On Mon, Feb 10, 2025 at 09:18:04PM +0000, Matthew Wilcox wrote:
> On Tue, Feb 11, 2025 at 08:09:31AM +1100, Dave Chinner wrote:
> > Better to only do the FGP_NOWAIT check when a failure occurs; that
> > puts it in the slow path rather than having to evaluate it
> > unnecessarily every time through the function/loop. i.e.
> >
> > folio = filemap_alloc_folio(gfp, order);
> > - if (!folio)
> > - return ERR_PTR(-ENOMEM);
> > + if (!folio) {
> > + if (fgp_flags & FGP_NOWAIT)
> > + err = -EAGAIN;
> > + else
> > + err = -ENOMEM;
> > + continue;
> > + }
>
> Or would we be better off handling ENOMEM the same way we handle EAGAIN?
> eg something like:
>
> +++ b/io_uring/io_uring.c
> @@ -1842,7 +1842,7 @@ void io_wq_submit_work(struct io_wq_work *work)
>
> do {
> ret = io_issue_sqe(req, issue_flags);
> - if (ret != -EAGAIN)
> + if (ret != -EAGAIN || ret != -ENOMEM)
> break;
This still allows -ENOMEM to escape to userspace instead of -EAGAIN
via pwritev2(RWF_NOWAIT) and AIO write interfaces.
-Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
