On Tue, Dec 3, 2019 at 7:38 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Tue, 3 Dec 2019 16:14:17 +0100 > Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > > On Tue, Dec 3, 2019 at 4:00 PM Qian Cai <cai@xxxxxx> wrote: > > > > > > > > > > > > > On Dec 3, 2019, at 9:35 AM, Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > > > > > > > At this point I don't really know why KMSAN and lockdep don't play > > > > well together, but I'm not expecting anyone to use them together > > > > either. > > > > > > Of course people will use those together. For example, distro debug kernel variants. > > Some tools are just not designed to work together. > > For example, you won't be able to compile the kernel with both KASAN > > and KMSAN enabled at the same time. > > > > Lockdep doesn't require any instrumentation to work, so it _might_ be > > possible to make it work with KMSAN, but it will probably still slow > > down the things to an unacceptable level. > > I'm inclining towards disabling the two together for now, unless > > anyone is willing to address that issue. > > Note, I'm much more interested in someone running with lockdep than > with KMSAN. Thus, you may not get as much use if you do not work with > lockdep. I enable lockdep first when testing out my code. If KMSAN is > not compatible, it wont get enabled. > > > > > Please let me know if you think I need to keep the link to > > https://github.com/google/kmsan/issues/57 in the Kconfig comment, > > right now it looks like: > > > > # KMSAN is currently incompatible with lockdep. > > > > Function tracing had lots of issues with lockdep, but I worked hard to > make sure they could be compatible. This usually required having the > lockdep code not be traced. Is it possible to have the same with KMSAN. > That is, have KMSAN not look at anything that lockdep does? > > -- Steve Qian, Steve, thanks for the data points. I thought it might be more valuable to cut some edges to make KMSAN available to early users, but in the case most developers use a single build for testing it indeed makes more sense to fix lockdep interoperability. I'll look into that. -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
