On 8/6/19 4:15 PM, Jason Gunthorpe wrote:
From: Jason Gunthorpe jgg@mellanox.com
This series introduces a new registration flow for mmu_notifiers based on the idea that the user would like to get a single refcounted piece of memory for a mm, keyed to its use.
For instance many users of mmu_notifiers use an interval tree or similar to dispatch notifications to some object. There are many objects but only one notifier subscription per mm holding the tree.
Of the 12 places that call mmu_notifier_register:
7 are maintaining some kind of obvious mapping of mm_struct to mmu_notifier registration, ie in some linked list or hash table. Of the 7 this series converts 4 (gru, hmm, RDMA, radeon)
3 (hfi1, gntdev, vhost) are registering multiple notifiers, but each one immediately does some VA range filtering, ie with an interval tree. These would be better with a global subsystem-wide range filter and could convert to this API.
2 (kvm, amd_iommu) are deliberately using a single mm at a time, and really can't use this API. One of the intel-svm's modes is also in this list
The 3/7 unconverted drivers are:
intel-svm This driver tracks mm's in a global linked list 'global_svm_list' and would benefit from this API.
Its flow is a bit complex, since it also wants a set of non-shared notifiers.
i915_gem_usrptr This driver tracks mm's in a per-device hash table (dev_priv->mm_structs), but only has an optional use of mmu_notifiers. Since it still seems to need the hash table it is difficult to convert.
amdkfd/kfd_process This driver is using a global SRCU hash table to track mm's
The control flow here is very complicated and the driver is relying on this hash table to be fast on the ioctl syscall path.
It would definitely benefit, but only if the ioctl path didn't need to do the search so often.
This series is already entangled with patches in the hmm & RDMA tree and will require some git topic branches for the RDMA ODP stuff. I intend for it to go through the hmm tree.
There is a git version here:
https://github.com/jgunthorpe/linux/commits/mmu_notifier
Which has the required pre-patches for the RDMA ODP conversion that are still being reviewed.
Jason Gunthorpe (11): mm/mmu_notifiers: hoist do_mmu_notifier_register down_write to the caller mm/mmu_notifiers: do not speculatively allocate a mmu_notifier_mm mm/mmu_notifiers: add a get/put scheme for the registration misc/sgi-gru: use mmu_notifier_get/put for struct gru_mm_struct hmm: use mmu_notifier_get/put for 'struct hmm' RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm' RDMA/odp: remove ib_ucontext from ib_umem drm/radeon: use mmu_notifier_get/put for struct radeon_mn drm/amdkfd: fix a use after free race with mmu_notifer unregister drm/amdkfd: use mmu_notifier_put mm/mmu_notifiers: remove unregister_no_release
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 1 + drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 3 - drivers/gpu/drm/amd/amdkfd/kfd_process.c | 88 ++++----- drivers/gpu/drm/nouveau/nouveau_drm.c | 3 + drivers/gpu/drm/radeon/radeon.h | 3 - drivers/gpu/drm/radeon/radeon_device.c | 2 - drivers/gpu/drm/radeon/radeon_drv.c | 2 + drivers/gpu/drm/radeon/radeon_mn.c | 157 ++++------------ drivers/infiniband/core/umem.c | 4 +- drivers/infiniband/core/umem_odp.c | 183 ++++++------------ drivers/infiniband/core/uverbs_cmd.c | 3 - drivers/infiniband/core/uverbs_main.c | 1 + drivers/infiniband/hw/mlx5/main.c | 5 - drivers/misc/sgi-gru/grufile.c | 1 + drivers/misc/sgi-gru/grutables.h | 2 - drivers/misc/sgi-gru/grutlbpurge.c | 84 +++------ include/linux/hmm.h | 12 +- include/linux/mm_types.h | 6 - include/linux/mmu_notifier.h | 40 +++- include/rdma/ib_umem.h | 2 +- include/rdma/ib_umem_odp.h | 10 +- include/rdma/ib_verbs.h | 3 - kernel/fork.c | 1 - mm/hmm.c | 121 +++--------- mm/mmu_notifier.c | 230 +++++++++++++++++------ 25 files changed, 408 insertions(+), 559 deletions(-)
For the core MM, HMM, and nouveau changes you can add: Tested-by: Ralph Campbell rcampbell@nvidia.com