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 <[email protected]>
Signed-off-by: Li Zefan <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Glauber Costa <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: <[email protected]>	[3.9+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 64f726599ff06c6319b82c05dc5a93ef17f5fe09..6b73d8657d64ae45bfd0085e6d4111fa417f3337 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6352,8 +6352,6 @@ mem_cgroup_css_online(struct cgroup *cont)
                 * call __mem_cgroup_free, so return directly
                 */
                mem_cgroup_put(memcg);
-               if (parent->use_hierarchy)
-                       mem_cgroup_put(parent);
        }
        return error;
 }