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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E31EFC33CA2 for ; Fri, 10 Jan 2020 08:49:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B650A20721 for ; Fri, 10 Jan 2020 08:49:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="Fyx7qH8P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727186AbgAJItO (ORCPT ); Fri, 10 Jan 2020 03:49:14 -0500 Received: from forwardcorp1o.mail.yandex.net ([95.108.205.193]:60930 "EHLO forwardcorp1o.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727152AbgAJItN (ORCPT ); Fri, 10 Jan 2020 03:49:13 -0500 Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id 22BFB2E037C; Fri, 10 Jan 2020 11:49:10 +0300 (MSK) Received: from sas1-9998cec34266.qloud-c.yandex.net (sas1-9998cec34266.qloud-c.yandex.net [2a02:6b8:c14:3a0e:0:640:9998:cec3]) by mxbackcorp1g.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id mOJVkqvLMH-n8dmwGcB; Fri, 10 Jan 2020 11:49:10 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1578646150; bh=qNR3NRByyHlpXQ4p8X/hlo3hrAKhN7Qz3lDeB34a2SE=; h=In-Reply-To:Message-ID:From:Date:References:To:Subject:Cc; b=Fyx7qH8P/x1bFQnJzbtV/n/oKwipgrSOqyHGMcwJ8hs8laBFTQJQCrEKnzAvegvLj 7DmxhCtvD5dSvHww2xkvK8WCrFCn8nLyOIVAc8fp2ddXKmixviBV9JqSrBpVvJZ0O9 vop6n5umIXK5jlres1B9ZHfNtHWTnSNRpRfoE+fw= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:8448:fbcc:1dac:c863]) by sas1-9998cec34266.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id yoMDYH1TTx-n8V0jXth; Fri, 10 Jan 2020 11:49:08 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) Subject: Re: [PATCH v7 02/10] mm/memcg: fold lru_lock in lock_page_lru To: Alex Shi , 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, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, willy@infradead.org, shakeelb@google.com, hannes@cmpxchg.org Cc: Michal Hocko , Vladimir Davydov References: <1577264666-246071-1-git-send-email-alex.shi@linux.alibaba.com> <1577264666-246071-3-git-send-email-alex.shi@linux.alibaba.com> From: Konstantin Khlebnikov Message-ID: <36d7e390-a3d1-908c-d181-4a9e9c8d3d98@yandex-team.ru> Date: Fri, 10 Jan 2020 11:49:08 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <1577264666-246071-3-git-send-email-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/12/2019 12.04, Alex Shi wrote: > From the commit_charge's explanations and mem_cgroup_commit_charge > comments, as well as call path when lrucare is ture, The lru_lock is > just to guard the task migration(which would be lead to move_account) > So it isn't needed when !PageLRU, and better be fold into PageLRU to > reduce lock contentions. > > Signed-off-by: Alex Shi > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Matthew Wilcox > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgroups@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index c5b5f74cfd4d..0ad10caabc3d 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2572,12 +2572,11 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) > > static void lock_page_lru(struct page *page, int *isolated) > { > - pg_data_t *pgdat = page_pgdat(page); > - > - spin_lock_irq(&pgdat->lru_lock); > if (PageLRU(page)) { > + pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > + spin_lock_irq(&pgdat->lru_lock); That's wrong. Here PageLRU must be checked again under lru_lock. Also I don't like these functions: - called lock/unlock but actually also isolates - used just once - pgdat evaluated twice > lruvec = mem_cgroup_page_lruvec(page, pgdat); > ClearPageLRU(page); > del_page_from_lru_list(page, lruvec, page_lru(page)); > @@ -2588,17 +2587,17 @@ static void lock_page_lru(struct page *page, int *isolated) > > static void unlock_page_lru(struct page *page, int isolated) > { > - pg_data_t *pgdat = page_pgdat(page); > > if (isolated) { > + pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > lruvec = mem_cgroup_page_lruvec(page, pgdat); > VM_BUG_ON_PAGE(PageLRU(page), page); > SetPageLRU(page); > add_page_to_lru_list(page, lruvec, page_lru(page)); > + spin_unlock_irq(&pgdat->lru_lock); > } > - spin_unlock_irq(&pgdat->lru_lock); > } > > static void commit_charge(struct page *page, struct mem_cgroup *memcg, > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Khlebnikov Subject: Re: [PATCH v7 02/10] mm/memcg: fold lru_lock in lock_page_lru Date: Fri, 10 Jan 2020 11:49:08 +0300 Message-ID: <36d7e390-a3d1-908c-d181-4a9e9c8d3d98@yandex-team.ru> References: <1577264666-246071-1-git-send-email-alex.shi@linux.alibaba.com> <1577264666-246071-3-git-send-email-alex.shi@linux.alibaba.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1578646150; bh=qNR3NRByyHlpXQ4p8X/hlo3hrAKhN7Qz3lDeB34a2SE=; h=In-Reply-To:Message-ID:From:Date:References:To:Subject:Cc; b=Fyx7qH8P/x1bFQnJzbtV/n/oKwipgrSOqyHGMcwJ8hs8laBFTQJQCrEKnzAvegvLj 7DmxhCtvD5dSvHww2xkvK8WCrFCn8nLyOIVAc8fp2ddXKmixviBV9JqSrBpVvJZ0O9 vop6n5umIXK5jlres1B9ZHfNtHWTnSNRpRfoE+fw= In-Reply-To: <1577264666-246071-3-git-send-email-alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org> Content-Language: en-CA Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Alex Shi , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, daniel.m.jordan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org, willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org Cc: Michal Hocko , Vladimir Davydov On 25/12/2019 12.04, Alex Shi wrote: > From the commit_charge's explanations and mem_cgroup_commit_charge > comments, as well as call path when lrucare is ture, The lru_lock is > just to guard the task migration(which would be lead to move_account) > So it isn't needed when !PageLRU, and better be fold into PageLRU to > reduce lock contentions. > > Signed-off-by: Alex Shi > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Matthew Wilcox > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org > Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > --- > mm/memcontrol.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index c5b5f74cfd4d..0ad10caabc3d 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2572,12 +2572,11 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) > > static void lock_page_lru(struct page *page, int *isolated) > { > - pg_data_t *pgdat = page_pgdat(page); > - > - spin_lock_irq(&pgdat->lru_lock); > if (PageLRU(page)) { > + pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > + spin_lock_irq(&pgdat->lru_lock); That's wrong. Here PageLRU must be checked again under lru_lock. Also I don't like these functions: - called lock/unlock but actually also isolates - used just once - pgdat evaluated twice > lruvec = mem_cgroup_page_lruvec(page, pgdat); > ClearPageLRU(page); > del_page_from_lru_list(page, lruvec, page_lru(page)); > @@ -2588,17 +2587,17 @@ static void lock_page_lru(struct page *page, int *isolated) > > static void unlock_page_lru(struct page *page, int isolated) > { > - pg_data_t *pgdat = page_pgdat(page); > > if (isolated) { > + pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > lruvec = mem_cgroup_page_lruvec(page, pgdat); > VM_BUG_ON_PAGE(PageLRU(page), page); > SetPageLRU(page); > add_page_to_lru_list(page, lruvec, page_lru(page)); > + spin_unlock_irq(&pgdat->lru_lock); > } > - spin_unlock_irq(&pgdat->lru_lock); > } > > static void commit_charge(struct page *page, struct mem_cgroup *memcg, >