mm/memremap.c - fs/xfs/xfs-linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2015 Intel Corporation. All rights reserved. */
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/kasan.h>
 #include <linux/memory_hotplug.h>
 #include <linux/mm.h>
 #include <linux/pfn_t.h>
 #include <linux/swap.h>
 #include <linux/mmzone.h>
 #include <linux/swapops.h>
 #include <linux/types.h>
 #include <linux/wait_bit.h>
 #include <linux/xarray.h>

 static DEFINE_XARRAY(pgmap_array);

 /*
  * The memremap() and memremap_pages() interfaces are alternately used
  * to map persistent memory namespaces. These interfaces place different
  * constraints on the alignment and size of the mapping (namespace).
  * memremap() can map individual PAGE_SIZE pages. memremap_pages() can
  * only map subsections (2MB), and at least one architecture (PowerPC)
  * the minimum mapping granularity of memremap_pages() is 16MB.
  *
  * The role of memremap_compat_align() is to communicate the minimum
  * arch supported alignment of a namespace such that it can freely
  * switch modes without violating the arch constraint. Namely, do not
  * allow a namespace to be PAGE_SIZE aligned since that namespace may be
  * reconfigured into a mode that requires SUBSECTION_SIZE alignment.
  */
 #ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
 unsigned long memremap_compat_align(void)
 {
 	return SUBSECTION_SIZE;
 }
 EXPORT_SYMBOL_GPL(memremap_compat_align);
 #endif

 #ifdef CONFIG_DEV_PAGEMAP_OPS
 DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
 EXPORT_SYMBOL(devmap_managed_key);

 static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
 {
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
 	    pgmap->type == MEMORY_DEVICE_FS_DAX)
 		static_branch_dec(&devmap_managed_key);
 }

 static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
 	    pgmap->type == MEMORY_DEVICE_FS_DAX)
 		static_branch_inc(&devmap_managed_key);
 }
 #else
 static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 }
 static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
 {
 }
 #endif /* CONFIG_DEV_PAGEMAP_OPS */

 static void pgmap_array_delete(struct range *range)
 {
 	xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
 			NULL, GFP_KERNEL);
 	synchronize_rcu();
 }

 static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
 {
 	struct range *range = &pgmap->ranges[range_id];
 	unsigned long pfn = PHYS_PFN(range->start);

 	if (range_id)
 		return pfn;
 	return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
 }

 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
 {
 	int i;

 	for (i = 0; i < pgmap->nr_range; i++) {
 		struct range *range = &pgmap->ranges[i];

 		if (pfn >= PHYS_PFN(range->start) &&
 		    pfn <= PHYS_PFN(range->end))
 			return pfn >= pfn_first(pgmap, i);
 	}

 	return false;
 }

 static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
 {
 	const struct range *range = &pgmap->ranges[range_id];

 	return (range->start + range_len(range)) >> PAGE_SHIFT;
 }

 static unsigned long pfn_next(unsigned long pfn)
 {
 	if (pfn % 1024 == 0)
 		cond_resched();
 	return pfn + 1;
 }

 #define for_each_device_pfn(pfn, map, i) \
 	for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); pfn = pfn_next(pfn))

 static void dev_pagemap_kill(struct dev_pagemap *pgmap)
 {
 	if (pgmap->ops && pgmap->ops->kill)
 		pgmap->ops->kill(pgmap);
 	else
 		percpu_ref_kill(pgmap->ref);
 }

 static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
 {
 	if (pgmap->ops && pgmap->ops->cleanup) {
 		pgmap->ops->cleanup(pgmap);
 	} else {
 		wait_for_completion(&pgmap->done);
 		percpu_ref_exit(pgmap->ref);
 	}
 	/*
 	 * Undo the pgmap ref assignment for the internal case as the
 	 * caller may re-enable the same pgmap.
 	 */
 	if (pgmap->ref == &pgmap->internal_ref)
 		pgmap->ref = NULL;
 }

 static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
 {
 	struct range *range = &pgmap->ranges[range_id];
 	struct page *first_page;
 	int nid;

