tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.09.07a head: cccf684a1da846c3ff830d553bc4cf97bf779f48 commit: cccf684a1da846c3ff830d553bc4cf97bf779f48 [23/23] rcu-tasks: Mass of debug and fixes config: ia64-defconfig (attached as .config) compiler: ia64-linux-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 cccf684a1da846c3ff830d553bc4cf97bf779f48 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 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 >>): ia64-linux-ld: kernel/sched/core.o: in function `try_invoke_on_locked_down_task': core.c:(.text+0x86b0): undefined reference to `n_rtt_sched' ia64-linux-ld: core.c:(.text+0x8811): undefined reference to `n_rtt_sched_waking' ia64-linux-ld: core.c:(.text+0x8851): undefined reference to `n_rtt_sched_fail' ia64-linux-ld: core.c:(.text+0x88a1): undefined reference to `n_rtt_sched_running' ia64-linux-ld: core.c:(.text+0x88e0): undefined reference to `n_rtt_sched_fail' ia64-linux-ld: core.c:(.text+0x88e1): undefined reference to `n_rtt_sched_fail' ia64-linux-ld: core.c:(.text+0x8991): undefined reference to `n_rtt_sched_offrq' ia64-linux-ld: core.c:(.text+0x8a91): undefined reference to `n_rtt_sched_onrq' --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org