From e984bb43f7450312ba66fe0e67a99efa6be3b246 Mon Sep 17 00:00:00 2001 From: Bob Picco Date: Sat, 20 May 2006 15:00:31 -0700 Subject: [PATCH] Align the node_mem_map endpoints to a MAX_ORDER boundary Andy added code to buddy allocator which does not require the zone's endpoints to be aligned to MAX_ORDER. An issue is that the buddy allocator requires the node_mem_map's endpoints to be MAX_ORDER aligned. Otherwise __page_find_buddy could compute a buddy not in node_mem_map for partial MAX_ORDER regions at zone's endpoints. page_is_buddy will detect that these pages at endpoints are not PG_buddy (they were zeroed out by bootmem allocator and not part of zone). Of course the negative here is we could waste a little memory but the positive is eliminating all the old checks for zone boundary conditions. SPARSEMEM won't encounter this issue because of MAX_ORDER size constraint when SPARSEMEM is configured. ia64 VIRTUAL_MEM_MAP doesn't need the logic either because the holes and endpoints are handled differently. This leaves checking alloc_remap and other arches which privately allocate for node_mem_map. Signed-off-by: Bob Picco Acked-by: Mel Gorman Cc: Dave Hansen Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/mmzone.h') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b5c21122c29..36740354d4d 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -22,6 +22,7 @@ #else #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER #endif +#define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1)) struct free_area { struct list_head free_list; -- cgit v1.2.3