[PATCH v2] mm/memcontrol:rewrite mem_cgroup_page_lruvec()

[Hui Su <sh_def@163.com>]

mem_cgroup_page_lruvec() in memcontrol.c and
mem_cgroup_lruvec() in memcontrol.h is very similar
except for the param(page and memcg) which also can be
convert to each other.

So rewrite mem_cgroup_page_lruvec() with mem_cgroup_lruvec().

v1->v2:
use page_memcg() instead of 'page->mem_cgroup'.

Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Hui Su <sh_def@163.com>
---
 include/linux/memcontrol.h | 16 +++++++++++++--
 mm/memcontrol.c            | 40 --------------------------------------
 2 files changed, 14 insertions(+), 42 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e391e3c56de5..727af7c74e91 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -457,9 +457,10 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
 /**
  * mem_cgroup_lruvec - get the lru list vector for a memcg & node
  * @memcg: memcg of the wanted lruvec
+ * @pgdat: pglist_data
  *
  * Returns the lru list vector holding pages for a given @memcg &
- * @node combination. This can be the node lruvec, if the memory
+ * @pgdat combination. This can be the node lruvec, if the memory
  * controller is disabled.
  */
 static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
@@ -489,7 +490,18 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
 	return lruvec;
 }
 
-struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *);
+/**
+ * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
+ * @page: the page
+ * @pgdat: pgdat of the page
+ *
+ * This function relies on page->mem_cgroup being stable.
+ */
+static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
+						struct pglist_data *pgdat)
+{
+	return mem_cgroup_lruvec(page_memcg(page), pgdat);
+}
 
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3dcbf24d2227..9d4e1150b194 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1330,46 +1330,6 @@ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
 	return ret;
 }
 
-/**
- * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
- * @page: the page
- * @pgdat: pgdat of the page
- *
- * This function relies on page->mem_cgroup being stable - see the
- * access rules in commit_charge().
- */
-struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat)
-{
-	struct mem_cgroup_per_node *mz;
-	struct mem_cgroup *memcg;
-	struct lruvec *lruvec;
-
-	if (mem_cgroup_disabled()) {
-		lruvec = &pgdat->__lruvec;
-		goto out;
-	}
-
-	memcg = page->mem_cgroup;
-	/*
-	 * Swapcache readahead pages are added to the LRU - and
-	 * possibly migrated - before they are charged.
-	 */
-	if (!memcg)
-		memcg = root_mem_cgroup;
-
-	mz = mem_cgroup_page_nodeinfo(memcg, page);
-	lruvec = &mz->lruvec;
-out:
-	/*
-	 * Since a node can be onlined after the mem_cgroup was created,
-	 * we have to be prepared to initialize lruvec->zone here;
-	 * and if offlined then reonlined, we need to reinitialize it.
-	 */
-	if (unlikely(lruvec->pgdat != pgdat))
-		lruvec->pgdat = pgdat;
-	return lruvec;
-}
-
 /**
  * mem_cgroup_update_lru_size - account for adding or removing an lru page
  * @lruvec: mem_cgroup per zone lru vector
-- 
2.29.0