1 files changed, 4 insertions, 1 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6728a7ae6f2d..228d6461c12a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4414,6 +4414,9 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
          */
         BUG_ON(!thresholds);
 
+        if (!thresholds->primary)
+                goto unlock;
+
         usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
 
         /* Check if a threshold crossed before removing */
@@ -4462,7 +4465,7 @@ swap_buffers:
 
         /* To be sure that nobody uses thresholds */
         synchronize_rcu();
-
+unlock:
         mutex_unlock(&memcg->thresholds_lock);
 }