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* [PATCH] memory hotplug: fix page_zone() calculation in test_pages_isolated()
@ 2008-10-27 16:49 Gerald Schaefer
  2008-10-27 17:17 ` Gerald Schaefer
                   ` (2 more replies)
  0 siblings, 3 replies; 10+ messages in thread
From: Gerald Schaefer @ 2008-10-27 16:49 UTC (permalink / raw)
  To: akpm
  Cc: linux-kernel, linux-mm, schwidefsky, heiko.carstens,
	kamezawa.hiroyu, y-goto

From: Gerald Schaefer <gerald.schaefer@de.ibm.com>

My last bugfix here (adding zone->lock) introduced a new problem: Using
pfn_to_page(pfn) to get the zone after the for() loop is wrong. pfn then
points to the first pfn after end_pfn, which may be in a different zone
or not present at all. This may lead to an addressing exception in
page_zone() or spin_lock_irqsave().

Using the last valid page that was found inside the for() loop, instead
of pfn_to_page(), should fix this.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>

---
mm/page_isolation.c |    6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

Index: linux-2.6/mm/page_isolation.c
===================================================================
--- linux-2.6.orig/mm/page_isolation.c
+++ linux-2.6/mm/page_isolation.c
@@ -115,7 +115,7 @@ __test_page_isolated_in_pageblock(unsign
int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
{
	unsigned long pfn, flags;
-	struct page *page;
+	struct page *page = NULL;
	struct zone *zone;
	int ret;

@@ -130,10 +130,10 @@ int test_pages_isolated(unsigned long st
		if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
			break;
	}
-	if (pfn < end_pfn)
+	if ((pfn < end_pfn) || !page)
		return -EBUSY;
	/* Check all pages are free or Marked as ISOLATED */
-	zone = page_zone(pfn_to_page(pfn));
+	zone = page_zone(page);
	spin_lock_irqsave(&zone->lock, flags);
	ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
	spin_unlock_irqrestore(&zone->lock, flags);


^ permalink raw reply	[flat|nested] 10+ messages in thread
* [PATCH] memory hotplug: fix page_zone() calculation in test_pages_isolated()
@ 2008-10-29 14:25 Gerald Schaefer
  2008-10-29 18:00 ` Nathan Fontenot
  2008-10-30  0:09 ` KAMEZAWA Hiroyuki
  0 siblings, 2 replies; 10+ messages in thread
From: Gerald Schaefer @ 2008-10-29 14:25 UTC (permalink / raw)
  To: akpm
  Cc: linux-kernel, linux-mm, schwidefsky, heiko.carstens,
	kamezawa.hiroyu, y-goto, dave

From: Gerald Schaefer <gerald.schaefer@de.ibm.com>

My last bugfix here (adding zone->lock) introduced a new problem: Using
page_zone(pfn_to_page(pfn)) to get the zone after the for() loop is wrong.
pfn will then be >= end_pfn, which may be in a different zone or not
present at all. This may lead to an addressing exception in page_zone()
or spin_lock_irqsave().

Now I use __first_valid_page() again after the loop to find a valid page
for page_zone().

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>

---
 mm/page_isolation.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/page_isolation.c
===================================================================
--- linux-2.6.orig/mm/page_isolation.c
+++ linux-2.6/mm/page_isolation.c
@@ -130,10 +130,11 @@ int test_pages_isolated(unsigned long st
 		if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 			break;
 	}
-	if (pfn < end_pfn)
+	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
+	if ((pfn < end_pfn) || !page)
 		return -EBUSY;
 	/* Check all pages are free or Marked as ISOLATED */
-	zone = page_zone(pfn_to_page(pfn));
+	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
 	spin_unlock_irqrestore(&zone->lock, flags);


^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2008-10-30  0:10 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-10-27 16:49 [PATCH] memory hotplug: fix page_zone() calculation in test_pages_isolated() Gerald Schaefer
2008-10-27 17:17 ` Gerald Schaefer
2008-10-27 17:19 ` Gerald Schaefer
2008-10-27 17:25 ` Dave Hansen
2008-10-27 17:59   ` Gerald Schaefer
2008-10-28  0:32     ` KAMEZAWA Hiroyuki
2008-10-28 13:00       ` Gerald Schaefer
2008-10-29 14:25 Gerald Schaefer
2008-10-29 18:00 ` Nathan Fontenot
2008-10-30  0:09 ` KAMEZAWA Hiroyuki

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