/*
 *  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
 */

#include <linux/config.h>
#include <linux/kernel_stat.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/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>

unsigned long totalram_pages;
unsigned long totalhigh_pages;
int nr_swap_pages;
pg_data_t *pgdat_list;

/*
 * Used by page_zone() to look up the address of the struct zone whose
 * id is encoded in the upper bits of page->flags
 */
struct zone *zone_table[MAX_NR_ZONES*MAX_NR_NODES];
EXPORT_SYMBOL(zone_table);

static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" };
static int zone_balance_ratio[MAX_NR_ZONES] __initdata = { 128, 128, 128, };
static int zone_balance_min[MAX_NR_ZONES] __initdata = { 20 , 20, 20, };
static int zone_balance_max[MAX_NR_ZONES] __initdata = { 255 , 255, 255, };

/*
 * Temporary debugging check for pages not lying within a given zone.
 */
static inline int bad_range(struct zone *zone, struct page *page)
{
        if (page_to_pfn(page) >= zone->zone_start_pfn + zone->size)
                return 1;
        if (page_to_pfn(page) < zone->zone_start_pfn)
                return 1;
        if (zone != page_zone(page))
                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 one bit for each pair of blocks, which
 * is set to 1 iff only one of the pair is allocated.  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
 */

void __free_pages_ok (struct page *page, unsigned int order)
{
        unsigned long index, page_idx, mask, flags;
        free_area_t *area;
        struct page *base;
        struct zone *zone;

        KERNEL_STAT_ADD(pgfree, 1<<order);

        BUG_ON(PageLRU(page));
        BUG_ON(PagePrivate(page));
        BUG_ON(page->mapping != NULL);
        BUG_ON(PageLocked(page));
        BUG_ON(PageActive(page));
        BUG_ON(PageWriteback(page));
        BUG_ON(page->pte.direct != 0);
        if (PageDirty(page))
                ClearPageDirty(page);
        BUG_ON(page_count(page) != 0);

        if (unlikely(current->flags & PF_FREE_PAGES)) {
                if (!current->nr_local_pages && !in_interrupt()) {
                        list_add(&page->list, &current->local_pages);
                        page->index = order;
                        current->nr_local_pages++;
                        goto out;
                }
        }

        zone = page_zone(page);

        mask = (~0UL) << order;
        base = zone->zone_mem_map;
        page_idx = page - base;
        if (page_idx & ~mask)
                BUG();
        index = page_idx >> (1 + order);
        area = zone->free_area + order;

        spin_lock_irqsave(&zone->lock, flags);
        zone->free_pages -= mask;
        while (mask + (1 << (MAX_ORDER-1))) {
                struct page *buddy1, *buddy2;

                BUG_ON(area >= zone->free_area + MAX_ORDER);
                if (!__test_and_change_bit(index, area->map))
                        /*
                         * the buddy page is still allocated.
                         */
                        break;
                /*
                 * Move the buddy up one level.
                 * This code is taking advantage of the identity:
                 *      -mask = 1+~mask
                 */
                buddy1 = base + (page_idx ^ -mask);
                buddy2 = base + page_idx;
                BUG_ON(bad_range(zone, buddy1));
                BUG_ON(bad_range(zone, buddy2));
                list_del(&buddy1->list);
                mask <<= 1;
                area++;
                index >>= 1;
                page_idx &= mask;
        }
        list_add(&(base + page_idx)->list, &area->free_list);
        spin_unlock_irqrestore(&zone->lock, flags);
out:
        return;
}

#define MARK_USED(index, order, area) \
        __change_bit((index) >> (1+(order)), (area)->map)

static inline struct page *
expand(struct zone *zone, struct page *page,
         unsigned long index, int low, int high, free_area_t * area)
{
        unsigned long size = 1 << high;

        while (high > low) {
                BUG_ON(bad_range(zone, page));
                area--;
                high--;
                size >>= 1;
                list_add(&page->list, &area->free_list);
                MARK_USED(index, high, area);
                index += size;
                page += size;
        }
        BUG_ON(bad_range(zone, page));
        return page;
}

