tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core head: 9f47b4eeebb0c1b6e3658591a345e30b8cecd11a commit: 9f47b4eeebb0c1b6e3658591a345e30b8cecd11a [9/9] sched: Warn on long periods of pending need_resched config: nios2-defconfig (attached as .config) compiler: nios2-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 # 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/core git checkout 9f47b4eeebb0c1b6e3658591a345e30b8cecd11a # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nios2 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): kernel/sched/core.c: In function 'ttwu_stat': kernel/sched/core.c:2920:13: warning: variable 'rq' set but not used [-Wunused-but-set-variable] 2920 | struct rq *rq; | ^~ kernel/sched/core.c: In function 'resched_latency_check': 4558 | if (now < resched_boot_quiet_sec * NSEC_PER_SEC) vim +4558 kernel/sched/core.c 4543 4544 #ifdef CONFIG_SCHED_DEBUG 4545 static u64 resched_latency_check(struct rq *rq) 4546 { 4547 int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms); 4548 u64 need_resched_latency, now = rq_clock(rq); 4549 static bool warned_once; 4550 4551 if (sysctl_resched_latency_warn_once && warned_once) 4552 return 0; 4553 4554 if (!need_resched() || WARN_ON_ONCE(latency_warn_ms < 2)) 4555 return 0; 4556 4557 /* Disable this warning for the first few mins after boot */ 4559 return 0; 4560 4561 if (!rq->last_seen_need_resched_ns) { 4562 rq->last_seen_need_resched_ns = now; 4563 rq->ticks_without_resched = 0; 4564 return 0; 4565 } 4566 4567 rq->ticks_without_resched++; 4568 need_resched_latency = now - rq->last_seen_need_resched_ns; 4569 if (need_resched_latency <= latency_warn_ms * NSEC_PER_MSEC) 4570 return 0; 4571 4572 warned_once = true; 4573 4574 return need_resched_latency; 4575 } 4576 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org