tree: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git 20211118-sysctl-cleanups-set-04-v2 head: 3110d41a56792588bd2f64621080948b0fceb6ab commit: 384c95eff01a635ed28e48a8521095421bd853c2 [22/36] printk: move printk sysctl to printk/sysctl.c config: nds32-allnoconfig (attached as .config) compiler: nds32le-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/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 20211118-sysctl-cleanups-set-04-v2 git checkout 384c95eff01a635ed28e48a8521095421bd853c2 # 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=nds32 SHELL=/bin/bash fs/ kernel/printk/ 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/printk/sysctl.c: In function 'printk_sysctl_init': 84 | register_sysctl_init("kernel", printk_sysctls, "printk"); | ^ In file included from kernel/printk/sysctl.c:6: include/linux/sysctl.h:210: note: macro "register_sysctl_init" defined here 210 | #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table) | 84 | register_sysctl_init("kernel", printk_sysctls, "printk"); | ^~~~~~~~~~~~~~~~~~~~ | register_sysctl_paths kernel/printk/sysctl.c:84:9: note: each undeclared identifier is reported only once for each function it appears in At top level: kernel/printk/sysctl.c:23:25: warning: 'printk_sysctls' defined but not used [-Wunused-variable] 23 | static struct ctl_table printk_sysctls[] = { | ^~~~~~~~~~~~~~ vim +/register_sysctl_init +84 kernel/printk/sysctl.c 81 82 void __init printk_sysctl_init(void) 83 { --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org