This showed up in logs where people had a hung chip, so pinning was blocked
on the chip unpinning other buffers, and the X Server took its scheduler
signal during that time.
Signed-off-by: Eric Anholt <eric@anholt.net> Signed-off-by: Dave Airlie <airlied@linux.ie> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>