Re: [External] Re: [PATCH v2 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one

[Michal Hocko]

On Thu 07-01-21 10:52:21, Muchun Song wrote:
> On Thu, Jan 7, 2021 at 12:13 AM Michal Hocko <mhocko@xxxxxxxx> wrote:
> >
> > On Wed 06-01-21 16:47:34, Muchun Song wrote:
> > > If the refcount is one when it is migrated, it means that the page
> > > was freed from under us. So we are done and do not need to migrate.
> >
> > Is this common enough that it would warrant the explicit check for each
> > migration?
> 
> Are you worried about the overhead caused by the check? Thanks.

I am not as worried as I would like to see some actual justification for
this optimization.
-- 
Michal Hocko
SUSE Labs