Hi Zhouyi, On Mon, Jan 16, 2023 at 1:33 PM Zhouyi Zhou <zhouzhouyi@xxxxxxxxx> wrote: > [..] > On Tue, Jan 17, 2023 at 1:27 AM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > I am seeing -EBUSY returned a lot during torture_onoff() when running > > rcutorture on arm64. This causes hotplug failure 30% of the time. I am > > also seeing this in 6.1-rc kernels. I believe see this only for CPU0. > > > > This causes warnings in torture tests: > > [ 217.582290] rcu-torture:torture_onoff task: offline 0 failed: errno -16 > > [ 221.866362] rcu-torture:torture_onoff task: offline 0 failed: errno -16 > > > > Full kernel log here: > > http://box.joelfernandes.org:9080/job/rcutorture_stable_arm/job/linux-5.15.y/7/artifact/tools/testing/selftests/rcutorture/res/2023.01.15-14.51.11/TREE04/console.log > > > > Any ideas on why this is happening and only for CPU 0 (presumably the > > boot CPU)? I'd personally need these warnings to go away for my tests > > as this causes rcutorture's tests to not cleanly pass for me. It > > appears remove_cpu() -> device_offline() is what returns the error. > > > I guess this probably because CPU 0 is the tick_do_timer_cpu in > nohz_full mode, which prevent that cpu from > going offline [1]. We have discussed this topic, but there is no > agreement on how to solve it yet. But I am seeing the issue in TRACE02 config which is: CONFIG_NO_HZ_IDLE=y # CONFIG_NO_HZ_FULL is not set So that is not NO_HZ_FULL: http://box.joelfernandes.org:9080/job/rcutorture_stable_arm/job/linux-5.15.y/7/artifact/tools/testing/selftests/rcutorture/res/2023.01.15-14.51.11/TRACE02/console.log.diags/ However, I can't seem to find the full kernel logs for that. Also, other than the TRACE02 fail, I only see the issue with configs with CONFIG_NO_HZ_FULL=y Can you try TRACE02 specifically, and see if you can reproduce the same issue on your setup? Meanwhile, I'll try to trace what is returning the -EBUSY. Thanks! - Joel > > [1] https://lore.kernel.org/lkml/20221127175317.GF4001@paulmck-ThinkPad-P17-Gen-1/T/ > > Thanks > Zhouyi > > You can browse through all the torture test artifacts here which > > contains everything (build logs, vmlinux, etc). > > http://box.joelfernandes.org:9080/job/rcutorture_stable_arm/job/linux-5.15.y/7/artifact/tools/testing/selftests/rcutorture/res/2023.01.15-14.51.11/ > > > > Thanks for your help! > > > > - Joel
