linux-kernel - Re: [PATCH v3 5/6] mm/cma: remove MIGRATE

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Message-ID: <087368b2-19d3-30e0-e420-456c291f16c9@suse.cz>
Date:	Mon, 27 Jun 2016 11:46:39 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	js1304@...il.com, Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	mgorman@...hsingularity.net, Laura Abbott <lauraa@...eaurora.org>,
	Minchan Kim <minchan@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Rui Teng <rui.teng@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v3 5/6] mm/cma: remove MIGRATE_CMA

On 05/26/2016 08:22 AM, js1304@...il.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
>
> 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@....com>

[...]

> @@ -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.