1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Detect hard and soft lockups on a system 4 * 5 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. 6 * 7 * Note: Most of this code is borrowed heavily from the original softlockup 8 * detector, so thanks to Ingo for the initial implementation. 9 * Some chunks also taken from the old x86-specific nmi watchdog code, thanks 10 * to those contributors as well. 11 */ 12 13 #define pr_fmt(fmt) "watchdog: " fmt 14 15 #include <linux/cpu.h> 16 #include <linux/init.h> 17 #include <linux/irq.h> 18 #include <linux/irqdesc.h> 19 #include <linux/kernel_stat.h> 20 #include <linux/kvm_para.h> 21 #include <linux/math64.h> 22 #include <linux/mm.h> 23 #include <linux/module.h> 24 #include <linux/nmi.h> 25 #include <linux/stop_machine.h> 26 #include <linux/sysctl.h> 27 #include <linux/tick.h> 28 #include <linux/sys_info.h> 29 30 #include <linux/sched/clock.h> 31 #include <linux/sched/debug.h> 32 #include <linux/sched/isolation.h> 33 34 #include <asm/irq_regs.h> 35 36 static DEFINE_MUTEX(watchdog_mutex); 37 38 #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HARDLOCKUP_DETECTOR_SPARC64) 39 # define WATCHDOG_HARDLOCKUP_DEFAULT 1 40 #else 41 # define WATCHDOG_HARDLOCKUP_DEFAULT 0 42 #endif 43 44 #define NUM_SAMPLE_PERIODS 5 45 46 unsigned long __read_mostly watchdog_enabled; 47 int __read_mostly watchdog_user_enabled = 1; 48 static int __read_mostly watchdog_hardlockup_user_enabled = WATCHDOG_HARDLOCKUP_DEFAULT; 49 static int __read_mostly watchdog_softlockup_user_enabled = 1; 50 int __read_mostly watchdog_thresh = 10; 51 static int __read_mostly watchdog_thresh_next; 52 static int __read_mostly watchdog_hardlockup_available; 53 54 struct cpumask watchdog_cpumask __read_mostly; 55 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); 56 57 #ifdef CONFIG_HARDLOCKUP_DETECTOR 58 59 # ifdef CONFIG_SMP 60 int __read_mostly sysctl_hardlockup_all_cpu_backtrace; 61 # endif /* CONFIG_SMP */ 62 63 /* 64 * Should we panic when a soft-lockup or hard-lockup occurs: 65 */ 66 unsigned int __read_mostly hardlockup_panic = 67 IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC); 68 69 /* 70 * bitmasks to control what kinds of system info to be printed when 71 * hard lockup is detected, it could be task, memory, lock etc. 72 * Refer include/linux/sys_info.h for detailed bit definition. 73 */ 74 unsigned long hardlockup_si_mask; 75 76 #ifdef CONFIG_SYSFS 77 78 static unsigned int hardlockup_count; 79 80 static ssize_t hardlockup_count_show(struct kobject *kobj, struct kobj_attribute *attr, 81 char *page) 82 { 83 return sysfs_emit(page, "%u\n", hardlockup_count); 84 } 85 86 static struct kobj_attribute hardlockup_count_attr = __ATTR_RO(hardlockup_count); 87 88 static __init int kernel_hardlockup_sysfs_init(void) 89 { 90 sysfs_add_file_to_group(kernel_kobj, &hardlockup_count_attr.attr, NULL); 91 return 0; 92 } 93 94 late_initcall(kernel_hardlockup_sysfs_init); 95 96 #endif // CONFIG_SYSFS 97 98 /* 99 * We may not want to enable hard lockup detection by default in all cases, 100 * for example when running the kernel as a guest on a hypervisor. In these 101 * cases this function can be called to disable hard lockup detection. This 102 * function should only be executed once by the boot processor before the 103 * kernel command line parameters are parsed, because otherwise it is not 104 * possible to override this in hardlockup_panic_setup(). 105 */ 106 void __init hardlockup_detector_disable(void) 107 { 108 watchdog_hardlockup_user_enabled = 0; 109 } 110 111 static int __init hardlockup_panic_setup(char *str) 112 { 113 next: 114 if (!strncmp(str, "panic", 5)) 115 hardlockup_panic = 1; 116 else if (!strncmp(str, "nopanic", 7)) 117 hardlockup_panic = 0; 118 else if (!strncmp(str, "0", 1)) 119 watchdog_hardlockup_user_enabled = 0; 120 else if (!strncmp(str, "1", 1)) 121 watchdog_hardlockup_user_enabled = 1; 122 else if (!strncmp(str, "r", 1)) 123 hardlockup_config_perf_event(str + 1); 124 while (*(str++)) { 125 if (*str == ',') { 126 str++; 127 goto next; 128 } 129 } 130 return 1; 131 } 132 __setup("nmi_watchdog=", hardlockup_panic_setup); 133 134 #endif /* CONFIG_HARDLOCKUP_DETECTOR */ 135 136 #if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER) 137 138 static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts); 139 static DEFINE_PER_CPU(int, hrtimer_interrupts_saved); 140 static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned); 141 static DEFINE_PER_CPU(bool, watchdog_hardlockup_touched); 142 static unsigned long hard_lockup_nmi_warn; 143 144 notrace void arch_touch_nmi_watchdog(void) 145 { 146 /* 147 * Using __raw here because some code paths have 148 * preemption enabled. If preemption is enabled 149 * then interrupts should be enabled too, in which 150 * case we shouldn't have to worry about the watchdog 151 * going off. 152 */ 153 raw_cpu_write(watchdog_hardlockup_touched, true); 154 } 155 EXPORT_SYMBOL(arch_touch_nmi_watchdog); 156 157 void watchdog_hardlockup_touch_cpu(unsigned int cpu) 158 { 159 per_cpu(watchdog_hardlockup_touched, cpu) = true; 160 } 161 162 static bool is_hardlockup(unsigned int cpu) 163 { 164 int hrint = atomic_read(&per_cpu(hrtimer_interrupts, cpu)); 165 166 if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) 