mm/memblock.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Procedures for maintaining information about logical memory blocks.
  *
  * Peter Bergner, IBM Corp.	June 2001.
  * Copyright (C) 2001 Peter Bergner.
  */

 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/bitops.h>
 #include <linux/poison.h>
 #include <linux/pfn.h>
 #include <linux/debugfs.h>
 #include <linux/kmemleak.h>
 #include <linux/seq_file.h>
 #include <linux/memblock.h>

 #include <asm/sections.h>
 #include <linux/io.h>

 #include "internal.h"

 #define INIT_MEMBLOCK_REGIONS			128
 #define INIT_PHYSMEM_REGIONS			4

 #ifndef INIT_MEMBLOCK_RESERVED_REGIONS
 # define INIT_MEMBLOCK_RESERVED_REGIONS		INIT_MEMBLOCK_REGIONS
 #endif

 /**
  * DOC: memblock overview
  *
  * Memblock is a method of managing memory regions during the early
  * boot period when the usual kernel memory allocators are not up and
  * running.
  *
  * Memblock views the system memory as collections of contiguous
  * regions. There are several types of these collections:
  *
  * * ``memory`` - describes the physical memory available to the
  *   kernel; this may differ from the actual physical memory installed
  *   in the system, for instance when the memory is restricted with
  *   ``mem=`` command line parameter
  * * ``reserved`` - describes the regions that were allocated
  * * ``physmem`` - describes the actual physical memory available during
  *   boot regardless of the possible restrictions and memory hot(un)plug;
  *   the ``physmem`` type is only available on some architectures.
  *
  * Each region is represented by struct memblock_region that
  * defines the region extents, its attributes and NUMA node id on NUMA
  * systems. Every memory type is described by the struct memblock_type
  * which contains an array of memory regions along with
  * the allocator metadata. The "memory" and "reserved" types are nicely
  * wrapped with struct memblock. This structure is statically
  * initialized at build time. The region arrays are initially sized to
  * %INIT_MEMBLOCK_REGIONS for "memory" and %INIT_MEMBLOCK_RESERVED_REGIONS
  * for "reserved". The region array for "physmem" is initially sized to
  * %INIT_PHYSMEM_REGIONS.
  * The memblock_allow_resize() enables automatic resizing of the region
  * arrays during addition of new regions. This feature should be used
  * with care so that memory allocated for the region array will not
  * overlap with areas that should be reserved, for example initrd.
  *
  * The early architecture setup should tell memblock what the physical
  * memory layout is by using memblock_add() or memblock_add_node()
  * functions. The first function does not assign the region to a NUMA
  * node and it is appropriate for UMA systems. Yet, it is possible to
  * use it on NUMA systems as well and assign the region to a NUMA node
  * later in the setup process using memblock_set_node(). The
  * memblock_add_node() performs such an assignment directly.
  *
  * Once memblock is setup the memory can be allocated using one of the
  * API variants:
  *
  * * memblock_phys_alloc*() - these functions return the **physical**
  *   address of the allocated memory
  * * memblock_alloc*() - these functions return the **virtual** address
  *   of the allocated memory.
  *
  * Note, that both API variants use implicit assumptions about allowed
  * memory ranges and the fallback methods. Consult the documentation
  * of memblock_alloc_internal() and memblock_alloc_range_nid()
  * functions for more elaborate description.
  *
  * As the system boot progresses, the architecture specific mem_init()
  * function frees all the memory to the buddy page allocator.
  *
  * Unless an architecture enables %CONFIG_ARCH_KEEP_MEMBLOCK, the
  * memblock data structures (except "physmem") will be discarded after the
  * system initialization completes.
  */

 #ifndef CONFIG_NUMA
 struct pglist_data __refdata contig_page_data;
 EXPORT_SYMBOL(contig_page_data);
 #endif

 unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
 unsigned long long max_possible_pfn;

 static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_RESERVED_REGIONS] __initdata_memblock;
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
 static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS];
 #endif

 struct memblock memblock __initdata_memblock = {
 	.memory.regions		= memblock_memory_init_regions,
 	.memory.cnt		= 1,	/* empty dummy entry */
 	.memory.max		= INIT_MEMBLOCK_REGIONS,
 	.memory.name		= "memory",

 	.reserved.regions	= memblock_reserved_init_regions,
 	.reserved.cnt		= 1,	/* empty dummy entry */
 	.reserved.max		= INIT_MEMBLOCK_RESERVED_REGIONS,
 	.reserved.name		= "reserved",

 	.bottom_up		= false,
 	.current_limit		= MEMBLOCK_ALLOC_ANYWHERE,
 };

 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
 struct memblock_type physmem = {
 	.regions		= memblock_physmem_init_regions,
 	.cnt			= 1,	/* empty dummy entry */
 	.max			= INIT_PHYSMEM_REGIONS,
 	.name			= "physmem",
 };
 #endif

 /*
  * keep a pointer to &memblock.memory in the text section to use it in
  * __next_mem_range() and its helpers.
  *  For architectures that do not keep memblock data after init, this
  * pointer will be reset to NULL at memblock_discard()
  */
 static __refdata struct memblock_type *memblock_memory = &memblock.memory;

 #define for_each_memblock_type(i, memblock_type, rgn)			\
 	for (i = 0, rgn = &memblock_type->regions[0];			\
 	     i < memblock_type->cnt;					\
 	     i++, rgn = &memblock_type->regions[i])

 #define memblock_dbg(fmt, ...)						\
 	do {								\
 		if (memblock_debug)					\
 			pr_info(fmt, ##__VA_ARGS__);			\
 	} while (0)

 static int memblock_debug __initdata_memblock;
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
 static int memblock_reserved_in_slab __initdata_memblock = 0;

 static enum memblock_flags __init_memblock choose_memblock_flags(void)
 {
 	return system_has_some_mirror ? MEMBLOCK_MIRROR : MEMBLOCK_NONE;
 }

 /* adjust *@size so that (@base + *@size) doesn't overflow, return new size */
 static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
 {
 	return *size = min(*size, PHYS_ADDR_MAX - base);
 }

 /*
  * Address comparison utilities
  */
 static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1,
 				       phys_addr_t base2, phys_addr_t size2)
 {
 	return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
 }

 bool __init_memblock memblock_overlaps_region(struct memblock_type *type,
 					phys_addr_t base, phys_addr_t size)
 {
 	unsigned long i;

 	memblock_cap_size(base, &size);

 	for (i = 0; i < type->cnt; i++)
 		if (memblock_addrs_overlap(base, size, type->regions[i].base,
 					   type->regions[i].size))
 			break;
 	return i < type->cnt;
 }

 /**
  * __memblock_find_range_bottom_up - find free area utility in bottom-up
  * @start: start of candidate range
  * @end: end of candidate range, can be %MEMBLOCK_ALLOC_ANYWHERE or
  *       %MEMBLOCK_ALLOC_ACCESSIBLE
  * @size: size of free area to find
  * @align: alignment of free area to find
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @flags: pick from blocks based on memory attributes
  *
  * Utility called from memblock_find_in_range_node(), find free area bottom-up.
  *
  * Return:
  * Found address on success, 0 on failure.
  */
 static phys_addr_t __init_memblock
 __memblock_find_range_bottom_up(phys_addr_t start, phys_addr_t end,
 				phys_addr_t size, phys_addr_t align, int nid,
 				enum memblock_flags flags)
 {
 	phys_addr_t this_start, this_end, cand;
 	u64 i;

 	for_each_free_mem_range(i, nid, flags, &this_start, &this_end, NULL) {
 		this_start = clamp(this_start, start, end);
 		this_end = clamp(this_end, start, end);

 		cand = round_up(this_start, align);
 		if (cand < this_end && this_end - cand >= size)
 			return cand;
 	}

