Normally the pointer to the cgroup to uncharge hangs off the struct
page, and gets queried when it's time to free the page. With
hugetlb_cgroup reservations, this is not possible. Because it's possible
for a page to be reserved by one task and actually faulted in by another
task.
The best place to put the hugetlb_cgroup pointer to uncharge for
reservations is in the resv_map. But, because the resv_map has different
semantics for private and shared mappings, the code patch to
charge/uncharge shared and private mappings is different. This patch
implements charging and uncharging for private mappings.
For private mappings, the counter to uncharge is in
resv_map->reservation_counter. On initializing the resv_map this is set
to NULL. On reservation of a region in private mapping, the tasks
hugetlb_cgroup is charged and the hugetlb_cgroup is placed is
resv_map->reservation_counter.
On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter.
Signed-off-by: Mina Almasry <[email protected]>
---
Changes in v10:
- Fixed cases where the mapping is private but cgroup accounting is disabled.
Changes in V9:
- Updated for reparenting of hugetlb reservation accounting.
---
include/linux/hugetlb.h | 10 +++++++++
include/linux/hugetlb_cgroup.h | 27 ++++++++++++++++++++++++
mm/hugetlb.c | 38 +++++++++++++++++++++++++++++++++-
mm/hugetlb_cgroup.c | 28 -------------------------
4 files changed, 74 insertions(+), 29 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index dea6143aa0685..5491932ea5758 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -46,6 +46,16 @@ struct resv_map {
long adds_in_progress;
struct list_head region_cache;
long region_cache_count;
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * On private mappings, the counter to uncharge reservations is stored
+ * here. If these fields are 0, then either the mapping is shared, or
+ * cgroup accounting is disabled for this resv_map.
+ */
+ struct page_counter *reservation_counter;
+ unsigned long pages_per_hpage;
+ struct cgroup_subsys_state *css;
+#endif
};
extern struct resv_map *resv_map_alloc(void);
void resv_map_release(struct kref *ref);
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index eab8a70d5bcb5..8c320accefe87 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -25,6 +25,33 @@ struct hugetlb_cgroup;
#define HUGETLB_CGROUP_MIN_ORDER 2
#ifdef CONFIG_CGROUP_HUGETLB
+enum hugetlb_memory_event {
+ HUGETLB_MAX,
+ HUGETLB_NR_MEMORY_EVENTS,
+};
+
+struct hugetlb_cgroup {
+ struct cgroup_subsys_state css;
+
+ /*
+ * the counter to account for hugepages from hugetlb.
+ */
+ struct page_counter hugepage[HUGE_MAX_HSTATE];
+
+ /*
+ * the counter to account for hugepage reservations from hugetlb.
+ */
+ struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
+
+ atomic_long_t events[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
+ atomic_long_t events_local[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
+
+ /* Handle for "hugetlb.events" */
+ struct cgroup_file events_file[HUGE_MAX_HSTATE];
+
+ /* Handle for "hugetlb.events.local" */
+ struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
+};
static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page,
bool reserved)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 62a4cf3db4090..f1b63946ee95c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -666,6 +666,17 @@ struct resv_map *resv_map_alloc(void)
INIT_LIST_HEAD(&resv_map->regions);
resv_map->adds_in_progress = 0;
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * Initialize these to 0. On shared mappings, 0's here indicate these
+ * fields don't do cgroup accounting. On private mappings, these will be
+ * re-initialized to the proper values, to indicate that hugetlb cgroup
+ * reservations are to be un-charged from here.
