From: Izik Eidus <ieidus@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org, avi@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 [thread overview]
Message-ID: <49DDEF83.7010406@redhat.com> (raw)
In-Reply-To: <20090409095408.GA31724@amt.cnet>
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...
next prev parent reply other threads:[~2009-04-09 12:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-31 0:00 [PATCH 0/3] kvm support for ksm Izik Eidus
2009-03-31 0:00 ` [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Izik Eidus
2009-03-31 0:00 ` [PATCH 2/3] kvm: add SPTE_HOST_WRITEABLE flag to the shadow ptes Izik Eidus
2009-03-31 0:00 ` [PATCH 3/3] kvm: add support for change_pte mmu notifiers Izik Eidus
2009-04-09 9:59 ` [PATCH 2/3] kvm: add SPTE_HOST_WRITEABLE flag to the shadow ptes Marcelo Tosatti
2009-04-09 12:58 ` Izik Eidus
2009-04-09 9:54 ` [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Marcelo Tosatti
2009-04-09 12:52 ` Izik Eidus [this message]
2009-04-12 9:01 ` Izik Eidus
2009-04-12 9:42 ` Avi Kivity
2022-10-18 3:19 ` [PATCH 0/3] kvm support for ksm ewandevelop
2022-10-18 3:31 ` ewandevelop
2009-09-10 16:38 [PATCH 0/3] ksm support for kvm Izik Eidus
2009-09-10 16:38 ` [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Izik Eidus
2009-09-23 18:25 [PATCH 0/3] ksm support for kvm v2 Izik Eidus
2009-09-23 18:25 ` [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Izik Eidus
2009-09-23 18:47 [PATCH 0/3] kvm ksm support v3 Izik Eidus
2009-09-23 18:47 ` [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Izik Eidus
2009-09-24 14:18 ` Marcelo Tosatti
2009-09-24 16:56 ` Andrea Arcangeli
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