167 return true; 168 169 /* 170 * NOTE: we don't need any fancy atomic_t or READ_ONCE/WRITE_ONCE 171 * for hrtimer_interrupts_saved. hrtimer_interrupts_saved is 172 * written/read by a single CPU. 173 */ 174 per_cpu(hrtimer_interrupts_saved, cpu) = hrint; 175 176 return false; 177 } 178 179 static void watchdog_hardlockup_kick(void) 180 { 181 int new_interrupts; 182 183 new_interrupts = atomic_inc_return(this_cpu_ptr(&hrtimer_interrupts)); 184 watchdog_buddy_check_hardlockup(new_interrupts); 185 } 186 187 void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs) 188 { 189 int hardlockup_all_cpu_backtrace; 190 191 if (per_cpu(watchdog_hardlockup_touched, cpu)) { 192 per_cpu(watchdog_hardlockup_touched, cpu) = false; 193 return; 194 } 195 196 hardlockup_all_cpu_backtrace = (hardlockup_si_mask & SYS_INFO_ALL_BT) ? 197 1 : sysctl_hardlockup_all_cpu_backtrace; 198 /* 199 * Check for a hardlockup by making sure the CPU's timer 200 * interrupt is incrementing. The timer interrupt should have 201 * fired multiple times before we overflow'd. If it hasn't 202 * then this is a good indication the cpu is stuck 203 */ 204 if (is_hardlockup(cpu)) { 205 unsigned int this_cpu = smp_processor_id(); 206 unsigned long flags; 207 208 #ifdef CONFIG_SYSFS 209 ++hardlockup_count; 210 #endif 211 /* 212 * A poorly behaving BPF scheduler can trigger hard lockup by 213 * e.g. putting numerous affinitized tasks in a single queue and 214 * directing all CPUs at it. The following call can return true 215 * only once when sched_ext is enabled and will immediately 216 * abort the BPF scheduler and print out a warning message. 217 */ 218 if (scx_hardlockup(cpu)) 219 return; 220 221 /* Only print hardlockups once. */ 222 if (per_cpu(watchdog_hardlockup_warned, cpu)) 223 return; 224 225 /* 226 * Prevent multiple hard-lockup reports if one cpu is already 227 * engaged in dumping all cpu back traces. 228 */ 229 if (hardlockup_all_cpu_backtrace) { 230 if (test_and_set_bit_lock(0, &hard_lockup_nmi_warn)) 231 return; 232 } 233 234 /* 235 * NOTE: we call printk_cpu_sync_get_irqsave() after printing 236 * the lockup message. While it would be nice to serialize 237 * that printout, we really want to make sure that if some 238 * other CPU somehow locked up while holding the lock associated 239 * with printk_cpu_sync_get_irqsave() that we can still at least 240 * get the message about the lockup out. 241 */ 242 pr_emerg("CPU%u: Watchdog detected hard LOCKUP on cpu %u\n", this_cpu, cpu); 243 printk_cpu_sync_get_irqsave(flags); 244 245 print_modules(); 246 print_irqtrace_events(current); 247 if (cpu == this_cpu) { 248 if (regs) 249 show_regs(regs); 250 else 251 dump_stack(); 252 printk_cpu_sync_put_irqrestore(flags); 253 } else { 254 printk_cpu_sync_put_irqrestore(flags); 255 trigger_single_cpu_backtrace(cpu); 256 } 257 258 if (hardlockup_all_cpu_backtrace) { 259 trigger_allbutcpu_cpu_backtrace(cpu); 260 if (!hardlockup_panic) 261 clear_bit_unlock(0, &hard_lockup_nmi_warn); 262 } 263 264 sys_info(hardlockup_si_mask & ~SYS_INFO_ALL_BT); 265 if (hardlockup_panic) 266 nmi_panic(regs, "Hard LOCKUP"); 267 268 per_cpu(watchdog_hardlockup_warned, cpu) = true; 269 } else { 270 per_cpu(watchdog_hardlockup_warned, cpu) = false; 271 } 272 } 273 274 #else /* CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */ 275 276 static inline void watchdog_hardlockup_kick(void) { } 277 278 #endif /* !CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */ 279 280 /* 281 * These functions can be overridden based on the configured hardlockdup detector. 282 * 283 * watchdog_hardlockup_enable/disable can be implemented to start and stop when 284 * softlockup watchdog start and stop. The detector must select the 285 * SOFTLOCKUP_DETECTOR Kconfig. 286 */ 287 void __weak watchdog_hardlockup_enable(unsigned int cpu) { } 288 289 void __weak watchdog_hardlockup_disable(unsigned int cpu) { } 290 291 /* 292 * Watchdog-detector specific API. 293 * 294 * Return 0 when hardlockup watchdog is available, negative value otherwise. 295 * Note that the negative value means that a delayed probe might 296 * succeed later. 297 */ 298 int __weak __init watchdog_hardlockup_probe(void) 299 { 300 return -ENODEV; 301 } 302 303 /** 304 * watchdog_hardlockup_stop - Stop the watchdog for reconfiguration 305 * 306 * The reconfiguration steps are: 307 * watchdog_hardlockup_stop(); 308 * update_variables(); 309 * watchdog_hardlockup_start(); 310 */ 311 void __weak watchdog_hardlockup_stop(void) { } 312 313 /** 314 * watchdog_hardlockup_start - Start the watchdog after reconfiguration 315 * 316 * Counterpart to watchdog_hardlockup_stop(). 317 * 318 * The following variables have been updated in update_variables() and 319 * contain the currently valid configuration: 320 * - watchdog_enabled 321 * - watchdog_thresh 322 * - watchdog_cpumask 323 */ 324 void __weak watchdog_hardlockup_start(void) { } 325 326 /** 327 * lockup_detector_update_enable - Update the sysctl enable bit 328 * 329 * Caller needs to make sure that the hard watchdogs are off, so this 330 * can't race with watchdog_hardlockup_disable(). 