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

From: Jakub Kicinski <[email-masked]>
Date: Sat, 23 Nov 2024 18:33:51 -0800

On Fri, 22 Nov 2024 14:10:28 -0800 Samiullah Khawaja wrote:
> > > > If you do this you may want to block accepting dmabufs that have CPU
> > > > pages inside them.  
> 
> I believe we should be following the dmabuf API for this purpose, if
> we really want to sync for CPU in. page_pool, and should not assume
> the behaviour of the backing memory.
> 
> The dmabuf exporters are supposed to implement the begin_cpu_access
> (optional) and the sync for cpu is done based on the exporter
> implementation.

DMABUF is a bit of a distraction here.

What's key is that we need to fill in the gap in the driver facing
page_pool API, because DMABUF will not be the only provider we can
plug in.