From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hirofumi Tsujimura Subject: HVM domain crash when network attach Date: Fri, 13 Oct 2006 22:44:46 +0900 Message-ID: <452F984E.7010709@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi all, I found a problem when I tested vnif of PV-on-HVM. My operation for the test is following. On domain0: # xm create -f domainHVM.config # xm network-attach domainHVM Then, the kernel of domainHVM panicked and outputted a message "kernel panic - not syncing: Unable to reduce memory reservation". The kernel sometimes panicked not always when I tested it some time. In my investigation ### netfront/netfront.c 285 err = xenbus_scanf(XBT_NIL, dev->otherend, "feature-rx-copy", "%u", 286 &feature_rx_copy); <---------------- (A) 287 if (err != 1) 288 feature_rx_copy = 0; === 802 if ( nr_flips != 0 ) { <------------------------------- (B) === 827 /* Check return status of HYPERVISOR_memory_op(). */ 828 if (unlikely(np->rx_mcl[i].result != i)) 829 panic("Unable to reduce memory reservation\n"); <------ (C) 830 } else { 831 if (HYPERVISOR_memory_op(XENMEM_decrease_reservation, 832 &reservation) != i) 833 panic("Unable to reduce memory reservation\n"); <------- (D) 834 } ### netback/xenbus.c 111 err = xenbus_printf(xbt, dev->nodename, "feature-rx-copy", "%d", 1);<-- (E) The problem happans in (C) or (D) when (B) become true. I think that (B) must not become true on a domainHVM. Because a domainHVM only uses rx_copy mode. (B) is true because (A) fails. (A) fails because (E) is executed after (A). (E) must be execute before (A). However (E) is not always executed before (A). The test environment is as follows. - Architecture : x86_32 with VTx - Xen change set: 11751 - Domain 0 : kernel2.6.16.29-xen - Domain U : kernel2.6.16.29-xen - Domain VTx : kernel2.6.16 Does anyone know how to fix the problem ? Thank you. -- FUJITSU COMPUTER TECHNOLOGIES LIMITED Development Dept. 5 Division 1 Hirofumi Tsujimura E-MAIL: tsujimura.hirof@jp.fujitsu.com