Re: [dm-devel] AMD-Vi IO_PAGE_FAULTs and ata3.00: failed command: READ FPDMA QUEUED errors since Linux 4.0

[Joerg Roedel <joro@8bytes.org>]

On Wed, Oct 07, 2015 at 06:52:58PM +0200, Andreas Hartmann wrote:
> To reproduce the error:
> First I mounted /daten2, afterwards /raid/mt, which produces the errors.
> The ssd mounts have been already active (during boot by fstab).

Okay, I spent the day on that problem, and managed to reproduce it here
on one of my AMD IOMMU boxes. I wasn't an easy journey, as I can only
reproduce it if I setup the crypto partition and everything above that
(like mounting the lvm volumes) _after_ the system has finished booting.
If everything is setup during system boot it works fine and I don't see
any IO_PAGE_FAULTS.

I also tried kernel v4.3-rc4 first, to have it tested with a
self-compiled kernel. It didn't show up there, so I built a 4.1.0, where
it showed up again. Something seems to have fixed the issue in the
latest kernels.

So I looked a little bit around at the commits that were merged into the
respective parts involved here, and found this one:

	586b286 dm crypt: constrain crypt device's max_segment_size to PAGE_SIZE

The problem fixed with this commit looks quite similar to what you have
seen (execpt that there was no IOMMU involved). So I cherry-picked that
commit on 4.1.0 and tested that. The problem was gone.

So it looks like it was a dm-crypt issue, the patch went into v4.3-rc3,
either this kernel of rc4 should fix the problem for you too. Can you
please verify this is fixed for you too with v4.3-rc4?


Thanks,

	Joerg