2024-06-14 01:08:13

by Baolin Wang

Subject: [PATCH] mm: memcontrol: add VM_BUG_ON_FOLIO() to catch lru folio in mem_cgroup_migrate()

The mem_cgroup_migrate() will clear the memcg data of the old folio,
therefore, the callers must make sure the old folio is no longer on
the LRU list, otherwise the old folio can not get the correct lruvec
object without the memcg data, which could lead to potential problems [1].

Thus adding a VM_BUG_ON_FOLIO() to catch this issue.

[1] https://lore.kernel.org/all/5ab860d8ee987955e917748f9d6da525d3b52690.1718326003.git.baolin.wang@linux.alibaba.com/
Suggested-by: Shakeel Butt <[email protected]>
Signed-off-by: Baolin Wang <[email protected]>
---
mm/memcontrol.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4d9fda1d84a0..62fa3869065c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7844,6 +7844,7 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
VM_BUG_ON_FOLIO(folio_test_anon(old) != folio_test_anon(new), new);
VM_BUG_ON_FOLIO(folio_nr_pages(old) != folio_nr_pages(new), new);
+ VM_BUG_ON_FOLIO(folio_test_lru(old), old);

if (mem_cgroup_disabled())
return;
--
2.39.3

2024-06-14 15:09:49

by Shakeel Butt

Subject: Re: [PATCH] mm: memcontrol: add VM_BUG_ON_FOLIO() to catch lru folio in mem_cgroup_migrate()

On Fri, Jun 14, 2024 at 09:07:42AM GMT, Baolin Wang wrote:
> The mem_cgroup_migrate() will clear the memcg data of the old folio,
> therefore, the callers must make sure the old folio is no longer on
> the LRU list, otherwise the old folio can not get the correct lruvec
> object without the memcg data, which could lead to potential problems [1].
>
> Thus adding a VM_BUG_ON_FOLIO() to catch this issue.
>
> [1] https://lore.kernel.org/all/5ab860d8ee987955e917748f9d6da525d3b52690.1718326003.git.baolin.wang@linux.alibaba.com/
> Suggested-by: Shakeel Butt <[email protected]>
> Signed-off-by: Baolin Wang <[email protected]>

Acked-by: Shakeel Butt <[email protected]>