Index: sys/kern/vfs_mount.c
===================================================================
--- sys/kern/vfs_mount.c
+++ sys/kern/vfs_mount.c
@@ -2469,7 +2469,7 @@
 	struct statfs *sfp = &mp->mnt_stat;
 	char *buf;
 
-	buf = malloc(DEVCTL_LEN, M_MOUNT, M_WAITOK);
+	buf = malloc(DEVCTL_LEN, M_MOUNT, M_NOWAIT);
 	if (buf == NULL)
 		return;
 	sbuf_new(&sb, buf, DEVCTL_LEN, SBUF_FIXEDLEN);
@@ -2496,7 +2496,8 @@
 		dev_vfs_event_mntopt(&sb, "optnew", mp->mnt_optnew);
 	sbuf_finish(&sb);
 
-	devctl_notify("VFS", "FS", type, sbuf_data(&sb));
+	if (sbuf_error(&sb) == 0)
+		devctl_notify("VFS", "FS", type, sbuf_data(&sb));
 	sbuf_delete(&sb);
 	free(buf, M_MOUNT);
 }