mm: migration: share the anon_vma ref counts between KSM and page migration

For clarity of review, KSM and page migration have separate refcounts on
the anon_vma.  While clear, this is a waste of memory.  This patch gets
KSM and page migration to share their toys in a spirit of harmony.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 956880f2ff49..6c3e99b4ae7c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -318,14 +318,14 @@ static void hold_anon_vma(struct rmap_item *rmap_item,
                           struct anon_vma *anon_vma)
 {
         rmap_item->anon_vma = anon_vma;
-        atomic_inc(&anon_vma->ksm_refcount);
+        atomic_inc(&anon_vma->external_refcount);
 }
 
 static void drop_anon_vma(struct rmap_item *rmap_item)
 {
         struct anon_vma *anon_vma = rmap_item->anon_vma;
 
-        if (atomic_dec_and_lock(&anon_vma->ksm_refcount, &anon_vma->lock)) {
+        if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) {
                 int empty = list_empty(&anon_vma->head);
                 spin_unlock(&anon_vma->lock);
                 if (empty)