On Thu, 2022-08-11 at 22:55 +0200, Ilya Dryomov wrote: > On Thu, Aug 11, 2022 at 10:04 PM Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Thu, Aug 11, 2022 at 8:25 AM Ilya Dryomov <idryomov@xxxxxxxxx> wrote: > > > > > > [..] Several patches > > > touch files outside of our normal purview to set the stage for bringing > > > in Jeff's long awaited ceph+fscrypt series in the near future. All of > > > them have appropriate acks and sat in linux-next for a while. > > > > What? No. > > > > I'm looking at the fs/dcache.c change, for example, and don't see the > > relevant maintainers having acked it at all. > > > > The mmdebug.h file similarly seems to not have the actual maintainer > > acks, and seems just plain stupid (why does it add that new folio > > warning macro, when the existing folio warning macro > > VM_WARN_ON_ONCE_FOLIO() is *better*? > > > > Those are some very core files, and while the changes seem harmless, > > they sure don't seem obviously ok. > > > > What's the point of warning about bogus folios more than once? That's > > a debug warning - if it hits even once, that's already "uhhuh, > > something is bad". Showing the warning more than once is likely just > > going to cause more problems, not give you more information. > > Xiubo and Jeff used it to track down some issues between netfs library > and folio code that have been randomly plaguing our automated tests for > a couple of releases. We already knew that there were issues in that > area and the actual occurrences mattered. This was done in cooperation > with Willy and, since he was involved and this is a no-impact change, > I didn't think twice. > > > > > And did somebody verify that d_same_name() is still inlined in the > > place that truly *matters*? Because from my quick test, that patch > > broke it. Now __d_lookup() does a function call. > > > > And I _suspect_ it's all ok, because it turns out that > > __d_lookup_rcu() is the *really* hot case, and that one has inlined it > > all manually. > > > > But this kind of "we touch some *truly* core functionality, without > > the acks from the maintainers, and then we *claim* to have relevant > > acks" is really not even remotely ok. > > I raised the lack of a formal Acked-by from Al on the dcache change > with Jeff a while ago and my understanding was that he reached out to > Al and got the ack (after some ghosting on Al's behalf). I apologize > if I got that wrong -- all this happened in the middle of Jeff > transitioning his maintainership duties. > Actually, I never got a formal ack from Al. I did send it repeatedly, but I assume he has been too busy to respond. We've had it sitting in linux-next for a couple of months, and he did suggest that approach in the first place, but I too would also prefer to see his official ack on it. > > > > I've pulled this because I suspect that d_same_name() thing is fine, > > and I think the VM_WARN_ON_FOLIO() addition is completely wrong but > > not horrendous. > > > > But you're on my tentative shit-list just for having claimed to have > > appropriate acks and having been found wanting. > > > > Just for your information: fs/dcache.c is some of the most optimized > > code in the kernel, and some of the subtlest. That RCU pathname lookup > > is serious business. You don't make changes to pathname lookup just > > willy nilly. There's a reason I start looking at individual patches > > when I see it in the diffstat. > > Understood. > > Thanks, > > Ilya -- Jeff Layton <jlayton@xxxxxxxxxx>
