The patch titled
Subject: memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge()
has been added to the -mm tree. Its filename is
memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge.patch
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------------------------------------------------------
From: Tejun Heo <tj@xxxxxxxxxx>
Subject: memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge()
mem_cgroup_move_charge() invokes lru_add_drain_all() so that the pvec
pages can be moved too. lru_add_drain_all() schedules and flushes work
items on system_wq which depends on being able to create new kworkers to
make forward progress. Since 1ed1328792ff ("sched, cgroup: replace
signal_struct->group_rwsem with a global percpu_rwsem"), a new task can't
be created while in the cgroup migration path and the described
lru_add_drain_all() invocation can easily lead to a deadlock.
Charge moving is best-effort and whether the pvec pages are migrated or
not doesn't really matter. Don't call it during charge moving.
Eventually, we want to move the actual charge moving outside the migration
path.
Fixes: 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem")
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Debugged-by: Petr Mladek <pmladek@xxxxxxxx>
Tested-by: Petr Mladek <pmladek@xxxxxxxx>
Reported-by: Cyril Hrubis <chrubis@xxxxxxx>
Reported-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.4+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 1 -
1 file changed, 1 deletion(-)
diff -puN mm/memcontrol.c~memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge
+++ a/mm/memcontrol.c
@@ -4859,7 +4859,6 @@ static void mem_cgroup_move_charge(struc
.mm = mm,
};
- lru_add_drain_all();
/*
* Signal lock_page_memcg() to take the memcg's move_lock
* while we're moving its pages to another memcg. Then wait
_
Patches currently in -mm which might be from tj@xxxxxxxxxx are
memcg-remove-lru_add_drain_all-invocation-from-mem_cgroup_move_charge.patch
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