[PATCH] drm/radeon: add a force flush to delay work when radeon
李真能
lizhenneng at kylinos.cn
Wed Aug 17 07:31:32 UTC 2022
在 2022/8/15 21:12, Christian König 写道:
> Am 15.08.22 um 09:34 schrieb 李真能:
>>
>> 在 2022/8/12 18:55, Christian König 写道:
>>> Am 11.08.22 um 09:25 schrieb Zhenneng Li:
>>>> Although radeon card fence and wait for gpu to finish processing
>>>> current batch rings,
>>>> there is still a corner case that radeon lockup work queue may not
>>>> be fully flushed,
>>>> and meanwhile the radeon_suspend_kms() function has called
>>>> pci_set_power_state() to
>>>> put device in D3hot state.
>>>
>>> If I'm not completely mistaken the reset worker uses the
>>> suspend/resume functionality as well to get the hardware into a
>>> working state again.
>>>
>>> So if I'm not completely mistaken this here would lead to a
>>> deadlock, please double check that.
>>
>> We have tested many times, there are no deadlock.
>
> Testing doesn't tells you anything, you need to audit the call paths.
>
>> In which situation, there would lead to a deadlock?
>
> GPU resets.
Although flush_delayed_work(&rdev->fence_drv[i].lockup_work) will wait
for a lockup_work to finish executing the last queueing, but this
kernel func haven't get any lock, and lockup_work will run in another
kernel thread, so I think flush_delayed_work could not lead to a deadlock.
Therefor if radeon_gpu_reset is called in another thread when
radeon_suspend_kms is blocked on flush_delayed_work, there could not
lead to a deadlock.
>
> Regards,
> Christian.
>
>>
>>>
>>> Regards,
>>> Christian.
>>>
>>>> Per PCI spec rev 4.0 on 5.3.1.4.1 D3hot State.
>>>>> Configuration and Message requests are the only TLPs accepted by a
>>>>> Function in
>>>>> the D3hot state. All other received Requests must be handled as
>>>>> Unsupported Requests,
>>>>> and all received Completions may optionally be handled as
>>>>> Unexpected Completions.
>>>> This issue will happen in following logs:
>>>> Unable to handle kernel paging request at virtual address
>>>> 00008800e0008010
>>>> CPU 0 kworker/0:3(131): Oops 0
>>>> pc = [<ffffffff811bea5c>] ra = [<ffffffff81240844>] ps = 0000
>>>> Tainted: G W
>>>> pc is at si_gpu_check_soft_reset+0x3c/0x240
>>>> ra is at si_dma_is_lockup+0x34/0xd0
>>>> v0 = 0000000000000000 t0 = fff08800e0008010 t1 = 0000000000010000
>>>> t2 = 0000000000008010 t3 = fff00007e3c00000 t4 = fff00007e3c00258
>>>> t5 = 000000000000ffff t6 = 0000000000000001 t7 = fff00007ef078000
>>>> s0 = fff00007e3c016e8 s1 = fff00007e3c00000 s2 = fff00007e3c00018
>>>> s3 = fff00007e3c00000 s4 = fff00007fff59d80 s5 = 0000000000000000
>>>> s6 = fff00007ef07bd98
>>>> a0 = fff00007e3c00000 a1 = fff00007e3c016e8 a2 = 0000000000000008
>>>> a3 = 0000000000000001 a4 = 8f5c28f5c28f5c29 a5 = ffffffff810f4338
>>>> t8 = 0000000000000275 t9 = ffffffff809b66f8 t10 = ff6769c5d964b800
>>>> t11= 000000000000b886 pv = ffffffff811bea20 at = 0000000000000000
>>>> gp = ffffffff81d89690 sp = 00000000aa814126
>>>> Disabling lock debugging due to kernel taint
>>>> Trace:
>>>> [<ffffffff81240844>] si_dma_is_lockup+0x34/0xd0
>>>> [<ffffffff81119610>] radeon_fence_check_lockup+0xd0/0x290
>>>> [<ffffffff80977010>] process_one_work+0x280/0x550
>>>> [<ffffffff80977350>] worker_thread+0x70/0x7c0
>>>> [<ffffffff80977410>] worker_thread+0x130/0x7c0
>>>> [<ffffffff80982040>] kthread+0x200/0x210
>>>> [<ffffffff809772e0>] worker_thread+0x0/0x7c0
>>>> [<ffffffff80981f8c>] kthread+0x14c/0x210
>>>> [<ffffffff80911658>] ret_from_kernel_thread+0x18/0x20
>>>> [<ffffffff80981e40>] kthread+0x0/0x210
>>>> Code: ad3e0008 43f0074a ad7e0018 ad9e0020 8c3001e8 40230101
>>>> <88210000> 4821ed21
>>>> So force lockup work queue flush to fix this problem.
>>>>
>>>> Signed-off-by: Zhenneng Li <lizhenneng at kylinos.cn>
>>>> ---
>>>> drivers/gpu/drm/radeon/radeon_device.c | 3 +++
>>>> 1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/radeon/radeon_device.c
>>>> b/drivers/gpu/drm/radeon/radeon_device.c
>>>> index 15692cb241fc..e608ca26780a 100644
>>>> --- a/drivers/gpu/drm/radeon/radeon_device.c
>>>> +++ b/drivers/gpu/drm/radeon/radeon_device.c
>>>> @@ -1604,6 +1604,9 @@ int radeon_suspend_kms(struct drm_device
>>>> *dev, bool suspend,
>>>> if (r) {
>>>> /* delay GPU reset to resume */
>>>> radeon_fence_driver_force_completion(rdev, i);
>>>> + } else {
>>>> + /* finish executing delayed work */
>>>> + flush_delayed_work(&rdev->fence_drv[i].lockup_work);
>>>> }
>>>> }
>>>
>
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