Hi Srikar, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y head: 3a9842b42e421f6496a78a42a123639cf6d7ed31 commit: e91077cf1780108dc586cedf1d19f65b44fa3870 [499/1334] powerpc/smp: Update cpu_core_map on all PowerPc systems config: powerpc64-randconfig-r033-20211012 (attached as .config) compiler: powerpc64-linux-gcc (GCC) 11.2.0 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/stable/linux-stable-rc.gi... git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git git fetch --no-tags linux-stable-rc linux-5.10.y git checkout e91077cf1780108dc586cedf1d19f65b44fa3870 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 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 >>): arch/powerpc/kernel/smp.c:551:6: error: no previous prototype for 'tick_broadcast' [-Werror=missing-prototypes] 551 | void tick_broadcast(const struct cpumask *mask) | ^~~~~~~~~~~~~~ arch/powerpc/kernel/smp.c:561:6: error: no previous prototype for 'debugger_ipi_callback' [-Werror=missing-prototypes] 561 | void debugger_ipi_callback(struct pt_regs *regs) | ^~~~~~~~~~~~~~~~~~~~~ arch/powerpc/kernel/smp.c: In function 'add_cpu_to_masks': 1380 | bool ret; | ^~~ cc1: all warnings being treated as errors vim +/ret +1380 arch/powerpc/kernel/smp.c b8a97cb4599cda Srikar Dronamraju 2020-09-21 1373 df52f6714071c4 Oliver O'Halloran 2017-06-29 1374 static void add_cpu_to_masks(int cpu) df52f6714071c4 Oliver O'Halloran 2017-06-29 1375 { bf6476152a0a08 Srikar Dronamraju 2021-04-15 1376 struct cpumask *(*submask_fn)(int) = cpu_sibling_mask; df52f6714071c4 Oliver O'Halloran 2017-06-29 1377 int first_thread = cpu_first_thread_sibling(cpu); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1378 int chip_id = cpu_to_chip_id(cpu); 84dbf66c634720 Srikar Dronamraju 2020-10-19 1379 cpumask_var_t mask; bf6476152a0a08 Srikar Dronamraju 2021-04-15 @1380 bool ret; df52f6714071c4 Oliver O'Halloran 2017-06-29 1381 int i; df52f6714071c4 Oliver O'Halloran 2017-06-29 1382 df52f6714071c4 Oliver O'Halloran 2017-06-29 1383 /* df52f6714071c4 Oliver O'Halloran 2017-06-29 1384 * This CPU will not be in the online mask yet so we need to manually df52f6714071c4 Oliver O'Halloran 2017-06-29 1385 * add it to it's own thread sibling mask. df52f6714071c4 Oliver O'Halloran 2017-06-29 1386 */ df52f6714071c4 Oliver O'Halloran 2017-06-29 1387 cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); e91077cf178010 Srikar Dronamraju 2021-08-26 1388 cpumask_set_cpu(cpu, cpu_core_mask(cpu)); df52f6714071c4 Oliver O'Halloran 2017-06-29 1389 df52f6714071c4 Oliver O'Halloran 2017-06-29 1390 for (i = first_thread; i < first_thread + threads_per_core; i++) df52f6714071c4 Oliver O'Halloran 2017-06-29 1391 if (cpu_online(i)) df52f6714071c4 Oliver O'Halloran 2017-06-29 1392 set_cpus_related(i, cpu, cpu_sibling_mask); df52f6714071c4 Oliver O'Halloran 2017-06-29 1393 425752c63b6f3f Gautham R. Shenoy 2018-10-11 1394 add_cpu_to_smallcore_masks(cpu); 84dbf66c634720 Srikar Dronamraju 2020-10-19 1395 84dbf66c634720 Srikar Dronamraju 2020-10-19 1396 /* In CPU-hotplug path, hence use GFP_ATOMIC */ bf6476152a0a08 Srikar Dronamraju 2021-04-15 1397 ret = alloc_cpumask_var_node(&mask, GFP_ATOMIC, cpu_to_node(cpu)); 84dbf66c634720 Srikar Dronamraju 2020-10-19 1398 update_mask_by_l2(cpu, &mask); 2a636a56d2d396 Oliver O'Halloran 2017-06-29 1399 b8a97cb4599cda Srikar Dronamraju 2020-09-21 1400 if (has_coregroup_support()) 84dbf66c634720 Srikar Dronamraju 2020-10-19 1401 update_coregroup_mask(cpu, &mask); 84dbf66c634720 Srikar Dronamraju 2020-10-19 1402 bf6476152a0a08 Srikar Dronamraju 2021-04-15 1403 if (shared_caches) bf6476152a0a08 Srikar Dronamraju 2021-04-15 1404 submask_fn = cpu_l2_cache_mask; bf6476152a0a08 Srikar Dronamraju 2021-04-15 1405 bf6476152a0a08 Srikar Dronamraju 2021-04-15 1406 /* Update core_mask with all the CPUs that are part of submask */ bf6476152a0a08 Srikar Dronamraju 2021-04-15 1407 or_cpumasks_related(cpu, cpu, submask_fn, cpu_core_mask); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1408 bf6476152a0a08 Srikar Dronamraju 2021-04-15 1409 /* Skip all CPUs already part of current CPU core mask */ bf6476152a0a08 Srikar Dronamraju 2021-04-15 1410 cpumask_andnot(mask, cpu_online_mask, cpu_core_mask(cpu)); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1411 e91077cf178010 Srikar Dronamraju 2021-08-26 1412 /* If chip_id is -1; limit the cpu_core_mask to within DIE*/ e91077cf178010 Srikar Dronamraju 2021-08-26 1413 if (chip_id == -1) e91077cf178010 Srikar Dronamraju 2021-08-26 1414 cpumask_and(mask, mask, cpu_cpu_mask(cpu)); e91077cf178010 Srikar Dronamraju 2021-08-26 1415 bf6476152a0a08 Srikar Dronamraju 2021-04-15 1416 for_each_cpu(i, mask) { bf6476152a0a08 Srikar Dronamraju 2021-04-15 1417 if (chip_id == cpu_to_chip_id(i)) { bf6476152a0a08 Srikar Dronamraju 2021-04-15 1418 or_cpumasks_related(cpu, i, submask_fn, cpu_core_mask); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1419 cpumask_andnot(mask, mask, submask_fn(i)); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1420 } else { bf6476152a0a08 Srikar Dronamraju 2021-04-15 1421 cpumask_andnot(mask, mask, cpu_core_mask(i)); bf6476152a0a08 Srikar Dronamraju 2021-04-15 1422 } bf6476152a0a08 Srikar Dronamraju 2021-04-15 1423 } bf6476152a0a08 Srikar Dronamraju 2021-04-15 1424 84dbf66c634720 Srikar Dronamraju 2020-10-19 1425 free_cpumask_var(mask); a8a5356cd511db Paul Mackerras 2013-08-12 1426 } a8a5356cd511db Paul Mackerras 2013-08-12 1427 :::::: The code at line 1380 was first introduced by commit :::::: bf6476152a0a084038b12b9d770e32717f54a6ab powerpc/smp: Reintroduce cpu_core_mask :::::: TO: Srikar Dronamraju <srikar(a)linux.vnet.ibm.com&gt; :::::: CC: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org