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authorBob Picco <bob.picco@hp.com>2006-05-20 15:00:31 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-05-21 12:59:22 -0700
commite984bb43f7450312ba66fe0e67a99efa6be3b246 (patch)
tree54c86240172136fc81c773f71cd70eda54fed6f2 /include/linux/mmzone.h
parentae57a856429dd932c547530df1b234eb7e642297 (diff)
[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 <bob.picco@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/mmzone.h')
-rw-r--r--include/linux/mmzone.h1
1 files changed, 1 insertions, 0 deletions
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;