kernel/linux.git/drivers/dax/hmem, branch v6.18.21

mm: remove callers of pfn_t functionality

2025-07-10T05:42:19+00:00

All PFN_* pfn_t flags have been removed. Therefore there is no longer a need for the pfn_t type and all uses can be replaced with normal pfns. Link: https://lkml.kernel.org/r/bbedfa576c9822f8032494efbe43544628698b1f.1750323463.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple Reviewed-by: Christoph Hellwig Reviewed-by: Jason Gunthorpe Acked-by: David Hildenbrand Cc: Balbir Singh Cc: Björn Töpel Cc: Björn Töpel Cc: Chunyan Zhang Cc: Dan Williams Cc: Deepak Gupta Cc: Gerald Schaefer Cc: Inki Dae Cc: John Groves Cc: John Hubbard Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Will Deacon Signed-off-by: Andrew Morton

dax: add missing MODULE_DESCRIPTION() macros

2024-06-17T23:42:16+00:00

make allmodconfig && make W=1 C=1 reports: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/hmem/dax_hmem.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/device_dax.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/kmem.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/dax_pmem.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/dax_cxl.o Add all missing invocations of the MODULE_DESCRIPTION() macro. [iweiny: edit descriptions] Signed-off-by: Jeff Johnson Link: https://patch.msgid.link/r/20240605-md-drivers-dax-v1-1-3d448f3368b4@quicinc.com Signed-off-by: Ira Weiny

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: 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

cxl/dax: Create dax devices for CXL RAM regions

2023-02-11T01:33:45+00:00

While platform firmware takes some responsibility for mapping the RAM capacity of CXL devices present at boot, the OS is responsible for mapping the remainder and hot-added devices. Platform firmware is also responsible for identifying the platform general purpose memory pool, typically DDR attached DRAM, and arranging for the remainder to be 'Soft Reserved'. That reservation allows the CXL subsystem to route the memory to core-mm via memory-hotplug (dax_kmem), or leave it for dedicated access (device-dax). The new 'struct cxl_dax_region' object allows for a CXL memory resource (region) to be published, but also allow for udev and module policy to act on that event. It also prevents cxl_core.ko from having a module loading dependency on any drivers/dax/ modules. Tested-by: Fan Ni Reviewed-by: Dave Jiang Reviewed-by: Jonathan Cameron Link: https://lore.kernel.org/r/167602003896.1924368.10335442077318970468.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams

dax: Assign RAM regions to memory-hotplug by default

2023-02-11T01:33:40+00:00

The default mode for device-dax instances is backwards for RAM-regions as evidenced by the fact that it tends to catch end users by surprise. "Where is my memory?". Recall that platforms are increasingly shipping with performance-differentiated memory pools beyond typical DRAM and NUMA effects. This includes HBM (high-bandwidth-memory) and CXL (dynamic interleave, varied media types, and future fabric attached possibilities). For this reason the EFI_MEMORY_SP (EFI Special Purpose Memory => Linux 'Soft Reserved') attribute is expected to be applied to all memory-pools that are not the general purpose pool. This designation gives an Operating System a chance to defer usage of a memory pool until later in the boot process where its performance properties can be interrogated and administrator policy can be applied. 'Soft Reserved' memory can be anything from too limited and precious to be part of the general purpose pool (HBM), too slow to host hot kernel data structures (some PMEM media), or anything in between. However, in the absence of an explicit policy, the memory should at least be made usable by default. The current device-dax default hides all non-general-purpose memory behind a device interface. The expectation is that the distribution of users that want the memory online by default vs device-dedicated-access by default follows the Pareto principle. A small number of enlightened users may want to do userspace memory management through a device, but general users just want the kernel to make the memory available with an option to get more advanced later. Arrange for all device-dax instances not backed by PMEM to default to attaching to the dax_kmem driver. From there the baseline memory hotplug policy (CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE / memhp_default_state=) gates whether the memory comes online or stays offline. Where, if it stays offline, it can be reliably converted back to device-mode where it can be partitioned, or fronted by a userspace allocator. So, if someone wants device-dax instances for their 'Soft Reserved' memory: 1/ Build a kernel with CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n or boot with memhp_default_state=offline, or roll the dice and hope that the kernel has not pinned a page in that memory before step 2. 2/ Write a udev rule to convert the target dax device(s) from 'system-ram' mode to 'devdax' mode: daxctl reconfigure-device $dax -m devdax -f Cc: Michal Hocko Cc: David Hildenbrand Cc: Dave Hansen Reviewed-by: Gregory Price Tested-by: Fan Ni Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/167602003336.1924368.6809503401422267885.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams

dax/hmem: Move hmem device registration to dax_hmem.ko

2023-02-11T01:33:34+00:00

In preparation for the CXL region driver to take over the responsibility of registering device-dax instances for CXL regions, move the registration of "hmem" devices to dax_hmem.ko. Previously the builtin component of this enabling (drivers/dax/hmem/device.o) would register platform devices for each address range and trigger the dax_hmem.ko module to load and attach device-dax instances to those devices. Now, the ranges are collected from the HMAT and EFI memory map walking, but the device creation is deferred. A new "hmem_platform" device is created which triggers dax_hmem.ko to load and register the platform devices. Tested-by: Fan Ni Reviewed-by: Dave Jiang Reviewed-by: Jonathan Cameron Link: https://lore.kernel.org/r/167602002771.1924368.5653558226424530127.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams

dax/hmem: Convey the dax range via memregion_info()

2023-02-11T01:33:29+00:00

In preparation for hmem platform devices to be unregistered, stop using platform_device_add_resources() to convey the address range. The platform_device_add_resources() API causes an existing "Soft Reserved" iomem resource to be re-parented under an inserted platform device resource. When that platform device is deleted it removes the platform device resource and all children. Instead, it is sufficient to convey just the address range and let request_mem_region() insert resources to indicate the devices active in the range. This allows the "Soft Reserved" resource to be re-enumerated upon the next probe event. Reviewed-by: Jonathan Cameron Tested-by: Fan Ni Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/167602002217.1924368.7036275892522551624.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams

dax/hmem: Drop unnecessary dax_hmem_remove()

2023-02-11T01:33:24+00:00

Empty driver remove callbacks can just be elided. Reviewed-by: Jonathan Cameron Reviewed-by: Gregory Price Tested-by: Fan Ni Reviewed-by: Vishal Verma Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/167602001664.1924368.9102029637928071240.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams

dax/hmem: Move HMAT and Soft reservation probe initcall level

2023-02-11T01:33:18+00:00

In preparation for moving more filtering of "hmem" ranges into the dax_hmem.ko module, update the initcall levels. HMAT range registration moves to subsys_initcall() to be done before Soft Reservation probing, and Soft Reservation probing is moved to device_initcall() to be done before dax_hmem.ko initialization if it is built-in. Tested-by: Fan Ni Reviewed-by: Vishal Verma Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/167602001107.1924368.11562316181038595611.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams