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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 60EBFC43331 for ; Tue, 12 Nov 2019 14:38:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 221CF2067B for ; Tue, 12 Nov 2019 14:38:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="LvBaEtA8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 221CF2067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AA2C76B0003; Tue, 12 Nov 2019 09:38:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A2C6F6B0007; Tue, 12 Nov 2019 09:38:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 91B4C6B0008; Tue, 12 Nov 2019 09:38:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0187.hostedemail.com [216.40.44.187]) by kanga.kvack.org (Postfix) with ESMTP id 7915A6B0003 for ; Tue, 12 Nov 2019 09:38:52 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 26A0D181AEF15 for ; Tue, 12 Nov 2019 14:38:52 +0000 (UTC) X-FDA: 76147882104.30.fang74_4d5e8d505b428 X-HE-Tag: fang74_4d5e8d505b428 X-Filterd-Recvd-Size: 5078 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 12 Nov 2019 14:38:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=TJr4CpD0eqtU9Muj0R5+F4ADnc1Bcgs5f/lnGegH6fY=; b=LvBaEtA8ObLDwTs+cO8119grZ vKdfNH/5J48mGoppknvgLSkL6fiB2cW1fxkYmA8fJop7axPcEuUVeurcjtB3xJBK5pnbidyISTaoA IM6x5zVCPcMTgxuuq26TOcMRCirfdUTitnIqlGwwh2Pp9SMmNs9XGqbcRhZMRjwWXt7nYjzjDgEfI jI1b9beMvWQzUtQnEfn2Mav98rJu5d/z5KMJM491QL0M+i70wAXb0Ju+2L8GGaOdiqIzhivqqa/B1 gG1KpJrOl6vIP1yv+OsIEwPZ7MgEIGZjzJR0PkJncm7BuntqbVatZqRD7MKhytieHYXb2VGyOFcT9 XAXpW5F4w==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUXJd-0003x1-1C; Tue, 12 Nov 2019 14:38:45 +0000 Date: Tue, 12 Nov 2019 06:38:44 -0800 From: Matthew Wilcox To: Alex Shi Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, Johannes Weiner , Roman Gushchin , Shakeel Butt , Chris Down , Thomas Gleixner Subject: Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression Message-ID: <20191112143844.GB7934@bombadil.infradead.org> References: <1573567588-47048-1-git-send-email-alex.shi@linux.alibaba.com> <1573567588-47048-7-git-send-email-alex.shi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1573567588-47048-7-git-send-email-alex.shi@linux.alibaba.com> User-Agent: Mutt/1.12.1 (2019-06-15) 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 Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote: > Intel 0day report there are performance regression on this patchset. > The detailed info points to rcu_read_lock + PROVE_LOCKING which causes > queued_spin_lock_slowpath waiting too long time to get lock. > Remove rcu_read_lock is safe here since we had a spinlock hold. Argh. You have not sent these patches in a properly reviewable form! I wasted all that time reviewing the earlier patch in this series only to find out that you changed it here. FIX THE PATCH, don't send a fix-patch on top of it! > Reported-by: kbuild test robot > Signed-off-by: Alex Shi > Cc: Andrew Morton > Cc: Johannes Weiner > Cc: Roman Gushchin > Cc: Shakeel Butt > Cc: Chris Down > Cc: Tejun Heo > Cc: Thomas Gleixner > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > include/linux/memcontrol.h | 29 ++++++++++++----------------- > 1 file changed, 12 insertions(+), 17 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 2421b720d272..f869897a68f0 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1307,20 +1307,18 @@ static inline struct lruvec *relock_page_lruvec_irq(struct page *page, > struct pglist_data *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > - rcu_read_lock(); > + if (!locked_lruvec) > + goto lock; > + > lruvec = mem_cgroup_page_lruvec(page, pgdat); > > - if (locked_lruvec == lruvec) { > - rcu_read_unlock(); > + if (locked_lruvec == lruvec) > return lruvec; > - } > - rcu_read_unlock(); > > - if (locked_lruvec) > - spin_unlock_irq(&locked_lruvec->lru_lock); > + spin_unlock_irq(&locked_lruvec->lru_lock); > > +lock: > lruvec = lock_page_lruvec_irq(page, pgdat); > - > return lruvec; > } > > @@ -1331,21 +1329,18 @@ static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page, > struct pglist_data *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > - rcu_read_lock(); > + if (!locked_lruvec) > + goto lock; > + > lruvec = mem_cgroup_page_lruvec(page, pgdat); > > - if (locked_lruvec == lruvec) { > - rcu_read_unlock(); > + if (locked_lruvec == lruvec) > return lruvec; > - } > - rcu_read_unlock(); > > - if (locked_lruvec) > - spin_unlock_irqrestore(&locked_lruvec->lru_lock, > - locked_lruvec->flags); > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, locked_lruvec->flags); > > +lock: > lruvec = lock_page_lruvec_irqsave(page, pgdat); > - > return lruvec; > } > > -- > 1.8.3.1 > >