Hi Mathias, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: b81b1829e7e39f6cebdf6e4d5484eacbceda8554 commit: b027789e5e50494c2325cc70c8642e7fd6059479 sched/fair: Prevent dead task groups from regaining cfs_rq's date: 3 months ago config: riscv-randconfig-c006-20220213 (https://download.01.org/0day-ci/archive/20220214/202202140339.Uk9VGrvV-lk...) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 478c237e21b2c3a83e46f26fcbeb3876682f9b14) 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 riscv cross compiling tool for clang build # apt-get install binutils-riscv64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout b027789e5e50494c2325cc70c8642e7fd6059479 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/mm/ drivers/clk/bcm/ drivers/gpu/drm/ kernel/sched/ 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 >>): void unregister_rt_sched_group(struct task_group *tg) { } ^ kernel/sched/rt.c:257:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void unregister_rt_sched_group(struct task_group *tg) { } ^ static kernel/sched/rt.c:259:6: error: no previous prototype for function 'free_rt_sched_group' [-Werror,-Wmissing-prototypes] void free_rt_sched_group(struct task_group *tg) { } ^ kernel/sched/rt.c:259:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void free_rt_sched_group(struct task_group *tg) { } ^ static kernel/sched/rt.c:261:5: error: no previous prototype for function 'alloc_rt_sched_group' [-Werror,-Wmissing-prototypes] int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) ^ kernel/sched/rt.c:261:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) ^ static kernel/sched/rt.c:675:6: error: no previous prototype for function 'sched_rt_bandwidth_account' [-Werror,-Wmissing-prototypes] bool sched_rt_bandwidth_account(struct rt_rq *rt_rq) ^ kernel/sched/rt.c:675:1: note: declare 'static' if the function is not intended to be used outside of this translation unit bool sched_rt_bandwidth_account(struct rt_rq *rt_rq) ^ static 4 errors generated. vim +/unregister_rt_sched_group +257 kernel/sched/rt.c 256 258 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org