From: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>

VM_NOHUGEPAGE is a no-op if CONFIG_TRANSPARENT_HUGEPAGE is disabled. So
it makes no sense to return an error when calling madvise() with
MADV_NOHUGEPAGE in that case.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 include/linux/huge_mm.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2f190c90192d..1a8082c61e01 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -506,6 +506,8 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
 
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#include <uapi/asm/mman.h>
+
 static inline bool folio_test_pmd_mappable(struct folio *folio)
 {
 	return false;
@@ -595,6 +597,9 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
 static inline int hugepage_madvise(struct vm_area_struct *vma,
 				   unsigned long *vm_flags, int advice)
 {
+	/* On a !THP kernel, MADV_NOHUGEPAGE is a no-op, but MADV_HUGEPAGE is not supported */
+	if (advice == MADV_NOHUGEPAGE)
+		return 0;
 	return -EINVAL;
 }
 
-- 
2.49.0

* Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [250515 16:15]:
> From: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> 
> VM_NOHUGEPAGE is a no-op if CONFIG_TRANSPARENT_HUGEPAGE is disabled. So
> it makes no sense to return an error when calling madvise() with
> MADV_NOHUGEPAGE in that case.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Nice to see you review this for yourself :)

> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
>  include/linux/huge_mm.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 2f190c90192d..1a8082c61e01 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -506,6 +506,8 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
>  
>  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
> +#include <uapi/asm/mman.h>
> +
>  static inline bool folio_test_pmd_mappable(struct folio *folio)
>  {
>  	return false;
> @@ -595,6 +597,9 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
>  static inline int hugepage_madvise(struct vm_area_struct *vma,
>  				   unsigned long *vm_flags, int advice)
>  {
> +	/* On a !THP kernel, MADV_NOHUGEPAGE is a no-op, but MADV_HUGEPAGE is not supported */
> +	if (advice == MADV_NOHUGEPAGE)
> +		return 0;
>  	return -EINVAL;
>  }
>  
> -- 
> 2.49.0
>

On Fri, May 16, 2025 at 11:40:23AM -0400, Liam R. Howlett wrote:
> * Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [250515 16:15]:
> > From: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> >
> > VM_NOHUGEPAGE is a no-op if CONFIG_TRANSPARENT_HUGEPAGE is disabled. So
> > it makes no sense to return an error when calling madvise() with
> > MADV_NOHUGEPAGE in that case.
> >
> > Suggested-by: Matthew Wilcox <willy@infradead.org>
> > Signed-off-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> > Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
> > Acked-by: David Hildenbrand <david@redhat.com>
> > Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>
> Nice to see you review this for yourself :)

Haha yeah... this is a Lorenzo-getting-confused-by-kernel-process situation
again, this is 100% Ignacio's patch, I just bundled it up in this series to
enforce ordering.

>
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

...But of course I did format-patch -s so I signed it off as well :P

At any rate the From: field and Ignacio's S-o-b should make everything correct
in the wash. I think.

Andrew - this is Ignacio's patch for avoidance of doubt :P

>
> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
>
> > ---
> >  include/linux/huge_mm.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > index 2f190c90192d..1a8082c61e01 100644
> > --- a/include/linux/huge_mm.h
> > +++ b/include/linux/huge_mm.h
> > @@ -506,6 +506,8 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
> >
> >  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
> >
> > +#include <uapi/asm/mman.h>
> > +
> >  static inline bool folio_test_pmd_mappable(struct folio *folio)
> >  {
> >  	return false;
> > @@ -595,6 +597,9 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
> >  static inline int hugepage_madvise(struct vm_area_struct *vma,
> >  				   unsigned long *vm_flags, int advice)
> >  {
> > +	/* On a !THP kernel, MADV_NOHUGEPAGE is a no-op, but MADV_HUGEPAGE is not supported */
> > +	if (advice == MADV_NOHUGEPAGE)
> > +		return 0;
> >  	return -EINVAL;
> >  }
> >
> > --
> > 2.49.0
> >
>

* Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [250516 11:43]:
> On Fri, May 16, 2025 at 11:40:23AM -0400, Liam R. Howlett wrote:
> > * Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [250515 16:15]:
> > > From: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> > >
> > > VM_NOHUGEPAGE is a no-op if CONFIG_TRANSPARENT_HUGEPAGE is disabled. So
> > > it makes no sense to return an error when calling madvise() with
> > > MADV_NOHUGEPAGE in that case.
> > >
> > > Suggested-by: Matthew Wilcox <willy@infradead.org>
> > > Signed-off-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> > > Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
> > > Acked-by: David Hildenbrand <david@redhat.com>
> > > Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> >
> > Nice to see you review this for yourself :)
> 
> Haha yeah... this is a Lorenzo-getting-confused-by-kernel-process situation
> again, this is 100% Ignacio's patch, I just bundled it up in this series to
> enforce ordering.
> 
> >
> > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> 
> ...But of course I did format-patch -s so I signed it off as well :P
> 
> At any rate the From: field and Ignacio's S-o-b should make everything correct
> in the wash. I think.
> 
> Andrew - this is Ignacio's patch for avoidance of doubt :P

Oh yes, I missed the initial sign off.  I think this is okay, but maybe
you didn't need your own RB?

> 
> >
> > Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> >
> > > ---
> > >  include/linux/huge_mm.h | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > >
> > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > > index 2f190c90192d..1a8082c61e01 100644
> > > --- a/include/linux/huge_mm.h
> > > +++ b/include/linux/huge_mm.h
> > > @@ -506,6 +506,8 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
> > >
> > >  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
> > >
> > > +#include <uapi/asm/mman.h>
> > > +
> > >  static inline bool folio_test_pmd_mappable(struct folio *folio)
> > >  {
> > >  	return false;
> > > @@ -595,6 +597,9 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma,
> > >  static inline int hugepage_madvise(struct vm_area_struct *vma,
> > >  				   unsigned long *vm_flags, int advice)
> > >  {
> > > +	/* On a !THP kernel, MADV_NOHUGEPAGE is a no-op, but MADV_HUGEPAGE is not supported */
> > > +	if (advice == MADV_NOHUGEPAGE)
> > > +		return 0;
> > >  	return -EINVAL;
> > >  }
> > >
> > > --
> > > 2.49.0
> > >
> >