Hi Nick, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 84196390620ac0e5070ae36af84c137c6216a7dc commit: 1e1b6d63d6340764e00356873e5794225a2a03ea lib/string.c: implement stpcpy date: 6 months ago config: s390-randconfig-r031-20210322 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 14696baaf4c43fe53f738bc292bbe169eed93d5d) 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 s390 cross compiling tool for clang build # apt-get install binutils-s390x-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 1e1b6d63d6340764e00356873e5794225a2a03ea # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 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 >>, old ones prefixed by <<): ERROR: modpost: "devm_ioremap_resource" [drivers/dma/idma64.ko] undefined! ERROR: modpost: "devm_ioremap" [drivers/dma/altera-msgdma.ko] undefined! ERROR: modpost: "devm_ioremap_resource" [drivers/dma/qcom/hdma.ko] undefined! --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org