diff --git a/drivers/char/agp/nvidia-agp.c b/drivers/char/agp/nvidia-agp.c
index eaceb61..0cc1c5b 100644
--- a/drivers/char/agp/nvidia-agp.c
+++ b/drivers/char/agp/nvidia-agp.c
@@ -201,10 +201,15 @@
 static int nvidia_insert_memory(struct agp_memory *mem, off_t pg_start, int type)
 {
 	int i, j;
+	int mask_type;
 
-	if ((type != 0) || (mem->type != 0))
+	mask_type = agp_generic_type_to_mask_type(mem->bridge, type);
+	if (mask_type != 0 || type != mem->type)
 		return -EINVAL;
 
+	if (mem->page_count == 0)
+		return 0;
+
 	if ((pg_start + mem->page_count) >
 		(nvidia_private.num_active_entries - agp_memory_reserved/PAGE_SIZE))
 		return -EINVAL;
@@ -220,10 +225,13 @@
 	}
 	for (i = 0, j = pg_start; i < mem->page_count; i++, j++) {
 		writel(agp_bridge->driver->mask_memory(agp_bridge,
-			mem->memory[i], mem->type),
+			mem->memory[i], mask_type),
 			agp_bridge->gatt_table+nvidia_private.pg_offset+j);
-		readl(agp_bridge->gatt_table+nvidia_private.pg_offset+j);	/* PCI Posting. */
 	}
+
+	/* PCI Posting. */
+	readl(agp_bridge->gatt_table+nvidia_private.pg_offset+j - 1);
+
 	agp_bridge->driver->tlb_flush(mem);
 	return 0;
 }
@@ -233,9 +241,15 @@
 {
 	int i;
 
-	if ((type != 0) || (mem->type != 0))
+	int mask_type;
+
+	mask_type = agp_generic_type_to_mask_type(mem->bridge, type);
+	if (mask_type != 0 || type != mem->type)
 		return -EINVAL;
 
+	if (mem->page_count == 0)
+		return 0;
+
 	for (i = pg_start; i < (mem->page_count + pg_start); i++)
 		writel(agp_bridge->scratch_page, agp_bridge->gatt_table+nvidia_private.pg_offset+i);