From: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com> To: Chris Wilson <chris@chris-wilson.co.uk> Cc: David Airlie <airlied@linux.ie>, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com> Subject: Re: [Intel-gfx] [PATCH] drm/i915: Fix context IDs not released on driver hot unbind Date: Thu, 04 Apr 2019 12:40:24 +0200 [thread overview] Message-ID: <c1a857b241020a44c070cfc6b57adb6e6aba00be.camel@linux.intel.com> (raw) In-Reply-To: <155437373474.7532.10868620123516507965@skylake-alporthouse-com> On Thu, 2019-04-04 at 11:28 +0100, Chris Wilson wrote: > Quoting Janusz Krzysztofik (2019-04-04 11:24:45) > > From: Janusz Krzysztofik <janusz.krzysztofik@intel.com> > > > > In case the driver gets unbound while a device is open, kernel > > panic > > may be forced if a list of allocated context IDs is not empty. > > > > When a device is open, the list may happen to be not empty because > > a > > context ID, once allocated by a context ID allocator to a context > > assosiated with that open file descriptor, is released as late as > > on device close. > > > > On the other hand, there is a need to release all allocated context > > IDs > > and destroy the context ID allocator on driver unbind, even if a > > device > > is open, in order to free memory resources consumed and prevent > > from > > memory leaks. The purpose of the forced kernel panic was to > > protect > > the context ID allocator from being silently destroyed if not all > > allocated IDs had been released. > > Those open fd are still pointing into kernel memory where the driver > used to be. The panic is entirely correct, we should not be unloading > the module before those dangling pointers have been made safe. > > This is papering over the symptom. How is the module being unloaded > with > open fd? A user can play with the driver unbind or device remove sysfs interface. Thanks, Janusz > If all the fd have been closed, how have we failed to flush and > retire all requests (thereby unpinning the contexts and all other > pointers). > -Chris > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
WARNING: multiple messages have this Message-ID (diff)
From: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com> To: Chris Wilson <chris@chris-wilson.co.uk> Cc: David Airlie <airlied@linux.ie>, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Rodrigo Vivi <rodrigo.vivi@intel.com> Subject: Re: [Intel-gfx] [PATCH] drm/i915: Fix context IDs not released on driver hot unbind Date: Thu, 04 Apr 2019 12:40:24 +0200 [thread overview] Message-ID: <c1a857b241020a44c070cfc6b57adb6e6aba00be.camel@linux.intel.com> (raw) In-Reply-To: <155437373474.7532.10868620123516507965@skylake-alporthouse-com> On Thu, 2019-04-04 at 11:28 +0100, Chris Wilson wrote: > Quoting Janusz Krzysztofik (2019-04-04 11:24:45) > > From: Janusz Krzysztofik <janusz.krzysztofik@intel.com> > > > > In case the driver gets unbound while a device is open, kernel > > panic > > may be forced if a list of allocated context IDs is not empty. > > > > When a device is open, the list may happen to be not empty because > > a > > context ID, once allocated by a context ID allocator to a context > > assosiated with that open file descriptor, is released as late as > > on device close. > > > > On the other hand, there is a need to release all allocated context > > IDs > > and destroy the context ID allocator on driver unbind, even if a > > device > > is open, in order to free memory resources consumed and prevent > > from > > memory leaks. The purpose of the forced kernel panic was to > > protect > > the context ID allocator from being silently destroyed if not all > > allocated IDs had been released. > > Those open fd are still pointing into kernel memory where the driver > used to be. The panic is entirely correct, we should not be unloading > the module before those dangling pointers have been made safe. > > This is papering over the symptom. How is the module being unloaded > with > open fd? A user can play with the driver unbind or device remove sysfs interface. Thanks, Janusz > If all the fd have been closed, how have we failed to flush and > retire all requests (thereby unpinning the contexts and all other > pointers). > -Chris > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-04-04 10:40 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-04 10:24 [PATCH] drm/i915: Fix context IDs not released on driver hot unbind Janusz Krzysztofik 2019-04-04 10:28 ` [Intel-gfx] " Chris Wilson 2019-04-04 10:28 ` Chris Wilson 2019-04-04 10:40 ` Janusz Krzysztofik [this message] 2019-04-04 10:40 ` [Intel-gfx] " Janusz Krzysztofik 2019-04-04 10:43 ` Chris Wilson 2019-04-04 10:43 ` Chris Wilson 2019-04-04 10:50 ` Janusz Krzysztofik 2019-04-04 10:53 ` Chris Wilson 2019-04-04 10:53 ` Chris Wilson 2019-04-04 13:47 ` Jani Nikula 2019-04-04 16:57 ` ✗ Fi.CI.BAT: failure for " Patchwork
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