From mboxrd@z Thu Jan  1 00:00:00 1970
From: Izik Eidus <ieidus@redhat.com>
Subject: Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped	sptes
 pages.
Date: Thu, 09 Apr 2009 15:52:19 +0300
Message-ID: <49DDEF83.7010406@redhat.com>
References: <1238457604-7637-1-git-send-email-ieidus@redhat.com> <1238457604-7637-2-git-send-email-ieidus@redhat.com> <20090409095408.GA31724@amt.cnet>
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Cc: kvm@vger.kernel.org, avi@redhat.com
To: Marcelo Tosatti <mtosatti@redhat.com>
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Marcelo Tosatti wrote:
> On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote:
>   
>> When using mmu notifiers, we are allowed to remove the page count
>> reference tooken by get_user_pages to a specific page that is mapped
>> inside the shadow page tables.
>>
>> This is needed so we can balance the pagecount against mapcount
>> checking.
>>
>> (Right now kvm increase the pagecount and does not increase the
>> mapcount when mapping page into shadow page table entry,
>> so when comparing pagecount against mapcount, you have no
>> reliable result.)
>>     
>
> IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset)
> instead of in the backward compat code gives less room for headaches.
>
>   
That was the first version of this patch, Avi preferred not to do it...