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From: Andy Whitcroft <apw@shadowen.org>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andy Whitcroft <apw@shadowen.org>, Mel Gorman <mel@csn.ul.ie>
Subject: [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely
Date: Tue, 27 Feb 2007 11:35:23 -0800	[thread overview]
Message-ID: <e64dea44318a03a559d7a230d9b14e42@kernel> (raw)
In-Reply-To: exportbomb.1172604830@kernel


Now that we are passing in a boolean active flag we need to
ensure that the result of PageActive(page) is comparible
to that boolean.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b878d54..2bfad79 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -632,7 +632,12 @@ static int __isolate_lru_page(struct page *page, int active)
 {
 	int ret = -EINVAL;
 
-	if (PageLRU(page) && (PageActive(page) == active)) {
+	/*
+	 * When checking the active state, we need to be sure we are
+	 * dealing with comparible boolean values.  Take the logical not
+	 * of each.
+	 */
+	if (PageLRU(page) && (!PageActive(page) == !active)) {
 		ret = -EBUSY;
 		if (likely(get_page_unless_zero(page))) {
 			/*

WARNING: multiple messages have this Message-ID (diff)
From: Andy Whitcroft <apw@shadowen.org>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andy Whitcroft <apw@shadowen.org>, Mel Gorman <mel@csn.ul.ie>
Subject: [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely
Date: Tue, 27 Feb 2007 11:35:23 -0800	[thread overview]
Message-ID: <e64dea44318a03a559d7a230d9b14e42@kernel> (raw)
In-Reply-To: exportbomb.1172604830@kernel

Now that we are passing in a boolean active flag we need to
ensure that the result of PageActive(page) is comparible
to that boolean.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b878d54..2bfad79 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -632,7 +632,12 @@ static int __isolate_lru_page(struct page *page, int active)
 {
 	int ret = -EINVAL;
 
-	if (PageLRU(page) && (PageActive(page) == active)) {
+	/*
+	 * When checking the active state, we need to be sure we are
+	 * dealing with comparible boolean values.  Take the logical not
+	 * of each.
+	 */
+	if (PageLRU(page) && (!PageActive(page) == !active)) {
 		ret = -EBUSY;
 		if (likely(get_page_unless_zero(page))) {
 			/*

--
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  parent reply	other threads:[~2007-02-27 19:35 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-27 19:33 [PATCH 0/5] Lumpy Reclaim V4 Andy Whitcroft
2007-02-27 19:33 ` Andy Whitcroft
2007-02-27 19:34 ` [PATCH 1/5] Lumpy Reclaim V3 Andy Whitcroft
2007-02-27 19:34   ` Andy Whitcroft
2007-02-28 18:14   ` Christoph Lameter
2007-02-28 18:14     ` Christoph Lameter
2007-03-02 15:45     ` Andy Whitcroft
2007-03-02 15:45       ` Andy Whitcroft
2007-02-27 19:34 ` [PATCH 2/5] lumpy: isolate_lru_pages wants to specifically take active or inactive pages Andy Whitcroft
2007-02-27 19:34   ` Andy Whitcroft
2007-02-28 18:17   ` Christoph Lameter
2007-02-28 18:17     ` Christoph Lameter
2007-03-02 15:57     ` Andy Whitcroft
2007-03-02 15:57       ` Andy Whitcroft
2007-02-27 19:35 ` Andy Whitcroft [this message]
2007-02-27 19:35   ` [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely Andy Whitcroft
2007-02-27 19:35 ` [PATCH 4/5] lumpy: update commentry on subtle comparisons and rounding assumptions Andy Whitcroft
2007-02-27 19:35   ` Andy Whitcroft
2007-02-27 19:36 ` [PATCH 5/5] lumpy: only check for valid pages when holes are present Andy Whitcroft
2007-02-27 19:36   ` Andy Whitcroft

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