um: Mark stub pages mapping with VM_PFNMAP
um: Mark stub pages mapping with VM_PFNMAP

Ensure that a process cannot destroy his stub pages with
using MADV_DONTNEED and friends.

Reported-by: 24e9a7e86225fc01f236a81fc86e902a74542aa1@gmx.de
Signed-off-by: Richard Weinberger <320bca71fc381a4a025636043ca86e734e31cf8b@nod.at>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs