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page_alloc.c

/*
 *  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/jiffies.h>
#include <linux/bootmem.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/oom.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 <linux/page-isolation.h>
#include <linux/page_cgroup.h>
#include <linux/debugobjects.h>
#include <linux/kmemleak.h>

#include <asm/tlbflush.h>
#include <asm/div64.h>
#include "internal.h"

/*
 * Array of node states.
 */
nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
      [N_POSSIBLE] = NODE_MASK_ALL,
      [N_ONLINE] = { { [0] = 1UL } },
#ifndef CONFIG_NUMA
      [N_NORMAL_MEMORY] = { { [0] = 1UL } },
#ifdef CONFIG_HIGHMEM
      [N_HIGH_MEMORY] = { { [0] = 1UL } },
#endif
      [N_CPU] = { { [0] = 1UL } },
#endif      /* NUMA */
};
EXPORT_SYMBOL(node_states);

unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
unsigned long highest_memmap_pfn __read_mostly;
int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;

#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
int pageblock_order __read_mostly;
#endif

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
       32,
};

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
       "Movable",
};

int min_free_kbytes = 1024;

unsigned long __meminitdata nr_kernel_pages;
unsigned long __meminitdata nr_all_pages;
static unsigned long __meminitdata dma_reserve;

#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
   * MAX_ACTIVE_REGIONS determines the maximum 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

  static struct node_active_region __meminitdata early_node_map[MAX_ACTIVE_REGIONS];
  static int __meminitdata nr_nodemap_entries;
  static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
  static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
  static unsigned long __initdata required_kernelcore;
  static unsigned long __initdata required_movablecore;
  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];

  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
  int movable_zone;
  EXPORT_SYMBOL(movable_zone);
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
int nr_online_nodes __read_mostly = 1;
EXPORT_SYMBOL(nr_node_ids);
EXPORT_SYMBOL(nr_online_nodes);
#endif

int page_group_by_mobility_disabled __read_mostly;

static void set_pageblock_migratetype(struct page *page, int migratetype)
{

      if (unlikely(page_group_by_mobility_disabled))
            migratetype = MIGRATE_UNMOVABLE;

      set_pageblock_flags_group(page, (unsigned long)migratetype,
                              PB_migrate, PB_migrate_end);
}

bool oom_killer_disabled __read_mostly;

#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)
{
      if (!pfn_valid_within(page_to_pfn(page)))
            return 0;
      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)
{
      static unsigned long resume;
      static unsigned long nr_shown;
      static unsigned long nr_unshown;

      /*
       * Allow a burst of 60 reports, then keep quiet for that minute;
       * or allow a steady drip of one report per second.
       */
      if (nr_shown == 60) {
            if (time_before(jiffies, resume)) {
                  nr_unshown++;
                  goto out;
            }
            if (nr_unshown) {
                  printk(KERN_ALERT
                        "BUG: Bad page state: %lu messages suppressed\n",
                        nr_unshown);
                  nr_unshown = 0;
            }
            nr_shown = 0;
      }
      if (nr_shown++ == 0)
            resume = jiffies + 60 * HZ;

      printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
            current->comm, page_to_pfn(page));
      printk(KERN_ALERT
            "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
            page, (void *)page->flags, page_count(page),
            page_mapcount(page), page->mapping, page->index);

      dump_stack();
out:
      /* Leave bad fields for debug, except PageBuddy could make trouble */
      __ClearPageBuddy(page);
      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, compound_order(page));
}

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);
      set_compound_order(page, order);
      __SetPageHead(page);
      for (i = 1; i < nr_pages; i++) {
            struct page *p = page + i;

            __SetPageTail(p);
            p->first_page = page;
      }
}

static int destroy_compound_page(struct page *page, unsigned long order)
{
      int i;
      int nr_pages = 1 << order;
      int bad = 0;

      if (unlikely(compound_order(page) != order) ||
          unlikely(!PageHead(page))) {
            bad_page(page);
            bad++;
      }

      __ClearPageHead(page);

      for (i = 1; i < nr_pages; i++) {
            struct page *p = page + i;

            if (unlikely(!PageTail(p) || (p->first_page != page))) {
                  bad_page(page);
                  bad++;
            }
            __ClearPageTail(p);
      }

      return bad;
}

static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
{
      int i;

      /*
       * 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);
}

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)
{
      if (!pfn_valid_within(page_to_pfn(buddy)))
            return 0;

      if (page_zone_id(page) != page_zone_id(buddy))
            return 0;

      if (PageBuddy(buddy) && page_order(buddy) == order) {
            VM_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,
            int migratetype)
{
      unsigned long page_idx;

      if (unlikely(PageCompound(page)))
            if (unlikely(destroy_compound_page(page, order)))
                  return;

      VM_BUG_ON(migratetype == -1);

      page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);

      VM_BUG_ON(page_idx & ((1 << order) - 1));
      VM_BUG_ON(bad_range(zone, page));

      while (order < MAX_ORDER-1) {
            unsigned long combined_idx;
            struct page *buddy;

            buddy = __page_find_buddy(page, page_idx, order);
            if (!page_is_buddy(page, buddy, order))
                  break;

            /* Our buddy is free, merge with it and move up one order. */
            list_del(&buddy->lru);
            zone->free_area[order].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[migratetype]);
      zone->free_area[order].nr_free++;
}

#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
/*
 * free_page_mlock() -- clean up attempts to free and mlocked() page.
 * Page should not be on lru, so no need to fix that up.
 * free_pages_check() will verify...
 */
static inline void free_page_mlock(struct page *page)
{
      __dec_zone_page_state(page, NR_MLOCK);
      __count_vm_event(UNEVICTABLE_MLOCKFREED);
}
#else
static void free_page_mlock(struct page *page) { }
#endif

static inline int free_pages_check(struct page *page)
{
      if (unlikely(page_mapcount(page) |
            (page->mapping != NULL)  |
            (atomic_read(&page->_count) != 0) |
            (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
            bad_page(page);
            return 1;
      }
      if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
            page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
      return 0;
}

/*
 * 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_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
      zone->pages_scanned = 0;

      __mod_zone_page_state(zone, NR_FREE_PAGES, count << order);
      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, page_private(page));
      }
      spin_unlock(&zone->lock);
}

static void free_one_page(struct zone *zone, struct page *page, int order,
                        int migratetype)
{
      spin_lock(&zone->lock);
      zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
      zone->pages_scanned = 0;

      __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
      __free_one_page(page, zone, order, migratetype);
      spin_unlock(&zone->lock);
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
      unsigned long flags;
      int i;
      int bad = 0;
      int wasMlocked = TestClearPageMlocked(page);

      kmemcheck_free_shadow(page, order);

      for (i = 0 ; i < (1 << order) ; ++i)
            bad += free_pages_check(page + i);
      if (bad)
            return;

      if (!PageHighMem(page)) {
            debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
            debug_check_no_obj_freed(page_address(page),
                                 PAGE_SIZE << order);
      }
      arch_free_page(page, order);
      kernel_map_pages(page, 1 << order, 0);

      local_irq_save(flags);
      if (unlikely(wasMlocked))
            free_page_mlock(page);
      __count_vm_events(PGFREE, 1 << order);
      free_one_page(page_zone(page), page, order,
                              get_pageblock_migratetype(page));
      local_irq_restore(flags);
}

/*
 * permit the bootmem allocator to evade page validation on high-order frees
 */
void __meminit __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,
      int migratetype)
{
      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[migratetype]);
            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)  |
            (atomic_read(&page->_count) != 0)  |
            (page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
            bad_page(page);
            return 1;
      }

      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;
}

/*
 * Go through the free lists for the given migratetype and remove
 * the smallest available page from the freelists
 */
static inline
struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
                                    int migratetype)
{
      unsigned int current_order;
      struct free_area * area;
      struct page *page;

      /* Find a page of the appropriate size in the preferred list */
      for (current_order = order; current_order < MAX_ORDER; ++current_order) {
            area = &(zone->free_area[current_order]);
            if (list_empty(&area->free_list[migratetype]))
                  continue;

            page = list_entry(area->free_list[migratetype].next,
                                          struct page, lru);
            list_del(&page->lru);
            rmv_page_order(page);
            area->nr_free--;
            expand(zone, page, order, current_order, area, migratetype);
            return page;
      }

      return NULL;
}


/*
 * This array describes the order lists are fallen back to when
 * the free lists for the desirable migrate type are depleted
 */
static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
      [MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_RESERVE },
      [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_RESERVE },
      [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
      [MIGRATE_RESERVE]     = { MIGRATE_RESERVE,     MIGRATE_RESERVE,   MIGRATE_RESERVE }, /* Never used */
};

/*
 * Move the free pages in a range to the free lists of the requested type.
 * Note that start_page and end_pages are not aligned on a pageblock
 * boundary. If alignment is required, use move_freepages_block()
 */
static int move_freepages(struct zone *zone,
                    struct page *start_page, struct page *end_page,
                    int migratetype)
{
      struct page *page;
      unsigned long order;
      int pages_moved = 0;

#ifndef CONFIG_HOLES_IN_ZONE
      /*
       * page_zone is not safe to call in this context when
       * CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant
       * anyway as we check zone boundaries in move_freepages_block().
       * Remove at a later date when no bug reports exist related to
       * grouping pages by mobility
       */
      BUG_ON(page_zone(start_page) != page_zone(end_page));
#endif

      for (page = start_page; page <= end_page;) {
            /* Make sure we are not inadvertently changing nodes */
            VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));

            if (!pfn_valid_within(page_to_pfn(page))) {
                  page++;
                  continue;
            }

            if (!PageBuddy(page)) {
                  page++;
                  continue;
            }

            order = page_order(page);
            list_del(&page->lru);
            list_add(&page->lru,
                  &zone->free_area[order].free_list[migratetype]);
            page += 1 << order;
            pages_moved += 1 << order;
      }

      return pages_moved;
}

static int move_freepages_block(struct zone *zone, struct page *page,
                        int migratetype)
{
      unsigned long start_pfn, end_pfn;
      struct page *start_page, *end_page;

      start_pfn = page_to_pfn(page);
      start_pfn = start_pfn & ~(pageblock_nr_pages-1);
      start_page = pfn_to_page(start_pfn);
      end_page = start_page + pageblock_nr_pages - 1;
      end_pfn = start_pfn + pageblock_nr_pages - 1;

      /* Do not cross zone boundaries */
      if (start_pfn < zone->zone_start_pfn)
            start_page = page;
      if (end_pfn >= zone->zone_start_pfn + zone->spanned_pages)
            return 0;

      return move_freepages(zone, start_page, end_page, migratetype);
}

/* Remove an element from the buddy allocator from the fallback list */
static inline struct page *
__rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
{
      struct free_area * area;
      int current_order;
      struct page *page;
      int migratetype, i;

