Re: commit 894d1b3db41c leads to frequent hangs when booting

[John Stultz]

On Wed, Dec 11, 2024 at 12:44 PM Bert Karwatzki <spasswolf@xxxxxx> wrote:
>
> Am Mittwoch, dem 11.12.2024 um 12:27 -0800 schrieb John Stultz:
> > On Wed, Dec 11, 2024 at 11:19 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > >
> > > On Wed, Dec 11 2024 at 19:25, Bert Karwatzki wrote:
> > > > I tried to debug this with CONFIG_LOCKDEP=y in v6.13-rc2, but using CONFIG_LOCKDEP=y
> > > > makes the hangs disappear or far less likely, and I get this warning
> > > > (2 examples from two boots):
> > > >
> > > > [   17.203857] [   T1337] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
> > >
> > > config LOCKDEP_CHAINS_BITS
> > >         int "Bitsize for MAX_LOCKDEP_CHAINS"
> > >         depends on LOCKDEP && !LOCKDEP_SMALL
> > >         range 10 21
> > >         default 16
> > >         help
> > >           Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
> > >
> > > Can you increase the chain bits config and try again?
> > >
> >
> > Thanks for the report and bisecting this down!
> >
> > Can you double check that the following commit is in your tree? I
> > think it has landed just in the last few days upstream:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=82f9cc094975240885c93effbca7f4603f5de1bf
> >
> > thanks
> > -john
>
> v6.13-rc2 does not contain commit 82f9cc094975, but linux-next-20241210 does
> contain it and shows the same buggy behaviour as v6.13-rc2, I'm currently

:/ hrm.

> testing if linux-next-20241010 can be fixed by the same revert as v6.12-rc2.
>  I didn't bisect this in the linux-next tree to avoid an overlapping bug which
> also caused a hang on boot (this has already been fixed):
> https://lore.kernel.org/linux-mm/CAOQ4uxgVNGmLqURdO0wf3vo=K-a2C--ZLKFzXw-22PJdkBjEdA@xxxxxxxxxxxxxx/T/#t

Could you share the config you're using to reproduce this?

I'll try to work up a few smaller reversions (along with some extra
debug details) to see if we can isolate where things are going awry.

thanks
-john