x86: ioremap(), extend check to all RAM pages

Suggested by Jan Beulich.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NJan Beulich <jbeulich@novell.com>

arch/x86/mm/ioremap.c

@@ -146,8 +146,9 @@ static void __iomem *__ioremap(resource_size_t phys_addr, unsigned long size,
 	/*
 	 * Don't allow anybody to remap normal RAM that we're using..
 	 */
-	for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
-	     (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+	for (pfn = phys_addr >> PAGE_SHIFT;
+				(pfn << PAGE_SHIFT) < last_addr; pfn++) {
+
 		if (page_is_ram(pfn) && pfn_valid(pfn) &&
 		    !PageReserved(pfn_to_page(pfn)))
 			return NULL;