Re: [PATCH v3 5/6] mm/cma: remove MIGRATE_CMA

[Vlastimil Babka]

On 05/26/2016 08:22 AM, js1304@xxxxxxxxx wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> Now, all reserved pages for CMA region are belong to the ZONE_CMA
> and there is no other type of pages. Therefore, we don't need to
> use MIGRATE_CMA to distinguish and handle differently for CMA pages
> and ordinary pages. Remove MIGRATE_CMA.
>
> Unfortunately, this patch make free CMA counter incorrect because
> we count it when pages are on the MIGRATE_CMA. It will be fixed
> by next patch. I can squash next patch here but it makes changes
> complicated and hard to review so I separate that.

Doesn't sound like a big deal.

> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

[...]

> @@ -7442,14 +7401,14 @@ int alloc_contig_range(unsigned long start, unsigned long end,
>  	 * allocator removing them from the buddy system.  This way
>  	 * page allocator will never consider using them.
>  	 *
> -	 * This lets us mark the pageblocks back as
> -	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
> -	 * aligned range but not in the unaligned, original range are
> -	 * put back to page allocator so that buddy can use them.
> +	 * This lets us mark the pageblocks back as MIGRATE_MOVABLE
> +	 * so that free pages in the aligned range but not in the
> +	 * unaligned, original range are put back to page allocator
> +	 * so that buddy can use them.
>  	 */
>
>  	ret = start_isolate_page_range(pfn_max_align_down(start),
> -				       pfn_max_align_up(end), migratetype,
> +				       pfn_max_align_up(end), MIGRATE_MOVABLE,
>  				       false);
>  	if (ret)
>  		return ret;
> @@ -7528,7 +7487,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
>
>  done:
>  	undo_isolate_page_range(pfn_max_align_down(start),
> -				pfn_max_align_up(end), migratetype);
> +				pfn_max_align_up(end), MIGRATE_MOVABLE);
>  	return ret;
>  }

Looks like all callers of {start,undo}_isolate_page_range() now use 
MIGRATE_MOVABLE, so it could be removed.