      /* Find the largest possible block of pages in the other list */
      for (current_order = MAX_ORDER-1; current_order >= order;
                                    --current_order) {
            for (i = 0; i < MIGRATE_TYPES - 1; i++) {
                  migratetype = fallbacks[start_migratetype][i];

                  /* MIGRATE_RESERVE handled later if necessary */
                  if (migratetype == MIGRATE_RESERVE)
                        continue;

                  area = &(zone->free_area[current_order]);
                  if (list_empty(&area->free_list[migratetype]))
                        continue;

                  page = list_entry(area->free_list[migratetype].next,
                              struct page, lru);
                  area->nr_free--;

                  /*
                   * If breaking a large block of pages, move all free
                   * pages to the preferred allocation list. If falling
                   * back for a reclaimable kernel allocation, be more
                   * agressive about taking ownership of free pages
                   */
                  if (unlikely(current_order >= (pageblock_order >> 1)) ||
                              start_migratetype == MIGRATE_RECLAIMABLE ||
                              page_group_by_mobility_disabled) {
                        unsigned long pages;
                        pages = move_freepages_block(zone, page,
                                                start_migratetype);

                        /* Claim the whole block if over half of it is free */
                        if (pages >= (1 << (pageblock_order-1)) ||
                                    page_group_by_mobility_disabled)
                              set_pageblock_migratetype(page,
                                                start_migratetype);

                        migratetype = start_migratetype;
                  }

                  /* Remove the page from the freelists */
                  list_del(&page->lru);
                  rmv_page_order(page);

                  if (current_order == pageblock_order)
                        set_pageblock_migratetype(page,
                                          start_migratetype);

                  expand(zone, page, order, current_order, area, migratetype);
                  return page;
            }
      }

      return NULL;
}

/*
 * 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,
                                    int migratetype)
{
      struct page *page;

retry_reserve:
      page = __rmqueue_smallest(zone, order, migratetype);

      if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
            page = __rmqueue_fallback(zone, order, migratetype);

            /*
             * Use MIGRATE_RESERVE rather than fail an allocation. goto
             * is used because __rmqueue_smallest is an inline function
             * and we want just one call site
             */
            if (!page) {
                  migratetype = MIGRATE_RESERVE;
                  goto retry_reserve;
            }
      }

      return page;
}

/* 
 * 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 migratetype, int cold)
{
      int i;
      
      spin_lock(&zone->lock);
      for (i = 0; i < count; ++i) {
            struct page *page = __rmqueue(zone, order, migratetype);
            if (unlikely(page == NULL))
                  break;

            /*
             * Split buddy pages returned by expand() are received here
             * in physical page order. The page is added to the callers and
             * list and the list head then moves forward. From the callers
             * perspective, the linked list is ordered by page number in
             * some conditions. This is useful for IO devices that can
             * merge IO requests if the physical pages are ordered
             * properly.
             */
            if (likely(cold == 0))
                  list_add(&page->lru, list);
            else
                  list_add_tail(&page->lru, list);
            set_page_private(page, migratetype);
            list = &page->lru;
      }
      __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
      spin_unlock(&zone->lock);
      return i;
}

#ifdef CONFIG_NUMA
/*
 * Called from the vmstat counter updater to drain pagesets of this
 * currently executing processor on remote nodes after they have
 * expired.
 *
 * Note that this function must be called with the thread pinned to
 * a single processor.
 */
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
      unsigned long flags;
      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

/*
 * Drain pages of the indicated processor.
 *
 * The processor must either be the current processor and the
 * thread pinned to the current processor or a processor that
 * is not online.
 */
static void drain_pages(unsigned int cpu)
{
      unsigned long flags;
      struct zone *zone;

      for_each_populated_zone(zone) {
            struct per_cpu_pageset *pset;
            struct per_cpu_pages *pcp;

            pset = zone_pcp(zone, cpu);

            pcp = &pset->pcp;
            local_irq_save(flags);
            free_pages_bulk(zone, pcp->count, &pcp->list, 0);
            pcp->count = 0;
            local_irq_restore(flags);
      }
}

/*
 * Spill all of this CPU's per-cpu pages back into the buddy allocator.
 */
void drain_local_pages(void *arg)
{
      drain_pages(smp_processor_id());
}

/*
 * Spill all the per-cpu pages from all CPUs back into the buddy allocator
 */
void drain_all_pages(void)
{
      on_each_cpu(drain_local_pages, NULL, 1);
}

#ifdef CONFIG_HIBERNATION

void mark_free_pages(struct zone *zone)
{
      unsigned long pfn, max_zone_pfn;
      unsigned long flags;
      int order, t;
      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 (!swsusp_page_is_forbidden(page))
                        swsusp_unset_page_free(page);
            }

      for_each_migratetype_order(order, t) {
            list_for_each(curr, &zone->free_area[order].free_list[t]) {
                  unsigned long i;

                  pfn = page_to_pfn(list_entry(curr, struct page, lru));
                  for (i = 0; i < (1UL << order); i++)
                        swsusp_set_page_free(pfn_to_page(pfn + i));
            }
      }
      spin_unlock_irqrestore(&zone->lock, flags);
}
#endif /* CONFIG_PM */

/*
 * Free a 0-order page
 */
static void free_hot_cold_page(struct page *page, int cold)
{
      struct zone *zone = page_zone(page);
      struct per_cpu_pages *pcp;
      unsigned long flags;
      int wasMlocked = TestClearPageMlocked(page);

      kmemcheck_free_shadow(page, 0);

      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);
            debug_check_no_obj_freed(page_address(page), PAGE_SIZE);
      }
      arch_free_page(page, 0);
      kernel_map_pages(page, 1, 0);

      pcp = &zone_pcp(zone, get_cpu())->pcp;
      set_page_private(page, get_pageblock_migratetype(page));
      local_irq_save(flags);
      if (unlikely(wasMlocked))
            free_page_mlock(page);
      __count_vm_event(PGFREE);

      if (cold)
            list_add_tail(&page->lru, &pcp->list);
      else
            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 free_hot_page(struct page *page)
{
      free_hot_cold_page(page, 0);
}
      
void 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));

#ifdef CONFIG_KMEMCHECK
      /*
       * Split shadow pages too, because free(page[0]) would
       * otherwise free the whole shadow.
       */
      if (kmemcheck_page_is_tracked(page))
            split_page(virt_to_page(page[0].shadow), order);
#endif

      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 inline
struct page *buffered_rmqueue(struct zone *preferred_zone,
                  struct zone *zone, int order, gfp_t gfp_flags,
                  int migratetype)
{
      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;
            local_irq_save(flags);
            if (!pcp->count) {
                  pcp->count = rmqueue_bulk(zone, 0,
                              pcp->batch, &pcp->list,
                              migratetype, cold);
                  if (unlikely(!pcp->count))
                        goto failed;
            }

            /* Find a page of the appropriate migrate type */
            if (cold) {
                  list_for_each_entry_reverse(page, &pcp->list, lru)
                        if (page_private(page) == migratetype)
                              break;
            } else {
                  list_for_each_entry(page, &pcp->list, lru)
                        if (page_private(page) == migratetype)
                              break;
            }

            /* Allocate more to the pcp list if necessary */
            if (unlikely(&page->lru == &pcp->list)) {
                  pcp->count += rmqueue_bulk(zone, 0,
                              pcp->batch, &pcp->list,
                              migratetype, cold);
                  page = list_entry(pcp->list.next, struct page, lru);
            }

            list_del(&page->lru);
            pcp->count--;
      } else {
            if (unlikely(gfp_flags & __GFP_NOFAIL)) {
                  /*
                   * __GFP_NOFAIL is not to be used in new code.
                   *
                   * All __GFP_NOFAIL callers should be fixed so that they
                   * properly detect and handle allocation failures.
                   *
                   * We most definitely don't want callers attempting to
                   * allocate greater than order-1 page units with
                   * __GFP_NOFAIL.
                   */
                  WARN_ON_ONCE(order > 1);
            }
            spin_lock_irqsave(&zone->lock, flags);
            page = __rmqueue(zone, order, migratetype);
            __mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << order));
            spin_unlock(&zone->lock);
            if (!page)
                  goto failed;
      }

      __count_zone_vm_events(PGALLOC, zone, 1 << order);
      zone_statistics(preferred_zone, 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;
}

/* The ALLOC_WMARK bits are used as an index to zone->watermark */
#define ALLOC_WMARK_MIN       WMARK_MIN
#define ALLOC_WMARK_LOW       WMARK_LOW
#define ALLOC_WMARK_HIGH      WMARK_HIGH
#define ALLOC_NO_WATERMARKS   0x04 /* don't check watermarks at all */

/* Mask to get the watermark bits */
#define ALLOC_WMARK_MASK      (ALLOC_NO_WATERMARKS-1)

#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;
      u32 min_order;

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

      struct dentry *ignore_gfp_highmem_file;
      struct dentry *ignore_gfp_wait_file;
      struct dentry *min_order_file;

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

} fail_page_alloc = {
      .attr = FAULT_ATTR_INITIALIZER,
      .ignore_gfp_wait = 1,
      .ignore_gfp_highmem = 1,
      .min_order = 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 (order < fail_page_alloc.min_order)
            return 0;
      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);
      fail_page_alloc.min_order_file =
            debugfs_create_u32("min-order", mode, dir,
                           &fail_page_alloc.min_order);

      if (!fail_page_alloc.ignore_gfp_wait_file ||
            !fail_page_alloc.ignore_gfp_highmem_file ||
            !fail_page_alloc.min_order_file) {
            err = -ENOMEM;
            debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
            debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
            debugfs_remove(fail_page_alloc.min_order_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 a lot 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_states[N_HIGH_MEMORY].)
 *
 * 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 (time_after(jiffies, zlc->last_full_zap + 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_states[N_HIGH_MEMORY];
      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 zoneref *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->_zonerefs;
      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 zoneref *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->_zonerefs;

      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 zoneref *z,
                        nodemask_t *allowednodes)
{
      return 1;
}

static void zlc_mark_zone_full(struct zonelist *zonelist, struct zoneref *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, nodemask_t *nodemask, unsigned int order,
            struct zonelist *zonelist, int high_zoneidx, int alloc_flags,
            struct zone *preferred_zone, int migratetype)
{
      struct zoneref *z;
      struct page *page = NULL;
      int classzone_idx;
      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 */

      classzone_idx = zone_idx(preferred_zone);
zonelist_scan:
      /*
       * Scan zonelist, looking for a zone with enough free.
       * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
       */
      for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                    high_zoneidx, nodemask) {
            if (NUMA_BUILD && zlc_active &&
                  !zlc_zone_worth_trying(zonelist, z, allowednodes))
                        continue;
            if ((alloc_flags & ALLOC_CPUSET) &&
                  !cpuset_zone_allowed_softwall(zone, gfp_mask))
                        goto try_next_zone;

            BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
            if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
                  unsigned long mark;
                  int ret;

                  mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
                  if (zone_watermark_ok(zone, order, mark,
                            classzone_idx, alloc_flags))
                        goto try_this_zone;

                  if (zone_reclaim_mode == 0)
                        goto this_zone_full;

                  ret = zone_reclaim(zone, gfp_mask, order);
                  switch (ret) {
                  case ZONE_RECLAIM_NOSCAN:
                        /* did not scan */
                        goto try_next_zone;
                  case ZONE_RECLAIM_FULL:
                        /* scanned but unreclaimable */
                        goto this_zone_full;
                  default:
                        /* did we reclaim enough */
                        if (!zone_watermark_ok(zone, order, mark,
                                    classzone_idx, alloc_flags))
                              goto this_zone_full;
                  }
            }

try_this_zone:
            page = buffered_rmqueue(preferred_zone, zone, order,
                                    gfp_mask, migratetype);
            if (page)
                  break;
this_zone_full:
            if (NUMA_BUILD)
                  zlc_mark_zone_full(zonelist, z);
try_next_zone:
            if (NUMA_BUILD && !did_zlc_setup && nr_online_nodes > 1) {
                  /*
                   * we do zlc_setup after the first zone is tried but only
                   * if there are multiple nodes make it worthwhile
                   */
                  allowednodes = zlc_setup(zonelist, alloc_flags);
                  zlc_active = 1;
                  did_zlc_setup = 1;
            }
      }

      if (unlikely(NUMA_BUILD && page == NULL && zlc_active)) {
            /* Disable zlc cache for second zonelist scan */
            zlc_active = 0;
            goto zonelist_scan;
      }
      return page;
}

static inline int
should_alloc_retry(gfp_t gfp_mask, unsigned int order,
                        unsigned long pages_reclaimed)
{
      /* Do not loop if specifically requested */
      if (gfp_mask & __GFP_NORETRY)
            return 0;

      /*
       * In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
       * means __GFP_NOFAIL, but that may not be true in other
       * implementations.
       */
      if (order <= PAGE_ALLOC_COSTLY_ORDER)
            return 1;

      /*
       * For order > PAGE_ALLOC_COSTLY_ORDER, if __GFP_REPEAT is
       * specified, then we retry until we no longer reclaim any pages
       * (above), or we've reclaimed an order of pages at least as
       * large as the allocation's order. In both cases, if the
       * allocation still fails, we stop retrying.
       */
      if (gfp_mask & __GFP_REPEAT && pages_reclaimed < (1 << order))
            return 1;

      /*
       * Don't let big-order allocations loop unless the caller
       * explicitly requests that.
       */
      if (gfp_mask & __GFP_NOFAIL)
            return 1;

      return 0;
}

static inline struct page *
__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
      struct zonelist *zonelist, enum zone_type high_zoneidx,
      nodemask_t *nodemask, struct zone *preferred_zone,
      int migratetype)
{
      struct page *page;

      /* Acquire the OOM killer lock for the zones in zonelist */
      if (!try_set_zone_oom(zonelist, gfp_mask)) {
            schedule_timeout_uninterruptible(1);
            return NULL;
      }

      /*
       * 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, nodemask,
            order, zonelist, high_zoneidx,
            ALLOC_WMARK_HIGH|ALLOC_CPUSET,
            preferred_zone, migratetype);
      if (page)
            goto out;

      /* The OOM killer will not help higher order allocs */
      if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_NOFAIL))
            goto out;

      /* Exhausted what can be done so it's blamo time */
      out_of_memory(zonelist, gfp_mask, order);

out:
      clear_zonelist_oom(zonelist, gfp_mask);
      return page;
}

/* The really slow allocator path where we enter direct reclaim */
static inline struct page *
__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
      struct zonelist *zonelist, enum zone_type high_zoneidx,
      nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
      int migratetype, unsigned long *did_some_progress)
{
      struct page *page = NULL;
      struct reclaim_state reclaim_state;
      struct task_struct *p = current;

      cond_resched();

      /* We now go into synchronous reclaim */
      cpuset_memory_pressure_bump();

      /*
       * The task's cpuset might have expanded its set of allowable nodes
       */
      p->flags |= PF_MEMALLOC;
      lockdep_set_current_reclaim_state(gfp_mask);
      reclaim_state.reclaimed_slab = 0;
      p->reclaim_state = &reclaim_state;

      *did_some_progress = try_to_free_pages(zonelist, order, gfp_mask, nodemask);

      p->reclaim_state = NULL;
      lockdep_clear_current_reclaim_state();
      p->flags &= ~PF_MEMALLOC;

      cond_resched();

      if (order != 0)
            drain_all_pages();

      if (likely(*did_some_progress))
            page = get_page_from_freelist(gfp_mask, nodemask, order,
                              zonelist, high_zoneidx,
                              alloc_flags, preferred_zone,
                              migratetype);
      return page;
}

/*
 * This is called in the allocator slow-path if the allocation request is of
 * sufficient urgency to ignore watermarks and take other desperate measures
 */
static inline struct page *
__alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
      struct zonelist *zonelist, enum zone_type high_zoneidx,
      nodemask_t *nodemask, struct zone *preferred_zone,
      int migratetype)
{
      struct page *page;

      do {
            page = get_page_from_freelist(gfp_mask, nodemask, order,
                  zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,
                  preferred_zone, migratetype);

            if (!page && gfp_mask & __GFP_NOFAIL)
                  congestion_wait(BLK_RW_ASYNC, HZ/50);
      } while (!page && (gfp_mask & __GFP_NOFAIL));

      return page;
}

static inline
void wake_all_kswapd(unsigned int order, struct zonelist *zonelist,
                                    enum zone_type high_zoneidx)
{
      struct zoneref *z;
      struct zone *zone;

      for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
            wakeup_kswapd(zone, order);
}

static inline int
gfp_to_alloc_flags(gfp_t gfp_mask)
{
      struct task_struct *p = current;
      int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
      const gfp_t wait = gfp_mask & __GFP_WAIT;

      /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
      BUILD_BUG_ON(__GFP_HIGH != ALLOC_HIGH);

      /*
       * 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 |= (gfp_mask & __GFP_HIGH);

      if (!wait) {
            alloc_flags |= ALLOC_HARDER;
            /*
             * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
             * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
             */
            alloc_flags &= ~ALLOC_CPUSET;
      } else if (unlikely(rt_task(p)))
            alloc_flags |= ALLOC_HARDER;

      if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
            if (!in_interrupt() &&
                ((p->flags & PF_MEMALLOC) ||
                 unlikely(test_thread_flag(TIF_MEMDIE))))
                  alloc_flags |= ALLOC_NO_WATERMARKS;
      }

      return alloc_flags;
}

static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
      struct zonelist *zonelist, enum zone_type high_zoneidx,
      nodemask_t *nodemask, struct zone *preferred_zone,
      int migratetype)
{
      const gfp_t wait = gfp_mask & __GFP_WAIT;
      struct page *page = NULL;
      int alloc_flags;
      unsigned long pages_reclaimed = 0;
      unsigned long did_some_progress;
      struct task_struct *p = current;

      /*
       * In the slowpath, we sanity check order to avoid ever trying to
       * reclaim >= MAX_ORDER areas which will never succeed. Callers may
       * be using allocators in order of preference for an area that is
       * too large.
       */
      if (order >= MAX_ORDER) {
            WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
            return NULL;
      }

      /*
       * 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;

      wake_all_kswapd(order, zonelist, high_zoneidx);

      /*
       * 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.
       */
      alloc_flags = gfp_to_alloc_flags(gfp_mask);

restart:
      /* This is the last chance, in general, before the goto nopage. */
      page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist,
                  high_zoneidx, alloc_flags & ~ALLOC_NO_WATERMARKS,
                  preferred_zone, migratetype);
      if (page)
            goto got_pg;

rebalance:
      /* Allocate without watermarks if the context allows */
      if (alloc_flags & ALLOC_NO_WATERMARKS) {
            page = __alloc_pages_high_priority(gfp_mask, order,
                        zonelist, high_zoneidx, nodemask,
                        preferred_zone, migratetype);
            if (page)
                  goto got_pg;
      }

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

      /* Avoid recursion of direct reclaim */
      if (p->flags & PF_MEMALLOC)
            goto nopage;

      /* Avoid allocations with no watermarks from looping endlessly */
      if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
            goto nopage;

      /* Try direct reclaim and then allocating */
      page = __alloc_pages_direct_reclaim(gfp_mask, order,
                              zonelist, high_zoneidx,
                              nodemask,
                              alloc_flags, preferred_zone,
                              migratetype, &did_some_progress);
      if (page)
            goto got_pg;

      /*
       * If we failed to make any progress reclaiming, then we are
       * running out of options and have to consider going OOM
       */
      if (!did_some_progress) {
            if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
                  if (oom_killer_disabled)
                        goto nopage;
                  page = __alloc_pages_may_oom(gfp_mask, order,
                              zonelist, high_zoneidx,
                              nodemask, preferred_zone,
                              migratetype);
                  if (page)
                        goto got_pg;

                  /*
                   * The OOM killer does not trigger for high-order
                   * ~__GFP_NOFAIL allocations so if no progress is being
                   * made, there are no other options and retrying is
                   * unlikely to help.
                   */
                  if (order > PAGE_ALLOC_COSTLY_ORDER &&
                                    !(gfp_mask & __GFP_NOFAIL))
                        goto nopage;

                  goto restart;
            }
      }

      /* Check if we should retry the allocation */
      pages_reclaimed += did_some_progress;
      if (should_alloc_retry(gfp_mask, order, pages_reclaimed)) {
            /* Wait for some write requests to complete then retry */
            congestion_wait(BLK_RW_ASYNC, 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();
      }
      return page;
got_pg:
      if (kmemcheck_enabled)
            kmemcheck_pagealloc_alloc(page, order, gfp_mask);
      return page;

