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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADB9BC433EF for ; Sat, 13 Nov 2021 02:46:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0DAE0610F7 for ; Sat, 13 Nov 2021 02:46:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0DAE0610F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 046D66B0075; Fri, 12 Nov 2021 21:46:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id F36EE6B0078; Fri, 12 Nov 2021 21:46:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E274A6B007B; Fri, 12 Nov 2021 21:46:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0243.hostedemail.com [216.40.44.243]) by kanga.kvack.org (Postfix) with ESMTP id D52546B0075 for ; Fri, 12 Nov 2021 21:46:56 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 73DD6805CF for ; Sat, 13 Nov 2021 02:46:56 +0000 (UTC) X-FDA: 78802369632.10.B759342 Received: from mail-yb1-f173.google.com (mail-yb1-f173.google.com [209.85.219.173]) by imf01.hostedemail.com (Postfix) with ESMTP id 66F0E509ECB2 for ; Sat, 13 Nov 2021 02:45:05 +0000 (UTC) Received: by mail-yb1-f173.google.com with SMTP id g17so28461283ybe.13 for ; Fri, 12 Nov 2021 18:45:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=OWWGJ2bSIzx6ZQI/hIj2QOWLmreuvhZZr/DXZdLo9fM=; b=DRNlPSbPYnBu1vVs+yuGRo1MofzLumdbIreZL7hwabCMT428dc2HlfwS1A+nmfQb42 5JUiNBia2k6ZDjfSi5rWefIr+NMz8BwT9rRiZFLXrIu6s1LLPXL67I3cH+MtaQ4W7NTj V5SHXL+5o6u1WKyBgPVs/eHc7YFQkKl7eZlWe9Ub7ahcqDEwFDsWmuROyll3+bSwjgpU CRuGI/wrPwTLW8JxPutgfjis8eu33zN0VWUg7lMO4scWZcO96djZ4wgA6liUHM9vfupb LPMeQDxcEKn2GRI1LQr7NLUpPY0Pn3jfIMC8hcM1wuaBCMXqMDVoYDsi8dZfedpGsMhf WR8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=OWWGJ2bSIzx6ZQI/hIj2QOWLmreuvhZZr/DXZdLo9fM=; b=DFmr90Qs4YkpiksaGFH27AkAW35397shXbdtMGgBW+XlI3YbPzR+YXjOZVaMSxVlaf 5nVYYJpxS9gCJexZl6Xhvr4mruQqa5CxG0ZitikNA5qOvpIzJ4IL8O2neNMZIW9X+eQb JF+LLnX28q6sOwAByIpWVA7chz8Cfp3DbwdKgmG3gQ9sfmnVsQNrrVBZg8S79fWNg/H3 1ZCJkhAeByDUt5kPKawtLvANVyk7RI9iT6On8njpEkApjO7ZgkKEQBqGix3EF7pV4qdy uzl2fCd/giJ4qJnz+7wxTBZ4MUwcPFGTigznQkVnBKywM88jvN2oyH09oVSHdRCq8Ml6 kpTA== X-Gm-Message-State: AOAM533j3VTAW3CTqpT2WInEbPmPzQJ+nPIvUBNK32pWH0LLIsZfIldJ 5t3GLS4q1NxZplaVzSjVov/jwPwN3t2CSDbuYl0bdQ== X-Google-Smtp-Source: ABdhPJxov/ZfVmDPDIOb0pU3NO/b9DAw7w8pfg1RuWVaj1GRMDMcmVDRaBWxYwdwmQUxPi35zIdUZf731YgQxJGZ0Mg= X-Received: by 2002:a05:6902:68a:: with SMTP id i10mr19994226ybt.340.1636771519444; Fri, 12 Nov 2021 18:45:19 -0800 (PST) MIME-Version: 1.0 References: <20211111015037.4092956-1-almasrymina@google.com> In-Reply-To: From: Muchun Song Date: Sat, 13 Nov 2021 10:44:41 +0800 Message-ID: Subject: Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file To: Mike Kravetz Cc: Mina Almasry , Andrew Morton , Shuah Khan , Miaohe Lin , Oscar Salvador , Michal Hocko , David Rientjes , Shakeel Butt , Jue Wang , Yang Yao , Joanna Li , Cannon Matthews , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-HE-Tag: 1636771505-125300 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 Sat, Nov 13, 2021 at 7:36 AM Mike Kravetz wrot= e: > > Subject: Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file > > To: Muchun Song , Mina Almasry > > Cc: Andrew Morton , Shuah Khan , Miaohe Lin , Oscar Salvador , Michal Hocko , David Rientjes , Shakeel Butt , Jue Wang , Yang Yao= , Joanna Li , Cannon Matthews , Linux Memory Management List , = LKML > > Bcc: > > -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D# Don't remove this line #=3D-=3D-=3D= -=3D-=3D-=3D-=3D-=3D-=3D- > > On 11/10/21 6:36 PM, Muchun Song wrote: > > > On Thu, Nov 11, 2021 at 9:50 AM Mina Almasry w= rote: > > >> > > >> +struct hugetlb_cgroup_per_node { > > >> + /* hugetlb usage in pages over all hstates. */ > > >> + atomic_long_t usage[HUGE_MAX_HSTATE]; > > > > > > Why do you use atomic? IIUC, 'usage' is always > > > increased/decreased under hugetlb_lock except > > > hugetlb_cgroup_read_numa_stat() which is always > > > reading it. So I think WRITE_ONCE/READ_ONCE > > > is enough. > > > > Thanks for continuing to work this, I was traveling and unable to > > comment. Have a good time. > > > > Unless I am missing something, I do not see a reason for WRITE_ONCE/READ_= ONCE Because __hugetlb_cgroup_commit_charge and hugetlb_cgroup_read_numa_stat can run parallely, which meets the definition of data race. I believe KCSAN could report this race. I'm not strongly suggest using WRITE/READ_ONCE() here. But in theory it should be like this. Right? Thanks. > > and would suggest going back to the way this code was in v5. > > -- > > Mike Kravetz >