--- a/Documentation/accounting/getdelays.c
+++ b/Documentation/accounting/getdelays.c
@@ -391,6 +391,10 @@
 			perror("error sending cgroupstats command");
 			goto err;
 		}
+	}
+	if (!maskset && !tid && !containerset) {
+		usage();
+		goto err;
 	}
 
 	do {