Re: [PATCH] mm: Unsigned 'nr_pages' always larger than zero

[Andrew Morton]

On Wed, 16 Oct 2019 17:07:44 +0800 zhong jiang <zhongjiang@xxxxxxxxxx> wrote:

> >> --- a/mm/gup.c~a
> >> +++ a/mm/gup.c
> >> @@ -1450,6 +1450,7 @@ static long check_and_migrate_cma_pages(
> >>       bool drain_allow = true;
> >>       bool migrate_allow = true;
> >>       LIST_HEAD(cma_page_list);
> >> +    long ret;
> >>     check_again:
> >>       for (i = 0; i < nr_pages;) {
> >> @@ -1511,17 +1512,18 @@ check_again:
> >>            * again migrating any new CMA pages which we failed to isolate
> >>            * earlier.
> >>            */
> >> -        nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages,
> >> +        ret = __get_user_pages_locked(tsk, mm, start, nr_pages,
> >>                              pages, vmas, NULL,
> >>                              gup_flags);
> >>   -        if ((nr_pages > 0) && migrate_allow) {
> >> +        nr_pages = ret;
> >> +        if (ret > 0 && migrate_allow) {
> >>               drain_allow = true;
> >>               goto check_again;
> >>           }
> >>       }
> >>   -    return nr_pages;
> >> +    return ret;
> >>   }
> >>   #else
> >>   static long check_and_migrate_cma_pages(struct task_struct *tsk,
> >>
> >
> > +1 for this approach, please.
> >
> >
> > thanks,
> Hi,  Andrew
> 
> I didn't see the fix for the issue in the upstream. Your proposal should be
> appiled to upstream. Could you appiled the patch or  repost by me ?

Forgotten about it ;)  Please send a patch sometime?