* Thomas Huth (th...@redhat.com) wrote: > On 18.11.2016 09:13, Thomas Huth wrote: > > On 17.11.2016 04:45, David Gibson wrote: > >> On Mon, Nov 14, 2016 at 07:34:59PM +0100, Juan Quintela wrote: > >>> Thomas Huth <th...@redhat.com> wrote: > >>>> qemu_savevm_state_iterate() expects the iterators to return 1 > >>>> when they are done, and 0 if there is still something left to do. > >>>> However, ram_save_iterate() does not obey this rule and returns > >>>> the number of saved pages instead. This causes a fatal hang with > >>>> ppc64 guests when you run QEMU like this (also works with TCG): > >>>> > >>>> qemu-img create -f qcow2 /tmp/test.qcow2 1M > >>>> qemu-system-ppc64 -nographic -nodefaults -m 256 \ > >>>> -hda /tmp/test.qcow2 -serial mon:stdio > >>>> > >>>> ... then switch to the monitor by pressing CTRL-a c and try to > >>>> save a snapshot with "savevm test1" for example. > >>>> > >>>> After the first iteration, ram_save_iterate() always returns 0 here, > >>>> so that qemu_savevm_state_iterate() hangs in an endless loop and you > >>>> can only "kill -9" the QEMU process. > >>>> Fix it by using proper return values in ram_save_iterate(). > >>>> > >>>> Signed-off-by: Thomas Huth <th...@redhat.com> > >>> > >>> Reviewed-by: Juan Quintela <quint...@redhat.com> > >>> > >>> Applied. > >>> > >>> I don't know how we broked this so much. > >> > >> Note that block save iterate has the same bug... > > > > I think you're right. Care to send a patch? > > Looking at this issue again ... could it be that block_save_iterate() is > currently just dead code? > As far as I can see, the ->save_live_iterate() handlers are only called > from qemu_savevm_state_iterate(), right? And qemu_savevm_state_iterate() > only calls the handlers if se->ops->is_active(se->opaque) returns true. > But block_is_active() seems to only return 0 during savevm, most likely > because qemu_savevm_state() explicitly sets the "blk" and "shared" > MigrationParams to zero. > So to me, it looks like we could also just remove block_save_iterate() > completely ... or did I miss something here?
Doesn't it get called by migrate -b ? Dave > Thomas > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
