Re: [PATCH v4 04/17] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access

[Dave Hansen]

On 3/1/19 6:44 PM, Fenghua Yu wrote:
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 33051436c864..eb8ae701ef65 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -93,7 +93,9 @@ struct cpuinfo_x86 {
>  	__u32			extended_cpuid_level;
>  	/* Maximum supported CPUID level, -1=no CPUID: */
>  	int			cpuid_level;
> -	__u32			x86_capability[NCAPINTS + NBUGINTS];
> +	/* Unsigned long alignment to avoid split lock in atomic bitmap ops */
> +	__u32			x86_capability[NCAPINTS + NBUGINTS]
> +				__aligned(sizeof(unsigned long));

I think this also warrants a comment in the changelog about the
alignment of 'struct cpuinfo_x86'.