text: /*
   *  linux/mm/page_alloc.c
   *
   *  Manages the free list, the system allocates free pages here.
   *  Note that kmalloc() lives in slab.c
   *
   *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   *  Swap reorganised 29.12.95, Stephen Tweedie
   *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
   *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
   *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
   *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
   *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
   */
  
  #include <linux/stddef.h>
  #include <linux/mm.h>
  #include <linux/swap.h>
  #include <linux/interrupt.h>
  #include <linux/pagemap.h>
  #include <linux/bootmem.h>
  #include <linux/compiler.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/suspend.h>
  #include <linux/pagevec.h>
  #include <linux/blkdev.h>
  #include <linux/slab.h>
  #include <linux/notifier.h>
  #include <linux/topology.h>
  #include <linux/sysctl.h>
  #include <linux/cpu.h>
  #include <linux/cpuset.h>
  #include <linux/memory_hotplug.h>
  #include <linux/nodemask.h>
  #include <linux/vmalloc.h>
  #include <linux/mempolicy.h>
  #include <linux/stop_machine.h>
  #include <linux/sort.h>
  #include <linux/pfn.h>
  #include <linux/backing-dev.h>
  #include <linux/fault-inject.h>
  
  #include <asm/tlbflush.h>
  #include <asm/div64.h>
  #include "internal.h"
  
  /*
   * MCD - HACK: Find somewhere to initialize this EARLY, or make this
   * initializer cleaner
   */
  nodemask_t node_online_map __read_mostly = { { [0] = 1UL } };
  EXPORT_SYMBOL(node_online_map);
  nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
  EXPORT_SYMBOL(node_possible_map);
  unsigned long totalram_pages __read_mostly;
  unsigned long totalreserve_pages __read_mostly;
  long nr_swap_pages;
  int percpu_pagelist_fraction;
  
  static void __free_pages_ok(struct page *page, unsigned int order);
  
  /*
   * results with 256, 32 in the lowmem_reserve sysctl:
   *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
   *	1G machine -> (16M dma, 784M normal, 224M high)
   *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
   *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
   *	HIGHMEM allocation will (224M+784M)/256 of ram reserved in ZONE_DMA
   *
   * TBD: should special case ZONE_DMA32 machines here - in those we normally
   * don't need any ZONE_NORMAL reservation
   */
  int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
  #ifdef CONFIG_ZONE_DMA
  	 256,
  #endif
  #ifdef CONFIG_ZONE_DMA32
  	 256,
  #endif
  #ifdef CONFIG_HIGHMEM
  	 32
  #endif
  };
  
  EXPORT_SYMBOL(totalram_pages);
  
  static char * const zone_names[MAX_NR_ZONES] = {
  #ifdef CONFIG_ZONE_DMA
  	 "DMA",
  #endif
  #ifdef CONFIG_ZONE_DMA32
  	 "DMA32",
  #endif
  	 "Normal",
  #ifdef CONFIG_HIGHMEM
  	 "HighMem"
  #endif
  };
  
  int min_free_kbytes = 1024;
  
  unsigned long __meminitdata nr_kernel_pages;
  unsigned long __meminitdata nr_all_pages;
  static unsigned long __initdata dma_reserve;
  
  #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
    /*
     * MAX_ACTIVE_REGIONS determines the maxmimum number of distinct
     * ranges of memory (RAM) that may be registered with add_active_range().
     * Ranges passed to add_active_range() will be merged if possible
     * so the number of times add_active_range() can be called is
     * related to the number of nodes and the number of holes
     */
    #ifdef CONFIG_MAX_ACTIVE_REGIONS
      /* Allow an architecture to set MAX_ACTIVE_REGIONS to save memory */
      #define MAX_ACTIVE_REGIONS CONFIG_MAX_ACTIVE_REGIONS
    #else
      #if MAX_NUMNODES >= 32
        /* If there can be many nodes, allow up to 50 holes per node */
        #define MAX_ACTIVE_REGIONS (MAX_NUMNODES*50)
      #else
        /* By default, allow up to 256 distinct regions */
        #define MAX_ACTIVE_REGIONS 256
      #endif
    #endif
  
    struct node_active_region __initdata early_node_map[MAX_ACTIVE_REGIONS];
    int __initdata nr_nodemap_entries;
    unsigned long __initdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
    unsigned long __initdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
  #ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
    unsigned long __initdata node_boundary_start_pfn[MAX_NUMNODES];
    unsigned long __initdata node_boundary_end_pfn[MAX_NUMNODES];
  #endif /* CONFIG_MEMORY_HOTPLUG_RESERVE */
  #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
  
  #ifdef CONFIG_DEBUG_VM
  static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
  {
  	int ret = 0;
  	unsigned seq;
  	unsigned long pfn = page_to_pfn(page);
  
  	do {
  		seq = zone_span_seqbegin(zone);
  		if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
  			ret = 1;
  		else if (pfn < zone->zone_start_pfn)
  			ret = 1;
  	} while (zone_span_seqretry(zone, seq));
  
  	return ret;
  }
  
  static int page_is_consistent(struct zone *zone, struct page *page)
  {
  #ifdef CONFIG_HOLES_IN_ZONE
  	if (!pfn_valid(page_to_pfn(page)))
  		return 0;
  #endif
  	if (zone != page_zone(page))
  		return 0;
  
  	return 1;
  }
  /*
   * Temporary debugging check for pages not lying within a given zone.
   */
  static int bad_range(struct zone *zone, struct page *page)
  {
  	if (page_outside_zone_boundaries(zone, page))
  		return 1;
  	if (!page_is_consistent(zone, page))
  		return 1;
  
  	return 0;
  }
  #else
  static inline int bad_range(struct zone *zone, struct page *page)
  {
  	return 0;
  }
  #endif
  
  static void bad_page(struct page *page)
  {
  	printk(KERN_EMERG "Bad page state in process '%s'\n"
  		KERN_EMERG "page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n"
  		KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
  		KERN_EMERG "Backtrace:\n",
  		current->comm, page, (int)(2*sizeof(unsigned long)),
  		(unsigned long)page->flags, page->mapping,
  		page_mapcount(page), page_count(page));
  	dump_stack();
  	page->flags &= ~(1 << PG_lru	|
  			1 << PG_private |
  			1 << PG_locked	|
  			1 << PG_active	|
  			1 << PG_dirty	|
  			1 << PG_reclaim |
  			1 << PG_slab    |
  			1 << PG_swapcache |
  			1 << PG_writeback |
  			1 << PG_buddy );
  	set_page_count(page, 0);
  	reset_page_mapcount(page);
  	page->mapping = NULL;
  	add_taint(TAINT_BAD_PAGE);
  }
  
  /*
   * Higher-order pages are called "compound pages".  They are structured thusly:
   *
   * The first PAGE_SIZE page is called the "head page".
   *
   * The remaining PAGE_SIZE pages are called "tail pages".
   *
   * All pages have PG_compound set.  All pages have their ->private pointing at
   * the head page (even the head page has this).
   *
   * The first tail page's ->lru.next holds the address of the compound page's
   * put_page() function.  Its ->lru.prev holds the order of allocation.
   * This usage means that zero-order pages may not be compound.
   */
  
  static void free_compound_page(struct page *page)
  {
  	__free_pages_ok(page, (unsigned long)page[1].lru.prev);
  }
  
  static void prep_compound_page(struct page *page, unsigned long order)
  {
  	int i;
  	int nr_pages = 1 << order;
  
  	set_compound_page_dtor(page, free_compound_page);
  	page[1].lru.prev = (void *)order;
  	for (i = 0; i < nr_pages; i++) {
  		struct page *p = page + i;
  
  		__SetPageCompound(p);
  		set_page_private(p, (unsigned long)page);
  	}
  }
  
  static void destroy_compound_page(struct page *page, unsigned long order)
  {
  	int i;
  	int nr_pages = 1 << order;
  
  	if (unlikely((unsigned long)page[1].lru.prev != order))
  		bad_page(page);
  
  	for (i = 0; i < nr_pages; i++) {
  		struct page *p = page + i;
  
  		if (unlikely(!PageCompound(p) |
  				(page_private(p) != (unsigned long)page)))
  			bad_page(page);
  		__ClearPageCompound(p);
  	}
  }
  
  static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
  {
  	int i;
  
  	VM_BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
  	/*
  	 * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
  	 * and __GFP_HIGHMEM from hard or soft interrupt context.
  	 */
  	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
  	for (i = 0; i < (1 << order); i++)
  		clear_highpage(page + i);
  }
  
  /*
   * function for dealing with page's order in buddy system.
   * zone->lock is already acquired when we use these.
   * So, we don't need atomic page->flags operations here.
   */
  static inline unsigned long page_order(struct page *page)
  {
  	return page_private(page);
  }
  
  static inline void set_page_order(struct page *page, int order)
  {
  	set_page_private(page, order);
  	__SetPageBuddy(page);
  }
  
  static inline void rmv_page_order(struct page *page)
  {
  	__ClearPageBuddy(page);
  	set_page_private(page, 0);
  }
  
  /*
   * Locate the struct page for both the matching buddy in our
   * pair (buddy1) and the combined O(n+1) page they form (page).
   *
   * 1) Any buddy B1 will have an order O twin B2 which satisfies
   * the following equation:
   *     B2 = B1 ^ (1 << O)
   * For example, if the starting buddy (buddy2) is #8 its order
   * 1 buddy is #10:
   *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
   *
   * 2) Any buddy B will have an order O+1 parent P which
   * satisfies the following equation:
   *     P = B & ~(1 << O)
   *
   * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
   */
  static inline struct page *
  __page_find_buddy(struct page *page, unsigned long page_idx, unsigned int order)
  {
  	unsigned long buddy_idx = page_idx ^ (1 << order);
  
  	return page + (buddy_idx - page_idx);
  }
  
  static inline unsigned long
  __find_combined_index(unsigned long page_idx, unsigned int order)
  {
  	return (page_idx & ~(1 << order));
  }
  
  /*
   * This function checks whether a page is free && is the buddy
   * we can do coalesce a page and its buddy if
   * (a) the buddy is not in a hole &&
   * (b) the buddy is in the buddy system &&
   * (c) a page and its buddy have the same order &&
   * (d) a page and its buddy are in the same zone.
   *
   * For recording whether a page is in the buddy system, we use PG_buddy.
   * Setting, clearing, and testing PG_buddy is serialized by zone->lock.
   *
   * For recording page's order, we use page_private(page).
   */
  static inline int page_is_buddy(struct page *page, struct page *buddy,
  								int order)
  {
  #ifdef CONFIG_HOLES_IN_ZONE
  	if (!pfn_valid(page_to_pfn(buddy)))
  		return 0;
  #endif
  
  	if (page_zone_id(page) != page_zone_id(buddy))
  		return 0;
  
  	if (PageBuddy(buddy) && page_order(buddy) == order) {
  		BUG_ON(page_count(buddy) != 0);
  		return 1;
  	}
  	return 0;
  }
  
  /*
   * Freeing function for a buddy system allocator.
   *
   * The concept of a buddy system is to maintain direct-mapped table
   * (containing bit values) for memory blocks of various "orders".
   * The bottom level table contains the map for the smallest allocatable
   * units of memory (here, pages), and each level above it describes
   * pairs of units from the levels below, hence, "buddies".
   * At a high level, all that happens here is marking the table entry
   * at the bottom level available, and propagating the changes upward
   * as necessary, plus some accounting needed to play nicely with other
   * parts of the VM system.
   * At each level, we keep a list of pages, which are heads of continuous
   * free pages of length of (1 << order) and marked with PG_buddy. Page's
   * order is recorded in page_private(page) field.
   * So when we are allocating or freeing one, we can derive the state of the
   * other.  That is, if we allocate a small block, and both were   
   * free, the remainder of the region must be split into blocks.   
   * If a block is freed, and its buddy is also free, then this
   * triggers coalescing into a block of larger size.            
   *
   * -- wli
   */
  
  static inline void __free_one_page(struct page *page,
  		struct zone *zone, unsigned int order)
  {
  	unsigned long page_idx;
  	int order_size = 1 << order;
  
  	if (unlikely(PageCompound(page)))
  		destroy_compound_page(page, order);
  
  	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
  
  	VM_BUG_ON(page_idx & (order_size - 1));
  	VM_BUG_ON(bad_range(zone, page));
  
  	__mod_zone_page_state(zone, NR_FREE_PAGES, order_size);
  	while (order < MAX_ORDER-1) {
  		unsigned long combined_idx;
  		struct free_area *area;
  		struct page *buddy;
  
  		buddy = __page_find_buddy(page, page_idx, order);
  		if (!page_is_buddy(page, buddy, order))
  			break;		/* Move the buddy up one level. */
  
  		list_del(&buddy->lru);
  		area = zone->free_area + order;
  		area->nr_free--;
  		rmv_page_order(buddy);
  		combined_idx = __find_combined_index(page_idx, order);
  		page = page + (combined_idx - page_idx);
  		page_idx = combined_idx;
  		order++;
  	}
  	set_page_order(page, order);
  	list_add(&page->lru, &zone->free_area[order].free_list);
  	zone->free_area[order].nr_free++;
  }
  
  static inline int free_pages_check(struct page *page)
  {
  	if (unlikely(page_mapcount(page) |
  		(page->mapping != NULL)  |
  		(page_count(page) != 0)  |
  		(page->flags & (
  			1 << PG_lru	|
  			1 << PG_private |
  			1 << PG_locked	|
  			1 << PG_active	|
  			1 << PG_reclaim	|
  			1 << PG_slab	|
  			1 << PG_swapcache |
  			1 << PG_writeback |
  			1 << PG_reserved |
  			1 << PG_buddy ))))
  		bad_page(page);
  	if (PageDirty(page))
  		__ClearPageDirty(page);
  	/*
  	 * For now, we report if PG_reserved was found set, but do not
  	 * clear it, and do not free the page.  But we shall soon need
  	 * to do more, for when the ZERO_PAGE count wraps negative.
  	 */
  	return PageReserved(page);
  }
  
