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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 CC420C4707C for ; Fri, 21 May 2021 17:39:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AECF061168 for ; Fri, 21 May 2021 17:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238324AbhEURlL (ORCPT ); Fri, 21 May 2021 13:41:11 -0400 Received: from foss.arm.com ([217.140.110.172]:52480 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234956AbhEURlC (ORCPT ); Fri, 21 May 2021 13:41:02 -0400 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 E389C1424; Fri, 21 May 2021 10:39:38 -0700 (PDT) Received: from e107158-lin.cambridge.arm.com (e107158-lin.cambridge.arm.com [10.1.195.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 953653F73D; Fri, 21 May 2021 10:39:36 -0700 (PDT) Date: Fri, 21 May 2021 18:39:34 +0100 From: Qais Yousef To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Li Zefan , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , kernel-team@android.com Subject: Re: [PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Message-ID: <20210521173934.pjcv37j63odtsrp6@e107158-lin.cambridge.arm.com> References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-8-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210518094725.7701-8-will@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/18/21 10:47, Will Deacon wrote: > If the scheduler cannot find an allowed CPU for a task, > cpuset_cpus_allowed_fallback() will widen the affinity to cpu_possible_mask > if cgroup v1 is in use. > > In preparation for allowing architectures to provide their own fallback > mask, just return early if we're either using cgroup v1 or we're using > cgroup v2 with a mask that contains invalid CPUs. This will allow > select_fallback_rq() to figure out the mask by itself. > > Cc: Li Zefan > Cc: Tejun Heo > Cc: Johannes Weiner > Reviewed-by: Quentin Perret > Signed-off-by: Will Deacon > --- > include/linux/cpuset.h | 1 + > kernel/cgroup/cpuset.c | 12 ++++++++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h > index 04c20de66afc..ed6ec677dd6b 100644 > --- a/include/linux/cpuset.h > +++ b/include/linux/cpuset.h > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > > #ifdef CONFIG_CPUSETS > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index a945504c0ae7..8c799260a4a2 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -3322,9 +3322,17 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) > > void cpuset_cpus_allowed_fallback(struct task_struct *tsk) > { > + const struct cpumask *cs_mask; > + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); > + > rcu_read_lock(); > - do_set_cpus_allowed(tsk, is_in_v2_mode() ? > - task_cs(tsk)->cpus_allowed : cpu_possible_mask); > + cs_mask = task_cs(tsk)->cpus_allowed; > + > + if (!is_in_v2_mode() || !cpumask_subset(cs_mask, possible_mask)) > + goto unlock; /* select_fallback_rq will try harder */ > + > + do_set_cpus_allowed(tsk, cs_mask); Shouldn't we take the intersection with possible_mask like we discussed before? https://lore.kernel.org/lkml/20201217145954.GA17881@willie-the-truck/ Thanks -- Qais Yousef > +unlock: > rcu_read_unlock(); > > /* > -- > 2.31.1.751.gd2f1c929bd-goog >