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mm: memcontrol: fix get_active_memcg return value 

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@bytedance.com
Fixes: 37d5985c00 ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Muchun Song 2021-02-24 12:04:22 -08:00 committed by Linus Torvalds
parent cae3af62b3
commit 1685bde6b9
1 changed files with 3 additions and 7 deletions
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10
mm/memcontrol.c
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@ -1061,13 +1061,9 @@ static __always_inline struct mem_cgroup *get_active_memcg(void)
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;