CIK hangs with kernel 3.15, bisected

[Marek Olšák]

Hi Christian,

Even though some regressions are fixed by these patches:

drm/radeon: fix page directory update size estimation
drm/radeon: fix buffer placement under memory pressure v2

and indeed, the texelFetch tests no longer hang, there is one more
hang which needs to be fixed. :( All I know is the exact same commit
causes it and it can only be reproduced by running whole piglit with
concurrency enabled.

My kernel git log:

* 2ba22c8 - drm/radeon: fix buffer placement under memory pressure v2
(10 hours ago) <Christian König>
* 3af91e5 - drm/radeon: fix page directory update size estimation (21
hours ago) <Christian König>
* 6d2f294 - drm/radeon: use normal BOs for the page tables v4 (2
months ago) <Christian König>
* fa68834 - drm/radeon: further cleanup vm flushing & fencing (2
months ago) <Christian König>

fa68834 doesn't hang, but 2ba22c8 hangs, which means 6d2f294 or either
of the two fixes is the first bad commit.

Marek

On Fri, May 9, 2014 at 8:03 PM, Marek Olšák <maraeo at gmail.com> wrote:
> Hi Christian,
>
> This commit which first appeared in 3.15-rc1 causes hangs on Bonaire:
>
> commit 6d2f2944e95e504a7d33385eeeb9bb7fcca72592
> Author: Christian König <christian.koenig at amd.com>
> Date:   Thu Feb 20 13:42:17 2014 +0100
>
>     drm/radeon: use normal BOs for the page tables v4
>
>     No need to make it more complicated than necessary,
>     just allocate the page tables as normal BO and
>     flush whenever the address change.
>
>     v2: update comments and function name
>     v3: squash bug fixes, page directory and tables patch
>     v4: rebased on Mareks changes
>
>     Signed-off-by: Christian König <christian.koenig at amd.com>
>
>
> Reverting the commit gives me a lot of merge conflicts.
>
> 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.
>
> Any idea what is wrong with it?
>
> Thanks,
>
> Marek