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Date: Mon, 18 Sep 2017 17:39:47 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [linux-next][XFS][trinity] WARNING: CPU: 32 PID: 31369 at
        fs/iomap.c:993
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References: <1505746565.6990.18.camel@abdul.in.ibm.com> <20170918152706.GA11482@lst.de> <8abed401-1634-760f-6543-4652fa495315@kernel.dk>
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To: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>, Abdul Haleem <abdhalee@linux.vnet.ibm.com>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, linux-xfs <linux-xfs@vger.kernel.org>, linux-next <linux-next@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, chandan <chandan@linux.vnet.ibm.com>

On Mon, Sep 18, 2017 at 09:28:55AM -0600, Jens Axboe wrote:
> If it's expected, why don't we kill the WARN_ON_ONCE()? I get it all
> the time running xfstests as well.

Dave insisted on it to decourage users/applications from mixing
mmap and direct I/O.

In many ways a tracepoint might be the better way to diagnose these.