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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 84C69CA9EBB for ; Mon, 4 Nov 2019 00:47:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58024222CA for ; Mon, 4 Nov 2019 00:47:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728615AbfKDArz (ORCPT ); Sun, 3 Nov 2019 19:47:55 -0500 Received: from foss.arm.com ([217.140.110.172]:33508 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728277AbfKDAry (ORCPT ); Sun, 3 Nov 2019 19:47:54 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F1C1A1FB; Sun, 3 Nov 2019 16:47:53 -0800 (PST) Received: from [10.0.2.15] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C4BA3F67D; Sun, 3 Nov 2019 16:47:52 -0800 (PST) Subject: Re: [PATCH v2] sched/topology, cpuset: Account for housekeeping CPUs to avoid empty cpumasks From: Valentin Schneider To: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Cc: lizefan@huawei.com, tj@kernel.org, hannes@cmpxchg.org, mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, Dietmar.Eggemann@arm.com, morten.rasmussen@arm.com, qperret@google.com, =?UTF-8?Q?Michal_Koutn=c3=bd?= References: <20191104003906.31476-1-valentin.schneider@arm.com> Message-ID: Date: Mon, 4 Nov 2019 00:47:50 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191104003906.31476-1-valentin.schneider@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/11/2019 00:39, Valentin Schneider wrote: > Michal noted that a cpuset's effective_cpus can be a non-empy mask, but > because of the masking done with housekeeping_cpumask(HK_FLAG_DOMAIN) > further down the line, we can still end up with an empty cpumask being > passed down to partition_sched_domains_locked(). > > Do the proper thing and don't just check the mask is non-empty - check > that its intersection with housekeeping_cpumask(HK_FLAG_DOMAIN) is > non-empty. > > Fixes: cd1cb3350561 ("sched/topology: Don't try to build empty sched domains") > Reported-by: Michal Koutný > Signed-off-by: Valentin Schneider > --- Sigh, this is missing: v2 changes: - Fix broken diff At least it *does* apply this time around. > kernel/cgroup/cpuset.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index c87ee6412b36..e4c10785dc7c 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -798,8 +798,14 @@ static int generate_sched_domains(cpumask_var_t **domains, > cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus)) > continue; > > + /* > + * Skip cpusets that would lead to an empty sched domain. > + * That could be because effective_cpus is empty, or because > + * it's only spanning CPUs outside the housekeeping mask. > + */ > if (is_sched_load_balance(cp) && > - !cpumask_empty(cp->effective_cpus)) > + cpumask_intersects(cp->effective_cpus, > + housekeeping_cpumask(HK_FLAG_DOMAIN))) > csa[csn++] = cp; > > /* skip @cp's subtree if not a partition root */ >