FYI, we noticed the below changes on

https://github.com/0day-ci/linux Andi-Kleen/x86-perf-Use-a-new-PMU-ack-sequence-on-Skylake/20151016-074238
commit 68c3d26413417b69cde6b4e6661f29dbf40fb65a ("x86, perf: Use a new PMU ack sequence on Skylake")


+---------------------------------------------------------------------------+------------+------------+
|                                                                           | e9363deeb2 | 68c3d26413 |
+---------------------------------------------------------------------------+------------+------------+
| boot_successes                                                            | 11         | 15         |
| boot_failures                                                             | 0          | 8          |
| WARNING:at_arch/x86/kernel/cpu/perf_event_intel.c:#intel_pmu_handle_irq() | 0          | 8          |
| backtrace:dev_printk                                                      | 0          | 2          |
| backtrace:pci_pm_init                                                     | 0          | 2          |
| backtrace:acpi_bus_scan                                                   | 0          | 8          |
| backtrace:acpi_scan_init                                                  | 0          | 8          |
| backtrace:acpi_init                                                       | 0          | 8          |
| backtrace:kernel_init_freeable                                            | 0          | 8          |
+---------------------------------------------------------------------------+------------+------------+


[    1.503050] pci 0000:00:00.0: [8086:3406] type 00 class 0x060000
[    1.509793] pci 0000:00:00.0: PME# supported from D0 D3hot D3cold
[    1.515028] ------------[ cut here ]------------
[    1.515032] WARNING: CPU: 0 PID: 1 at arch/x86/kernel/cpu/perf_event_intel.c:1820 intel_pmu_handle_irq+0x481/0x4a0()
[    1.515033] perfevents: irq loop stuck!
[    1.515034] Modules linked in:
[    1.515035] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.3.0-rc4-00237-g68c3d26 #1
[    1.515036] Hardware name: Intel Corporation S5520UR/S5520UR, BIOS S5500.86B.01.00.0050.050620101605 05/06/2010
[    1.515038]  ffffffff81b7a038 ffff8801e9a05b58 ffffffff81403b62 ffff8801e9a05ba0
[    1.515039]  ffff8801e9a05b90 ffffffff810757c6 ffff8801e9a0bfc0 0000000000000064
[    1.515040]  ffff88035e881000 0000000000000040 ffff8801e9a0c1c0 ffff8801e9a05bf0
[    1.515040] Call Trace:
[    1.515048]  <NMI>  [<ffffffff81403b62>] dump_stack+0x4b/0x69
[    1.515051]  [<ffffffff810757c6>] warn_slowpath_common+0x86/0xc0
[    1.515052]  [<ffffffff8107584c>] warn_slowpath_fmt+0x4c/0x50
[    1.515053]  [<ffffffff81034071>] intel_pmu_handle_irq+0x481/0x4a0
[    1.515057]  [<ffffffff8102a8d6>] perf_event_nmi_handler+0x26/0x40
[    1.515060]  [<ffffffff81019260>] nmi_handle+0x80/0x120
[    1.515061]  [<ffffffff81019784>] default_do_nmi+0x44/0x120
[    1.515062]  [<ffffffff81019942>] do_nmi+0xe2/0x130
[    1.515065]  [<ffffffff818b1921>] end_repeat_nmi+0x1a/0x1e
