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 A7306C76196 for ; Mon, 3 Apr 2023 17:30:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232663AbjDCRat (ORCPT ); Mon, 3 Apr 2023 13:30:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229379AbjDCRaq (ORCPT ); Mon, 3 Apr 2023 13:30:46 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 697D2198A for ; Mon, 3 Apr 2023 10:30:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680543002; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D1X5SC7LKhlLocmRueF17WE70pwm2bzlUhxp0ZwVzj8=; b=fuNta2PnqTniRsVTm6RfJsoM0Pj1J3Kib6mZQeOhobkRifykTMukXzDBAujNSaeEc8MeoC tk2pHS/1r1lPJVxulbn7vlu3mMKP7c2bkOGVbdlUHOmKe4oDDNCDWtDYWndKgO5QCYfYn3 b3z1yPoj53hWXAaLN4YdSE/lT1yZ8dE= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-563-qzZGLCXJNiKX1MnoIJst9w-1; Mon, 03 Apr 2023 13:29:59 -0400 X-MC-Unique: qzZGLCXJNiKX1MnoIJst9w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id ADD7B1C04B69; Mon, 3 Apr 2023 17:29:58 +0000 (UTC) Received: from [10.18.17.153] (dhcp-17-153.bos.redhat.com [10.18.17.153]) by smtp.corp.redhat.com (Postfix) with ESMTP id E65A140C6EC4; Mon, 3 Apr 2023 17:29:57 +0000 (UTC) Message-ID: <44843f08-b7c2-42e3-1951-a0c5688190a1@redhat.com> Date: Mon, 3 Apr 2023 13:29:57 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly Content-Language: en-US From: Waiman Long To: =?UTF-8?Q?Michal_Koutn=c3=bd?= Cc: Tejun Heo , Zefan Li , Johannes Weiner , Christian Brauner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Juri Lelli , Dietmar Eggemann , gscrivan@redhat.com References: <20230331145045.2251683-1-longman@redhat.com> <20230331145045.2251683-2-longman@redhat.com> <20230403165523.aphsec2epqi72k27@blackpad> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/3/23 13:18, Waiman Long wrote: > > On 4/3/23 12:55, Michal Koutný wrote: >> On Fri, Mar 31, 2023 at 10:50:43AM -0400, Waiman Long >> wrote: >>> By default, the clone(2) syscall spawn a child process into the same >>> cgroup as its parent. With the use of the CLONE_INTO_CGROUP flag >>> introduced by commit ef2c41cf38a7 ("clone3: allow spawning processes >>> into cgroups"), the child will be spawned into a different cgroup which >>> is somewhat similar to writing the child's tid into "cgroup.threads". >>> >>> The current cpuset_fork() method does not properly handle the >>> CLONE_INTO_CGROUP case where the cpuset of the child may be different >>> from that of its parent.  Update the cpuset_fork() method to treat the >>> CLONE_INTO_CGROUP case similar to cpuset_attach(). >> Should .can_fork=cpuset_can_fork in analogy to cpuset_can_attach be also >> devised? (Sorry if I missed that in the previous discussion.) > > I have thought about that too. > > However, the can_attach method checks only a couple of things: > > 1) PF_NO_SETAFFINITY flag - which won't be set in the case of fork() > as it is for kthread only. > 2) DL bandwidth - Juri has a cpuset outstanding to modify the way this > check is being done. I want to wait until it is settled before > tackling this, if necessary. BTW, even cloning without CLONE_INTO_CGROUP can be an issue WRT DL bandwidth. So I will let the scheduler folk figure out what to do with that. Cheers, Longman