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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E766AC32792 for ; Tue, 23 Aug 2022 13:12:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7D1E66B0073; Tue, 23 Aug 2022 09:12:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 780D26B0074; Tue, 23 Aug 2022 09:12:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 648848D0001; Tue, 23 Aug 2022 09:12:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 536A96B0073 for ; Tue, 23 Aug 2022 09:12:09 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 20EAB1408F5 for ; Tue, 23 Aug 2022 13:12:09 +0000 (UTC) X-FDA: 79830895578.21.7A48C78 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf14.hostedemail.com (Postfix) with ESMTP id 38E84100017 for ; Tue, 23 Aug 2022 13:12:08 +0000 (UTC) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MBqJz46S7zXdjc; Tue, 23 Aug 2022 21:07:47 +0800 (CST) Received: from dggpemm100009.china.huawei.com (7.185.36.113) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 23 Aug 2022 21:12:04 +0800 Received: from [10.174.179.24] (10.174.179.24) by dggpemm100009.china.huawei.com (7.185.36.113) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 23 Aug 2022 21:12:03 +0800 Subject: Re: [PATCH -next v2] mm, proc: collect percpu free pages into the free pages To: Andrew Morton , Greg Kroah-Hartman , huang ying , Aaron Lu , Dave Hansen , "Michal Hocko" , Jesper Dangaard Brouer , Vlastimil Babka , Kemi Wang , "Kefeng Wang" , , References: <20220822023311.909316-1-liushixin2@huawei.com> <20220822033354.952849-1-liushixin2@huawei.com> <20220822141207.24ff7252913a62f80ea55e90@linux-foundation.org> <20220822141309.3b7382db0367b63b6cd72c14@linux-foundation.org> From: Liu Shixin Message-ID: <4687e93d-9245-300e-6193-d5428a76c9b8@huawei.com> Date: Tue, 23 Aug 2022 21:12:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20220822141309.3b7382db0367b63b6cd72c14@linux-foundation.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.24] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=liushixin2@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661260328; a=rsa-sha256; cv=none; b=mNrHHijKlWlIL8XsttU9IUOzrQNMNsc5krAMSz6j/+q36U1AyeDzTR9URJef9646ELLUvK 9PJbmFFIx2DPMoa2MzgeKiB1yfkXbBJ47lkSS7TpnD4TCHhaWK6tDaUprnPZ8TD5lA/ZM8 hS2zxtM5mFWsu9nQKtOoQ37p6gv5IpU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661260328; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GS25f8WAZLGvsN/aahA+hQ6Tte17TYAYy/14p2/Bd/g=; b=LhLWYAIBYihshOSnWTzumVx3m4bkliA5HND8auyGZlzQo90Sd5oJuOyREDCdmE/zJD+cEB tuUnwrUUvM0g1QiZkJ6mbMcx7SbTiPMNHkSB4WVGzjD8jB3g++s4ISRxmQ3xhpYqve8cv+ 2CHP/Bo+fM9JBHrIhrJTI0aI2jh7aYM= Authentication-Results: imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=liushixin2@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 38E84100017 X-Stat-Signature: xku9ghkd7ebm8xfuwkcypdg9x9frneyn X-HE-Tag: 1661260328-804417 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 2022/8/23 5:13, Andrew Morton wrote: > On Mon, 22 Aug 2022 14:12:07 -0700 Andrew Morton wrote: > >> Prevention of races against zone/node hotplug? > I meant "cpu/node", of course. > . Thanks for your advice, but I didn't quite understand what you meant. Do you mean that I should use cpus_read_lock() to protect cpu hotplug just like this? + cpus_read_lock(); for_each_online_cpu(cpu) sum += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count; + cpus_read_unlock(); I see there is some areas were not protected by the cpus_{read/write}_lock, so I was confused as to whether I should add it. I want to replace for_each_zone with for_each_populated_zone, what else should I do to protect node hotplug. Thanks.