Hi Paul, First bad commit (maybe != root cause):

tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next head: 398b53b5b3751726c05f14a4331b0de258c0453a commit: a20b5bd09813bc981ab0bb01cfd7672017f8d74e [125/128] rcuperf: Change rcuperf to rcuscale config: x86_64-allyesconfig (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): git checkout a20b5bd09813bc981ab0bb01cfd7672017f8d74e # save the attached .config to linux build tree make W=1 ARCH=x86_64 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 >>): In file included from include/linux/kernel.h:15, from kernel/rcu/rcuscale.c:13: kernel/rcu/rcuscale.c: In function 'rcu_scale_writer': >> kernel/rcu/rcuscale.c:430:6: error: 'perf_type' undeclared (first use in this function); did you mean 'kernfs_type'? 430 | perf_type, PERF_FLAG, me, MIN_MEAS); | ^~~~~~~~~ include/linux/printk.h:319:35: note: in definition of macro 'pr_alert' 319 | printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) | ^~~~~~~~~~~ kernel/rcu/rcuscale.c:430:6: note: each undeclared identifier is reported only once for each function it appears in 430 | perf_type, PERF_FLAG, me, MIN_MEAS); | ^~~~~~~~~ include/linux/printk.h:319:35: note: in definition of macro 'pr_alert' 319 | printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) | ^~~~~~~~~~~ >> kernel/rcu/rcuscale.c:430:17: error: 'PERF_FLAG' undeclared (first use in this function) 430 | perf_type, PERF_FLAG, me, MIN_MEAS); | ^~~~~~~~~ include/linux/printk.h:319:35: note: in definition of macro 'pr_alert' 319 | printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) | ^~~~~~~~~~~ >> kernel/rcu/rcuscale.c:431:27: error: 'n_rcu_perf_writer_finished' undeclared (first use in this function); did you mean 'n_rcu_scale_writer_finished'? 431 | if (atomic_inc_return(&n_rcu_perf_writer_finished) >= | ^~~~~~~~~~~~~~~~~~~~~~~~~~ | n_rcu_scale_writer_finished # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/com... git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git git fetch --no-tags rcu rcu/next git checkout a20b5bd09813bc981ab0bb01cfd7672017f8d74e vim +430 kernel/rcu/rcuscale.c 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 353 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 354 /* a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 355 * RCU scale writer kthread. Repeatedly does a grace period. 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 356 */ 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 357 static int a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 358 rcu_scale_writer(void *arg) 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 359 { 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 360 int i = 0; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 361 int i_max; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 362 long me = (long)arg; 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 363 struct rcu_head *rhp = NULL; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 364 bool started = false, done = false, alldone = false; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 365 u64 t; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 366 u64 *wdp; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 367 u64 *wdpp = writer_durations[me]; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 368 a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 369 VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started"); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 370 WARN_ON(!wdpp); 6b558c4c7a4ba4 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-12 371 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); b1433395c4cc07 kernel/rcu/rcuperf.c Peter Zijlstra 2020-04-21 372 sched_set_fifo_low(current); df37e66bfdbb57 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-30 373 df37e66bfdbb57 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-30 374 if (holdoff) df37e66bfdbb57 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-30 375 schedule_timeout_uninterruptible(holdoff * HZ); df37e66bfdbb57 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-30 376 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 377) /* 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 378) * Wait until rcu_end_inkernel_boot() is called for normal GP tests 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 379) * so that RCU is not always expedited for normal GP tests. 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 380) * The system_state test is approximate, but works well in practice. 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 381) */ 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 382) while (!gp_exp && system_state != SYSTEM_RUNNING) 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 383) schedule_timeout_uninterruptible(1); 77e9752ce69f36 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-07-04 384) 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 385 t = ktime_get_mono_fast_ns(); a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 386 if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) { a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 387 t_rcu_scale_writer_started = t; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 388 if (gp_exp) { e6e78b004fa7e0 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-08-30 389) b_rcu_gp_test_started = 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 390 cur_ops->exp_completed() / 2; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 391 } else { e6e78b004fa7e0 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-08-30 392) b_rcu_gp_test_started = cur_ops->get_gp_seq(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 393 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 394 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 395 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 396 do { 820687a7b98a50 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-25 