331 */ 332 static void lockup_detector_update_enable(void) 333 { 334 watchdog_enabled = 0; 335 if (!watchdog_user_enabled) 336 return; 337 if (watchdog_hardlockup_available && watchdog_hardlockup_user_enabled) 338 watchdog_enabled |= WATCHDOG_HARDLOCKUP_ENABLED; 339 if (watchdog_softlockup_user_enabled) 340 watchdog_enabled |= WATCHDOG_SOFTOCKUP_ENABLED; 341 } 342 343 #ifdef CONFIG_SOFTLOCKUP_DETECTOR 344 345 /* 346 * Delay the soflockup report when running a known slow code. 347 * It does _not_ affect the timestamp of the last successdul reschedule. 348 */ 349 #define SOFTLOCKUP_DELAY_REPORT ULONG_MAX 350 351 #ifdef CONFIG_SMP 352 int __read_mostly sysctl_softlockup_all_cpu_backtrace; 353 #endif 354 355 /* 356 * bitmasks to control what kinds of system info to be printed when 357 * soft lockup is detected, it could be task, memory, lock etc. 358 * Refer include/linux/sys_info.h for detailed bit definition. 359 */ 360 static unsigned long softlockup_si_mask; 361 362 static struct cpumask watchdog_allowed_mask __read_mostly; 363 364 /* Global variables, exported for sysctl */ 365 unsigned int __read_mostly softlockup_panic = 366 CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC; 367 368 static bool softlockup_initialized __read_mostly; 369 static u64 __read_mostly sample_period; 370 371 #ifdef CONFIG_SYSFS 372 373 static unsigned int softlockup_count; 374 375 static ssize_t softlockup_count_show(struct kobject *kobj, struct kobj_attribute *attr, 376 char *page) 377 { 378 return sysfs_emit(page, "%u\n", softlockup_count); 379 } 380 381 static struct kobj_attribute softlockup_count_attr = __ATTR_RO(softlockup_count); 382 383 static __init int kernel_softlockup_sysfs_init(void) 384 { 385 sysfs_add_file_to_group(kernel_kobj, &softlockup_count_attr.attr, NULL); 386 return 0; 387 } 388 389 late_initcall(kernel_softlockup_sysfs_init); 390 391 #endif // CONFIG_SYSFS 392 393 /* Timestamp taken after the last successful reschedule. */ 394 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); 395 /* Timestamp of the last softlockup report. */ 396 static DEFINE_PER_CPU(unsigned long, watchdog_report_ts); 397 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); 398 static DEFINE_PER_CPU(bool, softlockup_touch_sync); 399 static unsigned long soft_lockup_nmi_warn; 400 401 static int __init softlockup_panic_setup(char *str) 402 { 403 softlockup_panic = simple_strtoul(str, NULL, 0); 404 return 1; 405 } 406 __setup("softlockup_panic=", softlockup_panic_setup); 407 408 static int __init nowatchdog_setup(char *str) 409 { 410 watchdog_user_enabled = 0; 411 return 1; 412 } 413 __setup("nowatchdog", nowatchdog_setup); 414 415 static int __init nosoftlockup_setup(char *str) 416 { 417 watchdog_softlockup_user_enabled = 0; 418 return 1; 419 } 420 __setup("nosoftlockup", nosoftlockup_setup); 421 422 static int __init watchdog_thresh_setup(char *str) 423 { 424 get_option(&str, &watchdog_thresh); 425 return 1; 426 } 427 __setup("watchdog_thresh=", watchdog_thresh_setup); 428 429 #ifdef CONFIG_SOFTLOCKUP_DETECTOR_INTR_STORM 430 enum stats_per_group { 431 STATS_SYSTEM, 432 STATS_SOFTIRQ, 433 STATS_HARDIRQ, 434 STATS_IDLE, 435 NUM_STATS_PER_GROUP, 436 }; 437 438 static const enum cpu_usage_stat tracked_stats[NUM_STATS_PER_GROUP] = { 439 CPUTIME_SYSTEM, 440 CPUTIME_SOFTIRQ, 441 CPUTIME_IRQ, 442 CPUTIME_IDLE, 443 }; 444 445 static DEFINE_PER_CPU(u16, cpustat_old[NUM_STATS_PER_GROUP]); 446 static DEFINE_PER_CPU(u8, cpustat_util[NUM_SAMPLE_PERIODS][NUM_STATS_PER_GROUP]); 447 static DEFINE_PER_CPU(u8, cpustat_tail); 448 449 /* 450 * We don't need nanosecond resolution. A granularity of 16ms is 451 * sufficient for our precision, allowing us to use u16 to store 452 * cpustats, which will roll over roughly every ~1000 seconds. 453 * 2^24 ~= 16 * 10^6 454 */ 455 static u16 get_16bit_precision(u64 data_ns) 456 { 457 /* 458 * 2^24ns ~= 16.8ms 459 * Round to the nearest multiple of 16.8 milliseconds. 460 */ 461 return (data_ns + (1 << 23)) >> 24LL; 462 } 463 464 static void update_cpustat(void) 465 { 466 int i; 467 u8 util; 468 u16 old_stat, new_stat; 469 struct kernel_cpustat kcpustat; 470 u64 *cpustat = kcpustat.cpustat; 471 u8 tail = __this_cpu_read(cpustat_tail); 472 u16 sample_period_16 = get_16bit_precision(sample_period); 473 474 kcpustat_cpu_fetch(&kcpustat, smp_processor_id()); 475 476 for (i = 0; i < NUM_STATS_PER_GROUP; i++) { 477 old_stat = __this_cpu_read(cpustat_old[i]); 478 new_stat = get_16bit_precision(cpustat[tracked_stats[i]]); 479 util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16); 480 /* 481 * Since we use 16-bit precision, the raw data will undergo 482 * integer division, which may sometimes result in data loss, 483 * and then result might exceed 100%. To avoid confusion, 484 * we enforce a 100% display cap when calculations exceed this threshold. 485 */ 486 if (util > 100) 487 util = 100; 488 __this_cpu_write(cpustat_util[tail][i], util); 489 __this_cpu_write(cpustat_old[i], new_stat); 490 } 491 492 __this_cpu_write(cpustat_tail, (tail + 1) % NUM_SAMPLE_PERIODS); 493 } 494 495 static void print_cpustat(void) 496 { 497 int i, group; 498 u8 tail = __this_cpu_read(cpustat_tail); 499 u64 sample_period_msecond = sample_period; 500 501 do_div(sample_period_msecond, NSEC_PER_MSEC); 502 503 /* 504 * Outputting the "watchdog" prefix on every line is redundant and not 505 * concise, and the original alarm information is sufficient for 506 * positioning in logs, hence here printk() is used instead of pr_crit(). 