path: root/mm/internal.h
diff options
authorAndy Whitcroft <apw@shadowen.org>2008-11-06 12:53:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-06 15:41:18 -0800
commit69d177c2fc702d402b17fdca2190d5a7e3ca55c5 (patch)
tree2040e0a84b7c07c29ac6fb6e51e125de52256f5d /mm/internal.h
parent22bece00dc1f28dd3374c55e464c9f02eb642876 (diff)
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 <apw@shadowen.org> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: <stable@kernel.org> [2.6.27.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/internal.h')
1 files changed, 28 insertions, 0 deletions
diff --git a/mm/internal.h b/mm/internal.h
index e4e728bdf32..f482460de3e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -176,6 +176,34 @@ static inline void free_page_mlock(struct page *page) { }
+ * 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
* in those cases. SPARSEMEM, however, allows for memory hotplug,