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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 07756C433E0 for ; Thu, 18 Jun 2020 08:51:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE8CA20B1F for ; Thu, 18 Jun 2020 08:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728820AbgFRIv2 (ORCPT ); Thu, 18 Jun 2020 04:51:28 -0400 Received: from foss.arm.com ([217.140.110.172]:46330 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728536AbgFRIv1 (ORCPT ); Thu, 18 Jun 2020 04:51:27 -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 3579931B; Thu, 18 Jun 2020 01:51:26 -0700 (PDT) Received: from e113632-lin (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A010F3F6CF; Thu, 18 Jun 2020 01:51:24 -0700 (PDT) References: <20200617121742.cpxppyi7twxmpin7@linutronix.de> <696309d91635fa965ad8436388e7ae7d098420a1.camel@redhat.com> <20200618080700.cig4x4y7n3thmneu@linutronix.de> User-agent: mu4e 0.9.17; emacs 26.3 From: Valentin Schneider To: Sebastian Andrzej Siewior Cc: Scott Wood , linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Thomas Gleixner Subject: Re: [PATCH] sched: __set_cpus_allowed_ptr(): Check cpus_mask, not cpus_ptr In-reply-to: <20200618080700.cig4x4y7n3thmneu@linutronix.de> Date: Thu, 18 Jun 2020 09:51:18 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/06/20 09:07, Sebastian Andrzej Siewior wrote: > On 2020-06-17 17:49:48 [-0500], Scott Wood wrote: >> > Makes sense, but what about the rest of the checks? Further down there is >> > >> > /* Can the task run on the task's current CPU? If so, we're done >> > */ >> > if (cpumask_test_cpu(task_cpu(p), new_mask)) >> > goto out; >> > >> > If the task is currently migrate disabled and for some stupid reason it >> > gets affined elsewhere, we could try to move it out - which AFAICT we >> > don't >> > want to do because migrate disabled. So I suppose you'd want an extra >> > bailout condition here when the task is migrate disabled. >> > >> > ISTR in RT you do re-check the affinity and potentially move the task away >> > when re-enabling migration, so that should work out all fine. >> >> On RT the above test is: >> >> /* Can the task run on the task's current CPU? If so, we're done */ >> if (cpumask_test_cpu(task_cpu(p), new_mask) || >> p->cpus_ptr != &p->cpus_mask) >> goto out; >> >> ...so we do bail out if we're migrate disabled. > > correct. There is a complete migrate_disable() patch in the RT queue > which has to wait. This patch however looked to be independent of that > and could "fix" the pointer part which is already here so I sent it. > Okay, thanks. I don't see any harm in including that extra check with the patch, but either way: Reviewed-by: Valentin Schneider >> -Scott > > Sebastian