if err != nil {
		t.Fatal(&os.PathError{Op: "open", Path: subCgroup, Err: err})
	}
	t.Cleanup(func() { syscall.Close(cgroupFD) })

	return cgroupFD, "/" + path.Base(subCgroup)
}

func TestUseCgroupFD(t *testing.T) {
	testenv.MustHaveExec(t)

	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
		// Read and print own cgroup path.
		selfCg, err := os.ReadFile("/proc/self/cgroup")
		if err != nil {