The patch titled
     Subject: mm: free compound page with correct order
has been added to the -mm tree.  Its filename is
     mm-free-compound-page-with-correct-order.patch

This patch should soon appear at
    
http://ozlabs.org/~akpm/mmots/broken-out/mm-free-compound-page-with-correct-order.patch
and later at
    
http://ozlabs.org/~akpm/mmotm/broken-out/mm-free-compound-page-with-correct-order.patch

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------------------------------------------------------
From: Yu Zhao <[email protected]>
Subject: mm: free compound page with correct order

Compound page should be freed by put_page() or free_pages() with correct
order.  Not doing so will cause tail pages leaked.

The compound order can be obtained by compound_order() or use
HPAGE_PMD_ORDER in our case.  Some people would argue the latter is faster
but I prefer the former which is more general.

Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Signed-off-by: Yu Zhao <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Bob Liu <[email protected]>
Cc: <[email protected]>    [3.8+]
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/huge_memory.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN mm/huge_memory.c~mm-free-compound-page-with-correct-order 
mm/huge_memory.c
--- a/mm/huge_memory.c~mm-free-compound-page-with-correct-order
+++ a/mm/huge_memory.c
@@ -200,7 +200,7 @@ retry:
        preempt_disable();
        if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
                preempt_enable();
-               __free_page(zero_page);
+               __free_pages(zero_page, compound_order(zero_page));
                goto retry;
        }
 
@@ -232,7 +232,7 @@ static unsigned long shrink_huge_zero_pa
        if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
                struct page *zero_page = xchg(&huge_zero_page, NULL);
                BUG_ON(zero_page == NULL);
-               __free_page(zero_page);
+               __free_pages(zero_page, compound_order(zero_page));
                return HPAGE_PMD_NR;
        }
 
_

Patches currently in -mm which might be from [email protected] are

mm-free-compound-page-with-correct-order.patch
mm-verify-compound-order-when-freeing-a-page.patch

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