linux-kernel - [PATCH v4 2/4] mm/migration: remove unneeded lock page and PageMovable check

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Message-ID: <20220530113016.16663-3-linmiaohe@huawei.com>
Date:   Mon, 30 May 2022 19:30:14 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <naoya.horiguchi@....com>
CC:     <peterx@...hat.com>, <apopple@...dia.com>, <ying.huang@...el.com>,
        <osalvador@...e.de>, <mike.kravetz@...cle.com>,
        <songmuchun@...edance.com>, <hch@....de>, <dhowells@...hat.com>,
        <cl@...ux.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH v4 2/4] mm/migration: remove unneeded lock page and PageMovable check

When non-lru movable page was freed from under us, __ClearPageMovable must
have been done.  So we can remove unneeded lock page and PageMovable check
here. Also free_pages_prepare() will clear PG_isolated for us, so we can
further remove ClearPageIsolated as suggested by David.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
---
 mm/migrate.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index e88ebb88fa6f..337336115e43 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1090,15 +1090,10 @@ static int unmap_and_move(new_page_t get_new_page,
 		return -ENOSYS;
 
 	if (page_count(page) == 1) {
-		/* page was freed from under us. So we are done. */
+		/* Page was freed from under us. So we are done. */
 		ClearPageActive(page);
 		ClearPageUnevictable(page);
-		if (unlikely(__PageMovable(page))) {
-			lock_page(page);
-			if (!PageMovable(page))
-				ClearPageIsolated(page);
-			unlock_page(page);
-		}
+		/* free_pages_prepare() will clear PG_isolated. */
 		goto out;
 	}
 
-- 
2.23.0