507 */ 508 printk(KERN_CRIT "CPU#%d Utilization every %llums during lockup:\n", 509 smp_processor_id(), sample_period_msecond); 510 511 for (i = 0; i < NUM_SAMPLE_PERIODS; i++) { 512 group = (tail + i) % NUM_SAMPLE_PERIODS; 513 printk(KERN_CRIT "\t#%d: %3u%% system,\t%3u%% softirq,\t" 514 "%3u%% hardirq,\t%3u%% idle\n", i + 1, 515 __this_cpu_read(cpustat_util[group][STATS_SYSTEM]), 516 __this_cpu_read(cpustat_util[group][STATS_SOFTIRQ]), 517 __this_cpu_read(cpustat_util[group][STATS_HARDIRQ]), 518 __this_cpu_read(cpustat_util[group][STATS_IDLE])); 519 } 520 } 521 522 #define HARDIRQ_PERCENT_THRESH 50 523 #define NUM_HARDIRQ_REPORT 5 524 struct irq_counts { 525 int irq; 526 u32 counts; 527 }; 528 529 static DEFINE_PER_CPU(bool, snapshot_taken); 530 531 /* Tabulate the most frequent interrupts. */ 532 static void tabulate_irq_count(struct irq_counts *irq_counts, int irq, u32 counts, int rank) 533 { 534 int i; 535 struct irq_counts new_count = {irq, counts}; 536 537 for (i = 0; i < rank; i++) { 538 if (counts > irq_counts[i].counts) 539 swap(new_count, irq_counts[i]); 540 } 541 } 542 543 /* 544 * If the hardirq time exceeds HARDIRQ_PERCENT_THRESH% of the sample_period, 545 * then the cause of softlockup might be interrupt storm. In this case, it 546 * would be useful to start interrupt counting. 547 */ 548 static bool need_counting_irqs(void) 549 { 550 u8 util; 551 int tail = __this_cpu_read(cpustat_tail); 552 553 tail = (tail + NUM_SAMPLE_PERIODS - 1) % NUM_SAMPLE_PERIODS; 554 util = __this_cpu_read(cpustat_util[tail][STATS_HARDIRQ]); 555 return util > HARDIRQ_PERCENT_THRESH; 556 } 557 558 static void start_counting_irqs(void) 559 { 560 if (!__this_cpu_read(snapshot_taken)) { 561 kstat_snapshot_irqs(); 562 __this_cpu_write(snapshot_taken, true); 563 } 564 } 565 566 static void stop_counting_irqs(void) 567 { 568 __this_cpu_write(snapshot_taken, false); 569 } 570 571 static void print_irq_counts(void) 572 { 573 unsigned int i, count; 574 struct irq_counts irq_counts_sorted[NUM_HARDIRQ_REPORT] = { 575 {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0} 576 }; 577 578 if (__this_cpu_read(snapshot_taken)) { 579 for_each_active_irq(i) { 580 count = kstat_get_irq_since_snapshot(i); 581 tabulate_irq_count(irq_counts_sorted, i, count, NUM_HARDIRQ_REPORT); 582 } 583 584 /* 585 * Outputting the "watchdog" prefix on every line is redundant and not 586 * concise, and the original alarm information is sufficient for 587 * positioning in logs, hence here printk() is used instead of pr_crit(). 588 */ 589 printk(KERN_CRIT "CPU#%d Detect HardIRQ Time exceeds %d%%. Most frequent HardIRQs:\n", 590 smp_processor_id(), HARDIRQ_PERCENT_THRESH); 591 592 for (i = 0; i < NUM_HARDIRQ_REPORT; i++) { 593 if (irq_counts_sorted[i].irq == -1) 594 break; 595 596 printk(KERN_CRIT "\t#%u: %-10u\tirq#%d\n", 597 i + 1, irq_counts_sorted[i].counts, 598 irq_counts_sorted[i].irq); 599 } 600 601 /* 602 * If the hardirq time is less than HARDIRQ_PERCENT_THRESH% in the last 603 * sample_period, then we suspect the interrupt storm might be subsiding. 604 */ 605 if (!need_counting_irqs()) 606 stop_counting_irqs(); 607 } 608 } 609 610 static void report_cpu_status(void) 611 { 612 print_cpustat(); 613 print_irq_counts(); 614 } 615 #else 616 static inline void update_cpustat(void) { } 617 static inline void report_cpu_status(void) { } 618 static inline bool need_counting_irqs(void) { return false; } 619 static inline void start_counting_irqs(void) { } 620 static inline void stop_counting_irqs(void) { } 621 #endif 622 623 /* 624 * Hard-lockup warnings should be triggered after just a few seconds. Soft- 625 * lockups can have false positives under extreme conditions. So we generally 626 * want a higher threshold for soft lockups than for hard lockups. So we couple 627 * the thresholds with a factor: we make the soft threshold twice the amount of 628 * time the hard threshold is. 629 */ 630 static int get_softlockup_thresh(void) 631 { 632 return watchdog_thresh * 2; 633 } 634 635 /* 636 * Returns seconds, approximately. We don't need nanosecond 637 * resolution, and we don't need to waste time with a big divide when 638 * 2^30ns == 1.074s. 639 */ 640 static unsigned long get_timestamp(void) 641 { 642 return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ 643 } 644 645 static void set_sample_period(void) 646 { 647 /* 648 * convert watchdog_thresh from seconds to ns 649 * the divide by 5 is to give hrtimer several chances (two 650 * or three with the current relation between the soft 651 * and hard thresholds) to increment before the 652 * hardlockup detector generates a warning 653 */ 654 sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / NUM_SAMPLE_PERIODS); 655 watchdog_update_hrtimer_threshold(sample_period); 656 } 657 658 static void update_report_ts(void) 659 { 660 __this_cpu_write(watchdog_report_ts, get_timestamp()); 661 } 662 663 /* Commands for resetting the watchdog */ 664 static void update_touch_ts(void) 665 { 666 __this_cpu_write(watchdog_touch_ts, get_timestamp()); 667 update_report_ts(); 668 } 669 670 /** 671 * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls 672 * 673 * Call when the scheduler may have stalled for legitimate reasons 674 * preventing the watchdog task from executing - e.g. the scheduler 675 * entering idle state. This should only be used for scheduler events. 