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Subject: Re: [dm-devel] AMD-Vi IO_PAGE_FAULTs and ata3.00: failed command:
 READ FPDMA QUEUED errors since Linux 4.0
To: Christoph Hellwig <hch@lst.de>,
	device-mapper development <dm-devel@redhat.com>,
	mpatocka@redhat.com, Milan Broz <mbroz@redhat.com>,
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 <20150728175054.GB24782@redhat.com> <55B7D054.4070308@maya.org>
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Cc: linux-pci <linux-pci@vger.kernel.org>
From: Andreas Hartmann <andihartmann@freenet.de>
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Date: Sun, 2 Aug 2015 15:38:38 +0200
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On 08/01/2015 at 04:20 PM Andreas Hartmann wrote:
> On 07/28/2015 at 09:29 PM, Mike Snitzer wrote:
> [...]
>> Mikulas was saying to biect what is causing ATA to fail.
> 
> Some good news and some bad news. The good news first:
> 
> Your patchset
> 
> f3396c58fd8442850e759843457d78b6ec3a9589,
> cf2f1abfbd0dba701f7f16ef619e4d2485de3366,
> 7145c241a1bf2841952c3e297c4080b357b3e52d,
> 94f5e0243c48aa01441c987743dc468e2d6eaca2,
> dc2676210c425ee8e5cb1bec5bc84d004ddf4179,
> 0f5d8e6ee758f7023e4353cca75d785b2d4f6abe,
> b3c5fd3052492f1b8d060799d4f18be5a5438add
> 
> seems to work fine w/ 3.18.19 !!
> 
> Why did I test it with 3.18.x now? Because I suddenly got two ata errors
> (ata1 and ata2) with clean 3.19.8 (w/o the AMD-Vi IO_PAGE_FAULTs) during
> normal operation. This means: 3.19 must already be broken, too.
> 
> Therefore, I applied your patchset to 3.18.x and it seems to work like a
> charme - I don't get any AMD-Vi IO_PAGE_FAULTs on boot and no ata errors
> (until now).
> 
> 
> Next I did: I tried to bisect between 3.18 and 3.19 with your patchset
> applied, because w/ this patchset applied, the problem can be seen
> easily and directly on boot. Unfortunately, this does work only a few
> git bisect rounds until I got stuck because of interferences with your
> extra patches applied:

[Resolved the problems written at the last post.]

Bisecting ended here:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=34b48db66e08ca1c1bc07cf305d672ac940268dc

block: remove artifical max_hw_sectors cap


Removing this patch on 3.19 and 4.1 make things working again. Didn't
test 4.0, but I think it's the same. No more AMD-Vi IO_PAGE_FAULTS  with
that patch reverted.


Please check why this patch triggers AMD-Vi IO_PAGE_FAULTS.


Thanks,
kind regards,
Andreas Hartmann