Re: [Qemu-devel][bug] qemu crash when migrate vm and vm's disks

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Yuchen <yu.chen@h3c.com>, pbonzini@redhat.com, mst@redhat.com
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel][bug] qemu crash when migrate vm and vm's disks
Date: Thu, 8 Apr 2021 12:27:01 +0100	[thread overview]
Message-ID: <YG7ohYazszYMnb7k@work-vm> (raw)
In-Reply-To: <9cd6ccabceff42f9afbaed917f77c9b2@h3c.com>

* Yuchen (yu.chen@h3c.com) wrote:
> When migrate vm and vm’s disks target host qemu crash due to an invalid free.
> 
> #0  object_unref (obj=0x1000) at /qemu-2.12/rpmbuild/BUILD/qemu-2.12/qom/object.c:920
> #1  0x0000560434d79e79 in memory_region_unref (mr=<optimized out>)
>     at /qemu-2.12/rpmbuild/BUILD/qemu-2.12/memory.c:1730
> #2  flatview_destroy (view=0x560439653880) at /qemu-2.12/rpmbuild/BUILD/qemu-2.12/memory.c:292
> #3  0x000056043514dfbe in call_rcu_thread (opaque=<optimized out>)
>     at /qemu-2.12/rpmbuild/BUILD/qemu-2.12/util/rcu.c:284
> #4  0x00007fbc2b36fe25 in start_thread () from /lib64/libpthread.so.0
> #5  0x00007fbc2b099bad in clone () from /lib64/libc.so.6
> 
> test base qemu-2.12.0，but use lastest qemu(v6.0.0-rc2) also reproduce.

Interesting.

> As follow patch can resolve this problem:
> https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02272.html

That's a pci/rcu change; ccing Paolo and Micahel.

> Steps to reproduce:
> (1) Create VM (virsh define)
> (2) Add 64 virtio scsi disks

Is that hot adding the disks later, or are they included in the VM at
creation?
Can you provide a libvirt XML example?

> (3) migrate vm and vm’disks

What do you mean by 'and vm disks' - are you doing a block migration?

Dave

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