text: /*
   *  bootmem - A boot-time physical memory allocator and configurator
   *
   *  Copyright (C) 1999 Ingo Molnar
   *                1999 Kanoj Sarcar, SGI
   *                2008 Johannes Weiner
   *
   * Access to this subsystem has to be serialized externally (which is true
   * for the boot process anyway).
   */
  #include <linux/init.h>
  #include <linux/pfn.h>
  #include <linux/slab.h>
  #include <linux/bootmem.h>
  #include <linux/export.h>
  #include <linux/kmemleak.h>
  #include <linux/range.h>
  #include <linux/memblock.h>
  
  #include <asm/bug.h>
  #include <asm/io.h>
  #include <asm/processor.h>
  
  #include "internal.h"
  
  #ifndef CONFIG_NEED_MULTIPLE_NODES
  struct pglist_data __refdata contig_page_data = {
  	.bdata = &bootmem_node_data[0]
  };
  EXPORT_SYMBOL(contig_page_data);
  #endif
  
  unsigned long max_low_pfn;
  unsigned long min_low_pfn;
  unsigned long max_pfn;
  
  bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
  
  static struct list_head bdata_list __initdata = LIST_HEAD_INIT(bdata_list);
  
  static int bootmem_debug;
  
  static int __init bootmem_debug_setup(char *buf)
  {
  	bootmem_debug = 1;
  	return 0;
  }
  early_param("bootmem_debug", bootmem_debug_setup);
  
  #define bdebug(fmt, args...) ({				\
  	if (unlikely(bootmem_debug))			\
  		printk(KERN_INFO			\
  			"bootmem::%s " fmt,		\
  			__func__, ## args);		\
  })
  
  static unsigned long __init bootmap_bytes(unsigned long pages)
  {
  	unsigned long bytes = DIV_ROUND_UP(pages, 8);
  
  	return ALIGN(bytes, sizeof(long));
  }
  
  /**
   * bootmem_bootmap_pages - calculate bitmap size in pages
   * @pages: number of pages the bitmap has to represent
   */
  unsigned long __init bootmem_bootmap_pages(unsigned long pages)
  {
  	unsigned long bytes = bootmap_bytes(pages);
  
  	return PAGE_ALIGN(bytes) >> PAGE_SHIFT;
  }
  
  /*
   * link bdata in order
   */
  static void __init link_bootmem(bootmem_data_t *bdata)
  {
  	struct list_head *iter;
  
  	list_for_each(iter, &bdata_list) {
  		bootmem_data_t *ent;
  
  		ent = list_entry(iter, bootmem_data_t, list);
  		if (bdata->node_min_pfn < ent->node_min_pfn)
  			break;
  	}
  	list_add_tail(&bdata->list, iter);
  }
  
  /*
   * Called once to set up the allocator itself.
   */
  static unsigned long __init init_bootmem_core(bootmem_data_t *bdata,
  	unsigned long mapstart, unsigned long start, unsigned long end)
  {
  	unsigned long mapsize;
  
  	mminit_validate_memmodel_limits(&start, &end);
  	bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
  	bdata->node_min_pfn = start;
  	bdata->node_low_pfn = end;
  	link_bootmem(bdata);
  
  	/*
  	 * Initially all pages are reserved - setup_arch() has to
  	 * register free RAM areas explicitly.
  	 */
  	mapsize = bootmap_bytes(end - start);
  	memset(bdata->node_bootmem_map, 0xff, mapsize);
  
  	bdebug("nid=%td start=%lx map=%lx end=%lx mapsize=%lx\n",
  		bdata - bootmem_node_data, start, mapstart, end, mapsize);
  
  	return mapsize;
  }
  
  /**
   * init_bootmem_node - register a node as boot memory
   * @pgdat: node to register
   * @freepfn: pfn where the bitmap for this node is to be placed
   * @startpfn: first pfn on the node
   * @endpfn: first pfn after the node
   *
   * Returns the number of bytes needed to hold the bitmap for this node.
   */
  unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
  				unsigned long startpfn, unsigned long endpfn)
  {
  	return init_bootmem_core(pgdat->bdata, freepfn, startpfn, endpfn);
  }
  
