bootmem.c 11.9 KB
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/*
 *  linux/mm/bootmem.c
 *
 *  Copyright (C) 1999 Ingo Molnar
 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 *
 *  simple boot-time physical memory area allocator and
 *  free memory collector. It's used to deal with reserved
 *  system memory and memory holes as well.
 */
#include <linux/init.h>
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#include <linux/pfn.h>
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#include <linux/bootmem.h>
#include <linux/module.h>
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#include <asm/bug.h>
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#include <asm/io.h>
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#include "internal.h"

/*
 * Access to this subsystem has to be serialized externally. (this is
 * true for the boot process anyway)
 */
unsigned long max_low_pfn;
unsigned long min_low_pfn;
unsigned long max_pfn;

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EXPORT_UNUSED_SYMBOL(max_pfn);  /*  June 2006  */
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static LIST_HEAD(bdata_list);
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#ifdef CONFIG_CRASH_DUMP
/*
 * If we have booted due to a crash, max_pfn will be a very low value. We need
 * to know the amount of memory that the previous kernel used.
 */
unsigned long saved_max_pfn;
#endif

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/* return the number of _pages_ that will be allocated for the boot bitmap */
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unsigned long __init bootmem_bootmap_pages(unsigned long pages)
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{
	unsigned long mapsize;

	mapsize = (pages+7)/8;
	mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
	mapsize >>= PAGE_SHIFT;

	return mapsize;
}
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/*
 * link bdata in order
 */
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static void __init link_bootmem(bootmem_data_t *bdata)
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{
	bootmem_data_t *ent;
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	if (list_empty(&bdata_list)) {
		list_add(&bdata->list, &bdata_list);
		return;
	}
	/* insert in order */
	list_for_each_entry(ent, &bdata_list, list) {
		if (bdata->node_boot_start < ent->node_boot_start) {
			list_add_tail(&bdata->list, &ent->list);
			return;
		}
	}
	list_add_tail(&bdata->list, &bdata_list);
}

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/*
 * Given an initialised bdata, it returns the size of the boot bitmap
 */
static unsigned long __init get_mapsize(bootmem_data_t *bdata)
{
	unsigned long mapsize;
	unsigned long start = PFN_DOWN(bdata->node_boot_start);
	unsigned long end = bdata->node_low_pfn;

	mapsize = ((end - start) + 7) / 8;
	return ALIGN(mapsize, sizeof(long));
}
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/*
 * Called once to set up the allocator itself.
 */
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static unsigned long __init init_bootmem_core(pg_data_t *pgdat,
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	unsigned long mapstart, unsigned long start, unsigned long end)
{
	bootmem_data_t *bdata = pgdat->bdata;
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	unsigned long mapsize;
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	bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
	bdata->node_boot_start = PFN_PHYS(start);
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	bdata->node_low_pfn = end;
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	link_bootmem(bdata);
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	/*
	 * Initially all pages are reserved - setup_arch() has to
	 * register free RAM areas explicitly.
	 */
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	mapsize = get_mapsize(bdata);
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	memset(bdata->node_bootmem_map, 0xff, mapsize);

	return mapsize;
}

/*
 * Marks a particular physical memory range as unallocatable. Usable RAM
 * might be used for boot-time allocations - or it might get added
 * to the free page pool later on.
 */
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static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
					unsigned long size)
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{
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	unsigned long sidx, eidx;
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	unsigned long i;
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	/*
	 * round up, partially reserved pages are considered
	 * fully reserved.
	 */
	BUG_ON(!size);
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	BUG_ON(PFN_DOWN(addr) >= bdata->node_low_pfn);
	BUG_ON(PFN_UP(addr + size) > bdata->node_low_pfn);

	sidx = PFN_DOWN(addr - bdata->node_boot_start);
	eidx = PFN_UP(addr + size - bdata->node_boot_start);
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	for (i = sidx; i < eidx; i++)
		if (test_and_set_bit(i, bdata->node_bootmem_map)) {
#ifdef CONFIG_DEBUG_BOOTMEM
			printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
#endif
		}
}

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static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
				     unsigned long size)
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{
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	unsigned long sidx, eidx;
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	unsigned long i;
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	/*
	 * round down end of usable mem, partially free pages are
	 * considered reserved.
	 */
	BUG_ON(!size);
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	BUG_ON(PFN_DOWN(addr + size) > bdata->node_low_pfn);
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	if (addr < bdata->last_success)
		bdata->last_success = addr;

