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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 D4223C34047 for ; Wed, 19 Feb 2020 15:19:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A692224656 for ; Wed, 19 Feb 2020 15:19:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582125566; bh=zt+Cc6b708uwVy9P2ZOmPG9kEF3K2JISVVsfp/BnBdE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=C8GBLtpATwxrxpZIvxzbGCBHY/Dv5vZWWbBhJ6y2OxsTSjyIh+ePfPLVuMxfaT+uR fRoH3VG/j6cO0oWGIPPt7U8DkHWndH+jwnSCsG4q2cGqZd5WgB3tGPcYOBrcKmJ9uS qCktfe40nBeKl0xhVswa83Ly38/Pe5adsMxh0NOg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726980AbgBSPTZ (ORCPT ); Wed, 19 Feb 2020 10:19:25 -0500 Received: from mail-qk1-f172.google.com ([209.85.222.172]:37388 "EHLO mail-qk1-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726634AbgBSPTZ (ORCPT ); Wed, 19 Feb 2020 10:19:25 -0500 Received: by mail-qk1-f172.google.com with SMTP id c188so438187qkg.4; Wed, 19 Feb 2020 07:19:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=SUXofl/MO5dWKqPfuAcBzgvKEpVFwkTb4AVbcHvWhdc=; b=qPicIwGzMD/HopbeCVkjoisZLYQAfbLcyi1p0R1hAaHnso/AF0eu8g8vXlN6X9FEtL 7fECFrXeR75PQ2/4EVbfDkXZbWXLnCZr7B4njrFd2xev//SFJ56qpIS7cTAGwLOppIW+ 6QoIEKm0kuX4X1tDUjofK4Xwep6ZNvUTyo3/6OkUYns5edz9MSvCBMcFqSaIEeLPNjYc jVK5cC7Qcho1lEs9bINnbQ/2tR+4alIRjxDZ/mm7X8VPxSrCXF1CXFjBGBewsAJyrwt1 BBtqD47i/ja6Hd9VM80jRs/6hlKZn+c7PApQ4oKjv//RN+EflbPUKgkHwt4/RA+hrmHd IHPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=SUXofl/MO5dWKqPfuAcBzgvKEpVFwkTb4AVbcHvWhdc=; b=HWAOpTO7ZNjNKwr2YAwDJfjuOeHSRSzsl3H7v1Iqmnk/VCy+1+NnLVVS4KuY7lbuvX 70cOhi0yEN7SHaH1Mrd6D8mk7tfeTqsWxT3olHhHF0mm5Ddps26/GLxTjYFq7ob/dVDf FY4Cxpq2IWoZFiturh++kfxZP6OMQ4i+uHMkOIG24dW7qHhckysR69TRVVwNhID8OlwC IPCRX19/dNQqmLwdC2kLbDRQWMvqUuA7ZL/5QKXVX/bKYGJKiF9w4VLLI0wR281Jdy1H fevu+r4A8AyIkHxSzlA550i9tkpa4rs/AX7tL/hlwbO5amG0oDJYomLUvUTIfWZe+539 V3Fw== X-Gm-Message-State: APjAAAWu3e1f6qIrZG91bexIKj6Nt4PHB/5L4g6ROWijFMhBeJ+K/Eyy jfFMS1wOFaoAmuOaGbnwy+4= X-Google-Smtp-Source: APXvYqz4XQB8eDF2DfUmb5+BpK601xOFtKM68l7/bbHY+fI8/esjoy0xFswzTchxq8tI/vgvXmPh7w== X-Received: by 2002:a37:7245:: with SMTP id n66mr25311079qkc.202.1582125563903; Wed, 19 Feb 2020 07:19:23 -0800 (PST) Received: from localhost ([2620:10d:c091:500::2:e7ce]) by smtp.gmail.com with ESMTPSA id o10sm117547qtp.38.2020.02.19.07.19.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Feb 2020 07:19:23 -0800 (PST) Date: Wed, 19 Feb 2020 10:19:22 -0500 From: Tejun Heo To: Mathieu Desnoyers Cc: Li Zefan , cgroups@vger.kernel.org, linux-kernel , Peter Zijlstra , Ingo Molnar , Valentin Schneider Subject: Re: [regression] cpuset: offlined CPUs removed from affinity masks Message-ID: <20200219151922.GB698990@mtj.thefacebook.com> References: <1251528473.590671.1579196495905.JavaMail.zimbra@efficios.com> <1317969050.4131.1581955387909.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317969050.4131.1581955387909.JavaMail.zimbra@efficios.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, Feb 17, 2020 at 11:03:07AM -0500, Mathieu Desnoyers wrote: > Hi, > > Adding Tejun and the cgroups mailing list in CC for this cpuset regression I > reported last month. > > Thanks, > > Mathieu > > ----- On Jan 16, 2020, at 12:41 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > > > Hi, > > > > I noticed the following regression with CONFIG_CPUSET=y. Note that > > I am not using cpusets at all (only using the root cpuset I'm given > > at boot), it's just configured in. I am currently working on a 5.2.5 > > kernel. I am simply combining use of taskset(1) (setting the affinity > > mask of a process) and cpu hotplug. The result is that with > > CONFIG_CPUSET=y, setting the affinity mask including an offline CPU number > > don't keep that CPU in the affinity mask, and it is never put back when the > > CPU comes back online. CONFIG_CPUSET=n behaves as expected, and puts back > > the CPU into the affinity mask reported to user-space when it comes back > > online. Because cpuset operations irreversibly change task affinity masks rather than masking them dynamically, the interaction has always been kinda broken. Hmm... Are there older kernel vesions which behave differently? Off the top of my head, I can't think of sth which could have changed that behavior recently but I could easily be missing something. Thanks. -- tejun