Hi Paul, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2021.08.25a head: 2ba1d046d9bc5b4496027d120e3ddcdfbb2fe9f4 commit: 545fb85f707c973cc4f1718572e33267c9c110a2 [77/115] EXP cpu: Make cpu_hp_check_delay() return true when detecting an anomaly config: arc-randconfig-r001-20210915 (attached as .config) compiler: arc-elf-gcc (GCC) 11.2.0 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 # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/com... git remote add paulmck-rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git git fetch --no-tags paulmck-rcu dev.2021.08.25a git checkout 545fb85f707c973cc4f1718572e33267c9c110a2 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arc 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 >>): kernel/cpu.c:137:6: error: redefinition of 'cpu_hp_start_now' 137 | void cpu_hp_start_now(void) | ^~~~~~~~~~~~~~~~ In file included from kernel/cpu.c:17: include/linux/cpu.h:147:20: note: previous definition of 'cpu_hp_start_now' with type 'void(void)' 147 | static inline void cpu_hp_start_now(void) { } | ^~~~~~~~~~~~~~~~ kernel/cpu.c:146:6: error: redefinition of 'cpu_hp_stop_now' 146 | void cpu_hp_stop_now(void) | ^~~~~~~~~~~~~~~ In file included from kernel/cpu.c:17: include/linux/cpu.h:148:20: note: previous definition of 'cpu_hp_stop_now' with type 'void(void)' 148 | static inline void cpu_hp_stop_now(void) { } | ^~~~~~~~~~~~~~~ 158 | bool cpu_hp_check_delay(const char *s, const void *func) | ^~~~~~~~~~~~~~~~~~ In file included from kernel/cpu.c:17: include/linux/cpu.h:149:20: note: previous definition of 'cpu_hp_check_delay' with type 'bool(const char *, void *)' {aka '_Bool(const char *, void *)'} 149 | static inline bool cpu_hp_check_delay(const char *s, void *func) { return false; } | ^~~~~~~~~~~~~~~~~~ In file included from arch/arc/include/asm/bug.h:30, from include/linux/bug.h:5, from include/linux/thread_info.h:13, from include/asm-generic/preempt.h:5, from ./arch/arc/include/generated/asm/preempt.h:1, from include/linux/preempt.h:78, from include/linux/rcupdate.h:27, from include/linux/rculist.h:11, from include/linux/pid.h:5, from include/linux/sched.h:14, from include/linux/sched/mm.h:7, from kernel/cpu.c:6: kernel/cpu.c: In function 'cpu_hp_check_delay': kernel/cpu.c:170:48: warning: integer overflow in expression of type 'long int' results in '1215752192' [-Woverflow] 170 | if (WARN_ONCE(time_after64(t1, t + 100 * NSEC_PER_SEC), "%s %ps took %llu milliseconds\n", s, func, (t1 - t) / NSEC_PER_MSEC)) { | ^ include/asm-generic/bug.h:173:32: note: in definition of macro 'WARN' 173 | int __ret_warn_on = !!(condition); \ | ^~~~~~~~~ kernel/cpu.c:170:13: note: in expansion of macro 'WARN_ONCE' 170 | if (WARN_ONCE(time_after64(t1, t + 100 * NSEC_PER_SEC), "%s %ps took %llu milliseconds\n", s, func, (t1 - t) / NSEC_PER_MSEC)) { | ^~~~~~~~~ kernel/cpu.c:170:23: note: in expansion of macro 'time_after64' 170 | if (WARN_ONCE(time_after64(t1, t + 100 * NSEC_PER_SEC), "%s %ps took %llu milliseconds\n", s, func, (t1 - t) / NSEC_PER_MSEC)) { | ^~~~~~~~~~~~ vim +158 kernel/cpu.c 156 157 /* Return true if a time-delay anomaly was detected. */ 159 { 160 bool ret = false; 161 u64 t, t1; 162 163 if (!smp_load_acquire(&cpu_hp_start_time_valid)) 164 return false; 165 t = READ_ONCE(cpu_hp_start_time); 166 smp_mb(); 167 if (!READ_ONCE(cpu_hp_start_time_valid)) 168 return false; 169 t1 = ktime_get(); 170 if (WARN_ONCE(time_after64(t1, t + 100 * NSEC_PER_SEC), "%s %ps took %llu milliseconds\n", s, func, (t1 - t) / NSEC_PER_MSEC)) { 171 WRITE_ONCE(cpu_hp_start_time, t1); 172 ret = true; 173 } 174 if (WARN_ONCE(time_before64(t1, t - 25 * NSEC_PER_MSEC), "%s %ps clock went backwards %llu milliseconds\n", s, func, (t - t1) / NSEC_PER_MSEC)){ 175 WRITE_ONCE(cpu_hp_start_time, t1); 176 ret = true; 177 } 178 return ret; 179 } 180 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org