 	return 0;
 }

 /**
  * __memblock_find_range_top_down - find free area utility, in top-down
  * @start: start of candidate range
  * @end: end of candidate range, can be %MEMBLOCK_ALLOC_ANYWHERE or
  *       %MEMBLOCK_ALLOC_ACCESSIBLE
  * @size: size of free area to find
  * @align: alignment of free area to find
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @flags: pick from blocks based on memory attributes
  *
  * Utility called from memblock_find_in_range_node(), find free area top-down.
  *
  * Return:
  * Found address on success, 0 on failure.
  */
 static phys_addr_t __init_memblock
 __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
 			       phys_addr_t size, phys_addr_t align, int nid,
 			       enum memblock_flags flags)
 {
 	phys_addr_t this_start, this_end, cand;
 	u64 i;

 	for_each_free_mem_range_reverse(i, nid, flags, &this_start, &this_end,
 					NULL) {
 		this_start = clamp(this_start, start, end);
 		this_end = clamp(this_end, start, end);

 		if (this_end < size)
 			continue;

 		cand = round_down(this_end - size, align);
 		if (cand >= this_start)
 			return cand;
 	}

 	return 0;
 }

 /**
  * memblock_find_in_range_node - find free area in given range and node
  * @size: size of free area to find
  * @align: alignment of free area to find
  * @start: start of candidate range
  * @end: end of candidate range, can be %MEMBLOCK_ALLOC_ANYWHERE or
  *       %MEMBLOCK_ALLOC_ACCESSIBLE
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @flags: pick from blocks based on memory attributes
  *
  * Find @size free area aligned to @align in the specified range and node.
  *
  * Return:
  * Found address on success, 0 on failure.
  */
 static phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
 					phys_addr_t end, int nid,
 					enum memblock_flags flags)
 {
 	/* pump up @end */
 	if (end == MEMBLOCK_ALLOC_ACCESSIBLE ||
 	    end == MEMBLOCK_ALLOC_KASAN)
 		end = memblock.current_limit;

 	/* avoid allocating the first page */
 	start = max_t(phys_addr_t, start, PAGE_SIZE);
 	end = max(start, end);

 	if (memblock_bottom_up())
 		return __memblock_find_range_bottom_up(start, end, size, align,
 						       nid, flags);
 	else
 		return __memblock_find_range_top_down(start, end, size, align,
 						      nid, flags);
 }

 /**
  * memblock_find_in_range - find free area in given range
  * @start: start of candidate range
  * @end: end of candidate range, can be %MEMBLOCK_ALLOC_ANYWHERE or
  *       %MEMBLOCK_ALLOC_ACCESSIBLE
  * @size: size of free area to find
  * @align: alignment of free area to find
  *
  * Find @size free area aligned to @align in the specified range.
  *
  * Return:
  * Found address on success, 0 on failure.
  */
 phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
 					phys_addr_t end, phys_addr_t size,
 					phys_addr_t align)
 {
 	phys_addr_t ret;
 	enum memblock_flags flags = choose_memblock_flags();

 again:
 	ret = memblock_find_in_range_node(size, align, start, end,
 					    NUMA_NO_NODE, flags);

 	if (!ret && (flags & MEMBLOCK_MIRROR)) {
 		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
 			&size);
 		flags &= ~MEMBLOCK_MIRROR;
 		goto again;
 	}

 	return ret;
 }

 static void __init_memblock memblock_remove_region(struct memblock_type *type, unsigned long r)
 {
 	type->total_size -= type->regions[r].size;
 	memmove(&type->regions[r], &type->regions[r + 1],
 		(type->cnt - (r + 1)) * sizeof(type->regions[r]));
 	type->cnt--;

 	/* Special case for empty arrays */
 	if (type->cnt == 0) {
 		WARN_ON(type->total_size != 0);
 		type->cnt = 1;
 		type->regions[0].base = 0;
 		type->regions[0].size = 0;
 		type->regions[0].flags = 0;
 		memblock_set_region_node(&type->regions[0], MAX_NUMNODES);
 	}
 }

 #ifndef CONFIG_ARCH_KEEP_MEMBLOCK
 /**
  * memblock_discard - discard memory and reserved arrays if they were allocated
  */
 void __init memblock_discard(void)
 {
 	phys_addr_t addr, size;

 	if (memblock.reserved.regions != memblock_reserved_init_regions) {
 		addr = __pa(memblock.reserved.regions);
 		size = PAGE_ALIGN(sizeof(struct memblock_region) *
 				  memblock.reserved.max);
 		__memblock_free_late(addr, size);
 	}

 	if (memblock.memory.regions != memblock_memory_init_regions) {
 		addr = __pa(memblock.memory.regions);
 		size = PAGE_ALIGN(sizeof(struct memblock_region) *
 				  memblock.memory.max);
 		__memblock_free_late(addr, size);
 	}

 	memblock_memory = NULL;
 }
 #endif

 /**
  * memblock_double_array - double the size of the memblock regions array
  * @type: memblock type of the regions array being doubled
  * @new_area_start: starting address of memory range to avoid overlap with
  * @new_area_size: size of memory range to avoid overlap with
  *
  * Double the size of the @type regions array. If memblock is being used to
  * allocate memory for a new reserved regions array and there is a previously
  * allocated memory range [@new_area_start, @new_area_start + @new_area_size]
  * waiting to be reserved, ensure the memory used by the new array does
  * not overlap.
  *
  * Return:
  * 0 on success, -1 on failure.
  */
 static int __init_memblock memblock_double_array(struct memblock_type *type,
 						phys_addr_t new_area_start,
 						phys_addr_t new_area_size)
 {
 	struct memblock_region *new_array, *old_array;
 	phys_addr_t old_alloc_size, new_alloc_size;
 	phys_addr_t old_size, new_size, addr, new_end;
 	int use_slab = slab_is_available();
 	int *in_slab;

 	/* We don't allow resizing until we know about the reserved regions
 	 * of memory that aren't suitable for allocation
 	 */
 	if (!memblock_can_resize)
 		return -1;

 	/* Calculate new doubled size */
 	old_size = type->max * sizeof(struct memblock_region);
 	new_size = old_size << 1;
 	/*
 	 * We need to allocated new one align to PAGE_SIZE,
 	 *   so we can free them completely later.
 	 */
 	old_alloc_size = PAGE_ALIGN(old_size);
 	new_alloc_size = PAGE_ALIGN(new_size);

 	/* Retrieve the slab flag */
 	if (type == &memblock.memory)
 		in_slab = &memblock_memory_in_slab;
 	else
 		in_slab = &memblock_reserved_in_slab;

 	/* Try to find some space for it */
 	if (use_slab) {
 		new_array = kmalloc(new_size, GFP_KERNEL);
 		addr = new_array ? __pa(new_array) : 0;
 	} else {
 		/* only exclude range when trying to double reserved.regions */
 		if (type != &memblock.reserved)
 			new_area_start = new_area_size = 0;

 		addr = memblock_find_in_range(new_area_start + new_area_size,
 						memblock.current_limit,
 						new_alloc_size, PAGE_SIZE);
 		if (!addr && new_area_size)
 			addr = memblock_find_in_range(0,
 				min(new_area_start, memblock.current_limit),
 				new_alloc_size, PAGE_SIZE);

 		new_array = addr ? __va(addr) : NULL;
 	}
 	if (!addr) {
 		pr_err("memblock: Failed to double %s array from %ld to %ld entries !\n",
 		       type->name, type->max, type->max * 2);
 		return -1;
 	}

 	new_end = addr + new_size - 1;
 	memblock_dbg("memblock: %s is doubled to %ld at [%pa-%pa]",
 			type->name, type->max * 2, &addr, &new_end);

 	/*
 	 * Found space, we now need to move the array over before we add the
 	 * reserved region since it may be our reserved array itself that is
 	 * full.
 	 */
 	memcpy(new_array, type->regions, old_size);
 	memset(new_array + type->max, 0, old_size);
 	old_array = type->regions;
 	type->regions = new_array;
 	type->max <<= 1;

 	/* Free old array. We needn't free it if the array is the static one */
 	if (*in_slab)
 		kfree(old_array);
 	else if (old_array != memblock_memory_init_regions &&
 		 old_array != memblock_reserved_init_regions)
 		memblock_free(__pa(old_array), old_alloc_size);

