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![Uwe Kleine-König](/assets/img/avatar_default.png)
The driver core ignores the return value of struct bus_type::remove() because there is only little that can be done. To simplify the quest to make this function return void, let struct dax_device_driver::remove() return void, too. All users already unconditionally return 0, this commit makes it obvious that returning an error code isn't intended. Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org> Link: https://lore.kernel.org/r/20210205222842.34896-6-uwe@kleine-koenig.org Signed-off-by: Dan Williams <dan.j.williams@intel.com>
225 lines
5.7 KiB
C
225 lines
5.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */
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#include <linux/memremap.h>
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#include <linux/pagemap.h>
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#include <linux/memory.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/pfn_t.h>
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#include <linux/slab.h>
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#include <linux/dax.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include "dax-private.h"
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#include "bus.h"
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/* Memory resource name used for add_memory_driver_managed(). */
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static const char *kmem_name;
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/* Set if any memory will remain added when the driver will be unloaded. */
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static bool any_hotremove_failed;
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static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
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{
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struct dev_dax_range *dax_range = &dev_dax->ranges[i];
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struct range *range = &dax_range->range;
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/* memory-block align the hotplug range */
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r->start = ALIGN(range->start, memory_block_size_bytes());
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r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
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if (r->start >= r->end) {
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r->start = range->start;
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r->end = range->end;
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return -ENOSPC;
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}
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return 0;
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}
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struct dax_kmem_data {
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const char *res_name;
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struct resource *res[];
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};
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static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
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{
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struct device *dev = &dev_dax->dev;
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struct dax_kmem_data *data;
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int rc = -ENOMEM;
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int i, mapped = 0;
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int numa_node;
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/*
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* Ensure good NUMA information for the persistent memory.
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* Without this check, there is a risk that slow memory
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* could be mixed in a node with faster memory, causing
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* unavoidable performance issues.
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*/
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numa_node = dev_dax->target_node;
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if (numa_node < 0) {
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dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
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numa_node);
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return -EINVAL;
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}
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data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
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if (!data->res_name)
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goto err_res_name;
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for (i = 0; i < dev_dax->nr_range; i++) {
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struct resource *res;
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struct range range;
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rc = dax_kmem_range(dev_dax, i, &range);
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if (rc) {
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dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
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i, range.start, range.end);
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continue;
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}
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/* Region is permanently reserved if hotremove fails. */
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res = request_mem_region(range.start, range_len(&range), data->res_name);
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if (!res) {
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dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
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i, range.start, range.end);
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/*
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* Once some memory has been onlined we can't
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* assume that it can be un-onlined safely.
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*/
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if (mapped)
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continue;
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rc = -EBUSY;
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goto err_request_mem;
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}
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data->res[i] = res;
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/*
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* Set flags appropriate for System RAM. Leave ..._BUSY clear
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* so that add_memory() can add a child resource. Do not
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* inherit flags from the parent since it may set new flags
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* unknown to us that will break add_memory() below.
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*/
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res->flags = IORESOURCE_SYSTEM_RAM;
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/*
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* Ensure that future kexec'd kernels will not treat
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* this as RAM automatically.
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*/
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rc = add_memory_driver_managed(numa_node, range.start,
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range_len(&range), kmem_name, MHP_NONE);
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if (rc) {
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dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
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i, range.start, range.end);
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release_resource(res);
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kfree(res);
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data->res[i] = NULL;
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if (mapped)
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continue;
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goto err_request_mem;
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}
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mapped++;
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}
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dev_set_drvdata(dev, data);
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return 0;
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err_request_mem:
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kfree(data->res_name);
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err_res_name:
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kfree(data);
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return rc;
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}
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#ifdef CONFIG_MEMORY_HOTREMOVE
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static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
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{
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int i, success = 0;
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struct device *dev = &dev_dax->dev;
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struct dax_kmem_data *data = dev_get_drvdata(dev);
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/*
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* We have one shot for removing memory, if some memory blocks were not
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* offline prior to calling this function remove_memory() will fail, and
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* there is no way to hotremove this memory until reboot because device
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* unbind will succeed even if we return failure.
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*/
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for (i = 0; i < dev_dax->nr_range; i++) {
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struct range range;
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int rc;
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rc = dax_kmem_range(dev_dax, i, &range);
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if (rc)
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continue;
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rc = remove_memory(dev_dax->target_node, range.start,
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range_len(&range));
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if (rc == 0) {
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release_resource(data->res[i]);
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kfree(data->res[i]);
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data->res[i] = NULL;
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success++;
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continue;
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}
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any_hotremove_failed = true;
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dev_err(dev,
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"mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
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i, range.start, range.end);
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}
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if (success >= dev_dax->nr_range) {
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kfree(data->res_name);
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kfree(data);
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dev_set_drvdata(dev, NULL);
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}
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}
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#else
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static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
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{
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/*
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* Without hotremove purposely leak the request_mem_region() for the
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* device-dax range and return '0' to ->remove() attempts. The removal
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* of the device from the driver always succeeds, but the region is
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* permanently pinned as reserved by the unreleased
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* request_mem_region().
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*/
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any_hotremove_failed = true;
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}
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#endif /* CONFIG_MEMORY_HOTREMOVE */
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static struct dax_device_driver device_dax_kmem_driver = {
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.probe = dev_dax_kmem_probe,
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.remove = dev_dax_kmem_remove,
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};
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static int __init dax_kmem_init(void)
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{
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int rc;
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/* Resource name is permanently allocated if any hotremove fails. */
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kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
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if (!kmem_name)
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return -ENOMEM;
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rc = dax_driver_register(&device_dax_kmem_driver);
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if (rc)
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kfree_const(kmem_name);
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return rc;
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}
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static void __exit dax_kmem_exit(void)
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{
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dax_driver_unregister(&device_dax_kmem_driver);
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if (!any_hotremove_failed)
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kfree_const(kmem_name);
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}
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MODULE_AUTHOR("Intel Corporation");
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MODULE_LICENSE("GPL v2");
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module_init(dax_kmem_init);
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module_exit(dax_kmem_exit);
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MODULE_ALIAS_DAX_DEVICE(0);
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