memcg: move memcg reclaimable page into tail of inactive list

The rotate_reclaimable_page function moves just written out pages, which
the VM wanted to reclaim, to the end of the inactive list.  That way the
VM will find those pages first next time it needs to free memory.

This patch applies the rule in memcg.  It can help to prevent unnecessary
working page eviction of memcg.

Signed-off-by: Minchan Kim <[email protected]>
Acked-by: Balbir Singh <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

include/linux/memcontrol.h

@@ -62,6 +62,7 @@ extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
 					gfp_t gfp_mask);
 extern void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru);
 extern void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru);
+extern void mem_cgroup_rotate_reclaimable_page(struct page *page);
 extern void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru);
 extern void mem_cgroup_del_lru(struct page *page);
 extern void mem_cgroup_move_lists(struct page *page,
@@ -211,6 +212,11 @@ static inline void mem_cgroup_del_lru_list(struct page *page, int lru)
 	return ;
 }
 
+static inline inline void mem_cgroup_rotate_reclaimable_page(struct page *page)
+{
+	return ;
+}
+
 static inline void mem_cgroup_rotate_lru_list(struct page *page, int lru)
 {
 	return ;

mm/memcontrol.c

@@ -829,6 +829,32 @@ void mem_cgroup_del_lru(struct page *page)
 	mem_cgroup_del_lru_list(page, page_lru(page));
 }
 
+/*
+ * Writeback is about to end against a page which has been marked for immediate
+ * reclaim.  If it still appears to be reclaimable, move it to the tail of the
+ * inactive list.
+ */
+void mem_cgroup_rotate_reclaimable_page(struct page *page)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct page_cgroup *pc;
+	enum lru_list lru = page_lru(page);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	pc = lookup_page_cgroup(page);
+	/* unused or root page is not rotated. */
+	if (!PageCgroupUsed(pc))
+		return;
+	/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
+	smp_rmb();
+	if (mem_cgroup_is_root(pc->mem_cgroup))
+		return;
+	mz = page_cgroup_zoneinfo(pc);
+	list_move_tail(&pc->lru, &mz->lists[lru]);
+}
+
 void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
 {
 	struct mem_cgroup_per_zone *mz;

mm/swap.c

@@ -200,8 +200,9 @@ static void pagevec_move_tail(struct pagevec *pvec)
 			spin_lock(&zone->lru_lock);
 		}
 		if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
-			int lru = page_lru_base_type(page);
+			enum lru_list lru = page_lru_base_type(page);
 			list_move_tail(&page->lru, &zone->lru[lru].list);
+			mem_cgroup_rotate_reclaimable_page(page);
 			pgmoved++;
 		}
 	}