[patch 03/84] mm: memcontrol: fix possible css ref leak on oom

[patch 03/84] mm: memcontrol: fix possible css ref leak on oom

[akpm]

From: Vladimir Davydov <vdavydov@virtuozzo.com>
Subject: mm: memcontrol: fix possible css ref leak on oom

mem_cgroup_oom may be invoked multiple times while a process is handling a
page fault, in which case current->memcg_in_oom will be overwritten
leaking the previously taken css reference.

Link: http://lkml.kernel.org/r/1464019330-7579-1-git-send-email-vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN mm/memcontrol.c~mm-memcontrol-fix-possible-css-ref-leak-on-oom mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcontrol-fix-possible-css-ref-leak-on-oom
+++ a/mm/memcontrol.c
@@ -1604,7 +1604,7 @@ static void memcg_oom_recover(struct mem
 
 static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
 {
-	if (!current->memcg_may_oom)
+	if (!current->memcg_may_oom || current->memcg_in_oom)
 		return;
 	/*
 	 * We are in the middle of the charge context here, so we
_