Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude protection

[Michal Hocko]

On Wed 29-05-19 23:44:53, Chris Down wrote:
> Michal Hocko writes:
> > Maybe I am missing something so correct me if I am wrong but the new
> > calculation actually means that we always allow to scan even min
> > protected memcgs right?
> 
> We check if the memcg is min protected as a precondition for coming into
> this function at all, so this generally isn't possible. See the
> mem_cgroup_protected MEMCG_PROT_MIN check in shrink_node.

OK, that is the part I was missing, I got confused by checking the min
limit as well here. Thanks for the clarification. A comment would be
handy or do we really need to consider min at all?

> (Of course, it's possible we race with going within protection thresholds
> again, but this patch doesn't make that any better or worse than the
> previous situation.)

Yeah.

With the above clarified. The code the resulting code is much easier to
follow and the overal logic makes sense to me.

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

-- 
Michal Hocko
SUSE Labs