+ */
+ resv_map->reservation_counter = NULL;
+ resv_map->pages_per_hpage = 0;
+ resv_map->css = NULL;
+#endif
INIT_LIST_HEAD(&resv_map->region_cache);
list_add(&rg->link, &resv_map->region_cache);
@@ -3194,7 +3205,11 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
reserve = (end - start) - region_count(resv, start, end);
- kref_put(&resv->refs, resv_map_release);
+#ifdef CONFIG_CGROUP_HUGETLB
+ hugetlb_cgroup_uncharge_counter(resv->reservation_counter,
+ (end - start) * resv->pages_per_hpage,
+ resv->css);
+#endif
if (reserve) {
/*
@@ -3204,6 +3219,8 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
hugetlb_acct_memory(h, -gbl_reserve);
}
+
+ kref_put(&resv->refs, resv_map_release);
}
static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
@@ -4550,6 +4567,7 @@ int hugetlb_reserve_pages(struct inode *inode,
struct hstate *h = hstate_inode(inode);
struct hugepage_subpool *spool = subpool_inode(inode);
struct resv_map *resv_map;
+ struct hugetlb_cgroup *h_cg;
long gbl_reserve;
/* This should never happen */
@@ -4583,12 +4601,30 @@ int hugetlb_reserve_pages(struct inode *inode,
chg = region_chg(resv_map, from, to);
} else {
+ /* Private mapping. */
resv_map = resv_map_alloc();
if (!resv_map)
return -ENOMEM;
chg = to - from;
+ if (hugetlb_cgroup_charge_cgroup(hstate_index(h),
+ chg * pages_per_huge_page(h),
+ &h_cg, true)) {
+ kref_put(&resv_map->refs, resv_map_release);
+ return -ENOMEM;
+ }
+
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * Since this branch handles private mappings, we attach the
+ * counter to uncharge for this reservation off resv_map.
+ */
+ resv_map->reservation_counter =
+ &h_cg->reserved_hugepage[hstate_index(h)];
+ resv_map->pages_per_hpage = pages_per_huge_page(h);
+#endif
+
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index c434f69f38354..ddfdf19a9ad35 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -23,34 +23,6 @@
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
-enum hugetlb_memory_event {
- HUGETLB_MAX,
- HUGETLB_NR_MEMORY_EVENTS,
-};
-
-struct hugetlb_cgroup {
- struct cgroup_subsys_state css;
-
- /*
- * the counter to account for hugepages from hugetlb.
- */
- struct page_counter hugepage[HUGE_MAX_HSTATE];
-
- /*
- * the counter to account for hugepage reservations from hugetlb.
- */
- struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
-
- atomic_long_t events[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
- atomic_long_t events_local[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
-
- /* Handle for "hugetlb.events" */
- struct cgroup_file events_file[HUGE_MAX_HSTATE];
-
- /* Handle for "hugetlb.events.local" */
- struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
-};
-
#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
#define MEMFILE_IDX(val) (((val) >> 16) & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
--
2.25.0.rc1.283.g88dfdc4193-goog
On 1/14/20 5:26 PM, Mina Almasry wrote:
> Normally the pointer to the cgroup to uncharge hangs off the struct
> page, and gets queried when it's time to free the page. With
> hugetlb_cgroup reservations, this is not possible. Because it's possible
> for a page to be reserved by one task and actually faulted in by another
> task.
>
> The best place to put the hugetlb_cgroup pointer to uncharge for
> reservations is in the resv_map. But, because the resv_map has different
> semantics for private and shared mappings, the code patch to
> charge/uncharge shared and private mappings is different. This patch
> implements charging and uncharging for private mappings.
>
> For private mappings, the counter to uncharge is in
> resv_map->reservation_counter. On initializing the resv_map this is set
> to NULL. On reservation of a region in private mapping, the tasks
> hugetlb_cgroup is charged and the hugetlb_cgroup is placed is
> resv_map->reservation_counter.
>
> On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter.
>
> Signed-off-by: Mina Almasry <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
--
Mike Kravetz
On Tue, 14 Jan 2020, Mina Almasry wrote:
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index dea6143aa0685..5491932ea5758 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -46,6 +46,16 @@ struct resv_map {
> long adds_in_progress;
> struct list_head region_cache;
> long region_cache_count;
> +#ifdef CONFIG_CGROUP_HUGETLB
> + /*
> + * On private mappings, the counter to uncharge reservations is stored
> + * here. If these fields are 0, then either the mapping is shared, or
> + * cgroup accounting is disabled for this resv_map.
