Messages in this thread Patch in this message |  | | | Date | Mon, 10 May 2010 15:34:59 -0700 | | From | Greg KH <> | | Subject | [47/98] x86, AMD: Fix stale cpuid4_info shared_map data in shared_cpu_map cpumasks |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
------------------ From: Prarit Bhargava <prarit@redhat.com>
commit ebb682f522411abbe358059a256a8672ec0bd55b upstream.
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 <prarit@redhat.com> LKML-Reference: <20091209183336.17855.98708.sendpatchset@prarit.bos.redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/kernel/cpu/intel_cacheinfo.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -647,18 +647,19 @@ static void __cpuinit cache_shared_cpu_m { 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; }
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