/*
   *  linux/mm/vmalloc.c
   *
   *  Copyright (C) 1993  Linus Torvalds
   *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
   *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002

   *  Numa awareness, Christoph Lameter, SGI, June 2005

   */

  #include <linux/vmalloc.h>

  #include <linux/mm.h>
  #include <linux/module.h>
  #include <linux/highmem.h>

  #include <linux/sched.h>

  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/interrupt.h>

  #include <linux/proc_fs.h>

  #include <linux/seq_file.h>

  #include <linux/debugobjects.h>

  #include <linux/kallsyms.h>

  #include <linux/list.h>
  #include <linux/rbtree.h>
  #include <linux/radix-tree.h>
  #include <linux/rcupdate.h>

  #include <linux/pfn.h>

  #include <linux/kmemleak.h>

  #include <linux/atomic.h>

  #include <asm/uaccess.h>
  #include <asm/tlbflush.h>

  #include <asm/shmparam.h>

  /*** Page table manipulation functions ***/

  static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
  {
  	pte_t *pte;
  
  	pte = pte_offset_kernel(pmd, addr);
  	do {
  		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
  		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
  	} while (pte++, addr += PAGE_SIZE, addr != end);
  }

  static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)

  {
  	pmd_t *pmd;
  	unsigned long next;
  
  	pmd = pmd_offset(pud, addr);
  	do {
  		next = pmd_addr_end(addr, end);
  		if (pmd_none_or_clear_bad(pmd))
  			continue;
  		vunmap_pte_range(pmd, addr, next);
  	} while (pmd++, addr = next, addr != end);
  }

  static void vunmap_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end)

  {
  	pud_t *pud;
  	unsigned long next;
  
  	pud = pud_offset(pgd, addr);
  	do {
  		next = pud_addr_end(addr, end);
  		if (pud_none_or_clear_bad(pud))
  			continue;
  		vunmap_pmd_range(pud, addr, next);
  	} while (pud++, addr = next, addr != end);
  }

  static void vunmap_page_range(unsigned long addr, unsigned long end)

  {
  	pgd_t *pgd;
  	unsigned long next;

  
  	BUG_ON(addr >= end);
  	pgd = pgd_offset_k(addr);

  	do {
  		next = pgd_addr_end(addr, end);
  		if (pgd_none_or_clear_bad(pgd))
  			continue;
  		vunmap_pud_range(pgd, addr, next);
  	} while (pgd++, addr = next, addr != end);

  }
  
  static int vmap_pte_range(pmd_t *pmd, unsigned long addr,

  		unsigned long end, pgprot_t prot, struct page **pages, int *nr)

  {
  	pte_t *pte;

  	/*
  	 * nr is a running index into the array which helps higher level
  	 * callers keep track of where we're up to.
  	 */

  	pte = pte_alloc_kernel(pmd, addr);

  	if (!pte)
  		return -ENOMEM;
  	do {

  		struct page *page = pages[*nr];
  
  		if (WARN_ON(!pte_none(*pte)))
  			return -EBUSY;
  		if (WARN_ON(!page))

  			return -ENOMEM;
  		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));

  		(*nr)++;

  	} while (pte++, addr += PAGE_SIZE, addr != end);
  	return 0;
  }

  static int vmap_pmd_range(pud_t *pud, unsigned long addr,
  		unsigned long end, pgprot_t prot, struct page **pages, int *nr)

  {
  	pmd_t *pmd;
  	unsigned long next;
  
  	pmd = pmd_alloc(&init_mm, pud, addr);
  	if (!pmd)
  		return -ENOMEM;
  	do {
  		next = pmd_addr_end(addr, end);

  		if (vmap_pte_range(pmd, addr, next, prot, pages, nr))

  			return -ENOMEM;
  	} while (pmd++, addr = next, addr != end);
  	return 0;
  }

  static int vmap_pud_range(pgd_t *pgd, unsigned long addr,
  		unsigned long end, pgprot_t prot, struct page **pages, int *nr)

  {
  	pud_t *pud;
  	unsigned long next;
  
  	pud = pud_alloc(&init_mm, pgd, addr);
  	if (!pud)
  		return -ENOMEM;
  	do {
  		next = pud_addr_end(addr, end);

  		if (vmap_pmd_range(pud, addr, next, prot, pages, nr))

  			return -ENOMEM;
  	} while (pud++, addr = next, addr != end);
  	return 0;
  }

  /*
   * Set up page tables in kva (addr, end). The ptes shall have prot "prot", and
   * will have pfns corresponding to the "pages" array.
   *
   * Ie. pte at addr+N*PAGE_SIZE shall point to pfn corresponding to pages[N]
   */

  static int vmap_page_range_noflush(unsigned long start, unsigned long end,
  				   pgprot_t prot, struct page **pages)

  {
  	pgd_t *pgd;
  	unsigned long next;

  	unsigned long addr = start;

  	int err = 0;
  	int nr = 0;

  
  	BUG_ON(addr >= end);
  	pgd = pgd_offset_k(addr);

  	do {
  		next = pgd_addr_end(addr, end);

  		err = vmap_pud_range(pgd, addr, next, prot, pages, &nr);

  		if (err)

  			return err;

  	} while (pgd++, addr = next, addr != end);

  	return nr;

  }

  static int vmap_page_range(unsigned long start, unsigned long end,
  			   pgprot_t prot, struct page **pages)
  {
  	int ret;
  
  	ret = vmap_page_range_noflush(start, end, prot, pages);
  	flush_cache_vmap(start, end);
  	return ret;
  }

  int is_vmalloc_or_module_addr(const void *x)

  {
  	/*

  	 * ARM, x86-64 and sparc64 put modules in a special place,

  	 * and fall back on vmalloc() if that fails. Others
  	 * just put it in the vmalloc space.
  	 */
  #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
  	unsigned long addr = (unsigned long)x;
  	if (addr >= MODULES_VADDR && addr < MODULES_END)
  		return 1;
  #endif
  	return is_vmalloc_addr(x);
  }

  /*

   * Walk a vmap address to the struct page it maps.

   */

  struct page *vmalloc_to_page(const void *vmalloc_addr)

  {
  	unsigned long addr = (unsigned long) vmalloc_addr;
  	struct page *page = NULL;
  	pgd_t *pgd = pgd_offset_k(addr);

  	/*
  	 * XXX we might need to change this if we add VIRTUAL_BUG_ON for
  	 * architectures that do not vmalloc module space
  	 */

  	VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));

  	if (!pgd_none(*pgd)) {

  		pud_t *pud = pud_offset(pgd, addr);

  		if (!pud_none(*pud)) {

  			pmd_t *pmd = pmd_offset(pud, addr);

  			if (!pmd_none(*pmd)) {

  				pte_t *ptep, pte;

  				ptep = pte_offset_map(pmd, addr);
  				pte = *ptep;
  				if (pte_present(pte))
  					page = pte_page(pte);
  				pte_unmap(ptep);
  			}
  		}
  	}
  	return page;
  }
  EXPORT_SYMBOL(vmalloc_to_page);
  
  /*
   * Map a vmalloc()-space virtual address to the physical page frame number.
   */

  unsigned long vmalloc_to_pfn(const void *vmalloc_addr)

  {
  	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
  }
  EXPORT_SYMBOL(vmalloc_to_pfn);

  
  /*** Global kva allocator ***/
  
  #define VM_LAZY_FREE	0x01
  #define VM_LAZY_FREEING	0x02
  #define VM_VM_AREA	0x04
  
  struct vmap_area {
  	unsigned long va_start;
  	unsigned long va_end;
  	unsigned long flags;
  	struct rb_node rb_node;		/* address sorted rbtree */
  	struct list_head list;		/* address sorted list */
  	struct list_head purge_list;	/* "lazy purge" list */

  	struct vm_struct *vm;

  	struct rcu_head rcu_head;
  };
  
  static DEFINE_SPINLOCK(vmap_area_lock);

  static LIST_HEAD(vmap_area_list);

  static struct rb_root vmap_area_root = RB_ROOT;
  
  /* The vmap cache globals are protected by vmap_area_lock */
  static struct rb_node *free_vmap_cache;
  static unsigned long cached_hole_size;
  static unsigned long cached_vstart;
  static unsigned long cached_align;

  static unsigned long vmap_area_pcpu_hole;

  
  static struct vmap_area *__find_vmap_area(unsigned long addr)

  {

  	struct rb_node *n = vmap_area_root.rb_node;
  
  	while (n) {
  		struct vmap_area *va;
  
  		va = rb_entry(n, struct vmap_area, rb_node);
  		if (addr < va->va_start)
  			n = n->rb_left;
  		else if (addr > va->va_start)
  			n = n->rb_right;
  		else
  			return va;
  	}
  
  	return NULL;
  }
  
  static void __insert_vmap_area(struct vmap_area *va)
  {
  	struct rb_node **p = &vmap_area_root.rb_node;
  	struct rb_node *parent = NULL;
  	struct rb_node *tmp;
  
  	while (*p) {

  		struct vmap_area *tmp_va;

  
  		parent = *p;

  		tmp_va = rb_entry(parent, struct vmap_area, rb_node);
  		if (va->va_start < tmp_va->va_end)

  			p = &(*p)->rb_left;

  		else if (va->va_end > tmp_va->va_start)

  			p = &(*p)->rb_right;
  		else
  			BUG();
  	}
  
  	rb_link_node(&va->rb_node, parent, p);
  	rb_insert_color(&va->rb_node, &vmap_area_root);
  
  	/* address-sort this list so it is usable like the vmlist */
  	tmp = rb_prev(&va->rb_node);
  	if (tmp) {
  		struct vmap_area *prev;
  		prev = rb_entry(tmp, struct vmap_area, rb_node);
  		list_add_rcu(&va->list, &prev->list);
  	} else
  		list_add_rcu(&va->list, &vmap_area_list);
  }
  
  static void purge_vmap_area_lazy(void);
  
