From 14e072984179d3d421bf9ab75cc67e0961742841 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Sun, 6 May 2007 14:49:14 -0700 Subject: [PATCH] add pfn_valid_within helper for sub-MAX_ORDER hole detection Generally we work under the assumption that memory the mem_map array is contigious and valid out to MAX_ORDER_NR_PAGES block of pages, ie. that if we have validated any page within this MAX_ORDER_NR_PAGES block we need not check any other. This is not true when CONFIG_HOLES_IN_ZONE is set and we must check each and every reference we make from a pfn. Add a pfn_valid_within() helper which should be used when scanning pages within a MAX_ORDER_NR_PAGES block when we have already checked the validility of the block normally with pfn_valid(). This can then be optimised away when we do not have holes within a MAX_ORDER_NR_PAGES block of pages. Signed-off-by: Andy Whitcroft Acked-by: Mel Gorman Acked-by: Bob Picco Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 12 ++++++++++++ mm/page_alloc.c | 8 ++------ 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index ee9e3143df..2f1544e830 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -784,6 +784,18 @@ void sparse_init(void); void memory_present(int nid, unsigned long start, unsigned long end); unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long); +/* + * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we + * need to check pfn validility within that MAX_ORDER_NR_PAGES block. + * pfn_valid_within() should be used in this case; we optimise this away + * when we have no holes within a MAX_ORDER_NR_PAGES block. + */ +#ifdef CONFIG_HOLES_IN_ZONE +#define pfn_valid_within(pfn) pfn_valid(pfn) +#else +#define pfn_valid_within(pfn) (1) +#endif + #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */ #endif /* _LINUX_MMZONE_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 019ceda6a8..f564717d22 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -156,10 +156,8 @@ static int page_outside_zone_boundaries(struct zone *zone, struct page *page) static int page_is_consistent(struct zone *zone, struct page *page) { -#ifdef CONFIG_HOLES_IN_ZONE - if (!pfn_valid(page_to_pfn(page))) + if (!pfn_valid_within(page_to_pfn(page))) return 0; -#endif if (zone != page_zone(page)) return 0; @@ -346,10 +344,8 @@ __find_combined_index(unsigned long page_idx, unsigned int order) static inline int page_is_buddy(struct page *page, struct page *buddy, int order) { -#ifdef CONFIG_HOLES_IN_ZONE - if (!pfn_valid(page_to_pfn(buddy))) + if (!pfn_valid_within(page_to_pfn(buddy))) return 0; -#endif if (page_zone_id(page) != page_zone_id(buddy)) return 0; -- 2.20.1