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Commit c361be55 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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Move free pages between lists on steal 



When a fallback occurs, there will be free pages for one allocation type
stored on the list for another.  When a large steal occurs, this patch will
move all the free pages within one list to the other.

[y-goto@jp.fujitsu.com: fix BUG_ON check at move_freepages()]
[apw@shadowen.org: Move to using pfn_valid_within()]
Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: default avatarYasunori Goto <y-goto@jp.fujitsu.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: default avatarAndy Whitcroft <andyw@uk.ibm.com>
Cc: Bob Picco <bob.picco@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e2c55dc8

mm/page_alloc.c

+71 −3
Original line number Diff line number Diff line
@@ -680,6 +680,72 @@ static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = { 
	[MIGRATE_MOVABLE]   = { MIGRATE_UNMOVABLE },

};



/*

 * Move the free pages in a range to the free lists of the requested type.

 * Note that start_page and end_pages are not aligned in a MAX_ORDER_NR_PAGES

 * boundary. If alignment is required, use move_freepages_block()

 */

int move_freepages(struct zone *zone,

			struct page *start_page, struct page *end_page,

			int migratetype)

{

	struct page *page;

	unsigned long order;

	int blocks_moved = 0;



#ifndef CONFIG_HOLES_IN_ZONE

	/*

	 * page_zone is not safe to call in this context when

	 * CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant

	 * anyway as we check zone boundaries in move_freepages_block().

	 * Remove at a later date when no bug reports exist related to

	 * CONFIG_PAGE_GROUP_BY_MOBILITY

	 */

	BUG_ON(page_zone(start_page) != page_zone(end_page));

#endif



	for (page = start_page; page <= end_page;) {

		if (!pfn_valid_within(page_to_pfn(page))) {

			page++;

			continue;

		}



		if (!PageBuddy(page)) {

			page++;

			continue;

		}



		order = page_order(page);

		list_del(&page->lru);

		list_add(&page->lru,

			&zone->free_area[order].free_list[migratetype]);

		page += 1 << order;

		blocks_moved++;

	}



	return blocks_moved;

}



int move_freepages_block(struct zone *zone, struct page *page, int migratetype)

{

	unsigned long start_pfn, end_pfn;

	struct page *start_page, *end_page;



	start_pfn = page_to_pfn(page);

	start_pfn = start_pfn & ~(MAX_ORDER_NR_PAGES-1);

	start_page = pfn_to_page(start_pfn);

	end_page = start_page + MAX_ORDER_NR_PAGES - 1;

	end_pfn = start_pfn + MAX_ORDER_NR_PAGES - 1;



	/* Do not cross zone boundaries */

	if (start_pfn < zone->zone_start_pfn)

		start_page = page;

	if (end_pfn >= zone->zone_start_pfn + zone->spanned_pages)

		return 0;



	return move_freepages(zone, start_page, end_page, migratetype);

}



/* Remove an element from the buddy allocator from the fallback list */

static struct page *__rmqueue_fallback(struct zone *zone, int order,

						int start_migratetype)
@@ -704,11 +770,13 @@ static struct page *__rmqueue_fallback(struct zone *zone, int order, 
			area->nr_free--;



			/*

			 * If breaking a large block of pages, place the buddies

			 * on the preferred allocation list

			 * If breaking a large block of pages, move all free

			 * pages to the preferred allocation list

			 */

			if (unlikely(current_order >= MAX_ORDER / 2))

			if (unlikely(current_order >= MAX_ORDER / 2)) {

				migratetype = start_migratetype;

				move_freepages_block(zone, page, migratetype);

			}



			/* Remove the page from the freelists */

			list_del(&page->lru);