From: Igor Mammedov <imammedo@redhat.com>
Date: Wed, 5 Oct 2011 00:43:50 +0000 (+1100)
Subject: memcg: do not expose uninitialized mem_cgroup_per_node to world
X-Git-Tag: next-20111013~1^2~51
X-Git-Url: https://git.kernelconcepts.de/?p=karo-tx-linux.git;a=commitdiff_plain;h=93998ad5c1122c00cfa07115b10dd22cfae728db

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>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 613f723ab384..4a8a2488b595 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4743,7 +4743,6 @@ 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)
@@ -4752,6 +4751,7 @@ 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;
 }