Messages in this thread | | | Date | Sun, 21 Aug 2022 17:14:01 -0700 | Subject | Re: [PATCH] mm/gup.c: Fix return value for __gup_longterm_locked() | From | John Hubbard <> |
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On 8/21/22 11:35, Shigeru Yoshida wrote: > __get_user_pages_locked() may return the number of pages less than > nr_pages. So __gup_longterm_locked() have to return the number of > pages __get_user_pages_locked() returns if it succeeded, not nr_pages > passed.
s/passed/requested/
> > Fixes: 61c63c2076d9 (mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes) > CC: Alistair Popple <apopple@nvidia.com> > Reported-by: syzbot+616ff0452fec30f4dcfd@syzkaller.appspotmail.com > Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> > --- > mm/gup.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-)
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
(with a couple of nits about line length, below)
> > diff --git a/mm/gup.c b/mm/gup.c > index 5aa7531a703b..542cf74c59b0 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2068,22 +2068,22 @@ static long __gup_longterm_locked(struct mm_struct *mm, > unsigned int gup_flags) > { > unsigned int flags; > - long rc; > + long rc, nr_pinned_pages; > > if (!(gup_flags & FOLL_LONGTERM)) > return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, > NULL, gup_flags); > flags = memalloc_pin_save(); > do { > - rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, > - NULL, gup_flags); > - if (rc <= 0) > + nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, > + NULL, gup_flags);
Can you please wrap at 80 cols, though?
> + if (nr_pinned_pages <= 0) > break; > - rc = check_and_migrate_movable_pages(rc, pages, gup_flags); > + rc = check_and_migrate_movable_pages(nr_pinned_pages, pages, gup_flags);
Also here.
> } while (rc == -EAGAIN); > memalloc_pin_restore(flags); > > - return rc ? rc : nr_pages; > + return rc ? rc : nr_pinned_pages; > } > > static bool is_valid_gup_flags(unsigned int gup_flags)
thanks, -- John Hubbard NVIDIA
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