Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2220 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
new file mode 100644
index 000000000000..c73dbbc1cd8f
--- /dev/null
+++ b/mm/page_alloc.c
@@ -0,0 +1,2220 @@
+/*
+ *  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/config.h>
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/interrupt.h>
+#include <linux/pagemap.h>
+#include <linux/bootmem.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+#include <linux/pagevec.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/notifier.h>
+#include <linux/topology.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/nodemask.h>
+#include <linux/vmalloc.h>
+
+#include <asm/tlbflush.h>
+#include "internal.h"
+
+/*
+ * MCD - HACK: Find somewhere to initialize this EARLY, or make this
+ * initializer cleaner
+ */
+nodemask_t node_online_map = { { [0] = 1UL } };
+nodemask_t node_possible_map = NODE_MASK_ALL;
+struct pglist_data *pgdat_list;
+unsigned long totalram_pages;
+unsigned long totalhigh_pages;
+long nr_swap_pages;
+
+/*
+ * 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
+ */
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = { 256, 32 };
+
+EXPORT_SYMBOL(totalram_pages);
+EXPORT_SYMBOL(nr_swap_pages);
+
+/*
+ * Used by page_zone() to look up the address of the struct zone whose
+ * id is encoded in the upper bits of page->flags
+ */
+struct zone *zone_table[1 << (ZONES_SHIFT + NODES_SHIFT)];
+EXPORT_SYMBOL(zone_table);
+
+static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" };
+int min_free_kbytes = 1024;
+
+unsigned long __initdata nr_kernel_pages;
+unsigned long __initdata nr_all_pages;
+
+/*
+ * Temporary debugging check for pages not lying within a given zone.
+ */
+static int bad_range(struct zone *zone, struct page *page)
+{
+	if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)
+		return 1;
+	if (page_to_pfn(page) < zone->zone_start_pfn)
+		return 1;
+#ifdef CONFIG_HOLES_IN_ZONE
+	if (!pfn_valid(page_to_pfn(page)))
+		return 1;
+#endif
+	if (zone != page_zone(page))
+		return 1;
+	return 0;
+}
+
+static void bad_page(const char *function, struct page *page)
+{
+	printk(KERN_EMERG "Bad page state at %s (in process '%s', page %p)\n",
+		function, current->comm, page);
+	printk(KERN_EMERG "flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
+		(int)(2*sizeof(page_flags_t)), (unsigned long)page->flags,
+		page->mapping, page_mapcount(page), page_count(page));
+	printk(KERN_EMERG "Backtrace:\n");
+	dump_stack();
+	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n");
+	page->flags &= ~(1 << PG_private	|
+			1 << PG_locked	|
+			1 << PG_lru	|
+			1 << PG_active	|
+			1 << PG_dirty	|
+			1 << PG_swapcache |
+			1 << PG_writeback);
+	set_page_count(page, 0);
+	reset_page_mapcount(page);
+	page->mapping = NULL;
+	tainted |= TAINT_BAD_PAGE;
+}
+
+#ifndef CONFIG_HUGETLB_PAGE
+#define prep_compound_page(page, order) do { } while (0)
+#define destroy_compound_page(page, order) do { } while (0)
+#else
+/*
+ * 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 ->mapping, if non-zero, holds the address of the
+ * compound page's put_page() function.
+ *
+ * The order of the allocation is stored in the first tail page's ->index
+ * This is only for debug at present.  This usage means that zero-order pages
+ * may not be compound.
+ */
+static void prep_compound_page(struct page *page, unsigned long order)
+{
+	int i;
+	int nr_pages = 1 << order;
+
+	page[1].mapping = NULL;
+	page[1].index = order;
+	for (i = 0; i < nr_pages; i++) {
+		struct page *p = page + i;
+
+		SetPageCompound(p);
+		p->private = (unsigned long)page;
+	}
+}
+
+static void destroy_compound_page(struct page *page, unsigned long order)
+{
+	int i;
+	int nr_pages = 1 << order;
+
+	if (!PageCompound(page))
+		return;
+
+	if (page[1].index != order)
+		bad_page(__FUNCTION__, page);
+
+	for (i = 0; i < nr_pages; i++) {
+		struct page *p = page + i;
+
+		if (!PageCompound(p))
+			bad_page(__FUNCTION__, page);
+		if (p->private != (unsigned long)page)
+			bad_page(__FUNCTION__, page);
+		ClearPageCompound(p);
+	}
+}
+#endif		/* CONFIG_HUGETLB_PAGE */
+
+/*
+ * function for dealing with page's order in buddy system.
+ * zone->lock is already acquired when we use these.
+ * So, we don't need atomic page->flags operations here.
+ */
+static inline unsigned long page_order(struct page *page) {
+	return page->private;
+}
+
+static inline void set_page_order(struct page *page, int order) {
+	page->private = order;
+	__SetPagePrivate(page);
+}
+
+static inline void rmv_page_order(struct page *page)
+{
+	__ClearPagePrivate(page);
+	page->private = 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 contigious 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 free &&
+ * (b) the buddy is on the buddy system &&
+ * (c) a page and its buddy have the same order.
+ * for recording page's order, we use page->private and PG_private.
+ *
+ */
+static inline int page_is_buddy(struct page *page, int order)
+{
+       if (PagePrivate(page)           &&
+           (page_order(page) == order) &&
+           !PageReserved(page)         &&
+            page_count(page) == 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_Private.Page's
+ * order is recorded in page->private 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_pages_bulk (struct page *page,
+		struct zone *zone, unsigned int order)
+{
+	unsigned long page_idx;
+	int order_size = 1 << order;
+
+	if (unlikely(order))
+		destroy_compound_page(page, order);
+
+	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
+
+	BUG_ON(page_idx & (order_size - 1));
+	BUG_ON(bad_range(zone, page));
+
+	zone->free_pages += order_size;
+	while (order < MAX_ORDER-1) {
+		unsigned long combined_idx;
+		struct free_area *area;
+		struct page *buddy;
+
+		combined_idx = __find_combined_index(page_idx, order);
+		buddy = __page_find_buddy(page, page_idx, order);
+
+		if (bad_range(zone, buddy))
+			break;
+		if (!page_is_buddy(buddy, order))
+			break;		/* Move the buddy up one level. */
+		list_del(&buddy->lru);
+		area = zone->free_area + order;
+		area->nr_free--;
+		rmv_page_order(buddy);
+		page = page + (combined_idx - page_idx);
+		page_idx = combined_idx;
+		order++;
+	}
+	set_page_order(page, order);
+	list_add(&page->lru, &zone->free_area[order].free_list);
+	zone->free_area[order].nr_free++;
+}
+
+static inline void free_pages_check(const char *function, struct page *page)
+{
+	if (	page_mapcount(page) ||
+		page->mapping != NULL ||
+		page_count(page) != 0 ||
+		(page->flags & (
+			1 << PG_lru	|
+			1 << PG_private |
+			1 << PG_locked	|
+			1 << PG_active	|
+			1 << PG_reclaim	|
+			1 << PG_slab	|
+			1 << PG_swapcache |
+			1 << PG_writeback )))
+		bad_page(function, page);
+	if (PageDirty(page))
+		ClearPageDirty(page);
+}
+
+/*
+ * Frees a list of pages. 
+ * Assumes all pages on list are in same zone, and of same order.
+ * count is the number of pages to free, or 0 for all on the list.
