On Mon, 3 Mar 2025 11:47:11 -0500
Steven Rostedt <rost...@goodmis.org> wrote:
> > [ 92.322619][ T28] ? srcu_gp_start_if_needed+0x1a9/0x5f0
> > [ 92.322636][ T28] srcu_gp_start_if_needed+0x1a9/0x5f0
>
> The lock taken is from the passed in rcu_pending pointer.
>
> > [ 92.322655][ T28] rcu_pending_enqueue+0x686/0xd30
I figured out what likely triggered the lockdep warning too. I thought
rcu_pending_equeue() was an internal RCU function, but then when I looked
at what directory it was in (found it in emacs so I only saw the file name
and not the path), I see that function is internal to bcachefs.
That function also has:
local_irq_save(flags);
p = this_cpu_ptr(pending->p);
spin_lock(&p->lock);
That is a sure sign of an RT disaster waiting to happen. As in PREEMPT_RT
that spin_lock turns into a mutex, and just before, you disable interrupts.
And yes, lockdep will report that as a bug.
-- Steve