676 * Use touch_softlockup_watchdog() for everything else. 677 */ 678 notrace void touch_softlockup_watchdog_sched(void) 679 { 680 /* 681 * Preemption can be enabled. It doesn't matter which CPU's watchdog 682 * report period gets restarted here, so use the raw_ operation. 683 */ 684 raw_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT); 685 } 686 687 notrace void touch_softlockup_watchdog(void) 688 { 689 touch_softlockup_watchdog_sched(); 690 wq_watchdog_touch(raw_smp_processor_id()); 691 } 692 EXPORT_SYMBOL(touch_softlockup_watchdog); 693 694 void touch_all_softlockup_watchdogs(void) 695 { 696 int cpu; 697 698 /* 699 * watchdog_mutex cannpt be taken here, as this might be called 700 * from (soft)interrupt context, so the access to 701 * watchdog_allowed_cpumask might race with a concurrent update. 702 * 703 * The watchdog time stamp can race against a concurrent real 704 * update as well, the only side effect might be a cycle delay for 705 * the softlockup check. 706 */ 707 for_each_cpu(cpu, &watchdog_allowed_mask) { 708 per_cpu(watchdog_report_ts, cpu) = SOFTLOCKUP_DELAY_REPORT; 709 wq_watchdog_touch(cpu); 710 } 711 } 712 713 void touch_softlockup_watchdog_sync(void) 714 { 715 __this_cpu_write(softlockup_touch_sync, true); 716 __this_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT); 717 } 718 719 static int is_softlockup(unsigned long touch_ts, 720 unsigned long period_ts, 721 unsigned long now) 722 { 723 if ((watchdog_enabled & WATCHDOG_SOFTOCKUP_ENABLED) && watchdog_thresh) { 724 /* 725 * If period_ts has not been updated during a sample_period, then 726 * in the subsequent few sample_periods, period_ts might also not 727 * be updated, which could indicate a potential softlockup. In 728 * this case, if we suspect the cause of the potential softlockup 729 * might be interrupt storm, then we need to count the interrupts 730 * to find which interrupt is storming. 731 */ 732 if (time_after_eq(now, period_ts + get_softlockup_thresh() / NUM_SAMPLE_PERIODS) && 733 need_counting_irqs()) 734 start_counting_irqs(); 735 736 /* 737 * A poorly behaving BPF scheduler can live-lock the system into 738 * soft lockups. Tell sched_ext to try ejecting the BPF 739 * scheduler when close to a soft lockup. 740 */ 741 if (time_after_eq(now, period_ts + get_softlockup_thresh() * 3 / 4)) 742 scx_softlockup(now - touch_ts); 743 744 /* Warn about unreasonable delays. */ 745 if (time_after(now, period_ts + get_softlockup_thresh())) 746 return now - touch_ts; 747 } 748 return 0; 749 } 750 751 /* watchdog detector functions */ 752 static DEFINE_PER_CPU(struct completion, softlockup_completion); 753 static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work); 754 755 /* 756 * The watchdog feed function - touches the timestamp. 757 * 758 * It only runs once every sample_period seconds (4 seconds by 759 * default) to reset the softlockup timestamp. If this gets delayed 760 * for more than 2*watchdog_thresh seconds then the debug-printout 761 * triggers in watchdog_timer_fn(). 762 */ 763 static int softlockup_fn(void *data) 764 { 765 update_touch_ts(); 766 stop_counting_irqs(); 767 complete(this_cpu_ptr(&softlockup_completion)); 768 769 return 0; 770 } 771 772 /* watchdog kicker functions */ 773 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) 774 { 775 unsigned long touch_ts, period_ts, now; 776 struct pt_regs *regs = get_irq_regs(); 777 int softlockup_all_cpu_backtrace; 778 int duration, thresh_count; 779 unsigned long flags; 780 781 if (!watchdog_enabled) 782 return HRTIMER_NORESTART; 783 784 /* 785 * pass the buddy check if a panic is in process 786 */ 787 if (panic_in_progress()) 788 return HRTIMER_NORESTART; 789 790 softlockup_all_cpu_backtrace = (softlockup_si_mask & SYS_INFO_ALL_BT) ? 791 1 : sysctl_softlockup_all_cpu_backtrace; 792 793 watchdog_hardlockup_kick(); 794 795 /* kick the softlockup detector */ 796 if (completion_done(this_cpu_ptr(&softlockup_completion))) { 797 reinit_completion(this_cpu_ptr(&softlockup_completion)); 798 stop_one_cpu_nowait(smp_processor_id(), 799 softlockup_fn, NULL, 800 this_cpu_ptr(&softlockup_stop_work)); 801 } 802 803 /* .. and repeat */ 804 hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); 805 806 /* 807 * Read the current timestamp first. It might become invalid anytime 808 * when a virtual machine is stopped by the host or when the watchog 809 * is touched from NMI. 810 */ 811 now = get_timestamp(); 812 /* 813 * If a virtual machine is stopped by the host it can look to 814 * the watchdog like a soft lockup. This function touches the watchdog. 815 */ 816 kvm_check_and_clear_guest_paused(); 817 /* 818 * The stored timestamp is comparable with @now only when not touched. 819 * It might get touched anytime from NMI. Make sure that is_softlockup() 820 * uses the same (valid) value. 