| Message ID | 20220821183547.950370-1-syoshida@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/gup.c: Fix return value for __gup_longterm_locked() | expand |
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,
On Mon, Aug 22, 2022 at 9:14 AM John Hubbard <jhubbard@nvidia.com> wrote: > 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> > Hi John, Thank you so much for your review. I'll send v2 patch. Shigeru > > (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 > >
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); + 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)
__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. 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(-)