From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: Crashing kernel with dom0/libxc gnttab/gntshr Date: Tue, 30 Jul 2013 17:58:38 +0100 Message-ID: <51F7F0BE.1040503@citrix.com> References: <51F79A58.5060004@citrix.com> <1375181944.11701.102.camel@kazak.uk.xensource.com> <51F7C280.6040703@luminar.eu.org> <51F7E0AE.4060605@luminar.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51F7E0AE.4060605@luminar.eu.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Vincent Bernardoff Cc: Daniel De Graaf , Stefano Stabellini , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 30/07/13 16:50, Vincent Bernardoff wrote: > I also have a bug using tools/libvchan/vchan-node1: > > When killing the server node (sudo ./vchan-node1 server read 0 > /local/domain/0/vchan) before the client node (sudo ./vchan-node1 client > write 0 /local/domain/0/vchan), the following dmesg error appears. Does this only happen if both client and server are in the same domain? Have you tested it using two domains? Did it work? > I'm using Xen unstable (master branch) and stock Archlinux 3.10.3-1-ARCH > kernel. > > Use the following script (setup.sh) if you want to try reproducing it > with vchan-node1, vchan-node1 indeed needs some xenstore keys to be > written in order to work correctly. [ 902.729307] BUG: Bad page map in process vchan-node1 pte:12bfff167 pmd:b9b5c067 [ 902.729312] page:ffffea0004afffc0 count:1 mapcount:-1 mapping: (null) index:0xffffffffffffffff I think this is the test for page_mapcount(page) < 0 in zap_pte_range(). This has looked up the page using the PTE it is trying to clear. Has it found the correct page? Since the MFN is currently mapped into the same domain, has the m2p_override stuff confused the look up and it is checking the grantee page not the granter? David