Re: [PATCH v2] drm/i915/gem: Execbuffer objects must have struct pages.

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 3/12/2024 3:55 PM, Jonathan Cavitt wrote:
> We cannot write requests to objects without struct pages, so escape
> early if the requests are bound to objects that lack them.
>
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> ---
>
> v2: s/vma-obj/vma->obj
>
>   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index d3a771afb083e..adb4f9e78cb49 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -3313,6 +3313,13 @@ eb_requests_create(struct i915_execbuffer *eb, struct dma_fence *in_fence,
>   	unsigned int i;
>   
>   	for_each_batch_create_order(eb, i) {
> +		/* Do not write requests to objects without struct pages. */
> +		if (eb->batches[i]->vma &&
> +		    !i915_gem_object_has_struct_page(eb->batches[i]->vma->obj)) {

As far as I understand, motivation of this patch is to avoid doing 
execbuf on dmabuf imported BO which are in error state of something. 
i915_gem_object_has_struct_page()  checks "obj->mem_flags & 
I915_BO_FLAG_STRUCT_PAGE" which is very i915 specific.

So I think this will not work and will cause regression in existing 
program which are trying to do the same with valid BO. Unfortunately I 
don't have any idea how to better detect that at this moment.


Regards,

Nirmoy

> +			out_fence = ERR_PTR(-EINVAL);
> +			return out_fence;
> +		}
> +
>   		/* Allocate a request for this batch buffer nice and early. */
>   		eb->requests[i] = i915_request_create(eb_find_context(eb, i));
>   		if (IS_ERR(eb->requests[i])) {