Messages in this thread | | | Date | Tue, 30 May 2006 07:52:15 +0200 | From | "Michal Piotrowski" <> | Subject | Re: [patch 00/61] ANNOUNCE: lock validator -V1 |
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Hi,
On 30/05/06, Dave Jones <davej@redhat.com> wrote: > On Tue, May 30, 2006 at 12:41:08AM +0200, Ingo Molnar wrote: > > > > ===================================================== > > > [ BUG: possible circular locking deadlock detected! ] > > > ----------------------------------------------------- > > > modprobe/1942 is trying to acquire lock: > > > (&anon_vma->lock){--..}, at: [<c10609cf>] anon_vma_link+0x1d/0xc9 > > > > > > but task is already holding lock: > > > (&mm->mmap_sem/1){--..}, at: [<c101e5a0>] copy_process+0xbc6/0x1519 > > > > > > which lock already depends on the new lock, > > > which could lead to circular deadlocks! > > > > hm, this one could perhaps be a real bug. Dave: lockdep complains about > > having observed: > > > > anon_vma->lock => mm->mmap_sem > > mm->mmap_sem => anon_vma->lock > > > > locking sequences, in the cpufreq code. Is there some special runtime > > behavior that still makes this safe, or is it a real bug? > > I'm feeling a bit overwhelmed by the voluminous output of this checker. > Especially as (directly at least) cpufreq doesn't touch vma's, or mmap's. > > The first stack trace it shows has us down in the bowels of cpu hotplug, > where we're taking the cpucontrol sem. The second stack trace shows > us in cpufreq_update_policy taking a per-cpu data->lock semaphore. > > Now, I notice this is modprobe triggering this, and this *looks* like > we're loading two modules simultaneously (the first trace is from a > scaling driver like powernow-k8 or the like, whilst the second trace > is from cpufreq-stats).
/etc/init.d/cpuspeed starts very early $ ls /etc/rc5.d/ | grep cpu S06cpuspeed
I have this in my /etc/rc.local modprobe -i cpufreq_conservative modprobe -i cpufreq_ondemand modprobe -i cpufreq_powersave modprobe -i cpufreq_stats modprobe -i cpufreq_userspace modprobe -i freq_table
> > How on earth did we get into this situation?
Just before gdm starts, while /etc/rc.local is processed.
> module loading is supposed > to be serialised on the module_mutex no ? > > It's been a while since a debug patch has sent me in search of paracetamol ;) > > Dave
Regards, Michal
-- Michal K. K. Piotrowski LTG - Linux Testers Group (http://www.stardust.webpages.pl/ltg/wiki/) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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