Bad rss-counter state from drm/ttm, drm/vmwgfx: Support huge TTM pagefaults

[Alex Xu (Hello71)]

Excerpts from Thomas Hellström (VMware)'s message of April 7, 2020 7:26 am:
> On 4/7/20 2:38 AM, Alex Xu (Hello71) wrote:
>> Excerpts from Thomas Hellström (VMware)'s message of April 6, 2020 5:04 pm:
>>> Hi,
>>>
>>> On 4/6/20 9:51 PM, Alex Xu (Hello71) wrote:
>>>> Using 314b658 with amdgpu, starting sway and firefox causes "BUG: Bad
>>>> rss-counter state" and "BUG: non-zero pgtables_bytes on freeing mm" to
>>>> start filling dmesg, and then closing programs causes more BUGs and
>>>> hangs, and then everything grinds to a halt (can't start more programs,
>>>> can't even reboot through systemd).
>>>>
>>>> Using master and reverting that branch up to that point fixes the
>>>> problem.
>>>>
>>>> I'm using a Ryzen 1600 and AMD Radeon RX 480 on an ASRock B450 Pro4
>>>> board with IOMMU enabled.
>>> If you could try the attached patch, that'd be great!
>>>
>>> Thanks,
>>>
>>> Thomas
>>>
>> Yeah, that works too. Kernel config sent off-list.
>>
>> Regards,
>> Alex.
> 
> Thanks. Do you want me to add your
> 
> Reported-by: and Tested-by: To this patch?
> 
> /Thomas
> 
> 

Sure. Shouldn't we fix it properly though?