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-rw-r--r--mm/memcontrol.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c265212bec8c..66beca1ad92f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2559,6 +2559,15 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
return 0;
mctz = soft_limit_tree_node(pgdat->node_id);
+
+ /*
+ * Do not even bother to check the largest node if the root
+ * is empty. Do it lockless to prevent lock bouncing. Races
+ * are acceptable as soft limit is best effort anyway.
+ */
+ if (RB_EMPTY_ROOT(&mctz->rb_root))
+ return 0;
+
/*
* This loop can run a while, specially if mem_cgroup's continuously
* keep exceeding their soft limit and putting the system under