Hi Dmitry, Thank you for the patch! Yet something to improve: [auto build test ERROR on linus/master] [cannot apply to v5.4-rc2 next-20191010] [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/Dmitry-Safonov/kernel-Introduce-... config: parisc-b180_defconfig (attached as .config) compiler: hppa-linux-gcc (GCC) 7.4.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=7.4.0 make.cross ARCH=parisc If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): kernel/time/namespace.o: In function `timens_set_vvar_page.isra.8.part.9': (.text+0x130): undefined reference to `arch_get_vdso_data' kernel/time/namespace.o: In function `timens_install': kernel/time/namespace.o: In function `timens_on_fork': (.text+0x804): undefined reference to `vdso_join_timens' --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation