Re: [PATCH 1/8] mm: Align struct page more aesthetically

[Michal Hocko <mhocko@kernel.org>]

On Sat 16-12-17 08:44:18, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
> 
> instead of an ifdef block at the end of the struct, which needed
> its own comment, define _struct_page_alignment up at the top where it
> fits nicely with the existing comment.
> 
> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/mm_types.h | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index cfd0ac4e5e0e..4509f0cfaf39 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -39,6 +39,12 @@ struct hmm;
>   * allows the use of atomic double word operations on the flags/mapping
>   * and lru list pointers also.
>   */
> +#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
> +#define _struct_page_alignment	__aligned(2 * sizeof(unsigned long))
> +#else
> +#define _struct_page_alignment
> +#endif
> +
>  struct page {
>  	/* First double word block */
>  	unsigned long flags;		/* Atomic flags, some possibly
> @@ -212,15 +218,7 @@ struct page {
>  #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
>  	int _last_cpupid;
>  #endif
> -}
> -/*
> - * The struct page can be forced to be double word aligned so that atomic ops
> - * on double words work. The SLUB allocator can make use of such a feature.
> - */
> -#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
> -	__aligned(2 * sizeof(unsigned long))
> -#endif
> -;
> +} _struct_page_alignment;
>  
>  #define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
>  #define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)
> -- 
> 2.15.1
> 
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-- 
Michal Hocko
SUSE Labs

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