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

From: Muchun Song
Date: Wed Nov 18 2020 - 22:01:30 EST


On Thu, Nov 19, 2020 at 6:39 AM Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
>
> 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.

Got it. Thanks

>
> --
> Mike Kravetz



--
Yours,
Muchun