}

/*
 * This is the 'heart' of the zoned buddy allocator.
 */
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
                  struct zonelist *zonelist, nodemask_t *nodemask)
{
      enum zone_type high_zoneidx = gfp_zone(gfp_mask);
      struct zone *preferred_zone;
      struct page *page;
      int migratetype = allocflags_to_migratetype(gfp_mask);

      gfp_mask &= gfp_allowed_mask;

      lockdep_trace_alloc(gfp_mask);

      might_sleep_if(gfp_mask & __GFP_WAIT);

      if (should_fail_alloc_page(gfp_mask, order))
            return NULL;

      /*
       * Check the zones suitable for the gfp_mask contain at least one
       * valid zone. It's possible to have an empty zonelist as a result
       * of GFP_THISNODE and a memoryless node
       */
      if (unlikely(!zonelist->_zonerefs->zone))
            return NULL;

      /* The preferred zone is used for statistics later */
      first_zones_zonelist(zonelist, high_zoneidx, nodemask, &preferred_zone);
      if (!preferred_zone)
            return NULL;

      /* First allocation attempt */
      page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
                  zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,
                  preferred_zone, migratetype);
      if (unlikely(!page))
            page = __alloc_pages_slowpath(gfp_mask, order,
                        zonelist, high_zoneidx, nodemask,
                        preferred_zone, migratetype);

      return page;
}
EXPORT_SYMBOL(__alloc_pages_nodemask);

/*
 * Common helper functions.
 */
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);

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);
}

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);

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);

/**
 * alloc_pages_exact - allocate an exact number physically-contiguous pages.
 * @size: the number of bytes to allocate
 * @gfp_mask: GFP flags for the allocation
 *
 * This function is similar to alloc_pages(), except that it allocates the
 * minimum number of pages to satisfy the request.  alloc_pages() can only
 * allocate memory in power-of-two pages.
 *
 * This function is also limited by MAX_ORDER.
 *
 * Memory allocated by this function must be released by free_pages_exact().
 */
void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
{
      unsigned int order = get_order(size);
      unsigned long addr;

      addr = __get_free_pages(gfp_mask, order);
      if (addr) {
            unsigned long alloc_end = addr + (PAGE_SIZE << order);
            unsigned long used = addr + PAGE_ALIGN(size);

            split_page(virt_to_page((void *)addr), order);
            while (used < alloc_end) {
                  free_page(used);
                  used += PAGE_SIZE;
            }
      }

      return (void *)addr;
}
EXPORT_SYMBOL(alloc_pages_exact);

/**
 * free_pages_exact - release memory allocated via alloc_pages_exact()
 * @virt: the value returned by alloc_pages_exact.
 * @size: size of allocation, same value as passed to alloc_pages_exact().
 *
 * Release the memory allocated by a previous call to alloc_pages_exact.
 */
void free_pages_exact(void *virt, size_t size)
{
      unsigned long addr = (unsigned long)virt;
      unsigned long end = addr + PAGE_ALIGN(size);

      while (addr < end) {
            free_page(addr);
            addr += PAGE_SIZE;
      }
}
EXPORT_SYMBOL(free_pages_exact);

static unsigned int nr_free_zone_pages(int offset)
{
      struct zoneref *z;
      struct zone *zone;

      /* Just pick one node, since fallback list is circular */
      unsigned int sum = 0;

      struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);

      for_each_zone_zonelist(zone, z, zonelist, offset) {
            unsigned long size = zone->present_pages;
            unsigned long high = high_wmark_pages(zone);
            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));
}
EXPORT_SYMBOL_GPL(nr_free_buffer_pages);

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

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_populated_zone(zone) {
            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: hi:%5d, btch:%4d usd:%4d\n",
                         cpu, pageset->pcp.high,
                         pageset->pcp.batch, pageset->pcp.count);
            }
      }

      printk("Active_anon:%lu active_file:%lu inactive_anon:%lu\n"
            " inactive_file:%lu"
            " unevictable:%lu"
            " dirty:%lu writeback:%lu unstable:%lu\n"
            " free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
            global_page_state(NR_ACTIVE_ANON),
            global_page_state(NR_ACTIVE_FILE),
            global_page_state(NR_INACTIVE_ANON),
            global_page_state(NR_INACTIVE_FILE),
            global_page_state(NR_UNEVICTABLE),
            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_populated_zone(zone) {
            int i;

            show_node(zone);
            printk("%s"
                  " free:%lukB"
                  " min:%lukB"
                  " low:%lukB"
                  " high:%lukB"
                  " active_anon:%lukB"
                  " inactive_anon:%lukB"
                  " active_file:%lukB"
                  " inactive_file:%lukB"
                  " unevictable:%lukB"
                  " present:%lukB"
                  " pages_scanned:%lu"
                  " all_unreclaimable? %s"
                  "\n",
                  zone->name,
                  K(zone_page_state(zone, NR_FREE_PAGES)),
                  K(min_wmark_pages(zone)),
                  K(low_wmark_pages(zone)),
                  K(high_wmark_pages(zone)),
                  K(zone_page_state(zone, NR_ACTIVE_ANON)),
                  K(zone_page_state(zone, NR_INACTIVE_ANON)),
                  K(zone_page_state(zone, NR_ACTIVE_FILE)),
                  K(zone_page_state(zone, NR_INACTIVE_FILE)),
                  K(zone_page_state(zone, NR_UNEVICTABLE)),
                  K(zone->present_pages),
                  zone->pages_scanned,
                  (zone_is_all_unreclaimable(zone) ? "yes" : "no")
                  );
            printk("lowmem_reserve[]:");
            for (i = 0; i < MAX_NR_ZONES; i++)
                  printk(" %lu", zone->lowmem_reserve[i]);
            printk("\n");
      }

      for_each_populated_zone(zone) {
            unsigned long nr[MAX_ORDER], flags, order, total = 0;

            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));
      }

      printk("%ld total pagecache pages\n", global_page_state(NR_FILE_PAGES));

      show_swap_cache_info();
}

static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
      zoneref->zone = zone;
      zoneref->zone_idx = zone_idx(zone);
}

/*
 * Builds allocation fallback zone lists.
 *
 * Add all populated zones of a node to the zonelist.
 */
static int 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)) {
                  zoneref_set_zone(zone,
                        &zonelist->_zonerefs[nr_zones++]);
                  check_highest_zone(zone_type);
            }

      } while (zone_type);
      return nr_zones;
}


/*
 *  zonelist_order:
 *  0 = automatic detection of better ordering.
 *  1 = order by ([node] distance, -zonetype)
 *  2 = order by (-zonetype, [node] distance)
 *
 *  If not NUMA, ZONELIST_ORDER_ZONE and ZONELIST_ORDER_NODE will create
 *  the same zonelist. So only NUMA can configure this param.
 */
#define ZONELIST_ORDER_DEFAULT  0
#define ZONELIST_ORDER_NODE     1
#define ZONELIST_ORDER_ZONE     2

/* zonelist order in the kernel.
 * set_zonelist_order() will set this to NODE or ZONE.
 */
static int current_zonelist_order = ZONELIST_ORDER_DEFAULT;
static char zonelist_order_name[3][8] = {"Default", "Node", "Zone"};


#ifdef CONFIG_NUMA
/* The value user specified ....changed by config */
static int user_zonelist_order = ZONELIST_ORDER_DEFAULT;
/* string for sysctl */
#define NUMA_ZONELIST_ORDER_LEN     16
char numa_zonelist_order[16] = "default";

/*
 * interface for configure zonelist ordering.
 * command line option "numa_zonelist_order"
 *    = "[dD]efault     - default, automatic configuration.
 *    = "[nN]ode  - order by node locality, then by zone within node
 *    = "[zZ]one      - order by zone, then by locality within zone
 */

static int __parse_numa_zonelist_order(char *s)
{
      if (*s == 'd' || *s == 'D') {
            user_zonelist_order = ZONELIST_ORDER_DEFAULT;
      } else if (*s == 'n' || *s == 'N') {
            user_zonelist_order = ZONELIST_ORDER_NODE;
      } else if (*s == 'z' || *s == 'Z') {
            user_zonelist_order = ZONELIST_ORDER_ZONE;
      } else {
            printk(KERN_WARNING
                  "Ignoring invalid numa_zonelist_order value:  "
                  "%s\n", s);
            return -EINVAL;
      }
      return 0;
}

static __init int setup_numa_zonelist_order(char *s)
{
      if (s)
            return __parse_numa_zonelist_order(s);
      return 0;
}
early_param("numa_zonelist_order", setup_numa_zonelist_order);

/*
 * sysctl handler for numa_zonelist_order
 */
int numa_zonelist_order_handler(ctl_table *table, int write,
            struct file *file, void __user *buffer, size_t *length,
            loff_t *ppos)
{
      char saved_string[NUMA_ZONELIST_ORDER_LEN];
      int ret;

      if (write)
            strncpy(saved_string, (char*)table->data,
                  NUMA_ZONELIST_ORDER_LEN);
      ret = proc_dostring(table, write, file, buffer, length, ppos);
      if (ret)
            return ret;
      if (write) {
            int oldval = user_zonelist_order;
            if (__parse_numa_zonelist_order((char*)table->data)) {
                  /*
                   * bogus value.  restore saved string
                   */
                  strncpy((char*)table->data, saved_string,
                        NUMA_ZONELIST_ORDER_LEN);
                  user_zonelist_order = oldval;
            } else if (oldval != user_zonelist_order)
                  build_all_zonelists();
      }
      return 0;
}


#define MAX_NODE_LOAD (nr_online_nodes)
static int 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 find_next_best_node(int node, nodemask_t *used_node_mask)
{
      int n, val;
      int min_val = INT_MAX;
      int best_node = -1;
      const struct cpumask *tmp = cpumask_of_node(0);

      /* 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_node_state(n, N_HIGH_MEMORY) {

            /* 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 = cpumask_of_node(n);
            if (!cpumask_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;
}


/*
 * Build zonelists ordered by node and zones within node.
 * This results in maximum locality--normal zone overflows into local
 * DMA zone, if any--but risks exhausting DMA zone.
 */
static void build_zonelists_in_node_order(pg_data_t *pgdat, int node)
{
      int j;
      struct zonelist *zonelist;

      zonelist = &pgdat->node_zonelists[0];
      for (j = 0; zonelist->_zonerefs[j].zone != NULL; j++)
            ;
      j = build_zonelists_node(NODE_DATA(node), zonelist, j,
                                          MAX_NR_ZONES - 1);
      zonelist->_zonerefs[j].zone = NULL;
      zonelist->_zonerefs[j].zone_idx = 0;
}