 	/* make sure to access a memmap that was actually initialized */
 	first_page = pfn_to_page(pfn_first(pgmap, range_id));

 	/* pages are dead and unused, undo the arch mapping */
 	nid = page_to_nid(first_page);

 	mem_hotplug_begin();
 	remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
 				   PHYS_PFN(range_len(range)));
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
 		__remove_pages(PHYS_PFN(range->start),
 			       PHYS_PFN(range_len(range)), NULL);
 	} else {
 		arch_remove_memory(nid, range->start, range_len(range),
 				pgmap_altmap(pgmap));
 		kasan_remove_zero_shadow(__va(range->start), range_len(range));
 	}
 	mem_hotplug_done();

 	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
 	pgmap_array_delete(range);
 }

 void memunmap_pages(struct dev_pagemap *pgmap)
 {
 	unsigned long pfn;
 	int i;

 	dev_pagemap_kill(pgmap);
 	for (i = 0; i < pgmap->nr_range; i++)
 		for_each_device_pfn(pfn, pgmap, i)
 			put_page(pfn_to_page(pfn));
 	dev_pagemap_cleanup(pgmap);

 	for (i = 0; i < pgmap->nr_range; i++)
 		pageunmap_range(pgmap, i);

 	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
 	devmap_managed_enable_put(pgmap);
 }
 EXPORT_SYMBOL_GPL(memunmap_pages);

 static void devm_memremap_pages_release(void *data)
 {
 	memunmap_pages(data);
 }

 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
 {
 	struct dev_pagemap *pgmap =
 		container_of(ref, struct dev_pagemap, internal_ref);

 	complete(&pgmap->done);
 }

 static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
 		int range_id, int nid)
 {
 	const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
 	struct range *range = &pgmap->ranges[range_id];
 	struct dev_pagemap *conflict_pgmap;
 	int error, is_ram;

 	if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
 				"altmap not supported for multiple ranges\n"))
 		return -EINVAL;

 	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
 	if (conflict_pgmap) {
 		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
 		return -ENOMEM;
 	}

 	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
 	if (conflict_pgmap) {
 		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
 		return -ENOMEM;
 	}

 	is_ram = region_intersects(range->start, range_len(range),
 		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);

 	if (is_ram != REGION_DISJOINT) {
 		WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
 				is_ram == REGION_MIXED ? "mixed" : "ram",
 				range->start, range->end);
 		return -ENXIO;
 	}

 	error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
 				PHYS_PFN(range->end), pgmap, GFP_KERNEL));
 	if (error)
 		return error;

 	if (nid < 0)
 		nid = numa_mem_id();

 	error = track_pfn_remap(NULL, &params->pgprot, PHYS_PFN(range->start), 0,
 			range_len(range));
 	if (error)
 		goto err_pfn_remap;

 	if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
 		error = -EINVAL;
 		goto err_pfn_remap;
 	}

 	mem_hotplug_begin();

 	/*
 	 * For device private memory we call add_pages() as we only need to
 	 * allocate and initialize struct page for the device memory. More-
 	 * over the device memory is un-accessible thus we do not want to
 	 * create a linear mapping for the memory like arch_add_memory()
 	 * would do.
 	 *
 	 * For all other device memory types, which are accessible by
 	 * the CPU, we do want the linear mapping and thus use
 	 * arch_add_memory().
 	 */
 	if (is_private) {
 		error = add_pages(nid, PHYS_PFN(range->start),
 				PHYS_PFN(range_len(range)), params);
 	} else {
 		error = kasan_add_zero_shadow(__va(range->start), range_len(range));
 		if (error) {
 			mem_hotplug_done();
 			goto err_kasan;
 		}

 		error = arch_add_memory(nid, range->start, range_len(range),
 					params);
 	}

 	if (!error) {
 		struct zone *zone;

 		zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
 		move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
 				PHYS_PFN(range_len(range)), params->altmap,
 				MIGRATE_MOVABLE);
 	}

 	mem_hotplug_done();
 	if (error)
 		goto err_add_memory;

