Re: Try to fix amdgpu's error handling

[Danilo Krummrich <dakr@kernel.org>]

On Tue, Mar 18, 2025 at 01:03:11PM +0100, Christian König wrote:
> Hi guys,
> 
> as partially discussed on the list already amdgpu has a bug in it's gang
> submission code.
> 
> Basic problem is to add the correct dependency to the gang leader we
> need to arm the other gang members first, but that is a point of no
> return and it is possible that adding the dependencies fails with
> ENOMEM.
> 
> Try to fix that by allowing drivers to preallocate dependency slots. Not
> sure if that is a good approach, but of hand I don't see much
> alternative.

I think that's reasonable, in GPUVM we have a similar problem where we have to
preallocate in order to avoid allocations under a mutex used in the fence
signalling critical path.

Unfortunately, this even prevented us from using the maple tree, since it can't
preallocate for multiple entries ahead of time.

From my side,

Acked-by: Danilo Krummrich <dakr@kernel.org>