Re: [OOPS] 2.6.21-rc6-git5 in cfq_dispatch_insert

[Roland Kuhn <rkuhn@e18.physik.tu-muenchen.de>]

Hi Jens!

On 25 Apr 2007, at 12:18, Jens Axboe wrote:

> On Wed, Apr 25 2007, Brad Campbell wrote:
> > Jens Axboe wrote:
> >
> > > It looks to be extremely rare. Aliases are extremely rare, front  
> > > merges
> > > are rare. And you need both to happen with the details you  
> > > outlined. But
> > > it's a large user base, and we've had 3-4 reports on this in the  
> > > past
> > > months. So it obviously does happen. I could not make it trigger  
> > > without
> > > doctoring the unplug code when I used aio.
> >
> > Well, not that rare on this particular machine (I had a case where  
> > I could
> > reproduce it in less than an hour of normal use previously on this  
> > box),
> > and I've had it occur a number of times on my servers, I just never
> > reported it before as I never took the time to set up a serial  
> > console and
> > capture the oops.
>
> Extremely rare in the sense that it takes md and some certain  
> conditions
> to happen for it to trigger. So for most people it'll be extremely  
> rare,
> and for others (such as yourself) that hit it, it wont be so rare :-)
>
> > > Here's a fix for it, confirmed.
> >
> > Shall I leave the other debugging in, apply this and run it for a  
> > few hard
> > days?
>
> Yes, that would be perfect!
Okay, I left all debugging patches in, disabled all kernel  
debugging .config stuff and gave it a spin with our usual "killer"  
workload (as far as batch systems are repeatable anyway) and so far  
there was not a single glitch or message, so I preliminarily conclude  
that the bug is squashed. The final word will come once my 1800 batch  
jobs are processed and I have my particle physics result ;-)

Ciao,
                    Roland

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