[PATCH 3/3] memcg: bail out proactive reclaim when memcg is dying

[Jiayuan Chen <jiayuan.chen@linux.dev>]

From: Jiayuan Chen <jiayuan.chen@shopee.com>

Proactive reclaim via memory.reclaim can run for a long time - swap I/O
or thrashing again dominating the latency - and delays cgroup removal in
the same way.

Mitigate this by stopping the reclaim once memcg_is_dying().

Reported-by: Zhou Yingfu <yingfu.zhou@shopee.com>
Cc: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
---
 mm/vmscan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8190c4abec84..1162b7f76655 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7922,6 +7922,9 @@ int user_proactive_reclaim(char *buf,
 		if (memcg) {
 			unsigned int reclaim_options;
 
+			if (memcg_is_dying(memcg))
+				break;
+
 			reclaim_options = MEMCG_RECLAIM_MAY_SWAP |
 					  MEMCG_RECLAIM_PROACTIVE;
 			reclaimed = try_to_free_mem_cgroup_pages(memcg,
-- 
2.43.0