Cgroups v2 have been around for a while and many users have fully adopted them,
so they never use cgroups v1 features and functionality. Yet they have to "pay"
for the cgroup v1 support anyway:
1) the kernel binary contains useless cgroup v1 code,
2) some common structures like task_struct and mem_cgroup have never used
cgroup v1-specific members,
3) some code paths have additional checks which are not needed.
Cgroup v1's memory controller has a number of features that are not supported
by cgroup v2 and their implementation is pretty much self contained.
Most notably, these features are: soft limit reclaim, oom handling in userspace,
complicated event notification system, charge migration.
Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
intervened with generic and cgroup v2-specific code. It's a burden on
developers and maintainers.
This patchset aims to solve these problems by:
1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
mm/internal.h header
3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
5) putting unused struct memory_cgroup and task_struct members under
CONFIG_MEMCG_V1 as well.
This is an RFC version, which is not 100% polished yet, so but it would be great
to discuss and agree on the overall approach.
Some open questions, opinions are appreciated:
1) I consider renaming non-static functions in memcontrol-v1.c to have
mem_cgroup_v1_ prefix. Is this a good idea?
2) Do we want to extend it beyond the memory controller? Should
3) Is it better to use a new include/linux/memcontrol-v1.h instead of
mm/internal.h? Or mm/memcontrol-v1.h.
diffstat:
include/linux/memcontrol.h | 165 ++++---
include/linux/sched.h | 5 +-
init/Kconfig | 7 +
mm/Makefile | 2 +
mm/internal.h | 124 +++++
mm/memcontrol-v1.c | 2941 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
mm/memcontrol.c | 4121 ++++++++++++++++++++++---------------------------------------------------------------------------------------------------------------------------------
7 files changed, 3765 insertions(+), 3600 deletions(-)
Suggested-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Roman Gushchin <[email protected]>
Roman Gushchin (9):
mm: memcg: introduce memcontrol-v1.c
mm: memcg: move soft limit reclaim code to memcontrol-v1.c
mm: memcg: move charge migration code to memcontrol-v1.c
mm: memcg: move legacy memcg event code into memcontrol-v1.c
mm: memcg: move cgroup v1 interface files to memcontrol-v1.c
mm: memcg: move cgroup v1 oom handling code into memcontrol-v1.c
mm: memcg: put cgroup v1-specific code under a config option
mm: memcg: put corresponding struct mem_cgroup members under
CONFIG_MEMCG_V1
mm: memcg: put cgroup v1-related members of task_struct under config
option
include/linux/memcontrol.h | 165 +-
include/linux/sched.h | 5 +-
init/Kconfig | 7 +
mm/Makefile | 2 +
mm/internal.h | 124 ++
mm/memcontrol-v1.c | 2941 +++++++++++++++++++++++++
mm/memcontrol.c | 4121 ++++++------------------------------
7 files changed, 3765 insertions(+), 3600 deletions(-)
create mode 100644 mm/memcontrol-v1.c
--
2.43.2
This patch introduces the mm/memcontrol-v1.c source file which will be used for
all legacy (cgroup v1) memory cgroup code.
As of now, let's compile it if CONFIG_MEMCG is set, similar to mm/memcontrol.c.
Later on it can be switched to use a separate config option, so that the legacy
code won't be compiled if not required.
Signed-off-by: Roman Gushchin <[email protected]>
---
mm/Makefile | 3 ++-
mm/memcontrol-v1.c | 2 ++
2 files changed, 4 insertions(+), 1 deletion(-)
create mode 100644 mm/memcontrol-v1.c
diff --git a/mm/Makefile b/mm/Makefile
index 25da205becdd..c717a3ee612e 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -26,6 +26,7 @@ KCOV_INSTRUMENT_page_alloc.o := n
KCOV_INSTRUMENT_debug-pagealloc.o := n
KCOV_INSTRUMENT_kmemleak.o := n
KCOV_INSTRUMENT_memcontrol.o := n
+KCOV_INSTRUMENT_memcontrol-v1.o := n
KCOV_INSTRUMENT_mmzone.o := n
KCOV_INSTRUMENT_vmstat.o := n
KCOV_INSTRUMENT_failslab.o := n
@@ -95,7 +96,7 @@ obj-$(CONFIG_NUMA) += memory-tiers.o
obj-$(CONFIG_DEVICE_MIGRATION) += migrate_device.o
obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o
obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
-obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
+obj-$(CONFIG_MEMCG) += memcontrol.o memcontrol-v1.o vmpressure.o
ifdef CONFIG_SWAP
obj-$(CONFIG_MEMCG) += swap_cgroup.o
endif
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
new file mode 100644
index 000000000000..4bc66fc244c0
--- /dev/null
+++ b/mm/memcontrol-v1.c
@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
--
2.43.2
From: Roman Gushchin <[email protected]>
Soft limits are cgroup v1-specific and are not supported
by cgroup v2, so let's move the corresponding code into
memcontrol-v1.c.
Aside from simple moving the code, this commits introduces
a trivial mem_cgroup_soft_limit_reset() function to reset
soft limits and also moves the global soft limit tree initialization
code into a new mem_cgroup_v1_init() function.
It also moves corresponding definitions in include/memcontrol.h
into a separate section at the end of the file. The idea is to group
all memcg v1-specific definitions in one place and provide trivial
alternatives later on to support compiling the kernel without
support of the legacy memory controller.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 28 +--
mm/internal.h | 5 +
mm/memcontrol-v1.c | 347 +++++++++++++++++++++++++++++++++++++
mm/memcontrol.c | 336 +----------------------------------
4 files changed, 372 insertions(+), 344 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 030d34e9d117..f77b6fbf38fd 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1120,10 +1120,6 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
void split_page_memcg(struct page *head, int old_order, int new_order);
-unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
- gfp_t gfp_mask,
- unsigned long *total_scanned);
-
#else /* CONFIG_MEMCG */
#define MEM_CGROUP_ID_SHIFT 0
@@ -1575,13 +1571,6 @@ static inline void split_page_memcg(struct page *head, int old_order, int new_or
{
}
-static inline
-unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
- gfp_t gfp_mask,
- unsigned long *total_scanned)
-{
- return 0;
-}
#endif /* CONFIG_MEMCG */
/*
@@ -1932,4 +1921,21 @@ static inline bool mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg)
}
#endif
+/* Cgroup v1-specific definitions */
+
+#ifdef CONFIG_MEMCG
+unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned);
+#else /* CONFIG_MEMCG */
+
+static inline
+unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
+{
+ return 0;
+}
+#endif /* CONFIG_MEMCG */
+
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/internal.h b/mm/internal.h
index b2c75b12014e..19e96d626977 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1521,4 +1521,9 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry,
void workingset_update_node(struct xa_node *node);
extern struct list_lru shadow_nodes;
+/* Memory cgroups v1-specific definitions */
+void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid);
+void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg);
+void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg);
+
#endif /* __MM_INTERNAL_H */
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 4bc66fc244c0..951e1c1189cc 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1,2 +1,349 @@
// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
+
+#include "internal.h"
+
+/*
+ * Cgroups above their limits are maintained in a RB-Tree, independent of
+ * their hierarchy representation
+ */
+
+struct mem_cgroup_tree_per_node {
+ struct rb_root rb_root;
+ struct rb_node *rb_rightmost;
+ spinlock_t lock;
+};
+
+struct mem_cgroup_tree {
+ struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
+};
+
+static struct mem_cgroup_tree soft_limit_tree __read_mostly;
+
+/*
+ * Maximum loops in mem_cgroup_soft_reclaim(), used for soft
+ * limit reclaim to prevent infinite loops, if they ever occur.
+ */
+#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100
+#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2
+
+static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
+ struct mem_cgroup_tree_per_node *mctz,
+ unsigned long new_usage_in_excess)
+{
+ struct rb_node **p = &mctz->rb_root.rb_node;
+ struct rb_node *parent = NULL;
+ struct mem_cgroup_per_node *mz_node;
+ bool rightmost = true;
+
+ if (mz->on_tree)
+ return;
+
+ mz->usage_in_excess = new_usage_in_excess;
+ if (!mz->usage_in_excess)
+ return;
+ while (*p) {
+ parent = *p;
+ mz_node = rb_entry(parent, struct mem_cgroup_per_node,
+ tree_node);
+ if (mz->usage_in_excess < mz_node->usage_in_excess) {
+ p = &(*p)->rb_left;
+ rightmost = false;
+ } else {
+ p = &(*p)->rb_right;
+ }
+ }
+
+ if (rightmost)
+ mctz->rb_rightmost = &mz->tree_node;
+
+ rb_link_node(&mz->tree_node, parent, p);
+ rb_insert_color(&mz->tree_node, &mctz->rb_root);
+ mz->on_tree = true;
+}
+
+static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
+ struct mem_cgroup_tree_per_node *mctz)
+{
+ if (!mz->on_tree)
+ return;
+
+ if (&mz->tree_node == mctz->rb_rightmost)
+ mctz->rb_rightmost = rb_prev(&mz->tree_node);
+
+ rb_erase(&mz->tree_node, &mctz->rb_root);
+ mz->on_tree = false;
+}
+
+static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
+ struct mem_cgroup_tree_per_node *mctz)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&mctz->lock, flags);
+ __mem_cgroup_remove_exceeded(mz, mctz);
+ spin_unlock_irqrestore(&mctz->lock, flags);
+}
+
+static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
+{
+ unsigned long nr_pages = page_counter_read(&memcg->memory);
+ unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
+ unsigned long excess = 0;
+
+ if (nr_pages > soft_limit)
+ excess = nr_pages - soft_limit;
+
+ return excess;
+}
+
+void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
+{
+ unsigned long excess;
+ struct mem_cgroup_per_node *mz;
+ struct mem_cgroup_tree_per_node *mctz;
+
+ if (lru_gen_enabled()) {
+ if (soft_limit_excess(memcg))
+ lru_gen_soft_reclaim(memcg, nid);
+ return;
+ }
+
+ mctz = soft_limit_tree.rb_tree_per_node[nid];
+ if (!mctz)
+ return;
+ /*
+ * Necessary to update all ancestors when hierarchy is used.
+ * because their event counter is not touched.
+ */
+ for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+ mz = memcg->nodeinfo[nid];
+ excess = soft_limit_excess(memcg);
+ /*
+ * We have to update the tree if mz is on RB-tree or
+ * mem is over its softlimit.
+ */
+ if (excess || mz->on_tree) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&mctz->lock, flags);
+ /* if on-tree, remove it */
+ if (mz->on_tree)
+ __mem_cgroup_remove_exceeded(mz, mctz);
+ /*
+ * Insert again. mz->usage_in_excess will be updated.
+ * If excess is 0, no tree ops.
+ */
+ __mem_cgroup_insert_exceeded(mz, mctz, excess);
+ spin_unlock_irqrestore(&mctz->lock, flags);
+ }
+ }
+}
+
+void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_tree_per_node *mctz;
+ struct mem_cgroup_per_node *mz;
+ int nid;
+
+ for_each_node(nid) {
+ mz = memcg->nodeinfo[nid];
+ mctz = soft_limit_tree.rb_tree_per_node[nid];
+ if (mctz)
+ mem_cgroup_remove_exceeded(mz, mctz);
+ }
+}
+
+static struct mem_cgroup_per_node *
+__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
+{
+ struct mem_cgroup_per_node *mz;
+
+retry:
+ mz = NULL;
+ if (!mctz->rb_rightmost)
+ goto done; /* Nothing to reclaim from */
+
+ mz = rb_entry(mctz->rb_rightmost,
+ struct mem_cgroup_per_node, tree_node);
+ /*
+ * Remove the node now but someone else can add it back,
+ * we will to add it back at the end of reclaim to its correct
+ * position in the tree.
+ */
+ __mem_cgroup_remove_exceeded(mz, mctz);
+ if (!soft_limit_excess(mz->memcg) ||
+ !css_tryget(&mz->memcg->css))
+ goto retry;
+done:
+ return mz;
+}
+
+static struct mem_cgroup_per_node *
+mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
+{
+ struct mem_cgroup_per_node *mz;
+
+ spin_lock_irq(&mctz->lock);
+ mz = __mem_cgroup_largest_soft_limit_node(mctz);
+ spin_unlock_irq(&mctz->lock);
+ return mz;
+}
+
+static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
+ pg_data_t *pgdat,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
+{
+ struct mem_cgroup *victim = NULL;
+ int total = 0;
+ int loop = 0;
+ unsigned long excess;
+ unsigned long nr_scanned;
+ struct mem_cgroup_reclaim_cookie reclaim = {
+ .pgdat = pgdat,
+ };
+
+ excess = soft_limit_excess(root_memcg);
+
+ while (1) {
+ victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
+ if (!victim) {
+ loop++;
+ if (loop >= 2) {
+ /*
+ * If we have not been able to reclaim
+ * anything, it might because there are
+ * no reclaimable pages under this hierarchy
+ */
+ if (!total)
+ break;
+ /*
+ * We want to do more targeted reclaim.
+ * excess >> 2 is not to excessive so as to
+ * reclaim too much, nor too less that we keep
+ * coming back to reclaim from this cgroup
+ */
+ if (total >= (excess >> 2) ||
+ (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
+ break;
+ }
+ continue;
+ }
+ total += mem_cgroup_shrink_node(victim, gfp_mask, false,
+ pgdat, &nr_scanned);
+ *total_scanned += nr_scanned;
+ if (!soft_limit_excess(root_memcg))
+ break;
+ }
+ mem_cgroup_iter_break(root_memcg, victim);
+ return total;
+}
+
+unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
+{
+ unsigned long nr_reclaimed = 0;
+ struct mem_cgroup_per_node *mz, *next_mz = NULL;
+ unsigned long reclaimed;
+ int loop = 0;
+ struct mem_cgroup_tree_per_node *mctz;
+ unsigned long excess;
+
+ if (lru_gen_enabled())
+ return 0;
+
+ if (order > 0)
+ return 0;
+
+ mctz = soft_limit_tree.rb_tree_per_node[pgdat->node_id];
+
+ /*
+ * Do not even bother to check the largest node if the root
+ * is empty. Do it lockless to prevent lock bouncing. Races
+ * are acceptable as soft limit is best effort anyway.
+ */
+ if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
+ return 0;
+
+ /*
+ * This loop can run a while, specially if mem_cgroup's continuously
+ * keep exceeding their soft limit and putting the system under
+ * pressure
+ */
+ do {
+ if (next_mz)
+ mz = next_mz;
+ else
+ mz = mem_cgroup_largest_soft_limit_node(mctz);
+ if (!mz)
+ break;
+
+ reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
+ gfp_mask, total_scanned);
+ nr_reclaimed += reclaimed;
+ spin_lock_irq(&mctz->lock);
+
+ /*
+ * If we failed to reclaim anything from this memory cgroup
+ * it is time to move on to the next cgroup
+ */
+ next_mz = NULL;
+ if (!reclaimed)
+ next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
+
+ excess = soft_limit_excess(mz->memcg);
+ /*
+ * One school of thought says that we should not add
+ * back the node to the tree if reclaim returns 0.
+ * But our reclaim could return 0, simply because due
+ * to priority we are exposing a smaller subset of
+ * memory to reclaim from. Consider this as a longer
+ * term TODO.
+ */
+ /* If excess == 0, no tree ops */
+ __mem_cgroup_insert_exceeded(mz, mctz, excess);
+ spin_unlock_irq(&mctz->lock);
+ css_put(&mz->memcg->css);
+ loop++;
+ /*
+ * Could not reclaim anything and there are no more
+ * mem cgroups to try or we seem to be looping without
+ * reclaiming anything.
+ */
+ if (!nr_reclaimed &&
+ (next_mz == NULL ||
+ loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
+ break;
+ } while (!nr_reclaimed);
+ if (next_mz)
+ css_put(&next_mz->memcg->css);
+ return nr_reclaimed;
+}
+
+void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg)
+{
+ WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
+}
+
+static int __init mem_cgroup_v1_init(void)
+{
+ int node;
+
+ for_each_node(node) {
+ struct mem_cgroup_tree_per_node *rtpn;
+
+ rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, node);
+
+ rtpn->rb_root = RB_ROOT;
+ rtpn->rb_rightmost = NULL;
+ spin_lock_init(&rtpn->lock);
+ soft_limit_tree.rb_tree_per_node[node] = rtpn;
+ }
+
+ return 0;
+}
+subsys_initcall(mem_cgroup_v1_init);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5d4da23264fa..0c2196f42631 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -108,23 +108,6 @@ static bool do_memsw_account(void)
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
-/*
- * Cgroups above their limits are maintained in a RB-Tree, independent of
- * their hierarchy representation
- */
-
-struct mem_cgroup_tree_per_node {
- struct rb_root rb_root;
- struct rb_node *rb_rightmost;
- spinlock_t lock;
-};
-
-struct mem_cgroup_tree {
- struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
-};
-
-static struct mem_cgroup_tree soft_limit_tree __read_mostly;
-
/* for OOM */
struct mem_cgroup_eventfd_list {
struct list_head list;
@@ -199,13 +182,6 @@ static struct move_charge_struct {
.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
-/*
- * Maximum loops in mem_cgroup_soft_reclaim(), used for soft
- * limit reclaim to prevent infinite loops, if they ever occur.
- */
-#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100
-#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2
-
/* for encoding cft->private value on file */
enum res_type {
_MEM,
@@ -413,169 +389,6 @@ ino_t page_cgroup_ino(struct page *page)
return ino;
}
-static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
- struct mem_cgroup_tree_per_node *mctz,
- unsigned long new_usage_in_excess)
-{
- struct rb_node **p = &mctz->rb_root.rb_node;
- struct rb_node *parent = NULL;
- struct mem_cgroup_per_node *mz_node;
- bool rightmost = true;
-
- if (mz->on_tree)
- return;
-
- mz->usage_in_excess = new_usage_in_excess;
- if (!mz->usage_in_excess)
- return;
- while (*p) {
- parent = *p;
- mz_node = rb_entry(parent, struct mem_cgroup_per_node,
- tree_node);
- if (mz->usage_in_excess < mz_node->usage_in_excess) {
- p = &(*p)->rb_left;
- rightmost = false;
- } else {
- p = &(*p)->rb_right;
- }
- }
-
- if (rightmost)
- mctz->rb_rightmost = &mz->tree_node;
-
- rb_link_node(&mz->tree_node, parent, p);
- rb_insert_color(&mz->tree_node, &mctz->rb_root);
- mz->on_tree = true;
-}
-
-static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
- struct mem_cgroup_tree_per_node *mctz)
-{
- if (!mz->on_tree)
- return;
-
- if (&mz->tree_node == mctz->rb_rightmost)
- mctz->rb_rightmost = rb_prev(&mz->tree_node);
-
- rb_erase(&mz->tree_node, &mctz->rb_root);
- mz->on_tree = false;
-}
-
-static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
- struct mem_cgroup_tree_per_node *mctz)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&mctz->lock, flags);
- __mem_cgroup_remove_exceeded(mz, mctz);
- spin_unlock_irqrestore(&mctz->lock, flags);
-}
-
-static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
-{
- unsigned long nr_pages = page_counter_read(&memcg->memory);
- unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
- unsigned long excess = 0;
-
- if (nr_pages > soft_limit)
- excess = nr_pages - soft_limit;
-
- return excess;
-}
-
-static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
-{
- unsigned long excess;
- struct mem_cgroup_per_node *mz;
- struct mem_cgroup_tree_per_node *mctz;
-
- if (lru_gen_enabled()) {
- if (soft_limit_excess(memcg))
- lru_gen_soft_reclaim(memcg, nid);
- return;
- }
-
- mctz = soft_limit_tree.rb_tree_per_node[nid];
- if (!mctz)
- return;
- /*
- * Necessary to update all ancestors when hierarchy is used.
- * because their event counter is not touched.
- */
- for (; memcg; memcg = parent_mem_cgroup(memcg)) {
- mz = memcg->nodeinfo[nid];
- excess = soft_limit_excess(memcg);
- /*
- * We have to update the tree if mz is on RB-tree or
- * mem is over its softlimit.
- */
- if (excess || mz->on_tree) {
- unsigned long flags;
-
- spin_lock_irqsave(&mctz->lock, flags);
- /* if on-tree, remove it */
- if (mz->on_tree)
- __mem_cgroup_remove_exceeded(mz, mctz);
- /*
- * Insert again. mz->usage_in_excess will be updated.
- * If excess is 0, no tree ops.
- */
- __mem_cgroup_insert_exceeded(mz, mctz, excess);
- spin_unlock_irqrestore(&mctz->lock, flags);
- }
- }
-}
-
-static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
-{
- struct mem_cgroup_tree_per_node *mctz;
- struct mem_cgroup_per_node *mz;
- int nid;
-
- for_each_node(nid) {
- mz = memcg->nodeinfo[nid];
- mctz = soft_limit_tree.rb_tree_per_node[nid];
- if (mctz)
- mem_cgroup_remove_exceeded(mz, mctz);
- }
-}
-
-static struct mem_cgroup_per_node *
-__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
-{
- struct mem_cgroup_per_node *mz;
-
-retry:
- mz = NULL;
- if (!mctz->rb_rightmost)
- goto done; /* Nothing to reclaim from */
-
- mz = rb_entry(mctz->rb_rightmost,
- struct mem_cgroup_per_node, tree_node);
- /*
- * Remove the node now but someone else can add it back,
- * we will to add it back at the end of reclaim to its correct
- * position in the tree.
- */
- __mem_cgroup_remove_exceeded(mz, mctz);
- if (!soft_limit_excess(mz->memcg) ||
- !css_tryget(&mz->memcg->css))
- goto retry;
-done:
- return mz;
-}
-
-static struct mem_cgroup_per_node *
-mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
-{
- struct mem_cgroup_per_node *mz;
-
- spin_lock_irq(&mctz->lock);
- mz = __mem_cgroup_largest_soft_limit_node(mctz);
- spin_unlock_irq(&mctz->lock);
- return mz;
-}
-
/* Subset of node_stat_item for memcg stats */
static const unsigned int memcg_node_stat_items[] = {
NR_INACTIVE_ANON,
@@ -1983,56 +1796,6 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
return ret;
}
-static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
- pg_data_t *pgdat,
- gfp_t gfp_mask,
- unsigned long *total_scanned)
-{
- struct mem_cgroup *victim = NULL;
- int total = 0;
- int loop = 0;
- unsigned long excess;
- unsigned long nr_scanned;
- struct mem_cgroup_reclaim_cookie reclaim = {
- .pgdat = pgdat,
- };
-
- excess = soft_limit_excess(root_memcg);
-
- while (1) {
- victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
- if (!victim) {
- loop++;
- if (loop >= 2) {
- /*
- * If we have not been able to reclaim
- * anything, it might because there are
- * no reclaimable pages under this hierarchy
- */
- if (!total)
- break;
- /*
- * We want to do more targeted reclaim.
- * excess >> 2 is not to excessive so as to
- * reclaim too much, nor too less that we keep
- * coming back to reclaim from this cgroup
- */
- if (total >= (excess >> 2) ||
- (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
- break;
- }
- continue;
- }
- total += mem_cgroup_shrink_node(victim, gfp_mask, false,
- pgdat, &nr_scanned);
- *total_scanned += nr_scanned;
- if (!soft_limit_excess(root_memcg))
- break;
- }
- mem_cgroup_iter_break(root_memcg, victim);
- return total;
-}
-
#ifdef CONFIG_LOCKDEP
static struct lockdep_map memcg_oom_lock_dep_map = {
.name = "memcg_oom_lock",
@@ -3932,88 +3695,6 @@ static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
return ret;
}
-unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
- gfp_t gfp_mask,
- unsigned long *total_scanned)
-{
- unsigned long nr_reclaimed = 0;
- struct mem_cgroup_per_node *mz, *next_mz = NULL;
- unsigned long reclaimed;
- int loop = 0;
- struct mem_cgroup_tree_per_node *mctz;
- unsigned long excess;
-
- if (lru_gen_enabled())
- return 0;
-
- if (order > 0)
- return 0;
-
- mctz = soft_limit_tree.rb_tree_per_node[pgdat->node_id];
-
- /*
- * Do not even bother to check the largest node if the root
- * is empty. Do it lockless to prevent lock bouncing. Races
- * are acceptable as soft limit is best effort anyway.
- */
- if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
- return 0;
-
- /*
- * This loop can run a while, specially if mem_cgroup's continuously
- * keep exceeding their soft limit and putting the system under
- * pressure
- */
- do {
- if (next_mz)
- mz = next_mz;
- else
- mz = mem_cgroup_largest_soft_limit_node(mctz);
- if (!mz)
- break;
-
- reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
- gfp_mask, total_scanned);
- nr_reclaimed += reclaimed;
- spin_lock_irq(&mctz->lock);
-
- /*
- * If we failed to reclaim anything from this memory cgroup
- * it is time to move on to the next cgroup
- */
- next_mz = NULL;
- if (!reclaimed)
- next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
-
- excess = soft_limit_excess(mz->memcg);
- /*
- * One school of thought says that we should not add
- * back the node to the tree if reclaim returns 0.
- * But our reclaim could return 0, simply because due
- * to priority we are exposing a smaller subset of
- * memory to reclaim from. Consider this as a longer
- * term TODO.
- */
- /* If excess == 0, no tree ops */
- __mem_cgroup_insert_exceeded(mz, mctz, excess);
- spin_unlock_irq(&mctz->lock);
- css_put(&mz->memcg->css);
- loop++;
- /*
- * Could not reclaim anything and there are no more
- * mem cgroups to try or we seem to be looping without
- * reclaiming anything.
- */
- if (!nr_reclaimed &&
- (next_mz == NULL ||
- loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
- break;
- } while (!nr_reclaimed);
- if (next_mz)
- css_put(&next_mz->memcg->css);
- return nr_reclaimed;
-}
-
/*
* Reclaims as many pages from the given memcg as possible.
*
@@ -5791,7 +5472,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
return ERR_CAST(memcg);
page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
- WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
+ mem_cgroup_soft_limit_reset(memcg);
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
memcg->zswap_max = PAGE_COUNTER_MAX;
WRITE_ONCE(memcg->zswap_writeback,
@@ -5964,7 +5645,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
- WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
+ mem_cgroup_soft_limit_reset(memcg);
page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
memcg_wb_domain_size_changed(memcg);
}
@@ -7992,7 +7673,7 @@ __setup("cgroup.memory=", cgroup_memory);
*/
static int __init mem_cgroup_init(void)
{
- int cpu, node;
+ int cpu;
/*
* Currently s32 type (can refer to struct batched_lruvec_stat) is
@@ -8009,17 +7690,6 @@ static int __init mem_cgroup_init(void)
INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
drain_local_stock);
- for_each_node(node) {
- struct mem_cgroup_tree_per_node *rtpn;
-
- rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, node);
-
- rtpn->rb_root = RB_ROOT;
- rtpn->rb_rightmost = NULL;
- spin_lock_init(&rtpn->lock);
- soft_limit_tree.rb_tree_per_node[node] = rtpn;
- }
-
return 0;
}
subsys_initcall(mem_cgroup_init);
--
2.43.2
Cgroup v1's memory controller contains a pretty complicated
event notifications mechanism which is not used on cgroup v2.
Let's move the corresponding code into memcontrol-v1.c.
Please, note, that mem_cgroup_event_ratelimit() remains in
memcontrol.c, otherwise it would require exporting too many
details on memcg stats outside of memcontrol.c.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 12 -
mm/internal.h | 55 ++-
mm/memcontrol-v1.c | 653 +++++++++++++++++++++++++++++++++++
mm/memcontrol.c | 687 +------------------------------------
4 files changed, 712 insertions(+), 695 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 60355f3cb67c..fc4aaa73aa5e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -69,18 +69,6 @@ struct mem_cgroup_id {
refcount_t ref;
};
-/*
- * Per memcg event counter is incremented at every pagein/pageout. With THP,
- * it will be incremented by the number of pages. This counter is used
- * to trigger some periodic events. This is straightforward and better
- * than using jiffies etc. to handle periodic memcg event.
- */
-enum mem_cgroup_events_target {
- MEM_CGROUP_TARGET_THRESH,
- MEM_CGROUP_TARGET_SOFTLIMIT,
- MEM_CGROUP_NTARGETS,
-};
-
struct memcg_vmstats_percpu;
struct memcg_vmstats;
struct lruvec_stats_percpu;
diff --git a/mm/internal.h b/mm/internal.h
index 9ffd48375ae5..79104cfc08a9 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1521,6 +1521,29 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry,
void workingset_update_node(struct xa_node *node);
extern struct list_lru shadow_nodes;
+#ifdef CONFIG_CGROUPS
+/* Whether legacy memory+swap accounting is active */
+static inline bool do_memsw_account(void)
+{
+ return !cgroup_subsys_on_dfl(memory_cgrp_subsys);
+}
+#endif
+
+/*
+ * Iteration constructs for visiting all cgroups (under a tree). If
+ * loops are exited prematurely (break), mem_cgroup_iter_break() must
+ * be used for reference counting.
+ */
+#define for_each_mem_cgroup_tree(iter, root) \
+ for (iter = mem_cgroup_iter(root, NULL, NULL); \
+ iter != NULL; \
+ iter = mem_cgroup_iter(root, iter, NULL))
+
+#define for_each_mem_cgroup(iter) \
+ for (iter = mem_cgroup_iter(NULL, NULL, NULL); \
+ iter != NULL; \
+ iter = mem_cgroup_iter(NULL, iter, NULL))
+
/* Memcontrol definitions used by memory cgroups v1-specific code */
int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages);
@@ -1535,11 +1558,27 @@ static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
}
void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages);
-void memcg_check_events(struct mem_cgroup *memcg, int nid);
void memcg_oom_recover(struct mem_cgroup *memcg);
void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n);
void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n);
+unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap);
+
+/*
+ * Per memcg event counter is incremented at every pagein/pageout. With THP,
+ * it will be incremented by the number of pages. This counter is used
+ * to trigger some periodic events. This is straightforward and better
+ * than using jiffies etc. to handle periodic memcg event.
+ */
+enum mem_cgroup_events_target {
+ MEM_CGROUP_TARGET_THRESH,
+ MEM_CGROUP_TARGET_SOFTLIMIT,
+ MEM_CGROUP_NTARGETS,
+};
+
+bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+ enum mem_cgroup_events_target target);
+
/* Memory cgroups v1-specific definitions */
void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid);
void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg);
@@ -1557,4 +1596,18 @@ void mem_cgroup_cancel_attach(struct cgroup_taskset *tset);
bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg);
void mem_cgroup_move_task(void);
+/* for encoding cft->private value on file */
+enum res_type {
+ _MEM,
+ _MEMSWAP,
+ _KMEM,
+ _TCP,
+};
+
+void memcg_check_events(struct mem_cgroup *memcg, int nid);
+void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
+ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off);
+void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg);
+
#endif /* __MM_INTERNAL_H */
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index b39bfa4a8de6..5bf0b62cd7b5 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -4,8 +4,12 @@
#include <linux/pagewalk.h>
#include <linux/backing-dev.h>
#include <linux/swap.h>
+#include <linux/eventfd.h>
+#include <linux/poll.h>
+#include <linux/sort.h>
#include <linux/mm_inline.h>
#include <linux/swap_cgroup.h>
+#include <linux/file.h>
#include "internal.h"
#include "swap.h"
@@ -59,6 +63,54 @@ static struct move_charge_struct {
.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
+/*
+ * cgroup_event represents events which userspace want to receive.
+ */
+struct mem_cgroup_event {
+ /*
+ * memcg which the event belongs to.
