linux-stable/drivers/nvdimm
Linus Torvalds f67e3fb489 device-dax for 5.1
* Replace the /sys/class/dax device model with /sys/bus/dax, and include
   a compat driver so distributions can opt-in to the new ABI.
 
 * Allow for an alternative driver for the device-dax address-range
 
 * Introduce the 'kmem' driver to hotplug / assign a device-dax
   address-range to the core-mm.
 
 * Arrange for the device-dax target-node to be onlined so that the newly
   added memory range can be uniquely referenced by numa apis.
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Merge tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull device-dax updates from Dan Williams:
 "New device-dax infrastructure to allow persistent memory and other
  "reserved" / performance differentiated memories, to be assigned to
  the core-mm as "System RAM".

  Some users want to use persistent memory as additional volatile
  memory. They are willing to cope with potential performance
  differences, for example between DRAM and 3D Xpoint, and want to use
  typical Linux memory management apis rather than a userspace memory
  allocator layered over an mmap() of a dax file. The administration
  model is to decide how much Persistent Memory (pmem) to use as System
  RAM, create a device-dax-mode namespace of that size, and then assign
  it to the core-mm. The rationale for device-dax is that it is a
  generic memory-mapping driver that can be layered over any "special
  purpose" memory, not just pmem. On subsequent boots udev rules can be
  used to restore the memory assignment.

  One implication of using pmem as RAM is that mlock() no longer keeps
  data off persistent media. For this reason it is recommended to enable
  NVDIMM Security (previously merged for 5.0) to encrypt pmem contents
  at rest. We considered making this recommendation an actively enforced
  requirement, but in the end decided to leave it as a distribution /
  administrator policy to allow for emulation and test environments that
  lack security capable NVDIMMs.

  Summary:

   - Replace the /sys/class/dax device model with /sys/bus/dax, and
     include a compat driver so distributions can opt-in to the new ABI.

   - Allow for an alternative driver for the device-dax address-range

   - Introduce the 'kmem' driver to hotplug / assign a device-dax
     address-range to the core-mm.

   - Arrange for the device-dax target-node to be onlined so that the
     newly added memory range can be uniquely referenced by numa apis"

NOTE! I'm not entirely happy with the whole "PMEM as RAM" model because
we currently have special - and very annoying rules in the kernel about
accessing PMEM only with the "MC safe" accessors, because machine checks
inside the regular repeat string copy functions can be fatal in some
(not described) circumstances.

And apparently the PMEM modules can cause that a lot more than regular
RAM.  The argument is that this happens because PMEM doesn't necessarily
get scrubbed at boot like RAM does, but that is planned to be added for
the user space tooling.

Quoting Dan from another email:
 "The exposure can be reduced in the volatile-RAM case by scanning for
  and clearing errors before it is onlined as RAM. The userspace tooling
  for that can be in place before v5.1-final. There's also runtime
  notifications of errors via acpi_nfit_uc_error_notify() from
  background scrubbers on the DIMM devices. With that mechanism the
  kernel could proactively clear newly discovered poison in the volatile
  case, but that would be additional development more suitable for v5.2.

  I understand the concern, and the need to highlight this issue by
  tapping the brakes on feature development, but I don't see PMEM as RAM
  making the situation worse when the exposure is also there via DAX in
  the PMEM case. Volatile-RAM is arguably a safer use case since it's
  possible to repair pages where the persistent case needs active
  application coordination"

* tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  device-dax: "Hotplug" persistent memory for use like normal RAM
  mm/resource: Let walk_system_ram_range() search child resources
  mm/memory-hotplug: Allow memory resources to be children
  mm/resource: Move HMM pr_debug() deeper into resource code
  mm/resource: Return real error codes from walk failures
  device-dax: Add a 'modalias' attribute to DAX 'bus' devices
  device-dax: Add a 'target_node' attribute
  device-dax: Auto-bind device after successful new_id
  acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node
  device-dax: Add /sys/class/dax backwards compatibility
  device-dax: Add support for a dax override driver
  device-dax: Move resource pinning+mapping into the common driver
  device-dax: Introduce bus + driver model
  device-dax: Start defining a dax bus model
  device-dax: Remove multi-resource infrastructure
  device-dax: Kill dax_region base
  device-dax: Kill dax_region ida
2019-03-16 13:05:32 -07:00
..
badrange.c libnvdimm, badrange: remove a WARN for list_empty 2017-11-02 10:42:30 -07:00
blk.c block: genhd: add 'groups' argument to device_add_disk 2018-09-28 08:30:28 -06:00
btt.c libnvdimm/btt: Fix LBA masking during 'free list' population 2019-02-28 09:57:39 -08:00
btt.h libnvdimm/btt: Fix LBA masking during 'free list' population 2019-02-28 09:57:39 -08:00
btt_devs.c libnvdimm/btt: Fix LBA masking during 'free list' population 2019-02-28 09:57:39 -08:00
bus.c libnvdimm: Schedule device registration on node local to the device 2019-01-31 14:20:54 +01:00
claim.c libnvdimm, pmem: Fix memcpy_mcsafe() return code handling in nsio_rw_bytes() 2018-06-28 18:21:30 -07:00
core.c libnvdimm: remove redundant __func__ in dev_dbg 2018-03-06 08:44:17 -08:00
dax_devs.c libnvdimm: remove redundant __func__ in dev_dbg 2018-03-06 08:44:17 -08:00
dimm.c libnvdimm/security: Require nvdimm_security_setup_events() to succeed 2019-01-21 09:57:43 -08:00
dimm_devs.c Merge branch 'for-5.1/libnvdimm' into libnvdimm-for-next 2019-03-11 12:13:42 -07:00
e820.c acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node 2019-01-06 21:41:57 -08:00
Kconfig acpi/nfit, libnvdimm: Add unlock of nvdimm support for Intel DIMMs 2018-12-13 17:54:13 -08:00
label.c libnvdimm/dimm: Add a no-BLK quirk based on NVDIMM family 2019-02-02 16:35:26 -08:00
label.h nvdimm: Use namespace index data to reduce number of label reads needed 2018-10-12 08:39:31 -07:00
Makefile acpi/nfit, libnvdimm: Add unlock of nvdimm support for Intel DIMMs 2018-12-13 17:54:13 -08:00
namespace_devs.c Merge branch 'for-5.1/libnvdimm-start-pad' into libnvdimm-for-next 2019-03-11 12:20:30 -07:00
nd-core.h libnvdimm/security: Fix nvdimm_security_state() state request selection 2019-01-15 13:54:33 -08:00
nd.h device-dax for 5.1 2019-03-16 13:05:32 -07:00
of_pmem.c device-dax for 5.1 2019-03-16 13:05:32 -07:00
pfn.h libnvdimm, dax: autodetect support 2016-05-20 22:02:57 -07:00
pfn_devs.c libnvdimm/pfn: Remove dax_label_reserve 2019-02-22 11:52:32 -08:00
pmem.c Merge branch 'akpm' (patches from Andrew) 2018-12-28 16:55:46 -08:00
pmem.h libnvdimm, pmem: Restore page attributes when clearing errors 2018-08-20 09:22:45 -07:00
region.c libnvdimm, region: quiet region probe 2018-04-07 07:47:10 -07:00
region_devs.c device-dax for 5.1 2019-03-16 13:05:32 -07:00
security.c libnvdimm/security: Quiet security operations 2018-12-22 11:35:41 -08:00