  /*
   * Allocate a region of KVA of the specified size and alignment, within the
   * vstart and vend.
   */
  static struct vmap_area *alloc_vmap_area(unsigned long size,
  				unsigned long align,
  				unsigned long vstart, unsigned long vend,
  				int node, gfp_t gfp_mask)
  {
  	struct vmap_area *va;
  	struct rb_node *n;

  	unsigned long addr;

  	int purged = 0;

  	struct vmap_area *first;

  	BUG_ON(!size);

  	BUG_ON(size & ~PAGE_MASK);

  	BUG_ON(!is_power_of_2(align));

  	va = kmalloc_node(sizeof(struct vmap_area),
  			gfp_mask & GFP_RECLAIM_MASK, node);
  	if (unlikely(!va))
  		return ERR_PTR(-ENOMEM);
  
  retry:
  	spin_lock(&vmap_area_lock);

  	/*
  	 * Invalidate cache if we have more permissive parameters.
  	 * cached_hole_size notes the largest hole noticed _below_
  	 * the vmap_area cached in free_vmap_cache: if size fits
  	 * into that hole, we want to scan from vstart to reuse
  	 * the hole instead of allocating above free_vmap_cache.
  	 * Note that __free_vmap_area may update free_vmap_cache
  	 * without updating cached_hole_size or cached_align.
  	 */
  	if (!free_vmap_cache ||
  			size < cached_hole_size ||
  			vstart < cached_vstart ||
  			align < cached_align) {
  nocache:
  		cached_hole_size = 0;
  		free_vmap_cache = NULL;
  	}
  	/* record if we encounter less permissive parameters */
  	cached_vstart = vstart;
  	cached_align = align;
  
  	/* find starting point for our search */
  	if (free_vmap_cache) {
  		first = rb_entry(free_vmap_cache, struct vmap_area, rb_node);

  		addr = ALIGN(first->va_end, align);

  		if (addr < vstart)
  			goto nocache;
  		if (addr + size - 1 < addr)
  			goto overflow;
  
  	} else {
  		addr = ALIGN(vstart, align);
  		if (addr + size - 1 < addr)
  			goto overflow;
  
  		n = vmap_area_root.rb_node;
  		first = NULL;
  
  		while (n) {

  			struct vmap_area *tmp;
  			tmp = rb_entry(n, struct vmap_area, rb_node);
  			if (tmp->va_end >= addr) {

  				first = tmp;

  				if (tmp->va_start <= addr)
  					break;
  				n = n->rb_left;
  			} else

  				n = n->rb_right;

  		}

  
  		if (!first)
  			goto found;

  	}

  
  	/* from the starting point, walk areas until a suitable hole is found */

  	while (addr + size > first->va_start && addr + size <= vend) {

  		if (addr + cached_hole_size < first->va_start)
  			cached_hole_size = first->va_start - addr;

  		addr = ALIGN(first->va_end, align);

  		if (addr + size - 1 < addr)
  			goto overflow;

  		if (list_is_last(&first->list, &vmap_area_list))

  			goto found;

  
  		first = list_entry(first->list.next,
  				struct vmap_area, list);

  	}

  found:
  	if (addr + size > vend)
  		goto overflow;

  
  	va->va_start = addr;
  	va->va_end = addr + size;
  	va->flags = 0;
  	__insert_vmap_area(va);

  	free_vmap_cache = &va->rb_node;

  	spin_unlock(&vmap_area_lock);

  	BUG_ON(va->va_start & (align-1));
  	BUG_ON(va->va_start < vstart);
  	BUG_ON(va->va_end > vend);

  	return va;

  
  overflow:
  	spin_unlock(&vmap_area_lock);
  	if (!purged) {
  		purge_vmap_area_lazy();
  		purged = 1;
  		goto retry;
  	}
  	if (printk_ratelimit())
  		printk(KERN_WARNING
  			"vmap allocation for size %lu failed: "
  			"use vmalloc=<size> to increase size.
  ", size);
  	kfree(va);
  	return ERR_PTR(-EBUSY);

  }

  static void __free_vmap_area(struct vmap_area *va)
  {
  	BUG_ON(RB_EMPTY_NODE(&va->rb_node));

  
  	if (free_vmap_cache) {
  		if (va->va_end < cached_vstart) {
  			free_vmap_cache = NULL;
  		} else {
  			struct vmap_area *cache;
  			cache = rb_entry(free_vmap_cache, struct vmap_area, rb_node);
  			if (va->va_start <= cache->va_start) {
  				free_vmap_cache = rb_prev(&va->rb_node);
  				/*
  				 * We don't try to update cached_hole_size or
  				 * cached_align, but it won't go very wrong.
  				 */
  			}
  		}
  	}

  	rb_erase(&va->rb_node, &vmap_area_root);
  	RB_CLEAR_NODE(&va->rb_node);
  	list_del_rcu(&va->list);

  	/*
  	 * Track the highest possible candidate for pcpu area
  	 * allocation.  Areas outside of vmalloc area can be returned
  	 * here too, consider only end addresses which fall inside
  	 * vmalloc area proper.
  	 */
  	if (va->va_end > VMALLOC_START && va->va_end <= VMALLOC_END)
  		vmap_area_pcpu_hole = max(vmap_area_pcpu_hole, va->va_end);

  	kfree_rcu(va, rcu_head);

  }
  
  /*
   * Free a region of KVA allocated by alloc_vmap_area
   */
  static void free_vmap_area(struct vmap_area *va)
  {
  	spin_lock(&vmap_area_lock);
  	__free_vmap_area(va);
  	spin_unlock(&vmap_area_lock);
  }
  
  /*
   * Clear the pagetable entries of a given vmap_area
   */
  static void unmap_vmap_area(struct vmap_area *va)
  {
  	vunmap_page_range(va->va_start, va->va_end);
  }

  static void vmap_debug_free_range(unsigned long start, unsigned long end)
  {
  	/*
  	 * Unmap page tables and force a TLB flush immediately if
  	 * CONFIG_DEBUG_PAGEALLOC is set. This catches use after free
  	 * bugs similarly to those in linear kernel virtual address
  	 * space after a page has been freed.
  	 *
  	 * All the lazy freeing logic is still retained, in order to
  	 * minimise intrusiveness of this debugging feature.
  	 *
  	 * This is going to be *slow* (linear kernel virtual address
  	 * debugging doesn't do a broadcast TLB flush so it is a lot
  	 * faster).
  	 */
  #ifdef CONFIG_DEBUG_PAGEALLOC
  	vunmap_page_range(start, end);
  	flush_tlb_kernel_range(start, end);
  #endif
  }

  /*
   * lazy_max_pages is the maximum amount of virtual address space we gather up
   * before attempting to purge with a TLB flush.
   *
   * There is a tradeoff here: a larger number will cover more kernel page tables
   * and take slightly longer to purge, but it will linearly reduce the number of
   * global TLB flushes that must be performed. It would seem natural to scale
   * this number up linearly with the number of CPUs (because vmapping activity
   * could also scale linearly with the number of CPUs), however it is likely
   * that in practice, workloads might be constrained in other ways that mean
   * vmap activity will not scale linearly with CPUs. Also, I want to be
   * conservative and not introduce a big latency on huge systems, so go with
   * a less aggressive log scale. It will still be an improvement over the old
   * code, and it will be simple to change the scale factor if we find that it
   * becomes a problem on bigger systems.
   */
  static unsigned long lazy_max_pages(void)
  {
  	unsigned int log;
  
  	log = fls(num_online_cpus());
  
  	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
  }
  
  static atomic_t vmap_lazy_nr = ATOMIC_INIT(0);

  /* for per-CPU blocks */
  static void purge_fragmented_blocks_allcpus(void);

  /*

   * called before a call to iounmap() if the caller wants vm_area_struct's
   * immediately freed.
   */
  void set_iounmap_nonlazy(void)
  {
  	atomic_set(&vmap_lazy_nr, lazy_max_pages()+1);
  }
  
  /*

   * Purges all lazily-freed vmap areas.
   *
   * If sync is 0 then don't purge if there is already a purge in progress.
   * If force_flush is 1, then flush kernel TLBs between *start and *end even
   * if we found no lazy vmap areas to unmap (callers can use this to optimise
   * their own TLB flushing).
   * Returns with *start = min(*start, lowest purged address)
   *              *end = max(*end, highest purged address)
   */
  static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
  					int sync, int force_flush)
  {

  	static DEFINE_SPINLOCK(purge_lock);

  	LIST_HEAD(valist);
  	struct vmap_area *va;

  	struct vmap_area *n_va;

  	int nr = 0;
  
  	/*
  	 * If sync is 0 but force_flush is 1, we'll go sync anyway but callers
  	 * should not expect such behaviour. This just simplifies locking for
  	 * the case that isn't actually used at the moment anyway.
  	 */
  	if (!sync && !force_flush) {

  		if (!spin_trylock(&purge_lock))

  			return;
  	} else

  		spin_lock(&purge_lock);

  	if (sync)
  		purge_fragmented_blocks_allcpus();

  	rcu_read_lock();
  	list_for_each_entry_rcu(va, &vmap_area_list, list) {
  		if (va->flags & VM_LAZY_FREE) {
  			if (va->va_start < *start)
  				*start = va->va_start;
  			if (va->va_end > *end)
  				*end = va->va_end;
  			nr += (va->va_end - va->va_start) >> PAGE_SHIFT;

  			list_add_tail(&va->purge_list, &valist);
  			va->flags |= VM_LAZY_FREEING;
  			va->flags &= ~VM_LAZY_FREE;
  		}
  	}
  	rcu_read_unlock();

  	if (nr)

  		atomic_sub(nr, &vmap_lazy_nr);

  
  	if (nr || force_flush)
  		flush_tlb_kernel_range(*start, *end);
  
  	if (nr) {
  		spin_lock(&vmap_area_lock);

  		list_for_each_entry_safe(va, n_va, &valist, purge_list)

  			__free_vmap_area(va);
  		spin_unlock(&vmap_area_lock);
  	}

  	spin_unlock(&purge_lock);

  }
  
  /*

   * Kick off a purge of the outstanding lazy areas. Don't bother if somebody
   * is already purging.
   */
  static void try_purge_vmap_area_lazy(void)
  {
  	unsigned long start = ULONG_MAX, end = 0;
  
  	__purge_vmap_area_lazy(&start, &end, 0, 0);
  }
  
  /*

   * Kick off a purge of the outstanding lazy areas.
   */
  static void purge_vmap_area_lazy(void)
  {
  	unsigned long start = ULONG_MAX, end = 0;

  	__purge_vmap_area_lazy(&start, &end, 1, 0);

  }
  
  /*

   * Free a vmap area, caller ensuring that the area has been unmapped
   * and flush_cache_vunmap had been called for the correct range
   * previously.

