Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm1-V0.7.28-1

[Ingo Molnar <mingo@elte.hu>]

* Christian Meder <chris@onestepahead.de> wrote:

> I've got one of those 'my box just locked up'. I can reproduce it with
> 0.7.25-1, 0.7.28-0 and 0.7.28-1 by starting the Jetty servlet
> container with our inhouse java project under a Blackdown 1.4 jdk.
> Within a minute the laptop just locks up: no mouse, no ping, console
> switching sysrq-t or anything. The peculiar thing is that I was
> running 0.7.25-1 for two or three days before and it was rocksolid. It
> was just when I started to work with the jvm that things fell apart.
> 
> Any chance to get any interesting and helpful data in this setup ?

best would be to have a reproducer. Can you trigger it over the network,
using a remote session? If yes then you might want to try this: let the
box boot in, switch it to a text console and dont touch the keyboard
after that. Do this over the remote session:

	echo 1 > /proc/sys/kernel/debug_direct_keyboard

this activates a direct interrupt line for the keyboard only. Keep the
box on the text-console, and try to reproduce the hang over the network. 
Once it triggers, try SysRq - does it work? (leds wont work, but normal
keys should work.)

if the keyboard still doesnt work then you could try nmi_watchdog=1 or
nmi_watchdog=2 (the latter on IO-APIC-less systems), and serial logging,
to capture a dump of the hard-lockup.

	Ingo