Shark hangs hard

[Martin Husemann <martin%duskware.de@localhost>]

Just a heads up (while still investigating): this week I have been unable
to run the weekly atf tests on shark.

The machine hangs hard, randomly, and never survived a full test run.
We have seen hangs before (on sharks with less memory, even during
the nightly runs), but never on this 96 MB one.

My other shark (with 64MB) is happy and never crashed since Nick's recent
pmap changes. I haven't stressed it a lot nor run atf tests on it though.

Martin