LinuxLists.cc - [patch] memcg: add memcg sanity checks at allocating and freeing pages

2011-02-03 14:15:47

Subject: [patch] memcg: add memcg sanity checks at allocating and freeing pages

From: Daisuke Nishimura <[email protected]>

This patch add checks at allocating or freeing a page whether the page is used
(iow, charged) from the view point of memcg.

This check may be useful in debugging a problem and we did similar checks
before the commit 52d4b9ac(memcg: allocate all page_cgroup at boot).

This patch adds some overheads at allocating or freeing memory, so it's enabled
only when CONFIG_DEBUG_VM is enabled.

Signed-off-by: Daisuke Nishimura <[email protected]>
Signed-off-by: Johannes Weiner <[email protected]>
---
include/linux/memcontrol.h | 17 +++++++++++++++++
mm/memcontrol.c | 30 ++++++++++++++++++++++++++++++
mm/page_alloc.c | 8 ++++++--
3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a1a1e53..3da48ae 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -150,6 +150,10 @@ u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail);
#endif

+#ifdef CONFIG_DEBUG_VM
+bool mem_cgroup_bad_page_check(struct page *page);
+void mem_cgroup_print_bad_page(struct page *page);
+#endif
#else /* CONFIG_CGROUP_MEM_RES_CTLR */
struct mem_cgroup;

@@ -346,5 +350,18 @@ static inline void mem_cgroup_split_huge_fixup(struct page *head,

#endif /* CONFIG_CGROUP_MEM_CONT */

+#if !defined(CONFIG_CGROUP_MEM_RES_CTLR) || !defined(CONFIG_DEBUG_VM)
+static inline bool
+mem_cgroup_bad_page_check(struct page *page)
+{
+ return false;
+}
+
+static inline void
+mem_cgroup_print_bad_page(struct page *page)
+{
+}
+#endif
+
#endif /* _LINUX_MEMCONTROL_H */

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6abaa10..2ed1b33 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3016,6 +3016,36 @@ int mem_cgroup_shmem_charge_fallback(struct page *page,
return ret;
}

+#ifdef CONFIG_DEBUG_VM
+static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
+{
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup(page);
+ if (likely(pc) && PageCgroupUsed(pc))
+ return pc;
+ return NULL;
+}
+
+bool mem_cgroup_bad_page_check(struct page *page)
+{
+ if (mem_cgroup_disabled())
+ return false;
+
+ return lookup_page_cgroup_used(page) != NULL;
+}
+
+void mem_cgroup_print_bad_page(struct page *page)
+{
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup_used(page);
+ if (pc)
+ printk(KERN_ALERT "pc:%p pc->flags:%ld pc->mem_cgroup:%p\n",
+ pc, pc->flags, pc->mem_cgroup);
+}
+#endif
+
static DEFINE_MUTEX(set_limit_mutex);

static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 26df268..60e58b0 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -53,6 +53,7 @@
#include <linux/compaction.h>
#include <trace/events/kmem.h>
#include <linux/ftrace_event.h>
+#include <linux/memcontrol.h>

#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -565,7 +566,8 @@ static inline int free_pages_check(struct page *page)
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
+ (page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
+ (mem_cgroup_bad_page_check(page)))) {
bad_page(page);
return 1;
}
@@ -750,7 +752,8 @@ static inline int check_new_page(struct page *page)
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
+ (page->flags & PAGE_FLAGS_CHECK_AT_PREP) |
+ (mem_cgroup_bad_page_check(page)))) {
bad_page(page);
return 1;
}
@@ -5693,4 +5696,5 @@ void dump_page(struct page *page)
page, atomic_read(&page->_count), page_mapcount(page),
page->mapping, page->index);
dump_page_flags(page->flags);
+ mem_cgroup_print_bad_page(page);
}
--
1.7.4

2011-02-04 00:06:14

by Kamezawa Hiroyuki

[permalink] [raw]

Subject: Re: [patch] memcg: add memcg sanity checks at allocating and freeing pages

2011-02-04 03:39:41

by Daisuke Nishimura

[permalink] [raw]

Subject: Re: [patch] memcg: add memcg sanity checks at allocating and freeing pages

On Thu, 3 Feb 2011 15:15:33 +0100
Johannes Weiner <[email protected]> wrote:

> From: Daisuke Nishimura <[email protected]>
>
> This patch add checks at allocating or freeing a page whether the page is used
> (iow, charged) from the view point of memcg.
>
> This check may be useful in debugging a problem and we did similar checks
> before the commit 52d4b9ac(memcg: allocate all page_cgroup at boot).
>
> This patch adds some overheads at allocating or freeing memory, so it's enabled
> only when CONFIG_DEBUG_VM is enabled.
>
> Signed-off-by: Daisuke Nishimura <[email protected]>
> Signed-off-by: Johannes Weiner <[email protected]>

Thank you for picking up this patch. You actually remind me about this patch :)

I have one comment.

> +void mem_cgroup_print_bad_page(struct page *page)
> +{
> + struct page_cgroup *pc;
> +
> + pc = lookup_page_cgroup_used(page);
> + if (pc)
> + printk(KERN_ALERT "pc:%p pc->flags:%ld pc->mem_cgroup:%p\n",
> + pc, pc->flags, pc->mem_cgroup);
> +}
> +#endif
> +
When I posted this patch before, I received a comment that showing the path of
the cgroup would be better.
This is a additional patch to show the path.

===
From: Daisuke Nishimura <[email protected]>

Let's try to show the path name of the cgroup too.

Signed-off-by: Daisuke Nishimura <[email protected]>
---
mm/memcontrol.c | 20 ++++++++++++++++++--
1 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2ed1b33..3c14d20 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3040,9 +3040,25 @@ void mem_cgroup_print_bad_page(struct page *page)
struct page_cgroup *pc;

pc = lookup_page_cgroup_used(page);
- if (pc)
- printk(KERN_ALERT "pc:%p pc->flags:%ld pc->mem_cgroup:%p\n",
+ if (pc) {
+ int ret = -1;
+ char *path;
+
+ printk(KERN_ALERT "pc:%p pc->flags:%ld pc->mem_cgroup:%p",
pc, pc->flags, pc->mem_cgroup);
+
+ path = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (path) {
+ rcu_read_lock();
+ ret = cgroup_path(pc->mem_cgroup->css.cgroup,
+ path, PATH_MAX);
+ rcu_read_unlock();
+ }
+
+ printk(KERN_ALERT "(%s)\n",
+ (ret < 0) ? "cannot get the path" : path);
+ kfree(path);
+ }
}
#endif

--
1.7.1