From 2b14e9cf1541415382213d2fa23fc1386f52c41c Mon Sep 17 00:00:00 2001
From: Hillf Danton <dhillf@gmail.com>
Date: Fri, 16 Dec 2011 15:49:24 +1100
Subject: [PATCH] memcg: keep root group unchanged if creation fails

If the request is to create non-root group and we fail to meet it, we
should leave the root unchanged.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/memcontrol.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d77dce0b4e62..31f2d6c224f4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5118,9 +5118,9 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 		int cpu;
 		enable_swap_cgroup();
 		parent = NULL;
-		root_mem_cgroup = memcg;
 		if (mem_cgroup_soft_limit_tree_init())
 			goto free_out;
+		root_mem_cgroup = memcg;
 		for_each_possible_cpu(cpu) {
 			struct memcg_stock_pcp *stock =
 						&per_cpu(memcg_stock, cpu);
@@ -5161,7 +5161,6 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	return &memcg->css;
 free_out:
 	__mem_cgroup_free(memcg);
-	root_mem_cgroup = NULL;
 	return ERR_PTR(error);
 }
 
-- 
2.39.5