1. 09 Feb, 2017 11 commits
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  3. 03 Feb, 2017 14 commits
  4. 30 Jan, 2017 12 commits
  5. 29 Jan, 2017 2 commits
    • Linus Torvalds's avatar
      Linux 4.10-rc6 · 566cf877
      Linus Torvalds authored
      566cf877
    • Linus Torvalds's avatar
      drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj() · 39cb2c9a
      Linus Torvalds authored
      I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
      call in intel_unpin_fb_obj() returns NULL, resulting in an oops
      immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
      tries to dereference it.
      
      It seems to be some race condition where the object is going away at
      shutdown time, since both times happened when shutting down the X
      server.  The call chains were different:
      
       - VT ioctl(KDSETMODE, KD_TEXT):
      
          intel_cleanup_plane_fb+0x5b/0xa0 [i915]
          drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
          intel_atomic_commit_tail+0x749/0xfe0 [i915]
          intel_atomic_commit+0x3cb/0x4f0 [i915]
          drm_atomic_commit+0x4b/0x50 [drm]
          restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
          drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
          drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
          intel_fbdev_set_par+0x18/0x70 [i915]
          fb_set_var+0x236/0x460
          fbcon_blank+0x30f/0x350
          do_unblank_screen+0xd2/0x1a0
          vt_ioctl+0x507/0x12a0
          tty_ioctl+0x355/0xc30
          do_vfs_ioctl+0xa3/0x5e0
          SyS_ioctl+0x79/0x90
          entry_SYSCALL_64_fastpath+0x13/0x94
      
       - i915 unpin_work workqueue:
      
          intel_unpin_work_fn+0x58/0x140 [i915]
          process_one_work+0x1f1/0x480
          worker_thread+0x48/0x4d0
          kthread+0x101/0x140
      
      and this patch purely papers over the issue by adding a NULL pointer
      check and a WARN_ON_ONCE() to avoid the oops that would then generally
      make the machine unresponsive.
      
      Other callers of i915_gem_object_to_ggtt() seem to also check for the
      returned pointer being NULL and warn about it, so this clearly has
      happened before in other places.
      
      [ Reported it originally to the i915 developers on Jan 8, applying the
        ugly workaround on my own now after triggering the problem for the
        second time with no feedback.
      
        This is likely to be the same bug reported as
      
           https://bugs.freedesktop.org/show_bug.cgi?id=98829
           https://bugs.freedesktop.org/show_bug.cgi?id=99134
      
        which has a patch for the underlying problem, but it hasn't gotten to
        me, so I'm applying the workaround. ]
      
      Cc: Daniel Vetter <daniel.vetter@intel.com>
      Cc: Jani Nikula <jani.nikula@linux.intel.com>
      Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
      Cc: Imre Deak <imre.deak@intel.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      39cb2c9a