[25/36] compound pages: Allow use of get_page_unless_zero with compound pages

[clameter@sgi.com]

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(-)

Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h	2007-08-27 20:59:40.000000000 -0700
+++ linux-2.6/include/linux/mm.h	2007-08-27 21:03:20.000000000 -0700
@@ -290,7 +290,7 @@ static inline int put_page_testzero(stru
  */
 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);
 }
 

-- 
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