The patch titled
memcg: fix mem_cgroup_shrink_usage()
has been added to the -mm tree. Its filename is
memcg-fix-mem_cgroup_shrink_usage.patch
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Subject: memcg: fix mem_cgroup_shrink_usage()
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Current mem_cgroup_shrink_usage() has two problems.
1. It doesn't call mem_cgroup_out_of_memory and doesn't update
last_oom_jiffies, so pagefault_out_of_memory invokes global OOM.
2. Considering hierarchy, shrinking has to be done from the
mem_over_limit, not from the memcg which the page would be charged to.
mem_cgroup_try_charge_swapin() does all of these things properly, so we
use it and call cancel_charge_swapin when it succeeded.
The name of "shrink_usage" is not appropriate for this behavior, so we
change it too.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: Dhaval Giani <dhaval@xxxxxxxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: YAMAMOTO Takashi <yamamoto@xxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 4 ++--
mm/memcontrol.c | 33 ++++++++++++---------------------
mm/shmem.c | 8 ++++++--
3 files changed, 20 insertions(+), 25 deletions(-)
diff -puN include/linux/memcontrol.h~memcg-fix-mem_cgroup_shrink_usage include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~memcg-fix-mem_cgroup_shrink_usage
+++ a/include/linux/memcontrol.h
@@ -56,7 +56,7 @@ extern void mem_cgroup_move_lists(struct
enum lru_list from, enum lru_list to);
extern void mem_cgroup_uncharge_page(struct page *page);
extern void mem_cgroup_uncharge_cache_page(struct page *page);
-extern int mem_cgroup_shrink_usage(struct page *page,
+extern int mem_cgroup_shmem_charge_fallback(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask);
extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
@@ -155,7 +155,7 @@ static inline void mem_cgroup_uncharge_c
{
}
-static inline int mem_cgroup_shrink_usage(struct page *page,
+static inline int mem_cgroup_shmem_charge_fallback(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask)
{
return 0;
diff -puN mm/memcontrol.c~memcg-fix-mem_cgroup_shrink_usage mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-mem_cgroup_shrink_usage
+++ a/mm/memcontrol.c
@@ -1618,37 +1618,28 @@ void mem_cgroup_end_migration(struct mem
}
/*
- * A call to try to shrink memory usage under specified resource controller.
- * This is typically used for page reclaiming for shmem for reducing side
- * effect of page allocation from shmem, which is used by some mem_cgroup.
+ * A call to try to shrink memory usage on charge failure at shmem's swapin.
+ * Calling hierarchical_reclaim is not enough because we should update
+ * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
+ * Moreover considering hierarchy, we should reclaim from the mem_over_limit,
+ * not from the memcg which this page would be charged to.
+ * try_charge_swapin does all of these works properly.
*/
-int mem_cgroup_shrink_usage(struct page *page,
+int mem_cgroup_shmem_charge_fallback(struct page *page,
struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *mem = NULL;
- int progress = 0;
- int retry = MEM_CGROUP_RECLAIM_RETRIES;
+ int ret;
if (mem_cgroup_disabled())
return 0;
- if (page)
- mem = try_get_mem_cgroup_from_swapcache(page);
- if (!mem && mm)
- mem = try_get_mem_cgroup_from_mm(mm);
- if (unlikely(!mem))
- return 0;
- do {
- progress = mem_cgroup_hierarchical_reclaim(mem,
- gfp_mask, true, false);
- progress += mem_cgroup_check_under_limit(mem);
- } while (!progress && --retry);
+ ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
+ if (!ret)
+ mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
- css_put(&mem->css);
- if (!retry)
- return -ENOMEM;
- return 0;
+ return ret;
}
static DEFINE_MUTEX(set_limit_mutex);
diff -puN mm/shmem.c~memcg-fix-mem_cgroup_shrink_usage mm/shmem.c
--- a/mm/shmem.c~memcg-fix-mem_cgroup_shrink_usage
+++ a/mm/shmem.c
@@ -1340,8 +1340,12 @@ repeat:
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
if (error == -ENOMEM) {
- /* allow reclaim from this memory cgroup */
- error = mem_cgroup_shrink_usage(swappage,
+ /*
+ * reclaim from proper memory cgroup and
+ * call memcg's OOM if needed.
+ */
+ error = mem_cgroup_shmem_charge_fallback(
+ swappage,
current->mm,
gfp);
if (error) {
_
Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are
vmscanmemcg-reintroduce-sc-may_swap.patch
memcg-fix-mem_cgroup_shrink_usage.patch
memcg-add-file-based-rss-accounting.patch
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