diff -r b420e936c022 drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c	Wed Jul 15 09:10:37 2009 +0100
+++ b/drivers/xen/blkback/blkback.c	Thu Jul 16 16:27:16 2009 -0700
@@ -453,6 +453,11 @@
 			DPRINTK("invalid buffer -- could not remap it\n");
 			map[i].handle = BLKBACK_INVALID_HANDLE;
 			ret |= 1;
+		} else {
+			blkback_pagemap_set(vaddr_pagenr(pending_req, i),
+					    virt_to_page(vaddr(pending_req, i)),
+					    blkif->domid, req->handle,
+					    req->seg[i].gref);
 		}
 
 		pending_handle(pending_req, i) = map[i].handle;
@@ -465,10 +470,6 @@
 			FOREIGN_FRAME(map[i].dev_bus_addr >> PAGE_SHIFT));
 		seg[i].buf  = map[i].dev_bus_addr | 
 			(req->seg[i].first_sect << 9);
-		blkback_pagemap_set(vaddr_pagenr(pending_req, i),
-				    virt_to_page(vaddr(pending_req, i)),
-				    blkif->domid, req->handle,
-				    req->seg[i].gref);
 	}
 
 	if (ret)