   */

  static void free_vmap_area_noflush(struct vmap_area *va)

  {
  	va->flags |= VM_LAZY_FREE;
  	atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr);
  	if (unlikely(atomic_read(&vmap_lazy_nr) > lazy_max_pages()))

  		try_purge_vmap_area_lazy();

  }

  /*

   * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been
   * called for the correct range previously.
   */
  static void free_unmap_vmap_area_noflush(struct vmap_area *va)
  {
  	unmap_vmap_area(va);
  	free_vmap_area_noflush(va);
  }
  
  /*

   * Free and unmap a vmap area
   */
  static void free_unmap_vmap_area(struct vmap_area *va)
  {
  	flush_cache_vunmap(va->va_start, va->va_end);
  	free_unmap_vmap_area_noflush(va);
  }

  static struct vmap_area *find_vmap_area(unsigned long addr)
  {
  	struct vmap_area *va;
  
  	spin_lock(&vmap_area_lock);
  	va = __find_vmap_area(addr);
  	spin_unlock(&vmap_area_lock);
  
  	return va;
  }
  
  static void free_unmap_vmap_area_addr(unsigned long addr)
  {
  	struct vmap_area *va;
  
  	va = find_vmap_area(addr);
  	BUG_ON(!va);
  	free_unmap_vmap_area(va);
  }
  
  
  /*** Per cpu kva allocator ***/
  
  /*
   * vmap space is limited especially on 32 bit architectures. Ensure there is
   * room for at least 16 percpu vmap blocks per CPU.
   */
  /*
   * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
   * to #define VMALLOC_SPACE		(VMALLOC_END-VMALLOC_START). Guess
   * instead (we just need a rough idea)
   */
  #if BITS_PER_LONG == 32
  #define VMALLOC_SPACE		(128UL*1024*1024)
  #else
  #define VMALLOC_SPACE		(128UL*1024*1024*1024)
  #endif
  
  #define VMALLOC_PAGES		(VMALLOC_SPACE / PAGE_SIZE)
  #define VMAP_MAX_ALLOC		BITS_PER_LONG	/* 256K with 4K pages */
  #define VMAP_BBMAP_BITS_MAX	1024	/* 4MB with 4K pages */
  #define VMAP_BBMAP_BITS_MIN	(VMAP_MAX_ALLOC*2)
  #define VMAP_MIN(x, y)		((x) < (y) ? (x) : (y)) /* can't use min() */
  #define VMAP_MAX(x, y)		((x) > (y) ? (x) : (y)) /* can't use max() */

  #define VMAP_BBMAP_BITS		\
  		VMAP_MIN(VMAP_BBMAP_BITS_MAX,	\
  		VMAP_MAX(VMAP_BBMAP_BITS_MIN,	\
  			VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))

  
  #define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)

  static bool vmap_initialized __read_mostly = false;

  struct vmap_block_queue {
  	spinlock_t lock;
  	struct list_head free;

  };
  
  struct vmap_block {
  	spinlock_t lock;
  	struct vmap_area *va;
  	struct vmap_block_queue *vbq;
  	unsigned long free, dirty;
  	DECLARE_BITMAP(alloc_map, VMAP_BBMAP_BITS);
  	DECLARE_BITMAP(dirty_map, VMAP_BBMAP_BITS);

  	struct list_head free_list;
  	struct rcu_head rcu_head;

  	struct list_head purge;

  };
  
  /* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
  static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
  
  /*
   * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
   * in the free path. Could get rid of this if we change the API to return a
   * "cookie" from alloc, to be passed to free. But no big deal yet.
   */
  static DEFINE_SPINLOCK(vmap_block_tree_lock);
  static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
  
  /*
   * We should probably have a fallback mechanism to allocate virtual memory
   * out of partially filled vmap blocks. However vmap block sizing should be
   * fairly reasonable according to the vmalloc size, so it shouldn't be a
   * big problem.
   */
  
  static unsigned long addr_to_vb_idx(unsigned long addr)
  {
  	addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
  	addr /= VMAP_BLOCK_SIZE;
  	return addr;
  }
  
  static struct vmap_block *new_vmap_block(gfp_t gfp_mask)
  {
  	struct vmap_block_queue *vbq;
  	struct vmap_block *vb;
  	struct vmap_area *va;
  	unsigned long vb_idx;
  	int node, err;
  
  	node = numa_node_id();
  
  	vb = kmalloc_node(sizeof(struct vmap_block),
  			gfp_mask & GFP_RECLAIM_MASK, node);
  	if (unlikely(!vb))
  		return ERR_PTR(-ENOMEM);
  
  	va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
  					VMALLOC_START, VMALLOC_END,
  					node, gfp_mask);

  	if (IS_ERR(va)) {

  		kfree(vb);

  		return ERR_CAST(va);

  	}
  
  	err = radix_tree_preload(gfp_mask);
  	if (unlikely(err)) {
  		kfree(vb);
  		free_vmap_area(va);
  		return ERR_PTR(err);
  	}
  
  	spin_lock_init(&vb->lock);
  	vb->va = va;
  	vb->free = VMAP_BBMAP_BITS;
  	vb->dirty = 0;
  	bitmap_zero(vb->alloc_map, VMAP_BBMAP_BITS);
  	bitmap_zero(vb->dirty_map, VMAP_BBMAP_BITS);
  	INIT_LIST_HEAD(&vb->free_list);

  
  	vb_idx = addr_to_vb_idx(va->va_start);
  	spin_lock(&vmap_block_tree_lock);
  	err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
  	spin_unlock(&vmap_block_tree_lock);
  	BUG_ON(err);
  	radix_tree_preload_end();
  
  	vbq = &get_cpu_var(vmap_block_queue);
  	vb->vbq = vbq;
  	spin_lock(&vbq->lock);

  	list_add_rcu(&vb->free_list, &vbq->free);

  	spin_unlock(&vbq->lock);

  	put_cpu_var(vmap_block_queue);

  
  	return vb;
  }

  static void free_vmap_block(struct vmap_block *vb)
  {
  	struct vmap_block *tmp;
  	unsigned long vb_idx;

  	vb_idx = addr_to_vb_idx(vb->va->va_start);
  	spin_lock(&vmap_block_tree_lock);
  	tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
  	spin_unlock(&vmap_block_tree_lock);
  	BUG_ON(tmp != vb);

  	free_vmap_area_noflush(vb->va);

  	kfree_rcu(vb, rcu_head);

  }

  static void purge_fragmented_blocks(int cpu)
  {
  	LIST_HEAD(purge);
  	struct vmap_block *vb;
  	struct vmap_block *n_vb;
  	struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
  
  		if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
  			continue;
  
  		spin_lock(&vb->lock);
  		if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
  			vb->free = 0; /* prevent further allocs after releasing lock */
  			vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
  			bitmap_fill(vb->alloc_map, VMAP_BBMAP_BITS);
  			bitmap_fill(vb->dirty_map, VMAP_BBMAP_BITS);
  			spin_lock(&vbq->lock);
  			list_del_rcu(&vb->free_list);
  			spin_unlock(&vbq->lock);
  			spin_unlock(&vb->lock);
  			list_add_tail(&vb->purge, &purge);
  		} else
  			spin_unlock(&vb->lock);
  	}
  	rcu_read_unlock();
  
  	list_for_each_entry_safe(vb, n_vb, &purge, purge) {
  		list_del(&vb->purge);
  		free_vmap_block(vb);
  	}
  }
  
  static void purge_fragmented_blocks_thiscpu(void)
  {
  	purge_fragmented_blocks(smp_processor_id());
  }
  
  static void purge_fragmented_blocks_allcpus(void)
  {
  	int cpu;
  
  	for_each_possible_cpu(cpu)
  		purge_fragmented_blocks(cpu);
  }

  static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
  {
  	struct vmap_block_queue *vbq;
  	struct vmap_block *vb;
  	unsigned long addr = 0;
  	unsigned int order;

  	int purge = 0;

  
  	BUG_ON(size & ~PAGE_MASK);
  	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);

  	if (WARN_ON(size == 0)) {
  		/*
  		 * Allocating 0 bytes isn't what caller wants since
  		 * get_order(0) returns funny result. Just warn and terminate
  		 * early.
  		 */
  		return NULL;
  	}

  	order = get_order(size);
  
  again:
  	rcu_read_lock();
  	vbq = &get_cpu_var(vmap_block_queue);
  	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
  		int i;
  
  		spin_lock(&vb->lock);

  		if (vb->free < 1UL << order)
  			goto next;

  		i = bitmap_find_free_region(vb->alloc_map,
  						VMAP_BBMAP_BITS, order);

  		if (i < 0) {
  			if (vb->free + vb->dirty == VMAP_BBMAP_BITS) {
  				/* fragmented and no outstanding allocations */
  				BUG_ON(vb->dirty != VMAP_BBMAP_BITS);
  				purge = 1;

