[RFC PATCH v2 17/18] mm: lru: add VM_BUG_ON_PAGE to lru maintenance function

[Muchun Song]

We need to make sure that the page is deleted from or added to the
correct lruvec list. So add a VM_BUG_ON_PAGE() to catch invalid
users.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 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 355ea1ee32bd..d19870448287 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -84,6 +84,8 @@ static __always_inline void add_page_to_lru_list(struct page *page,
 {
 	enum lru_list lru = page_lru(page);
 
+	VM_BUG_ON_PAGE(!lruvec_holds_page_lru_lock(page, lruvec), page);
+
 	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
 	list_add(&page->lru, &lruvec->lists[lru]);
 }
@@ -93,6 +95,8 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page,
 {
 	enum lru_list lru = page_lru(page);
 
+	VM_BUG_ON_PAGE(!lruvec_holds_page_lru_lock(page, lruvec), page);
+
 	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
 	list_add_tail(&page->lru, &lruvec->lists[lru]);
 }
@@ -100,6 +104,8 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page,
 static __always_inline void del_page_from_lru_list(struct page *page,
 				struct lruvec *lruvec)
 {
+	VM_BUG_ON_PAGE(!lruvec_holds_page_lru_lock(page, lruvec), page);
+
 	list_del(&page->lru);
 	update_lru_size(lruvec, page_lru(page), page_zonenum(page),
 			-thp_nr_pages(page));
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4431007825ad..af0fc8110bdc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2063,7 +2063,6 @@ static unsigned int move_pages_to_lru(struct list_head *list)
 			continue;
 		}
 
-		VM_BUG_ON_PAGE(!lruvec_holds_page_lru_lock(page, lruvec), page);
 		add_page_to_lru_list(page, lruvec);
 		nr_pages = thp_nr_pages(page);
 		nr_moved += nr_pages;
-- 
2.11.0