 	/*
 	 * Reserve the new array if that comes from the memblock.  Otherwise, we
 	 * needn't do it
 	 */
 	if (!use_slab)
 		BUG_ON(memblock_reserve(addr, new_alloc_size));

 	/* Update slab flag */
 	*in_slab = use_slab;

 	return 0;
 }

 /**
  * memblock_merge_regions - merge neighboring compatible regions
  * @type: memblock type to scan
  *
  * Scan @type and merge neighboring compatible regions.
  */
 static void __init_memblock memblock_merge_regions(struct memblock_type *type)
 {
 	int i = 0;

 	/* cnt never goes below 1 */
 	while (i < type->cnt - 1) {
 		struct memblock_region *this = &type->regions[i];
 		struct memblock_region *next = &type->regions[i + 1];

 		if (this->base + this->size != next->base ||
 		    memblock_get_region_node(this) !=
 		    memblock_get_region_node(next) ||
 		    this->flags != next->flags) {
 			BUG_ON(this->base + this->size > next->base);
 			i++;
 			continue;
 		}

 		this->size += next->size;
 		/* move forward from next + 1, index of which is i + 2 */
 		memmove(next, next + 1, (type->cnt - (i + 2)) * sizeof(*next));
 		type->cnt--;
 	}
 }

 /**
  * memblock_insert_region - insert new memblock region
  * @type:	memblock type to insert into
  * @idx:	index for the insertion point
  * @base:	base address of the new region
  * @size:	size of the new region
  * @nid:	node id of the new region
  * @flags:	flags of the new region
  *
  * Insert new memblock region [@base, @base + @size) into @type at @idx.
  * @type must already have extra room to accommodate the new region.
  */
 static void __init_memblock memblock_insert_region(struct memblock_type *type,
 						   int idx, phys_addr_t base,
 						   phys_addr_t size,
 						   int nid,
 						   enum memblock_flags flags)
 {
 	struct memblock_region *rgn = &type->regions[idx];

 	BUG_ON(type->cnt >= type->max);
 	memmove(rgn + 1, rgn, (type->cnt - idx) * sizeof(*rgn));
 	rgn->base = base;
 	rgn->size = size;
 	rgn->flags = flags;
 	memblock_set_region_node(rgn, nid);
 	type->cnt++;
 	type->total_size += size;
 }

 /**
  * memblock_add_range - add new memblock region
  * @type: memblock type to add new region into
  * @base: base address of the new region
  * @size: size of the new region
  * @nid: nid of the new region
  * @flags: flags of the new region
  *
  * Add new memblock region [@base, @base + @size) into @type.  The new region
  * is allowed to overlap with existing ones - overlaps don't affect already
  * existing regions.  @type is guaranteed to be minimal (all neighbouring
  * compatible regions are merged) after the addition.
  *
  * Return:
  * 0 on success, -errno on failure.
  */
 static int __init_memblock memblock_add_range(struct memblock_type *type,
 				phys_addr_t base, phys_addr_t size,
 				int nid, enum memblock_flags flags)
 {
 	bool insert = false;
 	phys_addr_t obase = base;
 	phys_addr_t end = base + memblock_cap_size(base, &size);
 	int idx, nr_new;
 	struct memblock_region *rgn;

 	if (!size)
 		return 0;

 	/* special case for empty array */
 	if (type->regions[0].size == 0) {
 		WARN_ON(type->cnt != 1 || type->total_size);
 		type->regions[0].base = base;
 		type->regions[0].size = size;
 		type->regions[0].flags = flags;
 		memblock_set_region_node(&type->regions[0], nid);
 		type->total_size = size;
 		return 0;
 	}
 repeat:
 	/*
 	 * The following is executed twice.  Once with %false @insert and
 	 * then with %true.  The first counts the number of regions needed
 	 * to accommodate the new area.  The second actually inserts them.
 	 */
 	base = obase;
 	nr_new = 0;

 	for_each_memblock_type(idx, type, rgn) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;

 		if (rbase >= end)
 			break;
 		if (rend <= base)
 			continue;
 		/*
 		 * @rgn overlaps.  If it separates the lower part of new
 		 * area, insert that portion.
 		 */
 		if (rbase > base) {
 #ifdef CONFIG_NUMA
 			WARN_ON(nid != memblock_get_region_node(rgn));
 #endif
 			WARN_ON(flags != rgn->flags);
 			nr_new++;
 			if (insert)
 				memblock_insert_region(type, idx++, base,
 						       rbase - base, nid,
 						       flags);
 		}
 		/* area below @rend is dealt with, forget about it */
 		base = min(rend, end);
 	}

 	/* insert the remaining portion */
 	if (base < end) {
 		nr_new++;
 		if (insert)
 			memblock_insert_region(type, idx, base, end - base,
 					       nid, flags);
 	}

 	if (!nr_new)
 		return 0;

 	/*
 	 * If this was the first round, resize array and repeat for actual
 	 * insertions; otherwise, merge and return.
 	 */
 	if (!insert) {
 		while (type->cnt + nr_new > type->max)
 			if (memblock_double_array(type, obase, size) < 0)
 				return -ENOMEM;
 		insert = true;
 		goto repeat;
 	} else {
 		memblock_merge_regions(type);
 		return 0;
 	}
 }

 /**
  * memblock_add_node - add new memblock region within a NUMA node
  * @base: base address of the new region
  * @size: size of the new region
  * @nid: nid of the new region
  *
  * Add new memblock region [@base, @base + @size) to the "memory"
  * type. See memblock_add_range() description for mode details
  *
  * Return:
  * 0 on success, -errno on failure.
  */
 int __init_memblock memblock_add_node(phys_addr_t base, phys_addr_t size,
 				       int nid)
 {
 	return memblock_add_range(&memblock.memory, base, size, nid, 0);
 }

 /**
  * memblock_add - add new memblock region
  * @base: base address of the new region
  * @size: size of the new region
  *
  * Add new memblock region [@base, @base + @size) to the "memory"
  * type. See memblock_add_range() description for mode details
  *
  * Return:
  * 0 on success, -errno on failure.
  */
 int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;

 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);

 	return memblock_add_range(&memblock.memory, base, size, MAX_NUMNODES, 0);
 }

 /**
  * memblock_isolate_range - isolate given range into disjoint memblocks
  * @type: memblock type to isolate range for
  * @base: base of range to isolate
  * @size: size of range to isolate
  * @start_rgn: out parameter for the start of isolated region
  * @end_rgn: out parameter for the end of isolated region
  *
  * Walk @type and ensure that regions don't cross the boundaries defined by
  * [@base, @base + @size).  Crossing regions are split at the boundaries,
  * which may create at most two more regions.  The index of the first
  * region inside the range is returned in *@start_rgn and end in *@end_rgn.
  *
  * Return:
  * 0 on success, -errno on failure.
  */
 static int __init_memblock memblock_isolate_range(struct memblock_type *type,
 					phys_addr_t base, phys_addr_t size,
 					int *start_rgn, int *end_rgn)
 {
 	phys_addr_t end = base + memblock_cap_size(base, &size);
 	int idx;
 	struct memblock_region *rgn;

 	*start_rgn = *end_rgn = 0;

 	if (!size)
 		return 0;

 	/* we'll create at most two more regions */
 	while (type->cnt + 2 > type->max)
 		if (memblock_double_array(type, base, size) < 0)
 			return -ENOMEM;

 	for_each_memblock_type(idx, type, rgn) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;

 		if (rbase >= end)
 			break;
 		if (rend <= base)
 			continue;

 		if (rbase < base) {
 			/*
 			 * @rgn intersects from below.  Split and continue
 			 * to process the next region - the new top half.
 			 */
 			rgn->base = base;
 			rgn->size -= base - rbase;
 			type->total_size -= base - rbase;
 			memblock_insert_region(type, idx, rbase, base - rbase,
 					       memblock_get_region_node(rgn),
 					       rgn->flags);
 		} else if (rend > end) {
 			/*
 			 * @rgn intersects from above.  Split and redo the
 			 * current region - the new bottom half.
 			 */
 			rgn->base = end;
 			rgn->size -= end - rbase;
 			type->total_size -= end - rbase;
 			memblock_insert_region(type, idx--, rbase, end - rbase,
 					       memblock_get_region_node(rgn),
 					       rgn->flags);
 		} else {
 			/* @rgn is fully contained, record it */
 			if (!*end_rgn)
 				*start_rgn = idx;
 			*end_rgn = idx + 1;
 		}
 	}

 	return 0;
 }

 static int __init_memblock memblock_remove_range(struct memblock_type *type,
 					  phys_addr_t base, phys_addr_t size)
 {
 	int start_rgn, end_rgn;
 	int i, ret;

