[PATCH 01/13] mm: use add_page_to_lru_list()

[Yu Zhao <yuzhao@xxxxxxxxxx>]

This patch replaces the only open-coded lru list addition with
add_page_to_lru_list().

Before this patch, we have:
	update_lru_size()
	list_move()

After this patch, we have:
	list_del()
	add_page_to_lru_list()
		update_lru_size()
		list_add()

The only side effect is that page->lru is temporarily poisoned
after a page is deleted from its old list, which shouldn't be a
problem.

Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
 mm/vmscan.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9727dd8e2581..503fc5e1fe32 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1850,8 +1850,8 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 	while (!list_empty(list)) {
 		page = lru_to_page(list);
 		VM_BUG_ON_PAGE(PageLRU(page), page);
+		list_del(&page->lru);
 		if (unlikely(!page_evictable(page))) {
-			list_del(&page->lru);
 			spin_unlock_irq(&pgdat->lru_lock);
 			putback_lru_page(page);
 			spin_lock_irq(&pgdat->lru_lock);
@@ -1862,9 +1862,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		SetPageLRU(page);
 		lru = page_lru(page);
 
-		nr_pages = thp_nr_pages(page);
-		update_lru_size(lruvec, lru, page_zonenum(page), nr_pages);
-		list_move(&page->lru, &lruvec->lists[lru]);
+		add_page_to_lru_list(page, lruvec, lru);
 
 		if (put_page_testzero(page)) {
 			__ClearPageLRU(page);
@@ -1878,6 +1876,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 			} else
 				list_add(&page->lru, &pages_to_free);
 		} else {
+			nr_pages = thp_nr_pages(page);
 			nr_moved += nr_pages;
 			if (PageActive(page))
 				workingset_age_nonresident(lruvec, nr_pages);
-- 
2.28.0.681.g6f77f65b4e-goog