Merge remote-tracking branch 'remotes/stable/linux-4.4.y' into karo-tx6-mainline

[karo-tx-linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6ba4dd988e2e49b1ede4105d5efbcb19e9f3864e..67648e6b2ac85e081f74084e8b4525a34c84f3ae 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3661,6 +3661,7 @@ static void memcg_deactivate_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);
@@ -3668,6 +3669,8 @@ static void memcg_deactivate_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);