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Subject[PATCH] mm: memcontrol: fix get_active_memcg return value
Date
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.

Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/memcontrol.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index be6bc5044150..bbe25655f7eb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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;
--
2.11.0
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