Re: [PATCH] mm: kconfig: make Transparent Hugepage Support sysfs defaults to match the documentation

[Rafael Aquini <aquini@redhat.com>]

On Tue, Nov 19, 2019 at 01:47:41PM +0300, Kirill A. Shutemov wrote:
> On Mon, Nov 18, 2019 at 10:01:02PM -0500, Rafael Aquini wrote:
> > Documentation/admin-guide/mm/transhuge.rst (originally in Documentation/vm/transhuge.txt)
> > states that TRANSPARENT_HUGEPAGE_MADVISE is the default option for THP config:
> > 
> > "
> > madvise
> >         will enter direct reclaim like ``always`` but only for regions
> >         that are have used madvise(MADV_HUGEPAGE). This is the default
> >         behaviour.
> > "
> > 
> > This patch changes mm/Kconfig to reflect that fact, accordingly.
> 
> No. You've read it incorrectly.
>
Fair enough.

I'll reform the log message then, and repost.
 
> The documentation describes default behaviour wrt defragmentaton ("defrag"
> file), not page fault ("enabled" file). We don't have any Kconfig option
> to set default behaviour for "defrag".
> 
> > Besides keeping consistency between documentation and the code behavior,
> > other reasons to perform this minor adjustment are noted at:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1772133
> > 
> > Signed-off-by: Rafael Aquini <aquini@redhat.com>
> > ---
> >  mm/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index a5dae9a7eb51..c12a559aa1e5 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -385,7 +385,7 @@ config TRANSPARENT_HUGEPAGE
> >  choice
> >  	prompt "Transparent Hugepage Support sysfs defaults"
> >  	depends on TRANSPARENT_HUGEPAGE
> > -	default TRANSPARENT_HUGEPAGE_ALWAYS
> > +	default TRANSPARENT_HUGEPAGE_MADVISE
> >  	help
> >  	  Selects the sysfs defaults for Transparent Hugepage Support.
> >  
> > -- 
> > 2.17.2
> > 
> > 
> 
> -- 
>  Kirill A. Shutemov
>