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* device-dax: fix percpu_ref_exit orderingDan Williams2016-10-271-1/+1
| | | | | | | | | | | | | | | | | | | | | We need to wait until the percpu_ref is released before exit. Otherwise, we sometimes lose the race and trigger this new warning that was added in v4.9 (commit a67823c1ed10 "percpu-refcount: init ->confirm_switch member properly"): WARNING: CPU: 0 PID: 3629 at lib/percpu-refcount.c:107 percpu_ref_exit+0x51/0x60 [..] Call Trace: [<ffffffff814bf093>] dump_stack+0x85/0xc2 [<ffffffff810b15db>] __warn+0xcb/0xf0 [<ffffffff810b170d>] warn_slowpath_null+0x1d/0x20 [<ffffffff814d70c1>] percpu_ref_exit+0x51/0x60 [<ffffffffa005706a>] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem] [<ffffffff81615f1f>] devm_action_release+0xf/0x20 Cc: <stable@vger.kernel.org> Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* nvdimm: make CONFIG_NVDIMM_DAX 'bool'Arnd Bergmann2016-10-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Merge branch 'for-4.9/dax' into libnvdimm-for-nextDan Williams2016-10-074-232/+362
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| * dax: use correct dev_t valueArnd Bergmann2016-10-071-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The dev_t variable in devm_create_dax_dev() is used before it's first set: drivers/dax/dax.c: In function 'devm_create_dax_dev': drivers/dax/dax.c:205:39: error: 'dev_t' may be used uninitialized in this function [-Werror=maybe-uninitialized] inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/dax/dax.c:688:8: note: 'dev_t' was declared here This reorders the code to how it looks correct to me. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 3bc52c45bac2 ("dax: define a unified inode/address_space for device-dax mappings") Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: convert devm_create_dax_dev to PTR_ERRDan Williams2016-10-073-10/+16
| | | | | | | | | | | | | | For sub-division support we need access to the dax_dev created by devm_create_dax_dev(). Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: check resource alignment at dax region/device createDan Williams2016-08-231-3/+19
| | | | | | | | | | | | | | | | All the extents of a dax-device must match the alignment of the region. Otherwise, we are unable to guarantee fault semantics of a given page size. The region must be self-consistent itself as well. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: unmap/truncate on device shutdownDan Williams2016-08-231-0/+1
| | | | | | | | | | | | | | Invalidate all mappings of a device-dax instance when the device is unregistered. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: define a unified inode/address_space for device-dax mappingsDan Williams2016-08-231-4/+146
| | | | | | | | | | | | | | | | In support of enabling resize / truncate of device-dax instances, define a pseudo-fs to provide a unified inode/address space for vm operations. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: convert to the cdev apiDan Williams2016-08-232-41/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * dax: embed a struct device in dax_devDan Williams2016-08-231-85/+45
| | | | | | | | | | | | | | | | | | The kref in dax_dev can be made redundant if the final put_device() on the device associated with the dax_dev frees the dax_dev. This can be accomplished by embedding a struct device in struct dax_dev, open coding device_create() and specifying a custom release method. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: rename fops from dax_dev_ to dax_Dan Williams2016-08-231-8/+8
| | | | | | | | | | | | | | Shorten the prefix of the file operations to distinguish them from operations on the struct device associated with the dax_dev. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: reorder dax_fops function definitionsDan Williams2016-08-231-169/+168
| | | | | | | | | | | | | | | | In order to convert devm_create_dax_dev() to use cdev, it will need access to dax_fops. Move dax_fops and related function definitions before devm_create_dax_dev(). Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * dax: cleanup needlessly global symbol warningsDan Williams2016-08-232-1/+2
| | | | | | | | | | | | | | | | | | drivers/dax/dax.c:75:6: warning: symbol 'dax_region_put' was not declared. drivers/dax/dax.c:95:19: warning: symbol 'alloc_dax_region' was not declared. drivers/dax/dax.c:173:5: warning: symbol 'devm_create_dax_dev' was not declared. drivers/dax/pmem.c:27:17: warning: symbol 'to_dax_pmem' was not declared. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* | dax: fix mapping size checkDan Williams2016-09-031-1/+1
| | | | | | | | | | | | | | | | pgoff_to_phys() validates that both the starting address and the length of the mapping against the resource list. We need to check for a mapping size of PMD_SIZE not PAGE_SIZE in the pmd fault path. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* | dax: fix device-dax region baseDan Williams2016-08-261-0/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The data offset for a dax region needs to account for a reservation in the resource range. Otherwise, device-dax is allowing mappings directly into the memmap or device-info-block area with crash signatures like the following: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: get_zone_device_page+0x11/0x30 Call Trace: follow_devmap_pmd+0x298/0x2c0 follow_page_mask+0x275/0x530 __get_user_pages+0xe3/0x750 __gfn_to_pfn_memslot+0x1b2/0x450 [kvm] tdp_page_fault+0x130/0x280 [kvm] kvm_mmu_page_fault+0x5f/0xf0 [kvm] handle_ept_violation+0x94/0x180 [kvm_intel] vmx_handle_exit+0x1d3/0x1440 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x81d/0x16a0 [kvm] kvm_vcpu_ioctl+0x33c/0x620 [kvm] do_vfs_ioctl+0xa2/0x5d0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x1a/0xa4 Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Link: http://lkml.kernel.org/r/147205536732.1606.8994275381938837346.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Abhilash Kumar Mulumudi <m.abhilash-kumar@hpe.com> Reported-by: Toshi Kani <toshi.kani@hpe.com> Tested-by: Toshi Kani <toshi.kani@hpe.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dax: use devm_add_action_or_reset()Sajjan, Vikas C2016-07-062-12/+8
| | | | | | | | | | | | If devm_add_action() fails, we are explicitly calling the cleanup to free the resources allocated. Use the helper devm_add_action_or_reset() and return directly in case of error, since the cleanup function has been already called by the helper if there was any error. Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Vikas C Sajjan <vikas.cha.sajjan@hpe.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* /dev/dax, core: file operations and dax-mmapDan Williams2016-05-202-0/+323
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* /dev/dax, pmem: direct access to persistent memoryDan Williams2016-05-205-0/+464
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>
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