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Subject[BUGFIX][PATCH] Fix usemap initialization v2
Tested on ia64/2.6.25
DISCONTIGMEM + 16KB/64KB pages
SPARSEMEM + 16KB/64KB pages
seems no troubles.

Thanks,
-Kame

=
usemap must be initialized only when pfn is within zone.
If not, it corrupts memory.

And this patch also reduces the number of calls to set_pageblock_migratetype()
from
(pfn & (pageblock_nr_pages -1)
to
!(pfn & (pageblock_nr_pages-1)
it should be called once per pageblock.

Changelog v1->v2
- Fixed boundary check.
- Move calculation of pointer for zone to out of loop.


Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
mm/page_alloc.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

Index: linux-2.6.25/mm/page_alloc.c
===================================================================
--- linux-2.6.25.orig/mm/page_alloc.c
+++ linux-2.6.25/mm/page_alloc.c
@@ -2518,7 +2518,9 @@ void __meminit memmap_init_zone(unsigned
struct page *page;
unsigned long end_pfn = start_pfn + size;
unsigned long pfn;
+ struct zone *z;

+ z = &NODE_DATA(nid)->node_zones[zid];
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
/*
* There can be holes in boot-time mem_map[]s
@@ -2536,7 +2538,6 @@ void __meminit memmap_init_zone(unsigned
init_page_count(page);
reset_page_mapcount(page);
SetPageReserved(page);
-
/*
* Mark the block movable so that blocks are reserved for
* movable at startup. This will force kernel allocations
@@ -2545,8 +2546,15 @@ void __meminit memmap_init_zone(unsigned
* kernel allocations are made. Later some blocks near
* the start are marked MIGRATE_RESERVE by
* setup_zone_migrate_reserve()
+ *
+ * bitmap is creted for zone's valid pfn range. but memmap
+ * can be created for invalid pages (for alignment)
+ * check here not to call set_pageblock_migratetpye() against
+ * pfn out of zone.
*/
- if ((pfn & (pageblock_nr_pages-1)))
+ if ((z->zone_start_pfn <= pfn)
+ && (pfn < z->zone_start_pfn + z->spanned_pages)
+ && !(pfn & (pageblock_nr_pages - 1)))
set_pageblock_migratetype(page, MIGRATE_MOVABLE);

INIT_LIST_HEAD(&page->lru);
@@ -4460,6 +4468,8 @@ void set_pageblock_flags_group(struct pa
pfn = page_to_pfn(page);
bitmap = get_pageblock_bitmap(zone, pfn);
bitidx = pfn_to_bitidx(zone, pfn);
+ VM_BUG_ON(pfn < zone->zone_start_pfn);
+ VM_BUG_ON(pfn >= zone->zone_start_pfn + zone->spanned_pages);

for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
if (flags & value)


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