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[Xen-devel] [PATCH 9 of 13] Remove the read hazard from the COW path in

To: Andrew Morton <akpm@xxxxxxxx>
Subject: [Xen-devel] [PATCH 9 of 13] Remove the read hazard from the COW path in copy_one_pte
From: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Date: Tue, 01 Aug 2006 13:00:47 -0700
Cc: Virtualization <virtualization@xxxxxxxx>, Zachary Amsden <zach@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>, Hollis Blanchard <hollisb@xxxxxxxxxx>, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxxxxxx>, Ian Pratt <ian.pratt@xxxxxxxxxxxxx>, "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>, Gerd Hoffmann <kraxel@xxxxxxx>, Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>, Christoph Lameter <clameter@xxxxxxx>
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1 file changed, 1 insertion(+), 1 deletion(-)
mm/memory.c |    2 +-

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@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>


diff -r 0adfc39039c7 -r 20f9c0c451af mm/memory.c
--- a/mm/memory.c       Tue Aug 01 01:32:00 2006 -0700
+++ b/mm/memory.c       Tue Aug 01 01:32:00 2006 -0700
@@ -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);

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