[PATCH 03/10] mm/page_alloc: handle page on pcp correctly if it's pageblock is isolated

[Joonsoo Kim]

If pageblock of page on pcp are isolated now, we should free it to isolate
buddy list to prevent future allocation on it. But current code doesn't
do this.

Moreover, there is a freepage counting problem on current code. Although
pageblock of page on pcp are isolated now, it could go normal buddy list,
because get_onpcp_migratetype() will return non-isolate migratetype.
In this case, we should do either adding freepage count or changing
migratetype to MIGRATE_ISOLATE, but, current code do neither.

This patch fixes these two problems by handling pageblock migratetype
before calling __free_one_page(). And, if we find the page on isolated
pageblock, change migratetype to MIGRATE_ISOLATE to prevent future
allocation of this page and freepage counting problem.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
 mm/page_alloc.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index aeb51d1..99c05f7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -719,15 +719,17 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 			page = list_entry(list->prev, struct page, lru);
 			/* must delete as __free_one_page list manipulates */
 			list_del(&page->lru);
-			mt = get_freepage_migratetype(page);
+
+			if (unlikely(is_migrate_isolate_page(page))) {
+				mt = MIGRATE_ISOLATE;
+			} else {
+				mt = get_freepage_migratetype(page);
+				__mod_zone_freepage_state(zone, 1, mt);
+			}
+
 			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
 			__free_one_page(page, page_to_pfn(page), zone, 0, mt);
 			trace_mm_page_pcpu_drain(page, 0, mt);
-			if (likely(!is_migrate_isolate_page(page))) {
-				__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
-				if (is_migrate_cma(mt))
-					__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
-			}
 		} while (--to_free && --batch_free && !list_empty(list));
 	}
 	spin_unlock(&zone->lock);
-- 
1.7.9.5

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