[crash, bisected] Re: clocksource: Resolve cpu hotplug dead lockwith TSC unstable

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> 
> * Jens Axboe <jens.axboe@xxxxxxxxxx> 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@xxxxxxxxxxxxx>
 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.

	Ingo
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