[0/8] Add a new mmap locking API wrapping mmap_sem calls

Message

Michel Lespinasse March 26, 2020, 7:02 a.m. UTC

This patch series adds a new mmap locking API replacing the existing
mmap_sem lock and unlocks. Initially the API is just implemente in terms
of inlined rwsem calls, so it doesn't provide any new functionality.

There are two justifications for the new API:

- At first, it provides an easy hooking point to instrument mmap_sem
  locking latencies independently of any other rwsems.

- In the future, it may be a starting point for replacing the rwsem
  implementation with a different one, such as range locks. This is
  something that is being explored, even though there is no wide concensus
  about this possible direction yet.
  (see https://patchwork.kernel.org/cover/11401483/)

The changes apply on top of v5.6-rc7.

I think it would be feasible to apply them in the next merge cycle if
given sufficient approval.  The coccinelle part of the change is
relatively invasive, but can be skipped over on a file by file basis
if it causes any conflicts with other pending changes. The new mmap
locking API can interoperate with new code that is still using direct
rwsem calls, until the last patch in the series which renames mmap_sem
to enforce using the new API. Maybe that last patch could be delayed for
a bit, so that we'd get a chance to convert any new code that locks
mmap_sem in the -rc1 release before applying that last patch.

Michel Lespinasse (8):
  mmap locking API: initial implementation as rwsem wrappers
  MMU notifier: use the new mmap locking API
  mmap locking API: use coccinelle to convert mmap_sem rwsem call sites
  mmap locking API: convert mmap_sem call sites missed by coccinelle
  mmap locking API: convert nested write lock sites
  mmap locking API: add mmap_read_release() and mmap_read_unlock_non_owner()
  mmap locking API: add MMAP_LOCK_INITIALIZER
  mmap locking API: rename mmap_sem to mmap_lock

