mm: update_lru_size do the __mod_zone_page_state

Konstantin Khlebnikov pointed out (nearly four years ago, when lumpy
reclaim was removed) that lru_size can be updated by -nr_taken once per
call to isolate_lru_pages(), instead of page by page.

Update it inside isolate_lru_pages(), or at its two callsites? I chose
to update it at the callsites, rearranging and grouping the updates by
nr_taken and nr_scanned together in both.

With one exception, mem_cgroup_update_lru_size(,lru,) is then used where
__mod_zone_page_state(,NR_LRU_BASE+lru,) is used; and we shall be adding
some more calls in a future commit.  Make the code a little smaller and
simpler by incorporating stat update in lru_size update.

The exception was move_active_pages_to_lru(), which aggregated the
pgmoved stat update separately from the individual lru_size updates; but
I still think this a simplification worth making.

However, the __mod_zone_page_state is not peculiar to mem_cgroups: so
better use the name update_lru_size, calls mem_cgroup_update_lru_size
when CONFIG_MEMCG.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 18 insertions, 12 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1191d79aa495..94da96738df3 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -658,12 +658,6 @@ mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
 	return 0;
 }
 
-static inline void
-mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
-			      int increment)
-{
-}
-
 static inline unsigned long
 mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
 			     int nid, unsigned int lru_mask)
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index d8cea81ab1ac..5bd29ba4f174 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -22,22 +22,34 @@ static inline int page_is_file_cache(struct page *page)
 	return !PageSwapBacked(page);
 }
 
+static __always_inline void __update_lru_size(struct lruvec *lruvec,
+				enum lru_list lru, int nr_pages)
+{
+	__mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, nr_pages);
+}
+
+static __always_inline void update_lru_size(struct lruvec *lruvec,
+				enum lru_list lru, int nr_pages)
+{
+#ifdef CONFIG_MEMCG
+	mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+#else
+	__update_lru_size(lruvec, lru, nr_pages);
+#endif
+}
+
 static __always_inline void add_page_to_lru_list(struct page *page,
 				struct lruvec *lruvec, enum lru_list lru)
 {
-	int nr_pages = hpage_nr_pages(page);
-	mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+	update_lru_size(lruvec, lru, hpage_nr_pages(page));
 	list_add(&page->lru, &lruvec->lists[lru]);
-	__mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, nr_pages);
 }
 
 static __always_inline void del_page_from_lru_list(struct page *page,
 				struct lruvec *lruvec, enum lru_list lru)
 {
-	int nr_pages = hpage_nr_pages(page);
 	list_del(&page->lru);
-	mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
-	__mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, -nr_pages);
+	update_lru_size(lruvec, lru, -hpage_nr_pages(page));
 }
 
 /**