Re: [patch -mm] i386: use pte_update_defer in ptep_test_and_clear_{dirty,young}

From: Zachary Amsden
Date: Mon Mar 26 2007 - 15:24:41 EST


David Rientjes wrote:
Date: Sun, 25 Mar 2007 23:07:43 -0800
From: Zachary Amsden <zach@xxxxxxxxxx>

If you actually clear the bit, you need to:

+ pte_update_defer(vma->vm_mm, addr, ptep);

The reason is, when updating PTEs, the hypervisor must be notified. Using
atomic operations to do this is fine for all hypervisors I am aware of.
However, for hypervisors which shadow page tables, if these PTE
modifications are not trapped, you need a post-modification call to fulfill
the update of the shadow page table.

Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>

Acked-by: Zachary Amsden <zach@xxxxxxxxxx>

David, thanks for cleaning this up.
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