mm: memcontrol: add VM_BUG_ON_FOLIO() to catch lru folio in mem_cgroup_migrate()

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/

Link: https://lkml.kernel.org/r/66d181c41b7ced35dbd39ffd3f5774a11aef266a.1718327124.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Suggested-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9d7255f47329090d90da4b61ba0abd5fd84791bf..6244752dd1540708940aa717180101509d1db43d 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7807,6 +7807,7 @@ 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;