From: Michal Hocko <mhocko@suse.com>
To: Hui Su <sh_def@163.com>
Cc: hannes@cmpxchg.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/memcontrol: remove the unnecessary rcu_read_[un]lock
Date: Wed, 16 Dec 2020 08:35:05 +0100 [thread overview]
Message-ID: <20201216073505.GQ32193@dhcp22.suse.cz> (raw)
In-Reply-To: <20201216055213.GA63520@rlk>
On Wed 16-12-20 13:52:13, Hui Su wrote:
> the rcu_read_lock and rcu_read_unlock is unnecessary in:
> lock_page_lruvec()
> lock_page_lruvec_irq()
> lock_page_lruvec_irqsave()
Please add an explanation why it is unnecessary.
> Signed-off-by: Hui Su <sh_def@163.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
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2020-12-16 7:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 5:52 [PATCH] mm/memcontrol: remove the unnecessary rcu_read_[un]lock Hui Su
2020-12-16 7:35 ` Michal Hocko [this message]
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