tree: https://github.com/intel/linux-intel-lts.git 5.4/preempt-rt head: 2046457bf9f4a420f69e915453d59db5b38edbaa commit: 3c3f9863f8b96ccbf6fd420c93f1685f6085651a [15/16] Merge tag 'lts-v5.4.58-yocto-200825T002733Z' into lts2019/yocto-rt config: arm64-randconfig-r005-20210610 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project d2012d965d60c3258b3a69d024491698f8aec386) 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 arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu # https://github.com/intel/linux-intel-lts/commit/3c3f9863f8b96ccbf6fd420c9... git remote add intel-linux-intel-lts https://github.com/intel/linux-intel-lts.git git fetch --no-tags intel-linux-intel-lts 5.4/preempt-rt git checkout 3c3f9863f8b96ccbf6fd420c93f1685f6085651a # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): int vprintk_default(const char *fmt, va_list args) ^ kernel/printk/printk.c:2014:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int vprintk_default(const char *fmt, va_list args) ^ static 1 warning generated. -- static DEFINE_LOCAL_IRQ_LOCK(sp_llock); ^ 1 warning generated. -- lib/radix-tree.c:301:6: warning: no previous prototype for function 'radix_tree_node_rcu_free' [-Wmissing-prototypes] void radix_tree_node_rcu_free(struct rcu_head *head) ^ lib/radix-tree.c:301:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void radix_tree_node_rcu_free(struct rcu_head *head) ^ static static DEFINE_LOCAL_IRQ_LOCK(radix_tree_preloads_lock); ^ 2 warnings generated. -- static DEFINE_LOCAL_IRQ_LOCK(rotate_lock); ^ 1 warning generated. -- mm/page_alloc.c:6098:23: warning: no previous prototype for function 'memmap_init' [-Wmissing-prototypes] void __meminit __weak memmap_init(unsigned long size, int nid, ^ mm/page_alloc.c:6098:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __meminit __weak memmap_init(unsigned long size, int nid, ^ static static DEFINE_LOCAL_IRQ_LOCK(pa_lock); ^ 2 warnings generated. -- static DEFINE_LOCAL_IRQ_LOCK(event_lock); ^ mm/memcontrol.c:1010:43: warning: unused function 'get_mem_cgroup_from_current' [-Wunused-function] static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void) ^ 2 warnings generated. -- static DEFINE_LOCAL_IRQ_LOCK(zs_map_area_lock); ^ 1 warning generated. vim +/vprintk_default +2014 kernel/printk/printk.c ^1da177e4c3f41 kernel/printk.c Linus Torvalds 2005-04-16 2013 a0cba2179ea4c1 kernel/printk/printk.c Linus Torvalds 2016-08-09 @2014 int vprintk_default(const char *fmt, va_list args) afdc34a3d3b823 kernel/printk/printk.c Steven Rostedt (Red Hat 2014-06-19 2015) { afdc34a3d3b823 kernel/printk/printk.c Steven Rostedt (Red Hat 2014-06-19 2016) int r; afdc34a3d3b823 kernel/printk/printk.c Steven Rostedt (Red Hat 2014-06-19 2017) :::::: The code at line 2014 was first introduced by commit :::::: a0cba2179ea4c1820fce2ee046b6ed90ecc56196 Revert "printk: create pr_<level> functions" :::::: TO: Linus Torvalds <torvalds(a)linux-foundation.org&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org