linux.git/drivers/dax/bus.c, branch v6.9

Merge tag 'libnvdimm-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2024-03-15T18:58:32+00:00

Pull libnvdimm updates from Dave Jiang:

 - ACPI_NFIT Kconfig documetation fix

 - Make nvdimm_bus_type const

 - Make dax_bus_type const

 - remove SLAB_MEM_SPREAD flag usage in DAX

* tag 'libnvdimm-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: remove SLAB_MEM_SPREAD flag usage
  device-dax: make dax_bus_type const
  nvdimm: make nvdimm_bus_type const
  libnvdimm: Fix ACPI_NFIT in BLK_DEV_PMEM help

dax: add a sysfs knob to control memmap_on_memory behavior

2024-02-22T18:24:40+00:00

Add a sysfs knob for dax devices to control the memmap_on_memory setting
if the dax device were to be hotplugged as system memory.

The default memmap_on_memory setting for dax devices originating via pmem
or hmem is set to 'false' - i.e.  no memmap_on_memory semantics, to
preserve legacy behavior.  For dax devices via CXL, the default is on. 
The sysfs control allows the administrator to override the above defaults
if needed.

Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-5-20d16cb8d23d@intel.com
Signed-off-by: Vishal Verma 
Tested-by: Li Zhijian 
Reviewed-by: Jonathan Cameron 
Reviewed-by: David Hildenbrand 
Reviewed-by: Huang, Ying 
Reviewed-by: Alison Schofield 
Cc: Dan Williams 
Cc: Dave Jiang 
Cc: Dave Hansen 
Cc: Greg Kroah-Hartman 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

dax/bus.c: replace several sprintf() with sysfs_emit()

2024-02-22T18:24:40+00:00

There were several places where drivers/dax/bus.c uses 'sprintf' to print
sysfs data.  Since a sysfs_emit() helper is available specifically for
this purpose, replace all the sprintf() usage for sysfs with sysfs_emit()
in this file.

Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-2-20d16cb8d23d@intel.com
Signed-off-by: Vishal Verma 
Reported-by: Greg Kroah-Hartman 
Reviewed-by: Alison Schofield 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: Dave Jiang 
Cc: David Hildenbrand 
Cc: Huang Ying 
Cc: Jonathan Cameron 
Cc: Li Zhijian 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

dax/bus.c: replace driver-core lock usage by a local rwsem

2024-02-22T18:24:40+00:00

Patch series "Add DAX ABI for memmap_on_memory", v7.

This series adds sysfs ABI to control memmap_on_memory behavior for DAX
devices.

Patch 1 replaces incorrect device_lock() usage with a local rwsem - this
was identified during review.

Patch 2 is also a preparatory patch that replaces sprintf() for sysfs
operations with sysfs_emit()

Patch 3 adds the missing documentation for the sysfs ABI for DAX regions
and Dax devices.

Patch 4 exports mhp_supports_memmap_on_memory().

Patch 5 adds the new ABI for toggling memmap_on_memory semantics for dax
devices.


This patch (of 5):

The dax driver incorrectly used driver-core device locks to protect
internal dax region and dax device configuration structures.  Replace the
device lock usage with a local rwsem, one each for dax region
configuration and dax device configuration.  As a result of this
conversion, no device_lock() usage remains in dax/bus.c.

Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-0-20d16cb8d23d@intel.com
Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-1-20d16cb8d23d@intel.com
Signed-off-by: Vishal Verma 
Reported-by: Greg Kroah-Hartman 
Reviewed-by: Alison Schofield 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: Dave Jiang 
Cc: David Hildenbrand 
Cc: Huang Ying 
Cc: Jonathan Cameron 
Cc: Li Zhijian 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

device-dax: make dax_bus_type const

2024-02-12T22:10:21+00:00

Now that the driver core can properly handle constant struct bus_type,
move the dax_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: Ricardo B. Marliere 
Reviewed-by: Greg Kroah-Hartman 
Link: https://lore.kernel.org/r/20240204-bus_cleanup-dax-v1-1-69a6e4a8553b@marliere.net
Signed-off-by: Dave Jiang

dax/kmem: allow kmem to add memory with memmap_on_memory

2023-12-11T00:51:35+00:00

Large amounts of memory managed by the kmem driver may come in via CXL,
and it is often desirable to have the memmap for this memory on the new
memory itself.

