CIK hangs with kernel 3.15, bisected

[Christian König]

I could reproduce the problem with xonotic and I think I've found the issue.

Please test the attached patch.

Thanks,
Christian.

Am 11.05.2014 11:06, schrieb Christian König:
>> I have tested it and it doesn't fix the hangs.
> Yeah, thought so. Well it was just a guess.
>
>> (Also, I don't like the patch, because it reverts the behavior I added
>> for userspace buffers.)
> Actually it shouldn't affect that. The alternative domain always 
> contains GART even when userspace only specified VRAM as placement (as 
> long as it is technical possible to do so).
>
> So what should happen is that TTM sees the current placement, matches 
> that with the desired placement and should find that it doesn't need 
> to move the buffer (we should just test if this behavior really works 
> as expected).
>
> Christian.
>
> Am 10.05.2014 23:38, schrieb Marek Olšák:
>> Hi Christian,
>>
>> I have tested it and it doesn't fix the hangs.
>>
>> (Also, I don't like the patch, because it reverts the behavior I added
>> for userspace buffers.)
>>
>> Marek
>>
>>
>>
>> On Sat, May 10, 2014 at 6:34 PM, Christian König
>> <deathsimple at vodafone.de> wrote:
>>> Couldn't reproduce the issue so far. So the attached patch is just a
>>> complete shoot into the dark found by rereading the code, but it might
>>> actually be the problem.
>>>
>>> Please give it a try.
>>>
>>> Going to keep testing in the meantime,
>>> Christian.
>>>
>>> Am 10.05.2014 10:23, schrieb Christian König:
>>>
>>>>> I see hangs with kernel 3.15 and SI under memory pressure, e.g. if 
>>>>> I boot
>>>>> with radeon.vramlimit=256 and then run Xonotic timedemo with high 
>>>>> settings.
>>>>> I haven't had a chance to bisect it yet, but it might be a similar 
>>>>> problem.
>>>> Sounds like the same issue to me. Thx for the good test case.
>>>>
>>>>> Any idea what is wrong with it?
>>>> Actually I already wondered that it went so smooth without any 
>>>> regression
>>>> so far, didn't noticed the bug in bugzilla.kernel.org yet.
>>>>
>>>>> Some of the tests allocate a lot of MSAA textures and the tests also
>>>>> run in parallel, which creates a lot of memory pressure and probably
>>>>> causes buffer evictions.
>>>> Sounds like the underlying problem to me. We probably evict some 
>>>> part of a
>>>> page table without updating the page directory. Going to dig into 
>>>> it today,
>>>> it's probably just a one liner missing somewhere in the VM code.
>>>>
>>>> Christian.
>>>>
>>>> Am 09.05.2014 23:39, schrieb Grigori Goronzy:
>>>>> On 09.05.2014 20:03, Marek Olšák wrote:
>>>>>>
>>>>>> This commit which first appeared in 3.15-rc1 causes hangs on 
>>>>>> Bonaire:
>>>>>> [...]
>>>>>>
>>>>>> The simplest way to reproduce the hangs is to run piglit with these
>>>>>> parameters:
>>>>>> -t texelFetch.fs
>>>>>>
>>>>>> Some of the tests allocate a lot of MSAA textures and the tests also
>>>>>> run in parallel, which creates a lot of memory pressure and probably
>>>>>> causes buffer evictions.
>>>>>>
>>>>> I see hangs with kernel 3.15 and SI under memory pressure, e.g. if 
>>>>> I boot
>>>>> with radeon.vramlimit=256 and then run Xonotic timedemo with high 
>>>>> settings.
>>>>> I haven't had a chance to bisect it yet, but it might be a similar 
>>>>> problem.
>>>>>
>>>>> Grigori
>>>>
>

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