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| author | Vlastimil Babka <vbabka@suse.cz> | 2017-02-22 15:41:51 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-22 16:41:27 -0800 |
| commit | 13ad59df67f19788f6c22985b1a33e466eceb643 (patch) | |
| tree | 98644ed581610f3af1d52f01963627e94317f2cd /mm/page_alloc.c | |
| parent | 76741e776a37973a3e398d504069b3e55c5cc866 (diff) | |
| download | lwn-13ad59df67f19788f6c22985b1a33e466eceb643.tar.gz lwn-13ad59df67f19788f6c22985b1a33e466eceb643.zip | |
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>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 49d40261f8c4..af65c4eedc79 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -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 @@ continue_merging: 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 @@ done_merging: * 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); |