Re: Spinlock debug, was Re: [PATCH RFC] m68k: skip kernel premption if interrupts were disabled

Michael Schmitz
2024-03-30T02:46:19Z

Hi Finn,

Am 29.03.2024 um 08:54 schrieb Michael Schmitz:
> Hi Finn,
>
> Am 28.03.2024 um 15:48 schrieb Finn Thain:
>>> Spinlock recursion in scheduler_tick() doesn't look possible from
>>> reentering scheduler_tick() through code in its call path, so the
>>> mechanism there would be different.
>>>
>>> We did rule out the VIA timer interrupt (or MFP timer A interrupt)
>>> getting reentered, right?
>>>
>>
>> I never added an assertion to prove that because I don't have a way to
>> reproduce the "spinlock recursion" BUG reported by Guenter.
>
> Right. I can reproduce the bug in ARAnyM, so I'll check that the timer
> interrupt isn't reentered there. Doesn't quite amount to the same thing
> though.

The MFP timer C is not reentered in 66 boots even though I've seen it
appear in the stack trace of 8 recursion warnings.

This was with full preempt - no different from earlier when I got a
similar fraction of warnings at boot.

Cheers,

Michael