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| author | Bob Picco <bob.picco@hp.com> | 2006-05-20 15:00:31 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-21 12:59:22 -0700 |
| commit | e984bb43f7450312ba66fe0e67a99efa6be3b246 (patch) | |
| tree | 54c86240172136fc81c773f71cd70eda54fed6f2 | |
| parent | ae57a856429dd932c547530df1b234eb7e642297 (diff) | |
| download | linux-e984bb43f7450312ba66fe0e67a99efa6be3b246.tar.bz2 | |
[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>
| -rw-r--r-- | include/linux/mmzone.h | 1 | ||||
| -rw-r--r-- | mm/page_alloc.c | 14 |
2 files changed, 12 insertions, 3 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b5c21122c299..36740354d4db 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; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bb3416932ab0..253a450c400d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2125,14 +2125,22 @@ static void __init alloc_node_mem_map(struct pglist_data *pgdat) #ifdef CONFIG_FLAT_NODE_MEM_MAP /* ia64 gets its own node_mem_map, before this, without bootmem */ if (!pgdat->node_mem_map) { - unsigned long size; + unsigned long size, start, end; struct page *map; - size = (pgdat->node_spanned_pages + 1) * sizeof(struct page); + /* + * The zone's endpoints aren't required to be MAX_ORDER + * aligned but the node_mem_map endpoints must be in order + * for the buddy allocator to function correctly. + */ + start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1); + end = pgdat->node_start_pfn + pgdat->node_spanned_pages; + end = ALIGN(end, MAX_ORDER_NR_PAGES); + size = (end - start) * sizeof(struct page); map = alloc_remap(pgdat->node_id, size); if (!map) map = alloc_bootmem_node(pgdat, size); - pgdat->node_mem_map = map; + pgdat->node_mem_map = map + (pgdat->node_start_pfn - start); } #ifdef CONFIG_FLATMEM /* |