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>
diff --git a/mm/ksm.c b/mm/ksm.c
index 956880f..6c3e99b 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -318,14 +318,14 @@
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)
diff --git a/mm/migrate.c b/mm/migrate.c
index b768a1d..42a3d24 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -601,7 +601,7 @@
rcu_read_lock();
rcu_locked = 1;
anon_vma = page_anon_vma(page);
- atomic_inc(&anon_vma->migrate_refcount);
+ atomic_inc(&anon_vma->external_refcount);
}
/*
@@ -643,7 +643,7 @@
rcu_unlock:
/* Drop an anon_vma reference if we took one */
- if (anon_vma && atomic_dec_and_lock(&anon_vma->migrate_refcount, &anon_vma->lock)) {
+ if (anon_vma && 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)
diff --git a/mm/rmap.c b/mm/rmap.c
index f522cb0..b5c320f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -250,8 +250,7 @@
list_del(&anon_vma_chain->same_anon_vma);
/* We must garbage collect the anon_vma if it's empty */
- empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma) &&
- !migrate_refcount(anon_vma);
+ empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma);
spin_unlock(&anon_vma->lock);
if (empty)
@@ -275,8 +274,7 @@
struct anon_vma *anon_vma = data;
spin_lock_init(&anon_vma->lock);
- ksm_refcount_init(anon_vma);
- migrate_refcount_init(anon_vma);
+ anonvma_external_refcount_init(anon_vma);
INIT_LIST_HEAD(&anon_vma->head);
}