Index: sys/geom/geom_dev.c
===================================================================
--- sys/geom/geom_dev.c
+++ sys/geom/geom_dev.c
@@ -346,7 +346,7 @@
 	cp->private = sc;
 	cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
 	error = g_attach(cp, pp);
-	KASSERT(error == 0,
+	KASSERT(error == 0 || error == ENXIO,
 	    ("g_dev_taste(%s) failed to g_attach, err=%d", pp->name, error));
 
 	make_dev_args_init(&args);
Index: sys/geom/geom_subr.c
===================================================================
--- sys/geom/geom_subr.c
+++ sys/geom/geom_subr.c
@@ -896,6 +896,8 @@
 	G_VALID_PROVIDER(pp);
 	g_trace(G_T_TOPOLOGY, "g_attach(%p, %p)", cp, pp);
 	KASSERT(cp->provider == NULL, ("attach but attached"));
+	if ((pp->flags & (G_PF_ORPHAN | G_PF_WITHER)) != 0)
+		return (ENXIO);
 	cp->provider = pp;
 	cp->flags &= ~G_CF_ORPHAN;
 	LIST_INSERT_HEAD(&pp->consumers, cp, consumers);
Index: sys/geom/geom_vfs.c
===================================================================
--- sys/geom/geom_vfs.c
+++ sys/geom/geom_vfs.c
@@ -260,7 +260,11 @@
 	sc->sc_bo = bo;
 	gp->softc = sc;
 	cp = g_new_consumer(gp);
-	g_attach(cp, pp);
+	error = g_attach(cp, pp);
+	if (error) {
+		g_wither_geom(gp, ENXIO);
+		return (error);
+	}
 	error = g_access(cp, 1, wr, wr);
 	if (error) {
 		g_wither_geom(gp, ENXIO);
Index: sys/geom/mountver/g_mountver.c
===================================================================
--- sys/geom/mountver/g_mountver.c
+++ sys/geom/mountver/g_mountver.c
@@ -586,7 +586,12 @@
 		return (NULL);
 
 	cp = LIST_FIRST(&gp->consumer);
-	g_attach(cp, pp);
+	error = g_attach(cp, pp);
+	if (error != 0) {
+		G_MOUNTVER_DEBUG(0, "Cannot attach to %s; error = %d.", pp->name, error);
+		return (NULL);
+	}
+
 	error = g_mountver_ident_matches(gp);
 	if (error != 0) {
 		g_detach(cp);