mm/memcontrol:rewrite mem_cgroup_page_lruvec()

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().

[[email protected]: add missed warning in mem_cgroup_lruvec]
  Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: warn on missing memcg on mem_cgroup_page_lruvec()]
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/20201108143731.GA74138@rlk
Signed-off-by: Hui Su <[email protected]>
Signed-off-by: Alex Shi <[email protected]>
Signed-off-by: Lorenzo Stoakes <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Yafang Shao <[email protected]>
Cc: Chris Down <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 17 insertions, 2 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 196441f5dc99..d827bd7f3bfe 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -620,9 +620,10 @@ 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,
@@ -652,7 +653,21 @@ out:
 	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)
+{
+	struct mem_cgroup *memcg = page_memcg(page);
+
+	VM_WARN_ON_ONCE_PAGE(!memcg, page);
+	return mem_cgroup_lruvec(memcg, pgdat);
+}
 
 static inline bool lruvec_holds_page_lru_lock(struct page *page,
 					      struct lruvec *lruvec)