[25/41] compound pages: Allow use of get_page_unless_zero with compound pages

[Christoph Lameter <clameter@sgi.com>]

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This is needed by slab defragmentation. The refcount of a page head
may be incremented to ensure that a compound page will not go away under us.

It also may be needed for defragmentation of higher order pages. The
moving of compound pages may require the establishment of a reference
before the use of page migration functions.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
 include/linux/mm.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6f3a8d6..a8a0378 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -290,7 +290,7 @@ static inline int put_page_testzero(struct page *page)
  */
 static inline int get_page_unless_zero(struct page *page)
 {
-	VM_BUG_ON(PageCompound(page));
+	VM_BUG_ON(PageTail(page));
 	return atomic_inc_not_zero(&page->_count);
 }
 
-- 
1.5.2.5

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