[CentOS-virt] Xen PV DomU running Kernel 4.14.5-1.el7.elrepo.x86_64: xl -v vcpu-set <domU> <val> triggers domU kernel WARNING, then domU becomes unresponsive

Thu Dec 14 17:10:38 UTC 2017
Akemi Yagi <amyagi at gmail.com>

On Mon, Dec 11, 2017 at 4:52 PM, Adi Pircalabu <adi at ddns.com.au> wrote:

> Has anyone seen this recently? I couldn't replicate it on:
> - CentOS 6 running kernel-2.6.32-696.16.1.el6.x86_64,
> kernel-lt-4.4.105-1.el6.elrepo.x86_64
> - CentOS 7 running 4.9.67-1.el7.centos.x86_64
>
> But I can replicate it consistently running "xl -v vcpu-set <domU> <val>"
> on:
> - CentOS 6 running 4.14.5-1.el6.elrepo.x86_64
> - CentOS 7 running 4.14.5-1.el7.elrepo.x86_64
>
> dom0 versions tested with similar results in the domU:
> - 4.6.6-6.el7 on kernel 4.9.63-29.el7.x86_64
> - 4.6.3-15.el6 on kernel 4.9.37-29.el6.x86_64
>
> Noticed behaviour:
> - These commands stall:
> top
> ls -l /var/tmp
> ls -l /tmp
> - Stuck in D state on the CentOS 7 domU:
> root         5  0.0  0.0      0     0 ?        D    11:20   0:00
> [kworker/u8:0]
> root       316  0.0  0.0      0     0 ?        D    11:20   0:00
> [jbd2/xvda1-8]
> root      1145  0.0  0.2 116636  4776 ?        Ds   11:20   0:00 -bash
> root      1289  0.0  0.1  25852  2420 ?        Ds   11:35   0:00
> /usr/bin/systemd-tmpfiles --clean
> root      1290  0.0  0.1 125248  2696 pts/1    D+   11:44   0:00 ls
> --color=auto -l /tmp/
> root      1293  0.0  0.1 125248  2568 pts/2    D+   11:44   0:00 ls
> --color=auto -l /var/tmp
> root      1296  0.0  0.2 116636  4908 pts/3    Ds+  11:44   0:00 -bash
> root      1358  0.0  0.1 125248  2612 pts/4    D+   11:47   0:00 ls
> --color=auto -l /var/tmp
>
> At a first glance it appears the issue is in 4.14.5 kernel. Stack traces
> follow:
>
> Adi Pircalabu


Can you test-install 4.15-rcX​

 to see if the problem persists in the latest kernel?:

​http://elrepo.org/people/ajb/devel/kernel-ml/el7/x86_64/RPMS/

Akemi
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