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Commit 13ad59df authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Linus Torvalds
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mm, page_alloc: avoid page_to_pfn() when merging buddies 

On architectures that allow memory holes, page_is_buddy() has to perform
page_to_pfn() to check for the memory hole.  After the previous patch,
we have the pfn already available in __free_one_page(), which is the
only caller of page_is_buddy(), so move the check there and avoid
page_to_pfn().

Link: http://lkml.kernel.org/r/20161216120009.20064-2-vbabka@suse.cz


Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarMel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 76741e77

mm/page_alloc.c

+5 −5
Original line number Diff line number Diff line
@@ -714,7 +714,7 @@ static inline void rmv_page_order(struct page *page) 
/*

 * This function checks whether a page is free && is the buddy

 * we can do coalesce a page and its buddy if

 * (a) the buddy is not in a hole &&

 * (a) the buddy is not in a hole (check before calling!) &&

 * (b) the buddy is in the buddy system &&

 * (c) a page and its buddy have the same order &&

 * (d) a page and its buddy are in the same zone.
@@ -729,9 +729,6 @@ static inline void rmv_page_order(struct page *page) 
static inline int page_is_buddy(struct page *page, struct page *buddy,

							unsigned int order)

{

	if (!pfn_valid_within(page_to_pfn(buddy)))

		return 0;



	if (page_is_guard(buddy) && page_order(buddy) == order) {

		if (page_zone_id(page) != page_zone_id(buddy))

			return 0;
@@ -808,6 +805,9 @@ static inline void __free_one_page(struct page *page, 
	while (order < max_order - 1) {

		buddy_pfn = __find_buddy_pfn(pfn, order);

		buddy = page + (buddy_pfn - pfn);



		if (!pfn_valid_within(buddy_pfn))

			goto done_merging;

		if (!page_is_buddy(page, buddy, order))

			goto done_merging;

		/*
@@ -862,7 +862,7 @@ static inline void __free_one_page(struct page *page, 
	 * so it's less likely to be used soon and more likely to be merged

	 * as a higher order page

	 */

	if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) {

	if ((order < MAX_ORDER-2) && pfn_valid_within(buddy_pfn)) {

		struct page *higher_page, *higher_buddy;

		combined_pfn = buddy_pfn & pfn;

		higher_page = page + (combined_pfn - pfn);

mm/page_isolation.c

+1 −1
Original line number Diff line number Diff line
@@ -106,7 +106,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) 
			buddy_pfn = __find_buddy_pfn(pfn, order);

			buddy = page + (buddy_pfn - pfn);



			if (pfn_valid_within(page_to_pfn(buddy)) &&

			if (pfn_valid_within(buddy_pfn) &&

			    !is_migrate_isolate_page(buddy)) {

				__isolate_free_page(page, order);

				isolated_page = true;