linux-kernel - Re: [patch -mm] i386: use pte_update_defer in ptep_test_and_clear

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Message-ID: <46082BE6.30402@vmware.com>
Date:	Mon, 26 Mar 2007 12:24:06 -0800
From:	Zachary Amsden <zach@...are.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hugh@...itas.com>, linux-kernel@...r.kernel.org
Subject: Re: [patch -mm] i386: use pte_update_defer in ptep_test_and_clear_{dirty,young}

David Rientjes wrote:
> 	Date: Sun, 25 Mar 2007 23:07:43 -0800
> 	From: Zachary Amsden <zach@...are.com>
>
> 	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@...are.com>
> Cc: Hugh Dickins <hugh@...itas.com>
> Signed-off-by: David Rientjes <rientjes@...gle.com>
>   

Acked-by: Zachary Amsden <zach@...are.com>

David, thanks for cleaning this up.
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