From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754306Ab1FNWhZ (ORCPT ); Tue, 14 Jun 2011 18:37:25 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:41997 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753926Ab1FNWhA (ORCPT ); Tue, 14 Jun 2011 18:37:00 -0400 X-Authority-Analysis: v=1.1 cv=5asQ6euaRPJxDdFxwvXsn6JDb7fmFbz8qWDLMfa45gU= c=1 sm=0 a=vhdKIqpQuCYA:10 a=i4oitjsSMAcA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=JfrnYn6hAAAA:8 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=ayC55rCoAAAA:8 a=DGGDpp8ivC0nh92LMBIA:9 a=jeBq3FmKZ4MA:10 a=3Rfx1nUSh_UA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Message-Id: <20110614223657.824872966@goodmis.org> User-Agent: quilt/0.48-1 Date: Tue, 14 Jun 2011 18:36:25 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Peter Zijlstra , Paul McKenney , Andrew Theurer Subject: [PATCH 2/2] sched: Check if lowest_mask is initialized in find_lowest_rq References: <20110614223623.876681637@goodmis.org> Content-Disposition: inline; filename=0002-sched-Check-if-lowest_mask-is-initialized-in-find_lo.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt On system boot up, the lowest_mask is initialized with early_initcall. But RT tasks may wake up on other early_initcall callers before the lowest_mask is initialized, causing a system crash. The 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. Cc: Peter Zijlstra Cc: Paul McKenney Reported-by: Andrew Theurer Tested-by: Andrew Theurer Link: http://lkml.kernel.org/r/1308014683.9218.107.camel@gandalf.stny.rr.com Signed-off-by: Steven Rostedt --- 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 */ -- 1.7.4.4