Re: [PATCH RFC 3/8] memory-provider: dmabuf devmem memory provider

[David Ahern]

On 11/15/23 2:21 AM, Yunsheng Lin wrote:
> On 2023/11/14 21:16, Jason Gunthorpe wrote:
>> On Tue, Nov 14, 2023 at 04:21:26AM -0800, Mina Almasry wrote:
>>
>>> Actually because you put the 'strtuct page for devmem' in
>>> skb->bv_frag, the net stack will grab the 'struct page' for devmem
>>> using skb_frag_page() then call things like page_address(), kmap,
>>> get_page, put_page, etc, etc, etc.
>>
>> Yikes, please no. If net has its own struct page look alike it has to
>> stay entirely inside net. A non-mm owned struct page should not be
>> passed into mm calls. It is just way too hacky to be seriously
>> considered :(
> 
> Yes, that is something this patchset is trying to do, defining its own
> struct page look alike for page pool to support devmem.
> 

Networking needs to be able to move away from struct page references.
The devmem and host memory for Rx use cases do not need to be page based.