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path: root/drivers/dax/Kconfig
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2019-11-07device-dax: Add a driver for "hmem" devicesDan Williams
Platform firmware like EFI/ACPI may publish "hmem" platform devices. Such a device is a performance differentiated memory range likely reserved for an application specific use case. The driver gives access to 100% of the capacity via a device-dax mmap instance by default. However, if over-subscription and other kernel memory management is desired the resulting dax device can be assigned to the core-mm via the kmem driver. This consumes "hmem" devices the producer of "hmem" devices is saved for a follow-on patch so that it can reference the new CONFIG_DEV_DAX_HMEM symbol to gate performing the enumeration work. Reported-by: kbuild test robot <lkp@intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-07drivers/dax: Allow to include DEV_DAX_PMEM as builtinAneesh Kumar K.V
This move the dependency to DEV_DAX_PMEM_COMPAT such that only if DEV_DAX_PMEM is built as module we can allow the compat support. This allows to test the new code easily in a emulation setup where we often build things without module support. Cc: <stable@vger.kernel.org> Fixes: 730926c3b099 ("device-dax: Add /sys/class/dax backwards compatibility") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-28device-dax: "Hotplug" persistent memory for use like normal RAMDave Hansen
This is intended for use with NVDIMMs that are physically persistent (physically like flash) so that they can be used as a cost-effective RAM replacement. Intel Optane DC persistent memory is one implementation of this kind of NVDIMM. Currently, a persistent memory region is "owned" by a device driver, either the "Direct DAX" or "Filesystem DAX" drivers. These drivers allow applications to explicitly use persistent memory, generally by being modified to use special, new libraries. (DIMM-based persistent memory hardware/software is described in great detail here: Documentation/nvdimm/nvdimm.txt). However, this limits persistent memory use to applications which *have* been modified. To make it more broadly usable, this driver "hotplugs" memory into the kernel, to be managed and used just like normal RAM would be. To make this work, management software must remove the device from being controlled by the "Device DAX" infrastructure: echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind and then tell the new driver that it can bind to the device: echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id After this, there will be a number of new memory sections visible in sysfs that can be onlined, or that may get onlined by existing udev-initiated memory hotplug rules. This rebinding procedure is currently a one-way trip. Once memory is bound to "kmem", it's there permanently and can not be unbound and assigned back to device_dax. The kmem driver will never bind to a dax device unless the device is *explicitly* bound to the driver. There are two reasons for this: One, since it is a one-way trip, it can not be undone if bound incorrectly. Two, the kmem driver destroys data on the device. Think of if you had good data on a pmem device. It would be catastrophic if you compile-in "kmem", but leave out the "device_dax" driver. kmem would take over the device and write volatile data all over your good data. This inherits any existing NUMA information for the newly-added memory from the persistent memory device that came from the firmware. On Intel platforms, the firmware has guarantees that require each socket's persistent memory to be in a separate memory-only NUMA node. That means that this patch is not expected to create NUMA nodes, but will simply hotplug memory into existing nodes. Because NUMA nodes are created, the existing NUMA APIs and tools are sufficient to create policies for applications or memory areas to have affinity for or an aversion to using this memory. There is currently some metadata at the beginning of pmem regions. The section-size memory hotplug restrictions, plus this small reserved area can cause the "loss" of a section or two of capacity. This should be fixable in follow-on patches. But, as a first step, losing 256MB of memory (worst case) out of hundreds of gigabytes is a good tradeoff vs. the required code to fix this up precisely. This calculation is also the reason we export memory_block_size_bytes(). Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: Huang Ying <ying.huang@intel.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Takashi Iwai <tiwai@suse.de> Cc: Jerome Glisse <jglisse@redhat.com> Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-01-06device-dax: Add /sys/class/dax backwards compatibilityDan Williams
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>
2018-04-03dax: introduce CONFIG_DAX_DRIVERDan Williams
In support of allowing device-mapper to compile out idle/dead code when there are no dax providers in the system, introduce the DAX_DRIVER symbol. This is selected by all leaf drivers that device-mapper might be layered on top. This allows device-mapper to conditionally 'select DAX' only when a provider is present. Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-09device-dax: kill NR_DEV_DAXDan Williams
There is no point to ask how many device-dax instances the kernel should support. Since we are already using a dynamic major number, just allow the max number of minors by default and be done. This also fixes the fact that the proposed max for the NR_DEV_DAX range was larger than what could be supported by alloc_chrdev_region(). Fixes: ba09c01d2fa8 ("dax: convert to the cdev api") Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-08device-dax: Tell kbuild DEV_DAX_PMEM depends on DEV_DAXMike Galbraith
ERROR: "devm_create_dev_dax" [drivers/dax/dax_pmem.ko] undefined! ERROR: "alloc_dax_region" [drivers/dax/dax_pmem.ko] undefined! ERROR: "dax_region_put" [drivers/dax/dax_pmem.ko] undefined! Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-12dax: refactor dax-fs into a generic provider of 'struct dax_device' instancesDan Williams
