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Jason Gunthorpe says: ==================== Add mmu_notifier_get/put for managing mmu notifier registrations 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. ==================== Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.