linux-kernel - Re: dquot.c: possible circular locking Re: [2.6.20] BUG: workqueue leaked lock

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Message-Id: <1174397710.1158.75.camel@laptopd505.fenrus.org>
Date:	Tue, 20 Mar 2007 14:35:10 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	Jan Kara <jack@...e.cz>
Cc:	Jarek Poplawski <jarkao2@...pl>,
	Folkert van Heusden <folkert@...heusden.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...sign.ru>,
	Neil Brown <neilb@...e.de>, Christoph Hellwig <hch@....de>
Subject: Re: dquot.c: possible circular locking Re: [2.6.20] BUG: workqueue
	leaked lock



>   Yes, I was looking at it. Hmm, we can possibly get rid of tty_mutex being
> acquired under dqptr_sem in quota code. But looking at the path from
> con_close() there's another inversion with i_mutex which is also acquired
> along the path for sysfs. And we can hardly get rid of it in the quota code.
>   Now none of these is a real deadlock as quota should never call
> print_warning() for sysfs (it doesn't use quota) but still it's nasty. I
> suppose tty_mutex is above i_mutex because of those sysfs calls and it
> seems sysfs must be called under tty_mutex because of races with
> init_dev(). So it's not easy to get rid of that dependency either.

maybe a far more serious option: Why on EARTH is the quota code going to
TTY's directly? That's just WRONG. Maybe it wasn't 10 years ago, but
nowadays most people use graphical user interfaces and the like...

can we please just get rid of this instead?

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