 	/*
 	 * Initialization of the pages has been deferred until now in order
 	 * to allow us to do the work while not holding the hotplug lock.
 	 */
 	memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
 				PHYS_PFN(range->start),
 				PHYS_PFN(range_len(range)), pgmap);
 	percpu_ref_get_many(pgmap->ref, pfn_end(pgmap, range_id)
 			- pfn_first(pgmap, range_id));
 	return 0;

 err_add_memory:
 	kasan_remove_zero_shadow(__va(range->start), range_len(range));
 err_kasan:
 	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
 err_pfn_remap:
 	pgmap_array_delete(range);
 	return error;
 }


 /*
  * Not device managed version of dev_memremap_pages, undone by
  * memunmap_pages().  Please use dev_memremap_pages if you have a struct
  * device available.
  */
 void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 {
 	struct mhp_params params = {
 		.altmap = pgmap_altmap(pgmap),
 		.pgprot = PAGE_KERNEL,
 	};
 	const int nr_range = pgmap->nr_range;
 	int error, i;

 	if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
 		return ERR_PTR(-EINVAL);

 	switch (pgmap->type) {
 	case MEMORY_DEVICE_PRIVATE:
 		if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
 			WARN(1, "Device private memory not supported\n");
 			return ERR_PTR(-EINVAL);
 		}
 		if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
 			WARN(1, "Missing migrate_to_ram method\n");
 			return ERR_PTR(-EINVAL);
 		}
 		if (!pgmap->ops->page_free) {
 			WARN(1, "Missing page_free method\n");
 			return ERR_PTR(-EINVAL);
 		}
 		if (!pgmap->owner) {
 			WARN(1, "Missing owner\n");
 			return ERR_PTR(-EINVAL);
 		}
 		break;
 	case MEMORY_DEVICE_FS_DAX:
 		if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
 		    IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
 			WARN(1, "File system DAX not supported\n");
 			return ERR_PTR(-EINVAL);
 		}
 		break;
 	case MEMORY_DEVICE_GENERIC:
 		break;
 	case MEMORY_DEVICE_PCI_P2PDMA:
 		params.pgprot = pgprot_noncached(params.pgprot);
 		break;
 	default:
 		WARN(1, "Invalid pgmap type %d\n", pgmap->type);
 		break;
 	}

 	if (!pgmap->ref) {
 		if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
 			return ERR_PTR(-EINVAL);

 		init_completion(&pgmap->done);
 		error = percpu_ref_init(&pgmap->internal_ref,
 				dev_pagemap_percpu_release, 0, GFP_KERNEL);
 		if (error)
 			return ERR_PTR(error);
 		pgmap->ref = &pgmap->internal_ref;
 	} else {
 		if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
 			WARN(1, "Missing reference count teardown definition\n");
 			return ERR_PTR(-EINVAL);
 		}
 	}

 	devmap_managed_enable_get(pgmap);

 	/*
 	 * Clear the pgmap nr_range as it will be incremented for each
 	 * successfully processed range. This communicates how many
 	 * regions to unwind in the abort case.
 	 */
 	pgmap->nr_range = 0;
 	error = 0;
 	for (i = 0; i < nr_range; i++) {
 		error = pagemap_range(pgmap, &params, i, nid);
 		if (error)
 			break;
 		pgmap->nr_range++;
 	}

 	if (i < nr_range) {
 		memunmap_pages(pgmap);
 		pgmap->nr_range = nr_range;
 		return ERR_PTR(error);
 	}

 	return __va(pgmap->ranges[0].start);
 }
 EXPORT_SYMBOL_GPL(memremap_pages);

