linux-kernel - Re: [RFC PATCH] drm/i915: Tolerate file owned GEM contexts on hot unbind

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Date:   Fri, 17 May 2019 15:32:35 +0100
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Janusz Krzysztofik <janusz.krzysztofik@...ux.intel.com>,
        intel-gfx@...ts.freedesktop.org
Cc:     Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Michal Wajdeczko <michal.wajdeczko@...el.com>,
        Janusz Krzysztofik <janusz.krzysztofik@...el.com>
Subject: Re: [RFC PATCH] drm/i915: Tolerate file owned GEM contexts on hot unbind

Quoting Janusz Krzysztofik (2019-05-17 15:06:17)
> From: Janusz Krzysztofik <janusz.krzysztofik@...el.com>
> 
> During i915_driver_unload(), GEM contexts are verified restrictively
> inside i915_gem_fini() if they don't consume shared resources which
> should be cleaned up before the driver is released.  If those checks
> don't result in kernel panic, one more check is performed at the end of
> i915_gem_fini() which issues a WARN_ON() if GEM contexts still exist.

Just fix the underlying bug of this code being called too early. The
assumptions we made for unload are clearly invalid when applied to
unbind, and we need to split the phases.
-Chris