From: Arnd Bergmann <arnd@arndb.de>
To: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: Anton Altaparmakov <aia21@cam.ac.uk>, Jan Kara <jack@suse.cz>,
codalist@coda.cs.cmu.edu, autofs@linux.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
Christoph Hellwig <hch@infradead.org>,
Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Anders Larsen <al@alarsen.net>,
Evgeniy Dushistov <dushistov@mail.ru>,
Ingo Molnar <mingo@elte.hu>,
netdev@vger.kernel.org, Samuel Ortiz <samuel@sortiz.org>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Andrew Hendry <andrew.hendry@gmail.com>
Subject: Re: Remaining BKL users, what to do
Date: Tue, 21 Sep 2010 22:01:37 +0200 [thread overview]
Message-ID: <201009212201.37372.arnd@arndb.de> (raw)
In-Reply-To: <ead83d0d-e0ae-456d-8702-16ed8d3a179a@email.android.com>
On Saturday 18 September 2010 01:21:41 Petr Vandrovec wrote:
>
> I'll try to come up with something for ncpfs.
Ok, good.
> Trivial lock replacement will open deadlock possibility when
> someone reads to page which is also mmaped from the same
> filesystem (like grep likes to do). BKL with its automated
> release on sleep helped (or papered over) a lot here.
Right, I was more or less expecting something like this.
So I guess this is some AB-BA deadlock with another mutex
or a call to flush_scheduled_work that is currently done
under the BKL?
There is still the possibility of just working around those
by adding explicit mutex_unlock() calls around those, which
is what I initially did in the tty subsystem. The better
long-term approach would obviously be to understand all of
the data structures that actually need locking and only
lock the actual accesses, but that may be more work than
you are willing to spend on it.
Arnd
next prev parent reply other threads:[~2010-09-21 20:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-17 23:21 Remaining BKL users, what to do Petr Vandrovec
2010-09-21 20:01 ` Arnd Bergmann [this message]
-- strict thread matches above, loose matches on Subject: below --
2010-09-16 14:32 Arnd Bergmann
2010-09-16 14:49 ` Steven Rostedt
2010-09-16 18:32 ` Jens Axboe
2010-09-17 18:46 ` Arnd Bergmann
2010-09-16 15:04 ` Jan Kara
2010-09-16 21:26 ` Anton Altaparmakov
2010-09-17 10:45 ` Arnd Bergmann
2010-09-17 13:32 ` Christoph Hellwig
2010-09-17 13:50 ` Arnd Bergmann
2010-09-17 14:02 ` Christoph Hellwig
2010-09-17 14:56 ` Arnd Bergmann
2010-09-16 15:07 ` Alan Cox
2010-09-16 20:08 ` David Miller
2010-09-16 16:09 ` Anders Larsen
2010-09-16 16:57 ` Samuel Ortiz
2010-09-16 20:08 ` David Miller
2010-09-16 19:00 ` Jan Harkes
2010-09-16 19:26 ` Arnd Bergmann
2010-10-21 12:47 ` Christoph Hellwig
2010-10-21 13:38 ` Arnd Bergmann
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