Re: Crash with PREEMPT_RT on aarch64 machine

[Jan Kara]

On Mon 07-11-22 16:10:34, Sebastian Andrzej Siewior wrote:
> + locking, arm64
> 
> On 2022-11-07 14:56:36 [+0100], Jan Kara wrote:
> > > spinlock_t and raw_spinlock_t differ slightly in terms of locking.
> > > rt_spin_lock() has the fast path via try_cmpxchg_acquire(). If you
> > > enable CONFIG_DEBUG_RT_MUTEXES then you would force the slow path which
> > > always acquires the rt_mutex_base::wait_lock (which is a raw_spinlock_t)
> > > while the actual lock is modified via cmpxchg. 
> > 
> > So I've tried enabling CONFIG_DEBUG_RT_MUTEXES and indeed the corruption
> > stops happening as well. So do you suspect some bug in the CPU itself?
> 
> If it is only enabling CONFIG_DEBUG_RT_MUTEXES (and not whole lockdep)
> then it looks very suspicious. 

Just to confirm, CONFIG_DEBUG_RT_MUTEXES is the only thing I've enabled and
the list corruption disappeared.

								Honza

-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR