Quoting Janusz Krzysztofik (2019-04-04 11:40:24) > 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@xxxxxxxxx> > > > > > > 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. Sure, but we must still follow all the steps before _unloading_ the module or else the user is left pointing into reused kernel memory. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
