From: Zachary Amsden <zach@vmware.com>
Date: Sun, 1 Oct 2006 06:29:30 +0000 (-0700)
Subject: [PATCH] paravirt: remove read hazard from cow
X-Git-Tag: v2.6.19-rc1~501
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3dc907951446b9317b1887223caa4e083390de9f;p=linux-2.6

[PATCH] paravirt: remove read hazard from cow

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: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/mm/memory.c b/mm/memory.c
index 160f5b503e..7707187484 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -467,7 +467,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	 */
 	if (is_cow_mapping(vm_flags)) {
 		ptep_set_wrprotect(src_mm, addr, src_pte);
-		pte = *src_pte;
+		pte = pte_wrprotect(pte);
 	}
 
 	/*