821 */ 822 period_ts = READ_ONCE(*this_cpu_ptr(&watchdog_report_ts)); 823 824 update_cpustat(); 825 826 /* Reset the interval when touched by known problematic code. */ 827 if (period_ts == SOFTLOCKUP_DELAY_REPORT) { 828 if (unlikely(__this_cpu_read(softlockup_touch_sync))) { 829 /* 830 * If the time stamp was touched atomically 831 * make sure the scheduler tick is up to date. 832 */ 833 __this_cpu_write(softlockup_touch_sync, false); 834 sched_clock_tick(); 835 } 836 837 update_report_ts(); 838 return HRTIMER_RESTART; 839 } 840 841 /* Check for a softlockup. */ 842 touch_ts = __this_cpu_read(watchdog_touch_ts); 843 duration = is_softlockup(touch_ts, period_ts, now); 844 if (unlikely(duration)) { 845 #ifdef CONFIG_SYSFS 846 ++softlockup_count; 847 #endif 848 849 /* 850 * Prevent multiple soft-lockup reports if one cpu is already 851 * engaged in dumping all cpu back traces. 852 */ 853 if (softlockup_all_cpu_backtrace) { 854 if (test_and_set_bit_lock(0, &soft_lockup_nmi_warn)) 855 return HRTIMER_RESTART; 856 } 857 858 /* Start period for the next softlockup warning. */ 859 update_report_ts(); 860 861 printk_cpu_sync_get_irqsave(flags); 862 pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", 863 smp_processor_id(), duration, 864 current->comm, task_pid_nr(current)); 865 report_cpu_status(); 866 print_modules(); 867 print_irqtrace_events(current); 868 if (regs) 869 show_regs(regs); 870 else 871 dump_stack(); 872 printk_cpu_sync_put_irqrestore(flags); 873 874 if (softlockup_all_cpu_backtrace) { 875 trigger_allbutcpu_cpu_backtrace(smp_processor_id()); 876 if (!softlockup_panic) 877 clear_bit_unlock(0, &soft_lockup_nmi_warn); 878 } 879 880 add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); 881 sys_info(softlockup_si_mask & ~SYS_INFO_ALL_BT); 882 thresh_count = duration / get_softlockup_thresh(); 883 884 if (softlockup_panic && thresh_count >= softlockup_panic) 885 panic("softlockup: hung tasks"); 886 } 887 888 return HRTIMER_RESTART; 889 } 890 891 static void watchdog_enable(unsigned int cpu) 892 { 893 struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); 894 struct completion *done = this_cpu_ptr(&softlockup_completion); 895 896 WARN_ON_ONCE(cpu != smp_processor_id()); 897 898 init_completion(done); 899 complete(done); 900 901 /* 902 * Start the timer first to prevent the hardlockup watchdog triggering 903 * before the timer has a chance to fire. 904 */ 905 hrtimer_setup(hrtimer, watchdog_timer_fn, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); 906 hrtimer_start(hrtimer, ns_to_ktime(sample_period), 907 HRTIMER_MODE_REL_PINNED_HARD); 908 909 /* Initialize timestamp */ 910 update_touch_ts(); 911 /* Enable the hardlockup detector */ 912 if (watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED) 913 watchdog_hardlockup_enable(cpu); 914 } 915 916 static void watchdog_disable(unsigned int cpu) 917 { 918 struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); 919 920 WARN_ON_ONCE(cpu != smp_processor_id()); 921 922 /* 923 * Disable the hardlockup detector first. That prevents that a large 924 * delay between disabling the timer and disabling the hardlockup 925 * detector causes a false positive. 926 */ 927 watchdog_hardlockup_disable(cpu); 928 hrtimer_cancel(hrtimer); 929 wait_for_completion(this_cpu_ptr(&softlockup_completion)); 930 } 931 932 static int softlockup_stop_fn(void *data) 933 { 934 watchdog_disable(smp_processor_id()); 935 return 0; 936 } 937 938 static void softlockup_stop_all(void) 939 { 940 int cpu; 941 942 if (!softlockup_initialized) 943 return; 944 945 for_each_cpu(cpu, &watchdog_allowed_mask) 946 smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false); 947 948 cpumask_clear(&watchdog_allowed_mask); 949 } 950 951 static int softlockup_start_fn(void *data) 952 { 953 watchdog_enable(smp_processor_id()); 954 return 0; 955 } 956 957 static void softlockup_start_all(void) 958 { 959 int cpu; 960 961 cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask); 962 for_each_cpu(cpu, &watchdog_allowed_mask) 963 smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false); 964 } 965 966 int lockup_detector_online_cpu(unsigned int cpu) 967 { 968 if (cpumask_test_cpu(cpu, &watchdog_allowed_mask)) 969 watchdog_enable(cpu); 970 return 0; 971 } 972 973 int lockup_detector_offline_cpu(unsigned int cpu) 974 { 975 if (cpumask_test_cpu(cpu, &watchdog_allowed_mask)) 976 watchdog_disable(cpu); 977 return 0; 978 } 979 980 static void __lockup_detector_reconfigure(bool thresh_changed) 981 { 982 cpus_read_lock(); 983 watchdog_hardlockup_stop(); 984 985 softlockup_stop_all(); 986 /* 987 * To prevent watchdog_timer_fn from using the old interval and 988 * the new watchdog_thresh at the same time, which could lead to 989 * false softlockup reports, it is necessary to update the 990 * watchdog_thresh after the softlockup is completed. 991 */ 992 if (thresh_changed) 993 watchdog_thresh = READ_ONCE(watchdog_thresh_next); 994 set_sample_period(); 995 lockup_detector_update_enable(); 996 if (watchdog_enabled && watchdog_thresh) 997 softlockup_start_all(); 998 999 watchdog_hardlockup_start(); 1000 cpus_read_unlock(); 1001 } 1002 1003 void lockup_detector_reconfigure(void) 1004 { 1005 mutex_lock(&watchdog_mutex); 1006 __lockup_detector_reconfigure(false); 1007 mutex_unlock(&watchdog_mutex); 1008 } 1009 1010 /* 1011 * Create the watchdog infrastructure and configure the detector(s). 1012 */ 1013 static __init void lockup_detector_setup(void) 1014 { 1015 /* 1016 * If sysctl is off and watchdog got disabled on the command line, 1017 * nothing to do here. 1018 */ 1019 lockup_detector_update_enable(); 1020 1021 if (!IS_ENABLED(CONFIG_SYSCTL) && 1022 !