[AMD Public Use]
Hi Christian,
Since it's out of amdgpu driver scope, so I just attached my patch in this email thread instead of sending it by git sent-email.
Regards,
Guchun
-----Original Message-----
From: Koenig, Christian <Christian.Koenig@xxxxxxx>
Sent: Tuesday, August 11, 2020 3:52 PM
To: Chen, Guchun <Guchun.Chen@xxxxxxx>; Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Kuehling, Felix <Felix.Kuehling@xxxxxxx>; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; daniel@xxxxxxxx
Subject: Re: [PATCH v3] drm/amdgpu: annotate a false positive recursive locking
Nice catch, it's not often that we stumble over something like this :)
Can you provide a patch to fix this? Problem is that we probably won't be able to push it to the AMD servers, but I can probably merge it through drm-misc-next.
Until this is fixed feel free to commit the patch with the {} in place.
Thanks,
Christian.
Am 11.08.20 um 09:44 schrieb Chen, Guchun:
> [AMD Public Use]
>
> # define down_write_nest_lock(sem, nest_lock) \
> do { \
> typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
> _down_write_nest_lock(sem, &(nest_lock)->dep_map); \
> } while (0);
>
> Looks the ';' after while (0) is the error point. It should be dropped.
>
> Regards,
> Guchun
>
> -----Original Message-----
> From: Koenig, Christian <Christian.Koenig@xxxxxxx>
> Sent: Tuesday, August 11, 2020 3:41 PM
> To: Chen, Guchun <Guchun.Chen@xxxxxxx>; Li, Dennis
> <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Kuehling, Felix <Felix.Kuehling@xxxxxxx>;
> Zhang, Hawking <Hawking.Zhang@xxxxxxx>; daniel@xxxxxxxx
> Subject: Re: [PATCH v3] drm/amdgpu: annotate a false positive
> recursive locking
>
> Am 11.08.20 um 09:36 schrieb Chen, Guchun:
>> [AMD Public Use]
>>
>>> - down_write(&adev->reset_sem);
>>> + if (hive) {
>>> + down_write_nest_lock(&adev->reset_sem, &hive->hive_lock);
>>> + } else
>>> + down_write(&adev->reset_sem);
>> Coding style nit pick: You should drop the {} here.
>>
>> {} could not be dropped here, as down_write_nest_lock Is one macro with multiple lines, otherwise, build error would say 'else' missed one previous 'if'.
>> Instead of dropping, another {} should be added to else to include down_write(&adev->reset_sem), which makes the braces been balanced.
> Interesting bug, that is something which should not happen with macros in the Linux kernel. They protection by "do { ... } while(0)" is mandatory here.
>
> Let me take a look,
> Christian.
>
>> Regards,
>> Guchun
>>
>> -----Original Message-----
>> From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
>> Christian König
>> Sent: Tuesday, August 11, 2020 2:53 PM
>> To: Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx;
>> Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Kuehling, Felix
>> <Felix.Kuehling@xxxxxxx>; Zhang, Hawking <Hawking.Zhang@xxxxxxx>;
>> daniel@xxxxxxxx
>> Subject: Re: [PATCH v3] drm/amdgpu: annotate a false positive
>> recursive locking
>>
>> Am 11.08.20 um 04:12 schrieb Dennis Li:
>>> [ 584.110304] ============================================
>>> [ 584.110590] WARNING: possible recursive locking detected
>>> [ 584.110876] 5.6.0-deli-v5.6-2848-g3f3109b0e75f #1 Tainted: G OE
>>> [ 584.111164] --------------------------------------------
>>> [ 584.111456] kworker/38:1/553 is trying to acquire lock:
>>> [ 584.111721] ffff9b15ff0a47a0 (&adev->reset_sem){++++}, at:
>>> amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.112112]
>>> but task is already holding lock:
>>> [ 584.112673] ffff9b1603d247a0 (&adev->reset_sem){++++}, at:
>>> amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.113068]
>>> other info that might help us debug this:
>>> [ 584.113689] Possible unsafe locking scenario:
>>>
>>> [ 584.114350] CPU0
>>> [ 584.114685] ----
>>> [ 584.115014] lock(&adev->reset_sem);
>>> [ 584.115349] lock(&adev->reset_sem);
>>> [ 584.115678]
>>> *** DEADLOCK ***
>>>
>>> [ 584.116624] May be due to missing lock nesting notation
>>>
>>> [ 584.117284] 4 locks held by kworker/38:1/553:
>>> [ 584.117616] #0: ffff9ad635c1d348 ((wq_completion)events){+.+.},
>>> at: process_one_work+0x21f/0x630 [ 584.117967] #1:
>>> ffffac708e1c3e58 ((work_completion)(&con->recovery_work)){+.+.}, at:
>>> process_one_work+0x21f/0x630 [ 584.118358] #2: ffffffffc1c2a5d0
>>> (&tmp->hive_lock){+.+.}, at: amdgpu_device_gpu_recover+0xae/0x1030 [amdgpu] [ 584.118786] #3: ffff9b1603d247a0 (&adev->reset_sem){++++}, at: amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.119222]
>>> stack backtrace:
>>> [ 584.119990] CPU: 38 PID: 553 Comm: kworker/38:1 Kdump: loaded Tainted: G OE 5.6.0-deli-v5.6-2848-g3f3109b0e75f #1
>>> [ 584.120782] Hardware name: Supermicro SYS-7049GP-TRT/X11DPG-QT,
>>> BIOS 3.1 05/23/2019 [ 584.121223] Workqueue: events
>>> amdgpu_ras_do_recovery [amdgpu] [ 584.121638] Call Trace:
>>> [ 584.122050] dump_stack+0x98/0xd5 [ 584.122499]
>>> __lock_acquire+0x1139/0x16e0 [ 584.122931] ?
