Re: [Qemu-devel] [PATCH RFC 1/1] vmstate: draft fix for failed iotests case 68 and 91

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Kevin Wolf (kwolf@redhat.com) wrote:
> Am 07.03.2017 um 03:53 hat QingFeng Hao geschrieben:
> > I am not very clear about the logic in vmstate.c, but from its context in
> > vmstate_save_state, it seems size should not be 0, otherwise the followed
> > for loop will keep working on the same element. So I just add a simple
> > check to pass that case, not sure if it's right but it can pass iotest
> > case 68 and 91 now.
> > 
> > The iotest's failed output is:
> > 068 1s ... - output mismatch (see 068.out.bad)
> > --- /home/haoqf/KVMonz/gitcheck/work/qemu-master/tree/qemu/tests/qemu-iotests/068.out   2017-03-06 05:52:24.817328899 +0100
> > +++ 068.out.bad 2017-03-07 03:28:44.426714519 +0100
> > @@ -3,9 +3,13 @@
> >  === Saving and reloading a VM state to/from a qcow2 image ===
> > 
> >  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
> > +qemu-system-s390x: migration/vmstate.c:336: vmstate_save_state: Assertion `first_elem || !n_elems' failed.
> > +./common.config: line 109: 52497 Aborted                 ( if [ -n "${QEMU_NEED_PID}" ]; then
> > +    echo $BASHPID > "${QEMU_TEST_DIR}/qemu-${_QEMU_HANDLE}.pid";
> > +fi; exec "$QEMU_PROG" $QEMU_OPTIONS "$@" )
> >  QEMU X.Y.Z monitor - type 'help' for more information
> >  (qemu) savevm 0
> > -(qemu) quit
> > +qemu-system-s390x: Device 'virtio0' does not have the requested snapshot '0'
> >  QEMU X.Y.Z monitor - type 'help' for more information
> >  (qemu) quit
> >  *** done
> > 
> > 091 1s ... [failed, exit status 1] - output mismatch (see 091.out.bad)
> >     --- tests/qemu-iotests/091.out	2016-08-30 12:35:04.207683276 +0200
> >     +++ 091.out.bad	2017-03-06 13:08:03.717135426 +0100
> >     @@ -11,18 +11,23 @@
> >      
> >      vm1: qemu-io disk write complete
> >      vm1: live migration started
> >     -vm1: live migration completed
> >     -
> >     -=== VM 2: Post-migration, write to disk, verify running ===
> >     -
> >     -vm2: qemu-io disk write complete
> >     -vm2: qemu process running successfully
> >     -vm2: flush io, and quit
> >     -Check image pattern
> >     -read 4194304/4194304 bytes at offset 0
> >     -4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> >     -Running 'qemu-img check -r all $TEST_IMG'
> >     -No errors were found on the image.
> >     -80/16384 = 0.49% allocated, 0.00% fragmented, 0.00% compressed clusters
> >     -Image end offset: 5570560
> >     -*** done
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +./common.qemu: line 110: write error: Broken pipe
> >     +Timeout waiting for completed on handle 0
> > 
> > Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
> > ---
> >  migration/vmstate.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> > index 78b3cd4..ff28dde 100644
> > --- a/migration/vmstate.c
> > +++ b/migration/vmstate.c
> > @@ -106,6 +106,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >              int i, n_elems = vmstate_n_elems(opaque, field);
> >              int size = vmstate_size(opaque, field);
> >  
> > +            if (size == 0) {
> > +                field++;
> > +                continue;
> > +            }
> >              vmstate_handle_alloc(first_elem, field, opaque);
> >              if (field->flags & VMS_POINTER) {
> >                  first_elem = *(void **)first_elem;
> > @@ -322,6 +326,10 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >              int64_t old_offset, written_bytes;
> >              QJSON *vmdesc_loop = vmdesc;
> >  
> > +            if (size == 0) {
> > +                field++;
> > +                continue;
> > +            }
> >              trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
> >              if (field->flags & VMS_POINTER) {
> >                  first_elem = *(void **)first_elem;
> 
> This is really a live migration fix, so I'm adding Juan and Dave to CC.
> 
> I suspect the real question is why a field with size 0 was even stored
> in the vmstate to begin with.

Yes; which field is it that's failing?

Dave

> Kevin
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK