linux-kernel - [PATCH 5/5] mm/vmscan: fix misleading comment in isolate_lru

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Message-ID: <20210710100329.49174-6-linmiaohe@huawei.com>
Date:   Sat, 10 Jul 2021 18:03:29 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <hannes@...xchg.org>, <vbabka@...e.cz>, <mhocko@...e.com>,
        <axboe@...nel.dk>, <iamjoonsoo.kim@....com>, <alexs@...nel.org>,
        <apopple@...dia.com>, <willy@...radead.org>, <minchan@...nel.org>,
        <david@...hat.com>, <shli@...com>, <hillf.zj@...baba-inc.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 5/5] mm/vmscan: fix misleading comment in isolate_lru_pages()

We couldn't know whether the page is being freed elsewhere until we failed
to increase the page count.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a74760c48bd8..6e26b3c93242 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1891,7 +1891,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		 */
 		scan += nr_pages;
 		if (!__isolate_lru_page_prepare(page, mode)) {
-			/* It is being freed elsewhere */
 			list_move(&page->lru, src);
 			continue;
 		}
@@ -1901,6 +1900,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		 * page release code relies on it.
 		 */
 		if (unlikely(!get_page_unless_zero(page))) {
+			/* It is being freed elsewhere. */
 			list_move(&page->lru, src);
 			continue;
 		}
-- 
2.23.0