Here's a repeatable (happens every hour or so) panic on NetBSD 3.1_STABLE. 
This has been dictated on the phone by a customer, so might not be exact. 
This machine has 2x 512MB DIMMs, we've run memtest86 w/o probs and tried 
various combinations of RAM sticks and slots. This machine and software is 
pretty much the same as other machines at other sites which are not having 
this problem.

uvm fault: kernel page fault trap
stopped in pid 20.1 pagedaemon at NetBSD:pool_reclaim+0x92:mov1
db> bt
pool_reclaim at NetBSD:pool_reclaim+0x92
pool_drain at NetBSD:pool_drain+0x45
uvm_pageout at NetBSD:uvm_pageout+0x11e

Any idea where to start looking?

-- 
Stephen