+ *
+ * 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 int
+free_pages_bulk(struct zone *zone, int count,
+		struct list_head *list, unsigned int order)
+{
+	unsigned long flags;
+	struct page *page = NULL;
+	int ret = 0;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	zone->all_unreclaimable = 0;
+	zone->pages_scanned = 0;
+	while (!list_empty(list) && count--) {
+		page = list_entry(list->prev, struct page, lru);
+		/* have to delete it as __free_pages_bulk list manipulates */
+		list_del(&page->lru);
+		__free_pages_bulk(page, zone, order);
+		ret++;
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+	return ret;
+}
+
+void __free_pages_ok(struct page *page, unsigned int order)
+{
+	LIST_HEAD(list);
+	int i;
+
+	arch_free_page(page, order);
+
+	mod_page_state(pgfree, 1 << order);
+
+#ifndef CONFIG_MMU
+	if (order > 0)
+		for (i = 1 ; i < (1 << order) ; ++i)
+			__put_page(page + i);
+#endif
+
+	for (i = 0 ; i < (1 << order) ; ++i)
+		free_pages_check(__FUNCTION__, page + i);
+	list_add(&page->lru, &list);
+	kernel_map_pages(page, 1<<order, 0);
+	free_pages_bulk(page_zone(page), 1, &list, 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 struct page *
+expand(struct zone *zone, struct page *page,
+ 	int low, int high, struct free_area *area)
+{
+	unsigned long size = 1 << high;
+
+	while (high > low) {
+		area--;
+		high--;
+		size >>= 1;
+		BUG_ON(bad_range(zone, &page[size]));
+		list_add(&page[size].lru, &area->free_list);
+		area->nr_free++;
+		set_page_order(&page[size], high);
+	}
+	return page;
+}
+
+void set_page_refs(struct page *page, int order)
+{
+#ifdef CONFIG_MMU
+	set_page_count(page, 1);
+#else
+	int i;
+
+	/*
+	 * We need to reference all the pages for this order, otherwise if
+	 * anyone accesses one of the pages with (get/put) it will be freed.
+	 * - eg: access_process_vm()
+	 */
+	for (i = 0; i < (1 << order); i++)
+		set_page_count(page + i, 1);
+#endif /* CONFIG_MMU */
+}
+
+/*
+ * This page is about to be returned from the page allocator
+ */
+static void prep_new_page(struct page *page, int order)
+{
+	if (page->mapping || page_mapcount(page) ||
+	    (page->flags & (
+			1 << PG_private	|
+			1 << PG_locked	|
+			1 << PG_lru	|
+			1 << PG_active	|
+			1 << PG_dirty	|
+			1 << PG_reclaim	|
+			1 << PG_swapcache |
+			1 << PG_writeback )))
+		bad_page(__FUNCTION__, page);
+
+	page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
+			1 << PG_referenced | 1 << PG_arch_1 |
+			1 << PG_checked | 1 << PG_mappedtodisk);
+	page->private = 0;
+	set_page_refs(page, order);
+	kernel_map_pages(page, 1 << order, 1);
+}
+
+/* 
+ * Do the hard work of removing an element from the buddy allocator.
+ * Call me with the zone->lock already held.
+ */
+static struct page *__rmqueue(struct zone *zone, unsigned int order)
+{
+	struct free_area * area;
+	unsigned int current_order;
+	struct page *page;
+
+	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
+		area = zone->free_area + current_order;
+		if (list_empty(&area->free_list))
+			continue;
+
+		page = list_entry(area->free_list.next, struct page, lru);
+		list_del(&page->lru);
+		rmv_page_order(page);
+		area->nr_free--;
+		zone->free_pages -= 1UL << order;
+		return expand(zone, page, order, current_order, area);
+	}
+
+	return NULL;
+}
+
+/* 
+ * Obtain a specified number of elements from the buddy allocator, all under
+ * a single hold of the lock, for efficiency.  Add them to the supplied list.
+ * Returns the number of new pages which were placed at *list.
+ */
+static int rmqueue_bulk(struct zone *zone, unsigned int order, 
+			unsigned long count, struct list_head *list)
+{
+	unsigned long flags;
+	int i;
+	int allocated = 0;
+	struct page *page;
+	
+	spin_lock_irqsave(&zone->lock, flags);
+	for (i = 0; i < count; ++i) {
+		page = __rmqueue(zone, order);
+		if (page == NULL)
+			break;
+		allocated++;
+		list_add_tail(&page->lru, list);
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+	return allocated;
+}
+
+#if defined(CONFIG_PM) || defined(CONFIG_HOTPLUG_CPU)
+static void __drain_pages(unsigned int cpu)
+{
+	struct zone *zone;
+	int i;
+
+	for_each_zone(zone) {
+		struct per_cpu_pageset *pset;
+
+		pset = &zone->pageset[cpu];
+		for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
+			struct per_cpu_pages *pcp;
+
+			pcp = &pset->pcp[i];
+			pcp->count -= free_pages_bulk(zone, pcp->count,
+						&pcp->list, 0);
+		}
+	}
+}
+#endif /* CONFIG_PM || CONFIG_HOTPLUG_CPU */
+
+#ifdef CONFIG_PM
+
+void mark_free_pages(struct zone *zone)
+{
+	unsigned long zone_pfn, flags;
+	int order;
+	struct list_head *curr;
+
+	if (!zone->spanned_pages)
+		return;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
+		ClearPageNosaveFree(pfn_to_page(zone_pfn + zone->zone_start_pfn));
+
+	for (order = MAX_ORDER - 1; order >= 0; --order)
+		list_for_each(curr, &zone->free_area[order].free_list) {
+			unsigned long start_pfn, i;
+
+			start_pfn = page_to_pfn(list_entry(curr, struct page, lru));
+
+			for (i=0; i < (1<<order); i++)
+				SetPageNosaveFree(pfn_to_page(start_pfn+i));
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+/*
+ * Spill all of this CPU's per-cpu pages back into the buddy allocator.
+ */
+void drain_local_pages(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);	
+	__drain_pages(smp_processor_id());
+	local_irq_restore(flags);	
+}
+#endif /* CONFIG_PM */
+
+static void zone_statistics(struct zonelist *zonelist, struct zone *z)
+{
+#ifdef CONFIG_NUMA
+	unsigned long flags;
+	int cpu;
+	pg_data_t *pg = z->zone_pgdat;
+	pg_data_t *orig = zonelist->zones[0]->zone_pgdat;
+	struct per_cpu_pageset *p;
+
+	local_irq_save(flags);
+	cpu = smp_processor_id();
+	p = &z->pageset[cpu];
+	if (pg == orig) {
+		z->pageset[cpu].numa_hit++;
+	} else {
+		p->numa_miss++;
+		zonelist->zones[0]->pageset[cpu].numa_foreign++;
+	}
+	if (pg == NODE_DATA(numa_node_id()))
+		p->local_node++;
+	else
+		p->other_node++;
+	local_irq_restore(flags);
+#endif
+}
+
+/*
+ * Free a 0-order page
+ */
+static void FASTCALL(free_hot_cold_page(struct page *page, int cold));
+static void fastcall free_hot_cold_page(struct page *page, int cold)
+{
+	struct zone *zone = page_zone(page);
+	struct per_cpu_pages *pcp;
+	unsigned long flags;
+
+	arch_free_page(page, 0);
+
+	kernel_map_pages(page, 1, 0);
+	inc_page_state(pgfree);
+	if (PageAnon(page))
+		page->mapping = NULL;
+	free_pages_check(__FUNCTION__, page);
+	pcp = &zone->pageset[get_cpu()].pcp[cold];
+	local_irq_save(flags);
+	if (pcp->count >= pcp->high)
+		pcp->count -= free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
+	list_add(&page->lru, &pcp->list);
+	pcp->count++;
+	local_irq_restore(flags);
+	put_cpu();
+}
+
+void fastcall free_hot_page(struct page *page)
+{
+	free_hot_cold_page(page, 0);
+}
+	
+void fastcall free_cold_page(struct page *page)
+{
+	free_hot_cold_page(page, 1);
+}
+
+static inline void prep_zero_page(struct page *page, int order, unsigned int __nocast gfp_flags)
+{
+	int i;
+
+	BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
+	for(i = 0; i < (1 << order); i++)
+		clear_highpage(page + i);
+}
+
+/*
+ * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
+ * we cheat by calling it from here, in the order > 0 path.  Saves a branch
+ * or two.
