From: Dave Chinner <david@fromorbit.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: xfs <linux-xfs@vger.kernel.org>
Subject: Re: generic/475 deadlock?
Date: Thu, 21 Mar 2019 08:39:33 +1100 [thread overview]
Message-ID: <20190320213933.GT23020@dastard> (raw)
In-Reply-To: <20190320050408.GA24923@magnolia>
On Tue, Mar 19, 2019 at 10:04:08PM -0700, Darrick J. Wong wrote:
> Hmmm.
>
> Every now and then I see a generic/475 deadlock that generates the
> hangcheck warning pasted below.
>
> I /think/ this is ... the ail is processing an inode log item, for which
> it locked the cluster buffer and pushed the cil to unpin the buffer.
> However, the cil is cleaning up after the shut down and is trying to
> simulate an EIO completion, but tries grabs the buffer lock and hence
> the cil and ail deadlock. Maybe the solution is to trylock in the
> (freed && remove) case of xfs_buf_item_unpin, since we're tearing the
> whole system down anyway?
Oh, that's looks like a bug in xfs_iflush() - we are forcing the log
to unpin a buffer we already own the lock on. It's the same problem
we had in the discard code fixed by commit 8c81dd46ef3c ("Force log
to disk before reading the AGF during a fstrim").
It also means that the log forces in the busy extent code have the
same potential problem, as does xfs_qm_dqflush().
I'll move further down the discussion now....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
prev parent reply other threads:[~2019-03-20 21:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 5:04 generic/475 deadlock? Darrick J. Wong
2019-03-20 17:03 ` Brian Foster
2019-03-20 17:45 ` Darrick J. Wong
2019-03-20 17:59 ` Brian Foster
2019-03-20 21:49 ` Dave Chinner
2019-03-21 12:11 ` Brian Foster
2019-03-21 21:10 ` Dave Chinner
2019-03-21 21:53 ` Brian Foster
2019-03-21 23:50 ` Dave Chinner
2019-03-22 0:07 ` Darrick J. Wong
2019-03-22 12:01 ` Brian Foster
2019-03-24 23:03 ` Dave Chinner
2019-03-25 12:34 ` Brian Foster
2019-03-27 1:22 ` Dave Chinner
2019-03-26 17:13 ` Brian Foster
2019-03-27 1:05 ` Dave Chinner
2019-03-27 14:13 ` Brian Foster
2019-03-20 21:39 ` Dave Chinner [this message]
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