 /**
  * devm_memremap_pages - remap and provide memmap backing for the given resource
  * @dev: hosting device for @res
  * @pgmap: pointer to a struct dev_pagemap
  *
  * Notes:
  * 1/ At a minimum the res and type members of @pgmap must be initialized
  *    by the caller before passing it to this function
  *
  * 2/ The altmap field may optionally be initialized, in which case
  *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
  *
  * 3/ The ref field may optionally be provided, in which pgmap->ref must be
  *    'live' on entry and will be killed and reaped at
  *    devm_memremap_pages_release() time, or if this routine fails.
  *
  * 4/ range is expected to be a host memory range that could feasibly be
  *    treated as a "System RAM" range, i.e. not a device mmio range, but
  *    this is not enforced.
  */
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
 	int error;
 	void *ret;

 	ret = memremap_pages(pgmap, dev_to_node(dev));
 	if (IS_ERR(ret))
 		return ret;

 	error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
 			pgmap);
 	if (error)
 		return ERR_PTR(error);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(devm_memremap_pages);

 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
 	devm_release_action(dev, devm_memremap_pages_release, pgmap);
 }
 EXPORT_SYMBOL_GPL(devm_memunmap_pages);

 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 {
 	/* number of pfns from base where pfn_to_page() is valid */
 	if (altmap)
 		return altmap->reserve + altmap->free;
 	return 0;
 }

 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
 {
 	altmap->alloc -= nr_pfns;
 }

 /**
  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
  * @pfn: page frame number to lookup page_map
  * @pgmap: optional known pgmap that already has a reference
  *
  * If @pgmap is non-NULL and covers @pfn it will be returned as-is.  If @pgmap
  * is non-NULL but does not cover @pfn the reference to it will be released.
  */
 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 		struct dev_pagemap *pgmap)
 {
 	resource_size_t phys = PFN_PHYS(pfn);

 	/*
 	 * In the cached case we're already holding a live reference.
 	 */
 	if (pgmap) {
 		if (phys >= pgmap->range.start && phys <= pgmap->range.end)
 			return pgmap;
 		put_dev_pagemap(pgmap);
 	}

 	/* fall back to slow path lookup */
 	rcu_read_lock();
 	pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
 	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
 		pgmap = NULL;
 	rcu_read_unlock();

 	return pgmap;
 }
 EXPORT_SYMBOL_GPL(get_dev_pagemap);

 #ifdef CONFIG_DEV_PAGEMAP_OPS
 void free_devmap_managed_page(struct page *page)
 {
 	/* notify page idle for dax */
 	if (!is_device_private_page(page)) {
 		wake_up_var(&page->_refcount);
 		return;
 	}

 	__ClearPageWaiters(page);

 	mem_cgroup_uncharge(page);

 	/*
 	 * When a device_private page is freed, the page->mapping field
 	 * may still contain a (stale) mapping value. For example, the
 	 * lower bits of page->mapping may still identify the page as an
 	 * anonymous page. Ultimately, this entire field is just stale
 	 * and wrong, and it will cause errors if not cleared.  One
 	 * example is:
 	 *
 	 *  migrate_vma_pages()
 	 *    migrate_vma_insert_page()
 	 *      page_add_new_anon_rmap()
 	 *        __page_set_anon_rmap()
 	 *          ...checks page->mapping, via PageAnon(page) call,
 	 *            and incorrectly concludes that the page is an
 	 *            anonymous page. Therefore, it incorrectly,
 	 *            silently fails to set up the new anon rmap.
 	 *
 	 * For other types of ZONE_DEVICE pages, migration is either
 	 * handled differently or not done at all, so there is no need
 	 * to clear page->mapping.
 	 */
 	page->mapping = NULL;
 	page->pgmap->ops->page_free(page);
 }
 #endif /* CONFIG_DEV_PAGEMAP_OPS */
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright(c) 2015 Intel Corporation. All rights reserved. */
	#include <linux/device.h>
	#include <linux/io.h>
	#include <linux/kasan.h>
	#include <linux/memory_hotplug.h>
	#include <linux/mm.h>
	#include <linux/pfn_t.h>
	#include <linux/swap.h>
	#include <linux/mmzone.h>
	#include <linux/swapops.h>
	#include <linux/types.h>
	#include <linux/wait_bit.h>
	#include <linux/xarray.h>

	static DEFINE_XARRAY(pgmap_array);

