Re: perf: fuzzer triggered warning in intel_pmu_drain_pebs_nhm()

[Vince Weaver]

On Fri, 3 Jul 2015, Peter Zijlstra wrote:

> That said, its far too warm and I might just not be making sense.

you need to come visit Maine!  Although I am not sure the cooler weather 
necessarily improves my kernel debugging skills.

I managed to lock the machine (again this is with the patch applied).

[  299.366027] ------------[ cut here ]------------
[  299.370985] WARNING: CPU: 2 PID: 8241 at arch/x86/kernel/cpu/perf_event_intel_ds.c:1198 intel_pmu_drain_pebs_nhm+0x283/0x2e0()
[  299.456929] CPU: 2 PID: 8241 Comm: perf_fuzzer Tainted: G        W       4.1.0+ #164
[  299.465750] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
[  299.474274]  ffffffff81a105a0 ffff88011ea85b10 ffffffff8169f823 0000000000000000
[  299.482864]  0000000000000000 ffff88011ea85b50 ffffffff8106ec8a ffff88011ea85ba0
[  299.491488]  0000000000000000 0000000000000001 ffff88011ea8bd80 ffff8801190400c0
[  299.500029] Call Trace:
[  299.503190]  <NMI>  [<ffffffff8169f823>] dump_stack+0x45/0x57
[  299.509936]  [<ffffffff8106ec8a>] warn_slowpath_common+0x8a/0xc0
[  299.516901]  [<ffffffff8106ed7a>] warn_slowpath_null+0x1a/0x20
[  299.523715]  [<ffffffff8102f783>] intel_pmu_drain_pebs_nhm+0x283/0x2e0
[  299.531268]  [<ffffffff81032235>] intel_pmu_handle_irq+0x255/0x440
[  299.538487]  [<ffffffff81028e76>] perf_event_nmi_handler+0x26/0x40
[  299.545638]  [<ffffffff810181ad>] nmi_handle+0x9d/0x140
[  299.551772]  [<ffffffff81018115>] ? nmi_handle+0x5/0x140
[  299.558013]  [<ffffffff8101843a>] default_do_nmi+0x4a/0x120
[  299.564527]  [<ffffffff8101859d>] do_nmi+0x8d/0xc0
[  299.570185]  [<ffffffff816a979f>] end_repeat_nmi+0x1e/0x2e
[  299.576580]  [<ffffffff811bc9d2>] ? check_poison_obj+0x92/0x230
[  299.583390]  [<ffffffff811bc9d2>] ? check_poison_obj+0x92/0x230
[  299.590163]  [<ffffffff811bc9d2>] ? check_poison_obj+0x92/0x230
[  299.596922]  <<EOE>>  [<ffffffff8115bea8>] ? perf_event_alloc+0x58/0x680
[  299.604594]  [<ffffffff811bcf7d>] cache_alloc_debugcheck_after.isra.51+0x1cd/0x250
[  299.613140]  [<ffffffff811c08b6>] kmem_cache_alloc_trace+0xa6/0x510
[  299.620330]  [<ffffffff8115bea8>] ? perf_event_alloc+0x58/0x680
[  299.627088]  [<ffffffff8106ee48>] ? get_online_cpus+0x58/0x70
[  299.633688]  [<ffffffff8115bea8>] perf_event_alloc+0x58/0x680
[  299.640319]  [<ffffffff8115c897>] SYSC_perf_event_open+0x3c7/0xd40
[  299.647353]  [<ffffffff8105f86b>] ? __do_page_fault+0x1ab/0x3f0
[  299.654172]  [<ffffffff8115d689>] SyS_perf_event_open+0x9/0x10
[  299.660871]  [<ffffffff816a7572>] entry_SYSCALL_64_fastpath+0x16/0x7a
[  299.668236] ---[ end trace 3356c74581c13f1d ]---
[  299.673648] Uhhuh. NMI received for unknown reason 31 on CPU 2.
[  299.680427] Do you have a strange power saving mode enabled?
[  299.686963] Dazed and confused, but trying to continue
[  299.692904] Uhhuh. NMI received for unknown reason 31 on CPU 2.
[  299.699748] Do you have a strange power saving mode enabled?
[  299.706227] Dazed and confused, but trying to continue
[  299.712172] Uhhuh. NMI received for unknown reason 31 on CPU 2.
[  299.718946] Do you have a strange power saving mode enabled?
[  299.725446] Dazed and confused, but trying to continue
[  299.731419] Uhhuh. NMI received for unknown reason 31 on CPU 2.
[  299.738235] Do you have a strange power saving mode enabled?
[  299.744740] Dazed and confused, but trying to continue
[  299.750660] Uhhuh. NMI received for unknown reason 21 on CPU 2.
[  299.757398] Do you have a strange power saving mode enabled?
[  299.763862] Dazed and confused, but trying to continue

(machine eventually locks up after lots of these messages)

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