[PATCH 3.13.y-ckt 64/95] mm/hugetlb: use pmd_page() in follow_huge_pmd()

From: Kamal Mostafa
Date: Wed May 27 2015 - 15:01:58 EST


3.13.11-ckt21 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>

commit 97534127012f0e396eddea4691f4c9b170aed74b upstream.

Commit 61f77eda9bbf ("mm/hugetlb: reduce arch dependent code around
follow_huge_*") broke follow_huge_pmd() on s390, where pmd and pte
layout differ and using pte_page() on a huge pmd will return wrong
results. Using pmd_page() instead fixes this.

All architectures that were touched by that commit have pmd_page()
defined, so this should not break anything on other architectures.

Fixes: 61f77eda "mm/hugetlb: reduce arch dependent code around follow_huge_*"
Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>, Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
mm/hugetlb.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a716aac..b14f49b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3491,8 +3491,7 @@ retry:
if (!pmd_huge(*pmd))
goto out;
if (pmd_present(*pmd)) {
- page = pte_page(*(pte_t *)pmd) +
- ((address & ~PMD_MASK) >> PAGE_SHIFT);
+ page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
if (flags & FOLL_GET)
get_page(page);
} else {
--
1.9.1

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