Commit 87560179 authored by Yu Zhao's avatar Yu Zhao Committed by Linus Torvalds
Browse files

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: default avatarYu 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 46ae6b2c

include/linux/mm_inline.h

+10 −18
Original line number Diff line number Diff line
@@ -61,27 +61,19 @@ static inline enum lru_list page_lru_base_type(struct page *page) 
}



/**

 * page_off_lru - which LRU list was page on? clearing its lru flags.

 * @page: the page to test

 *

 * Returns the LRU list a page was on, as an index into the array of LRU

 * lists; and clears its Unevictable or Active flags, ready for freeing.

 * __clear_page_lru_flags - clear page lru flags before releasing a page

 * @page: the page that was on lru and now has a zero reference

 */

static __always_inline enum lru_list page_off_lru(struct page *page)

static __always_inline void __clear_page_lru_flags(struct page *page)

{

	enum lru_list lru;

	__ClearPageLRU(page);



	/* this shouldn't happen, so leave the flags to bad_page() */

	if (PageActive(page) && PageUnevictable(page))

		return;



	if (PageUnevictable(page)) {

		__ClearPageUnevictable(page);

		lru = LRU_UNEVICTABLE;

	} else {

		lru = page_lru_base_type(page);

		if (PageActive(page)) {

	__ClearPageActive(page);

			lru += LRU_ACTIVE;

		}

	}

	return lru;

	__ClearPageUnevictable(page);

}



/**

mm/swap.c

+2 −4
Original line number Diff line number Diff line
@@ -84,9 +84,8 @@ static void __page_cache_release(struct page *page) 


		lruvec = lock_page_lruvec_irqsave(page, &flags);

		VM_BUG_ON_PAGE(!PageLRU(page), page);

		__ClearPageLRU(page);

		del_page_from_lru_list(page, lruvec);

		page_off_lru(page);

		__clear_page_lru_flags(page);

		unlock_page_lruvec_irqrestore(lruvec, flags);

	}

	__ClearPageWaiters(page);
@@ -911,9 +910,8 @@ void release_pages(struct page **pages, int nr) 
				lock_batch = 0;



			VM_BUG_ON_PAGE(!PageLRU(page), page);

			__ClearPageLRU(page);

			del_page_from_lru_list(page, lruvec);

			page_off_lru(page);

			__clear_page_lru_flags(page);

		}



		__ClearPageWaiters(page);

mm/vmscan.c

+1 −2
Original line number Diff line number Diff line
@@ -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);