On Mon, Aug 25, 2025 at 11:43:00PM +0200, Mateusz Guzik wrote:
> __get_file_rcu() bails early:
>
> if (unlikely(!file_ref_get(&file->f_ref)))
> return ERR_PTR(-EAGAIN);
>
> But get_file_rcu():
> for (;;) {
> struct file __rcu *file;
>
> file = __get_file_rcu(f);
> if (!IS_ERR(file))
> return file;
> }
>
> So if this encounters a saturated refcount, the loop with never end.
>
> I don't know what makes the most sense to do here and I'm no position
> to mess with any patches.
>
> This is not a serious problem either, so I would put this on the back
> burner. Just reporting for interested.
That's like past 2^63 - 1 references. Apart from an odd bug is that
really something to worry about. I mean, we can add a VFS_WARN_ON_ONCE()
in there of course but specifically handling that in the code doesn't
seem sensible to me.
