linux-kernel - Re: [PATCH 3/6] KVM: MMU: introduce gfn_to_page_atomic() and gfn_to_pfn

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Date:	Wed, 16 Jun 2010 14:08:22 +0300
From:	Avi Kivity <avi@...hat.com>
To:	huang ying <huang.ying.caritas@...il.com>
CC:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Huang Ying <ying.huang@...el.com>
Subject: Re: [PATCH 3/6] KVM: MMU: introduce gfn_to_page_atomic() and 	gfn_to_pfn_atomic()

On 06/16/2010 01:51 PM, huang ying wrote:
> On Tue, Jun 15, 2010 at 7:22 PM, Avi Kivity<avi@...hat.com>  wrote:
>    
>> btw, is_hwpoison_address() is racy.  While it looks up the address, some
>> other task can unmap the page tables under us.
>>
>> Andi/Huang?
>>
>> One way of fixing it is get_user_pages_ptes_fast(), which also returns the
>> pte, also atomically.  I want it for other reasons as well (respond to a
>> read fault by gupping the page for read, but allowing write access if the
>> pte indicates it is writeable).
>>      
> Yes. is_hwpoison_address() is racy. But I think it is not absolutely
> necessary to call is_hwpoison_address() in hva_to_pfn_atomic(), is it?
>    

We can probably ignore it, yes.

> For is_hwpoison_address() in hva_to_pfn(), we can protect it with mmap_sem.
>    

Not very appealing, but should work.

-- 
error compiling committee.c: too many arguments to function

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