Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758274Ab0KAPvR (ORCPT ); Mon, 1 Nov 2010 11:51:17 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:64918 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758155Ab0KAPvP (ORCPT ); Mon, 1 Nov 2010 11:51:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=x4LoTWSuNniz9Qpi9Ucnd8lPDzV50atL2e+rRNsUci5vf8QI8q4NrXMtL2zU15zKvz BDTFLx6NkIgK5EVvnn/kMEjXQjq6R9cCdBzb2PqybEDquUjFZUD2Xc3D8/SXhH39oA2Z lxzyV9IpL6IicGkuhK/EPSXlVneJwtTlAt+zQ= Date: Mon, 1 Nov 2010 18:51:10 +0300 From: Cyrill Gorcunov To: Don Zickus Cc: Jan Kiszka , Ingo Molnar , Peter Zijlstra , Eric Paris , Randy Dunlap , Frederic Weisbecker , Linux Kernel Mailing List Subject: Re: BUG: using smp_processor_id() in preemptible arch_trigger_all_cpu_backtrace_handler Message-ID: <20101101155110.GC5985@lenovo> References: <4CCEB51C.7010901@web.de> <20101101154536.GT4823@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101101154536.GT4823@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 43 On Mon, Nov 01, 2010 at 11:45:36AM -0400, Don Zickus wrote: ... > Heh. Yeah when I migrated the code, I completely forgot the notifier > chain could be called from a preemptible context (ie not NMI). > > This patch should fix it and I think it is the correct fix. Let me know > how it works out. > > Cheers, > Don > > diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c > index c7c9ae4..1bdd0b5 100644 > --- a/arch/x86/kernel/apic/hw_nmi.c > +++ b/arch/x86/kernel/apic/hw_nmi.c > @@ -63,7 +63,7 @@ arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self, > { > struct die_args *args = __args; > struct pt_regs *regs; > - int cpu = smp_processor_id(); > + int cpu; > > switch (cmd) { > case DIE_NMI: > @@ -74,6 +74,7 @@ arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self, > } > > regs = args->regs; > + cpu = smp_processor_id(); > > if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { > static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED; > yup, this will do the trick for a while. In general I believe we might have kind of NMI exclusive chain so we wouldn't need the 'case:'s. Cyrill -- 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/