As I already reported mkiss never triggered any Oops kernel panic up to 
linux-6.14.11.

In that version I put a number of printk inside of mkiss.c in order to 
follow the normal behaviour and content outside and during FPAC 
functionning especially when issuing a connect request.

On the opposite an FPAC connect request systematically triggers a kernel 
panic with linux-6.15.2 and following kernels.

In 6.14.11 I observe that when mkiss runs core/dev is never activated 
i.e. neither __netif_receive_skb nor __netif_receive_skb_one_core.

These functions appear in kernel 6.15.2 panics after mkiss_receive_buf.

One can guess that mkiss_receive_buf() is triggering something wrong in 
kernel 6.15.2 and all following kernels up to net-next.

The challenge to locate the bug is quite difficult as I did not find the 
way to find relevant code differences between both kernels in absence of 
inc patch...

I sincerely regret not knowing how to go further.

Bernard,
hamradio f6bvp /ai7bg