[PATCH v2 1/2] mm: free compound page with correct order

From: Yu Zhao
Date: Wed Oct 15 2014 - 15:27:17 EST

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.

Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Cc: stable@xxxxxxxxxxxxxxx (v3.8+)
Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
mm/huge_memory.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 74c78aa..780d12c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -200,7 +200,7 @@ retry:
if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
- __free_page(zero_page);
+ __free_pages(zero_page, compound_order(zero_page));
goto retry;

@@ -232,7 +232,7 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
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;


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/