+ */
+static struct page *
+buffered_rmqueue(struct zone *zone, int order, unsigned int __nocast gfp_flags)
+{
+	unsigned long flags;
+	struct page *page = NULL;
+	int cold = !!(gfp_flags & __GFP_COLD);
+
+	if (order == 0) {
+		struct per_cpu_pages *pcp;
+
+		pcp = &zone->pageset[get_cpu()].pcp[cold];
+		local_irq_save(flags);
+		if (pcp->count <= pcp->low)
+			pcp->count += rmqueue_bulk(zone, 0,
+						pcp->batch, &pcp->list);
+		if (pcp->count) {
+			page = list_entry(pcp->list.next, struct page, lru);
+			list_del(&page->lru);
+			pcp->count--;
+		}
+		local_irq_restore(flags);
+		put_cpu();
+	}
+
+	if (page == NULL) {
+		spin_lock_irqsave(&zone->lock, flags);
+		page = __rmqueue(zone, order);
+		spin_unlock_irqrestore(&zone->lock, flags);
+	}
+
+	if (page != NULL) {
+		BUG_ON(bad_range(zone, page));
+		mod_page_state_zone(zone, pgalloc, 1 << order);
+		prep_new_page(page, order);
+
+		if (gfp_flags & __GFP_ZERO)
+			prep_zero_page(page, order, gfp_flags);
+
+		if (order && (gfp_flags & __GFP_COMP))
+			prep_compound_page(page, order);
+	}
+	return page;
+}
+
+/*
+ * 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 can_try_harder, int gfp_high)
+{
+	/* free_pages my go negative - that's OK */
+	long min = mark, free_pages = z->free_pages - (1 << order) + 1;
+	int o;
+
+	if (gfp_high)
+		min -= min / 2;
+	if (can_try_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;
+}
+
+/*
+ * This is the 'heart' of the zoned buddy allocator.
+ */
+struct page * fastcall
+__alloc_pages(unsigned int __nocast gfp_mask, unsigned int order,
+		struct zonelist *zonelist)
+{
+	const int wait = gfp_mask & __GFP_WAIT;
+	struct zone **zones, *z;
+	struct page *page;
+	struct reclaim_state reclaim_state;
+	struct task_struct *p = current;
+	int i;
+	int classzone_idx;
+	int do_retry;
+	int can_try_harder;
+	int did_some_progress;
+
+	might_sleep_if(wait);
+
+	/*
+	 * The caller may dip into page reserves a bit more if the caller
+	 * cannot run direct reclaim, or is the caller has realtime scheduling
+	 * policy
+	 */
+	can_try_harder = (unlikely(rt_task(p)) && !in_interrupt()) || !wait;
+
+	zones = zonelist->zones;  /* the list of zones suitable for gfp_mask */
+
+	if (unlikely(zones[0] == NULL)) {
+		/* Should this ever happen?? */
+		return NULL;
+	}
+
+	classzone_idx = zone_idx(zones[0]);
+
+ restart:
+	/* Go through the zonelist once, looking for a zone with enough free */
+	for (i = 0; (z = zones[i]) != NULL; i++) {
+
+		if (!zone_watermark_ok(z, order, z->pages_low,
+				       classzone_idx, 0, 0))
+			continue;
+
+		if (!cpuset_zone_allowed(z))
+			continue;
+
+		page = buffered_rmqueue(z, order, gfp_mask);
+		if (page)
+			goto got_pg;
+	}
+
+	for (i = 0; (z = zones[i]) != NULL; i++)
+		wakeup_kswapd(z, order);
+
+	/*
+	 * Go through the zonelist again. Let __GFP_HIGH and allocations
+	 * coming from realtime tasks to go deeper into reserves
+	 *
+	 * This is the last chance, in general, before the goto nopage.
+	 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
+	 */
+	for (i = 0; (z = zones[i]) != NULL; i++) {
+		if (!zone_watermark_ok(z, order, z->pages_min,
+				       classzone_idx, can_try_harder,
+				       gfp_mask & __GFP_HIGH))
+			continue;
+
+		if (wait && !cpuset_zone_allowed(z))
+			continue;
+
+		page = buffered_rmqueue(z, order, gfp_mask);
+		if (page)
+			goto got_pg;
+	}
+
+	/* This allocation should allow future memory freeing. */
+	if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE))) && !in_interrupt()) {
+		/* go through the zonelist yet again, ignoring mins */
+		for (i = 0; (z = zones[i]) != NULL; i++) {
+			if (!cpuset_zone_allowed(z))
+				continue;
+			page = buffered_rmqueue(z, order, gfp_mask);
+			if (page)
+				goto got_pg;
+		}
+		goto nopage;
+	}
+
+	/* Atomic allocations - we can't balance anything */
+	if (!wait)
+		goto nopage;
+
+rebalance:
+	cond_resched();
+
+	/* We now go into synchronous reclaim */
+	p->flags |= PF_MEMALLOC;
+	reclaim_state.reclaimed_slab = 0;
+	p->reclaim_state = &reclaim_state;
+
+	did_some_progress = try_to_free_pages(zones, gfp_mask, order);
+
+	p->reclaim_state = NULL;
+	p->flags &= ~PF_MEMALLOC;
+
+	cond_resched();
+
+	if (likely(did_some_progress)) {
+		/*
+		 * 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.
+		 */
+		for (i = 0; (z = zones[i]) != NULL; i++) {
+			if (!zone_watermark_ok(z, order, z->pages_min,
+					       classzone_idx, can_try_harder,
+					       gfp_mask & __GFP_HIGH))
+				continue;
+
+			if (!cpuset_zone_allowed(z))
+				continue;
+
+			page = buffered_rmqueue(z, order, gfp_mask);
+			if (page)
+				goto got_pg;
+		}
+	} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
+		/*
+		 * Go through the zonelist yet one more time, keep
+		 * very high watermark here, this is only to catch
+		 * a parallel oom killing, we must fail if we're still
+		 * under heavy pressure.
