From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages Date: Thu, 24 Sep 2009 18:56:09 +0200 Message-ID: <20090924165609.GB6864@random.random> References: <1253731638-24575-1-git-send-email-ieidus@redhat.com> <1253731638-24575-2-git-send-email-ieidus@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi@redhat.com, kvm@vger.kernel.org, mtosatti@redhat.com To: Izik Eidus Return-path: Received: from mx1.redhat.com ([209.132.183.28]:25174 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751801AbZIXQ4H (ORCPT ); Thu, 24 Sep 2009 12:56:07 -0400 Received: from int-mx04.intmail.prod.int.phx2.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.17]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n8OGuBcA022137 for ; Thu, 24 Sep 2009 12:56:11 -0400 Content-Disposition: inline In-Reply-To: <1253731638-24575-2-git-send-email-ieidus@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Sep 23, 2009 at 09:47:16PM +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.) > > Signed-off-by: Izik Eidus Acked-by: Andrea Arcangeli