Hi Steve, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git 20210916-firmware-builtin-v2 head: f69194f4bcf5b301f2d169b2f036c0da4b642e53 commit: b4a8c8f8fa8b7b86bb62257fbb27e7bde58ac97e [1565/2476] cifs: rename fs/cifs directory to fs/smbfs_client config: x86_64-randconfig-a003-20210928 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project dc6e8dfdfe7efecfda318d43a06fae18b40eb498) 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/commit/?id=b4a8c8f8fa8b7b86bb62257fbb27e7bde58ac97e git remote add mcgrof-next https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git git fetch --no-tags mcgrof-next 20210916-firmware-builtin-v2 git checkout b4a8c8f8fa8b7b86bb62257fbb27e7bde58ac97e # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> fs/smbfs_client/cifsroot.c:83:12: warning: no previous prototype for function 'cifs_root_data' [-Wmissing-prototypes] int __init cifs_root_data(char **dev, char **opts) ^ fs/smbfs_client/cifsroot.c:83:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int __init cifs_root_data(char **dev, char **opts) ^ static 1 warning generated. vim +/cifs_root_data +83 fs/smbfs_client/cifsroot.c 8eecd1c2e5bc73d fs/cifs/cifsroot.c Paulo Alcantara (SUSE 2019-07-16 82) 8eecd1c2e5bc73d fs/cifs/cifsroot.c Paulo Alcantara (SUSE 2019-07-16 @83) int __init cifs_root_data(char **dev, char **opts) :::::: The code at line 83 was first introduced by commit :::::: 8eecd1c2e5bc73d33f3a544751305679dbf88eb4 cifs: Add support for root file systems :::::: TO: Paulo Alcantara (SUSE) :::::: CC: Steve French --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org