> -current sources as of Nov 30:
> 
>  panic: pmap_page_protect !PG_V: ctx 0, va 0xf0173000, pte 0x0

This is a long-standing bug that crops up every 6 months or so.
mgr seems to have seen most of these...

Anyway, this one is the first with the context info appended since
I put that in pmap.c, and the fact that `va' is a kernel address
might provide a clue.  If this is like the other cases, then the
traceback would show process 0 preparing a page for page-out
which includes doing a pmap_page_protect(PROT_NONE) on that page.

Now, pages eligible for page-out do not normally map to kernel addresses,
unless it's double-mapped user page doing physio() or something like that.

-pk