This is the easiest way I have found to reproduce the issue we are seeing in production:

Repro:

• With a default ports build of MongoDB 1.8.3 on FreeBSD 8.2 AMD 64, create a database with about 5 Gigs of data.
• Load it up with continuous mega-inefficient text-search regex queries from 12 or so node.js clients
• Let it run for a few minutes
• Start killing and restarting your clients en masse

Expected:
Database stays up

Observed:
Seg fault, DB shuts down.

Thu Sep 22 11:29:29 [conn109] SocketException in connThread, closing client connection
Thu Sep 22 11:29:30 Invalid access at address: 0x5e8067

Thu Sep 22 11:29:30 Got signal: 11 (Segmentation fault: 11).

Thu Sep 22 11:29:30 Backtrace:

Thu Sep 22 11:29:30 dbexit:

We've seen this three times in production, and I have reproduced it on a test server. I'll try to get a build that will give me a backtrace.