linux-kernel - [PATCH v2 2/3] PM / Hibernate : do not count debug pages as savable

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Date:	Fri, 18 Nov 2011 17:25:06 +0100
From:	Stanislaw Gruszka <sgruszka@...hat.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Stanislaw Gruszka <sgruszka@...hat.com>
Subject: [PATCH v2 2/3] PM / Hibernate : do not count debug pages as savable

When debugging with CONFIG_DEBUG_PAGEALLOC and
debug_guardpage_minorder > 0, we have lot of free pages that are not
marked so. Snapshot code account them as savable, what cause hibernate
memory preallocation failure.

It is pretty hard to make hibernate allocation succeed with
debug_guardpage_minorder=1. This change at least make it possible when
system has relatively big amount of RAM.

v1 -> v2:
 - change "corrupt" name to guard page

Acked-by: Rafael J. Wysocki <rjw@...k.pl>
Signed-off-by: Stanislaw Gruszka <sgruszka@...hat.com>
---
 kernel/power/snapshot.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index cbe2c14..1cf8890 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -858,6 +858,9 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
 	    PageReserved(page))
 		return NULL;
 
+	if (page_is_guard(page))
+		return NULL;
+
 	return page;
 }
 
@@ -920,6 +923,9 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn)
 	    && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
 		return NULL;
 
+	if (page_is_guard(page))
+		return NULL;
+
 	return page;
 }
 
-- 
1.7.1

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