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Date: Fri, 25 Jan 2019 08:00:56 -0800 From: Andi Kleen <ak@...ux.intel.com> To: Ravi Bangoria <ravi.bangoria@...ux.ibm.com> Cc: lkml <linux-kernel@...r.kernel.org>, Jiri Olsa <jolsa@...hat.com>, Peter Zijlstra <peterz@...radead.org>, linux-perf-users@...r.kernel.org, Arnaldo Carvalho de Melo <acme@...nel.org>, eranian@...gle.com, vincent.weaver@...ne.edu, "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> Subject: Re: System crash with perf_fuzzer (kernel: 5.0.0-rc3) > [Fri Jan 25 10:28:53 2019] perf: interrupt took too long (2501 > 2500), lowering kernel.perf_event_max_sample_rate to 79750 > [Fri Jan 25 10:29:08 2019] perf: interrupt took too long (3136 > 3126), lowering kernel.perf_event_max_sample_rate to 63750 > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (4140 > 3920), lowering kernel.perf_event_max_sample_rate to 48250 > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (5231 > 5175), lowering kernel.perf_event_max_sample_rate to 38000 > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (6736 > 6538), lowering kernel.perf_event_max_sample_rate to 29500 These are fairly normal. > [Fri Jan 25 10:32:44 2019] ------------[ cut here ]------------ > [Fri Jan 25 10:32:44 2019] perfevents: irq loop stuck! I believe it's always possible to cause an irq loop. This happens when the PMU is programmed to cause PMIs on multiple counters too quickly. Maybe should just recover from it without printing such scary messages. Right now the scary message is justified because it resets the complete PMU. Perhaps need to be a bit more selective resetting on only the events that loop. > [Fri Jan 25 10:32:44 2019] WARNING: CPU: 1 PID: 0 at arch/x86/events/intel/core.c:2440 intel_pmu_handle_irq+0x158/0x170 This looks independent. I would apply the following patch (cut'n'pasted, so may need manual apply) and then run with cd /sys/kernel/debug/tracing echo 50000 > buffer_size_kb echo default_do_nmi > set_graph_function echo 1 > events/msr/enable echo 'msr != 0xc0000100 && msr != 0x6e0' > events/msr/write_msr/filter echo function_graph > current_tracer echo printk:traceoff > set_ftrace_filter echo 1 > tracing_on and then collect the trace from /sys/kernel/debug/tracing/trace after the oops. This should show the context of when it happens. diff --git a/kernel/events/Makefile b/kernel/events/Makefile index 3c022e33c109..8afc997110e0 100644 --- a/kernel/events/Makefile +++ b/kernel/events/Makefile @@ -1,7 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 -ifdef CONFIG_FUNCTION_TRACER -CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE) -endif obj-y := core.o ring_buffer.o callchain.o
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