Index: sys/kern/vfs_mountroot.c
===================================================================
--- sys/kern/vfs_mountroot.c
+++ sys/kern/vfs_mountroot.c
@@ -515,7 +515,9 @@
 	do {
 		error = EINVAL;
 		printf("\nmountroot> ");
+		DROP_GIANT();
 		cngets(name, sizeof(name), GETS_ECHO);
+		PICKUP_GIANT();
 		if (name[0] == '\0')
 			break;
 		if (name[0] == '?' && name[1] == '\0') {