OOM conditions

[Benjamin M. Schwartz]

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Richard A. Smith wrote:
> Working the table at the Boston book festival I was reminded how painful the OOM stuff is on a gen 1.

The OOM problem on Gen 1 is a True Kernel Bug.  The problem is that the
OOM killer just isn't working.  Almost all the time, it fails to kill
_any_ process, and instead just locks up the machine.

I believe Andres was able to connect via a serial port during one of these
events, and observed the kswapd process in an "uninterruptible sleep"
(a.k.a. "state D").  This should never happen.

There has been a significant amount of churn in the OOM system over the
past few years, and a number of bugs are known to have been created and
resolved.  To the best of my knowledge, no one has ever precisely
identified whether the XO's problem is due to one of them.

Until recently, there was no newer XO kernel with which to test.  It would
be worthwhile to observe the F11-XO1 builds' behavior at OOM, to see if
there has been an improvement.

- --Ben
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