Messages in this thread | | | Date | Wed, 17 Aug 2022 13:40:32 +0200 | Subject | Re: [PATCH] drm/radeon: add a force flush to delay work when radeon | From | Christian König <> |
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Am 17.08.22 um 09:31 schrieb 李真能: > > 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.
Ok sounds like you didn't go what I wanted to say.
The key problem is that radeon_gpu_reset() calls radeon_suspend() which in turn calls rdev->asic->suspend().
And this function in turn could end up in radeon_suspend_kms() again, but I'm not 100% sure about that.
Just double check the order of function called here (e.g. if radeon_suspend_kms() call radeon_suspend() or the other way around). Apart from that your patch looks correct to me as well.
Regards, Christian.
> >> >> 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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