Re: iTCO_wdt: watchdog pretimeout panic after KVM guest suspend/resume

[Guenter Roeck]

On 6/30/26 19:46, Evict7837 wrote:
> `Hi,`
>
> `I'd like to report a kernel panic in iTCO_wdt triggered reproducibly after`
> `suspending and resuming a KVM virtual machine host.`
>
> `== Environment ==`
>
> `Host:`
>    `OS:      Ubuntu 24.04.4 LTS`
>    `Kernel:  6.17.0-35-generic`
>    `CPU:     AMD Ryzen 7 6800H`
>    `QEMU:    8.2.2 (Debian 1:8.2.2+ds-0ubuntu1.17)`
>    `libvirt: 10.0.0`
>
> `Guest:`
>    `OS:      Rocky Linux 10.2`
>    `Kernel:  6.12.0-211.26.1.el10_2.x86_64`

This is a pretty old kernel, and it is not an upstream kernel,
meaning it is unknown if any relevant downstream patches have been
applied.

>    `vCPU:    1`
>    `RAM:     1 GiB`
>    `Machine: Q35 + ICH9`
>    `Watchdog device exposed via libvirt XML:`
>      `<watchdog model="itco" action="reset"/>`
>    `Modules loaded: iTCO_wdt, iTCO_vendor_support`
>
> `== Bug Description ==`
>
> `After suspending the KVM host for >= 1 minute and resuming, the guest`
> `kernel panics with "watchdog pretimeout event". The panic is 100%`
> `reproducible with a suspend duration >= 1 minute. Shorter durations`
> `do not trigger the panic.`
>
> `The bug is a regression: it does NOT occur with the Rocky Linux 10.1`

Both Rocky 10.1 and 10.2 are based on upstream Linux v6.12. Whatever
changed between 6.12.0-124.8.1 (which is supposedly the distribution
version number for Rocky 10.1) and 6.12.0-211.26.1 is only known to the
distribution vendor.

This report is not actionable. I would suggest to submit a bug with the
distribution vendor. Please check "Distribution kernels" at
https://www.kernel.org/category/releases.html for additional information.

Thanks,
Guenter