Re: [PATCH memcg v4] net: set proper memcg for net_init hooks allocations

[Michal Koutný]

On Tue, Apr 26, 2022 at 10:23:32PM -0700, Shakeel Butt <shakeelb@xxxxxxxxxx> wrote:
> [...]
> >
> > +static inline struct mem_cgroup *get_mem_cgroup_from_obj(void *p)
> > +{
> > +       struct mem_cgroup *memcg;
> > +
> 
> Do we need memcg_kmem_enabled() check here or maybe
> mem_cgroup_from_obj() should be doing memcg_kmem_enabled() instead of
> mem_cgroup_disabled() as we can have "cgroup.memory=nokmem" boot
> param.

I reckon such a guard is on the charge side and readers should treat
NULL and root_mem_group equally. Or is there a case when these two are
different? 

(I can see it's different semantics when stored in current->active_memcg
(and active_memcg() getter) but for such "outer" callers like here it
seems equal.)

Regards,
Michal