From: Rusty Russell <rusty@rustcorp.com.au>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH] x86: avoid theoretical spurious NMI backtraces with CONFIG_CPUMASK_OFFSTACK=y
Date: Tue, 21 Apr 2009 16:03:41 +0930 [thread overview]
Message-ID: <200904211603.41980.rusty@rustcorp.com.au> (raw)
In-Reply-To: <200904211600.16348.rusty@rustcorp.com.au>
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 <rusty@rustcorp.com.au>
---
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
next prev parent reply other threads:[~2009-04-21 6:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-21 1:35 [BUG] NULL pointer crash in early NMI handler Steven Rostedt
2009-04-21 6:30 ` [PATCH] x86: fix boot crash in NMI watchdog with CONFIG_CPUMASK_OFFSTACK=y and flat APIC Rusty Russell
2009-04-21 6:33 ` Rusty Russell [this message]
2009-04-21 8:12 ` [tip:x86/urgent] " tip-bot for Rusty Russell
2009-04-21 8:12 ` [tip:x86/urgent] x86: avoid theoretical spurious NMI backtraces with CONFIG_CPUMASK_OFFSTACK=y tip-bot for Rusty Russell
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