[PATCH v2 1/2] mm: use add_page_to_lru_list()/page_lru()/page_off_lru()

[Yu Zhao]

This is a trivial but worth having clean-up patch. There should be
no side effects except page->lru is temporarily poisoned after it's
deleted but before it's added to the new list in move_pages_to_lru()
(which is not a problem).

[ I was under false impression that page_off_lru() clears PG_lru;
  Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> pointed that out. So in v2,
  we keep __ClearPageLRU(). ]

Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
 mm/swap.c   |  4 +---
 mm/vmscan.c | 13 ++++---------
 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 40bf20a75278..2735ecf0f566 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -597,11 +597,9 @@ static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
 {
 	if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
 	    !PageSwapCache(page) && !PageUnevictable(page)) {
-		bool active = PageActive(page);
 		int nr_pages = thp_nr_pages(page);
 
-		del_page_from_lru_list(page, lruvec,
-				       LRU_INACTIVE_ANON + active);
+		del_page_from_lru_list(page, lruvec, page_lru(page));
 		ClearPageActive(page);
 		ClearPageReferenced(page);
 		/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 99e1796eb833..1b871c3987e7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1845,13 +1845,12 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 	int nr_pages, nr_moved = 0;
 	LIST_HEAD(pages_to_free);
 	struct page *page;
-	enum lru_list lru;
 
 	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);
@@ -1860,16 +1859,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
 		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, page_lru(page));
 
 		if (put_page_testzero(page)) {
 			__ClearPageLRU(page);
-			__ClearPageActive(page);
-			del_page_from_lru_list(page, lruvec, lru);
+			del_page_from_lru_list(page, lruvec, page_off_lru(page));
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&pgdat->lru_lock);
@@ -1878,6 +1872,7 @@ 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);
-- 
2.28.0.402.g5ffc5be6b7-goog