[PATCH] mm/memcontrol: skip obj_stock drain when refilled objcg shares memcg

[Shakeel Butt]

Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
---
 mm/memcontrol.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d978e18b9b2d..01ed7a8e18ac 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3318,6 +3318,7 @@ static void __refill_obj_stock(struct obj_cgroup *objcg,
 			       unsigned int nr_bytes,
 			       bool allow_uncharge)
 {
+	struct obj_cgroup *cached;
 	unsigned int nr_pages = 0;
 
 	if (!stock) {
@@ -3327,7 +3328,18 @@ static void __refill_obj_stock(struct obj_cgroup *objcg,
 		goto out;
 	}
 
-	if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */
+	cached = READ_ONCE(stock->cached_objcg);
+	if (cached != objcg &&
+	    (!cached || obj_cgroup_memcg(cached) != obj_cgroup_memcg(objcg))) {
 		drain_obj_stock(stock);
 		obj_cgroup_get(objcg);
 		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
-- 
2.53.0-Meta