  			}

  			goto next;

  		}

  		addr = vb->va->va_start + (i << PAGE_SHIFT);
  		BUG_ON(addr_to_vb_idx(addr) !=
  				addr_to_vb_idx(vb->va->va_start));
  		vb->free -= 1UL << order;
  		if (vb->free == 0) {
  			spin_lock(&vbq->lock);
  			list_del_rcu(&vb->free_list);
  			spin_unlock(&vbq->lock);
  		}
  		spin_unlock(&vb->lock);
  		break;
  next:

  		spin_unlock(&vb->lock);
  	}

  
  	if (purge)
  		purge_fragmented_blocks_thiscpu();

  	put_cpu_var(vmap_block_queue);

  	rcu_read_unlock();
  
  	if (!addr) {
  		vb = new_vmap_block(gfp_mask);
  		if (IS_ERR(vb))
  			return vb;
  		goto again;
  	}
  
  	return (void *)addr;
  }
  
  static void vb_free(const void *addr, unsigned long size)
  {
  	unsigned long offset;
  	unsigned long vb_idx;
  	unsigned int order;
  	struct vmap_block *vb;
  
  	BUG_ON(size & ~PAGE_MASK);
  	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);

  
  	flush_cache_vunmap((unsigned long)addr, (unsigned long)addr + size);

  	order = get_order(size);
  
  	offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1);
  
  	vb_idx = addr_to_vb_idx((unsigned long)addr);
  	rcu_read_lock();
  	vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
  	rcu_read_unlock();
  	BUG_ON(!vb);

  	vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);

  	spin_lock(&vb->lock);

  	BUG_ON(bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order));

  	vb->dirty += 1UL << order;
  	if (vb->dirty == VMAP_BBMAP_BITS) {

  		BUG_ON(vb->free);

  		spin_unlock(&vb->lock);
  		free_vmap_block(vb);
  	} else
  		spin_unlock(&vb->lock);
  }
  
  /**
   * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
   *
   * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
   * to amortize TLB flushing overheads. What this means is that any page you
   * have now, may, in a former life, have been mapped into kernel virtual
   * address by the vmap layer and so there might be some CPUs with TLB entries
   * still referencing that page (additional to the regular 1:1 kernel mapping).
   *
   * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
   * be sure that none of the pages we have control over will have any aliases
   * from the vmap layer.
   */
  void vm_unmap_aliases(void)
  {
  	unsigned long start = ULONG_MAX, end = 0;
  	int cpu;
  	int flush = 0;

  	if (unlikely(!vmap_initialized))
  		return;

  	for_each_possible_cpu(cpu) {
  		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
  		struct vmap_block *vb;
  
  		rcu_read_lock();
  		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
  			int i;
  
  			spin_lock(&vb->lock);
  			i = find_first_bit(vb->dirty_map, VMAP_BBMAP_BITS);
  			while (i < VMAP_BBMAP_BITS) {
  				unsigned long s, e;
  				int j;
  				j = find_next_zero_bit(vb->dirty_map,
  					VMAP_BBMAP_BITS, i);
  
  				s = vb->va->va_start + (i << PAGE_SHIFT);
  				e = vb->va->va_start + (j << PAGE_SHIFT);

  				flush = 1;
  
  				if (s < start)
  					start = s;
  				if (e > end)
  					end = e;
  
  				i = j;
  				i = find_next_bit(vb->dirty_map,
  							VMAP_BBMAP_BITS, i);
  			}
  			spin_unlock(&vb->lock);
  		}
  		rcu_read_unlock();
  	}
  
  	__purge_vmap_area_lazy(&start, &end, 1, flush);
  }
  EXPORT_SYMBOL_GPL(vm_unmap_aliases);
  
  /**
   * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
   * @mem: the pointer returned by vm_map_ram
   * @count: the count passed to that vm_map_ram call (cannot unmap partial)
   */
  void vm_unmap_ram(const void *mem, unsigned int count)
  {
  	unsigned long size = count << PAGE_SHIFT;
  	unsigned long addr = (unsigned long)mem;
  
  	BUG_ON(!addr);
  	BUG_ON(addr < VMALLOC_START);
  	BUG_ON(addr > VMALLOC_END);
  	BUG_ON(addr & (PAGE_SIZE-1));
  
  	debug_check_no_locks_freed(mem, size);

  	vmap_debug_free_range(addr, addr+size);

  
  	if (likely(count <= VMAP_MAX_ALLOC))
  		vb_free(mem, size);
  	else
  		free_unmap_vmap_area_addr(addr);
  }
  EXPORT_SYMBOL(vm_unmap_ram);
  
  /**
   * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
   * @pages: an array of pointers to the pages to be mapped
   * @count: number of pages
   * @node: prefer to allocate data structures on this node
   * @prot: memory protection to use. PAGE_KERNEL for regular RAM

   *
   * Returns: a pointer to the address that has been mapped, or %NULL on failure

   */
  void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
  {
  	unsigned long size = count << PAGE_SHIFT;
  	unsigned long addr;
  	void *mem;
  
  	if (likely(count <= VMAP_MAX_ALLOC)) {
  		mem = vb_alloc(size, GFP_KERNEL);
  		if (IS_ERR(mem))
  			return NULL;
  		addr = (unsigned long)mem;
  	} else {
  		struct vmap_area *va;
  		va = alloc_vmap_area(size, PAGE_SIZE,
  				VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
  		if (IS_ERR(va))
  			return NULL;
  
  		addr = va->va_start;
  		mem = (void *)addr;
  	}
  	if (vmap_page_range(addr, addr + size, prot, pages) < 0) {
  		vm_unmap_ram(mem, count);
  		return NULL;
  	}
  	return mem;
  }
  EXPORT_SYMBOL(vm_map_ram);

  /**

   * vm_area_add_early - add vmap area early during boot
   * @vm: vm_struct to add
   *
   * This function is used to add fixed kernel vm area to vmlist before
   * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
   * should contain proper values and the other fields should be zero.
   *
   * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
   */
  void __init vm_area_add_early(struct vm_struct *vm)
  {
  	struct vm_struct *tmp, **p;
  
  	BUG_ON(vmap_initialized);
  	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
  		if (tmp->addr >= vm->addr) {
  			BUG_ON(tmp->addr < vm->addr + vm->size);
  			break;
  		} else
  			BUG_ON(tmp->addr + tmp->size > vm->addr);
  	}
  	vm->next = *p;
  	*p = vm;
  }
  
  /**

   * vm_area_register_early - register vmap area early during boot
   * @vm: vm_struct to register

   * @align: requested alignment

   *
   * This function is used to register kernel vm area before
   * vmalloc_init() is called.  @vm->size and @vm->flags should contain
   * proper values on entry and other fields should be zero.  On return,
   * vm->addr contains the allocated address.
   *
   * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
   */

  void __init vm_area_register_early(struct vm_struct *vm, size_t align)

  {
  	static size_t vm_init_off __initdata;

  	unsigned long addr;
  
  	addr = ALIGN(VMALLOC_START + vm_init_off, align);
  	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;

  	vm->addr = (void *)addr;

  	vm_area_add_early(vm);

  }

  void __init vmalloc_init(void)
  {

  	struct vmap_area *va;
  	struct vm_struct *tmp;

  	int i;
  
  	for_each_possible_cpu(i) {
  		struct vmap_block_queue *vbq;
  
  		vbq = &per_cpu(vmap_block_queue, i);
  		spin_lock_init(&vbq->lock);
  		INIT_LIST_HEAD(&vbq->free);

  	}

  	/* Import existing vmlist entries. */
  	for (tmp = vmlist; tmp; tmp = tmp->next) {

  		va = kzalloc(sizeof(struct vmap_area), GFP_NOWAIT);

  		va->flags = VM_VM_AREA;

  		va->va_start = (unsigned long)tmp->addr;
  		va->va_end = va->va_start + tmp->size;

  		va->vm = tmp;

  		__insert_vmap_area(va);
  	}

  
  	vmap_area_pcpu_hole = VMALLOC_END;

  	vmap_initialized = true;

  }

  /**
   * map_kernel_range_noflush - map kernel VM area with the specified pages
   * @addr: start of the VM area to map
   * @size: size of the VM area to map
   * @prot: page protection flags to use
   * @pages: pages to map
   *
   * Map PFN_UP(@size) pages at @addr.  The VM area @addr and @size
   * specify should have been allocated using get_vm_area() and its
   * friends.
   *
   * NOTE:
   * This function does NOT do any cache flushing.  The caller is
   * responsible for calling flush_cache_vmap() on to-be-mapped areas
   * before calling this function.
   *
   * RETURNS:
   * The number of pages mapped on success, -errno on failure.
   */
  int map_kernel_range_noflush(unsigned long addr, unsigned long size,
  			     pgprot_t prot, struct page **pages)
  {
  	return vmap_page_range_noflush(addr, addr + size, prot, pages);
  }
  
  /**
   * unmap_kernel_range_noflush - unmap kernel VM area
   * @addr: start of the VM area to unmap
   * @size: size of the VM area to unmap
   *
   * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size
   * specify should have been allocated using get_vm_area() and its
   * friends.
   *
   * NOTE:
   * This function does NOT do any cache flushing.  The caller is
   * responsible for calling flush_cache_vunmap() on to-be-mapped areas
   * before calling this function and flush_tlb_kernel_range() after.
   */
  void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
  {
  	vunmap_page_range(addr, addr + size);
  }

