Re: [PATCH] mm: clarify COMPACTION Kconfig text

[Markus Trippelsdorf]

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    

-- 
Markus