+ */
+ struct mem_cgroup *memcg;
+ /*
+ * eventfd to signal userspace about the event.
+ */
+ struct eventfd_ctx *eventfd;
+ /*
+ * Each of these stored in a list by the cgroup.
+ */
+ struct list_head list;
+ /*
+ * register_event() callback will be used to add new userspace
+ * waiter for changes related to this event. Use eventfd_signal()
+ * on eventfd to send notification to userspace.
+ */
+ int (*register_event)(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args);
+ /*
+ * unregister_event() callback will be called when userspace closes
+ * the eventfd or on cgroup removing. This callback must be set,
+ * if you want provide notification functionality.
+ */
+ void (*unregister_event)(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd);
+ /*
+ * All fields below needed to unregister event when
+ * userspace closes eventfd.
+ */
+ poll_table pt;
+ wait_queue_head_t *wqh;
+ wait_queue_entry_t wait;
+ struct work_struct remove;
+};
+
+/* for OOM */
+struct mem_cgroup_eventfd_list {
+ struct list_head list;
+ struct eventfd_ctx *eventfd;
+};
+
+extern spinlock_t memcg_oom_lock;
+
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz,
unsigned long new_usage_in_excess)
@@ -1310,6 +1362,607 @@ void mem_cgroup_move_task(void)
}
#endif
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+ struct mem_cgroup_threshold_ary *t;
+ unsigned long usage;
+ int i;
+
+ rcu_read_lock();
+ if (!swap)
+ t = rcu_dereference(memcg->thresholds.primary);
+ else
+ t = rcu_dereference(memcg->memsw_thresholds.primary);
+
+ if (!t)
+ goto unlock;
+
+ usage = mem_cgroup_usage(memcg, swap);
+
+ /*
+ * current_threshold points to threshold just below or equal to usage.
+ * If it's not true, a threshold was crossed after last
+ * call of __mem_cgroup_threshold().
+ */
+ i = t->current_threshold;
+
+ /*
+ * Iterate backward over array of thresholds starting from
+ * current_threshold and check if a threshold is crossed.
+ * If none of thresholds below usage is crossed, we read
+ * only one element of the array here.
+ */
+ for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
+ eventfd_signal(t->entries[i].eventfd);
+
+ /* i = current_threshold + 1 */
+ i++;
+
+ /*
+ * Iterate forward over array of thresholds starting from
+ * current_threshold+1 and check if a threshold is crossed.
+ * If none of thresholds above usage is crossed, we read
+ * only one element of the array here.
+ */
+ for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
+ eventfd_signal(t->entries[i].eventfd);
+
+ /* Update current_threshold */
+ t->current_threshold = i - 1;
+unlock:
+ rcu_read_unlock();
+}
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg)
+{
+ while (memcg) {
+ __mem_cgroup_threshold(memcg, false);
+ if (do_memsw_account())
+ __mem_cgroup_threshold(memcg, true);
+
+ memcg = parent_mem_cgroup(memcg);
+ }
+}
+
+/*
+ * Check events in order.
+ *
+ */
+void memcg_check_events(struct mem_cgroup *memcg, int nid)
+{
+ if (IS_ENABLED(CONFIG_PREEMPT_RT))
+ return;
+
+ /* threshold event is triggered in finer grain than soft limit */
+ if (unlikely(mem_cgroup_event_ratelimit(memcg,
+ MEM_CGROUP_TARGET_THRESH))) {
+ bool do_softlimit;
+
+ do_softlimit = mem_cgroup_event_ratelimit(memcg,
+ MEM_CGROUP_TARGET_SOFTLIMIT);
+ mem_cgroup_threshold(memcg);
+ if (unlikely(do_softlimit))
+ mem_cgroup_update_tree(memcg, nid);
+ }
+}
+
+static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_eventfd_list *ev;
+
+ spin_lock(&memcg_oom_lock);
+
+ list_for_each_entry(ev, &memcg->oom_notify, list)
+ eventfd_signal(ev->eventfd);
+
+ spin_unlock(&memcg_oom_lock);
+ return 0;
+}
+
+void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ for_each_mem_cgroup_tree(iter, memcg)
+ mem_cgroup_oom_notify_cb(iter);
+}
+
+static int compare_thresholds(const void *a, const void *b)
+{
+ const struct mem_cgroup_threshold *_a = a;
+ const struct mem_cgroup_threshold *_b = b;
+
+ if (_a->threshold > _b->threshold)
+ return 1;
+
+ if (_a->threshold < _b->threshold)
+ return -1;
+
+ return 0;
+}
+
+static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args, enum res_type type)
+{
+ struct mem_cgroup_thresholds *thresholds;
+ struct mem_cgroup_threshold_ary *new;
+ unsigned long threshold;
+ unsigned long usage;
+ int i, size, ret;
+
+ ret = page_counter_memparse(args, "-1", &threshold);
+ if (ret)
+ return ret;
+
+ mutex_lock(&memcg->thresholds_lock);
+
+ if (type == _MEM) {
+ thresholds = &memcg->thresholds;
+ usage = mem_cgroup_usage(memcg, false);
+ } else if (type == _MEMSWAP) {
+ thresholds = &memcg->memsw_thresholds;
+ usage = mem_cgroup_usage(memcg, true);
+ } else
+ BUG();
+
+ /* Check if a threshold crossed before adding a new one */
+ if (thresholds->primary)
+ __mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+ size = thresholds->primary ? thresholds->primary->size + 1 : 1;
+
+ /* Allocate memory for new array of thresholds */
+ new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
+ if (!new) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ new->size = size;
+
+ /* Copy thresholds (if any) to new array */
+ if (thresholds->primary)
+ memcpy(new->entries, thresholds->primary->entries,
+ flex_array_size(new, entries, size - 1));
+
+ /* Add new threshold */
+ new->entries[size - 1].eventfd = eventfd;
+ new->entries[size - 1].threshold = threshold;
+
+ /* Sort thresholds. Registering of new threshold isn't time-critical */
+ sort(new->entries, size, sizeof(*new->entries),
+ compare_thresholds, NULL);
+
+ /* Find current threshold */
+ new->current_threshold = -1;
+ for (i = 0; i < size; i++) {
+ if (new->entries[i].threshold <= usage) {
+ /*
+ * new->current_threshold will not be used until
+ * rcu_assign_pointer(), so it's safe to increment
+ * it here.
+ */
+ ++new->current_threshold;
+ } else
+ break;
+ }
+
+ /* Free old spare buffer and save old primary buffer as spare */
+ kfree(thresholds->spare);
+ thresholds->spare = thresholds->primary;
+
+ rcu_assign_pointer(thresholds->primary, new);
+
+ /* To be sure that nobody uses thresholds */
+ synchronize_rcu();
+
+unlock:
+ mutex_unlock(&memcg->thresholds_lock);
+
+ return ret;
+}
+
+static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
+}
+
+static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
+}
+
+static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, enum res_type type)
+{
+ struct mem_cgroup_thresholds *thresholds;
+ struct mem_cgroup_threshold_ary *new;
+ unsigned long usage;
+ int i, j, size, entries;
+
+ mutex_lock(&memcg->thresholds_lock);
+
+ if (type == _MEM) {
+ thresholds = &memcg->thresholds;
+ usage = mem_cgroup_usage(memcg, false);
+ } else if (type == _MEMSWAP) {
+ thresholds = &memcg->memsw_thresholds;
+ usage = mem_cgroup_usage(memcg, true);
+ } else
+ BUG();
+
+ if (!thresholds->primary)
+ goto unlock;
+
+ /* Check if a threshold crossed before removing */
+ __mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+ /* Calculate new number of threshold */
+ size = entries = 0;
+ for (i = 0; i < thresholds->primary->size; i++) {
+ if (thresholds->primary->entries[i].eventfd != eventfd)
+ size++;
+ else
+ entries++;
+ }
+
+ new = thresholds->spare;
+
+ /* If no items related to eventfd have been cleared, nothing to do */
+ if (!entries)
+ goto unlock;
+
+ /* Set thresholds array to NULL if we don't have thresholds */
+ if (!size) {
+ kfree(new);
+ new = NULL;
+ goto swap_buffers;
+ }
+
+ new->size = size;
+
+ /* Copy thresholds and find current threshold */
+ new->current_threshold = -1;
+ for (i = 0, j = 0; i < thresholds->primary->size; i++) {
+ if (thresholds->primary->entries[i].eventfd == eventfd)
+ continue;
+
+ new->entries[j] = thresholds->primary->entries[i];
+ if (new->entries[j].threshold <= usage) {
+ /*
+ * new->current_threshold will not be used
+ * until rcu_assign_pointer(), so it's safe to increment
+ * it here.
+ */
+ ++new->current_threshold;
+ }
+ j++;
+ }
+
+swap_buffers:
+ /* Swap primary and spare array */
+ thresholds->spare = thresholds->primary;
+
+ rcu_assign_pointer(thresholds->primary, new);
+
+ /* To be sure that nobody uses thresholds */
+ synchronize_rcu();
+
+ /* If all events are unregistered, free the spare array */
+ if (!new) {
+ kfree(thresholds->spare);
+ thresholds->spare = NULL;
+ }
+unlock:
+ mutex_unlock(&memcg->thresholds_lock);
+}
+
+static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
+}
+
+static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
+}
+
+static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ struct mem_cgroup_eventfd_list *event;
+
+ event = kmalloc(sizeof(*event), GFP_KERNEL);
+ if (!event)
+ return -ENOMEM;
+
+ spin_lock(&memcg_oom_lock);
+
+ event->eventfd = eventfd;
+ list_add(&event->list, &memcg->oom_notify);
+
+ /* already in OOM ? */
+ if (memcg->under_oom)
+ eventfd_signal(eventfd);
+ spin_unlock(&memcg_oom_lock);
+
+ return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ struct mem_cgroup_eventfd_list *ev, *tmp;
+
+ spin_lock(&memcg_oom_lock);
+
+ list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
+ if (ev->eventfd == eventfd) {
+ list_del(&ev->list);
+ kfree(ev);
+ }
+ }
+
+ spin_unlock(&memcg_oom_lock);
+}
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * "cgroup.event_control" implementation.
+ *
+ * This is way over-engineered. It tries to support fully configurable
+ * events for each user. Such level of flexibility is completely
+ * unnecessary especially in the light of the planned unified hierarchy.
+ *
+ * Please deprecate this and replace with something simpler if at all
+ * possible.
+ */
+
+/*
+ * Unregister event and free resources.
+ *
+ * Gets called from workqueue.
+ */
+static void memcg_event_remove(struct work_struct *work)
+{
+ struct mem_cgroup_event *event =
+ container_of(work, struct mem_cgroup_event, remove);
+ struct mem_cgroup *memcg = event->memcg;
+
+ remove_wait_queue(event->wqh, &event->wait);
+
+ event->unregister_event(memcg, event->eventfd);
+
+ /* Notify userspace the event is going away. */
+ eventfd_signal(event->eventfd);
+
+ eventfd_ctx_put(event->eventfd);
+ kfree(event);
+ css_put(&memcg->css);
+}
+
+/*
+ * Gets called on EPOLLHUP on eventfd when user closes it.
+ *
+ * Called with wqh->lock held and interrupts disabled.
+ */
+static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode,
+ int sync, void *key)
+{
+ struct mem_cgroup_event *event =
+ container_of(wait, struct mem_cgroup_event, wait);
+ struct mem_cgroup *memcg = event->memcg;
+ __poll_t flags = key_to_poll(key);
+
+ if (flags & EPOLLHUP) {
+ /*
+ * If the event has been detached at cgroup removal, we
+ * can simply return knowing the other side will cleanup
+ * for us.
+ *
+ * We can't race against event freeing since the other
+ * side will require wqh->lock via remove_wait_queue(),
+ * which we hold.
+ */
+ spin_lock(&memcg->event_list_lock);
+ if (!list_empty(&event->list)) {
+ list_del_init(&event->list);
+ /*
+ * We are in atomic context, but cgroup_event_remove()
+ * may sleep, so we have to call it in workqueue.
+ */
+ schedule_work(&event->remove);
+ }
+ spin_unlock(&memcg->event_list_lock);
+ }
+
+ return 0;
+}
+
+static void memcg_event_ptable_queue_proc(struct file *file,
+ wait_queue_head_t *wqh, poll_table *pt)
+{
+ struct mem_cgroup_event *event =
+ container_of(pt, struct mem_cgroup_event, pt);
+
+ event->wqh = wqh;
+ add_wait_queue(wqh, &event->wait);
+}
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * Parse input and register new cgroup event handler.
+ *
+ * Input must be in format '<event_fd> <control_fd> <args>'.
+ * Interpretation of args is defined by control file implementation.
+ */
+ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup_subsys_state *css = of_css(of);
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+ struct mem_cgroup_event *event;
+ struct cgroup_subsys_state *cfile_css;
+ unsigned int efd, cfd;
+ struct fd efile;
+ struct fd cfile;
+ struct dentry *cdentry;
+ const char *name;
+ char *endp;
+ int ret;
+
+ if (IS_ENABLED(CONFIG_PREEMPT_RT))
+ return -EOPNOTSUPP;
+
+ buf = strstrip(buf);
+
+ efd = simple_strtoul(buf, &endp, 10);
+ if (*endp != ' ')
+ return -EINVAL;
+ buf = endp + 1;
+
+ cfd = simple_strtoul(buf, &endp, 10);
+ if ((*endp != ' ') && (*endp != '\0'))
+ return -EINVAL;
+ buf = endp + 1;
+
+ event = kzalloc(sizeof(*event), GFP_KERNEL);
+ if (!event)
+ return -ENOMEM;
+
+ event->memcg = memcg;
+ INIT_LIST_HEAD(&event->list);
+ init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
+ init_waitqueue_func_entry(&event->wait, memcg_event_wake);
+ INIT_WORK(&event->remove, memcg_event_remove);
+
+ efile = fdget(efd);
+ if (!efile.file) {
+ ret = -EBADF;
+ goto out_kfree;
+ }
+
+ event->eventfd = eventfd_ctx_fileget(efile.file);
+ if (IS_ERR(event->eventfd)) {
+ ret = PTR_ERR(event->eventfd);
+ goto out_put_efile;
+ }
+
+ cfile = fdget(cfd);
+ if (!cfile.file) {
+ ret = -EBADF;
+ goto out_put_eventfd;
+ }
+
+ /* the process need read permission on control file */
+ /* AV: shouldn't we check that it's been opened for read instead? */
+ ret = file_permission(cfile.file, MAY_READ);
+ if (ret < 0)
+ goto out_put_cfile;
+
+ /*
+ * The control file must be a regular cgroup1 file. As a regular cgroup
+ * file can't be renamed, it's safe to access its name afterwards.
+ */
+ cdentry = cfile.file->f_path.dentry;
+ if (cdentry->d_sb->s_type != &cgroup_fs_type || !d_is_reg(cdentry)) {
+ ret = -EINVAL;
+ goto out_put_cfile;
+ }
+
+ /*
+ * Determine the event callbacks and set them in @event. This used
+ * to be done via struct cftype but cgroup core no longer knows
+ * about these events. The following is crude but the whole thing
+ * is for compatibility anyway.
+ *
+ * DO NOT ADD NEW FILES.
+ */
+ name = cdentry->d_name.name;
+
+ if (!strcmp(name, "memory.usage_in_bytes")) {
+ event->register_event = mem_cgroup_usage_register_event;
+ event->unregister_event = mem_cgroup_usage_unregister_event;
+ } else if (!strcmp(name, "memory.oom_control")) {
+ event->register_event = mem_cgroup_oom_register_event;
+ event->unregister_event = mem_cgroup_oom_unregister_event;
+ } else if (!strcmp(name, "memory.pressure_level")) {
+ event->register_event = vmpressure_register_event;
+ event->unregister_event = vmpressure_unregister_event;
+ } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
+ event->register_event = memsw_cgroup_usage_register_event;
+ event->unregister_event = memsw_cgroup_usage_unregister_event;
+ } else {
+ ret = -EINVAL;
+ goto out_put_cfile;
+ }
+
+ /*
+ * Verify @cfile should belong to @css. Also, remaining events are
+ * automatically removed on cgroup destruction but the removal is
+ * asynchronous, so take an extra ref on @css.
+ */
+ cfile_css = css_tryget_online_from_dir(cdentry->d_parent,
+ &memory_cgrp_subsys);
+ ret = -EINVAL;
+ if (IS_ERR(cfile_css))
+ goto out_put_cfile;
+ if (cfile_css != css) {
+ css_put(cfile_css);
+ goto out_put_cfile;
+ }
+
+ ret = event->register_event(memcg, event->eventfd, buf);
+ if (ret)
+ goto out_put_css;
+
+ vfs_poll(efile.file, &event->pt);
+
+ spin_lock_irq(&memcg->event_list_lock);
+ list_add(&event->list, &memcg->event_list);
+ spin_unlock_irq(&memcg->event_list_lock);
+
+ fdput(cfile);
+ fdput(efile);
+
+ return nbytes;
+
+out_put_css:
+ css_put(css);
+out_put_cfile:
+ fdput(cfile);
+out_put_eventfd:
+ eventfd_ctx_put(event->eventfd);
+out_put_efile:
+ fdput(efile);
+out_kfree:
+ kfree(event);
+
+ return ret;
+}
+
+void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_event *event, *tmp;
+
+ /*
+ * Unregister events and notify userspace.
+ * Notify userspace about cgroup removing only after rmdir of cgroup
+ * directory to avoid race between userspace and kernelspace.
+ */
+ spin_lock_irq(&memcg->event_list_lock);
+ list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
+ list_del_init(&event->list);
+ schedule_work(&event->remove);
+ }
+ spin_unlock_irq(&memcg->event_list_lock);
+}
+
static int __init mem_cgroup_v1_init(void)
{
int node;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dc0a38d1107c..7c1a4ea0e9b5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -46,9 +46,6 @@
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/spinlock.h>
-#include <linux/eventfd.h>
-#include <linux/poll.h>
-#include <linux/sort.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/parser.h>
@@ -59,7 +56,6 @@
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/lockdep.h>
-#include <linux/file.h>
#include <linux/resume_user_mode.h>
#include <linux/psi.h>
#include <linux/seq_buf.h>
@@ -96,91 +92,13 @@ static bool cgroup_memory_nobpf __ro_after_init;
static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
#endif
-/* Whether legacy memory+swap accounting is active */
-static bool do_memsw_account(void)
-{
- return !cgroup_subsys_on_dfl(memory_cgrp_subsys);
-}
-
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
-/* for OOM */
-struct mem_cgroup_eventfd_list {
- struct list_head list;
- struct eventfd_ctx *eventfd;
-};
-
-/*
- * cgroup_event represents events which userspace want to receive.
- */
-struct mem_cgroup_event {
- /*
- * memcg which the event belongs to.
- */
- struct mem_cgroup *memcg;
- /*
- * eventfd to signal userspace about the event.
- */
- struct eventfd_ctx *eventfd;
- /*
- * Each of these stored in a list by the cgroup.
- */
- struct list_head list;
- /*
- * register_event() callback will be used to add new userspace
- * waiter for changes related to this event. Use eventfd_signal()
- * on eventfd to send notification to userspace.
- */
- int (*register_event)(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args);
- /*
- * unregister_event() callback will be called when userspace closes
- * the eventfd or on cgroup removing. This callback must be set,
- * if you want provide notification functionality.
- */
- void (*unregister_event)(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd);
- /*
- * All fields below needed to unregister event when
- * userspace closes eventfd.
- */
- poll_table pt;
- wait_queue_head_t *wqh;
- wait_queue_entry_t wait;
- struct work_struct remove;
-};
-
-static void mem_cgroup_threshold(struct mem_cgroup *memcg);
-static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
-
-/* for encoding cft->private value on file */
-enum res_type {
- _MEM,
- _MEMSWAP,
- _KMEM,
- _TCP,
-};
-
#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
-/*
- * Iteration constructs for visiting all cgroups (under a tree). If
- * loops are exited prematurely (break), mem_cgroup_iter_break() must
- * be used for reference counting.
- */
-#define for_each_mem_cgroup_tree(iter, root) \
- for (iter = mem_cgroup_iter(root, NULL, NULL); \
- iter != NULL; \
- iter = mem_cgroup_iter(root, iter, NULL))
-
-#define for_each_mem_cgroup(iter) \
- for (iter = mem_cgroup_iter(NULL, NULL, NULL); \
- iter != NULL; \
- iter = mem_cgroup_iter(NULL, iter, NULL))
-
static inline bool task_is_dying(void)
{
return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
@@ -942,8 +860,8 @@ void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages)
__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
}
-static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
- enum mem_cgroup_events_target target)
+bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+ enum mem_cgroup_events_target target)
{
unsigned long val, next;
@@ -967,28 +885,6 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
return false;
}
-/*
- * Check events in order.
- *
- */
-void memcg_check_events(struct mem_cgroup *memcg, int nid)
-{
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- return;
-
- /* threshold event is triggered in finer grain than soft limit */
- if (unlikely(mem_cgroup_event_ratelimit(memcg,
- MEM_CGROUP_TARGET_THRESH))) {
- bool do_softlimit;
-
- do_softlimit = mem_cgroup_event_ratelimit(memcg,
- MEM_CGROUP_TARGET_SOFTLIMIT);
- mem_cgroup_threshold(memcg);
- if (unlikely(do_softlimit))
- mem_cgroup_update_tree(memcg, nid);
- }
-}
-
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
{
/*
@@ -1728,7 +1624,7 @@ static struct lockdep_map memcg_oom_lock_dep_map = {
};
#endif
-static DEFINE_SPINLOCK(memcg_oom_lock);
+DEFINE_SPINLOCK(memcg_oom_lock);
/*
* Check OOM-Killer is already running under our hierarchy.
@@ -3550,7 +3446,7 @@ static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
return -EINVAL;
}
-static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
+unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
{
unsigned long val;
@@ -4051,331 +3947,6 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
return 0;
}
-static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
-{
- struct mem_cgroup_threshold_ary *t;
- unsigned long usage;
- int i;
-
- rcu_read_lock();
- if (!swap)
- t = rcu_dereference(memcg->thresholds.primary);
- else
- t = rcu_dereference(memcg->memsw_thresholds.primary);
-
- if (!t)
- goto unlock;
-
- usage = mem_cgroup_usage(memcg, swap);
-
- /*
- * current_threshold points to threshold just below or equal to usage.
- * If it's not true, a threshold was crossed after last
- * call of __mem_cgroup_threshold().
- */
- i = t->current_threshold;
-
- /*
- * Iterate backward over array of thresholds starting from
- * current_threshold and check if a threshold is crossed.
- * If none of thresholds below usage is crossed, we read
- * only one element of the array here.
- */
- for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
- eventfd_signal(t->entries[i].eventfd);
-
- /* i = current_threshold + 1 */
- i++;
-
- /*
- * Iterate forward over array of thresholds starting from
- * current_threshold+1 and check if a threshold is crossed.
- * If none of thresholds above usage is crossed, we read
- * only one element of the array here.
- */
- for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
- eventfd_signal(t->entries[i].eventfd);
-
- /* Update current_threshold */
- t->current_threshold = i - 1;
-unlock:
- rcu_read_unlock();
-}
-
-static void mem_cgroup_threshold(struct mem_cgroup *memcg)
-{
- while (memcg) {
- __mem_cgroup_threshold(memcg, false);
- if (do_memsw_account())
- __mem_cgroup_threshold(memcg, true);
-
- memcg = parent_mem_cgroup(memcg);
- }
-}
-
-static int compare_thresholds(const void *a, const void *b)
-{
- const struct mem_cgroup_threshold *_a = a;
- const struct mem_cgroup_threshold *_b = b;
-
- if (_a->threshold > _b->threshold)
- return 1;
-
- if (_a->threshold < _b->threshold)
- return -1;
-
- return 0;
-}
-
-static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
-{
- struct mem_cgroup_eventfd_list *ev;
-
- spin_lock(&memcg_oom_lock);
-
- list_for_each_entry(ev, &memcg->oom_notify, list)
- eventfd_signal(ev->eventfd);
-
- spin_unlock(&memcg_oom_lock);
- return 0;
-}
-
-static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- for_each_mem_cgroup_tree(iter, memcg)
- mem_cgroup_oom_notify_cb(iter);
-}
-
-static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args, enum res_type type)
-{
- struct mem_cgroup_thresholds *thresholds;
- struct mem_cgroup_threshold_ary *new;
- unsigned long threshold;
- unsigned long usage;
- int i, size, ret;
-
- ret = page_counter_memparse(args, "-1", &threshold);
- if (ret)
- return ret;
-
- mutex_lock(&memcg->thresholds_lock);
-
- if (type == _MEM) {
- thresholds = &memcg->thresholds;
- usage = mem_cgroup_usage(memcg, false);
- } else if (type == _MEMSWAP) {
- thresholds = &memcg->memsw_thresholds;
- usage = mem_cgroup_usage(memcg, true);
- } else
- BUG();
-
- /* Check if a threshold crossed before adding a new one */
- if (thresholds->primary)
- __mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
- size = thresholds->primary ? thresholds->primary->size + 1 : 1;
-
- /* Allocate memory for new array of thresholds */
- new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
- if (!new) {
- ret = -ENOMEM;
- goto unlock;
- }
- new->size = size;
-
- /* Copy thresholds (if any) to new array */
- if (thresholds->primary)
- memcpy(new->entries, thresholds->primary->entries,
- flex_array_size(new, entries, size - 1));
-
- /* Add new threshold */
- new->entries[size - 1].eventfd = eventfd;
- new->entries[size - 1].threshold = threshold;
-
- /* Sort thresholds. Registering of new threshold isn't time-critical */
- sort(new->entries, size, sizeof(*new->entries),
- compare_thresholds, NULL);
-
- /* Find current threshold */
- new->current_threshold = -1;
- for (i = 0; i < size; i++) {
- if (new->entries[i].threshold <= usage) {
- /*
- * new->current_threshold will not be used until
- * rcu_assign_pointer(), so it's safe to increment
- * it here.
- */
- ++new->current_threshold;
- } else
- break;
- }
-
- /* Free old spare buffer and save old primary buffer as spare */
- kfree(thresholds->spare);
- thresholds->spare = thresholds->primary;
-
- rcu_assign_pointer(thresholds->primary, new);
-
- /* To be sure that nobody uses thresholds */
- synchronize_rcu();
-
-unlock:
- mutex_unlock(&memcg->thresholds_lock);
-
- return ret;
-}
-
-static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
-}
-
-static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
-}
-
-static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, enum res_type type)
-{
- struct mem_cgroup_thresholds *thresholds;
- struct mem_cgroup_threshold_ary *new;
- unsigned long usage;
- int i, j, size, entries;
-
- mutex_lock(&memcg->thresholds_lock);
-
- if (type == _MEM) {
- thresholds = &memcg->thresholds;
- usage = mem_cgroup_usage(memcg, false);
- } else if (type == _MEMSWAP) {
- thresholds = &memcg->memsw_thresholds;
- usage = mem_cgroup_usage(memcg, true);
- } else
- BUG();
-
- if (!thresholds->primary)
- goto unlock;
-
- /* Check if a threshold crossed before removing */
- __mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
- /* Calculate new number of threshold */
- size = entries = 0;
- for (i = 0; i < thresholds->primary->size; i++) {
- if (thresholds->primary->entries[i].eventfd != eventfd)
- size++;
- else
- entries++;
- }
-
- new = thresholds->spare;
-
- /* If no items related to eventfd have been cleared, nothing to do */
- if (!entries)
- goto unlock;
-
- /* Set thresholds array to NULL if we don't have thresholds */
- if (!size) {
- kfree(new);
- new = NULL;
- goto swap_buffers;
- }
-
- new->size = size;
-
- /* Copy thresholds and find current threshold */
- new->current_threshold = -1;
- for (i = 0, j = 0; i < thresholds->primary->size; i++) {
- if (thresholds->primary->entries[i].eventfd == eventfd)
- continue;
-
- new->entries[j] = thresholds->primary->entries[i];
- if (new->entries[j].threshold <= usage) {
- /*
- * new->current_threshold will not be used
- * until rcu_assign_pointer(), so it's safe to increment
- * it here.
- */
- ++new->current_threshold;
- }
- j++;
- }
-
-swap_buffers:
- /* Swap primary and spare array */
- thresholds->spare = thresholds->primary;
-
- rcu_assign_pointer(thresholds->primary, new);
-
- /* To be sure that nobody uses thresholds */
- synchronize_rcu();
-
- /* If all events are unregistered, free the spare array */
- if (!new) {
- kfree(thresholds->spare);
- thresholds->spare = NULL;
- }
-unlock:
- mutex_unlock(&memcg->thresholds_lock);
-}
-
-static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
-}
-
-static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
-}
-
-static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- struct mem_cgroup_eventfd_list *event;
-
- event = kmalloc(sizeof(*event), GFP_KERNEL);
- if (!event)
- return -ENOMEM;
-
- spin_lock(&memcg_oom_lock);
-
- event->eventfd = eventfd;
- list_add(&event->list, &memcg->oom_notify);
-
- /* already in OOM ? */
- if (memcg->under_oom)
- eventfd_signal(eventfd);
- spin_unlock(&memcg_oom_lock);
-
- return 0;
-}
-
-static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- struct mem_cgroup_eventfd_list *ev, *tmp;
-
- spin_lock(&memcg_oom_lock);
-
- list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
- if (ev->eventfd == eventfd) {
- list_del(&ev->list);
- kfree(ev);
- }
- }
-
- spin_unlock(&memcg_oom_lock);
-}
-
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
@@ -4616,243 +4187,6 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
#endif /* CONFIG_CGROUP_WRITEBACK */
-/*
- * DO NOT USE IN NEW FILES.
- *
- * "cgroup.event_control" implementation.
- *
- * This is way over-engineered. It tries to support fully configurable
- * events for each user. Such level of flexibility is completely
- * unnecessary especially in the light of the planned unified hierarchy.
- *
- * Please deprecate this and replace with something simpler if at all
- * possible.
- */
-
-/*
- * Unregister event and free resources.
- *
- * Gets called from workqueue.
- */
-static void memcg_event_remove(struct work_struct *work)
-{
- struct mem_cgroup_event *event =
- container_of(work, struct mem_cgroup_event, remove);
- struct mem_cgroup *memcg = event->memcg;
-
- remove_wait_queue(event->wqh, &event->wait);
-
- event->unregister_event(memcg, event->eventfd);
-
- /* Notify userspace the event is going away. */
- eventfd_signal(event->eventfd);
-
- eventfd_ctx_put(event->eventfd);
- kfree(event);
- css_put(&memcg->css);
-}
-
-/*
- * Gets called on EPOLLHUP on eventfd when user closes it.
- *
- * Called with wqh->lock held and interrupts disabled.
- */
-static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode,
- int sync, void *key)
-{
- struct mem_cgroup_event *event =
- container_of(wait, struct mem_cgroup_event, wait);
- struct mem_cgroup *memcg = event->memcg;
- __poll_t flags = key_to_poll(key);
-
- if (flags & EPOLLHUP) {
- /*
- * If the event has been detached at cgroup removal, we
- * can simply return knowing the other side will cleanup
- * for us.
- *
- * We can't race against event freeing since the other
- * side will require wqh->lock via remove_wait_queue(),
- * which we hold.
- */
- spin_lock(&memcg->event_list_lock);
- if (!list_empty(&event->list)) {
- list_del_init(&event->list);
- /*
- * We are in atomic context, but cgroup_event_remove()
- * may sleep, so we have to call it in workqueue.
