[PATCH v6 0/8] mmu notifier provide context informations

[jglisse]

From: JÃrÃme Glisse <jglisse@xxxxxxxxxx>

(Andrew this apply on top of my HMM patchset as otherwise you will have
 conflict with changes to mm/hmm.c)

Changes since v5:
    - drop KVM bits waiting for KVM people to express interest if they
      do not then i will post patchset to remove change_pte_notify as
      without the changes in v5 change_pte_notify is just useless (it
      it is useless today upstream it is just wasting cpu cycles)
    - rebase on top of lastest Linus tree

Previous cover letter with minor update:


Here i am not posting users of this, they already have been posted to
appropriate mailing list [6] and will be merge through the appropriate
tree once this patchset is upstream.

Note that this serie does not change any behavior for any existing
code. It just pass down more information to mmu notifier listener.

The rational for this patchset:

CPU page table update can happens for many reasons, not only as a
result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...)
but also as a result of kernel activities (memory compression, reclaim,
migration, ...).

This patch introduce a set of enums that can be associated with each
of the events triggering a mmu notifier:

    - UNMAP: munmap() or mremap()
    - CLEAR: page table is cleared (migration, compaction, reclaim, ...)
    - PROTECTION_VMA: change in access protections for the range
    - PROTECTION_PAGE: change in access protections for page in the range
    - SOFT_DIRTY: soft dirtyness tracking

Being able to identify munmap() and mremap() from other reasons why the
page table is cleared is important to allow user of mmu notifier to
update their own internal tracking structure accordingly (on munmap or
mremap it is not longer needed to track range of virtual address as it
becomes invalid). Without this serie, driver are force to assume that
every notification is an munmap which triggers useless trashing within
drivers that associate structure with range of virtual address. Each
driver is force to free up its tracking structure and then restore it
on next device page fault. With this serie we can also optimize device
page table update [6].

More over this can also be use to optimize out some page table updates
like for KVM where we can update the secondary MMU directly from the
callback instead of clearing it.

ACKS AMD/RADEON https://lkml.org/lkml/2019/2/1/395
ACKS RDMA https://lkml.org/lkml/2018/12/6/1473

Cheers,
JÃrÃme

[1] v1 https://lkml.org/lkml/2018/3/23/1049
[2] v2 https://lkml.org/lkml/2018/12/5/10
[3] v3 https://lkml.org/lkml/2018/12/13/620
[4] v4 https://lkml.org/lkml/2019/1/23/838
[5] v5 https://lkml.org/lkml/2019/2/19/752
[6] patches to use this:
    https://lkml.org/lkml/2019/1/23/833
    https://lkml.org/lkml/2019/1/23/834
    https://lkml.org/lkml/2019/1/23/832
    https://lkml.org/lkml/2019/1/23/831

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Christian KÃnig <christian.koenig@xxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-rdma@xxxxxxxxxxxxxxx
Cc: Arnd Bergmann <arnd@xxxxxxxx>

JÃrÃme Glisse (8):
  mm/mmu_notifier: helper to test if a range invalidation is blockable
  mm/mmu_notifier: convert user range->blockable to helper function
  mm/mmu_notifier: convert mmu_notifier_range->blockable to a flags
  mm/mmu_notifier: contextual information for event enums
  mm/mmu_notifier: contextual information for event triggering
    invalidation v2
  mm/mmu_notifier: use correct mmu_notifier events for each invalidation
  mm/mmu_notifier: pass down vma and reasons why mmu notifier is
    happening v2
  mm/mmu_notifier: mmu_notifier_range_update_to_read_only() helper

 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c  |  8 ++--
 drivers/gpu/drm/i915/i915_gem_userptr.c |  2 +-
 drivers/gpu/drm/radeon/radeon_mn.c      |  4 +-
 drivers/infiniband/core/umem_odp.c      |  5 +-
 drivers/xen/gntdev.c                    |  6 +--
 fs/proc/task_mmu.c                      |  3 +-
 include/linux/mmu_notifier.h            | 63 +++++++++++++++++++++++--
 kernel/events/uprobes.c                 |  3 +-
 mm/hmm.c                                |  6 +--
 mm/huge_memory.c                        | 14 +++---
 mm/hugetlb.c                            | 12 +++--
 mm/khugepaged.c                         |  3 +-
 mm/ksm.c                                |  6 ++-
 mm/madvise.c                            |  3 +-
 mm/memory.c                             | 25 ++++++----
 mm/migrate.c                            |  5 +-
 mm/mmu_notifier.c                       | 12 ++++-
 mm/mprotect.c                           |  4 +-
 mm/mremap.c                             |  3 +-
 mm/oom_kill.c                           |  3 +-
 mm/rmap.c                               |  6 ++-
 virt/kvm/kvm_main.c                     |  3 +-
 22 files changed, 147 insertions(+), 52 deletions(-)

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2.20.1