[PATCH v1 26/26] mm: lru: add VM_WARN_ON_ONCE_FOLIO to lru maintenance helpers

Qi Zheng
2025-10-28T14:07:55Z

From: Muchun Song <songmuchun@bytedance.com>

We must ensure the folio is deleted from or added to the correct lruvec
list. So, add VM_WARN_ON_ONCE_FOLIO() to catch invalid users. The
VM_BUG_ON_PAGE() in move_pages_to_lru() can be removed as
add_page_to_lru_list() will perform the necessary check.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
include/linux/mm_inline.h | 6 ++++++
mm/vmscan.c | 1 -
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index f6a2b2d200162..dfed0523e0c43 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -342,6 +342,8 @@ void lruvec_add_folio(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);

+ VM_WARN_ON_ONCE_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
+
if (lru_gen_add_folio(lruvec, folio, false))
return;

@@ -356,6 +358,8 @@ void lruvec_add_folio_tail(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);

+ VM_WARN_ON_ONCE_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
+
if (lru_gen_add_folio(lruvec, folio, true))
return;

@@ -370,6 +374,8 @@ void lruvec_del_folio(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);

+ VM_WARN_ON_ONCE_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
+
if (lru_gen_del_folio(lruvec, folio, false))
return;

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 82c4cc6edbca5..5f22ec438c018 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1934,7 +1934,6 @@ static unsigned int move_folios_to_lru(struct list_head *list)
continue;
}

- VM_BUG_ON_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
lruvec_add_folio(lruvec, folio);
nr_pages = folio_nr_pages(folio);
nr_moved += nr_pages;
--
2.20.1