- */
- schedule_work(&event->remove);
- }
- spin_unlock(&memcg->event_list_lock);
- }
-
- return 0;
-}
-
-static void memcg_event_ptable_queue_proc(struct file *file,
- wait_queue_head_t *wqh, poll_table *pt)
-{
- struct mem_cgroup_event *event =
- container_of(pt, struct mem_cgroup_event, pt);
-
- event->wqh = wqh;
- add_wait_queue(wqh, &event->wait);
-}
-
-/*
- * DO NOT USE IN NEW FILES.
- *
- * Parse input and register new cgroup event handler.
- *
- * Input must be in format '<event_fd> <control_fd> <args>'.
- * Interpretation of args is defined by control file implementation.
- */
-static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- struct cgroup_subsys_state *css = of_css(of);
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- struct mem_cgroup_event *event;
- struct cgroup_subsys_state *cfile_css;
- unsigned int efd, cfd;
- struct fd efile;
- struct fd cfile;
- struct dentry *cdentry;
- const char *name;
- char *endp;
- int ret;
-
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- return -EOPNOTSUPP;
-
- buf = strstrip(buf);
-
- efd = simple_strtoul(buf, &endp, 10);
- if (*endp != ' ')
- return -EINVAL;
- buf = endp + 1;
-
- cfd = simple_strtoul(buf, &endp, 10);
- if ((*endp != ' ') && (*endp != '\0'))
- return -EINVAL;
- buf = endp + 1;
-
- event = kzalloc(sizeof(*event), GFP_KERNEL);
- if (!event)
- return -ENOMEM;
-
- event->memcg = memcg;
- INIT_LIST_HEAD(&event->list);
- init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
- init_waitqueue_func_entry(&event->wait, memcg_event_wake);
- INIT_WORK(&event->remove, memcg_event_remove);
-
- efile = fdget(efd);
- if (!efile.file) {
- ret = -EBADF;
- goto out_kfree;
- }
-
- event->eventfd = eventfd_ctx_fileget(efile.file);
- if (IS_ERR(event->eventfd)) {
- ret = PTR_ERR(event->eventfd);
- goto out_put_efile;
- }
-
- cfile = fdget(cfd);
- if (!cfile.file) {
- ret = -EBADF;
- goto out_put_eventfd;
- }
-
- /* the process need read permission on control file */
- /* AV: shouldn't we check that it's been opened for read instead? */
- ret = file_permission(cfile.file, MAY_READ);
- if (ret < 0)
- goto out_put_cfile;
-
- /*
- * The control file must be a regular cgroup1 file. As a regular cgroup
- * file can't be renamed, it's safe to access its name afterwards.
- */
- cdentry = cfile.file->f_path.dentry;
- if (cdentry->d_sb->s_type != &cgroup_fs_type || !d_is_reg(cdentry)) {
- ret = -EINVAL;
- goto out_put_cfile;
- }
-
- /*
- * Determine the event callbacks and set them in @event. This used
- * to be done via struct cftype but cgroup core no longer knows
- * about these events. The following is crude but the whole thing
- * is for compatibility anyway.
- *
- * DO NOT ADD NEW FILES.
- */
- name = cdentry->d_name.name;
-
- if (!strcmp(name, "memory.usage_in_bytes")) {
- event->register_event = mem_cgroup_usage_register_event;
- event->unregister_event = mem_cgroup_usage_unregister_event;
- } else if (!strcmp(name, "memory.oom_control")) {
- event->register_event = mem_cgroup_oom_register_event;
- event->unregister_event = mem_cgroup_oom_unregister_event;
- } else if (!strcmp(name, "memory.pressure_level")) {
- event->register_event = vmpressure_register_event;
- event->unregister_event = vmpressure_unregister_event;
- } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
- event->register_event = memsw_cgroup_usage_register_event;
- event->unregister_event = memsw_cgroup_usage_unregister_event;
- } else {
- ret = -EINVAL;
- goto out_put_cfile;
- }
-
- /*
- * Verify @cfile should belong to @css. Also, remaining events are
- * automatically removed on cgroup destruction but the removal is
- * asynchronous, so take an extra ref on @css.
- */
- cfile_css = css_tryget_online_from_dir(cdentry->d_parent,
- &memory_cgrp_subsys);
- ret = -EINVAL;
- if (IS_ERR(cfile_css))
- goto out_put_cfile;
- if (cfile_css != css) {
- css_put(cfile_css);
- goto out_put_cfile;
- }
-
- ret = event->register_event(memcg, event->eventfd, buf);
- if (ret)
- goto out_put_css;
-
- vfs_poll(efile.file, &event->pt);
-
- spin_lock_irq(&memcg->event_list_lock);
- list_add(&event->list, &memcg->event_list);
- spin_unlock_irq(&memcg->event_list_lock);
-
- fdput(cfile);
- fdput(efile);
-
- return nbytes;
-
-out_put_css:
- css_put(css);
-out_put_cfile:
- fdput(cfile);
-out_put_eventfd:
- eventfd_ctx_put(event->eventfd);
-out_put_efile:
- fdput(efile);
-out_kfree:
- kfree(event);
-
- return ret;
-}
-
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
static int mem_cgroup_slab_show(struct seq_file *m, void *p)
{
@@ -5319,19 +4653,8 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- struct mem_cgroup_event *event, *tmp;
- /*
- * Unregister events and notify userspace.
- * Notify userspace about cgroup removing only after rmdir of cgroup
- * directory to avoid race between userspace and kernelspace.
- */
- spin_lock_irq(&memcg->event_list_lock);
- list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
- list_del_init(&event->list);
- schedule_work(&event->remove);
- }
- spin_unlock_irq(&memcg->event_list_lock);
+ mem_cgroup_v1_offline_memcg(memcg);
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
--
2.43.2
From: Roman Gushchin <[email protected]>
Unlike the legacy cgroup v1 memory controller, cgroup v2 memory
controller doesn't support moving charged pages between cgroups.
It's a fairly large and complicated code which created a number
of problems in the past. Let's move this code into memcontrol-v1.c.
It shaves off 1k lines from memcontrol.c. It's also another step
towards making the legacy memory controller code compiled optionally.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 78 +--
mm/internal.h | 31 ++
mm/memcontrol-v1.c | 981 +++++++++++++++++++++++++++++++++++
mm/memcontrol.c | 1005 +-----------------------------------
4 files changed, 1059 insertions(+), 1036 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f77b6fbf38fd..60355f3cb67c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -971,29 +971,10 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
struct mem_cgroup *oom_domain);
void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);
-void folio_memcg_lock(struct folio *folio);
-void folio_memcg_unlock(struct folio *folio);
void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
int val);
-/* try to stablize folio_memcg() for all the pages in a memcg */
-static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
-{
- rcu_read_lock();
-
- if (mem_cgroup_disabled() || !atomic_read(&memcg->moving_account))
- return true;
-
- rcu_read_unlock();
- return false;
-}
-
-static inline void mem_cgroup_unlock_pages(void)
-{
- rcu_read_unlock();
-}
-
/* idx can be of type enum memcg_stat_item or node_stat_item */
static inline void mod_memcg_state(struct mem_cgroup *memcg,
enum memcg_stat_item idx, int val)
@@ -1435,26 +1416,6 @@ mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
{
}
-static inline void folio_memcg_lock(struct folio *folio)
-{
-}
-
-static inline void folio_memcg_unlock(struct folio *folio)
-{
-}
-
-static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
-{
- /* to match folio_memcg_rcu() */
- rcu_read_lock();
- return true;
-}
-
-static inline void mem_cgroup_unlock_pages(void)
-{
- rcu_read_unlock();
-}
-
static inline void mem_cgroup_handle_over_high(gfp_t gfp_mask)
{
}
@@ -1927,6 +1888,25 @@ static inline bool mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg)
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
gfp_t gfp_mask,
unsigned long *total_scanned);
+void folio_memcg_lock(struct folio *folio);
+void folio_memcg_unlock(struct folio *folio);
+
+/* try to stablize folio_memcg() for all the pages in a memcg */
+static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
+{
+ rcu_read_lock();
+
+ if (mem_cgroup_disabled() || !atomic_read(&memcg->moving_account))
+ return true;
+
+ rcu_read_unlock();
+ return false;
+}
+
+static inline void mem_cgroup_unlock_pages(void)
+{
+ rcu_read_unlock();
+}
#else /* CONFIG_MEMCG */
static inline
@@ -1936,6 +1916,26 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
{
return 0;
}
+
+static inline void folio_memcg_lock(struct folio *folio)
+{
+}
+
+static inline void folio_memcg_unlock(struct folio *folio)
+{
+}
+
+static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
+{
+ /* to match folio_memcg_rcu() */
+ rcu_read_lock();
+ return true;
+}
+
+static inline void mem_cgroup_unlock_pages(void)
+{
+ rcu_read_unlock();
+}
#endif /* CONFIG_MEMCG */
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/internal.h b/mm/internal.h
index 19e96d626977..9ffd48375ae5 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1521,9 +1521,40 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry,
void workingset_update_node(struct xa_node *node);
extern struct list_lru shadow_nodes;
+/* Memcontrol definitions used by memory cgroups v1-specific code */
+int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
+ unsigned int nr_pages);
+
+static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
+ unsigned int nr_pages)
+{
+ if (mem_cgroup_is_root(memcg))
+ return 0;
+
+ return try_charge_memcg(memcg, gfp_mask, nr_pages);
+}
+
+void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages);
+void memcg_check_events(struct mem_cgroup *memcg, int nid);
+void memcg_oom_recover(struct mem_cgroup *memcg);
+void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n);
+void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n);
+
/* Memory cgroups v1-specific definitions */
void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid);
void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg);
void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg);
+struct cftype;
+u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
+ struct cftype *cft);
+int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val);
+
+struct cgroup_taskset;
+int mem_cgroup_can_attach(struct cgroup_taskset *tset);
+void mem_cgroup_cancel_attach(struct cgroup_taskset *tset);
+bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg);
+void mem_cgroup_move_task(void);
+
#endif /* __MM_INTERNAL_H */
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 951e1c1189cc..b39bfa4a8de6 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1,9 +1,14 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/memcontrol.h>
+#include <linux/pagewalk.h>
+#include <linux/backing-dev.h>
+#include <linux/swap.h>
#include <linux/mm_inline.h>
+#include <linux/swap_cgroup.h>
#include "internal.h"
+#include "swap.h"
/*
* Cgroups above their limits are maintained in a RB-Tree, independent of
@@ -29,6 +34,31 @@ static struct mem_cgroup_tree soft_limit_tree __read_mostly;
#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100
#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2
+/* Stuff for move charges at task migration. */
+/*
+ * Types of charges to be moved.
+ */
+#define MOVE_ANON 0x1U
+#define MOVE_FILE 0x2U
+#define MOVE_MASK (MOVE_ANON | MOVE_FILE)
+
+/* "mc" and its members are protected by cgroup_mutex */
+static struct move_charge_struct {
+ spinlock_t lock; /* for from, to */
+ struct mm_struct *mm;
+ struct mem_cgroup *from;
+ struct mem_cgroup *to;
+ unsigned long flags;
+ unsigned long precharge;
+ unsigned long moved_charge;
+ unsigned long moved_swap;
+ struct task_struct *moving_task; /* a task moving charges */
+ wait_queue_head_t waitq; /* a waitq for other context */
+} mc = {
+ .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
+ .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
+};
+
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz,
unsigned long new_usage_in_excess)
@@ -329,6 +359,957 @@ void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg)
WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
}
+/*
+ * A routine for checking "mem" is under move_account() or not.
+ *
+ * Checking a cgroup is mc.from or mc.to or under hierarchy of
+ * moving cgroups. This is for waiting at high-memory pressure
+ * caused by "move".
+ */
+static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *from;
+ struct mem_cgroup *to;
+ bool ret = false;
+ /*
+ * Unlike task_move routines, we access mc.to, mc.from not under
+ * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
+ */
+ spin_lock(&mc.lock);
+ from = mc.from;
+ to = mc.to;
+ if (!from)
+ goto unlock;
+
+ ret = mem_cgroup_is_descendant(from, memcg) ||
+ mem_cgroup_is_descendant(to, memcg);
+unlock:
+ spin_unlock(&mc.lock);
+ return ret;
+}
+
+bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
+{
+ if (mc.moving_task && current != mc.moving_task) {
+ if (mem_cgroup_under_move(memcg)) {
+ DEFINE_WAIT(wait);
+ prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
+ /* moving charge context might have finished. */
+ if (mc.moving_task)
+ schedule();
+ finish_wait(&mc.waitq, &wait);
+ return true;
+ }
+ }
+ return false;
+}
+
+/**
+ * folio_memcg_lock - Bind a folio to its memcg.
+ * @folio: The folio.
+ *
+ * This function prevents unlocked LRU folios from being moved to
+ * another cgroup.
+ *
+ * It ensures lifetime of the bound memcg. The caller is responsible
+ * for the lifetime of the folio.
+ */
+void folio_memcg_lock(struct folio *folio)
+{
+ struct mem_cgroup *memcg;
+ unsigned long flags;
+
+ /*
+ * The RCU lock is held throughout the transaction. The fast
+ * path can get away without acquiring the memcg->move_lock
+ * because page moving starts with an RCU grace period.
+ */
+ rcu_read_lock();
+
+ if (mem_cgroup_disabled())
+ return;
+again:
+ memcg = folio_memcg(folio);
+ if (unlikely(!memcg))
+ return;
+
+#ifdef CONFIG_PROVE_LOCKING
+ local_irq_save(flags);
+ might_lock(&memcg->move_lock);
+ local_irq_restore(flags);
+#endif
+
+ if (atomic_read(&memcg->moving_account) <= 0)
+ return;
+
+ spin_lock_irqsave(&memcg->move_lock, flags);
+ if (memcg != folio_memcg(folio)) {
+ spin_unlock_irqrestore(&memcg->move_lock, flags);
+ goto again;
+ }
+
+ /*
+ * When charge migration first begins, we can have multiple
+ * critical sections holding the fast-path RCU lock and one
+ * holding the slowpath move_lock. Track the task who has the
+ * move_lock for folio_memcg_unlock().
+ */
+ memcg->move_lock_task = current;
+ memcg->move_lock_flags = flags;
+}
+
+static void __folio_memcg_unlock(struct mem_cgroup *memcg)
+{
+ if (memcg && memcg->move_lock_task == current) {
+ unsigned long flags = memcg->move_lock_flags;
+
+ memcg->move_lock_task = NULL;
+ memcg->move_lock_flags = 0;
+
+ spin_unlock_irqrestore(&memcg->move_lock, flags);
+ }
+
+ rcu_read_unlock();
+}
+
+/**
+ * folio_memcg_unlock - Release the binding between a folio and its memcg.
+ * @folio: The folio.
+ *
+ * This releases the binding created by folio_memcg_lock(). This does
+ * not change the accounting of this folio to its memcg, but it does
+ * permit others to change it.
+ */
+void folio_memcg_unlock(struct folio *folio)
+{
+ __folio_memcg_unlock(folio_memcg(folio));
+}
+
+#ifdef CONFIG_SWAP
+/**
+ * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
+ * @entry: swap entry to be moved
+ * @from: mem_cgroup which the entry is moved from
+ * @to: mem_cgroup which the entry is moved to
+ *
+ * It succeeds only when the swap_cgroup's record for this entry is the same
+ * as the mem_cgroup's id of @from.
+ *
+ * Returns 0 on success, -EINVAL on failure.
+ *
+ * The caller must have charged to @to, IOW, called page_counter_charge() about
+ * both res and memsw, and called css_get().
+ */
+static int mem_cgroup_move_swap_account(swp_entry_t entry,
+ struct mem_cgroup *from, struct mem_cgroup *to)
+{
+ unsigned short old_id, new_id;
+
+ old_id = mem_cgroup_id(from);
+ new_id = mem_cgroup_id(to);
+
+ if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
+ mod_memcg_state(from, MEMCG_SWAP, -1);
+ mod_memcg_state(to, MEMCG_SWAP, 1);
+ return 0;
+ }
+ return -EINVAL;
+}
+#else
+static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
+ struct mem_cgroup *from, struct mem_cgroup *to)
+{
+ return -EINVAL;
+}
+#endif
+
+u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return mem_cgroup_from_css(css)->move_charge_at_immigrate;
+}
+
+#ifdef CONFIG_MMU
+int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+ pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. "
+ "Please report your usecase to [email protected] if you "
+ "depend on this functionality.\n");
+
+ if (val & ~MOVE_MASK)
+ return -EINVAL;
+
+ /*
+ * No kind of locking is needed in here, because ->can_attach() will
+ * check this value once in the beginning of the process, and then carry
+ * on with stale data. This means that changes to this value will only
+ * affect task migrations starting after the change.
+ */
+ memcg->move_charge_at_immigrate = val;
+ return 0;
+}
+#else
+int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ return -ENOSYS;
+}
+#endif
+
+#ifdef CONFIG_MMU
+/* Handlers for move charge at task migration. */
+static int mem_cgroup_do_precharge(unsigned long count)
+{
+ int ret;
+
+ /* Try a single bulk charge without reclaim first, kswapd may wake */
+ ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
+ if (!ret) {
+ mc.precharge += count;
+ return ret;
+ }
+
+ /* Try charges one by one with reclaim, but do not retry */
+ while (count--) {
+ ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
+ if (ret)
+ return ret;
+ mc.precharge++;
+ cond_resched();
+ }
+ return 0;
+}
+
+union mc_target {
+ struct folio *folio;
+ swp_entry_t ent;
+};
+
+enum mc_target_type {
+ MC_TARGET_NONE = 0,
+ MC_TARGET_PAGE,
+ MC_TARGET_SWAP,
+ MC_TARGET_DEVICE,
+};
+
+static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t ptent)
+{
+ struct page *page = vm_normal_page(vma, addr, ptent);
+
+ if (!page)
+ return NULL;
+ if (PageAnon(page)) {
+ if (!(mc.flags & MOVE_ANON))
+ return NULL;
+ } else {
+ if (!(mc.flags & MOVE_FILE))
+ return NULL;
+ }
+ get_page(page);
+
+ return page;
+}
+
+#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+ pte_t ptent, swp_entry_t *entry)
+{
+ struct page *page = NULL;
+ swp_entry_t ent = pte_to_swp_entry(ptent);
+
+ if (!(mc.flags & MOVE_ANON))
+ return NULL;
+
+ /*
+ * Handle device private pages that are not accessible by the CPU, but
+ * stored as special swap entries in the page table.
+ */
+ if (is_device_private_entry(ent)) {
+ page = pfn_swap_entry_to_page(ent);
+ if (!get_page_unless_zero(page))
+ return NULL;
+ return page;
+ }
+
+ if (non_swap_entry(ent))
+ return NULL;
+
+ /*
+ * Because swap_cache_get_folio() updates some statistics counter,
+ * we call find_get_page() with swapper_space directly.
+ */
+ page = find_get_page(swap_address_space(ent), swp_offset(ent));
+ entry->val = ent.val;
+
+ return page;
+}
+#else
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+ pte_t ptent, swp_entry_t *entry)
+{
+ return NULL;
+}
+#endif
+
+static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t ptent)
+{
+ unsigned long index;
+ struct folio *folio;
+
+ if (!vma->vm_file) /* anonymous vma */
+ return NULL;
+ if (!(mc.flags & MOVE_FILE))
+ return NULL;
+
+ /* folio is moved even if it's not RSS of this task(page-faulted). */
+ /* shmem/tmpfs may report page out on swap: account for that too. */
+ index = linear_page_index(vma, addr);
+ folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
+ if (IS_ERR(folio))
+ return NULL;
+ return folio_file_page(folio, index);
+}
+
+/**
+ * mem_cgroup_move_account - move account of the folio
+ * @folio: The folio.
+ * @compound: charge the page as compound or small page
+ * @from: mem_cgroup which the folio is moved from.
+ * @to: mem_cgroup which the folio is moved to. @from != @to.
+ *
+ * The folio must be locked and not on the LRU.
+ *
+ * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
+ * from old cgroup.
+ */
+static int mem_cgroup_move_account(struct folio *folio,
+ bool compound,
+ struct mem_cgroup *from,
+ struct mem_cgroup *to)
+{
+ struct lruvec *from_vec, *to_vec;
+ struct pglist_data *pgdat;
+ unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1;
+ int nid, ret;
+
+ VM_BUG_ON(from == to);
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
+ VM_BUG_ON(compound && !folio_test_large(folio));
+
+ ret = -EINVAL;
+ if (folio_memcg(folio) != from)
+ goto out;
+
+ pgdat = folio_pgdat(folio);
+ from_vec = mem_cgroup_lruvec(from, pgdat);
+ to_vec = mem_cgroup_lruvec(to, pgdat);
+
+ folio_memcg_lock(folio);
+
+ if (folio_test_anon(folio)) {
+ if (folio_mapped(folio)) {
+ __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
+ if (folio_test_pmd_mappable(folio)) {
+ __mod_lruvec_state(from_vec, NR_ANON_THPS,
+ -nr_pages);
+ __mod_lruvec_state(to_vec, NR_ANON_THPS,
+ nr_pages);
+ }
+ }
+ } else {
+ __mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);
+
+ if (folio_test_swapbacked(folio)) {
+ __mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_SHMEM, nr_pages);
+ }
+
+ if (folio_mapped(folio)) {
+ __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
+ }
+
+ if (folio_test_dirty(folio)) {
+ struct address_space *mapping = folio_mapping(folio);
+
+ if (mapping_can_writeback(mapping)) {
+ __mod_lruvec_state(from_vec, NR_FILE_DIRTY,
+ -nr_pages);
+ __mod_lruvec_state(to_vec, NR_FILE_DIRTY,
+ nr_pages);
+ }
+ }
+ }
+
+#ifdef CONFIG_SWAP
+ if (folio_test_swapcache(folio)) {
+ __mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages);
+ }
+#endif
+ if (folio_test_writeback(folio)) {
+ __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
+ __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);
+ }
+
+ /*
+ * All state has been migrated, let's switch to the new memcg.
+ *
+ * It is safe to change page's memcg here because the page
+ * is referenced, charged, isolated, and locked: we can't race
+ * with (un)charging, migration, LRU putback, or anything else
+ * that would rely on a stable page's memory cgroup.
+ *
+ * Note that folio_memcg_lock is a memcg lock, not a page lock,
+ * to save space. As soon as we switch page's memory cgroup to a
+ * new memcg that isn't locked, the above state can change
+ * concurrently again. Make sure we're truly done with it.
+ */
+ smp_mb();
+
+ css_get(&to->css);
+ css_put(&from->css);
+
+ folio->memcg_data = (unsigned long)to;
+
+ __folio_memcg_unlock(from);
+
+ ret = 0;
+ nid = folio_nid(folio);
+
+ local_irq_disable();
+ mem_cgroup_charge_statistics(to, nr_pages);
+ memcg_check_events(to, nid);
+ mem_cgroup_charge_statistics(from, -nr_pages);
+ memcg_check_events(from, nid);
+ local_irq_enable();
+out:
+ return ret;
+}
+
+/**
+ * get_mctgt_type - get target type of moving charge
+ * @vma: the vma the pte to be checked belongs
+ * @addr: the address corresponding to the pte to be checked
+ * @ptent: the pte to be checked
+ * @target: the pointer the target page or swap ent will be stored(can be NULL)
+ *
+ * Context: Called with pte lock held.
+ * Return:
+ * * MC_TARGET_NONE - If the pte is not a target for move charge.
+ * * MC_TARGET_PAGE - If the page corresponding to this pte is a target for
+ * move charge. If @target is not NULL, the folio is stored in target->folio
+ * with extra refcnt taken (Caller should release it).
+ * * MC_TARGET_SWAP - If the swap entry corresponding to this pte is a
+ * target for charge migration. If @target is not NULL, the entry is
+ * stored in target->ent.
+ * * MC_TARGET_DEVICE - Like MC_TARGET_PAGE but page is device memory and
+ * thus not on the lru. For now such page is charged like a regular page
+ * would be as it is just special memory taking the place of a regular page.
+ * See Documentations/vm/hmm.txt and include/linux/hmm.h
+ */
+static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
+ unsigned long addr, pte_t ptent, union mc_target *target)
+{
+ struct page *page = NULL;
+ struct folio *folio;
+ enum mc_target_type ret = MC_TARGET_NONE;
+ swp_entry_t ent = { .val = 0 };
+
+ if (pte_present(ptent))
+ page = mc_handle_present_pte(vma, addr, ptent);
+ else if (pte_none_mostly(ptent))
+ /*
+ * PTE markers should be treated as a none pte here, separated
+ * from other swap handling below.
+ */
+ page = mc_handle_file_pte(vma, addr, ptent);
+ else if (is_swap_pte(ptent))
+ page = mc_handle_swap_pte(vma, ptent, &ent);
+
+ if (page)
+ folio = page_folio(page);
+ if (target && page) {
+ if (!folio_trylock(folio)) {
+ folio_put(folio);
+ return ret;
+ }
+ /*
+ * page_mapped() must be stable during the move. This
+ * pte is locked, so if it's present, the page cannot
+ * become unmapped. If it isn't, we have only partial
+ * control over the mapped state: the page lock will
+ * prevent new faults against pagecache and swapcache,
+ * so an unmapped page cannot become mapped. However,
+ * if the page is already mapped elsewhere, it can
+ * unmap, and there is nothing we can do about it.
+ * Alas, skip moving the page in this case.
+ */
+ if (!pte_present(ptent) && page_mapped(page)) {
+ folio_unlock(folio);
+ folio_put(folio);
+ return ret;
+ }
+ }
+
+ if (!page && !ent.val)
+ return ret;
+ if (page) {
+ /*
+ * Do only loose check w/o serialization.
+ * mem_cgroup_move_account() checks the page is valid or
+ * not under LRU exclusion.
+ */
+ if (folio_memcg(folio) == mc.from) {
+ ret = MC_TARGET_PAGE;
+ if (folio_is_device_private(folio) ||
+ folio_is_device_coherent(folio))
+ ret = MC_TARGET_DEVICE;
+ if (target)
+ target->folio = folio;
+ }
+ if (!ret || !target) {
+ if (target)
+ folio_unlock(folio);
+ folio_put(folio);
+ }
+ }
+ /*
+ * There is a swap entry and a page doesn't exist or isn't charged.
+ * But we cannot move a tail-page in a THP.
+ */
+ if (ent.val && !ret && (!page || !PageTransCompound(page)) &&
+ mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
+ ret = MC_TARGET_SWAP;
+ if (target)
+ target->ent = ent;
+ }
+ return ret;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * We don't consider PMD mapped swapping or file mapped pages because THP does
+ * not support them for now.
+ * Caller should make sure that pmd_trans_huge(pmd) is true.
+ */
+static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+ struct page *page = NULL;
+ struct folio *folio;
+ enum mc_target_type ret = MC_TARGET_NONE;
+
+ if (unlikely(is_swap_pmd(pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(pmd));
+ return ret;
+ }
+ page = pmd_page(pmd);
+ VM_BUG_ON_PAGE(!page || !PageHead(page), page);
+ folio = page_folio(page);
+ if (!(mc.flags & MOVE_ANON))
+ return ret;
+ if (folio_memcg(folio) == mc.from) {
+ ret = MC_TARGET_PAGE;
+ if (target) {
+ folio_get(folio);
+ if (!folio_trylock(folio)) {
+ folio_put(folio);
+ return MC_TARGET_NONE;
+ }
+ target->folio = folio;
+ }
+ }
+ return ret;
+}
+#else
+static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+ return MC_TARGET_NONE;
+}
+#endif
+
+static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct vm_area_struct *vma = walk->vma;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (ptl) {
+ /*
+ * Note their can not be MC_TARGET_DEVICE for now as we do not
+ * support transparent huge page with MEMORY_DEVICE_PRIVATE but
+ * this might change.
+ */
+ if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
+ mc.precharge += HPAGE_PMD_NR;
+ spin_unlock(ptl);
+ return 0;
+ }
+
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+ if (!pte)
+ return 0;
+ for (; addr != end; pte++, addr += PAGE_SIZE)
+ if (get_mctgt_type(vma, addr, ptep_get(pte), NULL))
+ mc.precharge++; /* increment precharge temporarily */
+ pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
+
+ return 0;
+}
+
+static const struct mm_walk_ops precharge_walk_ops = {
+ .pmd_entry = mem_cgroup_count_precharge_pte_range,
+ .walk_lock = PGWALK_RDLOCK,
+};
+
+static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
+{
+ unsigned long precharge;
+
+ mmap_read_lock(mm);
+ walk_page_range(mm, 0, ULONG_MAX, &precharge_walk_ops, NULL);
+ mmap_read_unlock(mm);
+
+ precharge = mc.precharge;
+ mc.precharge = 0;
+
+ return precharge;
+}
+
+static int mem_cgroup_precharge_mc(struct mm_struct *mm)
+{
+ unsigned long precharge = mem_cgroup_count_precharge(mm);
+
+ VM_BUG_ON(mc.moving_task);
+ mc.moving_task = current;
+ return mem_cgroup_do_precharge(precharge);
+}
+
+/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
+static void __mem_cgroup_clear_mc(void)
+{
+ struct mem_cgroup *from = mc.from;
+ struct mem_cgroup *to = mc.to;
+
+ /* we must uncharge all the leftover precharges from mc.to */
+ if (mc.precharge) {
+ mem_cgroup_cancel_charge(mc.to, mc.precharge);
+ mc.precharge = 0;
+ }
+ /*
+ * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
+ * we must uncharge here.
+ */
+ if (mc.moved_charge) {
+ mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
+ mc.moved_charge = 0;
+ }
+ /* we must fixup refcnts and charges */
+ if (mc.moved_swap) {
+ /* uncharge swap account from the old cgroup */
+ if (!mem_cgroup_is_root(mc.from))
+ page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
+
+ mem_cgroup_id_put_many(mc.from, mc.moved_swap);
+
+ /*
+ * we charged both to->memory and to->memsw, so we
+ * should uncharge to->memory.
+ */
+ if (!mem_cgroup_is_root(mc.to))
+ page_counter_uncharge(&mc.to->memory, mc.moved_swap);
+
+ mc.moved_swap = 0;
+ }
+ memcg_oom_recover(from);
+ memcg_oom_recover(to);
+ wake_up_all(&mc.waitq);
+}
+
+static void mem_cgroup_clear_mc(void)
+{
+ struct mm_struct *mm = mc.mm;
+
+ /*
+ * we must clear moving_task before waking up waiters at the end of
+ * task migration.
+ */
+ mc.moving_task = NULL;
+ __mem_cgroup_clear_mc();
+ spin_lock(&mc.lock);
+ mc.from = NULL;
+ mc.to = NULL;
+ mc.mm = NULL;
+ spin_unlock(&mc.lock);
+
+ mmput(mm);
+}
+
+int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+ struct cgroup_subsys_state *css;
+ struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
+ struct mem_cgroup *from;
+ struct task_struct *leader, *p;
+ struct mm_struct *mm;
+ unsigned long move_flags;
+ int ret = 0;
+
+ /* charge immigration isn't supported on the default hierarchy */
+ if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+ return 0;
+
+ /*
+ * Multi-process migrations only happen on the default hierarchy
+ * where charge immigration is not used. Perform charge
+ * immigration if @tset contains a leader and whine if there are
+ * multiple.
+ */
+ p = NULL;
+ cgroup_taskset_for_each_leader(leader, css, tset) {
+ WARN_ON_ONCE(p);
+ p = leader;
+ memcg = mem_cgroup_from_css(css);
+ }
+ if (!p)
+ return 0;
+
+ /*
+ * We are now committed to this value whatever it is. Changes in this
+ * tunable will only affect upcoming migrations, not the current one.
+ * So we need to save it, and keep it going.
