Re: [PATCH v2] hugetlb: allow to free gigantic pages regardless of the configuration

[Alexandre Ghiti]

On 02/13/2019 08:30 PM, Dave Hansen wrote:
> > -#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
> > +#ifdef CONFIG_COMPACTION_CORE
> >   static __init int gigantic_pages_init(void)
> >   {
> >   	/* With compaction or CMA we can allocate gigantic pages at runtime */
> > diff --git a/fs/Kconfig b/fs/Kconfig
> > index ac474a61be37..8fecd3ea5563 100644
> > --- a/fs/Kconfig
> > +++ b/fs/Kconfig
> > @@ -207,8 +207,9 @@ config HUGETLB_PAGE
> >   config MEMFD_CREATE
> >   	def_bool TMPFS || HUGETLBFS
> >   
> > -config ARCH_HAS_GIGANTIC_PAGE
> > +config COMPACTION_CORE
> >   	bool
> > +	default y if (MEMORY_ISOLATION && MIGRATION) || CMA
> This takes a hard dependency (#if) and turns it into a Kconfig *default*
> that can be overridden.  That seems like trouble.
>
> Shouldn't it be:
>
> config COMPACTION_CORE
> 	def_bool y
> 	depends on (MEMORY_ISOLATION && MIGRATION) || CMA
>
> ?

Thanks for that,

Alex