diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d73bfad..e1028fa 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3438,7 +3438,7 @@
 		mem_map = NODE_DATA(0)->node_mem_map;
 #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
 		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
-			mem_map -= pgdat->node_start_pfn;
+			mem_map -= (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
 	}
 #endif