Enroll kmem-managed memory for memmap_on_memory semantics if the dax
region originates via CXL.  For non-CXL dax regions, retain the existing
default behavior of hot adding without memmap_on_memory semantics.

Link: https://lkml.kernel.org/r/20231107-vv-kmem_memmap-v10-3-1253ec050ed0@intel.com
Signed-off-by: Vishal Verma 
Reviewed-by: Jonathan Cameron 
Reviewed-by: David Hildenbrand 
Reviewed-by: "Huang, Ying" 
Tested-by: Li Zhijian 	[cxl.kmem and nvdimm.kmem]
Cc: Michal Hocko 
Cc: Oscar Salvador 
Cc: Dan Williams 
Cc: Dave Jiang 
Cc: Dave Hansen 
Cc: Aneesh Kumar K.V 
Cc: Fan Ni 
Cc: Jeff Moyer 
Signed-off-by: Andrew Morton

dax: refactor deprecated strncpy

2023-09-27T17:33:46+00:00

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

`dax_id->dev_name` is expected to be NUL-terminated and has been zero-allocated.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer. Moreover, due to
`dax_id` being zero-allocated the padding behavior of `strncpy` is not
needed and a simple 1:1 replacement of strncpy -> strscpy should
suffice.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt 
Reviewed-by: Dave Jiang 
Signed-off-by: Ira Weiny

dax: Cleanup extra dax_region references

2023-06-23T07:03:50+00:00

Now that free_dev_dax_id() internally manages the references it needs
the extra references taken by the dax_region drivers are not needed.

Reported-by: Ira Weiny 
Signed-off-by: Dan Williams 
Link: https://lore.kernel.org/r/168577285161.1672036.8111253437794419696.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Dave Jiang 
Reviewed-by: Fan Ni 
Reviewed-by: Ira Weiny 
Signed-off-by: Vishal Verma

dax: Introduce alloc_dev_dax_id()

2023-06-23T07:03:50+00:00

The reference counting of dax_region objects is needlessly complicated,
has lead to confusion [1], and has hidden a bug [2]. Towards cleaning up
that mess introduce alloc_dev_dax_id() to minimize the holding of a
dax_region reference to only what dev_dax_release() needs, the
dax_region->ida.

Part of the reason for the mess was the design to dereference a
dax_region in all cases in free_dev_dax_id() even if the id was
statically assigned by the upper level dax_region driver. Remove the
need to call "is_static(dax_region)" by tracking whether the id is
dynamic directly in the dev_dax instance itself.

With that flag the dax_region pinning and release per dev_dax instance
can move to alloc_dev_dax_id() and free_dev_dax_id() respectively.

A follow-on cleanup address the unnecessary references in the dax_region
setup and drivers.

Fixes: 0f3da14a4f05 ("device-dax: introduce 'seed' devices")
Link: http://lore.kernel.org/r/20221203095858.612027-1-liuyongqiang13@huawei.com [1]
Link: http://lore.kernel.org/r/3cf0890b-4eb0-e70e-cd9c-2ecc3d496263@hpe.com [2]
Reported-by: Yongqiang Liu 
Reported-by: Paul Cassella 
Reported-by: Ira Weiny 
Signed-off-by: Dan Williams 
Link: https://lore.kernel.org/r/168577284563.1672036.13493034988900989554.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Ira Weiny 
Signed-off-by: Vishal Verma

dax: Use device_unregister() in unregister_dax_mapping()

2023-06-23T07:03:50+00:00

Replace an open-coded device_unregister() sequence with the helper.

Signed-off-by: Dan Williams 
Link: https://lore.kernel.org/r/168577283989.1672036.7777592498865470652.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Dave Jiang 
Reviewed-by: Fan Ni 
Reviewed-by: Ira Weiny 
Signed-off-by: Vishal Verma