Re: [PATCH 0/3] block/nbd: fix crashers in reconnect while migrating

[Vladimir Sementsov-Ogievskiy]

28.01.2021 23:14, Roman Kagan wrote:
> During the final phase of migration the NBD reconnection logic may
> encounter situations it doesn't expect during regular operation.
>
> This series addresses some of them that make qemu crash.  They are
> reproducible when a vm with a secondary drive attached via nbd with
> non-zero "reconnect-delay" runs a stress load (fio with big queue depth)
> in the guest on that drive and is migrated (e.g. to a file), while the
> nbd server is SIGKILL-ed and restarted every second.
>
> See the individual patches for specific crash conditions and more
> detailed explanations.
>
> Roman Kagan (3):
>    block/nbd: only detach existing iochannel from aio_context
>    block/nbd: only enter connection coroutine if it's present
>    nbd: make nbd_read* return -EIO on error
>
>   include/block/nbd.h |  7 ++++---
>   block/nbd.c         | 25 +++++++++++++++++--------
>   2 files changed, 21 insertions(+), 11 deletions(-)

Thanks a lot for fixing!

Do you have some reproducer scripts? Could you post them or may be add an 
iotest?

--
Best regards,
Vladimir