linux-kernel - Re: [Xen-devel] Re: [PATCH 0/6] xen: don't call vmalloc_sync

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Message-ID: <4E7C6B18.7030100@citrix.com>
Date:	Fri, 23 Sep 2011 12:18:48 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [Xen-devel] Re: [PATCH 0/6] xen: don't call vmalloc_sync_all()
 when mapping foreign pages

On 22/09/11 22:19, Jeremy Fitzhardinge wrote:
> 
> But I'd be happier pretending that vmalloc_sync_* just doesn't exist,
> and deal with it at the hypercall level - in the short term, by just
> making sure that the callers touch all those pages before passing them
> into the hypercall.

I don't think you can access the pages at the addresses allocated with
alloc_vm_area() because the pages don't exist yet and there's a check of
pte_present() in vmalloc_fault() and I think an Oops will be reported.

David
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