Hi Joel 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. [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
