From: Alex Shi <alex.shi@linux.alibaba.com>
To: hughd@google.com
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/3] mm/memcg: remove rcu locking for lock_page_lruvec function series
Date: Tue, 22 Dec 2020 13:20:52 +0800 [thread overview]
Message-ID: <1608614453-10739-2-git-send-email-alex.shi@linux.alibaba.com> (raw)
In-Reply-To: <1608614453-10739-1-git-send-email-alex.shi@linux.alibaba.com>
lock_page_lruvec() and its variants used rcu_read_lock() with the
intention of safeguarding against the mem_cgroup being destroyed
concurrently; but so long as they are called under the specified
conditions (as they are), there is no way for the page's mem_cgroup
to be destroyed. Delete the unnecessary rcu_read_lock() and _unlock().
Hugh Dickin's polished the commit log, Thanks a lot!
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/memcontrol.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8d400efc81b9..0af13c4fe4b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1356,10 +1356,8 @@ 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);
@@ -1371,10 +1369,8 @@ 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);
@@ -1386,10 +1382,8 @@ 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.GIT
next prev parent reply other threads:[~2020-12-22 5:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-22 5:20 [PATCH v2 1/3] mm/memcg: revise the using condition of lock_page_lruvec function series Alex Shi
2020-12-22 5:20 ` Alex Shi [this message]
2020-12-22 8:00 ` [PATCH v2 2/3] mm/memcg: remove rcu locking for " Alex Shi
2020-12-22 5:20 ` [PATCH v2 3/3] mm/compaction: remove rcu_read_lock during page compaction Alex Shi
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