Hi Andrei, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on soc/for-next] [also build test WARNING on arm/for-next kvmarm/next v5.7] [cannot apply to arm64/for-next/core next-20200602] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Andrei-Vagin/arm64-add-the-time-namespace-support/20200603-020504 base: https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next config: arm64-randconfig-r004-20200602 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 2388a096e7865c043e83ece4e26654bd3d1a20d5) 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 # 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: kbuild test robot All warnings (new ones prefixed by >>, old ones prefixed by <<): >> arch/arm64/kernel/vdso.c:93:19: warning: no previous prototype for function 'arch_get_vdso_data' [-Wmissing-prototypes] struct vdso_data *arch_get_vdso_data(void *vvar_page) ^ arch/arm64/kernel/vdso.c:93:1: note: declare 'static' if the function is not intended to be used outside of this translation unit struct vdso_data *arch_get_vdso_data(void *vvar_page) ^ static 1 warning generated. vim +/arch_get_vdso_data +93 arch/arm64/kernel/vdso.c 91 92 > 93 struct vdso_data *arch_get_vdso_data(void *vvar_page) 94 { 95 return (struct vdso_data *)(vvar_page); 96 } 97 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org