Commit | Line | Data |
---|---|---|
58687acb DZ |
1 | /* |
2 | * Detect hard and soft lockups on a system | |
3 | * | |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
5 | * | |
86f5e6a7 FLVC |
6 | * Note: Most of this code is borrowed heavily from the original softlockup |
7 | * detector, so thanks to Ingo for the initial implementation. | |
8 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks | |
58687acb DZ |
9 | * to those contributors as well. |
10 | */ | |
11 | ||
4501980a AM |
12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
13 | ||
58687acb DZ |
14 | #include <linux/mm.h> |
15 | #include <linux/cpu.h> | |
16 | #include <linux/nmi.h> | |
17 | #include <linux/init.h> | |
58687acb DZ |
18 | #include <linux/module.h> |
19 | #include <linux/sysctl.h> | |
bcd951cf | 20 | #include <linux/smpboot.h> |
8bd75c77 | 21 | #include <linux/sched/rt.h> |
fe4ba3c3 | 22 | #include <linux/tick.h> |
58687acb DZ |
23 | |
24 | #include <asm/irq_regs.h> | |
5d1c0f4a | 25 | #include <linux/kvm_para.h> |
58687acb DZ |
26 | #include <linux/perf_event.h> |
27 | ||
84d56e66 UO |
28 | /* |
29 | * The run state of the lockup detectors is controlled by the content of the | |
30 | * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - | |
31 | * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. | |
32 | * | |
33 | * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' | |
34 | * are variables that are only used as an 'interface' between the parameters | |
35 | * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The | |
36 | * 'watchdog_thresh' variable is handled differently because its value is not | |
37 | * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' | |
38 | * is equal zero. | |
39 | */ | |
40 | #define NMI_WATCHDOG_ENABLED_BIT 0 | |
41 | #define SOFT_WATCHDOG_ENABLED_BIT 1 | |
42 | #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) | |
43 | #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) | |
44 | ||
ab992dc3 PZ |
45 | static DEFINE_MUTEX(watchdog_proc_mutex); |
46 | ||
84d56e66 UO |
47 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
48 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; | |
49 | #else | |
50 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; | |
51 | #endif | |
52 | int __read_mostly nmi_watchdog_enabled; | |
53 | int __read_mostly soft_watchdog_enabled; | |
54 | int __read_mostly watchdog_user_enabled; | |
4eec42f3 | 55 | int __read_mostly watchdog_thresh = 10; |
84d56e66 | 56 | |
ed235875 AT |
57 | #ifdef CONFIG_SMP |
58 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; | |
59 | #else | |
60 | #define sysctl_softlockup_all_cpu_backtrace 0 | |
61 | #endif | |
fe4ba3c3 CM |
62 | static struct cpumask watchdog_cpumask __read_mostly; |
63 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); | |
64 | ||
65 | /* Helper for online, unparked cpus. */ | |
66 | #define for_each_watchdog_cpu(cpu) \ | |
67 | for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask) | |
ed235875 | 68 | |
3c00ea82 | 69 | static int __read_mostly watchdog_running; |
0f34c400 | 70 | static u64 __read_mostly sample_period; |
58687acb DZ |
71 | |
72 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
73 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
74 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
75 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 76 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
77 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
78 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 79 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
23637d47 | 80 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
81 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
82 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
83 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
84 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
85 | #endif | |
ed235875 | 86 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 87 | |
58687acb DZ |
88 | /* boot commands */ |
89 | /* | |
90 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
91 | */ | |
23637d47 | 92 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
93 | static int hardlockup_panic = |
94 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
6e7458a6 UO |
95 | /* |
96 | * We may not want to enable hard lockup detection by default in all cases, | |
97 | * for example when running the kernel as a guest on a hypervisor. In these | |
98 | * cases this function can be called to disable hard lockup detection. This | |