  /*
   * Frees a list of pages. 
   * Assumes all pages on list are in same zone, and of same order.
   * count is the number of pages to free.
   *
   * If the zone was previously in an "all pages pinned" state then look to
   * see if this freeing clears that state.
   *
   * And clear the zone's pages_scanned counter, to hold off the "all pages are
   * pinned" detection logic.
   */
  static void free_pages_bulk(struct zone *zone, int count,
  					struct list_head *list, int order)
  {
  	spin_lock(&zone->lock);
  	zone->all_unreclaimable = 0;
  	zone->pages_scanned = 0;
  	while (count--) {
  		struct page *page;
  
  		VM_BUG_ON(list_empty(list));
  		page = list_entry(list->prev, struct page, lru);
  		/* have to delete it as __free_one_page list manipulates */
  		list_del(&page->lru);
  		__free_one_page(page, zone, order);
  	}
  	spin_unlock(&zone->lock);
  }
  
  static void free_one_page(struct zone *zone, struct page *page, int order)
  {
  	spin_lock(&zone->lock);
  	zone->all_unreclaimable = 0;
  	zone->pages_scanned = 0;
  	__free_one_page(page, zone, order);
  	spin_unlock(&zone->lock);
  }
  
  static void __free_pages_ok(struct page *page, unsigned int order)
  {
  	unsigned long flags;
  	int i;
  	int reserved = 0;
  
  	for (i = 0 ; i < (1 << order) ; ++i)
  		reserved += free_pages_check(page + i);
  	if (reserved)
  		return;
  
  	if (!PageHighMem(page))
  		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
  	arch_free_page(page, order);
  	kernel_map_pages(page, 1 << order, 0);
  
  	local_irq_save(flags);
  	__count_vm_events(PGFREE, 1 << order);
  	free_one_page(page_zone(page), page, order);
  	local_irq_restore(flags);
  }
  
  /*
   * permit the bootmem allocator to evade page validation on high-order frees
   */
  void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
  {
  	if (order == 0) {
  		__ClearPageReserved(page);
  		set_page_count(page, 0);
  		set_page_refcounted(page);
  		__free_page(page);
  	} else {
  		int loop;
  
  		prefetchw(page);
  		for (loop = 0; loop < BITS_PER_LONG; loop++) {
  			struct page *p = &page[loop];
  
  			if (loop + 1 < BITS_PER_LONG)
  				prefetchw(p + 1);
  			__ClearPageReserved(p);
  			set_page_count(p, 0);
  		}
  
  		set_page_refcounted(page);
  		__free_pages(page, order);
  	}
  }
  
  
  /*
   * The order of subdivision here is critical for the IO subsystem.
   * Please do not alter this order without good reasons and regression
   * testing. Specifically, as large blocks of memory are subdivided,
   * the order in which smaller blocks are delivered depends on the order
   * they're subdivided in this function. This is the primary factor
   * influencing the order in which pages are delivered to the IO
   * subsystem according to empirical testing, and this is also justified
   * by considering the behavior of a buddy system containing a single
   * large block of memory acted on by a series of small allocations.
   * This behavior is a critical factor in sglist merging's success.
   *
   * -- wli
   */
  static inline void expand(struct zone *zone, struct page *page,
   	int low, int high, struct free_area *area)
  {
  	unsigned long size = 1 << high;
  
  	while (high > low) {
  		area--;
  		high--;
  		size >>= 1;
  		VM_BUG_ON(bad_range(zone, &page[size]));
  		list_add(&page[size].lru, &area->free_list);
  		area->nr_free++;
  		set_page_order(&page[size], high);
  	}
  }
  
  /*
   * This page is about to be returned from the page allocator
   */
  static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
  {
  	if (unlikely(page_mapcount(page) |
  		(page->mapping != NULL)  |
  		(page_count(page) != 0)  |
  		(page->flags & (
  			1 << PG_lru	|
  			1 << PG_private	|
  			1 << PG_locked	|
  			1 << PG_active	|
  			1 << PG_dirty	|
  			1 << PG_reclaim	|
  			1 << PG_slab    |
  			1 << PG_swapcache |
  			1 << PG_writeback |
  			1 << PG_reserved |
  			1 << PG_buddy ))))
  		bad_page(page);
  
  	/*
  	 * For now, we report if PG_reserved was found set, but do not
  	 * clear it, and do not allocate the page: as a safety net.
  	 */
  	if (PageReserved(page))
  		return 1;
  
  	page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
  			1 << PG_referenced | 1 << PG_arch_1 |
  			1 << PG_owner_priv_1 | 1 << PG_mappedtodisk);
  	set_page_private(page, 0);
  	set_page_refcounted(page);
  
  	arch_alloc_page(page, order);
  	kernel_map_pages(page, 1 << order, 1);
  
  	if (gfp_flags & __GFP_ZERO)
  		prep_zero_page(page, order, gfp_flags);
  
  	if (order && (gfp_flags & __GFP_COMP))
  		prep_compound_page(page, order);
  
  	return 0;
  }
  
  /* 
   * Do the hard work of removing an element from the buddy allocator.
   * Call me with the zone->lock already held.
   */
  static struct page *__rmqueue(struct zone *zone, unsigned int order)
  {
  	struct free_area * area;
  	unsigned int current_order;
  	struct page *page;
  
  	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
  		area = zone->free_area + current_order;
  		if (list_empty(&area->free_list))
  			continue;
  
  		page = list_entry(area->free_list.next, struct page, lru);
  		list_del(&page->lru);
  		rmv_page_order(page);
  		area->nr_free--;
  		__mod_zone_page_state(zone, NR_FREE_PAGES, - (1UL << order));
  		expand(zone, page, order, current_order, area);
  		return page;
  	}
  
  	return NULL;
  }
  
  /* 
   * Obtain a specified number of elements from the buddy allocator, all under
   * a single hold of the lock, for efficiency.  Add them to the supplied list.
   * Returns the number of new pages which were placed at *list.
   */
  static int rmqueue_bulk(struct zone *zone, unsigned int order, 
  			unsigned long count, struct list_head *list)
  {
  	int i;
  	
  	spin_lock(&zone->lock);
  	for (i = 0; i < count; ++i) {
  		struct page *page = __rmqueue(zone, order);
  		if (unlikely(page == NULL))
  			break;
  		list_add_tail(&page->lru, list);
  	}
  	spin_unlock(&zone->lock);
  	return i;
  }
  
  #if MAX_NUMNODES > 1
  int nr_node_ids __read_mostly;
  EXPORT_SYMBOL(nr_node_ids);
  
  /*
   * Figure out the number of possible node ids.
   */
  static void __init setup_nr_node_ids(void)
  {
  	unsigned int node;
  	unsigned int highest = 0;
  
  	for_each_node_mask(node, node_possible_map)
  		highest = node;
  	nr_node_ids = highest + 1;
  }
  #else
  static void __init setup_nr_node_ids(void) {}
  #endif
  
  #ifdef CONFIG_NUMA
  /*
   * Called from the slab reaper to drain pagesets on a particular node that
   * belongs to the currently executing processor.
   * Note that this function must be called with the thread pinned to
   * a single processor.
   */
  void drain_node_pages(int nodeid)
  {
  	int i;
  	enum zone_type z;
  	unsigned long flags;
  
  	for (z = 0; z < MAX_NR_ZONES; z++) {
  		struct zone *zone = NODE_DATA(nodeid)->node_zones + z;
  		struct per_cpu_pageset *pset;
  
  		if (!populated_zone(zone))
  			continue;
  
  		pset = zone_pcp(zone, smp_processor_id());
  		for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
  			struct per_cpu_pages *pcp;
  
  			pcp = &pset->pcp[i];
  			if (pcp->count) {
  				int to_drain;
  
  				local_irq_save(flags);
  				if (pcp->count >= pcp->batch)
  					to_drain = pcp->batch;
  				else
  					to_drain = pcp->count;
  				free_pages_bulk(zone, to_drain, &pcp->list, 0);
  				pcp->count -= to_drain;
  				local_irq_restore(flags);
  			}
  		}
  	}
  }
  #endif
  
  static void __drain_pages(unsigned int cpu)
  {
  	unsigned long flags;
  	struct zone *zone;
  	int i;
  
  	for_each_zone(zone) {
  		struct per_cpu_pageset *pset;
  
  		if (!populated_zone(zone))
  			continue;
  
  		pset = zone_pcp(zone, cpu);
  		for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
  			struct per_cpu_pages *pcp;
  
  			pcp = &pset->pcp[i];
  			local_irq_save(flags);
  			free_pages_bulk(zone, pcp->count, &pcp->list, 0);
  			pcp->count = 0;
  			local_irq_restore(flags);
  		}
  	}
  }
  
  #ifdef CONFIG_PM
  
  void mark_free_pages(struct zone *zone)
  {
  	unsigned long pfn, max_zone_pfn;
  	unsigned long flags;
  	int order;
  	struct list_head *curr;
  
  	if (!zone->spanned_pages)
  		return;
  
  	spin_lock_irqsave(&zone->lock, flags);
  
  	max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
  	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
  		if (pfn_valid(pfn)) {
  			struct page *page = pfn_to_page(pfn);
  
  			if (!PageNosave(page))
  				ClearPageNosaveFree(page);
  		}
  
  	for (order = MAX_ORDER - 1; order >= 0; --order)
  		list_for_each(curr, &zone->free_area[order].free_list) {
  			unsigned long i;
  
  			pfn = page_to_pfn(list_entry(curr, struct page, lru));
  			for (i = 0; i < (1UL << order); i++)
  				SetPageNosaveFree(pfn_to_page(pfn + i));
  		}
  
  	spin_unlock_irqrestore(&zone->lock, flags);
  }
  
  /*
   * Spill all of this CPU's per-cpu pages back into the buddy allocator.
   */
  void drain_local_pages(void)
  {
  	unsigned long flags;
  
  	local_irq_save(flags);	
  	__drain_pages(smp_processor_id());
  	local_irq_restore(flags);	
  }
  #endif /* CONFIG_PM */
  
  /*
   * Free a 0-order page
   */
  static void fastcall free_hot_cold_page(struct page *page, int cold)
  {
  	struct zone *zone = page_zone(page);
  	struct per_cpu_pages *pcp;
  	unsigned long flags;
  
  	if (PageAnon(page))
  		page->mapping = NULL;
  	if (free_pages_check(page))
  		return;
  
  	if (!PageHighMem(page))
  		debug_check_no_locks_freed(page_address(page), PAGE_SIZE);
  	arch_free_page(page, 0);
  	kernel_map_pages(page, 1, 0);
  
  	pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
  	local_irq_save(flags);
  	__count_vm_event(PGFREE);
  	list_add(&page->lru, &pcp->list);
  	pcp->count++;
  	if (pcp->count >= pcp->high) {
  		free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
  		pcp->count -= pcp->batch;
  	}
  	local_irq_restore(flags);
  	put_cpu();
  }
  
  void fastcall free_hot_page(struct page *page)
  {
  	free_hot_cold_page(page, 0);
  }
  	
  void fastcall free_cold_page(struct page *page)
  {
  	free_hot_cold_page(page, 1);
  }
  
  /*
   * split_page takes a non-compound higher-order page, and splits it into
   * n (1<<order) sub-pages: page[0..n]
   * Each sub-page must be freed individually.
   *
   * Note: this is probably too low level an operation for use in drivers.
   * Please consult with lkml before using this in your driver.
   */
  void split_page(struct page *page, unsigned int order)
  {
  	int i;
  
  	VM_BUG_ON(PageCompound(page));
  	VM_BUG_ON(!page_count(page));
  	for (i = 1; i < (1 << order); i++)
  		set_page_refcounted(page + i);
  }
  
  /*
   * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
   * we cheat by calling it from here, in the order > 0 path.  Saves a branch
   * or two.
   */
  static struct page *buffered_rmqueue(struct zonelist *zonelist,
  			struct zone *zone, int order, gfp_t gfp_flags)
  {
  	unsigned long flags;
  	struct page *page;
  	int cold = !!(gfp_flags & __GFP_COLD);
  	int cpu;
  
  again:
  	cpu  = get_cpu();
  	if (likely(order == 0)) {
  		struct per_cpu_pages *pcp;
  
  		pcp = &zone_pcp(zone, cpu)->pcp[cold];
  		local_irq_save(flags);
  		if (!pcp->count) {
  			pcp->count = rmqueue_bulk(zone, 0,
  						pcp->batch, &pcp->list);
  			if (unlikely(!pcp->count))
  				goto failed;
  		}
  		page = list_entry(pcp->list.next, struct page, lru);
  		list_del(&page->lru);
  		pcp->count--;
  	} else {
  		spin_lock_irqsave(&zone->lock, flags);
  		page = __rmqueue(zone, order);
  		spin_unlock(&zone->lock);
  		if (!page)
  			goto failed;
  	}
  
  	__count_zone_vm_events(PGALLOC, zone, 1 << order);
  	zone_statistics(zonelist, zone);
  	local_irq_restore(flags);
  	put_cpu();
  
