Re: spinlock recursion when running q800 emulation in qemu

Michael Schmitz
2024-03-05T00:48:59Z

Hi Guenter,

On 5/03/24 13:33, Finn Thain wrote:
> On Mon, 4 Mar 2024, Guenter Roeck wrote:
>
>> when running the q800 qemu emulation, am seeing random "spinlock
>> recursion" messages every few test runs. Some examples are below. This
>> is not a new problem, but it keeps popping up.
>>
> You have to enable CONFIG_DEBUG_SPINLOCK to see it. I have logs from 10
> years ago that show it. Those logs have the VIA timer driver in the
> backtrace, like yours. That was v3.17 running on a PowerBook 180.
>
>> Is this a potential problem or just noise ?
> Maybe the locking validation is not compatible with nested interrupts (?)
Seeing as m68k is the only architecture that allows nesting of
interrupts, I'd rate that as quite likely. At least that's how I
understood the situation a few years back when that weird access past
end of RAM during interrupt accounting bug was discussed.
> Does "spinlock recursion" show up in Aranym as well? I would check for
> that myself but I don't have a reproducer.

If you can give me a hint on what kind of workload that happens at, I'd
be happy to run something similar (if not the same) on my 030 hardware.

I've never set CONFIG_DEBUG_SPINLOCK, so would have missed these
messages, too.

Cheers,

Michael