Fix: update writeback instrumentation for kernel 4.14

Fix: update writeback instrumentation for kernel 4.14

See upstream commits:

  commit 11fb998986a72aa7e997d96d63d52582a01228c5
  Author: Mel Gorman <mgorman@techsingularity.net>
  Date:   Thu Jul 28 15:46:20 2016 -0700

    mm: move most file-based accounting to the node

    There are now a number of accounting oddities such as mapped file pages
    being accounted for on the node while the total number of file pages are
    accounted on the zone.  This can be coped with to some extent but it's
    confusing so this patch moves the relevant file-based accounted.  Due to
    throttling logic in the page allocator for reliable OOM detection, it is
    still necessary to track dirty and writeback pages on a per-zone basis.

  commit c4a25635b60d08853a3e4eaae3ab34419a36cfa2
  Author: Mel Gorman <mgorman@techsingularity.net>
  Date:   Thu Jul 28 15:46:23 2016 -0700

    mm: move vmscan writes and file write accounting to the node

    As reclaim is now node-based, it follows that page write activity due to
    page reclaim should also be accounted for on the node.  For consistency,
    also account page writes and page dirtying on a per-node basis.

    After this patch, there are a few remaining zone counters that may appear
    strange but are fine.  NUMA stats are still per-zone as this is a
    user-space interface that tools consume.  NR_MLOCK, NR_SLAB_*,
    NR_PAGETABLE, NR_KERNEL_STACK and NR_BOUNCE are all allocations that
    potentially pin low memory and cannot trivially be reclaimed on demand.
    This information is still useful for debugging a page allocation failure
    warning.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>