 	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
 	if (ret)
 		return ret;

 	for (i = end_rgn - 1; i >= start_rgn; i--)
 		memblock_remove_region(type, i);
 	return 0;
 }

 int __init_memblock memblock_remove(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;

 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);

 	return memblock_remove_range(&memblock.memory, base, size);
 }

 /**
  * memblock_free - free boot memory block
  * @base: phys starting address of the  boot memory block
  * @size: size of the boot memory block in bytes
  *
  * Free boot memory block previously allocated by memblock_alloc_xx() API.
  * The freeing memory will not be released to the buddy allocator.
  */
 int __init_memblock memblock_free(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;

 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);

 	kmemleak_free_part_phys(base, size);
 	return memblock_remove_range(&memblock.reserved, base, size);
 }

 int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;

 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);

 	return memblock_add_range(&memblock.reserved, base, size, MAX_NUMNODES, 0);
 }

 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
 int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;

 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);

 	return memblock_add_range(&physmem, base, size, MAX_NUMNODES, 0);
 }
 #endif

 /**
  * memblock_setclr_flag - set or clear flag for a memory region
  * @base: base address of the region
  * @size: size of the region
  * @set: set or clear the flag
  * @flag: the flag to update
  *
  * This function isolates region [@base, @base + @size), and sets/clears flag
  *
  * Return: 0 on success, -errno on failure.
  */
 static int __init_memblock memblock_setclr_flag(phys_addr_t base,
 				phys_addr_t size, int set, int flag)
 {
 	struct memblock_type *type = &memblock.memory;
 	int i, ret, start_rgn, end_rgn;

 	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
 	if (ret)
 		return ret;

 	for (i = start_rgn; i < end_rgn; i++) {
 		struct memblock_region *r = &type->regions[i];

 		if (set)
 			r->flags |= flag;
 		else
 			r->flags &= ~flag;
 	}

 	memblock_merge_regions(type);
 	return 0;
 }

 /**
  * memblock_mark_hotplug - Mark hotpluggable memory with flag MEMBLOCK_HOTPLUG.
  * @base: the base phys addr of the region
  * @size: the size of the region
  *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_mark_hotplug(phys_addr_t base, phys_addr_t size)
 {
 	return memblock_setclr_flag(base, size, 1, MEMBLOCK_HOTPLUG);
 }

 /**
  * memblock_clear_hotplug - Clear flag MEMBLOCK_HOTPLUG for a specified region.
  * @base: the base phys addr of the region
  * @size: the size of the region
  *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
 {
 	return memblock_setclr_flag(base, size, 0, MEMBLOCK_HOTPLUG);
 }

 /**
  * memblock_mark_mirror - Mark mirrored memory with flag MEMBLOCK_MIRROR.
  * @base: the base phys addr of the region
  * @size: the size of the region
  *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
 {
 	system_has_some_mirror = true;

 	return memblock_setclr_flag(base, size, 1, MEMBLOCK_MIRROR);
 }

 /**
  * memblock_mark_nomap - Mark a memory region with flag MEMBLOCK_NOMAP.
  * @base: the base phys addr of the region
  * @size: the size of the region
  *
  * The memory regions marked with %MEMBLOCK_NOMAP will not be added to the
  * direct mapping of the physical memory. These regions will still be
  * covered by the memory map. The struct page representing NOMAP memory
  * frames in the memory map will be PageReserved()
  *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
 {
 	return memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
 }

 /**
  * memblock_clear_nomap - Clear flag MEMBLOCK_NOMAP for a specified region.
  * @base: the base phys addr of the region
  * @size: the size of the region
  *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_clear_nomap(phys_addr_t base, phys_addr_t size)
 {
 	return memblock_setclr_flag(base, size, 0, MEMBLOCK_NOMAP);
 }

 static bool should_skip_region(struct memblock_type *type,
 			       struct memblock_region *m,
 			       int nid, int flags)
 {
 	int m_nid = memblock_get_region_node(m);

 	/* we never skip regions when iterating memblock.reserved or physmem */
 	if (type != memblock_memory)
 		return false;

 	/* only memory regions are associated with nodes, check it */
 	if (nid != NUMA_NO_NODE && nid != m_nid)
 		return true;

 	/* skip hotpluggable memory regions if needed */
 	if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
 		return true;

 	/* if we want mirror memory skip non-mirror memory regions */
 	if ((flags & MEMBLOCK_MIRROR) && !memblock_is_mirror(m))
 		return true;

 	/* skip nomap memory unless we were asked for it explicitly */
 	if (!(flags & MEMBLOCK_NOMAP) && memblock_is_nomap(m))
 		return true;

 	return false;
 }

 /**
  * __next_mem_range - next function for for_each_free_mem_range() etc.
  * @idx: pointer to u64 loop variable
  * @nid: node selector, %NUMA_NO_NODE for all nodes
  * @flags: pick from blocks based on memory attributes
  * @type_a: pointer to memblock_type from where the range is taken
  * @type_b: pointer to memblock_type which excludes memory from being taken
  * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
  * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
  * @out_nid: ptr to int for nid of the range, can be %NULL
  *
  * Find the first area from *@idx which matches @nid, fill the out
  * parameters, and update *@idx for the next iteration.  The lower 32bit of
  * *@idx contains index into type_a and the upper 32bit indexes the
  * areas before each region in type_b.	For example, if type_b regions
  * look like the following,
  *
  *	0:[0-16), 1:[32-48), 2:[128-130)
  *
  * The upper 32bit indexes the following regions.
  *
  *	0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
  *
  * As both region arrays are sorted, the function advances the two indices
  * in lockstep and returns each intersection.
  */
 void __next_mem_range(u64 *idx, int nid, enum memblock_flags flags,
 		      struct memblock_type *type_a,
 		      struct memblock_type *type_b, phys_addr_t *out_start,
 		      phys_addr_t *out_end, int *out_nid)
 {
 	int idx_a = *idx & 0xffffffff;
 	int idx_b = *idx >> 32;

 	if (WARN_ONCE(nid == MAX_NUMNODES,
 	"Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
 		nid = NUMA_NO_NODE;

 	for (; idx_a < type_a->cnt; idx_a++) {
 		struct memblock_region *m = &type_a->regions[idx_a];

 		phys_addr_t m_start = m->base;
 		phys_addr_t m_end = m->base + m->size;
 		int	    m_nid = memblock_get_region_node(m);

 		if (should_skip_region(type_a, m, nid, flags))
 			continue;

 		if (!type_b) {
 			if (out_start)
 				*out_start = m_start;
 			if (out_end)
 				*out_end = m_end;
 			if (out_nid)
 				*out_nid = m_nid;
 			idx_a++;
 			*idx = (u32)idx_a | (u64)idx_b << 32;
 			return;
 		}

 		/* scan areas before each reservation */
 		for (; idx_b < type_b->cnt + 1; idx_b++) {
 			struct memblock_region *r;
 			phys_addr_t r_start;
 			phys_addr_t r_end;

 			r = &type_b->regions[idx_b];
 			r_start = idx_b ? r[-1].base + r[-1].size : 0;
 			r_end = idx_b < type_b->cnt ?
 				r->base : PHYS_ADDR_MAX;

