We have this constructor in ReservedSpace:
// Initialize the reserved space with the given size. If preferred_page_size
// is set, use this as minimum page size/alignment. This may waste some space
// if the given size is not aligned to that value, as the reservation will be
// aligned up to the final alignment in this case.
ReservedSpace(size_t size, size_t preferred_page_size = 0);
Instead of having the default parameter using two constructors would make the implementation more straight forward.
This cleanup is another step towards JDK-8261527.