	/*
	 * Round up the beginning of the address.
	 */
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	sidx = PFN_UP(addr) - PFN_DOWN(bdata->node_boot_start);
	eidx = PFN_DOWN(addr + size - bdata->node_boot_start);
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	for (i = sidx; i < eidx; i++) {
		if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
			BUG();
	}
}

/*
 * We 'merge' subsequent allocations to save space. We might 'lose'
 * some fraction of a page if allocations cannot be satisfied due to
 * size constraints on boxes where there is physical RAM space
 * fragmentation - in these cases (mostly large memory boxes) this
 * is not a problem.
 *
 * On low memory boxes we get it right in 100% of the cases.
 *
 * alignment has to be a power of 2 value.
 *
 * NOTE:  This function is _not_ reentrant.
 */
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void * __init
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__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
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	      unsigned long align, unsigned long goal, unsigned long limit)
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{
	unsigned long offset, remaining_size, areasize, preferred;
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	unsigned long i, start = 0, incr, eidx, end_pfn;
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	void *ret;

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	if (!size) {
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		printk("__alloc_bootmem_core(): zero-sized request\n");
		BUG();
	}
	BUG_ON(align & (align-1));

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	if (limit && bdata->node_boot_start >= limit)
		return NULL;

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	end_pfn = bdata->node_low_pfn;
	limit = PFN_DOWN(limit);
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	if (limit && end_pfn > limit)
		end_pfn = limit;

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	eidx = end_pfn - PFN_DOWN(bdata->node_boot_start);
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	offset = 0;
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	if (align && (bdata->node_boot_start & (align - 1UL)) != 0)
		offset = align - (bdata->node_boot_start & (align - 1UL));
	offset = PFN_DOWN(offset);
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	/*
	 * We try to allocate bootmem pages above 'goal'
	 * first, then we try to allocate lower pages.
	 */
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	if (goal && goal >= bdata->node_boot_start && PFN_DOWN(goal) < end_pfn) {
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		preferred = goal - bdata->node_boot_start;

		if (bdata->last_success >= preferred)
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			if (!limit || (limit && limit > bdata->last_success))
				preferred = bdata->last_success;
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	} else
		preferred = 0;

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	preferred = PFN_DOWN(ALIGN(preferred, align)) + offset;
	areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
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	incr = align >> PAGE_SHIFT ? : 1;

restart_scan:
	for (i = preferred; i < eidx; i += incr) {
		unsigned long j;
		i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
		i = ALIGN(i, incr);
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		if (i >= eidx)
			break;
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		if (test_bit(i, bdata->node_bootmem_map))
			continue;
		for (j = i + 1; j < i + areasize; ++j) {
			if (j >= eidx)
				goto fail_block;
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			if (test_bit(j, bdata->node_bootmem_map))
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				goto fail_block;
		}
		start = i;
		goto found;
	fail_block:
		i = ALIGN(j, incr);
	}

	if (preferred > offset) {
		preferred = offset;
		goto restart_scan;
	}
	return NULL;

found:
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	bdata->last_success = PFN_PHYS(start);
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	BUG_ON(start >= eidx);

	/*
	 * Is the next page of the previous allocation-end the start
	 * of this allocation's buffer? If yes then we can 'merge'
	 * the previous partial page with this allocation.
	 */
	if (align < PAGE_SIZE &&
	    bdata->last_offset && bdata->last_pos+1 == start) {
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		offset = ALIGN(bdata->last_offset, align);
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		BUG_ON(offset > PAGE_SIZE);
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		remaining_size = PAGE_SIZE - offset;
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		if (size < remaining_size) {
			areasize = 0;
			/* last_pos unchanged */
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			bdata->last_offset = offset + size;
			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
					   offset +
					   bdata->node_boot_start);
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		} else {
			remaining_size = size - remaining_size;
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			areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
					   offset +
					   bdata->node_boot_start);
			bdata->last_pos = start + areasize - 1;
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			bdata->last_offset = remaining_size;
		}
		bdata->last_offset &= ~PAGE_MASK;
	} else {
		bdata->last_pos = start + areasize - 1;
		bdata->last_offset = size & ~PAGE_MASK;
		ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
	}

