FYI, we noticed the following commit:

commit: 3e95abd02e38d3195d33b7ffaeba875ffff24def ("ACPI / CPPC: Make cppc acpi driver aware of pcc subspace ids")
url: https://github.com/0day-ci/linux/commits/George-Cherian/Make-cppc-acpi-driver-aware-of-pcc-subspace-ids/20170402-124136
base: https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git linux-next

in testcase: reaim
with following parameters:

	runtime: 300s
	nr_task: 100%
	nr_job: 1000
	test: alltests
	cpufreq_governor: performance

test-description: REAIM is an updated and improved version of AIM 7 benchmark.
test-url: https://sourceforge.net/projects/re-aim-7/


on test machine: 112 threads Skylake with 64G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+------------------------------------------------------------------+------------+------------+
|                                                                  | 042703d265 | 3e95abd02e |
+------------------------------------------------------------------+------------+------------+
| boot_successes                                                   | 4          | 4          |
| boot_failures                                                    | 0          | 6          |
| BUG:unable_to_handle_kernel                                      | 0          | 4          |
| Oops:#[##]                                                       | 0          | 4          |
| Kernel_panic-not_syncing:Fatal_exception                         | 0          | 4          |
| invoked_oom-killer:gfp_mask=0x                                   | 0          | 2          |
| Mem-Info                                                         | 0          | 2          |
| Kernel_panic-not_syncing:Out_of_memory_and_no_killable_processes | 0          | 2          |
+------------------------------------------------------------------+------------+------------+



[   20.247700] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
[   20.255890] IP: pcc_mbox_request_channel+0x42/0x140
[   20.260986] PGD 0 
[   20.260986] 
[   20.264939] Oops: 0000 [#1] SMP
[   20.268301] Modules linked in:
[   20.271597] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 4.11.0-rc4-00028-g3e95abd #5
[   20.279524] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS SE5C620.86B.01.00.0294.101220161509 10/12/2016
[   20.289958] task: ffff88103ddc0000 task.stack: ffffc90000078000
[   20.296101] RIP: 0010:pcc_mbox_request_channel+0x42/0x140
[   20.301720] RSP: 0000:ffffc9000007bc78 EFLAGS: 00010207
[   20.307166] RAX: ffffffff823b8b00 RBX: 0000000000000000 RCX: 000000000000017a
[   20.314557] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff820d15e0
[   20.321908] RBP: ffffc9000007bca8 R08: 000000000001cd20 R09: ffffffff814e5997
[   20.329264] R10: ffffea002105aa80 R11: 000000000000005f R12: 0000000000000000
[   20.336614] R13: 0000000000000000 R14: ffffffff823b8b00 R15: 0000000000000000
[   20.343963] FS:  0000000000000000(0000) GS:ffff88085d900000(0000) knlGS:0000000000000000
[   20.352421] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   20.358388] CR2: 0000000000000010 CR3: 000000107f011000 CR4: 00000000003406e0
[   20.365743] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   20.373093] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   20.380440] Call Trace:
[   20.383109]  acpi_cppc_processor_probe+0x2df/0x47d
[   20.388125]  __acpi_processor_start+0x3f/0x179
[   20.392815]  acpi_processor_start+0x35/0x38
[   20.397221]  driver_probe_device+0x135/0x289
[   20.401711]  __driver_attach+0x6f/0x91
[   20.405682]  ? driver_probe_device+0x289/0x289
[   20.410340]  bus_for_each_dev+0x6d/0x85
[   20.414399]  driver_attach+0x1e/0x20
[   20.418193]  bus_add_driver+0xf3/0x1e3
[   20.422165]  ? set_debug_rodata+0x12/0x12
[   20.426399]  driver_register+0x88/0xbf
[   20.430369]  ? acpi_fan_driver_init+0x14/0x14
[   20.434949]  acpi_processor_driver_init+0x20/0x94
[   20.439872]  do_one_initcall+0x90/0x141
[   20.443935]  ? set_debug_rodata+0x12/0x12
[   20.448178]  kernel_init_freeable+0x16f/0x1f2
[   20.452755]  ? rest_init+0x87/0x87
[   20.456374]  kernel_init+0xe/0xf5
[   20.459913]  ret_from_fork+0x2c/0x40
[   20.463732] Code: 4c 8b 25 41 8e ae 00 78 29 3b 35 51 8e ae 00 7f 21 4c 63 ee 49 69 dd f8 00 00 00 48 03 1d be 8e ae 00 48 81 fb 00 f0 ff ff 77 07 <48> 83 7b 10 00 74 1b 48 c7 c6 86 b3 f1 81 4c 89 e7 48 c7 c3 f0 
[   20.483118] RIP: pcc_mbox_request_channel+0x42/0x140 RSP: ffffc9000007bc78
[   20.490207] CR2: 0000000000000010
[   20.493882] ---[ end trace 7ca91660c25bc27d ]---


To reproduce:

        git clone https://github.com/01org/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Kernel Test Robot