397 if (writer_holdoff) 820687a7b98a50 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-25 398 udelay(writer_holdoff); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 399 wdp = &wdpp[i]; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 400 *wdp = ktime_get_mono_fast_ns(); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 401 if (gp_async) { 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 402 retry: 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 403 if (!rhp) 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 404 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 405 if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) { 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 406 atomic_inc(this_cpu_ptr(&n_async_inflight)); a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 407 cur_ops->async(rhp, rcu_scale_async_cb); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 408 rhp = NULL; 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 409 } else if (!kthread_should_stop()) { 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 410 cur_ops->gp_barrier(); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 411 goto retry; 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 412 } else { 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 413 kfree(rhp); /* Because we are stopping. */ 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 414 } 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 415 } else if (gp_exp) { 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 416 cur_ops->exp_sync(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 417 } else { 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 418 cur_ops->sync(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 419 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 420 t = ktime_get_mono_fast_ns(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 421 *wdp = t - *wdp; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 422 i_max = i; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 423 if (!started && a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 424 atomic_read(&n_rcu_scale_writer_started) >= nrealwriters) 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 425 started = true; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 426 if (!done && i >= MIN_MEAS) { 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 427 done = true; b1433395c4cc07 kernel/rcu/rcuperf.c Peter Zijlstra 2020-04-21 428 sched_set_normal(current, 0); a56fefa2605cf8 kernel/rcu/rcuperf.c SeongJae Park 2016-08-21 429 pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n", a56fefa2605cf8 kernel/rcu/rcuperf.c SeongJae Park 2016-08-21 @430 perf_type, PERF_FLAG, me, MIN_MEAS); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 @431 if (atomic_inc_return(&n_rcu_perf_writer_finished) >= 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 432 nrealwriters) { 620316e52a9238 kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-30 433 schedule_timeout_interruptible(10); ac2bb275e8e5ab kernel/rcu/rcuperf.c Paul E. McKenney 2016-01-29 434 rcu_ftrace_dump(DUMP_ALL); a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 435 SCALEOUT_STRING("Test complete"); a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 436 t_rcu_scale_writer_finished = t; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 437 if (gp_exp) { e6e78b004fa7e0 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-08-30 438) b_rcu_gp_test_finished = 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 439 cur_ops->exp_completed() / 2; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 440 } else { e6e78b004fa7e0 kernel/rcu/rcuperf.c Joel Fernandes (Google 2019-08-30 441) b_rcu_gp_test_finished = 17ef2fe97c8c8e kernel/rcu/rcuperf.c Paul E. McKenney 2018-04-27 442 cur_ops->get_gp_seq(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 443 } e6fb1fc1085e5b kernel/rcu/rcuperf.c Artem Savkov 2016-02-07 444 if (shutdown) { 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 445 smp_mb(); /* Assign before wake. */ 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 446 wake_up(&shutdown_wq); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 447 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 448 } e6fb1fc1085e5b kernel/rcu/rcuperf.c Artem Savkov 2016-02-07 449 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 450 if (done && !alldone && a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 451 atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters) 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 452 alldone = true; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 453 if (started && !alldone && i < MAX_MEAS - 1) 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 454 i++; a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 455 rcu_scale_wait_shutdown(); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 456 } while (!torture_must_stop()); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 457 if (gp_async) { 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 458 cur_ops->gp_barrier(); 881ed593a323c8 kernel/rcu/rcuperf.c Paul E. McKenney 2017-04-17 459 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 460 writer_n_durations[me] = i_max; a20b5bd09813bc kernel/rcu/rcuscale.c Paul E. McKenney 2020-08-11 461 torture_kthread_stopping("rcu_scale_writer"); 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 462 return 0; 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 463 } 8704baab9bc848 kernel/rcu/rcuperf.c Paul E. McKenney 2015-12-31 464 :::::: The code at line 430 was first introduced by commit :::::: a56fefa2605cf8e125ef09451487f30336128028 rcuperf: Consistently insert space between flag and message :::::: TO: SeongJae Park <sj38.park(a)gmail.com&gt; :::::: CC: Paul E. McKenney <paulmck(a)linux.vnet.ibm.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org