+ */
+ move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
+ if (!move_flags)
+ return 0;
+
+ from = mem_cgroup_from_task(p);
+
+ VM_BUG_ON(from == memcg);
+
+ mm = get_task_mm(p);
+ if (!mm)
+ return 0;
+ /* We move charges only when we move a owner of the mm */
+ if (mm->owner == p) {
+ VM_BUG_ON(mc.from);
+ VM_BUG_ON(mc.to);
+ VM_BUG_ON(mc.precharge);
+ VM_BUG_ON(mc.moved_charge);
+ VM_BUG_ON(mc.moved_swap);
+
+ spin_lock(&mc.lock);
+ mc.mm = mm;
+ mc.from = from;
+ mc.to = memcg;
+ mc.flags = move_flags;
+ spin_unlock(&mc.lock);
+ /* We set mc.moving_task later */
+
+ ret = mem_cgroup_precharge_mc(mm);
+ if (ret)
+ mem_cgroup_clear_mc();
+ } else {
+ mmput(mm);
+ }
+ return ret;
+}
+
+void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+ if (mc.to)
+ mem_cgroup_clear_mc();
+}
+
+static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ int ret = 0;
+ struct vm_area_struct *vma = walk->vma;
+ pte_t *pte;
+ spinlock_t *ptl;
+ enum mc_target_type target_type;
+ union mc_target target;
+ struct folio *folio;
+
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (ptl) {
+ if (mc.precharge < HPAGE_PMD_NR) {
+ spin_unlock(ptl);
+ return 0;
+ }
+ target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
+ if (target_type == MC_TARGET_PAGE) {
+ folio = target.folio;
+ if (folio_isolate_lru(folio)) {
+ if (!mem_cgroup_move_account(folio, true,
+ mc.from, mc.to)) {
+ mc.precharge -= HPAGE_PMD_NR;
+ mc.moved_charge += HPAGE_PMD_NR;
+ }
+ folio_putback_lru(folio);
+ }
+ folio_unlock(folio);
+ folio_put(folio);
+ } else if (target_type == MC_TARGET_DEVICE) {
+ folio = target.folio;
+ if (!mem_cgroup_move_account(folio, true,
+ mc.from, mc.to)) {
+ mc.precharge -= HPAGE_PMD_NR;
+ mc.moved_charge += HPAGE_PMD_NR;
+ }
+ folio_unlock(folio);
+ folio_put(folio);
+ }
+ spin_unlock(ptl);
+ return 0;
+ }
+
+retry:
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+ if (!pte)
+ return 0;
+ for (; addr != end; addr += PAGE_SIZE) {
+ pte_t ptent = ptep_get(pte++);
+ bool device = false;
+ swp_entry_t ent;
+
+ if (!mc.precharge)
+ break;
+
+ switch (get_mctgt_type(vma, addr, ptent, &target)) {
+ case MC_TARGET_DEVICE:
+ device = true;
+ fallthrough;
+ case MC_TARGET_PAGE:
+ folio = target.folio;
+ /*
+ * We can have a part of the split pmd here. Moving it
+ * can be done but it would be too convoluted so simply
+ * ignore such a partial THP and keep it in original
+ * memcg. There should be somebody mapping the head.
+ */
+ if (folio_test_large(folio))
+ goto put;
+ if (!device && !folio_isolate_lru(folio))
+ goto put;
+ if (!mem_cgroup_move_account(folio, false,
+ mc.from, mc.to)) {
+ mc.precharge--;
+ /* we uncharge from mc.from later. */
+ mc.moved_charge++;
+ }
+ if (!device)
+ folio_putback_lru(folio);
+put: /* get_mctgt_type() gets & locks the page */
+ folio_unlock(folio);
+ folio_put(folio);
+ break;
+ case MC_TARGET_SWAP:
+ ent = target.ent;
+ if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
+ mc.precharge--;
+ mem_cgroup_id_get_many(mc.to, 1);
+ /* we fixup other refcnts and charges later. */
+ mc.moved_swap++;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
+
+ if (addr != end) {
+ /*
+ * We have consumed all precharges we got in can_attach().
+ * We try charge one by one, but don't do any additional
+ * charges to mc.to if we have failed in charge once in attach()
+ * phase.
+ */
+ ret = mem_cgroup_do_precharge(1);
+ if (!ret)
+ goto retry;
+ }
+
+ return ret;
+}
+
+static const struct mm_walk_ops charge_walk_ops = {
+ .pmd_entry = mem_cgroup_move_charge_pte_range,
+ .walk_lock = PGWALK_RDLOCK,
+};
+
+static void mem_cgroup_move_charge(void)
+{
+ lru_add_drain_all();
+ /*
+ * Signal folio_memcg_lock() to take the memcg's move_lock
+ * while we're moving its pages to another memcg. Then wait
+ * for already started RCU-only updates to finish.
+ */
+ atomic_inc(&mc.from->moving_account);
+ synchronize_rcu();
+retry:
+ if (unlikely(!mmap_read_trylock(mc.mm))) {
+ /*
+ * Someone who are holding the mmap_lock might be waiting in
+ * waitq. So we cancel all extra charges, wake up all waiters,
+ * and retry. Because we cancel precharges, we might not be able
+ * to move enough charges, but moving charge is a best-effort
+ * feature anyway, so it wouldn't be a big problem.
+ */
+ __mem_cgroup_clear_mc();
+ cond_resched();
+ goto retry;
+ }
+ /*
+ * When we have consumed all precharges and failed in doing
+ * additional charge, the page walk just aborts.
+ */
+ walk_page_range(mc.mm, 0, ULONG_MAX, &charge_walk_ops, NULL);
+ mmap_read_unlock(mc.mm);
+ atomic_dec(&mc.from->moving_account);
+}
+
+void mem_cgroup_move_task(void)
+{
+ if (mc.to) {
+ mem_cgroup_move_charge();
+ mem_cgroup_clear_mc();
+ }
+}
+
+#else /* !CONFIG_MMU */
+int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+ return 0;
+}
+void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+}
+void mem_cgroup_move_task(void)
+{
+}
+#endif
+
static int __init mem_cgroup_v1_init(void)
{
int node;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0c2196f42631..dc0a38d1107c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -28,7 +28,6 @@
#include <linux/page_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
-#include <linux/pagewalk.h>
#include <linux/sched/mm.h>
#include <linux/shmem_fs.h>
#include <linux/hugetlb.h>
@@ -45,7 +44,6 @@
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
-#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/spinlock.h>
#include <linux/eventfd.h>
@@ -71,7 +69,6 @@
#include <net/sock.h>
#include <net/ip.h>
#include "slab.h"
-#include "swap.h"
#include <linux/uaccess.h>
@@ -157,31 +154,6 @@ struct mem_cgroup_event {
static void mem_cgroup_threshold(struct mem_cgroup *memcg);
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
-/* Stuffs for move charges at task migration. */
-/*
- * Types of charges to be moved.
- */
-#define MOVE_ANON 0x1U
-#define MOVE_FILE 0x2U
-#define MOVE_MASK (MOVE_ANON | MOVE_FILE)
-
-/* "mc" and its members are protected by cgroup_mutex */
-static struct move_charge_struct {
- spinlock_t lock; /* for from, to */
- struct mm_struct *mm;
- struct mem_cgroup *from;
- struct mem_cgroup *to;
- unsigned long flags;
- unsigned long precharge;
- unsigned long moved_charge;
- unsigned long moved_swap;
- struct task_struct *moving_task; /* a task moving charges */
- wait_queue_head_t waitq; /* a waitq for other context */
-} mc = {
- .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
- .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
-};
-
/* for encoding cft->private value on file */
enum res_type {
_MEM,
@@ -957,8 +929,7 @@ static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
return READ_ONCE(memcg->vmstats->events_local[i]);
}
-static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
- int nr_pages)
+void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages)
{
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
@@ -1000,7 +971,7 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
* Check events in order.
*
*/
-static void memcg_check_events(struct mem_cgroup *memcg, int nid)
+void memcg_check_events(struct mem_cgroup *memcg, int nid)
{
if (IS_ENABLED(CONFIG_PREEMPT_RT))
return;
@@ -1469,51 +1440,6 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
return margin;
}
-/*
- * A routine for checking "mem" is under move_account() or not.
- *
- * Checking a cgroup is mc.from or mc.to or under hierarchy of
- * moving cgroups. This is for waiting at high-memory pressure
- * caused by "move".
- */
-static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *from;
- struct mem_cgroup *to;
- bool ret = false;
- /*
- * Unlike task_move routines, we access mc.to, mc.from not under
- * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
- */
- spin_lock(&mc.lock);
- from = mc.from;
- to = mc.to;
- if (!from)
- goto unlock;
-
- ret = mem_cgroup_is_descendant(from, memcg) ||
- mem_cgroup_is_descendant(to, memcg);
-unlock:
- spin_unlock(&mc.lock);
- return ret;
-}
-
-static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
-{
- if (mc.moving_task && current != mc.moving_task) {
- if (mem_cgroup_under_move(memcg)) {
- DEFINE_WAIT(wait);
- prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
- /* moving charge context might have finished. */
- if (mc.moving_task)
- schedule();
- finish_wait(&mc.waitq, &wait);
- return true;
- }
- }
- return false;
-}
-
struct memory_stat {
const char *name;
unsigned int idx;
@@ -1906,7 +1832,7 @@ static int memcg_oom_wake_function(wait_queue_entry_t *wait,
return autoremove_wake_function(wait, mode, sync, arg);
}
-static void memcg_oom_recover(struct mem_cgroup *memcg)
+void memcg_oom_recover(struct mem_cgroup *memcg)
{
/*
* For the following lockless ->under_oom test, the only required
@@ -2097,87 +2023,6 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
pr_cont(" are going to be killed due to memory.oom.group set\n");
}
-/**
- * folio_memcg_lock - Bind a folio to its memcg.
- * @folio: The folio.
- *
- * This function prevents unlocked LRU folios from being moved to
- * another cgroup.
- *
- * It ensures lifetime of the bound memcg. The caller is responsible
- * for the lifetime of the folio.
- */
-void folio_memcg_lock(struct folio *folio)
-{
- struct mem_cgroup *memcg;
- unsigned long flags;
-
- /*
- * The RCU lock is held throughout the transaction. The fast
- * path can get away without acquiring the memcg->move_lock
- * because page moving starts with an RCU grace period.
- */
- rcu_read_lock();
-
- if (mem_cgroup_disabled())
- return;
-again:
- memcg = folio_memcg(folio);
- if (unlikely(!memcg))
- return;
-
-#ifdef CONFIG_PROVE_LOCKING
- local_irq_save(flags);
- might_lock(&memcg->move_lock);
- local_irq_restore(flags);
-#endif
-
- if (atomic_read(&memcg->moving_account) <= 0)
- return;
-
- spin_lock_irqsave(&memcg->move_lock, flags);
- if (memcg != folio_memcg(folio)) {
- spin_unlock_irqrestore(&memcg->move_lock, flags);
- goto again;
- }
-
- /*
- * When charge migration first begins, we can have multiple
- * critical sections holding the fast-path RCU lock and one
- * holding the slowpath move_lock. Track the task who has the
- * move_lock for folio_memcg_unlock().
- */
- memcg->move_lock_task = current;
- memcg->move_lock_flags = flags;
-}
-
-static void __folio_memcg_unlock(struct mem_cgroup *memcg)
-{
- if (memcg && memcg->move_lock_task == current) {
- unsigned long flags = memcg->move_lock_flags;
-
- memcg->move_lock_task = NULL;
- memcg->move_lock_flags = 0;
-
- spin_unlock_irqrestore(&memcg->move_lock, flags);
- }
-
- rcu_read_unlock();
-}
-
-/**
- * folio_memcg_unlock - Release the binding between a folio and its memcg.
- * @folio: The folio.
- *
- * This releases the binding created by folio_memcg_lock(). This does
- * not change the accounting of this folio to its memcg, but it does
- * permit others to change it.
- */
-void folio_memcg_unlock(struct folio *folio)
-{
- __folio_memcg_unlock(folio_memcg(folio));
-}
-
struct memcg_stock_pcp {
local_lock_t stock_lock;
struct mem_cgroup *cached; /* this never be root cgroup */
@@ -2657,8 +2502,8 @@ void mem_cgroup_handle_over_high(gfp_t gfp_mask)
css_put(&memcg->css);
}
-static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
- unsigned int nr_pages)
+int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
+ unsigned int nr_pages)
{
unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
int nr_retries = MAX_RECLAIM_RETRIES;
@@ -2853,15 +2698,6 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
return 0;
}
-static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
- unsigned int nr_pages)
-{
- if (mem_cgroup_is_root(memcg))
- return 0;
-
- return try_charge_memcg(memcg, gfp_mask, nr_pages);
-}
-
/**
* mem_cgroup_cancel_charge() - cancel an uncommitted try_charge() call.
* @memcg: memcg previously charged.
@@ -3601,44 +3437,6 @@ void split_page_memcg(struct page *head, int old_order, int new_order)
css_get_many(&memcg->css, old_nr / new_nr - 1);
}
-#ifdef CONFIG_SWAP
-/**
- * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
- * @entry: swap entry to be moved
- * @from: mem_cgroup which the entry is moved from
- * @to: mem_cgroup which the entry is moved to
- *
- * It succeeds only when the swap_cgroup's record for this entry is the same
- * as the mem_cgroup's id of @from.
- *
- * Returns 0 on success, -EINVAL on failure.
- *
- * The caller must have charged to @to, IOW, called page_counter_charge() about
- * both res and memsw, and called css_get().
- */
-static int mem_cgroup_move_swap_account(swp_entry_t entry,
- struct mem_cgroup *from, struct mem_cgroup *to)
-{
- unsigned short old_id, new_id;
-
- old_id = mem_cgroup_id(from);
- new_id = mem_cgroup_id(to);
-
- if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
- mod_memcg_state(from, MEMCG_SWAP, -1);
- mod_memcg_state(to, MEMCG_SWAP, 1);
- return 0;
- }
- return -EINVAL;
-}
-#else
-static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
- struct mem_cgroup *from, struct mem_cgroup *to)
-{
- return -EINVAL;
-}
-#endif
-
static DEFINE_MUTEX(memcg_max_mutex);
static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
@@ -4021,42 +3819,6 @@ static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
return nbytes;
}
-static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return mem_cgroup_from_css(css)->move_charge_at_immigrate;
-}
-
-#ifdef CONFIG_MMU
-static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-
- pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. "
- "Please report your usecase to [email protected] if you "
- "depend on this functionality.\n");
-
- if (val & ~MOVE_MASK)
- return -EINVAL;
-
- /*
- * No kind of locking is needed in here, because ->can_attach() will
- * check this value once in the beginning of the process, and then carry
- * on with stale data. This means that changes to this value will only
- * affect task migrations starting after the change.
- */
- memcg->move_charge_at_immigrate = val;
- return 0;
-}
-#else
-static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- return -ENOSYS;
-}
-#endif
-
#ifdef CONFIG_NUMA
#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
@@ -5267,13 +5029,13 @@ static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
}
}
-static void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg,
- unsigned int n)
+void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg,
+ unsigned int n)
{
refcount_add(n, &memcg->id.ref);
}
-static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
+void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
{
if (refcount_sub_and_test(n, &memcg->id.ref)) {
mem_cgroup_id_remove(memcg);
@@ -5753,757 +5515,6 @@ static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu)
atomic64_set(&memcg->vmstats->stats_updates, 0);
}
-#ifdef CONFIG_MMU
-/* Handlers for move charge at task migration. */
-static int mem_cgroup_do_precharge(unsigned long count)
-{
- int ret;
-
- /* Try a single bulk charge without reclaim first, kswapd may wake */
- ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
- if (!ret) {
- mc.precharge += count;
- return ret;
- }
-
- /* Try charges one by one with reclaim, but do not retry */
- while (count--) {
- ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
- if (ret)
- return ret;
- mc.precharge++;
- cond_resched();
- }
- return 0;
-}
-
-union mc_target {
- struct folio *folio;
- swp_entry_t ent;
-};
-
-enum mc_target_type {
- MC_TARGET_NONE = 0,
- MC_TARGET_PAGE,
- MC_TARGET_SWAP,
- MC_TARGET_DEVICE,
-};
-
-static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
- unsigned long addr, pte_t ptent)
-{
- struct page *page = vm_normal_page(vma, addr, ptent);
-
- if (!page)
- return NULL;
- if (PageAnon(page)) {
- if (!(mc.flags & MOVE_ANON))
- return NULL;
- } else {
- if (!(mc.flags & MOVE_FILE))
- return NULL;
- }
- get_page(page);
-
- return page;
-}
-
-#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
-static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
- pte_t ptent, swp_entry_t *entry)
-{
- struct page *page = NULL;
- swp_entry_t ent = pte_to_swp_entry(ptent);
-
- if (!(mc.flags & MOVE_ANON))
- return NULL;
-
- /*
- * Handle device private pages that are not accessible by the CPU, but
- * stored as special swap entries in the page table.
- */
- if (is_device_private_entry(ent)) {
- page = pfn_swap_entry_to_page(ent);
- if (!get_page_unless_zero(page))
- return NULL;
- return page;
- }
-
- if (non_swap_entry(ent))
- return NULL;
-
- /*
- * Because swap_cache_get_folio() updates some statistics counter,
- * we call find_get_page() with swapper_space directly.
- */
- page = find_get_page(swap_address_space(ent), swp_offset(ent));
- entry->val = ent.val;
-
- return page;
-}
-#else
-static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
- pte_t ptent, swp_entry_t *entry)
-{
- return NULL;
-}
-#endif
-
-static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
- unsigned long addr, pte_t ptent)
-{
- unsigned long index;
- struct folio *folio;
-
- if (!vma->vm_file) /* anonymous vma */
- return NULL;
- if (!(mc.flags & MOVE_FILE))
- return NULL;
-
- /* folio is moved even if it's not RSS of this task(page-faulted). */
- /* shmem/tmpfs may report page out on swap: account for that too. */
- index = linear_page_index(vma, addr);
- folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
- if (IS_ERR(folio))
- return NULL;
- return folio_file_page(folio, index);
-}
-
-/**
- * mem_cgroup_move_account - move account of the folio
- * @folio: The folio.
- * @compound: charge the page as compound or small page
- * @from: mem_cgroup which the folio is moved from.
- * @to: mem_cgroup which the folio is moved to. @from != @to.
- *
- * The folio must be locked and not on the LRU.
- *
- * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
- * from old cgroup.
- */
-static int mem_cgroup_move_account(struct folio *folio,
- bool compound,
- struct mem_cgroup *from,
- struct mem_cgroup *to)
-{
- struct lruvec *from_vec, *to_vec;
- struct pglist_data *pgdat;
- unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1;
- int nid, ret;
-
- VM_BUG_ON(from == to);
- VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
- VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
- VM_BUG_ON(compound && !folio_test_large(folio));
-
- ret = -EINVAL;
- if (folio_memcg(folio) != from)
- goto out;
-
- pgdat = folio_pgdat(folio);
- from_vec = mem_cgroup_lruvec(from, pgdat);
- to_vec = mem_cgroup_lruvec(to, pgdat);
-
- folio_memcg_lock(folio);
-
- if (folio_test_anon(folio)) {
- if (folio_mapped(folio)) {
- __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
- __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
- if (folio_test_pmd_mappable(folio)) {
- __mod_lruvec_state(from_vec, NR_ANON_THPS,
- -nr_pages);
- __mod_lruvec_state(to_vec, NR_ANON_THPS,
- nr_pages);
- }
- }
- } else {
- __mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
- __mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);
-
- if (folio_test_swapbacked(folio)) {
- __mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages);
- __mod_lruvec_state(to_vec, NR_SHMEM, nr_pages);
- }
-
- if (folio_mapped(folio)) {
- __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
- __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
- }
-
- if (folio_test_dirty(folio)) {
- struct address_space *mapping = folio_mapping(folio);
-
- if (mapping_can_writeback(mapping)) {
- __mod_lruvec_state(from_vec, NR_FILE_DIRTY,
- -nr_pages);
- __mod_lruvec_state(to_vec, NR_FILE_DIRTY,
- nr_pages);
- }
- }
- }
-
-#ifdef CONFIG_SWAP
- if (folio_test_swapcache(folio)) {
- __mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages);
- __mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages);
- }
-#endif
- if (folio_test_writeback(folio)) {
- __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
- __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);
- }
-
- /*
- * All state has been migrated, let's switch to the new memcg.
- *
- * It is safe to change page's memcg here because the page
- * is referenced, charged, isolated, and locked: we can't race
- * with (un)charging, migration, LRU putback, or anything else
- * that would rely on a stable page's memory cgroup.
- *
- * Note that folio_memcg_lock is a memcg lock, not a page lock,
- * to save space. As soon as we switch page's memory cgroup to a
- * new memcg that isn't locked, the above state can change
- * concurrently again. Make sure we're truly done with it.
- */
- smp_mb();
-
- css_get(&to->css);
- css_put(&from->css);
-
- folio->memcg_data = (unsigned long)to;
-
- __folio_memcg_unlock(from);
-
- ret = 0;
- nid = folio_nid(folio);
-
- local_irq_disable();
- mem_cgroup_charge_statistics(to, nr_pages);
- memcg_check_events(to, nid);
- mem_cgroup_charge_statistics(from, -nr_pages);
- memcg_check_events(from, nid);
- local_irq_enable();
-out:
- return ret;
-}
-
-/**
- * get_mctgt_type - get target type of moving charge
- * @vma: the vma the pte to be checked belongs
- * @addr: the address corresponding to the pte to be checked
- * @ptent: the pte to be checked
- * @target: the pointer the target page or swap ent will be stored(can be NULL)
- *
- * Context: Called with pte lock held.
- * Return:
- * * MC_TARGET_NONE - If the pte is not a target for move charge.
- * * MC_TARGET_PAGE - If the page corresponding to this pte is a target for
- * move charge. If @target is not NULL, the folio is stored in target->folio
- * with extra refcnt taken (Caller should release it).
- * * MC_TARGET_SWAP - If the swap entry corresponding to this pte is a
- * target for charge migration. If @target is not NULL, the entry is
- * stored in target->ent.
- * * MC_TARGET_DEVICE - Like MC_TARGET_PAGE but page is device memory and
- * thus not on the lru. For now such page is charged like a regular page
- * would be as it is just special memory taking the place of a regular page.
- * See Documentations/vm/hmm.txt and include/linux/hmm.h
- */
-static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
- unsigned long addr, pte_t ptent, union mc_target *target)
-{
- struct page *page = NULL;
- struct folio *folio;
- enum mc_target_type ret = MC_TARGET_NONE;
- swp_entry_t ent = { .val = 0 };
-
- if (pte_present(ptent))
- page = mc_handle_present_pte(vma, addr, ptent);
- else if (pte_none_mostly(ptent))
- /*
- * PTE markers should be treated as a none pte here, separated
- * from other swap handling below.
- */
- page = mc_handle_file_pte(vma, addr, ptent);
- else if (is_swap_pte(ptent))
- page = mc_handle_swap_pte(vma, ptent, &ent);
-
- if (page)
- folio = page_folio(page);
- if (target && page) {
- if (!folio_trylock(folio)) {
- folio_put(folio);
- return ret;
- }
- /*
- * page_mapped() must be stable during the move. This
- * pte is locked, so if it's present, the page cannot
- * become unmapped. If it isn't, we have only partial
- * control over the mapped state: the page lock will
- * prevent new faults against pagecache and swapcache,
- * so an unmapped page cannot become mapped. However,
- * if the page is already mapped elsewhere, it can
- * unmap, and there is nothing we can do about it.
- * Alas, skip moving the page in this case.
- */
- if (!pte_present(ptent) && page_mapped(page)) {
- folio_unlock(folio);
- folio_put(folio);
- return ret;
- }
- }
-
- if (!page && !ent.val)
- return ret;
- if (page) {
- /*
- * Do only loose check w/o serialization.
- * mem_cgroup_move_account() checks the page is valid or
- * not under LRU exclusion.
- */
- if (folio_memcg(folio) == mc.from) {
- ret = MC_TARGET_PAGE;
- if (folio_is_device_private(folio) ||
- folio_is_device_coherent(folio))
- ret = MC_TARGET_DEVICE;
- if (target)
- target->folio = folio;
- }
- if (!ret || !target) {
- if (target)
- folio_unlock(folio);
- folio_put(folio);
- }
- }
- /*
- * There is a swap entry and a page doesn't exist or isn't charged.
- * But we cannot move a tail-page in a THP.
- */
- if (ent.val && !ret && (!page || !PageTransCompound(page)) &&
- mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
- ret = MC_TARGET_SWAP;
- if (target)
- target->ent = ent;
- }
- return ret;
-}
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-/*
- * We don't consider PMD mapped swapping or file mapped pages because THP does
- * not support them for now.
- * Caller should make sure that pmd_trans_huge(pmd) is true.
- */
-static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
- unsigned long addr, pmd_t pmd, union mc_target *target)
-{
- struct page *page = NULL;
- struct folio *folio;
- enum mc_target_type ret = MC_TARGET_NONE;
-
- if (unlikely(is_swap_pmd(pmd))) {
- VM_BUG_ON(thp_migration_supported() &&
- !is_pmd_migration_entry(pmd));
- return ret;
- }
- page = pmd_page(pmd);
- VM_BUG_ON_PAGE(!page || !PageHead(page), page);
- folio = page_folio(page);
- if (!(mc.flags & MOVE_ANON))
- return ret;
- if (folio_memcg(folio) == mc.from) {
- ret = MC_TARGET_PAGE;
- if (target) {
- folio_get(folio);
- if (!folio_trylock(folio)) {
- folio_put(folio);
- return MC_TARGET_NONE;
- }
- target->folio = folio;
- }
- }
- return ret;
-}
-#else
-static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
- unsigned long addr, pmd_t pmd, union mc_target *target)
-{
- return MC_TARGET_NONE;
-}
-#endif
-
-static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
- unsigned long addr, unsigned long end,
- struct mm_walk *walk)
-{
- struct vm_area_struct *vma = walk->vma;
- pte_t *pte;
- spinlock_t *ptl;
-
- ptl = pmd_trans_huge_lock(pmd, vma);
- if (ptl) {
- /*
- * Note their can not be MC_TARGET_DEVICE for now as we do not
- * support transparent huge page with MEMORY_DEVICE_PRIVATE but
- * this might change.
- */
- if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
- mc.precharge += HPAGE_PMD_NR;
- spin_unlock(ptl);
- return 0;
- }
-
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- if (!pte)
- return 0;
- for (; addr != end; pte++, addr += PAGE_SIZE)
- if (get_mctgt_type(vma, addr, ptep_get(pte), NULL))
- mc.precharge++; /* increment precharge temporarily */
- pte_unmap_unlock(pte - 1, ptl);
- cond_resched();
-
- return 0;
-}
-
-static const struct mm_walk_ops precharge_walk_ops = {
- .pmd_entry = mem_cgroup_count_precharge_pte_range,
- .walk_lock = PGWALK_RDLOCK,
-};
-
-static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
-{
- unsigned long precharge;
-
- mmap_read_lock(mm);
- walk_page_range(mm, 0, ULONG_MAX, &precharge_walk_ops, NULL);
- mmap_read_unlock(mm);
-
- precharge = mc.precharge;
- mc.precharge = 0;
-
- return precharge;
-}
-
-static int mem_cgroup_precharge_mc(struct mm_struct *mm)
-{
- unsigned long precharge = mem_cgroup_count_precharge(mm);
-
- VM_BUG_ON(mc.moving_task);
- mc.moving_task = current;
- return mem_cgroup_do_precharge(precharge);
-}
-
-/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
-static void __mem_cgroup_clear_mc(void)
-{
- struct mem_cgroup *from = mc.from;
- struct mem_cgroup *to = mc.to;
-
- /* we must uncharge all the leftover precharges from mc.to */
- if (mc.precharge) {
- mem_cgroup_cancel_charge(mc.to, mc.precharge);
- mc.precharge = 0;
- }
- /*
- * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
- * we must uncharge here.
- */
- if (mc.moved_charge) {
- mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
- mc.moved_charge = 0;
- }
- /* we must fixup refcnts and charges */
- if (mc.moved_swap) {
- /* uncharge swap account from the old cgroup */
- if (!mem_cgroup_is_root(mc.from))
- page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
-
- mem_cgroup_id_put_many(mc.from, mc.moved_swap);
-
- /*
- * we charged both to->memory and to->memsw, so we
- * should uncharge to->memory.
- */
- if (!mem_cgroup_is_root(mc.to))
- page_counter_uncharge(&mc.to->memory, mc.moved_swap);
-
- mc.moved_swap = 0;
- }
- memcg_oom_recover(from);
- memcg_oom_recover(to);
- wake_up_all(&mc.waitq);
-}
-
-static void mem_cgroup_clear_mc(void)
-{
- struct mm_struct *mm = mc.mm;
-
- /*
- * we must clear moving_task before waking up waiters at the end of
- * task migration.
- */
- mc.moving_task = NULL;
- __mem_cgroup_clear_mc();
- spin_lock(&mc.lock);
- mc.from = NULL;
- mc.to = NULL;
- mc.mm = NULL;
- spin_unlock(&mc.lock);
-
- mmput(mm);
-}
-
-static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
-{
- struct cgroup_subsys_state *css;
- struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
- struct mem_cgroup *from;
- struct task_struct *leader, *p;
- struct mm_struct *mm;
- unsigned long move_flags;
- int ret = 0;
-
- /* charge immigration isn't supported on the default hierarchy */
- if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
- return 0;
-
- /*
- * Multi-process migrations only happen on the default hierarchy
- * where charge immigration is not used. Perform charge
- * immigration if @tset contains a leader and whine if there are
- * multiple.
- */
- p = NULL;
- cgroup_taskset_for_each_leader(leader, css, tset) {
- WARN_ON_ONCE(p);
- p = leader;
- memcg = mem_cgroup_from_css(css);
- }
- if (!p)
- return 0;
-
- /*
- * We are now committed to this value whatever it is. Changes in this
- * tunable will only affect upcoming migrations, not the current one.
- * So we need to save it, and keep it going.
