[PATCH 1/2] mm: page_isolation: check pfn validity before access

[Weijie Yang]

In the undo path of start_isolate_page_range(), we need to check
the pfn validity before access its page, or it will trigger an
addressing exception if there is hole in the zone.

Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
---
 mm/page_isolation.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index d1473b2..3ddc8b3 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -137,8 +137,11 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 undo:
 	for (pfn = start_pfn;
 	     pfn < undo_pfn;
-	     pfn += pageblock_nr_pages)
-		unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
+	     pfn += pageblock_nr_pages) {
+		page = __first_valid_page(pfn, pageblock_nr_pages);
+		if (page)
+			unset_migratetype_isolate(page, migratetype);
+	}
 
 	return -EBUSY;
 }
-- 
1.7.0.4


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