diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ce93aaf69f8..98954dda5734 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1125,9 +1125,7 @@ static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer,
 }
 #endif
 
-#ifndef CONFIG_GENERIC_DEVMEM_IS_ALLOWED
 extern int devmem_is_allowed(unsigned long pfn);
-#endif
 
 #endif /* __KERNEL__ */