[PATCH v2 00/22] mm: Add vma_lookup()

[Liam Howlett]

Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.

Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.

The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma.  This results in a bug that is often overlooked for a long time.

Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().

v2:
 - Changed find_vma_intersection() comments and whitespace to be
   compliant.  Thanks Davidlohr Bueso
 - Moved vma_lookup() call in vma_to_resize() to be separate from the
   declaration as requested by Davidlohr Bueso
 - Added Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> for 08/22
   "arch/m68k/kernel/sys_m68k: Use vma_lookup() in sys_cacheflush()"
 - Added Reviewed-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
 - Added Acked-by: Davidlohr Bueso <dbueso@xxxxxxx>

This patch set was originally part of the maple tree patch set.
Changes since being broken out on its own:
- Changed initial implementation of vma_lookup() to use find_vma() as requested
  by Michel Lespinasse.
- Updated commit comments to be more descriptive

These patches are based on next-20210506

Liam R. Howlett (22):
  mm: Add vma_lookup(), update find_vma_intersection() comments
  drm/i915/selftests: Use vma_lookup() in __igt_mmap()
  arch/arc/kernel/troubleshoot: use vma_lookup() instead of find_vma()
  arch/arm64/kvm: Use vma_lookup() instead of find_vma_intersection()
  arch/powerpc/kvm/book3s_hv_uvmem: Use vma_lookup() instead of
    find_vma_intersection()
  arch/powerpc/kvm/book3s: Use vma_lookup() in
    kvmppc_hv_setup_htab_rma()
  arch/mips/kernel/traps: Use vma_lookup() instead of find_vma()
  arch/m68k/kernel/sys_m68k: Use vma_lookup() in sys_cacheflush()
  x86/sgx: Use vma_lookup() in sgx_encl_find()
  virt/kvm: Use vma_lookup() instead of find_vma_intersection()
  vfio: Use vma_lookup() instead of find_vma_intersection()
  net/ipv5/tcp: Use vma_lookup() in tcp_zerocopy_receive()
  drm/amdgpu: Use vma_lookup() in amdgpu_ttm_tt_get_user_pages()
  media: videobuf2: Use vma_lookup() in get_vaddr_frames()
  misc/sgi-gru/grufault: Use vma_lookup() in gru_find_vma()
  kernel/events/uprobes: Use vma_lookup() in find_active_uprobe()
  lib/test_hmm: Use vma_lookup() in dmirror_migrate()
  mm/ksm: Use vma_lookup() in find_mergeable_vma()
  mm/migrate: Use vma_lookup() in do_pages_stat_array()
  mm/mremap: Use vma_lookup() in vma_to_resize()
  mm/memory.c: Use vma_lookup() in __access_remote_vm()
  mm/mempolicy: Use vma_lookup() in __access_remote_vm()

 arch/arc/kernel/troubleshoot.c                |  8 ++---
 arch/arm64/kvm/mmu.c                          |  2 +-
 arch/m68k/kernel/sys_m68k.c                   |  4 +--
 arch/mips/kernel/traps.c                      |  4 +--
 arch/powerpc/kvm/book3s_hv.c                  |  4 +--
 arch/powerpc/kvm/book3s_hv_uvmem.c            |  2 +-
 arch/x86/kernel/cpu/sgx/encl.h                |  4 +--
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       |  4 +--
 .../drm/i915/gem/selftests/i915_gem_mman.c    |  2 +-
 drivers/media/common/videobuf2/frame_vector.c |  2 +-
 drivers/misc/sgi-gru/grufault.c               |  4 +--
 drivers/vfio/vfio_iommu_type1.c               |  2 +-
 include/linux/mm.h                            | 36 ++++++++++++++++---
 kernel/events/uprobes.c                       |  4 +--
 lib/test_hmm.c                                |  5 ++-
 mm/ksm.c                                      |  6 ++--
 mm/memory.c                                   |  4 +--
 mm/mempolicy.c                                |  2 +-
 mm/migrate.c                                  |  4 +--
 mm/mremap.c                                   |  5 +--
 net/ipv4/tcp.c                                |  4 +--
 virt/kvm/kvm_main.c                           |  2 +-
 22 files changed, 69 insertions(+), 45 deletions(-)

-- 
2.30.2