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mapcontroller.md

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  • bootmem.c 20.78 KiB
    /*
     *  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/export.h>
    #include <linux/kmemleak.h>
    #include <linux/range.h>
    #include <linux/bug.h>
    #include <linux/io.h>
    #include <linux/bootmem.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;
    unsigned long long max_possible_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))			\
    		pr_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)
    {
    	bootmem_data_t *ent;
    
    	list_for_each_entry(ent, &bdata_list, list) {
    		if (bdata->node_min_pfn < ent->node_min_pfn) {
    			list_add_tail(&bdata->list, &ent->list);
    			return;
    		}
    	}
    
    	list_add_tail(&bdata->list, &bdata_list);
    }
    
    /*
     * 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 physical 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 physaddr, unsigned long size)
    {
    	unsigned long cursor, end;
    
    	kmemleak_free_part_phys(physaddr, size);
    
    	cursor = PFN_UP(physaddr);
    	end = PFN_DOWN(physaddr + size);
    
    	for (; cursor < end; cursor++) {
    		__free_pages_bootmem(pfn_to_page(cursor), cursor, 0);
    		totalram_pages++;
    	}
    }
    
    static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
    {
    	struct page *page;
    	unsigned long *map, start, end, pages, cur, count = 0;
    
    	if (!bdata->node_bootmem_map)
    		return 0;
    
    	map = bdata->node_bootmem_map;
    	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 idx, vec;
    		unsigned shift;
    
    		idx = start - bdata->node_min_pfn;
    		shift = idx & (BITS_PER_LONG - 1);
    		/*
    		 * vec holds at most BITS_PER_LONG map bits,
    		 * bit 0 corresponds to start.
    		 */
    		vec = ~map[idx / BITS_PER_LONG];
    
    		if (shift) {
    			vec >>= shift;
    			if (end - start >= BITS_PER_LONG)
    				vec |= ~map[idx / BITS_PER_LONG + 1] <<
    					(BITS_PER_LONG - shift);
    		}
    		/*
    		 * 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), start, order);
    			count += BITS_PER_LONG;
    			start += BITS_PER_LONG;
    		} else {
    			cur = start;
    
    			start = ALIGN(start + 1, BITS_PER_LONG);
    			while (vec && cur != start) {
    				if (vec & 1) {
    					page = pfn_to_page(cur);
    					__free_pages_bootmem(page, cur, 0);
    					count++;
    				}
    				vec >>= 1;
    				++cur;
    			}
    		}
    	}
    
    	cur = bdata->node_min_pfn;
    	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++, cur++, 0);
    	bdata->node_bootmem_map = NULL;
    
    	bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
    
    	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++)
    		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;
    }
    
    /**
     * 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;
    
    	reset_all_zones_managed_pages();
    
    	list_for_each_entry(bdata, &bdata_list, list)
    		total_pages += free_all_bootmem_core(bdata);
    
    	totalram_pages += total_pages;
    
    	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 (WARN_ON(bdata->node_bootmem_map == NULL))
    		return;
    
    	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);
    
    	if (WARN_ON(bdata->node_bootmem_map == NULL))
    		return 0;
    
    	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_phys(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 physical 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 physaddr, unsigned long size)
    {
    	unsigned long start, end;
    
    	kmemleak_free_part_phys(physaddr, size);
    
    	start = PFN_UP(physaddr);
    	end = PFN_DOWN(physaddr + 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 reserved
     * @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);
    }
    
    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_bdata(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_bootmem_core(unsigned long size,
    					unsigned long align,
    					unsigned long goal,
    					unsigned long limit)
    {
    	bootmem_data_t *bdata;
    	void *region;
    
    	if (WARN_ON_ONCE(slab_is_available()))
    		return kzalloc(size, GFP_NOWAIT);
    
    	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_bdata(bdata, size, align, goal, limit);
    		if (region)
    			return region;
    	}
    
    	return NULL;
    }
    
    static void * __init ___alloc_bootmem_nopanic(unsigned long size,
    					      unsigned long align,
    					      unsigned long goal,
    					      unsigned long limit)
    {
    	void *ptr;
    
    restart:
    	ptr = alloc_bootmem_core(size, align, goal, limit);
    	if (ptr)
    		return ptr;
    	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.
    	 */
    	pr_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);
    }
    
    void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
    				unsigned long size, unsigned long align,
    				unsigned long goal, unsigned long limit)
    {
    	void *ptr;
    
    	if (WARN_ON_ONCE(slab_is_available()))
    		return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
    again:
    
    	/* do not panic in alloc_bootmem_bdata() */
    	if (limit && goal + size > limit)
    		limit = 0;
    
    	ptr = alloc_bootmem_bdata(pgdat->bdata, size, align, goal, limit);
    	if (ptr)
    		return ptr;
    
    	ptr = alloc_bootmem_core(size, align, goal, limit);
    	if (ptr)
    		return ptr;
    
    	if (goal) {
    		goal = 0;
    		goto again;
    	}
    
    	return NULL;
    }
    
    void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
    				   unsigned long align, unsigned long goal)
    {
    	return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
    }
    
    void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
    				    unsigned long align, unsigned long goal,
    				    unsigned long limit)
    {
    	void *ptr;
    
    	ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
    	if (ptr)
    		return ptr;
    
    	pr_alert("bootmem alloc of %lu bytes failed!\n", size);
    	panic("Out of memory");
    	return NULL;
    }
    
    /**
     * __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, 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_end_pfn(pgdat);
    
    	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_bdata(pgdat->bdata, size, align,
    						 new_goal, 0);
    		if (ptr)
    			return ptr;
    	}
    #endif
    
    	return __alloc_bootmem_node(pgdat, size, align, goal);
    
    }
    
    /**
     * __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);
    }
    
    void * __init __alloc_bootmem_low_nopanic(unsigned long size,
    					  unsigned long align,
    					  unsigned long goal)
    {
    	return ___alloc_bootmem_nopanic(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, size, align,
    				     goal, ARCH_LOW_ADDRESS_LIMIT);
    }