From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E728AC4361B for ; Wed, 16 Dec 2020 07:35:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 459172333E for ; Wed, 16 Dec 2020 07:35:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 459172333E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A5F4B6B0068; Wed, 16 Dec 2020 02:35:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A0E726B006C; Wed, 16 Dec 2020 02:35:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8D77C6B006E; Wed, 16 Dec 2020 02:35:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0223.hostedemail.com [216.40.44.223]) by kanga.kvack.org (Postfix) with ESMTP id 743A26B0068 for ; Wed, 16 Dec 2020 02:35:08 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 364681EE6 for ; Wed, 16 Dec 2020 07:35:08 +0000 (UTC) X-FDA: 77598334296.17.rake49_07151f12742a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 11304180D018B for ; Wed, 16 Dec 2020 07:35:08 +0000 (UTC) X-HE-Tag: rake49_07151f12742a X-Filterd-Recvd-Size: 3072 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Wed, 16 Dec 2020 07:35:07 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1608104106; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=i6r+QjOa5VJLHtoN/qARO5iLDlJY4rWyvupxvYJjs5Y=; b=rLc88kV0JCaUwwc1S8gEYimH+HZ87tj2RbeJO9Yr8OLBWHAWZ5UOAoP+6zSwYAqpdsdkpj H1YRTgtbGNnv8Qb7momflhyYN3BVTWpgZXHZWSSsBkrexT6cedC+PPvP7mQ5+7EkwhqziU ZayQBENXMHFX+7lhBelNshlmACiJrms= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 22244ACF1; Wed, 16 Dec 2020 07:35:06 +0000 (UTC) Date: Wed, 16 Dec 2020 08:35:05 +0100 From: Michal Hocko To: Hui Su 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 Message-ID: <20201216073505.GQ32193@dhcp22.suse.cz> References: <20201216055213.GA63520@rlk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201216055213.GA63520@rlk> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 > --- > 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