From: Jeff Moyer <jmoyer@redhat.com>
Subject: Re: dax pmd fault handler never returns to userspace
Date: Wed, 18 Nov 2015 13:32:46 -0500
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Cc: Dan Williams <dan.j.williams@intel.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@ml01.01.org>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	Ross Zwisler <ross.zwisler@intel.com>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
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In-Reply-To: <20151118182320.GA7901@linux.intel.com> (Ross Zwisler's message
	of "Wed, 18 Nov 2015 11:23:20 -0700")
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Ross Zwisler <ross.zwisler@linux.intel.com> writes:

> Yea, my first round of testing was broken, sorry about that.
>
> It looks like this test causes the PMD fault handler to be called repeatedly
> over and over until you kill the userspace process.  This doesn't happen for
> XFS because when using XFS this test doesn't hit PMD faults, only PTE faults.

Hmm, I wonder why not?  Sounds like that will need investigating as
well, right?

-Jeff

> So, looks like a livelock as far as I can tell.
>
> Still debugging.

Thanks!
Jeff