Subject: [PATCH 02/14] mm: page_poison: always declare __kernel_map_pages() function

From: Arnd Bergmann <[email-masked]>
Date: Wed, 17 May 2023 15:10:50 +0200

From: Arnd Bergmann <[email-masked]>

The __kernel_map_pages() function is mainly used for
CONFIG_DEBUG_PAGEALLOC, but has a number of architecture specific
definitions that may also be used in other configurations, as well
as a global fallback definition for architectures that do not support
DEBUG_PAGEALLOC.

When the option is disabled, any definitions without the prototype
cause a warning:

mm/page_poison.c:102:6: error: no previous prototype for '__kernel_map_pages' [-Werror=missing-prototypes]

The function is a trivial nop here, so just declare it anyway
to avoid the warning.

Signed-off-by: Arnd Bergmann <[email-masked]>
---
 include/linux/mm.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 27ce77080c79..e95d7c575ea6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3453,13 +3453,12 @@ static inline bool debug_pagealloc_enabled_static(void)
 	return static_branch_unlikely(&_debug_pagealloc_enabled);
 }
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
 /*
  * To support DEBUG_PAGEALLOC architecture must ensure that
  * __kernel_map_pages() never fails
  */
 extern void __kernel_map_pages(struct page *page, int numpages, int enable);
-
+#ifdef CONFIG_DEBUG_PAGEALLOC
 static inline void debug_pagealloc_map_pages(struct page *page, int numpages)
 {
 	if (debug_pagealloc_enabled_static())
-- 
2.39.2