Re: Kernel panic at boot with ondemand governor as default (2.6.24-rc2)

Dave Jones
2007-11-12T20:26:59Z

On Mon, Nov 12, 2007 at 04:23:09PM +0100, Thomas Renninger wrote:
> On Mon, 2007-11-12 at 15:02 +0100, Eric Piel wrote:
> > 11/12/2007 10:16 AM, Thomas Renninger wrote/a écrit:
> > > On Sun, 2007-11-11 at 20:10 +0100, Eric Piel wrote:
> > >> Hello,
> > >>
> > >> I've tried kernel 2.6.24-rc2 and I have a problem with the new option
> > >> for setting up the cpufreq ondemand governor as default: a kernel panic
> > >> happens early at boot time. If I boot first with performance governor
> > >> and later change to ondemand, everything is fine (as usual).
> > >>
> > >> This seems related to the delayed_workqueue. The kernel panic message
> > >> finishes by:
> > >> EIP: [<c012aa60>] wq_per_cpu+0x0/0x10 SS:ESP 0068:c191be58
> > >> Kernel panic - not syncing: Attempted to kill init!
> > >>
> > >> A picture of the whole message is available here:
> > >> http://pieleric.free.fr/unorder/1162-ondemand-panic.jpg
> > >>
> > >> My computer is a x86 using speedstep-ich, and you can find the full
> > >> .config leading to the panic attached.
> > >>
> > >> Does anyone has any idea was it going wrong?
> > >
> > > Does it work if you compile speedstep-ich as a module?
> > > If you load it, ondemand governor should still be set up automatically.
> > > If this works, could it be that the kernel does not like that
> > > queue_delayed_work_on is called that early?
> >
> > Yes, it works if I compile speedstep-ich as module. I've put the module
> > in initramfs and as soon it is loaded, the ondemand governor is selected
> > and works.
> >
> > However, do you think it's ok to prevent cpufreq drivers to be built-in
> > if ondemand governor is selected as default?
> > Another way would be to
> > reorganise the initialisation code so that workqueue is initialised
> > before the cpufreq framework is started, do you think it's possible?
> Making all this work with low-level drivers built in would be perfect of
> course...
> If nobody answers the next days, could you open a bug at
> bugzilla.kernel.org, so that this does not get lost, pls.
> Add myself and Venkatesh to CC...
> I try to have a look at it ASAP.
> If someone already finds out more, this would be great.

I'm actually surprised that speedstep-ich works with a low enough
latency for ondemand. On the kernel that works, can you boot
with cpufreq.debug=7 and send the cpufreq messages from dmesg?

Dave

--