/*
 * This page is about to be returned from the page allocator
 */
static inline void prep_new_page(struct page *page)
{
        BUG_ON(page->mapping);
        BUG_ON(PagePrivate(page));
        BUG_ON(PageLocked(page));
        BUG_ON(PageLRU(page));
        BUG_ON(PageActive(page));
        BUG_ON(PageDirty(page));
        BUG_ON(PageWriteback(page));
        BUG_ON(page->pte.direct != 0);
        page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
                        1 << PG_referenced | 1 << PG_arch_1 |
                        1 << PG_checked);
        set_page_count(page, 1);
}

static struct page *rmqueue(struct zone *zone, unsigned int order)
{
        free_area_t * area = zone->free_area + order;
        unsigned int curr_order = order;
        struct list_head *head, *curr;
        unsigned long flags;
        struct page *page;

        spin_lock_irqsave(&zone->lock, flags);
        do {
                head = &area->free_list;
                curr = head->next;

                if (curr != head) {
                        unsigned int index;

                        page = list_entry(curr, struct page, list);
                        BUG_ON(bad_range(zone, page));
                        list_del(curr);
                        index = page - zone->zone_mem_map;
                        if (curr_order != MAX_ORDER-1)
                                MARK_USED(index, curr_order, area);
                        zone->free_pages -= 1UL << order;

                        page = expand(zone, page, index, order, curr_order, area);
                        spin_unlock_irqrestore(&zone->lock, flags);

                        if (bad_range(zone, page))
                                BUG();
                        prep_new_page(page);
                        return page;    
                }
                curr_order++;
                area++;
        } while (curr_order < MAX_ORDER);
        spin_unlock_irqrestore(&zone->lock, flags);

        return NULL;
}

#ifdef CONFIG_SOFTWARE_SUSPEND
int is_head_of_free_region(struct page *page)
{
        struct zone *zone = page_zone(page);
        unsigned long flags;
        int order;
        struct list_head *curr;

        /*
         * Should not matter as we need quiescent system for
         * suspend anyway, but...
         */
        spin_lock_irqsave(&zone->lock, flags);
        for (order = MAX_ORDER - 1; order >= 0; --order)
                list_for_each(curr, &zone->free_area[order].free_list)
                        if (page == list_entry(curr, struct page, list)) {
                                spin_unlock_irqrestore(&zone->lock, flags);
                                return 1 << order;
                        }
        spin_unlock_irqrestore(&zone->lock, flags);
        return 0;
}
#endif /* CONFIG_SOFTWARE_SUSPEND */

static /* inline */ struct page *
balance_classzone(struct zone* classzone, unsigned int gfp_mask,
                        unsigned int order, int * freed)
{
        struct page * page = NULL;
        int __freed = 0;

        BUG_ON(in_interrupt());

        current->allocation_order = order;
        current->flags |= PF_MEMALLOC | PF_FREE_PAGES;

        __freed = try_to_free_pages(classzone, gfp_mask, order);

        current->flags &= ~(PF_MEMALLOC | PF_FREE_PAGES);

        if (current->nr_local_pages) {
                struct list_head * entry, * local_pages;
                struct page * tmp;
                int nr_pages;

                local_pages = &current->local_pages;

                if (likely(__freed)) {
                        /* pick from the last inserted so we're lifo */
                        entry = local_pages->next;
                        do {
                                tmp = list_entry(entry, struct page, list);
                                if (tmp->index == order && memclass(page_zone(tmp), classzone)) {
                                        list_del(entry);
                                        page = tmp;
                                        current->nr_local_pages--;
                                        prep_new_page(page);
                                        break;
                                }
                        } while ((entry = entry->next) != local_pages);
                }

                nr_pages = current->nr_local_pages;
                /* free in reverse order so that the global order will be lifo */
                while ((entry = local_pages->prev) != local_pages) {
                        list_del(entry);
                        tmp = list_entry(entry, struct page, list);
                        __free_pages_ok(tmp, tmp->index);
                        if (!nr_pages--)
                                BUG();
                }
                current->nr_local_pages = 0;
        }
        *freed = __freed;
        return page;
}

/*
 * This is the 'heart' of the zoned buddy allocator:
 */
struct page *
__alloc_pages(unsigned int gfp_mask, unsigned int order,
                struct zonelist *zonelist)
{
        unsigned long min;
        struct zone **zones, *classzone;
        struct page * page;
        int freed, i;

        KERNEL_STAT_ADD(pgalloc, 1<<order);

        zones = zonelist->zones;  /* the list of zones suitable for gfp_mask */
        classzone = zones[0]; 
        if (classzone == NULL)    /* no zones in the zonelist */
                return NULL;

        /* Go through the zonelist once, looking for a zone with enough free */
        min = 1UL << order;
        for (i = 0; zones[i] != NULL; i++) {
                struct zone *z = zones[i];

                /* the incremental min is allegedly to discourage fallback */
                min += z->pages_low;
                if (z->free_pages > min || z->free_pages >= z->pages_high) {
                        page = rmqueue(z, order);
                        if (page)
                                return page;
                }
        }

        classzone->need_balance = 1;
        mb();
        /* we're somewhat low on memory, failed to find what we needed */
        if (waitqueue_active(&kswapd_wait))
                wake_up_interruptible(&kswapd_wait);

        /* Go through the zonelist again, taking __GFP_HIGH into account */
        min = 1UL << order;
        for (i = 0; zones[i] != NULL; i++) {
                unsigned long local_min;
                struct zone *z = zones[i];

                local_min = z->pages_min;
                if (gfp_mask & __GFP_HIGH)
                        local_min >>= 2;
                min += local_min;
                if (z->free_pages > min || z->free_pages >= z->pages_high) {
                        page = rmqueue(z, order);
                        if (page)
                                return page;
                }
        }

        /* here we're in the low on memory slow path */

rebalance:
        if (current->flags & (PF_MEMALLOC | PF_MEMDIE)) {
                /* go through the zonelist yet again, ignoring mins */
                for (i = 0; zones[i] != NULL; i++) {
                        struct zone *z = zones[i];

                        page = rmqueue(z, order);
                        if (page)
                                return page;
                }
nopage:
                if (!(current->flags & PF_NOWARN)) {
                        printk("%s: page allocation failure."
                                " order:%d, mode:0x%x\n",
                                current->comm, order, gfp_mask);
                }
                return NULL;
        }

        /* Atomic allocations - we can't balance anything */
        if (!(gfp_mask & __GFP_WAIT))
                goto nopage;

        KERNEL_STAT_INC(allocstall);
        page = balance_classzone(classzone, gfp_mask, order, &freed);
        if (page)
                return page;

        /* go through the zonelist yet one more time */
        min = 1UL << order;
        for (i = 0; zones[i] != NULL; i++) {
                struct zone *z = zones[i];

                min += z->pages_min;
                if (z->free_pages > min || z->free_pages >= z->pages_high) {
                        page = rmqueue(z, order);
                        if (page)
                                return page;
                }
        }

        /* Don't let big-order allocations loop */
        if (order > 3)
                goto nopage;

        /* Yield for kswapd, and try again */
        yield();
        goto rebalance;
}

/*
 * Common helper functions.
 */
unsigned long __get_free_pages(unsigned int gfp_mask, unsigned int order)
{
        struct page * page;

        page = alloc_pages(gfp_mask, order);
        if (!page)
                return 0;
        return (unsigned long) page_address(page);
}

unsigned long get_zeroed_page(unsigned int gfp_mask)
{
        struct page * page;

        page = alloc_pages(gfp_mask, 0);
        if (page) {
                void *address = page_address(page);
                clear_page(address);
                return (unsigned long) address;
        }
        return 0;
}

void __pagevec_free(struct pagevec *pvec)
{
        int i = pagevec_count(pvec);

        while (--i >= 0)
                __free_pages_ok(pvec->pages[i], 0);
}

void __free_pages(struct page *page, unsigned int order)
{
        if (!PageReserved(page) && put_page_testzero(page))
                __free_pages_ok(page, order);
}

void free_pages(unsigned long addr, unsigned int order)
{
        if (addr != 0) {
                BUG_ON(!virt_addr_valid(addr));
                __free_pages(virt_to_page(addr), order);
        }
}

/*
 * Total amount of free (allocatable) RAM:
 */
unsigned int nr_free_pages(void)
{
        unsigned int sum = 0;
        struct zone *zone;

        for_each_zone(zone)
                sum += zone->free_pages;

        return sum;
}

static unsigned int nr_free_zone_pages(int offset)
{
        pg_data_t *pgdat;
        unsigned int sum = 0;

        for_each_pgdat(pgdat) {
                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->size;
                        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_USER & GFP_ZONEMASK);
}

