Re: [PATCH (repost)] locking/lockdep: add debug_show_all_lock_holders()

[Boqun Feng]

On Fri, Sep 16, 2022 at 10:51:14AM -0400, Waiman Long wrote:
[...]
> > 
> > I'm expecting lockdep to continue working without calling printk() even after
> > one of problem patterns (e.g. circular locking dependency) was printk()ed, so that
> > debug_show_all_locks()/debug_show_all_lock_holders() can call printk() when needed.
> > 
> > Changing debug_locks behavior is a future patch. For now, this patch alone
> > will help debugging Greg's usb.git#usb-testing tree which is generating
> > many "INFO: task hung in" reports.

The default behavior today does make sense: if the system has one
deadlock it should be fixed first before searching out another. So I
expect that changing debug_locks behavior would be configurable and we
keep the default as today.

> 
> Boqun is actually working on a modularization patch to make some lockdep
> checking still active even after a lockdep bug is reported. I think he will
> take into consideration about this request.
> 

Yes, this is one of the "problems" I try to resolve while cleaning up
the lockdep.

Regards,
Boqun

> Cheers,
> Longman
>