99 | * function should only be executed once by the boot processor before the | |
100 | * kernel command line parameters are parsed, because otherwise it is not | |
101 | * possible to override this in hardlockup_panic_setup(). | |
102 | */ | |
692297d8 | 103 | void hardlockup_detector_disable(void) |
6e7458a6 | 104 | { |
692297d8 | 105 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
6e7458a6 UO |
106 | } |
107 | ||
58687acb DZ |
108 | static int __init hardlockup_panic_setup(char *str) |
109 | { | |
110 | if (!strncmp(str, "panic", 5)) | |
111 | hardlockup_panic = 1; | |
fef2c9bc DZ |
112 | else if (!strncmp(str, "nopanic", 7)) |
113 | hardlockup_panic = 0; | |
5dc30558 | 114 | else if (!strncmp(str, "0", 1)) |
195daf66 UO |
115 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
116 | else if (!strncmp(str, "1", 1)) | |
117 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; | |
58687acb DZ |
118 | return 1; |
119 | } | |
120 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
121 | #endif | |
122 | ||
123 | unsigned int __read_mostly softlockup_panic = | |
124 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
125 | ||
126 | static int __init softlockup_panic_setup(char *str) | |
127 | { | |
128 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
129 | ||
130 | return 1; | |
131 | } | |
132 | __setup("softlockup_panic=", softlockup_panic_setup); | |
133 | ||
134 | static int __init nowatchdog_setup(char *str) | |
135 | { | |
195daf66 | 136 | watchdog_enabled = 0; |
58687acb DZ |
137 | return 1; |
138 | } | |
139 | __setup("nowatchdog", nowatchdog_setup); | |
140 | ||
58687acb DZ |
141 | static int __init nosoftlockup_setup(char *str) |
142 | { | |
195daf66 | 143 | watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED; |
58687acb DZ |
144 | return 1; |
145 | } | |
146 | __setup("nosoftlockup", nosoftlockup_setup); | |
195daf66 | 147 | |
ed235875 AT |
148 | #ifdef CONFIG_SMP |
149 | static int __init softlockup_all_cpu_backtrace_setup(char *str) | |
150 | { | |
151 | sysctl_softlockup_all_cpu_backtrace = | |
152 | !!simple_strtol(str, NULL, 0); | |
153 | return 1; | |
154 | } | |
155 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
156 | #endif | |
58687acb | 157 | |
4eec42f3 MSB |
158 | /* |
159 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
160 | * lockups can have false positives under extreme conditions. So we generally | |
161 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
162 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
163 | * time the hard threshold is. | |
164 | */ | |
6e9101ae | 165 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
166 | { |
167 | return watchdog_thresh * 2; | |
168 | } | |
58687acb DZ |
169 | |
170 | /* | |
171 | * Returns seconds, approximately. We don't need nanosecond | |
172 | * resolution, and we don't need to waste time with a big divide when | |
173 | * 2^30ns == 1.074s. | |
174 | */ | |
c06b4f19 | 175 | static unsigned long get_timestamp(void) |
58687acb | 176 | { |
545a2bf7 | 177 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
178 | } |
179 | ||
0f34c400 | 180 | static void set_sample_period(void) |
58687acb DZ |
181 | { |
182 | /* | |
586692a5 | 183 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
184 | * the divide by 5 is to give hrtimer several chances (two |
185 | * or three with the current relation between the soft | |
186 | * and hard thresholds) to increment before the | |
187 | * hardlockup detector generates a warning | |
58687acb | 188 | */ |
0f34c400 | 189 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
190 | } |
191 | ||
192 | /* Commands for resetting the watchdog */ | |
193 | static void __touch_watchdog(void) | |
194 | { | |
c06b4f19 | 195 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
196 | } |
197 | ||
332fbdbc | 198 | void touch_softlockup_watchdog(void) |
58687acb | 199 | { |
7861144b AM |
200 | /* |
201 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
202 | * gets zeroed here, so use the raw_ operation. | |
203 | */ | |
204 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 205 | } |
0167c781 | 206 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 207 | |
332fbdbc | 208 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
209 | { |
210 | int cpu; | |
211 | ||
212 | /* | |
213 | * this is done lockless | |
214 | * do we care if a 0 races with a timestamp? | |
215 | * all it means is the softlock check starts one cycle later | |
216 | */ | |
fe4ba3c3 | 217 | for_each_watchdog_cpu(cpu) |
58687acb DZ |
