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

[Andreas Hartmann <andihartmann@freenet.de>]

On 08/04/2015 at 08:11 PM, Andreas Hartmann wrote:
> On 08/04/2015 at 06:10 PM Jeff Moyer wrote:
>> Mike Snitzer <snitzer@redhat.com> writes:
>>
>>> On Mon, Aug 03 2015 at  4:12am -0400,
>>> Joerg Roedel <joro@8bytes.org> wrote:
>>>
>>>> On Sun, Aug 02, 2015 at 08:48:06PM +0200, Andreas Hartmann wrote:
>>>>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=34b48db66e08ca1c1bc07cf305d672ac940268dc
>>>>>>>
>>>>>>> block: remove artifical max_hw_sectors cap
>>>>
>>>> Looking at the patch, it seems to me that it just uncovered a bug
>>>> elsewhere. It looks like an underlying driver doesn't expect the
>>>> big io-requests that the patch enables and does not dma-map the whole
>>>> target buffer, causing the IO_PAGE_FAULTs later.
>>>
>>> That patch has caused issues elsewhere too, see this 'Revert "block:
>>> remove artifical max_hw_sectors cap"' thread (if/when lkml.org
>>> cooperates): https://lkml.org/lkml/2015/7/20/572
>>>
>>> But it could be that there is a need for a horkage fix for this specific
>>> hardware? something comparable to this?:
>>> http://git.kernel.org/linus/af34d637637eabaf49406eb35c948cd51ba262a6
>>>
>>> We are running out of time to fix these whack-a-mole issues in 4.2
>>> though.
>>
>> CC-ing linux-ide.  Original dm-devel posting:
>>   https://www.redhat.com/archives/dm-devel/2015-July/msg00178.html
>>
>> Andreas, I would be curious to know what the value of
>> /sys/block/sdX/queue/max_hw_sectors_kb is for the affected disks.
> 
> 
> It's always 32767.
> 
> Where does this value come from? Is it empirical or is it calculated (on
> base of which parameters)?
> 
> 
> Devices are:
> 
> 1 x Corsair Force GT (SSD)
> 2 x ST3000DM001-1CH166 (rotational) (WD)
> 
> 
> How can I set a higher max_sectors_kb on boot before the partitions are
> mounted (-> as kernel option)? Mounting the partitions here (w/ systemd)
> is the easiest and best way to trigger the problem!

Please - no idea how to set higher max_sectors_kb before mounting of
partitions? Come on! I want to test exactly this situation!


Regards,
Andreas