diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c27031b4683a..cb98a1889c8c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3480,7 +3480,7 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
 	struct mem_cgroup_thresholds *thresholds;
 	struct mem_cgroup_threshold_ary *new;
 	unsigned long usage;
-	int i, j, size;
+	int i, j, size, entries;
 
 	mutex_lock(&memcg->thresholds_lock);
 
@@ -3500,14 +3500,20 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
 	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
 
 	/* Calculate new number of threshold */
-	size = 0;
+	size = entries = 0;
 	for (i = 0; i < thresholds->primary->size; i++) {
 		if (thresholds->primary->entries[i].eventfd != eventfd)
 			size++;
+		else
+			entries++;
 	}
 
 	new = thresholds->spare;
 
+	/* If no items related to eventfd have been cleared, nothing to do */
+	if (!entries)
+		goto unlock;
+
 	/* Set thresholds array to NULL if we don't have thresholds */
 	if (!size) {
 		kfree(new);