From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Subject: mm/page_alloc: move prototype for find_suitable_fallback make W=1 generates the following warning in mmap_lock.c for allnoconfig mm/page_alloc.c:2670:5: warning: no previous prototype for `find_suitable_fallback' [-Wmissing-prototypes] int find_suitable_fallback(struct free_area *area, unsigned int order, ^~~~~~~~~~~~~~~~~~~~~~ find_suitable_fallback is only shared outside of page_alloc.c for CONFIG_COMPACTION but to suppress the warning, move the protype outside of CONFIG_COMPACTION. It is not worth the effort at this time to find a clever way of allowing compaction.c to share the code or avoid the use entirely as the function is called on relatively slow paths. Link: https://lkml.kernel.org/r/20210520084809.8576-14-mgorman@xxxxxxxxxxxxxxxxxxx Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Yang Shi <shy828301@xxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Dan Streetman <ddstreet@xxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/internal.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/mm/internal.h~mm-page_alloc-move-prototype-for-find_suitable_fallback +++ a/mm/internal.h @@ -274,11 +274,10 @@ isolate_freepages_range(struct compact_c int isolate_migratepages_range(struct compact_control *cc, unsigned long low_pfn, unsigned long end_pfn); +#endif int find_suitable_fallback(struct free_area *area, unsigned int order, int migratetype, bool only_stealable, bool *can_steal); -#endif - /* * This function returns the order of a free page in the buddy system. In * general, page_zone(page)->lock must be held by the caller to prevent the _