VOID
MmUnmapLockedPages(
IN PVOID BaseAddress,
IN PMDL MemoryDescriptorList
);
MmUnmapLockedPages releases a mapping set up by a preceding call to MmMapLockedPages.
Callers of MmUnmapLockedPages must be running at IRQL <= DISPATCH_LEVEL if the pages were mapped to system space. Otherwise, the caller must be running at IRQL < DISPATCH_LEVEL.