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Commit 73f839b6 authored by Muchun Song's avatar Muchun Song Committed by Andrew Morton
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mm: memcontrol: fix swap counter leak from offline cgroup

Commit 67691831 removed the parameter of id from swap_cgroup_record()
and get the memcg id from mem_cgroup_id(folio_memcg(folio)).  However, the
caller of it may update a different memcg's counter instead of
folio_memcg(folio).

E.g.  in the caller of mem_cgroup_swapout(), @swap_memcg could be
different with @memcg and update the counter of @swap_memcg, but
swap_cgroup_record() records the wrong memcg's ID.  When it is uncharged
from __mem_cgroup_uncharge_swap(), the swap counter will leak since the
wrong recorded ID.

Fix it by bringing the parameter of id back.

Link: https://lkml.kernel.org/r/20250306023133.44838-1-songmuchun@bytedance.com


Fixes: 67691831 ("mm/swap_cgroup: decouple swap cgroup recording and clearing")
Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Reviewed-by: default avatarKairui Song <kasong@tencent.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 8c6ff7f1
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