Re: [PATCH] watchdog/hardlockup: reassign last_timestamp when enable nmi event
From: kbuild test robot
Date: Sun Oct 13 2019 - 16:35:37 EST
Hi Li,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Li-RongQing/watchdog-hardlockup-reassign-last_timestamp-when-enable-nmi-event/20191014-022936
config: i386-randconfig-g004-201941 (attached as .config)
compiler: gcc-7 (Debian 7.4.0-13) 7.4.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
All error/warnings (new ones prefixed by >>):
In file included from include/asm-generic/percpu.h:7:0,
from arch/x86/include/asm/percpu.h:556,
from arch/x86/include/asm/current.h:6,
from include/linux/sched.h:12,
from include/linux/nmi.h:8,
from kernel/watchdog_hld.c:15:
kernel/watchdog_hld.c: In function 'hardlockup_detector_perf_enable':
>> kernel/watchdog_hld.c:201:17: error: 'last_timestamp' undeclared (first use in this function); did you mean 'statx_timestamp'?
this_cpu_write(last_timestamp, now);
^
include/linux/percpu-defs.h:220:47: note: in definition of macro '__verify_pcpu_ptr'
const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
^~~
>> include/linux/percpu-defs.h:509:34: note: in expansion of macro '__pcpu_size_call'
#define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val)
^~~~~~~~~~~~~~~~
>> kernel/watchdog_hld.c:201:2: note: in expansion of macro 'this_cpu_write'
this_cpu_write(last_timestamp, now);
^~~~~~~~~~~~~~
kernel/watchdog_hld.c:201:17: note: each undeclared identifier is reported only once for each function it appears in
this_cpu_write(last_timestamp, now);
^
include/linux/percpu-defs.h:220:47: note: in definition of macro '__verify_pcpu_ptr'
const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
^~~
>> include/linux/percpu-defs.h:509:34: note: in expansion of macro '__pcpu_size_call'
#define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val)
^~~~~~~~~~~~~~~~
>> kernel/watchdog_hld.c:201:2: note: in expansion of macro 'this_cpu_write'
this_cpu_write(last_timestamp, now);
^~~~~~~~~~~~~~
kernel/watchdog_hld.c: In function 'hardlockup_detector_perf_restart':
kernel/watchdog_hld.c:283:12: error: 'last_timestamp' undeclared (first use in this function); did you mean 'statx_timestamp'?
per_cpu(last_timestamp, cpu) = now;
^
include/linux/percpu-defs.h:220:47: note: in definition of macro '__verify_pcpu_ptr'
const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
^~~
include/linux/percpu-defs.h:270:29: note: in expansion of macro 'per_cpu_ptr'
#define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu))
^~~~~~~~~~~
>> kernel/watchdog_hld.c:283:4: note: in expansion of macro 'per_cpu'
per_cpu(last_timestamp, cpu) = now;
^~~~~~~
vim +201 kernel/watchdog_hld.c
14
> 15 #include <linux/nmi.h>
16 #include <linux/atomic.h>
17 #include <linux/module.h>
18 #include <linux/sched/debug.h>
19
20 #include <asm/irq_regs.h>
21 #include <linux/perf_event.h>
22
23 static DEFINE_PER_CPU(bool, hard_watchdog_warn);
24 static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
25 static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
26 static DEFINE_PER_CPU(struct perf_event *, dead_event);
27 static struct cpumask dead_events_mask;
28
29 static unsigned long hardlockup_allcpu_dumped;
30 static atomic_t watchdog_cpus = ATOMIC_INIT(0);
31
32 notrace void arch_touch_nmi_watchdog(void)
33 {
34 /*
35 * Using __raw here because some code paths have
36 * preemption enabled. If preemption is enabled
37 * then interrupts should be enabled too, in which
38 * case we shouldn't have to worry about the watchdog
39 * going off.
