Re: [PATCH v3 3/8] mm/debug-pagealloc: make debug-pagealloc boottime configurable

[Andrew Morton]

On Mon, 24 Nov 2014 17:15:21 +0900 Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:

> Now, we have prepared to avoid using debug-pagealloc in boottime. So
> introduce new kernel-parameter to disable debug-pagealloc in boottime,
> and makes related functions to be disabled in this case.
> 
> Only non-intuitive part is change of guard page functions. Because
> guard page is effective only if debug-pagealloc is enabled, turning off
> according to debug-pagealloc is reasonable thing to do.
> 
> ...
>
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -858,6 +858,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			causing system reset or hang due to sending
>  			INIT from AP to BSP.
>  
> +	disable_debug_pagealloc
> +			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
> +			parameter allows user to disable it at boot time.
> +			With this parameter, we can avoid allocating huge
> +			chunk of memory for debug pagealloc and then
> +			the system will work mostly same with the kernel
> +			built without CONFIG_DEBUG_PAGEALLOC.
> +

Weren't we going to make this default to "off", require a boot option
to turn debug_pagealloc on?

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