From: Pankaj Raghav split_huge_page_to_list_[to_order](), split_huge_page() and try_folio_split() return 0 on success and error codes on failure. When THP is disabled, these functions return 0 indicating success even though an error code should be returned as it is not possible to split a folio when THP is disabled. Make all these functions return -EINVAL to indicate failure instead of 0. As large folios depend on CONFIG_THP, issue warning as this function should not be called without a large folio. Signed-off-by: Pankaj Raghav --- This issue was discovered while experimenting enabling large folios without THP and found that returning 0 in these functions is resulting in undefined behavior in truncate operations. This change fixes the issue. include/linux/huge_mm.h | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 29ef70022da1..23f124493c47 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -588,22 +588,30 @@ static inline int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, unsigned int new_order) { - return 0; + struct folio *folio = page_folio(page); + + VM_WARN_ON_ONCE_FOLIO(1, folio); + return -EINVAL; } static inline int split_huge_page(struct page *page) { - return 0; + struct folio *folio = page_folio(page); + + VM_WARN_ON_ONCE_FOLIO(1, folio); + return -EINVAL; } static inline int split_folio_to_list(struct folio *folio, struct list_head *list) { - return 0; + VM_WARN_ON_ONCE_FOLIO(1, folio); + return -EINVAL; } static inline int try_folio_split(struct folio *folio, struct page *page, struct list_head *list) { - return 0; + VM_WARN_ON_ONCE_FOLIO(1, folio); + return -EINVAL; } static inline void deferred_split_folio(struct folio *folio, bool partially_mapped) {} base-commit: 291634ccfd2820c09f6e8c4982c2dee8155d09ae -- 2.50.1