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SubjectRe: [crash, bisected] Re: clocksource: Resolve cpu hotplug dead lock with TSC unstable
On Fri, 11 Sep 2009 09:37:47 +0200
Ingo Molnar <mingo@elte.hu> wrote:

>
> * Ingo Molnar <mingo@elte.hu> wrote:
>
> >
> > * Ingo Molnar <mingo@elte.hu> wrote:
> >
> > >
> > > * Jens Axboe <jens.axboe@oracle.com> wrote:
> > >
> > > > I went to try -tip btw, but it crashes on boot. Here's the
> > > > backtrace, typed manually, it's crashing in
> > > > queue_work_on+0x28/0x60.
> > > >
> > > > Call Trace:
> > > > queue_work
> > > > schedule_work
> > > > clocksource_mark_unstable
> > > > mark_tsc_unstable
> > > > check_tsc_sync_source
> > > > native_cpu_up
> > > > relay_hotcpu_callback
> > > > do_forK_idle
> > > > _cpu_up
> > > > cpu_up
> > > > kernel_init
> > > > kernel_thread_helper
> > >
> > > hm, that looks like an old bug i fixed days ago via:
> > >
> > > 00a3273: Revert "x86: Make tsc=reliable override boot time stability checks"
> > >
> > > Have you tested tip:master - do you still know which sha1?
> >
> > Ok, i reproduced it on a testbox and bisected it, the crash is
> > caused by:
> >
> > 7285dd7fd375763bfb8ab1ac9cf3f1206f503c16 is first bad commit
> > commit 7285dd7fd375763bfb8ab1ac9cf3f1206f503c16
> > Author: Thomas Gleixner <tglx@linutronix.de>
> > Date: Fri Aug 28 20:25:24 2009 +0200
> >
> > clocksource: Resolve cpu hotplug dead lock with TSC unstable
> >
> > Martin Schwidefsky analyzed it:
> >
> > I've reverted it in tip/master for now.
>
> and that uncovers the circular locking bug that this commit was
> supposed to fix ...
>
> Martin?

Damn, back to running around in circles ..

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.



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