On Thu, Feb 22, 2018 at 6:09 PM, Daniel Colascione <dancol@google.com>
wrote:

> Thanks for taking a look.
>
> On Feb 22, 2018 6:01 PM, "Minchan Kim" <minchan@kernel.org> wrote:
>
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index ad06d42adb1a..f8129afebbdd 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -1507,14 +1507,28 @@ extern int mprotect_fixup(struct vm_area_struct
> *vma,
> >   */
> >  int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
> >                         struct page **pages);
> > +
> > +#ifdef SPLIT_RSS_COUNTING
> > +/* Flush all task-buffered MM counters to the mm */
> > +void sync_mm_rss_all_users(struct mm_struct *mm);
>
> Really heavy functioin iterates all of processes and threads.
>
>
> Just all processes and the threads of each process attached to the mm.
> Maybe that's not much better.
>


Another option would be to maintain a list (with the list_head in the mm)
of all the tasks with unflushed counters. This way, we at least wouldn't
have to scan the world.