CIK hangs with kernel 3.15, bisected

[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
>>>