Hi!

> For architectures with CONFIG_ARCH_HAS_SET_ALIAS, pages can be unmapped
> briefly on the directmap, even when CONFIG_DEBUG_PAGEALLOC is not configured.
> So this changes kernel_map_pages and kernel_page_present to be defined when
> CONFIG_ARCH_HAS_SET_ALIAS is defined as well. It also changes places
> (page_alloc.c) where those functions are assumed to only be implemented when
> CONFIG_DEBUG_PAGEALLOC is defined.

Which architectures are that?

Should this be merged to the patch where HAS_SET_ALIAS is introduced? We
don't want broken hibernation in between....


> -#ifdef CONFIG_DEBUG_PAGEALLOC
>  extern bool _debug_pagealloc_enabled;
> -extern void __kernel_map_pages(struct page *page, int numpages, int enable);
>  
>  static inline bool debug_pagealloc_enabled(void)
>  {
> -	return _debug_pagealloc_enabled;
> +	return IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) && _debug_pagealloc_enabled;
>  }

This will break build AFAICT. _debug_pagealloc_enabled variable does
not exist in !CONFIG_DEBUG_PAGEALLOC case.

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html