Re: [PATCH net-next v2 4/5] page_pool: disable sync for cpu for dmabuf memory provider

[Jason Gunthorpe]

On Thu, Nov 07, 2024 at 09:23:08PM +0000, Mina Almasry wrote:
> dmabuf dma-addresses should not be dma_sync'd for CPU/device. Typically
> its the driver responsibility to dma_sync for CPU, but the driver should
> not dma_sync for CPU if the netmem is actually coming from a dmabuf
> memory provider.

This is not completely true, it is not *all* dmabuf, just the parts of
the dmabuf that are actually MMIO.

If you do this you may want to block accepting dmabufs that have CPU
pages inside them.

Jason