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Commit 66c64223 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
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mm/compaction: split freepages without holding the zone lock 

We don't need to split freepages with holding the zone lock.  It will
cause more contention on zone lock so not desirable.

[rientjes@google.com: if __isolate_free_page() fails, avoid adding to freelist so we don't call map_pages() with it]
  Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211447001.43430@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com


Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3b1d9ca6

include/linux/mm.h

+0 −1
Original line number Diff line number Diff line
@@ -537,7 +537,6 @@ void __put_page(struct page *page); 
void put_pages_list(struct list_head *pages);



void split_page(struct page *page, unsigned int order);

int split_free_page(struct page *page);



/*

 * Compound pages have a destructor function.  Provide a

mm/compaction.c

+33 −14
Original line number Diff line number Diff line
@@ -64,15 +64,33 @@ static unsigned long release_freepages(struct list_head *freelist) 


static void map_pages(struct list_head *list)

{

	struct page *page;

	unsigned int i, order, nr_pages;

	struct page *page, *next;

	LIST_HEAD(tmp_list);



	list_for_each_entry_safe(page, next, list, lru) {

		list_del(&page->lru);



	list_for_each_entry(page, list, lru) {

		arch_alloc_page(page, 0);

		kernel_map_pages(page, 1, 1);

		kasan_alloc_pages(page, 0);

		order = page_private(page);

		nr_pages = 1 << order;

		set_page_private(page, 0);

		set_page_refcounted(page);



		arch_alloc_page(page, order);

		kernel_map_pages(page, nr_pages, 1);

		kasan_alloc_pages(page, order);

		if (order)

			split_page(page, order);



		for (i = 0; i < nr_pages; i++) {

			list_add(&page->lru, &tmp_list);

			page++;

		}

	}



	list_splice(&tmp_list, list);

}



static inline bool migrate_async_suitable(int migratetype)

{

	return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
@@ -405,12 +423,13 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, 
	unsigned long flags = 0;

	bool locked = false;

	unsigned long blockpfn = *start_pfn;

	unsigned int order;



	cursor = pfn_to_page(blockpfn);



	/* Isolate free pages. */

	for (; blockpfn < end_pfn; blockpfn++, cursor++) {

		int isolated, i;

		int isolated;

		struct page *page = cursor;



		/*
@@ -476,17 +495,17 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, 
				goto isolate_fail;

		}



		/* Found a free page, break it into order-0 pages */

		isolated = split_free_page(page);

		/* Found a free page, will break it into order-0 pages */

		order = page_order(page);

		isolated = __isolate_free_page(page, order);

		if (!isolated)

			break;

		set_page_private(page, order);



		total_isolated += isolated;

		cc->nr_freepages += isolated;

		for (i = 0; i < isolated; i++) {

			list_add(&page->lru, freelist);

			page++;

		}

		list_add_tail(&page->lru, freelist);



		if (!strict && cc->nr_migratepages <= cc->nr_freepages) {

			blockpfn += isolated;

			break;
@@ -605,7 +624,7 @@ isolate_freepages_range(struct compact_control *cc, 
		 */

	}



	/* split_free_page does not map the pages */

	/* __isolate_free_page() does not map the pages */

	map_pages(&freelist);



	if (pfn < end_pfn) {
@@ -1102,7 +1121,7 @@ static void isolate_freepages(struct compact_control *cc) 
		}

	}



	/* split_free_page does not map the pages */

	/* __isolate_free_page() does not map the pages */

	map_pages(freelist);



	/*

mm/page_alloc.c

+0 −27
Original line number Diff line number Diff line
@@ -2526,33 +2526,6 @@ int __isolate_free_page(struct page *page, unsigned int order) 
	return 1UL << order;

}



/*

 * Similar to split_page except the page is already free. As this is only

 * being used for migration, the migratetype of the block also changes.

 * As this is called with interrupts disabled, the caller is responsible

 * for calling arch_alloc_page() and kernel_map_page() after interrupts

 * are enabled.

 *

 * Note: this is probably too low level an operation for use in drivers.

 * Please consult with lkml before using this in your driver.

 */

int split_free_page(struct page *page)

{

	unsigned int order;

	int nr_pages;



	order = page_order(page);



	nr_pages = __isolate_free_page(page, order);

	if (!nr_pages)

		return 0;



	/* Split into individual pages */

	set_page_refcounted(page);

	split_page(page, order);

	return nr_pages;

}



/*

 * Update NUMA hit/miss statistics

 *