Test for pte_young before going to the costlier atomic test_and_clear, as
asm-generic does.  Test for pte_dirty before going to the costlier atomic
test_and_clear, as asm-generic does (I said before that I would not do so for
pte_dirty, but was missing the point: there is nothing atomic about deciding
to do nothing).  But I've not touched the rather different ppc and ppc64.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>