Hi, I've seen this too, but it was hard to tell the cause.
There was a commit made to attempt a fix to the problem, which was not pull up by accident - I've requested to pull it to -7 and -7-0. I'm not sure if it fixes the problem, because it is hard to reproduce and the backtrace gave no indication of the cause, and it's not immediately clear that the code does what we suspect it might -- zero sized allocations (as with the previous panic, but without hitting an assert). It will provide a warning in dmesg instead with the new change. http://freshbsd.org/commit/netbsd/c02dc097d7c140630046c7b3accbb26dc9684e0c Hope it helps.
