Date:   Thu, 16 Feb 2023 00:41:15 +0000
Mime-Version: 1.0
Message-ID: <cover.1676507663.git.ackerleytng@google.com>
Subject: [RFC PATCH 0/2] Providing mount for memfd_restricted() syscall
From:   Ackerley Tng <ackerleytng@google.com>
To:     kvm@vger.kernel.org, linux-api@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, qemu-devel@nongnu.org
Cc:     chao.p.peng@linux.intel.com, aarcange@redhat.com,
        ak@linux.intel.com, akpm@linux-foundation.org, arnd@arndb.de,
        bfields@fieldses.org, bp@alien8.de, corbet@lwn.net,
        dave.hansen@intel.com, david@redhat.com, ddutile@redhat.com,
        dhildenb@redhat.com, hpa@zytor.com, hughd@google.com,
        jlayton@kernel.org, jmattson@google.com, joro@8bytes.org,
        jun.nakajima@intel.com, kirill.shutemov@linux.intel.com,
        linmiaohe@huawei.com, luto@kernel.org, mail@maciej.szmigiero.name,
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        rppt@kernel.org, seanjc@google.com, shuah@kernel.org,
        steven.price@arm.com, tabba@google.com, tglx@linutronix.de,
        vannapurve@google.com, vbabka@suse.cz, vkuznets@redhat.com,
        wanpengli@tencent.com, wei.w.wang@intel.com, x86@kernel.org,
        yu.c.zhang@linux.intel.com, Ackerley Tng <ackerleytng@google.com>
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Hello,

This patchset builds upon the memfd_restricted() system call that has
been discussed in the =E2=80=98KVM: mm: fd-based approach for supporting KV=
M=E2=80=99
patch series, at
https://lore.kernel.org/lkml/20221202061347.1070246-1-chao.p.peng@linux.int=
el.com/T/#m7e944d7892afdd1d62a03a287bd488c56e377b0c

The tree can be found at:
https://github.com/googleprodkernel/linux-cc/tree/restrictedmem-provide-mou=
nt-path

In this patchset, a modification to the memfd_restricted() syscall is
proposed, which allows userspace to provide a mount, on which the file
will be created and returned from the memfd_restricted().

Allowing userspace to provide a mount allows userspace to control
various memory binding policies via tmpfs mount options, such as
Transparent HugePage memory allocation policy through
=E2=80=98huge=3Dalways/never=E2=80=99 and NUMA memory allocation policy thr=
ough
=E2=80=98mpol=3Dlocal/bind:*=E2=80=99.

Dependencies:
+ Sean=E2=80=99s iteration of the =E2=80=98KVM: mm: fd-based approach for s=
upporting
  KVM=E2=80=99 patch series at
  https://github.com/sean-jc/linux/tree/x86/upm_base_support
+ Proposed fixes for these issues mentioned on the mailing list:
    + https://lore.kernel.org/lkml/diqzzga0fv96.fsf@ackerleytng-cloudtop-sg=
.c.googlers.com/

Future work/TODOs:
+ man page for the memfd_restricted() syscall
+ Support for per file Transparent HugePage allocation hints
+ Support for per file NUMA binding hints

Ackerley Tng (2):
  mm: restrictedmem: Allow userspace to specify mount_path for
    memfd_restricted
  selftests: restrictedmem: Check hugepage-ness of shmem file backing
    restrictedmem fd

 include/linux/syscalls.h                      |   2 +-
 include/uapi/linux/restrictedmem.h            |   8 +
 mm/restrictedmem.c                            |  63 +++-
 tools/testing/selftests/Makefile              |   1 +
 .../selftests/restrictedmem/.gitignore        |   3 +
 .../testing/selftests/restrictedmem/Makefile  |  14 +
 .../testing/selftests/restrictedmem/common.c  |   9 +
 .../testing/selftests/restrictedmem/common.h  |   8 +
 .../restrictedmem_hugepage_test.c             | 344 ++++++++++++++++++
 9 files changed, 445 insertions(+), 7 deletions(-)
 create mode 100644 include/uapi/linux/restrictedmem.h
 create mode 100644 tools/testing/selftests/restrictedmem/.gitignore
 create mode 100644 tools/testing/selftests/restrictedmem/Makefile
 create mode 100644 tools/testing/selftests/restrictedmem/common.c
 create mode 100644 tools/testing/selftests/restrictedmem/common.h
 create mode 100644 tools/testing/selftests/restrictedmem/restrictedmem_hug=
epage_test.c

--
2.39.1.637.g21b0678d19-goog