	/*
	 * Reserve the area now:
	 */
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	for (i = start; i < start + areasize; i++)
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		if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
			BUG();
	memset(ret, 0, size);
	return ret;
}

static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
{
	struct page *page;
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	unsigned long pfn;
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	bootmem_data_t *bdata = pgdat->bdata;
	unsigned long i, count, total = 0;
	unsigned long idx;
	unsigned long *map; 
	int gofast = 0;

	BUG_ON(!bdata->node_bootmem_map);

	count = 0;
	/* first extant page of the node */
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	pfn = PFN_DOWN(bdata->node_boot_start);
	idx = bdata->node_low_pfn - pfn;
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	map = bdata->node_bootmem_map;
	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
	if (bdata->node_boot_start == 0 ||
	    ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
		gofast = 1;
	for (i = 0; i < idx; ) {
		unsigned long v = ~map[i / BITS_PER_LONG];
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		if (gofast && v == ~0UL) {
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			int order;
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			page = pfn_to_page(pfn);
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			count += BITS_PER_LONG;
			order = ffs(BITS_PER_LONG) - 1;
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			__free_pages_bootmem(page, order);
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			i += BITS_PER_LONG;
			page += BITS_PER_LONG;
		} else if (v) {
			unsigned long m;
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			page = pfn_to_page(pfn);
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			for (m = 1; m && i < idx; m<<=1, page++, i++) {
				if (v & m) {
					count++;
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					__free_pages_bootmem(page, 0);
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				}
			}
		} else {
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			i += BITS_PER_LONG;
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		}
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		pfn += BITS_PER_LONG;
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	}
	total += count;

	/*
	 * Now free the allocator bitmap itself, it's not
	 * needed anymore:
	 */
	page = virt_to_page(bdata->node_bootmem_map);
	count = 0;
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	idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
	for (i = 0; i < idx; i++, page++) {
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		__free_pages_bootmem(page, 0);
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		count++;
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	}
	total += count;
	bdata->node_bootmem_map = NULL;

	return total;
}

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unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
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				unsigned long startpfn, unsigned long endpfn)
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{
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	return init_bootmem_core(pgdat, freepfn, startpfn, endpfn);
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}

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void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
				 unsigned long size)
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{
	reserve_bootmem_core(pgdat->bdata, physaddr, size);
}

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void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
			      unsigned long size)
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{
	free_bootmem_core(pgdat->bdata, physaddr, size);
}

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unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
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{
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	return free_all_bootmem_core(pgdat);
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}

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unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
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{
	max_low_pfn = pages;
	min_low_pfn = start;
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	return init_bootmem_core(NODE_DATA(0), start, 0, pages);
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}

#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
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void __init reserve_bootmem(unsigned long addr, unsigned long size)
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{
	reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
}
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */

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void __init free_bootmem(unsigned long addr, unsigned long size)
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{
	free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
}

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unsigned long __init free_all_bootmem(void)
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{
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	return free_all_bootmem_core(NODE_DATA(0));
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}

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void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
				      unsigned long goal)
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{
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	bootmem_data_t *bdata;
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	void *ptr;

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	list_for_each_entry(bdata, &bdata_list, list) {
		ptr = __alloc_bootmem_core(bdata, size, align, goal, 0);
		if (ptr)
			return ptr;
	}
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	return NULL;
}
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void * __init __alloc_bootmem(unsigned long size, unsigned long align,
			      unsigned long goal)
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{
	void *mem = __alloc_bootmem_nopanic(size,align,goal);
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	if (mem)
		return mem;
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	/*
	 * Whoops, we cannot satisfy the allocation request.
	 */
	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
	panic("Out of memory");
	return NULL;
}

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void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
				   unsigned long align, unsigned long goal)
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{
	void *ptr;

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	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);
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	if (ptr)
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		return ptr;
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	return __alloc_bootmem(size, align, goal);
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}

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#define LOW32LIMIT 0xffffffff

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void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
				  unsigned long goal)
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{
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	bootmem_data_t *bdata;
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	void *ptr;

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	list_for_each_entry(bdata, &bdata_list, list) {
		ptr = __alloc_bootmem_core(bdata, size, align, goal, LOW32LIMIT);
		if (ptr)
			return ptr;
	}
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	/*
	 * Whoops, we cannot satisfy the allocation request.
	 */
	printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!\n", size);
	panic("Out of low memory");
	return NULL;
}

void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
				       unsigned long align, unsigned long goal)
{
	return __alloc_bootmem_core(pgdat->bdata, size, align, goal, LOW32LIMIT);
}