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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 B3CB1C433DF for ; Mon, 10 Aug 2020 13:10:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C864206C3 for ; Mon, 10 Aug 2020 13:10:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726797AbgHJNKz (ORCPT ); Mon, 10 Aug 2020 09:10:55 -0400 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:42891 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726330AbgHJNKw (ORCPT ); Mon, 10 Aug 2020 09:10:52 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R871e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01358;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=19;SR=0;TI=SMTPD_---0U5Mm29u_1597065044; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U5Mm29u_1597065044) by smtp.aliyun-inc.com(127.0.0.1); Mon, 10 Aug 2020 21:10:46 +0800 Subject: Re: [PATCH v17 14/21] mm/compaction: do page isolation first in compaction To: Alexander Duyck Cc: Andrew Morton , Mel Gorman , Tejun Heo , Hugh Dickins , Konstantin Khlebnikov , Daniel Jordan , Yang Shi , Matthew Wilcox , Johannes Weiner , kbuild test robot , linux-mm , LKML , cgroups@vger.kernel.org, Shakeel Butt , Joonsoo Kim , Wei Yang , "Kirill A. Shutemov" , Rong Chen References: <1595681998-19193-1-git-send-email-alex.shi@linux.alibaba.com> <1595681998-19193-15-git-send-email-alex.shi@linux.alibaba.com> <241ca157-104f-4f0d-7d5b-de394443788d@linux.alibaba.com> From: Alex Shi Message-ID: <8dbd004e-8eba-f1ec-a5eb-5dc551978936@linux.alibaba.com> Date: Mon, 10 Aug 2020 21:10:17 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2020/8/7 下午10:51, Alexander Duyck 写道: > I wonder if this entire section shouldn't be restructured. This is the > only spot I can see where we are resetting the LRU flag instead of > pulling the page from the LRU list with the lock held. Looking over > the code it seems like something like that should be possible. I am > not sure the LRU lock is really protecting us in either the > PageCompound check nor the skip bits. It seems like holding a > reference on the page should prevent it from switching between > compound or not, and the skip bits are per pageblock with the LRU bits > being per node/memcg which I would think implies that we could have > multiple LRU locks that could apply to a single skip bit. Hi Alexander, I don't find problem yet on compound or skip bit usage. Would you clarify the issue do you concerned? Thanks! From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Shi Subject: Re: [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Date: Mon, 10 Aug 2020 21:10:17 +0800 Message-ID: <8dbd004e-8eba-f1ec-a5eb-5dc551978936@linux.alibaba.com> References: <1595681998-19193-1-git-send-email-alex.shi@linux.alibaba.com> <1595681998-19193-15-git-send-email-alex.shi@linux.alibaba.com> <241ca157-104f-4f0d-7d5b-de394443788d@linux.alibaba.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="utf-8" To: Alexander Duyck Cc: Andrew Morton , Mel Gorman , Tejun Heo , Hugh Dickins , Konstantin Khlebnikov , Daniel Jordan , Yang Shi , Matthew Wilcox , Johannes Weiner , kbuild test robot , linux-mm , LKML , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shakeel Butt , Joonsoo Kim , Wei Yang , "Kirill A. Shutemov" , Rong Chen 在 2020/8/7 下午10:51, Alexander Duyck 写道: > I wonder if this entire section shouldn't be restructured. This is the > only spot I can see where we are resetting the LRU flag instead of > pulling the page from the LRU list with the lock held. Looking over > the code it seems like something like that should be possible. I am > not sure the LRU lock is really protecting us in either the > PageCompound check nor the skip bits. It seems like holding a > reference on the page should prevent it from switching between > compound or not, and the skip bits are per pageblock with the LRU bits > being per node/memcg which I would think implies that we could have > multiple LRU locks that could apply to a single skip bit. Hi Alexander, I don't find problem yet on compound or skip bit usage. Would you clarify the issue do you concerned? Thanks!