- */
- move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
- if (!move_flags)
- return 0;
-
- from = mem_cgroup_from_task(p);
-
- VM_BUG_ON(from == memcg);
-
- mm = get_task_mm(p);
- if (!mm)
- return 0;
- /* We move charges only when we move a owner of the mm */
- if (mm->owner == p) {
- VM_BUG_ON(mc.from);
- VM_BUG_ON(mc.to);
- VM_BUG_ON(mc.precharge);
- VM_BUG_ON(mc.moved_charge);
- VM_BUG_ON(mc.moved_swap);
-
- spin_lock(&mc.lock);
- mc.mm = mm;
- mc.from = from;
- mc.to = memcg;
- mc.flags = move_flags;
- spin_unlock(&mc.lock);
- /* We set mc.moving_task later */
-
- ret = mem_cgroup_precharge_mc(mm);
- if (ret)
- mem_cgroup_clear_mc();
- } else {
- mmput(mm);
- }
- return ret;
-}
-
-static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
-{
- if (mc.to)
- mem_cgroup_clear_mc();
-}
-
-static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
- unsigned long addr, unsigned long end,
- struct mm_walk *walk)
-{
- int ret = 0;
- struct vm_area_struct *vma = walk->vma;
- pte_t *pte;
- spinlock_t *ptl;
- enum mc_target_type target_type;
- union mc_target target;
- struct folio *folio;
-
- ptl = pmd_trans_huge_lock(pmd, vma);
- if (ptl) {
- if (mc.precharge < HPAGE_PMD_NR) {
- spin_unlock(ptl);
- return 0;
- }
- target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
- if (target_type == MC_TARGET_PAGE) {
- folio = target.folio;
- if (folio_isolate_lru(folio)) {
- if (!mem_cgroup_move_account(folio, true,
- mc.from, mc.to)) {
- mc.precharge -= HPAGE_PMD_NR;
- mc.moved_charge += HPAGE_PMD_NR;
- }
- folio_putback_lru(folio);
- }
- folio_unlock(folio);
- folio_put(folio);
- } else if (target_type == MC_TARGET_DEVICE) {
- folio = target.folio;
- if (!mem_cgroup_move_account(folio, true,
- mc.from, mc.to)) {
- mc.precharge -= HPAGE_PMD_NR;
- mc.moved_charge += HPAGE_PMD_NR;
- }
- folio_unlock(folio);
- folio_put(folio);
- }
- spin_unlock(ptl);
- return 0;
- }
-
-retry:
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- if (!pte)
- return 0;
- for (; addr != end; addr += PAGE_SIZE) {
- pte_t ptent = ptep_get(pte++);
- bool device = false;
- swp_entry_t ent;
-
- if (!mc.precharge)
- break;
-
- switch (get_mctgt_type(vma, addr, ptent, &target)) {
- case MC_TARGET_DEVICE:
- device = true;
- fallthrough;
- case MC_TARGET_PAGE:
- folio = target.folio;
- /*
- * We can have a part of the split pmd here. Moving it
- * can be done but it would be too convoluted so simply
- * ignore such a partial THP and keep it in original
- * memcg. There should be somebody mapping the head.
- */
- if (folio_test_large(folio))
- goto put;
- if (!device && !folio_isolate_lru(folio))
- goto put;
- if (!mem_cgroup_move_account(folio, false,
- mc.from, mc.to)) {
- mc.precharge--;
- /* we uncharge from mc.from later. */
- mc.moved_charge++;
- }
- if (!device)
- folio_putback_lru(folio);
-put: /* get_mctgt_type() gets & locks the page */
- folio_unlock(folio);
- folio_put(folio);
- break;
- case MC_TARGET_SWAP:
- ent = target.ent;
- if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
- mc.precharge--;
- mem_cgroup_id_get_many(mc.to, 1);
- /* we fixup other refcnts and charges later. */
- mc.moved_swap++;
- }
- break;
- default:
- break;
- }
- }
- pte_unmap_unlock(pte - 1, ptl);
- cond_resched();
-
- if (addr != end) {
- /*
- * We have consumed all precharges we got in can_attach().
- * We try charge one by one, but don't do any additional
- * charges to mc.to if we have failed in charge once in attach()
- * phase.
- */
- ret = mem_cgroup_do_precharge(1);
- if (!ret)
- goto retry;
- }
-
- return ret;
-}
-
-static const struct mm_walk_ops charge_walk_ops = {
- .pmd_entry = mem_cgroup_move_charge_pte_range,
- .walk_lock = PGWALK_RDLOCK,
-};
-
-static void mem_cgroup_move_charge(void)
-{
- lru_add_drain_all();
- /*
- * Signal folio_memcg_lock() to take the memcg's move_lock
- * while we're moving its pages to another memcg. Then wait
- * for already started RCU-only updates to finish.
- */
- atomic_inc(&mc.from->moving_account);
- synchronize_rcu();
-retry:
- if (unlikely(!mmap_read_trylock(mc.mm))) {
- /*
- * Someone who are holding the mmap_lock might be waiting in
- * waitq. So we cancel all extra charges, wake up all waiters,
- * and retry. Because we cancel precharges, we might not be able
- * to move enough charges, but moving charge is a best-effort
- * feature anyway, so it wouldn't be a big problem.
- */
- __mem_cgroup_clear_mc();
- cond_resched();
- goto retry;
- }
- /*
- * When we have consumed all precharges and failed in doing
- * additional charge, the page walk just aborts.
- */
- walk_page_range(mc.mm, 0, ULONG_MAX, &charge_walk_ops, NULL);
- mmap_read_unlock(mc.mm);
- atomic_dec(&mc.from->moving_account);
-}
-
-static void mem_cgroup_move_task(void)
-{
- if (mc.to) {
- mem_cgroup_move_charge();
- mem_cgroup_clear_mc();
- }
-}
-
-#else /* !CONFIG_MMU */
-static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
-{
- return 0;
-}
-static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
-{
-}
-static void mem_cgroup_move_task(void)
-{
-}
-#endif
-
#ifdef CONFIG_MEMCG_KMEM
static void mem_cgroup_fork(struct task_struct *task)
{
--
2.43.2
Move legacy cgroup v1 memory controller interfaces and corresponding
code into memcontrol-v1.c.
Signed-off-by: Roman Gushchin <[email protected]>
---
mm/internal.h | 15 +-
mm/memcontrol-v1.c | 733 +++++++++++++++++++++++++++++++++++++++++++-
mm/memcontrol.c | 748 +--------------------------------------------
3 files changed, 751 insertions(+), 745 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index 79104cfc08a9..533aa999a450 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -13,6 +13,7 @@
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/cgroup-defs.h>
#include <linux/tracepoint-defs.h>
struct folio_batch;
@@ -1579,6 +1580,14 @@ enum mem_cgroup_events_target {
bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
enum mem_cgroup_events_target target);
+int memory_stat_show(struct seq_file *m, void *v);
+unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx);
+unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item);
+unsigned long memcg_page_state_local_output(struct mem_cgroup *memcg, int item);
+unsigned long memcg_events(struct mem_cgroup *memcg, int event);
+unsigned long memcg_events_local(struct mem_cgroup *memcg, int event);
+void drain_all_stock(struct mem_cgroup *root_memcg);
+
/* Memory cgroups v1-specific definitions */
void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid);
void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg);
@@ -1606,8 +1615,10 @@ enum res_type {
void memcg_check_events(struct mem_cgroup *memcg, int nid);
void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
-ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off);
+void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg);
+extern struct cftype memsw_files[];
+extern struct cftype mem_cgroup_legacy_files[];
+
#endif /* __MM_INTERNAL_H */
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 5bf0b62cd7b5..cd711f6b8386 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -10,6 +10,7 @@
#include <linux/mm_inline.h>
#include <linux/swap_cgroup.h>
#include <linux/file.h>
+#include <linux/seq_buf.h>
#include "internal.h"
#include "swap.h"
@@ -111,6 +112,18 @@ struct mem_cgroup_eventfd_list {
extern spinlock_t memcg_oom_lock;
+enum {
+ RES_USAGE,
+ RES_LIMIT,
+ RES_MAX_USAGE,
+ RES_FAILCNT,
+ RES_SOFT_LIMIT,
+};
+
+#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
+#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff)
+#define MEMFILE_ATTR(val) ((val) & 0xffff)
+
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz,
unsigned long new_usage_in_excess)
@@ -1801,8 +1814,8 @@ static void memcg_event_ptable_queue_proc(struct file *file,
* Input must be in format '<event_fd> <control_fd> <args>'.
* Interpretation of args is defined by control file implementation.
*/
-ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
+static ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
{
struct cgroup_subsys_state *css = of_css(of);
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
@@ -1946,6 +1959,722 @@ ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf,
return ret;
}
+static DEFINE_MUTEX(memcg_max_mutex);
+
+static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
+ unsigned long max, bool memsw)
+{
+ bool enlarge = false;
+ bool drained = false;
+ int ret;
+ bool limits_invariant;
+ struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
+
+ do {
+ if (signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+
+ mutex_lock(&memcg_max_mutex);
+ /*
+ * Make sure that the new limit (memsw or memory limit) doesn't
+ * break our basic invariant rule memory.max <= memsw.max.
+ */
+ limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) :
+ max <= memcg->memsw.max;
+ if (!limits_invariant) {
+ mutex_unlock(&memcg_max_mutex);
+ ret = -EINVAL;
+ break;
+ }
+ if (max > counter->max)
+ enlarge = true;
+ ret = page_counter_set_max(counter, max);
+ mutex_unlock(&memcg_max_mutex);
+
+ if (!ret)
+ break;
+
+ if (!drained) {
+ drain_all_stock(memcg);
+ drained = true;
+ continue;
+ }
+
+ if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
+ memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP, NULL)) {
+ ret = -EBUSY;
+ break;
+ }
+ } while (true);
+
+ if (!ret && enlarge)
+ memcg_oom_recover(memcg);
+
+ return ret;
+}
+
+/*
+ * Reclaims as many pages from the given memcg as possible.
+ *
+ * Caller is responsible for holding css reference for memcg.
+ */
+static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
+{
+ int nr_retries = MAX_RECLAIM_RETRIES;
+
+ /* we call try-to-free pages for make this cgroup empty */
+ lru_add_drain_all();
+
+ drain_all_stock(memcg);
+
+ /* try to free all pages in this cgroup */
+ while (nr_retries && page_counter_read(&memcg->memory)) {
+ if (signal_pending(current))
+ return -EINTR;
+
+ if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
+ MEMCG_RECLAIM_MAY_SWAP, NULL))
+ nr_retries--;
+ }
+
+ return 0;
+}
+
+static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+ if (mem_cgroup_is_root(memcg))
+ return -EINVAL;
+ return mem_cgroup_force_empty(memcg) ?: nbytes;
+}
+
+static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return 1;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val == 1)
+ return 0;
+
+ pr_warn_once("Non-hierarchical mode is deprecated. "
+ "Please report your usecase to [email protected] if you "
+ "depend on this functionality.\n");
+
+ return -EINVAL;
+}
+
+static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+ struct page_counter *counter;
+
+ switch (MEMFILE_TYPE(cft->private)) {
+ case _MEM:
+ counter = &memcg->memory;
+ break;
+ case _MEMSWAP:
+ counter = &memcg->memsw;
+ break;
+ case _KMEM:
+ counter = &memcg->kmem;
+ break;
+ case _TCP:
+ counter = &memcg->tcpmem;
+ break;
+ default:
+ BUG();
+ }
+
+ switch (MEMFILE_ATTR(cft->private)) {
+ case RES_USAGE:
+ if (counter == &memcg->memory)
+ return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
+ if (counter == &memcg->memsw)
+ return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
+ return (u64)page_counter_read(counter) * PAGE_SIZE;
+ case RES_LIMIT:
+ return (u64)counter->max * PAGE_SIZE;
+ case RES_MAX_USAGE:
+ return (u64)counter->watermark * PAGE_SIZE;
+ case RES_FAILCNT:
+ return counter->failcnt;
+ case RES_SOFT_LIMIT:
+ return (u64)READ_ONCE(memcg->soft_limit) * PAGE_SIZE;
+ default:
+ BUG();
+ }
+}
+
+/*
+ * This function doesn't do anything useful. Its only job is to provide a read
+ * handler for a file so that cgroup_file_mode() will add read permissions.
+ */
+static int mem_cgroup_dummy_seq_show(__always_unused struct seq_file *m,
+ __always_unused void *v)
+{
+ return -EINVAL;
+}
+
+static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
+{
+ int ret;
+
+ mutex_lock(&memcg_max_mutex);
+
+ ret = page_counter_set_max(&memcg->tcpmem, max);
+ if (ret)
+ goto out;
+
+ if (!memcg->tcpmem_active) {
+ /*
+ * The active flag needs to be written after the static_key
+ * update. This is what guarantees that the socket activation
+ * function is the last one to run. See mem_cgroup_sk_alloc()
+ * for details, and note that we don't mark any socket as
+ * belonging to this memcg until that flag is up.
+ *
+ * We need to do this, because static_keys will span multiple
+ * sites, but we can't control their order. If we mark a socket
+ * as accounted, but the accounting functions are not patched in
+ * yet, we'll lose accounting.
+ *
+ * We never race with the readers in mem_cgroup_sk_alloc(),
+ * because when this value change, the code to process it is not
+ * patched in yet.
+ */
+ static_branch_inc(&memcg_sockets_enabled_key);
+ memcg->tcpmem_active = true;
+ }
+out:
+ mutex_unlock(&memcg_max_mutex);
+ return ret;
+}
+
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
+static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ unsigned long nr_pages;
+ int ret;
+
+ buf = strstrip(buf);
+ ret = page_counter_memparse(buf, "-1", &nr_pages);
+ if (ret)
+ return ret;
+
+ switch (MEMFILE_ATTR(of_cft(of)->private)) {
+ case RES_LIMIT:
+ if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
+ ret = -EINVAL;
+ break;
+ }
+ switch (MEMFILE_TYPE(of_cft(of)->private)) {
+ case _MEM:
+ ret = mem_cgroup_resize_max(memcg, nr_pages, false);
+ break;
+ case _MEMSWAP:
+ ret = mem_cgroup_resize_max(memcg, nr_pages, true);
+ break;
+ case _KMEM:
+ pr_warn_once("kmem.limit_in_bytes is deprecated and will be removed. "
+ "Writing any value to this file has no effect. "
+ "Please report your usecase to [email protected] if you "
+ "depend on this functionality.\n");
+ ret = 0;
+ break;
+ case _TCP:
+ ret = memcg_update_tcp_max(memcg, nr_pages);
+ break;
+ }
+ break;
+ case RES_SOFT_LIMIT:
+ if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ ret = -EOPNOTSUPP;
+ } else {
+ WRITE_ONCE(memcg->soft_limit, nr_pages);
+ ret = 0;
+ }
+ break;
+ }
+ return ret ?: nbytes;
+}
+
+static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ struct page_counter *counter;
+
+ switch (MEMFILE_TYPE(of_cft(of)->private)) {
+ case _MEM:
+ counter = &memcg->memory;
+ break;
+ case _MEMSWAP:
+ counter = &memcg->memsw;
+ break;
+ case _KMEM:
+ counter = &memcg->kmem;
+ break;
+ case _TCP:
+ counter = &memcg->tcpmem;
+ break;
+ default:
+ BUG();
+ }
+
+ switch (MEMFILE_ATTR(of_cft(of)->private)) {
+ case RES_MAX_USAGE:
+ page_counter_reset_watermark(counter);
+ break;
+ case RES_FAILCNT:
+ counter->failcnt = 0;
+ break;
+ default:
+ BUG();
+ }
+
+ return nbytes;
+}
+
+#ifdef CONFIG_NUMA
+
+#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
+#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
+#define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
+
+static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+ int nid, unsigned int lru_mask, bool tree)
+{
+ struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
+ unsigned long nr = 0;
+ enum lru_list lru;
+
+ VM_BUG_ON((unsigned)nid >= nr_node_ids);
+
+ for_each_lru(lru) {
+ if (!(BIT(lru) & lru_mask))
+ continue;
+ if (tree)
+ nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru);
+ else
+ nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru);
+ }
+ return nr;
+}
+
+static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
+ unsigned int lru_mask,
+ bool tree)
+{
+ unsigned long nr = 0;
+ enum lru_list lru;
+
+ for_each_lru(lru) {
+ if (!(BIT(lru) & lru_mask))
+ continue;
+ if (tree)
+ nr += memcg_page_state(memcg, NR_LRU_BASE + lru);
+ else
+ nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru);
+ }
+ return nr;
+}
+
+static int memcg_numa_stat_show(struct seq_file *m, void *v)
+{
+ struct numa_stat {
+ const char *name;
+ unsigned int lru_mask;
+ };
+
+ static const struct numa_stat stats[] = {
+ { "total", LRU_ALL },
+ { "file", LRU_ALL_FILE },
+ { "anon", LRU_ALL_ANON },
+ { "unevictable", BIT(LRU_UNEVICTABLE) },
+ };
+ const struct numa_stat *stat;
+ int nid;
+ struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+ mem_cgroup_flush_stats(memcg);
+
+ for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+ seq_printf(m, "%s=%lu", stat->name,
+ mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
+ false));
+ for_each_node_state(nid, N_MEMORY)
+ seq_printf(m, " N%d=%lu", nid,
+ mem_cgroup_node_nr_lru_pages(memcg, nid,
+ stat->lru_mask, false));
+ seq_putc(m, '\n');
+ }
+
+ for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+
+ seq_printf(m, "hierarchical_%s=%lu", stat->name,
+ mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
+ true));
+ for_each_node_state(nid, N_MEMORY)
+ seq_printf(m, " N%d=%lu", nid,
+ mem_cgroup_node_nr_lru_pages(memcg, nid,
+ stat->lru_mask, true));
+ seq_putc(m, '\n');
+ }
+
+ return 0;
+}
+#endif /* CONFIG_NUMA */
+
+static const unsigned int memcg1_stats[] = {
+ NR_FILE_PAGES,
+ NR_ANON_MAPPED,
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ NR_ANON_THPS,
+#endif
+ NR_SHMEM,
+ NR_FILE_MAPPED,
+ NR_FILE_DIRTY,
+ NR_WRITEBACK,
+ WORKINGSET_REFAULT_ANON,
+ WORKINGSET_REFAULT_FILE,
+#ifdef CONFIG_SWAP
+ MEMCG_SWAP,
+ NR_SWAPCACHE,
+#endif
+};
+
+static const char *const memcg1_stat_names[] = {
+ "cache",
+ "rss",
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ "rss_huge",
+#endif
+ "shmem",
+ "mapped_file",
+ "dirty",
+ "writeback",
+ "workingset_refault_anon",
+ "workingset_refault_file",
+#ifdef CONFIG_SWAP
+ "swap",
+ "swapcached",
+#endif
+};
+
+/* Universal VM events cgroup1 shows, original sort order */
+static const unsigned int memcg1_events[] = {
+ PGPGIN,
+ PGPGOUT,
+ PGFAULT,
+ PGMAJFAULT,
+};
+
+void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
+{
+ unsigned long memory, memsw;
+ struct mem_cgroup *mi;
+ unsigned int i;
+
+ BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
+
+ mem_cgroup_flush_stats(memcg);
+
+ for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+ unsigned long nr;
+
+ nr = memcg_page_state_local_output(memcg, memcg1_stats[i]);
+ seq_buf_printf(s, "%s %lu\n", memcg1_stat_names[i], nr);
+ }
+
+ for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
+ seq_buf_printf(s, "%s %lu\n", vm_event_name(memcg1_events[i]),
+ memcg_events_local(memcg, memcg1_events[i]));
+
+ for (i = 0; i < NR_LRU_LISTS; i++)
+ seq_buf_printf(s, "%s %lu\n", lru_list_name(i),
+ memcg_page_state_local(memcg, NR_LRU_BASE + i) *
+ PAGE_SIZE);
+
+ /* Hierarchical information */
+ memory = memsw = PAGE_COUNTER_MAX;
+ for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
+ memory = min(memory, READ_ONCE(mi->memory.max));
+ memsw = min(memsw, READ_ONCE(mi->memsw.max));
+ }
+ seq_buf_printf(s, "hierarchical_memory_limit %llu\n",
+ (u64)memory * PAGE_SIZE);
+ seq_buf_printf(s, "hierarchical_memsw_limit %llu\n",
+ (u64)memsw * PAGE_SIZE);
+
+ for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+ unsigned long nr;
+
+ nr = memcg_page_state_output(memcg, memcg1_stats[i]);
+ seq_buf_printf(s, "total_%s %llu\n", memcg1_stat_names[i],
+ (u64)nr);
+ }
+
+ for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
+ seq_buf_printf(s, "total_%s %llu\n",
+ vm_event_name(memcg1_events[i]),
+ (u64)memcg_events(memcg, memcg1_events[i]));
+
+ for (i = 0; i < NR_LRU_LISTS; i++)
+ seq_buf_printf(s, "total_%s %llu\n", lru_list_name(i),
+ (u64)memcg_page_state(memcg, NR_LRU_BASE + i) *
+ PAGE_SIZE);
+
+#ifdef CONFIG_DEBUG_VM
+ {
+ pg_data_t *pgdat;
+ struct mem_cgroup_per_node *mz;
+ unsigned long anon_cost = 0;
+ unsigned long file_cost = 0;
+
+ for_each_online_pgdat(pgdat) {
+ mz = memcg->nodeinfo[pgdat->node_id];
+
+ anon_cost += mz->lruvec.anon_cost;
+ file_cost += mz->lruvec.file_cost;
+ }
+ seq_buf_printf(s, "anon_cost %lu\n", anon_cost);
+ seq_buf_printf(s, "file_cost %lu\n", file_cost);
+ }
+#endif
+}
+
+static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+ return mem_cgroup_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+ if (val > MAX_SWAPPINESS)
+ return -EINVAL;
+
+ if (!mem_cgroup_is_root(memcg))
+ WRITE_ONCE(memcg->swappiness, val);
+ else
+ WRITE_ONCE(vm_swappiness, val);
+
+ return 0;
+}
+
+static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
+
+ seq_printf(sf, "oom_kill_disable %d\n", READ_ONCE(memcg->oom_kill_disable));
+ seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
+ seq_printf(sf, "oom_kill %lu\n",
+ atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
+ return 0;
+}
+
+static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+ /* cannot set to root cgroup and only 0 and 1 are allowed */
+ if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1)))
+ return -EINVAL;
+
+ WRITE_ONCE(memcg->oom_kill_disable, val);
+ if (!val)
+ memcg_oom_recover(memcg);
+
+ return 0;
+}
+
+#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
+static int mem_cgroup_slab_show(struct seq_file *m, void *p)
+{
+ /*
+ * Deprecated.
+ * Please, take a look at tools/cgroup/memcg_slabinfo.py .
+ */
+ return 0;
+}
+#endif
+
+struct cftype mem_cgroup_legacy_files[] = {
+ {
+ .name = "usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "max_usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
+ .write = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "soft_limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+ .write = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "failcnt",
+ .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "stat",
+ .seq_show = memory_stat_show,
+ },
+ {
+ .name = "force_empty",
+ .write = mem_cgroup_force_empty_write,
+ },
+ {
+ .name = "use_hierarchy",
+ .write_u64 = mem_cgroup_hierarchy_write,
+ .read_u64 = mem_cgroup_hierarchy_read,
+ },
+ {
+ .name = "cgroup.event_control", /* XXX: for compat */
+ .write = memcg_write_event_control,
+ .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
+ },
+ {
+ .name = "swappiness",
+ .read_u64 = mem_cgroup_swappiness_read,
+ .write_u64 = mem_cgroup_swappiness_write,
+ },
+ {
+ .name = "move_charge_at_immigrate",
+ .read_u64 = mem_cgroup_move_charge_read,
+ .write_u64 = mem_cgroup_move_charge_write,
+ },
+ {
+ .name = "oom_control",
+ .seq_show = mem_cgroup_oom_control_read,
+ .write_u64 = mem_cgroup_oom_control_write,
+ },
+ {
+ .name = "pressure_level",
+ .seq_show = mem_cgroup_dummy_seq_show,
+ },
+#ifdef CONFIG_NUMA
+ {
+ .name = "numa_stat",
+ .seq_show = memcg_numa_stat_show,
+ },
+#endif
+ {
+ .name = "kmem.limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
+ .write = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.failcnt",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.max_usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
+ {
+ .name = "kmem.slabinfo",
+ .seq_show = mem_cgroup_slab_show,
+ },
+#endif
+ {
+ .name = "kmem.tcp.limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
+ .write = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.tcp.usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_TCP, RES_USAGE),
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.tcp.failcnt",
+ .private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "kmem.tcp.max_usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ { }, /* terminate */
+};
+
+struct cftype memsw_files[] = {
+ {
+ .name = "memsw.usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "memsw.max_usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "memsw.limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
+ .write = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
+ .name = "memsw.failcnt",
+ .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
+ .write = mem_cgroup_reset,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ { }, /* terminate */
+};
+
void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg)
{
struct mem_cgroup_event *event, *tmp;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7c1a4ea0e9b5..cd7e5f67d9b5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -95,10 +95,6 @@ static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
-#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
-#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff)
-#define MEMFILE_ATTR(val) ((val) & 0xffff)
-
static inline bool task_is_dying(void)
{
return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
@@ -675,7 +671,7 @@ void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
}
/* idx can be of type enum memcg_stat_item or node_stat_item. */
-static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
+unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
{
long x;
int i = memcg_stats_index(idx);
@@ -827,7 +823,7 @@ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
memcg_stats_unlock();
}
-static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
+unsigned long memcg_events(struct mem_cgroup *memcg, int event)
{
int i = memcg_events_index(event);
@@ -837,7 +833,7 @@ static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
return READ_ONCE(memcg->vmstats->events[i]);
}
-static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
+unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
{
int i = memcg_events_index(event);
@@ -1422,15 +1418,13 @@ static int memcg_page_state_output_unit(int item)
}
}
-static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg,
- int item)
+unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item)
{
return memcg_page_state(memcg, item) *
memcg_page_state_output_unit(item);
}
-static inline unsigned long memcg_page_state_local_output(
- struct mem_cgroup *memcg, int item)
+unsigned long memcg_page_state_local_output(struct mem_cgroup *memcg, int item)
{
return memcg_page_state_local(memcg, item) *
memcg_page_state_output_unit(item);
@@ -1489,8 +1483,6 @@ static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
WARN_ON_ONCE(seq_buf_has_overflowed(s));
}
-static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
-
static void memory_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
@@ -2077,7 +2069,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
* Drains all per-CPU charge caches for given root_memcg resp. subtree
* of the hierarchy under it.
*/
-static void drain_all_stock(struct mem_cgroup *root_memcg)
+void drain_all_stock(struct mem_cgroup *root_memcg)
{
int cpu, curcpu;
@@ -3333,119 +3325,6 @@ void split_page_memcg(struct page *head, int old_order, int new_order)
css_get_many(&memcg->css, old_nr / new_nr - 1);
}
-static DEFINE_MUTEX(memcg_max_mutex);
-
-static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
- unsigned long max, bool memsw)
-{
- bool enlarge = false;
- bool drained = false;
- int ret;
- bool limits_invariant;
- struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
-
- do {
- if (signal_pending(current)) {
- ret = -EINTR;
- break;
- }
-
- mutex_lock(&memcg_max_mutex);
- /*
- * Make sure that the new limit (memsw or memory limit) doesn't
- * break our basic invariant rule memory.max <= memsw.max.
- */
- limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) :
- max <= memcg->memsw.max;
- if (!limits_invariant) {
- mutex_unlock(&memcg_max_mutex);
- ret = -EINVAL;
- break;
- }
- if (max > counter->max)
- enlarge = true;
- ret = page_counter_set_max(counter, max);
- mutex_unlock(&memcg_max_mutex);
-
- if (!ret)
- break;
-
- if (!drained) {
- drain_all_stock(memcg);
- drained = true;
- continue;
- }
-
- if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
- memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP, NULL)) {
- ret = -EBUSY;
- break;
- }
- } while (true);
-
- if (!ret && enlarge)
- memcg_oom_recover(memcg);
-
- return ret;
-}
-
-/*
- * Reclaims as many pages from the given memcg as possible.
- *
- * Caller is responsible for holding css reference for memcg.
- */
-static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
-{
- int nr_retries = MAX_RECLAIM_RETRIES;
-
- /* we call try-to-free pages for make this cgroup empty */
- lru_add_drain_all();
-
- drain_all_stock(memcg);
-
- /* try to free all pages in this cgroup */
- while (nr_retries && page_counter_read(&memcg->memory)) {
- if (signal_pending(current))
- return -EINTR;
-
- if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
- MEMCG_RECLAIM_MAY_SWAP, NULL))
- nr_retries--;
- }
-
- return 0;
-}
-
-static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
-
- if (mem_cgroup_is_root(memcg))
- return -EINVAL;
- return mem_cgroup_force_empty(memcg) ?: nbytes;
-}
-
-static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return 1;
-}
-
-static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- if (val == 1)
- return 0;
-
- pr_warn_once("Non-hierarchical mode is deprecated. "
- "Please report your usecase to [email protected] if you "
- "depend on this functionality.\n");
-
- return -EINVAL;
-}
-
unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
{
unsigned long val;
@@ -3468,67 +3347,6 @@ unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
return val;
}
-enum {
- RES_USAGE,
- RES_LIMIT,
- RES_MAX_USAGE,
- RES_FAILCNT,
- RES_SOFT_LIMIT,
-};
-
-static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- struct page_counter *counter;
-
- switch (MEMFILE_TYPE(cft->private)) {
- case _MEM:
- counter = &memcg->memory;
- break;
- case _MEMSWAP:
- counter = &memcg->memsw;
- break;
- case _KMEM:
- counter = &memcg->kmem;
- break;
- case _TCP:
- counter = &memcg->tcpmem;
- break;
- default:
- BUG();
- }
-
- switch (MEMFILE_ATTR(cft->private)) {
- case RES_USAGE:
- if (counter == &memcg->memory)
- return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
- if (counter == &memcg->memsw)
- return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
- return (u64)page_counter_read(counter) * PAGE_SIZE;
- case RES_LIMIT:
- return (u64)counter->max * PAGE_SIZE;
- case RES_MAX_USAGE:
- return (u64)counter->watermark * PAGE_SIZE;
- case RES_FAILCNT:
- return counter->failcnt;
- case RES_SOFT_LIMIT:
- return (u64)READ_ONCE(memcg->soft_limit) * PAGE_SIZE;
- default:
- BUG();
- }
-}
-
-/*
- * This function doesn't do anything useful. Its only job is to provide a read
- * handler for a file so that cgroup_file_mode() will add read permissions.
- */
-static int mem_cgroup_dummy_seq_show(__always_unused struct seq_file *m,
- __always_unused void *v)
-{
- return -EINVAL;
-}
-
#ifdef CONFIG_MEMCG_KMEM
static int memcg_online_kmem(struct mem_cgroup *memcg)
{
@@ -3590,390 +3408,6 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
}
#endif /* CONFIG_MEMCG_KMEM */
-static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
-{
- int ret;
-
- mutex_lock(&memcg_max_mutex);
-
- ret = page_counter_set_max(&memcg->tcpmem, max);
- if (ret)
- goto out;
-
- if (!memcg->tcpmem_active) {
- /*
- * The active flag needs to be written after the static_key
- * update. This is what guarantees that the socket activation
- * function is the last one to run. See mem_cgroup_sk_alloc()
- * for details, and note that we don't mark any socket as
- * belonging to this memcg until that flag is up.
- *
- * We need to do this, because static_keys will span multiple
- * sites, but we can't control their order. If we mark a socket
- * as accounted, but the accounting functions are not patched in
- * yet, we'll lose accounting.
- *
- * We never race with the readers in mem_cgroup_sk_alloc(),
- * because when this value change, the code to process it is not
- * patched in yet.
- */
- static_branch_inc(&memcg_sockets_enabled_key);
- memcg->tcpmem_active = true;
- }
-out:
- mutex_unlock(&memcg_max_mutex);
- return ret;
-}
-
-/*
- * The user of this function is...
- * RES_LIMIT.
