From: Markus <M4rkusXXL@web.de>
To: lkml <linux-kernel@vger.kernel.org>
Cc: Jan Kara <jack@suse.cz>, Jack Stone <jwjstone@fastmail.fm>,
        akpm@linux-foundation.org, adilger.kernel@dilger.ca,
        gregkh@linuxfoundation.org
Subject: Re: Deadlock?
Date: Wed, 15 Feb 2012 12:42:45 +0100
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Hi!

/proc/sysrq-trigger does not exists, I will apply the patch and enable sysrq.
But it may take some days for a result.

Thanks,
Markus

Jan Kara schrieb am 14.02.2012:
> On Mon 13-02-12 17:37:34, Jack Stone wrote:
> > Adding CCs
> > 
> > On 02/13/2012 11:17 AM, Markus wrote:
> > > I noted some kind of deadlock, where I was not able to write to the raid6, 
> > > while writing to each disk would still work.
> > > This caused many processes to "wait" in d-state, thus making it impossible to 
> > > unmount, cleanly reboot, sync, ...
>   Thanks for report. Could you please provide output of
>     'echo w >/proc/sysrq-trigger'
> in dmesg? That would help us narrow down the real cause the the current
> deadlock.
> 
> > > So I enabled the detection of hung tasks and this deplock option.
> > > After running a 3.2.2 for about 5 days:
> > > http://pastebin.com/gy1kaYmS
> > > 
> > > I dont know if its a bug or nothing. Or if it has anything to do with my 
> > > problem as there was no hungtask detected and the raid still seems to work.
>   It's lock debugging code complaining about a possible problem it found.
> Actually, the problem looks real (although hard to hit AFAICS) and attached
> patch should fix it. Does the patch fix things for you? If not, please
> provide the output I describe above.
> 
> 									Honza
> -- 
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR
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