panic when zones fail correct alignment and other checks.
The alternative could be random and/or undetected corruption later.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c	2006-05-19 13:15:51.000000000 +1000
+++ linux-2.6/mm/page_alloc.c	2006-05-21 12:22:44.000000000 +1000
@@ -2041,6 +2041,47 @@ static __meminit void zone_pcp_init(stru
 			zone->name, zone->present_pages, batch);
 }
 
+static __meminit void zone_debug_checks(struct zone *zone)
+{
+	unsigned long pfn;
+	unsigned long start = zone->zone_start_pfn;
+	unsigned long end = start + zone->spanned_pages;
+	const unsigned long mask = ((1<<MAX_ORDER)-1);
+	
+	if (start & mask)
+		panic("zone start pfn (%lx) not MAX_ORDER aligned\n", start);
+
+	if (end & mask)
+		panic("zone end pfn (%lx) not MAX_ORDER aligned\n", end);
+
+	for (pfn = start; pfn < end; pfn++) {
+		struct page *page;
+		int order;
+
+#ifndef CONFIG_HOLES_IN_ZONE
+		if (!pfn_valid(pfn))
+			panic("zone pfn (%lx) not valid\n", pfn);
+#endif
+
+		page = pfn_to_page(pfn);
+		if (page_zone(page) != zone)
+			panic("zone page (pfn %lx) in wrong zone\n", pfn);
+
+		for (order = 0; order < MAX_ORDER-1; order++) {
+			struct page *buddy;
+			buddy = __page_find_buddy(page, pfn & mask, order);
+
+#ifndef CONFIG_HOLES_IN_ZONE
+			if (!pfn_valid(page_to_pfn(buddy)))
+				panic("pfn (%lx) buddy (order %d) not valid\n", pfn, order);
+#endif
+
+			if (page_zone(buddy) != zone)
+				panic("pfn (%lx) buddy (order %d) in wrong zone\n", pfn, order);
+		}
+	}
+}
+
 static __meminit void init_currently_empty_zone(struct zone *zone,
 		unsigned long zone_start_pfn, unsigned long size)
 {
@@ -2054,6 +2095,8 @@ static __meminit void init_currently_emp
 	memmap_init(size, pgdat->node_id, zone_idx(zone), zone_start_pfn);
 
 	zone_init_free_lists(pgdat, zone, zone->spanned_pages);
+
+	zone_debug_checks(zone);
 }
 
 /*