  /**
   * init_bootmem - register boot memory
   * @start: pfn where the bitmap is to be placed
   * @pages: number of available physical pages
   *
   * Returns the number of bytes needed to hold the bitmap.
   */
  unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
  {
  	max_low_pfn = pages;
  	min_low_pfn = start;
  	return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages);
  }
  
  /*
   * free_bootmem_late - free bootmem pages directly to page allocator
   * @addr: starting address of the range
   * @size: size of the range in bytes
   *
   * This is only useful when the bootmem allocator has already been torn
   * down, but we are still initializing the system.  Pages are given directly
   * to the page allocator, no bootmem metadata is updated because it is gone.
   */
  void __init free_bootmem_late(unsigned long addr, unsigned long size)
  {
  	unsigned long cursor, end;
  
  	kmemleak_free_part(__va(addr), size);
  
  	cursor = PFN_UP(addr);
  	end = PFN_DOWN(addr + size);
  
  	for (; cursor < end; cursor++) {
  		__free_pages_bootmem(pfn_to_page(cursor), 0);
  		totalram_pages++;
  	}
  }
  
  static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
  {
  	struct page *page;
  	unsigned long start, end, pages, count = 0;
  
  	if (!bdata->node_bootmem_map)
  		return 0;
  
  	start = bdata->node_min_pfn;
  	end = bdata->node_low_pfn;
  
  	bdebug("nid=%td start=%lx end=%lx\n",
  		bdata - bootmem_node_data, start, end);
  
  	while (start < end) {
  		unsigned long *map, idx, vec;
  
  		map = bdata->node_bootmem_map;
  		idx = start - bdata->node_min_pfn;
  		vec = ~map[idx / BITS_PER_LONG];
  		/*
  		 * If we have a properly aligned and fully unreserved
  		 * BITS_PER_LONG block of pages in front of us, free
  		 * it in one go.
  		 */
  		if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL) {
  			int order = ilog2(BITS_PER_LONG);
  
  			__free_pages_bootmem(pfn_to_page(start), order);
  			count += BITS_PER_LONG;
  			start += BITS_PER_LONG;
  		} else {
  			unsigned long off = 0;
  
  			while (vec && off < BITS_PER_LONG) {
  				if (vec & 1) {
  					page = pfn_to_page(start + off);
  					__free_pages_bootmem(page, 0);
  					count++;
  				}
  				vec >>= 1;
  				off++;
  			}
  			start = ALIGN(start + 1, BITS_PER_LONG);
  		}
  	}
  
  	page = virt_to_page(bdata->node_bootmem_map);
  	pages = bdata->node_low_pfn - bdata->node_min_pfn;
  	pages = bootmem_bootmap_pages(pages);
  	count += pages;
  	while (pages--)
  		__free_pages_bootmem(page++, 0);
  
  	bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
  
  	return count;
  }
  
  /**
   * free_all_bootmem_node - release a node's free pages to the buddy allocator
   * @pgdat: node to be released
   *
   * Returns the number of pages actually released.
   */
  unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
  {
  	register_page_bootmem_info_node(pgdat);
  	return free_all_bootmem_core(pgdat->bdata);
  }
  
  /**
   * free_all_bootmem - release free pages to the buddy allocator
   *
   * Returns the number of pages actually released.
   */
  unsigned long __init free_all_bootmem(void)
  {
  	unsigned long total_pages = 0;
  	bootmem_data_t *bdata;
  
  	list_for_each_entry(bdata, &bdata_list, list)
  		total_pages += free_all_bootmem_core(bdata);
  
  	return total_pages;
  }
  
  static void __init __free(bootmem_data_t *bdata,
  			unsigned long sidx, unsigned long eidx)
  {
  	unsigned long idx;
  
  	bdebug("nid=%td start=%lx end=%lx\n", bdata - bootmem_node_data,
  		sidx + bdata->node_min_pfn,
  		eidx + bdata->node_min_pfn);
  
  	if (bdata->hint_idx > sidx)
  		bdata->hint_idx = sidx;
  
  	for (idx = sidx; idx < eidx; idx++)
  		if (!test_and_clear_bit(idx, bdata->node_bootmem_map))
  			BUG();
  }
  
  static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,
  			unsigned long eidx, int flags)
  {
  	unsigned long idx;
  	int exclusive = flags & BOOTMEM_EXCLUSIVE;
  
