trap in FFS softdep add_to_worklist()

[Nate Lawson]

I checked the archives for this but didn't find it anywhere.  After
upgrading to RELENG_7, I got a page fault trap in
ffs_softdep.c:add_to_worklist() while running cvsup.  I assume it only
occurs during heavy disk IO.  Since it's RELENG_7, INVARIANTS is not on.
 Looking at the surrounding code, it appears the trap is a side effect
of a bug somewhere else (possibly an invalid workitem list).

If it happens again, I'll try to get a better bug report in.  Just
curious if anyone has seen this.

-- 
Nate