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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8A75C433EF for ; Tue, 15 Feb 2022 12:19:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237584AbiBOMTu (ORCPT ); Tue, 15 Feb 2022 07:19:50 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232094AbiBOMTs (ORCPT ); Tue, 15 Feb 2022 07:19:48 -0500 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DE8C1074E6 for ; Tue, 15 Feb 2022 04:19:39 -0800 (PST) Received: by mail-pf1-x432.google.com with SMTP id f6so13583481pfj.11 for ; Tue, 15 Feb 2022 04:19:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=t4VIfPOAozNC70kbDOl2dbBGsgdLxKSP4QJrhlwbu5k=; b=yyPjnmR65ZCx8CliAl5MrjTv9+HVfnSjBHgKjhUGGWHpNtMQ3MrbqjhZKmbJ4Ko+bx LumaWc5vrjhUHkrk/GCHfhEIlw9m+hQrIdOHvCwdRhQ1vbLqCIPgfRipClamscTA3LDw SwC3RN+HIeuaP2HLdtnAivns5km7Haf5yjKAJo2tIX7G6Fh+5ia+S7KGem6DBgSpCOTR Sn84/Y8jlIekJSXbhd8KTg4O1LOakBoFxYDA8U1ADohldqKVPkYVOFRPUt7MaCC+TSib TFrGXB+d33NMx/ESGHZHd6JMgsDxUI6Yyjf9WypdjvJDM1ml6XV/fgLioq40ccaxEFy1 R/Jg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=t4VIfPOAozNC70kbDOl2dbBGsgdLxKSP4QJrhlwbu5k=; b=On4sAnvfbYhmzb1qjMhqi7YBpuBEWYlnR19C7rbfr1rj2TEupfFXsvZwDB0xWYSpCF IXZtmEu7l5VK9moRfYcd5brzA403SjTu/KtIAZT5X9i/r+bFLi2KtRAdz5BpJ4VCPX43 zR59sCR4W5VYBkumTWKa/wN/D1/QiJ9ziAsIvqmhnestb6G9pHgTBXAntwhNBMBD6+H1 tYPe+PYNl2JuYMHUonrtEa/jWo709y7Uzk6bgkRJAB2tFqa256hCiyRNAAvCHlT/0FfJ 2yR4sidyGn1CCgk8gxBqvYNGB/skSX5yac8/ARRzzsAq74vMw+D87IofurO9et7XEC8h ik4Q== X-Gm-Message-State: AOAM532BAF+NuWSLrCeFmPeZwaxWVJ14Ww5iPJCnZ/X2q7cMX6j5BfgB BW5C9My6QpCScuUqbLcAjNS6nUIpK9J7Jg== X-Google-Smtp-Source: ABdhPJyyX/bNQ6faE4RjKlHG3VF68qqDZQ25cF/jMO0cIIJIK7Zt3bWZ6ezKMnlD1KgSLiGYM7nuuw== X-Received: by 2002:a05:6a00:2444:: with SMTP id d4mr4123710pfj.46.1644927578757; Tue, 15 Feb 2022 04:19:38 -0800 (PST) Received: from [10.255.13.118] ([139.177.225.246]) by smtp.gmail.com with ESMTPSA id s9sm5706044pjk.1.2022.02.15.04.19.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Feb 2022 04:19:38 -0800 (PST) Message-ID: Date: Tue, 15 Feb 2022 20:19:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [External] Re: [PATCH] sched/cpuacct: fix charge percpu cpuusage Content-Language: en-US To: Peter Zijlstra Cc: tj@kernel.org, arbn@yandex-team.com, mingo@redhat.com, linux-kernel@vger.kernel.org, Minye Zhu References: <20220213120118.93471-1-zhouchengming@bytedance.com> From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/2/14 6:09 下午, Peter Zijlstra wrote: > On Sun, Feb 13, 2022 at 08:01:18PM +0800, Chengming Zhou wrote: >> The cpuacct_account_field() is always called by the current task >> itself, so it's ok to use __this_cpu_add() to charge the tick time. >> >> But cpuacct_charge() maybe called by update_curr() in load_balance() >> on a random CPU, different from the CPU on which the task is running. >> So __this_cpu_add() will charge that cputime to a random incorrect CPU. >> >> Reported-by: Minye Zhu >> Signed-off-by: Chengming Zhou > > Can I get a Fixes: tag for this? Yes, Fixes: 73e6aafd9ea8 ("sched/cpuacct: Simplify the cpuacct code") I will send a patch v2 to add it. > >> --- >> kernel/sched/cpuacct.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c >> index 3d06c5e4220d..75fbc212cb71 100644 >> --- a/kernel/sched/cpuacct.c >> +++ b/kernel/sched/cpuacct.c >> @@ -335,11 +335,12 @@ static struct cftype files[] = { >> void cpuacct_charge(struct task_struct *tsk, u64 cputime) >> { >> struct cpuacct *ca; >> + unsigned int cpu = task_cpu(tsk); >> >> rcu_read_lock(); >> >> for (ca = task_ca(tsk); ca; ca = parent_ca(ca)) >> - __this_cpu_add(*ca->cpuusage, cputime); >> + *per_cpu_ptr(ca->cpuusage, cpu) += cputime; >> >> rcu_read_unlock(); >> } > > Also, while we there, what about this as an additional patch? > > --- a/kernel/sched/cpuacct.c > +++ b/kernel/sched/cpuacct.c > @@ -334,15 +334,13 @@ static struct cftype files[] = { > */ > void cpuacct_charge(struct task_struct *tsk, u64 cputime) > { > - struct cpuacct *ca; > unsigned int cpu = task_cpu(tsk); > + struct cpuacct *ca; > > - rcu_read_lock(); > + lockdep_assert_rq_held(cpu_rq(cpu)); > > for (ca = task_ca(tsk); ca; ca = parent_ca(ca)) > *per_cpu_ptr(ca->cpuusage, cpu) += cputime; > - > - rcu_read_unlock(); > } > > /* This is much better, I will send an additional patch to include this. Thanks.