  	bdebug("nid=%td start=%lx end=%lx flags=%x\n",
  		bdata - bootmem_node_data,
  		sidx + bdata->node_min_pfn,
  		eidx + bdata->node_min_pfn,
  		flags);
  
  	for (idx = sidx; idx < eidx; idx++)
  		if (test_and_set_bit(idx, bdata->node_bootmem_map)) {
  			if (exclusive) {
  				__free(bdata, sidx, idx);
  				return -EBUSY;
  			}
  			bdebug("silent double reserve of PFN %lx\n",
  				idx + bdata->node_min_pfn);
  		}
  	return 0;
  }
  
  static int __init mark_bootmem_node(bootmem_data_t *bdata,
  				unsigned long start, unsigned long end,
  				int reserve, int flags)
  {
  	unsigned long sidx, eidx;
  
  	bdebug("nid=%td start=%lx end=%lx reserve=%d flags=%x\n",
  		bdata - bootmem_node_data, start, end, reserve, flags);
  
  	BUG_ON(start < bdata->node_min_pfn);
  	BUG_ON(end > bdata->node_low_pfn);
  
  	sidx = start - bdata->node_min_pfn;
  	eidx = end - bdata->node_min_pfn;
  
  	if (reserve)
  		return __reserve(bdata, sidx, eidx, flags);
  	else
  		__free(bdata, sidx, eidx);
  	return 0;
  }
  
  static int __init mark_bootmem(unsigned long start, unsigned long end,
  				int reserve, int flags)
  {
  	unsigned long pos;
  	bootmem_data_t *bdata;
  
  	pos = start;
  	list_for_each_entry(bdata, &bdata_list, list) {
  		int err;
  		unsigned long max;
  
  		if (pos < bdata->node_min_pfn ||
  		    pos >= bdata->node_low_pfn) {
  			BUG_ON(pos != start);
  			continue;
  		}
  
  		max = min(bdata->node_low_pfn, end);
  
  		err = mark_bootmem_node(bdata, pos, max, reserve, flags);
  		if (reserve && err) {
  			mark_bootmem(start, pos, 0, 0);
  			return err;
  		}
  
  		if (max == end)
  			return 0;
  		pos = bdata->node_low_pfn;
  	}
  	BUG();
  }
  
  /**
   * free_bootmem_node - mark a page range as usable
   * @pgdat: node the range resides on
   * @physaddr: starting address of the range
   * @size: size of the range in bytes
   *
   * Partial pages will be considered reserved and left as they are.
   *
   * The range must reside completely on the specified node.
   */
  void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
  			      unsigned long size)
  {
  	unsigned long start, end;
  
  	kmemleak_free_part(__va(physaddr), size);
  
  	start = PFN_UP(physaddr);
  	end = PFN_DOWN(physaddr + size);
  
  	mark_bootmem_node(pgdat->bdata, start, end, 0, 0);
  }
  
  /**
   * free_bootmem - mark a page range as usable
   * @addr: starting address of the range
   * @size: size of the range in bytes
   *
   * Partial pages will be considered reserved and left as they are.
   *
   * The range must be contiguous but may span node boundaries.
   */
  void __init free_bootmem(unsigned long addr, unsigned long size)
  {
  	unsigned long start, end;
  
  	kmemleak_free_part(__va(addr), size);
  
  	start = PFN_UP(addr);
  	end = PFN_DOWN(addr + size);
  
  	mark_bootmem(start, end, 0, 0);
  }
  
  /**
   * reserve_bootmem_node - mark a page range as reserved
   * @pgdat: node the range resides on
   * @physaddr: starting address of the range
   * @size: size of the range in bytes
   * @flags: reservation flags (see linux/bootmem.h)
   *
   * Partial pages will be reserved.
   *
   * The range must reside completely on the specified node.
   */
  int __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
  				 unsigned long size, int flags)
  {
  	unsigned long start, end;
  
  	start = PFN_DOWN(physaddr);
  	end = PFN_UP(physaddr + size);
  
  	return mark_bootmem_node(pgdat->bdata, start, end, 1, flags);
  }
  
  /**
   * reserve_bootmem - mark a page range as usable
   * @addr: starting address of the range
   * @size: size of the range in bytes
   * @flags: reservation flags (see linux/bootmem.h)
   *
   * Partial pages will be reserved.
   *
   * The range must be contiguous but may span node boundaries.
   */
  int __init reserve_bootmem(unsigned long addr, unsigned long size,
  			    int flags)
  {
  	unsigned long start, end;
  
