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Re: [Xen-devel] [PATCH] Make get_page_from_l1e refcount correctly onfor

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Make get_page_from_l1e refcount correctly onforeign pagetables.
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Thu, 14 May 2009 10:39:14 +0100
Cc: Yunhong Jiang <yunhong.jiang@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>
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At 10:23 +0100 on 14 May (1242296611), Keir Fraser wrote:
> > This is all pretty confusing, though, and Keir may correct me on any or
> > all of it. :)
> 
> I wish I could. I need a damp towel wrapped round my head to understand the
> details of that code now.

You're not alone.  Every time I look at that I need to start from
scratch.  It doesn't help that the put_page side also takes a domain
pointer but has different semantics.

> We may need to step back and refactor and rethink
> after 3.4. Hence my reluctance to mess with it now, as I fear introducing
> bugs more significant than latent stubdom issues.

I think it'd be OK to leave this patch out if you're worried about it,
especially if you're going to refactor this after 3.4.  The crash it
fixes hasn't been seen by anyone else, David has a heavily modified
system, and the bug's been there since out-of-sync pagetables came in.

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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