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Howlett" Cc: linux-kernel@vger.kernel.org, kernel@pankajraghav.com, willy@infradead.org, linux-mm@kvack.org, mcgrof@kernel.org, gost.dev@samsung.com, Pankaj Raghav , Kiryl Shutsemau , kernel test robot Subject: [PATCH v4] huge_memory: return -EINVAL in folio split functions when THP is disabled Date: Fri, 5 Sep 2025 17:00:12 +0200 Message-ID: <20250905150012.93714-1-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 3357C40014 X-Stat-Signature: b5m4kwn9m9cqxo3sh53qrq38uujjccju X-Rspam-User: X-HE-Tag: 1757084421-687039 X-HE-Meta: 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 2B84pWds qwUEE2YUgTaL5ILDU9SMDIcNF6PCfYKQgJpgI+fvUwb9FOVMwpSPVdA63jg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Acked-by: David Hildenbrand Acked-by: Zi Yan Acked-by: Kiryl Shutsemau Reviewed-by: Lorenzo Stoakes Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202509051753.riCeG7LC-lkp@intel.com/ Signed-off-by: Pankaj Raghav --- Changes since v3: - use VM_WARN_ON_ONCE_PAGE instead of the folio version in functions that take a page. Changes since v2: - use page_folio(page) directly in VM_WARN_ON_ONCE_FOLIO include/linux/huge_mm.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 7748489fde1b..cd61d2b789ec 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -553,22 +553,26 @@ static inline int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, unsigned int new_order) { - return 0; + VM_WARN_ON_ONCE_PAGE(1, page); + return -EINVAL; } static inline int split_huge_page(struct page *page) { - return 0; + VM_WARN_ON_ONCE_PAGE(1, page); + 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: e6b9dce0aeeb91dfc0974ab87f02454e24566182 -- 2.50.1