linux-kernel - [PATCH v5 4/7] mm: memcontrol: change ug->dummy

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Message-Id: <20210319163821.20704-5-songmuchun@bytedance.com>
Date:   Sat, 20 Mar 2021 00:38:17 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     guro@...com, hannes@...xchg.org, mhocko@...nel.org,
        akpm@...ux-foundation.org, shakeelb@...gle.com,
        vdavydov.dev@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        duanxiongchun@...edance.com, Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v5 4/7] mm: memcontrol: change ug->dummy_page only if memcg changed

Just like assignment to ug->memcg, we only need to update ug->dummy_page
if memcg changed. So move it to there. This is a very small optimization.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Reviewed-by: Shakeel Butt <shakeelb@...gle.com>
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9489c7fc1e04..8d28a5a2ee58 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6854,6 +6854,7 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
 			uncharge_gather_clear(ug);
 		}
 		ug->memcg = page_memcg(page);
+		ug->dummy_page = page;
 
 		/* pairs with css_put in uncharge_batch */
 		css_get(&ug->memcg->css);
@@ -6867,7 +6868,6 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
 	else
 		ug->pgpgout++;
 
-	ug->dummy_page = page;
 	page->memcg_data = 0;
 	css_put(&ug->memcg->css);
 }
-- 
2.11.0