[PATCH v2 1/6] mm/balloon_compaction: ignore anonymous pages

[Konstantin Khlebnikov <koct9i@gmail.com>]

From: Konstantin Khlebnikov <k.khlebnikov@samsung.com>

Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in function __is_movable_balloon_page() which tests AS_BALLOON_MAP
in page->mapping->flags. This function has no protection against anonymous
pages. As result it tried to check address space flags in inside anon-vma.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: stable <stable@vger.kernel.org> # v3.8
---
 include/linux/balloon_compaction.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 089743a..53d482e 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -128,7 +128,7 @@ static inline bool page_flags_cleared(struct page *page)
 static inline bool __is_movable_balloon_page(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
-	return mapping_balloon(mapping);
+	return !PageAnon(page) && mapping_balloon(mapping);
 }
 
 /*

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