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=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 291B5C432BE for ; Fri, 30 Jul 2021 02:46:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8FA8E61019 for ; Fri, 30 Jul 2021 02:46:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8FA8E61019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 2B8F18D0001; Thu, 29 Jul 2021 22:46:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 268FE6B005D; Thu, 29 Jul 2021 22:46:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 157948D0001; Thu, 29 Jul 2021 22:46:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0042.hostedemail.com [216.40.44.42]) by kanga.kvack.org (Postfix) with ESMTP id EC4816B0036 for ; Thu, 29 Jul 2021 22:46:29 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 90D988249980 for ; Fri, 30 Jul 2021 02:46:29 +0000 (UTC) X-FDA: 78417715698.15.60E4B8A Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf17.hostedemail.com (Postfix) with ESMTP id B68C2F003237 for ; Fri, 30 Jul 2021 02:46:28 +0000 (UTC) Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4GbWr36KL3z80M9; Fri, 30 Jul 2021 10:41:39 +0800 (CST) Received: from [10.174.178.209] (10.174.178.209) by dggeme703-chm.china.huawei.com (10.1.199.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 30 Jul 2021 10:46:24 +0800 Subject: Re: [External] Re: [PATCH 5/5] mm, memcg: always call __mod_node_page_state() with preempt disabled To: Muchun Song CC: Shakeel Butt , Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Roman Gushchin , Matthew Wilcox , Alex Shi , Wei Yang , Linux MM , LKML , Cgroups References: <20210729125755.16871-1-linmiaohe@huawei.com> <20210729125755.16871-6-linmiaohe@huawei.com> <29c4bb2a-ceaf-6c8b-c222-38b30460780f@huawei.com> From: Miaohe Lin Message-ID: <0077ebd3-abef-5763-8f50-7a937734c54b@huawei.com> Date: Fri, 30 Jul 2021 10:46:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.209] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected Authentication-Results: imf17.hostedemail.com; dkim=none; spf=pass (imf17.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=none) header.from=huawei.com X-Rspamd-Server: rspam02 X-Stat-Signature: argdo8h84bt4brfiocjmna4ndyj8dqoc X-Rspamd-Queue-Id: B68C2F003237 X-HE-Tag: 1627613188-773675 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 2021/7/30 10:33, Muchun Song wrote: > On Fri, Jul 30, 2021 at 9:52 AM Miaohe Lin wrote: >> >> On 2021/7/29 22:39, Shakeel Butt wrote: >>> On Thu, Jul 29, 2021 at 5:58 AM Miaohe Lin wrote: >>>> >>>> We should always ensure __mod_node_page_state() is called with preempt >>>> disabled or percpu ops may manipulate the wrong cpu when preempt happened. >>>> >>>> Fixes: b4e0b68fbd9d ("mm: memcontrol: use obj_cgroup APIs to charge kmem pages") >>>> Signed-off-by: Miaohe Lin >>>> --- >>>> mm/memcontrol.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index 70a32174e7c4..616d1a72ece3 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -697,8 +697,8 @@ void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx, >>>> memcg = page_memcg(head); >>>> /* Untracked pages have no memcg, no lruvec. Update only the node */ >>>> if (!memcg) { >>>> - rcu_read_unlock(); >>>> __mod_node_page_state(pgdat, idx, val); >>>> + rcu_read_unlock(); >>> >>> This rcu is for page_memcg. The preemption and interrupts are disabled >>> across __mod_lruvec_page_state(). >>> >> >> I thought it's used to protect __mod_node_page_state(). Looks somewhat confusing for me. >> Many thanks for pointing this out! > > Hi Miaohe, > > git show b4e0b68fbd9d can help you find out why we add > the rcu read lock around it. Thanks for your tip. That's my overlook when I checked this commit. I should have looked at this more closely. :( > > Thanks. > >> >>>> return; >>>> } >>>> >>>> -- >>>> 2.23.0 >>>> >>> . >>> >> > . >