Re: [PATCH 2/2] perf/x86/amd: Don't allow pre-emption in amd_pmu_lbr_reset()

[Peter Zijlstra]

On Tue, Oct 24, 2023 at 11:04:06AM -0500, Mario Limonciello wrote:

> > IIRC this is the hotplug thread running a teardown function on that CPU
> > itself. It being a strict per-cpu thread should not trip
> > smp_processor_id() wanrs.
> > 
> 
> BUG: using smp_processor_id() in preemptible [00000000] code: rtcwake/2960
> caller is amd_pmu_lbr_reset+0x19/0xc0
> CPU: 104 PID: 2960 Comm: rtcwake Not tainted 6.6.0-rc6-00002-g3e2c7f3ac51f

Very much not the cpuhp/%u thread :/, let me try and figure out how that
happens.

> #1025
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x44/0x60
>  check_preemption_disabled+0xce/0xf0
>  ? __pfx_x86_pmu_dead_cpu+0x10/0x10
>  amd_pmu_lbr_reset+0x19/0xc0
>  ? __pfx_x86_pmu_dead_cpu+0x10/0x10
>  amd_pmu_cpu_reset.constprop.0+0x51/0x60
>  amd_pmu_cpu_dead+0x3e/0x90
>  x86_pmu_dead_cpu+0x13/0x20
>  cpuhp_invoke_callback+0x169/0x4b0
>  ? __pfx_virtnet_cpu_dead+0x10/0x10
>  __cpuhp_invoke_callback_range+0x76/0xe0
>  _cpu_down+0x112/0x270
>  freeze_secondary_cpus+0x8e/0x280
>  suspend_devices_and_enter+0x342/0x900
>  pm_suspend+0x2fd/0x690
>  state_store+0x71/0xd0
>  kernfs_fop_write_iter+0x128/0x1c0
>  vfs_write+0x2db/0x400
>  ksys_write+0x5f/0xe0
>  do_syscall_64+0x59/0x90
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? count_memcg_events.constprop.0+0x1a/0x30
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? handle_mm_fault+0x1e9/0x340
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? preempt_count_add+0x4d/0xa0
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? up_read+0x38/0x70
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? do_user_addr_fault+0x343/0x6b0
>  ? srso_alias_return_thunk+0x5/0x7f
>  ? exc_page_fault+0x74/0x170
>  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> RIP: 0033:0x7f32f8d14a77
> Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa
> 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff
> 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
> RSP: 002b:00007ffdc648de18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f32f8d14a77
> RDX: 0000000000000004 RSI: 000055b2fc2a5670 RDI: 0000000000000004
> RBP: 000055b2fc2a5670 R08: 0000000000000000 R09: 000055b2fc2a5670
> R10: 00007f32f8e1a2f0 R11: 0000000000000246 R12: 0000000000000004
> R13: 000055b2fc2a2480 R14: 00007f32f8e16600 R15: 00007f32f8e15a00
>  </TASK>