On Thu, Jul 30, 2020 at 05:17:01PM +0100, Al Viro wrote: > On Thu, Jul 30, 2020 at 05:20:46PM +0200, Christoph Hellwig wrote: > > > Fortunately I think the fix is pretty easy - remove the special pipe > > zero copy optimization from copy_page_to_iter, and just have the > > callers actually want it because they have pagecache or similar > > refcountable pages use it explicitly for the ITER_PIPE case. That gives > > us a safe default with an opt-in into the optimized variant. I'm > > currently auditing all the users of for how it is used and that looks > > pretty promising. > > Huh? What does that have to do with anything? FWIW, none of the dubious (and outright broken) cases I've found go anywhere near that. And it definitely won't help tun/tap...
