VOID
MmFreePagesFromMdl(
  IN  PMDL MemoryDescriptorList
  );

Routine Description:

    This routine walks the argument MDL freeing each physical page back to
    the PFN database.  This is designed to free pages acquired via
    MmAllocatePagesForMdl only.

Arguments:

    MemoryDescriptorList - Supplies an MDL which contains the pages to be freed.

Return Value:

    None.

Environment:

    Kernel mode, IRQL of APC_LEVEL or below.