From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756237AbdJJLFv (ORCPT ); Tue, 10 Oct 2017 07:05:51 -0400 Received: from terminus.zytor.com ([65.50.211.136]:45833 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755824AbdJJLFt (ORCPT ); Tue, 10 Oct 2017 07:05:49 -0400 Date: Tue, 10 Oct 2017 04:01:03 -0700 From: tip-bot for Brendan Jackman Message-ID: Cc: dietmar.eggemann@arm.com, peterz@infradead.org, brendan.jackman@arm.com, mingo@kernel.org, linux-kernel@vger.kernel.org, efault@gmx.de, morten.rasmussen@arm.com, tglx@linutronix.de, josef@toxicpanda.com, vincent.guittot@linaro.org, jbacik@fb.com, torvalds@linux-foundation.org, hpa@zytor.com Reply-To: efault@gmx.de, morten.rasmussen@arm.com, josef@toxicpanda.com, tglx@linutronix.de, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, peterz@infradead.org, mingo@kernel.org, brendan.jackman@arm.com, linux-kernel@vger.kernel.org, jbacik@fb.com, torvalds@linux-foundation.org, hpa@zytor.com In-Reply-To: <20171005114516.18617-6-brendan.jackman@arm.com> References: <20171005114516.18617-6-brendan.jackman@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/fair: Fix usage of find_idlest_group() when the local group is idlest Git-Commit-ID: 93f50f90247e3e926bbe9830df089c64a5cec236 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: 93f50f90247e3e926bbe9830df089c64a5cec236 Gitweb: https://git.kernel.org/tip/93f50f90247e3e926bbe9830df089c64a5cec236 Author: Brendan Jackman AuthorDate: Thu, 5 Oct 2017 12:45:16 +0100 Committer: Ingo Molnar CommitDate: Tue, 10 Oct 2017 11:45:36 +0200 sched/fair: Fix usage of find_idlest_group() when the local group is idlest find_idlest_group() returns NULL when the local group is idlest. The caller then continues the find_idlest_group() search at a lower level of the current CPU's sched_domain hierarchy. find_idlest_group_cpu() is not consulted and, crucially, @new_cpu is not updated. This means the search is pointless and we return @prev_cpu from select_task_rq_fair(). This is fixed by initialising @new_cpu to @cpu instead of @prev_cpu. Signed-off-by: Brendan Jackman Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josef Bacik Reviewed-by: Vincent Guittot 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/20171005114516.18617-6-brendan.jackman@arm.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ed80d6b..56f343b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5917,7 +5917,7 @@ find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p, int cpu, int prev_cpu, int sd_flag) { - int new_cpu = prev_cpu; + int new_cpu = cpu; if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed)) return prev_cpu;