linux-kernel - [PATCH 01/11] mm: page_alloc: handle MIGRATE_ISOLATE in free_pcppages

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Date:	Fri, 18 Nov 2011 17:43:08 +0100
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-media@...r.kernel.org, linux-mm@...ck.org,
	linaro-mm-sig@...ts.linaro.org
Cc:	Michal Nazarewicz <mina86@...a86.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Ankita Garg <ankita@...ibm.com>,
	Daniel Walker <dwalker@...eaurora.org>,
	Mel Gorman <mel@....ul.ie>, Arnd Bergmann <arnd@...db.de>,
	Jesse Barker <jesse.barker@...aro.org>,
	Jonathan Corbet <corbet@....net>,
	Shariq Hasnain <shariq.hasnain@...aro.org>,
	Chunsang Jeong <chunsang.jeong@...aro.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: [PATCH 01/11] mm: page_alloc: handle MIGRATE_ISOLATE in
 free_pcppages_bulk()

From: Michal Nazarewicz <mina86@...a86.com>

If page is on PCP list while pageblock it belongs to gets isolated,
the page's private still holds the old migrate type.  This means
that free_pcppages_bulk() will put the page on a freelist of the
old migrate type instead of MIGRATE_ISOLATE.

This commit changes that by explicitly checking whether page's
pageblock's migrate type is MIGRATE_ISOLATE and if it is, overwrites
page's private data.

Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
 mm/page_alloc.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9dd443d..58d1a2e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -628,6 +628,18 @@ 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);
+
+			/*
+			 * When page is isolated in set_migratetype_isolate()
+			 * function it's page_private is not changed since the
+			 * function has no way of knowing if it can touch it.
+			 * This means that when a page is on PCP list, it's
+			 * page_private no longer matches the desired migrate
+			 * type.
+			 */
+			if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
+				set_page_private(page, MIGRATE_ISOLATE);
+
 			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
 			__free_one_page(page, zone, 0, page_private(page));
 			trace_mm_page_pcpu_drain(page, 0, page_private(page));
-- 
1.7.1.569.g6f426

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