On 2023/11/16 1:57, David Ahern wrote: > 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. Yes, I am agreed the ultimate goal is to move away from struct page references. But I am not sure if we can do it right away as there still are different types of existing 'struct page' in the netstack, see: https://lore.kernel.org/all/8b7d25eb-1f10-3e37-8753-92b42da3fb34@xxxxxxxxxx/ > > > . >