	/*
	* The memremap() and memremap_pages() interfaces are alternately used
	* to map persistent memory namespaces. These interfaces place different
	* constraints on the alignment and size of the mapping (namespace).
	* memremap() can map individual PAGE_SIZE pages. memremap_pages() can
	* only map subsections (2MB), and at least one architecture (PowerPC)
	* the minimum mapping granularity of memremap_pages() is 16MB.
	*
	* The role of memremap_compat_align() is to communicate the minimum
	* arch supported alignment of a namespace such that it can freely
	* switch modes without violating the arch constraint. Namely, do not
	* allow a namespace to be PAGE_SIZE aligned since that namespace may be
	* reconfigured into a mode that requires SUBSECTION_SIZE alignment.
	*/
	#ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
	unsigned long memremap_compat_align(void)
	{
	return SUBSECTION_SIZE;
	}
	EXPORT_SYMBOL_GPL(memremap_compat_align);
	#endif

	#ifdef CONFIG_DEV_PAGEMAP_OPS
	DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
	EXPORT_SYMBOL(devmap_managed_key);

	static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
	{
	if (pgmap->type == MEMORY_DEVICE_PRIVATE \|\|
	pgmap->type == MEMORY_DEVICE_FS_DAX)
	static_branch_dec(&devmap_managed_key);
	}

	static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
	{
	if (pgmap->type == MEMORY_DEVICE_PRIVATE \|\|
	pgmap->type == MEMORY_DEVICE_FS_DAX)
	static_branch_inc(&devmap_managed_key);
	}
	#else
	static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
	{
	}
	static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
	{
	}
	#endif /* CONFIG_DEV_PAGEMAP_OPS */

	static void pgmap_array_delete(struct range *range)
	{
	xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
	NULL, GFP_KERNEL);
	synchronize_rcu();
	}

	static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
	{
	struct range *range = &pgmap->ranges[range_id];
	unsigned long pfn = PHYS_PFN(range->start);

	if (range_id)
	return pfn;
	return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
	}

	bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
	{
	int i;

	for (i = 0; i < pgmap->nr_range; i++) {
	struct range *range = &pgmap->ranges[i];

	if (pfn >= PHYS_PFN(range->start) &&
	pfn <= PHYS_PFN(range->end))
	return pfn >= pfn_first(pgmap, i);
	}

	return false;
	}

	static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
	{
	const struct range *range = &pgmap->ranges[range_id];

	return (range->start + range_len(range)) >> PAGE_SHIFT;
	}

	static unsigned long pfn_next(unsigned long pfn)
	{
	if (pfn % 1024 == 0)
	cond_resched();
	return pfn + 1;
	}

	#define for_each_device_pfn(pfn, map, i) \
	for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); pfn = pfn_next(pfn))

	static void dev_pagemap_kill(struct dev_pagemap *pgmap)
	{
	if (pgmap->ops && pgmap->ops->kill)
	pgmap->ops->kill(pgmap);
	else
	percpu_ref_kill(pgmap->ref);
	}

	static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
	{
	if (pgmap->ops && pgmap->ops->cleanup) {
	pgmap->ops->cleanup(pgmap);
	} else {
	wait_for_completion(&pgmap->done);
	percpu_ref_exit(pgmap->ref);
	}
	/*
	* Undo the pgmap ref assignment for the internal case as the
	* caller may re-enable the same pgmap.
	*/
	if (pgmap->ref == &pgmap->internal_ref)
	pgmap->ref = NULL;
	}

	static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
	{
	struct range *range = &pgmap->ranges[range_id];
	struct page *first_page;
	int nid;

