Feedback-ID: iccd040f4:Fastmail
From:   Zi Yan <zi.yan@sent.com>
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Yang Shi <shy828301@gmail.com>, Yu Zhao <yuzhao@google.com>,
        linux-mm@kvack.org
Cc:     Zi Yan <ziy@nvidia.com>, Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH 0/5] Split a folio to any lower order folios
Date:   Mon, 20 Mar 2023 20:48:24 -0400
Message-Id: <20230321004829.2012847-1-zi.yan@sent.com>
Reply-To: Zi Yan <ziy@nvidia.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

From: Zi Yan <ziy@nvidia.com>

Hi all,

File folio supports any order and people would like to support flexible ord=
ers
for anonymous folio[1] too. Currently, split_huge_page() only splits a huge
page to order-0 pages, but splitting to orders higher than 0 is also useful.
This patchset adds support for splitting a huge page to any lower order pag=
es
and uses it during folio truncate operations.

The patchset is on top of mm-everything-2023-03-19-21-50.

* Patch 1 and 2 add new_order parameter split_page_memcg() and
  split_page_owner() and prepare for upcoming changes.
* Patch 3 adds split_huge_page_to_list_to_order() to split a huge page
  to any lower order. The original split_huge_page_to_list() calls
  split_huge_page_to_list_to_order() with new_order =3D 0.
* Patch 4 uses split_huge_page_to_list_to_order() in large pagecache folio
  truncation instead of split the large folio all the way down to order-0.
* Patch 5 adds a test API to debugfs and test cases in
  split_huge_page_test selftests.

Comments and/or suggestions are welcome.

[1] https://lore.kernel.org/linux-mm/Y%2FblF0GIunm+pRIC@casper.infradead.or=
g/

Zi Yan (5):
  mm: memcg: make memcg huge page split support any order split.
  mm: page_owner: add support for splitting to any order in split
    page_owner.
  mm: thp: split huge page to any lower order pages.
  mm: truncate: split huge page cache page to a non-zero order if
    possible.
  mm: huge_memory: enable debugfs to split huge pages to any order.

 include/linux/huge_mm.h                       |  10 +-
 include/linux/memcontrol.h                    |   5 +-
 include/linux/page_owner.h                    |  12 +-
 mm/huge_memory.c                              | 138 ++++++++---
 mm/memcontrol.c                               |   8 +-
 mm/page_alloc.c                               |   8 +-
 mm/page_owner.c                               |  11 +-
 mm/truncate.c                                 |  21 +-
 .../selftests/mm/split_huge_page_test.c       | 225 +++++++++++++++++-
 9 files changed, 368 insertions(+), 70 deletions(-)

--=20
2.39.2