tree: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git sched/lazymm head: c0d03d4f2778fd0a7c16e69cdfb3f111296129b5 commit: 23ef8314367945e2dd63230fb1c2ebb7e148fe48 [11/16] Rework "sched/core: Fix illegal RCU from offline CPUs" config: i386-randconfig-c021-20211117 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?id... git remote add luto https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git git fetch --no-tags luto sched/lazymm git checkout 23ef8314367945e2dd63230fb1c2ebb7e148fe48 # save the attached .config to linux build tree mkdir build_dir make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash 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 >>): ld: kernel/sched/idle.o: in function `do_idle': vim +288 kernel/sched/idle.c 255 256 /* 257 * Generic idle loop implementation 258 * 259 * Called with polling cleared. 260 */ 261 static void do_idle(void) 262 { 263 int cpu = smp_processor_id(); 264 265 /* 266 * Check if we need to update blocked load 267 */ 268 nohz_run_idle_balance(cpu); 269 270 /* 271 * If the arch has a polling bit, we maintain an invariant: 272 * 273 * Our polling bit is clear if we're not scheduled (i.e. if rq->curr != 274 * rq->idle). This means that, if rq->idle has the polling bit set, 275 * then setting need_resched is guaranteed to cause the CPU to 276 * reschedule. 277 */ 278 279 __current_set_polling(); 280 tick_nohz_idle_enter(); 281 282 while (!need_resched()) { 283 rmb(); 284 285 local_irq_disable(); 286 287 if (cpu_is_offline(cpu)) { 289 tick_nohz_idle_stop_tick(); 290 cpuhp_report_idle_dead(); 291 arch_cpu_idle_dead(); 292 } 293 294 arch_cpu_idle_enter(); 295 rcu_nocb_flush_deferred_wakeup(); 296 297 /* 298 * In poll mode we reenable interrupts and spin. Also if we 299 * detected in the wakeup from idle path that the tick 300 * broadcast device expired for us, we don't want to go deep 301 * idle as we know that the IPI is going to arrive right away. 302 */ 303 if (cpu_idle_force_poll || tick_check_broadcast_expired()) { 304 tick_nohz_idle_restart_tick(); 305 cpu_idle_poll(); 306 } else { 307 cpuidle_idle_call(); 308 } 309 arch_cpu_idle_exit(); 310 } 311 312 /* 313 * Since we fell out of the loop above, we know TIF_NEED_RESCHED must 314 * be set, propagate it into PREEMPT_NEED_RESCHED. 315 * 316 * This is required because for polling idle loops we will not have had 317 * an IPI to fold the state for us. 318 */ 319 preempt_set_need_resched(); 320 tick_nohz_idle_exit(); 321 __current_clr_polling(); 322 323 /* 324 * We promise to call sched_ttwu_pending() and reschedule if 325 * need_resched() is set while polling is set. That means that clearing 326 * polling needs to be visible before doing these things. 327 */ 328 smp_mb__after_atomic(); 329 330 /* 331 * RCU relies on this call to be done outside of an RCU read-side 332 * critical section. 333 */ 334 flush_smp_call_function_from_idle(); 335 schedule_idle(); 336 337 if (unlikely(klp_patch_pending(current))) 338 klp_update_patch_state(current); 339 } 340 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org