Re: 2.6.16-rc1-mm3

[Nick Piggin <nickpiggin@yahoo.com.au>]

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Nick Piggin wrote:

> Thanks, it confirms my suspicions.
> 
> Can you try the following patch, please?
> It appears the warnings were brought out by my improvement to
> the put_page_testzero debugging code (which previously did not
> check that we might be attempting to free a constituent compound
> page).
> 
> Can you test the following patch please?
> 

Sorry, wrong patch.

Note the warnings you are seeing should not result in memory
corruption, but will result in the given hugepage leaking.

-- 
SUSE Labs, Novell Inc.

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Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -294,6 +294,8 @@ struct page {
  */
 static inline int put_page_testzero(struct page *page)
 {
+	if (unlikely(PageCompound(page)))
+		page = (struct page *)page_private(page);
 	BUG_ON(atomic_read(&page->_count) == 0);
 	return atomic_dec_and_test(&page->_count);
 }