218 | per_cpu(watchdog_touch_ts, cpu) = 0; |
219 | } | |
220 | ||
cafcd80d | 221 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
222 | void touch_nmi_watchdog(void) |
223 | { | |
62572e29 BZ |
224 | /* |
225 | * Using __raw here because some code paths have | |
226 | * preemption enabled. If preemption is enabled | |
227 | * then interrupts should be enabled too, in which | |
228 | * case we shouldn't have to worry about the watchdog | |
229 | * going off. | |
230 | */ | |
f7f66b05 | 231 | raw_cpu_write(watchdog_nmi_touch, true); |
332fbdbc | 232 | touch_softlockup_watchdog(); |
58687acb DZ |
233 | } |
234 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
235 | ||
cafcd80d DZ |
236 | #endif |
237 | ||
58687acb DZ |
238 | void touch_softlockup_watchdog_sync(void) |
239 | { | |
f7f66b05 CL |
240 | __this_cpu_write(softlockup_touch_sync, true); |
241 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
242 | } |
243 | ||
23637d47 | 244 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 245 | /* watchdog detector functions */ |
26e09c6e | 246 | static int is_hardlockup(void) |
58687acb | 247 | { |
909ea964 | 248 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 249 | |
909ea964 | 250 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
251 | return 1; |
252 | ||
909ea964 | 253 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
254 | return 0; |
255 | } | |
256 | #endif | |
257 | ||
26e09c6e | 258 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 259 | { |
c06b4f19 | 260 | unsigned long now = get_timestamp(); |
58687acb | 261 | |
195daf66 UO |
262 | if (watchdog_enabled & SOFT_WATCHDOG_ENABLED) { |
263 | /* Warn about unreasonable delays. */ | |
264 | if (time_after(now, touch_ts + get_softlockup_thresh())) | |
265 | return now - touch_ts; | |
266 | } | |
58687acb DZ |
267 | return 0; |
268 | } | |
269 | ||
23637d47 | 270 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 271 | |
58687acb DZ |
272 | static struct perf_event_attr wd_hw_attr = { |
273 | .type = PERF_TYPE_HARDWARE, | |
274 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
275 | .size = sizeof(struct perf_event_attr), | |
276 | .pinned = 1, | |
277 | .disabled = 1, | |
278 | }; | |
279 | ||
280 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 281 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
282 | struct perf_sample_data *data, |
283 | struct pt_regs *regs) | |
284 | { | |
c6db67cd PZ |
285 | /* Ensure the watchdog never gets throttled */ |
286 | event->hw.interrupts = 0; | |
287 | ||
909ea964 CL |
288 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
289 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
290 | return; |
291 | } | |
292 | ||
293 | /* check for a hardlockup | |
294 | * This is done by making sure our timer interrupt | |
295 | * is incrementing. The timer interrupt should have | |
296 | * fired multiple times before we overflow'd. If it hasn't | |
297 | * then this is a good indication the cpu is stuck | |
298 | */ | |
26e09c6e DZ |
299 | if (is_hardlockup()) { |
300 | int this_cpu = smp_processor_id(); | |
301 | ||
58687acb | 302 | /* only print hardlockups once */ |
909ea964 | 303 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
304 | return; |
305 | ||
306 | if (hardlockup_panic) | |
656c3b79 FF |
307 | panic("Watchdog detected hard LOCKUP on cpu %d", |
308 | this_cpu); | |
58687acb | 309 | else |
656c3b79 FF |
310 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", |
311 | this_cpu); | |
58687acb | 312 | |
909ea964 | 313 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
314 | return; |
315 | } | |
316 | ||
909ea964 | 317 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
318 | return; |
319 | } | |
bcd951cf TG |
320 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
321 | ||
58687acb DZ |
322 | static void watchdog_interrupt_count(void) |
323 | { | |
909ea964 | 324 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 325 | } |
bcd951cf TG |
326 | |
327 | static int watchdog_nmi_enable(unsigned int cpu); | |
328 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
329 | |
330 | /* watchdog kicker functions */ | |
331 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
332 | { | |
909ea964 | 333 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
334 | struct pt_regs *regs = get_irq_regs(); |
335 | int duration; | |
ed235875 | 336 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb DZ |
337 | |
338 | /* kick the hardlockup detector */ | |
339 | watchdog_interrupt_count(); | |
340 | ||
341 | /* kick the softlockup detector */ | |
