Re: [PATCH v2 1/3] mm/gup_benchmark: handle gup failures

[Michael S. Tsirkin]

On Sat, Apr 07, 2018 at 01:08:43PM -0700, Linus Torvalds wrote:
> On Thu, Apr 5, 2018 at 2:03 PM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> >
> >                 nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
> > -               i += nr;
> > +               if (nr > 0)
> > +                       i += nr;
> 
> Can we just make this robust while at it, and just make it
> 
>         if (nr <= 0)
>                 break;
> 
> instead? Then it doesn't care about zero vs negative error, and
> wouldn't get stuck in an endless loop if it got zero.
> 
>              Linus

I don't mind though it alredy breaks out on the next cycle:

                if (nr != gup->nr_pages_per_call)
                        break;

the only issue is i getting corrupted when nr < 0;