int offset = addr.diff(start).toInt(); int page = Conversions.bytesToPages(offset);
int page = Conversions.bytesToPages(addr.diff(start).toWord().toExtent());
  public final int getSize(VM_Address addr) {    int offset = addr.diff(start).toInt();    int page = Conversions.bytesToPages(offset);    return freeList.size(page);  }