tree: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git 20211116-sysctl-cleanups-v3 head: 06113f1d9a2d0669964adfa2e0128bd50e56b621 commit: 39ba9159476b6d86288f95f4cb62ad7055680395 [18/20] sysctl: add helper to register a sysctl mount point config: arc-randconfig-r013-20211116 (attached as .config) compiler: arceb-elf-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/mcgrof/linux-next.git/com... git remote add mcgrof-next https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git git fetch --no-tags mcgrof-next 20211116-sysctl-cleanups-v3 git checkout 39ba9159476b6d86288f95f4cb62ad7055680395 # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arc prepare 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/arc/Makefile:26: ** WARNING ** CONFIG_ARC_TUNE_MCPU flag '' is unknown, fallback to '' error: no override and no default toolchain set init/Kconfig:70:warning: 'RUSTC_VERSION': number is invalid In file included from include/linux/key.h:17, from include/linux/cred.h:13, from include/linux/sched/signal.h:10, from include/linux/rcuwait.h:6, 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:717, from arch/arc/kernel/asm-offsets.c:7: include/linux/sysctl.h: In function 'register_sysctl_mount_point': 230 | } | ^ At top level: include/linux/sysctl.h:227:30: warning: 'register_sysctl_mount_point' defined but not used [-Wunused-function] 227 | static struct sysctl_header *register_sysctl_mount_point(const char *path) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ make[2]: *** [scripts/Makefile.build:122: arch/arc/kernel/asm-offsets.s] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [Makefile:1279: prepare0] Error 2 make[1]: Target 'prepare' not remade because of errors. make: *** [Makefile:226: __sub-make] Error 2 make: Target 'prepare' not remade because of errors. vim +230 include/linux/sysctl.h 226 227 static struct sysctl_header *register_sysctl_mount_point(const char *path) 228 { 229 return NULL 231 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org