909ea964 | 342 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
343 | |
344 | /* .. and repeat */ | |
0f34c400 | 345 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
346 | |
347 | if (touch_ts == 0) { | |
909ea964 | 348 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
349 | /* |
350 | * If the time stamp was touched atomically | |
351 | * make sure the scheduler tick is up to date. | |
352 | */ | |
909ea964 | 353 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
354 | sched_clock_tick(); |
355 | } | |
5d1c0f4a EM |
356 | |
357 | /* Clear the guest paused flag on watchdog reset */ | |
358 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
359 | __touch_watchdog(); |
360 | return HRTIMER_RESTART; | |
361 | } | |
362 | ||
363 | /* check for a softlockup | |
364 | * This is done by making sure a high priority task is | |
365 | * being scheduled. The task touches the watchdog to | |
366 | * indicate it is getting cpu time. If it hasn't then | |
367 | * this is a good indication some task is hogging the cpu | |
368 | */ | |
26e09c6e | 369 | duration = is_softlockup(touch_ts); |
58687acb | 370 | if (unlikely(duration)) { |
5d1c0f4a EM |
371 | /* |
372 | * If a virtual machine is stopped by the host it can look to | |
373 | * the watchdog like a soft lockup, check to see if the host | |
374 | * stopped the vm before we issue the warning | |
375 | */ | |
376 | if (kvm_check_and_clear_guest_paused()) | |
377 | return HRTIMER_RESTART; | |
378 | ||
58687acb | 379 | /* only warn once */ |
b1a8de1f | 380 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
381 | /* | |
382 | * When multiple processes are causing softlockups the | |
383 | * softlockup detector only warns on the first one | |
384 | * because the code relies on a full quiet cycle to | |
385 | * re-arm. The second process prevents the quiet cycle | |
386 | * and never gets reported. Use task pointers to detect | |
387 | * this. | |
388 | */ | |
389 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
390 | current) { | |
391 | __this_cpu_write(soft_watchdog_warn, false); | |
392 | __touch_watchdog(); | |
393 | } | |
58687acb | 394 | return HRTIMER_RESTART; |
b1a8de1f | 395 | } |
58687acb | 396 | |
ed235875 AT |
397 | if (softlockup_all_cpu_backtrace) { |
398 | /* Prevent multiple soft-lockup reports if one cpu is already | |
399 | * engaged in dumping cpu back traces | |
400 | */ | |
401 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
402 | /* Someone else will report us. Let's give up */ | |
403 | __this_cpu_write(soft_watchdog_warn, true); | |
404 | return HRTIMER_RESTART; | |
405 | } | |
406 | } | |
407 | ||
656c3b79 | 408 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 409 | smp_processor_id(), duration, |
58687acb | 410 | current->comm, task_pid_nr(current)); |
b1a8de1f | 411 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
412 | print_modules(); |
413 | print_irqtrace_events(current); | |
414 | if (regs) | |
415 | show_regs(regs); | |
416 | else | |
417 | dump_stack(); | |
418 | ||
ed235875 AT |
419 | if (softlockup_all_cpu_backtrace) { |
420 | /* Avoid generating two back traces for current | |
421 | * given that one is already made above | |
422 | */ | |
423 | trigger_allbutself_cpu_backtrace(); | |
424 | ||
425 | clear_bit(0, &soft_lockup_nmi_warn); | |
426 | /* Barrier to sync with other cpus */ | |
427 | smp_mb__after_atomic(); | |
428 | } | |
429 | ||
69361eef | 430 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
431 | if (softlockup_panic) |
432 | panic("softlockup: hung tasks"); | |
909ea964 | 433 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 434 | } else |
909ea964 | 435 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
436 | |
437 | return HRTIMER_RESTART; | |
438 | } | |
439 | ||
bcd951cf TG |
440 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
441 | { | |
442 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 443 | |
bcd951cf TG |
444 | sched_setscheduler(current, policy, ¶m); |
445 | } | |
446 | ||
447 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 448 | { |
f7f66b05 | 449 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 450 | |
3935e895 BM |
451 | /* kick off the timer for the hardlockup detector */ |
452 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
453 | hrtimer->function = watchdog_timer_fn; | |
454 | ||
bcd951cf TG |
455 | /* Enable the perf event */ |
456 | watchdog_nmi_enable(cpu); | |
58687acb | 457 | |
58687acb | 458 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 459 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