  	VM_BUG_ON(bad_range(zone, page));
  	if (prep_new_page(page, order, gfp_flags))
  		goto again;
  	return page;
  
  failed:
  	local_irq_restore(flags);
  	put_cpu();
  	return NULL;
  }
  
  #define ALLOC_NO_WATERMARKS	0x01 /* don't check watermarks at all */
  #define ALLOC_WMARK_MIN		0x02 /* use pages_min watermark */
  #define ALLOC_WMARK_LOW		0x04 /* use pages_low watermark */
  #define ALLOC_WMARK_HIGH	0x08 /* use pages_high watermark */
  #define ALLOC_HARDER		0x10 /* try to alloc harder */
  #define ALLOC_HIGH		0x20 /* __GFP_HIGH set */
  #define ALLOC_CPUSET		0x40 /* check for correct cpuset */
  
  #ifdef CONFIG_FAIL_PAGE_ALLOC
  
  static struct fail_page_alloc_attr {
  	struct fault_attr attr;
  
  	u32 ignore_gfp_highmem;
  	u32 ignore_gfp_wait;
  
  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
  
  	struct dentry *ignore_gfp_highmem_file;
  	struct dentry *ignore_gfp_wait_file;
  
  #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
  
  } fail_page_alloc = {
  	.attr = FAULT_ATTR_INITIALIZER,
  	.ignore_gfp_wait = 1,
  	.ignore_gfp_highmem = 1,
  };
  
  static int __init setup_fail_page_alloc(char *str)
  {
  	return setup_fault_attr(&fail_page_alloc.attr, str);
  }
  __setup("fail_page_alloc=", setup_fail_page_alloc);
  
  static int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
  {
  	if (gfp_mask & __GFP_NOFAIL)
  		return 0;
  	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
  		return 0;
  	if (fail_page_alloc.ignore_gfp_wait && (gfp_mask & __GFP_WAIT))
  		return 0;
  
  	return should_fail(&fail_page_alloc.attr, 1 << order);
  }
  
  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
  
  static int __init fail_page_alloc_debugfs(void)
  {
  	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
  	struct dentry *dir;
  	int err;
  
  	err = init_fault_attr_dentries(&fail_page_alloc.attr,
  				       "fail_page_alloc");
  	if (err)
  		return err;
  	dir = fail_page_alloc.attr.dentries.dir;
  
  	fail_page_alloc.ignore_gfp_wait_file =
  		debugfs_create_bool("ignore-gfp-wait", mode, dir,
  				      &fail_page_alloc.ignore_gfp_wait);
  
  	fail_page_alloc.ignore_gfp_highmem_file =
  		debugfs_create_bool("ignore-gfp-highmem", mode, dir,
  				      &fail_page_alloc.ignore_gfp_highmem);
  
  	if (!fail_page_alloc.ignore_gfp_wait_file ||
  			!fail_page_alloc.ignore_gfp_highmem_file) {
  		err = -ENOMEM;
  		debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
  		debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
  		cleanup_fault_attr_dentries(&fail_page_alloc.attr);
  	}
  
  	return err;
  }
  
  late_initcall(fail_page_alloc_debugfs);
  
  #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
  
  #else /* CONFIG_FAIL_PAGE_ALLOC */
  
  static inline int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
  {
  	return 0;
  }
  
  #endif /* CONFIG_FAIL_PAGE_ALLOC */
  
  /*
   * Return 1 if free pages are above 'mark'. This takes into account the order
   * of the allocation.
   */
  int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
  		      int classzone_idx, int alloc_flags)
  {
  	/* free_pages my go negative - that's OK */
  	long min = mark;
  	long free_pages = zone_page_state(z, NR_FREE_PAGES) - (1 << order) + 1;
  	int o;
  
  	if (alloc_flags & ALLOC_HIGH)
  		min -= min / 2;
  	if (alloc_flags & ALLOC_HARDER)
  		min -= min / 4;
  
  	if (free_pages <= min + z->lowmem_reserve[classzone_idx])
  		return 0;
  	for (o = 0; o < order; o++) {
  		/* At the next order, this order's pages become unavailable */
  		free_pages -= z->free_area[o].nr_free << o;
  
  		/* Require fewer higher order pages to be free */
  		min >>= 1;
  
  		if (free_pages <= min)
  			return 0;
  	}
  	return 1;
  }
  
  #ifdef CONFIG_NUMA
  /*
   * zlc_setup - Setup for "zonelist cache".  Uses cached zone data to
   * skip over zones that are not allowed by the cpuset, or that have
   * been recently (in last second) found to be nearly full.  See further
   * comments in mmzone.h.  Reduces cache footprint of zonelist scans
   * that have to skip over alot of full or unallowed zones.
   *
   * If the zonelist cache is present in the passed in zonelist, then
   * returns a pointer to the allowed node mask (either the current
   * tasks mems_allowed, or node_online_map.)
   *
   * If the zonelist cache is not available for this zonelist, does
   * nothing and returns NULL.
   *
   * If the fullzones BITMAP in the zonelist cache is stale (more than
   * a second since last zap'd) then we zap it out (clear its bits.)
   *
   * We hold off even calling zlc_setup, until after we've checked the
   * first zone in the zonelist, on the theory that most allocations will
   * be satisfied from that first zone, so best to examine that zone as
   * quickly as we can.
   */
  static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
  {
  	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
  	nodemask_t *allowednodes;	/* zonelist_cache approximation */
  
  	zlc = zonelist->zlcache_ptr;
  	if (!zlc)
  		return NULL;
  
  	if (jiffies - zlc->last_full_zap > 1 * HZ) {
  		bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
  		zlc->last_full_zap = jiffies;
  	}
  
  	allowednodes = !in_interrupt() && (alloc_flags & ALLOC_CPUSET) ?
  					&cpuset_current_mems_allowed :
  					&node_online_map;
  	return allowednodes;
  }
  
  /*
   * Given 'z' scanning a zonelist, run a couple of quick checks to see
   * if it is worth looking at further for free memory:
   *  1) Check that the zone isn't thought to be full (doesn't have its
   *     bit set in the zonelist_cache fullzones BITMAP).
   *  2) Check that the zones node (obtained from the zonelist_cache
   *     z_to_n[] mapping) is allowed in the passed in allowednodes mask.
   * Return true (non-zero) if zone is worth looking at further, or
   * else return false (zero) if it is not.
   *
   * This check -ignores- the distinction between various watermarks,
   * such as GFP_HIGH, GFP_ATOMIC, PF_MEMALLOC, ...  If a zone is
   * found to be full for any variation of these watermarks, it will
   * be considered full for up to one second by all requests, unless
   * we are so low on memory on all allowed nodes that we are forced
   * into the second scan of the zonelist.
   *
   * In the second scan we ignore this zonelist cache and exactly
   * apply the watermarks to all zones, even it is slower to do so.
   * We are low on memory in the second scan, and should leave no stone
   * unturned looking for a free page.
   */
  static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
  						nodemask_t *allowednodes)
  {
  	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
  	int i;				/* index of *z in zonelist zones */
  	int n;				/* node that zone *z is on */
  
  	zlc = zonelist->zlcache_ptr;
  	if (!zlc)
  		return 1;
  
  	i = z - zonelist->zones;
  	n = zlc->z_to_n[i];
  
  	/* This zone is worth trying if it is allowed but not full */
  	return node_isset(n, *allowednodes) && !test_bit(i, zlc->fullzones);
  }
  
  /*
   * Given 'z' scanning a zonelist, set the corresponding bit in
   * zlc->fullzones, so that subsequent attempts to allocate a page
   * from that zone don't waste time re-examining it.
   */
  static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
  {
  	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
  	int i;				/* index of *z in zonelist zones */
  
  	zlc = zonelist->zlcache_ptr;
  	if (!zlc)
  		return;
  
  	i = z - zonelist->zones;
  
  	set_bit(i, zlc->fullzones);
  }
  
  #else	/* CONFIG_NUMA */
  
  static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
  {
  	return NULL;
  }
  
  static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
  				nodemask_t *allowednodes)
  {
  	return 1;
  }
  
  static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
  {
  }
  #endif	/* CONFIG_NUMA */
  
  /*
   * get_page_from_freelist goes through the zonelist trying to allocate
   * a page.
   */
  static struct page *
  get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
  		struct zonelist *zonelist, int alloc_flags)
  {
  	struct zone **z;
  	struct page *page = NULL;
  	int classzone_idx = zone_idx(zonelist->zones[0]);
  	struct zone *zone;
  	nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
  	int zlc_active = 0;		/* set if using zonelist_cache */
  	int did_zlc_setup = 0;		/* just call zlc_setup() one time */
  
  zonelist_scan:
  	/*
  	 * Scan zonelist, looking for a zone with enough free.
  	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
  	 */
  	z = zonelist->zones;
  
  	do {
  		if (NUMA_BUILD && zlc_active &&
  			!zlc_zone_worth_trying(zonelist, z, allowednodes))
  				continue;
  		zone = *z;
  		if (unlikely(NUMA_BUILD && (gfp_mask & __GFP_THISNODE) &&
  			zone->zone_pgdat != zonelist->zones[0]->zone_pgdat))
  				break;
  		if ((alloc_flags & ALLOC_CPUSET) &&
  			!cpuset_zone_allowed_softwall(zone, gfp_mask))
  				goto try_next_zone;
  
  		if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
  			unsigned long mark;
  			if (alloc_flags & ALLOC_WMARK_MIN)
  				mark = zone->pages_min;
  			else if (alloc_flags & ALLOC_WMARK_LOW)
  				mark = zone->pages_low;
  			else
  				mark = zone->pages_high;
  			if (!zone_watermark_ok(zone, order, mark,
  				    classzone_idx, alloc_flags)) {
  				if (!zone_reclaim_mode ||
  				    !zone_reclaim(zone, gfp_mask, order))
  					goto this_zone_full;
  			}
  		}
  
  		page = buffered_rmqueue(zonelist, zone, order, gfp_mask);
  		if (page)
  			break;
  this_zone_full:
  		if (NUMA_BUILD)
  			zlc_mark_zone_full(zonelist, z);
  try_next_zone:
  		if (NUMA_BUILD && !did_zlc_setup) {
  			/* we do zlc_setup after the first zone is tried */
  			allowednodes = zlc_setup(zonelist, alloc_flags);
  			zlc_active = 1;
  			did_zlc_setup = 1;
  		}
  	} while (*(++z) != NULL);
  
  	if (unlikely(NUMA_BUILD && page == NULL && zlc_active)) {
  		/* Disable zlc cache for second zonelist scan */
  		zlc_active = 0;
  		goto zonelist_scan;
  	}
  	return page;
  }
  
  /*
   * This is the 'heart' of the zoned buddy allocator.
   */
  struct page * fastcall
  __alloc_pages(gfp_t gfp_mask, unsigned int order,
  		struct zonelist *zonelist)
  {
  	const gfp_t wait = gfp_mask & __GFP_WAIT;
  	struct zone **z;
  	struct page *page;
  	struct reclaim_state reclaim_state;
  	struct task_struct *p = current;
  	int do_retry;
  	int alloc_flags;
  	int did_some_progress;
  
  	might_sleep_if(wait);
  
  	if (should_fail_alloc_page(gfp_mask, order))
  		return NULL;
  
  restart:
  	z = zonelist->zones;  /* the list of zones suitable for gfp_mask */
  
  	if (unlikely(*z == NULL)) {
  		/* Should this ever happen?? */
  		return NULL;
  	}
  
  	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
  				zonelist, ALLOC_WMARK_LOW|ALLOC_CPUSET);
  	if (page)
  		goto got_pg;
  
  	/*
  	 * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and
  	 * __GFP_NOWARN set) should not cause reclaim since the subsystem
  	 * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim
  	 * using a larger set of nodes after it has established that the
  	 * allowed per node queues are empty and that nodes are
  	 * over allocated.
  	 */
  	if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
  		goto nopage;
  
  	for (z = zonelist->zones; *z; z++)
  		wakeup_kswapd(*z, order);
  
  	/*
  	 * OK, we're below the kswapd watermark and have kicked background
  	 * reclaim. Now things get more complex, so set up alloc_flags according
  	 * to how we want to proceed.
  	 *
  	 * The caller may dip into page reserves a bit more if the caller
  	 * cannot run direct reclaim, or if the caller has realtime scheduling
  	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
  	 * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
  	 */
  	alloc_flags = ALLOC_WMARK_MIN;
  	if ((unlikely(rt_task(p)) && !in_interrupt()) || !wait)
  		alloc_flags |= ALLOC_HARDER;
  	if (gfp_mask & __GFP_HIGH)
  		alloc_flags |= ALLOC_HIGH;
  	if (wait)
  		alloc_flags |= ALLOC_CPUSET;
  
  	/*
  	 * Go through the zonelist again. Let __GFP_HIGH and allocations
  	 * coming from realtime tasks go deeper into reserves.
  	 *
  	 * This is the last chance, in general, before the goto nopage.
  	 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
  	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
  	 */
  	page = get_page_from_freelist(gfp_mask, order, zonelist, alloc_flags);
  	if (page)
  		goto got_pg;
  
  	/* This allocation should allow future memory freeing. */
  
  rebalance:
  	if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE)))
  			&& !in_interrupt()) {
  		if (!(gfp_mask & __GFP_NOMEMALLOC)) {
  nofail_alloc:
  			/* go through the zonelist yet again, ignoring mins */
  			page = get_page_from_freelist(gfp_mask, order,
  				zonelist, ALLOC_NO_WATERMARKS);
  			if (page)
  				goto got_pg;
  			if (gfp_mask & __GFP_NOFAIL) {
  				congestion_wait(WRITE, HZ/50);
  				goto nofail_alloc;
  			}
  		}
  		goto nopage;
  	}
  
