Messages in this thread | | | From | Alistair Popple <> | Subject | Re: [PATCH v2] mm/gup.c: Fix return value for __gup_longterm_locked() | Date | Tue, 23 Aug 2022 11:15:29 +1000 |
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Shigeru Yoshida <syoshida@redhat.com> writes:
> __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 > requested.
Thanks for fixing this, I've been out the last few days so just catching up. I think I missed that 'rc' was passed as nr_pages into check_and_migrate_movable_pages(). Will double check that I don't make the same mistake in my latest series.
> Fixes: 61c63c2076d9 (mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes)
I couldn't find that SHA1, I'm guessing due to rebasing, etc. of mm-unstable? Not sure how that is dealt with, but feel free to also add:
Reviewed-by: Alistair Popple <apopple@nvidia.com>
> CC: Alistair Popple <apopple@nvidia.com> > Reported-by: syzbot+616ff0452fec30f4dcfd@syzkaller.appspotmail.com > Reviewed-by: John Hubbard <jhubbard@nvidia.com> > Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> > --- > mm/gup.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 5aa7531a703b..66582203220a 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2068,22 +2068,24 @@ 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); > + 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); > } 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)
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