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 810B2C433EF for ; Mon, 13 Jun 2022 03:04:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234086AbiFMDEX (ORCPT ); Sun, 12 Jun 2022 23:04:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234511AbiFMDEW (ORCPT ); Sun, 12 Jun 2022 23:04:22 -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 ESMTP id 590615FFF for ; Sun, 12 Jun 2022 20:04:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655089460; 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=I0JU6u7vHZ6SvfZIROd4EtKu4qFIwPLVf15Wl39hmo0=; b=KxrgwSmT7WS8VFdgYJ7Ha85LK/oS78IwW0UULmJ8cGYzkKjmgqh88s6pe9RuLDXfgNCF/K r/mPWykCADsVIiSP+U2hqEp14FRuXwvPAWNbe698df1/Ocr24MUP+IfDryFiZqtj4jTHQy wNEMwIzw5crDoJ//w6OKUXQa3Nm5eb8= 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-63-arB-8VpdMqKwfkM8I74vdA-1; Sun, 12 Jun 2022 23:04:15 -0400 X-MC-Unique: arB-8VpdMqKwfkM8I74vdA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DDC5D85A582; Mon, 13 Jun 2022 03:04:14 +0000 (UTC) Received: from [10.22.16.100] (unknown [10.22.16.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3C04F1415103; Mon, 13 Jun 2022 03:04:14 +0000 (UTC) Message-ID: Date: Sun, 12 Jun 2022 23:04:14 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v11 3/8] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective Content-Language: en-US To: Tejun Heo Cc: Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Roman Gushchin , Phil Auld , Peter Zijlstra , Juri Lelli , Frederic Weisbecker , Marcelo Tosatti , =?UTF-8?Q?Michal_Koutn=c3=bd?= References: <20220510153413.400020-1-longman@redhat.com> <20220510153413.400020-4-longman@redhat.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 6/12/22 22:55, Tejun Heo wrote: > On Sun, Jun 12, 2022 at 10:53:53PM -0400, Waiman Long wrote: >> Without this patch, cpus.effective will never be empty. It just falls back >> to its parent if it becomes empty. Now with an empty cpus.effective, I am > Yeah, that part is fine. > >> afraid that if a task is somehow moved to such a cpuset, something bad may >> happen. So I add this check as a safeguard. > But how would that happen? A lot of other things would break too if that > were to happen. I will perform further check to see if this check is necessary. Thanks, Longman