+		 */
+		for (i = 0; (z = zones[i]) != NULL; i++) {
+			if (!zone_watermark_ok(z, order, z->pages_high,
+					       classzone_idx, 0, 0))
+				continue;
+
+			if (!cpuset_zone_allowed(z))
+				continue;
+
+			page = buffered_rmqueue(z, order, gfp_mask);
+			if (page)
+				goto got_pg;
+		}
+
+		out_of_memory(gfp_mask);
+		goto restart;
+	}
+
+	/*
+	 * Don't let big-order allocations loop unless the caller explicitly
+	 * requests that.  Wait for some write requests to complete then retry.
+	 *
+	 * In this implementation, __GFP_REPEAT means __GFP_NOFAIL for order
+	 * <= 3, but that may not be true in other implementations.
+	 */
+	do_retry = 0;
+	if (!(gfp_mask & __GFP_NORETRY)) {
+		if ((order <= 3) || (gfp_mask & __GFP_REPEAT))
+			do_retry = 1;
+		if (gfp_mask & __GFP_NOFAIL)
+			do_retry = 1;
+	}
+	if (do_retry) {
+		blk_congestion_wait(WRITE, HZ/50);
+		goto rebalance;
+	}
+
+nopage:
+	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) {
+		printk(KERN_WARNING "%s: page allocation failure."
+			" order:%d, mode:0x%x\n",
+			p->comm, order, gfp_mask);
+		dump_stack();
+	}
+	return NULL;
+got_pg:
+	zone_statistics(zonelist, z);
+	return page;
+}
+
+EXPORT_SYMBOL(__alloc_pages);
+
+/*
+ * Common helper functions.
+ */
+fastcall unsigned long __get_free_pages(unsigned int __nocast gfp_mask, unsigned int order)
+{
+	struct page * page;
+	page = alloc_pages(gfp_mask, order);
+	if (!page)
+		return 0;
+	return (unsigned long) page_address(page);
+}
+
+EXPORT_SYMBOL(__get_free_pages);
+
+fastcall unsigned long get_zeroed_page(unsigned int __nocast gfp_mask)
+{
+	struct page * page;
+
+	/*
+	 * get_zeroed_page() returns a 32-bit address, which cannot represent
+	 * a highmem page
+	 */
+	BUG_ON(gfp_mask & __GFP_HIGHMEM);
+
+	page = alloc_pages(gfp_mask | __GFP_ZERO, 0);
+	if (page)
+		return (unsigned long) page_address(page);
+	return 0;
+}
+
+EXPORT_SYMBOL(get_zeroed_page);
+
+void __pagevec_free(struct pagevec *pvec)
+{
+	int i = pagevec_count(pvec);
+
+	while (--i >= 0)
+		free_hot_cold_page(pvec->pages[i], pvec->cold);
+}
+
+fastcall void __free_pages(struct page *page, unsigned int order)
+{
+	if (!PageReserved(page) && put_page_testzero(page)) {
+		if (order == 0)
+			free_hot_page(page);
+		else
+			__free_pages_ok(page, order);
+	}
+}
+
+EXPORT_SYMBOL(__free_pages);
+
+fastcall void free_pages(unsigned long addr, unsigned int order)
+{
+	if (addr != 0) {
+		BUG_ON(!virt_addr_valid((void *)addr));
+		__free_pages(virt_to_page((void *)addr), order);
+	}
+}
+
+EXPORT_SYMBOL(free_pages);
+
+/*
+ * Total amount of free (allocatable) RAM:
+ */
+unsigned int nr_free_pages(void)
+{
+	unsigned int sum = 0;
+	struct zone *zone;
+
+	for_each_zone(zone)
+		sum += zone->free_pages;
+
+	return sum;
+}
+
+EXPORT_SYMBOL(nr_free_pages);
+
+#ifdef CONFIG_NUMA
+unsigned int nr_free_pages_pgdat(pg_data_t *pgdat)
+{
+	unsigned int i, sum = 0;
+
+	for (i = 0; i < MAX_NR_ZONES; i++)
+		sum += pgdat->node_zones[i].free_pages;
+
+	return sum;
+}
+#endif
+
+static unsigned int nr_free_zone_pages(int offset)
+{
+	pg_data_t *pgdat;
+	unsigned int sum = 0;
+
+	for_each_pgdat(pgdat) {
+		struct zonelist *zonelist = pgdat->node_zonelists + offset;
+		struct zone **zonep = zonelist->zones;
+		struct zone *zone;
+
+		for (zone = *zonep++; zone; zone = *zonep++) {
+			unsigned long size = zone->present_pages;
+			unsigned long high = zone->pages_high;
+			if (size > high)
+				sum += size - high;
+		}
+	}
+
+	return sum;
+}
+
+/*
+ * Amount of free RAM allocatable within ZONE_DMA and ZONE_NORMAL
+ */
+unsigned int nr_free_buffer_pages(void)
+{
+	return nr_free_zone_pages(GFP_USER & GFP_ZONEMASK);
+}
+
+/*
+ * Amount of free RAM allocatable within all zones
+ */
+unsigned int nr_free_pagecache_pages(void)
+{
+	return nr_free_zone_pages(GFP_HIGHUSER & GFP_ZONEMASK);
+}
+
+#ifdef CONFIG_HIGHMEM
+unsigned int nr_free_highpages (void)
+{
+	pg_data_t *pgdat;
+	unsigned int pages = 0;
+
+	for_each_pgdat(pgdat)
+		pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages;
+
+	return pages;
+}
+#endif
+
+#ifdef CONFIG_NUMA
+static void show_node(struct zone *zone)
+{
+	printk("Node %d ", zone->zone_pgdat->node_id);
+}
+#else
+#define show_node(zone)	do { } while (0)
+#endif
+
+/*
+ * Accumulate the page_state information across all CPUs.
+ * The result is unavoidably approximate - it can change
+ * during and after execution of this function.