  	/* Atomic allocations - we can't balance anything */
  	if (!wait)
  		goto nopage;
  
  	cond_resched();
  
  	/* We now go into synchronous reclaim */
  	cpuset_memory_pressure_bump();
  	p->flags |= PF_MEMALLOC;
  	reclaim_state.reclaimed_slab = 0;
  	p->reclaim_state = &reclaim_state;
  
  	did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask);
  
  	p->reclaim_state = NULL;
  	p->flags &= ~PF_MEMALLOC;
  
  	cond_resched();
  
  	if (likely(did_some_progress)) {
  		page = get_page_from_freelist(gfp_mask, order,
  						zonelist, alloc_flags);
  		if (page)
  			goto got_pg;
  	} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
  		/*
  		 * Go through the zonelist yet one more time, keep
  		 * very high watermark here, this is only to catch
  		 * a parallel oom killing, we must fail if we're still
  		 * under heavy pressure.
  		 */
  		page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
  				zonelist, ALLOC_WMARK_HIGH|ALLOC_CPUSET);
  		if (page)
  			goto got_pg;
  
  		out_of_memory(zonelist, gfp_mask, order);
  		goto restart;
  	}
  
  	/*
  	 * Don't let big-order allocations loop unless the caller explicitly
  	 * requests that.  Wait for some write requests to complete then retry.
  	 *
  	 * In this implementation, __GFP_REPEAT means __GFP_NOFAIL for order
  	 * <= 3, but that may not be true in other implementations.
  	 */
  	do_retry = 0;
  	if (!(gfp_mask & __GFP_NORETRY)) {
  		if ((order <= 3) || (gfp_mask & __GFP_REPEAT))
  			do_retry = 1;
  		if (gfp_mask & __GFP_NOFAIL)
  			do_retry = 1;
  	}
  	if (do_retry) {
  		congestion_wait(WRITE, HZ/50);
  		goto rebalance;
  	}
  
  nopage:
  	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) {
  		printk(KERN_WARNING "%s: page allocation failure."
  			" order:%d, mode:0x%x\n",
  			p->comm, order, gfp_mask);
  		dump_stack();
  		show_mem();
  	}
  got_pg:
  	return page;
  }
  
  EXPORT_SYMBOL(__alloc_pages);
  
  /*
   * Common helper functions.
   */
  fastcall unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
  {
  	struct page * page;
  	page = alloc_pages(gfp_mask, order);
  	if (!page)
  		return 0;
  	return (unsigned long) page_address(page);
  }
  
  EXPORT_SYMBOL(__get_free_pages);
  
  fastcall unsigned long get_zeroed_page(gfp_t gfp_mask)
  {
  	struct page * page;
  
  	/*
  	 * get_zeroed_page() returns a 32-bit address, which cannot represent
  	 * a highmem page
  	 */
  	VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
  
  	page = alloc_pages(gfp_mask | __GFP_ZERO, 0);
  	if (page)
  		return (unsigned long) page_address(page);
  	return 0;
  }
  
  EXPORT_SYMBOL(get_zeroed_page);
  
  void __pagevec_free(struct pagevec *pvec)
  {
  	int i = pagevec_count(pvec);
  
  	while (--i >= 0)
  		free_hot_cold_page(pvec->pages[i], pvec->cold);
  }
  
  fastcall void __free_pages(struct page *page, unsigned int order)
  {
  	if (put_page_testzero(page)) {
  		if (order == 0)
  			free_hot_page(page);
  		else
  			__free_pages_ok(page, order);
  	}
  }
  
  EXPORT_SYMBOL(__free_pages);
  
  fastcall void free_pages(unsigned long addr, unsigned int order)
  {
  	if (addr != 0) {
  		VM_BUG_ON(!virt_addr_valid((void *)addr));
  		__free_pages(virt_to_page((void *)addr), order);
  	}
  }
  
  EXPORT_SYMBOL(free_pages);
  
  static unsigned int nr_free_zone_pages(int offset)
  {
  	/* Just pick one node, since fallback list is circular */
  	pg_data_t *pgdat = NODE_DATA(numa_node_id());
  	unsigned int sum = 0;
  
  	struct zonelist *zonelist = pgdat->node_zonelists + offset;
  	struct zone **zonep = zonelist->zones;
  	struct zone *zone;
  
  	for (zone = *zonep++; zone; zone = *zonep++) {
  		unsigned long size = zone->present_pages;
  		unsigned long high = zone->pages_high;
  		if (size > high)
  			sum += size - high;
  	}
  
  	return sum;
  }
  
  /*
   * Amount of free RAM allocatable within ZONE_DMA and ZONE_NORMAL
   */
  unsigned int nr_free_buffer_pages(void)
  {
  	return nr_free_zone_pages(gfp_zone(GFP_USER));
  }
  
  /*
   * Amount of free RAM allocatable within all zones
   */
  unsigned int nr_free_pagecache_pages(void)
  {
  	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER));
  }
  
  static inline void show_node(struct zone *zone)
  {
  	if (NUMA_BUILD)
  		printk("Node %d ", zone_to_nid(zone));
  }
  
  void si_meminfo(struct sysinfo *val)
  {
  	val->totalram = totalram_pages;
  	val->sharedram = 0;
  	val->freeram = global_page_state(NR_FREE_PAGES);
  	val->bufferram = nr_blockdev_pages();
  	val->totalhigh = totalhigh_pages;
  	val->freehigh = nr_free_highpages();
  	val->mem_unit = PAGE_SIZE;
  }
  
  EXPORT_SYMBOL(si_meminfo);
  
  #ifdef CONFIG_NUMA
  void si_meminfo_node(struct sysinfo *val, int nid)
  {
  	pg_data_t *pgdat = NODE_DATA(nid);
  
  	val->totalram = pgdat->node_present_pages;
  	val->freeram = node_page_state(nid, NR_FREE_PAGES);
  #ifdef CONFIG_HIGHMEM
  	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
  	val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
  			NR_FREE_PAGES);
  #else
  	val->totalhigh = 0;
  	val->freehigh = 0;
  #endif
  	val->mem_unit = PAGE_SIZE;
  }
  #endif
  
  #define K(x) ((x) << (PAGE_SHIFT-10))
  
  /*
   * Show free area list (used inside shift_scroll-lock stuff)
   * We also calculate the percentage fragmentation. We do this by counting the
   * memory on each free list with the exception of the first item on the list.
   */
  void show_free_areas(void)
  {
  	int cpu;
  	struct zone *zone;
  
  	for_each_zone(zone) {
  		if (!populated_zone(zone))
  			continue;
  
  		show_node(zone);
  		printk("%s per-cpu:\n", zone->name);
  
  		for_each_online_cpu(cpu) {
  			struct per_cpu_pageset *pageset;
  
  			pageset = zone_pcp(zone, cpu);
  
  			printk("CPU %4d: Hot: hi:%5d, btch:%4d usd:%4d   "
  			       "Cold: hi:%5d, btch:%4d usd:%4d\n",
  			       cpu, pageset->pcp[0].high,
  			       pageset->pcp[0].batch, pageset->pcp[0].count,
  			       pageset->pcp[1].high, pageset->pcp[1].batch,
  			       pageset->pcp[1].count);
  		}
  	}
  
  	printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu unstable:%lu\n"
  		" free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
  		global_page_state(NR_ACTIVE),
  		global_page_state(NR_INACTIVE),
  		global_page_state(NR_FILE_DIRTY),
  		global_page_state(NR_WRITEBACK),
  		global_page_state(NR_UNSTABLE_NFS),
  		global_page_state(NR_FREE_PAGES),
  		global_page_state(NR_SLAB_RECLAIMABLE) +
  			global_page_state(NR_SLAB_UNRECLAIMABLE),
  		global_page_state(NR_FILE_MAPPED),
  		global_page_state(NR_PAGETABLE),
  		global_page_state(NR_BOUNCE));
  
  	for_each_zone(zone) {
  		int i;
  
  		if (!populated_zone(zone))
  			continue;
  
  		show_node(zone);
  		printk("%s"
  			" free:%lukB"
  			" min:%lukB"
  			" low:%lukB"
  			" high:%lukB"
  			" active:%lukB"
  			" inactive:%lukB"
  			" present:%lukB"
  			" pages_scanned:%lu"
  			" all_unreclaimable? %s"
  			"\n",
  			zone->name,
  			K(zone_page_state(zone, NR_FREE_PAGES)),
  			K(zone->pages_min),
  			K(zone->pages_low),
  			K(zone->pages_high),
  			K(zone_page_state(zone, NR_ACTIVE)),
  			K(zone_page_state(zone, NR_INACTIVE)),
  			K(zone->present_pages),
  			zone->pages_scanned,
  			(zone->all_unreclaimable ? "yes" : "no")
  			);
  		printk("lowmem_reserve[]:");
  		for (i = 0; i < MAX_NR_ZONES; i++)
  			printk(" %lu", zone->lowmem_reserve[i]);
  		printk("\n");
  	}
  
  	for_each_zone(zone) {
   		unsigned long nr[MAX_ORDER], flags, order, total = 0;
  
  		if (!populated_zone(zone))
  			continue;
  
  		show_node(zone);
  		printk("%s: ", zone->name);
  
  		spin_lock_irqsave(&zone->lock, flags);
  		for (order = 0; order < MAX_ORDER; order++) {
  			nr[order] = zone->free_area[order].nr_free;
  			total += nr[order] << order;
  		}
  		spin_unlock_irqrestore(&zone->lock, flags);
  		for (order = 0; order < MAX_ORDER; order++)
  			printk("%lu*%lukB ", nr[order], K(1UL) << order);
  		printk("= %lukB\n", K(total));
  	}
  
  	show_swap_cache_info();
  }
  
  /*
   * Builds allocation fallback zone lists.
   *
   * Add all populated zones of a node to the zonelist.
   */
  static int __meminit build_zonelists_node(pg_data_t *pgdat,
  			struct zonelist *zonelist, int nr_zones, enum zone_type zone_type)
  {
  	struct zone *zone;
  
  	BUG_ON(zone_type >= MAX_NR_ZONES);
  	zone_type++;
  
  	do {
  		zone_type--;
  		zone = pgdat->node_zones + zone_type;
  		if (populated_zone(zone)) {
  			zonelist->zones[nr_zones++] = zone;
  			check_highest_zone(zone_type);
  		}
  
  	} while (zone_type);
  	return nr_zones;
  }
  
  #ifdef CONFIG_NUMA
  #define MAX_NODE_LOAD (num_online_nodes())
  static int __meminitdata node_load[MAX_NUMNODES];
  /**
   * find_next_best_node - find the next node that should appear in a given node's fallback list
   * @node: node whose fallback list we're appending
   * @used_node_mask: nodemask_t of already used nodes
   *
   * We use a number of factors to determine which is the next node that should
   * appear on a given node's fallback list.  The node should not have appeared
   * already in @node's fallback list, and it should be the next closest node
   * according to the distance array (which contains arbitrary distance values
   * from each node to each node in the system), and should also prefer nodes
   * with no CPUs, since presumably they'll have very little allocation pressure
   * on them otherwise.
   * It returns -1 if no node is found.
   */
  static int __meminit find_next_best_node(int node, nodemask_t *used_node_mask)
  {
  	int n, val;
  	int min_val = INT_MAX;
  	int best_node = -1;
  
  	/* Use the local node if we haven't already */
  	if (!node_isset(node, *used_node_mask)) {
  		node_set(node, *used_node_mask);
  		return node;
  	}
  
  	for_each_online_node(n) {
  		cpumask_t tmp;
  
  		/* Don't want a node to appear more than once */
  		if (node_isset(n, *used_node_mask))
  			continue;
  
  		/* Use the distance array to find the distance */
  		val = node_distance(node, n);
  
  		/* Penalize nodes under us ("prefer the next node") */
  		val += (n < node);
  
  		/* Give preference to headless and unused nodes */
  		tmp = node_to_cpumask(n);
  		if (!cpus_empty(tmp))
  			val += PENALTY_FOR_NODE_WITH_CPUS;
  
  		/* Slight preference for less loaded node */
  		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
  		val += node_load[n];
  
  		if (val < min_val) {
  			min_val = val;
  			best_node = n;
  		}
  	}
  
  	if (best_node >= 0)
  		node_set(best_node, *used_node_mask);
  
  	return best_node;
  }
  
  static void __meminit build_zonelists(pg_data_t *pgdat)
  {
  	int j, node, local_node;
  	enum zone_type i;
  	int prev_node, load;
  	struct zonelist *zonelist;
  	nodemask_t used_mask;
  
  	/* initialize zonelists */
  	for (i = 0; i < MAX_NR_ZONES; i++) {
  		zonelist = pgdat->node_zonelists + i;
  		zonelist->zones[0] = NULL;
  	}
  
  	/* NUMA-aware ordering of nodes */
  	local_node = pgdat->node_id;
  	load = num_online_nodes();
  	prev_node = local_node;
  	nodes_clear(used_mask);
  	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
  		int distance = node_distance(local_node, node);
  
  		/*
  		 * If another node is sufficiently far away then it is better
  		 * to reclaim pages in a zone before going off node.
  		 */
  		if (distance > RECLAIM_DISTANCE)
  			zone_reclaim_mode = 1;
  