  	start = PFN_DOWN(addr);
  	end = PFN_UP(addr + size);
  
  	return mark_bootmem(start, end, 1, flags);
  }
  
  int __weak __init reserve_bootmem_generic(unsigned long phys, unsigned long len,
  				   int flags)
  {
  	return reserve_bootmem(phys, len, flags);
  }
  
  static unsigned long __init align_idx(struct bootmem_data *bdata,
  				      unsigned long idx, unsigned long step)
  {
  	unsigned long base = bdata->node_min_pfn;
  
  	/*
  	 * Align the index with respect to the node start so that the
  	 * combination of both satisfies the requested alignment.
  	 */
  
  	return ALIGN(base + idx, step) - base;
  }
  
  static unsigned long __init align_off(struct bootmem_data *bdata,
  				      unsigned long off, unsigned long align)
  {
  	unsigned long base = PFN_PHYS(bdata->node_min_pfn);
  
  	/* Same as align_idx for byte offsets */
  
  	return ALIGN(base + off, align) - base;
  }
  
  static void * __init alloc_bootmem_core(struct bootmem_data *bdata,
  					unsigned long size, unsigned long align,
  					unsigned long goal, unsigned long limit)
  {
  	unsigned long fallback = 0;
  	unsigned long min, max, start, sidx, midx, step;
  
  	bdebug("nid=%td size=%lx [%lu pages] align=%lx goal=%lx limit=%lx\n",
  		bdata - bootmem_node_data, size, PAGE_ALIGN(size) >> PAGE_SHIFT,
  		align, goal, limit);
  
  	BUG_ON(!size);
  	BUG_ON(align & (align - 1));
  	BUG_ON(limit && goal + size > limit);
  
  	if (!bdata->node_bootmem_map)
  		return NULL;
  
  	min = bdata->node_min_pfn;
  	max = bdata->node_low_pfn;
  
  	goal >>= PAGE_SHIFT;
  	limit >>= PAGE_SHIFT;
  
  	if (limit && max > limit)
  		max = limit;
  	if (max <= min)
  		return NULL;
  
  	step = max(align >> PAGE_SHIFT, 1UL);
  
  	if (goal && min < goal && goal < max)
  		start = ALIGN(goal, step);
  	else
  		start = ALIGN(min, step);
  
  	sidx = start - bdata->node_min_pfn;
  	midx = max - bdata->node_min_pfn;
  
  	if (bdata->hint_idx > sidx) {
  		/*
  		 * Handle the valid case of sidx being zero and still
  		 * catch the fallback below.
  		 */
  		fallback = sidx + 1;
  		sidx = align_idx(bdata, bdata->hint_idx, step);
  	}
  
  	while (1) {
  		int merge;
  		void *region;
  		unsigned long eidx, i, start_off, end_off;
  find_block:
  		sidx = find_next_zero_bit(bdata->node_bootmem_map, midx, sidx);
  		sidx = align_idx(bdata, sidx, step);
  		eidx = sidx + PFN_UP(size);
  
  		if (sidx >= midx || eidx > midx)
  			break;
  
  		for (i = sidx; i < eidx; i++)
  			if (test_bit(i, bdata->node_bootmem_map)) {
  				sidx = align_idx(bdata, i, step);
  				if (sidx == i)
  					sidx += step;
  				goto find_block;
  			}
  
  		if (bdata->last_end_off & (PAGE_SIZE - 1) &&
  				PFN_DOWN(bdata->last_end_off) + 1 == sidx)
  			start_off = align_off(bdata, bdata->last_end_off, align);
  		else
  			start_off = PFN_PHYS(sidx);
  
  		merge = PFN_DOWN(start_off) < sidx;
  		end_off = start_off + size;
  
  		bdata->last_end_off = end_off;
  		bdata->hint_idx = PFN_UP(end_off);
  