 			/*
 			 * if idx_b advanced past idx_a,
 			 * break out to advance idx_a
 			 */
 			if (r_start >= m_end)
 				break;
 			/* if the two regions intersect, we're done */
 			if (m_start < r_end) {
 				if (out_start)
 					*out_start =
 						max(m_start, r_start);
 				if (out_end)
 					*out_end = min(m_end, r_end);
 				if (out_nid)
 					*out_nid = m_nid;
 				/*
 				 * The region which ends first is
 				 * advanced for the next iteration.
 				 */
 				if (m_end <= r_end)
 					idx_a++;
 				else
 					idx_b++;
 				*idx = (u32)idx_a | (u64)idx_b << 32;
 				return;
 			}
 		}
 	}

 	/* signal end of iteration */
 	*idx = ULLONG_MAX;
 }

 /**
  * __next_mem_range_rev - generic next function for for_each_*_range_rev()
  *
  * @idx: pointer to u64 loop variable
  * @nid: node selector, %NUMA_NO_NODE for all nodes
  * @flags: pick from blocks based on memory attributes
  * @type_a: pointer to memblock_type from where the range is taken
  * @type_b: pointer to memblock_type which excludes memory from being taken
  * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
  * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
  * @out_nid: ptr to int for nid of the range, can be %NULL
  *
  * Finds the next range from type_a which is not marked as unsuitable
  * in type_b.
  *
  * Reverse of __next_mem_range().
  */
 void __init_memblock __next_mem_range_rev(u64 *idx, int nid,
 					  enum memblock_flags flags,
 					  struct memblock_type *type_a,
 					  struct memblock_type *type_b,
 					  phys_addr_t *out_start,
 					  phys_addr_t *out_end, int *out_nid)
 {
 	int idx_a = *idx & 0xffffffff;
 	int idx_b = *idx >> 32;

 	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
 		nid = NUMA_NO_NODE;

 	if (*idx == (u64)ULLONG_MAX) {
 		idx_a = type_a->cnt - 1;
 		if (type_b != NULL)
 			idx_b = type_b->cnt;
 		else
 			idx_b = 0;
 	}

 	for (; idx_a >= 0; idx_a--) {
 		struct memblock_region *m = &type_a->regions[idx_a];

 		phys_addr_t m_start = m->base;
 		phys_addr_t m_end = m->base + m->size;
 		int m_nid = memblock_get_region_node(m);

 		if (should_skip_region(type_a, m, nid, flags))
 			continue;

 		if (!type_b) {
 			if (out_start)
 				*out_start = m_start;
 			if (out_end)
 				*out_end = m_end;
 			if (out_nid)
 				*out_nid = m_nid;
 			idx_a--;
 			*idx = (u32)idx_a | (u64)idx_b << 32;
 			return;
 		}

 		/* scan areas before each reservation */
 		for (; idx_b >= 0; idx_b--) {
 			struct memblock_region *r;
 			phys_addr_t r_start;
 			phys_addr_t r_end;

 			r = &type_b->regions[idx_b];
 			r_start = idx_b ? r[-1].base + r[-1].size : 0;
 			r_end = idx_b < type_b->cnt ?
 				r->base : PHYS_ADDR_MAX;
 			/*
 			 * if idx_b advanced past idx_a,
 			 * break out to advance idx_a
 			 */

 			if (r_end <= m_start)
 				break;
 			/* if the two regions intersect, we're done */
 			if (m_end > r_start) {
 				if (out_start)
 					*out_start = max(m_start, r_start);
 				if (out_end)
 					*out_end = min(m_end, r_end);
 				if (out_nid)
 					*out_nid = m_nid;
 				if (m_start >= r_start)
 					idx_a--;
 				else
 					idx_b--;
 				*idx = (u32)idx_a | (u64)idx_b << 32;
 				return;
 			}
 		}
 	}
 	/* signal end of iteration */
 	*idx = ULLONG_MAX;
 }

 /*
  * Common iterator interface used to define for_each_mem_pfn_range().
  */
 void __init_memblock __next_mem_pfn_range(int *idx, int nid,
 				unsigned long *out_start_pfn,
 				unsigned long *out_end_pfn, int *out_nid)
 {
 	struct memblock_type *type = &memblock.memory;
 	struct memblock_region *r;
 	int r_nid;

 	while (++*idx < type->cnt) {
 		r = &type->regions[*idx];
 		r_nid = memblock_get_region_node(r);

 		if (PFN_UP(r->base) >= PFN_DOWN(r->base + r->size))
 			continue;
 		if (nid == MAX_NUMNODES || nid == r_nid)
 			break;
 	}
 	if (*idx >= type->cnt) {
 		*idx = -1;
 		return;
 	}

 	if (out_start_pfn)
 		*out_start_pfn = PFN_UP(r->base);
 	if (out_end_pfn)
 		*out_end_pfn = PFN_DOWN(r->base + r->size);
 	if (out_nid)
 		*out_nid = r_nid;
 }

 /**
  * memblock_set_node - set node ID on memblock regions
  * @base: base of area to set node ID for
  * @size: size of area to set node ID for
  * @type: memblock type to set node ID for
  * @nid: node ID to set
  *
  * Set the nid of memblock @type regions in [@base, @base + @size) to @nid.
  * Regions which cross the area boundaries are split as necessary.
  *
  * Return:
  * 0 on success, -errno on failure.
  */
 int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
 				      struct memblock_type *type, int nid)
 {
 #ifdef CONFIG_NUMA
 	int start_rgn, end_rgn;
 	int i, ret;

 	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
 	if (ret)
 		return ret;

 	for (i = start_rgn; i < end_rgn; i++)
 		memblock_set_region_node(&type->regions[i], nid);

 	memblock_merge_regions(type);
 #endif
 	return 0;
 }

 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 /**
  * __next_mem_pfn_range_in_zone - iterator for for_each_*_range_in_zone()
  *
  * @idx: pointer to u64 loop variable
  * @zone: zone in which all of the memory blocks reside
  * @out_spfn: ptr to ulong for start pfn of the range, can be %NULL
  * @out_epfn: ptr to ulong for end pfn of the range, can be %NULL
  *
  * This function is meant to be a zone/pfn specific wrapper for the
  * for_each_mem_range type iterators. Specifically they are used in the
  * deferred memory init routines and as such we were duplicating much of
  * this logic throughout the code. So instead of having it in multiple
  * locations it seemed like it would make more sense to centralize this to
  * one new iterator that does everything they need.
  */
 void __init_memblock
 __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
 			     unsigned long *out_spfn, unsigned long *out_epfn)
 {
 	int zone_nid = zone_to_nid(zone);
 	phys_addr_t spa, epa;
 	int nid;

 	__next_mem_range(idx, zone_nid, MEMBLOCK_NONE,
 			 &memblock.memory, &memblock.reserved,
 			 &spa, &epa, &nid);

 	while (*idx != U64_MAX) {
 		unsigned long epfn = PFN_DOWN(epa);
 		unsigned long spfn = PFN_UP(spa);

 		/*
 		 * Verify the end is at least past the start of the zone and
 		 * that we have at least one PFN to initialize.
 		 */
 		if (zone->zone_start_pfn < epfn && spfn < epfn) {
 			/* if we went too far just stop searching */
 			if (zone_end_pfn(zone) <= spfn) {
 				*idx = U64_MAX;
 				break;
 			}

 			if (out_spfn)
 				*out_spfn = max(zone->zone_start_pfn, spfn);
 			if (out_epfn)
 				*out_epfn = min(zone_end_pfn(zone), epfn);

 			return;
 		}

 		__next_mem_range(idx, zone_nid, MEMBLOCK_NONE,
 				 &memblock.memory, &memblock.reserved,
 				 &spa, &epa, &nid);
 	}

 	/* signal end of iteration */
 	if (out_spfn)
 		*out_spfn = ULONG_MAX;
 	if (out_epfn)
 		*out_epfn = 0;
 }

