Fix the situation when clear_bit() is called for page->private before
the page pointer is actually assigned.  While at it, remove work_busy()
check because it is costly and does not give 100% guarantee anyway.
Signed-off-by: NVitaly Wool <vitalywool@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: <Oleksiy.Avramchenko@sony.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>