Hey, Op 29-07-12 22:15, Marcin Slusarz schreef: > On Thu, Jul 26, 2012 at 02:56:22PM +0200, Ortwin Glück wrote: >> On 25.07.2012 20:42, Marcin Slusarz wrote: >>> Good, below patch should fix this panic. >>> >>> Note that you can hit an oops in drm_handle_vblank because patch from >>> http://lists.freedesktop.org/archives/dri-devel/2012-May/023498.html >>> has not been applied (yet?). >> After applying your patch, it still crashes, although with a slightly >> different stack trace. I then also applied the second patch, but that >> doesn't make any difference. New log attached. >> >> Looks like interrupt occurs before nouveau_software_context_new() is >> called? Shouldn't the initialization be done from >> nouveau_irq_preinstall() so it is available when the irq occurs? Again, >> I am not an expert here. Just guessing... > No, the real problem is: with "noaccel" we don't register "software engine", > but vblank ISR relies on its existance and happily derefences NULL pointer. > > Now, this patch should fix it for real... > > --- > From: Marcin Slusarz <marcin.slus...@gmail.com> > Subject: [PATCH] drm/nouveau: disable vblank interrupts before registering > PDISPLAY ISR > > Currently, we register vblank IRQ handler and later we disable vblank > interrupts. So, for the short amount of time, we rely on vblank ISR > to operate correctly, even if vblank interrupts are never going to be > used later. > > In "noaccel" case, software engine - which is used by vblank ISR - is not > registered, so if vblank interrupt triggers in a wrong moment, we can hit > NULL pointer dereference in nouveau_software_vblank. > > To fix it, disable vblank interrupts before registering PDISPLAY ISR. > > Reported-by: Ortwin Glück <o...@odi.ch> > Signed-off-by: Marcin Slusarz <marcin.slus...@gmail.com> > Cc: sta...@vger.kernel.org [3.5] > I can confirm this bug when I was working on adding d0 vblank, but it seems to me like nv*_display_create would be a more logical place to put the disable call. This will make it more clear that vblank is disabled before the irq is registered.
Also maybe add a WARN_ON(!nv_engine(dev, NVOBJ_ENGINE_SW)); in nouveau_vblank_enable and/or return -EINVAL in that case? If you add the modification to nouveau_vblank_enable: Reviewed-by: Maarten Lankhorst <maarten.lankho...@canonical.com> ~Maarten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
