Messages in this thread | | | Date | Wed, 17 Aug 2022 15:31:32 +0800 | Subject | Re: [PATCH] drm/radeon: add a force flush to delay work when radeon | From | 李真能 <> |
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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@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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