 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

 /**
  * memblock_alloc_range_nid - allocate boot memory block
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @start: the lower bound of the memory region to allocate (phys address)
  * @end: the upper bound of the memory region to allocate (phys address)
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @exact_nid: control the allocation fall back to other nodes
  *
  * The allocation is performed from memory region limited by
  * memblock.current_limit if @end == %MEMBLOCK_ALLOC_ACCESSIBLE.
  *
  * If the specified node can not hold the requested memory and @exact_nid
  * is false, the allocation falls back to any node in the system.
  *
  * For systems with memory mirroring, the allocation is attempted first
  * from the regions with mirroring enabled and then retried from any
  * memory region.
  *
  * In addition, function sets the min_count to 0 using kmemleak_alloc_phys for
  * allocated boot memory block, so that it is never reported as leaks.
  *
  * Return:
  * Physical address of allocated memory block on success, %0 on failure.
  */
 phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
 					phys_addr_t end, int nid,
 					bool exact_nid)
 {
 	enum memblock_flags flags = choose_memblock_flags();
 	phys_addr_t found;

 	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
 		nid = NUMA_NO_NODE;

 	if (!align) {
 		/* Can't use WARNs this early in boot on powerpc */
 		dump_stack();
 		align = SMP_CACHE_BYTES;
 	}

 again:
 	found = memblock_find_in_range_node(size, align, start, end, nid,
 					    flags);
 	if (found && !memblock_reserve(found, size))
 		goto done;

 	if (nid != NUMA_NO_NODE && !exact_nid) {
 		found = memblock_find_in_range_node(size, align, start,
 						    end, NUMA_NO_NODE,
 						    flags);
 		if (found && !memblock_reserve(found, size))
 			goto done;
 	}

 	if (flags & MEMBLOCK_MIRROR) {
 		flags &= ~MEMBLOCK_MIRROR;
 		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
 			&size);
 		goto again;
 	}

 	return 0;

 done:
 	/* Skip kmemleak for kasan_init() due to high volume. */
 	if (end != MEMBLOCK_ALLOC_KASAN)
 		/*
 		 * The min_count is set to 0 so that memblock allocated
 		 * blocks are never reported as leaks. This is because many
 		 * of these blocks are only referred via the physical
 		 * address which is not looked up by kmemleak.
 		 */
 		kmemleak_alloc_phys(found, size, 0, 0);

 	return found;
 }

 /**
  * memblock_phys_alloc_range - allocate a memory block inside specified range
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @start: the lower bound of the memory region to allocate (physical address)
  * @end: the upper bound of the memory region to allocate (physical address)
  *
  * Allocate @size bytes in the between @start and @end.
  *
  * Return: physical address of the allocated memory block on success,
  * %0 on failure.
  */
 phys_addr_t __init memblock_phys_alloc_range(phys_addr_t size,
 					     phys_addr_t align,
 					     phys_addr_t start,
 					     phys_addr_t end)
 {
 	memblock_dbg("%s: %llu bytes align=0x%llx from=%pa max_addr=%pa %pS\n",
 		     __func__, (u64)size, (u64)align, &start, &end,
 		     (void *)_RET_IP_);
 	return memblock_alloc_range_nid(size, align, start, end, NUMA_NO_NODE,
 					false);
 }

 /**
  * memblock_phys_alloc_try_nid - allocate a memory block from specified NUMA node
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  *
  * Allocates memory block from the specified NUMA node. If the node
  * has no available memory, attempts to allocated from any node in the
  * system.
  *
  * Return: physical address of the allocated memory block on success,
  * %0 on failure.
  */
 phys_addr_t __init memblock_phys_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid)
 {
 	return memblock_alloc_range_nid(size, align, 0,
 					MEMBLOCK_ALLOC_ACCESSIBLE, nid, false);
 }

 /**
  * memblock_alloc_internal - allocate boot memory block
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @min_addr: the lower bound of the memory region to allocate (phys address)
  * @max_addr: the upper bound of the memory region to allocate (phys address)
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @exact_nid: control the allocation fall back to other nodes
  *
  * Allocates memory block using memblock_alloc_range_nid() and
  * converts the returned physical address to virtual.
  *
  * The @min_addr limit is dropped if it can not be satisfied and the allocation
  * will fall back to memory below @min_addr. Other constraints, such
  * as node and mirrored memory will be handled again in
  * memblock_alloc_range_nid().
  *
  * Return:
  * Virtual address of allocated memory block on success, NULL on failure.
  */
 static void * __init memblock_alloc_internal(
 				phys_addr_t size, phys_addr_t align,
 				phys_addr_t min_addr, phys_addr_t max_addr,
 				int nid, bool exact_nid)
 {
 	phys_addr_t alloc;

 	/*
 	 * Detect any accidental use of these APIs after slab is ready, as at
 	 * this moment memblock may be deinitialized already and its
 	 * internal data may be destroyed (after execution of memblock_free_all)
 	 */
 	if (WARN_ON_ONCE(slab_is_available()))
 		return kzalloc_node(size, GFP_NOWAIT, nid);

 	if (max_addr > memblock.current_limit)
 		max_addr = memblock.current_limit;

 	alloc = memblock_alloc_range_nid(size, align, min_addr, max_addr, nid,
 					exact_nid);

 	/* retry allocation without lower limit */
 	if (!alloc && min_addr)
 		alloc = memblock_alloc_range_nid(size, align, 0, max_addr, nid,
 						exact_nid);

 	if (!alloc)
 		return NULL;

 	return phys_to_virt(alloc);
 }

 /**
  * memblock_alloc_exact_nid_raw - allocate boot memory block on the exact node
  * without zeroing memory
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @min_addr: the lower bound of the memory region from where the allocation
  *	  is preferred (phys address)
  * @max_addr: the upper bound of the memory region from where the allocation
  *	      is preferred (phys address), or %MEMBLOCK_ALLOC_ACCESSIBLE to
  *	      allocate only from memory limited by memblock.current_limit value
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  *
  * Public function, provides additional debug information (including caller
  * info), if enabled. Does not zero allocated memory.
  *
  * Return:
  * Virtual address of allocated memory block on success, NULL on failure.
  */
 void * __init memblock_alloc_exact_nid_raw(
 			phys_addr_t size, phys_addr_t align,
 			phys_addr_t min_addr, phys_addr_t max_addr,
 			int nid)
 {
 	void *ptr;

 	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
 		     __func__, (u64)size, (u64)align, nid, &min_addr,
 		     &max_addr, (void *)_RET_IP_);

 	ptr = memblock_alloc_internal(size, align,
 					   min_addr, max_addr, nid, true);
 	if (ptr && size > 0)
 		page_init_poison(ptr, size);

 	return ptr;
 }

 /**
  * memblock_alloc_try_nid_raw - allocate boot memory block without zeroing
  * memory and without panicking
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @min_addr: the lower bound of the memory region from where the allocation
  *	  is preferred (phys address)
  * @max_addr: the upper bound of the memory region from where the allocation
  *	      is preferred (phys address), or %MEMBLOCK_ALLOC_ACCESSIBLE to
  *	      allocate only from memory limited by memblock.current_limit value
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  *
  * Public function, provides additional debug information (including caller
  * info), if enabled. Does not zero allocated memory, does not panic if request
  * cannot be satisfied.
  *
  * Return:
  * Virtual address of allocated memory block on success, NULL on failure.
  */
 void * __init memblock_alloc_try_nid_raw(
 			phys_addr_t size, phys_addr_t align,
 			phys_addr_t min_addr, phys_addr_t max_addr,
 			int nid)
 {
 	void *ptr;

 	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
 		     __func__, (u64)size, (u64)align, nid, &min_addr,
 		     &max_addr, (void *)_RET_IP_);

 	ptr = memblock_alloc_internal(size, align,
 					   min_addr, max_addr, nid, false);
 	if (ptr && size > 0)
 		page_init_poison(ptr, size);

 	return ptr;
 }

 /**
  * memblock_alloc_try_nid - allocate boot memory block
  * @size: size of memory block to be allocated in bytes
  * @align: alignment of the region and block's size
  * @min_addr: the lower bound of the memory region from where the allocation
  *	  is preferred (phys address)
  * @max_addr: the upper bound of the memory region from where the allocation
  *	      is preferred (phys address), or %MEMBLOCK_ALLOC_ACCESSIBLE to
  *	      allocate only from memory limited by memblock.current_limit value
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  *
  * Public function, provides additional debug information (including caller
  * info), if enabled. This function zeroes the allocated memory.
  *
  * Return:
  * Virtual address of allocated memory block on success, NULL on failure.
  */
 void * __init memblock_alloc_try_nid(
 			phys_addr_t size, phys_addr_t align,
 			phys_addr_t min_addr, phys_addr_t max_addr,
 			int nid)
 {
 	void *ptr;

 	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
 		     __func__, (u64)size, (u64)align, nid, &min_addr,
 		     &max_addr, (void *)_RET_IP_);
 	ptr = memblock_alloc_internal(size, align,
 					   min_addr, max_addr, nid, false);
 	if (ptr)
 		memset(ptr, 0, size);

 	return ptr;
 }

 /**
  * __memblock_free_late - free pages directly to buddy allocator
  * @base: phys starting address of the  boot memory block
  * @size: size of the boot memory block in bytes
  *
  * This is only useful when the memblock allocator has already been torn
  * down, but we are still initializing the system.  Pages are released directly
  * to the buddy allocator.
  */
 void __init __memblock_free_late(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t cursor, end;

 	end = base + size - 1;
 	memblock_dbg("%s: [%pa-%pa] %pS\n",
 		     __func__, &base, &end, (void *)_RET_IP_);
 	kmemleak_free_part_phys(base, size);
 	cursor = PFN_UP(base);
 	end = PFN_DOWN(base + size);

 	for (; cursor < end; cursor++) {
 		memblock_free_pages(pfn_to_page(cursor), cursor, 0);
 		totalram_pages_inc();
 	}
 }

 /*
  * Remaining API functions
  */

 phys_addr_t __init_memblock memblock_phys_mem_size(void)
 {
 	return memblock.memory.total_size;
 }

 phys_addr_t __init_memblock memblock_reserved_size(void)
 {
 	return memblock.reserved.total_size;
 }

 /* lowest address */
 phys_addr_t __init_memblock memblock_start_of_DRAM(void)
 {
 	return memblock.memory.regions[0].base;
 }

 phys_addr_t __init_memblock memblock_end_of_DRAM(void)
 {
 	int idx = memblock.memory.cnt - 1;

 	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
 }

 static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
 {
 	phys_addr_t max_addr = PHYS_ADDR_MAX;
 	struct memblock_region *r;

 	/*
 	 * translate the memory @limit size into the max address within one of
 	 * the memory memblock regions, if the @limit exceeds the total size
 	 * of those regions, max_addr will keep original value PHYS_ADDR_MAX
 	 */
 	for_each_mem_region(r) {
 		if (limit <= r->size) {
 			max_addr = r->base + limit;
 			break;
 		}
 		limit -= r->size;
 	}

 	return max_addr;
 }

 void __init memblock_enforce_memory_limit(phys_addr_t limit)
 {
 	phys_addr_t max_addr;

 	if (!limit)
 		return;

 	max_addr = __find_max_addr(limit);

 	/* @limit exceeds the total size of the memory, do nothing */
 	if (max_addr == PHYS_ADDR_MAX)
 		return;

 	/* truncate both memory and reserved regions */
 	memblock_remove_range(&memblock.memory, max_addr,
 			      PHYS_ADDR_MAX);
 	memblock_remove_range(&memblock.reserved, max_addr,
 			      PHYS_ADDR_MAX);
 }

 void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
 {
 	int start_rgn, end_rgn;
 	int i, ret;

 	if (!size)
 		return;

 	ret = memblock_isolate_range(&memblock.memory, base, size,
 						&start_rgn, &end_rgn);
 	if (ret)
 		return;

 	/* remove all the MAP regions */
 	for (i = memblock.memory.cnt - 1; i >= end_rgn; i--)
 		if (!memblock_is_nomap(&memblock.memory.regions[i]))
 			memblock_remove_region(&memblock.memory, i);

 	for (i = start_rgn - 1; i >= 0; i--)
 		if (!memblock_is_nomap(&memblock.memory.regions[i]))
 			memblock_remove_region(&memblock.memory, i);

 	/* truncate the reserved regions */
 	memblock_remove_range(&memblock.reserved, 0, base);
 	memblock_remove_range(&memblock.reserved,
 			base + size, PHYS_ADDR_MAX);
 }

 void __init memblock_mem_limit_remove_map(phys_addr_t limit)
 {
 	phys_addr_t max_addr;

 	if (!limit)
 		return;

 	max_addr = __find_max_addr(limit);

 	/* @limit exceeds the total size of the memory, do nothing */
 	if (max_addr == PHYS_ADDR_MAX)
 		return;

 	memblock_cap_memory_range(0, max_addr);
 }

 static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
 {
 	unsigned int left = 0, right = type->cnt;

 	do {
 		unsigned int mid = (right + left) / 2;

 		if (addr < type->regions[mid].base)
 			right = mid;
 		else if (addr >= (type->regions[mid].base +
 				  type->regions[mid].size))
 			left = mid + 1;
 		else
 			return mid;
 	} while (left < right);
 	return -1;
 }

 bool __init_memblock memblock_is_reserved(phys_addr_t addr)
 {
 	return memblock_search(&memblock.reserved, addr) != -1;
 }

 bool __init_memblock memblock_is_memory(phys_addr_t addr)
 {
 	return memblock_search(&memblock.memory, addr) != -1;
 }

 bool __init_memblock memblock_is_map_memory(phys_addr_t addr)
 {
 	int i = memblock_search(&memblock.memory, addr);

 	if (i == -1)
 		return false;
 	return !memblock_is_nomap(&memblock.memory.regions[i]);
 }

 int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
 			 unsigned long *start_pfn, unsigned long *end_pfn)
 {
 	struct memblock_type *type = &memblock.memory;
 	int mid = memblock_search(type, PFN_PHYS(pfn));

 	if (mid == -1)
 		return -1;

 	*start_pfn = PFN_DOWN(type->regions[mid].base);
 	*end_pfn = PFN_DOWN(type->regions[mid].base + type->regions[mid].size);

 	return memblock_get_region_node(&type->regions[mid]);
 }

 /**
  * memblock_is_region_memory - check if a region is a subset of memory
  * @base: base of region to check
  * @size: size of region to check
  *
  * Check if the region [@base, @base + @size) is a subset of a memory block.
  *
  * Return:
  * 0 if false, non-zero if true
  */
 bool __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t size)
 {
 	int idx = memblock_search(&memblock.memory, base);
 	phys_addr_t end = base + memblock_cap_size(base, &size);

 	if (idx == -1)
 		return false;
 	return (memblock.memory.regions[idx].base +
 		 memblock.memory.regions[idx].size) >= end;
 }

 /**
  * memblock_is_region_reserved - check if a region intersects reserved memory
  * @base: base of region to check
  * @size: size of region to check
  *
  * Check if the region [@base, @base + @size) intersects a reserved
  * memory block.
  *
  * Return:
  * True if they intersect, false if not.
  */
 bool __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t size)
 {
 	return memblock_overlaps_region(&memblock.reserved, base, size);
 }

 void __init_memblock memblock_trim_memory(phys_addr_t align)
 {
 	phys_addr_t start, end, orig_start, orig_end;
 	struct memblock_region *r;

 	for_each_mem_region(r) {
 		orig_start = r->base;
 		orig_end = r->base + r->size;
 		start = round_up(orig_start, align);
 		end = round_down(orig_end, align);

 		if (start == orig_start && end == orig_end)
 			continue;

 		if (start < end) {
 			r->base = start;
 			r->size = end - start;
 		} else {
 			memblock_remove_region(&memblock.memory,
 					       r - memblock.memory.regions);
 			r--;
 		}
 	}
 }

 void __init_memblock memblock_set_current_limit(phys_addr_t limit)
 {
 	memblock.current_limit = limit;
 }

 phys_addr_t __init_memblock memblock_get_current_limit(void)
 {
 	return memblock.current_limit;
 }

