As raised by Andrew [1], a folio/compound page never spans a negative number of pages. Consequently, let's use "unsigned long" instead of "long" consistently for folio_nr_pages(), folio_large_nr_pages() and compound_nr(). Using "unsigned long" as return value is fine, because even "(long)-folio_nr_pages()" will keep on working as expected. Using "unsigned int" instead would actually break these use cases. This patch takes the first step changing these to return unsigned long (and making drm_gem_get_pages() use the new types instead of replacing min()). In the future, we might want to make more callers of these functions to consistently use "unsigned long". [1] https://lore.kernel.org/linux-mm/20250503182858.5a02729fcffd6d4723afcfc2@linux-foundation.org/ Link: https://lore.kernel.org/linux-mm/20250503182858.5a02729fcffd6d4723afcfc2@linux-foundation.org/ Signed-off-by: Aristeu Rozanski Suggested-by: Andrew Morton Suggested-by: David Hildenbrand Cc: David Hildenbrand Cc: Andrew Morton Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Simona Vetter --- drivers/gpu/drm/drm_gem.c | 4 ++-- include/linux/mm.h | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-) --- linus-2.6.orig/drivers/gpu/drm/drm_gem.c 2025-08-11 14:52:45.878752324 -0400 +++ linus-2.6/drivers/gpu/drm/drm_gem.c 2025-08-19 00:31:01.495295839 -0400 @@ -620,7 +620,7 @@ struct page **drm_gem_get_pages(struct d struct page **pages; struct folio *folio; struct folio_batch fbatch; - long i, j, npages; + unsigned long i, j, npages; if (WARN_ON(!obj->filp)) return ERR_PTR(-EINVAL); @@ -644,7 +644,7 @@ WARN_ON((obj->size & (PAGE_SIZE - 1)) != i = 0; while (i < npages) { - long nr; + unsigned long nr; folio = shmem_read_folio_gfp(mapping, i, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) --- linus-2.6.orig/include/linux/mm.h 2025-08-11 14:52:45.878752324 -0400 +++ linus-2.6/include/linux/mm.h 2025-08-11 14:53:00.396630632 -0400 @@ -951,12 +951,12 @@ return folio->_flags_1 & 0xff; } #ifdef NR_PAGES_IN_LARGE_FOLIO -static inline long folio_large_nr_pages(const struct folio *folio) +static inline unsigned long folio_large_nr_pages(const struct folio *folio) { return folio->_nr_pages; } #else -static inline long folio_large_nr_pages(const struct folio *folio) +static inline unsigned long folio_large_nr_pages(const struct folio *folio) { return 1L << folio_large_order(folio); } @@ -1971,7 +1971,7 @@ static inline void set_page_links(struct * * Return: A positive power of two. */ -static inline long folio_nr_pages(const struct folio *folio) +static inline unsigned long folio_nr_pages(const struct folio *folio) { if (!folio_test_large(folio)) return 1; @@ -1990,7 +1990,7 @@ static inline long folio_nr_pages(const * page. compound_nr() can be called on a tail page, and is defined to * return 1 in that case. */ -static inline long compound_nr(struct page *page) +static inline unsigned long compound_nr(struct page *page) { struct folio *folio = (struct folio *)page;