Re: [PATCH 4/8] mm: Improve comment on page->mapping

[Michal Hocko <mhocko@kernel.org>]

On Sat 16-12-17 08:44:21, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
> 
> The comment on page->mapping is terse, and out of date (it does not
> mention the possibility of PAGE_MAPPING_MOVABLE).  Instead, point
> the interested reader to page-flags.h where there is a much better
> comment.
> 
> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>

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

> ---
>  include/linux/mm_types.h | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index c2294e6204e8..8c3b8cea22ee 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -50,15 +50,9 @@ struct page {
>  	unsigned long flags;		/* Atomic flags, some possibly
>  					 * updated asynchronously */
>  	union {
> -		struct address_space *mapping;	/* If low bit clear, points to
> -						 * inode address_space, or NULL.
> -						 * If page mapped as anonymous
> -						 * memory, low bit is set, and
> -						 * it points to anon_vma object
> -						 * or KSM private structure. See
> -						 * PAGE_MAPPING_ANON and
> -						 * PAGE_MAPPING_KSM.
> -						 */
> +		/* See page-flags.h for the definition of PAGE_MAPPING_FLAGS */
> +		struct address_space *mapping;
> +
>  		void *s_mem;			/* slab first object */
>  		atomic_t compound_mapcount;	/* first tail page */
>  		/* page_deferred_list().next	 -- second tail page */
> -- 
> 2.15.1
> 
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-- 
Michal Hocko
SUSE Labs

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