diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bb34169..253a450 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2125,14 +2125,22 @@
 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 	/* ia64 gets its own node_mem_map, before this, without bootmem */
 	if (!pgdat->node_mem_map) {
-		unsigned long size;
+		unsigned long size, start, end;
 		struct page *map;
 
-		size = (pgdat->node_spanned_pages + 1) * sizeof(struct page);
+		/*
+		 * The zone's endpoints aren't required to be MAX_ORDER
+		 * aligned but the node_mem_map endpoints must be in order
+		 * for the buddy allocator to function correctly.
+		 */
+		start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
+		end = pgdat->node_start_pfn + pgdat->node_spanned_pages;
+		end = ALIGN(end, MAX_ORDER_NR_PAGES);
+		size =  (end - start) * sizeof(struct page);
 		map = alloc_remap(pgdat->node_id, size);
 		if (!map)
 			map = alloc_bootmem_node(pgdat, size);
-		pgdat->node_mem_map = map;
+		pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
 	}
 #ifdef CONFIG_FLATMEM
 	/*