nouveau. swiotlb: coherent allocation failed for device 0000:01:00.0 size=2097152

[Ilia Mirkin]

On Tue, Dec 19, 2017 at 8:45 AM, Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
> Am 19.12.2017 um 11:39 schrieb Michel Dänzer:
>>
>> On 2017-12-19 11:37 AM, Michel Dänzer wrote:
>>>
>>> On 2017-12-18 08:01 PM, Tobias Klausmann wrote:
>>>>
>>>> On 12/18/17 7:06 PM, Mike Galbraith wrote:
>>>>>
>>>>> Greetings,
>>>>>
>>>>> Kernel bound workloads seem to trigger the below for whatever reason.
>>>>>    I only see this when beating up NFS.  There was a kworker wakeup
>>>>> latency issue, but with a bandaid applied to fix that up, I can still
>>>>> trigger this.
>>>>
>>>>
>>>> Hi,
>>>>
>>>> i have seen this one as well with my system, but i could not find an
>>>> easy way to trigger it for bisecting purpose. If you can trigger it
>>>> conveniently, a bisect would be nice!
>>>
>>> I'm seeing this (with the amdgpu and radeon drivers) when restic takes a
>>> backup, creating memory pressure. I happen to have just finished
>>> bisecting, the result is:
>>>
>>> 648bc3574716400acc06f99915815f80d9563783 is the first bad commit
>>> commit 648bc3574716400acc06f99915815f80d9563783
>>> Author: Christian König <christian.koenig at amd.com>
>>> Date:   Thu Jul 6 09:59:43 2017 +0200
>>>
>>>      drm/ttm: add transparent huge page support for DMA allocations v2
>>>
>>>      Try to allocate huge pages when it makes sense.
>>>
>>>      v2: fix comment and use ifdef
>>>
>>>
>> BTW, I haven't noticed any bad effects other than the dmesg splats, so
>> maybe it's just noise about transient failures for which there is a
>> proper fallback in place.
>
>
> Yeah, I think that is exactly what happens here.
>
> We try to allocate a huge page, but fail and so fall back to using multiple
> 4k pages instead.
>
> Going to send out a patch to suppress the warning.

Hi Christian,

Did you ever send out such a patch? I didn't see one on the list, but
perhaps I missed it. One definitely hasn't made it upstream yet. (I
just hit the issue myself with Linus's tree from last night.)

Thanks,

  -ilia