460 | HRTIMER_MODE_REL_PINNED); |
461 | ||
bcd951cf TG |
462 | /* initialize timestamp */ |
463 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
464 | __touch_watchdog(); | |
465 | } | |
58687acb | 466 | |
bcd951cf TG |
467 | static void watchdog_disable(unsigned int cpu) |
468 | { | |
f7f66b05 | 469 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 470 | |
bcd951cf TG |
471 | watchdog_set_prio(SCHED_NORMAL, 0); |
472 | hrtimer_cancel(hrtimer); | |
473 | /* disable the perf event */ | |
474 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
475 | } |
476 | ||
b8900bc0 FW |
477 | static void watchdog_cleanup(unsigned int cpu, bool online) |
478 | { | |
479 | watchdog_disable(cpu); | |
480 | } | |
481 | ||
bcd951cf TG |
482 | static int watchdog_should_run(unsigned int cpu) |
483 | { | |
484 | return __this_cpu_read(hrtimer_interrupts) != | |
485 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
486 | } | |
487 | ||
488 | /* | |
489 | * The watchdog thread function - touches the timestamp. | |
490 | * | |
0f34c400 | 491 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
492 | * default) to reset the softlockup timestamp. If this gets delayed |
493 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
494 | * triggers in watchdog_timer_fn(). | |
495 | */ | |
496 | static void watchdog(unsigned int cpu) | |
497 | { | |
498 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
499 | __this_cpu_read(hrtimer_interrupts)); | |
500 | __touch_watchdog(); | |
bcfba4f4 UO |
501 | |
502 | /* | |
503 | * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the | |
504 | * failure path. Check for failures that can occur asynchronously - | |
505 | * for example, when CPUs are on-lined - and shut down the hardware | |
506 | * perf event on each CPU accordingly. | |
507 | * | |
508 | * The only non-obvious place this bit can be cleared is through | |
509 | * watchdog_nmi_enable(), so a pr_info() is placed there. Placing a | |
510 | * pr_info here would be too noisy as it would result in a message | |
511 | * every few seconds if the hardlockup was disabled but the softlockup | |
512 | * enabled. | |
513 | */ | |
514 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
515 | watchdog_nmi_disable(cpu); | |
bcd951cf | 516 | } |
58687acb | 517 | |
23637d47 | 518 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
519 | /* |
520 | * People like the simple clean cpu node info on boot. | |
521 | * Reduce the watchdog noise by only printing messages | |
522 | * that are different from what cpu0 displayed. | |
523 | */ | |
524 | static unsigned long cpu0_err; | |
525 | ||
bcd951cf | 526 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
527 | { |
528 | struct perf_event_attr *wd_attr; | |
529 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
530 | ||
195daf66 UO |
531 | /* nothing to do if the hard lockup detector is disabled */ |
532 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
533 | goto out; | |
6e7458a6 | 534 | |
58687acb DZ |
535 | /* is it already setup and enabled? */ |
536 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
537 | goto out; | |
538 | ||
539 | /* it is setup but not enabled */ | |
540 | if (event != NULL) | |
541 | goto out_enable; | |
542 | ||
58687acb | 543 | wd_attr = &wd_hw_attr; |
4eec42f3 | 544 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
545 | |
546 | /* Try to register using hardware perf events */ | |
4dc0da86 | 547 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
548 | |
549 | /* save cpu0 error for future comparision */ | |
550 | if (cpu == 0 && IS_ERR(event)) | |
551 | cpu0_err = PTR_ERR(event); | |
552 | ||
58687acb | 553 | if (!IS_ERR(event)) { |
a7027046 DZ |
554 | /* only print for cpu0 or different than cpu0 */ |
555 | if (cpu == 0 || cpu0_err) | |
556 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
557 | goto out_save; |
558 | } | |
559 | ||
bcfba4f4 UO |
560 | /* |
561 | * Disable the hard lockup detector if _any_ CPU fails to set up | |
562 | * set up the hardware perf event. The watchdog() function checks | |
563 | * the NMI_WATCHDOG_ENABLED bit periodically. | |
564 | * | |
565 | * The barriers are for syncing up watchdog_enabled across all the | |
566 | * cpus, as clear_bit() does not use barriers. | |
567 | */ | |
568 | smp_mb__before_atomic(); | |
569 | clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); | |
570 | smp_mb__after_atomic(); | |
571 | ||
a7027046 DZ |
572 | /* skip displaying the same error again */ |
