On Fri, 16 Jun 2023 20:41:45 +0200 Jesper Dangaard Brouer wrote:

quoted

This is a sort-of. One thing that has come up as of late is that all
this stuff is being moved over to folios anyway and getting away from
pages. In addition I am not sure how often we are having to take this
path as I am not sure how many non-Tx frames end up having to have
fragments added to them. For something like veth it might be more
common though since Tx becomes Rx in this case.  

I'm thinking, that is it very unlikely that XDP have modified the
fragments.  So, why are we allocating and copying the fragments?
Wouldn't it be possible for this veth code to bump the refcnt on these
fragments? (maybe I missed some detail).

They may be page cache pages, AFAIU.