Re: [PATCH v3 17/21] migration/savevm: don't worry if bitmap migration postcopy failed

[Eric Blake]

On 7/24/20 3:43 AM, Vladimir Sementsov-Ogievskiy wrote:
> First, if only bitmaps postcopy enabled (not ram postcopy)

is enabled (and not ram postcopy),

> postcopy_pause_incoming crashes on assertion assert(mis->to_src_file).

on an

> And anyway, bitmaps postcopy is not prepared to be somehow recovered.
> The original idea instead is that if bitmaps postcopy failed, we just
> loss some bitmaps, which is not critical. So, on failure we just need

lose

> to remove unfinished bitmaps and guest should continue execution on
> destination.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---
>   migration/savevm.c | 37 ++++++++++++++++++++++++++++++++-----
>   1 file changed, 32 insertions(+), 5 deletions(-)

Definitely a bug fix, but I'd like David's opinion on whether this is 
still 5.1 material (because it is limited to just bitmaps migration, 
which is opt-in) or too risky (because we've already had several 
releases where it was broken, what's one more?).

I'm less familiar with the code, so this is weak, but I did read through 
it and nothing jumped out at me, so:

Reviewed-by: Eric Blake <eblake@redhat.com>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org