573 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
574 | return PTR_ERR(event); | |
5651f7f4 DZ |
575 | |
576 | /* vary the KERN level based on the returned errno */ | |
577 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 578 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 579 | else if (PTR_ERR(event) == -ENOENT) |
656c3b79 | 580 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
4501980a | 581 | cpu); |
5651f7f4 | 582 | else |
4501980a AM |
583 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
584 | cpu, PTR_ERR(event)); | |
bcfba4f4 UO |
585 | |
586 | pr_info("Shutting down hard lockup detector on all cpus\n"); | |
587 | ||
eac24335 | 588 | return PTR_ERR(event); |
58687acb DZ |
589 | |
590 | /* success path */ | |
591 | out_save: | |
592 | per_cpu(watchdog_ev, cpu) = event; | |
593 | out_enable: | |
594 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
595 | out: | |
596 | return 0; | |
597 | } | |
598 | ||
bcd951cf | 599 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
600 | { |
601 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
602 | ||
603 | if (event) { | |
604 | perf_event_disable(event); | |
605 | per_cpu(watchdog_ev, cpu) = NULL; | |
606 | ||
607 | /* should be in cleanup, but blocks oprofile */ | |
608 | perf_event_release_kernel(event); | |
609 | } | |
df577149 UO |
610 | if (cpu == 0) { |
611 | /* watchdog_nmi_enable() expects this to be zero initially. */ | |
612 | cpu0_err = 0; | |
613 | } | |
58687acb | 614 | } |
b3738d29 SE |
615 | |
616 | void watchdog_nmi_enable_all(void) | |
617 | { | |
618 | int cpu; | |
619 | ||
ab992dc3 PZ |
620 | mutex_lock(&watchdog_proc_mutex); |
621 | ||
622 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
623 | goto unlock; | |
b3738d29 SE |
624 | |
625 | get_online_cpus(); | |
fe4ba3c3 | 626 | for_each_watchdog_cpu(cpu) |
b3738d29 SE |
627 | watchdog_nmi_enable(cpu); |
628 | put_online_cpus(); | |
ab992dc3 PZ |
629 | |
630 | unlock: | |
1173ff09 | 631 | mutex_unlock(&watchdog_proc_mutex); |
b3738d29 SE |
632 | } |
633 | ||
634 | void watchdog_nmi_disable_all(void) | |
635 | { | |
636 | int cpu; | |
637 | ||
ab992dc3 PZ |
638 | mutex_lock(&watchdog_proc_mutex); |
639 | ||
b3738d29 | 640 | if (!watchdog_running) |
ab992dc3 | 641 | goto unlock; |
b3738d29 SE |
642 | |
643 | get_online_cpus(); | |
fe4ba3c3 | 644 | for_each_watchdog_cpu(cpu) |
b3738d29 SE |
645 | watchdog_nmi_disable(cpu); |
646 | put_online_cpus(); | |
ab992dc3 PZ |
647 | |
648 | unlock: | |
649 | mutex_unlock(&watchdog_proc_mutex); | |
b3738d29 | 650 | } |
58687acb | 651 | #else |
bcd951cf TG |
652 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
653 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
b3738d29 SE |
654 | void watchdog_nmi_enable_all(void) {} |
655 | void watchdog_nmi_disable_all(void) {} | |
23637d47 | 656 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 657 | |
b8900bc0 FW |
658 | static struct smp_hotplug_thread watchdog_threads = { |
659 | .store = &softlockup_watchdog, | |
660 | .thread_should_run = watchdog_should_run, | |
661 | .thread_fn = watchdog, | |
662 | .thread_comm = "watchdog/%u", | |
663 | .setup = watchdog_enable, | |
664 | .cleanup = watchdog_cleanup, | |
665 | .park = watchdog_disable, | |
666 | .unpark = watchdog_enable, | |
667 | }; | |
668 | ||
9809b18f MH |
669 | static void restart_watchdog_hrtimer(void *info) |
670 | { | |
f7f66b05 | 671 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
9809b18f MH |
672 | int ret; |
673 | ||
674 | /* | |
675 | * No need to cancel and restart hrtimer if it is currently executing | |
676 | * because it will reprogram itself with the new period now. | |
677 | * We should never see it unqueued here because we are running per-cpu | |
678 | * with interrupts disabled. | |
679 | */ | |
680 | ret = hrtimer_try_to_cancel(hrtimer); | |
681 | if (ret == 1) | |
682 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), | |
683 | HRTIMER_MODE_REL_PINNED); | |
684 | } | |
685 | ||
b2f57c3a | 686 | static void update_watchdog(int cpu) |
9809b18f | 687 | { |
9809b18f MH |
688 | /* |
689 | * Make sure that perf event counter will adopt to a new | |
690 | * sampling period. Updating the sampling period directly would | |
691 | * be much nicer but we do not have an API for that now so | |
692 | * let's use a big hammer. | |
693 | * Hrtimer will adopt the new period on the next tick but this | |
694 | * might be late already so we have to restart the timer as well. | |
695 | */ | |
696 | watchdog_nmi_disable(cpu); | |