- */
-static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
- unsigned long nr_pages;
- int ret;
-
- buf = strstrip(buf);
- ret = page_counter_memparse(buf, "-1", &nr_pages);
- if (ret)
- return ret;
-
- switch (MEMFILE_ATTR(of_cft(of)->private)) {
- case RES_LIMIT:
- if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
- ret = -EINVAL;
- break;
- }
- switch (MEMFILE_TYPE(of_cft(of)->private)) {
- case _MEM:
- ret = mem_cgroup_resize_max(memcg, nr_pages, false);
- break;
- case _MEMSWAP:
- ret = mem_cgroup_resize_max(memcg, nr_pages, true);
- break;
- case _KMEM:
- pr_warn_once("kmem.limit_in_bytes is deprecated and will be removed. "
- "Writing any value to this file has no effect. "
- "Please report your usecase to [email protected] if you "
- "depend on this functionality.\n");
- ret = 0;
- break;
- case _TCP:
- ret = memcg_update_tcp_max(memcg, nr_pages);
- break;
- }
- break;
- case RES_SOFT_LIMIT:
- if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
- ret = -EOPNOTSUPP;
- } else {
- WRITE_ONCE(memcg->soft_limit, nr_pages);
- ret = 0;
- }
- break;
- }
- return ret ?: nbytes;
-}
-
-static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
- struct page_counter *counter;
-
- switch (MEMFILE_TYPE(of_cft(of)->private)) {
- case _MEM:
- counter = &memcg->memory;
- break;
- case _MEMSWAP:
- counter = &memcg->memsw;
- break;
- case _KMEM:
- counter = &memcg->kmem;
- break;
- case _TCP:
- counter = &memcg->tcpmem;
- break;
- default:
- BUG();
- }
-
- switch (MEMFILE_ATTR(of_cft(of)->private)) {
- case RES_MAX_USAGE:
- page_counter_reset_watermark(counter);
- break;
- case RES_FAILCNT:
- counter->failcnt = 0;
- break;
- default:
- BUG();
- }
-
- return nbytes;
-}
-
-#ifdef CONFIG_NUMA
-
-#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
-#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
-#define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
-
-static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
- int nid, unsigned int lru_mask, bool tree)
-{
- struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
- unsigned long nr = 0;
- enum lru_list lru;
-
- VM_BUG_ON((unsigned)nid >= nr_node_ids);
-
- for_each_lru(lru) {
- if (!(BIT(lru) & lru_mask))
- continue;
- if (tree)
- nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru);
- else
- nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru);
- }
- return nr;
-}
-
-static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
- unsigned int lru_mask,
- bool tree)
-{
- unsigned long nr = 0;
- enum lru_list lru;
-
- for_each_lru(lru) {
- if (!(BIT(lru) & lru_mask))
- continue;
- if (tree)
- nr += memcg_page_state(memcg, NR_LRU_BASE + lru);
- else
- nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru);
- }
- return nr;
-}
-
-static int memcg_numa_stat_show(struct seq_file *m, void *v)
-{
- struct numa_stat {
- const char *name;
- unsigned int lru_mask;
- };
-
- static const struct numa_stat stats[] = {
- { "total", LRU_ALL },
- { "file", LRU_ALL_FILE },
- { "anon", LRU_ALL_ANON },
- { "unevictable", BIT(LRU_UNEVICTABLE) },
- };
- const struct numa_stat *stat;
- int nid;
- struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-
- mem_cgroup_flush_stats(memcg);
-
- for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
- seq_printf(m, "%s=%lu", stat->name,
- mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
- false));
- for_each_node_state(nid, N_MEMORY)
- seq_printf(m, " N%d=%lu", nid,
- mem_cgroup_node_nr_lru_pages(memcg, nid,
- stat->lru_mask, false));
- seq_putc(m, '\n');
- }
-
- for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
-
- seq_printf(m, "hierarchical_%s=%lu", stat->name,
- mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
- true));
- for_each_node_state(nid, N_MEMORY)
- seq_printf(m, " N%d=%lu", nid,
- mem_cgroup_node_nr_lru_pages(memcg, nid,
- stat->lru_mask, true));
- seq_putc(m, '\n');
- }
-
- return 0;
-}
-#endif /* CONFIG_NUMA */
-
-static const unsigned int memcg1_stats[] = {
- NR_FILE_PAGES,
- NR_ANON_MAPPED,
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- NR_ANON_THPS,
-#endif
- NR_SHMEM,
- NR_FILE_MAPPED,
- NR_FILE_DIRTY,
- NR_WRITEBACK,
- WORKINGSET_REFAULT_ANON,
- WORKINGSET_REFAULT_FILE,
-#ifdef CONFIG_SWAP
- MEMCG_SWAP,
- NR_SWAPCACHE,
-#endif
-};
-
-static const char *const memcg1_stat_names[] = {
- "cache",
- "rss",
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- "rss_huge",
-#endif
- "shmem",
- "mapped_file",
- "dirty",
- "writeback",
- "workingset_refault_anon",
- "workingset_refault_file",
-#ifdef CONFIG_SWAP
- "swap",
- "swapcached",
-#endif
-};
-
-/* Universal VM events cgroup1 shows, original sort order */
-static const unsigned int memcg1_events[] = {
- PGPGIN,
- PGPGOUT,
- PGFAULT,
- PGMAJFAULT,
-};
-
-static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
-{
- unsigned long memory, memsw;
- struct mem_cgroup *mi;
- unsigned int i;
-
- BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
-
- mem_cgroup_flush_stats(memcg);
-
- for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
- unsigned long nr;
-
- nr = memcg_page_state_local_output(memcg, memcg1_stats[i]);
- seq_buf_printf(s, "%s %lu\n", memcg1_stat_names[i], nr);
- }
-
- for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
- seq_buf_printf(s, "%s %lu\n", vm_event_name(memcg1_events[i]),
- memcg_events_local(memcg, memcg1_events[i]));
-
- for (i = 0; i < NR_LRU_LISTS; i++)
- seq_buf_printf(s, "%s %lu\n", lru_list_name(i),
- memcg_page_state_local(memcg, NR_LRU_BASE + i) *
- PAGE_SIZE);
-
- /* Hierarchical information */
- memory = memsw = PAGE_COUNTER_MAX;
- for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
- memory = min(memory, READ_ONCE(mi->memory.max));
- memsw = min(memsw, READ_ONCE(mi->memsw.max));
- }
- seq_buf_printf(s, "hierarchical_memory_limit %llu\n",
- (u64)memory * PAGE_SIZE);
- seq_buf_printf(s, "hierarchical_memsw_limit %llu\n",
- (u64)memsw * PAGE_SIZE);
-
- for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
- unsigned long nr;
-
- nr = memcg_page_state_output(memcg, memcg1_stats[i]);
- seq_buf_printf(s, "total_%s %llu\n", memcg1_stat_names[i],
- (u64)nr);
- }
-
- for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
- seq_buf_printf(s, "total_%s %llu\n",
- vm_event_name(memcg1_events[i]),
- (u64)memcg_events(memcg, memcg1_events[i]));
-
- for (i = 0; i < NR_LRU_LISTS; i++)
- seq_buf_printf(s, "total_%s %llu\n", lru_list_name(i),
- (u64)memcg_page_state(memcg, NR_LRU_BASE + i) *
- PAGE_SIZE);
-
-#ifdef CONFIG_DEBUG_VM
- {
- pg_data_t *pgdat;
- struct mem_cgroup_per_node *mz;
- unsigned long anon_cost = 0;
- unsigned long file_cost = 0;
-
- for_each_online_pgdat(pgdat) {
- mz = memcg->nodeinfo[pgdat->node_id];
-
- anon_cost += mz->lruvec.anon_cost;
- file_cost += mz->lruvec.file_cost;
- }
- seq_buf_printf(s, "anon_cost %lu\n", anon_cost);
- seq_buf_printf(s, "file_cost %lu\n", file_cost);
- }
-#endif
-}
-
-static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-
- return mem_cgroup_swappiness(memcg);
-}
-
-static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-
- if (val > MAX_SWAPPINESS)
- return -EINVAL;
-
- if (!mem_cgroup_is_root(memcg))
- WRITE_ONCE(memcg->swappiness, val);
- else
- WRITE_ONCE(vm_swappiness, val);
-
- return 0;
-}
-
-static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
-
- seq_printf(sf, "oom_kill_disable %d\n", READ_ONCE(memcg->oom_kill_disable));
- seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
- seq_printf(sf, "oom_kill %lu\n",
- atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
- return 0;
-}
-
-static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-
- /* cannot set to root cgroup and only 0 and 1 are allowed */
- if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1)))
- return -EINVAL;
-
- WRITE_ONCE(memcg->oom_kill_disable, val);
- if (!val)
- memcg_oom_recover(memcg);
-
- return 0;
-}
-
#ifdef CONFIG_CGROUP_WRITEBACK
#include <trace/events/writeback.h>
@@ -4187,147 +3621,6 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
#endif /* CONFIG_CGROUP_WRITEBACK */
-#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
-static int mem_cgroup_slab_show(struct seq_file *m, void *p)
-{
- /*
- * Deprecated.
- * Please, take a look at tools/cgroup/memcg_slabinfo.py .
- */
- return 0;
-}
-#endif
-
-static int memory_stat_show(struct seq_file *m, void *v);
-
-static struct cftype mem_cgroup_legacy_files[] = {
- {
- .name = "usage_in_bytes",
- .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "max_usage_in_bytes",
- .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "limit_in_bytes",
- .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
- .write = mem_cgroup_write,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "soft_limit_in_bytes",
- .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
- .write = mem_cgroup_write,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "failcnt",
- .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "stat",
- .seq_show = memory_stat_show,
- },
- {
- .name = "force_empty",
- .write = mem_cgroup_force_empty_write,
- },
- {
- .name = "use_hierarchy",
- .write_u64 = mem_cgroup_hierarchy_write,
- .read_u64 = mem_cgroup_hierarchy_read,
- },
- {
- .name = "cgroup.event_control", /* XXX: for compat */
- .write = memcg_write_event_control,
- .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
- },
- {
- .name = "swappiness",
- .read_u64 = mem_cgroup_swappiness_read,
- .write_u64 = mem_cgroup_swappiness_write,
- },
- {
- .name = "move_charge_at_immigrate",
- .read_u64 = mem_cgroup_move_charge_read,
- .write_u64 = mem_cgroup_move_charge_write,
- },
- {
- .name = "oom_control",
- .seq_show = mem_cgroup_oom_control_read,
- .write_u64 = mem_cgroup_oom_control_write,
- },
- {
- .name = "pressure_level",
- .seq_show = mem_cgroup_dummy_seq_show,
- },
-#ifdef CONFIG_NUMA
- {
- .name = "numa_stat",
- .seq_show = memcg_numa_stat_show,
- },
-#endif
- {
- .name = "kmem.limit_in_bytes",
- .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
- .write = mem_cgroup_write,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.usage_in_bytes",
- .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.failcnt",
- .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.max_usage_in_bytes",
- .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
-#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
- {
- .name = "kmem.slabinfo",
- .seq_show = mem_cgroup_slab_show,
- },
-#endif
- {
- .name = "kmem.tcp.limit_in_bytes",
- .private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
- .write = mem_cgroup_write,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.tcp.usage_in_bytes",
- .private = MEMFILE_PRIVATE(_TCP, RES_USAGE),
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.tcp.failcnt",
- .private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "kmem.tcp.max_usage_in_bytes",
- .private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- { }, /* terminate */
-};
-
/*
* Private memory cgroup IDR
*
@@ -5119,7 +4412,7 @@ static int memory_events_local_show(struct seq_file *m, void *v)
return 0;
}
-static int memory_stat_show(struct seq_file *m, void *v)
+int memory_stat_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
@@ -6351,33 +5644,6 @@ static struct cftype swap_files[] = {
{ } /* terminate */
};
-static struct cftype memsw_files[] = {
- {
- .name = "memsw.usage_in_bytes",
- .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "memsw.max_usage_in_bytes",
- .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "memsw.limit_in_bytes",
- .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
- .write = mem_cgroup_write,
- .read_u64 = mem_cgroup_read_u64,
- },
- {
- .name = "memsw.failcnt",
- .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
- .write = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read_u64,
- },
- { }, /* terminate */
-};
-
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
/**
* obj_cgroup_may_zswap - check if this cgroup can zswap
--
2.43.2
Put members of struct mem_cgroup which are related to the legacy
cgroup v1 memory controller under the CONFIG_MEMCG_V1 config option.
Also, put the initialization and some trivial access code under the
same option.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 33 ++++++++++++++++++++-------------
mm/memcontrol.c | 25 +++++++++++++++++++------
2 files changed, 39 insertions(+), 19 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d2a4145b1909..4347d6889fa0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -182,9 +182,11 @@ struct mem_cgroup {
struct page_counter memsw; /* v1 only */
};
+#ifdef CONFIG_MEMCG_V1
/* Legacy consumer-oriented counters */
struct page_counter kmem; /* v1 only */
struct page_counter tcpmem; /* v1 only */
+#endif
/* Range enforcement for interrupt charges */
struct work_struct high_work;
@@ -198,24 +200,15 @@ struct mem_cgroup {
*/
bool zswap_writeback;
#endif
-
- unsigned long soft_limit;
-
- /* vmpressure notifications */
- struct vmpressure vmpressure;
+ int swappiness;
/*
* Should the OOM killer kill all belonging tasks, had it kill one?
*/
bool oom_group;
- /* protected by memcg_oom_lock */
- bool oom_lock;
- int under_oom;
-
- int swappiness;
- /* OOM-Killer disable */
- int oom_kill_disable;
+ /* vmpressure notifications */
+ struct vmpressure vmpressure;
/* memory.events and memory.events.local */
struct cgroup_file events_file;
@@ -224,6 +217,16 @@ struct mem_cgroup {
/* handle for "memory.swap.events" */
struct cgroup_file swap_events_file;
+#ifdef CONFIG_MEMCG_V1
+ unsigned long soft_limit;
+
+ /* protected by memcg_oom_lock */
+ bool oom_lock;
+ int under_oom;
+
+ /* OOM-Killer disable */
+ int oom_kill_disable;
+
/* protect arrays of thresholds */
struct mutex thresholds_lock;
@@ -244,6 +247,7 @@ struct mem_cgroup {
/* taken only while moving_account > 0 */
spinlock_t move_lock;
unsigned long move_lock_flags;
+#endif
CACHELINE_PADDING(_pad1_);
@@ -279,12 +283,13 @@ struct mem_cgroup {
#endif
CACHELINE_PADDING(_pad2_);
-
+#ifdef CONFIG_MEMCG_V1
/*
* set > 0 if pages under this cgroup are moving to other cgroup.
*/
atomic_t moving_account;
struct task_struct *move_lock_task;
+#endif
struct memcg_vmstats_percpu __percpu *vmstats_percpu;
@@ -294,9 +299,11 @@ struct mem_cgroup {
struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT];
#endif
+#ifdef CONFIG_MEMCG_V1
/* List of events which userspace want to receive */
struct list_head event_list;
spinlock_t event_list_lock;
+#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
struct deferred_split deferred_split_queue;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d5883f748330..4dcfd1ef5d61 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1537,6 +1537,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->swap)),
K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt);
+#ifdef CONFIG_MEMCG_V1
else {
pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memsw)),
@@ -1545,6 +1546,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
K((u64)page_counter_read(&memcg->kmem)),
K((u64)memcg->kmem.max), memcg->kmem.failcnt);
}
+#endif
pr_info("Memory cgroup stats for ");
pr_cont_cgroup_path(memcg->css.cgroup);
@@ -2650,12 +2652,14 @@ struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio)
static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
{
mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
+#ifdef CONFIG_MEMCG_V1
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
if (nr_pages > 0)
page_counter_charge(&memcg->kmem, nr_pages);
else
page_counter_uncharge(&memcg->kmem, -nr_pages);
}
+#endif
}
@@ -3602,12 +3606,14 @@ static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent)
goto fail;
INIT_WORK(&memcg->high_work, high_work_func);
+#ifdef CONFIG_MEMCG_V1
INIT_LIST_HEAD(&memcg->oom_notify);
mutex_init(&memcg->thresholds_lock);
spin_lock_init(&memcg->move_lock);
- vmpressure_init(&memcg->vmpressure);
INIT_LIST_HEAD(&memcg->event_list);
spin_lock_init(&memcg->event_list_lock);
+#endif
+ vmpressure_init(&memcg->vmpressure);
memcg->socket_pressure = jiffies;
#ifdef CONFIG_MEMCG_KMEM
memcg->kmemcg_id = -1;
@@ -3654,20 +3660,22 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
if (parent) {
WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent));
- WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable));
-
page_counter_init(&memcg->memory, &parent->memory);
page_counter_init(&memcg->swap, &parent->swap);
+#ifdef CONFIG_MEMCG_V1
page_counter_init(&memcg->kmem, &parent->kmem);
page_counter_init(&memcg->tcpmem, &parent->tcpmem);
+ WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable));
+#endif
} else {
init_memcg_stats();
init_memcg_events();
page_counter_init(&memcg->memory, NULL);
page_counter_init(&memcg->swap, NULL);
+#ifdef CONFIG_MEMCG_V1
page_counter_init(&memcg->kmem, NULL);
page_counter_init(&memcg->tcpmem, NULL);
-
+#endif
root_mem_cgroup = memcg;
return &memcg->css;
}
@@ -3802,12 +3810,14 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
+#ifdef CONFIG_MEMCG_V1
page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
+ mem_cgroup_soft_limit_reset(memcg);
+#endif
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
- mem_cgroup_soft_limit_reset(memcg);
page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
memcg_wb_domain_size_changed(memcg);
}
@@ -5018,6 +5028,7 @@ void mem_cgroup_sk_free(struct sock *sk)
bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
gfp_t gfp_mask)
{
+#ifdef CONFIG_MEMCG_V1
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
struct page_counter *fail;
@@ -5032,6 +5043,7 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
}
return false;
}
+#endif
if (try_charge(memcg, gfp_mask, nr_pages) == 0) {
mod_memcg_state(memcg, MEMCG_SOCK, nr_pages);
@@ -5048,11 +5060,12 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
*/
void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
{
+#ifdef CONFIG_MEMCG_V1
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
page_counter_uncharge(&memcg->tcpmem, nr_pages);
return;
}
-
+#endif
mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages);
refill_stock(memcg, nr_pages);
--
2.43.2
Cgroup v1 supported a complicated OOM handling mechanism in userspace,
which is not supported by cgroup v2. Let's move the corresponding code
into memcontrol-v1.c.
Aside from mechanical code movement this patch introduces two new
functions: mem_cgroup_v1_oom_prepare() and mem_cgroup_v1_oom_finish().
Those are implementing cgroup v1-specific parts of the common memcg
OOM handling path.
Signed-off-by: Roman Gushchin <[email protected]>
---
mm/internal.h | 4 +-
mm/memcontrol-v1.c | 229 +++++++++++++++++++++++++++++++++++++++++++++
mm/memcontrol.c | 220 +------------------------------------------
3 files changed, 234 insertions(+), 219 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index 533aa999a450..1b94e2169e19 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1614,8 +1614,10 @@ enum res_type {
};
void memcg_check_events(struct mem_cgroup *memcg, int nid);
-void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
+bool mem_cgroup_v1_oom_prepare(struct mem_cgroup *memcg, gfp_t mask, int order,
+ bool *locked);
+void mem_cgroup_v1_oom_finish(struct mem_cgroup *memcg, bool *locked);
void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg);
extern struct cftype memsw_files[];
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index cd711f6b8386..15356bbbc058 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -2675,6 +2675,235 @@ struct cftype memsw_files[] = {
{ }, /* terminate */
};
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map memcg_oom_lock_dep_map = {
+ .name = "memcg_oom_lock",
+};
+#endif
+
+DEFINE_SPINLOCK(memcg_oom_lock);
+
+/*
+ * Check OOM-Killer is already running under our hierarchy.
+ * If someone is running, return false.
+ */
+static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter, *failed = NULL;
+
+ spin_lock(&memcg_oom_lock);
+
+ for_each_mem_cgroup_tree(iter, memcg) {
+ if (iter->oom_lock) {
+ /*
+ * this subtree of our hierarchy is already locked
+ * so we cannot give a lock.
+ */
+ failed = iter;
+ mem_cgroup_iter_break(memcg, iter);
+ break;
+ } else
+ iter->oom_lock = true;
+ }
+
+ if (failed) {
+ /*
+ * OK, we failed to lock the whole subtree so we have
+ * to clean up what we set up to the failing subtree
+ */
+ for_each_mem_cgroup_tree(iter, memcg) {
+ if (iter == failed) {
+ mem_cgroup_iter_break(memcg, iter);
+ break;
+ }
+ iter->oom_lock = false;
+ }
+ } else
+ mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
+
+ spin_unlock(&memcg_oom_lock);
+
+ return !failed;
+}
+
+static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ spin_lock(&memcg_oom_lock);
+ mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
+ for_each_mem_cgroup_tree(iter, memcg)
+ iter->oom_lock = false;
+ spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ spin_lock(&memcg_oom_lock);
+ for_each_mem_cgroup_tree(iter, memcg)
+ iter->under_oom++;
+ spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ /*
+ * Be careful about under_oom underflows because a child memcg
+ * could have been added after mem_cgroup_mark_under_oom.
+ */
+ spin_lock(&memcg_oom_lock);
+ for_each_mem_cgroup_tree(iter, memcg)
+ if (iter->under_oom > 0)
+ iter->under_oom--;
+ spin_unlock(&memcg_oom_lock);
+}
+
+bool mem_cgroup_v1_oom_prepare(struct mem_cgroup *memcg, gfp_t mask, int order,
+ bool *locked)
+{
+ /*
+ * We are in the middle of the charge context here, so we
+ * don't want to block when potentially sitting on a callstack
+ * that holds all kinds of filesystem and mm locks.
+ *
+ * cgroup1 allows disabling the OOM killer and waiting for outside
+ * handling until the charge can succeed; remember the context and put
+ * the task to sleep at the end of the page fault when all locks are
+ * released.
+ *
+ * On the other hand, in-kernel OOM killer allows for an async victim
+ * memory reclaim (oom_reaper) and that means that we are not solely
+ * relying on the oom victim to make a forward progress and we can
+ * invoke the oom killer here.
+ *
+ * Please note that mem_cgroup_out_of_memory might fail to find a
+ * victim and then we have to bail out from the charge path.
+ */
+ if (READ_ONCE(memcg->oom_kill_disable)) {
+ if (current->in_user_fault) {
+ css_get(&memcg->css);
+ current->memcg_in_oom = memcg;
+ current->memcg_oom_gfp_mask = mask;
+ current->memcg_oom_order = order;
+ }
+ return false;
+ }
+
+ mem_cgroup_mark_under_oom(memcg);
+
+ *locked = mem_cgroup_oom_trylock(memcg);
+
+ if (*locked)
+ mem_cgroup_oom_notify(memcg);
+
+ mem_cgroup_unmark_under_oom(memcg);
+
+ return true;
+}
+
+void mem_cgroup_v1_oom_finish(struct mem_cgroup *memcg, bool *locked)
+{
+ if (*locked)
+ mem_cgroup_oom_unlock(memcg);
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
+
+struct oom_wait_info {
+ struct mem_cgroup *memcg;
+ wait_queue_entry_t wait;
+};
+
+static int memcg_oom_wake_function(wait_queue_entry_t *wait,
+ unsigned mode, int sync, void *arg)
+{
+ struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
+ struct mem_cgroup *oom_wait_memcg;
+ struct oom_wait_info *oom_wait_info;
+
+ oom_wait_info = container_of(wait, struct oom_wait_info, wait);
+ oom_wait_memcg = oom_wait_info->memcg;
+
+ if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
+ !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, arg);
+}
+
+void memcg_oom_recover(struct mem_cgroup *memcg)
+{
+ /*
+ * For the following lockless ->under_oom test, the only required
+ * guarantee is that it must see the state asserted by an OOM when
+ * this function is called as a result of userland actions
+ * triggered by the notification of the OOM. This is trivially
+ * achieved by invoking mem_cgroup_mark_under_oom() before
+ * triggering notification.
+ */
+ if (memcg && memcg->under_oom)
+ __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
+}
+
+/**
+ * mem_cgroup_oom_synchronize - complete memcg OOM handling
+ * @handle: actually kill/wait or just clean up the OOM state
+ *
+ * This has to be called at the end of a page fault if the memcg OOM
+ * handler was enabled.
+ *
+ * Memcg supports userspace OOM handling where failed allocations must
+ * sleep on a waitqueue until the userspace task resolves the
+ * situation. Sleeping directly in the charge context with all kinds
+ * of locks held is not a good idea, instead we remember an OOM state
+ * in the task and mem_cgroup_oom_synchronize() has to be called at
+ * the end of the page fault to complete the OOM handling.
+ *
+ * Returns %true if an ongoing memcg OOM situation was detected and
+ * completed, %false otherwise.
+ */
+bool mem_cgroup_oom_synchronize(bool handle)
+{
+ struct mem_cgroup *memcg = current->memcg_in_oom;
+ struct oom_wait_info owait;
+ bool locked;
+
+ /* OOM is global, do not handle */
+ if (!memcg)
+ return false;
+
+ if (!handle)
+ goto cleanup;
+
+ owait.memcg = memcg;
+ owait.wait.flags = 0;
+ owait.wait.func = memcg_oom_wake_function;
+ owait.wait.private = current;
+ INIT_LIST_HEAD(&owait.wait.entry);
+
+ prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+ mem_cgroup_mark_under_oom(memcg);
+
+ locked = mem_cgroup_oom_trylock(memcg);
+
+ if (locked)
+ mem_cgroup_oom_notify(memcg);
+
+ schedule();
+ mem_cgroup_unmark_under_oom(memcg);
+ finish_wait(&memcg_oom_waitq, &owait.wait);
+
+ if (locked)
+ mem_cgroup_oom_unlock(memcg);
+cleanup:
+ current->memcg_in_oom = NULL;
+ css_put(&memcg->css);
+ return true;
+}
+
void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg)
{
struct mem_cgroup_event *event, *tmp;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index cd7e5f67d9b5..805efc98ae12 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1610,130 +1610,6 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
return ret;
}
-#ifdef CONFIG_LOCKDEP
-static struct lockdep_map memcg_oom_lock_dep_map = {
- .name = "memcg_oom_lock",
-};
-#endif
-
-DEFINE_SPINLOCK(memcg_oom_lock);
-
-/*
- * Check OOM-Killer is already running under our hierarchy.
- * If someone is running, return false.
- */
-static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter, *failed = NULL;
-
- spin_lock(&memcg_oom_lock);
-
- for_each_mem_cgroup_tree(iter, memcg) {
- if (iter->oom_lock) {
- /*
- * this subtree of our hierarchy is already locked
- * so we cannot give a lock.
- */
- failed = iter;
- mem_cgroup_iter_break(memcg, iter);
- break;
- } else
- iter->oom_lock = true;
- }
-
- if (failed) {
- /*
- * OK, we failed to lock the whole subtree so we have
- * to clean up what we set up to the failing subtree
- */
- for_each_mem_cgroup_tree(iter, memcg) {
- if (iter == failed) {
- mem_cgroup_iter_break(memcg, iter);
- break;
- }
- iter->oom_lock = false;
- }
- } else
- mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
-
- spin_unlock(&memcg_oom_lock);
-
- return !failed;
-}
-
-static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- spin_lock(&memcg_oom_lock);
- mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
- for_each_mem_cgroup_tree(iter, memcg)
- iter->oom_lock = false;
- spin_unlock(&memcg_oom_lock);
-}
-
-static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- spin_lock(&memcg_oom_lock);
- for_each_mem_cgroup_tree(iter, memcg)
- iter->under_oom++;
- spin_unlock(&memcg_oom_lock);
-}
-
-static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- /*
- * Be careful about under_oom underflows because a child memcg
- * could have been added after mem_cgroup_mark_under_oom.
- */
- spin_lock(&memcg_oom_lock);
- for_each_mem_cgroup_tree(iter, memcg)
- if (iter->under_oom > 0)
- iter->under_oom--;
- spin_unlock(&memcg_oom_lock);
-}
-
-static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
-
-struct oom_wait_info {
- struct mem_cgroup *memcg;
- wait_queue_entry_t wait;
-};
-
-static int memcg_oom_wake_function(wait_queue_entry_t *wait,
- unsigned mode, int sync, void *arg)
-{
- struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
- struct mem_cgroup *oom_wait_memcg;
- struct oom_wait_info *oom_wait_info;
-
- oom_wait_info = container_of(wait, struct oom_wait_info, wait);
- oom_wait_memcg = oom_wait_info->memcg;
-
- if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
- !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
- return 0;
- return autoremove_wake_function(wait, mode, sync, arg);
-}
-
-void memcg_oom_recover(struct mem_cgroup *memcg)
-{
- /*
- * For the following lockless ->under_oom test, the only required
- * guarantee is that it must see the state asserted by an OOM when
- * this function is called as a result of userland actions
- * triggered by the notification of the OOM. This is trivially
- * achieved by invoking mem_cgroup_mark_under_oom() before
- * triggering notification.
- */
- if (memcg && memcg->under_oom)
- __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
-}
-
/*
* Returns true if successfully killed one or more processes. Though in some
* corner cases it can return true even without killing any process.
@@ -1747,106 +1623,14 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
memcg_memory_event(memcg, MEMCG_OOM);
- /*
- * We are in the middle of the charge context here, so we
- * don't want to block when potentially sitting on a callstack
- * that holds all kinds of filesystem and mm locks.
- *
- * cgroup1 allows disabling the OOM killer and waiting for outside
- * handling until the charge can succeed; remember the context and put
- * the task to sleep at the end of the page fault when all locks are
- * released.
- *
- * On the other hand, in-kernel OOM killer allows for an async victim
- * memory reclaim (oom_reaper) and that means that we are not solely
- * relying on the oom victim to make a forward progress and we can
- * invoke the oom killer here.
- *
- * Please note that mem_cgroup_out_of_memory might fail to find a
- * victim and then we have to bail out from the charge path.
- */
- if (READ_ONCE(memcg->oom_kill_disable)) {
- if (current->in_user_fault) {
- css_get(&memcg->css);
- current->memcg_in_oom = memcg;
- current->memcg_oom_gfp_mask = mask;
- current->memcg_oom_order = order;
- }
+ if (!mem_cgroup_v1_oom_prepare(memcg, mask, order, &locked))
return false;
- }
-
- mem_cgroup_mark_under_oom(memcg);
-
- locked = mem_cgroup_oom_trylock(memcg);
-
- if (locked)
- mem_cgroup_oom_notify(memcg);
-
- mem_cgroup_unmark_under_oom(memcg);
ret = mem_cgroup_out_of_memory(memcg, mask, order);
-
- if (locked)
- mem_cgroup_oom_unlock(memcg);
+ mem_cgroup_v1_oom_finish(memcg, &locked);
return ret;
}
-/**
- * mem_cgroup_oom_synchronize - complete memcg OOM handling
- * @handle: actually kill/wait or just clean up the OOM state
- *
- * This has to be called at the end of a page fault if the memcg OOM
- * handler was enabled.
- *
- * Memcg supports userspace OOM handling where failed allocations must
- * sleep on a waitqueue until the userspace task resolves the
- * situation. Sleeping directly in the charge context with all kinds
- * of locks held is not a good idea, instead we remember an OOM state
- * in the task and mem_cgroup_oom_synchronize() has to be called at
- * the end of the page fault to complete the OOM handling.
- *
- * Returns %true if an ongoing memcg OOM situation was detected and
- * completed, %false otherwise.