  		/*
  		 * We don't want to pressure a particular node.
  		 * So adding penalty to the first node in same
  		 * distance group to make it round-robin.
  		 */
  
  		if (distance != node_distance(local_node, prev_node))
  			node_load[node] += load;
  		prev_node = node;
  		load--;
  		for (i = 0; i < MAX_NR_ZONES; i++) {
  			zonelist = pgdat->node_zonelists + i;
  			for (j = 0; zonelist->zones[j] != NULL; j++);
  
  	 		j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
  			zonelist->zones[j] = NULL;
  		}
  	}
  }
  
  /* Construct the zonelist performance cache - see further mmzone.h */
  static void __meminit build_zonelist_cache(pg_data_t *pgdat)
  {
  	int i;
  
  	for (i = 0; i < MAX_NR_ZONES; i++) {
  		struct zonelist *zonelist;
  		struct zonelist_cache *zlc;
  		struct zone **z;
  
  		zonelist = pgdat->node_zonelists + i;
  		zonelist->zlcache_ptr = zlc = &zonelist->zlcache;
  		bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
  		for (z = zonelist->zones; *z; z++)
  			zlc->z_to_n[z - zonelist->zones] = zone_to_nid(*z);
  	}
  }
  
  #else	/* CONFIG_NUMA */
  
  static void __meminit build_zonelists(pg_data_t *pgdat)
  {
  	int node, local_node;
  	enum zone_type i,j;
  
  	local_node = pgdat->node_id;
  	for (i = 0; i < MAX_NR_ZONES; i++) {
  		struct zonelist *zonelist;
  
  		zonelist = pgdat->node_zonelists + i;
  
   		j = build_zonelists_node(pgdat, zonelist, 0, i);
   		/*
   		 * Now we build the zonelist so that it contains the zones
   		 * of all the other nodes.
   		 * We don't want to pressure a particular node, so when
   		 * building the zones for node N, we make sure that the
   		 * zones coming right after the local ones are those from
   		 * node N+1 (modulo N)
   		 */
  		for (node = local_node + 1; node < MAX_NUMNODES; node++) {
  			if (!node_online(node))
  				continue;
  			j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
  		}
  		for (node = 0; node < local_node; node++) {
  			if (!node_online(node))
  				continue;
  			j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
  		}
  
  		zonelist->zones[j] = NULL;
  	}
  }
  
  /* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
  static void __meminit build_zonelist_cache(pg_data_t *pgdat)
  {
  	int i;
  
  	for (i = 0; i < MAX_NR_ZONES; i++)
  		pgdat->node_zonelists[i].zlcache_ptr = NULL;
  }
  
  #endif	/* CONFIG_NUMA */
  
  /* return values int ....just for stop_machine_run() */
  static int __meminit __build_all_zonelists(void *dummy)
  {
  	int nid;
  
  	for_each_online_node(nid) {
  		build_zonelists(NODE_DATA(nid));
  		build_zonelist_cache(NODE_DATA(nid));
  	}
  	return 0;
  }
  
  void __meminit build_all_zonelists(void)
  {
  	if (system_state == SYSTEM_BOOTING) {
  		__build_all_zonelists(NULL);
  		cpuset_init_current_mems_allowed();
  	} else {
  		/* we have to stop all cpus to guaranntee there is no user
  		   of zonelist */
  		stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
  		/* cpuset refresh routine should be here */
  	}
  	vm_total_pages = nr_free_pagecache_pages();
  	printk("Built %i zonelists.  Total pages: %ld\n",
  			num_online_nodes(), vm_total_pages);
  }
  
  /*
   * Helper functions to size the waitqueue hash table.
   * Essentially these want to choose hash table sizes sufficiently
   * large so that collisions trying to wait on pages are rare.
   * But in fact, the number of active page waitqueues on typical
   * systems is ridiculously low, less than 200. So this is even
   * conservative, even though it seems large.
   *
   * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to
   * waitqueues, i.e. the size of the waitq table given the number of pages.
   */
  #define PAGES_PER_WAITQUEUE	256
  
  #ifndef CONFIG_MEMORY_HOTPLUG
  static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
  {
  	unsigned long size = 1;
  
  	pages /= PAGES_PER_WAITQUEUE;
  
  	while (size < pages)
  		size <<= 1;
  
  	/*
  	 * Once we have dozens or even hundreds of threads sleeping
  	 * on IO we've got bigger problems than wait queue collision.
  	 * Limit the size of the wait table to a reasonable size.
  	 */
  	size = min(size, 4096UL);
  
  	return max(size, 4UL);
  }
  #else
  /*
   * A zone's size might be changed by hot-add, so it is not possible to determine
   * a suitable size for its wait_table.  So we use the maximum size now.
   *
   * The max wait table size = 4096 x sizeof(wait_queue_head_t).   ie:
   *
   *    i386 (preemption config)    : 4096 x 16 = 64Kbyte.
   *    ia64, x86-64 (no preemption): 4096 x 20 = 80Kbyte.
   *    ia64, x86-64 (preemption)   : 4096 x 24 = 96Kbyte.
   *
   * The maximum entries are prepared when a zone's memory is (512K + 256) pages
   * or more by the traditional way. (See above).  It equals:
   *
   *    i386, x86-64, powerpc(4K page size) : =  ( 2G + 1M)byte.
   *    ia64(16K page size)                 : =  ( 8G + 4M)byte.
   *    powerpc (64K page size)             : =  (32G +16M)byte.
   */
  static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
  {
  	return 4096UL;
  }
  #endif
  
  /*
   * This is an integer logarithm so that shifts can be used later
   * to extract the more random high bits from the multiplicative
   * hash function before the remainder is taken.
   */
  static inline unsigned long wait_table_bits(unsigned long size)
  {
  	return ffz(~size);
  }
  
  #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))
  
  /*
   * Initially all pages are reserved - free ones are freed
   * up by free_all_bootmem() once the early boot process is
   * done. Non-atomic initialization, single-pass.
   */
  void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
  		unsigned long start_pfn, enum memmap_context context)
  {
  	struct page *page;
  	unsigned long end_pfn = start_pfn + size;
  	unsigned long pfn;
  
  	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
  		/*
  		 * There can be holes in boot-time mem_map[]s
  		 * handed to this function.  They do not
  		 * exist on hotplugged memory.
  		 */
  		if (context == MEMMAP_EARLY) {
  			if (!early_pfn_valid(pfn))
  				continue;
  			if (!early_pfn_in_nid(pfn, nid))
  				continue;
  		}
  		page = pfn_to_page(pfn);
  		set_page_links(page, zone, nid, pfn);
  		init_page_count(page);
  		reset_page_mapcount(page);
  		SetPageReserved(page);
  		INIT_LIST_HEAD(&page->lru);
  #ifdef WANT_PAGE_VIRTUAL
  		/* The shift won't overflow because ZONE_NORMAL is below 4G. */
  		if (!is_highmem_idx(zone))
  			set_page_address(page, __va(pfn << PAGE_SHIFT));
  #endif
  	}
  }
  
  void zone_init_free_lists(struct pglist_data *pgdat, struct zone *zone,
  				unsigned long size)
  {
  	int order;
  	for (order = 0; order < MAX_ORDER ; order++) {
  		INIT_LIST_HEAD(&zone->free_area[order].free_list);
  		zone->free_area[order].nr_free = 0;
  	}
  }
  
  #ifndef __HAVE_ARCH_MEMMAP_INIT
  #define memmap_init(size, nid, zone, start_pfn) \
  	memmap_init_zone((size), (nid), (zone), (start_pfn), MEMMAP_EARLY)
  #endif
  
  static int __cpuinit zone_batchsize(struct zone *zone)
  {
  	int batch;
  
  	/*
  	 * The per-cpu-pages pools are set to around 1000th of the
  	 * size of the zone.  But no more than 1/2 of a meg.
  	 *
  	 * OK, so we don't know how big the cache is.  So guess.
  	 */
  	batch = zone->present_pages / 1024;
  	if (batch * PAGE_SIZE > 512 * 1024)
  		batch = (512 * 1024) / PAGE_SIZE;
  	batch /= 4;		/* We effectively *= 4 below */
  	if (batch < 1)
  		batch = 1;
  
  	/*
  	 * Clamp the batch to a 2^n - 1 value. Having a power
  	 * of 2 value was found to be more likely to have
  	 * suboptimal cache aliasing properties in some cases.
  	 *
  	 * For example if 2 tasks are alternately allocating
  	 * batches of pages, one task can end up with a lot
  	 * of pages of one half of the possible page colors
  	 * and the other with pages of the other colors.
  	 */
  	batch = (1 << (fls(batch + batch/2)-1)) - 1;
  
  	return batch;
  }
  
  inline void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
  {
  	struct per_cpu_pages *pcp;
  
  	memset(p, 0, sizeof(*p));
  
  	pcp = &p->pcp[0];		/* hot */
  	pcp->count = 0;
  	pcp->high = 6 * batch;
  	pcp->batch = max(1UL, 1 * batch);
  	INIT_LIST_HEAD(&pcp->list);
  
  	pcp = &p->pcp[1];		/* cold*/
  	pcp->count = 0;
  	pcp->high = 2 * batch;
  	pcp->batch = max(1UL, batch/2);
  	INIT_LIST_HEAD(&pcp->list);
  }
  
  /*
   * setup_pagelist_highmark() sets the high water mark for hot per_cpu_pagelist
   * to the value high for the pageset p.
   */
  
  static void setup_pagelist_highmark(struct per_cpu_pageset *p,
  				unsigned long high)
  {
  	struct per_cpu_pages *pcp;
  
  	pcp = &p->pcp[0]; /* hot list */
  	pcp->high = high;
  	pcp->batch = max(1UL, high/4);
  	if ((high/4) > (PAGE_SHIFT * 8))
  		pcp->batch = PAGE_SHIFT * 8;
  }
  
  
  #ifdef CONFIG_NUMA
  /*
   * Boot pageset table. One per cpu which is going to be used for all
   * zones and all nodes. The parameters will be set in such a way
   * that an item put on a list will immediately be handed over to
   * the buddy list. This is safe since pageset manipulation is done
   * with interrupts disabled.
   *
   * Some NUMA counter updates may also be caught by the boot pagesets.
   *
   * The boot_pagesets must be kept even after bootup is complete for
   * unused processors and/or zones. They do play a role for bootstrapping
   * hotplugged processors.
   *
   * zoneinfo_show() and maybe other functions do
   * not check if the processor is online before following the pageset pointer.
   * Other parts of the kernel may not check if the zone is available.
   */
  static struct per_cpu_pageset boot_pageset[NR_CPUS];
  
  /*
   * Dynamically allocate memory for the
   * per cpu pageset array in struct zone.
   */
  static int __cpuinit process_zones(int cpu)
  {
  	struct zone *zone, *dzone;
  
  	for_each_zone(zone) {
  
  		if (!populated_zone(zone))
  			continue;
  
  		zone_pcp(zone, cpu) = kmalloc_node(sizeof(struct per_cpu_pageset),
  					 GFP_KERNEL, cpu_to_node(cpu));
  		if (!zone_pcp(zone, cpu))
  			goto bad;
  
  		setup_pageset(zone_pcp(zone, cpu), zone_batchsize(zone));
  
  		if (percpu_pagelist_fraction)
  			setup_pagelist_highmark(zone_pcp(zone, cpu),
  			 	(zone->present_pages / percpu_pagelist_fraction));
  	}
  
  	return 0;
  bad:
  	for_each_zone(dzone) {
  		if (dzone == zone)
  			break;
  		kfree(zone_pcp(dzone, cpu));
  		zone_pcp(dzone, cpu) = NULL;
  	}
  	return -ENOMEM;
  }
  
  static inline void free_zone_pagesets(int cpu)
  {
  	struct zone *zone;
  
  	for_each_zone(zone) {
  		struct per_cpu_pageset *pset = zone_pcp(zone, cpu);
  
  		/* Free per_cpu_pageset if it is slab allocated */
  		if (pset != &boot_pageset[cpu])
  			kfree(pset);
  		zone_pcp(zone, cpu) = NULL;
  	}
  }
  
  static int __cpuinit pageset_cpuup_callback(struct notifier_block *nfb,
  		unsigned long action,
  		void *hcpu)
  {
  	int cpu = (long)hcpu;
  	int ret = NOTIFY_OK;
  
  	switch (action) {
  	case CPU_UP_PREPARE:
  		if (process_zones(cpu))
  			ret = NOTIFY_BAD;
  		break;
  	case CPU_UP_CANCELED:
  	case CPU_DEAD:
  		free_zone_pagesets(cpu);
  		break;
  	default:
  		break;
  	}
  	return ret;
  }
  
  static struct notifier_block __cpuinitdata pageset_notifier =
  	{ &pageset_cpuup_callback, NULL, 0 };
  
  void __init setup_per_cpu_pageset(void)
  {
  	int err;
  
  	/* Initialize per_cpu_pageset for cpu 0.
  	 * A cpuup callback will do this for every cpu
  	 * as it comes online
  	 */
  	err = process_zones(smp_processor_id());
  	BUG_ON(err);
  	register_cpu_notifier(&pageset_notifier);
  }
  
  #endif
  
  static __meminit
  int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
  {
  	int i;
  	struct pglist_data *pgdat = zone->zone_pgdat;
  	size_t alloc_size;
  