  EXPORT_SYMBOL_GPL(unmap_kernel_range_noflush);

  
  /**
   * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
   * @addr: start of the VM area to unmap
   * @size: size of the VM area to unmap
   *
   * Similar to unmap_kernel_range_noflush() but flushes vcache before
   * the unmapping and tlb after.
   */

  void unmap_kernel_range(unsigned long addr, unsigned long size)
  {
  	unsigned long end = addr + size;

  
  	flush_cache_vunmap(addr, end);

  	vunmap_page_range(addr, end);
  	flush_tlb_kernel_range(addr, end);
  }
  
  int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
  {
  	unsigned long addr = (unsigned long)area->addr;
  	unsigned long end = addr + area->size - PAGE_SIZE;
  	int err;
  
  	err = vmap_page_range(addr, end, prot, *pages);
  	if (err > 0) {
  		*pages += err;
  		err = 0;
  	}
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(map_vm_area);
  
  /*** Old vmalloc interfaces ***/
  DEFINE_RWLOCK(vmlist_lock);
  struct vm_struct *vmlist;

  static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,

  			      unsigned long flags, const void *caller)

  {

  	vm->flags = flags;
  	vm->addr = (void *)va->va_start;
  	vm->size = va->va_end - va->va_start;
  	vm->caller = caller;

  	va->vm = vm;

  	va->flags |= VM_VM_AREA;

  }

  static void insert_vmalloc_vmlist(struct vm_struct *vm)
  {
  	struct vm_struct *tmp, **p;
  
  	vm->flags &= ~VM_UNLIST;

  	write_lock(&vmlist_lock);
  	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
  		if (tmp->addr >= vm->addr)
  			break;
  	}
  	vm->next = *p;
  	*p = vm;
  	write_unlock(&vmlist_lock);
  }

  static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,

  			      unsigned long flags, const void *caller)

  {
  	setup_vmalloc_vm(vm, va, flags, caller);
  	insert_vmalloc_vmlist(vm);
  }

  static struct vm_struct *__get_vm_area_node(unsigned long size,

  		unsigned long align, unsigned long flags, unsigned long start,

  		unsigned long end, int node, gfp_t gfp_mask, const void *caller)

  {

  	struct vmap_area *va;

  	struct vm_struct *area;

  	BUG_ON(in_interrupt());

  	if (flags & VM_IOREMAP) {
  		int bit = fls(size);
  
  		if (bit > IOREMAP_MAX_ORDER)
  			bit = IOREMAP_MAX_ORDER;
  		else if (bit < PAGE_SHIFT)
  			bit = PAGE_SHIFT;
  
  		align = 1ul << bit;
  	}

  	size = PAGE_ALIGN(size);

  	if (unlikely(!size))
  		return NULL;

  	area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);

  	if (unlikely(!area))
  		return NULL;

  	/*
  	 * We always allocate a guard page.
  	 */
  	size += PAGE_SIZE;

  	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
  	if (IS_ERR(va)) {
  		kfree(area);
  		return NULL;

  	}

  	/*
  	 * When this function is called from __vmalloc_node_range,
  	 * we do not add vm_struct to vmlist here to avoid
  	 * accessing uninitialized members of vm_struct such as
  	 * pages and nr_pages fields. They will be set later.
  	 * To distinguish it from others, we use a VM_UNLIST flag.
  	 */
  	if (flags & VM_UNLIST)
  		setup_vmalloc_vm(area, va, flags, caller);
  	else
  		insert_vmalloc_vm(area, va, flags, caller);

  	return area;

  }

  struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
  				unsigned long start, unsigned long end)
  {

  	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
  				  GFP_KERNEL, __builtin_return_address(0));

  }

  EXPORT_SYMBOL_GPL(__get_vm_area);

  struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
  				       unsigned long start, unsigned long end,

  				       const void *caller)

  {

  	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
  				  GFP_KERNEL, caller);

  }

  /**

   *	get_vm_area  -  reserve a contiguous kernel virtual area

   *	@size:		size of the area
   *	@flags:		%VM_IOREMAP for I/O mappings or VM_ALLOC
   *
   *	Search an area of @size in the kernel virtual mapping area,
   *	and reserved it for out purposes.  Returns the area descriptor
   *	on success or %NULL on failure.
   */
  struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
  {

  	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,

  				  NUMA_NO_NODE, GFP_KERNEL,
  				  __builtin_return_address(0));

  }
  
  struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,

  				const void *caller)

  {

  	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,

  				  NUMA_NO_NODE, GFP_KERNEL, caller);

  }

  /**
   *	find_vm_area  -  find a continuous kernel virtual area
   *	@addr:		base address
   *
   *	Search for the kernel VM area starting at @addr, and return it.
   *	It is up to the caller to do all required locking to keep the returned
   *	pointer valid.
   */
  struct vm_struct *find_vm_area(const void *addr)

  {

  	struct vmap_area *va;

  	va = find_vmap_area((unsigned long)addr);
  	if (va && va->flags & VM_VM_AREA)

  		return va->vm;

  	return NULL;

  }

  /**

   *	remove_vm_area  -  find and remove a continuous kernel virtual area

   *	@addr:		base address
   *
   *	Search for the kernel VM area starting at @addr, and remove it.
   *	This function returns the found VM area, but using it is NOT safe
   *	on SMP machines, except for its size or flags.
   */

  struct vm_struct *remove_vm_area(const void *addr)

  {

  	struct vmap_area *va;
  
  	va = find_vmap_area((unsigned long)addr);
  	if (va && va->flags & VM_VM_AREA) {

  		struct vm_struct *vm = va->vm;

  
  		if (!(vm->flags & VM_UNLIST)) {
  			struct vm_struct *tmp, **p;
  			/*
  			 * remove from list and disallow access to
  			 * this vm_struct before unmap. (address range
  			 * confliction is maintained by vmap.)
  			 */
  			write_lock(&vmlist_lock);
  			for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next)
  				;
  			*p = tmp->next;
  			write_unlock(&vmlist_lock);
  		}

  		vmap_debug_free_range(va->va_start, va->va_end);
  		free_unmap_vmap_area(va);
  		vm->size -= PAGE_SIZE;

  		return vm;
  	}
  	return NULL;

  }

  static void __vunmap(const void *addr, int deallocate_pages)

  {
  	struct vm_struct *area;
  
  	if (!addr)
  		return;
  
  	if ((PAGE_SIZE-1) & (unsigned long)addr) {

  		WARN(1, KERN_ERR "Trying to vfree() bad address (%p)
  ", addr);

  		return;
  	}
  
  	area = remove_vm_area(addr);
  	if (unlikely(!area)) {

  		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)
  ",

  				addr);

  		return;
  	}

  	debug_check_no_locks_freed(addr, area->size);

  	debug_check_no_obj_freed(addr, area->size);

  	if (deallocate_pages) {
  		int i;
  
  		for (i = 0; i < area->nr_pages; i++) {

  			struct page *page = area->pages[i];
  
  			BUG_ON(!page);
  			__free_page(page);

  		}

  		if (area->flags & VM_VPAGES)

  			vfree(area->pages);
  		else
  			kfree(area->pages);
  	}
  
  	kfree(area);
  	return;
  }
  
  /**
   *	vfree  -  release memory allocated by vmalloc()

   *	@addr:		memory base address
   *

   *	Free the virtually continuous memory area starting at @addr, as

   *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
   *	NULL, no operation is performed.

   *

   *	Must not be called in interrupt context.

   */

  void vfree(const void *addr)

  {
  	BUG_ON(in_interrupt());

  
  	kmemleak_free(addr);

  	__vunmap(addr, 1);
  }

  EXPORT_SYMBOL(vfree);
  
  /**
   *	vunmap  -  release virtual mapping obtained by vmap()

   *	@addr:		memory base address
   *
   *	Free the virtually contiguous memory area starting at @addr,
   *	which was created from the page array passed to vmap().
   *

   *	Must not be called in interrupt context.

   */

  void vunmap(const void *addr)

  {
  	BUG_ON(in_interrupt());

  	might_sleep();

  	__vunmap(addr, 0);
  }

  EXPORT_SYMBOL(vunmap);
  
  /**
   *	vmap  -  map an array of pages into virtually contiguous space

   *	@pages:		array of page pointers
   *	@count:		number of pages to map
   *	@flags:		vm_area->flags
   *	@prot:		page protection for the mapping
   *
   *	Maps @count pages from @pages into contiguous kernel virtual
   *	space.
   */
  void *vmap(struct page **pages, unsigned int count,
  		unsigned long flags, pgprot_t prot)
  {
  	struct vm_struct *area;

  	might_sleep();

  	if (count > totalram_pages)

  		return NULL;

  	area = get_vm_area_caller((count << PAGE_SHIFT), flags,
  					__builtin_return_address(0));

  	if (!area)
  		return NULL;

  	if (map_vm_area(area, prot, &pages)) {
  		vunmap(area->addr);
  		return NULL;
  	}
  
  	return area->addr;
  }

  EXPORT_SYMBOL(vmap);

  static void *__vmalloc_node(unsigned long size, unsigned long align,
  			    gfp_t gfp_mask, pgprot_t prot,

  			    int node, const void *caller);

  static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,

  				 pgprot_t prot, int node, const void *caller)

  {

  	const int order = 0;

  	struct page **pages;
  	unsigned int nr_pages, array_size, i;

  	gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;

  
  	nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
  	array_size = (nr_pages * sizeof(struct page *));
  
  	area->nr_pages = nr_pages;
  	/* Please note that the recursion is strictly bounded. */

  	if (array_size > PAGE_SIZE) {

  		pages = __vmalloc_node(array_size, 1, nested_gfp|__GFP_HIGHMEM,

  				PAGE_KERNEL, node, caller);

  		area->flags |= VM_VPAGES;