+ */
+static DEFINE_PER_CPU(struct page_state, page_states) = {0};
+
+atomic_t nr_pagecache = ATOMIC_INIT(0);
+EXPORT_SYMBOL(nr_pagecache);
+#ifdef CONFIG_SMP
+DEFINE_PER_CPU(long, nr_pagecache_local) = 0;
+#endif
+
+void __get_page_state(struct page_state *ret, int nr)
+{
+	int cpu = 0;
+
+	memset(ret, 0, sizeof(*ret));
+
+	cpu = first_cpu(cpu_online_map);
+	while (cpu < NR_CPUS) {
+		unsigned long *in, *out, off;
+
+		in = (unsigned long *)&per_cpu(page_states, cpu);
+
+		cpu = next_cpu(cpu, cpu_online_map);
+
+		if (cpu < NR_CPUS)
+			prefetch(&per_cpu(page_states, cpu));
+
+		out = (unsigned long *)ret;
+		for (off = 0; off < nr; off++)
+			*out++ += *in++;
+	}
+}
+
+void get_page_state(struct page_state *ret)
+{
+	int nr;
+
+	nr = offsetof(struct page_state, GET_PAGE_STATE_LAST);
+	nr /= sizeof(unsigned long);
+
+	__get_page_state(ret, nr + 1);
+}
+
+void get_full_page_state(struct page_state *ret)
+{
+	__get_page_state(ret, sizeof(*ret) / sizeof(unsigned long));
+}
+
+unsigned long __read_page_state(unsigned offset)
+{
+	unsigned long ret = 0;
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		unsigned long in;
+
+		in = (unsigned long)&per_cpu(page_states, cpu) + offset;
+		ret += *((unsigned long *)in);
+	}
+	return ret;
+}
+
+void __mod_page_state(unsigned offset, unsigned long delta)
+{
+	unsigned long flags;
+	void* ptr;
+
+	local_irq_save(flags);
+	ptr = &__get_cpu_var(page_states);
+	*(unsigned long*)(ptr + offset) += delta;
+	local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL(__mod_page_state);
+
+void __get_zone_counts(unsigned long *active, unsigned long *inactive,
+			unsigned long *free, struct pglist_data *pgdat)
+{
+	struct zone *zones = pgdat->node_zones;
+	int i;
+
+	*active = 0;
+	*inactive = 0;
+	*free = 0;
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		*active += zones[i].nr_active;
+		*inactive += zones[i].nr_inactive;
+		*free += zones[i].free_pages;
+	}
+}
+
+void get_zone_counts(unsigned long *active,
+		unsigned long *inactive, unsigned long *free)
+{
+	struct pglist_data *pgdat;
+
+	*active = 0;
+	*inactive = 0;
+	*free = 0;
+	for_each_pgdat(pgdat) {
+		unsigned long l, m, n;
+		__get_zone_counts(&l, &m, &n, pgdat);
+		*active += l;
+		*inactive += m;
+		*free += n;
+	}
+}
+
+void si_meminfo(struct sysinfo *val)
+{
+	val->totalram = totalram_pages;
+	val->sharedram = 0;
+	val->freeram = nr_free_pages();
+	val->bufferram = nr_blockdev_pages();
+#ifdef CONFIG_HIGHMEM
+	val->totalhigh = totalhigh_pages;
+	val->freehigh = nr_free_highpages();
+#else
+	val->totalhigh = 0;
+	val->freehigh = 0;
+#endif
+	val->mem_unit = PAGE_SIZE;
+}
+
+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 = nr_free_pages_pgdat(pgdat);
+	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
+	val->freehigh = pgdat->node_zones[ZONE_HIGHMEM].free_pages;
+	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)
+{
+	struct page_state ps;
+	int cpu, temperature;
+	unsigned long active;
+	unsigned long inactive;
+	unsigned long free;
+	struct zone *zone;
+
+	for_each_zone(zone) {
+		show_node(zone);
+		printk("%s per-cpu:", zone->name);
+
+		if (!zone->present_pages) {
+			printk(" empty\n");
+			continue;
+		} else
+			printk("\n");
+
+		for (cpu = 0; cpu < NR_CPUS; ++cpu) {
+			struct per_cpu_pageset *pageset;
+
+			if (!cpu_possible(cpu))
+				continue;
+
+			pageset = zone->pageset + cpu;
+
+			for (temperature = 0; temperature < 2; temperature++)
+				printk("cpu %d %s: low %d, high %d, batch %d\n",
+					cpu,
+					temperature ? "cold" : "hot",
+					pageset->pcp[temperature].low,
+					pageset->pcp[temperature].high,
+					pageset->pcp[temperature].batch);
+		}
+	}
+
+	get_page_state(&ps);
+	get_zone_counts(&active, &inactive, &free);
+
+	printk("\nFree pages: %11ukB (%ukB HighMem)\n",
+		K(nr_free_pages()),
+		K(nr_free_highpages()));
+
+	printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu "
+		"unstable:%lu free:%u slab:%lu mapped:%lu pagetables:%lu\n",
+		active,
+		inactive,
+		ps.nr_dirty,
+		ps.nr_writeback,
+		ps.nr_unstable,
+		nr_free_pages(),
+		ps.nr_slab,
+		ps.nr_mapped,
+		ps.nr_page_table_pages);
+
+	for_each_zone(zone) {
+		int i;
+
+		show_node(zone);
+		printk("%s"
+			" free:%lukB"
+			" min:%lukB"
+			" low:%lukB"
+			" high:%lukB"
+			" active:%lukB"
+			" inactive:%lukB"
+			" present:%lukB"
+			" pages_scanned:%lu"
+			" all_unreclaimable? %s"
+			"\n",
+			zone->name,
+			K(zone->free_pages),
+			K(zone->pages_min),
+			K(zone->pages_low),
+			K(zone->pages_high),
+			K(zone->nr_active),
+			K(zone->nr_inactive),
+			K(zone->present_pages),
+			zone->pages_scanned,
+			(zone->all_unreclaimable ? "yes" : "no")
+			);
+		printk("lowmem_reserve[]:");
+		for (i = 0; i < MAX_NR_ZONES; i++)
+			printk(" %lu", zone->lowmem_reserve[i]);
+		printk("\n");
+	}
+
+	for_each_zone(zone) {
+ 		unsigned long nr, flags, order, total = 0;
+
+		show_node(zone);
+		printk("%s: ", zone->name);
+		if (!zone->present_pages) {
+			printk("empty\n");
+			continue;
+		}
+
+		spin_lock_irqsave(&zone->lock, flags);
+		for (order = 0; order < MAX_ORDER; order++) {
+			nr = zone->free_area[order].nr_free;
+			total += nr << order;
+			printk("%lu*%lukB ", nr, K(1UL) << order);
+		}
+		spin_unlock_irqrestore(&zone->lock, flags);
+		printk("= %lukB\n", K(total));
+	}
+
+	show_swap_cache_info();
+}
+
+/*
+ * Builds allocation fallback zone lists.
+ */
+static int __init build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist, int j, int k)
+{
+	switch (k) {
+		struct zone *zone;
+	default:
+		BUG();
+	case ZONE_HIGHMEM:
+		zone = pgdat->node_zones + ZONE_HIGHMEM;
+		if (zone->present_pages) {
+#ifndef CONFIG_HIGHMEM
+			BUG();
+#endif
+			zonelist->zones[j++] = zone;
+		}
+	case ZONE_NORMAL:
+		zone = pgdat->node_zones + ZONE_NORMAL;
+		if (zone->present_pages)
+			zonelist->zones[j++] = zone;
+	case ZONE_DMA:
+		zone = pgdat->node_zones + ZONE_DMA;
+		if (zone->present_pages)
+			zonelist->zones[j++] = zone;
+	}
+
+	return j;
+}
+
+#ifdef CONFIG_NUMA
+#define MAX_NODE_LOAD (num_online_nodes())
+static int __initdata 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 __init find_next_best_node(int node, nodemask_t *used_node_mask)
+{
+	int i, n, val;
+	int min_val = INT_MAX;
+	int best_node = -1;
+
+	for_each_online_node(i) {
+		cpumask_t tmp;
+
+		/* Start from local node */
+		n = (node+i) % num_online_nodes();
+
+		/* Don't want a node to appear more than once */
+		if (node_isset(n, *used_node_mask))
+			continue;
+
+		/* Use the local node if we haven't already */
+		if (!node_isset(node, *used_node_mask)) {
+			best_node = node;
+			break;
+		}
+
+		/* Use the distance array to find the distance */
+		val = node_distance(node, n);
+
+		/* Give preference to headless and unused nodes */
+		tmp = node_to_cpumask(n);
+		if (!cpus_empty(tmp))
+			val += PENALTY_FOR_NODE_WITH_CPUS;
+
+		/* Slight preference for less loaded node */
+		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
+		val += node_load[n];
+
+		if (val < min_val) {
+			min_val = val;
+			best_node = n;
+		}
+	}
+
+	if (best_node >= 0)
+		node_set(best_node, *used_node_mask);
+
+	return best_node;
+}
+
+static void __init build_zonelists(pg_data_t *pgdat)
+{
+	int i, j, k, node, local_node;
+	int prev_node, load;
+	struct zonelist *zonelist;
+	nodemask_t used_mask;
+
+	/* initialize zonelists */
+	for (i = 0; i < GFP_ZONETYPES; i++) {
+		zonelist = pgdat->node_zonelists + i;
+		zonelist->zones[0] = NULL;
+	}
+
+	/* NUMA-aware ordering of nodes */
+	local_node = pgdat->node_id;
+	load = num_online_nodes();
+	prev_node = local_node;
+	nodes_clear(used_mask);
+	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+		/*
+		 * 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 (node_distance(local_node, node) !=
+				node_distance(local_node, prev_node))
+			node_load[node] += load;
+		prev_node = node;
+		load--;
+		for (i = 0; i < GFP_ZONETYPES; i++) {
+			zonelist = pgdat->node_zonelists + i;
+			for (j = 0; zonelist->zones[j] != NULL; j++);
+
+			k = ZONE_NORMAL;
+			if (i & __GFP_HIGHMEM)
+				k = ZONE_HIGHMEM;
+			if (i & __GFP_DMA)
+				k = ZONE_DMA;
+
+	 		j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+			zonelist->zones[j] = NULL;
+		}
+	}
+}
+
+#else	/* CONFIG_NUMA */
+
+static void __init build_zonelists(pg_data_t *pgdat)
+{
+	int i, j, k, node, local_node;
+
+	local_node = pgdat->node_id;
+	for (i = 0; i < GFP_ZONETYPES; i++) {
+		struct zonelist *zonelist;
+
+		zonelist = pgdat->node_zonelists + i;
+
+		j = 0;
+		k = ZONE_NORMAL;
+		if (i & __GFP_HIGHMEM)
+			k = ZONE_HIGHMEM;
+		if (i & __GFP_DMA)
+			k = ZONE_DMA;
+
+ 		j = build_zonelists_node(pgdat, zonelist, j, k);
+ 		/*
+ 		 * Now we build the zonelist so that it contains the zones
+ 		 * of all the other nodes.
