[PATCH] mm: exclude isolated non-lru pages from NR_ISOLATED_ANON or NR_ISOLATED_FILE.

[ming.ling]

Non-lru pages don't belong to any lru, so accounting them to
NR_ISOLATED_ANON or NR_ISOLATED_FILE doesn't make any sense.
It may misguide functions such as pgdat_reclaimable_pages and
too_many_isolated.

This patch adds NR_ISOLATED_NONLRU to vmstat and moves isolated non-lru
pages from NR_ISOLATED_ANON or NR_ISOLATED_FILE to NR_ISOLATED_NONLRU.
And with non-lru pages in vmstat, it helps to optimize algorithm of
function too_many_isolated oneday.

Signed-off-by: ming.ling <ming.ling@xxxxxxxxxxxxxx>
---
 include/linux/mmzone.h |  1 +
 mm/compaction.c        | 12 +++++++++---
 mm/migrate.c           | 14 ++++++++++----
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7f2ae99..dc0adba 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -169,6 +169,7 @@ enum node_stat_item {
 	NR_VMSCAN_IMMEDIATE,	/* Prioritise for reclaim when writeback ends */
 	NR_DIRTIED,		/* page dirtyings since bootup */
 	NR_WRITTEN,		/* page writings since bootup */
+	NR_ISOLATED_NONLRU,	/* Temporary isolated pages from non-lru */
 	NR_VM_NODE_STAT_ITEMS
 };
 
diff --git a/mm/compaction.c b/mm/compaction.c
index 9affb29..8da1dca 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -638,16 +638,21 @@ isolate_freepages_range(struct compact_control *cc,
 static void acct_isolated(struct zone *zone, struct compact_control *cc)
 {
 	struct page *page;
-	unsigned int count[2] = { 0, };
+	unsigned int count[3] = { 0, };
 
 	if (list_empty(&cc->migratepages))
 		return;
 
-	list_for_each_entry(page, &cc->migratepages, lru)
-		count[!!page_is_file_cache(page)]++;
+	list_for_each_entry(page, &cc->migratepages, lru) {
+		if (PageLRU(page))
+			count[!!page_is_file_cache(page)]++;
+		else
+			count[2]++;
+	}
 
 	mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON, count[0]);
 	mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, count[1]);
+	mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_NONLRU, count[2]);
 }
 
 /* Similar to reclaim, but different enough that they don't share logic */
@@ -659,6 +664,7 @@ static bool too_many_isolated(struct zone *zone)
 			node_page_state(zone->zone_pgdat, NR_INACTIVE_ANON);
 	active = node_page_state(zone->zone_pgdat, NR_ACTIVE_FILE) +
 			node_page_state(zone->zone_pgdat, NR_ACTIVE_ANON);
+	/* Is it necessary to add NR_ISOLATED_NONLRU?? */
 	isolated = node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE) +
 			node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON);
 
diff --git a/mm/migrate.c b/mm/migrate.c
index f7ee04a..cd5abb2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -168,8 +168,11 @@ void putback_movable_pages(struct list_head *l)
 			continue;
 		}
 		list_del(&page->lru);
-		dec_node_page_state(page, NR_ISOLATED_ANON +
-				page_is_file_cache(page));
+		if (PageLRU(page))
+			dec_node_page_state(page, NR_ISOLATED_ANON +
+					page_is_file_cache(page));
+		else
+			dec_node_page_state(page, NR_ISOLATED_NONLRU);
 		/*
 		 * We isolated non-lru movable page so here we can use
 		 * __PageMovable because LRU page's mapping cannot have
@@ -1121,8 +1124,11 @@ out:
 		 * restored.
 		 */
 		list_del(&page->lru);
-		dec_node_page_state(page, NR_ISOLATED_ANON +
-				page_is_file_cache(page));
+		if (PageLRU(page))
+			dec_node_page_state(page, NR_ISOLATED_ANON +
+					page_is_file_cache(page));
+		else
+			dec_node_page_state(page, NR_ISOLATED_NONLRU);
 	}
 
 	/*
-- 
1.9.1