diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0bca2376bd42..573d138fa7a5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -307,27 +307,31 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
 {
 #ifdef CONFIG_HIGHMEM
 	int node;
-	unsigned long x = 0;
+	unsigned long x;
 	int i;
-	unsigned long dirtyable = atomic_read(&highmem_file_pages);
+	unsigned long dirtyable = 0;
 
 	for_each_node_state(node, N_HIGH_MEMORY) {
 		for (i = ZONE_NORMAL + 1; i < MAX_NR_ZONES; i++) {
 			struct zone *z;
+			unsigned long nr_pages;
 
 			if (!is_highmem_idx(i))
 				continue;
 
 			z = &NODE_DATA(node)->node_zones[i];
-			dirtyable += zone_page_state(z, NR_FREE_PAGES);
+			if (!populated_zone(z))
+				continue;
 
+			nr_pages = zone_page_state(z, NR_FREE_PAGES);
 			/* watch for underflows */
-			dirtyable -= min(dirtyable, high_wmark_pages(z));
-
-			x += dirtyable;
+			nr_pages -= min(nr_pages, high_wmark_pages(z));
+			dirtyable += nr_pages;
 		}
 	}
 
+	x = dirtyable + atomic_read(&highmem_file_pages);
+
 	/*
 	 * Unreclaimable memory (kernel memory or anonymous memory
 	 * without swap) can bring down the dirtyable pages below