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From:   Muchun Song <songmuchun@bytedance.com>
Date:   Thu, 31 Mar 2022 16:53:48 +0800
Message-ID: <CAMZfGtVsSJWT6Fojr5FcN26=MPnjp79usQXF+xRGXHLUvwYU_Q@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] mm: hugetlb_vmemmap: introduce ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP
To:     David Hildenbrand <david@redhat.com>
Cc:     Will Deacon <will@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oscar Salvador <osalvador@suse.de>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        David Rientjes <rientjes@google.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>, james.morse@arm.com,
        Barry Song <21cnbao@gmail.com>,
        LAK <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Xiongchun duan <duanxiongchun@bytedance.com>,
        Fam Zheng <fam.zheng@bytedance.com>,
        Muchun Song <smuchun@gmail.com>
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On Thu, Mar 31, 2022 at 4:51 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 31.03.22 10:48, Muchun Song wrote:
> > On Thu, Mar 31, 2022 at 4:42 PM David Hildenbrand <david@redhat.com> wrote:
> >>
> >> On 31.03.22 08:56, Muchun Song wrote:
> >>> The feature of minimizing overhead of struct page associated with each
> >>> HugeTLB page is implemented on x86_64, however, the infrastructure of
> >>> this feature is already there, we could easily enable it for other
> >>> architectures.  Introduce ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP for other
> >>> architectures to be easily enabled.  Just select this config if they
> >>> want to enable this feature.
> >>>
> >>> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> >>> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> >>> ---
> >>>  arch/x86/Kconfig |  1 +
> >>>  fs/Kconfig       | 10 +++++++++-
> >>>  2 files changed, 10 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> >>> index 9f5bd41bf660..e69d42528542 100644
> >>> --- a/arch/x86/Kconfig
> >>> +++ b/arch/x86/Kconfig
> >>> @@ -119,6 +119,7 @@ config X86
> >>>       select ARCH_WANTS_DYNAMIC_TASK_STRUCT
> >>>       select ARCH_WANTS_NO_INSTR
> >>>       select ARCH_WANT_HUGE_PMD_SHARE
> >>> +     select ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP      if X86_64
> >>>       select ARCH_WANT_LD_ORPHAN_WARN
> >>>       select ARCH_WANTS_THP_SWAP              if X86_64
> >>>       select ARCH_HAS_PARANOID_L1D_FLUSH
> >>> diff --git a/fs/Kconfig b/fs/Kconfig
> >>> index 6c7dc1387beb..f6db2af33738 100644
> >>> --- a/fs/Kconfig
> >>> +++ b/fs/Kconfig
> >>> @@ -245,9 +245,17 @@ config HUGETLBFS
> >>>  config HUGETLB_PAGE
> >>>       def_bool HUGETLBFS
> >>>
> >>> +#
> >>> +# Select this config option from the architecture Kconfig, if it is preferred
> >>> +# to enable the feature of minimizing overhead of struct page associated with
> >>> +# each HugeTLB page.
> >>> +#
> >>> +config ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP
> >>> +     bool
> >>> +
> >>>  config HUGETLB_PAGE_FREE_VMEMMAP
> >>>       def_bool HUGETLB_PAGE
> >>> -     depends on X86_64
> >>> +     depends on ARCH_WANT_HUGETLB_PAGE_FREE_VMEMMAP
> >>>       depends on SPARSEMEM_VMEMMAP
> >>>
> >>>  config HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON
> >>
> >>
> >> I think something like "HUGETLB_OPTIMIZE_VMEMMAP" might be more
> >> expressive, but that would imply renaming the existing config knob.
> >>
> >
> > How about doing a full code cleanup in a separate series in the future?
> >
>
> Yeah.
>

OK. Have Added it into my To-do list.

Thanks.