  		/*
  		 * Reserve the area now:
  		 */
  		if (__reserve(bdata, PFN_DOWN(start_off) + merge,
  				PFN_UP(end_off), BOOTMEM_EXCLUSIVE))
  			BUG();
  
  		region = phys_to_virt(PFN_PHYS(bdata->node_min_pfn) +
  				start_off);
  		memset(region, 0, size);
  		/*
  		 * The min_count is set to 0 so that bootmem allocated blocks
  		 * are never reported as leaks.
  		 */
  		kmemleak_alloc(region, size, 0, 0);
  		return region;
  	}
  
  	if (fallback) {
  		sidx = align_idx(bdata, fallback - 1, step);
  		fallback = 0;
  		goto find_block;
  	}
  
  	return NULL;
  }
  
  static void * __init alloc_arch_preferred_bootmem(bootmem_data_t *bdata,
  					unsigned long size, unsigned long align,
  					unsigned long goal, unsigned long limit)
  {
  	if (WARN_ON_ONCE(slab_is_available()))
  		return kzalloc(size, GFP_NOWAIT);
  
  #ifdef CONFIG_HAVE_ARCH_BOOTMEM
  	{
  		bootmem_data_t *p_bdata;
  
  		p_bdata = bootmem_arch_preferred_node(bdata, size, align,
  							goal, limit);
  		if (p_bdata)
  			return alloc_bootmem_core(p_bdata, size, align,
  							goal, limit);
  	}
  #endif
  	return NULL;
  }
  
  static void * __init ___alloc_bootmem_nopanic(unsigned long size,
  					unsigned long align,
  					unsigned long goal,
  					unsigned long limit)
  {
  	bootmem_data_t *bdata;
  	void *region;
  
  restart:
  	region = alloc_arch_preferred_bootmem(NULL, size, align, goal, limit);
  	if (region)
  		return region;
  
  	list_for_each_entry(bdata, &bdata_list, list) {
  		if (goal && bdata->node_low_pfn <= PFN_DOWN(goal))
  			continue;
  		if (limit && bdata->node_min_pfn >= PFN_DOWN(limit))
  			break;
  
  		region = alloc_bootmem_core(bdata, size, align, goal, limit);
  		if (region)
  			return region;
  	}
  
  	if (goal) {
  		goal = 0;
  		goto restart;
  	}
  
  	return NULL;
  }
  
  /**
   * __alloc_bootmem_nopanic - allocate boot memory without panicking
   * @size: size of the request in bytes
   * @align: alignment of the region
   * @goal: preferred starting address of the region
   *
   * The goal is dropped if it can not be satisfied and the allocation will
   * fall back to memory below @goal.
   *
   * Allocation may happen on any node in the system.
   *
   * Returns NULL on failure.
   */
  void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
  					unsigned long goal)
  {
  	unsigned long limit = 0;
  
  	return ___alloc_bootmem_nopanic(size, align, goal, limit);
  }
  
  static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
  					unsigned long goal, unsigned long limit)
  {
  	void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit);
  
  	if (mem)
  		return mem;
  	/*
  	 * Whoops, we cannot satisfy the allocation request.
  	 */
  	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
  	panic("Out of memory");
  	return NULL;
  }
  
  /**
   * __alloc_bootmem - allocate boot memory
   * @size: size of the request in bytes
   * @align: alignment of the region
   * @goal: preferred starting address of the region
   *
   * The goal is dropped if it can not be satisfied and the allocation will
   * fall back to memory below @goal.
   *
   * Allocation may happen on any node in the system.
   *
   * The function panics if the request can not be satisfied.
   */
  void * __init __alloc_bootmem(unsigned long size, unsigned long align,
  			      unsigned long goal)
  {
  	unsigned long limit = 0;
  
  	return ___alloc_bootmem(size, align, goal, limit);
  }
  
  static void * __init ___alloc_bootmem_node(bootmem_data_t *bdata,
  				unsigned long size, unsigned long align,
  				unsigned long goal, unsigned long limit)
  {
  	void *ptr;
  
  	ptr = alloc_arch_preferred_bootmem(bdata, size, align, goal, limit);
  	if (ptr)
  		return ptr;
  
  	ptr = alloc_bootmem_core(bdata, size, align, goal, limit);
  	if (ptr)
  		return ptr;
  
