On Mon, Feb 24, 2025 at 12:49 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Mon, Feb 24, 2025 at 12:45:21PM -0300, Raphael S. Carvalho wrote:
> > On Mon, Feb 24, 2025 at 12:33 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> > >
> > > On Mon, Feb 24, 2025 at 03:17:44PM +0100, Christoph Hellwig wrote:
> > > > On Mon, Feb 24, 2025 at 05:13:28AM -0300, Raphael S. Carvalho wrote:
> > > > > + if (err) {
> > > > > + /* Prevents -ENOMEM from escaping to user space with FGP_NOWAIT */
> > > > > + if ((fgp_flags & FGP_NOWAIT) && err == -ENOMEM)
> > > > > + err = -EAGAIN;
> > > > > return ERR_PTR(err);
> > > >
> > > > I don't think the comment is all that useful. It's also overly long.
> > > >
> > > > I'd suggest this instead:
> > > >
> > > > /*
> > > > * When NOWAIT I/O fails to allocate folios this could
> > > > * be due to a nonblocking memory allocation and not
> > > > * because the system actually is out of memory.
> > > > * Return -EAGAIN so that there caller retries in a
> > > > * blocking fashion instead of propagating -ENOMEM
> > > > * to the application.
> > > > */
> > >
> > > I don't think it needs a comment at all, but the memory allocation
> > > might be for something other than folios, so your suggested comment
> > > is misleading.
> >
> > Isn't it all in the context of allocating or adding folio? The reason
> > behind a comment is to prevent movements in the future that could
> > cause a similar regression, and also to inform the poor reader that
> > might be left wondering why we're converting -ENOMEM into -EAGAIN with
> > FGP_NOWAIT. Can it be slightly adjusted to make it more correct? Or
> > you really think it's better to remove it completely?
>
> I really don't think the comment is needed. This is a common mistake
> when fixing a bug.
Ok, so I will proceed with v4 now, removing the comment.
