Revert "memcg: avoid dangling reference count in creation failure"
This reverts commit e4715f01be697a.
mem_cgroup_put is hierarchy aware so mem_cgroup_put(memcg) already drops
an additional reference from all parents so the additional
mem_cgrroup_put(parent) potentially causes use-after-free.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org> [3.9+]
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 64f7265..6b73d86 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6352,8 +6352,6 @@
* call __mem_cgroup_free, so return directly
*/
mem_cgroup_put(memcg);
- if (parent->use_hierarchy)
- mem_cgroup_put(parent);
}
return error;
}
