From 72fad7139b6829f71d7f41f39eb30da5760d90a8 Mon Sep 17 00:00:00 2001
From: Adam Litke <agl@us.ibm.com>
Date: Mon, 10 Dec 2007 15:49:28 -0800
Subject: [PATCH] hugetlb: handle write-protection faults in
follow_hugetlb_page
The follow_hugetlb_page() fix I posted (merged as git commit
5b23dbe8173c212d6a326e35347b038705603d39) missed one case. If the pte is
present, but not writable and write access is requested by the caller to
get_user_pages(), the code will do the wrong thing. Rather than calling
hugetlb_fault to make the pte writable, it notes the presence of the pte
and continues.
This simple one-liner makes sure we also fault on the pte for this case.
Please apply.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Acked-by: Dave Kleikamp <shaggy@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 6121b57bbe96..6f978218c2c8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -907,7 +907,7 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
*/
pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
- if (!pte || pte_none(*pte)) {
+ if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
int ret;
spin_unlock(&mm->page_table_lock);