Re: [PATCH] drm/radeon: add a force flush to delay work when radeon

[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.

In which situation, there would lead to a deadlock?

> 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@xxxxxxxxxx>
> > ---
> >   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);
> >           }
> >       }