linux-kernel - [PATCH 2/4] ksm: use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from

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Date:   Tue, 30 Mar 2021 10:02:26 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <hughd@...gle.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 2/4] ksm: use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()

It's unnecessary to lock the page when get ksm page if we're going to
remove the rmap item as page migration is irrelevant in this case. Use
GET_KSM_PAGE_NOLOCK instead to save some page lock cycles.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/ksm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 359afb3023b4..5650a282da3e 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -778,12 +778,11 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
 		struct page *page;
 
 		stable_node = rmap_item->head;
-		page = get_ksm_page(stable_node, GET_KSM_PAGE_LOCK);
+		page = get_ksm_page(stable_node, GET_KSM_PAGE_NOLOCK);
 		if (!page)
 			goto out;
 
 		hlist_del(&rmap_item->hlist);
-		unlock_page(page);
 		put_page(page);
 
 		if (!hlist_empty(&stable_node->hlist))
-- 
2.19.1