Re: [WARNING] kernel/rcu/tree.c:1058 rcu_irq_enter+0x15/0x20

[Peter Zijlstra]

On Fri, Oct 02, 2020 at 01:56:44PM -0400, Steven Rostedt wrote:
> On Wed, 30 Sep 2020 20:13:23 +0200
> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> > Blergh, IIRC there's header hell that way. The sane fix is killing off
> > that trace_*_rcuidle() disease.
> > 
> > But I think this will also cure it.
> 
> I guess you still don't build modules ;-). I had to add a
> EXPORT_SYMBOL(lockdep_recursion) to get it to build, and then move the

Correct, my regular configs are all without modules.

> checks within the irq disabling to get rid of the using cpu pointers within
> preemptable code warnings

Ah, I think I lost a s/__this_cpu_read/raw_cpu_read/ somewhere. The
thing is, if we're preemptible/migratable it will be 0 on both CPUs and
it doesn't matter which 0 we read. If it is !0, IRQs will be disabled
and we can't get migrated.

Anyway, let me go write a Changelog to go with it.