linux-kernel - Re: Radeon regression in 6.6 kernel

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Message-ID: <db75bcf5-13a7-4176-a2fb-94cd198a1a7b@gmail.com>
Date:   Wed, 29 Nov 2023 22:47:44 -0500
From:   Luben Tuikov <ltuikov89@...il.com>
To:     Alex Deucher <alexdeucher@...il.com>
Cc:     Phillip Susi <phill@...susis.net>,
        Linux regressions mailing list <regressions@...ts.linux.dev>,
        Christian König <ckoenig.leichtzumerken@...il.com>,
        linux-kernel@...r.kernel.org,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        dri-devel@...ts.freedesktop.org,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        Danilo Krummrich <dakr@...hat.com>
Subject: Re: Radeon regression in 6.6 kernel

On 2023-11-29 22:36, Luben Tuikov wrote:
> On 2023-11-29 15:49, Alex Deucher wrote:
>> On Wed, Nov 29, 2023 at 3:10 PM Alex Deucher <alexdeucher@...il.com> wrote:
>>>
>>> Actually I think I see the problem.  I'll try and send out a patch
>>> later today to test.
>>
>> Does the attached patch fix it?
> 
> Thanks for the patch, Alex.
> 
> Is it possible for AMD to also reproduce this issue and test this patch on a Navi23 system?
> 
>> From 96e75b5218f7a124eafa53853681eef8fe567ab8 Mon Sep 17 00:00:00 2001
>> From: Alex Deucher <alexander.deucher@....com>
>> Date: Wed, 29 Nov 2023 15:44:25 -0500
>> Subject: [PATCH] drm/amdgpu: fix buffer funcs setting order on suspend
>>
>> We need to make disable this after the last eviction
> 
> "make disable" --> "disable"
> 
>> call, but before we disable the SDMA IP.
>>
>> Fixes: b70438004a14 ("drm/amdgpu: move buffer funcs setting up a level")
>> Link: https://lists.freedesktop.org/archives/amd-gfx/2023-November/101197.html
> 
> Link: https://lore.kernel.org/r/87edgv4x3i.fsf@vps.thesusis.net
> 
> Let's link the start of the thread.
> 
> Regards,
> Luben
> 
>> Signed-off-by: Alex Deucher <alexander.deucher@....com>
>> Cc: Phillip Susi <phill@...susis.net>
>> Cc: Luben Tuikov <ltuikov89@...il.com>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> index b5edf40b5d03..78553e027db4 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> @@ -4531,8 +4531,6 @@ int amdgpu_device_suspend(struct drm_device *dev, bool fbcon)
>>  
>>  	amdgpu_ras_suspend(adev);
>>  
>> -	amdgpu_ttm_set_buffer_funcs_status(adev, false);
>> -
>>  	amdgpu_device_ip_suspend_phase1(adev);
>>  
>>  	if (!adev->in_s0ix)
>> @@ -4542,6 +4540,8 @@ int amdgpu_device_suspend(struct drm_device *dev, bool fbcon)
>>  	if (r)
>>  		return r;
>>  
>> +	amdgpu_ttm_set_buffer_funcs_status(adev, false);
>> +

If you're moving this past phase 1, there's another instance in amdgpu_device_ip_suspend(),
which may need to be moved down.

