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From:   Phillip Susi <phill@thesusis.net>
To:     Luben Tuikov <ltuikov89@gmail.com>,
        Alex Deucher <alexdeucher@gmail.com>
Cc:     Linux regressions mailing list <regressions@lists.linux.dev>,
        Christian =?utf-8?Q?K=C3=B6nig?= 
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        "amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
        dri-devel@lists.freedesktop.org,
        Alex Deucher <alexander.deucher@amd.com>,
        Christian =?utf-8?Q?K=C3=B6nig?= <christian.koenig@amd.com>,
        Danilo Krummrich <dakr@redhat.com>
Subject: Re: Radeon regression in 6.6 kernel
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Date:   Wed, 29 Nov 2023 15:24:06 -0500
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Luben Tuikov <ltuikov89@gmail.com> writes:

> I remember that the problem was really that amdgpu called drm_sched_entity_init(),
> in amdgpu_ttm_set_buffer_funcs_status() without actually having initialized the scheduler
> used therein. For instance, the code before commit b70438004a14f4, looked like this:
>

<snip>

> 		sched = &ring->sched;                             <-- LT: No one has initialized this scheduler
>	        r = drm_sched_entity_init(&adev->mman.entity,     <-- Oopses, now that sched->sched_rq is not

<snip>

> Before commit 56e449603f0ac5, amdgpu was getting away with this, because the sched->sched_rq
> was a static array.
>
> Ideally, amdgpu code would be fixed.

This sounds like an initilization problem that resulted in an OOPS at
boot time, but I don't remember seeing that.  I just get a failure on
system suspend.