Using drm_exec for TTMs BO eviction

[Thomas Hellström]

Hi, Christian,

On Wed, 2024-07-03 at 15:25 +0200, Christian König wrote:
> Hi guys,
> 
> We recently ran into a problem with deadlocks during eviction and
> while back Thomas worked on a patch set which was going into the
> direction of solving this.
> 
> So I simplified it to just the functionality needed to resolve this
> issue at. The resulting patch set is just the initial first step of
> using drm_exec in TTM for locking BOs during eviction.
> 
> Should a deadlock happen the drm_exec object is now used to resolve
> it and prelock the contended object. This approach solves this the
> ENOMEM issue on contending evictions quite nicely.
> 
> Please review and comment,
> Christian.

Overall it looks sane, but I think it makes sense to review and  land
the part of the shrinker series first that touches this eviction path
and gets rid of a lot of code that's hard to understand and simplifies
the locking a lot. (That part doesn't touch drm_exec), and it has been
pending reviews for some time.

I don't think it's correct to bypass that. Then we could work out the
drm_exec implications.

/Thomas


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