- */
-bool mem_cgroup_oom_synchronize(bool handle)
-{
- struct mem_cgroup *memcg = current->memcg_in_oom;
- struct oom_wait_info owait;
- bool locked;
-
- /* OOM is global, do not handle */
- if (!memcg)
- return false;
-
- if (!handle)
- goto cleanup;
-
- owait.memcg = memcg;
- owait.wait.flags = 0;
- owait.wait.func = memcg_oom_wake_function;
- owait.wait.private = current;
- INIT_LIST_HEAD(&owait.wait.entry);
-
- prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
- mem_cgroup_mark_under_oom(memcg);
-
- locked = mem_cgroup_oom_trylock(memcg);
-
- if (locked)
- mem_cgroup_oom_notify(memcg);
-
- schedule();
- mem_cgroup_unmark_under_oom(memcg);
- finish_wait(&memcg_oom_waitq, &owait.wait);
-
- if (locked)
- mem_cgroup_oom_unlock(memcg);
-cleanup:
- current->memcg_in_oom = NULL;
- css_put(&memcg->css);
- return true;
-}
-
/**
* mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM
* @victim: task to be killed by the OOM killer
--
2.43.2
Put legacy cgroup v1 memory controller code under a new
CONFIG_MEMCG_V1 config option. The option is turned on by default
as of now to keep things backward-compatible. But users who have fully
adopted cgroup v2 and don't use cgroup v1 anymore can turn it off
and benefit from a smaller memory footprint and small CPU wins on
some memcg paths.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 13 ++++++++++---
init/Kconfig | 7 +++++++
mm/Makefile | 3 ++-
mm/internal.h | 24 +++++++++++++++++++++++-
mm/memcontrol.c | 10 +++++++---
5 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index fc4aaa73aa5e..d2a4145b1909 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -954,7 +954,14 @@ static inline bool task_in_memcg_oom(struct task_struct *p)
return p->memcg_in_oom;
}
+#ifdef CONFIG_MEMCG_V1
bool mem_cgroup_oom_synchronize(bool wait);
+#else
+static inline bool mem_cgroup_oom_synchronize(bool wait)
+{
+ return false;
+}
+#endif
struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
struct mem_cgroup *oom_domain);
void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);
@@ -1872,7 +1879,7 @@ static inline bool mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg)
/* Cgroup v1-specific definitions */
-#ifdef CONFIG_MEMCG
+#ifdef CONFIG_MEMCG_V1
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
gfp_t gfp_mask,
unsigned long *total_scanned);
@@ -1895,7 +1902,7 @@ static inline void mem_cgroup_unlock_pages(void)
{
rcu_read_unlock();
}
-#else /* CONFIG_MEMCG */
+#else /* CONFIG_MEMCG_V1 */
static inline
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
@@ -1924,6 +1931,6 @@ static inline void mem_cgroup_unlock_pages(void)
{
rcu_read_unlock();
}
-#endif /* CONFIG_MEMCG */
+#endif /* CONFIG_MEMCG_V1 */
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/init/Kconfig b/init/Kconfig
index 10d4a638d9ae..ce9b78279627 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -969,6 +969,13 @@ config MEMCG
help
Provides control over the memory footprint of tasks in a cgroup.
+config MEMCG_V1
+ bool "Legacy memory controller"
+ depends on MEMCG
+ default y
+ help
+ Legacy cgroup v1 memory controller.
+
config MEMCG_KMEM
bool
depends on MEMCG
diff --git a/mm/Makefile b/mm/Makefile
index c717a3ee612e..4e2fe5f6637c 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -96,7 +96,8 @@ obj-$(CONFIG_NUMA) += memory-tiers.o
obj-$(CONFIG_DEVICE_MIGRATION) += migrate_device.o
obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o
obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
-obj-$(CONFIG_MEMCG) += memcontrol.o memcontrol-v1.o vmpressure.o
+obj-$(CONFIG_MEMCG_V1) += memcontrol-v1.o
+obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
ifdef CONFIG_SWAP
obj-$(CONFIG_MEMCG) += swap_cgroup.o
endif
diff --git a/mm/internal.h b/mm/internal.h
index 1b94e2169e19..8c5640ef85f8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1559,7 +1559,6 @@ static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
}
void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages);
-void memcg_oom_recover(struct mem_cgroup *memcg);
void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n);
void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n);
@@ -1589,6 +1588,7 @@ unsigned long memcg_events_local(struct mem_cgroup *memcg, int event);
void drain_all_stock(struct mem_cgroup *root_memcg);
/* Memory cgroups v1-specific definitions */
+#ifdef CONFIG_MEMCG_V1
void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid);
void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg);
void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg);
@@ -1618,9 +1618,31 @@ void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
bool mem_cgroup_v1_oom_prepare(struct mem_cgroup *memcg, gfp_t mask, int order,
bool *locked);
void mem_cgroup_v1_oom_finish(struct mem_cgroup *memcg, bool *locked);
+void memcg_oom_recover(struct mem_cgroup *memcg);
void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg);
extern struct cftype memsw_files[];
extern struct cftype mem_cgroup_legacy_files[];
+#else /* CONFIG_MEMCG_V1 */
+static inline void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) {}
+static inline void mem_cgroup_soft_limit_reset(struct mem_cgroup *memcg) {}
+
+static inline bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
+{
+ return false;
+}
+
+static inline void memcg_check_events(struct mem_cgroup *memcg, int nid) {}
+static inline void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) {}
+static inline bool mem_cgroup_v1_oom_prepare(struct mem_cgroup *memcg, gfp_t mask, int order,
+ bool *locked)
+{
+ return true;
+}
+static inline void mem_cgroup_v1_oom_finish(struct mem_cgroup *memcg, bool *locked) {}
+static inline void memcg_oom_recover(struct mem_cgroup *memcg) {}
+static inline void mem_cgroup_v1_offline_memcg(struct mem_cgroup *memcg) {}
+#endif /* CONFIG_MEMCG_V1 */
+
#endif /* __MM_INTERNAL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 805efc98ae12..d5883f748330 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4435,18 +4435,20 @@ struct cgroup_subsys memory_cgrp_subsys = {
.css_free = mem_cgroup_css_free,
.css_reset = mem_cgroup_css_reset,
.css_rstat_flush = mem_cgroup_css_rstat_flush,
- .can_attach = mem_cgroup_can_attach,
#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM)
.attach = mem_cgroup_attach,
#endif
- .cancel_attach = mem_cgroup_cancel_attach,
- .post_attach = mem_cgroup_move_task,
#ifdef CONFIG_MEMCG_KMEM
.fork = mem_cgroup_fork,
.exit = mem_cgroup_exit,
#endif
.dfl_cftypes = memory_files,
+#ifdef CONFIG_MEMCG_V1
+ .can_attach = mem_cgroup_can_attach,
+ .cancel_attach = mem_cgroup_cancel_attach,
+ .post_attach = mem_cgroup_move_task,
.legacy_cftypes = mem_cgroup_legacy_files,
+#endif
.early_init = 0,
};
@@ -5618,7 +5620,9 @@ static int __init mem_cgroup_swap_init(void)
return 0;
WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files));
+#ifdef CONFIG_MEMCG_V1
WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files));
+#endif
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, zswap_files));
#endif
--
2.43.2
Guard cgroup v1-related members of task_struct under the CONFIG_MEMCG_V1
config option, so that users who adopted cgroup v2 don't have to waste
the memory for fields which are never accessed.
Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 11 ++++++++++-
include/linux/sched.h | 5 ++++-
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4347d6889fa0..8005d749f8fc 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -944,6 +944,7 @@ void mem_cgroup_print_oom_context(struct mem_cgroup *memcg,
void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg);
+#ifdef CONFIG_MEMCG_V1
static inline void mem_cgroup_enter_user_fault(void)
{
WARN_ON(current->in_user_fault);
@@ -961,9 +962,17 @@ static inline bool task_in_memcg_oom(struct task_struct *p)
return p->memcg_in_oom;
}
-#ifdef CONFIG_MEMCG_V1
bool mem_cgroup_oom_synchronize(bool wait);
#else
+static inline void mem_cgroup_enter_user_fault(void) {}
+
+static inline void mem_cgroup_exit_user_fault(void) {}
+
+static inline bool task_in_memcg_oom(struct task_struct *p)
+{
+ return false;
+}
+
static inline bool mem_cgroup_oom_synchronize(bool wait)
{
return false;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4118b3f959c3..2ecdeb7588e3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1446,11 +1446,14 @@ struct task_struct {
unsigned int kcov_softirq;
#endif
-#ifdef CONFIG_MEMCG
+
+#ifdef CONFIG_MEMCG_V1
struct mem_cgroup *memcg_in_oom;
gfp_t memcg_oom_gfp_mask;
int memcg_oom_order;
+#endif
+#ifdef CONFIG_MEMCG
/* Number of pages to reclaim on returning to userland: */
unsigned int memcg_nr_pages_over_high;
--
2.43.2
On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> Cgroups v2 have been around for a while and many users have fully adopted them,
> so they never use cgroups v1 features and functionality. Yet they have to "pay"
> for the cgroup v1 support anyway:
> 1) the kernel binary contains useless cgroup v1 code,
> 2) some common structures like task_struct and mem_cgroup have never used
> cgroup v1-specific members,
> 3) some code paths have additional checks which are not needed.
>
> Cgroup v1's memory controller has a number of features that are not supported
> by cgroup v2 and their implementation is pretty much self contained.
> Most notably, these features are: soft limit reclaim, oom handling in userspace,
> complicated event notification system, charge migration.
>
> Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> intervened with generic and cgroup v2-specific code. It's a burden on
> developers and maintainers.
>
> This patchset aims to solve these problems by:
> 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> mm/internal.h header
> 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> 5) putting unused struct memory_cgroup and task_struct members under
> CONFIG_MEMCG_V1 as well.
>
> This is an RFC version, which is not 100% polished yet, so but it would be great
> to discuss and agree on the overall approach.
>
> Some open questions, opinions are appreciated:
> 1) I consider renaming non-static functions in memcontrol-v1.c to have
> mem_cgroup_v1_ prefix. Is this a good idea?
> 2) Do we want to extend it beyond the memory controller? Should
> 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> mm/internal.h? Or mm/memcontrol-v1.h.
>
Hi Roman,
A very timely and important topic and we should definitely talk about it
during LSFMM as well. I have been thinking about this problem for quite
sometime and I am getting more and more convinced that we should aim to
completely deprecate memcg-v1.
More specifically:
1. What are the memcg-v1 features which have no alternative in memcg-v2
and are blocker for memcg-v1 users? (setting aside the cgroup v2
structual restrictions)
2. What are unused memcg-v1 features which we should start deprecating?
IMO we should systematically start deprecating memcg-v1 features and
start unblocking the users stuck on memcg-v1.
Now regarding the proposal in this series, I think it can be a first
step but should not give an impression that we are done. The only
concern I have is the potential of "out of sight, out of mind" situation
with this change but if we keep the momentum of deprecation of memcg-v1
it should be fine.
I have CCed Greg and David from Google to get their opinion on what
memcg-v1 features are blocker for their memcg-v2 migration and if they
have concern in deprecation of memcg-v1 features.
Anyone else still on memcg-v1, please do provide your input.
thanks,
Shakeel
On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> Cgroups v2 have been around for a while and many users have fully adopted them,
> so they never use cgroups v1 features and functionality. Yet they have to "pay"
> for the cgroup v1 support anyway:
> 1) the kernel binary contains useless cgroup v1 code,
> 2) some common structures like task_struct and mem_cgroup have never used
> cgroup v1-specific members,
> 3) some code paths have additional checks which are not needed.
>
> Cgroup v1's memory controller has a number of features that are not supported
> by cgroup v2 and their implementation is pretty much self contained.
> Most notably, these features are: soft limit reclaim, oom handling in userspace,
> complicated event notification system, charge migration.
>
> Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> intervened with generic and cgroup v2-specific code. It's a burden on
> developers and maintainers.
Great patchset. The moves look clean and straight-forward to me on
first glance.
> This patchset aims to solve these problems by:
> 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
+1
> 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> mm/internal.h header
You proposed mm/memcontrol-v1.h below, IMO that's the best option.
> 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
+1
CONFIG_MEMCG1 should also work.
> 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
+1
> 5) putting unused struct memory_cgroup and task_struct members under
> CONFIG_MEMCG_V1 as well.
+1
>
> This is an RFC version, which is not 100% polished yet, so but it would be great
> to discuss and agree on the overall approach.
>
> Some open questions, opinions are appreciated:
> 1) I consider renaming non-static functions in memcontrol-v1.c to have
> mem_cgroup_v1_ prefix. Is this a good idea?
I think this would be great, to make it more obvious in memcontrol.c.
For core cgroup code, we used cgroup1_foo(). Maybe name them all
things like memcg1_update_tree() etc.? That's short and sweet while
sticking out visually pretty well.
> 2) Do we want to extend it beyond the memory controller? Should
Could you please elaborate? ^_^
> 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> mm/internal.h? Or mm/memcontrol-v1.h.
mm/memcontrol-v1.h sounds good to me.
> mm/memcontrol.c | 4121 ++++++++++++++++++++++---------------------------------------------------------------------------------------------------------------------------------
Lol, awesome.
On Thu, May 09, 2024 at 10:22:10AM -0400, Johannes Weiner wrote:
> On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > mm/internal.h? Or mm/memcontrol-v1.h.
>
> mm/memcontrol-v1.h sounds good to me.
Argh, there is a folio_memcg_lock() callsite in fs/buffer.c. I suppose
include/linux/memcontrol-v1.h makes the most sense then.
On Thu, May 09, 2024 at 10:36:35AM -0400, Johannes Weiner wrote:
> On Thu, May 09, 2024 at 10:22:10AM -0400, Johannes Weiner wrote:
> > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > mm/internal.h? Or mm/memcontrol-v1.h.
> >
> > mm/memcontrol-v1.h sounds good to me.
>
> Argh, there is a folio_memcg_lock() callsite in fs/buffer.c. I suppose
> include/linux/memcontrol-v1.h makes the most sense then.
You mean put everything into include/linux/memcontrol-v1.h?
And functions from memcontrol.c by memcontrol-v1.c into
include/linux/memcontrol.h?
It's an option I considered it but the downside is that we're "leaking"
a lot of internal definitions into the outside world, because
memcontrol.h is included everywhere.
So maybe mm/memcontrol-v1.h for definitions shared between v1 and v2
and keep exported functions in include/linux/memcontrol.h? There are
only few of them.
Thanks!
On Wed, May 08, 2024 at 11:33:07PM -0700, Shakeel Butt wrote:
> On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > Cgroups v2 have been around for a while and many users have fully adopted them,
> > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > for the cgroup v1 support anyway:
> > 1) the kernel binary contains useless cgroup v1 code,
> > 2) some common structures like task_struct and mem_cgroup have never used
> > cgroup v1-specific members,
> > 3) some code paths have additional checks which are not needed.
> >
> > Cgroup v1's memory controller has a number of features that are not supported
> > by cgroup v2 and their implementation is pretty much self contained.
> > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > complicated event notification system, charge migration.
> >
> > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > intervened with generic and cgroup v2-specific code. It's a burden on
> > developers and maintainers.
> >
> > This patchset aims to solve these problems by:
> > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > mm/internal.h header
> > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > 5) putting unused struct memory_cgroup and task_struct members under
> > CONFIG_MEMCG_V1 as well.
> >
> > This is an RFC version, which is not 100% polished yet, so but it would be great
> > to discuss and agree on the overall approach.
> >
> > Some open questions, opinions are appreciated:
> > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > mem_cgroup_v1_ prefix. Is this a good idea?
> > 2) Do we want to extend it beyond the memory controller? Should
> > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > mm/internal.h? Or mm/memcontrol-v1.h.
> >
>
> Hi Roman,
>
> A very timely and important topic and we should definitely talk about it
> during LSFMM as well. I have been thinking about this problem for quite
> sometime and I am getting more and more convinced that we should aim to
> completely deprecate memcg-v1.
>
> More specifically:
>
> 1. What are the memcg-v1 features which have no alternative in memcg-v2
> and are blocker for memcg-v1 users? (setting aside the cgroup v2
> structual restrictions)
I don't think there are any, except there might be a certain cost to migrate,
so some companies might be resistant to put in resources, because they don't
see any immediate benefits as well.
>
> 2. What are unused memcg-v1 features which we should start deprecating?
>
> IMO we should systematically start deprecating memcg-v1 features and
> start unblocking the users stuck on memcg-v1.
I'm not sure we want to deprecate them one-by-one - it's a lot of work
and maybe we can deprecate it all together instead.
I think the only feature which we might want to deprecate separately -
it's the charge migration. It's the most annoying feature as it requires
a lot more synchronization, which can be dropped otherwise, so it's
complicating a lot of things. Other features are more or less self-contained.
>
> Now regarding the proposal in this series, I think it can be a first
> step but should not give an impression that we are done.
Yeah, it's really only a first step.
> The only
> concern I have is the potential of "out of sight, out of mind" situation
> with this change but if we keep the momentum of deprecation of memcg-v1
> it should be fine.
My rough plan here:
1) move it out to a separate file and put under a config option, default on
2) clean up all remaining small bits here and there
.. < wait a year >
3) flip the config option to be off by default
.. < wait another year or two >
4) drop the code entirely
>
> I have CCed Greg and David from Google to get their opinion on what
> memcg-v1 features are blocker for their memcg-v2 migration and if they
> have concern in deprecation of memcg-v1 features.
Thank you!
On Wed, 8 May 2024, Shakeel Butt wrote:
> Hi Roman,
>
> A very timely and important topic and we should definitely talk about it
> during LSFMM as well. I have been thinking about this problem for quite
> sometime and I am getting more and more convinced that we should aim to
> completely deprecate memcg-v1.
>
I think this would be a very worthwhile discussion at LSF/MM, I'm not sure
if it would be too late for someone to make a formal proposal for it to be
included in the schedule. Michal would know if there is a opportunity.
I say that in light of
https://lore.kernel.org/bpf/[email protected]/T/#mb6c21b09543c434dd85e718a8ecf5ca6485e6d07
as well for the whole cgroup v1 -> v2 transition.
Chris, now cc'd, would know best about all of the dependencies that Google
has for memcg specifically.
> More specifically:
>
> 1. What are the memcg-v1 features which have no alternative in memcg-v2
> and are blocker for memcg-v1 users? (setting aside the cgroup v2
> structual restrictions)
>
> 2. What are unused memcg-v1 features which we should start deprecating?
>
> IMO we should systematically start deprecating memcg-v1 features and
> start unblocking the users stuck on memcg-v1.
>
> Now regarding the proposal in this series, I think it can be a first
> step but should not give an impression that we are done. The only
> concern I have is the potential of "out of sight, out of mind" situation
> with this change but if we keep the momentum of deprecation of memcg-v1
> it should be fine.
>
> I have CCed Greg and David from Google to get their opinion on what
> memcg-v1 features are blocker for their memcg-v2 migration and if they
> have concern in deprecation of memcg-v1 features.
>
> Anyone else still on memcg-v1, please do provide your input.
>
> thanks,
> Shakeel
>
On Thu, May 9, 2024 at 7:59 PM David Rientjes <[email protected]> wrote:
>
> On Wed, 8 May 2024, Shakeel Butt wrote:
>
> > Hi Roman,
> >
> > A very timely and important topic and we should definitely talk about it
> > during LSFMM as well. I have been thinking about this problem for quite
> > sometime and I am getting more and more convinced that we should aim to
> > completely deprecate memcg-v1.
> >
>
> I think this would be a very worthwhile discussion at LSF/MM, I'm not sure
> if it would be too late for someone to make a formal proposal for it to be
> included in the schedule. Michal would know if there is a opportunity.
>
> I say that in light of
> https://lore.kernel.org/bpf/[email protected]/T/#mb6c21b09543c434dd85e718a8ecf5ca6485e6d07
> as well for the whole cgroup v1 -> v2 transition.
>
> Chris, now cc'd, would know best about all of the dependencies that Google
> has for memcg specifically.
Thanks David,
Yes, I am very interested in that cgroup v1 -> v2 transition discussion.
>
> > More specifically:
> >
> > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > structual restrictions)
In the list mentioned by Roman: "soft limit reclaim, oom handling in userspace,
complicated event notification system, charge migration."
The "oom.control" and leak of user space oom control is a big one for google.
Some test frameworks also use "memory.force_empty".
Soft limit reclaim and charge migration is also used.
There is also the combined "memsw" limit enforcement. Google has some
internal work around for V2 but it would be good if that upstream can
support it directly.
BTW, I know you are not looking for the "cgroup v2 structure restrictions".
Two cgroup controllers that can't have different sets of processes is
a bit too restrictive.
That is what I recall right now, I might be missing some small odd items.
Anyway, glad to join the discussion if there is a session.
Chris
Chris
> >
> > 2. What are unused memcg-v1 features which we should start deprecating?
> >
> > IMO we should systematically start deprecating memcg-v1 features and
> > start unblocking the users stuck on memcg-v1.
> >
> > Now regarding the proposal in this series, I think it can be a first
> > step but should not give an impression that we are done. The only
> > concern I have is the potential of "out of sight, out of mind" situation
> > with this change but if we keep the momentum of deprecation of memcg-v1
> > it should be fine.
> >
> > I have CCed Greg and David from Google to get their opinion on what
> > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > have concern in deprecation of memcg-v1 features.
> >
> > Anyone else still on memcg-v1, please do provide your input.
> >
> > thanks,
> > Shakeel
> >
On Thu 09-05-24 19:59:19, David Rientjes wrote:
> On Wed, 8 May 2024, Shakeel Butt wrote:
>
> > Hi Roman,
> >
> > A very timely and important topic and we should definitely talk about it
> > during LSFMM as well. I have been thinking about this problem for quite
> > sometime and I am getting more and more convinced that we should aim to
> > completely deprecate memcg-v1.
> >
>
> I think this would be a very worthwhile discussion at LSF/MM, I'm not sure
> if it would be too late for someone to make a formal proposal for it to be
> included in the schedule. Michal would know if there is a opportunity.
yes, I think we can and should have this discussion. I will put that on
the schedule. I will reference this email thread as a topic proposal
with Shakeel and Roman to lead the session.
--
Michal Hocko
SUSE Labs
On Wed 08-05-24 20:41:35, Roman Gushchin wrote:
[...]
> @@ -1747,106 +1623,14 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
>
> memcg_memory_event(memcg, MEMCG_OOM);
>
> - /*
> - * We are in the middle of the charge context here, so we
> - * don't want to block when potentially sitting on a callstack
> - * that holds all kinds of filesystem and mm locks.
> - *
> - * cgroup1 allows disabling the OOM killer and waiting for outside
> - * handling until the charge can succeed; remember the context and put
> - * the task to sleep at the end of the page fault when all locks are
> - * released.
> - *
> - * On the other hand, in-kernel OOM killer allows for an async victim
> - * memory reclaim (oom_reaper) and that means that we are not solely
> - * relying on the oom victim to make a forward progress and we can
> - * invoke the oom killer here.
> - *
> - * Please note that mem_cgroup_out_of_memory might fail to find a
> - * victim and then we have to bail out from the charge path.
> - */
> - if (READ_ONCE(memcg->oom_kill_disable)) {
> - if (current->in_user_fault) {
> - css_get(&memcg->css);
> - current->memcg_in_oom = memcg;
> - current->memcg_oom_gfp_mask = mask;
> - current->memcg_oom_order = order;
> - }
> + if (!mem_cgroup_v1_oom_prepare(memcg, mask, order, &locked))
> return false;
> - }
> -
> - mem_cgroup_mark_under_oom(memcg);
> -
> - locked = mem_cgroup_oom_trylock(memcg);
This really confused me because this looks like the oom locking is
removed for v2 but this is not the case because
mem_cgroup_v1_oom_prepare is not really v1 only code - in other words
this is not going to be just return false for CONFIG_MEMCG_V1=n.
It makes sense to move the userspace oom handling out to the v1 file. I
would keep mem_cgroup_mark_under_oom here. I am not sure about the oom
locking thing because I think we can make it v1 only. For v2 I guess we
can go without this locking as the oom path is already locked and it
implements overkilling prevention (oom_evaluate_task) as it walks all
processes in the oom hierarchy.
> -
> - if (locked)
> - mem_cgroup_oom_notify(memcg);
> -
> - mem_cgroup_unmark_under_oom(memcg);
> ret = mem_cgroup_out_of_memory(memcg, mask, order);
> -
> - if (locked)
> - mem_cgroup_oom_unlock(memcg);
> + mem_cgroup_v1_oom_finish(memcg, &locked);
>
> return ret;
> }
--
Michal Hocko
SUSE Labs
On Wed 08-05-24 20:41:29, Roman Gushchin wrote:
> Cgroups v2 have been around for a while and many users have fully adopted them,
> so they never use cgroups v1 features and functionality. Yet they have to "pay"
> for the cgroup v1 support anyway:
> 1) the kernel binary contains useless cgroup v1 code,
> 2) some common structures like task_struct and mem_cgroup have never used
> cgroup v1-specific members,
> 3) some code paths have additional checks which are not needed.
>
> Cgroup v1's memory controller has a number of features that are not supported
> by cgroup v2 and their implementation is pretty much self contained.
> Most notably, these features are: soft limit reclaim, oom handling in userspace,
> complicated event notification system, charge migration.
>
> Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> intervened with generic and cgroup v2-specific code. It's a burden on
> developers and maintainers.
>
> This patchset aims to solve these problems by:
> 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> mm/internal.h header
> 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> 5) putting unused struct memory_cgroup and task_struct members under
> CONFIG_MEMCG_V1 as well.
This makes sense and I have to admit I didn't think this was so much
code to move. It will make the code base much esier to follow. I do not
think we can drop that code anytime soon as there is still quite a lot
of use of v1 out there. From my experience there is no good reason for
many other than inertia and those are just waiting for somebody to move
them to v2. There are some workloads which depend on v1 only features
and we should discuss what to do about those.
--
Michal Hocko
SUSE Labs
On Thu, May 09, 2024 at 07:57:30AM -0700, Roman Gushchin wrote:
> So maybe mm/memcontrol-v1.h for definitions shared between v1 and v2
> and keep exported functions in include/linux/memcontrol.h? There are
> only few of them.
That sounds best to me.
On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
>
> On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > Cgroups v2 have been around for a while and many users have fully adopted them,
> > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > for the cgroup v1 support anyway:
> > 1) the kernel binary contains useless cgroup v1 code,
> > 2) some common structures like task_struct and mem_cgroup have never used
> > cgroup v1-specific members,
> > 3) some code paths have additional checks which are not needed.
> >
> > Cgroup v1's memory controller has a number of features that are not supported
> > by cgroup v2 and their implementation is pretty much self contained.
> > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > complicated event notification system, charge migration.
> >
> > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > intervened with generic and cgroup v2-specific code. It's a burden on
> > developers and maintainers.
> >
> > This patchset aims to solve these problems by:
> > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > mm/internal.h header
> > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > 5) putting unused struct memory_cgroup and task_struct members under
> > CONFIG_MEMCG_V1 as well.
> >
> > This is an RFC version, which is not 100% polished yet, so but it would be great
> > to discuss and agree on the overall approach.
> >
> > Some open questions, opinions are appreciated:
> > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > mem_cgroup_v1_ prefix. Is this a good idea?
> > 2) Do we want to extend it beyond the memory controller? Should
> > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > mm/internal.h? Or mm/memcontrol-v1.h.
> >
>
> Hi Roman,
>
> A very timely and important topic and we should definitely talk about it
> during LSFMM as well. I have been thinking about this problem for quite
> sometime and I am getting more and more convinced that we should aim to
> completely deprecate memcg-v1.
>
> More specifically:
>
> 1. What are the memcg-v1 features which have no alternative in memcg-v2
> and are blocker for memcg-v1 users? (setting aside the cgroup v2
> structual restrictions)
>
> 2. What are unused memcg-v1 features which we should start deprecating?
>
> IMO we should systematically start deprecating memcg-v1 features and
> start unblocking the users stuck on memcg-v1.
>
> Now regarding the proposal in this series, I think it can be a first
> step but should not give an impression that we are done. The only
> concern I have is the potential of "out of sight, out of mind" situation
> with this change but if we keep the momentum of deprecation of memcg-v1
> it should be fine.
>
> I have CCed Greg and David from Google to get their opinion on what
> memcg-v1 features are blocker for their memcg-v2 migration and if they
> have concern in deprecation of memcg-v1 features.
>
> Anyone else still on memcg-v1, please do provide your input.
Hi Shakeel,
Hopefully I'm not too late. We are currently using memcg v1.
One specific feature we rely on in v1 is skmem accounting. In v1, we
account for TCP memory usage without charging it to memcg v1, which is
useful for monitoring the TCP memory usage generated by tasks running
in a container. However, in memcg v2, monitoring TCP memory requires
charging it to the container, which can easily cause OOM issues. It
would be better if we could monitor skmem usage without charging it in
the memcg v2, allowing us to account for it without the risk of
triggering OOM conditions.
--
Regards
Yafang
On Thu, May 16, 2024 at 11:35:57AM +0800, Yafang Shao wrote:
> On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
> >
> > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > for the cgroup v1 support anyway:
> > > 1) the kernel binary contains useless cgroup v1 code,
> > > 2) some common structures like task_struct and mem_cgroup have never used
> > > cgroup v1-specific members,
> > > 3) some code paths have additional checks which are not needed.
> > >
> > > Cgroup v1's memory controller has a number of features that are not supported
> > > by cgroup v2 and their implementation is pretty much self contained.
> > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > complicated event notification system, charge migration.
> > >
> > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > developers and maintainers.
> > >
> > > This patchset aims to solve these problems by:
> > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > mm/internal.h header
> > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > 5) putting unused struct memory_cgroup and task_struct members under
> > > CONFIG_MEMCG_V1 as well.
> > >
> > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > to discuss and agree on the overall approach.
> > >
> > > Some open questions, opinions are appreciated:
> > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > 2) Do we want to extend it beyond the memory controller? Should
> > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > mm/internal.h? Or mm/memcontrol-v1.h.
> > >
> >
> > Hi Roman,
> >
> > A very timely and important topic and we should definitely talk about it
> > during LSFMM as well. I have been thinking about this problem for quite
> > sometime and I am getting more and more convinced that we should aim to
> > completely deprecate memcg-v1.
> >
> > More specifically:
> >
> > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > structual restrictions)
> >
> > 2. What are unused memcg-v1 features which we should start deprecating?
> >
> > IMO we should systematically start deprecating memcg-v1 features and
> > start unblocking the users stuck on memcg-v1.
> >
> > Now regarding the proposal in this series, I think it can be a first
> > step but should not give an impression that we are done. The only
> > concern I have is the potential of "out of sight, out of mind" situation
> > with this change but if we keep the momentum of deprecation of memcg-v1
> > it should be fine.
> >
> > I have CCed Greg and David from Google to get their opinion on what
> > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > have concern in deprecation of memcg-v1 features.
> >
> > Anyone else still on memcg-v1, please do provide your input.
>
> Hi Shakeel,
>
> Hopefully I'm not too late. We are currently using memcg v1.
>
> One specific feature we rely on in v1 is skmem accounting. In v1, we
> account for TCP memory usage without charging it to memcg v1, which is
> useful for monitoring the TCP memory usage generated by tasks running
> in a container. However, in memcg v2, monitoring TCP memory requires
> charging it to the container, which can easily cause OOM issues. It
> would be better if we could monitor skmem usage without charging it in
> the memcg v2, allowing us to account for it without the risk of
> triggering OOM conditions.
Hi Yafang,
the data itself is available on cgroup v2 in memory.stat:sock, however
you're right, it's charged on pair with other types of memory. It was
one of the main principles of cgroup v2's memory controller, so I don't
think it can be changed.
So the feature you need is not skmem accounting, but something quite
opposite :)
The question I have here: what makes socket memory different here?
Is it something specific to your setup (e.g. you mostly use memory.max
to protect against memory leaks in the userspace code, but socket memory
spikes are always caused by external traffic and are legit) or we have
more fundamental problems with the socket memory handling, e.g. we can't
effectively reclaim it under the memory pressure?
In the first case you can maintain a ~2-lines non-upstream patch which will
disable the charging while maintaining statistics - it's not a perfect, but
likely the best option here. In the second case we need collectively fix it
for cgroup v2.
Thanks!
