Index: subr_autoconf.c
===================================================================
RCS file: /cvs/src/sys/kern/subr_autoconf.c,v
retrieving revision 1.83
diff -u -p -r1.83 subr_autoconf.c
--- subr_autoconf.c	19 Jan 2015 23:01:07 -0000	1.83
+++ subr_autoconf.c	21 Jan 2015 02:02:37 -0000
@@ -935,8 +935,11 @@ device_ref(struct device *dv)
 void
 device_unref(struct device *dv)
 {
+	struct cfattach *ca;
+
 	dv->dv_ref--;
 	if (dv->dv_ref == 0) {
-		free(dv, M_DEVBUF, 0);
+		ca = dv->dv_cfdata->cf_attach;
+		free(dv, M_DEVBUF, ca->ca_devsize);
 	}
 }