/*
 * Amount of free RAM allocatable within all zones
 */
unsigned int nr_free_pagecache_pages(void)
{
        return nr_free_zone_pages(GFP_HIGHUSER & GFP_ZONEMASK);
}

#if CONFIG_HIGHMEM
unsigned int nr_free_highpages (void)
{
        pg_data_t *pgdat;
        unsigned int pages = 0;

        for_each_pgdat(pgdat)
                pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages;

        return pages;
}
#endif

/*
 * Accumulate the page_state information across all CPUs.
 * The result is unavoidably approximate - it can change
 * during and after execution of this function.
 */
struct page_state page_states[NR_CPUS] __cacheline_aligned;
EXPORT_SYMBOL(page_states);

void get_page_state(struct page_state *ret)
{
        int pcpu;

        memset(ret, 0, sizeof(*ret));
        for (pcpu = 0; pcpu < NR_CPUS; pcpu++) {
                struct page_state *ps;

                if (!cpu_online(pcpu))
                        continue;

                ps = &page_states[pcpu];
                ret->nr_dirty += ps->nr_dirty;
                ret->nr_writeback += ps->nr_writeback;
                ret->nr_pagecache += ps->nr_pagecache;
                ret->nr_page_table_pages += ps->nr_page_table_pages;
                ret->nr_reverse_maps += ps->nr_reverse_maps;
                ret->nr_mapped += ps->nr_mapped;
                ret->nr_slab += ps->nr_slab;
        }
}

void get_zone_counts(unsigned long *active, unsigned long *inactive)
{
        struct zone *zone;

        *active = 0;
        *inactive = 0;
        for_each_zone(zone) {
                *active += zone->nr_active;
                *inactive += zone->nr_inactive;
        }
}

unsigned long get_page_cache_size(void)
{
        struct page_state ps;

        get_page_state(&ps);
        return ps.nr_pagecache;
}

void si_meminfo(struct sysinfo *val)
{
        val->totalram = totalram_pages;
        val->sharedram = 0;
        val->freeram = nr_free_pages();
        val->bufferram = nr_blockdev_pages();
#ifdef CONFIG_HIGHMEM
        val->totalhigh = totalhigh_pages;
        val->freehigh = nr_free_highpages();
#else
        val->totalhigh = 0;
        val->freehigh = 0;
#endif
        val->mem_unit = PAGE_SIZE;
}

#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)
{
        pg_data_t *pgdat;
        struct page_state ps;
        int type;
        unsigned long active;
        unsigned long inactive;

        get_page_state(&ps);
        get_zone_counts(&active, &inactive);

        printk("Free pages:      %6dkB (%6dkB HighMem)\n",
                K(nr_free_pages()),
                K(nr_free_highpages()));

        for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
                for (type = 0; type < MAX_NR_ZONES; ++type) {
                        struct zone *zone = &pgdat->node_zones[type];
                        printk("Zone:%s"
                                " freepages:%6lukB"
                                " min:%6lukB"
                                " low:%6lukB"
                                " high:%6lukB"
                                " active:%6lukB"
                                " inactive:%6lukB"
                                "\n",
                                zone->name,
                                K(zone->free_pages),
                                K(zone->pages_min),
                                K(zone->pages_low),
                                K(zone->pages_high),
                                K(zone->nr_active),
                                K(zone->nr_inactive)
                                );
                }

        printk("( Active:%lu inactive:%lu dirty:%lu writeback:%lu free:%u )\n",
                active,
                inactive,
                ps.nr_dirty,
                ps.nr_writeback,
                nr_free_pages());

        for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
                for (type = 0; type < MAX_NR_ZONES; type++) {
                        struct list_head *elem;
                        struct zone *zone = &pgdat->node_zones[type];
                        unsigned long nr, flags, order, total = 0;

                        if (!zone->size)
                                continue;

