Date:   Sat, 18 Feb 2023 00:43:00 +0000
Mime-Version: 1.0
Message-ID: <cover.1676680548.git.ackerleytng@google.com>
Subject: [RFC PATCH 0/2] Add flag as THP allocation hint 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,
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Cc:     aarcange@redhat.com, ak@linux.intel.com, akpm@linux-foundation.org,
        arnd@arndb.de, bfields@fieldses.org, bp@alien8.de,
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        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-rmfd-hugepa=
ge

Following the RFC to provide mount for memfd_restricted() syscall at
https://lore.kernel.org/lkml/cover.1676507663.git.ackerleytng@google.com/T/=
#u,
this patchset adds the RMFD_HUGEPAGE flag to the memfd_restricted()
syscall, which will hint the kernel to use Transparent HugePages to
back restrictedmem pages.

This supplements the interface proposed earlier, which requires the
creation of a tmpfs mount to be passed to memfd_restricted(), with a
more direct per-file hint.

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 fix for restrictedmem_getattr() as mentioned on the mailing
  list at
  https://lore.kernel.org/lkml/diqzzga0fv96.fsf@ackerleytng-cloudtop-sg.c.g=
ooglers.com/
+ Hugh=E2=80=99s patch:
  https://lore.kernel.org/lkml/c140f56a-1aa3-f7ae-b7d1-93da7d5a3572@google.=
com/,
  which provides functionality in shmem that reads the VM_HUGEPAGE
  flag in key functions shmem_is_huge() and shmem_get_inode()

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

Ackerley Tng (2):
  mm: restrictedmem: Add flag as THP allocation hint for
    memfd_restricted() syscall
  selftests: restrictedmem: Add selftest for RMFD_HUGEPAGE

 include/uapi/linux/restrictedmem.h            |  1 +
 mm/restrictedmem.c                            | 27 ++++++++++++-------
 .../restrictedmem_hugepage_test.c             | 25 +++++++++++++++++
 3 files changed, 43 insertions(+), 10 deletions(-)

--
2.39.2.637.g21b0678d19-goog