linux-kernel - Re: Non-robust apps and resets (was Re: [PATCH v5 1/1] drm/doc: Document DRM device reset expectations)

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Message-ID: <a9f88c90-5777-02b0-09b1-26979432b3bc@mailbox.org>
Date:   Wed, 2 Aug 2023 10:34:26 +0200
From:   Michel Dänzer <michel.daenzer@...lbox.org>
To:     Marek Olšák <maraeo@...il.com>
Cc:     pierre-eric.pelloux-prayer@....com,
        Samuel Pitoiset <samuel.pitoiset@...il.com>,
        André Almeida <andrealmeid@...lia.com>,
        Timur Kristóf <timur.kristof@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        Pekka Paalanen <ppaalanen@...il.com>,
        dri-devel@...ts.freedesktop.org, kernel-dev@...lia.com,
        alexander.deucher@....com,
        Pekka Paalanen <pekka.paalanen@...labora.com>,
        christian.koenig@....com
Subject: Re: Non-robust apps and resets (was Re: [PATCH v5 1/1] drm/doc:
 Document DRM device reset expectations)

On 8/2/23 09:38, Marek Olšák wrote:
> 
> The precedent from the CPU land is pretty strong here. There is
> SIGSEGV for invalid CPU memory access and SIGILL for invalid CPU
> instructions, yet we do nothing for invalid GPU memory access and
> invalid GPU instructions. Sending a terminating signal from the kernel
> would be the most natural thing to do.

After an unhandled SIGSEGV or SIGILL, the process is in an inconsistent state and cannot safely continue executing. That's why the process is terminated by default in those cases.

The same is not true when an OpenGL context stops working. Any threads / other parts of the process not using that OpenGL context continue working normally. And any attempts to use that OpenGL context can be safely ignored (or the OpenGL implementation couldn't support the robustness extensions).


-- 
Earthling Michel Dänzer            |                  https://redhat.com
Libre software enthusiast          |         Mesa and Xwayland developer