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-rw-r--r--mm/memcontrol.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 925b431f3f03..58c69c94402a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2896,6 +2896,7 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
* ordering is imposed by list_lru_node->lock taken by
* memcg_drain_all_list_lrus().
*/
+ rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */
css_for_each_descendant_pre(css, &memcg->css) {
child = mem_cgroup_from_css(css);
BUG_ON(child->kmemcg_id != kmemcg_id);
@@ -2903,6 +2904,8 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
if (!memcg->use_hierarchy)
break;
}
+ rcu_read_unlock();
+
memcg_drain_all_list_lrus(kmemcg_id, parent->kmemcg_id);
memcg_free_cache_id(kmemcg_id);