/*
 * Build gfp_thisnode zonelists
 */
static void build_thisnode_zonelists(pg_data_t *pgdat)
{
      int j;
      struct zonelist *zonelist;

      zonelist = &pgdat->node_zonelists[1];
      j = build_zonelists_node(pgdat, zonelist, 0, MAX_NR_ZONES - 1);
      zonelist->_zonerefs[j].zone = NULL;
      zonelist->_zonerefs[j].zone_idx = 0;
}

/*
 * Build zonelists ordered by zone and nodes within zones.
 * This results in conserving DMA zone[s] until all Normal memory is
 * exhausted, but results in overflowing to remote node while memory
 * may still exist in local DMA zone.
 */
static int node_order[MAX_NUMNODES];

static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
{
      int pos, j, node;
      int zone_type;          /* needs to be signed */
      struct zone *z;
      struct zonelist *zonelist;

      zonelist = &pgdat->node_zonelists[0];
      pos = 0;
      for (zone_type = MAX_NR_ZONES - 1; zone_type >= 0; zone_type--) {
            for (j = 0; j < nr_nodes; j++) {
                  node = node_order[j];
                  z = &NODE_DATA(node)->node_zones[zone_type];
                  if (populated_zone(z)) {
                        zoneref_set_zone(z,
                              &zonelist->_zonerefs[pos++]);
                        check_highest_zone(zone_type);
                  }
            }
      }
      zonelist->_zonerefs[pos].zone = NULL;
      zonelist->_zonerefs[pos].zone_idx = 0;
}

static int default_zonelist_order(void)
{
      int nid, zone_type;
      unsigned long low_kmem_size,total_size;
      struct zone *z;
      int average_size;
      /*
         * ZONE_DMA and ZONE_DMA32 can be very small area in the sytem.
       * If they are really small and used heavily, the system can fall
       * into OOM very easily.
       * This function detect ZONE_DMA/DMA32 size and confgigures zone order.
       */
      /* Is there ZONE_NORMAL ? (ex. ppc has only DMA zone..) */
      low_kmem_size = 0;
      total_size = 0;
      for_each_online_node(nid) {
            for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
                  z = &NODE_DATA(nid)->node_zones[zone_type];
                  if (populated_zone(z)) {
                        if (zone_type < ZONE_NORMAL)
                              low_kmem_size += z->present_pages;
                        total_size += z->present_pages;
                  }
            }
      }
      if (!low_kmem_size ||  /* there are no DMA area. */
          low_kmem_size > total_size/2) /* DMA/DMA32 is big. */
            return ZONELIST_ORDER_NODE;
      /*
       * look into each node's config.
       * If there is a node whose DMA/DMA32 memory is very big area on
       * local memory, NODE_ORDER may be suitable.
         */
      average_size = total_size /
                        (nodes_weight(node_states[N_HIGH_MEMORY]) + 1);
      for_each_online_node(nid) {
            low_kmem_size = 0;
            total_size = 0;
            for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
                  z = &NODE_DATA(nid)->node_zones[zone_type];
                  if (populated_zone(z)) {
                        if (zone_type < ZONE_NORMAL)
                              low_kmem_size += z->present_pages;
                        total_size += z->present_pages;
                  }
            }
            if (low_kmem_size &&
                total_size > average_size && /* ignore small node */
                low_kmem_size > total_size * 70/100)
                  return ZONELIST_ORDER_NODE;
      }
      return ZONELIST_ORDER_ZONE;
}

static void set_zonelist_order(void)
{
      if (user_zonelist_order == ZONELIST_ORDER_DEFAULT)
            current_zonelist_order = default_zonelist_order();
      else
            current_zonelist_order = user_zonelist_order;
}

static void build_zonelists(pg_data_t *pgdat)
{
      int j, node, load;
      enum zone_type i;
      nodemask_t used_mask;
      int local_node, prev_node;
      struct zonelist *zonelist;
      int order = current_zonelist_order;

      /* initialize zonelists */
      for (i = 0; i < MAX_ZONELISTS; i++) {
            zonelist = pgdat->node_zonelists + i;
            zonelist->_zonerefs[0].zone = NULL;
            zonelist->_zonerefs[0].zone_idx = 0;
      }

      /* NUMA-aware ordering of nodes */
      local_node = pgdat->node_id;
      load = nr_online_nodes;
      prev_node = local_node;
      nodes_clear(used_mask);

      memset(node_order, 0, sizeof(node_order));
      j = 0;

      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--;
            if (order == ZONELIST_ORDER_NODE)
                  build_zonelists_in_node_order(pgdat, node);
            else
                  node_order[j++] = node; /* remember order */
      }

      if (order == ZONELIST_ORDER_ZONE) {
            /* calculate node order -- i.e., DMA last! */
            build_zonelists_in_zone_order(pgdat, j);
      }

      build_thisnode_zonelists(pgdat);
}

/* Construct the zonelist performance cache - see further mmzone.h */
static void build_zonelist_cache(pg_data_t *pgdat)
{
      struct zonelist *zonelist;
      struct zonelist_cache *zlc;
      struct zoneref *z;

      zonelist = &pgdat->node_zonelists[0];
      zonelist->zlcache_ptr = zlc = &zonelist->zlcache;
      bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
      for (z = zonelist->_zonerefs; z->zone; z++)
            zlc->z_to_n[z - zonelist->_zonerefs] = zonelist_node_idx(z);
}


#else /* CONFIG_NUMA */

static void set_zonelist_order(void)
{
      current_zonelist_order = ZONELIST_ORDER_ZONE;
}

static void build_zonelists(pg_data_t *pgdat)
{
      int node, local_node;
      enum zone_type j;
      struct zonelist *zonelist;

      local_node = pgdat->node_id;

      zonelist = &pgdat->node_zonelists[0];
      j = build_zonelists_node(pgdat, zonelist, 0, MAX_NR_ZONES - 1);

      /*
       * 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,
                                          MAX_NR_ZONES - 1);
      }
      for (node = 0; node < local_node; node++) {
            if (!node_online(node))
                  continue;
            j = build_zonelists_node(NODE_DATA(node), zonelist, j,
                                          MAX_NR_ZONES - 1);
      }

      zonelist->_zonerefs[j].zone = NULL;
      zonelist->_zonerefs[j].zone_idx = 0;
}

/* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
static void build_zonelist_cache(pg_data_t *pgdat)
{
      pgdat->node_zonelists[0].zlcache_ptr = NULL;
}

#endif      /* CONFIG_NUMA */

/* return values int ....just for stop_machine() */
static int __build_all_zonelists(void *dummy)
{
      int nid;

#ifdef CONFIG_NUMA
      memset(node_load, 0, sizeof(node_load));
#endif
      for_each_online_node(nid) {
            pg_data_t *pgdat = NODE_DATA(nid);

            build_zonelists(pgdat);
            build_zonelist_cache(pgdat);
      }
      return 0;
}

void build_all_zonelists(void)
{
      set_zonelist_order();

      if (system_state == SYSTEM_BOOTING) {
            __build_all_zonelists(NULL);
            mminit_verify_zonelist();
            cpuset_init_current_mems_allowed();
      } else {
            /* we have to stop all cpus to guarantee there is no user
               of zonelist */
            stop_machine(__build_all_zonelists, NULL, NULL);
            /* cpuset refresh routine should be here */
      }
      vm_total_pages = nr_free_pagecache_pages();
      /*
       * Disable grouping by mobility if the number of pages in the
       * system is too low to allow the mechanism to work. It would be
       * more accurate, but expensive to check per-zone. This check is
       * made on memory-hotadd so a system can start with mobility
       * disabled and enable it later
       */
      if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
            page_group_by_mobility_disabled = 1;
      else
            page_group_by_mobility_disabled = 0;

      printk("Built %i zonelists in %s order, mobility grouping %s.  "
            "Total pages: %ld\n",
                  nr_online_nodes,
                  zonelist_order_name[current_zonelist_order],
                  page_group_by_mobility_disabled ? "off" : "on",
                  vm_total_pages);
#ifdef CONFIG_NUMA
      printk("Policy zone: %s\n", zone_names[policy_zone]);
#endif
}

/*
 * 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))

/*
 * Mark a number of pageblocks as MIGRATE_RESERVE. The number
 * of blocks reserved is based on min_wmark_pages(zone). The memory within
 * the reserve will tend to store contiguous free pages. Setting min_free_kbytes
 * higher will lead to a bigger reserve which will get freed as contiguous
 * blocks as reclaim kicks in
 */
static void setup_zone_migrate_reserve(struct zone *zone)
{
      unsigned long start_pfn, pfn, end_pfn;
      struct page *page;
      unsigned long reserve, block_migratetype;

      /* Get the start pfn, end pfn and the number of blocks to reserve */
      start_pfn = zone->zone_start_pfn;
      end_pfn = start_pfn + zone->spanned_pages;
      reserve = roundup(min_wmark_pages(zone), pageblock_nr_pages) >>
                                          pageblock_order;

      for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
            if (!pfn_valid(pfn))
                  continue;
            page = pfn_to_page(pfn);

            /* Watch out for overlapping nodes */
            if (page_to_nid(page) != zone_to_nid(zone))
                  continue;

            /* Blocks with reserved pages will never free, skip them. */
            if (PageReserved(page))
                  continue;

            block_migratetype = get_pageblock_migratetype(page);

            /* If this block is reserved, account for it */
            if (reserve > 0 && block_migratetype == MIGRATE_RESERVE) {
                  reserve--;
                  continue;
            }

            /* Suitable for reserving if this block is movable */
            if (reserve > 0 && block_migratetype == MIGRATE_MOVABLE) {
                  set_pageblock_migratetype(page, MIGRATE_RESERVE);
                  move_freepages_block(zone, page, MIGRATE_RESERVE);
                  reserve--;
                  continue;
            }

            /*
             * If the reserve is met and this is a previous reserved block,
             * take it back
             */
            if (block_migratetype == MIGRATE_RESERVE) {
                  set_pageblock_migratetype(page, MIGRATE_MOVABLE);
                  move_freepages_block(zone, page, MIGRATE_MOVABLE);
            }
      }
}

/*
 * 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;
      struct zone *z;

      if (highest_memmap_pfn < end_pfn - 1)
            highest_memmap_pfn = end_pfn - 1;

      z = &NODE_DATA(nid)->node_zones[zone];
      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);
            mminit_verify_page_links(page, zone, nid, pfn);
            init_page_count(page);
            reset_page_mapcount(page);
            SetPageReserved(page);
            /*
             * Mark the block movable so that blocks are reserved for
             * movable at startup. This will force kernel allocations
             * to reserve their blocks rather than leaking throughout
             * the address space during boot when many long-lived
             * kernel allocations are made. Later some blocks near
             * the start are marked MIGRATE_RESERVE by
             * setup_zone_migrate_reserve()
             *
             * bitmap is created for zone's valid pfn range. but memmap
             * can be created for invalid pages (for alignment)
             * check here not to call set_pageblock_migratetype() against
             * pfn out of zone.
             */
            if ((z->zone_start_pfn <= pfn)
                && (pfn < z->zone_start_pfn + z->spanned_pages)
                && !(pfn & (pageblock_nr_pages - 1)))
                  set_pageblock_migratetype(page, MIGRATE_MOVABLE);

