Re: [RFC 04/10] drivers: i915 selftest: use pgtable_has_pmd_leaves()

[Luiz Capitulino]

On 2025-11-17 12:30, David Hildenbrand (Red Hat) wrote:
> On 06.11.25 22:28, Luiz Capitulino wrote:
> > igt_can_allocate_thp() uses has_transparente_hugepage() to check if
> > PMD-sized pages are supported, use pgtable_has_pmd_leaves() instead.
> >
> > Signed-off-by: Luiz Capitulino <luizcap@xxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/gem/selftests/huge_pages.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
> > index bd08605a1611..c76aafa36d2b 100644
> > --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
> > +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
> > @@ -1316,7 +1316,7 @@ typedef struct drm_i915_gem_object *
> >   static inline bool igt_can_allocate_thp(struct drm_i915_private *i915)
> >   {
> > -    return i915->mm.gemfs && has_transparent_hugepage();
> > +    return i915->mm.gemfs && pgtable_has_pmd_leaves();
>
> On second thought, is it problematic that we might be losing the CONFIG_TRANSPARENT_HUGEPAGE check? Should we check for that separately?

That's a good point.

In this RFC, pgtable_has_pmd_leaves() should be functionally equivalent
to has_transparent_hugepage() so I think we're good. That beind said, I
also think that we should disentangle pgtable_has_pmd_leaves() from THP
now or in the future. When we do this the breakage you're spotting will
happen.

What about adding thp_has_pmd_support() which does:

  return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && pgtable_has_pmd_leaves();

Then I can convert all the cases you spotted to thp_has_pmd_support().