On Mon, Oct 28, 2013 at 01:22:39PM -0400, Cole Robinson wrote: > On 10/28/2013 01:14 PM, Daniel P. Berrange wrote: > > On Mon, Oct 28, 2013 at 01:08:45PM -0400, Cole Robinson wrote: > >> On 10/28/2013 01:06 PM, Daniel P. Berrange wrote: > >>> On Mon, Oct 28, 2013 at 01:03:49PM -0400, Cole Robinson wrote: > >>>> On 10/28/2013 07:52 AM, Daniel P. Berrange wrote: > >>>>> From: "Daniel P. Berrange" <berrange@xxxxxxxxxx> > >>>>> > >>>>> The following sequence > >>>>> > >>>>> 1. Define a persistent QMEU guest > >>>>> 2. Start the QEMU guest > >>>>> 3. Stop libvirtd > >>>>> 4. Kill the QEMU process > >>>>> 5. Start libvirtd > >>>>> 6. List persistent guets > >>>>> > >>>>> At the last step, the previously running persistent guest > >>>>> will be missing. This is because of a race condition in the > >>>>> QEMU driver startup code. It does > >>>>> > >>>>> 1. Load all VM state files > >>>>> 2. Spawn thread to reconnect to each VM > >>>>> 3. Load all VM config files > >>>>> > >>>>> Only at the end of step 3, does the 'virDomainObjPtr' get > >>>>> marked as "persistent". There is therefore a window where > >>>>> the thread reconnecting to the VM will remove the persistent > >>>>> VM from the list. > >>>>> > >>>>> The easy fix is to simply switch the order of steps 2 & 3. > >>>>> > >>>>> Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx> > >>>>> --- > >>>>> src/qemu/qemu_driver.c | 3 +-- > >>>>> 1 file changed, 1 insertion(+), 2 deletions(-) > >>>>> > >>>>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c > >>>>> index c613967..9c3daad 100644 > >>>>> --- a/src/qemu/qemu_driver.c > >>>>> +++ b/src/qemu/qemu_driver.c > >>>>> @@ -816,8 +816,6 @@ qemuStateInitialize(bool privileged, > >>>>> > >>>>> conn = virConnectOpen(cfg->uri); > >>>>> > >>>>> - qemuProcessReconnectAll(conn, qemu_driver); > >>>>> - > >>>>> /* Then inactive persistent configs */ > >>>>> if (virDomainObjListLoadAllConfigs(qemu_driver->domains, > >>>>> cfg->configDir, > >>>>> @@ -828,6 +826,7 @@ qemuStateInitialize(bool privileged, > >>>>> NULL, NULL) < 0) > >>>>> goto error; > >>>>> > >>>>> + qemuProcessReconnectAll(conn, qemu_driver); > >>>>> > >>>>> virDomainObjListForEach(qemu_driver->domains, > >>>>> qemuDomainSnapshotLoad, > >>>>> > >>>> > >>>> I tried testing this patch to see if it would fix: > >>>> > >>>> https://bugzilla.redhat.com/show_bug.cgi?id=1015246 > >>>> > >>>> from current master I did: > >>>> > >>>> git revert a924d9d083c215df6044387057c501d9aa338b96 > >>>> reproduce the bug > >>>> git am <your-patch> > >>>> > >>>> But the daemon won't even start up after your patch is built: > >>>> > >>>> (gdb) bt > >>>> #0 qemuMonitorOpen (vm=vm@entry=0x7fffd4211090, config=0x0, json=false, > >>>> cb=cb@entry=0x7fffddcae720 <monitorCallbacks>, > >>>> opaque=opaque@entry=0x7fffd419b840) at qemu/qemu_monitor.c:852 > > > >> Sorry for not being clear: The daemon crashes, that's the backtrace. > > > > Hmm config is NULL - does the state XML files not include the > > monitor info perhaps ? > > > > I see: > > pidfile for busted VM in /var/run/libvirt/qemu > nothing in /var/cache/libvirt/qemu > no state that I can see in /var/lib/libvirt/qemu > > But I'm not sure where it's supposed to be stored. > > FWIW reproducing this state was pretty simple: revert > a924d9d083c215df6044387057c501d9aa338b96, edit an existing x86 guest to remove > all <video> and <graphics> devices, start the guest, libvirtd crashes. Ok, I believe you probably have SELinux disabled on your machine or in libvirtd. With SELinux enabled you hit another bug first 2013-10-29 13:50:11.711+0000: 17579: error : qemuConnectMonitor:1401 : Failed to set security context for monitor for rhel6x86_64 which prevents hitting the crash you report. The fix is the same in both cases - we must skip VMs with PID of zero. I've sent a v2 patch. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list