 static void __init_memblock memblock_dump(struct memblock_type *type)
 {
 	phys_addr_t base, end, size;
 	enum memblock_flags flags;
 	int idx;
 	struct memblock_region *rgn;

 	pr_info(" %s.cnt  = 0x%lx\n", type->name, type->cnt);

 	for_each_memblock_type(idx, type, rgn) {
 		char nid_buf[32] = "";

 		base = rgn->base;
 		size = rgn->size;
 		end = base + size - 1;
 		flags = rgn->flags;
 #ifdef CONFIG_NUMA
 		if (memblock_get_region_node(rgn) != MAX_NUMNODES)
 			snprintf(nid_buf, sizeof(nid_buf), " on node %d",
 				 memblock_get_region_node(rgn));
 #endif
 		pr_info(" %s[%#x]\t[%pa-%pa], %pa bytes%s flags: %#x\n",
 			type->name, idx, &base, &end, &size, nid_buf, flags);
 	}
 }

 static void __init_memblock __memblock_dump_all(void)
 {
 	pr_info("MEMBLOCK configuration:\n");
 	pr_info(" memory size = %pa reserved size = %pa\n",
 		&memblock.memory.total_size,
 		&memblock.reserved.total_size);

 	memblock_dump(&memblock.memory);
 	memblock_dump(&memblock.reserved);
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
 	memblock_dump(&physmem);
 #endif
 }

 void __init_memblock memblock_dump_all(void)
 {
 	if (memblock_debug)
 		__memblock_dump_all();
 }

 void __init memblock_allow_resize(void)
 {
 	memblock_can_resize = 1;
 }

 static int __init early_memblock(char *p)
 {
 	if (p && strstr(p, "debug"))
 		memblock_debug = 1;
 	return 0;
 }
 early_param("memblock", early_memblock);

 static void __init free_memmap(unsigned long start_pfn, unsigned long end_pfn)
 {
 	struct page *start_pg, *end_pg;
 	phys_addr_t pg, pgend;

 	/*
 	 * Convert start_pfn/end_pfn to a struct page pointer.
 	 */
 	start_pg = pfn_to_page(start_pfn - 1) + 1;
 	end_pg = pfn_to_page(end_pfn - 1) + 1;

 	/*
 	 * Convert to physical addresses, and round start upwards and end
 	 * downwards.
 	 */
 	pg = PAGE_ALIGN(__pa(start_pg));
 	pgend = __pa(end_pg) & PAGE_MASK;

 	/*
 	 * If there are free pages between these, free the section of the
 	 * memmap array.
 	 */
 	if (pg < pgend)
 		memblock_free(pg, pgend - pg);
 }

 /*
  * The mem_map array can get very big.  Free the unused area of the memory map.
  */
 static void __init free_unused_memmap(void)
 {
 	unsigned long start, end, prev_end = 0;
 	int i;

 	if (!IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) ||
 	    IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
 		return;

 	/*
 	 * This relies on each bank being in address order.
 	 * The banks are sorted previously in bootmem_init().
 	 */
 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, NULL) {
 #ifdef CONFIG_SPARSEMEM
 		/*
 		 * Take care not to free memmap entries that don't exist
 		 * due to SPARSEMEM sections which aren't present.
 		 */
 		start = min(start, ALIGN(prev_end, PAGES_PER_SECTION));
 #endif
 		/*
 		 * Align down here since many operations in VM subsystem
 		 * presume that there are no holes in the memory map inside
 		 * a pageblock
 		 */
 		start = round_down(start, pageblock_nr_pages);

 		/*
 		 * If we had a previous bank, and there is a space
 		 * between the current bank and the previous, free it.
 		 */
 		if (prev_end && prev_end < start)
 			free_memmap(prev_end, start);

 		/*
 		 * Align up here since many operations in VM subsystem
 		 * presume that there are no holes in the memory map inside
 		 * a pageblock
 		 */
 		prev_end = ALIGN(end, pageblock_nr_pages);
 	}

 #ifdef CONFIG_SPARSEMEM
 	if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION)) {
 		prev_end = ALIGN(end, pageblock_nr_pages);
 		free_memmap(prev_end, ALIGN(prev_end, PAGES_PER_SECTION));
 	}
 #endif
 }

 static void __init __free_pages_memory(unsigned long start, unsigned long end)
 {
 	int order;

 	while (start < end) {
 		order = min(MAX_ORDER - 1UL, __ffs(start));

 		while (start + (1UL << order) > end)
 			order--;

 		memblock_free_pages(pfn_to_page(start), start, order);

 		start += (1UL << order);
 	}
 }

 static unsigned long __init __free_memory_core(phys_addr_t start,
 				 phys_addr_t end)
 {
 	unsigned long start_pfn = PFN_UP(start);
 	unsigned long end_pfn = min_t(unsigned long,
 				      PFN_DOWN(end), max_low_pfn);

 	if (start_pfn >= end_pfn)
 		return 0;

 	__free_pages_memory(start_pfn, end_pfn);

 	return end_pfn - start_pfn;
 }

 static void __init memmap_init_reserved_pages(void)
 {
 	struct memblock_region *region;
 	phys_addr_t start, end;
 	u64 i;

 	/* initialize struct pages for the reserved regions */
 	for_each_reserved_mem_range(i, &start, &end)
 		reserve_bootmem_region(start, end);

 	/* and also treat struct pages for the NOMAP regions as PageReserved */
 	for_each_mem_region(region) {
 		if (memblock_is_nomap(region)) {
 			start = region->base;
 			end = start + region->size;
 			reserve_bootmem_region(start, end);
 		}
 	}
 }

 static unsigned long __init free_low_memory_core_early(void)
 {
 	unsigned long count = 0;
 	phys_addr_t start, end;
 	u64 i;

 	memblock_clear_hotplug(0, -1);

 	memmap_init_reserved_pages();

 	/*
 	 * We need to use NUMA_NO_NODE instead of NODE_DATA(0)->node_id
 	 *  because in some case like Node0 doesn't have RAM installed
 	 *  low ram will be on Node1
 	 */
 	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
 				NULL)
 		count += __free_memory_core(start, end);

 	return count;
 }

 static int reset_managed_pages_done __initdata;

 void reset_node_managed_pages(pg_data_t *pgdat)
 {
 	struct zone *z;

 	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
 		atomic_long_set(&z->managed_pages, 0);
 }

 void __init reset_all_zones_managed_pages(void)
 {
 	struct pglist_data *pgdat;

 	if (reset_managed_pages_done)
 		return;

 	for_each_online_pgdat(pgdat)
 		reset_node_managed_pages(pgdat);

 	reset_managed_pages_done = 1;
 }

 /**
  * memblock_free_all - release free pages to the buddy allocator
  */
 void __init memblock_free_all(void)
 {
 	unsigned long pages;

 	free_unused_memmap();
 	reset_all_zones_managed_pages();

 	pages = free_low_memory_core_early();
 	totalram_pages_add(pages);
 }

 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK)

 static int memblock_debug_show(struct seq_file *m, void *private)
 {
 	struct memblock_type *type = m->private;
 	struct memblock_region *reg;
 	int i;
 	phys_addr_t end;

 	for (i = 0; i < type->cnt; i++) {
 		reg = &type->regions[i];
 		end = reg->base + reg->size - 1;

 		seq_printf(m, "%4d: ", i);
 		seq_printf(m, "%pa..%pa\n", &reg->base, &end);
 	}
 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(memblock_debug);

 static int __init memblock_init_debugfs(void)
 {
 	struct dentry *root = debugfs_create_dir("memblock", NULL);

 	debugfs_create_file("memory", 0444, root,
 			    &memblock.memory, &memblock_debug_fops);
 	debugfs_create_file("reserved", 0444, root,
 			    &memblock.reserved, &memblock_debug_fops);
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
 	debugfs_create_file("physmem", 0444, root, &physmem,
 			    &memblock_debug_fops);
 #endif

 	return 0;
 }
 __initcall(memblock_init_debugfs);

 #endif /* CONFIG_DEBUG_FS */