From 69d177c2fc702d402b17fdca2190d5a7e3ca55c5 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Thu, 6 Nov 2008 12:53:26 -0800 Subject: hugetlbfs: handle pages higher order than MAX_ORDER When working with hugepages, hugetlbfs assumes that those hugepages are smaller than MAX_ORDER. Specifically it assumes that the mem_map is contigious and uses that to optimise access to the elements of the mem_map that represent the hugepage. Gigantic pages (such as 16GB pages on powerpc) by definition are of greater order than MAX_ORDER (larger than MAX_ORDER_NR_PAGES in size). This means that we can no longer make use of the buddy alloctor guarentees for the contiguity of the mem_map, which ensures that the mem_map is at least contigious for maximmally aligned areas of MAX_ORDER_NR_PAGES pages. This patch adds new mem_map accessors and iterator helpers which handle any discontiguity at MAX_ORDER_NR_PAGES boundaries. It then uses these to implement gigantic page versions of copy_huge_page and clear_huge_page, and to allow follow_hugetlb_page handle gigantic pages. Signed-off-by: Andy Whitcroft Cc: Jon Tollefson Cc: Mel Gorman Cc: Nick Piggin Cc: Christoph Lameter Cc: [2.6.27.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index e4e728bdf324..f482460de3e6 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -175,6 +175,34 @@ static inline void free_page_mlock(struct page *page) { } #endif /* CONFIG_UNEVICTABLE_LRU */ +/* + * Return the mem_map entry representing the 'offset' subpage within + * the maximally aligned gigantic page 'base'. Handle any discontiguity + * in the mem_map at MAX_ORDER_NR_PAGES boundaries. + */ +static inline struct page *mem_map_offset(struct page *base, int offset) +{ + if (unlikely(offset >= MAX_ORDER_NR_PAGES)) + return pfn_to_page(page_to_pfn(base) + offset); + return base + offset; +} + +/* + * Iterator over all subpages withing the maximally aligned gigantic + * page 'base'. Handle any discontiguity in the mem_map. + */ +static inline struct page *mem_map_next(struct page *iter, + struct page *base, int offset) +{ + if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) { + unsigned long pfn = page_to_pfn(base) + offset; + if (!pfn_valid(pfn)) + return NULL; + return pfn_to_page(pfn); + } + return iter + 1; +} + /* * FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node, * so all functions starting at paging_init should be marked __init -- cgit v1.2.2 From 18229df5b613ed0732a766fc37850de2e7988e43 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Thu, 6 Nov 2008 12:53:27 -0800 Subject: hugetlb: pull gigantic page initialisation out of the default path As we can determine exactly when a gigantic page is in use we can optimise the common regular page cases by pulling out gigantic page initialisation into its own function. As gigantic pages are never released to buddy we do not need a destructor. This effectivly reverts the previous change to the main buddy allocator. It also adds a paranoid check to ensure we never release gigantic pages from hugetlbfs to the main buddy. Signed-off-by: Andy Whitcroft Cc: Jon Tollefson Cc: Mel Gorman Cc: Nick Piggin Cc: Christoph Lameter Cc: [2.6.27.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index f482460de3e6..13333bc2eb68 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -17,6 +17,7 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma, unsigned long floor, unsigned long ceiling); extern void prep_compound_page(struct page *page, unsigned long order); +extern void prep_compound_gigantic_page(struct page *page, unsigned long order); static inline void set_page_count(struct page *page, int v) { -- cgit v1.2.2