Am 15.10.19 um 20:12 schrieb Jason Gunthorpe:
From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
8 of the mmu_notifier using drivers (i915_gem, radeon_mn, umem_odp, hfi1,
scif_dma, vhost, gntdev, hmm) drivers are using a common pattern where
they only use invalidate_range_start/end and immediately check the
invalidating range against some driver data structure to tell if the
driver is interested. Half of them use an interval_tree, the others are
simple linear search lists.
Of the ones I checked they largely seem to have various kinds of races,
bugs and poor implementation. This is a result of the complexity in how
the notifier interacts with get_user_pages(). It is extremely difficult to
use it correctly.
Consolidate all of this code together into the core mmu_notifier and
provide a locking scheme similar to hmm_mirror that allows the user to
safely use get_user_pages() and reliably know if the page list still
matches the mm.
That sounds really good, but could you outline for a moment how that is
archived?
Please keep in mind that the page reference get_user_pages() grabs is
*NOT* sufficient to guarantee coherency here.
Regards,
Christian.
This new arrangment plays nicely with the !blockable mode for
OOM. Scanning the interval tree is done such that the intersection test
will always succeed, and since there is no invalidate_range_end exposed to
drivers the scheme safely allows multiple drivers to be subscribed.
Four places are converted as an example of how the new API is used.
Four are left for future patches:
- i915_gem has complex locking around destruction of a registration,
needs more study
- hfi1 (2nd user) needs access to the rbtree
- scif_dma has a complicated logic flow
- vhost's mmu notifiers are already being rewritten
This is still being tested, but I figured to send it to start getting help
from the xen, amd and hfi drivers which I cannot test here.
It would be intended for the hmm tree.
Jason Gunthorpe (15):
mm/mmu_notifier: define the header pre-processor parts even if
disabled
mm/mmu_notifier: add an interval tree notifier
mm/hmm: allow hmm_range to be used with a mmu_range_notifier or
hmm_mirror
mm/hmm: define the pre-processor related parts of hmm.h even if
disabled
RDMA/odp: Use mmu_range_notifier_insert()
RDMA/hfi1: Use mmu_range_notifier_inset for user_exp_rcv
drm/radeon: use mmu_range_notifier_insert
xen/gntdev: Use select for DMA_SHARED_BUFFER
xen/gntdev: use mmu_range_notifier_insert
nouveau: use mmu_notifier directly for invalidate_range_start
nouveau: use mmu_range_notifier instead of hmm_mirror
drm/amdgpu: Call find_vma under mmap_sem
drm/amdgpu: Use mmu_range_insert instead of hmm_mirror
drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror
mm/hmm: remove hmm_mirror and related
Documentation/vm/hmm.rst | 105 +---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 +
.../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 9 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 14 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 445 ++------------
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h | 53 --
drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 13 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 111 ++--
drivers/gpu/drm/nouveau/nouveau_svm.c | 229 +++++---
drivers/gpu/drm/radeon/radeon.h | 9 +-
drivers/gpu/drm/radeon/radeon_mn.c | 218 ++-----
drivers/infiniband/core/device.c | 1 -
drivers/infiniband/core/umem_odp.c | 288 +---------
drivers/infiniband/hw/hfi1/file_ops.c | 2 +-
drivers/infiniband/hw/hfi1/hfi.h | 2 +-
drivers/infiniband/hw/hfi1/user_exp_rcv.c | 144 ++---
drivers/infiniband/hw/hfi1/user_exp_rcv.h | 3 +-
drivers/infiniband/hw/mlx5/mlx5_ib.h | 7 +-
drivers/infiniband/hw/mlx5/mr.c | 3 +-
drivers/infiniband/hw/mlx5/odp.c | 48 +-
drivers/xen/Kconfig | 3 +-
drivers/xen/gntdev-common.h | 8 +-
drivers/xen/gntdev.c | 179 ++----
include/linux/hmm.h | 195 +------
include/linux/mmu_notifier.h | 124 +++-
include/rdma/ib_umem_odp.h | 65 +--
include/rdma/ib_verbs.h | 2 -
kernel/fork.c | 1 -
mm/Kconfig | 2 +-
mm/hmm.c | 275 +--------
mm/mmu_notifier.c | 542 +++++++++++++++++-
32 files changed, 1180 insertions(+), 1923 deletions(-)
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