From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758682AbZBLKvH (ORCPT ); Thu, 12 Feb 2009 05:51:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756637AbZBLKux (ORCPT ); Thu, 12 Feb 2009 05:50:53 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:41277 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754362AbZBLKuw (ORCPT ); Thu, 12 Feb 2009 05:50:52 -0500 Date: Thu, 12 Feb 2009 11:50:27 +0100 From: Ingo Molnar To: Frederic Weisbecker Cc: Thomas Gleixner , LKML , rt-users , Steven Rostedt , Peter Zijlstra , Carsten Emde , Clark Williams Subject: [patch] sched: cpu hotplug fix Message-ID: <20090212105027.GA12474@elte.hu> References: <20090212005032.GA4788@nowhere> <20090212021257.GB4697@nowhere> <20090212081801.GA22979@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090212081801.GA22979@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The fix below addresses a lockdep warning i triggered with your config. (You could hit this if you try to use s2ram or hibernation or explicit CPU hotplug ops.) Ingo --------------> Subject: sched: cpu hotplug fix From: Ingo Molnar Date: Thu Feb 12 11:35:40 CET 2009 rq_attach_root() does a kfree() with the runqueue lock held. That's not a very wise move, fix it. Signed-off-by: Ingo Molnar --- kernel/sched.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) Index: tip/kernel/sched.c =================================================================== --- tip.orig/kernel/sched.c +++ tip/kernel/sched.c @@ -7619,20 +7619,26 @@ static void free_rootdomain(struct root_ static void rq_attach_root(struct rq *rq, struct root_domain *rd) { + struct root_domain *old_rd = NULL; unsigned long flags; spin_lock_irqsave(&rq->lock, flags); if (rq->rd) { - struct root_domain *old_rd = rq->rd; + old_rd = rq->rd; if (cpumask_test_cpu(rq->cpu, old_rd->online)) set_rq_offline(rq); cpumask_clear_cpu(rq->cpu, old_rd->span); - if (atomic_dec_and_test(&old_rd->refcount)) - free_rootdomain(old_rd); + /* + * If we dont want to free the old_rt yet then + * set old_rd to NULL to skip the freeing later + * in this function: + */ + if (!atomic_dec_and_test(&old_rd->refcount)) + old_rd = NULL; } atomic_inc(&rd->refcount); @@ -7643,6 +7649,9 @@ static void rq_attach_root(struct rq *rq set_rq_online(rq); spin_unlock_irqrestore(&rq->lock, flags); + + if (old_rd) + free_rootdomain(old_rd); } static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)