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

[Ilia Mirkin]

On Sun, Dec 31, 2017 at 3:53 PM, Mike Galbraith <efault@xxxxxx> wrote:
> On Sun, 2017-12-31 at 13:27 -0500, Ilia Mirkin wrote:
>> On Tue, Dec 19, 2017 at 8:45 AM, Christian KÃnig
>> <ckoenig.leichtzumerken@xxxxxxxxx> wrote:
>> > Am 19.12.2017 um 11:39 schrieb Michel DÃnzer:
>> >>
>> >> On 2017-12-19 11:37 AM, Michel DÃnzer 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 KÃnig <christian.koenig@xxxxxxx>
>> >>> 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.)
>
> Actually, that wants a bit more methinks, because while the stack dump
> goes away, you still get spammed, it just comes in smaller chunks.

OK, well this has to either be fixed or reverted. Right now it's
complaining all the time for me after like a day of uptime.

  -ilia