From: Jiri Olsa jolsa@kernel.org
[ Upstream commit 475113d937adfd150eb82b5e2c5507125a68e7af ]
It's possible to set up PEBS events to get only errors and not any data, like on SNB-X (model 45) and IVB-EP (model 62) via 2 perf commands running simultaneously:
taskset -c 1 ./perf record -c 4 -e branches:pp -j any -C 10
This leads to a soft lock up, because the error path of the intel_pmu_drain_pebs_nhm() does not account event->hw.interrupt for error PEBS interrupts, so in case you're getting ONLY errors you don't have a way to stop the event when it's over the max_samples_per_tick limit:
NMI watchdog: BUG: soft lockup - CPU#22 stuck for 22s! [perf_fuzzer:5816] ... RIP: 0010:[<ffffffff81159232>] [<ffffffff81159232>] smp_call_function_single+0xe2/0x140 ... Call Trace: ? trace_hardirqs_on_caller+0xf5/0x1b0 ? perf_cgroup_attach+0x70/0x70 perf_install_in_context+0x199/0x1b0 ? ctx_resched+0x90/0x90 SYSC_perf_event_open+0x641/0xf90 SyS_perf_event_open+0x9/0x10 do_syscall_64+0x6c/0x1f0 entry_SYSCALL64_slow_path+0x25/0x25
Add perf_event_account_interrupt() which does the interrupt and frequency checks and call it from intel_pmu_drain_pebs_nhm()'s error path.
We keep the pending_kill and pending_wakeup logic only in the __perf_event_overflow() path, because they make sense only if there's any data to deliver.
Signed-off-by: Jiri Olsa jolsa@kernel.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Stephane Eranian eranian@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vince@deater.net Cc: Vince Weaver vincent.weaver@maine.edu Link: http://lkml.kernel.org/r/1482931866-6018-2-git-send-email-jolsa@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@verizon.com --- arch/x86/events/intel/ds.c | 6 +++++- include/linux/perf_event.h | 1 + kernel/events/core.c | 47 ++++++++++++++++++++++++++++++---------------- 3 files changed, 37 insertions(+), 17 deletions(-)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index be202390bbd3..9dfeeeca0ea8 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1389,9 +1389,13 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs) continue;
/* log dropped samples number */ - if (error[bit]) + if (error[bit]) { perf_log_lost_samples(event, error[bit]);
+ if (perf_event_account_interrupt(event)) + x86_pmu_stop(event, 0); + } + if (counts[bit]) { __intel_pmu_pebs_event(event, iregs, base, top, bit, counts[bit]); diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 4741ecdb9817..78ed8105e64d 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1259,6 +1259,7 @@ extern void perf_event_disable(struct perf_event *event); extern void perf_event_disable_local(struct perf_event *event); extern void perf_event_disable_inatomic(struct perf_event *event); extern void perf_event_task_tick(void); +extern int perf_event_account_interrupt(struct perf_event *event); #else /* !CONFIG_PERF_EVENTS: */ static inline void * perf_aux_output_begin(struct perf_output_handle *handle, diff --git a/kernel/events/core.c b/kernel/events/core.c index 36ff2d93f222..13b9784427b0 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7088,25 +7088,12 @@ static void perf_log_itrace_start(struct perf_event *event) perf_output_end(&handle); }
-/* - * Generic event overflow handling, sampling. - */ - -static int __perf_event_overflow(struct perf_event *event, - int throttle, struct perf_sample_data *data, - struct pt_regs *regs) +static int +__perf_event_account_interrupt(struct perf_event *event, int throttle) { - int events = atomic_read(&event->event_limit); struct hw_perf_event *hwc = &event->hw; - u64 seq; int ret = 0; - - /* - * Non-sampling counters might still use the PMI to fold short - * hardware counters, ignore those. - */ - if (unlikely(!is_sampling_event(event))) - return 0; + u64 seq;
seq = __this_cpu_read(perf_throttled_seq); if (seq != hwc->interrupts_seq) { @@ -7134,6 +7121,34 @@ static int __perf_event_overflow(struct perf_event *event, perf_adjust_period(event, delta, hwc->last_period, true); }
+ return ret; +} + +int perf_event_account_interrupt(struct perf_event *event) +{ + return __perf_event_account_interrupt(event, 1); +} + +/* + * Generic event overflow handling, sampling. + */ + +static int __perf_event_overflow(struct perf_event *event, + int throttle, struct perf_sample_data *data, + struct pt_regs *regs) +{ + int events = atomic_read(&event->event_limit); + int ret = 0; + + /* + * Non-sampling counters might still use the PMI to fold short + * hardware counters, ignore those. + */ + if (unlikely(!is_sampling_event(event))) + return 0; + + ret = __perf_event_account_interrupt(event, throttle); + /* * XXX event_limit might not quite work as expected on inherited * events