From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@lst.de>
Cc: peterz@infradead.org, xfs@oss.sgi.com
Subject: Re: [PATCH, RFC] xfs: remove i_iolock and use i_rwsem in the VFS inode instead
Date: Thu, 8 Sep 2016 07:45:36 +1000 [thread overview]
Message-ID: <20160907214536.GQ30056@dastard> (raw)
In-Reply-To: <20160905151529.GB16726@lst.de>
On Mon, Sep 05, 2016 at 05:15:29PM +0200, Christoph Hellwig wrote:
> Hi Dave,
>
> I looked into killing the mrlock and ran into an unexpected problem.
>
> Currently mr_writer tracks that there is someone holding a write lock,
> lockdep on the other hand checks if the calling thread has that lock.
>
> While that generally is the right semantic, our hack to offload
> btree splits to a work item offends lockdep. E.g. this callstack
> now asserts:
It's a semaphore, not a mutex. Semaphore locking is independent of
task context, the lock follows the object it protects, not the task
that took the lock. i.e. Lockdep is wrong to assume the "owner" of a
rw_sem will not change between lock and unlock.
> While it previously did fine. I fear there might be other locking
> asserts in the code called from that work item as well.
Probably.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2016-09-07 21:45 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 17:10 [PATCH, RFC] xfs: remove i_iolock and use i_rwsem in the VFS inode instead Christoph Hellwig
2016-08-11 21:54 ` Peter Zijlstra
2016-08-18 17:37 ` Christoph Hellwig
2016-08-19 13:27 ` Peter Zijlstra
2016-08-20 6:37 ` Christoph Hellwig
2016-08-22 8:34 ` Peter Zijlstra
2016-09-05 15:12 ` Christoph Hellwig
2016-09-07 7:43 ` Peter Zijlstra
2016-09-08 6:06 ` Ingo Molnar
2016-08-11 23:43 ` Dave Chinner
2016-08-12 2:50 ` Christoph Hellwig
2016-08-12 9:58 ` Dave Chinner
2016-09-05 15:15 ` Christoph Hellwig
2016-09-07 21:45 ` Dave Chinner [this message]
2016-09-08 6:54 ` Peter Zijlstra
2016-09-09 1:06 ` Dave Chinner
2016-09-09 8:21 ` Peter Zijlstra
2016-09-09 8:34 ` Christoph Hellwig
2016-09-11 0:17 ` Dave Chinner
2016-09-13 19:42 ` Peter Zijlstra
2016-09-09 8:33 ` Christoph Hellwig
2016-09-09 8:44 ` Peter Zijlstra
2016-09-09 9:05 ` Christoph Hellwig
2016-09-09 9:51 ` Peter Zijlstra
2016-09-10 16:20 ` Christoph Hellwig
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