From 0a619e58703b86d53d07e938eade9a91a4a863c6 Mon Sep 17 00:00:00 2001
From: Igor Mammedov <imammedo@redhat.com>
Date: Wed, 2 Nov 2011 13:38:21 -0700
Subject: [PATCH] memcg: do not expose uninitialized mem_cgroup_per_node to
 world

If somebody is touching data too early, it might be easier to diagnose a
problem when dereferencing NULL at mem->info.nodeinfo[node] than trying to
understand why mem_cgroup_per_zone is [un|partly]initialized.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c02d87028b9..f6c4beb4db5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4742,7 +4742,6 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
 	if (!pn)
 		return 1;
 
-	memcg->info.nodeinfo[node] = pn;
 	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
 		mz = &pn->zoneinfo[zone];
 		for_each_lru(l)
@@ -4751,6 +4750,7 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
 		mz->on_tree = false;
 		mz->mem = memcg;
 	}
+	memcg->info.nodeinfo[node] = pn;
 	return 0;
 }