            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
      }
}

static void __meminit zone_init_free_lists(struct zone *zone)
{
      int order, t;
      for_each_migratetype_order(order, t) {
            INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
            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 zone_batchsize(struct zone *zone)
{
#ifdef CONFIG_MMU
      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 = rounddown_pow_of_two(batch + batch/2) - 1;

      return batch;

#else
      /* The deferral and batching of frees should be suppressed under NOMMU
       * conditions.
       *
       * The problem is that NOMMU needs to be able to allocate large chunks
       * of contiguous memory as there's no hardware page translation to
       * assemble apparent contiguous memory from discontiguous pages.
       *
       * Queueing large contiguous runs of pages for batching, however,
       * causes the pages to actually be freed in smaller chunks.  As there
       * can be a significant delay between the individual batches being
       * recycled, this leads to the once large chunks of space being
       * fragmented and becoming unavailable for high-order allocations.
       */
      return 0;
#endif
}

static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
{
      struct per_cpu_pages *pcp;

      memset(p, 0, sizeof(*p));

      pcp = &p->pcp;
      pcp->count = 0;
      pcp->high = 6 * batch;
      pcp->batch = max(1UL, 1 * batch);
      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;
      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;
      int node = cpu_to_node(cpu);

      node_set_state(node, N_CPU);  /* this node has a cpu */

      for_each_populated_zone(zone) {
            zone_pcp(zone, cpu) = kmalloc_node(sizeof(struct per_cpu_pageset),
                               GFP_KERNEL, node);
            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 (!populated_zone(dzone))
                  continue;
            if (dzone == zone)
                  break;
            kfree(zone_pcp(dzone, cpu));
            zone_pcp(dzone, cpu) = &boot_pageset[cpu];
      }
      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) = &boot_pageset[cpu];
      }
}

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:
      case CPU_UP_PREPARE_FROZEN:
            if (process_zones(cpu))
                  ret = NOTIFY_BAD;
            break;
      case CPU_UP_CANCELED:
      case CPU_UP_CANCELED_FROZEN:
      case CPU_DEAD:
      case CPU_DEAD_FROZEN:
            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 noinline __init_refok
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 (!slab_is_available()) {
            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 = 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;

      mminit_dprintk(MMINIT_TRACE, "memmap_init",
                  "Initialising map node %d zone %lu pfns %lu -> %lu\n",
                  pgdat->node_id,
                  (unsigned long)zone_idx(zone),
                  zone_start_pfn, (zone_start_pfn + size));

      zone_init_free_lists(zone);

      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 __meminit 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 regardless of node
 */
static int __meminit 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 __meminit __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;
      }
      /* This is a memory hole */
      return -1;
}
#endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */

int __meminit early_pfn_to_nid(unsigned long pfn)
{
      int nid;

      nid = __early_pfn_to_nid(pfn);
      if (nid >= 0)
            return nid;
      /* just returns 0 */
      return 0;
}

#ifdef CONFIG_NODES_SPAN_OTHER_NODES
bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
{
      int nid;

      nid = __early_pfn_to_nid(pfn);
      if (nid >= 0 && nid != node)
            return false;
      return true;
}
#endif

/* 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);
      }
}

void __init work_with_active_regions(int nid, work_fn_t work_fn, void *data)
{
      int i;
      int ret;

      for_each_active_range_index_in_nid(i, nid) {
            ret = work_fn(early_node_map[i].start_pfn,
                        early_node_map[i].end_pfn, data);
            if (ret)
                  break;
      }
}
/**
 * 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);
}

/**
 * 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 __meminit 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)
            *start_pfn = 0;
}

/*
 * This finds a zone that can be used for ZONE_MOVABLE pages. The
 * assumption is made that zones within a node are ordered in monotonic
 * increasing memory addresses so that the "highest" populated zone is used
 */
static void __init find_usable_zone_for_movable(void)
{
      int zone_index;
      for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
            if (zone_index == ZONE_MOVABLE)
                  continue;

            if (arch_zone_highest_possible_pfn[zone_index] >
                        arch_zone_lowest_possible_pfn[zone_index])
                  break;
      }

      VM_BUG_ON(zone_index == -1);
      movable_zone = zone_index;
}

/*
 * The zone ranges provided by the architecture do not include ZONE_MOVABLE
 * because it is sized independant of architecture. Unlike the other zones,
 * the starting point for ZONE_MOVABLE is not fixed. It may be different
 * in each node depending on the size of each node and how evenly kernelcore
 * is distributed. This helper function adjusts the zone ranges
 * provided by the architecture for a given node by using the end of the
 * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
 * zones within a node are in order of monotonic increases memory addresses
 */
static void __meminit adjust_zone_range_for_zone_movable(int nid,
                              unsigned long zone_type,
                              unsigned long node_start_pfn,
                              unsigned long node_end_pfn,
                              unsigned long *zone_start_pfn,
                              unsigned long *zone_end_pfn)
{
      /* Only adjust if ZONE_MOVABLE is on this node */
      if (zone_movable_pfn[nid]) {
            /* Size ZONE_MOVABLE */
            if (zone_type == ZONE_MOVABLE) {
                  *zone_start_pfn = zone_movable_pfn[nid];
                  *zone_end_pfn = min(node_end_pfn,
                        arch_zone_highest_possible_pfn[movable_zone]);

            /* Adjust for ZONE_MOVABLE starting within this range */
            } else if (*zone_start_pfn < zone_movable_pfn[nid] &&
                        *zone_end_pfn > zone_movable_pfn[nid]) {
                  *zone_end_pfn = zone_movable_pfn[nid];

            /* Check if this whole range is within ZONE_MOVABLE */
            } else if (*zone_start_pfn >= zone_movable_pfn[nid])
                  *zone_start_pfn = *zone_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()
 */
static unsigned long __meminit 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];
      adjust_zone_range_for_zone_movable(nid, zone_type,
                        node_start_pfn, node_end_pfn,
                        &zone_start_pfn, &zone_end_pfn);

      /* 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.
 */
static unsigned long __meminit __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;

      prev_end_pfn = min(early_node_map[i].start_pfn, range_end_pfn);

      /* Account for ranges before physical memory on this node */
      if (early_node_map[i].start_pfn > range_start_pfn)
            hole_pages = prev_end_pfn - range_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 */
static unsigned long __meminit 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);

      adjust_zone_range_for_zone_movable(nid, zone_type,
                  node_start_pfn, node_end_pfn,
                  &zone_start_pfn, &zone_end_pfn);
      return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
}

#else
static inline unsigned long __meminit zone_spanned_pages_in_node(int nid,
                              unsigned long zone_type,
                              unsigned long *zones_size)
{
      return zones_size[zone_type];
}

static inline unsigned long __meminit 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 __meminit 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);
}

#ifndef CONFIG_SPARSEMEM
/*
 * Calculate the size of the zone->blockflags rounded to an unsigned long
 * Start by making sure zonesize is a multiple of pageblock_order by rounding
 * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
 * round what is now in bits to nearest long in bits, then return it in
 * bytes.
 */
static unsigned long __init usemap_size(unsigned long zonesize)
{
      unsigned long usemapsize;

      usemapsize = roundup(zonesize, pageblock_nr_pages);
      usemapsize = usemapsize >> pageblock_order;
      usemapsize *= NR_PAGEBLOCK_BITS;
      usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));

      return usemapsize / 8;
}

static void __init setup_usemap(struct pglist_data *pgdat,
                        struct zone *zone, unsigned long zonesize)
{
      unsigned long usemapsize = usemap_size(zonesize);
      zone->pageblock_flags = NULL;
      if (usemapsize)
            zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize);
}
#else
static void inline setup_usemap(struct pglist_data *pgdat,
                        struct zone *zone, unsigned long zonesize) {}
#endif /* CONFIG_SPARSEMEM */

#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE

/* Return a sensible default order for the pageblock size. */
static inline int pageblock_default_order(void)
{
      if (HPAGE_SHIFT > PAGE_SHIFT)
            return HUGETLB_PAGE_ORDER;

      return MAX_ORDER-1;
}

/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
static inline void __init set_pageblock_order(unsigned int order)
{
      /* Check that pageblock_nr_pages has not already been setup */
      if (pageblock_order)
            return;

      /*
       * Assume the largest contiguous order of interest is a huge page.
       * This value may be variable depending on boot parameters on IA64
       */
      pageblock_order = order;
}
#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

/*
 * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
 * and pageblock_default_order() are unused as pageblock_order is set
 * at compile-time. See include/linux/pageblock-flags.h for the values of
 * pageblock_order based on the kernel config
 */
static inline int pageblock_default_order(unsigned int order)
{
      return MAX_ORDER-1;
}
#define set_pageblock_order(x)      do {} while (0)

#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

/*
 * Set up the zone data structures:
 *   - mark all pages reserved
 *   - mark all memory queues empty
 *   - clear the memory bitmaps
 */
static void __paginginit 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;
      pgdat_page_cgroup_init(pgdat);
      
      for (j = 0; j < MAX_NR_ZONES; j++) {
            struct zone *zone = pgdat->node_zones + j;
            unsigned long size, realsize, memmap_pages;
            enum lru_list l;

