performance: address_space: add padding for i_map and i_mmap_rwsem to mitigate a false sharing

[Philip Cox]

This is a public version of https://bugs.launchpad.net/bugs/2034983

[Description]
  When running UnixBench/shell1&shell8&exelc cases, we observed high false sharing for accessing i_mmap against i_mmap_rwsem.
  The patch places the i_mmap and i_mmap_rwsem in separate cache lines to avoid this false sharing problem.

[Hardware Information]
  Architecture:
    Intel / AMD (x86_64)
  Platform(s):
    DNP
  Date HW is expected at Canonical:

  Component(s):
    Performance and Scalability

[Software Information]
  Target Version:
    23.10
  Target Kernel:
    TBD
  Commit IDs:
    aee79d4e5271 fs/address_space: add alignment padding for i_map and i_mmap_rwsem to mitigate a false sharing.
  External Links:

[Business Justification]

[Testing guidance]

[External ID]
  OSVE-5159

Here's the commit ID: aee79d4e5271cee4ffa89ed830189929a6272eb8

https://github.com/torvalds/linux/commit/aee79d4e5271cee4ffa89ed830189929a6272eb8

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/5.15.0-102.112 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux' to 'verification-done-jammy-linux'. If the problem still exists, change the tag 'verification-needed-jammy-linux' to 'verification-failed-jammy-linux'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-aws-fips/5.15.0-1057.63+fips1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-aws-fips' to 'verification-done-jammy-linux-aws-fips'. If the problem still exists, change the tag 'verification-needed-jammy-linux-aws-fips' to 'verification-failed-jammy-linux-aws-fips'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-aws-5.15/5.15.0-1057.63~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-aws-5.15' to 'verification-done-focal-linux-aws-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-aws-5.15' to 'verification-failed-focal-linux-aws-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra/5.15.0-1023.23 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-nvidia-tegra' to 'verification-done-jammy-linux-nvidia-tegra'. If the problem still exists, change the tag 'verification-needed-jammy-linux-nvidia-tegra' to 'verification-failed-jammy-linux-nvidia-tegra'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra-5.15/5.15.0-1023.23~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-nvidia-tegra-5.15' to 'verification-done-focal-linux-nvidia-tegra-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-nvidia-tegra-5.15' to 'verification-failed-focal-linux-nvidia-tegra-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.15.0-102.112

---------------
linux (5.15.0-102.112) jammy; urgency=medium

  * jammy/linux: 5.15.0-102.112 -proposed tracker (LP: #2055632)

  * Drop ABI checks from kernel build (LP: #2055686)
    - [Packaging] Remove in-tree abi checks
    - [Packaging] Drop abi checks from final-checks

  * Packaging resync (LP: #1786013)
    - [Packaging] drop ABI data
    - [Packaging] update annotations scripts
    - debian.master/dkms-versions -- update from kernel-versions (main/2024.03.04)

  * block/loop: No longer allows to create partitions (LP: #2056143)
    - block, loop: support partitions without scanning

  * Cranky update-dkms-versions rollout (LP: #2055685)
    - [Packaging] remove update-dkms-versions
    - Move debian/dkms-versions to debian.master/dkms-versions
    - [Packaging] Replace debian/dkms-versions with $(DEBIAN)/dkms-versions
    - [Packaging] remove update-version-dkms

  * linux: please move erofs.ko (CONFIG_EROFS for EROFS support) from linux-
    modules-extra to linux-modules (LP: #2054809)
    - UBUNTU [Packaging]: Include erofs in linux-modules instead of linux-modules-
      extra

  * linux-tools-common: man page of usbip[d] is misplaced (LP: #2054094)
    - [Packaging] rules: Put usbip manpages in the correct directory

  * CVE-2024-23851
    - dm ioctl: log an error if the ioctl structure is corrupted
    - dm: limit the number of targets and parameter size area

  * CVE-2024-23850
    - btrfs: do not ASSERT() if the newly created subvolume already got read

  * x86: performance: tsc: Extend watchdog check exemption to 4-Sockets platform
    (LP: #2054699)
    - x86/tsc: Extend watchdog check exemption to 4-Sockets platform

  * linux: please move dmi-sysfs.ko (CONFIG_DMI_SYSFS for SMBIOS support) from
    linux-modules-extra to linux-modules (LP: #2045561)
    - [Packaging] Move dmi-sysfs.ko into linux-modules

  * Fix bpf selftests build failure after v5.15.139 update (LP: #2054567)
    - Revert "selftests/bpf: Test tail call counting with bpf2bpf and data on
      stack"

  * Jammy update: v5.15.148 upstream stable release (LP: #2055145)
    - f2fs: explicitly null-terminate the xattr list
    - pinctrl: lochnagar: Don't build on MIPS
    - ALSA: hda - Fix speaker and headset mic pin config for CHUWI CoreBook XPro
    - mptcp: fix uninit-value in mptcp_incoming_options
    - wifi: cfg80211: lock wiphy mutex for rfkill poll
    - debugfs: fix automount d_fsdata usage
    - drm/amdgpu: Fix cat debugfs amdgpu_regs_didt causes kernel null pointer
    - nvme-core: check for too small lba shift
    - ASoC: wm8974: Correct boost mixer inputs
    - ASoC: Intel: Skylake: Fix mem leak in few functions
    - ASoC: nau8822: Fix incorrect type in assignment and cast to restricted
      __be16
    - ASoC: Intel: Skylake: mem leak in skl register function
    - ASoC: cs43130: Fix the position of const qualifier
    - ASoC: cs43130: Fix incorrect frame delay configuration
    - ASoC: rt5650: add mutex to avoid the jack detection failure
    - nouveau/tu102: flush all pdbs on vmm flush
    - net/tg3: fix race condition in tg3_reset_task()
    - ASoC: da7219: Support low DC impedance hea...

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-intel-iotg/5.15.0-1052.58 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-intel-iotg' to 'verification-done-jammy-linux-intel-iotg'. If the problem still exists, change the tag 'verification-needed-jammy-linux-intel-iotg' to 'verification-failed-jammy-linux-intel-iotg'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1040.42 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-oracle-5.15/5.15.0-1055.61~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-oracle-5.15' to 'verification-done-focal-linux-oracle-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-oracle-5.15' to 'verification-failed-focal-linux-oracle-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra-igx/5.15.0-1010.10 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-nvidia-tegra-igx' to 'verification-done-jammy-linux-nvidia-tegra-igx'. If the problem still exists, change the tag 'verification-needed-jammy-linux-nvidia-tegra-igx' to 'verification-failed-jammy-linux-nvidia-tegra-igx'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-xilinx-zynqmp/5.15.0-1029.33 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-xilinx-zynqmp' to 'verification-done-jammy-linux-xilinx-zynqmp'. If the problem still exists, change the tag 'verification-needed-jammy-linux-xilinx-zynqmp' to 'verification-failed-jammy-linux-xilinx-zynqmp'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!