	/* make sure to access a memmap that was actually initialized */
	first_page = pfn_to_page(pfn_first(pgmap, range_id));

	/* pages are dead and unused, undo the arch mapping */
	nid = page_to_nid(first_page);

	mem_hotplug_begin();
	remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
	PHYS_PFN(range_len(range)));
	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
	__remove_pages(PHYS_PFN(range->start),
	PHYS_PFN(range_len(range)), NULL);
	} else {
	arch_remove_memory(nid, range->start, range_len(range),
	pgmap_altmap(pgmap));
	kasan_remove_zero_shadow(__va(range->start), range_len(range));
	}
	mem_hotplug_done();

	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
	pgmap_array_delete(range);
	}

	void memunmap_pages(struct dev_pagemap *pgmap)
	{
	unsigned long pfn;
	int i;

	dev_pagemap_kill(pgmap);
	for (i = 0; i < pgmap->nr_range; i++)
	for_each_device_pfn(pfn, pgmap, i)
	put_page(pfn_to_page(pfn));
	dev_pagemap_cleanup(pgmap);

	for (i = 0; i < pgmap->nr_range; i++)
	pageunmap_range(pgmap, i);

	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
	devmap_managed_enable_put(pgmap);
	}
	EXPORT_SYMBOL_GPL(memunmap_pages);

	static void devm_memremap_pages_release(void *data)
	{
	memunmap_pages(data);
	}

	static void dev_pagemap_percpu_release(struct percpu_ref *ref)
	{
	struct dev_pagemap *pgmap =
	container_of(ref, struct dev_pagemap, internal_ref);

	complete(&pgmap->done);
	}

	static int pagemap_range(struct dev_pagemap pgmap, struct mhp_params params,
	int range_id, int nid)
	{
	const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
	struct range *range = &pgmap->ranges[range_id];
	struct dev_pagemap *conflict_pgmap;
	int error, is_ram;

	if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
	"altmap not supported for multiple ranges\n"))
	return -EINVAL;

	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
	if (conflict_pgmap) {
	WARN(1, "Conflicting mapping in same section\n");
	put_dev_pagemap(conflict_pgmap);
	return -ENOMEM;
	}

	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
	if (conflict_pgmap) {
	WARN(1, "Conflicting mapping in same section\n");
	put_dev_pagemap(conflict_pgmap);
	return -ENOMEM;
	}

	is_ram = region_intersects(range->start, range_len(range),
	IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);

	if (is_ram != REGION_DISJOINT) {
	WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
	is_ram == REGION_MIXED ? "mixed" : "ram",
	range->start, range->end);
	return -ENXIO;
	}

	error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
	PHYS_PFN(range->end), pgmap, GFP_KERNEL));
	if (error)
	return error;

	if (nid < 0)
	nid = numa_mem_id();

	error = track_pfn_remap(NULL, &params->pgprot, PHYS_PFN(range->start), 0,
	range_len(range));
	if (error)
	goto err_pfn_remap;

	if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
	error = -EINVAL;
	goto err_pfn_remap;
	}

	mem_hotplug_begin();

	/*
	* For device private memory we call add_pages() as we only need to
	* allocate and initialize struct page for the device memory. More-
	* over the device memory is un-accessible thus we do not want to
	* create a linear mapping for the memory like arch_add_memory()
	* would do.
	*
	* For all other device memory types, which are accessible by
	* the CPU, we do want the linear mapping and thus use
	* arch_add_memory().
	*/
	if (is_private) {
	error = add_pages(nid, PHYS_PFN(range->start),
	PHYS_PFN(range_len(range)), params);
	} else {
	error = kasan_add_zero_shadow(__va(range->start), range_len(range));
	if (error) {
	mem_hotplug_done();
	goto err_kasan;
	}

	error = arch_add_memory(nid, range->start, range_len(range),
	params);
	}

	if (!error) {
	struct zone *zone;

	zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
	move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
	PHYS_PFN(range_len(range)), params->altmap,
	MIGRATE_MOVABLE);
	}

	mem_hotplug_done();
	if (error)
	goto err_add_memory;

