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Re: [PATCH 0/3] block/nbd: fix crashers in reconnect while migrating
From: |
Roman Kagan |
Subject: |
Re: [PATCH 0/3] block/nbd: fix crashers in reconnect while migrating |
Date: |
Fri, 29 Jan 2021 10:35:27 +0300 |
On Fri, Jan 29, 2021 at 08:51:39AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> 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?
I don't have it scripted, just ad hoc command lines. I'll look into
making up a test. Can you perhaps suggest what existing test to base
on?
Thanks,
Roman.