diff -urN kernel-source-2.4.24/arch/um/drivers/ubd_kern.c kernel-source-2.4.24.mp/arch/um/drivers/ubd_kern.c
--- kernel-source-2.4.24/arch/um/drivers/ubd_kern.c	2004-04-14 14:38:21.000000000 +0200
+++ kernel-source-2.4.24.mp/arch/um/drivers/ubd_kern.c	2004-04-14 14:42:55.000000000 +0200
@@ -495,6 +495,16 @@
 
 void kill_io_thread(void)
 {
+	int i;
+	struct ubd * ubd_devp = ubd_dev;
+
+	for(i = 0; i < MAX_DEV; i++, ubd_devp++) {
+		if(ubd_devp) {
+			os_close_file(ubd_devp->fd);
+			close(ubd_devp->cow.fd);	
+		}
+	}
+
 	if(io_pid != -1)
 		os_kill_process(io_pid, 1);
 }