previously we noticed that calling MmUnmapLockedPages() causes kernel crashes (thus the code is if 0-ed). however, when we don't unmap memory, it keeps accumulating in the nfsd's process memory (and is never "freed").
in this patch
(a) calling unmap
(b) checking if MmMapLockedPagesSpecifyCache() returns us a NULL pointer which is a type of failure that doesn't throw an exception but still is a failure.
(c) cosmetic change to printf.
NOTE: this cause still leads to failures for general tests. Running them in a loop (previously produced kernel crashes) now just leads to test failing. the cause is unknown!