Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756948Ab2FFP4S (ORCPT ); Wed, 6 Jun 2012 11:56:18 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40264 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756675Ab2FFP4P (ORCPT ); Wed, 6 Jun 2012 11:56:15 -0400 Date: Wed, 6 Jun 2012 08:56:03 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Always initialize cpu-power Git-Commit-ID: c3decf0dfbc95736b7c0ab68fa4e5854c4734da9 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-4.2.6 (terminus.zytor.com [127.0.0.1]); Wed, 06 Jun 2012 08:56:08 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2614 Lines: 73 Commit-ID: c3decf0dfbc95736b7c0ab68fa4e5854c4734da9 Gitweb: http://git.kernel.org/tip/c3decf0dfbc95736b7c0ab68fa4e5854c4734da9 Author: Peter Zijlstra AuthorDate: Thu, 31 May 2012 12:05:32 +0200 Committer: Ingo Molnar CommitDate: Wed, 6 Jun 2012 16:52:27 +0200 sched: Always initialize cpu-power Often when we run into mis-shapen topologies the balance iteration fails to update the cpu power properly and we'll end up in /0 traps. Always initialize the cpu-power to a semi-sane value so that we can at least boot the machine, even if the load-balancer might not function correctly. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-3lbhyj25sr169ha7z3qht5na@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 13 ++++++++++++- kernel/sched/fair.c | 2 +- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 781acb9..725ee7c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5604,7 +5604,12 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, break; } - if (!group->sgp->power) { + /* + * Even though we initialize ->power to something semi-sane, + * we leave power_orig unset. This allows us to detect if + * domain iteration is still funny without causing /0 traps. + */ + if (!group->sgp->power_orig) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: domain->cpu_power not " "set\n"); @@ -6075,6 +6080,12 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) if (atomic_inc_return(&sg->sgp->ref) == 1) build_group_mask(sd, sg); + /* + * Initialize sgp->power such that even if we mess up the + * domains and no possible iteration will get us here, we won't + * die on a /0 trap. + */ + sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); /* * Make sure the first group of this domain contains the diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 54cbaa4..c9fd6d6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3602,7 +3602,7 @@ void update_group_power(struct sched_domain *sd, int cpu) } while (group != child->groups); } - sdg->sgp->power = power; + sdg->sgp->power_orig = sdg->sgp->power = power; } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/