> + */
> + struct page_counter *reservation_counter;
> + unsigned long pages_per_hpage;
> + struct cgroup_subsys_state *css;
> +#endif
> };
> extern struct resv_map *resv_map_alloc(void);
> void resv_map_release(struct kref *ref);
> diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> index eab8a70d5bcb5..8c320accefe87 100644
> --- a/include/linux/hugetlb_cgroup.h
> +++ b/include/linux/hugetlb_cgroup.h
> @@ -25,6 +25,33 @@ struct hugetlb_cgroup;
> #define HUGETLB_CGROUP_MIN_ORDER 2
>
> #ifdef CONFIG_CGROUP_HUGETLB
> +enum hugetlb_memory_event {
> + HUGETLB_MAX,
> + HUGETLB_NR_MEMORY_EVENTS,
> +};
> +
> +struct hugetlb_cgroup {
> + struct cgroup_subsys_state css;
> +
> + /*
> + * the counter to account for hugepages from hugetlb.
> + */
> + struct page_counter hugepage[HUGE_MAX_HSTATE];
> +
> + /*
> + * the counter to account for hugepage reservations from hugetlb.
> + */
> + struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
> +
> + atomic_long_t events[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
> + atomic_long_t events_local[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
> +
> + /* Handle for "hugetlb.events" */
> + struct cgroup_file events_file[HUGE_MAX_HSTATE];
> +
> + /* Handle for "hugetlb.events.local" */
> + struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
> +};
>
> static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page,
> bool reserved)
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 62a4cf3db4090..f1b63946ee95c 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -666,6 +666,17 @@ struct resv_map *resv_map_alloc(void)
> INIT_LIST_HEAD(&resv_map->regions);
>
> resv_map->adds_in_progress = 0;
> +#ifdef CONFIG_CGROUP_HUGETLB
> + /*
> + * Initialize these to 0. On shared mappings, 0's here indicate these
> + * fields don't do cgroup accounting. On private mappings, these will be
> + * re-initialized to the proper values, to indicate that hugetlb cgroup
> + * reservations are to be un-charged from here.
> + */
> + resv_map->reservation_counter = NULL;
> + resv_map->pages_per_hpage = 0;
> + resv_map->css = NULL;
> +#endif
Might be better to extract out a resv_map_init() that does the
initialization when CONFIG_CGROUP_HUGETLB is enabled? Could be used here
as well as hugetlb_reserve_pages().
>
> INIT_LIST_HEAD(&resv_map->region_cache);
> list_add(&rg->link, &resv_map->region_cache);
> @@ -3194,7 +3205,11 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
>
> reserve = (end - start) - region_count(resv, start, end);
>
> - kref_put(&resv->refs, resv_map_release);
> +#ifdef CONFIG_CGROUP_HUGETLB
> + hugetlb_cgroup_uncharge_counter(resv->reservation_counter,
> + (end - start) * resv->pages_per_hpage,
> + resv->css);
> +#endif
>
> if (reserve) {
> /*
Mike has given is Reviewed-by so likely not a big concern for the generic
hugetlb code, but I was wondering if we can reduce the number of #ifdef's
if we defined a CONFIG_CGROUP_HUGETLB helper to take the resv, end, and
start? If CONFIG_CGROUP_HUGETLB is defined, it converts into the above,
otherwise it's a no-op and we don't run into any compile errors because we
are accessing fields that don't exist without the option.
Otherwise looks good!
Acked-by: David Rientjes <[email protected]>
On Wed, Jan 29, 2020 at 1:28 PM David Rientjes <[email protected]> wrote:
>
> On Tue, 14 Jan 2020, Mina Almasry wrote:
>
> > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> > index dea6143aa0685..5491932ea5758 100644
> > --- a/include/linux/hugetlb.h
> > +++ b/include/linux/hugetlb.h
> > @@ -46,6 +46,16 @@ struct resv_map {
> > long adds_in_progress;
> > struct list_head region_cache;
> > long region_cache_count;
> > +#ifdef CONFIG_CGROUP_HUGETLB
> > + /*
> > + * On private mappings, the counter to uncharge reservations is stored
> > + * here. If these fields are 0, then either the mapping is shared, or
> > + * cgroup accounting is disabled for this resv_map.
