在 2017/11/16 3:39, Dr. David Alan Gilbert 写道:
> * Yori Fang (fangyi...@huawei.com) wrote:
>>
>>
>> 在 2017/11/14 19:40, Marc-André Lureau 写道:
>>> Hi
>>>
>>> On Tue, Nov 14, 2017 at 8:09 AM, fangying <fangyi...@huawei.com> wrote:
>>>> Hi all,
>>>>
>>>> We have a vm running migration with vhost-user as network backend, we
>>>> notice that qemu will abort when openvswitch is restarted
>>>> when MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward) is called. The
>>>> reasion is clear that vhost_dev_set_log returns -1 because
>>>> the network connection is temporarily lost due to the restart of
>>>> openvswitch service.
>>>>
>>>> Below is the trace of the call stack.
>>>>
>>>> #0 0x00007f868ed971d7 in raise() from /usr/lib64/libc.so.6
>>>> #1 0x00007f868ed988c8 in abort() from /usr/lib64/libc.so.6
>>>> #2 0x00000000004d0d35 in vhost_log_global_start (listener=<optimized
>>>> out>) at /usr/src/debug/qemu-kvm-2.8.1/hw/virtio/vhost.c:794
>>>> #2 0x0000000000486bd2 in memory_global_dirty_log_start at
>>>> /usr/src/debug/qemu-kvm-2.8.1/memory.c:2304
>>>> #3 0x0000000000486dcd in ram_save_init_globals at
>>>> /usr/src/debug/qemu-kvm-2.8.1/migration/ram.c:2072
>>>> #4 0x000000000048c185 in ram_save_setup (f=0x25e6ac0, opaque=<optimized
>>>> out>) at /usr/src/debug/qemu-kvm-2.8.1/migration/ram.c:2093
>>>> #5 0x00000000004fbee2 in qemu_savevm_state_begin at
>>>> /usr/src/debug/qemu-kvm-2.8.1/migration/savevm.c:956
>>>> #6 0x000000000083d8f8 in migration_thread at migration/migration.c:2198
>>>>
>>>> static void vhost_log_global_start(MemoryListener *listener)
>>>> {
>>>> int r;
>>>>
>>>> r = vhost_migration_log(listener, true);
>>>> if (r < 0) {
>>>> abort(); /* branch taken */
>>>> }
>>>> }
>>>>
>>>> What confuse me is that
>>>> 1. do we really need to abort here ?
>>>
>>> Not if we have a sane way to handle the situation. It make sense
>>> though to not want to support that use case (restarting the vhost-user
>>> process during migration).
>>>
>>>> 2. all member of callbacks in MemoryListener returned with type void, we
>>>> cannot judge in any upper function on the call stack.
>>>> Can we just cancel migration here instead of calling abort ? like:
>>>
>>> That would be acceptable to me, but there should be a better way than
>>> calling qmp_migrate_cancel() (we need to give a reason for cancelling,
>>> and report it to user). Juan should be able to help.
>>
>> I agree with you, we'd better give more details here instead of passing NULL
>> in qmp_migrate_cancel.
>
> This is an unfortunate place to want to kill the migration; cancel is
> the wrong call to use though (it's for users to cancel it).
> I think the only way to do it is to call
> migrate_fd_error(migrate_get_current(),...)
>
> It's not nice though, but the only one I can think of from here.
Thanks, we should use migrate_fd_error(migrate_get_current(),...) instead.
Actually, this kind of error is better handled in upper level of
migration_thread.
However, the current MEMORY_LISTENER_CALL_xxx doesn't take care of the return
value of MemoryListener callbacks.
>
> Dave
>
>>>
>>>>
>>>> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>>>> index ddc42f0..27ae4a2 100644
>>>> --- a/hw/virtio/vhost.c
>>>> +++ b/hw/virtio/vhost.c
>>>> @@ -27,6 +27,7 @@
>>>> #include "hw/virtio/virtio-access.h"
>>>> #include "migration/blocker.h"
>>>> #include "sysemu/dma.h"
>>>> +#include "qmp-commands.h"
>>>>
>>>> /* enabled until disconnected backend stabilizes */
>>>> #define _VHOST_DEBUG 1
>>>> @@ -885,7 +886,7 @@ static void vhost_log_global_start(MemoryListener
>>>> *listener)
>>>>
>>>> r = vhost_migration_log(listener, true);
>>>> if (r < 0) {
>>>> - abort();
>>>> + qmp_migrate_cancel(NULL);
>>>> }
>>>> }
>>>>
>>>> @@ -895,7 +896,7 @@ static void vhost_log_global_stop(MemoryListener
>>>> *listener)
>>>>
>>>> r = vhost_migration_log(listener, false);
>>>> if (r < 0) {
>>>> - abort();
>>>> + qmp_migrate_cancel(NULL);
>>>> }
>>>> }
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
> --
> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
>
> .
>
