Re: how to debug a deadlock'ed kernel?

From: Brian Horton (
Date: Fri Dec 14 2001 - 16:35:26 EST

Yup, the nmi_watchdog option didn't work, but I was able to get
information I needed with kdb!

thx! .bri.

Oliver Xymoron wrote:
> On Tue, 11 Dec 2001, Brian Horton wrote:
> > Thanks, I'll try the nmi_watchdog option out. It appears to not be in
> > the 2.2.14 kernel, but is in a 2.2.19 kernel that I have from RedHat.
> It's there by default in SMP, you just have to enable it with
> nmiwatchdog=1 at boot (or something). I didn't mention it because it
> probably won't help your problem: as you can use the magic sysrq keys to
> reboot, you are not deadlocked with interrupts off, therefore the timer
> interrupt will keep the NMI watchdog from ever firing. NMI watchdog is
> mostly of use when you can't even get the capslock light to toggle..
> > > > Anyone got any good tips on how to debug a SMP system that is locked up
> > > > in a deadlock situation in the kernel? I'm working on a kernel module,
> > > > and after some number of hours of stress testing, the box locks up. None
> > > > of the sysrq options show anything on the display, though the reBoot
> > > > option does reboot the system. RedHat 6.2 and its 2.2.14 kernel. Doesn't
> > > > hang for me on 2.4, so I need to debug it here...
> --
> "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:29 EST