From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753455Ab3KSTQO (ORCPT ); Tue, 19 Nov 2013 14:16:14 -0500 Received: from terminus.zytor.com ([198.137.202.10]:51683 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752197Ab3KSTQL (ORCPT ); Tue, 19 Nov 2013 14:16:11 -0500 Date: Tue, 19 Nov 2013 11:15:24 -0800 From: tip-bot for Srikar Dronamraju Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com, peterz@infradead.org, tglx@linutronix.de In-Reply-To: <20131113151718.GN21461@twins.programming.kicks-ass.net> References: <20131113151718.GN21461@twins.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Check sched_domain before computing group power Git-Commit-ID: 9abf24d465180f5f2eb26a43545348262f16b771 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 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Tue, 19 Nov 2013 11:15:31 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9abf24d465180f5f2eb26a43545348262f16b771 Gitweb: http://git.kernel.org/tip/9abf24d465180f5f2eb26a43545348262f16b771 Author: Srikar Dronamraju AuthorDate: Tue, 12 Nov 2013 22:11:26 +0530 Committer: Ingo Molnar CommitDate: Tue, 19 Nov 2013 17:01:15 +0100 sched: Check sched_domain before computing group power After commit 863bffc80898 ("sched/fair: Fix group power_orig computation"), we can dereference rq->sd before it is set. Fix this by falling back to power_of() in this case and add a comment explaining things. Signed-off-by: Srikar Dronamraju [ Added comment and tweaked patch. ] Signed-off-by: Peter Zijlstra Cc: mikey@neuling.org Link: http://lkml.kernel.org/r/20131113151718.GN21461@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e8b652e..fd773ad 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5379,10 +5379,31 @@ void update_group_power(struct sched_domain *sd, int cpu) */ for_each_cpu(cpu, sched_group_cpus(sdg)) { - struct sched_group *sg = cpu_rq(cpu)->sd->groups; + struct sched_group_power *sgp; + struct rq *rq = cpu_rq(cpu); - power_orig += sg->sgp->power_orig; - power += sg->sgp->power; + /* + * build_sched_domains() -> init_sched_groups_power() + * gets here before we've attached the domains to the + * runqueues. + * + * Use power_of(), which is set irrespective of domains + * in update_cpu_power(). + * + * This avoids power/power_orig from being 0 and + * causing divide-by-zero issues on boot. + * + * Runtime updates will correct power_orig. + */ + if (unlikely(!rq->sd)) { + power_orig += power_of(cpu); + power += power_of(cpu); + continue; + } + + sgp = rq->sd->groups->sgp; + power_orig += sgp->power_orig; + power += sgp->power; } } else { /*