[PATCH v3 00/10] Add a new mmap locking API wrapping mmap_sem calls

Michel Lespinasse
2020-03-27T22:51:09Z

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/)

Changes since v2 of the patchset:

- Removed the mmap_is_locked API - v2 had removed all uses of it,
but the actual function definition was still there unused.
Thanks to Jason Gunthorpe for noticing the unused mmap_is_locked function.

Changes since v1 of the patchset:

- Manually convert drivers/dma-buf/dma-resv.c ahead of the automated
coccinelle conversion as this file requires a new include statement.
Thanks to Intel's kbuild test bot for finding the issue.

- In coccinelle automated conversion, apply a single coccinelle rule
as suggested by Markus Elfring.

- In manual conversion of sites missed by coccinelle, fix an issue where
I had used mm_read_unlock (from an older version of my patchset) instead
of mmap_read_unlock in some arch/mips code.
This was also identified by Intel's kbuild test bot.

- Do not add a new mmap_is_locked API, and use lockdep_assert_held instead.
Thanks to Jason Gunthorpe and Matthew Wilcox for the suggestion.

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

I think it would be feasible to push these changes towards mainline 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 (10):
mmap locking API: initial implementation as rwsem wrappers
MMU notifier: use the new mmap locking API
DMA reservations: 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: use lockdep_assert_held
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 | 5 +-
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 | 77 +++++++++++++++++++
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, 774 insertions(+), 693 deletions(-)
create mode 100644 include/linux/mmap_lock.h

--
2.26.0.rc2.310.g2932bb562d-goog