On Fri, Mar 11, 2022 at 06:36:07PM -0500, Steven Rostedt wrote: > On Fri, 11 Mar 2022 15:28:09 -0800 > Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx> wrote: > > > OK, you know more than I, so hopefully we can land on if we really need > > it or not. For now I've left it in. > > > > > > > > > > The other thing is that this patch applied to 5.10.X on ARM64 does not > > > > appear to hit this. Is it some weird interaction with something else or > > > > was 5.10.X just getting lucky? > > > > > > Perhaps it's because you allocated the page with kzalloc and not just > > > getting a page directly? > > I sent a version that removes it, but I think we can add it back. > > > > > > > > Yeah, I think so too. I was able to repro locally and validate that using > > alloc_pages directly fixes this by setting DEBUG_VM_PGFLAGS=y. > > > > I've posted a patch for this: > > https://lore.kernel.org/linux-trace-devel/20220311223028.1865-1-beaub@xxxxxxxxxxxxxxxxxxx/ > > Just saw it (I screwed up my procmail settings getting rid of some more > spam, and ended up sending all my email to a ":" folder :-p) > > If you want, I can send another version of my patch that doesn't remove the > reserve. But I like my patch as it sets the MAX_EVENTS based on a order and > not the other way around. I never pass up free work (or drinks), I would prefer to keep the reserve in there. Worst case it's redundant, best case it protects us from a crash in a user process down the road. Thanks, -Beau
