vm_unreserve_memory_or_swap
void vm_unreserve_memory_or_swap(size_t bytes);
vm_unreserve_memory_or_swap(fCommittedSize - actualSize);
vm_unreserve_memory_or_swap((off_t)pageCount * B_PAGE_SIZE);
vm_unreserve_memory_or_swap(fCommittedSize);
vm_unreserve_memory_or_swap(fCommittedSize - size);
vm_unreserve_memory_or_swap(amount);