On 2020/03/30 18:01, Dmitry Vyukov wrote: > On Mon, Mar 30, 2020 at 10:49 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >> >> On Mon, Mar 30, 2020 at 2:43 AM Guilherme Piccoli >> <gpiccoli@xxxxxxxxxxxxx> wrote: >>> >>> Hi Tetsuo and Dmitry, thanks for noticing this Tetsuo. And sorry for >>> not looping you in the patch Dmitry, I wasn't aware that you were >>> working with testing. By the way, I suggest people interested in linux >>> testing to create a ML; I'd be glad to have looped such list, but I >>> couldn't find information about a group dealing with testing. >>> >>> So Tetsuo, you got it right: just change it to >>> "sysctl.kernel.hung_task_all_cpu_backtrace=1" and that should work >>> fine, once Vlastimil's patch gets merged (and I hope it happens soon). >>> Cheers, >>> >>> >>> Guilherme >> >> +LKML, workflows, syzkaller, kernelci, cki, kbuild >> >> Tetsuo, thanks for notifying again. >> >> Yes, kernel devs breaking all testing happens from time to time and >> currently there is no good way to address this. >> Other things I remember is the introduction of CONFIG_DEBUG_MEMORY, >> which defaults to =n and disables KASAN, which in turn produced an >> explosion of assorted crashes caused by memory corruptions; also >> periodic changes in kernel crash messages which I assume all testing >> systems parse and need to understand. >> >> Is there already a mailing list for this? Or should we create one? >> I.e. announce and changes that may need actions from all testing >> systems. I think we can create one. >> Another thing that may benefit from announcements is addition of new >> useful debugging configs. Currently they are introduced silently and >> don't reach the target audience. > > I've fixed this up: > https://github.com/google/syzkaller/commit/c8d1cc20df5ca5d9ea437054720fa3cfdfa1f578 Excuse me, but that commit is incorrect. There will be no /proc/sys/sysctl/kernel/hung_task_all_cpu_backtrace file. What Vlastimil's patch will allow is to set sysctl values via kernel command line option using "sysctl." as a prefix. That is, -hung_task_all_cpu_backtrace=1 +sysctl.kernel.hung_task_all_cpu_backtrace=1 on dashboard/config/*.cmdline files is what you need. > > But what would be even better is some kind of canned configs/settings > for testing systems so that I enable it once and then such changes > magically auto-happen for me. Yes, updating kernel config is a burden for kernel testing projects. I'm waiting for comments from more kernel testing projects on https://lkml.kernel.org/r/55c906c8-ca70-9d1b-a90f-49660773856b@xxxxxxxxxxxxxxxxxxx . > Imposing work on N testing systems maintainers is not good. > And there really is no good point in the current kernel dev process > for this. Announcing unmerged changes is too early (as this patch > showed). And once it's in linux-next it's already too late.. > And I don't want to be inventing a new unique kernel configuration for > testing. I don't think it's the right way to approach this. Whatever > is "the testing configuration", whatever kernel developers want to see > in task hang reports, I just want the system to provide that. >