+ 		 * We don't want to pressure a particular node, so when
+ 		 * building the zones for node N, we make sure that the
+ 		 * zones coming right after the local ones are those from
+ 		 * node N+1 (modulo N)
+ 		 */
+		for (node = local_node + 1; node < MAX_NUMNODES; node++) {
+			if (!node_online(node))
+				continue;
+			j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+		}
+		for (node = 0; node < local_node; node++) {
+			if (!node_online(node))
+				continue;
+			j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+		}
+
+		zonelist->zones[j] = NULL;
+	}
+}
+
+#endif	/* CONFIG_NUMA */
+
+void __init build_all_zonelists(void)
+{
+	int i;
+
+	for_each_online_node(i)
+		build_zonelists(NODE_DATA(i));
+	printk("Built %i zonelists\n", num_online_nodes());
+	cpuset_init_current_mems_allowed();
+}
+
+/*
+ * Helper functions to size the waitqueue hash table.
+ * Essentially these want to choose hash table sizes sufficiently
+ * large so that collisions trying to wait on pages are rare.
+ * But in fact, the number of active page waitqueues on typical
+ * systems is ridiculously low, less than 200. So this is even
+ * conservative, even though it seems large.
+ *
+ * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to
+ * waitqueues, i.e. the size of the waitq table given the number of pages.
+ */
+#define PAGES_PER_WAITQUEUE	256
+
+static inline unsigned long wait_table_size(unsigned long pages)
+{
+	unsigned long size = 1;
+
+	pages /= PAGES_PER_WAITQUEUE;
+
+	while (size < pages)
+		size <<= 1;
+
+	/*
+	 * Once we have dozens or even hundreds of threads sleeping
+	 * on IO we've got bigger problems than wait queue collision.
+	 * Limit the size of the wait table to a reasonable size.
+	 */
+	size = min(size, 4096UL);
+
+	return max(size, 4UL);
+}
+
+/*
+ * 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))
+
+static void __init calculate_zone_totalpages(struct pglist_data *pgdat,
+		unsigned long *zones_size, unsigned long *zholes_size)
+{
+	unsigned long realtotalpages, totalpages = 0;
+	int i;
+
+	for (i = 0; i < MAX_NR_ZONES; i++)
+		totalpages += zones_size[i];
+	pgdat->node_spanned_pages = totalpages;
+
+	realtotalpages = totalpages;
+	if (zholes_size)
+		for (i = 0; i < MAX_NR_ZONES; i++)
+			realtotalpages -= zholes_size[i];
+	pgdat->node_present_pages = realtotalpages;
+	printk(KERN_DEBUG "On node %d totalpages: %lu\n", pgdat->node_id, realtotalpages);
+}
+
+
+/*
+ * 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 __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
+		unsigned long start_pfn)
+{
+	struct page *start = pfn_to_page(start_pfn);
+	struct page *page;
+
+	for (page = start; page < (start + size); page++) {
+		set_page_zone(page, NODEZONE(nid, zone));
+		set_page_count(page, 0);
+		reset_page_mapcount(page);
+		SetPageReserved(page);
+		INIT_LIST_HEAD(&page->lru);
+#ifdef WANT_PAGE_VIRTUAL
+		/* The shift won't overflow because ZONE_NORMAL is below 4G. */
+		if (!is_highmem_idx(zone))
+			set_page_address(page, __va(start_pfn << PAGE_SHIFT));
+#endif
+		start_pfn++;
+	}
+}
+
+void zone_init_free_lists(struct pglist_data *pgdat, struct zone *zone,
+				unsigned long size)
+{
+	int order;
+	for (order = 0; order < MAX_ORDER ; order++) {
+		INIT_LIST_HEAD(&zone->free_area[order].free_list);
+		zone->free_area[order].nr_free = 0;
+	}
+}
+
+#ifndef __HAVE_ARCH_MEMMAP_INIT
+#define memmap_init(size, nid, zone, start_pfn) \
+	memmap_init_zone((size), (nid), (zone), (start_pfn))
+#endif
+
+/*
+ * Set up the zone data structures:
+ *   - mark all pages reserved
+ *   - mark all memory queues empty
+ *   - clear the memory bitmaps
+ */
+static void __init free_area_init_core(struct pglist_data *pgdat,
+		unsigned long *zones_size, unsigned long *zholes_size)
+{
+	unsigned long i, j;
+	const unsigned long zone_required_alignment = 1UL << (MAX_ORDER-1);
+	int cpu, nid = pgdat->node_id;
+	unsigned long zone_start_pfn = pgdat->node_start_pfn;
+
+	pgdat->nr_zones = 0;
+	init_waitqueue_head(&pgdat->kswapd_wait);
+	pgdat->kswapd_max_order = 0;
+	
+	for (j = 0; j < MAX_NR_ZONES; j++) {
+		struct zone *zone = pgdat->node_zones + j;
+		unsigned long size, realsize;
+		unsigned long batch;
+
+		zone_table[NODEZONE(nid, j)] = zone;
+		realsize = size = zones_size[j];
+		if (zholes_size)
+			realsize -= zholes_size[j];
+
+		if (j == ZONE_DMA || j == ZONE_NORMAL)
+			nr_kernel_pages += realsize;
+		nr_all_pages += realsize;
+
+		zone->spanned_pages = size;
+		zone->present_pages = realsize;
+		zone->name = zone_names[j];
+		spin_lock_init(&zone->lock);
+		spin_lock_init(&zone->lru_lock);
+		zone->zone_pgdat = pgdat;
+		zone->free_pages = 0;
+
+		zone->temp_priority = zone->prev_priority = DEF_PRIORITY;
+
+		/*
+		 * The per-cpu-pages pools are set to around 1000th of the
+		 * size of the zone.  But no more than 1/4 of a meg - there's
+		 * no point in going beyond the size of L2 cache.
