From: Aristeu Rozanski Date: Tue, 26 Aug 2025 15:37:21 +0000 (-0400) Subject: mm: make folio page count functions return unsigned X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fa17bcd5f65ed702df001579cca8c885fa6bf3e7;p=thirdparty%2Fkernel%2Fstable.git mm: make folio page count functions return unsigned 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". Link: https://lore.kernel.org/linux-mm/20250503182858.5a02729fcffd6d4723afcfc2@linux-foundation.org/ Link: https://lkml.kernel.org/r/20250826153721.GA23292@cathedrallabs.org Link: https://lore.kernel.org/linux-mm/20250503182858.5a02729fcffd6d4723afcfc2@linux-foundation.org/ [1] Signed-off-by: Aristeu Rozanski Suggested-by: Andrew Morton Suggested-by: David Hildenbrand Acked-by: David Hildenbrand Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Simona Vetter Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 6a44351e58b77..5dbcf91ff73cc 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -621,7 +621,7 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj) 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); @@ -645,7 +645,7 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj) 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)) diff --git a/include/linux/mm.h b/include/linux/mm.h index da6e0abad2cb3..8f5b4df9b1667 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1018,12 +1018,12 @@ static inline unsigned int folio_large_order(const struct folio *folio) } #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); } @@ -2062,7 +2062,7 @@ static inline void set_page_links(struct page *page, enum zone_type zone, * * 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; @@ -2097,7 +2097,7 @@ static inline long folio_nr_pages(const struct folio *folio) * page. compound_nr() can be called on a tail page, and is defined to * return 1 in that case. */ -static inline long compound_nr(const struct page *page) +static inline unsigned long compound_nr(const struct page *page) { const struct folio *folio = (struct folio *)page;