Re: Possible bug? DOM-U network stopped working after fatal error reported in DOM0

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

On Sun, Dec 19, 2021 at 2:35 AM G.R. <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi all,
>
> I ran into the following error report in the DOM0 kernel after a recent 
> upgrade:
> [  501.840816] vif vif-1-0 vif1.0: Cross page boundary, txp->offset:
> 2872, size: 1460
> [  501.840828] vif vif-1-0 vif1.0: fatal error; disabling device
> [  501.841076] xenbr0: port 2(vif1.0) entered disabled state
> Once this error happens, the DOM-U behind this vif is no-longer
> accessible. And recreating the same DOM-U does not fix the problem.
> Only a reboot on the physical host machine helps.
>
> The problem showed up after a recent upgrade on the DOM-U OS from
> FreeNAS 11.3 to TrueNAS 12.0U7 and breaks the iSCSI service while
> leaving other services like NFS intact.
To clarify -- mounting iSCSI disk will cause the problem immediately.

> The underlying OS for the NAS is FreeBSD, version 11.3 and 12.2 respectively.
> So far I have tried the following combos:
> - Linux 4.19 DOM0 + XEN 4.8 + FreeBSD 11.3 DOM-U: Good
> - Linux 4.19 DOM0 + XEN 4.8 + FreeBSD 12.2 DOM-U: Regressed
> - Linux 5.10 DOM0 + XEN 4.8 + FreeBSD 12.2 DOM-U: Regressed
> - Linux 5.10 DOM0 + XEN 4.11 + FreeBSD 12.2 DOM-U: Regressed
- Linux 5.10 DOM0 + XEN 4.14 + FreeBSD 12.2 DOM-U: Regressed
>
> I plan to try out the XEN 4.14 version which is the latest I can get
> from the distro (Debian).
I just upgraded to Debian bullseye (11) from buster (10) and migrated
to XEN4.14 as a result.
The syndrome persists, unfortunately.
BTW, my Dom0 kernel is a custom built version. Does any kernel config
could contribute to this problem?

> If that still does not fix the problem, I would build the 4.16 version
> from source as my last resort.
>
> I have to admit that this trial process is blind as I have no idea
> which component in the combo is to be blamed. Is it a bug in the
> backend-driver, frontend-driver or the hypervisor itself? Or due to
> incompatible versions? Any suggestion on other diagnose ideas (e.g.
> debug logs) will be welcome, while I work on the planned experiments.
>
> Thanks,
> G.R.