Re: [RFC RESEND 00/16] Split IOMMU DMA mapping operation to two steps

Christoph Hellwig
2024-03-24T23:16:20Z

On Fri, Mar 22, 2024 at 07:46:17PM +0200, Leon Romanovsky wrote:
> > As far as I can tell it totally misses the point. Which is not to never
> > return non-P2P if the flag is set, but to return either all P2P or non-P2
> > P and not create a boundary in the single call.
>
> You are treating FOLL_PCI_P2PDMA as a hint, but in iov_iter_extract_user_pages()
> you set it only for p2p queues. I was under impression that you want only p2p pages
> in these queues.

FOLL_PCI_P2PDMA is an indicator that the caller can cope with P2P
pages. Most callers simply can't.