tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/wip2 head: fb0089110c5e29151c75028add05458ad2bf8a68 commit: 4668b8e3eb50c6b6efeffb610dfaa1e698ee2040 [2/5] sched/hotplug: Ensure only per-cpu kthreads run during hotplug config: powerpc-allyesconfig (attached as .config) compiler: powerpc64-linux-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 4668b8e3eb50c6b6efeffb610dfaa1e698ee2040 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): kernel/sched/core.c:2380:6: warning: no previous prototype for 'sched_set_stop_task' [-Wmissing-prototypes] 2380 | void sched_set_stop_task(int cpu, struct task_struct *stop) | ^~~~~~~~~~~~~~~~~~~ kernel/sched/core.c: In function 'schedule_tail': kernel/sched/core.c:3751:13: warning: variable 'rq' set but not used [-Wunused-but-set-variable] 3751 | struct rq *rq; | ^~ kernel/sched/core.c: In function '__balance_push_cpu_stop': 6869 | update_rq_clockrq(); | ^~~~~~~~~~~~~~~~~ | update_rq_clock cc1: some warnings being treated as errors # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?... git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git git fetch --no-tags peterz-queue sched/wip2 git checkout 4668b8e3eb50c6b6efeffb610dfaa1e698ee2040 vim +6869 kernel/sched/core.c 6858 6859 static int __balance_push_cpu_stop(void *arg) 6860 { 6861 struct task_struct *p = arg; 6862 struct rq *rq = this_rq(); 6863 struct rq_flags rf; 6864 int cpu; 6865 6866 raw_spin_lock_irq(&p->pi_lock); 6867 rq_lock(rq, &rf); 6868 6870 6871 if (task_rq(p) == rq && task_on_rq_queued(p)) { 6872 cpu = select_fallback_rq(rq->cpu, p); 6873 rq = __migrate_task(rq, &rf, p, cpu); 6874 } 6875 6876 rq_unlock(rq, &rf); 6877 raw_spin_unlock_irq(&p->pi_lock); 6878 6879 put_task_struct(p); 6880 6881 return 0; 6882 } 6883 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org