cgroups: use hierarchy mutex in creation failure path

Now, cgrp->sibling is handled under hierarchy mutex.
error route should do so, too.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Acked-by Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c29831076e7a..2ae7cb47dbfa 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2434,7 +2434,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
  err_remove:
 
+        cgroup_lock_hierarchy(root);
         list_del(&cgrp->sibling);
+        cgroup_unlock_hierarchy(root);
         root->number_of_cgroups--;
 
  err_destroy: