Re: mmotm 2017-08-25-15-50 uploaded

[Stephen Rothwell]

Hi Michal,

On Mon, 28 Aug 2017 09:59:31 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> From 31d551dbcb1b7987a4cd07767c1e2805849b7a26 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@xxxxxxxx>
> Date: Mon, 28 Aug 2017 09:41:39 +0200
> Subject: [PATCH] 
>  mm-hmm-struct-hmm-is-only-use-by-hmm-mirror-functionality-v2-fix
> 
> Compiler is complaining for allnoconfig
> 
> kernel/fork.c: In function 'mm_init':
> kernel/fork.c:814:2: error: implicit declaration of function 'hmm_mm_init' [-Werror=implicit-function-declaration]
>   hmm_mm_init(mm);
>   ^
> kernel/fork.c: In function '__mmdrop':
> kernel/fork.c:893:2: error: implicit declaration of function 'hmm_mm_destroy' [-Werror=implicit-function-declaration]
>   hmm_mm_destroy(mm);
> 
> Make sure that hmm_mm_init/hmm_mm_destroy empty stups are defined when
> CONFIG_HMM is disabled.
> 
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
>  include/linux/hmm.h | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 9583d9a15f9c..aeb94e682dda 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -508,11 +508,10 @@ static inline void hmm_mm_init(struct mm_struct *mm)
>  {
>  	mm->hmm = NULL;
>  }
> -#else /* IS_ENABLED(CONFIG_HMM_MIRROR) */
> +#endif
> +
> +#else /* IS_ENABLED(CONFIG_HMM) */
>  static inline void hmm_mm_destroy(struct mm_struct *mm) {}
>  static inline void hmm_mm_init(struct mm_struct *mm) {}
> -#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
> -
> -
>  #endif /* IS_ENABLED(CONFIG_HMM) */
>  #endif /* LINUX_HMM_H */

What happens when CONFIG_HMM is defined but CONFIG_HMM_MIRROR is not?
Or is that not possible (in which case why would we have
CONFIG_HMM_MIRROR)? 
-- 
Cheers,
Stephen Rothwell