Re: [PATCH v4 03/21] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP

[Mike Kravetz]

On 11/13/20 2:59 AM, Muchun Song wrote:
> The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure
> whether to enable the feature of freeing unused vmemmap associated
> with HugeTLB pages. Now only support x86.
> 
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
>  arch/x86/mm/init_64.c |  2 +-
>  fs/Kconfig            | 14 ++++++++++++++
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 0a45f062826e..0435bee2e172 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1225,7 +1225,7 @@ static struct kcore_list kcore_vsyscall;
>  
>  static void __init register_page_bootmem_info(void)
>  {
> -#ifdef CONFIG_NUMA
> +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP)
>  	int i;
>  
>  	for_each_online_node(i)
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 976e8b9033c4..67e1bc99574f 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -245,6 +245,20 @@ config HUGETLBFS
>  config HUGETLB_PAGE
>  	def_bool HUGETLBFS
>  
> +config HUGETLB_PAGE_FREE_VMEMMAP
> +	def_bool HUGETLB_PAGE
> +	depends on X86
> +	depends on SPARSEMEM_VMEMMAP
> +	depends on HAVE_BOOTMEM_INFO_NODE
> +	help
> +	  When using SPARSEMEM_VMEMMAP, the system can save up some memory

Should that read,

	When using HUGETLB_PAGE_FREE_VMEMMAP, ...

as the help message is for this config option.

-- 
Mike Kravetz