Re: [PATCH V2] lockdep: fix deadlock issue between lockdep and rcu

[Bart Van Assche]

On 2/1/24 11:48, Boqun Feng wrote:
> raw_spin_lock_irqsave():
>    lock_acquire():
>      __lock_acquire():
>        validate_chain():
>          lookup_chain_cache_add():
>            graph_lock();
>
> Basically, every lock acquisition may lock the lockdep graph because
> of dependency checking.

Wouldn't it be simpler to make __lock_acquire() return early if
this_cpu_read(lockdep_recursion) indicates that the graph lock is held?

Thanks,

Bart.