From: Vlastimil Babka <vbabka@xxxxxxx> Subject: 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@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 10 +++++----- mm/page_isolation.c | 2 +- 2 files changed, 6 insertions(+), 6 deletions(-) diff -puN mm/page_alloc.c~mm-page_alloc-avoid-page_to_pfn-when-merging-buddies mm/page_alloc.c --- a/mm/page_alloc.c~mm-page_alloc-avoid-page_to_pfn-when-merging-buddies +++ a/mm/page_alloc.c @@ -714,7 +714,7 @@ static inline void rmv_page_order(struct /* * 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 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); diff -puN mm/page_isolation.c~mm-page_alloc-avoid-page_to_pfn-when-merging-buddies mm/page_isolation.c --- a/mm/page_isolation.c~mm-page_alloc-avoid-page_to_pfn-when-merging-buddies +++ a/mm/page_isolation.c @@ -106,7 +106,7 @@ static void unset_migratetype_isolate(st 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
