Hi Heiko,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y
head:   65f1995ea1e930674e76c5888b4643581e11434c
commit: ba02635769f18a9231aba6e032d65f1fa6c537b4 [3754/3969] init/Kconfig: make COMPILE_TEST depend on !S390
config: s390-buildonly-randconfig-r002-20210731 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 4f71f59bf3d9914188a11d0c41bedbb339d36ff5)
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/stable/linux-stable-rc.git/commit/?id=ba02635769f18a9231aba6e032d65f1fa6c537b4
        git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
        git fetch --no-tags linux-stable-rc linux-5.10.y
        git checkout ba02635769f18a9231aba6e032d65f1fa6c537b4
        # 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@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "devm_ioremap" [drivers/input/keyboard/samsung-keypad.ko] undefined!

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org