Pull dax updates from Dan Williams:
 "The fruits of a bug hunt in the fsdax implementation with Willy and a
  small feature update for device-dax:

   - Fix a hang condition that started triggering after the Xarray
     conversion of fsdax in the v4.20 kernel.

   - Add a 'resource' (root-only physical base address) sysfs attribute
     to device-dax instances to correlate memory-blocks onlined via the
     kmem driver with a given device instance"

* tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Fix missed wakeup with PMD faults
  device-dax: Add a 'resource' attribute

This patch adds 'DAXDEV_SYNC' flag which is set
for nd_region doing synchronous flush. This later
is used to disable MAP_SYNC functionality for
ext4 & xfs filesystem for devices don't support
synchronous flush.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

device-dax based devices were missing a 'resource' attribute to indicate
the physical address range contributed by the device in question. This
information is desirable to userspace tooling that may want to use the
dax device as system-ram, and wants to selectively hotplug and online
the memory blocks associated with a given device.

Without this, the tooling would have to parse /proc/iomem for the memory
ranges contributed by dax devices, which can be a workaround, but it is
far easier to provide this information in the sysfs hierarchy.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add a 'modalias' attribute to devices under the DAX bus so that userspace
is able to dynamically load modules as needed.

Normally, udev can get the modalias from 'uevent', and that is correctly
set up by the DAX bus. However other tooling such as 'libndctl' for
interacting with drivers/nvdimm/, and 'libdaxctl' for drivers/dax/ can
also use the modalias to dynamically load modules via libkmod lookups.

The 'nd' bus set up by the libnvdimm subsystem exports a modalias
attribute. Imitate this to export the same for the 'dax' bus.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

The target-node attribute is the Linux numa-node that a device-dax
instance may create when it is online. Prior to being online the
device's 'numa_node' property reflects the closest online cpu node which
is the typical expectation of a device 'numa_node'. Once it is online it
becomes its own distinct numa node, i.e. 'target_node'.

Export the 'target_node' property to give userspace tooling the ability
to predict the effective numa-node from a device-dax instance configured
to provide 'System RAM' capacity.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

The typical 'new_id' attribute behavior is to immediately attach a
device to its driver after a new device-id is added. Implement this
behavior for the dax bus.

Reported-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reported-by: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Persistent memory, as described by the ACPI NFIT (NVDIMM Firmware
Interface Table), is the first known instance of a memory range
described by a unique "target" proximity domain. Where "initiator" and
"target" proximity domains is an approach that the ACPI HMAT
(Heterogeneous Memory Attributes Table) uses to described the unique
performance properties of a memory range relative to a given initiator
(e.g. CPU or DMA device).

Currently the numa-node for a /dev/pmemX block-device or /dev/daxX.Y
char-device follows the traditional notion of 'numa-node' where the
attribute conveys the closest online numa-node. That numa-node attribute
is useful for cpu-binding and memory-binding processes *near* the
device. However, when the memory range backing a 'pmem', or 'dax' device
is onlined (memory hot-add) the memory-only-numa-node representing that
address needs to be differentiated from the set of online nodes. In
other words, the numa-node association of the device depends on whether
you can bind processes *near* the cpu-numa-node in the offline
device-case, or bind process *on* the memory-range directly after the
backing address range is onlined.

Allow for the case that platform firmware describes persistent memory
with a unique proximity domain, i.e. when it is distinct from the
proximity of DRAM and CPUs that are on the same socket. Plumb the Linux
numa-node translation of that proximity through the libnvdimm region
device to namespaces that are in device-dax mode. With this in place the
proposed kmem driver [1] can optionally discover a unique numa-node
number for the address range as it transitions the memory from an
offline state managed by a device-driver to an online memory range
managed by the core-mm.

[1]: https://lore.kernel.org/lkml/20181022201317.8558C1D8@viggo.jf.intel.com

Reported-by: Fan Du <fan.du@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

On the expectation that some environments may not upgrade libdaxctl
(userspace component that depends on the /sys/class/dax hierarchy),
provide a default / legacy dax_pmem_compat driver. The dax_pmem_compat
driver implements the original /sys/class/dax sysfs layout rather than
/sys/bus/dax. When userspace is upgraded it can blacklist this module
and switch to the dax_pmem driver going forward.

CONFIG_DEV_DAX_PMEM_COMPAT and supporting code will be deleted according
to the dax_pmem entry in Documentation/ABI/obsolete/.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Introduce the 'new_id' concept for enabling a custom device-driver attach
policy for dax-bus drivers. The intended use is to have a mechanism for
hot-plugging device-dax ranges into the page allocator on-demand. With
this in place the default policy of using device-dax for performance
differentiated memory can be overridden by user-space policy that can
arrange for the memory range to be managed as 'System RAM' with
user-defined NUMA and other performance attributes.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Move the responsibility of calling devm_request_resource() and
devm_memremap_pages() into the common device-dax driver. This is another
preparatory step to allowing an alternate personality driver for a
device-dax range.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>