linux-kernel - [PATCH v2 5/5] power: add zone range overlapping check

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Message-Id: <1459476406-28418-6-git-send-email-iamjoonsoo.kim@lge.com>
Date:	Fri,  1 Apr 2016 11:06:46 +0900
From:	js1304@...il.com
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Mel Gorman <mgorman@...e.de>,
	Laura Abbott <lauraa@...eaurora.org>,
	Minchan Kim <minchan@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v2 5/5] power: add zone range overlapping check

From: Joonsoo Kim <iamjoonsoo.kim@....com>

There is a system that node's pfn are overlapped like as following.

-----pfn-------->
N0 N1 N2 N0 N1 N2

Therefore, we need to care this overlapping when iterating pfn range.

mark_free_pages() iterates requested zone's pfn range and unset
all range's bitmap first. And then it marks freepages in a zone
to the bitmap. If there is an overlapping zone, above unset could
clear previous marked bit and reference to this bitmap in the future
will cause the problem. To prevent it, this patch adds a zone check
in mark_free_pages().

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 mm/page_alloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0cfee62..437a934 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2156,6 +2156,10 @@ void mark_free_pages(struct zone *zone)
 	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 		if (pfn_valid(pfn)) {
 			page = pfn_to_page(pfn);
+
+			if (page_zone(page) != zone)
+				continue;
+
 			if (!swsusp_page_is_forbidden(page))
 				swsusp_unset_page_free(page);
 		}
-- 
1.9.1