  	/*
  	 * The per-page waitqueue mechanism uses hashed waitqueues
  	 * per zone.
  	 */
  	zone->wait_table_hash_nr_entries =
  		 wait_table_hash_nr_entries(zone_size_pages);
  	zone->wait_table_bits =
  		wait_table_bits(zone->wait_table_hash_nr_entries);
  	alloc_size = zone->wait_table_hash_nr_entries
  					* sizeof(wait_queue_head_t);
  
   	if (system_state == SYSTEM_BOOTING) {
  		zone->wait_table = (wait_queue_head_t *)
  			alloc_bootmem_node(pgdat, alloc_size);
  	} else {
  		/*
  		 * This case means that a zone whose size was 0 gets new memory
  		 * via memory hot-add.
  		 * But it may be the case that a new node was hot-added.  In
  		 * this case vmalloc() will not be able to use this new node's
  		 * memory - this wait_table must be initialized to use this new
  		 * node itself as well.
  		 * To use this new node's memory, further consideration will be
  		 * necessary.
  		 */
  		zone->wait_table = (wait_queue_head_t *)vmalloc(alloc_size);
  	}
  	if (!zone->wait_table)
  		return -ENOMEM;
  
  	for(i = 0; i < zone->wait_table_hash_nr_entries; ++i)
  		init_waitqueue_head(zone->wait_table + i);
  
  	return 0;
  }
  
  static __meminit void zone_pcp_init(struct zone *zone)
  {
  	int cpu;
  	unsigned long batch = zone_batchsize(zone);
  
  	for (cpu = 0; cpu < NR_CPUS; cpu++) {
  #ifdef CONFIG_NUMA
  		/* Early boot. Slab allocator not functional yet */
  		zone_pcp(zone, cpu) = &boot_pageset[cpu];
  		setup_pageset(&boot_pageset[cpu],0);
  #else
  		setup_pageset(zone_pcp(zone,cpu), batch);
  #endif
  	}
  	if (zone->present_pages)
  		printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%lu\n",
  			zone->name, zone->present_pages, batch);
  }
  
  __meminit int init_currently_empty_zone(struct zone *zone,
  					unsigned long zone_start_pfn,
  					unsigned long size,
  					enum memmap_context context)
  {
  	struct pglist_data *pgdat = zone->zone_pgdat;
  	int ret;
  	ret = zone_wait_table_init(zone, size);
  	if (ret)
  		return ret;
  	pgdat->nr_zones = zone_idx(zone) + 1;
  
  	zone->zone_start_pfn = zone_start_pfn;
  
  	memmap_init(size, pgdat->node_id, zone_idx(zone), zone_start_pfn);
  
  	zone_init_free_lists(pgdat, zone, zone->spanned_pages);
  
  	return 0;
  }
  
  #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
   * Basic iterator support. Return the first range of PFNs for a node
   * Note: nid == MAX_NUMNODES returns first region regardless of node
   */
  static int __init first_active_region_index_in_nid(int nid)
  {
  	int i;
  
  	for (i = 0; i < nr_nodemap_entries; i++)
  		if (nid == MAX_NUMNODES || early_node_map[i].nid == nid)
  			return i;
  
  	return -1;
  }
  
  /*
   * Basic iterator support. Return the next active range of PFNs for a node
   * Note: nid == MAX_NUMNODES returns next region regardles of node
   */
  static int __init next_active_region_index_in_nid(int index, int nid)
  {
  	for (index = index + 1; index < nr_nodemap_entries; index++)
  		if (nid == MAX_NUMNODES || early_node_map[index].nid == nid)
  			return index;
  
  	return -1;
  }
  
  #ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
  /*
   * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
   * Architectures may implement their own version but if add_active_range()
   * was used and there are no special requirements, this is a convenient
   * alternative
   */
  int __init early_pfn_to_nid(unsigned long pfn)
  {
  	int i;
  
  	for (i = 0; i < nr_nodemap_entries; i++) {
  		unsigned long start_pfn = early_node_map[i].start_pfn;
  		unsigned long end_pfn = early_node_map[i].end_pfn;
  
  		if (start_pfn <= pfn && pfn < end_pfn)
  			return early_node_map[i].nid;
  	}
  
  	return 0;
  }
  #endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
  
  /* Basic iterator support to walk early_node_map[] */
  #define for_each_active_range_index_in_nid(i, nid) \
  	for (i = first_active_region_index_in_nid(nid); i != -1; \
  				i = next_active_region_index_in_nid(i, nid))
  
  /**
   * free_bootmem_with_active_regions - Call free_bootmem_node for each active range
   * @nid: The node to free memory on. If MAX_NUMNODES, all nodes are freed.
   * @max_low_pfn: The highest PFN that will be passed to free_bootmem_node
   *
   * If an architecture guarantees that all ranges registered with
   * add_active_ranges() contain no holes and may be freed, this
   * this function may be used instead of calling free_bootmem() manually.
   */
  void __init free_bootmem_with_active_regions(int nid,
  						unsigned long max_low_pfn)
  {
  	int i;
  
  	for_each_active_range_index_in_nid(i, nid) {
  		unsigned long size_pages = 0;
  		unsigned long end_pfn = early_node_map[i].end_pfn;
  
  		if (early_node_map[i].start_pfn >= max_low_pfn)
  			continue;
  
  		if (end_pfn > max_low_pfn)
  			end_pfn = max_low_pfn;
  
  		size_pages = end_pfn - early_node_map[i].start_pfn;
  		free_bootmem_node(NODE_DATA(early_node_map[i].nid),
  				PFN_PHYS(early_node_map[i].start_pfn),
  				size_pages << PAGE_SHIFT);
  	}
  }
  
  /**
   * sparse_memory_present_with_active_regions - Call memory_present for each active range
   * @nid: The node to call memory_present for. If MAX_NUMNODES, all nodes will be used.
   *
   * If an architecture guarantees that all ranges registered with
   * add_active_ranges() contain no holes and may be freed, this
   * function may be used instead of calling memory_present() manually.
   */
  void __init sparse_memory_present_with_active_regions(int nid)
  {
  	int i;
  
  	for_each_active_range_index_in_nid(i, nid)
  		memory_present(early_node_map[i].nid,
  				early_node_map[i].start_pfn,
  				early_node_map[i].end_pfn);
  }
  
  /**
   * push_node_boundaries - Push node boundaries to at least the requested boundary
   * @nid: The nid of the node to push the boundary for
   * @start_pfn: The start pfn of the node
   * @end_pfn: The end pfn of the node
   *
   * In reserve-based hot-add, mem_map is allocated that is unused until hotadd
   * time. Specifically, on x86_64, SRAT will report ranges that can potentially
   * be hotplugged even though no physical memory exists. This function allows
   * an arch to push out the node boundaries so mem_map is allocated that can
   * be used later.
   */
  #ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
  void __init push_node_boundaries(unsigned int nid,
  		unsigned long start_pfn, unsigned long end_pfn)
  {
  	printk(KERN_DEBUG "Entering push_node_boundaries(%u, %lu, %lu)\n",
  			nid, start_pfn, end_pfn);
  
  	/* Initialise the boundary for this node if necessary */
  	if (node_boundary_end_pfn[nid] == 0)
  		node_boundary_start_pfn[nid] = -1UL;
  
  	/* Update the boundaries */
  	if (node_boundary_start_pfn[nid] > start_pfn)
  		node_boundary_start_pfn[nid] = start_pfn;
  	if (node_boundary_end_pfn[nid] < end_pfn)
  		node_boundary_end_pfn[nid] = end_pfn;
  }
  
  /* If necessary, push the node boundary out for reserve hotadd */
  static void __init account_node_boundary(unsigned int nid,
  		unsigned long *start_pfn, unsigned long *end_pfn)
  {
  	printk(KERN_DEBUG "Entering account_node_boundary(%u, %lu, %lu)\n",
  			nid, *start_pfn, *end_pfn);
  
  	/* Return if boundary information has not been provided */
  	if (node_boundary_end_pfn[nid] == 0)
  		return;
  
  	/* Check the boundaries and update if necessary */
  	if (node_boundary_start_pfn[nid] < *start_pfn)
  		*start_pfn = node_boundary_start_pfn[nid];
  	if (node_boundary_end_pfn[nid] > *end_pfn)
  		*end_pfn = node_boundary_end_pfn[nid];
  }
  #else
  void __init push_node_boundaries(unsigned int nid,
  		unsigned long start_pfn, unsigned long end_pfn) {}
  
  static void __init account_node_boundary(unsigned int nid,
  		unsigned long *start_pfn, unsigned long *end_pfn) {}
  #endif
  
  
  /**
   * get_pfn_range_for_nid - Return the start and end page frames for a node
   * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
   * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
   * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
   *
   * It returns the start and end page frame of a node based on information
   * provided by an arch calling add_active_range(). If called for a node
   * with no available memory, a warning is printed and the start and end
   * PFNs will be 0.
   */
  void __init get_pfn_range_for_nid(unsigned int nid,
  			unsigned long *start_pfn, unsigned long *end_pfn)
  {
  	int i;
  	*start_pfn = -1UL;
  	*end_pfn = 0;
  
  	for_each_active_range_index_in_nid(i, nid) {
  		*start_pfn = min(*start_pfn, early_node_map[i].start_pfn);
  		*end_pfn = max(*end_pfn, early_node_map[i].end_pfn);
  	}
  
  	if (*start_pfn == -1UL) {
  		printk(KERN_WARNING "Node %u active with no memory\n", nid);
  		*start_pfn = 0;
  	}
  
  	/* Push the node boundaries out if requested */
  	account_node_boundary(nid, start_pfn, end_pfn);
  }
  
  /*
   * Return the number of pages a zone spans in a node, including holes
   * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
   */
  unsigned long __init zone_spanned_pages_in_node(int nid,
  					unsigned long zone_type,
  					unsigned long *ignored)
  {
  	unsigned long node_start_pfn, node_end_pfn;
  	unsigned long zone_start_pfn, zone_end_pfn;
  
  	/* Get the start and end of the node and zone */
  	get_pfn_range_for_nid(nid, &node_start_pfn, &node_end_pfn);
  	zone_start_pfn = arch_zone_lowest_possible_pfn[zone_type];
  	zone_end_pfn = arch_zone_highest_possible_pfn[zone_type];
  
  	/* Check that this node has pages within the zone's required range */
  	if (zone_end_pfn < node_start_pfn || zone_start_pfn > node_end_pfn)
  		return 0;
  
  	/* Move the zone boundaries inside the node if necessary */
  	zone_end_pfn = min(zone_end_pfn, node_end_pfn);
  	zone_start_pfn = max(zone_start_pfn, node_start_pfn);
  
  	/* Return the spanned pages */
  	return zone_end_pfn - zone_start_pfn;
  }
  
  /*
   * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
   * then all holes in the requested range will be accounted for.
   */
  unsigned long __init __absent_pages_in_range(int nid,
  				unsigned long range_start_pfn,
  				unsigned long range_end_pfn)
  {
  	int i = 0;
  	unsigned long prev_end_pfn = 0, hole_pages = 0;
  	unsigned long start_pfn;
  
  	/* Find the end_pfn of the first active range of pfns in the node */
  	i = first_active_region_index_in_nid(nid);
  	if (i == -1)
  		return 0;
  
  	/* Account for ranges before physical memory on this node */
  	if (early_node_map[i].start_pfn > range_start_pfn)
  		hole_pages = early_node_map[i].start_pfn - range_start_pfn;
  
  	prev_end_pfn = early_node_map[i].start_pfn;
  
  	/* Find all holes for the zone within the node */
  	for (; i != -1; i = next_active_region_index_in_nid(i, nid)) {
  
  		/* No need to continue if prev_end_pfn is outside the zone */
  		if (prev_end_pfn >= range_end_pfn)
  			break;
  
  		/* Make sure the end of the zone is not within the hole */
  		start_pfn = min(early_node_map[i].start_pfn, range_end_pfn);
  		prev_end_pfn = max(prev_end_pfn, range_start_pfn);
  
  		/* Update the hole size cound and move on */
  		if (start_pfn > range_start_pfn) {
  			BUG_ON(prev_end_pfn > start_pfn);
  			hole_pages += start_pfn - prev_end_pfn;
  		}
  		prev_end_pfn = early_node_map[i].end_pfn;
  	}
  
  	/* Account for ranges past physical memory on this node */
  	if (range_end_pfn > prev_end_pfn)
  		hole_pages += range_end_pfn -
  				max(range_start_pfn, prev_end_pfn);
  
  	return hole_pages;
  }
  
  /**
   * absent_pages_in_range - Return number of page frames in holes within a range
   * @start_pfn: The start PFN to start searching for holes
   * @end_pfn: The end PFN to stop searching for holes
   *
   * It returns the number of pages frames in memory holes within a range.
   */
  unsigned long __init absent_pages_in_range(unsigned long start_pfn,
  							unsigned long end_pfn)
  {
  	return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
  }
  
  /* Return the number of page frames in holes in a zone on a node */
  unsigned long __init zone_absent_pages_in_node(int nid,
  					unsigned long zone_type,
  					unsigned long *ignored)
  {
  	unsigned long node_start_pfn, node_end_pfn;
  	unsigned long zone_start_pfn, zone_end_pfn;
  
  	get_pfn_range_for_nid(nid, &node_start_pfn, &node_end_pfn);
  	zone_start_pfn = max(arch_zone_lowest_possible_pfn[zone_type],
  							node_start_pfn);
  	zone_end_pfn = min(arch_zone_highest_possible_pfn[zone_type],
  							node_end_pfn);
  
  	return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
  }
  
  #else
  static inline unsigned long zone_spanned_pages_in_node(int nid,
  					unsigned long zone_type,
  					unsigned long *zones_size)
  {
  	return zones_size[zone_type];
  }
  
  static inline unsigned long zone_absent_pages_in_node(int nid,
  						unsigned long zone_type,
  						unsigned long *zholes_size)
  {
  	if (!zholes_size)
  		return 0;
  
  	return zholes_size[zone_type];
  }
  
  #endif
  
  static void __init calculate_node_totalpages(struct pglist_data *pgdat,
  		unsigned long *zones_size, unsigned long *zholes_size)
  {
  	unsigned long realtotalpages, totalpages = 0;
  	enum zone_type i;
  
  	for (i = 0; i < MAX_NR_ZONES; i++)
  		totalpages += zone_spanned_pages_in_node(pgdat->node_id, i,
  								zones_size);
  	pgdat->node_spanned_pages = totalpages;
  
  	realtotalpages = totalpages;
  	for (i = 0; i < MAX_NR_ZONES; i++)
  		realtotalpages -=
  			zone_absent_pages_in_node(pgdat->node_id, i,
  								zholes_size);
  	pgdat->node_present_pages = realtotalpages;
  	printk(KERN_DEBUG "On node %d totalpages: %lu\n", pgdat->node_id,
  							realtotalpages);
  }
  
