Re: [PATCH v5 0/4] add hugetlb_free_vmemmap sysctl

From: Masahiro Yamada <masahiroy@kernel.org>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	mike.kravetz@oracle.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>,
	Oscar Salvador <osalvador@suse.de>,
	David Hildenbrand <david@redhat.com>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	duanxiongchun@bytedance.com, smuchun@gmail.com
Subject: Re: [PATCH v5 0/4] add hugetlb_free_vmemmap sysctl
Date: Fri, 25 Mar 2022 14:03:22 +0900	[thread overview]
Message-ID: <CAK7LNASSzXsRkgR=P56Xdpk7OtVeX+GnQ-WTwVWKfcKRc0z7Pw@mail.gmail.com> (raw)
In-Reply-To: <YjuX5WCHNsjxgcCM@bombadil.infradead.org>

On Thu, Mar 24, 2022 at 6:58 AM Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> Masahiro,
>
> can I trouble you to help review the first patch here? I thought
> something like this might be possible, and Muchun has done some good
> work to try it. If anyone can find hole on that kconfig hack it would
> be you. I'll bounce you a copy of the patches.
>
>   Luis

Now, I took a look at it.
Please do not do such a horrible hack.

Thanks.

>
> On Wed, Mar 23, 2022 at 08:55:19PM +0800, Muchun Song wrote:
> > This series is based on next-20220310.
> >
> > This series amis to add hugetlb_free_vmemmap sysctl to enable the feature
> > of freeing vmemmap pages of HugeTLB pages.
> >
> > v5:
> >   - Fix not working properly if one is workig off of a very clean build
> >     reported by Luis Chamberlain.
> >   - Add Suggested-by for Luis Chamberlain.
> >
> > Thanks.
> >
> > v4:
> >   - Introduce STRUCT_PAGE_SIZE_IS_POWER_OF_2 inspired by Luis.
> >
> > v3:
> >   - Add pr_warn_once() (Mike).
> >   - Handle the transition from enabling to disabling (Luis)
> >
> > v2:
> >   - Fix compilation when !CONFIG_MHP_MEMMAP_ON_MEMORY reported by kernel
> >     test robot <lkp@intel.com>.
> >   - Move sysctl code from kernel/sysctl.c to mm/hugetlb_vmemmap.c.
> >
> > Muchun Song (4):
> >   mm: hugetlb_vmemmap: introduce STRUCT_PAGE_SIZE_IS_POWER_OF_2
> >   mm: memory_hotplug: override memmap_on_memory when
> >     hugetlb_free_vmemmap=on
> >   sysctl: allow to set extra1 to SYSCTL_ONE
> >   mm: hugetlb_vmemmap: add hugetlb_free_vmemmap sysctl
> >
> >  Documentation/admin-guide/sysctl/vm.rst |  14 +++++
> >  Kbuild                                  |  14 +++++
> >  fs/Kconfig                              |   1 +
> >  include/linux/memory_hotplug.h          |   9 +++
> >  include/linux/mm_types.h                |   2 +
> >  kernel/sysctl.c                         |   2 +-
> >  mm/Kconfig                              |   3 +
> >  mm/hugetlb_vmemmap.c                    | 107 ++++++++++++++++++++++++--------
> >  mm/hugetlb_vmemmap.h                    |   4 +-
> >  mm/memory_hotplug.c                     |  27 ++++++--
> >  mm/struct_page_size.c                   |  19 ++++++
> >  scripts/check_struct_page_po2.sh        |   9 +++
> >  12 files changed, 177 insertions(+), 34 deletions(-)
> >  create mode 100644 mm/struct_page_size.c
> >  create mode 100755 scripts/check_struct_page_po2.sh
> >
> > --
> > 2.11.0
> >

-- 
Best Regards
Masahiro Yamada