Re: [PATCH v3 5/6] mm/gup: migrate pinned pages out of movable zone

[Michal Hocko]

On Mon 14-12-20 15:21:21, David Hildenbrand wrote:
> On 14.12.20 14:36, Jason Gunthorpe wrote:
> > On Sat, Dec 12, 2020 at 08:29:11AM +0100, David Hildenbrand wrote:
> > 
> >>> Racing with another GUP in another thread is also not reasonable, so
> >>> failing to isolate can't be a failure
> >>
> >> Having VMs with multiple vfio containers is certainly realistic, and
> >> optimizing in user space to do vfio mappings concurrently doesn‘t
> >> sound too crazy to me. But I haven‘t checked if vfio common code
> >> already handles such concurrency.
> > 
> > There is a lot more out there than vfio.. RDMA already does concurrent
> > pin_user_pages in real apps
> 
> I actually misread your comment. I think we both agree that temporary
> isolation failures must not lead to a failure.

Yes, isolation failures are ephemeral. I believe that the migration
should start distinguishing between these and hard failures.
-- 
Michal Hocko
SUSE Labs