On Fri, Mar 03, 2023 at 01:41:00PM +0100, Paolo Abeni wrote: > On Fri, 2023-03-03 at 12:44 +0100, Greg Kroah-Hartman wrote: > > On Fri, Mar 03, 2023 at 12:39:07PM +0100, Paolo Abeni wrote: > > > Additionally, some self-tests check for known bugs/regressions. Running > > > them on older kernel will cause real trouble, and checking for bug > > > presence in the running kernel would be problematic at best, I think. > > > > No, not at all, why wouldn't you want to test for know bugs and > > regressions and fail? That's a great thing to do, and so you will know > > to backport those bugfixes to those older kernels if you have to use > > them. > > I'm sorry, I likely was not clear at all. What I mean is that the self- > test for a bug may trigger e.g. memory corruption on the bugged kernel > (or more specifically to networking, the infamous, recurring > "unregister_netdevice: waiting for ...") which in turn could cause > random failures later. > > If that specific case runs on older (unpatched) kernel will screw the > overall tests results. The same could happen in less-detectable way for > old bugs non explicitly checked by any test, but still triggered by the > test-suite. As a consequence I expect that the results observed running > newer self-tests on older kernel are unreliable. For the stable/LTS kernel trees, they should _never_ be unreliable, otherwise that means we have missed a needed fix and so we need to resolve that. Which is why I always recommend running the latest selftests on all older kernels, and have for a very long time now. thanks, greg k-h
