Re: [PATCH] mm: clarify COMPACTION Kconfig text

[Michal Hocko]

On Tue 23-08-16 10:38:30, Markus Trippelsdorf wrote:
> On 2016.08.23 at 10:09 +0200, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@xxxxxxxx>
> > 
> > The current wording of the COMPACTION Kconfig help text doesn't
> > emphasise that disabling COMPACTION might cripple the page allocator
> > which relies on the compaction quite heavily for high order requests and
> > an unexpected OOM can happen with the lack of compaction. Make sure
> > we are vocal about that.
> 
> Just a few nitpicks inline below:
> 
> >  mm/Kconfig | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index 78a23c5c302d..0dff2f05b6d1 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -262,7 +262,14 @@ config COMPACTION
> >  	select MIGRATION
> >  	depends on MMU
> >  	help
> > -	  Allows the compaction of memory for the allocation of huge pages.
> > +          Compaction is the only memory management component to form
> > +          high order (larger physically contiguous) memory blocks
> > +          reliably. Page allocator relies on the compaction heavily and
>                        The page allo...      on compaction    
> > +          the lack of the feature can lead to unexpected OOM killer
> > +          invocation for high order memory requests. You shouldnm't
>              invocations                                    shouldn't  
> > +          disable this option unless there is really a strong reason for
>                                               really is      
> > +          it and then we are really interested to hear about that at
>                             would be    

Thanks for the review. Updated patch follows:
---