 arch/alpha/kernel/traps.c                     |  4 +-
 arch/alpha/mm/fault.c                         | 10 +--
 arch/arc/kernel/process.c                     |  4 +-
 arch/arc/kernel/troubleshoot.c                |  4 +-
 arch/arc/mm/fault.c                           |  4 +-
 arch/arm/kernel/process.c                     |  4 +-
 arch/arm/kernel/swp_emulate.c                 |  4 +-
 arch/arm/lib/uaccess_with_memcpy.c            | 16 ++--
 arch/arm/mm/fault.c                           |  6 +-
 arch/arm64/kernel/traps.c                     |  4 +-
 arch/arm64/kernel/vdso.c                      |  8 +-
 arch/arm64/mm/fault.c                         |  8 +-
 arch/csky/kernel/vdso.c                       |  4 +-
 arch/csky/mm/fault.c                          |  8 +-
 arch/hexagon/kernel/vdso.c                    |  4 +-
 arch/hexagon/mm/vm_fault.c                    |  8 +-
 arch/ia64/kernel/perfmon.c                    |  8 +-
 arch/ia64/mm/fault.c                          | 12 +--
 arch/ia64/mm/init.c                           | 12 +--
 arch/m68k/kernel/sys_m68k.c                   | 14 ++--
 arch/m68k/mm/fault.c                          |  8 +-
 arch/microblaze/mm/fault.c                    | 12 +--
 arch/mips/kernel/traps.c                      |  4 +-
 arch/mips/kernel/vdso.c                       |  4 +-
 arch/mips/mm/fault.c                          | 10 +--
 arch/nds32/kernel/vdso.c                      |  6 +-
 arch/nds32/mm/fault.c                         | 12 +--
 arch/nios2/mm/fault.c                         | 12 +--
 arch/nios2/mm/init.c                          |  4 +-
 arch/openrisc/mm/fault.c                      | 10 +--
 arch/parisc/kernel/traps.c                    |  6 +-
 arch/parisc/mm/fault.c                        |  8 +-
 arch/powerpc/kernel/vdso.c                    |  6 +-
 arch/powerpc/kvm/book3s_64_mmu_hv.c           |  4 +-
 arch/powerpc/kvm/book3s_hv.c                  |  6 +-
 arch/powerpc/kvm/book3s_hv_uvmem.c            | 12 +--
 arch/powerpc/kvm/e500_mmu_host.c              |  4 +-
 arch/powerpc/mm/book3s64/iommu_api.c          |  4 +-
 arch/powerpc/mm/book3s64/subpage_prot.c       | 12 +--
 arch/powerpc/mm/copro_fault.c                 |  4 +-
 arch/powerpc/mm/fault.c                       | 12 +--
 arch/powerpc/oprofile/cell/spu_task_sync.c    |  6 +-
 arch/powerpc/platforms/cell/spufs/file.c      |  4 +-
 arch/riscv/kernel/vdso.c                      |  4 +-
 arch/riscv/mm/fault.c                         | 10 +--
 arch/s390/kernel/vdso.c                       |  4 +-
 arch/s390/kvm/gaccess.c                       |  4 +-
 arch/s390/kvm/kvm-s390.c                      | 24 +++---
 arch/s390/kvm/priv.c                          | 32 ++++----
 arch/s390/mm/fault.c                          |  6 +-
 arch/s390/mm/gmap.c                           | 40 ++++-----
 arch/s390/pci/pci_mmio.c                      |  4 +-
 arch/sh/kernel/sys_sh.c                       |  6 +-
 arch/sh/kernel/vsyscall/vsyscall.c            |  4 +-
 arch/sh/mm/fault.c                            | 14 ++--
 arch/sparc/mm/fault_32.c                      | 18 ++--
 arch/sparc/mm/fault_64.c                      | 12 +--
 arch/sparc/vdso/vma.c                         |  4 +-
 arch/um/include/asm/mmu_context.h             |  5 +-
 arch/um/kernel/tlb.c                          |  2 +-
 arch/um/kernel/trap.c                         |  6 +-
 arch/unicore32/mm/fault.c                     |  6 +-
 arch/x86/entry/vdso/vma.c                     | 14 ++--
 arch/x86/events/core.c                        |  4 +-
 arch/x86/kernel/tboot.c                       |  2 +-
 arch/x86/kernel/vm86_32.c                     |  4 +-
 arch/x86/kvm/mmu/paging_tmpl.h                |  8 +-
 arch/x86/mm/fault.c                           | 10 +--
 arch/x86/um/vdso/vma.c                        |  4 +-
 arch/xtensa/mm/fault.c                        | 10 +--
 drivers/android/binder_alloc.c                | 10 +--
 drivers/dma-buf/dma-resv.c                    |  4 +-
 drivers/firmware/efi/efi.c                    |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |  4 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       | 10 +--
 drivers/gpu/drm/amd/amdkfd/kfd_events.c       |  4 +-
 drivers/gpu/drm/etnaviv/etnaviv_gem.c         |  2 +-
 drivers/gpu/drm/i915/gem/i915_gem_mman.c      |  4 +-
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c   |  8 +-
 drivers/gpu/drm/nouveau/nouveau_svm.c         | 20 ++---
 drivers/gpu/drm/radeon/radeon_cs.c            |  4 +-
 drivers/gpu/drm/radeon/radeon_gem.c           |  6 +-
 drivers/gpu/drm/ttm/ttm_bo_vm.c               |  4 +-
 drivers/infiniband/core/umem_odp.c            |  4 +-
 drivers/infiniband/core/uverbs_main.c         |  4 +-