	/*
	* Initialization of the pages has been deferred until now in order
	* to allow us to do the work while not holding the hotplug lock.
	*/
	memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
	PHYS_PFN(range->start),
	PHYS_PFN(range_len(range)), pgmap);
	percpu_ref_get_many(pgmap->ref, pfn_end(pgmap, range_id)
	- pfn_first(pgmap, range_id));
	return 0;

	err_add_memory:
	kasan_remove_zero_shadow(__va(range->start), range_len(range));
	err_kasan:
	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
	err_pfn_remap:
	pgmap_array_delete(range);
	return error;
	}


	/*
	* Not device managed version of dev_memremap_pages, undone by
	* memunmap_pages(). Please use dev_memremap_pages if you have a struct
	* device available.
	*/
	void memremap_pages(struct dev_pagemap pgmap, int nid)
	{
	struct mhp_params params = {
	.altmap = pgmap_altmap(pgmap),
	.pgprot = PAGE_KERNEL,
	};
	const int nr_range = pgmap->nr_range;
	int error, i;

	if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
	return ERR_PTR(-EINVAL);

	switch (pgmap->type) {
	case MEMORY_DEVICE_PRIVATE:
	if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
	WARN(1, "Device private memory not supported\n");
	return ERR_PTR(-EINVAL);
	}
	if (!pgmap->ops \|\| !pgmap->ops->migrate_to_ram) {
	WARN(1, "Missing migrate_to_ram method\n");
	return ERR_PTR(-EINVAL);
	}
	if (!pgmap->ops->page_free) {
	WARN(1, "Missing page_free method\n");
	return ERR_PTR(-EINVAL);
	}
	if (!pgmap->owner) {
	WARN(1, "Missing owner\n");
	return ERR_PTR(-EINVAL);
	}
	break;
	case MEMORY_DEVICE_FS_DAX:
	if (!IS_ENABLED(CONFIG_ZONE_DEVICE) \|\|
	IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
	WARN(1, "File system DAX not supported\n");
	return ERR_PTR(-EINVAL);
	}
	break;
	case MEMORY_DEVICE_GENERIC:
	break;
	case MEMORY_DEVICE_PCI_P2PDMA:
	params.pgprot = pgprot_noncached(params.pgprot);
	break;
	default:
	WARN(1, "Invalid pgmap type %d\n", pgmap->type);
	break;
	}

	if (!pgmap->ref) {
	if (pgmap->ops && (pgmap->ops->kill \|\| pgmap->ops->cleanup))
	return ERR_PTR(-EINVAL);

	init_completion(&pgmap->done);
	error = percpu_ref_init(&pgmap->internal_ref,
	dev_pagemap_percpu_release, 0, GFP_KERNEL);
	if (error)
	return ERR_PTR(error);
	pgmap->ref = &pgmap->internal_ref;
	} else {
	if (!pgmap->ops \|\| !pgmap->ops->kill \|\| !pgmap->ops->cleanup) {
	WARN(1, "Missing reference count teardown definition\n");
	return ERR_PTR(-EINVAL);
	}
	}

	devmap_managed_enable_get(pgmap);

	/*
	* Clear the pgmap nr_range as it will be incremented for each
	* successfully processed range. This communicates how many
	* regions to unwind in the abort case.
	*/
	pgmap->nr_range = 0;
	error = 0;
	for (i = 0; i < nr_range; i++) {
	error = pagemap_range(pgmap, &params, i, nid);
	if (error)
	break;
	pgmap->nr_range++;
	}

	if (i < nr_range) {
	memunmap_pages(pgmap);
	pgmap->nr_range = nr_range;
	return ERR_PTR(error);
	}

	return __va(pgmap->ranges[0].start);
	}
	EXPORT_SYMBOL_GPL(memremap_pages);