  	} else {

  		pages = kmalloc_node(array_size, nested_gfp, node);

  	}

  	area->pages = pages;

  	area->caller = caller;

  	if (!area->pages) {
  		remove_vm_area(area->addr);
  		kfree(area);
  		return NULL;
  	}

  
  	for (i = 0; i < area->nr_pages; i++) {

  		struct page *page;

  		gfp_t tmp_mask = gfp_mask | __GFP_NOWARN;

  		if (node < 0)

  			page = alloc_page(tmp_mask);

  		else

  			page = alloc_pages_node(node, tmp_mask, order);

  
  		if (unlikely(!page)) {

  			/* Successfully allocated i pages, free them in __vunmap() */
  			area->nr_pages = i;
  			goto fail;
  		}

  		area->pages[i] = page;

  	}
  
  	if (map_vm_area(area, prot, &pages))
  		goto fail;
  	return area->addr;
  
  fail:

  	warn_alloc_failed(gfp_mask, order,
  			  "vmalloc: allocation failure, allocated %ld of %ld bytes
  ",

  			  (area->nr_pages*PAGE_SIZE), area->size);

  	vfree(area->addr);
  	return NULL;
  }
  
  /**

   *	__vmalloc_node_range  -  allocate virtually contiguous memory

   *	@size:		allocation size

   *	@align:		desired alignment

   *	@start:		vm area range start
   *	@end:		vm area range end

   *	@gfp_mask:	flags for the page level allocator
   *	@prot:		protection mask for the allocated pages

   *	@node:		node to use for allocation or NUMA_NO_NODE

   *	@caller:	caller's return address

   *
   *	Allocate enough pages to cover @size from the page level
   *	allocator with @gfp_mask flags.  Map them into contiguous
   *	kernel virtual space, using a pagetable protection of @prot.
   */

  void *__vmalloc_node_range(unsigned long size, unsigned long align,
  			unsigned long start, unsigned long end, gfp_t gfp_mask,

  			pgprot_t prot, int node, const void *caller)

  {
  	struct vm_struct *area;

  	void *addr;
  	unsigned long real_size = size;

  
  	size = PAGE_ALIGN(size);

  	if (!size || (size >> PAGE_SHIFT) > totalram_pages)

  		goto fail;

  	area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNLIST,
  				  start, end, node, gfp_mask, caller);

  	if (!area)

  		goto fail;

  	addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller);

  	if (!addr)
  		return NULL;

  
  	/*

  	 * In this function, newly allocated vm_struct is not added
  	 * to vmlist at __get_vm_area_node(). so, it is added here.
  	 */
  	insert_vmalloc_vmlist(area);
  
  	/*

  	 * A ref_count = 3 is needed because the vm_struct and vmap_area
  	 * structures allocated in the __get_vm_area_node() function contain
  	 * references to the virtual address of the vmalloc'ed block.
  	 */
  	kmemleak_alloc(addr, real_size, 3, gfp_mask);
  
  	return addr;

  
  fail:
  	warn_alloc_failed(gfp_mask, 0,
  			  "vmalloc: allocation failure: %lu bytes
  ",
  			  real_size);
  	return NULL;

  }

  /**
   *	__vmalloc_node  -  allocate virtually contiguous memory
   *	@size:		allocation size
   *	@align:		desired alignment
   *	@gfp_mask:	flags for the page level allocator
   *	@prot:		protection mask for the allocated pages

   *	@node:		node to use for allocation or NUMA_NO_NODE

   *	@caller:	caller's return address
   *
   *	Allocate enough pages to cover @size from the page level
   *	allocator with @gfp_mask flags.  Map them into contiguous
   *	kernel virtual space, using a pagetable protection of @prot.
   */
  static void *__vmalloc_node(unsigned long size, unsigned long align,
  			    gfp_t gfp_mask, pgprot_t prot,

  			    int node, const void *caller)

  {
  	return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
  				gfp_mask, prot, node, caller);
  }

  void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
  {

  	return __vmalloc_node(size, 1, gfp_mask, prot, NUMA_NO_NODE,

  				__builtin_return_address(0));

  }

  EXPORT_SYMBOL(__vmalloc);

  static inline void *__vmalloc_node_flags(unsigned long size,
  					int node, gfp_t flags)
  {
  	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
  					node, __builtin_return_address(0));
  }

  /**
   *	vmalloc  -  allocate virtually contiguous memory

   *	@size:		allocation size

   *	Allocate enough pages to cover @size from the page level
   *	allocator and map them into contiguous kernel virtual space.
   *

   *	For tight control over page level allocator and protection flags

   *	use __vmalloc() instead.
   */
  void *vmalloc(unsigned long size)
  {

  	return __vmalloc_node_flags(size, NUMA_NO_NODE,
  				    GFP_KERNEL | __GFP_HIGHMEM);

  }

  EXPORT_SYMBOL(vmalloc);

  /**

   *	vzalloc - allocate virtually contiguous memory with zero fill
   *	@size:	allocation size
   *	Allocate enough pages to cover @size from the page level
   *	allocator and map them into contiguous kernel virtual space.
   *	The memory allocated is set to zero.
   *
   *	For tight control over page level allocator and protection flags
   *	use __vmalloc() instead.
   */
  void *vzalloc(unsigned long size)
  {

  	return __vmalloc_node_flags(size, NUMA_NO_NODE,

  				GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
  }
  EXPORT_SYMBOL(vzalloc);
  
  /**

   * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
   * @size: allocation size

   *

   * The resulting memory area is zeroed so it can be mapped to userspace
   * without leaking data.

   */
  void *vmalloc_user(unsigned long size)
  {
  	struct vm_struct *area;
  	void *ret;

  	ret = __vmalloc_node(size, SHMLBA,
  			     GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,

  			     PAGE_KERNEL, NUMA_NO_NODE,
  			     __builtin_return_address(0));

  	if (ret) {

  		area = find_vm_area(ret);

  		area->flags |= VM_USERMAP;

  	}

  	return ret;
  }
  EXPORT_SYMBOL(vmalloc_user);
  
  /**

   *	vmalloc_node  -  allocate memory on a specific node

   *	@size:		allocation size

   *	@node:		numa node

   *
   *	Allocate enough pages to cover @size from the page level
   *	allocator and map them into contiguous kernel virtual space.
   *

   *	For tight control over page level allocator and protection flags

   *	use __vmalloc() instead.
   */
  void *vmalloc_node(unsigned long size, int node)
  {

  	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,

  					node, __builtin_return_address(0));

  }
  EXPORT_SYMBOL(vmalloc_node);

  /**
   * vzalloc_node - allocate memory on a specific node with zero fill
   * @size:	allocation size
   * @node:	numa node
   *
   * Allocate enough pages to cover @size from the page level
   * allocator and map them into contiguous kernel virtual space.
   * The memory allocated is set to zero.
   *
   * For tight control over page level allocator and protection flags
   * use __vmalloc_node() instead.
   */
  void *vzalloc_node(unsigned long size, int node)
  {
  	return __vmalloc_node_flags(size, node,
  			 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
  }
  EXPORT_SYMBOL(vzalloc_node);

  #ifndef PAGE_KERNEL_EXEC
  # define PAGE_KERNEL_EXEC PAGE_KERNEL
  #endif

  /**
   *	vmalloc_exec  -  allocate virtually contiguous, executable memory

   *	@size:		allocation size
   *
   *	Kernel-internal function to allocate enough pages to cover @size
   *	the page level allocator and map them into contiguous and
   *	executable kernel virtual space.
   *

   *	For tight control over page level allocator and protection flags

   *	use __vmalloc() instead.
   */

  void *vmalloc_exec(unsigned long size)
  {

  	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,

  			      NUMA_NO_NODE, __builtin_return_address(0));

  }

  #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)

  #define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL

  #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)

  #define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL

  #else
  #define GFP_VMALLOC32 GFP_KERNEL
  #endif

  /**
   *	vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)

   *	@size:		allocation size
   *
   *	Allocate enough 32bit PA addressable pages to cover @size from the
   *	page level allocator and map them into contiguous kernel virtual space.
   */
  void *vmalloc_32(unsigned long size)
  {

  	return __vmalloc_node(size, 1, GFP_VMALLOC32, PAGE_KERNEL,

  			      NUMA_NO_NODE, __builtin_return_address(0));

  }

  EXPORT_SYMBOL(vmalloc_32);

  /**

   * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory

   *	@size:		allocation size

   *
   * The resulting memory area is 32bit addressable and zeroed so it can be
   * mapped to userspace without leaking data.

