tree: https://github.com/alexshi/linux.git lrunext0813 head: 1c1171d98eb66e2baa74b742c64b7274d94f2f74 commit: 79404b968cecd4e1b666078ffa3ac7e9dbbf6559 [28/29] mm/pageblock: mitigation cmpxchg false sharing in pageblock flags config: arm-allyesconfig (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 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 git checkout 79404b968cecd4e1b666078ffa3ac7e9dbbf6559 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 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 >>): arm-linux-gnueabi-ld: mm/page_alloc.o: in function `set_pfnblock_flags_mask': arm-linux-gnueabi-ld: drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.o: in function `hw_atl_b0_get_mac_temp': hw_atl_b0.c:(.text+0x30fc): undefined reference to `__bad_udelay' --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org