I saw something very very similar to this, withOUT afs, but with
kernel source supped, approximately, Friday, on a pmax.  Except I saw
it on a local FFS filesystems, and it was probably due to a glitch in
the source tree on my NFS server.

It looks like, just maybe, some of your kernel header files aren't
quite consistent with the kernel source code.  My advice is to resup
and try again, after making *sure* you've rebuild and reinstalled and
rerun config.

If you still see this problem, you may need to recompile your AFS
client code/LKM from source.