   */
  void *vmalloc_32_user(unsigned long size)
  {
  	struct vm_struct *area;
  	void *ret;

  	ret = __vmalloc_node(size, 1, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,

  			     NUMA_NO_NODE, __builtin_return_address(0));

  	if (ret) {

  		area = find_vm_area(ret);

  		area->flags |= VM_USERMAP;

  	}

  	return ret;
  }
  EXPORT_SYMBOL(vmalloc_32_user);

  /*
   * small helper routine , copy contents to buf from addr.
   * If the page is not present, fill zero.
   */
  
  static int aligned_vread(char *buf, char *addr, unsigned long count)
  {
  	struct page *p;
  	int copied = 0;
  
  	while (count) {
  		unsigned long offset, length;
  
  		offset = (unsigned long)addr & ~PAGE_MASK;
  		length = PAGE_SIZE - offset;
  		if (length > count)
  			length = count;
  		p = vmalloc_to_page(addr);
  		/*
  		 * To do safe access to this _mapped_ area, we need
  		 * lock. But adding lock here means that we need to add
  		 * overhead of vmalloc()/vfree() calles for this _debug_
  		 * interface, rarely used. Instead of that, we'll use
  		 * kmap() and get small overhead in this access function.
  		 */
  		if (p) {
  			/*
  			 * we can expect USER0 is not used (see vread/vwrite's
  			 * function description)
  			 */

  			void *map = kmap_atomic(p);

  			memcpy(buf, map + offset, length);

  			kunmap_atomic(map);

  		} else
  			memset(buf, 0, length);
  
  		addr += length;
  		buf += length;
  		copied += length;
  		count -= length;
  	}
  	return copied;
  }
  
  static int aligned_vwrite(char *buf, char *addr, unsigned long count)
  {
  	struct page *p;
  	int copied = 0;
  
  	while (count) {
  		unsigned long offset, length;
  
  		offset = (unsigned long)addr & ~PAGE_MASK;
  		length = PAGE_SIZE - offset;
  		if (length > count)
  			length = count;
  		p = vmalloc_to_page(addr);
  		/*
  		 * To do safe access to this _mapped_ area, we need
  		 * lock. But adding lock here means that we need to add
  		 * overhead of vmalloc()/vfree() calles for this _debug_
  		 * interface, rarely used. Instead of that, we'll use
  		 * kmap() and get small overhead in this access function.
  		 */
  		if (p) {
  			/*
  			 * we can expect USER0 is not used (see vread/vwrite's
  			 * function description)
  			 */

  			void *map = kmap_atomic(p);

  			memcpy(map + offset, buf, length);

  			kunmap_atomic(map);

  		}
  		addr += length;
  		buf += length;
  		copied += length;
  		count -= length;
  	}
  	return copied;
  }
  
  /**
   *	vread() -  read vmalloc area in a safe way.
   *	@buf:		buffer for reading data
   *	@addr:		vm address.
   *	@count:		number of bytes to be read.
   *
   *	Returns # of bytes which addr and buf should be increased.
   *	(same number to @count). Returns 0 if [addr...addr+count) doesn't
   *	includes any intersect with alive vmalloc area.
   *
   *	This function checks that addr is a valid vmalloc'ed area, and
   *	copy data from that area to a given buffer. If the given memory range
   *	of [addr...addr+count) includes some valid address, data is copied to
   *	proper area of @buf. If there are memory holes, they'll be zero-filled.
   *	IOREMAP area is treated as memory hole and no copy is done.
   *
   *	If [addr...addr+count) doesn't includes any intersects with alive

   *	vm_struct area, returns 0. @buf should be kernel's buffer.

   *
   *	Note: In usual ops, vread() is never necessary because the caller
   *	should know vmalloc() area is valid and can use memcpy().
   *	This is for routines which have to access vmalloc area without
   *	any informaion, as /dev/kmem.
   *
   */

  long vread(char *buf, char *addr, unsigned long count)
  {
  	struct vm_struct *tmp;
  	char *vaddr, *buf_start = buf;

  	unsigned long buflen = count;

  	unsigned long n;
  
  	/* Don't allow overflow */
  	if ((unsigned long) addr + count < count)
  		count = -(unsigned long) addr;
  
  	read_lock(&vmlist_lock);

  	for (tmp = vmlist; count && tmp; tmp = tmp->next) {

  		vaddr = (char *) tmp->addr;
  		if (addr >= vaddr + tmp->size - PAGE_SIZE)
  			continue;
  		while (addr < vaddr) {
  			if (count == 0)
  				goto finished;
  			*buf = '\0';
  			buf++;
  			addr++;
  			count--;
  		}
  		n = vaddr + tmp->size - PAGE_SIZE - addr;

  		if (n > count)
  			n = count;
  		if (!(tmp->flags & VM_IOREMAP))
  			aligned_vread(buf, addr, n);
  		else /* IOREMAP area is treated as memory hole */
  			memset(buf, 0, n);
  		buf += n;
  		addr += n;
  		count -= n;

  	}
  finished:
  	read_unlock(&vmlist_lock);

  
  	if (buf == buf_start)
  		return 0;
  	/* zero-fill memory holes */
  	if (buf != buf_start + buflen)
  		memset(buf, 0, buflen - (buf - buf_start));
  
  	return buflen;

  }

  /**
   *	vwrite() -  write vmalloc area in a safe way.
   *	@buf:		buffer for source data
   *	@addr:		vm address.
   *	@count:		number of bytes to be read.
   *
   *	Returns # of bytes which addr and buf should be incresed.
   *	(same number to @count).
   *	If [addr...addr+count) doesn't includes any intersect with valid
   *	vmalloc area, returns 0.
   *
   *	This function checks that addr is a valid vmalloc'ed area, and
   *	copy data from a buffer to the given addr. If specified range of
   *	[addr...addr+count) includes some valid address, data is copied from
   *	proper area of @buf. If there are memory holes, no copy to hole.
   *	IOREMAP area is treated as memory hole and no copy is done.
   *
   *	If [addr...addr+count) doesn't includes any intersects with alive

   *	vm_struct area, returns 0. @buf should be kernel's buffer.

   *
   *	Note: In usual ops, vwrite() is never necessary because the caller
   *	should know vmalloc() area is valid and can use memcpy().
   *	This is for routines which have to access vmalloc area without
   *	any informaion, as /dev/kmem.

   */

  long vwrite(char *buf, char *addr, unsigned long count)
  {
  	struct vm_struct *tmp;

  	char *vaddr;
  	unsigned long n, buflen;
  	int copied = 0;

  
  	/* Don't allow overflow */
  	if ((unsigned long) addr + count < count)
  		count = -(unsigned long) addr;

  	buflen = count;

  
  	read_lock(&vmlist_lock);

  	for (tmp = vmlist; count && tmp; tmp = tmp->next) {

  		vaddr = (char *) tmp->addr;
  		if (addr >= vaddr + tmp->size - PAGE_SIZE)
  			continue;
  		while (addr < vaddr) {
  			if (count == 0)
  				goto finished;
  			buf++;
  			addr++;
  			count--;
  		}
  		n = vaddr + tmp->size - PAGE_SIZE - addr;

  		if (n > count)
  			n = count;
  		if (!(tmp->flags & VM_IOREMAP)) {
  			aligned_vwrite(buf, addr, n);
  			copied++;
  		}
  		buf += n;
  		addr += n;
  		count -= n;

  	}
  finished:
  	read_unlock(&vmlist_lock);

  	if (!copied)
  		return 0;
  	return buflen;

  }

  
  /**
   *	remap_vmalloc_range  -  map vmalloc pages to userspace

   *	@vma:		vma to cover (map full range of vma)
   *	@addr:		vmalloc memory
   *	@pgoff:		number of pages into addr before first page to map

   *
   *	Returns:	0 for success, -Exxx on failure

   *
   *	This function checks that addr is a valid vmalloc'ed area, and
   *	that it is big enough to cover the vma. Will return failure if
   *	that criteria isn't met.
   *

   *	Similar to remap_pfn_range() (see mm/memory.c)

   */
  int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
  						unsigned long pgoff)
  {
  	struct vm_struct *area;
  	unsigned long uaddr = vma->vm_start;
  	unsigned long usize = vma->vm_end - vma->vm_start;

  
  	if ((PAGE_SIZE-1) & (unsigned long)addr)
  		return -EINVAL;

  	area = find_vm_area(addr);

  	if (!area)

  		return -EINVAL;

  
  	if (!(area->flags & VM_USERMAP))

  		return -EINVAL;

  
  	if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)

  		return -EINVAL;

  
  	addr += pgoff << PAGE_SHIFT;
  	do {
  		struct page *page = vmalloc_to_page(addr);

  		int ret;

  		ret = vm_insert_page(vma, uaddr, page);
  		if (ret)
  			return ret;
  
  		uaddr += PAGE_SIZE;
  		addr += PAGE_SIZE;
  		usize -= PAGE_SIZE;
  	} while (usize > 0);

  	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;

  	return 0;

  }
  EXPORT_SYMBOL(remap_vmalloc_range);

  /*
   * Implement a stub for vmalloc_sync_all() if the architecture chose not to
   * have one.
   */
  void  __attribute__((weak)) vmalloc_sync_all(void)
  {
  }

  static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)

  {

  	pte_t ***p = data;
  
  	if (p) {
  		*(*p) = pte;
  		(*p)++;
  	}

  	return 0;
  }
  
  /**
   *	alloc_vm_area - allocate a range of kernel address space
   *	@size:		size of the area

   *	@ptes:		returns the PTEs for the address space

   *
   *	Returns:	NULL on failure, vm_struct on success

   *
   *	This function reserves a range of kernel address space, and
   *	allocates pagetables to map that range.  No actual mappings

   *	are created.
   *
   *	If @ptes is non-NULL, pointers to the PTEs (in init_mm)
   *	allocated for the VM area are returned.

