Re: 2.6.18-rc4-mm1

Andrew Morton
2006-08-14T21:47:17Z

On Mon, 14 Aug 2006 16:20:04 -0400
Dave Jones <davej@redhat.com> wrote:

> On Mon, Aug 14, 2006 at 01:55:56PM +0200, Ben Buxton wrote:
>
> > > > Also, whenever I echo anything to "scaling_governor", I get the
> > > > following kernel message:
> > > >
> > > > [ 734.156000] BUG: warning at kernel/cpu.c:38/lock_cpu_hotplug()
> > > > [ 734.156000] [<c013c3ec>] lock_cpu_hotplug+0x7c/0x90
> > > > [ 734.156000] [<c01327f4>] __create_workqueue+0x44/0x140
> > > > [ 734.156000] [<c02dcf7b>] mutex_lock+0xb/0x20
> > > > [ 734.156000] [<e01f2665>] cpufreq_governor_dbs+0x2b5/0x310 [cpufreq_ondemand]
> > >
> > > This makes no sense at all, because in -mm __create_workqueue doesn't
> > > call lock_cpu_hotplug().
> > >
> > > Are you sure this was from a tree with -mm1 applied ?
> >
> > Definitely 2.6.18-rc4-mm1, and I've done a clean rebuild + removal of
> > all modules under /lib/modules beforehand.
>
> It's a real mystery. Andrew ?
>

I'm suspecting it's just stack gunk. If Ben could send some more such
traces that'd clear things up. Also, turning on CONFIG_UNWIND_INFO,
CONFIG_STACK_UNWIND and perhaps CONFIG_FRAME_POINTER might give us a
cleaner backtrace.