Subject: Re: next-20250327 - lockdep whine and USB issues at boot

From: Ming Lei <[email-masked]>
Date: Mon, 31 Mar 2025 17:21:01 +0800

On Sat, Mar 29, 2025 at 02:02:10AM -0400, Valdis Klētnieks wrote:
> On Sat, 29 Mar 2025 10:06:39 +0800, Ming Lei said:
> > On Fri, Mar 28, 2025 at 02:10:53PM -0400, Valdis Kl??tnieks wrote:
> > > Saw this during boot on a Dell Inspiron 5559 laptop.  
> > > 
> > > In addition, the external USB ports all gave up, rendering a USB mouse and a
> > > USB external drive totally dead in the water.  May or may not be related, I didn't
> > > dig too far into it.
> >
> > It shouldn't be related to the warning.
> 
> > For this lockdep warning, feel free to try patch in the following link:
> >
> > https://lore.kernel.org/linux-block/Z-dUCLvf06SfTOHy@fedora/
> 
> After applying that patch, USB *didn't* die during boot.  So apparently
> *something* changed.  

That is surprising, and maybe the USB die isn't 100% thing.

> 
> Also, the patch merely caused a *different* lockdep warning.
> Rather than  &q->q_usage_counter(io) and &q->elevator_lock, the
> new one is &q->elevator_lock versus pcpu_alloc_mutex...
> 
> Looks like it's a bit more convoluted than first looked?

That is another story wrt. freeze lock, fs_reclaim & percpu allocator
lock, looks one real risk, I will try to work one patch and see if
all can be addressed.

Thanks,
Ming