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

[Andreas Hartmann <andihartmann@freenet.de>]

On 08/02/2015 at 07:57 PM, Mikulas Patocka wrote:
> 
> 
> On Sun, 2 Aug 2015, Andreas Hartmann wrote:
> 
>> 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.

After long period of testing, I now can say, that max_sectors_kb can be
set to 1024 - higher values produce AMD-Vi IO_PAGE_FAULTS and ata faults.


This patch "sd: Fix maximum I/O size for BLOCK_PC requests"[1] as part
of 4.1.7 produces ata / AMD-Vi IO_PAGE_FAULTS already during boot, too -
no matter if "block: remove artifical max_hw_sectors cap"[2] has been
applied or not.


Next I tested was "dm crypt: constrain crypt device's max_segment_size
to PAGE_SIZE" patch[3] applied to an unchanged 4.1.7 kernel w/o setting
max_sectors_kb to 1024.

Interesting effect was, that booting has been fine, but I could see lots
of ata errors afterwards as soon as there is load on the md raid 1
(during kernel compile e.g.), which is built on *rotational* disks:


[  367.264873] ata2.00: exception Emask 0x0 SAct 0x7fbfffff SErr 0x0
action 0x6 frozen
[  367.264883] ata2.00: failed command: WRITE FPDMA QUEUED
[  367.264893] ata2.00: cmd 61/40:00:b0:7b:d4/05:00:06:00:00/40 tag 0
ncq 688128 out
[  367.264893]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask
0x4 (timeout)
[  367.264899] ata2.00: status: { DRDY }
...
[  367.265332] ata2.00: failed command: WRITE FPDMA QUEUED
[  367.265339] ata2.00: cmd 61/40:f0:30:71:d4/05:00:06:00:00/40 tag 30
ncq 688128 out
[  367.265339]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask
0x4 (timeout)
[  367.265343] ata2.00: status: { DRDY }
[  367.265350] ata2: hard resetting link
[  367.775330] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[  367.776970] ata2.00: configured for UDMA/133
[  367.776997] ata2.00: device reported invalid CHS sector 0
...
[  367.777761] ata2: EH complete


Iow: Using an unpatched kernel >= 3.19 means high risk to break
filesystems if there are given some yet unknown conditions [4].

>>
>>
>> Please check why this patch triggers AMD-Vi IO_PAGE_FAULTS.
> 
> I would submit this bug to maintainers of AMD-Vi. They understand the 
> hardware, so they should tell why do large I/O requests result in 
> IO_PAGE_FAULTs.
> 
> It is probably bug either in AMD-Vi driver or in hardware.

Until now, I didn't hear anything from the maintainers of AMD-Vi.


Regards,
Andreas Hartmann


[1] http://thread.gmane.org/gmane.linux.kernel.commits.head/538464
[2]
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=34b48db66e08ca1c1bc07cf305d672ac940268dc
[3]
http://news.gmane.org/find-root.php?group=gmane.linux.kernel&article=2036495
[4] http://thread.gmane.org/gmane.linux.kernel.pci/43851/focus=44011