linux-kernel - [PATCH 02/13] mm: use page_off

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Message-Id: <20200918030051.650890-3-yuzhao@google.com>
Date:   Thu, 17 Sep 2020 21:00:40 -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 02/13] mm: use page_off_lru()

This patch replaces the only open-coded __ClearPageActive() with
page_off_lru(). There is no open-coded __ClearPageUnevictable()s.

Before this patch, we have:
	__ClearPageActive()
	add_page_to_lru_list()

After this patch, we have:
	page_off_lru()
		if PageUnevictable()
			__ClearPageUnevictable()
		else if PageActive()
			__ClearPageActive()
	add_page_to_lru_list()

Checking PageUnevictable() shouldn't be a problem because these two
flags are mutually exclusive. Leaking either will trigger bad_page().

Signed-off-by: Yu Zhao <yuzhao@...gle.com>
---
 mm/vmscan.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 503fc5e1fe32..f257d2f61574 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1845,7 +1845,6 @@ 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);
@@ -1860,14 +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);
-
 		add_page_to_lru_list(page, lruvec, lru);
 
 		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);
-- 
2.28.0.681.g6f77f65b4e-goog