Re: [PATCH net-next 2/3] net: devmem: use memory provider helpers for net_iovs

[Pavel Begunkov <asml.silence@gmail.com>]

On 9/22/26 21:43, Stanislav Fomichev wrote:
> Use public memory-provider helpers for DMA address storage and page-pool
> association instead of open-coding page_pool state and accounting.
> 
> Zero the net_iov array because net_mp_niov_set_page_pool() ORs
> PP_SIGNATURE into pp_magic. Reject DMA addresses that cannot be
> represented in net_iov metadata.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

> @@ -247,7 +245,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
>   			goto err_unmap;
>   		}
>   	}
> -	binding->area.niovs = kvmalloc_objs(*binding->area.niovs,
> +	binding->area.niovs = kvzalloc_objs(*binding->area.niovs,
>   					    binding->area.num_niovs);
>   	if (!binding->area.niovs) {
>   		err = -ENOMEM;
> @@ -274,8 +272,12 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
>   		for (i = 0; i < nr_niovs; i++, niov_idx++) {
>   			niov = &binding->area.niovs[niov_idx];
>   			net_iov_init(niov, &binding->area, NET_IOV_DMABUF);
> -			page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
> -						      dma_addr);
> +			if (net_mp_niov_set_dma_addr(niov, dma_addr)) {

I'd do this chunk as a separate patch with stable+fix tags to
keep it minimal and help backporting, e.g.

if (page_pool_set_dma_addr_netmem())
	// fail;

Looks like the bot was saying the same (with an extra wall of text),
but I guess it depends on whether you need it backported.

> +				err = -EFAULT;
> +				NL_SET_ERR_MSG(extack,
> +					       "dmabuf DMA address cannot be represented");
> +				goto err_free_niovs;
> +			}
>   			if (direction == DMA_TO_DEVICE)
>   				binding->tx_vec[niov_idx] = niov;
-- 
Pavel Begunkov