linux-kernel - Re: R.I.P. pdflush

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Message-ID: <1343976814.1730.20.camel@sauron.fi.intel.com>
Date:	Fri, 03 Aug 2012 09:53:34 +0300
From:	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
To:	Jeff Mahoney <jeffm@...e.de>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Linux Kernel Maling List <linux-kernel@...r.kernel.org>,
	Linux FS Maling List <linux-fsdevel@...r.kernel.org>
Subject: Re: R.I.P. pdflush

On Thu, 2012-08-02 at 17:27 -0400, Jeff Mahoney wrote:
> On 7/25/12 11:11 AM, Artem Bityutskiy wrote:
> > For example, reiserfs deadlocked quickly when I tested it using
> > xfstests with resierfs quota support enabled. I spend several days
> > trying to fix this, but reiserfs is quite complex and I'd say its
> > locking is crazy (partially because of the BKL push-down). But I
> > gave up after I realized that the dead-lock is related to the quota
> > support. I disabled quotas and xfstests passed.
> 
> Thanks for mentioning this. This is due to both reiserfs_write_dquot
> and reiserfs_evict_inode taking the reiserfs_write_lock. The old
> reiserfs locking code depended on the recursive locking ability of the
> BKL and the push-down made that a special case. This case isn't
> handled so even though the write lock is supposed to be dropped to
> take the journal lock safely, it's not and we end up with an ABBA case
> there.
> 
> I'll work up a fix.

Thanks Jeff. Note, I sent the bug-report as well:
http://thread.gmane.org/gmane.linux.file-systems/64794/focus=23910

-- 
Best Regards,
Artem Bityutskiy

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