From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/4] Swapping Date: Tue, 16 Oct 2007 09:36:13 +0200 Message-ID: <471469ED.7030100@qumranet.com> References: <47102823.2000600@qumranet.com> <4713ACF8.6010809@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Anthony Liguori Return-path: In-Reply-To: <4713ACF8.6010809-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Anthony Liguori wrote: > I've been playing around with these patches. If I do an > madvise(MADV_DONTNEED) in userspace, when I close the VM, I get the > following bug. My knowledge of the mm is limited but since > madvise(MADV_DONTNEED) effectively does a zap_page_range() I wonder if > we're lacking the necessary callback to also remove any potential GPA > covered by that range from shadow page cache. > > Regards, > > Anthony Liguori > > [ 860.724555] rmap_remove: ffff81004c48cf00 506d1025 0->BUG > The mmu should keep a page's refcount elevated while it's mapped in, so MADV_DONTNEED should not affect it. Looks like there is a bug where kvm looks at the host pagetables for a page which is already in the shadow pagetables. We need to avoid this as long as we don't have pte notifiers. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/