mm: add __clear_page_lru_flags() to replace page_off_lru()

Similar to page_off_lru(), the new function does non-atomic clearing
of PageLRU() in addition to PageActive() and PageUnevictable(), on a
page that has no references left.

If PageActive() and PageUnevictable() are both set, refuse to clear
either and leave them to bad_page(). This is a behavior change that
is meant to help debug.

Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7c65d47e6612..452dd3818aa3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1849,8 +1849,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		SetPageLRU(page);
 
 		if (unlikely(put_page_testzero(page))) {
-			__ClearPageLRU(page);
-			__ClearPageActive(page);
+			__clear_page_lru_flags(page);
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&lruvec->lru_lock);