[    1.515068]  [<ffffffff8141035c>] ? delay_tsc+0x2c/0x70
[    1.515069]  [<ffffffff8141035c>] ? delay_tsc+0x2c/0x70
[    1.515070]  [<ffffffff8141035c>] ? delay_tsc+0x2c/0x70
[    1.515072]  <<EOE>>  [<ffffffff814102c7>] __const_udelay+0x27/0x30
[    1.515075]  [<ffffffff81511ecc>] wait_for_xmitr+0x2c/0xa0
[    1.515077]  [<ffffffff81511f5c>] serial8250_console_putchar+0x1c/0x30
[    1.515078]  [<ffffffff81511f40>] ? wait_for_xmitr+0xa0/0xa0
[    1.515079]  [<ffffffff8150b5f3>] uart_console_write+0x33/0x60
[    1.515082]  [<ffffffff81514590>] serial8250_console_write+0xc0/0x270
[    1.515084]  [<ffffffff810951d1>] ? atomic_notifier_call_chain+0x21/0x30
[    1.515087]  [<ffffffff81503fd1>] ? vt_console_print+0x231/0x3d0
[    1.515088]  [<ffffffff8150fb46>] univ8250_console_write+0x26/0x30
[    1.515090]  [<ffffffff810cba06>] call_console_drivers+0xf6/0x100
[    1.515092]  [<ffffffff810cce5a>] console_unlock+0x2fa/0x4d0
[    1.515093]  [<ffffffff810cd3f2>] vprintk_emit+0x3c2/0x540
[    1.515096]  [<ffffffff815488a4>] dev_vprintk_emit+0xb4/0x210
[    1.515099]  [<ffffffff8147ee7d>] ? acpi_os_signal_semaphore+0x73/0x83
[    1.515102]  [<ffffffff814c0f5d>] ? acpi_ut_release_mutex+0xb4/0xbc
[    1.515104]  [<ffffffff814b3d16>] ? acpi_get_data_full+0x7d/0x90
[    1.515105]  [<ffffffff81482fa0>] ? __acpi_match_device+0x64/0x117
[    1.515106]  [<ffffffff81548a3e>] dev_printk_emit+0x3e/0x40
[    1.515109]  [<ffffffff8175a9f3>] ? raw_pci_read+0x23/0x40
[    1.515110]  [<ffffffff81548a86>] __dev_printk+0x46/0x90
[    1.515111]  [<ffffffff81548b1d>] dev_printk+0x4d/0x50
[    1.515113]  [<ffffffff814486c0>] pci_pm_init+0x1c0/0x220
[    1.515115]  [<ffffffff81443044>] pci_device_add+0xb4/0x180
[    1.515116]  [<ffffffff8144319c>] pci_scan_single_device+0x8c/0xb0
[    1.515117]  [<ffffffff81443213>] pci_scan_slot+0x53/0x110
[    1.515118]  [<ffffffff814443b8>] pci_scan_child_bus+0x38/0x150
[    1.515120]  [<ffffffff817594a0>] pci_acpi_scan_root+0x290/0x5e0
[    1.515122]  [<ffffffff8148a242>] acpi_pci_root_add+0x3b0/0x49f
[    1.515123]  [<ffffffff81ec77cd>] ? acpi_sleep_proc_init+0x2a/0x2a
[    1.515125]  [<ffffffff8148573b>] acpi_bus_attach+0xd4/0x171
[    1.515126]  [<ffffffff81485795>] acpi_bus_attach+0x12e/0x171
[    1.515127]  [<ffffffff81485795>] acpi_bus_attach+0x12e/0x171
[    1.515129]  [<ffffffff814858c6>] acpi_bus_scan+0x5c/0x67
[    1.515130]  [<ffffffff81ec7bf2>] acpi_scan_init+0x5b/0x190
[    1.515131]  [<ffffffff81ec7a36>] acpi_init+0x269/0x286
[    1.515133]  [<ffffffff81002123>] do_one_initcall+0xb3/0x1d0
[    1.515135]  [<ffffffff81e7c14e>] kernel_init_freeable+0x1c1/0x24e
[    1.515137]  [<ffffffff818a29c0>] ? rest_init+0x90/0x90
[    1.515138]  [<ffffffff818a29ce>] kernel_init+0xe/0xe0
[    1.515139]  [<ffffffff818af71f>] ret_from_fork+0x3f/0x70
[    1.515140]  [<ffffffff818a29c0>] ? rest_init+0x90/0x90
[    1.515142] ---[ end trace 01fce7d27e4440f8 ]---
[    1.515143] 


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Ying Huang