            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 =
                  PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT;
            if (realsize >= memmap_pages) {
                  realsize -= memmap_pages;
                  if (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);
            for_each_lru(l) {
                  INIT_LIST_HEAD(&zone->lru[l].list);
                  zone->lru[l].nr_saved_scan = 0;
            }
            zone->reclaim_stat.recent_rotated[0] = 0;
            zone->reclaim_stat.recent_rotated[1] = 0;
            zone->reclaim_stat.recent_scanned[0] = 0;
            zone->reclaim_stat.recent_scanned[1] = 0;
            zap_zone_vm_stats(zone);
            zone->flags = 0;
            if (!size)
                  continue;

            set_pageblock_order(pageblock_default_order());
            setup_usemap(pgdat, zone, size);
            ret = init_currently_empty_zone(zone, zone_start_pfn,
                                    size, MEMMAP_EARLY);
            BUG_ON(ret);
            memmap_init(size, nid, j, zone_start_pfn);
            zone_start_pfn += size;
      }
}

static void __init_refok 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);
      }
#ifndef CONFIG_NEED_MULTIPLE_NODES
      /*
       * 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 - ARCH_PFN_OFFSET);
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
      }
#endif
#endif /* CONFIG_FLAT_NODE_MEM_MAP */
}

void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
            unsigned long node_start_pfn, unsigned long *zholes_size)
{
      pg_data_t *pgdat = NODE_DATA(nid);

      pgdat->node_id = nid;
      pgdat->node_start_pfn = node_start_pfn;
      calculate_node_totalpages(pgdat, zones_size, zholes_size);

      alloc_node_mem_map(pgdat);
#ifdef CONFIG_FLAT_NODE_MEM_MAP
      printk(KERN_DEBUG "free_area_init_node: node %d, pgdat %08lx, node_mem_map %08lx\n",
            nid, (unsigned long)pgdat,
            (unsigned long)pgdat->node_mem_map);
#endif

      free_area_init_core(pgdat, zones_size, zholes_size);
}

#ifdef CONFIG_ARCH_POPULATES_NODE_MAP

#if MAX_NUMNODES > 1
/*
 * 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 inline void setup_nr_node_ids(void)
{
}
#endif

/**
 * 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;

      mminit_dprintk(MMINIT_TRACE, "memory_register",
                  "Entering add_active_range(%d, %#lx, %#lx) "
                  "%d entries of %d used\n",
                  nid, start_pfn, end_pfn,
                  nr_nodemap_entries, MAX_ACTIVE_REGIONS);

      mminit_validate_memmodel_limits(&start_pfn, &end_pfn);

      /* 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;
}

/**
 * remove_active_range - Shrink an existing registered range of PFNs
 * @nid: The node id the range is on that should be shrunk
 * @start_pfn: The new PFN of the range
 * @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 near the end physical page range that has already been
 * registered. This function allows an arch to shrink an existing registered
 * range.
 */
void __init remove_active_range(unsigned int nid, unsigned long start_pfn,
                        unsigned long end_pfn)
{
      int i, j;
      int removed = 0;

      printk(KERN_DEBUG "remove_active_range (%d, %lu, %lu)\n",
                    nid, start_pfn, end_pfn);

      /* Find the old active region end and shrink */
      for_each_active_range_index_in_nid(i, nid) {
            if (early_node_map[i].start_pfn >= start_pfn &&
                early_node_map[i].end_pfn <= end_pfn) {
                  /* clear it */
                  early_node_map[i].start_pfn = 0;
                  early_node_map[i].end_pfn = 0;
                  removed = 1;
                  continue;
            }
            if (early_node_map[i].start_pfn < start_pfn &&
                early_node_map[i].end_pfn > start_pfn) {
                  unsigned long temp_end_pfn = early_node_map[i].end_pfn;
                  early_node_map[i].end_pfn = start_pfn;
                  if (temp_end_pfn > end_pfn)
                        add_active_range(nid, end_pfn, temp_end_pfn);
                  continue;
            }
            if (early_node_map[i].start_pfn >= start_pfn &&
                early_node_map[i].end_pfn > end_pfn &&
                early_node_map[i].start_pfn < end_pfn) {
                  early_node_map[i].start_pfn = end_pfn;
                  continue;
            }
      }

      if (!removed)
            return;

      /* remove the blank ones */
      for (i = nr_nodemap_entries - 1; i > 0; i--) {
            if (early_node_map[i].nid != nid)
                  continue;
            if (early_node_map[i].end_pfn)
                  continue;
            /* we found it, get rid of it */
            for (j = i; j < nr_nodemap_entries - 1; j++)
                  memcpy(&early_node_map[j], &early_node_map[j+1],
                        sizeof(early_node_map[j]));
            j = nr_nodemap_entries - 1;
            memset(&early_node_map[j], 0, sizeof(early_node_map[j]));
            nr_nodemap_entries--;
      }
}

/**
 * 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;
}

/* 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 */
static unsigned long __init find_min_pfn_for_node(int 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 %d\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);
}

/*
 * early_calculate_totalpages()
 * Sum pages in active regions for movable zone.
 * Populate N_HIGH_MEMORY for calculating usable_nodes.
 */
static unsigned long __init early_calculate_totalpages(void)
{
      int i;
      unsigned long totalpages = 0;

      for (i = 0; i < nr_nodemap_entries; i++) {
            unsigned long pages = early_node_map[i].end_pfn -
                                    early_node_map[i].start_pfn;
            totalpages += pages;
            if (pages)
                  node_set_state(early_node_map[i].nid, N_HIGH_MEMORY);
      }
      return totalpages;
}

/*
 * Find the PFN the Movable zone begins in each node. Kernel memory
 * is spread evenly between nodes as long as the nodes have enough
 * memory. When they don't, some nodes will have more kernelcore than
 * others
 */
static void __init find_zone_movable_pfns_for_nodes(unsigned long *movable_pfn)
{
      int i, nid;
      unsigned long usable_startpfn;
      unsigned long kernelcore_node, kernelcore_remaining;
      /* save the state before borrow the nodemask */
      nodemask_t saved_node_state = node_states[N_HIGH_MEMORY];
      unsigned long totalpages = early_calculate_totalpages();
      int usable_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);

      /*
       * If movablecore was specified, calculate what size of
       * kernelcore that corresponds so that memory usable for
       * any allocation type is evenly spread. If both kernelcore
       * and movablecore are specified, then the value of kernelcore
       * will be used for required_kernelcore if it's greater than
       * what movablecore would have allowed.
       */
      if (required_movablecore) {
            unsigned long corepages;

            /*
             * Round-up so that ZONE_MOVABLE is at least as large as what
             * was requested by the user
             */
            required_movablecore =
                  roundup(required_movablecore, MAX_ORDER_NR_PAGES);
            corepages = totalpages - required_movablecore;

            required_kernelcore = max(required_kernelcore, corepages);
      }

      /* If kernelcore was not specified, there is no ZONE_MOVABLE */
      if (!required_kernelcore)
            goto out;

      /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
      find_usable_zone_for_movable();
      usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];

restart:
      /* Spread kernelcore memory as evenly as possible throughout nodes */
      kernelcore_node = required_kernelcore / usable_nodes;
      for_each_node_state(nid, N_HIGH_MEMORY) {
            /*
             * Recalculate kernelcore_node if the division per node
             * now exceeds what is necessary to satisfy the requested
             * amount of memory for the kernel
             */
            if (required_kernelcore < kernelcore_node)
                  kernelcore_node = required_kernelcore / usable_nodes;

            /*
             * As the map is walked, we track how much memory is usable
             * by the kernel using kernelcore_remaining. When it is
             * 0, the rest of the node is usable by ZONE_MOVABLE
             */
            kernelcore_remaining = kernelcore_node;

            /* Go through each range of PFNs within this node */
            for_each_active_range_index_in_nid(i, nid) {
                  unsigned long start_pfn, end_pfn;
                  unsigned long size_pages;

                  start_pfn = max(early_node_map[i].start_pfn,
                                    zone_movable_pfn[nid]);
                  end_pfn = early_node_map[i].end_pfn;
                  if (start_pfn >= end_pfn)
                        continue;

                  /* Account for what is only usable for kernelcore */
                  if (start_pfn < usable_startpfn) {
                        unsigned long kernel_pages;
                        kernel_pages = min(end_pfn, usable_startpfn)
                                                - start_pfn;

                        kernelcore_remaining -= min(kernel_pages,
                                          kernelcore_remaining);
                        required_kernelcore -= min(kernel_pages,
                                          required_kernelcore);

                        /* Continue if range is now fully accounted */
                        if (end_pfn <= usable_startpfn) {

                              /*
                               * Push zone_movable_pfn to the end so
                               * that if we have to rebalance
                               * kernelcore across nodes, we will
                               * not double account here
                               */
                              zone_movable_pfn[nid] = end_pfn;
                              continue;
                        }
                        start_pfn = usable_startpfn;
                  }

                  /*
                   * The usable PFN range for ZONE_MOVABLE is from
                   * start_pfn->end_pfn. Calculate size_pages as the
                   * number of pages used as kernelcore
                   */
                  size_pages = end_pfn - start_pfn;
                  if (size_pages > kernelcore_remaining)
                        size_pages = kernelcore_remaining;
                  zone_movable_pfn[nid] = start_pfn + size_pages;

                  /*
                   * Some kernelcore has been met, update counts and
                   * break if the kernelcore for this node has been
                   * satisified
                   */
                  required_kernelcore -= min(required_kernelcore,
                                                size_pages);
                  kernelcore_remaining -= size_pages;
                  if (!kernelcore_remaining)
                        break;
            }
      }

      /*
       * If there is still required_kernelcore, we do another pass with one
       * less node in the count. This will push zone_movable_pfn[nid] further
       * along on the nodes that still have memory until kernelcore is
       * satisified
       */
      usable_nodes--;
      if (usable_nodes && required_kernelcore > usable_nodes)
            goto restart;

      /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
      for (nid = 0; nid < MAX_NUMNODES; nid++)
            zone_movable_pfn[nid] =
                  roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);

out:
      /* restore the node_state */
      node_states[N_HIGH_MEMORY] = saved_node_state;
}

/* Any regular memory on that node ? */
static void check_for_regular_memory(pg_data_t *pgdat)
{
#ifdef CONFIG_HIGHMEM
      enum zone_type zone_type;

      for (zone_type = 0; zone_type <= ZONE_NORMAL; zone_type++) {
            struct zone *zone = &pgdat->node_zones[zone_type];
            if (zone->present_pages)
                  node_set_state(zone_to_nid(zone), N_NORMAL_MEMORY);
      }
#endif
}

/**
 * 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;
      int 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++) {
            if (i == ZONE_MOVABLE)
                  continue;
            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]);
      }
      arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;
      arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;

      /* Find the PFNs that ZONE_MOVABLE begins at in each node */
      memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
      find_zone_movable_pfns_for_nodes(zone_movable_pfn);

      /* Print out the zone ranges */
      printk("Zone PFN ranges:\n");
      for (i = 0; i < MAX_NR_ZONES; i++) {
            if (i == ZONE_MOVABLE)
                  continue;
            printk("  %-8s %0#10lx -> %0#10lx\n",
                        zone_names[i],
                        arch_zone_lowest_possible_pfn[i],
                        arch_zone_highest_possible_pfn[i]);
      }

