The zone's rotation statistics must not be accessed without the
corresponding LRU lock held.  Fix an unprotected write in
shrink_active_list().
Acked-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NJohannes Weiner <hannes@saeurebad.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>