[PATCH RFC 28/28] mm: lru: add VM_WARN_ON_ONCE_FOLIO to lru maintenance helpers

[Muchun Song]

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@xxxxxxxxxxxxx>
Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
---
 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 f9157a0c42a5..f36491c42ace 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -341,6 +341,8 @@ 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;
 
@@ -355,6 +357,8 @@ 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;
 
@@ -369,6 +373,8 @@ 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 fbba14094c6d..a59268bf4112 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1952,7 +1952,6 @@ 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