From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756231AbdJJLFX (ORCPT ); Tue, 10 Oct 2017 07:05:23 -0400 Received: from terminus.zytor.com ([65.50.211.136]:46009 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754938AbdJJLFT (ORCPT ); Tue, 10 Oct 2017 07:05:19 -0400 Date: Tue, 10 Oct 2017 04:00:39 -0700 From: tip-bot for Brendan Jackman Message-ID: Cc: morten.rasmussen@arm.com, josef@toxicpanda.com, hpa@zytor.com, brendan.jackman@arm.com, torvalds@linux-foundation.org, vincent.guittot@linaro.org, peterz@infradead.org, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, efault@gmx.de, jbacik@fb.com, dietmar.eggemann@arm.com Reply-To: peterz@infradead.org, dietmar.eggemann@arm.com, jbacik@fb.com, linux-kernel@vger.kernel.org, efault@gmx.de, mingo@kernel.org, tglx@linutronix.de, josef@toxicpanda.com, morten.rasmussen@arm.com, torvalds@linux-foundation.org, vincent.guittot@linaro.org, brendan.jackman@arm.com, hpa@zytor.com In-Reply-To: <20171005114516.18617-5-brendan.jackman@arm.com> References: <20171005114516.18617-5-brendan.jackman@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/fair: Fix usage of find_idlest_group() when no groups are allowed Git-Commit-ID: 6fee85ccbc76e8aeba43dc120c5fa3c5409a4e2c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6fee85ccbc76e8aeba43dc120c5fa3c5409a4e2c Gitweb: https://git.kernel.org/tip/6fee85ccbc76e8aeba43dc120c5fa3c5409a4e2c Author: Brendan Jackman AuthorDate: Thu, 5 Oct 2017 12:45:15 +0100 Committer: Ingo Molnar CommitDate: Tue, 10 Oct 2017 11:45:35 +0200 sched/fair: Fix usage of find_idlest_group() when no groups are allowed When 'p' is not allowed on any of the CPUs in the sched_domain, we currently return NULL from find_idlest_group(), and pointlessly continue the search on lower sched_domain levels (where 'p' is also not allowed) before returning prev_cpu regardless (as we have not updated new_cpu). Add an explicit check for this case, and add a comment to find_idlest_group(). Now when find_idlest_group() returns NULL, it always means that the local group is allowed and idlest. Signed-off-by: Brendan Jackman Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Reviewed-by: Josef Bacik Cc: Dietmar Eggemann Cc: Josef Bacik Cc: Linus Torvalds Cc: Mike Galbraith Cc: Morten Rasmussen Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20171005114516.18617-5-brendan.jackman@arm.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cca1835..ed80d6b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5730,6 +5730,8 @@ static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) /* * find_idlest_group finds and returns the least busy CPU group within the * domain. + * + * Assumes p is allowed on at least one CPU in sd. */ static struct sched_group * find_idlest_group(struct sched_domain *sd, struct task_struct *p, @@ -5917,6 +5919,9 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p { int new_cpu = prev_cpu; + if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed)) + return prev_cpu; + while (sd) { struct sched_group *group; struct sched_domain *tmp;