Subject: Re: [PATCH vhost v7 01/11] virtio_ring: split: separate dma codes

From: Christoph Hellwig <[email-masked]>
Date: Sun, 30 Apr 2023 21:24:52 -0700

> +static dma_addr_t vring_sg_address(struct scatterlist *sg)
> +{
> +	if (sg->dma_address)
> +		return sg->dma_address;

0 is a perfectly valid DMA address.  So I have no idea how this is
even supposed to work.