      /* Print out the PFNs ZONE_MOVABLE begins at in each node */
      printk("Movable zone start PFN for each node\n");
      for (i = 0; i < MAX_NUMNODES; i++) {
            if (zone_movable_pfn[i])
                  printk("  Node %d: %lu\n", i, zone_movable_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: %0#10lx -> %0#10lx\n", early_node_map[i].nid,
                                    early_node_map[i].start_pfn,
                                    early_node_map[i].end_pfn);

      /* Initialise every node */
      mminit_verify_pageflags_layout();
      setup_nr_node_ids();
      for_each_online_node(nid) {
            pg_data_t *pgdat = NODE_DATA(nid);
            free_area_init_node(nid, NULL,
                        find_min_pfn_for_node(nid), NULL);

            /* Any memory on that node */
            if (pgdat->node_present_pages)
                  node_set_state(nid, N_HIGH_MEMORY);
            check_for_regular_memory(pgdat);
      }
}

static int __init cmdline_parse_core(char *p, unsigned long *core)
{
      unsigned long long coremem;
      if (!p)
            return -EINVAL;

      coremem = memparse(p, &p);
      *core = coremem >> PAGE_SHIFT;

      /* Paranoid check that UL is enough for the coremem value */
      WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);

      return 0;
}

/*
 * kernelcore=size sets the amount of memory for use for allocations that
 * cannot be reclaimed or migrated.
 */
static int __init cmdline_parse_kernelcore(char *p)
{
      return cmdline_parse_core(p, &required_kernelcore);
}

/*
 * movablecore=size sets the amount of memory for use for allocations that
 * can be reclaimed or migrated.
 */
static int __init cmdline_parse_movablecore(char *p)
{
      return cmdline_parse_core(p, &required_movablecore);
}

early_param("kernelcore", cmdline_parse_kernelcore);
early_param("movablecore", cmdline_parse_movablecore);

#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
struct pglist_data __refdata contig_page_data = { .bdata = &bootmem_node_data[0] };
EXPORT_SYMBOL(contig_page_data);
#endif

void __init free_area_init(unsigned long *zones_size)
{
      free_area_init_node(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 || action == CPU_DEAD_FROZEN) {
            drain_pages(cpu);

            /*
             * Spill the event counters of the dead processor
             * into the current processors event counters.
             * This artificially elevates the count of the current
             * processor.
             */
            vm_events_fold_cpu(cpu);

            /*
             * Zero the differential counters of the dead processor
             * so that the vm statistics are consistent.
             *
             * This is only okay since the processor is dead and cannot
             * race with what we are doing.
             */
            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 the high watermark as reserved pages. */
                  max += high_wmark_pages(zone);

                  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_wmarks - called when min_free_kbytes changes
 * or when memory is hot-{added|removed}
 *
 * Ensures that the watermark[min,low,high] values for each zone are set
 * correctly with respect to min_free_kbytes.
 */
void setup_per_zone_wmarks(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->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 WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_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->watermark[WMARK_MIN] = min_pages;
            } else {
                  /*
                   * If it's a lowmem zone, reserve a number of pages
                   * proportionate to the zone's size.
                   */
                  zone->watermark[WMARK_MIN] = tmp;
            }

            zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) + (tmp >> 2);
            zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1);
            setup_zone_migrate_reserve(zone);
            spin_unlock_irqrestore(&zone->lock, flags);
      }

      /* update totalreserve_pages */
      calculate_totalreserve_pages();
}

/**
 * The inactive anon list should be small enough that the VM never has to
 * do too much work, but large enough that each inactive page has a chance
 * to be referenced again before it is swapped out.
 *
 * The inactive_anon ratio is the target ratio of ACTIVE_ANON to
 * INACTIVE_ANON pages on this zone's LRU, maintained by the
 * pageout code. A zone->inactive_ratio of 3 means 3:1 or 25% of
 * the anonymous pages are kept on the inactive list.
 *
 * total     target    max
 * memory    ratio     inactive anon
 * -------------------------------------
 *   10MB       1         5MB
 *  100MB       1        50MB
 *    1GB       3       250MB
 *   10GB      10       0.9GB
 *  100GB      31         3GB
 *    1TB     101        10GB
 *   10TB     320        32GB
 */
void calculate_zone_inactive_ratio(struct zone *zone)
{
      unsigned int gb, ratio;

      /* Zone size in gigabytes */
      gb = zone->present_pages >> (30 - PAGE_SHIFT);
      if (gb)
            ratio = int_sqrt(10 * gb);
      else
            ratio = 1;

      zone->inactive_ratio = ratio;
}

static void __init setup_per_zone_inactive_ratio(void)
{
      struct zone *zone;

      for_each_zone(zone)
            calculate_zone_inactive_ratio(zone);
}

/*
 * 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_wmark_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_wmarks();
      setup_per_zone_lowmem_reserve();
      setup_per_zone_inactive_ratio();
      return 0;
}
module_init(init_per_zone_wmark_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);
      if (write)
            setup_per_zone_wmarks();
      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
 * minimum 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_populated_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_nopanic(size);
            else if (hashdist)
                  table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
            else {
                  /*
                   * If bucketsize is not a power-of-two, we may free
                   * some pages at the end of hash table which
                   * alloc_pages_exact() automatically does
                   */
                  if (get_order(size) < MAX_ORDER) {
                        table = alloc_pages_exact(size, GFP_ATOMIC);
                        kmemleak_alloc(table, size, 1, GFP_ATOMIC);
                  }
            }
      } while (!table && size > PAGE_SIZE && --log2qty);

      if (!table)
            panic("Failed to allocate %s hash table\n", tablename);

      printk(KERN_INFO "%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;
}

/* Return a pointer to the bitmap storing bits affecting a block of pages */
static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
                                          unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
      return __pfn_to_section(pfn)->pageblock_flags;
#else
      return zone->pageblock_flags;
#endif /* CONFIG_SPARSEMEM */
}

static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
      pfn &= (PAGES_PER_SECTION-1);
      return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#else
      pfn = pfn - zone->zone_start_pfn;
      return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#endif /* CONFIG_SPARSEMEM */
}

/**
 * get_pageblock_flags_group - Return the requested group of flags for the pageblock_nr_pages block of pages
 * @page: The page within the block of interest
 * @start_bitidx: The first bit of interest to retrieve
 * @end_bitidx: The last bit of interest
 * returns pageblock_bits flags
 */
unsigned long get_pageblock_flags_group(struct page *page,
                              int start_bitidx, int end_bitidx)
{
      struct zone *zone;
      unsigned long *bitmap;
      unsigned long pfn, bitidx;
      unsigned long flags = 0;
      unsigned long value = 1;

      zone = page_zone(page);
      pfn = page_to_pfn(page);
      bitmap = get_pageblock_bitmap(zone, pfn);
      bitidx = pfn_to_bitidx(zone, pfn);

      for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
            if (test_bit(bitidx + start_bitidx, bitmap))
                  flags |= value;

      return flags;
}

/**
 * set_pageblock_flags_group - Set the requested group of flags for a pageblock_nr_pages block of pages
 * @page: The page within the block of interest
 * @start_bitidx: The first bit of interest
 * @end_bitidx: The last bit of interest
 * @flags: The flags to set
 */
void set_pageblock_flags_group(struct page *page, unsigned long flags,
                              int start_bitidx, int end_bitidx)
{
      struct zone *zone;
      unsigned long *bitmap;
      unsigned long pfn, bitidx;
      unsigned long value = 1;

      zone = page_zone(page);
      pfn = page_to_pfn(page);
      bitmap = get_pageblock_bitmap(zone, pfn);
      bitidx = pfn_to_bitidx(zone, pfn);
      VM_BUG_ON(pfn < zone->zone_start_pfn);
      VM_BUG_ON(pfn >= zone->zone_start_pfn + zone->spanned_pages);

      for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
            if (flags & value)
                  __set_bit(bitidx + start_bitidx, bitmap);
            else
                  __clear_bit(bitidx + start_bitidx, bitmap);
}

/*
 * This is designed as sub function...plz see page_isolation.c also.
 * set/clear page block's type to be ISOLATE.
 * page allocater never alloc memory from ISOLATE block.
 */

int set_migratetype_isolate(struct page *page)
{
      struct zone *zone;
      unsigned long flags;
      int ret = -EBUSY;

      zone = page_zone(page);
      spin_lock_irqsave(&zone->lock, flags);
      /*
       * In future, more migrate types will be able to be isolation target.
       */
      if (get_pageblock_migratetype(page) != MIGRATE_MOVABLE)
            goto out;
      set_pageblock_migratetype(page, MIGRATE_ISOLATE);
      move_freepages_block(zone, page, MIGRATE_ISOLATE);
      ret = 0;
out:
      spin_unlock_irqrestore(&zone->lock, flags);
      if (!ret)
            drain_all_pages();
      return ret;
}

void unset_migratetype_isolate(struct page *page)
{
      struct zone *zone;
      unsigned long flags;
      zone = page_zone(page);
      spin_lock_irqsave(&zone->lock, flags);
      if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
            goto out;
      set_pageblock_migratetype(page, MIGRATE_MOVABLE);
      move_freepages_block(zone, page, MIGRATE_MOVABLE);
out:
      spin_unlock_irqrestore(&zone->lock, flags);
}

#ifdef CONFIG_MEMORY_HOTREMOVE
/*
 * All pages in the range must be isolated before calling this.
 */
void
__offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
{
      struct page *page;
      struct zone *zone;
      int order, i;
      unsigned long pfn;
      unsigned long flags;
      /* find the first valid pfn */
      for (pfn = start_pfn; pfn < end_pfn; pfn++)
            if (pfn_valid(pfn))
                  break;
      if (pfn == end_pfn)
            return;
      zone = page_zone(pfn_to_page(pfn));
      spin_lock_irqsave(&zone->lock, flags);
      pfn = start_pfn;
      while (pfn < end_pfn) {
            if (!pfn_valid(pfn)) {
                  pfn++;
                  continue;
            }
            page = pfn_to_page(pfn);
            BUG_ON(page_count(page));
            BUG_ON(!PageBuddy(page));
            order = page_order(page);
#ifdef CONFIG_DEBUG_VM
            printk(KERN_INFO "remove from free list %lx %d %lx\n",
                   pfn, 1 << order, end_pfn);
#endif
            list_del(&page->lru);
            rmv_page_order(page);
            zone->free_area[order].nr_free--;
            __mod_zone_page_state(zone, NR_FREE_PAGES,
                              - (1UL << order));
            for (i = 0; i < (1 << order); i++)
                  SetPageReserved((page+i));
            pfn += (1 << order);
      }
      spin_unlock_irqrestore(&zone->lock, flags);
}
#endif

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