memcg: only free spare array when readers are done

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index eaa3accb01e708a11986135a8df1146f7dbc1b4b..437ae2cbe102c6ca8f63da86b86f5d26135c5a7b 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5790,16 +5790,17 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
 swap_buffers:
        /* Swap primary and spare array */
        thresholds->spare = thresholds->primary;
-       /* If all events are unregistered, free the spare array */
-       if (!new) {
-               kfree(thresholds->spare);
-               thresholds->spare = NULL;
-       }
 
        rcu_assign_pointer(thresholds->primary, new);
 
        /* To be sure that nobody uses thresholds */
        synchronize_rcu();
+
+       /* If all events are unregistered, free the spare array */
+       if (!new) {
+               kfree(thresholds->spare);
+               thresholds->spare = NULL;
+       }
 unlock:
        mutex_unlock(&memcg->thresholds_lock);
 }