Linux Virtualization - Apr 2007 - [PATCH 1/9] 00mm1 remove read hazard from cow.patch

We don't want to read PTEs directly like this after they have been
modified, as a lazy MMU implementation of direct page tables may not
have written the updated PTE back to memory yet.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: linux-mm@kvack.org

---
 mm/memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


==================================================================---
a/mm/memory.c
+++ b/mm/memory.c
@@ -466,7 +466,7 @@ copy_one_pte(struct mm_struct *dst_mm, s
 	 */
 	if (is_cow_mapping(vm_flags)) {
 		ptep_set_wrprotect(src_mm, addr, src_pte);
-		pte = *src_pte;
+		pte = pte_wrprotect(pte);
 	}
 
 	/*

We don't want to read PTEs directly like this after they have been
modified, as a lazy MMU implementation of direct page tables may not
have written the updated PTE back to memory yet.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: linux-mm@kvack.org

---
 mm/memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


==================================================================---
a/mm/memory.c
+++ b/mm/memory.c
@@ -466,7 +466,7 @@ copy_one_pte(struct mm_struct *dst_mm, s
 	 */
 	if (is_cow_mapping(vm_flags)) {
 		ptep_set_wrprotect(src_mm, addr, src_pte);
-		pte = *src_pte;
+		pte = pte_wrprotect(pte);
 	}
 
 	/*