This is a note to let you know that I've just added the patch titled
mm: memcontrol: fix get_active_memcg return value
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-memcontrol-fix-get_active_memcg-return-value.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1685bde6b9af55923180a76152036c7fb7176db0 Mon Sep 17 00:00:00 2001
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Date: Wed, 24 Feb 2021 12:04:22 -0800
Subject: mm: memcontrol: fix get_active_memcg return value
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
commit 1685bde6b9af55923180a76152036c7fb7176db0 upstream.
We use a global percpu int_active_memcg variable to store the remote memcg
when we are in the interrupt context. But get_active_memcg always return
the current->active_memcg or root_mem_cgroup. The remote memcg (set in
the interrupt context) is ignored. This is not what we want. So fix it.
Link: https://lkml.kernel.org/r/20210223091101.42150-1-songmuchun@xxxxxxxxxxxxx
Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1083,13 +1083,9 @@ static __always_inline struct mem_cgroup
rcu_read_lock();
memcg = active_memcg();
- if (memcg) {
- /* current->active_memcg must hold a ref. */
- if (WARN_ON_ONCE(!css_tryget(&memcg->css)))
- memcg = root_mem_cgroup;
- else
- memcg = current->active_memcg;
- }
+ /* remote memcg must hold a ref. */
+ if (memcg && WARN_ON_ONCE(!css_tryget(&memcg->css)))
+ memcg = root_mem_cgroup;
rcu_read_unlock();
return memcg;
Patches currently in stable-queue which might be from songmuchun@xxxxxxxxxxxxx are
queue-5.10/mm-memcontrol-fix-slub-memory-accounting.patch
queue-5.10/mm-memcontrol-fix-nr_anon_thps-accounting-in-charge-.patch
queue-5.10/mm-memcontrol-fix-get_active_memcg-return-value.patch
queue-5.10/mm-memcontrol-fix-swap-undercounting-in-cgroup2.patch
