tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core head: 816969e4af7a56bfd284d2e0fa11511900ab93e3 commit: 6bcd3e21ba278098920d26d4888f5e6f4087c61d [2/5] sched/fair: Bring back select_idle_smt(), but differently config: powerpc64-randconfig-r033-20210409 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project dd453a1389b6a7e6d9214b449d3c54981b1a89b6) 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 # install powerpc64 cross compiling tool for clang build # apt-get install binutils-powerpc64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=6b... git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git git fetch --no-tags tip sched/core git checkout 6bcd3e21ba278098920d26d4888f5e6f4087c61d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64 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 >>): if (static_branch_likely(&sched_smt_present)) { ^ 4 errors generated. vim +/sched_smt_present +6345 kernel/sched/fair.c 6259 6260 /* 6261 * Try and locate an idle core/thread in the LLC cache domain. 6262 */ 6263 static int select_idle_sibling(struct task_struct *p, int prev, int target) 6264 { 6265 bool has_idle_core = false; 6266 struct sched_domain *sd; 6267 unsigned long task_util; 6268 int i, recent_used_cpu; 6269 6270 /* 6271 * On asymmetric system, update task utilization because we will check 6272 * that the task fits with cpu's capacity. 6273 */ 6274 if (static_branch_unlikely(&sched_asym_cpucapacity)) { 6275 sync_entity_load_avg(&p->se); 6276 task_util = uclamp_task_util(p); 6277 } 6278 6279 if ((available_idle_cpu(target) || sched_idle_cpu(target)) && 6280 asym_fits_capacity(task_util, target)) 6281 return target; 6282 6283 /* 6284 * If the previous CPU is cache affine and idle, don't be stupid: 6285 */ 6286 if (prev != target && cpus_share_cache(prev, target) && 6287 (available_idle_cpu(prev) || sched_idle_cpu(prev)) && 6288 asym_fits_capacity(task_util, prev)) 6289 return prev; 6290 6291 /* 6292 * Allow a per-cpu kthread to stack with the wakee if the 6293 * kworker thread and the tasks previous CPUs are the same. 6294 * The assumption is that the wakee queued work for the 6295 * per-cpu kthread that is now complete and the wakeup is 6296 * essentially a sync wakeup. An obvious example of this 6297 * pattern is IO completions. 6298 */ 6299 if (is_per_cpu_kthread(current) && 6300 prev == smp_processor_id() && 6301 this_rq()->nr_running <= 1) { 6302 return prev; 6303 } 6304 6305 /* Check a recently used CPU as a potential idle candidate: */ 6306 recent_used_cpu = p->recent_used_cpu; 6307 if (recent_used_cpu != prev && 6308 recent_used_cpu != target && 6309 cpus_share_cache(recent_used_cpu, target) && 6310 (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) && 6311 cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && 6312 asym_fits_capacity(task_util, recent_used_cpu)) { 6313 /* 6314 * Replace recent_used_cpu with prev as it is a potential 6315 * candidate for the next wake: 6316 */ 6317 p->recent_used_cpu = prev; 6318 return recent_used_cpu; 6319 } 6320 6321 /* 6322 * For asymmetric CPU capacity systems, our domain of interest is 6323 * sd_asym_cpucapacity rather than sd_llc. 6324 */ 6325 if (static_branch_unlikely(&sched_asym_cpucapacity)) { 6326 sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target)); 6327 /* 6328 * On an asymmetric CPU capacity system where an exclusive 6329 * cpuset defines a symmetric island (i.e. one unique 6330 * capacity_orig value through the cpuset), the key will be set 6331 * but the CPUs within that cpuset will not have a domain with 6332 * SD_ASYM_CPUCAPACITY. These should follow the usual symmetric 6333 * capacity path. 6334 */ 6335 if (sd) { 6336 i = select_idle_capacity(p, sd, target); 6337 return ((unsigned)i < nr_cpumask_bits) ? i : target; 6338 } 6339 } 6340 6341 sd = rcu_dereference(per_cpu(sd_llc, target)); 6342 if (!sd) 6343 return target; 6344 6346 has_idle_core = test_idle_cores(target, false); 6347 6348 if (!has_idle_core && cpus_share_cache(prev, target)) { 6349 i = select_idle_smt(p, sd, prev); 6350 if ((unsigned int)i < nr_cpumask_bits) 6351 return i; 6352 } 6353 } 6354 6355 i = select_idle_cpu(p, sd, has_idle_core, target); 6356 if ((unsigned)i < nr_cpumask_bits) 6357 return i; 6358 6359 return target; 6360 } 6361 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org