armv7 kernel panic on swap exhaustion

A Pi2B v1.1 (armv7) has paniced while running a -j3 buildworld.

I've put details at
http://www.zefox.net/~fbsd/rpi2/panic_on_swap_exhaustion/

This particular machine has been patched for the 
"panic on shutdown" problem, and that patch seemed
to work: shutdown panics were reproducible and the
patch made them go away completely. 

The panic reported in this message has never been 
seen before; whether it touches on the same issue
or is completely unrelated I've no idea. There are
no behaviors suggesting a faulty hard disk but some
of the console messages  might suggest otherwise.
The disk is far from new and has been well-used.
 
At the time top stopped updating swap usage was
modest (69 MB).

Thanks for reading,

bob prohaska