From: Muchun Song <songmuchun@bytedance.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Oscar Salvador <osalvador@suse.de>,
Michal Hocko <mhocko@suse.com>,
"Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
David Hildenbrand <david@redhat.com>,
Chen Huang <chenhuang5@huawei.com>,
"Bodeddula, Balasubramaniam" <bodeddub@amazon.com>,
Jonathan Corbet <corbet@lwn.net>,
Xiongchun duan <duanxiongchun@bytedance.com>,
fam.zheng@bytedance.com, linux-doc@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [External] Re: [PATCH v2 0/3] Split huge PMD mapping of vmemmap pages
Date: Tue, 15 Jun 2021 13:37:15 +0800 [thread overview]
Message-ID: <CAMZfGtU3=9JUVj5a7fFo_1K18yOcU4+9c5R2goXVwsGGJxLvNw@mail.gmail.com> (raw)
In-Reply-To: <fe65a409-b989-5e05-952e-6fcf6aa2ab55@oracle.com>
On Tue, Jun 15, 2021 at 11:52 AM Mike Kravetz <mike.kravetz@oracle.com> wrote:
>
> On 6/14/21 6:12 PM, Andrew Morton wrote:
> > On Sat, 12 Jun 2021 17:45:52 +0800 Muchun Song <songmuchun@bytedance.com> wrote:
> >
> >> In order to reduce the difficulty of code review in series[1]. We disable
> >> huge PMD mapping of vmemmap pages when that feature is enabled. In this
> >> series, we do not disable huge PMD mapping of vmemmap pages anymore. We
> >> will split huge PMD mapping when needed. When HugeTLB pages are freed from
> >> the pool we do not attempt coalasce and move back to a PMD mapping because
> >> it is much more complex.
> >>
> >> [1] https://lore.kernel.org/linux-doc/20210510030027.56044-1-songmuchun@bytedance.com/
> >
> > [1] had a nice [0/n] description but the v2 series lost that. I could
> > copy/paste the v1 changelogging but I am unsure that it has been
> > maintained appropriately for the v2 series.
> >
> > I think I'll pass on this v2 pending additional review input. Please reinstate
> > the [0/n] overview if/when resending?
>
> There may be some confusion.
>
> This series is a follow on optimization for the functionality provided by
> [1]. Early in the development of [1], it was decided to drop some code
> for ease of review. Specifically, splitting vmemmap PMD mappings to PTE
> mappings as required when hugetlb pages were allocated. The
> 'simplification' in [1] is that if the feature is enabled then vmemmap
> will only be mapped with PTEs.
>
> This series provides the ability to split PMD mappings 'on demand' as
> hugetlb pages are allocated. As mentioned, it really is a follow on and
> optimization to functionality provided in [1]. As such, I am not sure
> that repeating the [0/n] description from 1 is necessary here.
>
> In any case, this should be clearly stated in the [0/n] description of
> this series.
Thanks for the clarification for me. I totally agree with you.
>
> BTW- I did get through the series today, and did not discover any
> issues. However, I want to sleep on it before signing off.
> --
> Mike Kravetz
prev parent reply other threads:[~2021-06-15 5:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-12 9:45 [PATCH v2 0/3] Split huge PMD mapping of vmemmap pages Muchun Song
2021-06-12 9:45 ` [PATCH v2 1/3] mm: sparsemem: split the " Muchun Song
2021-06-15 22:31 ` Mike Kravetz
2021-06-16 3:23 ` [External] " Muchun Song
2021-06-12 9:45 ` [PATCH v2 2/3] mm: sparsemem: use huge PMD mapping for " Muchun Song
2021-06-12 9:45 ` [PATCH v2 3/3] mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON Muchun Song
2021-06-15 23:00 ` Joao Martins
2021-06-16 3:04 ` [External] " Muchun Song
2021-06-15 1:12 ` [PATCH v2 0/3] Split huge PMD mapping of vmemmap pages Andrew Morton
2021-06-15 3:52 ` Mike Kravetz
2021-06-15 5:37 ` Muchun Song [this message]
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