linux-kernel - Re: Populating multiple ptes at fault time

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Message-ID: <48D2F05C.4040000@redhat.com>
Date:	Thu, 18 Sep 2008 17:20:44 -0700
From:	Avi Kivity <avi@...hat.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Nick Piggin <nickpiggin@...oo.com.au>,
	Hugh Dickens <hugh@...itas.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: Populating multiple ptes at fault time

Jeremy Fitzhardinge wrote:
>
>>> bet there's an appropriate pvop hook you could use to force
>>> synchronization just before the kernel actually inspects the bits
>>> (leaving lazy mode sounds good).
>>>   
>>>       
>> It would have to be a new lazy mode, not the existing one, I think.
>>     
>
> The only direct use of pte_young() is in zap_pte_range, within a
> mmu_lazy region.  So syncing the A bit state on entering lazy mmu mode
> would work fine there.
>
>   

Ugh, leaving lazy pte.a mode when entering lazy mmu mode?


> The call via page_referenced_one() doesn't seem to have a very
> convenient hook though.  Perhaps putting something in
> page_check_address() would do the job.
>
>   

Why there?

Why not explicitly in the callers?  We need more than to exit lazy pte.a 
mode, we also need to enter it again later.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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