linux-kernel - Re: Deadlock?

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Date:	Tue, 14 Feb 2012 13:47:35 +0100
From:	Jan Kara <jack@...e.cz>
To:	Jack Stone <jwjstone@...tmail.fm>
Cc:	Markus <M4rkusXXL@....de>, lkml <linux-kernel@...r.kernel.org>,
	jack@...e.cz, akpm@...ux-foundation.org, adilger.kernel@...ger.ca,
	gregkh@...uxfoundation.org
Subject: Re: Deadlock?

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@...e.cz>
SUSE Labs, CR

View attachment "0001-quota-Make-quota-code-not-call-tty-layer-with-dqptr_.patch" of type "text/x-patch" (16617 bytes)