On Mon 28-08-17 18:27:05, Stephen Rothwell wrote: > Hi Michal, > > On Mon, 28 Aug 2017 09:59:31 +0200 Michal Hocko <[email protected]> wrote: > > > > From 31d551dbcb1b7987a4cd07767c1e2805849b7a26 Mon Sep 17 00:00:00 2001 > > From: Michal Hocko <[email protected]> > > 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 <[email protected]> > > --- > > 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)?
This is something to Jerome to answer but hmm_mm_init/hmm_mm_destroy are used regardless of the specific HMM configuration so an empty stub should be defined unconditionally AFAIU. -- Michal Hocko SUSE Labs
