Re: [PATCHv5 2/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path

Pingfan Liu
2020-03-02T02:29:00Z

On Sat, Feb 29, 2020 at 6:34 AM Ira Weiny <ira.weiny@intel.com> wrote:
>
> On Fri, Feb 28, 2020 at 07:32:29PM +0800, Pingfan Liu wrote:
> > FOLL_LONGTERM suggests a pin which is going to be given to hardware and
> > can't move. It would truncate CMA permanently and should be excluded.
>
> I don't understand what is 'truncated' here?
a pinned page will truncate a continuous area, and prevent CMA to
reclaim the continuous area.
>
> I generally agree with Jason that this is going to be confusing to the user.
Please see the reply in anothe mail.

Thanks,
Pingfan …