linux-kernel - [PATCH] mm, hugetlb: correct bit shift in hstate

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Message-Id: <1413915307-20536-1-git-send-email-sasha.levin@oracle.com>
Date:	Tue, 21 Oct 2014 14:15:07 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	akpm@...ux-foundation.org
Cc:	n-horiguchi@...jp.nec.com, aarcange@...hat.com, mgorman@...e.de,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	a.ryabinin@...sung.com, Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] mm, hugetlb: correct bit shift in hstate_sizelog

hstate_sizelog() would shift left an int rather than long, triggering
undefined behaviour and passing an incorrect value when the requested
page size was more than 4GB, thus breaking >4GB pages.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 include/linux/hugetlb.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 65e12a2..57e0dfd 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -312,7 +312,8 @@ static inline struct hstate *hstate_sizelog(int page_size_log)
 {
 	if (!page_size_log)
 		return &default_hstate;
-	return size_to_hstate(1 << page_size_log);
+
+	return size_to_hstate(1UL << page_size_log);
 }
 
 static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
-- 
1.7.10.4

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