From: Juergen Gross <jgross@suse.com>
To: glenn@rimuhosting.com, xen-devel@lists.xen.org
Subject: Re: null domains after xl destroy
Date: Tue, 11 Apr 2017 07:59:39 +0200 [thread overview]
Message-ID: <95efee87-6925-5376-e347-55e438c90212@suse.com> (raw)
In-Reply-To: <78571a7b-62ec-b046-02e3-3d6739b779a6@rimuhosting.com>
On 11/04/17 07:25, Glenn Enright wrote:
> Hi all
>
> We are seeing an odd issue with domu domains from xl destroy, under
> recent 4.9 kernels a (null) domain is left behind.
I guess this is the dom0 kernel version?
> This has occurred on a variety of hardware, with no obvious commonality.
>
> 4.4.55 does not show this behavior.
>
> On my test machine I have the following packages installed under
> centos6, from https://xen.crc.id.au/
>
> ~]# rpm -qa | grep xen
> xen47-licenses-4.7.2-4.el6.x86_64
> xen47-4.7.2-4.el6.x86_64
> kernel-xen-4.9.21-1.el6xen.x86_64
> xen47-ocaml-4.7.2-4.el6.x86_64
> xen47-libs-4.7.2-4.el6.x86_64
> xen47-libcacard-4.7.2-4.el6.x86_64
> xen47-hypervisor-4.7.2-4.el6.x86_64
> xen47-runtime-4.7.2-4.el6.x86_64
> kernel-xen-firmware-4.9.21-1.el6xen.x86_64
>
> I've also replicated the issue with 4.9.17 and 4.9.20
>
> To replicate, on a cleanly booted dom0 with one pv VM, I run the
> following on the VM
>
> {
> while true; do
> dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync
> done
> }
>
> Then on the dom0 I do this sequence to reliably get a null domain. This
> occurs with oxenstored and xenstored both.
>
> {
> xl sync 1
> xl destroy 1
> }
>
> xl list then renders something like ...
>
> (null) 1 4 4 --p--d
> 9.8 0
Something is referencing the domain, e.g. some of its memory pages are
still mapped by dom0.
> From what I can see it appears to be disk related. Affected VMs all use
> lvm storage for their boot disk. lvdisplay of the affected lv shows that
> the lv has is being help open by something.
How are the disks configured? Especially the backend type is important.
>
> ~]# lvdisplay test/test.img | grep open
> # open 1
>
> I've not been able to determine what that thing is as yet. I tried lsof,
> dmsetup, various lv tools. Waiting for the disk to be released does not
> work.
>
> ~]# xl list
> Name ID Mem VCPUs State
> Time(s)
> Domain-0 0 1512 2 r-----
> 29.0
> (null) 1 4 4 --p--d
> 9.8
>
> xenstore-ls reports nothing for the null domain id that I can see.
Any qemu process related to the domain still running?
Any dom0 kernel messages related to Xen?
Juergen
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next prev parent reply other threads:[~2017-04-11 5:59 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 5:25 null domains after xl destroy Glenn Enright
2017-04-11 5:59 ` Juergen Gross [this message]
2017-04-11 8:03 ` Glenn Enright
2017-04-11 9:49 ` Dietmar Hahn
2017-04-11 22:13 ` Glenn Enright
2017-04-11 22:23 ` Andrew Cooper
2017-04-11 22:45 ` Glenn Enright
2017-04-18 8:36 ` Juergen Gross
2017-04-19 1:02 ` Glenn Enright
2017-04-19 4:39 ` Juergen Gross
2017-04-19 7:16 ` Roger Pau Monné
2017-04-19 7:35 ` Juergen Gross
2017-04-19 10:09 ` Juergen Gross
2017-04-19 16:22 ` Steven Haigh
2017-04-21 8:42 ` Steven Haigh
2017-04-21 8:44 ` Juergen Gross
2017-05-01 0:55 ` Glenn Enright
2017-05-03 10:45 ` Steven Haigh
2017-05-03 13:38 ` Juergen Gross
2017-05-03 15:53 ` Juergen Gross
2017-05-03 16:58 ` Steven Haigh
2017-05-03 22:17 ` Glenn Enright
2017-05-08 9:10 ` Juergen Gross
2017-05-09 9:24 ` Roger Pau Monné
2017-05-13 4:02 ` Glenn Enright
2017-05-15 9:57 ` Juergen Gross
2017-05-16 0:49 ` Glenn Enright
2017-05-16 1:18 ` Steven Haigh
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