                        spin_lock_irqsave(&zone->lock, flags);
                        for (order = 0; order < MAX_ORDER; order++) {
                                nr = 0;
                                list_for_each(elem, &zone->free_area[order].free_list)
                                        ++nr;
                                total += nr << order;
                                printk("%lu*%lukB ", nr, K(1UL) << order);
                        }
                        spin_unlock_irqrestore(&zone->lock, flags);
                        printk("= %lukB)\n", K(total));
                }

        show_swap_cache_info();
}

/*
 * Builds allocation fallback zone lists.
 */
static int __init build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist, int j, int k)
{
        switch (k) {
                struct zone *zone;
        default:
                BUG();
        case ZONE_HIGHMEM:
                zone = pgdat->node_zones + ZONE_HIGHMEM;
                if (zone->size) {
#ifndef CONFIG_HIGHMEM
                        BUG();
#endif
                        zonelist->zones[j++] = zone;
                }
        case ZONE_NORMAL:
                zone = pgdat->node_zones + ZONE_NORMAL;
                if (zone->size)
                        zonelist->zones[j++] = zone;
        case ZONE_DMA:
                zone = pgdat->node_zones + ZONE_DMA;
                if (zone->size)
                        zonelist->zones[j++] = zone;
        }

        return j;
}

static void __init build_zonelists(pg_data_t *pgdat)
{
        int i, j, k, node, local_node;

        local_node = pgdat->node_id;
        printk("Building zonelist for node : %d\n", local_node);
        for (i = 0; i <= GFP_ZONEMASK; i++) {
                struct zonelist *zonelist;

                zonelist = pgdat->node_zonelists + i;
                memset(zonelist, 0, sizeof(*zonelist));

                j = 0;
                k = ZONE_NORMAL;
                if (i & __GFP_HIGHMEM)
                        k = ZONE_HIGHMEM;
                if (i & __GFP_DMA)
                        k = ZONE_DMA;

                j = build_zonelists_node(pgdat, zonelist, j, k);
                /*
                 * 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 < numnodes; node++)
                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
                for (node = 0; node < local_node; node++)
                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
 
                zonelist->zones[j++] = NULL;
        } 
}

void __init build_all_zonelists(void)
{
        int i;

        for(i = 0 ; i < numnodes ; i++)
                build_zonelists(NODE_DATA(i));
}

void __init calculate_totalpages (pg_data_t *pgdat, unsigned long *zones_size,
        unsigned long *zholes_size)
{
        unsigned long realtotalpages, totalpages = 0;
        int i;

        for (i = 0; i < MAX_NR_ZONES; i++)
                totalpages += zones_size[i];
        pgdat->node_size = totalpages;

        realtotalpages = totalpages;
        if (zholes_size)
                for (i = 0; i < MAX_NR_ZONES; i++)
                        realtotalpages -= zholes_size[i];
        printk("On node %d totalpages: %lu\n", pgdat->node_id, realtotalpages);
}

/*
 * 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

static inline unsigned long wait_table_size(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 size;
}

/*
 * 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))

/*
 * Set up the zone data structures:
 *   - mark all pages reserved
 *   - mark all memory queues empty
 *   - clear the memory bitmaps
 */
void __init free_area_init_core(pg_data_t *pgdat,
                unsigned long *zones_size, unsigned long *zholes_size)
{
        unsigned long i, j;
        unsigned long local_offset;
        const unsigned long zone_required_alignment = 1UL << (MAX_ORDER-1);
        int nid = pgdat->node_id;
        struct page *lmem_map = pgdat->node_mem_map;
        unsigned long zone_start_pfn = pgdat->node_start_pfn;

        pgdat->nr_zones = 0;
        local_offset = 0;                /* offset within lmem_map */
        for (j = 0; j < MAX_NR_ZONES; j++) {
                struct zone *zone = pgdat->node_zones + j;
                unsigned long mask;
                unsigned long size, realsize;

                zone_table[nid * MAX_NR_ZONES + j] = zone;
                realsize = size = zones_size[j];
                if (zholes_size)
                        realsize -= zholes_size[j];

                printk("  %s zone: %lu pages\n", zone_names[j], realsize);
                zone->size = size;
                zone->name = zone_names[j];
                spin_lock_init(&zone->lock);
                spin_lock_init(&zone->lru_lock);
                zone->zone_pgdat = pgdat;
                zone->free_pages = 0;
                zone->need_balance = 0;
                INIT_LIST_HEAD(&zone->active_list);
                INIT_LIST_HEAD(&zone->inactive_list);
                atomic_set(&zone->refill_counter, 0);
                zone->nr_active = 0;
                zone->nr_inactive = 0;
                if (!size)
                        continue;

