Re: Linux 6.3-rc2

[Guenter Roeck]

On 3/13/23 15:16, Linus Torvalds wrote:
> On Mon, Mar 13, 2023 at 1:30 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > It gets weird. Bisect log below. Reverting the identified patch does
> > indeed seem to fix the problem, only I have no clue why this might
> > be the case. The patch looks completely innocent to me. Yet, I can
> > reliably reproduce the problem with v6.3-rc2, but at least so far I
> > have not been able to reproduce it with commit f3dd0c53370 reverted
> > (and I am trying on five different servers in parallel).
>
> Yeah, that commit looks very innocuous. I'm surprised it would even
> change any code generation, but it's very possible that it ends up
> affecting some code layout or something almost by mistake.
>
> I'd be inclined to think that the problem is very timing-sensitive,
> and has probably been there for a while, and some random moon phase
> just made it happen now.

Maybe, but it seems unlikely. I can reliably reproduce the problem
with v6.3-rc2. Typically it takes some 20-30 boot attempts to see it. With
f3dd0c53370 reverted I tried more than 1,000 boot attempts and did not see
the problem. I also don't recall ever having seen it before.

Anyway, I'll probably just disable CONFIG_DEBUG_LOCK_ALLOC for my
arm boot tests to avoid the message. I don't want it to create noise
and hide other problems.

Thanks,
Guenter