[PATCH v5 00/17] device-dax: support sub-dividing soft-reserved ranges

[Dan Williams]

Changes since v4 [1]:
- Rebased on
  device-dax-move-instance-creation-parameters-to-struct-dev_dax_data.patch
  in -mm [2]. I.e. patches that did not need fixups from v4 are not
  included.

- Folded all fixes

- Replaced "device-dax: kill dax_kmem_res" with:

      device-dax/kmem: introduce dax_kmem_range()
      device-dax/kmem: move resource name tracking to drvdata
      device-dax/kmem: replace release_resource() with release_mem_region()

  ...to address David's request to make those cleanups easier to review.
  Note that I dropped changes to how IORESOURCE_BUSY is manipulated since
  David and I are still debating the best way forward there.

- Broke out some of dax-bus reworks in "device-dax: introduce 'seed'
  devices" to a new "device-dax: introduce 'struct dev_dax' typed-driver
  operations"

- Added a conversion of xen_alloc_unallocated_pages() from pgmap.res to
  pgmap.range. I found it odd that there is no corresponding
  memunmap_pages() triggered by xen_free_unallocated_pages()?

- Not included, a conversion of virtio_fs to use pgmap.range for its new
  usage of devm_memremap_pages(). It appears the virtio_fs changes are
  merged after -mm? My mental model of -mm was that it applies on top of
  linux-next? In any event, Vivek, you will need to coordinate a
  conversion to pgmap.range for the virtio_fs dax-support merge. Maybe
  that should go through Andrew as well?

- Lowercase all the subject lines per akpm's preference

- Received a 0day robot build-success notification over 122 configs

- Thanks to Joao for looking after this set while I was out.

[1]: http://lore.kernel.org/r/159625229779.3040297.11363509688097221416.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[2]: https://ozlabs.org/~akpm/mmots/broken-out/device-dax-move-instance-creation-parameters-to-struct-dev_dax_data.patch

---

Andrew, this series replaces

device-dax-make-pgmap-optional-for-instance-creation.patch

...through...

dax-hmem-introduce-dax_hmemregion_idle-parameter.patch

...in your stack.

Let me know if there is a different / preferred way to refresh a bulk of
patches in your queue when only a subset need updates.

---

The device-dax facility allows an address range to be directly mapped
through a chardev, or optionally hotplugged to the core kernel page
allocator as System-RAM. It is the mechanism for converting persistent
memory (pmem) to be used as another volatile memory pool i.e. the
current Memory Tiering hot topic on linux-mm.

In the case of pmem the nvdimm-namespace-label mechanism can sub-divide
it, but that labeling mechanism is not available / applicable to
soft-reserved ("EFI specific purpose") memory [3]. This series provides
a sysfs-mechanism for the daxctl utility to enable provisioning of
volatile-soft-reserved memory ranges.

The motivations for this facility are:

1/ Allow performance differentiated memory ranges to be split between
   kernel-managed and directly-accessed use cases.

2/ Allow physical memory to be provisioned along performance relevant
   address boundaries. For example, divide a memory-side cache [4] along
   cache-color boundaries.

3/ Parcel out soft-reserved memory to VMs using device-dax as a security
   / permissions boundary [5]. Specifically I have seen people (ab)using
   memmap=nn!ss (mark System-RAM as Persistent Memory) just to get the
   device-dax interface on custom address ranges. A follow-on for the VM
   use case is to teach device-dax to dynamically allocate 'struct page' at
   runtime to reduce the duplication of 'struct page' space in both the
   guest and the host kernel for the same physical pages.

[3]: http://lore.kernel.org/r/157309097008.1579826.12818463304589384434.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[4]: http://lore.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[5]: http://lore.kernel.org/r/20200110190313.17144-1-joao.m.martins@xxxxxxxxxx

---

Dan Williams (14):
      device-dax: make pgmap optional for instance creation
      device-dax/kmem: introduce dax_kmem_range()
      device-dax/kmem: move resource name tracking to drvdata
      device-dax/kmem: replace release_resource() with release_mem_region()
      device-dax: add an allocation interface for device-dax instances
      device-dax: introduce 'struct dev_dax' typed-driver operations
      device-dax: introduce 'seed' devices
      drivers/base: make device_find_child_by_name() compatible with sysfs inputs
      device-dax: add resize support
      mm/memremap_pages: convert to 'struct range'
      mm/memremap_pages: support multiple ranges per invocation
      device-dax: add dis-contiguous resource support
      device-dax: introduce 'mapping' devices
      device-dax: add an 'align' attribute

Joao Martins (3):
      device-dax: make align a per-device property
      dax/hmem: introduce dax_hmem.region_idle parameter
      device-dax: add a range mapping allocation attribute


 arch/powerpc/kvm/book3s_hv_uvmem.c     |   14 
 drivers/base/core.c                    |    2 
 drivers/dax/bus.c                      | 1039 ++++++++++++++++++++++++++++++--
 drivers/dax/bus.h                      |   11 
 drivers/dax/dax-private.h              |   58 ++
 drivers/dax/device.c                   |  112 ++-
 drivers/dax/hmem/hmem.c                |   17 -
 drivers/dax/kmem.c                     |  178 +++--
 drivers/dax/pmem/compat.c              |    2 
 drivers/dax/pmem/core.c                |   14 
 drivers/gpu/drm/nouveau/nouveau_dmem.c |   15 
 drivers/nvdimm/badrange.c              |   26 -
 drivers/nvdimm/claim.c                 |   13 
 drivers/nvdimm/nd.h                    |    3 
 drivers/nvdimm/pfn_devs.c              |   13 
 drivers/nvdimm/pmem.c                  |   27 -
 drivers/nvdimm/region.c                |   21 -
 drivers/pci/p2pdma.c                   |   12 
 drivers/xen/unpopulated-alloc.c        |   45 +
 include/linux/memremap.h               |   11 
 include/linux/range.h                  |    6 
 lib/test_hmm.c                         |   15 
 mm/memremap.c                          |  299 +++++----
 tools/testing/nvdimm/dax-dev.c         |   22 -
 tools/testing/nvdimm/test/iomap.c      |    2 
 25 files changed, 1557 insertions(+), 420 deletions(-)

base-commit: 6764736525f27a411ba2c0c430aaa2df7375f3ac