On Mon, Apr 15, 2024 at 09:19:06AM -0700, Suren Baghdasaryan wrote: > On Mon, Apr 15, 2024 at 9:13 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > The tcp vma is not file backed, but I'm pretty sure that COW is not > > something they want, so there's never an anon_vma. It's for pages > > that contain received TCP packets; ie it's mmaped TCP. > > I was following > tcp_zerocopy_receive()->tcp_zerocopy_vm_insert_batch()->vm_insert_pages()->insert_page_in_batch_locked()->validate_page_before_insert() > which errors out for PageAnon(page). So, I assumed this path works on > file-backed pages but I'm not familiar with this code at all. It turns out there are pages which are neither file nor anon ;-) I have a partial list here: https://kernelnewbies.org/MatthewWilcox/Memdescs but I don't even have TCP on that list. I haven't looked into what they need -- I don't think they need mapping, index, etc, but I need to figure that out.
