diff options
| author | Muchun Song <songmuchun@bytedance.com> | 2025-03-06 10:31:33 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-16 17:40:24 -0700 |
| commit | 73f839b6d2ed75f281bd75aeb68e81bce373bdee (patch) | |
| tree | c16eddc1ff554a9a869796f0b81c86d0ed704703 /mm | |
| parent | mm/vma: do not register private-anon mappings with khugepaged during mmap (diff) | |
| download | linux-73f839b6d2ed75f281bd75aeb68e81bce373bdee.tar.gz linux-73f839b6d2ed75f281bd75aeb68e81bce373bdee.zip | |
mm: memcontrol: fix swap counter leak from offline cgroup
Commit 6769183166b3 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: 6769183166b3 ("mm/swap_cgroup: decouple swap cgroup recording and clearing")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Kairui 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: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 4 | ||||
| -rw-r--r-- | mm/swap_cgroup.c | 7 |
2 files changed, 6 insertions, 5 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4de6acb9b8ec..8f9b35f80e24 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4993,7 +4993,7 @@ void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) mem_cgroup_id_get_many(swap_memcg, nr_entries - 1); mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries); - swap_cgroup_record(folio, entry); + swap_cgroup_record(folio, mem_cgroup_id(swap_memcg), entry); folio_unqueue_deferred_split(folio); folio->memcg_data = 0; @@ -5055,7 +5055,7 @@ int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry) mem_cgroup_id_get_many(memcg, nr_pages - 1); mod_memcg_state(memcg, MEMCG_SWAP, nr_pages); - swap_cgroup_record(folio, entry); + swap_cgroup_record(folio, mem_cgroup_id(memcg), entry); return 0; } diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c index be39078f255b..1007c30f12e2 100644 --- a/mm/swap_cgroup.c +++ b/mm/swap_cgroup.c @@ -58,9 +58,11 @@ static unsigned short __swap_cgroup_id_xchg(struct swap_cgroup *map, * entries must not have been charged * * @folio: the folio that the swap entry belongs to + * @id: mem_cgroup ID to be recorded * @ent: the first swap entry to be recorded */ -void swap_cgroup_record(struct folio *folio, swp_entry_t ent) +void swap_cgroup_record(struct folio *folio, unsigned short id, + swp_entry_t ent) { unsigned int nr_ents = folio_nr_pages(folio); struct swap_cgroup *map; @@ -72,8 +74,7 @@ void swap_cgroup_record(struct folio *folio, swp_entry_t ent) map = swap_cgroup_ctrl[swp_type(ent)].map; do { - old = __swap_cgroup_id_xchg(map, offset, - mem_cgroup_id(folio_memcg(folio))); + old = __swap_cgroup_id_xchg(map, offset, id); VM_BUG_ON(old); } while (++offset != end); } |