[..]
> > > + *
> > > + * @entry: first swap entry from which we want to increase the refcount.
> > > + * @nr: Number of entries in range.
> > > + *
> > > * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
> > > * but could not be atomically allocated. Returns 0, just as if it succeeded,
> > > * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
> > > * might occur if a page table entry has got corrupted.
> > > + *
> > > + * Note that we are currently not handling the case where nr > 1 and we need to
> > > + * add swap count continuation. This is OK, because no such user exists - shmem
> > > + * is the only user that can pass nr > 1, and it never re-duplicates any swap
> > > + * entry it owns.
> >
> > Do we need this comment when we have the WARN + comment in __swap_duplicate()?
>
> Here I'm just being cautious and include the limitation of the
> function in the API documentation itself.
>
> No strong opinions though.
Maybe it would be more useful to add a warning in the loop if nr > 1,
with a comment that explains that the current -ENOMEM handling does
not properly handle nr > 1?
> >
> > > */
> > > -int swap_duplicate(swp_entry_t entry)
> > > +int swap_duplicate_nr(swp_entry_t entry, int nr)
> > > {
> > > int err = 0;
> > >
> > > - while (!err && __swap_duplicate(entry, 1, 1) == -ENOMEM)
> > > + while (!err && __swap_duplicate(entry, 1, nr) == -ENOMEM)
> > > err = add_swap_count_continuation(entry, GFP_ATOMIC);
> > > return err;
> > > }
> > > --
> > > 2.43.5