(watchdog_enabled && watchdog_thresh)) 1023 return; 1024 1025 mutex_lock(&watchdog_mutex); 1026 __lockup_detector_reconfigure(false); 1027 softlockup_initialized = true; 1028 mutex_unlock(&watchdog_mutex); 1029 } 1030 1031 #else /* CONFIG_SOFTLOCKUP_DETECTOR */ 1032 static void __lockup_detector_reconfigure(bool thresh_changed) 1033 { 1034 cpus_read_lock(); 1035 watchdog_hardlockup_stop(); 1036 if (thresh_changed) 1037 watchdog_thresh = READ_ONCE(watchdog_thresh_next); 1038 lockup_detector_update_enable(); 1039 watchdog_hardlockup_start(); 1040 cpus_read_unlock(); 1041 } 1042 void lockup_detector_reconfigure(void) 1043 { 1044 __lockup_detector_reconfigure(false); 1045 } 1046 static inline void lockup_detector_setup(void) 1047 { 1048 __lockup_detector_reconfigure(false); 1049 } 1050 #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ 1051 1052 /** 1053 * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) 1054 * 1055 * Special interface for parisc. It prevents lockup detector warnings from 1056 * the default pm_poweroff() function which busy loops forever. 1057 */ 1058 void lockup_detector_soft_poweroff(void) 1059 { 1060 watchdog_enabled = 0; 1061 } 1062 1063 #ifdef CONFIG_SYSCTL 1064 1065 /* Propagate any changes to the watchdog infrastructure */ 1066 static void proc_watchdog_update(bool thresh_changed) 1067 { 1068 /* Remove impossible cpus to keep sysctl output clean. */ 1069 cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); 1070 __lockup_detector_reconfigure(thresh_changed); 1071 } 1072 1073 /* 1074 * common function for watchdog, nmi_watchdog and soft_watchdog parameter 1075 * 1076 * caller | table->data points to | 'which' 1077 * -------------------|----------------------------------|------------------------------- 1078 * proc_watchdog | watchdog_user_enabled | WATCHDOG_HARDLOCKUP_ENABLED | 1079 * | | WATCHDOG_SOFTOCKUP_ENABLED 1080 * -------------------|----------------------------------|------------------------------- 1081 * proc_nmi_watchdog | watchdog_hardlockup_user_enabled | WATCHDOG_HARDLOCKUP_ENABLED 1082 * -------------------|----------------------------------|------------------------------- 1083 * proc_soft_watchdog | watchdog_softlockup_user_enabled | WATCHDOG_SOFTOCKUP_ENABLED 1084 */ 1085 static int proc_watchdog_common(int which, const struct ctl_table *table, int write, 1086 void *buffer, size_t *lenp, loff_t *ppos) 1087 { 1088 int err, old, *param = table->data; 1089 1090 mutex_lock(&watchdog_mutex); 1091 1092 old = *param; 1093 if (!write) { 1094 /* 1095 * On read synchronize the userspace interface. This is a 1096 * racy snapshot. 1097 */ 1098 *param = (watchdog_enabled & which) != 0; 1099 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 1100 *param = old; 1101 } else { 1102 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 1103 if (!err && old != READ_ONCE(*param)) 1104 proc_watchdog_update(false); 1105 } 1106 mutex_unlock(&watchdog_mutex); 1107 return err; 1108 } 1109 1110 /* 1111 * /proc/sys/kernel/watchdog 1112 */ 1113 static int proc_watchdog(const struct ctl_table *table, int write, 1114 void *buffer, size_t *lenp, loff_t *ppos) 1115 { 1116 return proc_watchdog_common(WATCHDOG_HARDLOCKUP_ENABLED | 1117 WATCHDOG_SOFTOCKUP_ENABLED, 1118 table, write, buffer, lenp, ppos); 1119 } 1120 1121 /* 1122 * /proc/sys/kernel/nmi_watchdog 1123 */ 1124 static int proc_nmi_watchdog(const struct ctl_table *table, int write, 1125 void *buffer, size_t *lenp, loff_t *ppos) 1126 { 1127 if (!watchdog_hardlockup_available && write) 1128 return -ENOTSUPP; 1129 return proc_watchdog_common(WATCHDOG_HARDLOCKUP_ENABLED, 1130 table, write, buffer, lenp, ppos); 1131 } 1132 1133 #ifdef CONFIG_SOFTLOCKUP_DETECTOR 1134 /* 1135 * /proc/sys/kernel/soft_watchdog 1136 */ 1137 static int proc_soft_watchdog(const struct ctl_table *table, int write, 1138 void *buffer, size_t *lenp, loff_t *ppos) 1139 { 1140 return proc_watchdog_common(WATCHDOG_SOFTOCKUP_ENABLED, 1141 table, write, buffer, lenp, ppos); 1142 } 1143 #endif 1144 1145 /* 1146 * /proc/sys/kernel/watchdog_thresh 1147 */ 1148 static int proc_watchdog_thresh(const struct ctl_table *table, int write, 1149 void *buffer, size_t *lenp, loff_t *ppos) 1150 { 1151 int err, old; 1152 1153 mutex_lock(&watchdog_mutex); 1154 1155 watchdog_thresh_next = READ_ONCE(watchdog_thresh); 1156 1157 old = watchdog_thresh_next; 1158 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 1159 1160 if (!err && write && old != READ_ONCE(watchdog_thresh_next)) 1161 proc_watchdog_update(true); 1162 1163 mutex_unlock(&watchdog_mutex); 1164 return err; 1165 } 1166 1167 /* 1168 * The cpumask is the mask of possible cpus that the watchdog can run 1169 * on, not the mask of cpus it is actually running on. This allows the 1170 * user to specify a mask that will include cpus that have not yet 1171 * been brought online, if desired. 