e0a23b06 | 697 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
9809b18f MH |
698 | watchdog_nmi_enable(cpu); |
699 | } | |
700 | ||
b2f57c3a | 701 | static void update_watchdog_all_cpus(void) |
9809b18f MH |
702 | { |
703 | int cpu; | |
704 | ||
705 | get_online_cpus(); | |
fe4ba3c3 | 706 | for_each_watchdog_cpu(cpu) |
b2f57c3a | 707 | update_watchdog(cpu); |
9809b18f MH |
708 | put_online_cpus(); |
709 | } | |
710 | ||
b2f57c3a | 711 | static int watchdog_enable_all_cpus(void) |
58687acb | 712 | { |
b8900bc0 | 713 | int err = 0; |
58687acb | 714 | |
3c00ea82 | 715 | if (!watchdog_running) { |
b8900bc0 FW |
716 | err = smpboot_register_percpu_thread(&watchdog_threads); |
717 | if (err) | |
718 | pr_err("Failed to create watchdog threads, disabled\n"); | |
fe4ba3c3 CM |
719 | else { |
720 | if (smpboot_update_cpumask_percpu_thread( | |
721 | &watchdog_threads, &watchdog_cpumask)) | |
722 | pr_err("Failed to set cpumask for watchdog threads\n"); | |
3c00ea82 | 723 | watchdog_running = 1; |
fe4ba3c3 | 724 | } |
b2f57c3a UO |
725 | } else { |
726 | /* | |
727 | * Enable/disable the lockup detectors or | |
728 | * change the sample period 'on the fly'. | |
729 | */ | |
730 | update_watchdog_all_cpus(); | |
bcd951cf | 731 | } |
b8900bc0 FW |
732 | |
733 | return err; | |
58687acb DZ |
734 | } |
735 | ||
b8900bc0 FW |
736 | /* prepare/enable/disable routines */ |
737 | /* sysctl functions */ | |
738 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
739 | static void watchdog_disable_all_cpus(void) |
740 | { | |
3c00ea82 FW |
741 | if (watchdog_running) { |
742 | watchdog_running = 0; | |
b8900bc0 | 743 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 744 | } |
58687acb DZ |
745 | } |
746 | ||
58687acb | 747 | /* |
a0c9cbb9 UO |
748 | * Update the run state of the lockup detectors. |
749 | */ | |
750 | static int proc_watchdog_update(void) | |
751 | { | |
752 | int err = 0; | |
753 | ||
754 | /* | |
755 | * Watchdog threads won't be started if they are already active. | |
756 | * The 'watchdog_running' variable in watchdog_*_all_cpus() takes | |
757 | * care of this. If those threads are already active, the sample | |
758 | * period will be updated and the lockup detectors will be enabled | |
759 | * or disabled 'on the fly'. | |
760 | */ | |
761 | if (watchdog_enabled && watchdog_thresh) | |
b2f57c3a | 762 | err = watchdog_enable_all_cpus(); |
a0c9cbb9 UO |
763 | else |
764 | watchdog_disable_all_cpus(); | |
765 | ||
766 | return err; | |
767 | ||
768 | } | |
769 | ||
ef246a21 UO |
770 | /* |
771 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
772 | * | |
773 | * caller | table->data points to | 'which' contains the flag(s) | |
774 | * -------------------|-----------------------|----------------------------- | |
775 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed | |
776 | * | | with SOFT_WATCHDOG_ENABLED | |
777 | * -------------------|-----------------------|----------------------------- | |
778 | * proc_nmi_watchdog | nmi_watchdog_enabled | NMI_WATCHDOG_ENABLED | |
779 | * -------------------|-----------------------|----------------------------- | |
780 | * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED | |
781 | */ | |
782 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
783 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
784 | { | |
785 | int err, old, new; | |
786 | int *watchdog_param = (int *)table->data; | |
787 | ||
788 | mutex_lock(&watchdog_proc_mutex); | |
789 | ||
790 | /* | |
791 | * If the parameter is being read return the state of the corresponding | |
792 | * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the | |
793 | * run state of the lockup detectors. | |
794 | */ | |
795 | if (!write) { | |
796 | *watchdog_param = (watchdog_enabled & which) != 0; | |
797 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
798 | } else { | |
799 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
800 | if (err) | |
801 | goto out; | |
802 | ||
803 | /* | |
804 | * There is a race window between fetching the current value | |
805 | * from 'watchdog_enabled' and storing the new value. During | |
806 | * this race window, watchdog_nmi_enable() can sneak in and | |
807 | * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'. | |
808 | * The 'cmpxchg' detects this race and the loop retries. | |
809 | */ | |
810 | do { | |
811 | old = watchdog_enabled; | |
812 | /* | |
813 | * If the parameter value is not zero set the | |
814 | * corresponding bit(s), else clear it(them). | |
815 | */ | |
816 | if (*watchdog_param) | |
817 | new = old | which; | |
