From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266AbZDUGd6 (ORCPT ); Tue, 21 Apr 2009 02:33:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751124AbZDUGdt (ORCPT ); Tue, 21 Apr 2009 02:33:49 -0400 Received: from ozlabs.org ([203.10.76.45]:39496 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750919AbZDUGdt (ORCPT ); Tue, 21 Apr 2009 02:33:49 -0400 From: Rusty Russell To: Steven Rostedt Subject: [PATCH] x86: avoid theoretical spurious NMI backtraces with CONFIG_CPUMASK_OFFSTACK=y Date: Tue, 21 Apr 2009 16:03:41 +0930 User-Agent: KMail/1.11.2 (Linux/2.6.28-11-generic; KDE/4.2.2; i686; ; ) Cc: LKML , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner References: <200904211600.16348.rusty@rustcorp.com.au> In-Reply-To: <200904211600.16348.rusty@rustcorp.com.au> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904211603.41980.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In theory (though not shown in practice) alloc_cpumask_var() doesn't zero memory, so CPUs might print an "NMI backtrace for cpu %d" once on boot. (Bug introduced in fcef8576d8a64fc603e719c97d423f9f6d4e0e8b). Signed-off-by: Rusty Russell --- arch/x86/kernel/apic/nmi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c --- a/arch/x86/kernel/apic/nmi.c +++ b/arch/x86/kernel/apic/nmi.c @@ -138,7 +138,7 @@ int __init check_nmi_watchdog(void) if (!prev_nmi_count) goto error; - alloc_cpumask_var(&backtrace_mask, GFP_KERNEL); + alloc_cpumask_var(&backtrace_mask, GFP_KERNEL|__GFP_ZERO); printk(KERN_INFO "Testing NMI watchdog ... "); #ifdef CONFIG_SMP