+		 *
+		 * OK, so we don't know how big the cache is.  So guess.
+		 */
+		batch = zone->present_pages / 1024;
+		if (batch * PAGE_SIZE > 256 * 1024)
+			batch = (256 * 1024) / PAGE_SIZE;
+		batch /= 4;		/* We effectively *= 4 below */
+		if (batch < 1)
+			batch = 1;
+
+		for (cpu = 0; cpu < NR_CPUS; cpu++) {
+			struct per_cpu_pages *pcp;
+
+			pcp = &zone->pageset[cpu].pcp[0];	/* hot */
+			pcp->count = 0;
+			pcp->low = 2 * batch;
+			pcp->high = 6 * batch;
+			pcp->batch = 1 * batch;
+			INIT_LIST_HEAD(&pcp->list);
+
+			pcp = &zone->pageset[cpu].pcp[1];	/* cold */
+			pcp->count = 0;
+			pcp->low = 0;
+			pcp->high = 2 * batch;
+			pcp->batch = 1 * batch;
+			INIT_LIST_HEAD(&pcp->list);
+		}
+		printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%lu\n",
+				zone_names[j], realsize, batch);
+		INIT_LIST_HEAD(&zone->active_list);
+		INIT_LIST_HEAD(&zone->inactive_list);
+		zone->nr_scan_active = 0;
+		zone->nr_scan_inactive = 0;
+		zone->nr_active = 0;
+		zone->nr_inactive = 0;
+		if (!size)
+			continue;
+
+		/*
+		 * The per-page waitqueue mechanism uses hashed waitqueues
+		 * per zone.
+		 */
+		zone->wait_table_size = wait_table_size(size);
+		zone->wait_table_bits =
+			wait_table_bits(zone->wait_table_size);
+		zone->wait_table = (wait_queue_head_t *)
+			alloc_bootmem_node(pgdat, zone->wait_table_size
+						* sizeof(wait_queue_head_t));
+
+		for(i = 0; i < zone->wait_table_size; ++i)
+			init_waitqueue_head(zone->wait_table + i);
+
+		pgdat->nr_zones = j+1;
+
+		zone->zone_mem_map = pfn_to_page(zone_start_pfn);
+		zone->zone_start_pfn = zone_start_pfn;
+
+		if ((zone_start_pfn) & (zone_required_alignment-1))
+			printk(KERN_CRIT "BUG: wrong zone alignment, it will crash\n");
+
+		memmap_init(size, nid, j, zone_start_pfn);
+
+		zone_start_pfn += size;
+
+		zone_init_free_lists(pgdat, zone, zone->spanned_pages);
+	}
+}
+
+static void __init alloc_node_mem_map(struct pglist_data *pgdat)
+{
+	unsigned long size;
+
+	/* Skip empty nodes */
+	if (!pgdat->node_spanned_pages)
+		return;
+
+	/* ia64 gets its own node_mem_map, before this, without bootmem */
+	if (!pgdat->node_mem_map) {
+		size = (pgdat->node_spanned_pages + 1) * sizeof(struct page);
+		pgdat->node_mem_map = alloc_bootmem_node(pgdat, size);
+	}
+#ifndef CONFIG_DISCONTIGMEM
+	/*
+	 * 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;
+#endif
+}
+
+void __init free_area_init_node(int nid, struct pglist_data *pgdat,
+		unsigned long *zones_size, unsigned long node_start_pfn,
+		unsigned long *zholes_size)
+{
+	pgdat->node_id = nid;
+	pgdat->node_start_pfn = node_start_pfn;
+	calculate_zone_totalpages(pgdat, zones_size, zholes_size);
+
+	alloc_node_mem_map(pgdat);
+
+	free_area_init_core(pgdat, zones_size, zholes_size);
+}
+
+#ifndef CONFIG_DISCONTIGMEM
+static bootmem_data_t contig_bootmem_data;
+struct pglist_data contig_page_data = { .bdata = &contig_bootmem_data };
+
+EXPORT_SYMBOL(contig_page_data);
+
+void __init free_area_init(unsigned long *zones_size)
+{
+	free_area_init_node(0, &contig_page_data, zones_size,
+			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
+}
+#endif
+
+#ifdef CONFIG_PROC_FS
+
+#include <linux/seq_file.h>
+
+static void *frag_start(struct seq_file *m, loff_t *pos)
+{
+	pg_data_t *pgdat;
+	loff_t node = *pos;
+
+	for (pgdat = pgdat_list; pgdat && node; pgdat = pgdat->pgdat_next)
+		--node;
+
+	return pgdat;
+}
+
+static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	(*pos)++;
+	return pgdat->pgdat_next;
+}
+
+static void frag_stop(struct seq_file *m, void *arg)
+{
+}
+
+/* 
+ * This walks the free areas for each zone.