On Fri, May 17, 2024 at 1:29 AM Roman Gushchin <[email protected]> wrote:
>
> On Thu, May 16, 2024 at 11:35:57AM +0800, Yafang Shao wrote:
> > On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <shakeel.butt@linuxdev> wrote:
> > >
> > > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > > for the cgroup v1 support anyway:
> > > > 1) the kernel binary contains useless cgroup v1 code,
> > > > 2) some common structures like task_struct and mem_cgroup have never used
> > > > cgroup v1-specific members,
> > > > 3) some code paths have additional checks which are not needed.
> > > >
> > > > Cgroup v1's memory controller has a number of features that are not supported
> > > > by cgroup v2 and their implementation is pretty much self contained.
> > > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > > complicated event notification system, charge migration.
> > > >
> > > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > > developers and maintainers.
> > > >
> > > > This patchset aims to solve these problems by:
> > > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1c file,
> > > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > > mm/internal.h header
> > > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > > 5) putting unused struct memory_cgroup and task_struct members under
> > > > CONFIG_MEMCG_V1 as well.
> > > >
> > > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > > to discuss and agree on the overall approach.
> > > >
> > > > Some open questions, opinions are appreciated:
> > > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > > 2) Do we want to extend it beyond the memory controller? Should
> > > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > > mm/internal.h? Or mm/memcontrol-v1.h.
> > > >
> > >
> > > Hi Roman,
> > >
> > > A very timely and important topic and we should definitely talk about it
> > > during LSFMM as well. I have been thinking about this problem for quite
> > > sometime and I am getting more and more convinced that we should aim to
> > > completely deprecate memcg-v1.
> > >
> > > More specifically:
> > >
> > > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > > structual restrictions)
> > >
> > > 2. What are unused memcg-v1 features which we should start deprecating?
> > >
> > > IMO we should systematically start deprecating memcg-v1 features and
> > > start unblocking the users stuck on memcg-v1.
> > >
> > > Now regarding the proposal in this series, I think it can be a first
> > > step but should not give an impression that we are done. The only
> > > concern I have is the potential of "out of sight, out of mind" situation
> > > with this change but if we keep the momentum of deprecation of memcg-v1
> > > it should be fine.
> > >
> > > I have CCed Greg and David from Google to get their opinion on what
> > > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > > have concern in deprecation of memcg-v1 features.
> > >
> > > Anyone else still on memcg-v1, please do provide your input.
> >
> > Hi Shakeel,
> >
> > Hopefully I'm not too late. We are currently using memcg v1.
> >
> > One specific feature we rely on in v1 is skmem accounting. In v1, we
> > account for TCP memory usage without charging it to memcg v1, which is
> > useful for monitoring the TCP memory usage generated by tasks running
> > in a container. However, in memcg v2, monitoring TCP memory requires
> > charging it to the container, which can easily cause OOM issues. It
> > would be better if we could monitor skmem usage without charging it in
> > the memcg v2, allowing us to account for it without the risk of
> > triggering OOM conditions.
>
> Hi Yafang,
>
> the data itself is available on cgroup v2 in memory.stat:sock, however
> you're right, it's charged on pair with other types of memory. It was
> one of the main principles of cgroup v2's memory controller, so I don't
> think it can be changed.
>
> So the feature you need is not skmem accounting, but something quite
> opposite :)
>
> The question I have here: what makes socket memory different here?
>
> Is it something specific to your setup (e.g. you mostly use memory.max
> to protect against memory leaks in the userspace code, but socket memory
> spikes are always caused by external traffic and are legit) or we have
> more fundamental problems with the socket memory handling, e.g. we can't
> effectively reclaim it under the memory pressure?
It is the first case.
>
> In the first case you can maintain a ~2-lines non-upstream patch which will
> disable the charging while maintaining statistics - it's not a perfect, but
> likely the best option here. In the second case we need collectively fix it
> for cgroup v2.
>
Thank you for your advice. Currently, we do not have any immediate
plans to migrate to cgroup v2. If we are required to use cgroup v2 in
the future, we will need to maintain non-upstream patches.
By the way, is there any reason we cannot keep this behavior
consistent with memcg v1 in the upstream kernel? That would save us
from having to maintain it locally.
--
Regards
Yafang
On Fri, May 17, 2024 at 10:21:01AM +0800, Yafang Shao wrote:
> On Fri, May 17, 2024 at 1:29 AM Roman Gushchin <[email protected]> wrote:
> >
> > On Thu, May 16, 2024 at 11:35:57AM +0800, Yafang Shao wrote:
> > > On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
> > > >
> > > > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > > > for the cgroup v1 support anyway:
> > > > > 1) the kernel binary contains useless cgroup v1 code,
> > > > > 2) some common structures like task_struct and mem_cgroup have never used
> > > > > cgroup v1-specific members,
> > > > > 3) some code paths have additional checks which are not needed.
> > > > >
> > > > > Cgroup v1's memory controller has a number of features that are not supported
> > > > > by cgroup v2 and their implementation is pretty much self contained.
> > > > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > > > complicated event notification system, charge migration.
> > > > >
> > > > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > > > developers and maintainers.
> > > > >
> > > > > This patchset aims to solve these problems by:
> > > > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > > > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > > > mm/internal.h header
> > > > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > > > 5) putting unused struct memory_cgroup and task_struct members under
> > > > > CONFIG_MEMCG_V1 as well.
> > > > >
> > > > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > > > to discuss and agree on the overall approach.
> > > > >
> > > > > Some open questions, opinions are appreciated:
> > > > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > > > 2) Do we want to extend it beyond the memory controller? Should
> > > > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > > > mm/internal.h? Or mm/memcontrol-v1.h.
> > > > >
> > > >
> > > > Hi Roman,
> > > >
> > > > A very timely and important topic and we should definitely talk about it
> > > > during LSFMM as well. I have been thinking about this problem for quite
> > > > sometime and I am getting more and more convinced that we should aim to
> > > > completely deprecate memcg-v1.
> > > >
> > > > More specifically:
> > > >
> > > > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > > > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > > > structual restrictions)
> > > >
> > > > 2. What are unused memcg-v1 features which we should start deprecating?
> > > >
> > > > IMO we should systematically start deprecating memcg-v1 features and
> > > > start unblocking the users stuck on memcg-v1.
> > > >
> > > > Now regarding the proposal in this series, I think it can be a first
> > > > step but should not give an impression that we are done. The only
> > > > concern I have is the potential of "out of sight, out of mind" situation
> > > > with this change but if we keep the momentum of deprecation of memcg-v1
> > > > it should be fine.
> > > >
> > > > I have CCed Greg and David from Google to get their opinion on what
> > > > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > > > have concern in deprecation of memcg-v1 features.
> > > >
> > > > Anyone else still on memcg-v1, please do provide your input.
> > >
> > > Hi Shakeel,
> > >
> > > Hopefully I'm not too late. We are currently using memcg v1.
> > >
> > > One specific feature we rely on in v1 is skmem accounting. In v1, we
> > > account for TCP memory usage without charging it to memcg v1, which is
> > > useful for monitoring the TCP memory usage generated by tasks running
> > > in a container. However, in memcg v2, monitoring TCP memory requires
> > > charging it to the container, which can easily cause OOM issues. It
> > > would be better if we could monitor skmem usage without charging it in
> > > the memcg v2, allowing us to account for it without the risk of
> > > triggering OOM conditions.
> >
> > Hi Yafang,
> >
> > the data itself is available on cgroup v2 in memory.stat:sock, however
> > you're right, it's charged on pair with other types of memory. It was
> > one of the main principles of cgroup v2's memory controller, so I don't
> > think it can be changed.
> >
> > So the feature you need is not skmem accounting, but something quite
> > opposite :)
> >
> > The question I have here: what makes socket memory different here?
> >
> > Is it something specific to your setup (e.g. you mostly use memory.max
> > to protect against memory leaks in the userspace code, but socket memory
> > spikes are always caused by external traffic and are legit) or we have
> > more fundamental problems with the socket memory handling, e.g. we can't
> > effectively reclaim it under the memory pressure?
>
> It is the first case.
>
> >
> > In the first case you can maintain a ~2-lines non-upstream patch which will
> > disable the charging while maintaining statistics - it's not a perfect, but
> > likely the best option here. In the second case we need collectively fix it
> > for cgroup v2.
> >
>
> Thank you for your advice. Currently, we do not have any immediate
> plans to migrate to cgroup v2. If we are required to use cgroup v2 in
> the future, we will need to maintain non-upstream patches.
>
> By the way, is there any reason we cannot keep this behavior
> consistent with memcg v1 in the upstream kernel? That would save us
> from having to maintain it locally.
The idea to handle various types of memory independently isn't working well
for most users: it makes the configuration trickier and more fragile.
It's also more expensive in terms of the accounting overhead.
The tcpmem accounting is btw quite expensive by itself. So by switching to
cgroup v2 you might see (depending on your traffic and cpu load) some
nice performance benefits.
Thanks!
On Thu, May 16, 2024 at 11:35:57AM +0800, Yafang Shao wrote:
> On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
> >
>
[...]
> Hi Shakeel,
>
> Hopefully I'm not too late. We are currently using memcg v1.
>
> One specific feature we rely on in v1 is skmem accounting. In v1, we
> account for TCP memory usage without charging it to memcg v1, which is
> useful for monitoring the TCP memory usage generated by tasks running
> in a container. However, in memcg v2, monitoring TCP memory requires
> charging it to the container, which can easily cause OOM issues. It
> would be better if we could monitor skmem usage without charging it in
> the memcg v2, allowing us to account for it without the risk of
> triggering OOM conditions.
>
Hi Yafang,
No worries. From what I understand, you are not really using skmem
charging of v1 but just the network memory usage stats and you are
worried that charging network memory to cgroup memory may cause OOMs. Is
that correct? Have you tried charging network memory to cgroup memory
before and saw OOMs? If yes then I would really like to see OOM reports.
I have two examples where the v2's skmem charging is working fine in
production namely Google and Meta. Google is still on v1 but for skmem
charging, they have moved to v2 semantics. Actually I have another
report from Cloudflare [0] where the tcp throttling mechanism for v2's
tcp memory accounting is too much conservative for their production
traffic.
Anyways this just means that we need a more flexible way to provide
and enforce semantics for tcp memory pressure with a decent default
behavior. I will followup on this separately.
[0] https://lore.kernel.org/lkml/CABWYdi0G7cyNFbndM-ELTDAR3x4Ngm0AehEp5aP0tfNkXUE+Uw@mail.gmail.com/
thanks,
Shakeel
On Sat, May 18, 2024 at 3:33 PM Shakeel Butt <[email protected]> wrote:
>
> On Thu, May 16, 2024 at 11:35:57AM +0800, Yafang Shao wrote:
> > On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <shakeel.butt@linuxdev> wrote:
> > >
> >
> [...]
> > Hi Shakeel,
> >
> > Hopefully I'm not too late. We are currently using memcg v1.
> >
> > One specific feature we rely on in v1 is skmem accounting. In v1, we
> > account for TCP memory usage without charging it to memcg v1, which is
> > useful for monitoring the TCP memory usage generated by tasks running
> > in a container. However, in memcg v2, monitoring TCP memory requires
> > charging it to the container, which can easily cause OOM issues. It
> > would be better if we could monitor skmem usage without charging it in
> > the memcg v2, allowing us to account for it without the risk of
> > triggering OOM conditions.
> >
>
> Hi Yafang,
>
> No worries. From what I understand, you are not really using skmem
> charging of v1 but just the network memory usage stats and you are
> worried that charging network memory to cgroup memory may cause OOMs. Is
> that correct?
Correct.
> Have you tried charging network memory to cgroup memory
> before and saw OOMs? If yes then I would really like to see OOM reports.
No, we don't enable the charging for TCP memory in memcg v1 and we
don't have a plan to add support for it currently.
>
> I have two examples where the v2's skmem charging is working fine in
> production namely Google and Meta. Google is still on v1 but for skmem
> charging, they have moved to v2 semantics. Actually I have another
> report from Cloudflare [0] where the tcp throttling mechanism for v2's
> tcp memory accounting is too much conservative for their production
> traffic.
>
> Anyways this just means that we need a more flexible way to provide
> and enforce semantics for tcp memory pressure with a decent default
> behavior. I will followup on this separately.
>
> [0] https://lore.kernel.org/lkml/CABWYdi0G7cyNFbndM-ELTDAR3x4Ngm0AehEp5aP0tfNkXUE+Uw@mail.gmail.com/
Thanks for your explanation.
--
Regards
Yafang
On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
>
> On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > Cgroups v2 have been around for a while and many users have fully adopted them,
> > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > for the cgroup v1 support anyway:
> > 1) the kernel binary contains useless cgroup v1 code,
> > 2) some common structures like task_struct and mem_cgroup have never used
> > cgroup v1-specific members,
> > 3) some code paths have additional checks which are not needed.
> >
> > Cgroup v1's memory controller has a number of features that are not supported
> > by cgroup v2 and their implementation is pretty much self contained.
> > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > complicated event notification system, charge migration.
> >
> > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > intervened with generic and cgroup v2-specific code. It's a burden on
> > developers and maintainers.
> >
> > This patchset aims to solve these problems by:
> > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > mm/internal.h header
> > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > 5) putting unused struct memory_cgroup and task_struct members under
> > CONFIG_MEMCG_V1 as well.
> >
> > This is an RFC version, which is not 100% polished yet, so but it would be great
> > to discuss and agree on the overall approach.
> >
> > Some open questions, opinions are appreciated:
> > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > mem_cgroup_v1_ prefix. Is this a good idea?
> > 2) Do we want to extend it beyond the memory controller? Should
> > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > mm/internal.h? Or mm/memcontrol-v1.h.
> >
>
> Hi Roman,
>
> A very timely and important topic and we should definitely talk about it
> during LSFMM as well. I have been thinking about this problem for quite
> sometime and I am getting more and more convinced that we should aim to
> completely deprecate memcg-v1.
>
> More specifically:
>
> 1. What are the memcg-v1 features which have no alternative in memcg-v2
> and are blocker for memcg-v1 users? (setting aside the cgroup v2
> structual restrictions)
>
> 2. What are unused memcg-v1 features which we should start deprecating?
>
> IMO we should systematically start deprecating memcg-v1 features and
> start unblocking the users stuck on memcg-v1.
>
> Now regarding the proposal in this series, I think it can be a first
> step but should not give an impression that we are done. The only
> concern I have is the potential of "out of sight, out of mind" situation
> with this change but if we keep the momentum of deprecation of memcg-v1
> it should be fine.
>
> I have CCed Greg and David from Google to get their opinion on what
> memcg-v1 features are blocker for their memcg-v2 migration and if they
> have concern in deprecation of memcg-v1 features.
>
> Anyone else still on memcg-v1, please do provide your input.
>
Hi,
Sorry for joining the discussion late, but I'd like to add some info
here: We are using the "memsw" feature a lot. It's a very useful knob
for container memory overcommitting: It's a great abstraction of the
"expected total memory usage" of a container, so containers can't
allocate too much memory using SWAP, but still be able to SWAP out.
For a simple example, with memsw.limit == memory.limit, containers
can't exceed their original memory limit, even with SWAP enabled, they
get OOM killed as how they used to, but the host is now able to
offload cold pages.
Similar ability seems absent with V2: With memory.swap.max == 0, the
host can't use SWAP to reclaim container memory at all. But with a
value larger than that, containers are able to overuse memory, causing
delayed OOM kill, thrashing, CPU/Memory usage ratio could be heavily
out of balance, especially with compress SWAP backends.
Cgroup accounting of ZSWAP/ZRAM doesn't really help, we want to
account for the total raw usage, not the compressed usage. One example
is that if a container uses tons of duplicated pages, then it can
allocate much more memory than it is limited, that could cause
trouble.
I saw Chris also mentioned Google has a workaround internally for it
for Cgroup V2. This will be a blocker for us and a similar workaround
might be needed. It will be great so see an upstream support for this.
On Thu, May 23, 2024 at 01:58:49AM +0800, Kairui Song wrote:
> On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <[email protected]> wrote:
> >
> > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > for the cgroup v1 support anyway:
> > > 1) the kernel binary contains useless cgroup v1 code,
> > > 2) some common structures like task_struct and mem_cgroup have never used
> > > cgroup v1-specific members,
> > > 3) some code paths have additional checks which are not needed.
> > >
> > > Cgroup v1's memory controller has a number of features that are not supported
> > > by cgroup v2 and their implementation is pretty much self contained.
> > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > complicated event notification system, charge migration.
> > >
> > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > developers and maintainers.
> > >
> > > This patchset aims to solve these problems by:
> > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file,
> > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > mm/internal.h header
> > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > 5) putting unused struct memory_cgroup and task_struct members under
> > > CONFIG_MEMCG_V1 as well.
> > >
> > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > to discuss and agree on the overall approach.
> > >
> > > Some open questions, opinions are appreciated:
> > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > 2) Do we want to extend it beyond the memory controller? Should
> > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > mm/internal.h? Or mm/memcontrol-v1.h.
> > >
> >
> > Hi Roman,
> >
> > A very timely and important topic and we should definitely talk about it
> > during LSFMM as well. I have been thinking about this problem for quite
> > sometime and I am getting more and more convinced that we should aim to
> > completely deprecate memcg-v1.
> >
> > More specifically:
> >
> > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > structual restrictions)
> >
> > 2. What are unused memcg-v1 features which we should start deprecating?
> >
> > IMO we should systematically start deprecating memcg-v1 features and
> > start unblocking the users stuck on memcg-v1.
> >
> > Now regarding the proposal in this series, I think it can be a first
> > step but should not give an impression that we are done. The only
> > concern I have is the potential of "out of sight, out of mind" situation
> > with this change but if we keep the momentum of deprecation of memcg-v1
> > it should be fine.
> >
> > I have CCed Greg and David from Google to get their opinion on what
> > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > have concern in deprecation of memcg-v1 features.
> >
> > Anyone else still on memcg-v1, please do provide your input.
> >
>
> Hi,
>
> Sorry for joining the discussion late, but I'd like to add some info
> here: We are using the "memsw" feature a lot. It's a very useful knob
> for container memory overcommitting: It's a great abstraction of the
> "expected total memory usage" of a container, so containers can't
> allocate too much memory using SWAP, but still be able to SWAP out.
>
> For a simple example, with memsw.limit == memory.limit, containers
> can't exceed their original memory limit, even with SWAP enabled, they
> get OOM killed as how they used to, but the host is now able to
> offload cold pages.
>
> Similar ability seems absent with V2: With memory.swap.max == 0, the
> host can't use SWAP to reclaim container memory at all. But with a
> value larger than that, containers are able to overuse memory, causing
> delayed OOM kill, thrashing, CPU/Memory usage ratio could be heavily
> out of balance, especially with compress SWAP backends.
>
> Cgroup accounting of ZSWAP/ZRAM doesn't really help, we want to
> account for the total raw usage, not the compressed usage. One example
> is that if a container uses tons of duplicated pages, then it can
> allocate much more memory than it is limited, that could cause
> trouble.
So you don't need separate swap knobs, only combined, right?
> I saw Chris also mentioned Google has a workaround internally for it
> for Cgroup V2. This will be a blocker for us and a similar workaround
> might be needed. It will be great so see an upstream support for this.
I think that _at least_ we should refactor the code so that it would
be a minimal patch (e.g. one #define) to switch to the old mode.
I don't think it's reasonable to add a new interface, but having a
patch/config option or even a mount option which changes the semantics
of memory.swap.max to the v1-like behavior should be ok.
I'll try to do the first part (refactoring this code), and we can have
a discussion from there.
Thanks!
On Thu, May 23, 2024 at 12:56 PM Roman Gushchin
<[email protected]> wrote:
>
> On Thu, May 23, 2024 at 01:58:49AM +0800, Kairui Song wrote:
> > On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <shakeel.butt@linuxdev> wrote:
> > >
> > > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > > for the cgroup v1 support anyway:
> > > > 1) the kernel binary contains useless cgroup v1 code,
> > > > 2) some common structures like task_struct and mem_cgroup have never used
> > > > cgroup v1-specific members,
> > > > 3) some code paths have additional checks which are not needed.
> > > >
> > > > Cgroup v1's memory controller has a number of features that are not supported
> > > > by cgroup v2 and their implementation is pretty much self contained.
> > > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > > complicated event notification system, charge migration.
> > > >
> > > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > > developers and maintainers.
> > > >
> > > > This patchset aims to solve these problems by:
> > > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1c file,
> > > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > > mm/internal.h header
> > > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > > 5) putting unused struct memory_cgroup and task_struct members under
> > > > CONFIG_MEMCG_V1 as well.
> > > >
> > > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > > to discuss and agree on the overall approach.
> > > >
> > > > Some open questions, opinions are appreciated:
> > > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > > 2) Do we want to extend it beyond the memory controller? Should
> > > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > > mm/internal.h? Or mm/memcontrol-v1.h.
> > > >
> > >
> > > Hi Roman,
> > >
> > > A very timely and important topic and we should definitely talk about it
> > > during LSFMM as well. I have been thinking about this problem for quite
> > > sometime and I am getting more and more convinced that we should aim to
> > > completely deprecate memcg-v1.
> > >
> > > More specifically:
> > >
> > > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > > structual restrictions)
> > >
> > > 2. What are unused memcg-v1 features which we should start deprecating?
> > >
> > > IMO we should systematically start deprecating memcg-v1 features and
> > > start unblocking the users stuck on memcg-v1.
> > >
> > > Now regarding the proposal in this series, I think it can be a first
> > > step but should not give an impression that we are done. The only
> > > concern I have is the potential of "out of sight, out of mind" situation
> > > with this change but if we keep the momentum of deprecation of memcg-v1
> > > it should be fine.
> > >
> > > I have CCed Greg and David from Google to get their opinion on what
> > > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > > have concern in deprecation of memcg-v1 features.
> > >
> > > Anyone else still on memcg-v1, please do provide your input.
> > >
> >
> > Hi,
> >
> > Sorry for joining the discussion late, but I'd like to add some info
> > here: We are using the "memsw" feature a lot. It's a very useful knob
> > for container memory overcommitting: It's a great abstraction of the
> > "expected total memory usage" of a container, so containers can't
> > allocate too much memory using SWAP, but still be able to SWAP out.
+Michal,
Just FYI, we do have companies like Tensent using the V1 combine memsw
limitation as well. Google is not the only company using this API.
> >
> > For a simple example, with memsw.limit == memory.limit, containers
> > can't exceed their original memory limit, even with SWAP enabled, they
> > get OOM killed as how they used to, but the host is now able to
> > offload cold pages.
> >
> > Similar ability seems absent with V2: With memory.swap.max == 0, the
> > host can't use SWAP to reclaim container memory at all. But with a
> > value larger than that, containers are able to overuse memory, causing
> > delayed OOM kill, thrashing, CPU/Memory usage ratio could be heavily
> > out of balance, especially with compress SWAP backends.
> >
> > Cgroup accounting of ZSWAP/ZRAM doesn't really help, we want to
> > account for the total raw usage, not the compressed usage. One example
> > is that if a container uses tons of duplicated pages, then it can
> > allocate much more memory than it is limited, that could cause
> > trouble.
>
> So you don't need separate swap knobs, only combined, right?
>
> > I saw Chris also mentioned Google has a workaround internally for it
> > for Cgroup V2. This will be a blocker for us and a similar workaround
> > might be needed. It will be great so see an upstream support for this.
>
> I think that _at least_ we should refactor the code so that it would
> be a minimal patch (e.g. one #define) to switch to the old mode.
That would be great to have a path forward to allow cgroup V2 to
provide the combined memsw limitations.
>
> I don't think it's reasonable to add a new interface, but having a
> patch/config option or even a mount option which changes the semantics
> of memory.swap.max to the v1-like behavior should be ok.
Using sysctl or a slightly different cgroup API is fine. The feature
needs to be there.
> I'll try to do the first part (refactoring this code), and we can have
> a discussion from there.
Looking forward to it.
Thanks
Chris
On Fri, May 10, 2024 at 03:26:35PM +0200, Michal Hocko wrote:
> On Wed 08-05-24 20:41:35, Roman Gushchin wrote:
> [...]
> > @@ -1747,106 +1623,14 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
> >
> > memcg_memory_event(memcg, MEMCG_OOM);
> >
> > - /*
> > - * We are in the middle of the charge context here, so we
> > - * don't want to block when potentially sitting on a callstack
> > - * that holds all kinds of filesystem and mm locks.
> > - *
> > - * cgroup1 allows disabling the OOM killer and waiting for outside
> > - * handling until the charge can succeed; remember the context and put
> > - * the task to sleep at the end of the page fault when all locks are
> > - * released.
> > - *
> > - * On the other hand, in-kernel OOM killer allows for an async victim
> > - * memory reclaim (oom_reaper) and that means that we are not solely
> > - * relying on the oom victim to make a forward progress and we can
> > - * invoke the oom killer here.
> > - *
> > - * Please note that mem_cgroup_out_of_memory might fail to find a
> > - * victim and then we have to bail out from the charge path.
> > - */
> > - if (READ_ONCE(memcg->oom_kill_disable)) {
> > - if (current->in_user_fault) {
> > - css_get(&memcg->css);
> > - current->memcg_in_oom = memcg;
> > - current->memcg_oom_gfp_mask = mask;
> > - current->memcg_oom_order = order;
> > - }
> > + if (!mem_cgroup_v1_oom_prepare(memcg, mask, order, &locked))
> > return false;
> > - }
> > -
> > - mem_cgroup_mark_under_oom(memcg);
> > -
> > - locked = mem_cgroup_oom_trylock(memcg);
>
> This really confused me because this looks like the oom locking is
> removed for v2 but this is not the case because
> mem_cgroup_v1_oom_prepare is not really v1 only code - in other words
> this is not going to be just return false for CONFIG_MEMCG_V1=n.
>
> It makes sense to move the userspace oom handling out to the v1 file. I
> would keep mem_cgroup_mark_under_oom here.
Hm, I don't see any usages of memcg->under_oom outside of v1-specific
context. I probably miss something, can you, please, clarify?
> I am not sure about the oom
> locking thing because I think we can make it v1 only. For v2 I guess we
> can go without this locking as the oom path is already locked and it
> implements overkilling prevention (oom_evaluate_task) as it walks all
> processes in the oom hierarchy.
It's a good point and not obvious if we really need anything of this on v2.
I guess no, but will think a bit more.
Thank you!
On Fri, May 24, 2024 at 3:55 AM Roman Gushchin <[email protected]> wrote:
>
> On Thu, May 23, 2024 at 01:58:49AM +0800, Kairui Song wrote:
> > On Thu, May 9, 2024 at 2:33 PM Shakeel Butt <shakeel.butt@linuxdev> wrote:
> > >
> > > On Wed, May 08, 2024 at 08:41:29PM -0700, Roman Gushchin wrote:
> > > > Cgroups v2 have been around for a while and many users have fully adopted them,
> > > > so they never use cgroups v1 features and functionality. Yet they have to "pay"
> > > > for the cgroup v1 support anyway:
> > > > 1) the kernel binary contains useless cgroup v1 code,
> > > > 2) some common structures like task_struct and mem_cgroup have never used
> > > > cgroup v1-specific members,
> > > > 3) some code paths have additional checks which are not needed.
> > > >
> > > > Cgroup v1's memory controller has a number of features that are not supported
> > > > by cgroup v2 and their implementation is pretty much self contained.
> > > > Most notably, these features are: soft limit reclaim, oom handling in userspace,
> > > > complicated event notification system, charge migration.
> > > >
> > > > Cgroup v1-specific code in memcontrol.c is close to 4k lines in size and it's
> > > > intervened with generic and cgroup v2-specific code. It's a burden on
> > > > developers and maintainers.
> > > >
> > > > This patchset aims to solve these problems by:
> > > > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1c file,
> > > > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the
> > > > mm/internal.h header
> > > > 3) introducing the CONFIG_MEMCG_V1 config option, turned on by default
> > > > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set
> > > > 5) putting unused struct memory_cgroup and task_struct members under
> > > > CONFIG_MEMCG_V1 as well.
> > > >
> > > > This is an RFC version, which is not 100% polished yet, so but it would be great
> > > > to discuss and agree on the overall approach.
> > > >
> > > > Some open questions, opinions are appreciated:
> > > > 1) I consider renaming non-static functions in memcontrol-v1.c to have
> > > > mem_cgroup_v1_ prefix. Is this a good idea?
> > > > 2) Do we want to extend it beyond the memory controller? Should
> > > > 3) Is it better to use a new include/linux/memcontrol-v1.h instead of
> > > > mm/internal.h? Or mm/memcontrol-v1.h.
> > > >
> > >
> > > Hi Roman,
> > >
> > > A very timely and important topic and we should definitely talk about it
> > > during LSFMM as well. I have been thinking about this problem for quite
> > > sometime and I am getting more and more convinced that we should aim to
> > > completely deprecate memcg-v1.
> > >
> > > More specifically:
> > >
> > > 1. What are the memcg-v1 features which have no alternative in memcg-v2
> > > and are blocker for memcg-v1 users? (setting aside the cgroup v2
> > > structual restrictions)
> > >
> > > 2. What are unused memcg-v1 features which we should start deprecating?
> > >
> > > IMO we should systematically start deprecating memcg-v1 features and
> > > start unblocking the users stuck on memcg-v1.
> > >
> > > Now regarding the proposal in this series, I think it can be a first
> > > step but should not give an impression that we are done. The only
> > > concern I have is the potential of "out of sight, out of mind" situation
> > > with this change but if we keep the momentum of deprecation of memcg-v1
> > > it should be fine.
> > >
> > > I have CCed Greg and David from Google to get their opinion on what
> > > memcg-v1 features are blocker for their memcg-v2 migration and if they
> > > have concern in deprecation of memcg-v1 features.
> > >
> > > Anyone else still on memcg-v1, please do provide your input.
> > >
> >
> > Hi,
> >
> > Sorry for joining the discussion late, but I'd like to add some info
> > here: We are using the "memsw" feature a lot. It's a very useful knob
> > for container memory overcommitting: It's a great abstraction of the
> > "expected total memory usage" of a container, so containers can't
> > allocate too much memory using SWAP, but still be able to SWAP out.
> >
> > For a simple example, with memsw.limit == memory.limit, containers
> > can't exceed their original memory limit, even with SWAP enabled, they
> > get OOM killed as how they used to, but the host is now able to
> > offload cold pages.
> >
> > Similar ability seems absent with V2: With memory.swap.max == 0, the
> > host can't use SWAP to reclaim container memory at all. But with a
> > value larger than that, containers are able to overuse memory, causing
> > delayed OOM kill, thrashing, CPU/Memory usage ratio could be heavily
> > out of balance, especially with compress SWAP backends.
> >
> > Cgroup accounting of ZSWAP/ZRAM doesn't really help, we want to
> > account for the total raw usage, not the compressed usage. One example
> > is that if a container uses tons of duplicated pages, then it can
> > allocate much more memory than it is limited, that could cause
> > trouble.
>
> So you don't need separate swap knobs, only combined, right?
Yes, currently we use either combined or separate knobs.
> > I saw Chris also mentioned Google has a workaround internally for it
> > for Cgroup V2. This will be a blocker for us and a similar workaround
> > might be needed. It will be great so see an upstream support for this.
>
> I think that _at least_ we should refactor the code so that it would
> be a minimal patch (e.g. one #define) to switch to the old mode.
>
> I don't think it's reasonable to add a new interface, but having a
> patch/config option or even a mount option which changes the semantics
> of memory.swap.max to the v1-like behavior should be ok.
>
> I'll try to do the first part (refactoring this code), and we can have
> a discussion from there.
Thanks, that sounds like a good start.