Setting MTU on interface in down state freezes system

[desooo]

Hello people,
I encountered the strangest issue I ever experienced so far: When I set the MTU on an interface which is down, my system freezes completely after around 10 seconds.
Also in about 10% of the freezes my system will shutdown and reboot right away.

I can reproduce it like this:

[Hu]

I would assume hardware first, on the grounds that this seems like a fairly reasonable thing for people to do, and if a kernel bug was at fault, it would have been reported. It's possible that you're just the first to find a kernel bug, though. wrfl is a macro that expands to a call to igb_rd32. In turn, that function reads a value from the hardware and returns it. You could try adding more logging there, but the function is so simple that I do not see how this can fail unless reading a hardware register hangs.

If you trigger this while at a text console, does the kernel print anything useful before the system hangs?

Generally, sysrq should work unless the kernel has panicked or the hardware has stopped running Linux. I have seen boards that would fail hard enough that the kernel stopped running.

Has this system ever been able to do this successfully?

[desooo]