Re: [RFC-PATCH 2/4] mm: Add __rcu_alloc_page_lockless() func.

Peter Zijlstra
2020-09-25T08:16:01Z

On Thu, Sep 24, 2020 at 05:21:12PM +0200, Uladzislau Rezki wrote:
> On Thu, Sep 24, 2020 at 01:19:07PM +0200, Peter Zijlstra wrote:
> > On Thu, Sep 24, 2020 at 10:16:14AM +0200, Uladzislau Rezki wrote:
> > > The key point is "enough". We need pages to make a) fast progress b) support
> > > single argument of kvfree_rcu(one_arg). Not vice versa. That "enough" depends
> > > on scheduler latency and vague pre-allocated number of pages, it might
> > > be not enough what would require to refill it more and more or we can overshoot
> > > that would lead to memory overhead. So we have here timing issues and
> > > not accurate model. IMHO.
> >
> > I'm firmly opposed to the single argument kvfree_rcu() idea, that's
> > requiring memory to free memory.
> >
> Hmm.. The problem is there is a demand in it:

People demand ponies all the time, the usual answer is: No.