BMC/Intel-BMC/linux.git/drivers/nvdimm/region_devs.c, branch dev-5.2

libnvdimm/bus: Fix wait_nvdimm_bus_probe_idle() ABBA deadlock

2019-08-09T15:51:41+00:00

commit ca6bf264f6d856f959c4239cda1047b587745c67 upstream. A multithreaded namespace creation/destruction stress test currently deadlocks with the following lockup signature: INFO: task ndctl:2924 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2924 1176 0x00000000 Call Trace: ? __schedule+0x27e/0x780 schedule+0x30/0xb0 wait_nvdimm_bus_probe_idle+0x8a/0xd0 [libnvdimm] ? finish_wait+0x80/0x80 uuid_store+0xe6/0x2e0 [libnvdimm] kernfs_fop_write+0xf0/0x1a0 vfs_write+0xb7/0x1b0 ksys_write+0x5c/0xd0 do_syscall_64+0x60/0x240 INFO: task ndctl:2923 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2923 1175 0x00000000 Call Trace: ? __schedule+0x27e/0x780 ? __mutex_lock+0x489/0x910 schedule+0x30/0xb0 schedule_preempt_disabled+0x11/0x20 __mutex_lock+0x48e/0x910 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] ? __lock_acquire+0x23f/0x1710 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] __dax_pmem_probe+0x5e/0x210 [dax_pmem_core] ? nvdimm_bus_probe+0x1d0/0x2c0 [libnvdimm] dax_pmem_probe+0xc/0x20 [dax_pmem] nvdimm_bus_probe+0x90/0x2c0 [libnvdimm] really_probe+0xef/0x390 driver_probe_device+0xb4/0x100 In this sequence an 'nd_dax' device is being probed and trying to take the lock on its backing namespace to validate that the 'nd_dax' device indeed has exclusive access to the backing namespace. Meanwhile, another thread is trying to update the uuid property of that same backing namespace. So one thread is in the probe path trying to acquire the lock, and the other thread has acquired the lock and tries to flush the probe path. Fix this deadlock by not holding the namespace device_lock over the wait_nvdimm_bus_probe_idle() synchronization step. In turn this requires the device_lock to be held on entry to wait_nvdimm_bus_probe_idle() and subsequently dropped internally to wait_nvdimm_bus_probe_idle(). Cc: Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation") Cc: Vishal Verma Tested-by: Jane Chu Link: https://lore.kernel.org/r/156341210094.292348.2384694131126767789.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Signed-off-by: Sasha Levin

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295

2019-06-05T15:36:38+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of version 2 of the gnu general public license as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 64 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Alexios Zavras Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de Signed-off-by: Greg Kroah-Hartman

Merge tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2019-03-16T20:05:32+00:00

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

libnvdimm/dimm: Add a no-BLK quirk based on NVDIMM family

2019-02-03T00:35:26+00:00

As Dexuan reports the NVDIMM_FAMILY_HYPERV platform is incompatible with the existing Linux namespace implementation because it uses NSLABEL_FLAG_LOCAL for x1-width PMEM interleave sets. Quirk it as an platform / DIMM that does not provide BLK-aperture access. Allow the libnvdimm core to assume no potential for aliasing. In case other implementations make the same mistake, provide a "noblk" module parameter to force-enable the quirk. Link: https://lkml.kernel.org/r/PU1P153MB0169977604493B82B662A01CBF920@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM Reported-by: Dexuan Cui Tested-by: Dexuan Cui Signed-off-by: Dan Williams

acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node

2019-01-07T05:41:57+00:00

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 Cc: Michael Ellerman Cc: "Oliver O'Halloran" Cc: Dave Hansen Cc: Jérôme Glisse Reviewed-by: Yang Shi Signed-off-by: Dan Williams

Merge miscellaneous libnvdimm updates for 4.21

2018-12-28T03:54:10+00:00

* Use common helpers, bitmap_zalloc() and kstrndup(), to replace open coded versions. * Clarify the comments around hotplug vs initial init case for the nfit driver. * Cleanup the libnvdimm init path.

acpi/nfit, libnvdimm/security: Add security DSM overwrite support

2018-12-21T20:44:41+00:00

Add support for the NVDIMM_FAMILY_INTEL "ovewrite" capability as described by the Intel DSM spec v1.7. This will allow triggering of overwrite on Intel NVDIMMs. The overwrite operation can take tens of minutes. When the overwrite DSM is issued successfully, the NVDIMMs will be unaccessible. The kernel will do backoff polling to detect when the overwrite process is completed. According to the DSM spec v1.7, the 128G NVDIMMs can take up to 15mins to perform overwrite and larger DIMMs will take longer. Given that overwrite puts the DIMM in an indeterminate state until it completes introduce the NDD_SECURITY_OVERWRITE flag to prevent other operations from executing when overwrite is happening. The NDD_WORK_PENDING flag is added to denote that there is a device reference on the nvdimm device for an async workqueue thread context. Signed-off-by: Dave Jiang Signed-off-by: Dan Williams

libnvdimm, pfn: Pad pfn namespaces relative to other regions

2018-12-05T22:16:12+00:00

Commit cfe30b872058 "libnvdimm, pmem: adjust for section collisions with 'System RAM'" enabled Linux to workaround occasions where platform firmware arranges for "System RAM" and "Persistent Memory" to collide within a single section boundary. Unfortunately, as reported in this issue [1], platform firmware can inflict the same collision between persistent memory regions. The approach of interrogating iomem_resource does not work in this case because platform firmware may merge multiple regions into a single iomem_resource range. Instead provide a method to interrogate regions that share the same parent bus. This is a stop-gap until the core-MM can grow support for hotplug on sub-section boundaries. [1]: https://github.com/pmem/ndctl/issues/76 Fixes: cfe30b872058 ("libnvdimm, pmem: adjust for section collisions with...") Cc: Reported-by: Patrick Geary Tested-by: Patrick Geary Reviewed-by: Vishal Verma Signed-off-by: Dan Williams

libnvdimm, region: Fail badblocks listing for inactive regions

2018-09-28T18:12:34+00:00

While experimenting with region driver loading the following backtrace was triggered: INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. [..] Call Trace: dump_stack+0x85/0xcb register_lock_class+0x571/0x580 ? __lock_acquire+0x2ba/0x1310 ? kernfs_seq_start+0x2a/0x80 __lock_acquire+0xd4/0x1310 ? dev_attr_show+0x1c/0x50 ? __lock_acquire+0x2ba/0x1310 ? kernfs_seq_start+0x2a/0x80 ? lock_acquire+0x9e/0x1a0 lock_acquire+0x9e/0x1a0 ? dev_attr_show+0x1c/0x50 badblocks_show+0x70/0x190 ? dev_attr_show+0x1c/0x50 dev_attr_show+0x1c/0x50 This results from a missing successful call to devm_init_badblocks() from nd_region_probe(). Block attempts to show badblocks while the region is not enabled. Fixes: 6a6bef90425e ("libnvdimm: add mechanism to publish badblocks...") Cc: Reviewed-by: Johannes Thumshirn Reviewed-by: Dave Jiang Signed-off-by: Dan Williams

libnvdimm: Export max available extent

2018-07-25T21:11:43+00:00

The 'available_size' attribute showing the combined total of all unallocated space isn't always useful to know how large of a namespace a user may be able to allocate if the region is fragmented. This patch will export the largest extent of unallocated space that may be allocated to create a new namespace. Signed-off-by: Keith Busch Reviewed-by: Vishal Verma Signed-off-by: Dave Jiang