1172 */ 1173 static int proc_watchdog_cpumask(const struct ctl_table *table, int write, 1174 void *buffer, size_t *lenp, loff_t *ppos) 1175 { 1176 int err; 1177 1178 mutex_lock(&watchdog_mutex); 1179 1180 err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); 1181 if (!err && write) 1182 proc_watchdog_update(false); 1183 1184 mutex_unlock(&watchdog_mutex); 1185 return err; 1186 } 1187 1188 static const int sixty = 60; 1189 1190 static const struct ctl_table watchdog_sysctls[] = { 1191 { 1192 .procname = "watchdog", 1193 .data = &watchdog_user_enabled, 1194 .maxlen = sizeof(int), 1195 .mode = 0644, 1196 .proc_handler = proc_watchdog, 1197 .extra1 = SYSCTL_ZERO, 1198 .extra2 = SYSCTL_ONE, 1199 }, 1200 { 1201 .procname = "watchdog_thresh", 1202 .data = &watchdog_thresh_next, 1203 .maxlen = sizeof(int), 1204 .mode = 0644, 1205 .proc_handler = proc_watchdog_thresh, 1206 .extra1 = SYSCTL_ZERO, 1207 .extra2 = (void *)&sixty, 1208 }, 1209 { 1210 .procname = "watchdog_cpumask", 1211 .data = &watchdog_cpumask_bits, 1212 .maxlen = NR_CPUS, 1213 .mode = 0644, 1214 .proc_handler = proc_watchdog_cpumask, 1215 }, 1216 #ifdef CONFIG_SOFTLOCKUP_DETECTOR 1217 { 1218 .procname = "soft_watchdog", 1219 .data = &watchdog_softlockup_user_enabled, 1220 .maxlen = sizeof(int), 1221 .mode = 0644, 1222 .proc_handler = proc_soft_watchdog, 1223 .extra1 = SYSCTL_ZERO, 1224 .extra2 = SYSCTL_ONE, 1225 }, 1226 { 1227 .procname = "softlockup_panic", 1228 .data = &softlockup_panic, 1229 .maxlen = sizeof(int), 1230 .mode = 0644, 1231 .proc_handler = proc_dointvec_minmax, 1232 .extra1 = SYSCTL_ZERO, 1233 .extra2 = SYSCTL_INT_MAX, 1234 }, 1235 { 1236 .procname = "softlockup_sys_info", 1237 .data = &softlockup_si_mask, 1238 .maxlen = sizeof(softlockup_si_mask), 1239 .mode = 0644, 1240 .proc_handler = sysctl_sys_info_handler, 1241 }, 1242 #ifdef CONFIG_SMP 1243 { 1244 .procname = "softlockup_all_cpu_backtrace", 1245 .data = &sysctl_softlockup_all_cpu_backtrace, 1246 .maxlen = sizeof(int), 1247 .mode = 0644, 1248 .proc_handler = proc_dointvec_minmax, 1249 .extra1 = SYSCTL_ZERO, 1250 .extra2 = SYSCTL_ONE, 1251 }, 1252 #endif /* CONFIG_SMP */ 1253 #endif 1254 #ifdef CONFIG_HARDLOCKUP_DETECTOR 1255 { 1256 .procname = "hardlockup_panic", 1257 .data = &hardlockup_panic, 1258 .maxlen = sizeof(int), 1259 .mode = 0644, 1260 .proc_handler = proc_dointvec_minmax, 1261 .extra1 = SYSCTL_ZERO, 1262 .extra2 = SYSCTL_ONE, 1263 }, 1264 { 1265 .procname = "hardlockup_sys_info", 1266 .data = &hardlockup_si_mask, 1267 .maxlen = sizeof(hardlockup_si_mask), 1268 .mode = 0644, 1269 .proc_handler = sysctl_sys_info_handler, 1270 }, 1271 #ifdef CONFIG_SMP 1272 { 1273 .procname = "hardlockup_all_cpu_backtrace", 1274 .data = &sysctl_hardlockup_all_cpu_backtrace, 1275 .maxlen = sizeof(int), 1276 .mode = 0644, 1277 .proc_handler = proc_dointvec_minmax, 1278 .extra1 = SYSCTL_ZERO, 1279 .extra2 = SYSCTL_ONE, 1280 }, 1281 #endif /* CONFIG_SMP */ 1282 #endif 1283 { 1284 .procname = "nmi_watchdog", 1285 .data = &watchdog_hardlockup_user_enabled, 1286 .maxlen = sizeof(int), 1287 .mode = 0644, 1288 .proc_handler = proc_nmi_watchdog, 1289 .extra1 = SYSCTL_ZERO, 1290 .extra2 = SYSCTL_ONE, 1291 }, 1292 }; 1293 1294 static void __init watchdog_sysctl_init(void) 1295 { 1296 register_sysctl_init("kernel", watchdog_sysctls); 1297 } 1298 1299 #else 1300 #define watchdog_sysctl_init() do { } while (0) 1301 #endif /* CONFIG_SYSCTL */ 1302 1303 static void __init lockup_detector_delay_init(struct work_struct *work); 1304 static bool allow_lockup_detector_init_retry __initdata; 1305 1306 static struct work_struct detector_work __initdata = 1307 __WORK_INITIALIZER(detector_work, lockup_detector_delay_init); 1308 1309 static void __init lockup_detector_delay_init(struct work_struct *work) 1310 { 1311 int ret; 1312 1313 ret = watchdog_hardlockup_probe(); 1314 if (ret) { 1315 if (ret == -ENODEV) 1316 pr_info("NMI not fully supported\n"); 1317 else 1318 pr_info("Delayed init of the lockup detector failed: %d\n", ret); 1319 pr_info("Hard watchdog permanently disabled\n"); 1320 return; 1321 } 1322 1323 allow_lockup_detector_init_retry = false; 1324 1325 watchdog_hardlockup_available = true; 1326 lockup_detector_setup(); 1327 } 1328 1329 /* 1330 * lockup_detector_retry_init - retry init lockup detector if possible. 1331 * 1332 * Retry hardlockup detector init. It is useful when it requires some 1333 * functionality that has to be initialized later on a particular 1334 * platform. 1335 */ 1336 void __init lockup_detector_retry_init(void) 1337 { 1338 /* Must be called before late init calls */ 1339 if (!allow_lockup_detector_init_retry) 1340 return; 1341 1342 schedule_work(&detector_work); 1343 } 1344 1345 /* 1346 * Ensure that optional delayed hardlockup init is proceed before 1347 * the init code and memory is freed. 1348 */ 1349 static int __init lockup_detector_check(void) 1350 { 1351 /* Prevent any later retry. */ 1352 allow_lockup_detector_init_retry = false; 1353 1354 /* Make sure no work is pending. */ 1355 flush_work(&detector_work); 1356 1357 watchdog_sysctl_init(); 1358 1359 return 0; 1360 1361 } 1362 late_initcall_sync(lockup_detector_check); 1363 1364 void __init lockup_detector_init(void) 1365 { 1366 if (tick_nohz_full_enabled()) 1367 pr_info("Disabling watchdog on nohz_full cores by default\n"); 1368 1369 cpumask_copy(&watchdog_cpumask, 1370 housekeeping_cpumask(HK_TYPE_TIMER)); 1371 1372 if (!watchdog_hardlockup_probe()) 1373 watchdog_hardlockup_available = true; 1374 else 1375 allow_lockup_detector_init_retry = true; 1376 1377 lockup_detector_setup(); 1378 } 1379