Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763332Ab3ECSdI (ORCPT ); Fri, 3 May 2013 14:33:08 -0400 Received: from www.linutronix.de ([62.245.132.108]:46407 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759070Ab3ECSdH (ORCPT ); Fri, 3 May 2013 14:33:07 -0400 Date: Fri, 3 May 2013 20:32:58 +0200 (CEST) From: Thomas Gleixner To: Dave Jones cc: Yinghai Lu , Linux Kernel Subject: Re: clockevents_program_event WARN_ON preventing boot. In-Reply-To: <20130503144912.GB1283@redhat.com> Message-ID: References: <20130430212007.GB18598@redhat.com> <20130430213719.GA14988@redhat.com> <20130502154621.GA23990@redhat.com> <20130503144912.GB1283@redhat.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2837 Lines: 81 On Fri, 3 May 2013, Dave Jones wrote: > On Fri, May 03, 2013 at 12:49:20AM +0200, Thomas Gleixner wrote: > > > I'm fundamentally confused and Daves observation about slub debug does > > not make it less confusing. > > > > It'd be nice if you could add some more instrumentation or bisect the > > issue. > > Here's what I ended up with.. > b352bc1cbc29134a356b5c16ee2281807a7b984e is the first bad commit > commit b352bc1cbc29134a356b5c16ee2281807a7b984e > Author: Thomas Gleixner > Date: Tue Mar 5 14:25:32 2013 +0100 > > tick: Convert broadcast cpu bitmaps to cpumask_var_t > > Signed-off-by: Thomas Gleixner > Link: http://lkml.kernel.org/r/20130306111537.366394000@linutronix.de > Cc: Rusty Russell > I bet you have CONFIG_CPUMASK_OFFSTACK enabled. /me is a moron and rumages for a brown paperbag. Patch below. Thanks, tglx ------------> Subject: tick: Use zalloc_cpumask_var for allocating offstack cpumasks From: Thomas Gleixner Date: Fri, 03 May 2013 20:22:36 +0200 commit b352bc1cbc (tick: Convert broadcast cpu bitmaps to cpumask_var_t) broke CONFIG_CPUMASK_OFFSTACK in a very subtle way. Instead of allocating the cpumasks with zalloc_cpumask_var it uses alloc_cpumask_var, so we can get random data there, which of course confuses the logic completely and causes random failures. Reported-by: Dave Jones Reported-by: Yinghai Lu Signed-off-by: Thomas Gleixner --- kernel/time/tick-broadcast.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) Index: linux-2.6/kernel/time/tick-broadcast.c =================================================================== --- linux-2.6.orig/kernel/time/tick-broadcast.c +++ linux-2.6/kernel/time/tick-broadcast.c @@ -785,11 +785,11 @@ bool tick_broadcast_oneshot_available(vo void __init tick_broadcast_init(void) { - alloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT); - alloc_cpumask_var(&tmpmask, GFP_NOWAIT); + zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT); + zalloc_cpumask_var(&tmpmask, GFP_NOWAIT); #ifdef CONFIG_TICK_ONESHOT - alloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT); - alloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT); - alloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT); + zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT); + zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT); + zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT); #endif } -- 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/