VMMAP: Initialize virtual memmap properly in memmap_init_zone

If we have a VIRTUAL_MEM_MAP then memmap_init_zone needs to
consider the page boundaries of the virtual memory map.

This also introduces VMEMMAP_PAGE_SIZE which defines the page
size of the pages used for the Virtual memmap.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.18-mm3/mm/page_alloc.c
===================================================================
--- linux-2.6.18-mm3.orig/mm/page_alloc.c	2006-10-04 00:35:57.131054837 -0500
+++ linux-2.6.18-mm3/mm/page_alloc.c	2006-10-04 01:34:13.100258531 -0500
@@ -1772,6 +1772,23 @@ void __meminit memmap_init_zone(unsigned
 	unsigned long end_pfn = start_pfn + size;
 	unsigned long pfn;
 
+#ifdef CONFIG_VIRTUAL_MEM_MAP
+	/*
+	 * We have to initialize "out of bounds" struct page elements that
+	 * fit completely on the same pages that were allocated for the
+	 * "in bounds" elements because they may be referenced later (and
+	 * found to be "reserved").
+	 */
+	start_pfn -=
+	  ((unsigned long) pfn_to_page(start_pfn)) & (VMEMMAP_PAGE_SIZE - 1)
+			/ sizeof(struct page);
+
+	end_pfn +=
+	   (ALIGN(((unsigned long) pfn_to_page(end_pfn)), VMEMMAP_PAGE_SIZE) -
+			(unsigned long) (pfn_to_page(end_pfn)))
+		   		/ sizeof(struct page);
+
+#endif
 	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
 		if (!early_pfn_valid(pfn))
 			continue;
Index: linux-2.6.18-mm3/arch/ia64/mm/init.c
===================================================================
--- linux-2.6.18-mm3.orig/arch/ia64/mm/init.c	2006-10-04 01:17:44.914767745 -0500
+++ linux-2.6.18-mm3/arch/ia64/mm/init.c	2006-10-04 01:34:13.129557898 -0500
@@ -530,15 +530,6 @@ virtual_memmap_init (u64 start, u64 end,
 	if (map_end > args->end)
 		map_end = args->end;
 
-	/*
-	 * We have to initialize "out of bounds" struct page elements that fit completely
-	 * on the same pages that were allocated for the "in bounds" elements because they
-	 * may be referenced later (and found to be "reserved").
-	 */
-	map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1)) / sizeof(struct page);
-	map_end += ((PAGE_ALIGN((unsigned long) map_end) - (unsigned long) map_end)
-		    / sizeof(struct page));
-
 	if (map_start < map_end)
 		memmap_init_zone((unsigned long)(map_end - map_start),
 				 args->nid, args->zone, page_to_pfn(map_start));