>>> trace_hardirqs_on+0x3b/0xf0 [ 584.123358] ?
>>> cancel_delayed_work+0xa6/0xc0 [ 584.123771]
>>> lock_acquire+0xb8/0x1c0 [ 584.124197] ?
>>> amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.124599] down_write+0x49/0x120 [ 584.125032] ?
>>> amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.125472]
>>> amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.125910] ?
>>> amdgpu_ras_error_query+0x1b8/0x2a0 [amdgpu] [ 584.126367]
>>> amdgpu_ras_do_recovery+0x159/0x190 [amdgpu] [ 584.126789]
>>> process_one_work+0x29e/0x630 [ 584.127208]
>>> worker_thread+0x3c/0x3f0 [ 584.127621] ?
>>> __kthread_parkme+0x61/0x90 [ 584.128014]
>>> kthread+0x12f/0x150 [ 584.128402] ? process_one_work+0x630/0x630 [
>>> 584.128790] ? kthread_park+0x90/0x90 [ 584.129174]
>>> ret_from_fork+0x3a/0x50
>>>
>>> Each adev has owned lock_class_key to avoid false positive recursive
>>> locking.
>>>
>>> v2:
>>> 1. register adev->lock_key into lockdep, otherwise lockdep will
>>> report the below warning
>>>
>>> [ 1216.705820] BUG: key ffff890183b647d0 has not been registered!
>>> [ 1216.705924] ------------[ cut here ]------------ [ 1216.705972]
>>> DEBUG_LOCKS_WARN_ON(1) [ 1216.705997] WARNING: CPU: 20 PID: 541 at
>>> kernel/locking/lockdep.c:3743 lockdep_init_map+0x150/0x210
>>>
>>> v3:
>>> change to use down_write_nest_lock to annotate the false dead-lock
>>> warning.
>>>
>>> Signed-off-by: Dennis Li <Dennis.Li@xxxxxxx>
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index 62ecac97fbd2..8a55b0bc044a 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -4145,12 +4145,15 @@ static int amdgpu_do_asic_reset(struct amdgpu_hive_info *hive,
>>> return r;
>>> }
>>>
>>> -static bool amdgpu_device_lock_adev(struct amdgpu_device *adev)
>>> +static bool amdgpu_device_lock_adev(struct amdgpu_device *adev,
>>> +struct amdgpu_hive_info *hive)
>>> {
>>> if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0)
>>> return false;
>>>
>>> - down_write(&adev->reset_sem);
>>> + if (hive) {
>>> + down_write_nest_lock(&adev->reset_sem, &hive->hive_lock);
>>> + } else
>>> + down_write(&adev->reset_sem);
>> Coding style nit pick: You should drop the {} here.
>>
>> Apart from that the patch is Reviewed-by: Christian König
>> <christian.koenig@xxxxxxx>
>>
>>>
>>> atomic_inc(&adev->gpu_reset_counter);
>>> switch (amdgpu_asic_reset_method(adev)) { @@ -4312,7 +4315,7 @@
>>> int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
>>>
>>> /* block all schedulers and reset given job's ring */
>>> list_for_each_entry(tmp_adev, device_list_handle, gmc.xgmi.head) {
>>> - if (!amdgpu_device_lock_adev(tmp_adev)) {
>>> + if (!amdgpu_device_lock_adev(tmp_adev, hive)) {
>>> DRM_INFO("Bailing on TDR for s_job:%llx, as another already in progress",
>>> job ? job->base.id : -1);
>>> r = 0;
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Attachment:
0001-locking-rwsem-remove-redundant-semicolon-of-down_wri.patch
Description: 0001-locking-rwsem-remove-redundant-semicolon-of-down_wri.patch
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