linux-kernel - [PATCH 03/13] mm: move __ClearPageLRU() into page_off

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Date:   Thu, 17 Sep 2020 21:00:41 -0600
From:   Yu Zhao <yuzhao@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>
Cc:     Alex Shi <alex.shi@...ux.alibaba.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Chris Down <chris@...isdown.name>,
        Yafang Shao <laoar.shao@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Huang Ying <ying.huang@...el.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Minchan Kim <minchan@...nel.org>,
        Jaewon Kim <jaewon31.kim@...sung.com>, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Yu Zhao <yuzhao@...gle.com>
Subject: [PATCH 03/13] mm: move __ClearPageLRU() into page_off_lru()

Now we have a total of three places that free lru pages when their
references become zero (after we drop the reference from isolation).

Before this patch, they all do:
	__ClearPageLRU()
	page_off_lru()
	del_page_from_lru_list()

After this patch, they become:
	page_off_lru()
		__ClearPageLRU()
	del_page_from_lru_list()

This change should have no side effects.

Signed-off-by: Yu Zhao <yuzhao@...gle.com>
---
 include/linux/mm_inline.h | 1 +
 mm/swap.c                 | 2 --
 mm/vmscan.c               | 1 -
 3 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 8fc71e9d7bb0..be9418425e41 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -92,6 +92,7 @@ static __always_inline enum lru_list page_off_lru(struct page *page)
 {
 	enum lru_list lru;
 
+	__ClearPageLRU(page);
 	if (PageUnevictable(page)) {
 		__ClearPageUnevictable(page);
 		lru = LRU_UNEVICTABLE;
diff --git a/mm/swap.c b/mm/swap.c
index 40bf20a75278..8362083f00c9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -86,7 +86,6 @@ static void __page_cache_release(struct page *page)
 		spin_lock_irqsave(&pgdat->lru_lock, flags);
 		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 		VM_BUG_ON_PAGE(!PageLRU(page), page);
-		__ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
 	}
@@ -895,7 +894,6 @@ void release_pages(struct page **pages, int nr)
 
 			lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
-			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		}
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f257d2f61574..f9a186a96410 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1862,7 +1862,6 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		add_page_to_lru_list(page, lruvec, lru);
 
 		if (put_page_testzero(page)) {
-			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
 
 			if (unlikely(PageCompound(page))) {
-- 
2.28.0.681.g6f77f65b4e-goog