  /*
   * Set up the zone data structures:
   *   - mark all pages reserved
   *   - mark all memory queues empty
   *   - clear the memory bitmaps
   */
  static void __meminit free_area_init_core(struct pglist_data *pgdat,
  		unsigned long *zones_size, unsigned long *zholes_size)
  {
  	enum zone_type j;
  	int nid = pgdat->node_id;
  	unsigned long zone_start_pfn = pgdat->node_start_pfn;
  	int ret;
  
  	pgdat_resize_init(pgdat);
  	pgdat->nr_zones = 0;
  	init_waitqueue_head(&pgdat->kswapd_wait);
  	pgdat->kswapd_max_order = 0;
  	
  	for (j = 0; j < MAX_NR_ZONES; j++) {
  		struct zone *zone = pgdat->node_zones + j;
  		unsigned long size, realsize, memmap_pages;
  
  		size = zone_spanned_pages_in_node(nid, j, zones_size);
  		realsize = size - zone_absent_pages_in_node(nid, j,
  								zholes_size);
  
  		/*
  		 * Adjust realsize so that it accounts for how much memory
  		 * is used by this zone for memmap. This affects the watermark
  		 * and per-cpu initialisations
  		 */
  		memmap_pages = (size * sizeof(struct page)) >> PAGE_SHIFT;
  		if (realsize >= memmap_pages) {
  			realsize -= memmap_pages;
  			printk(KERN_DEBUG
  				"  %s zone: %lu pages used for memmap\n",
  				zone_names[j], memmap_pages);
  		} else
  			printk(KERN_WARNING
  				"  %s zone: %lu pages exceeds realsize %lu\n",
  				zone_names[j], memmap_pages, realsize);
  
  		/* Account for reserved pages */
  		if (j == 0 && realsize > dma_reserve) {
  			realsize -= dma_reserve;
  			printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
  					zone_names[0], dma_reserve);
  		}
  
  		if (!is_highmem_idx(j))
  			nr_kernel_pages += realsize;
  		nr_all_pages += realsize;
  
  		zone->spanned_pages = size;
  		zone->present_pages = realsize;
  #ifdef CONFIG_NUMA
  		zone->node = nid;
  		zone->min_unmapped_pages = (realsize*sysctl_min_unmapped_ratio)
  						/ 100;
  		zone->min_slab_pages = (realsize * sysctl_min_slab_ratio) / 100;
  #endif
  		zone->name = zone_names[j];
  		spin_lock_init(&zone->lock);
  		spin_lock_init(&zone->lru_lock);
  		zone_seqlock_init(zone);
  		zone->zone_pgdat = pgdat;
  
  		zone->prev_priority = DEF_PRIORITY;
  
  		zone_pcp_init(zone);
  		INIT_LIST_HEAD(&zone->active_list);
  		INIT_LIST_HEAD(&zone->inactive_list);
  		zone->nr_scan_active = 0;
  		zone->nr_scan_inactive = 0;
  		zap_zone_vm_stats(zone);
  		atomic_set(&zone->reclaim_in_progress, 0);
  		if (!size)
  			continue;
  
  		ret = init_currently_empty_zone(zone, zone_start_pfn,
  						size, MEMMAP_EARLY);
  		BUG_ON(ret);
  		zone_start_pfn += size;
  	}
  }
  
  static void __init alloc_node_mem_map(struct pglist_data *pgdat)
  {
  	/* Skip empty nodes */
  	if (!pgdat->node_spanned_pages)
  		return;
  
  #ifdef CONFIG_FLAT_NODE_MEM_MAP
  	/* ia64 gets its own node_mem_map, before this, without bootmem */
  	if (!pgdat->node_mem_map) {
  		unsigned long size, start, end;
  		struct page *map;
  
  		/*
  		 * The zone's endpoints aren't required to be MAX_ORDER
  		 * aligned but the node_mem_map endpoints must be in order
  		 * for the buddy allocator to function correctly.
  		 */
  		start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
  		end = pgdat->node_start_pfn + pgdat->node_spanned_pages;
  		end = ALIGN(end, MAX_ORDER_NR_PAGES);
  		size =  (end - start) * sizeof(struct page);
  		map = alloc_remap(pgdat->node_id, size);
  		if (!map)
  			map = alloc_bootmem_node(pgdat, size);
  		pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
  	}
  #ifdef CONFIG_FLATMEM
  	/*
  	 * With no DISCONTIG, the global mem_map is just set as node 0's
  	 */
  	if (pgdat == NODE_DATA(0)) {
  		mem_map = NODE_DATA(0)->node_mem_map;
  #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
  			mem_map -= pgdat->node_start_pfn;
  #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
  	}
  #endif
  #endif /* CONFIG_FLAT_NODE_MEM_MAP */
  }
  
  void __meminit free_area_init_node(int nid, struct pglist_data *pgdat,
  		unsigned long *zones_size, unsigned long node_start_pfn,
  		unsigned long *zholes_size)
  {
  	pgdat->node_id = nid;
  	pgdat->node_start_pfn = node_start_pfn;
  	calculate_node_totalpages(pgdat, zones_size, zholes_size);
  
  	alloc_node_mem_map(pgdat);
  
  	free_area_init_core(pgdat, zones_size, zholes_size);
  }
  
  #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /**
   * add_active_range - Register a range of PFNs backed by physical memory
   * @nid: The node ID the range resides on
   * @start_pfn: The start PFN of the available physical memory
   * @end_pfn: The end PFN of the available physical memory
   *
   * These ranges are stored in an early_node_map[] and later used by
   * free_area_init_nodes() to calculate zone sizes and holes. If the
   * range spans a memory hole, it is up to the architecture to ensure
   * the memory is not freed by the bootmem allocator. If possible
   * the range being registered will be merged with existing ranges.
   */
  void __init add_active_range(unsigned int nid, unsigned long start_pfn,
  						unsigned long end_pfn)
  {
  	int i;
  
  	printk(KERN_DEBUG "Entering add_active_range(%d, %lu, %lu) "
  			  "%d entries of %d used\n",
  			  nid, start_pfn, end_pfn,
  			  nr_nodemap_entries, MAX_ACTIVE_REGIONS);
  
  	/* Merge with existing active regions if possible */
  	for (i = 0; i < nr_nodemap_entries; i++) {
  		if (early_node_map[i].nid != nid)
  			continue;
  
  		/* Skip if an existing region covers this new one */
  		if (start_pfn >= early_node_map[i].start_pfn &&
  				end_pfn <= early_node_map[i].end_pfn)
  			return;
  
  		/* Merge forward if suitable */
  		if (start_pfn <= early_node_map[i].end_pfn &&
  				end_pfn > early_node_map[i].end_pfn) {
  			early_node_map[i].end_pfn = end_pfn;
  			return;
  		}
  
  		/* Merge backward if suitable */
  		if (start_pfn < early_node_map[i].end_pfn &&
  				end_pfn >= early_node_map[i].start_pfn) {
  			early_node_map[i].start_pfn = start_pfn;
  			return;
  		}
  	}
  
  	/* Check that early_node_map is large enough */
  	if (i >= MAX_ACTIVE_REGIONS) {
  		printk(KERN_CRIT "More than %d memory regions, truncating\n",
  							MAX_ACTIVE_REGIONS);
  		return;
  	}
  
  	early_node_map[i].nid = nid;
  	early_node_map[i].start_pfn = start_pfn;
  	early_node_map[i].end_pfn = end_pfn;
  	nr_nodemap_entries = i + 1;
  }
  
  /**
   * shrink_active_range - Shrink an existing registered range of PFNs
   * @nid: The node id the range is on that should be shrunk
   * @old_end_pfn: The old end PFN of the range
   * @new_end_pfn: The new PFN of the range
   *
   * i386 with NUMA use alloc_remap() to store a node_mem_map on a local node.
   * The map is kept at the end physical page range that has already been
   * registered with add_active_range(). This function allows an arch to shrink
   * an existing registered range.
   */
  void __init shrink_active_range(unsigned int nid, unsigned long old_end_pfn,
  						unsigned long new_end_pfn)
  {
  	int i;
  
  	/* Find the old active region end and shrink */
  	for_each_active_range_index_in_nid(i, nid)
  		if (early_node_map[i].end_pfn == old_end_pfn) {
  			early_node_map[i].end_pfn = new_end_pfn;
  			break;
  		}
  }
  
  /**
   * remove_all_active_ranges - Remove all currently registered regions
   *
   * During discovery, it may be found that a table like SRAT is invalid
   * and an alternative discovery method must be used. This function removes
   * all currently registered regions.
   */
  void __init remove_all_active_ranges(void)
  {
  	memset(early_node_map, 0, sizeof(early_node_map));
  	nr_nodemap_entries = 0;
  #ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
  	memset(node_boundary_start_pfn, 0, sizeof(node_boundary_start_pfn));
  	memset(node_boundary_end_pfn, 0, sizeof(node_boundary_end_pfn));
  #endif /* CONFIG_MEMORY_HOTPLUG_RESERVE */
  }
  
  /* Compare two active node_active_regions */
  static int __init cmp_node_active_region(const void *a, const void *b)
  {
  	struct node_active_region *arange = (struct node_active_region *)a;
  	struct node_active_region *brange = (struct node_active_region *)b;
  
  	/* Done this way to avoid overflows */
  	if (arange->start_pfn > brange->start_pfn)
  		return 1;
  	if (arange->start_pfn < brange->start_pfn)
  		return -1;
  
  	return 0;
  }
  
  /* sort the node_map by start_pfn */
  static void __init sort_node_map(void)
  {
  	sort(early_node_map, (size_t)nr_nodemap_entries,
  			sizeof(struct node_active_region),
  			cmp_node_active_region, NULL);
  }
  
  /* Find the lowest pfn for a node */
  unsigned long __init find_min_pfn_for_node(unsigned long nid)
  {
  	int i;
  	unsigned long min_pfn = ULONG_MAX;
  
  	/* Assuming a sorted map, the first range found has the starting pfn */
  	for_each_active_range_index_in_nid(i, nid)
  		min_pfn = min(min_pfn, early_node_map[i].start_pfn);
  
  	if (min_pfn == ULONG_MAX) {
  		printk(KERN_WARNING
  			"Could not find start_pfn for node %lu\n", nid);
  		return 0;
  	}
  
  	return min_pfn;
  }
  
  /**
   * find_min_pfn_with_active_regions - Find the minimum PFN registered
   *
   * It returns the minimum PFN based on information provided via
   * add_active_range().
   */
  unsigned long __init find_min_pfn_with_active_regions(void)
  {
  	return find_min_pfn_for_node(MAX_NUMNODES);
  }
  
  /**
   * find_max_pfn_with_active_regions - Find the maximum PFN registered
   *
   * It returns the maximum PFN based on information provided via
   * add_active_range().
   */
  unsigned long __init find_max_pfn_with_active_regions(void)
  {
  	int i;
  	unsigned long max_pfn = 0;
  
  	for (i = 0; i < nr_nodemap_entries; i++)
  		max_pfn = max(max_pfn, early_node_map[i].end_pfn);
  
  	return max_pfn;
  }
  
  /**
   * free_area_init_nodes - Initialise all pg_data_t and zone data
   * @max_zone_pfn: an array of max PFNs for each zone
   *
   * This will call free_area_init_node() for each active node in the system.
   * Using the page ranges provided by add_active_range(), the size of each
   * zone in each node and their holes is calculated. If the maximum PFN
   * between two adjacent zones match, it is assumed that the zone is empty.
   * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
   * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
   * starts where the previous one ended. For example, ZONE_DMA32 starts
   * at arch_max_dma_pfn.
   */
  void __init free_area_init_nodes(unsigned long *max_zone_pfn)
  {
  	unsigned long nid;
  	enum zone_type i;
  
  	/* Sort early_node_map as initialisation assumes it is sorted */
  	sort_node_map();
  
  	/* Record where the zone boundaries are */
  	memset(arch_zone_lowest_possible_pfn, 0,
  				sizeof(arch_zone_lowest_possible_pfn));
  	memset(arch_zone_highest_possible_pfn, 0,
  				sizeof(arch_zone_highest_possible_pfn));
  	arch_zone_lowest_possible_pfn[0] = find_min_pfn_with_active_regions();
  	arch_zone_highest_possible_pfn[0] = max_zone_pfn[0];
  	for (i = 1; i < MAX_NR_ZONES; i++) {
  		arch_zone_lowest_possible_pfn[i] =
  			arch_zone_highest_possible_pfn[i-1];
  		arch_zone_highest_possible_pfn[i] =
  			max(max_zone_pfn[i], arch_zone_lowest_possible_pfn[i]);
  	}
  
