LKFT started testing KCSAN enabled kernel from the linux next tree. Here we have found BUG: KCSAN: data-race in tick_nohz_next_event / tick_nohz_stop_tick This report is from an x86_64 machine clang-11 linux next 20201201. Since we are running for the first time we do not call this regression. [ 47.811425] BUG: KCSAN: data-race in tick_nohz_next_event / tick_nohz_stop_tick [ 47.818738] [ 47.820239] write to 0xffffffffa4cbe920 of 4 bytes by task 0 on cpu 2: [ 47.826766] tick_nohz_stop_tick+0x8b/0x310 [ 47.830951] tick_nohz_idle_stop_tick+0xcb/0x170 [ 47.835571] do_idle+0x193/0x250 [ 47.838804] cpu_startup_entry+0x25/0x30 [ 47.842728] start_secondary+0xa0/0xb0 [ 47.846482] secondary_startup_64_no_verify+0xc2/0xcb [ 47.851531] [ 47.853034] read to 0xffffffffa4cbe920 of 4 bytes by task 0 on cpu 3: [ 47.859473] tick_nohz_next_event+0x165/0x1e0 [ 47.863831] tick_nohz_get_sleep_length+0x94/0xd0 [ 47.868539] menu_select+0x250/0xac0 [ 47.872116] cpuidle_select+0x47/0x50 [ 47.875781] do_idle+0x17c/0x250 [ 47.879015] cpu_startup_entry+0x25/0x30 [ 47.882942] start_secondary+0xa0/0xb0 [ 47.886694] secondary_startup_64_no_verify+0xc2/0xcb [ 47.891743] [ 47.893234] Reported by Kernel Concurrency Sanitizer on: [ 47.898541] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.10.0-rc6-next-20201201 #2 [ 47.906017] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.2 05/23/2018 metadata: git_repo: https://gitlab.com/aroxell/lkft-linux-next target_arch: x86 toolchain: clang-11 git_describe: next-20201201 download_url: https://builds.tuxbuild.com/1l8eiWgGMi6W4aDobjAAlOleFVl/ Full test log link, https://lkft.validation.linaro.org/scheduler/job/2002643#L2019 -- Linaro LKFT https://lkft.linaro.org