+ */
+static int frag_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+	struct zone *zone;
+	struct zone *node_zones = pgdat->node_zones;
+	unsigned long flags;
+	int order;
+
+	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
+		if (!zone->present_pages)
+			continue;
+
+		spin_lock_irqsave(&zone->lock, flags);
+		seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+		for (order = 0; order < MAX_ORDER; ++order)
+			seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
+		spin_unlock_irqrestore(&zone->lock, flags);
+		seq_putc(m, '\n');
+	}
+	return 0;
+}
+
+struct seq_operations fragmentation_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= frag_show,
+};
+
+static char *vmstat_text[] = {
+	"nr_dirty",
+	"nr_writeback",
+	"nr_unstable",
+	"nr_page_table_pages",
+	"nr_mapped",
+	"nr_slab",
+
+	"pgpgin",
+	"pgpgout",
+	"pswpin",
+	"pswpout",
+	"pgalloc_high",
+
+	"pgalloc_normal",
+	"pgalloc_dma",
+	"pgfree",
+	"pgactivate",
+	"pgdeactivate",
+
+	"pgfault",
+	"pgmajfault",
+	"pgrefill_high",
+	"pgrefill_normal",
+	"pgrefill_dma",
+
+	"pgsteal_high",
+	"pgsteal_normal",
+	"pgsteal_dma",
+	"pgscan_kswapd_high",
+	"pgscan_kswapd_normal",
+
+	"pgscan_kswapd_dma",
+	"pgscan_direct_high",
+	"pgscan_direct_normal",
+	"pgscan_direct_dma",
+	"pginodesteal",
+
+	"slabs_scanned",
+	"kswapd_steal",
+	"kswapd_inodesteal",
+	"pageoutrun",
+	"allocstall",
+
+	"pgrotated",
+};
+
+static void *vmstat_start(struct seq_file *m, loff_t *pos)
+{
+	struct page_state *ps;
+
+	if (*pos >= ARRAY_SIZE(vmstat_text))
+		return NULL;
+
+	ps = kmalloc(sizeof(*ps), GFP_KERNEL);
+	m->private = ps;
+	if (!ps)
+		return ERR_PTR(-ENOMEM);
+	get_full_page_state(ps);
+	ps->pgpgin /= 2;		/* sectors -> kbytes */
+	ps->pgpgout /= 2;
+	return (unsigned long *)ps + *pos;
+}
+
+static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos >= ARRAY_SIZE(vmstat_text))
+		return NULL;
+	return (unsigned long *)m->private + *pos;
+}
+
+static int vmstat_show(struct seq_file *m, void *arg)
+{
+	unsigned long *l = arg;
+	unsigned long off = l - (unsigned long *)m->private;
+
+	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
+	return 0;
+}
+
+static void vmstat_stop(struct seq_file *m, void *arg)
+{
+	kfree(m->private);
+	m->private = NULL;
+}
+
+struct seq_operations vmstat_op = {
+	.start	= vmstat_start,
+	.next	= vmstat_next,
+	.stop	= vmstat_stop,
+	.show	= vmstat_show,
+};
+
+#endif /* CONFIG_PROC_FS */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int page_alloc_cpu_notify(struct notifier_block *self,
+				 unsigned long action, void *hcpu)
+{
+	int cpu = (unsigned long)hcpu;
+	long *count;
+	unsigned long *src, *dest;
+
+	if (action == CPU_DEAD) {
+		int i;
+
+		/* Drain local pagecache count. */
+		count = &per_cpu(nr_pagecache_local, cpu);
+		atomic_add(*count, &nr_pagecache);
+		*count = 0;
+		local_irq_disable();
+		__drain_pages(cpu);
+
+		/* Add dead cpu's page_states to our own. */
+		dest = (unsigned long *)&__get_cpu_var(page_states);
+		src = (unsigned long *)&per_cpu(page_states, cpu);
+
+		for (i = 0; i < sizeof(struct page_state)/sizeof(unsigned long);
+				i++) {
+			dest[i] += src[i];
+			src[i] = 0;
+		}
+
+		local_irq_enable();
+	}
+	return NOTIFY_OK;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+void __init page_alloc_init(void)
+{
+	hotcpu_notifier(page_alloc_cpu_notify, 0);
+}
+
+/*
+ * 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;
+	int j, idx;
+
+	for_each_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;
+
+			for (idx = j-1; idx >= 0; idx--) {
+				struct zone *lower_zone;
+
+				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;
+			}
+		}
+	}
+}
+
+/*
+ * setup_per_zone_pages_min - called when min_free_kbytes changes.  Ensures 
+ *	that the pages_{min,low,high} values for each zone are set correctly 
+ *	with respect to min_free_kbytes.
+ */
+static void setup_per_zone_pages_min(void)
+{
+	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
+	unsigned long lowmem_pages = 0;
+	struct zone *zone;
+	unsigned long flags;
+
+	/* Calculate total number of !ZONE_HIGHMEM pages */
+	for_each_zone(zone) {
+		if (!is_highmem(zone))
+			lowmem_pages += zone->present_pages;
+	}
+
+	for_each_zone(zone) {
+		spin_lock_irqsave(&zone->lru_lock, flags);
+		if (is_highmem(zone)) {
+			/*
+			 * Often, highmem doesn't need to reserve any pages.
+			 * But the pages_min/low/high values are also used for
+			 * batching up page reclaim activity so we need a
+			 * decent value here.
+			 */
+			int min_pages;
+
+			min_pages = zone->present_pages / 1024;
+			if (min_pages < SWAP_CLUSTER_MAX)
+				min_pages = SWAP_CLUSTER_MAX;
+			if (min_pages > 128)
+				min_pages = 128;
+			zone->pages_min = min_pages;
+		} else {
+			/* if it's a lowmem zone, reserve a number of pages 
+			 * proportionate to the zone's size.
+			 */
+			zone->pages_min = (pages_min * zone->present_pages) / 
+			                   lowmem_pages;
+		}
+
+		/*
+		 * When interpreting these watermarks, just keep in mind that:
+		 * zone->pages_min == (zone->pages_min * 4) / 4;
+		 */
+		zone->pages_low   = (zone->pages_min * 5) / 4;
+		zone->pages_high  = (zone->pages_min * 6) / 4;
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+	}
+}
+
+/*
+ * Initialise min_free_kbytes.
+ *
+ * For small machines we want it small (128k min).  For large machines
+ * we want it large (64MB max).  But it is not linear, because network
+ * bandwidth does not increase linearly with machine size.  We use
+ *
+ * 	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
+ *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
+ *
+ * which yields
+ *
+ * 16MB:	512k
+ * 32MB:	724k
+ * 64MB:	1024k
+ * 128MB:	1448k
+ * 256MB:	2048k
+ * 512MB:	2896k
+ * 1024MB:	4096k
+ * 2048MB:	5792k
+ * 4096MB:	8192k
+ * 8192MB:	11584k
+ * 16384MB:	16384k
+ */
+static int __init init_per_zone_pages_min(void)
+{
+	unsigned long lowmem_kbytes;
+
+	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
+
+	min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
+	if (min_free_kbytes < 128)
+		min_free_kbytes = 128;
+	if (min_free_kbytes > 65536)
+		min_free_kbytes = 65536;
+	setup_per_zone_pages_min();
+	setup_per_zone_lowmem_reserve();
+	return 0;
+}
+module_init(init_per_zone_pages_min)
+
+/*
+ * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so 
+ *	that we can call two helper functions whenever min_free_kbytes
+ *	changes.
+ */
+int min_free_kbytes_sysctl_handler(ctl_table *table, int write, 
+	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec(table, write, file, buffer, length, ppos);
+	setup_per_zone_pages_min();
+	return 0;
+}
+
+/*
+ * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
+ *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
+ *	whenever sysctl_lowmem_reserve_ratio changes.
+ *
+ * The reserve ratio obviously has absolutely no relation with the
+ * pages_min watermarks. The lowmem reserve ratio can only make sense
+ * if in function of the boot time zone sizes.
+ */
+int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write,
+	struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec_minmax(table, write, file, buffer, length, ppos);
+	setup_per_zone_lowmem_reserve();
+	return 0;
+}
+
+__initdata 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 = (flags & HASH_HIGHMEM) ? nr_all_pages : 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);
+	}
+	/* rounded up to nearest power of 2 in size */
+	numentries = 1UL << (long_log2(numentries) + 1);
+
+	/* 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 = long_log2(numentries);
+
+	do {
+		size = bucketsize << log2qty;
+		if (flags & HASH_EARLY)
+			table = alloc_bootmem(size);
+		else if (hashdist)
+			table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
+		else {
+			unsigned long order;
+			for (order = 0; ((1UL << order) << PAGE_SHIFT) < size; order++)
+				;
+			table = (void*) __get_free_pages(GFP_ATOMIC, order);
+		}
+	} while (!table && size > PAGE_SIZE && --log2qty);
+
+	if (!table)
+		panic("Failed to allocate %s hash table\n", tablename);
+
+	printk("%s hash table entries: %d (order: %d, %lu bytes)\n",
+	       tablename,
+	       (1U << log2qty),
+	       long_log2(size) - PAGE_SHIFT,
+	       size);
+
+	if (_hash_shift)
+		*_hash_shift = log2qty;
+	if (_hash_mask)
+		*_hash_mask = (1 << log2qty) - 1;
+
+	return table;
+}