int freed = freeList.free(Conversions.bytesToPages(start.diff(base).toInt()));
int freed = freeList.free(Conversions.bytesToPages(start.diff(base).toWord().toExtent()));
  public int free(VM_Address start) {    lock.acquire();    int freed = freeList.free(Conversions.bytesToPages(start.diff(base).toInt()));    lock.release();    memoryResource.release(freed);    return freed;  }