40 */
41 raw_cpu_write(watchdog_nmi_touch, true);
42 }
43 EXPORT_SYMBOL(arch_touch_nmi_watchdog);
44
45 #ifdef CONFIG_HARDLOCKUP_CHECK_TIMESTAMP
46 static DEFINE_PER_CPU(ktime_t, last_timestamp);
47 static DEFINE_PER_CPU(unsigned int, nmi_rearmed);
48 static ktime_t watchdog_hrtimer_sample_threshold __read_mostly;
49
50 void watchdog_update_hrtimer_threshold(u64 period)
51 {
52 /*
53 * The hrtimer runs with a period of (watchdog_threshold * 2) / 5
54 *
55 * So it runs effectively with 2.5 times the rate of the NMI
56 * watchdog. That means the hrtimer should fire 2-3 times before
57 * the NMI watchdog expires. The NMI watchdog on x86 is based on
58 * unhalted CPU cycles, so if Turbo-Mode is enabled the CPU cycles
59 * might run way faster than expected and the NMI fires in a
60 * smaller period than the one deduced from the nominal CPU
61 * frequency. Depending on the Turbo-Mode factor this might be fast
62 * enough to get the NMI period smaller than the hrtimer watchdog
63 * period and trigger false positives.
64 *
65 * The sample threshold is used to check in the NMI handler whether
66 * the minimum time between two NMI samples has elapsed. That
67 * prevents false positives.
68 *
69 * Set this to 4/5 of the actual watchdog threshold period so the
70 * hrtimer is guaranteed to fire at least once within the real
71 * watchdog threshold.
72 */
73 watchdog_hrtimer_sample_threshold = period * 2;
74 }
75
76 static bool watchdog_check_timestamp(void)
77 {
78 ktime_t delta, now = ktime_get_mono_fast_ns();
79
80 delta = now - __this_cpu_read(last_timestamp);
81 if (delta < watchdog_hrtimer_sample_threshold) {
82 /*
83 * If ktime is jiffies based, a stalled timer would prevent
84 * jiffies from being incremented and the filter would look
85 * at a stale timestamp and never trigger.
86 */
87 if (__this_cpu_inc_return(nmi_rearmed) < 10)
88 return false;
89 }
90 __this_cpu_write(nmi_rearmed, 0);
91 __this_cpu_write(last_timestamp, now);
92 return true;
93 }
94 #else
95 static inline bool watchdog_check_timestamp(void)
96 {
97 return true;
98 }
99 #endif
100
101 static struct perf_event_attr wd_hw_attr = {
102 .type = PERF_TYPE_HARDWARE,
103 .config = PERF_COUNT_HW_CPU_CYCLES,
104 .size = sizeof(struct perf_event_attr),
105 .pinned = 1,
106 .disabled = 1,
107 };
108
109 /* Callback function for perf event subsystem */
110 static void watchdog_overflow_callback(struct perf_event *event,
111 struct perf_sample_data *data,
112 struct pt_regs *regs)
113 {
114 /* Ensure the watchdog never gets throttled */
115 event->hw.interrupts = 0;
116
117 if (__this_cpu_read(watchdog_nmi_touch) == true) {
118 __this_cpu_write(watchdog_nmi_touch, false);
119 return;
120 }
121
122 if (!watchdog_check_timestamp())
123 return;
124
125 /* check for a hardlockup
126 * This is done by making sure our timer interrupt
127 * is incrementing. The timer interrupt should have
128 * fired multiple times before we overflow'd. If it hasn't
129 * then this is a good indication the cpu is stuck
130 */
131 if (is_hardlockup()) {
132 int this_cpu = smp_processor_id();
133
134 /* only print hardlockups once */
135 if (__this_cpu_read(hard_watchdog_warn) == true)
136 return;
137
138 pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n",
139 this_cpu);
140 print_modules();
141 print_irqtrace_events(current);
142 if (regs)
143 show_regs(regs);
144 else
145 dump_stack();
146
147 /*
148 * Perform all-CPU dump only once to avoid multiple hardlockups
149 * generating interleaving traces
150 */
151 if (sysctl_hardlockup_all_cpu_backtrace &&