Regards,
Luben

>>  	amdgpu_fence_driver_hw_fini(adev);
>>  
>>  	amdgpu_device_ip_suspend_phase2(adev);
> 
>>
>> Alex
>>
>>>
>>> Alex
>>>
>>> On Wed, Nov 29, 2023 at 1:52 PM Alex Deucher <alexdeucher@...il.com> wrote:
>>>>
>>>> On Wed, Nov 29, 2023 at 11:41 AM Luben Tuikov <ltuikov89@...il.com> wrote:
>>>>>
>>>>> On 2023-11-29 10:22, Alex Deucher wrote:
>>>>>> On Wed, Nov 29, 2023 at 8:50 AM Alex Deucher <alexdeucher@...il.com> wrote:
>>>>>>>
>>>>>>> On Tue, Nov 28, 2023 at 11:45 PM Luben Tuikov <ltuikov89@...il.com> wrote:
>>>>>>>>
>>>>>>>> On 2023-11-28 17:13, Alex Deucher wrote:
>>>>>>>>> On Mon, Nov 27, 2023 at 6:24 PM Phillip Susi <phill@...susis.net> wrote:
>>>>>>>>>>
>>>>>>>>>> Alex Deucher <alexdeucher@...il.com> writes:
>>>>>>>>>>
>>>>>>>>>>>> In that case those are the already known problems with the scheduler
>>>>>>>>>>>> changes, aren't they?
>>>>>>>>>>>
>>>>>>>>>>> Yes.  Those changes went into 6.7 though, not 6.6 AFAIK.  Maybe I'm
>>>>>>>>>>> misunderstanding what the original report was actually testing.  If it
>>>>>>>>>>> was 6.7, then try reverting:
>>>>>>>>>>> 56e449603f0ac580700621a356d35d5716a62ce5
>>>>>>>>>>> b70438004a14f4d0f9890b3297cd66248728546c
>>>>>>>>>>
>>>>>>>>>> At some point it was suggested that I file a gitlab issue, but I took
>>>>>>>>>> this to mean it was already known and being worked on.  -rc3 came out
>>>>>>>>>> today and still has the problem.  Is there a known issue I could track?
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> At this point, unless there are any objections, I think we should just
>>>>>>>>> revert the two patches
>>>>>>>> Uhm, no.
>>>>>>>>
>>>>>>>> Why "the two" patches?
>>>>>>>>
>>>>>>>> This email, part of this thread,
>>>>>>>>
>>>>>>>> https://lore.kernel.org/all/87r0kircdo.fsf@vps.thesusis.net/
>>>>>>>>
>>>>>>>> clearly states that reverting *only* this commit,
>>>>>>>> 56e449603f0ac5 drm/sched: Convert the GPU scheduler to variable number of run-queues
>>>>>>>> *does not* mitigate the failed suspend. (Furthermore, this commit doesn't really change
>>>>>>>> anything operational, other than using an allocated array, instead of a static one, in DRM,
>>>>>>>> while the 2nd patch is solely contained within the amdgpu driver code.)
>>>>>>>>
>>>>>>>> Leaving us with only this change,
>>>>>>>> b70438004a14f4 drm/amdgpu: move buffer funcs setting up a level
>>>>>>>> to be at fault, as the kernel log attached in the linked email above shows.
>>>>>>>>
>>>>>>>> The conclusion is that only b70438004a14f4 needs reverting.
>>>>>>>
>>>>>>> b70438004a14f4 was a fix for 56e449603f0ac5.  Without b70438004a14f4,
>>>>>>> 56e449603f0ac5 breaks amdgpu.
>>>>>>
>>>>>> We can try and re-enable it in the next kernel.  I'm just not sure
>>>>>> we'll be able to fix this in time for 6.7 with the holidays and all
>>>>>> and I don't want to cause a lot of scheduler churn at the end of the
>>>>>> 6.7 cycle if we hold off and try and fix it.  Reverting seems like the
>>>>>> best short term solution.
>>>>>
>>>>> A lot of subsequent code has come in since commit 56e449603f0ac5, as it opened
>>>>> the opportunity for a 1-to-1 relationship between an entity and a scheduler.
>>>>> (Should've always been the case, from the outset. Not sure why it was coded as
>>>>> a fixed-size array.)
>>>>>
>>>>> Given that commit 56e449603f0ac5 has nothing to do with amdgpu, and the problem
>>>>> is wholly contained in amdgpu, and no other driver has this problem, there is
>>>>> no reason to have to "churn", i.e. go back and forth in DRM, only to cover up
>>>>> an init bug in amdgpu. See the response I just sent in @this thread:
>>>>> https://lore.kernel.org/r/05007cb0-871e-4dc7-af58-1351f4ba43e2@gmail.com
>>>>>
>>>>> And it's not like this issue is unknown. I first posted about it on 2023-10-16.
>>>>>
>>>>> Ideally, amdgpu would just fix their init code.
>>>>
>>>> You can't make changes to core code that break other drivers.
>>>> Arguably 56e449603f0ac5 should not have gone in in the first place if
>>>> it broke amdgpu.  b70438004a14f4 was the code to fix amdgpu's init
>>>> code, but as a side effect it seems to have broken suspend for some
>>>> users.
>>>>
>>>> Alex

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