On Wed, Jul 22, 2026 at 12:32 AM Matthew Brost <[email protected]> wrote:
>
> HPAGE_PMD_SHIFT expands to BUILD_BUG() when CONFIG_PGTABLE_HAS_HUGE_LEAVES
> is not set, causing a compile error when both CONFIG_TRANSPARENT_HUGEPAGE
> and CONFIG_HUGETLB_PAGE are disabled:
>
> drivers/gpu/drm/drm_pagemap.c:480:12: error: call to
> '__compiletime_assert_458'
> declared with 'error' attribute: BUILD_BUG failed
> 480 | order = HPAGE_PMD_ORDER;
> | ^
> include/linux/huge_mm.h:117:26: note: expanded from macro 'HPAGE_PMD_ORDER'
> 117 | #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
> | ^
> include/linux/huge_mm.h:113:28: note: expanded from macro 'HPAGE_PMD_SHIFT'
> 113 | #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
>
> Define DRM_PAGEMAP_PMD_ORDER, which maps to HPAGE_PMD_ORDER when
> CONFIG_ARCH_ENABLE_THP_MIGRATION is enabled and to -1 otherwise.
>
> This is safe because all code paths that use DRM_PAGEMAP_PMD_ORDER are
> reachable only when CONFIG_ARCH_ENABLE_THP_MIGRATION is enabled.
>
> Fixes: 139ab31aea8a ("drm/pagemap: Correct cpages calculation for
> migrate_vma_setup")
> Reported-by: kernel test robot <[email protected]>
> Closes: https://lore.kernel.org/r/[email protected]/
> Cc: Jan Stancek <[email protected]>
> Signed-off-by: Matthew Brost <[email protected]>
> ---
> drivers/gpu/drm/drm_pagemap.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_pagemap.c b/drivers/gpu/drm/drm_pagemap.c
> index 15c78eca180b..951cd92c930c 100644
> --- a/drivers/gpu/drm/drm_pagemap.c
> +++ b/drivers/gpu/drm/drm_pagemap.c
> @@ -12,6 +12,12 @@
> #include <drm/drm_pagemap_util.h>
> #include <drm/drm_print.h>
>
> +#if IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION)
Now that d547b1001755 ("mm: rename ARCH_ENABLE_THP_MIGRATION to
ARCH_HAS_PMD_SOFTLEAVES")
landed in Linus' tree, would you consider applying this again using
the new config name?
Thanks,
Jan
> +#define DRM_PAGEMAP_PMD_ORDER HPAGE_PMD_ORDER
> +#else
> +#define DRM_PAGEMAP_PMD_ORDER (-1)
> +#endif
> +
> /**
> * DOC: Overview
> *
> @@ -579,7 +585,7 @@ static int drm_pagemap_cpages(unsigned long *migrate_pfn,
> unsigned long npages)
> order = folio_order(folio);
> cpages += NR_PAGES(order);
> } else if (migrate_pfn[i] & MIGRATE_PFN_COMPOUND) {
> - order = HPAGE_PMD_ORDER;
> + order = DRM_PAGEMAP_PMD_ORDER;
> cpages += NR_PAGES(order);
> }
>
> @@ -765,10 +771,11 @@ int drm_pagemap_migrate_to_devmem(struct
> drm_pagemap_devmem *devmem_allocation,
>
> if (migrate.src[i] & MIGRATE_PFN_COMPOUND) {
> drm_WARN_ONCE(dpagemap->drm, src_page &&
> - folio_order(page_folio(src_page)) !=
> HPAGE_PMD_ORDER,
> + folio_order(page_folio(src_page)) !=
> + DRM_PAGEMAP_PMD_ORDER,
> "Unexpected folio order\n");
>
> - order = HPAGE_PMD_ORDER;
> + order = DRM_PAGEMAP_PMD_ORDER;
> migrate.dst[i] |= MIGRATE_PFN_COMPOUND;
>
> for (j = 1; j < NR_PAGES(order) && i + j < npages;
> j++)
> --
> 2.34.1
>
