linux-kernel - [PATCH RFC 0/4] Optimize mremap during mutual alignment within PMD

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Message-ID: <20230518021825.712742-1-joel@joelfernandes.org>
Date:   Thu, 18 May 2023 02:18:21 +0000
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        linux-kselftest@...r.kernel.org, linux-mm@...ck.org,
        Shuah Khan <shuah@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Kirill A Shutemov <kirill@...temov.name>,
        "Liam R. Howlett" <liam.howlett@...cle.com>,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH RFC 0/4] Optimize mremap during mutual alignment within PMD

Hello,

I am posting this as an RFC for any feedback. I have tested them suitably and I
am continuing to test them.

These patches optimizes the start addresses in move_page_tables(). It addresses a
warning [1] that occurs due to a downward, overlapping move on a mutually-aligned
offset within a PMD during exec. By initiating the copy process at the PMD
level when such alignment is present, we can prevent this warning and speed up
the copying process at the same time. Linus Torvalds suggested this idea.

Please check the individual patches for more details.

thanks,

 - Joel

[1] https://lore.kernel.org/all/ZB2GTBD%2FLWTrkOiO@dhcp22.suse.cz/

Joel Fernandes (Google) (4):
mm/mremap: Optimize the start addresses in move_page_tables()
selftests: mm: Fix failure case when new remap region was not found
selftests: mm: Add a test for mutually aligned moves > PMD size
selftests: mm: Add a test for remapping to area immediately after
existing mapping

mm/mremap.c                              | 49 +++++++++++++++++
tools/testing/selftests/mm/mremap_test.c | 69 +++++++++++++++++++++---
2 files changed, 112 insertions(+), 6 deletions(-)

--
2.40.1.606.ga4b1b128d6-goog