From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756946AbZLISgq (ORCPT ); Wed, 9 Dec 2009 13:36:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756922AbZLISgo (ORCPT ); Wed, 9 Dec 2009 13:36:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49701 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756542AbZLISgk (ORCPT ); Wed, 9 Dec 2009 13:36:40 -0500 Date: Wed, 9 Dec 2009 13:36:45 -0500 From: Prarit Bhargava To: linux-kernel@vger.kernel.org, andreas.herrmann3@amd.com, bhavna.sarathy@amd.com, mingo@redhat.com Cc: Prarit Bhargava Message-Id: <20091209183336.17855.98708.sendpatchset@prarit.bos.redhat.com> Subject: [PATCH]: AMD cache - Fix stale data in shared_cpu_map cpumasks Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The per_cpu cpuid4_info shared_map can contain stale data when CPUs are added and removed. The stale data can lead to a NULL pointer derefernce panic on a remove of a CPU that has had siblings previously removed. This patch resolves the panic by verifying a cpu is actually online before adding it to the shared_cpu_map, only examining cpus that are part of the same lower level cache, and by updating other siblings lowest level cache maps when a cpu is added. Signed-off-by: Prarit Bhargava diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index 0df4c2b..70df1e4 100644 --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -504,18 +504,19 @@ static void __cpuinit cache_shared_cpu_map_setup(unsigned int cpu, int index) { struct _cpuid4_info *this_leaf, *sibling_leaf; unsigned long num_threads_sharing; - int index_msb, i; + int index_msb, i, sibling; struct cpuinfo_x86 *c = &cpu_data(cpu); if ((index == 3) && (c->x86_vendor == X86_VENDOR_AMD)) { - struct cpuinfo_x86 *d; - for_each_online_cpu(i) { + for_each_cpu(i, c->llc_shared_map) { if (!per_cpu(cpuid4_info, i)) continue; - d = &cpu_data(i); this_leaf = CPUID4_INFO_IDX(i, index); - cpumask_copy(to_cpumask(this_leaf->shared_cpu_map), - d->llc_shared_map); + for_each_cpu(sibling, c->llc_shared_map) { + if (!cpu_online(sibling)) + continue; + set_bit(sibling, this_leaf->shared_cpu_map); + } } return; }