If I understand correctly the linux source I just read, the FRAG mem parameter (memory used at the for the IP fragments re-assembly) is in bytes. I need to check for the other mem parameters, but I would expect to be in bytes too.
unless I am mistaken, it seems that the mem parameters for TCP and UDP is the number of kernel pages allocated. However, the memory parameter of FRAG seems to be the memory allocated bytes for fragmentation re-assembly...
"Very intuitive, and well documented" indeed. (use sarcastic tone)