[PATCH 2/4] drm/amdkfd: Signal page table fence after KFD flush tlb

[Christian König]

Am 01.06.23 um 21:31 schrieb Philip Yang:
> To free page table BOs which are freed when updating page table, for
> example PTE BOs when PDE0 used as PTE.
>
> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_process.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index af0a4b5257cc..0ff007a74d03 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -2101,6 +2101,11 @@ void kfd_flush_tlb(struct kfd_process_device *pdd, enum TLB_FLUSH_TYPE type)
>   			amdgpu_amdkfd_flush_gpu_tlb_pasid(
>   				dev->adev, pdd->process->pasid, type, xcc);
>   	}
> +
> +	/* Signal page table fence to free page table BOs */
> +	dma_fence_signal(vm->pt_fence);

That's not something you can do here.

Signaling a fence can never depend on anything except for hardware work. 
In other words dma_fence_signal() is supposed to be called only from 
interrupt context!

What we can to is to put the TLB flushing into an irq worker or work 
item and let the signaling happen from there.

Amar and Shashank are already working on this, I strongly suggest to 
sync up with them.

Regards,
Christian.

> +	dma_fence_put(vm->pt_fence);
> +	vm->pt_fence = amdgpu_pt_fence_create();
>   }
>   
>   struct kfd_process_device *kfd_process_device_data_by_id(struct kfd_process *p, uint32_t gpu_id)