mm/memcontrol.c: lost css_put in memcg_expand_shrinker_maps()

for_each_mem_cgroup() increases css reference counter for memory cgroup
and requires to use mem_cgroup_iter_break() if the walk is cancelled.

Link: http://lkml.kernel.org/r/c98414fb-7e1f-da0f-867a-9340ec4bd30b@virtuozzo.com
Fixes: 0a4465d34028 ("mm, memcg: assign memcg-aware shrinkers bitmap to memcg")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6f6dc8712e392e5e958868c6bcc191cee3d1e888..d09776cd6e1041d896aa25e726d55f93e46581ed 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -409,8 +409,10 @@ int memcg_expand_shrinker_maps(int new_id)
                if (mem_cgroup_is_root(memcg))
                        continue;
                ret = memcg_expand_one_shrinker_map(memcg, size, old_size);
-               if (ret)
+               if (ret) {
+                       mem_cgroup_iter_break(NULL, memcg);
                        goto unlock;
+               }
        }
 unlock:
        if (!ret)