  	return ___alloc_bootmem(size, align, goal, limit);
  }
  
  /**
   * __alloc_bootmem_node - allocate boot memory from a specific node
   * @pgdat: node to allocate from
   * @size: size of the request in bytes
   * @align: alignment of the region
   * @goal: preferred starting address of the region
   *
   * The goal is dropped if it can not be satisfied and the allocation will
   * fall back to memory below @goal.
   *
   * Allocation may fall back to any node in the system if the specified node
   * can not hold the requested memory.
   *
   * The function panics if the request can not be satisfied.
   */
  void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
  				   unsigned long align, unsigned long goal)
  {
  	if (WARN_ON_ONCE(slab_is_available()))
  		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
  
  	return  ___alloc_bootmem_node(pgdat->bdata, size, align, goal, 0);
  }
  
  void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size,
  				   unsigned long align, unsigned long goal)
  {
  #ifdef MAX_DMA32_PFN
  	unsigned long end_pfn;
  
  	if (WARN_ON_ONCE(slab_is_available()))
  		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
  
  	/* update goal according ...MAX_DMA32_PFN */
  	end_pfn = pgdat->node_start_pfn + pgdat->node_spanned_pages;
  
  	if (end_pfn > MAX_DMA32_PFN + (128 >> (20 - PAGE_SHIFT)) &&
  	    (goal >> PAGE_SHIFT) < MAX_DMA32_PFN) {
  		void *ptr;
  		unsigned long new_goal;
  
  		new_goal = MAX_DMA32_PFN << PAGE_SHIFT;
  		ptr = alloc_bootmem_core(pgdat->bdata, size, align,
  						 new_goal, 0);
  		if (ptr)
  			return ptr;
  	}
  #endif
  
  	return __alloc_bootmem_node(pgdat, size, align, goal);
  
  }
  
  #ifdef CONFIG_SPARSEMEM
  /**
   * alloc_bootmem_section - allocate boot memory from a specific section
   * @size: size of the request in bytes
   * @section_nr: sparse map section to allocate from
   *
   * Return NULL on failure.
   */
  void * __init alloc_bootmem_section(unsigned long size,
  				    unsigned long section_nr)
  {
  	bootmem_data_t *bdata;
  	unsigned long pfn, goal, limit;
  
  	pfn = section_nr_to_pfn(section_nr);
  	goal = pfn << PAGE_SHIFT;
  	limit = section_nr_to_pfn(section_nr + 1) << PAGE_SHIFT;
  	bdata = &bootmem_node_data[early_pfn_to_nid(pfn)];
  
  	return alloc_bootmem_core(bdata, size, SMP_CACHE_BYTES, goal, limit);
  }
  #endif
  
  void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
  				   unsigned long align, unsigned long goal)
  {
  	void *ptr;
  
  	if (WARN_ON_ONCE(slab_is_available()))
  		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
  
  	ptr = alloc_arch_preferred_bootmem(pgdat->bdata, size, align, goal, 0);
  	if (ptr)
  		return ptr;
  
  	ptr = alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);
  	if (ptr)
  		return ptr;
  
  	return __alloc_bootmem_nopanic(size, align, goal);
  }
  
  #ifndef ARCH_LOW_ADDRESS_LIMIT
  #define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
  #endif
  
  /**
   * __alloc_bootmem_low - allocate low boot memory
   * @size: size of the request in bytes
   * @align: alignment of the region
   * @goal: preferred starting address of the region
   *
   * The goal is dropped if it can not be satisfied and the allocation will
   * fall back to memory below @goal.
   *
   * Allocation may happen on any node in the system.
   *
   * The function panics if the request can not be satisfied.
   */
  void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
  				  unsigned long goal)
  {
  	return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT);
  }
  
  /**
   * __alloc_bootmem_low_node - allocate low boot memory from a specific node
   * @pgdat: node to allocate from
   * @size: size of the request in bytes
   * @align: alignment of the region
   * @goal: preferred starting address of the region
   *
   * The goal is dropped if it can not be satisfied and the allocation will
   * fall back to memory below @goal.
   *
   * Allocation may fall back to any node in the system if the specified node
   * can not hold the requested memory.
   *
   * The function panics if the request can not be satisfied.
   */
  void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
  				       unsigned long align, unsigned long goal)
  {
  	if (WARN_ON_ONCE(slab_is_available()))
  		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
  
  	return ___alloc_bootmem_node(pgdat->bdata, size, align,
  				goal, ARCH_LOW_ADDRESS_LIMIT);
  }
  