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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: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vlastimil Babka 2017-02-22 15:41:51 -08:00 committed by Linus Torvalds
parent 76741e776a
commit 13ad59df67
2 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
mm/page_alloc.c
View File

@ -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);

2
mm/page_isolation.c
View File

@ -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;