Hi Christoph, First bad commit (maybe != root cause): tree: git://git.infradead.org/users/hch/misc.git set_fs-removal head: 153bec971d1618bc5abb582c90a6de920fe00e59 commit: c3088068d50e2622ccfffadf9f809a97a87835f6 [23/85] md: move the early init autodetect code to drivers/md/ config: x86_64-allyesconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project bc2b70982be8f5250cd0082a7190f8b417bd4dfe) 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 x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu git checkout c3088068d50e2622ccfffadf9f809a97a87835f6 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 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 >>, old ones prefixed by <<): void __init md_run_setup(void) ^ drivers/md/md-autodetect.c:305:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __init md_run_setup(void) ^ static 1 warning generated. vim +/md_run_setup +305 drivers/md/md-autodetect.c 82cbc11a4146d6 init/do_mounts_md.c Ingo Molnar 2008-08-18 304 82cbc11a4146d6 init/do_mounts_md.c Ingo Molnar 2008-08-18 @305 void __init md_run_setup(void) :::::: The code at line 305 was first introduced by commit :::::: 82cbc11a4146d6a8acd81f81f7fe17387668107f warning: fix init do_mounts_md c :::::: TO: Ingo Molnar <mingo(a)elte.hu&gt; :::::: CC: Arjan van de Ven <arjan(a)linux.intel.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org