On Tue, 25 Oct 2016 10:09:30 +0200, Daniel Vetter wrote: > > On Tue, Oct 25, 2016 at 08:46:28AM +0200, Takashi Iwai wrote: > > On Fri, 21 Oct 2016 14:52:07 +0200, > > Ville Syrjälä wrote: > > > > > > On Thu, Oct 20, 2016 at 05:05:30PM +0200, Takashi Iwai wrote: > > > > Since 4.7 kernel, we've seen the error messages like > > > > > > > > kernel: [TTM] Buffer eviction failed > > > > kernel: qxl 0000:00:02.0: object_init failed for (4026540032, > > > > 0x00000001) > > > > kernel: [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate > > > > VRAM BO > > > > > > > > on QXL when switching and accessing on VT. The culprit was the > > > > generic deferred_io code (qxl driver switched to it since 4.7). > > > > There is a race between the dirty clip update and the call of > > > > callback. > > > > > > > > In drm_fb_helper_dirty(), the dirty clip is updated in the spinlock, > > > > while it kicks off the update worker outside the spinlock. Meanwhile > > > > the update worker clears the dirty clip in the spinlock, too. Thus, > > > > when drm_fb_helper_dirty() is called concurrently, schedule_work() is > > > > called after the clip is cleared in the first worker call. > > > > > > > > This patch addresses it by validating the clip before calling the > > > > dirty fb callback. > > > > > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98322 > > > > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1003298 > > > > Fixes: eaa434defaca ('drm/fb-helper: Add fb_deferred_io support') > > > > Cc: <stable at vger.kernel.org> > > > > Signed-off-by: Takashi Iwai <tiwai at suse.de> > > > > > > Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com> > > > > Daniel, could you pick this if it's OK as a quick fix? Currently > > qxl driver is utterly broken, and we should recover it ASAP. On top > > of this, we can put a more comprehensive fix covering both this and > > dirtyfb ioctl code paths. > > I thought I've pinged Dave already to pick up, I'll poke him again.
Thanks! Takashi
