[Devel] [PATCH rh7] mm/memcg: cleanup vmpressure from mem_cgroup_css_free()

[Andrey Ryabinin]

Cleaning up vmpressure from mem_cgroup_css_offline() doesn't look
safe. It looks like mem_cgroup_css_offline() might race with reclaim
which will queue vmpressure work  after the flush.

Put vmpressure_cleanup() in mem_cgroup_css_free() where we have
exclusive access to memcg. It was originally there, see
https://jira.sw.ru/browse/PSBM-93884 but moved in a process of rebase.

https://jira.sw.ru/browse/PSBM-122653
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/memcontrol.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e36ad592b3c7..803273a4d9cb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6822,8 +6822,6 @@ static void mem_cgroup_css_offline(struct cgroup *cont)
 	mem_cgroup_free_all(memcg);
 	mem_cgroup_reparent_charges(memcg);
 
-	vmpressure_cleanup(&memcg->vmpressure);
-
 	/*
 	 * A cgroup can be destroyed while somebody is waiting for its
 	 * oom context, in which case the context will never be unlocked
@@ -6878,7 +6876,7 @@ static void mem_cgroup_css_free(struct cgroup *cont)
 	mem_cgroup_reparent_charges(memcg);
 
 	cancel_work_sync(&memcg->high_work);
-
+	vmpressure_cleanup(&memcg->vmpressure);
 	memcg_destroy_kmem(memcg);
 	memcg_free_shrinker_maps(memcg);
 	__mem_cgroup_free(memcg);
-- 
2.26.2