We want dax capable drivers to be able to publish a set of dax operations [1]. However, we do not want to further abuse block_devices to advertise these operations. Instead we will attach these operations to a dax device and add a lookup mechanism to go from block device path to a dax device. A dax capable driver like pmem or brd is responsible for registering a dax device, alongside a block device, and then a dax capable filesystem is responsible for retrieving the dax device by path name if it wants to call dax_operations. For now, we refactor the dax pseudo-fs to be a generic facility, rather than an implementation detail, of the device-dax use case. Where a "dax device" is just an inode + dax infrastructure, and "Device DAX" is a mapping service layered on top of that base 'struct dax_device'. "Filesystem DAX" is then a mapping service that layers a filesystem on top of that same base device. Filesystem DAX is associated with a block_device for now, but perhaps directly to a dax device in the future, or for new pmem-only filesystems. [1]: https://lkml.org/lkml/2017/1/19/880 Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-12device-dax: switch to srcu, fix rcu_read_lock() vs pte allocationDan Williams
The following warning triggers with a new unit test that stresses the device-dax interface. =============================== [ ERR: suspicious RCU usage. ] 4.11.0-rc4+ #1049 Tainted: G O ------------------------------- ./include/linux/rcupdate.h:521 Illegal context switch in RCU read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 0 2 locks held by fio/9070: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8d0739d7>] __do_page_fault+0x167/0x4f0 #1: (rcu_read_lock){......}, at: [<ffffffffc03fbd02>] dax_dev_huge_fault+0x32/0x620 [dax] Call Trace: dump_stack+0x86/0xc3 lockdep_rcu_suspicious+0xd7/0x110 ___might_sleep+0xac/0x250 __might_sleep+0x4a/0x80 __alloc_pages_nodemask+0x23a/0x360 alloc_pages_current+0xa1/0x1f0 pte_alloc_one+0x17/0x80 __pte_alloc+0x1e/0x120 __get_locked_pte+0x1bf/0x1d0 insert_pfn.isra.70+0x3a/0x100 ? lookup_memtype+0xa6/0xd0 vm_insert_mixed+0x64/0x90 dax_dev_huge_fault+0x520/0x620 [dax] ? dax_dev_huge_fault+0x32/0x620 [dax] dax_dev_fault+0x10/0x20 [dax] __do_fault+0x1e/0x140 __handle_mm_fault+0x9af/0x10d0 handle_mm_fault+0x16d/0x370 ? handle_mm_fault+0x47/0x370 __do_page_fault+0x28c/0x4f0 trace_do_page_fault+0x58/0x2a0 do_async_page_fault+0x1a/0xa0 async_page_fault+0x28/0x30 Inserting a page table entry may trigger an allocation while we are holding a read lock to keep the device instance alive for the duration of the fault. Use srcu for this keep-alive protection. Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Cc: <stable@vger.kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-10-27nvdimm: make CONFIG_NVDIMM_DAX 'bool'Arnd Bergmann
A bugfix just tried to address a randconfig build problem and introduced a variant of the same problem: with CONFIG_LIBNVDIMM=y and CONFIG_NVDIMM_DAX=m, the nvdimm module now fails to link: drivers/nvdimm/built-in.o: In function `to_nd_device_type': bus.c:(.text+0x1b5d): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nd_region_notify_driver_action.constprop.2': region_devs.c:(.text+0x6b6c): undefined reference to `is_nd_dax' region_devs.c:(.text+0x6b8c): undefined reference to `to_nd_dax' drivers/nvdimm/built-in.o: In function `nd_region_probe': region.c:(.text+0x70f3): undefined reference to `nd_dax_create' drivers/nvdimm/built-in.o: In function `mode_show': namespace_devs.c:(.text+0xa196): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nvdimm_namespace_common_probe': (.text+0xa55f): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nvdimm_namespace_common_probe': (.text+0xa56e): undefined reference to `to_nd_dax' This reverts the earlier fix, making NVDIMM_DAX a 'bool' option again as it should be (it gets linked into the libnvdimm module). To fix the original problem, I'm adding a dependency on LIBNVDIMM to DEV_DAX_PMEM, which ensures we can't have that one built-in if the rest is a module. Fixes: 4e65e9381c7a ("/dev/dax: fix Kconfig dependency build breakage") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-08-23dax: convert to the cdev apiDan Williams
A goal of the device-DAX interface is to be able to support many exclusive allocations (partitions) of performance / feature differentiated memory. This count may exceed the default minors limit of 256. As a result of switching to an embedded cdev the inode-to-dax_dev conversion is simplified, as well as reference counting which can switch to the cdev kobject lifetime. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-05-20/dev/dax, core: file operations and dax-mmapDan Williams
The "Device DAX" core enables dax mappings of performance / feature differentiated memory. An open mapping or file handle keeps the backing struct device live, but new mappings are only possible while the device is enabled. Faults are handled under rcu_read_lock to synchronize with the enabled state of the device. Similar to the filesystem-dax case the backing memory may optionally have struct page entries. However, unlike fs-dax there is no support for private mappings, or mappings that are not backed by media (see use of zero-page in fs-dax). Mappings are always guaranteed to match the alignment of the dax_region. If the dax_region is configured to have a 2MB alignment, all mappings are guaranteed to be backed by a pmd entry. Contrast this determinism with the fs-dax case where pmd mappings are opportunistic. If userspace attempts to force a misaligned mapping, the driver will fail the mmap attempt. See dax_dev_check_vma() for other scenarios that are rejected, like MAP_PRIVATE mappings. Cc: Hannes Reinecke <hare@suse.de> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-05-20/dev/dax, pmem: direct access to persistent memoryDan Williams
Device DAX is the device-centric analogue of Filesystem DAX (CONFIG_FS_DAX). It allows memory ranges to be allocated and mapped without need of an intervening file system. Device DAX is strict, precise and predictable. Specifically this interface: 1/ Guarantees fault granularity with respect to a given page size (pte, pmd, or pud) set at configuration time. 2/ Enforces deterministic behavior by being strict about what fault scenarios are supported. For example, by forcing MADV_DONTFORK semantics and omitting MAP_PRIVATE support device-dax guarantees that a mapping always behaves/performs the same once established. It is the "what you see is what you get" access mechanism to differentiated memory vs filesystem DAX which has filesystem specific implementation semantics. Persistent memory is the first target, but the mechanism is also targeted for exclusive allocations of performance differentiated memory ranges. This commit is limited to the base device driver infrastructure to associate a dax device with pmem range. Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>