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* [PATCH] hugetlb: handle write-protection faults in follow_hugetlb_page
@ 2007-12-06 20:41 Adam Litke
  0 siblings, 0 replies; only message in thread
From: Adam Litke @ 2007-12-06 20:41 UTC (permalink / raw)
  To: Andrew Morton; +Cc: Adam Litke, Dave Kleikamp, Ken Chen, linux-kernel

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 <>
Acked-by: Dave Kleikamp <>

 mm/hugetlb.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 6121b57..6f97821 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;

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2007-12-06 20:41 [PATCH] hugetlb: handle write-protection faults in follow_hugetlb_page Adam Litke

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