  	/* Print out the zone ranges */
  	printk("Zone PFN ranges:\n");
  	for (i = 0; i < MAX_NR_ZONES; i++)
  		printk("  %-8s %8lu -> %8lu\n",
  				zone_names[i],
  				arch_zone_lowest_possible_pfn[i],
  				arch_zone_highest_possible_pfn[i]);
  
  	/* Print out the early_node_map[] */
  	printk("early_node_map[%d] active PFN ranges\n", nr_nodemap_entries);
  	for (i = 0; i < nr_nodemap_entries; i++)
  		printk("  %3d: %8lu -> %8lu\n", early_node_map[i].nid,
  						early_node_map[i].start_pfn,
  						early_node_map[i].end_pfn);
  
  	/* Initialise every node */
  	setup_nr_node_ids();
  	for_each_online_node(nid) {
  		pg_data_t *pgdat = NODE_DATA(nid);
  		free_area_init_node(nid, pgdat, NULL,
  				find_min_pfn_for_node(nid), NULL);
  	}
  }
  #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
  
  /**
   * set_dma_reserve - set the specified number of pages reserved in the first zone
   * @new_dma_reserve: The number of pages to mark reserved
   *
   * The per-cpu batchsize and zone watermarks are determined by present_pages.
   * In the DMA zone, a significant percentage may be consumed by kernel image
   * and other unfreeable allocations which can skew the watermarks badly. This
   * function may optionally be used to account for unfreeable pages in the
   * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
   * smaller per-cpu batchsize.
   */
  void __init set_dma_reserve(unsigned long new_dma_reserve)
  {
  	dma_reserve = new_dma_reserve;
  }
  
  #ifndef CONFIG_NEED_MULTIPLE_NODES
  static bootmem_data_t contig_bootmem_data;
  struct pglist_data contig_page_data = { .bdata = &contig_bootmem_data };
  
  EXPORT_SYMBOL(contig_page_data);
  #endif
  
  void __init free_area_init(unsigned long *zones_size)
  {
  	free_area_init_node(0, NODE_DATA(0), zones_size,
  			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
  }
  
  static int page_alloc_cpu_notify(struct notifier_block *self,
  				 unsigned long action, void *hcpu)
  {
  	int cpu = (unsigned long)hcpu;
  
  	if (action == CPU_DEAD) {
  		local_irq_disable();
  		__drain_pages(cpu);
  		vm_events_fold_cpu(cpu);
  		local_irq_enable();
  		refresh_cpu_vm_stats(cpu);
  	}
  	return NOTIFY_OK;
  }
  
  void __init page_alloc_init(void)
  {
  	hotcpu_notifier(page_alloc_cpu_notify, 0);
  }
  
  /*
   * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
   *	or min_free_kbytes changes.
   */
  static void calculate_totalreserve_pages(void)
  {
  	struct pglist_data *pgdat;
  	unsigned long reserve_pages = 0;
  	enum zone_type i, j;
  
  	for_each_online_pgdat(pgdat) {
  		for (i = 0; i < MAX_NR_ZONES; i++) {
  			struct zone *zone = pgdat->node_zones + i;
  			unsigned long max = 0;
  
  			/* Find valid and maximum lowmem_reserve in the zone */
  			for (j = i; j < MAX_NR_ZONES; j++) {
  				if (zone->lowmem_reserve[j] > max)
  					max = zone->lowmem_reserve[j];
  			}
  
  			/* we treat pages_high as reserved pages. */
  			max += zone->pages_high;
  
  			if (max > zone->present_pages)
  				max = zone->present_pages;
  			reserve_pages += max;
  		}
  	}
  	totalreserve_pages = reserve_pages;
  }
  
  /*
   * setup_per_zone_lowmem_reserve - called whenever
   *	sysctl_lower_zone_reserve_ratio changes.  Ensures that each zone
   *	has a correct pages reserved value, so an adequate number of
   *	pages are left in the zone after a successful __alloc_pages().
   */
  static void setup_per_zone_lowmem_reserve(void)
  {
  	struct pglist_data *pgdat;
  	enum zone_type j, idx;
  
  	for_each_online_pgdat(pgdat) {
  		for (j = 0; j < MAX_NR_ZONES; j++) {
  			struct zone *zone = pgdat->node_zones + j;
  			unsigned long present_pages = zone->present_pages;
  
  			zone->lowmem_reserve[j] = 0;
  
  			idx = j;
  			while (idx) {
  				struct zone *lower_zone;
  
  				idx--;
  
  				if (sysctl_lowmem_reserve_ratio[idx] < 1)
  					sysctl_lowmem_reserve_ratio[idx] = 1;
  
  				lower_zone = pgdat->node_zones + idx;
  				lower_zone->lowmem_reserve[j] = present_pages /
  					sysctl_lowmem_reserve_ratio[idx];
  				present_pages += lower_zone->present_pages;
  			}
  		}
  	}
  
  	/* update totalreserve_pages */
  	calculate_totalreserve_pages();
  }
  
  /**
   * setup_per_zone_pages_min - called when min_free_kbytes changes.
   *
   * Ensures that the pages_{min,low,high} values for each zone are set correctly
   * with respect to min_free_kbytes.
   */
  void setup_per_zone_pages_min(void)
  {
  	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
  	unsigned long lowmem_pages = 0;
  	struct zone *zone;
  	unsigned long flags;
  
  	/* Calculate total number of !ZONE_HIGHMEM pages */
  	for_each_zone(zone) {
  		if (!is_highmem(zone))
  			lowmem_pages += zone->present_pages;
  	}
  
  	for_each_zone(zone) {
  		u64 tmp;
  
  		spin_lock_irqsave(&zone->lru_lock, flags);
  		tmp = (u64)pages_min * zone->present_pages;
  		do_div(tmp, lowmem_pages);
  		if (is_highmem(zone)) {
  			/*
  			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
  			 * need highmem pages, so cap pages_min to a small
  			 * value here.
  			 *
  			 * The (pages_high-pages_low) and (pages_low-pages_min)
  			 * deltas controls asynch page reclaim, and so should
  			 * not be capped for highmem.
  			 */
  			int min_pages;
  
  			min_pages = zone->present_pages / 1024;
  			if (min_pages < SWAP_CLUSTER_MAX)
  				min_pages = SWAP_CLUSTER_MAX;
  			if (min_pages > 128)
  				min_pages = 128;
  			zone->pages_min = min_pages;
  		} else {
  			/*
  			 * If it's a lowmem zone, reserve a number of pages
  			 * proportionate to the zone's size.
  			 */
  			zone->pages_min = tmp;
  		}
  
  		zone->pages_low   = zone->pages_min + (tmp >> 2);
  		zone->pages_high  = zone->pages_min + (tmp >> 1);
  		spin_unlock_irqrestore(&zone->lru_lock, flags);
  	}
  
  	/* update totalreserve_pages */
  	calculate_totalreserve_pages();
  }
  
  /*
   * Initialise min_free_kbytes.
   *
   * For small machines we want it small (128k min).  For large machines
   * we want it large (64MB max).  But it is not linear, because network
   * bandwidth does not increase linearly with machine size.  We use
   *
   * 	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
   *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
   *
   * which yields
   *
   * 16MB:	512k
   * 32MB:	724k
   * 64MB:	1024k
   * 128MB:	1448k
   * 256MB:	2048k
   * 512MB:	2896k
   * 1024MB:	4096k
   * 2048MB:	5792k
   * 4096MB:	8192k
   * 8192MB:	11584k
   * 16384MB:	16384k
   */
  static int __init init_per_zone_pages_min(void)
  {
  	unsigned long lowmem_kbytes;
  
  	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
  
  	min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
  	if (min_free_kbytes < 128)
  		min_free_kbytes = 128;
  	if (min_free_kbytes > 65536)
  		min_free_kbytes = 65536;
  	setup_per_zone_pages_min();
  	setup_per_zone_lowmem_reserve();
  	return 0;
  }
  module_init(init_per_zone_pages_min)
  
  /*
   * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so 
   *	that we can call two helper functions whenever min_free_kbytes
   *	changes.
   */
  int min_free_kbytes_sysctl_handler(ctl_table *table, int write, 
  	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  {
  	proc_dointvec(table, write, file, buffer, length, ppos);
  	setup_per_zone_pages_min();
  	return 0;
  }
  
  #ifdef CONFIG_NUMA
  int sysctl_min_unmapped_ratio_sysctl_handler(ctl_table *table, int write,
  	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  {
  	struct zone *zone;
  	int rc;
  
  	rc = proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  	if (rc)
  		return rc;
  
  	for_each_zone(zone)
  		zone->min_unmapped_pages = (zone->present_pages *
  				sysctl_min_unmapped_ratio) / 100;
  	return 0;
  }
  
  int sysctl_min_slab_ratio_sysctl_handler(ctl_table *table, int write,
  	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  {
  	struct zone *zone;
  	int rc;
  
  	rc = proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  	if (rc)
  		return rc;
  
  	for_each_zone(zone)
  		zone->min_slab_pages = (zone->present_pages *
  				sysctl_min_slab_ratio) / 100;
  	return 0;
  }
  #endif
  
  /*
   * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
   *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
   *	whenever sysctl_lowmem_reserve_ratio changes.
   *
   * The reserve ratio obviously has absolutely no relation with the
   * pages_min watermarks. The lowmem reserve ratio can only make sense
   * if in function of the boot time zone sizes.
   */
  int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write,
  	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  {
  	proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  	setup_per_zone_lowmem_reserve();
  	return 0;
  }
  
  /*
   * percpu_pagelist_fraction - changes the pcp->high for each zone on each
   * cpu.  It is the fraction of total pages in each zone that a hot per cpu pagelist
   * can have before it gets flushed back to buddy allocator.
   */
  
  int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
  	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  {
  	struct zone *zone;
  	unsigned int cpu;
  	int ret;
  
  	ret = proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  	if (!write || (ret == -EINVAL))
  		return ret;
  	for_each_zone(zone) {
  		for_each_online_cpu(cpu) {
  			unsigned long  high;
  			high = zone->present_pages / percpu_pagelist_fraction;
  			setup_pagelist_highmark(zone_pcp(zone, cpu), high);
  		}
  	}
  	return 0;
  }
  
  int hashdist = HASHDIST_DEFAULT;
  
  #ifdef CONFIG_NUMA
  static int __init set_hashdist(char *str)
  {
  	if (!str)
  		return 0;
  	hashdist = simple_strtoul(str, &str, 0);
  	return 1;
  }
  __setup("hashdist=", set_hashdist);
  #endif
  
  /*
   * allocate a large system hash table from bootmem
   * - it is assumed that the hash table must contain an exact power-of-2
   *   quantity of entries
   * - limit is the number of hash buckets, not the total allocation size
   */
  void *__init alloc_large_system_hash(const char *tablename,
  				     unsigned long bucketsize,
  				     unsigned long numentries,
  				     int scale,
  				     int flags,
  				     unsigned int *_hash_shift,
  				     unsigned int *_hash_mask,
  				     unsigned long limit)
  {
  	unsigned long long max = limit;
  	unsigned long log2qty, size;
  	void *table = NULL;
  
  	/* allow the kernel cmdline to have a say */
  	if (!numentries) {
  		/* round applicable memory size up to nearest megabyte */
  		numentries = nr_kernel_pages;
  		numentries += (1UL << (20 - PAGE_SHIFT)) - 1;
  		numentries >>= 20 - PAGE_SHIFT;
  		numentries <<= 20 - PAGE_SHIFT;
  
  		/* limit to 1 bucket per 2^scale bytes of low memory */
  		if (scale > PAGE_SHIFT)
  			numentries >>= (scale - PAGE_SHIFT);
  		else
  			numentries <<= (PAGE_SHIFT - scale);
  
  		/* Make sure we've got at least a 0-order allocation.. */
  		if (unlikely((numentries * bucketsize) < PAGE_SIZE))
  			numentries = PAGE_SIZE / bucketsize;
  	}
  	numentries = roundup_pow_of_two(numentries);
  
  	/* limit allocation size to 1/16 total memory by default */
  	if (max == 0) {
  		max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
  		do_div(max, bucketsize);
  	}
  
  	if (numentries > max)
  		numentries = max;
  
  	log2qty = ilog2(numentries);
  
  	do {
  		size = bucketsize << log2qty;
  		if (flags & HASH_EARLY)
  			table = alloc_bootmem(size);
  		else if (hashdist)
  			table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
  		else {
  			unsigned long order;
  			for (order = 0; ((1UL << order) << PAGE_SHIFT) < size; order++)
  				;
  			table = (void*) __get_free_pages(GFP_ATOMIC, order);
  		}
  	} while (!table && size > PAGE_SIZE && --log2qty);
  
  	if (!table)
  		panic("Failed to allocate %s hash table\n", tablename);
  
  	printk("%s hash table entries: %d (order: %d, %lu bytes)\n",
  	       tablename,
  	       (1U << log2qty),
  	       ilog2(size) - PAGE_SHIFT,
  	       size);
  
  	if (_hash_shift)
  		*_hash_shift = log2qty;
  	if (_hash_mask)
  		*_hash_mask = (1 << log2qty) - 1;
  
  	return table;
  }
  
  #ifdef CONFIG_OUT_OF_LINE_PFN_TO_PAGE
  struct page *pfn_to_page(unsigned long pfn)
  {
  	return __pfn_to_page(pfn);
  }
  unsigned long page_to_pfn(struct page *page)
  {
  	return __page_to_pfn(page);
  }
  EXPORT_SYMBOL(pfn_to_page);
  EXPORT_SYMBOL(page_to_pfn);
  #endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */
  
  
  