if err != nil {
		t.Fatalf("mmap failed %s", err)
	}
	err = syscall.Mprotect(b[:pagesize], syscall.PROT_NONE)
	if err != nil {
		t.Fatalf("mprotect low failed %s\n", err)
	}
	err = syscall.Mprotect(b[2*pagesize:], syscall.PROT_NONE)
	if err != nil {
		t.Fatalf("mprotect high failed %s\n", err)
	}
	return b[pagesize : 2*pagesize]
}