linux-kernel - Re: [Bug][5.18-rc0] Between commits ed4643521e6a and 34af78c4e616, appears warning "WARNING: CPU: 31 PID: 51848 at drivers/dma-buf/dma-fence-array.c:191 dma_fence_array_create+0x101/0x120" and some games stopped working.

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Date:   Sat, 9 Apr 2022 16:27:17 +0200
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>,
        Christian König <christian.koenig@....com>
Cc:     thomas.hellstrom@...ux.intel.com,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        "Deucher, Alexander" <alexander.deucher@....com>, Ken.Xue@....com
Subject: Re: [Bug][5.18-rc0] Between commits ed4643521e6a and 34af78c4e616,
 appears warning "WARNING: CPU: 31 PID: 51848 at
 drivers/dma-buf/dma-fence-array.c:191 dma_fence_array_create+0x101/0x120" and
 some games stopped working.

Am 08.04.22 um 19:25 schrieb Mikhail Gavrilov:
> On Fri, 8 Apr 2022 at 19:27, Christian König <christian.koenig@....com> wrote:
>> Please test the attached patch, it just re-introduce the lock without
>> doing much else.
>>
>> And does your branch contain the following patch:
>>
>> commit d18b8eadd83e3d8d63a45f9479478640dbcfca02
>> Author: Christian König <christian.koenig@....com>
>> Date:   Wed Feb 23 14:35:31 2022 +0100
>>
>>       drm/amdgpu: install ctx entities with cmpxchg
>>
>>       Since we removed the context lock we need to make sure that not two
>> threads
>>       are trying to install an entity at the same time.
>>
>>       Signed-off-by: Christian König <christian.koenig@....com>
>>       Fixes: 461fa7b0ac565e ("drm/amdgpu: remove ctx->lock")
>>       Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@....com>
>>       Signed-off-by: Alex Deucher <alexander.deucher@....com>
> The all listed games are now working with an attached patch.
> Also flood messages "WARNING: CPU: 31 PID: 51848 at
> drivers/dma-buf/dma-fence-array.c:191
> dma_fence_array_create+0x101/0x120" has gone.

That's unfortunately not the end of the story.

This is fixing your problem, but reintroducing the original problem that 
we call the syncobj with a lock held which can crash badly as well.

Going to take a closer look on Monday. I hope you can test a few more 
patches to help narrow down what's actually going wrong here.

Thanks,
Christian.

>
> Thanks.
>
> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
>