[PATCH 3.12 011/142] mm/hugetlb: use pmd_page() in follow_huge_pmd()

Jiri Slaby
2015-05-16T08:48:59Z

From: Gerald Schaefer <gerald.schaefer@de.ibm.com>

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

===============

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@de.ibm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.cz>, Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
mm/hugetlb.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 424ee30fcd0d..c91c347bb3ea 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3494,8 +3494,7 @@ 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 {
--
2.3.7