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Commit e1409c32 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
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mm/compaction: pass only pageblock aligned range to pageblock_pfn_to_page 



pageblock_pfn_to_page() is used to check there is valid pfn and all
pages in the pageblock is in a single zone.  If there is a hole in the
pageblock, passing arbitrary position to pageblock_pfn_to_page() could
cause to skip whole pageblock scanning, instead of just skipping the
hole page.  For deterministic behaviour, it's better to always pass
pageblock aligned range to pageblock_pfn_to_page().  It will also help
further optimization on pageblock_pfn_to_page() in the following patch.

Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 623446e4

mm/compaction.c

+30 −11
Original line number Diff line number Diff line
@@ -555,13 +555,17 @@ unsigned long 
isolate_freepages_range(struct compact_control *cc,

			unsigned long start_pfn, unsigned long end_pfn)

{

	unsigned long isolated, pfn, block_end_pfn;

	unsigned long isolated, pfn, block_start_pfn, block_end_pfn;

	LIST_HEAD(freelist);



	pfn = start_pfn;

	block_start_pfn = pfn & ~(pageblock_nr_pages - 1);

	if (block_start_pfn < cc->zone->zone_start_pfn)

		block_start_pfn = cc->zone->zone_start_pfn;

	block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);



	for (; pfn < end_pfn; pfn += isolated,

				block_start_pfn = block_end_pfn,

				block_end_pfn += pageblock_nr_pages) {

		/* Protect pfn from changing by isolate_freepages_block */

		unsigned long isolate_start_pfn = pfn;
@@ -574,11 +578,13 @@ isolate_freepages_range(struct compact_control *cc, 
		 * scanning range to right one.

		 */

		if (pfn >= block_end_pfn) {

			block_start_pfn = pfn & ~(pageblock_nr_pages - 1);

			block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);

			block_end_pfn = min(block_end_pfn, end_pfn);

		}



		if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))

		if (!pageblock_pfn_to_page(block_start_pfn,

					block_end_pfn, cc->zone))

			break;



		isolated = isolate_freepages_block(cc, &isolate_start_pfn,
@@ -864,18 +870,23 @@ unsigned long 
isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,

							unsigned long end_pfn)

{

	unsigned long pfn, block_end_pfn;

	unsigned long pfn, block_start_pfn, block_end_pfn;



	/* Scan block by block. First and last block may be incomplete */

	pfn = start_pfn;

	block_start_pfn = pfn & ~(pageblock_nr_pages - 1);

	if (block_start_pfn < cc->zone->zone_start_pfn)

		block_start_pfn = cc->zone->zone_start_pfn;

	block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);



	for (; pfn < end_pfn; pfn = block_end_pfn,

				block_start_pfn = block_end_pfn,

				block_end_pfn += pageblock_nr_pages) {



		block_end_pfn = min(block_end_pfn, end_pfn);



		if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))

		if (!pageblock_pfn_to_page(block_start_pfn,

					block_end_pfn, cc->zone))

			continue;



		pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
@@ -1104,7 +1115,9 @@ int sysctl_compact_unevictable_allowed __read_mostly = 1; 
static isolate_migrate_t isolate_migratepages(struct zone *zone,

					struct compact_control *cc)

{

	unsigned long low_pfn, end_pfn;

	unsigned long block_start_pfn;

	unsigned long block_end_pfn;

	unsigned long low_pfn;

	unsigned long isolate_start_pfn;

	struct page *page;

	const isolate_mode_t isolate_mode =
@@ -1116,16 +1129,21 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, 
	 * initialized by compact_zone()

	 */

	low_pfn = cc->migrate_pfn;

	block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1);

	if (block_start_pfn < zone->zone_start_pfn)

		block_start_pfn = zone->zone_start_pfn;



	/* Only scan within a pageblock boundary */

	end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);

	block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);



	/*

	 * Iterate over whole pageblocks until we find the first suitable.

	 * Do not cross the free scanner.

	 */

	for (; end_pfn <= cc->free_pfn;

			low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {

	for (; block_end_pfn <= cc->free_pfn;

			low_pfn = block_end_pfn,

			block_start_pfn = block_end_pfn,

			block_end_pfn += pageblock_nr_pages) {



		/*

		 * This can potentially iterate a massively long zone with
@@ -1136,7 +1154,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, 
						&& compact_should_abort(cc))

			break;



		page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);

		page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,

									zone);

		if (!page)

			continue;
@@ -1155,8 +1174,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, 


		/* Perform the isolation */

		isolate_start_pfn = low_pfn;

		low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,

								isolate_mode);

		low_pfn = isolate_migratepages_block(cc, low_pfn,

						block_end_pfn, isolate_mode);



		if (!low_pfn || cc->contended) {

			acct_isolated(zone, cc);