152 !test_and_set_bit(0, &hardlockup_allcpu_dumped))
153 trigger_allbutself_cpu_backtrace();
154
155 if (hardlockup_panic)
156 nmi_panic(regs, "Hard LOCKUP");
157
158 __this_cpu_write(hard_watchdog_warn, true);
159 return;
160 }
161
162 __this_cpu_write(hard_watchdog_warn, false);
163 return;
164 }
165
166 static int hardlockup_detector_event_create(void)
167 {
168 unsigned int cpu = smp_processor_id();
169 struct perf_event_attr *wd_attr;
170 struct perf_event *evt;
171
172 wd_attr = &wd_hw_attr;
173 wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
174
175 /* Try to register using hardware perf events */
176 evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
177 watchdog_overflow_callback, NULL);
178 if (IS_ERR(evt)) {
179 pr_debug("Perf event create on CPU %d failed with %ld\n", cpu,
180 PTR_ERR(evt));
181 return PTR_ERR(evt);
182 }
183 this_cpu_write(watchdog_ev, evt);
184 return 0;
185 }
186
187 /**
188 * hardlockup_detector_perf_enable - Enable the local event
189 */
190 void hardlockup_detector_perf_enable(void)
191 {
192 ktime_t now = ktime_get_mono_fast_ns();
193
194 if (hardlockup_detector_event_create())
195 return;
196
197 /* use original value for check */
198 if (!atomic_fetch_inc(&watchdog_cpus))
199 pr_info("Enabled. Permanently consumes one hw-PMU counter.\n");
200
> 201 this_cpu_write(last_timestamp, now);
202 perf_event_enable(this_cpu_read(watchdog_ev));
203 }
204
205 /**
206 * hardlockup_detector_perf_disable - Disable the local event
207 */
208 void hardlockup_detector_perf_disable(void)
209 {
210 struct perf_event *event = this_cpu_read(watchdog_ev);
211
212 if (event) {
213 perf_event_disable(event);
214 this_cpu_write(watchdog_ev, NULL);
215 this_cpu_write(dead_event, event);
216 cpumask_set_cpu(smp_processor_id(), &dead_events_mask);
217 atomic_dec(&watchdog_cpus);
218 }
219 }
220
221 /**
222 * hardlockup_detector_perf_cleanup - Cleanup disabled events and destroy them
223 *
224 * Called from lockup_detector_cleanup(). Serialized by the caller.
225 */
226 void hardlockup_detector_perf_cleanup(void)
227 {
228 int cpu;
229
230 for_each_cpu(cpu, &dead_events_mask) {
231 struct perf_event *event = per_cpu(dead_event, cpu);
232
233 /*
234 * Required because for_each_cpu() reports unconditionally
235 * CPU0 as set on UP kernels. Sigh.
236 */
237 if (event)
238 perf_event_release_kernel(event);
239 per_cpu(dead_event, cpu) = NULL;
240 }
241 cpumask_clear(&dead_events_mask);
242 }
243
244 /**
245 * hardlockup_detector_perf_stop - Globally stop watchdog events
246 *
247 * Special interface for x86 to handle the perf HT bug.
248 */
249 void __init hardlockup_detector_perf_stop(void)
250 {
251 int cpu;
252
253 lockdep_assert_cpus_held();
254
255 for_each_online_cpu(cpu) {
256 struct perf_event *event = per_cpu(watchdog_ev, cpu);
257
258 if (event)
259 perf_event_disable(event);
260 }
261 }
262
263 /**
264 * hardlockup_detector_perf_restart - Globally restart watchdog events
265 *
266 * Special interface for x86 to handle the perf HT bug.
267 */
268 void __init hardlockup_detector_perf_restart(void)
269 {
270 int cpu;
271
272 lockdep_assert_cpus_held();
273
274 if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
275 return;
276
277 for_each_online_cpu(cpu) {
278 struct perf_event *event = per_cpu(watchdog_ev, cpu);
279
280 if (event) {
281 ktime_t now = ktime_get_mono_fast_ns();
282
> 283 per_cpu(last_timestamp, cpu) = now;
284 perf_event_enable(event);
285 }
286 }
287 }
288
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