[RFC PATCH 15/15] 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 <songmuc...@bytedance.com>
---
 include/linux/mm_inline.h | 6 ++++++
 mm/vmscan.c               | 3 ++-
 2 files changed, 8 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 fea6b43bc1f9..0a4a3072d092 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1656,6 +1656,8 @@ static unsigned long isolate_lru_pages(unsigned long 
nr_to_scan,
                page = lru_to_page(src);
                prefetchw_prev_lru_page(page, src, flags);
 
+               VM_BUG_ON_PAGE(!lruvec_holds_page_lru_lock(page, lruvec), page);
+
                nr_pages = compound_nr(page);
                total_scan += nr_pages;
 
@@ -1866,7 +1868,6 @@ static unsigned noinline_for_stack 
move_pages_to_lru(struct lruvec *lruvec,
                 * All pages were isolated from the same lruvec (and isolation
                 * inhibits memcg migration).
                 */
-               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