	/**
	* devm_memremap_pages - remap and provide memmap backing for the given resource
	* @dev: hosting device for @res
	* @pgmap: pointer to a struct dev_pagemap
	*
	* Notes:
	* 1/ At a minimum the res and type members of @pgmap must be initialized
	* by the caller before passing it to this function
	*
	* 2/ The altmap field may optionally be initialized, in which case
	* PGMAP_ALTMAP_VALID must be set in pgmap->flags.
	*
	* 3/ The ref field may optionally be provided, in which pgmap->ref must be
	* 'live' on entry and will be killed and reaped at
	* devm_memremap_pages_release() time, or if this routine fails.
	*
	* 4/ range is expected to be a host memory range that could feasibly be
	* treated as a "System RAM" range, i.e. not a device mmio range, but
	* this is not enforced.
	*/
	void devm_memremap_pages(struct device dev, struct dev_pagemap *pgmap)
	{
	int error;
	void *ret;

	ret = memremap_pages(pgmap, dev_to_node(dev));
	if (IS_ERR(ret))
	return ret;

	error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
	pgmap);
	if (error)
	return ERR_PTR(error);
	return ret;
	}
	EXPORT_SYMBOL_GPL(devm_memremap_pages);

	void devm_memunmap_pages(struct device dev, struct dev_pagemap pgmap)
	{
	devm_release_action(dev, devm_memremap_pages_release, pgmap);
	}
	EXPORT_SYMBOL_GPL(devm_memunmap_pages);

	unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
	{
	/* number of pfns from base where pfn_to_page() is valid */
	if (altmap)
	return altmap->reserve + altmap->free;
	return 0;
	}

	void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
	{
	altmap->alloc -= nr_pfns;
	}

	/**
	* get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
	* @pfn: page frame number to lookup page_map
	* @pgmap: optional known pgmap that already has a reference
	*
	* If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
	* is non-NULL but does not cover @pfn the reference to it will be released.
	*/
	struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
	struct dev_pagemap *pgmap)
	{
	resource_size_t phys = PFN_PHYS(pfn);

	/*
	* In the cached case we're already holding a live reference.
	*/
	if (pgmap) {
	if (phys >= pgmap->range.start && phys <= pgmap->range.end)
	return pgmap;
	put_dev_pagemap(pgmap);
	}

	/* fall back to slow path lookup */
	rcu_read_lock();
	pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
	pgmap = NULL;
	rcu_read_unlock();

	return pgmap;
	}
	EXPORT_SYMBOL_GPL(get_dev_pagemap);

	#ifdef CONFIG_DEV_PAGEMAP_OPS
	void free_devmap_managed_page(struct page *page)
	{
	/* notify page idle for dax */
	if (!is_device_private_page(page)) {
	wake_up_var(&page->_refcount);
	return;
	}

	__ClearPageWaiters(page);

	mem_cgroup_uncharge(page);

	/*
	* When a device_private page is freed, the page->mapping field
	* may still contain a (stale) mapping value. For example, the
	* lower bits of page->mapping may still identify the page as an
	* anonymous page. Ultimately, this entire field is just stale
	* and wrong, and it will cause errors if not cleared. One
	* example is:
	*
	* migrate_vma_pages()
	* migrate_vma_insert_page()
	* page_add_new_anon_rmap()
	* __page_set_anon_rmap()
	* ...checks page->mapping, via PageAnon(page) call,
	* and incorrectly concludes that the page is an
	* anonymous page. Therefore, it incorrectly,
	* silently fails to set up the new anon rmap.
	*
	* For other types of ZONE_DEVICE pages, migration is either
	* handled differently or not done at all, so there is no need
	* to clear page->mapping.
	*/
	page->mapping = NULL;
	page->pgmap->ops->page_free(page);
	}
	#endif /* CONFIG_DEV_PAGEMAP_OPS */