tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git tglx.2020.05.05a head: e6d36eed49b863bbe393e3c07cae737cd9c475e3 commit: ca303aa341bab5cdb3a3b41391ff262e252cd3f3 [105/140] x86/traps: Restructure #DB handling config: i386-tinyconfig (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout ca303aa341bab5cdb3a3b41391ff262e252cd3f3 # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; Note: the rcu/tglx.2020.05.05a HEAD e6d36eed49b863bbe393e3c07cae737cd9c475e3 builds fine. It only hurts bisectibility. All errors (new ones prefixed by >>, old ones prefixed by <<): arch/x86/kernel/traps.c: In function 'exc_debug_kernel': clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP); ^~~ arch/x86/kernel/traps.c:819:24: note: each undeclared identifier is reported only once for each function it appears in arch/x86/kernel/traps.c: In function 'exc_debug_user': arch/x86/kernel/traps.c:842:24: error: 'tsk' undeclared (first use in this function) clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP); ^~~ vim +/tsk +819 arch/x86/kernel/traps.c 809 810 static __always_inline void exc_debug_kernel(struct pt_regs *regs, 811 unsigned long dr6) 812 { 813 nmi_enter(); 814 /* 815 * The SDM says "The processor clears the BTF flag when it 816 * generates a debug exception." Clear TIF_BLOCKSTEP to keep 817 * TIF_BLOCKSTEP in sync with the hardware BTF flag. 818 */ 820 821 /* 822 * Catch SYSENTER with TF set and clear DR_STEP. If this hit a 823 * watchpoint at the same time then that will still be handled. 824 */ 825 if ((dr6 & DR_STEP) && is_sysenter_singlestep(regs)) 826 dr6 &= ~DR_STEP; 827 828 /* 829 * If DR6 is zero, no point in trying to handle it. The kernel is 830 * not using INT1. 831 */ 832 if (dr6) 833 handle_debug(regs, dr6, false); 834 835 nmi_exit(); 836 } 837 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org