From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754694Ab1AFAoT (ORCPT ); Wed, 5 Jan 2011 19:44:19 -0500 Received: from kroah.org ([198.145.64.141]:35872 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754354Ab1AFAad (ORCPT ); Wed, 5 Jan 2011 19:30:33 -0500 X-Mailbox-Line: From gregkh@clark.site Wed Jan 5 16:23:05 2011 Message-Id: <20110106002305.428923494@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 05 Jan 2011 16:23:10 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andreas Herrmann Subject: [091/152] x86, amd: Fix panic on AMD CPU family 0x15 In-Reply-To: <20110106002500.GA3172@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Andreas Herrmann [The mainline kernel doesn't have this problem. Commit "(23588c3) x86, amd: Add support for CPUID topology extension of AMD CPUs" removed the family check. But 2.6.32.y needs to be fixed.] This CPU family check is not required -- existence of the NodeId MSR is indicated by a CPUID feature flag which is already checked in amd_fixup_dcm() -- and it needlessly prevents amd_fixup_dcm() to be called for newer AMD CPUs. In worst case this can lead to a panic in the scheduler code for AMD family 0x15 multi-node AMD CPUs. I just have a picture of VGA console output so I can't copy-and-paste it herein, but the call stack of such a panic looked like: do_divide_error ... find_busiest_group run_rebalance_domains ... apic_timer_interrupt ... cpu_idle The mainline kernel doesn't have this problem. Commit "(23588c3) x86, amd: Add support for CPUID topology extension of AMD CPUs" removed the family check. But 2.6.32.y needs to be fixed. Signed-off-by: Andreas Herrmann Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/amd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -305,8 +305,7 @@ static void __cpuinit amd_detect_cmp(str /* use socket ID also for last level cache */ per_cpu(cpu_llc_id, cpu) = c->phys_proc_id; /* fixup topology information on multi-node processors */ - if ((c->x86 == 0x10) && (c->x86_model == 9)) - amd_fixup_dcm(c); + amd_fixup_dcm(c); #endif }