 drivers/infiniband/hw/mlx4/mr.c               |  4 +-
 drivers/infiniband/hw/qib/qib_user_pages.c    |  6 +-
 drivers/infiniband/hw/usnic/usnic_uiom.c      |  4 +-
 drivers/infiniband/sw/siw/siw_mem.c           |  4 +-
 drivers/iommu/amd_iommu_v2.c                  |  4 +-
 drivers/iommu/intel-svm.c                     |  4 +-
 drivers/media/v4l2-core/videobuf-core.c       |  4 +-
 drivers/media/v4l2-core/videobuf-dma-contig.c |  4 +-
 drivers/media/v4l2-core/videobuf-dma-sg.c     |  4 +-
 drivers/misc/cxl/cxllib.c                     |  4 +-
 drivers/misc/cxl/fault.c                      |  4 +-
 drivers/misc/sgi-gru/grufault.c               | 16 ++--
 drivers/misc/sgi-gru/grufile.c                |  4 +-
 drivers/oprofile/buffer_sync.c                | 10 +--
 drivers/staging/kpc2000/kpc_dma/fileops.c     |  4 +-
 drivers/tee/optee/call.c                      |  4 +-
 drivers/vfio/vfio_iommu_type1.c               |  8 +-
 drivers/xen/gntdev.c                          |  4 +-
 drivers/xen/privcmd.c                         | 14 ++--
 fs/aio.c                                      |  4 +-
 fs/coredump.c                                 |  4 +-
 fs/exec.c                                     | 16 ++--
 fs/io_uring.c                                 |  4 +-
 fs/proc/base.c                                | 18 ++--
 fs/proc/task_mmu.c                            | 28 +++----
 fs/proc/task_nommu.c                          | 18 ++--
 fs/userfaultfd.c                              | 28 +++----
 include/linux/mm.h                            |  1 +
 include/linux/mm_types.h                      |  2 +-
 include/linux/mmap_lock.h                     | 82 +++++++++++++++++++
 include/linux/mmu_notifier.h                  |  5 +-
 ipc/shm.c                                     |  8 +-
 kernel/acct.c                                 |  4 +-
 kernel/bpf/stackmap.c                         | 13 ++-
 kernel/events/core.c                          |  4 +-
 kernel/events/uprobes.c                       | 16 ++--
 kernel/exit.c                                 |  8 +-
 kernel/fork.c                                 | 14 ++--
 kernel/futex.c                                |  4 +-
 kernel/sched/fair.c                           |  4 +-
 kernel/sys.c                                  | 18 ++--
 kernel/trace/trace_output.c                   |  4 +-
 mm/filemap.c                                  |  6 +-
 mm/frame_vector.c                             |  4 +-
 mm/gup.c                                      | 20 ++---
 mm/hmm.c                                      |  2 +-
 mm/init-mm.c                                  |  2 +-
 mm/internal.h                                 |  2 +-
 mm/khugepaged.c                               | 36 ++++----
 mm/ksm.c                                      | 34 ++++----
 mm/madvise.c                                  | 18 ++--
 mm/memcontrol.c                               |  8 +-
 mm/memory.c                                   | 14 ++--
 mm/mempolicy.c                                | 22 ++---
 mm/migrate.c                                  |  8 +-
 mm/mincore.c                                  |  4 +-
 mm/mlock.c                                    | 16 ++--
 mm/mmap.c                                     | 36 ++++----
 mm/mmu_notifier.c                             | 22 ++---
 mm/mprotect.c                                 | 12 +--
 mm/mremap.c                                   |  6 +-
 mm/msync.c                                    |  8 +-
 mm/nommu.c                                    | 16 ++--
 mm/oom_kill.c                                 |  4 +-
 mm/pagewalk.c                                 | 15 ++--
 mm/process_vm_access.c                        |  4 +-
 mm/ptdump.c                                   |  4 +-
 mm/swapfile.c                                 |  4 +-
 mm/userfaultfd.c                              | 14 ++--
 mm/util.c                                     | 12 +--
 net/ipv4/tcp.c                                |  4 +-
 net/xdp/xdp_umem.c                            |  4 +-
 virt/kvm/arm/mmu.c                            | 14 ++--
 virt/kvm/async_pf.c                           |  4 +-
 virt/kvm/kvm_main.c                           |  8 +-
 160 files changed, 778 insertions(+), 693 deletions(-)
 create mode 100644 include/linux/mmap_lock.h

Comments

Michel Lespinasse March 26, 2020, 7:13 a.m. UTC | #1

On Thu, Mar 26, 2020 at 12:02 AM Michel Lespinasse <[e-mail]> wrote:
> I think it would be feasible to apply them in the next merge cycle if
> given sufficient approval.

Reading this part back, maybe it sounds more pushy than I intended.
What I meant is that I think the code is ready to be submitted through
the normal channels, whatever release that lands it into.