Re: 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal()

[Thomas Gleixner]

On Wed, Jul 28 2021 at 12:21, Paolo Bonzini wrote:
> On 28/07/21 10:06, Thomas Gleixner wrote:
>> On Wed, Jul 14 2021 at 12:35, Paolo Bonzini wrote:
>> Yes, that cures it, but if you think about what this wants to prevent,
>> then having the recursion counter per CPU is at least suboptimal.
>> 
>> Something like the untested below perhaps?
>
> Yes, that works (it should just be #ifdef CONFIG_EVENTFD).

Yup and it lacks an include.

> On !PREEMPT_RT the percpu variable consumes memory while your patch uses 
> none (there are plenty of spare bits in current), but it is otherwise 
> basically the same.  On PREEMPT_RT the local_lock is certainly more 
> expensive.

Let me send a proper patch for that.

Thanks,

        tglx