Subject: Re: [PATCH 00/14] replace call_rcu by kfree_rcu for simple kmem_cache_free callback

From: Uladzislau Rezki <[email-masked]>
Date: Mon, 17 Jun 2024 18:42:23 +0200

On Mon, Jun 17, 2024 at 06:33:23PM +0200, Jason A. Donenfeld wrote:
> On Mon, Jun 17, 2024 at 6:30 PM Uladzislau Rezki <[email-masked]> wrote:
> > Here if an "err" is less then "0" means there are still objects
> > whereas "is_destroyed" is set to "true" which is not correlated
> > with a comment:
> >
> > "Destruction happens when no objects"
> 
> The comment is just poorly written. But the logic of the code is right.
> 
OK.

> >
> > >  out_unlock:
> > >       mutex_unlock(&slab_mutex);
> > >       cpus_read_unlock();
> > > diff --git a/mm/slub.c b/mm/slub.c
> > > index 1373ac365a46..7db8fe90a323 100644
> > > --- a/mm/slub.c
> > > +++ b/mm/slub.c
> > > @@ -4510,6 +4510,8 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
> > >               return;
> > >       trace_kmem_cache_free(_RET_IP_, x, s);
> > >       slab_free(s, virt_to_slab(x), x, _RET_IP_);
> > > +     if (s->is_destroyed)
> > > +             kmem_cache_destroy(s);
>
Here i am not follow you. How do you see that a cache has been fully
freed? Or is it just super draft code?

Thanks!

--
Uladzislau Rezki