Re: [GIT PULL] ext4 changes for the 6.4 merge window

[Matthew Wilcox]

On Wed, Apr 26, 2023 at 10:03:37AM -0700, Linus Torvalds wrote:
> On Mon, Apr 24, 2023 at 9:18 PM Theodore Ts'o <tytso@xxxxxxx> wrote:
> >
> > Please note that after merging the mm and ext4 trees you will need to
> > apply the patch found here[1].
> >
> > [1] https://lore.kernel.org/r/20230419120923.3152939-1-willy@xxxxxxxxxxxxx
> >
> > This is due to a patch in the mm tree, "mm: return an ERR_PTR from
> > __filemap_get_folio" changing that function to returning an ERR_PTR
> > instead of returning NULL on an error.
> 
> Side note, itr would be wonderful if we could mark the places that
> return an error pointer as returning "nonnull", and catch things like
> this automatically at build time where people compare an error pointer
> to NULL.

This feels like something smatch could catch.  Adding Dan.

Unfortunately, I don't know that we have any buildbots that run smatch,
and most developers don't, so it'll always be an after-the-fact patch
to fix it rather than "anybody using W=1" or "anybody using C=1" will
catch it before it gets anywhere near a maintainer.