Re: Linux 6.3-rc2

[Ard Biesheuvel]

On Tue, 14 Mar 2023 at 12:40, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Tue, Mar 14, 2023 at 12:18:33PM +0100, Frederic Weisbecker wrote:
> > How does the following look like as a culprit?
> >
> > 62b95a7b44d1 (ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled)
>
> Ooh yeah, that asm implementation of local_bh_{dis,en}able completely
> miss out on the lockdep state tracking. Also I think it breaks RCU, note
> how __local_bh_disable_ip() explicitly does rcu_read_lock() for the
> first bh-disable.
>

Thanks a lot for the diagnosis, doctor :-)

I may need some hand holding getting this fixed - probably better to
run the C implementations wherever feasible, right?