                /*
                 * The per-page waitqueue mechanism uses hashed waitqueues
                 * per zone.
                 */
                zone->wait_table_size = wait_table_size(size);
                zone->wait_table_bits =
                        wait_table_bits(zone->wait_table_size);
                zone->wait_table = (wait_queue_head_t *)
                        alloc_bootmem_node(pgdat, zone->wait_table_size
                                                * sizeof(wait_queue_head_t));

                for(i = 0; i < zone->wait_table_size; ++i)
                        init_waitqueue_head(zone->wait_table + i);

                pgdat->nr_zones = j+1;

                mask = (realsize / zone_balance_ratio[j]);
                if (mask < zone_balance_min[j])
                        mask = zone_balance_min[j];
                else if (mask > zone_balance_max[j])
                        mask = zone_balance_max[j];
                zone->pages_min = mask;
                zone->pages_low = mask*2;
                zone->pages_high = mask*3;

                zone->zone_mem_map = lmem_map + local_offset;
                zone->zone_start_pfn = zone_start_pfn;

                if ((zone_start_pfn) & (zone_required_alignment-1))
                        printk("BUG: wrong zone alignment, it will crash\n");

                /*
                 * 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.
                 */
                for (i = 0; i < size; i++) {
                        struct page *page = lmem_map + local_offset + i;
                        set_page_zone(page, nid * MAX_NR_ZONES + j);
                        set_page_count(page, 0);
                        SetPageReserved(page);
                        INIT_LIST_HEAD(&page->list);
                        if (j != ZONE_HIGHMEM)
                                /*
                                 * The shift left won't overflow because the
                                 * ZONE_NORMAL is below 4G.
                                 */
                                set_page_address(page, __va(zone_start_pfn << PAGE_SHIFT));
                        zone_start_pfn++;
                }

                local_offset += size;
                for (i = 0; ; i++) {
                        unsigned long bitmap_size;

                        INIT_LIST_HEAD(&zone->free_area[i].free_list);
                        if (i == MAX_ORDER-1) {
                                zone->free_area[i].map = NULL;
                                break;
                        }

                        /*
                         * Page buddy system uses "index >> (i+1)",
                         * where "index" is at most "size-1".
                         *
                         * The extra "+3" is to round down to byte
                         * size (8 bits per byte assumption). Thus
                         * we get "(size-1) >> (i+4)" as the last byte
                         * we can access.
                         *
                         * The "+1" is because we want to round the
                         * byte allocation up rather than down. So
                         * we should have had a "+7" before we shifted
                         * down by three. Also, we have to add one as
                         * we actually _use_ the last bit (it's [0,n]
                         * inclusive, not [0,n[).
                         *
                         * So we actually had +7+1 before we shift
                         * down by 3. But (n+8) >> 3 == (n >> 3) + 1
                         * (modulo overflows, which we do not have).
                         *
                         * Finally, we LONG_ALIGN because all bitmap
                         * operations are on longs.
                         */
                        bitmap_size = (size-1) >> (i+4);
                        bitmap_size = LONG_ALIGN(bitmap_size+1);
                        zone->free_area[i].map = 
                          (unsigned long *) alloc_bootmem_node(pgdat, bitmap_size);
                }
        }
}

#ifndef CONFIG_DISCONTIGMEM
void __init free_area_init(unsigned long *zones_size)
{
        free_area_init_node(0, &contig_page_data, NULL, zones_size, 0, NULL);
        mem_map = contig_page_data.node_mem_map;
}
#endif

static int __init setup_mem_frac(char *str)
{
        int j = 0;

        while (get_option(&str, &zone_balance_ratio[j++]) == 2);
        printk("setup_mem_frac: ");
        for (j = 0; j < MAX_NR_ZONES; j++) printk("%d  ", zone_balance_ratio[j]);
        printk("\n");
        return 1;
}

__setup("memfrac=", setup_mem_frac);