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

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Message-ID: <20160628081731.GC19731@js1304-P5Q-DELUXE>
Date:	Tue, 28 Jun 2016 17:17:31 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	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
Subject: Re: [PATCH v3 5/6] mm/cma: remove MIGRATE_CMA

On Mon, Jun 27, 2016 at 11:46:39AM +0200, Vlastimil Babka wrote:
> 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.

Okay.

> 
> >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.

You're right. Will do in next spin.

Thanks.