Re: [PATCH] tools/testing/vma: add missing function stub

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Wed, May 28, 2025 at 03:52:18PM -0700, Andrew Morton wrote:
> On Wed, 28 May 2025 15:15:39 +0100 Lorenzo Stoakes via B4 Relay <devnull+lorenzo.stoakes.oracle.com@kernel.org> wrote:
>
> > From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> >
> > The hugetlb fix introduced in commit ee40c9920ac2 ("mm: fix copy_vma()
> > error handling for hugetlb mappings") mistakenly did not provide a stub for
> > the VMA userland testing, which results in a compile error when trying to
> > build this.
>
> Thanks, I'll add the Fixes: and the cc:stable (because ee40c9920ac2 had
> cc:stable).

Yeah I intentionally excluded those, as it'll lead to some backport pain
for something that isn't shipped.

I'm not sure if we generally backport test fixes as a rule? Though I
suppose it might be useful if somebody is investigating an issue in a
stable kernel.

>
> > Provide this stub to resolve the issue.
> >
> > ---
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>
> SOB goes above the "^---$", please ;)

b4 decided to do this :) first experiment with it. Will look at options, I also
pinged Konstantin.

>
> > --- a/tools/testing/vma/vma_internal.h
> > +++ b/tools/testing/vma/vma_internal.h
> > @@ -1461,4 +1461,9 @@ static inline int __call_mmap_prepare(struct file *file,
> >  	return file->f_op->mmap_prepare(desc);
> >  }
> >
> > +static inline void fixup_hugetlb_reservations(struct vm_area_struct *vma)
> > +{
> > +	(void)vma;
>
> <Curiousity> Was this statement found to be needed?  Normally we just
> use an empty function body in such cases.

I _could have sworn_ I was getting warnings in the gcc version I was using
the past by not doing this.

At any rate, it's consistent-ish with other functions here.

Since this is a churn-friendly file, I"ll probably do a pass to make all
the signatures consistent (by just removing variable names probably) at
some point.

>
> > +}
> > +
> >  #endif	/* __MM_VMA_INTERNAL_H */
>