818 | else | |
819 | new = old & ~which; | |
820 | } while (cmpxchg(&watchdog_enabled, old, new) != old); | |
821 | ||
822 | /* | |
823 | * Update the run state of the lockup detectors. | |
824 | * Restore 'watchdog_enabled' on failure. | |
825 | */ | |
826 | err = proc_watchdog_update(); | |
827 | if (err) | |
828 | watchdog_enabled = old; | |
829 | } | |
830 | out: | |
831 | mutex_unlock(&watchdog_proc_mutex); | |
832 | return err; | |
833 | } | |
834 | ||
83a80a39 UO |
835 | /* |
836 | * /proc/sys/kernel/watchdog | |
837 | */ | |
838 | int proc_watchdog(struct ctl_table *table, int write, | |
839 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
840 | { | |
841 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
842 | table, write, buffer, lenp, ppos); | |
843 | } | |
844 | ||
845 | /* | |
846 | * /proc/sys/kernel/nmi_watchdog | |
58687acb | 847 | */ |
83a80a39 UO |
848 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
849 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
850 | { | |
851 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, | |
852 | table, write, buffer, lenp, ppos); | |
853 | } | |
854 | ||
855 | /* | |
856 | * /proc/sys/kernel/soft_watchdog | |
857 | */ | |
858 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
859 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
860 | { | |
861 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
862 | table, write, buffer, lenp, ppos); | |
863 | } | |
58687acb | 864 | |
83a80a39 UO |
865 | /* |
866 | * /proc/sys/kernel/watchdog_thresh | |
867 | */ | |
868 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
869 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 870 | { |
83a80a39 | 871 | int err, old; |
58687acb | 872 | |
359e6fab | 873 | mutex_lock(&watchdog_proc_mutex); |
bcd951cf | 874 | |
83a80a39 | 875 | old = ACCESS_ONCE(watchdog_thresh); |
b8900bc0 | 876 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a39 | 877 | |
b8900bc0 | 878 | if (err || !write) |
359e6fab | 879 | goto out; |
e04ab2bc | 880 | |
b66a2356 | 881 | /* |
83a80a39 UO |
882 | * Update the sample period. |
883 | * Restore 'watchdog_thresh' on failure. | |
b66a2356 | 884 | */ |
83a80a39 UO |
885 | set_sample_period(); |
886 | err = proc_watchdog_update(); | |
887 | if (err) | |
888 | watchdog_thresh = old; | |
359e6fab MH |
889 | out: |
890 | mutex_unlock(&watchdog_proc_mutex); | |
b8900bc0 | 891 | return err; |
58687acb | 892 | } |
fe4ba3c3 CM |
893 | |
894 | /* | |
895 | * The cpumask is the mask of possible cpus that the watchdog can run | |
896 | * on, not the mask of cpus it is actually running on. This allows the | |
897 | * user to specify a mask that will include cpus that have not yet | |
898 | * been brought online, if desired. | |
899 | */ | |
900 | int proc_watchdog_cpumask(struct ctl_table *table, int write, | |
901 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
902 | { | |
903 | int err; | |
904 | ||
905 | mutex_lock(&watchdog_proc_mutex); | |
906 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); | |
907 | if (!err && write) { | |
908 | /* Remove impossible cpus to keep sysctl output cleaner. */ | |
909 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, | |
910 | cpu_possible_mask); | |
911 | ||
912 | if (watchdog_running) { | |
913 | /* | |
914 | * Failure would be due to being unable to allocate | |
915 | * a temporary cpumask, so we are likely not in a | |
916 | * position to do much else to make things better. | |
917 | */ | |
918 | if (smpboot_update_cpumask_percpu_thread( | |
919 | &watchdog_threads, &watchdog_cpumask) != 0) | |
920 | pr_err("cpumask update failed\n"); | |
921 | } | |
922 | } | |
923 | mutex_unlock(&watchdog_proc_mutex); | |
924 | return err; | |
925 | } | |
926 | ||
58687acb DZ |
927 | #endif /* CONFIG_SYSCTL */ |
928 | ||
004417a6 | 929 | void __init lockup_detector_init(void) |
58687acb | 930 | { |
0f34c400 | 931 | set_sample_period(); |
b8900bc0 | 932 | |
fe4ba3c3 CM |
933 | #ifdef CONFIG_NO_HZ_FULL |
934 | if (tick_nohz_full_enabled()) { | |
935 | if (!cpumask_empty(tick_nohz_full_mask)) | |
936 | pr_info("Disabling watchdog on nohz_full cores by default\n"); | |
937 | cpumask_andnot(&watchdog_cpumask, cpu_possible_mask, | |
938 | tick_nohz_full_mask); | |
939 | } else | |
940 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
941 | #else | |
942 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
943 | #endif | |
944 | ||
195daf66 | 945 | if (watchdog_enabled) |
b2f57c3a | 946 | watchdog_enable_all_cpus(); |
58687acb | 947 | } |