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

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Message-ID: <1818300.2E6qEfYBKl@jkrzyszt-desk.ger.corp.intel.com>
Date:   Mon, 20 May 2019 12:58:21 +0200
From:   Janusz Krzysztofik <janusz.krzysztofik@...ux.intel.com>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     intel-gfx@...ts.freedesktop.org, 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>
Subject: Re: [RFC PATCH] drm/i915: Tolerate file owned GEM contexts on hot unbind

On Friday, May 17, 2019 4:32:35 PM CEST Chris Wilson wrote:
> 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

Thanks Chris, I think I get it finally.

Janusz