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>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c02d870..f6c4beb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4742,7 +4742,6 @@
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 @@
mz->on_tree = false;
mz->mem = memcg;
}
+ memcg->info.nodeinfo[node] = pn;
return 0;
}