From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754613Ab1FOJv1 (ORCPT ); Wed, 15 Jun 2011 05:51:27 -0400 Received: from hera.kernel.org ([140.211.167.34]:55139 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754138Ab1FOJvZ (ORCPT ); Wed, 15 Jun 2011 05:51:25 -0400 Date: Wed, 15 Jun 2011 09:50:50 GMT From: tip-bot for Steven Rostedt Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, rostedt@goodmis.org, habanero@linux.vnet.ibm.com, tglx@linutronix.de, mingo@elte.hu Reply-To: paulmck@linux.vnet.ibm.com, mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, habanero@linux.vnet.ibm.com, rostedt@goodmis.org, peterz@infradead.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20110614223657.824872966@goodmis.org> References: <20110614223657.824872966@goodmis.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Check if lowest_mask is initialized in find_lowest_rq() Git-Commit-ID: 0da938c44921cfb690283d3b0c9c48a10375db2c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 15 Jun 2011 09:50:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 0da938c44921cfb690283d3b0c9c48a10375db2c Gitweb: http://git.kernel.org/tip/0da938c44921cfb690283d3b0c9c48a10375db2c Author: Steven Rostedt AuthorDate: Tue, 14 Jun 2011 18:36:25 -0400 Committer: Ingo Molnar CommitDate: Wed, 15 Jun 2011 11:44:48 +0200 sched: Check if lowest_mask is initialized in find_lowest_rq() On system boot up, the lowest_mask is initialized with an early_initcall(). But RT tasks may wake up on other early_initcall() callers before the lowest_mask is initialized, causing a system crash. Commit "d72bce0e67 rcu: Cure load woes" was the first commit to wake up RT tasks in early init. Before this commit this bug should not happen. Reported-by: Andrew Theurer Tested-by: Andrew Theurer Tested-by: Paul E. McKenney Signed-off-by: Steven Rostedt Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20110614223657.824872966@goodmis.org Signed-off-by: Ingo Molnar --- kernel/sched_rt.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 9b8d5dc..10d0182 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1239,6 +1239,10 @@ static int find_lowest_rq(struct task_struct *task) int this_cpu = smp_processor_id(); int cpu = task_cpu(task); + /* Make sure the mask is initialized first */ + if (unlikely(!lowest_mask)) + return -1; + if (task->rt.nr_cpus_allowed == 1) return -1; /* No other targets possible */