tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/wip2 head: fb0089110c5e29151c75028add05458ad2bf8a68 commit: b89bc5672b8331856b35fa6f63117c9832dd7416 [3/5] sched/core: Wait for tasks being pushed away on hotplug config: alpha-allyesconfig (attached as .config) compiler: alpha-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 b89bc5672b8331856b35fa6f63117c9832dd7416 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=alpha 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) | ^~~~~~~~~~~~~~~~~~~ In file included from include/linux/percpu-rwsem.h:7, from include/linux/fs.h:33, from include/linux/huge_mm.h:8, from include/linux/mm.h:677, from arch/alpha/include/asm/io.h:8, from include/linux/clocksource.h:21, from include/linux/clockchips.h:14, from include/linux/tick.h:8, from include/linux/sched/isolation.h:6, from kernel/sched/sched.h:17, from kernel/sched/core.c:13: kernel/sched/core.c: In function 'balance_hotplug_wait': 2601 | rcuwait_wait_event(&rq->hotplug_wait, rq->nr_running == 1, | ^~ include/linux/rcuwait.h:59:21: note: in definition of macro 'rcuwait_wait_event' 59 | prepare_to_rcuwait(w); \ | ^ 2601 | rcuwait_wait_event(&rq->hotplug_wait, rq->nr_running == 1, | ^~ include/linux/rcuwait.h:76:17: note: in definition of macro 'rcuwait_wait_event' 76 | finish_rcuwait(w); \ | ^ kernel/sched/core.c: In function 'schedule_tail': kernel/sched/core.c:3765:13: warning: variable 'rq' set but not used [-Wunused-but-set-variable] 3765 | struct rq *rq; | ^~ kernel/sched/core.c: At top level: 6968 | static inline void balance_hotplug_wait(void) { } | ^~~~~~~~~~~~~~~~~~~~ kernel/sched/core.c:2597:13: note: previous definition of 'balance_hotplug_wait' was here 2597 | static void balance_hotplug_wait(void) | ^~~~~~~~~~~~~~~~~~~~ kernel/sched/core.c: In function 'sched_cpu_activate': kernel/sched/core.c:7055:2: error: implicit declaration of function 'balance_push_set'; did you mean 'balance_push'? [-Werror=implicit-function-declaration] 7055 | balance_push_set(cpu, false); | ^~~~~~~~~~~~~~~~ | balance_push At top level: kernel/sched/core.c:2597:13: warning: 'balance_hotplug_wait' defined but not used [-Wunused-function] 2597 | static void balance_hotplug_wait(void) | ^~~~~~~~~~~~~~~~~~~~ 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 b89bc5672b8331856b35fa6f63117c9832dd7416 vim +2601 kernel/sched/core.c 2590 2591 /* 2592 * Invoked from a CPUs hotplug control thread after the CPU has been marked 2593 * inactive. All tasks which are not per CPU kernel threads are either 2594 * pushed off this CPU now via balance_push() or placed on a different CPU 2595 * during wakeup. Wait until the CPU is quiescent. 2596 */ 2597 static void balance_hotplug_wait(void) 2598 { 2599 struct rq *rq = this_rq(); 2600 2602 TASK_UNINTERRUPTIBLE); 2603 } 2604 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org