Messages in this thread | | | Date | Sun, 12 Feb 2012 12:19:15 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86: Move per cpu cpu_llc_shared_map to a field in struct cpuinfo_x86 |
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* Kevin Winchester <kjwinchester@gmail.com> wrote:
> On 11 February 2012 20:24, Kevin Winchester <kjwinchester@gmail.com> wrote: > > Commit 141168c36cde ("x86: Simplify code by removing a !SMP #ifdefs from > > 'struct cpuinfo_x86'") caused the compilation error: > > > > mce_amd.c:(.cpuinit.text+0x4723): undefined reference to 'cpu_llc_shared_map' > > > > by removing an #ifdef CONFIG_SMP around a block containing a reference > > to cpu_llc_shared_map. Rather than replace the #ifdef, move > > cpu_llc_shared_map to be a new field llc_shared_map in struct > > cpuinfo_x86 and adjust all references to cpu_llc_shared_map. > > > > Signed-off-by: Kevin Winchester <kjwinchester@gmail.com> > > --- > > arch/x86/include/asm/processor.h | 1 + > > arch/x86/include/asm/smp.h | 6 ------ > > arch/x86/kernel/cpu/intel_cacheinfo.c | 4 ++-- > > arch/x86/kernel/cpu/mcheck/mce_amd.c | 7 ++++--- > > arch/x86/kernel/smpboot.c | 15 ++++++--------- > > arch/x86/xen/smp.c | 1 - > > 6 files changed, 13 insertions(+), 21 deletions(-) > > > > > > static void impress_friends(void) > > @@ -1053,7 +1051,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) > > for_each_possible_cpu(i) { > > zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL); > > zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL); > > - zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL); > > } > > set_cpu_sibling_map(0); > > > > diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c > > index 041d4fe..a898ed5 100644 > > --- a/arch/x86/xen/smp.c > > +++ b/arch/x86/xen/smp.c > > @@ -225,7 +225,6 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus) > > for_each_possible_cpu(i) { > > zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL); > > zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL); > > - zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL); > > } > > set_cpu_sibling_map(0); > > > > I just realized that I took out a couple of allocations here > for cpu_llc_shared_map, without replacing them. Am I leaving > cpuinfo_x86.llc_shared_map unallocated then, and just writing > to whatever address that field happened to get?
That will probably crash CONFIG_CPUMASK_OFFSTACK=y kernels.
The simplest approach would be to use a cpumask_t (i.e. not a variable cpumask_var_t one), on the [valid looking] assumption that cpuinfo_x86 gets allocated in sane ways - i.e. never on the kernel stack and such.
The before/after vmlinux 'size' result should be inspected, with NR_CPUs set to 4096 and OFFSTACK activated in the .config, to see how bad the size effect is - but I think it should not be too bad.
Thanks,
Ingo -- 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/
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