Index: kern/kern_conf.c
===================================================================
--- kern/kern_conf.c	(revision 221375)
+++ kern/kern_conf.c	(working copy)
@@ -893,35 +893,69 @@
 	dev_unlock();
 }
 
-struct cdev *
-make_dev_alias(struct cdev *pdev, const char *fmt, ...)
+static int
+make_dev_alias_v(int flags, struct cdev **cdev, struct cdev *pdev,
+    const char *fmt, va_list ap)
 {
 	struct cdev *dev;
-	va_list ap;
 	int error;
 
 	KASSERT(pdev != NULL, ("NULL pdev"));
-	dev = devfs_alloc(MAKEDEV_WAITOK);
+	KASSERT((flags & MAKEDEV_WAITOK) == 0 || (flags & MAKEDEV_NOWAIT) == 0,
+	    ("make_dev_alias_v: both WAITOK and NOWAIT specified"));
+
+	dev = devfs_alloc(flags);
+	if (dev == NULL)
+		return (ENOMEM);
 	dev_lock();
 	dev->si_flags |= SI_ALIAS;
-	va_start(ap, fmt);
 	error = prep_devname(dev, fmt, ap);
-	va_end(ap);
 	if (error != 0) {
-		panic("make_dev_alias: bad si_name (error=%d, si_name=%s)",
-		    error, dev->si_name);
+		if ((flags & MAKEDEV_CHECKNAME) == 0) {
+			panic("make_dev_alias_v: bad si_name "
+			    "(error=%d, si_name=%s)", error, dev->si_name);
+		}
+		dev_unlock();
+		devfs_free(dev);
+	} else {
+		dev->si_flags |= SI_NAMED;
+		devfs_create(dev);
+		dev_dependsl(pdev, dev);
+		clean_unrhdrl(devfs_inos);
+		dev_unlock();
+		notify_create(dev, flags);
+		*cdev = dev;
 	}
-	dev->si_flags |= SI_NAMED;
-	devfs_create(dev);
-	dev_dependsl(pdev, dev);
-	clean_unrhdrl(devfs_inos);
-	dev_unlock();
 
-	notify_create(dev, MAKEDEV_WAITOK);
+	return (error);
+}
 
-	return (dev);
+struct cdev *
+make_dev_alias(struct cdev *pdev, const char *fmt, ...)
+{
+	struct cdev *dev;
+	va_list ap;
+	int res;
+
+	va_start(ap, fmt);
+	res = make_dev_alias_v(MAKEDEV_WAITOK, &dev, pdev, fmt, ap);
+	va_end(ap);
+	return (res == 0 ? dev: NULL);
 }
 
+int
+make_dev_alias_p(int flags, struct cdev **cdev, struct cdev *pdev,
+    const char *fmt, ...)
+{
+	va_list ap;
+	int res;
+
+	va_start(ap, fmt);
+	res = make_dev_alias_v(flags, cdev, pdev, fmt, ap);
+	va_end(ap);
+	return (res);
+}
+
 static void
 destroy_devl(struct cdev *dev)
 {
Index: geom/geom_dev.c
===================================================================
--- geom/geom_dev.c	(revision 221375)
+++ geom/geom_dev.c	(working copy)
@@ -148,7 +148,8 @@
 			snprintf(buf, sizeof(buf), "%s%s",
 			    val, gp->name + len);
 			freeenv(val);
-			adev = make_dev_alias(dev, buf);
+			make_dev_alias_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK,
+			    &adev, dev, "%s", buf);
 			break;
 		}
 	}
Index: sys/conf.h
===================================================================
--- sys/conf.h	(revision 221375)
+++ sys/conf.h	(working copy)
@@ -278,6 +278,8 @@
 		const char *_fmt, ...) __printflike(8, 9);
 struct cdev *make_dev_alias(struct cdev *_pdev, const char *_fmt, ...)
 		__printflike(2, 3);
+int	make_dev_alias_p(int _flags, struct cdev **_cdev, struct cdev *_pdev,
+		const char *_fmt, ...) __printflike(4, 5);
 void	dev_lock(void);
 void	dev_unlock(void);
 void	setconf(void);