Index: linux-2.6.18-rc5-mm1/kernel/wait.c
===================================================================
--- linux-2.6.18-rc5-mm1.orig/kernel/wait.c	2006-08-27 20:41:48.000000000 -0700
+++ linux-2.6.18-rc5-mm1/kernel/wait.c	2006-09-11 12:52:08.524348654 -0700
@@ -245,9 +245,20 @@ EXPORT_SYMBOL(wake_up_bit);
 fastcall wait_queue_head_t *bit_waitqueue(void *word, int bit)
 {
 	const int shift = BITS_PER_LONG == 32 ? 5 : 6;
-	const struct zone *zone = page_zone(virt_to_page(word));
+	const struct zone *zone;
 	unsigned long val = (unsigned long)word << shift | bit;
+	unsigned long hash = hash_long(val, zone->wait_table_bits);
+	struct page *page;
 
+	printk(KERN_CRIT "bit_waitqueue(%p,%d) shift=%d val=%ld\n", word, bit, shift, val);
+	page = virt_to_page(word);
+	printk(KERN_CRIT "page=%p flags=%lx\n", page, page->flags);
+	printk(KERN_CRIT "zone_id=%d zonetable[0]=%p\n", page_zone_id(page), zone_table[0]);
+	zone = page_zone(page);
+	BUG_ON(!zone);
+	hash = hash_long(val, zone->wait_table_bits);
+	printk(KERN_CRIT "bit_waitqueue virt_to_page=%p zone=%p hash=%lu\n",
+			virt_to_page(word), zone, hash);
 	return &zone->wait_table[hash_long(val, zone->wait_table_bits)];
 }
 EXPORT_SYMBOL(bit_waitqueue);