Please add this patch to stable 4.9 It exists in 4.14 and it is not applicable for earlier versions.
------------------------ commit c73322d098e4b6f5f0f0fa1330bf57e218775539 Author: Johannes Weiner hannes@cmpxchg.org Date: Wed May 3 14:51:51 2017 -0700
mm: fix 100% CPU kswapd busyloop on unreclaimable nodes -------------------------