Re: [RFC v2 PATCH] mm/percpu.c: fix panic triggered by BUG_ON() falsely

From: Tejun Heo
Date: Thu Oct 13 2016 - 20:25:16 EST


On Fri, Oct 14, 2016 at 08:06:10AM +0800, zijun_hu wrote:
> > I really can't decode what the actual issue is here. Can you please
> > give an example of a concrete case?
> >
> the right relationship between the number of CPUs @nr_cpus within a percpu group
> and the number of unites @nr_units within the same group is that
> @nr_units == roundup(@nr_cpus, @upa);

My question was whether there can be actual hardware configurations
where this code can fail and if so what they look like and how they
would fail.