FYI, we noticed the below changes on

https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core
commit 7aba70e47ca4e961acb5af96d5127e3fad651c7c ("x86, perf: Optimize stack walk user accesses")


+-------------------------------------------------------+------------+------------+
|                                                       | a170cc71ef | 7aba70e47c |
+-------------------------------------------------------+------------+------------+
| boot_successes                                        | 482        | 469        |
| boot_failures                                         | 0          | 15         |
| BUG:unable_to_handle_kernel                           | 0          | 13         |
| Oops                                                  | 0          | 13         |
| EIP_is_at_perf_prepare_sample                         | 0          | 13         |
| Kernel_panic-not_syncing:Fatal_exception              | 0          | 9          |
| backtrace:vfs_fstatat                                 | 0          | 2          |
| backtrace:SyS_fstatat64                               | 0          | 2          |
| Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0          | 4          |
| WARNING:at_arch/x86/mm/dump_pagetables.c:#note_page() | 0          | 2          |
| backtrace:mark_rodata_ro                              | 0          | 2          |
+-------------------------------------------------------+------------+------------+


[   21.984049] BUG: unable to handle kernel paging request at 696d2f62
[   21.986759] IP: [<4110c023>] perf_prepare_sample+0xcc/0x51d
[   21.987859] *pdpt = 0000000001a93001 *pde = 0000000000000000 
[   21.988015] Oops: 0000 [#1] PREEMPT 
[   21.988015] Modules linked in:
[   21.988015] CPU: 0 PID: 496 Comm: trinity-main Not tainted 4.3.0-01147-g7aba70e #1
[   21.988015] task: 50979040 ti: 50d24000 task.ti: 50d24000
[   21.988015] EIP: 0060:[<4110c023>] EFLAGS: 00010002 CPU: 0
[   21.988015] EIP is at perf_prepare_sample+0xcc/0x51d
[   21.988015] EAX: 696d2f62 EBX: 00000001 ECX: 00000002 EDX: 00000001
[   21.988015] ESI: 50d25e20 EDI: 50d25d60 EBP: 50d25d44 ESP: 50d25d24
[   21.988015]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
[   21.988015] CR0: 8005003b CR2: 696d2f62 CR3: 10da1a80 CR4: 000006b0
[   21.988015] DR0: 370a1000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[   21.988015] DR6: ffff0ff0 DR7: 000d0602
[   21.988015] Stack:
[   21.988015]  00000000 4110c474 00000000 000100b2 50de3800 50de3800 50d25e20 418a8d00
[   21.988015]  50d25d8c 4110c4ae 418a8d00 00000002 00000000 00000000 4110c474 00000009
[   21.988015]  00380001 00000000 00000001 00000000 50de3800 000c1459 00000000 50de3800
[   21.988015] Call Trace:
[   21.988015]  [<4110c474>] ? perf_prepare_sample+0x51d/0x51d
[   21.988015]  [<4110c4ae>] perf_event_output+0x3a/0x9f
[   21.988015]  [<4110c474>] ? perf_prepare_sample+0x51d/0x51d
[   21.988015]  [<4110c787>] __perf_event_overflow+0x274/0x2e3
[   21.988015]  [<4110d206>] perf_swevent_overflow+0x76/0xa6
[   21.988015]  [<4110d382>] perf_swevent_event+0x14c/0x156
[   21.988015]  [<4110db88>] ___perf_sw_event+0x348/0x388
[   21.988015]  [<4108a2bd>] ? sched_clock_cpu+0x16d/0x193
[   21.988015]  [<4103f3ec>] ? pvclock_clocksource_read+0xb0/0x1a0
[   21.988015]  [<4108a34f>] ? local_clock+0x28/0x32
[   21.988015]  [<41095319>] ? __lock_acquire+0x2f4/0xa48
[   21.988015]  [<41093cbd>] ? __lock_is_held+0x2d/0x43
[   21.988015]  [<41093cbd>] ? __lock_is_held+0x2d/0x43
[   21.988015]  [<4144ce5e>] __schedule+0x785/0xc57
[   21.988015]  [<4108c79b>] ? pick_next_task_fair+0x19f/0x21a
[   21.988015]  [<4144ce5e>] ? __schedule+0x785/0xc57
[   21.988015]  [<4144d380>] schedule+0x50/0x78
[   21.988015]  [<4100133a>] exit_to_usermode_loop+0x4d/0x144
[   21.988015]  [<41001a94>] prepare_exit_to_usermode+0x50/0x56
[   21.988015]  [<41453fbf>] resume_userspace+0x13/0x18
[   21.988015]  [<41450000>] ? __ww_mutex_lock+0x253/0xaf0
[   21.988015] Code: 45 f0 e8 9f 50 00 00 31 d2 85 c0 0f 95 c2 85 c0 8b 1c 95 04 4c 94 41 89 46 68 8d 4b 01 89 0c 95 04 4c 94 41 ba 01 00 00 00 74 03 <8b> 10 42 66 c1 e2 03 66 01 57 06 8b 55 ec 31 c0 81 e2 00 04 00
[   21.988015] EIP: [<4110c023>] perf_prepare_sample+0xcc/0x51d SS:ESP 0068:50d25d24
[   21.988015] CR2: 00000000696d2f62
[   21.988015] ---[ end trace 5e43f9815ea3ff0d ]---
[   21.988015] Kernel panic - not syncing: Fatal exception
[   21.988015] Kernel Offset: disabled


Thanks,
Ying Huang