linux-kernel - [PATCH] mm/memcontrol: remove the unnecessary rcu_read

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Date:   Wed, 16 Dec 2020 13:52:13 +0800
From:   Hui Su <sh_def@....com>
To:     hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        akpm@...ux-foundation.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     sh_def@....com
Subject: [PATCH] mm/memcontrol: remove the unnecessary rcu_read_[un]lock

the rcu_read_lock and rcu_read_unlock is unnecessary in:
	lock_page_lruvec()
	lock_page_lruvec_irq()
	lock_page_lruvec_irqsave()

Signed-off-by: Hui Su <sh_def@....com>
---
 mm/memcontrol.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e3c7ca7dc174..a19f820e8a3f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1396,10 +1396,8 @@ struct lruvec *lock_page_lruvec(struct page *page)
 	struct lruvec *lruvec;
 	struct pglist_data *pgdat = page_pgdat(page);
 
-	rcu_read_lock();
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 	spin_lock(&lruvec->lru_lock);
-	rcu_read_unlock();
 
 	lruvec_memcg_debug(lruvec, page);
 
@@ -1411,10 +1409,8 @@ struct lruvec *lock_page_lruvec_irq(struct page *page)
 	struct lruvec *lruvec;
 	struct pglist_data *pgdat = page_pgdat(page);
 
-	rcu_read_lock();
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 	spin_lock_irq(&lruvec->lru_lock);
-	rcu_read_unlock();
 
 	lruvec_memcg_debug(lruvec, page);
 
@@ -1426,10 +1422,8 @@ struct lruvec *lock_page_lruvec_irqsave(struct page *page, unsigned long *flags)
 	struct lruvec *lruvec;
 	struct pglist_data *pgdat = page_pgdat(page);
 
-	rcu_read_lock();
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 	spin_lock_irqsave(&lruvec->lru_lock, *flags);
-	rcu_read_unlock();
 
 	lruvec_memcg_debug(lruvec, page);
 
-- 
2.29.2