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 <l...@intel.com> 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 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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