Re: [PATCH] [suggestion] mm/gup: avoid IS_ERR_OR_NULL

From: Jason Gunthorpe
Date: Sat May 27 2023 - 05:52:18 EST

On Sat, May 20, 2023 at 10:12:40AM +0100, Lorenzo Stoakes wrote:
> > No, this returning 0 on failure is a foot gun. Failing to pin a single
> > page is always an error, the only question is what sub reason caused
> > the error to happen. There is no third case where it is not an error.
> The uprobe path thinks otherwise, but maybe the answer is that we just need
> to -EFAULT on missing VMA and -EPERM on invalid flags.

I think uprobe is just broken to think there is a third outcome. Let's
just fix it instead of trying to pretend it makes sense.