> > + */
> > + struct page_counter *reservation_counter;
> > + unsigned long pages_per_hpage;
> > + struct cgroup_subsys_state *css;
> > +#endif
> > };
> > extern struct resv_map *resv_map_alloc(void);
> > void resv_map_release(struct kref *ref);
> > diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> > index eab8a70d5bcb5..8c320accefe87 100644
> > --- a/include/linux/hugetlb_cgroup.h
> > +++ b/include/linux/hugetlb_cgroup.h
> > @@ -25,6 +25,33 @@ struct hugetlb_cgroup;
> > #define HUGETLB_CGROUP_MIN_ORDER 2
> >
> > #ifdef CONFIG_CGROUP_HUGETLB
> > +enum hugetlb_memory_event {
> > + HUGETLB_MAX,
> > + HUGETLB_NR_MEMORY_EVENTS,
> > +};
> > +
> > +struct hugetlb_cgroup {
> > + struct cgroup_subsys_state css;
> > +
> > + /*
> > + * the counter to account for hugepages from hugetlb.
> > + */
> > + struct page_counter hugepage[HUGE_MAX_HSTATE];
> > +
> > + /*
> > + * the counter to account for hugepage reservations from hugetlb.
> > + */
> > + struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
> > +
> > + atomic_long_t events[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
> > + atomic_long_t events_local[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
> > +
> > + /* Handle for "hugetlb.events" */
> > + struct cgroup_file events_file[HUGE_MAX_HSTATE];
> > +
> > + /* Handle for "hugetlb.events.local" */
> > + struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
> > +};
> >
> > static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page,
> > bool reserved)
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 62a4cf3db4090..f1b63946ee95c 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -666,6 +666,17 @@ struct resv_map *resv_map_alloc(void)
> > INIT_LIST_HEAD(&resv_map->regions);
> >
> > resv_map->adds_in_progress = 0;
> > +#ifdef CONFIG_CGROUP_HUGETLB
> > + /*
> > + * Initialize these to 0. On shared mappings, 0's here indicate these
> > + * fields don't do cgroup accounting. On private mappings, these will be
> > + * re-initialized to the proper values, to indicate that hugetlb cgroup
> > + * reservations are to be un-charged from here.
> > + */
> > + resv_map->reservation_counter = NULL;
> > + resv_map->pages_per_hpage = 0;
> > + resv_map->css = NULL;
> > +#endif
>
> Might be better to extract out a resv_map_init() that does the
> initialization when CONFIG_CGROUP_HUGETLB is enabled? Could be used here
> as well as hugetlb_reserve_pages().
>
> >
> > INIT_LIST_HEAD(&resv_map->region_cache);
> > list_add(&rg->link, &resv_map->region_cache);
> > @@ -3194,7 +3205,11 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
> >
> > reserve = (end - start) - region_count(resv, start, end);
> >
> > - kref_put(&resv->refs, resv_map_release);
> > +#ifdef CONFIG_CGROUP_HUGETLB
> > + hugetlb_cgroup_uncharge_counter(resv->reservation_counter,
> > + (end - start) * resv->pages_per_hpage,
> > + resv->css);
> > +#endif
> >
> > if (reserve) {
> > /*
>
> Mike has given is Reviewed-by so likely not a big concern for the generic
> hugetlb code, but I was wondering if we can reduce the number of #ifdef's
> if we defined a CONFIG_CGROUP_HUGETLB helper to take the resv, end, and
> start? If CONFIG_CGROUP_HUGETLB is defined, it converts into the above,
> otherwise it's a no-op and we don't run into any compile errors because we
> are accessing fields that don't exist without the option.
>
Yes wherever possible I refactored the code a bit to remove #ifdefs in
the middle of hugetlb logic.
> Otherwise looks good!
>
> Acked-by: David Rientjes <[email protected]>