Providing physically contiguous memory from memory that is allocated without
any guarantee of whether the underlying contiguous physical memory is contiguous
involves identifying contiguous pages of physical memory in the allocated virtual
memory. Such pages are contributed to a pool of contiguous physical memory for
use as required. Any pages that are not contributed to the pool of contiguous physical
memory, are not allocated with other pages that are contributed to the pool of
contiguous physical memory, can be freed from allocation for alternative uses.