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 8C349C76188 for ; Mon, 3 Apr 2023 17:19:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232927AbjDCRTk (ORCPT ); Mon, 3 Apr 2023 13:19:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232744AbjDCRTi (ORCPT ); Mon, 3 Apr 2023 13:19:38 -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 989F91BF for ; Mon, 3 Apr 2023 10:18:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680542326; 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=f9kl6sR8CDHCLHRJZnldn58uw/G4gK2ubpkyUoDgp1A=; b=FEKZZAkHWkp0/EJuqJAvofOEqTnG1XSV2GaaUXfc8UScyM14+aIesavGG/H+YpRFDldbtR Gr/phmH+R7gh19f447IB3J1hxy2Mg25OkcasC9dtttWXsVS1XHk1PtYryncUfxbSaAVyE5 8ptl1T1y4/527Ckv+ekGKA249g562W4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-547-MhGGYRJeNb-Gfs5MyfcpgA-1; Mon, 03 Apr 2023 13:18:43 -0400 X-MC-Unique: MhGGYRJeNb-Gfs5MyfcpgA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3E269886463; Mon, 3 Apr 2023 17:18:43 +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 C9527492C13; Mon, 3 Apr 2023 17:18:42 +0000 (UTC) Message-ID: Date: Mon, 3 Apr 2023 13:18:42 -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 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> From: Waiman Long In-Reply-To: <20230403165523.aphsec2epqi72k27@blackpad> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 3) security_task_setscheduler() - the CLONE_INTO_CGROUP code has already checked that, we don't need to duplicate the check. So we don't need a can_fork() check for now. Cheers, Longman