   */

  struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)

  {
  	struct vm_struct *area;

  	area = get_vm_area_caller(size, VM_IOREMAP,
  				__builtin_return_address(0));

  	if (area == NULL)
  		return NULL;
  
  	/*
  	 * This ensures that page tables are constructed for this region
  	 * of kernel virtual address space and mapped into init_mm.
  	 */
  	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,

  				size, f, ptes ? &ptes : NULL)) {

  		free_vm_area(area);
  		return NULL;
  	}

  	return area;
  }
  EXPORT_SYMBOL_GPL(alloc_vm_area);
  
  void free_vm_area(struct vm_struct *area)
  {
  	struct vm_struct *ret;
  	ret = remove_vm_area(area->addr);
  	BUG_ON(ret != area);
  	kfree(area);
  }
  EXPORT_SYMBOL_GPL(free_vm_area);

  #ifdef CONFIG_SMP

  static struct vmap_area *node_to_va(struct rb_node *n)
  {
  	return n ? rb_entry(n, struct vmap_area, rb_node) : NULL;
  }
  
  /**
   * pvm_find_next_prev - find the next and prev vmap_area surrounding @end
   * @end: target address
   * @pnext: out arg for the next vmap_area
   * @pprev: out arg for the previous vmap_area
   *
   * Returns: %true if either or both of next and prev are found,
   *	    %false if no vmap_area exists
   *
   * Find vmap_areas end addresses of which enclose @end.  ie. if not
   * NULL, *pnext->va_end > @end and *pprev->va_end <= @end.
   */
  static bool pvm_find_next_prev(unsigned long end,
  			       struct vmap_area **pnext,
  			       struct vmap_area **pprev)
  {
  	struct rb_node *n = vmap_area_root.rb_node;
  	struct vmap_area *va = NULL;
  
  	while (n) {
  		va = rb_entry(n, struct vmap_area, rb_node);
  		if (end < va->va_end)
  			n = n->rb_left;
  		else if (end > va->va_end)
  			n = n->rb_right;
  		else
  			break;
  	}
  
  	if (!va)
  		return false;
  
  	if (va->va_end > end) {
  		*pnext = va;
  		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
  	} else {
  		*pprev = va;
  		*pnext = node_to_va(rb_next(&(*pprev)->rb_node));
  	}
  	return true;
  }
  
  /**
   * pvm_determine_end - find the highest aligned address between two vmap_areas
   * @pnext: in/out arg for the next vmap_area
   * @pprev: in/out arg for the previous vmap_area
   * @align: alignment
   *
   * Returns: determined end address
   *
   * Find the highest aligned address between *@pnext and *@pprev below
   * VMALLOC_END.  *@pnext and *@pprev are adjusted so that the aligned
   * down address is between the end addresses of the two vmap_areas.
   *
   * Please note that the address returned by this function may fall
   * inside *@pnext vmap_area.  The caller is responsible for checking
   * that.
   */
  static unsigned long pvm_determine_end(struct vmap_area **pnext,
  				       struct vmap_area **pprev,
  				       unsigned long align)
  {
  	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
  	unsigned long addr;
  
  	if (*pnext)
  		addr = min((*pnext)->va_start & ~(align - 1), vmalloc_end);
  	else
  		addr = vmalloc_end;
  
  	while (*pprev && (*pprev)->va_end > addr) {
  		*pnext = *pprev;
  		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
  	}
  
  	return addr;
  }
  
  /**
   * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
   * @offsets: array containing offset of each area
   * @sizes: array containing size of each area
   * @nr_vms: the number of areas to allocate
   * @align: alignment, all entries in @offsets and @sizes must be aligned to this

   *
   * Returns: kmalloc'd vm_struct pointer array pointing to allocated
   *	    vm_structs on success, %NULL on failure
   *
   * Percpu allocator wants to use congruent vm areas so that it can
   * maintain the offsets among percpu areas.  This function allocates

   * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
   * be scattered pretty far, distance between two areas easily going up
   * to gigabytes.  To avoid interacting with regular vmallocs, these
   * areas are allocated from top.

   *
   * Despite its complicated look, this allocator is rather simple.  It
   * does everything top-down and scans areas from the end looking for
   * matching slot.  While scanning, if any of the areas overlaps with
   * existing vmap_area, the base address is pulled down to fit the
   * area.  Scanning is repeated till all the areas fit and then all
   * necessary data structres are inserted and the result is returned.
   */
  struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
  				     const size_t *sizes, int nr_vms,

  				     size_t align)

  {
  	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
  	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
  	struct vmap_area **vas, *prev, *next;
  	struct vm_struct **vms;
  	int area, area2, last_area, term_area;
  	unsigned long base, start, end, last_end;
  	bool purged = false;

  	/* verify parameters and allocate data structures */
  	BUG_ON(align & ~PAGE_MASK || !is_power_of_2(align));
  	for (last_area = 0, area = 0; area < nr_vms; area++) {
  		start = offsets[area];
  		end = start + sizes[area];
  
  		/* is everything aligned properly? */
  		BUG_ON(!IS_ALIGNED(offsets[area], align));
  		BUG_ON(!IS_ALIGNED(sizes[area], align));
  
  		/* detect the area with the highest address */
  		if (start > offsets[last_area])
  			last_area = area;
  
  		for (area2 = 0; area2 < nr_vms; area2++) {
  			unsigned long start2 = offsets[area2];
  			unsigned long end2 = start2 + sizes[area2];
  
  			if (area2 == area)
  				continue;
  
  			BUG_ON(start2 >= start && start2 < end);
  			BUG_ON(end2 <= end && end2 > start);
  		}
  	}
  	last_end = offsets[last_area] + sizes[last_area];
  
  	if (vmalloc_end - vmalloc_start < last_end) {
  		WARN_ON(true);
  		return NULL;
  	}

  	vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
  	vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);

  	if (!vas || !vms)

  		goto err_free2;

  
  	for (area = 0; area < nr_vms; area++) {

  		vas[area] = kzalloc(sizeof(struct vmap_area), GFP_KERNEL);
  		vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);

  		if (!vas[area] || !vms[area])
  			goto err_free;
  	}
  retry:
  	spin_lock(&vmap_area_lock);
  
  	/* start scanning - we scan from the top, begin with the last area */
  	area = term_area = last_area;
  	start = offsets[area];
  	end = start + sizes[area];
  
  	if (!pvm_find_next_prev(vmap_area_pcpu_hole, &next, &prev)) {
  		base = vmalloc_end - last_end;
  		goto found;
  	}
  	base = pvm_determine_end(&next, &prev, align) - end;
  
  	while (true) {
  		BUG_ON(next && next->va_end <= base + end);
  		BUG_ON(prev && prev->va_end > base + end);
  
  		/*
  		 * base might have underflowed, add last_end before
  		 * comparing.
  		 */
  		if (base + last_end < vmalloc_start + last_end) {
  			spin_unlock(&vmap_area_lock);
  			if (!purged) {
  				purge_vmap_area_lazy();
  				purged = true;
  				goto retry;
  			}
  			goto err_free;
  		}
  
  		/*
  		 * If next overlaps, move base downwards so that it's
  		 * right below next and then recheck.
  		 */
  		if (next && next->va_start < base + end) {
  			base = pvm_determine_end(&next, &prev, align) - end;
  			term_area = area;
  			continue;
  		}
  
  		/*
  		 * If prev overlaps, shift down next and prev and move
  		 * base so that it's right below new next and then
  		 * recheck.
  		 */
  		if (prev && prev->va_end > base + start)  {
  			next = prev;
  			prev = node_to_va(rb_prev(&next->rb_node));
  			base = pvm_determine_end(&next, &prev, align) - end;
  			term_area = area;
  			continue;
  		}
  
  		/*
  		 * This area fits, move on to the previous one.  If
  		 * the previous one is the terminal one, we're done.
  		 */
  		area = (area + nr_vms - 1) % nr_vms;
  		if (area == term_area)
  			break;
  		start = offsets[area];
  		end = start + sizes[area];
  		pvm_find_next_prev(base + end, &next, &prev);
  	}
  found:
  	/* we've found a fitting base, insert all va's */
  	for (area = 0; area < nr_vms; area++) {
  		struct vmap_area *va = vas[area];
  
  		va->va_start = base + offsets[area];
  		va->va_end = va->va_start + sizes[area];
  		__insert_vmap_area(va);
  	}
  
  	vmap_area_pcpu_hole = base + offsets[last_area];
  
  	spin_unlock(&vmap_area_lock);
  
  	/* insert all vm's */
  	for (area = 0; area < nr_vms; area++)
  		insert_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
  				  pcpu_get_vm_areas);
  
  	kfree(vas);
  	return vms;
  
  err_free:
  	for (area = 0; area < nr_vms; area++) {

  		kfree(vas[area]);
  		kfree(vms[area]);

  	}

  err_free2:

  	kfree(vas);
  	kfree(vms);
  	return NULL;
  }
  
  /**
   * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
   * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
   * @nr_vms: the number of allocated areas
   *
   * Free vm_structs and the array allocated by pcpu_get_vm_areas().
   */
  void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
  {
  	int i;
  
  	for (i = 0; i < nr_vms; i++)
  		free_vm_area(vms[i]);
  	kfree(vms);
  }

  #endif	/* CONFIG_SMP */

  
  #ifdef CONFIG_PROC_FS
  static void *s_start(struct seq_file *m, loff_t *pos)

  	__acquires(&vmlist_lock)

  {
  	loff_t n = *pos;
  	struct vm_struct *v;
  
  	read_lock(&vmlist_lock);
  	v = vmlist;
  	while (n > 0 && v) {
  		n--;
  		v = v->next;
  	}
  	if (!n)
  		return v;
  
  	return NULL;
  
  }
  
  static void *s_next(struct seq_file *m, void *p, loff_t *pos)
  {
  	struct vm_struct *v = p;
  
  	++*pos;
  	return v->next;
  }
  
  static void s_stop(struct seq_file *m, void *p)

  	__releases(&vmlist_lock)

  {
  	read_unlock(&vmlist_lock);
  }

  static void show_numa_info(struct seq_file *m, struct vm_struct *v)
  {

  	if (IS_ENABLED(CONFIG_NUMA)) {

  		unsigned int nr, *counters = m->private;
  
  		if (!counters)
  			return;
  
  		memset(counters, 0, nr_node_ids * sizeof(unsigned int));
  
  		for (nr = 0; nr < v->nr_pages; nr++)
  			counters[page_to_nid(v->pages[nr])]++;
  
  		for_each_node_state(nr, N_HIGH_MEMORY)
  			if (counters[nr])
  				seq_printf(m, " N%u=%u", nr, counters[nr]);
  	}
  }

  static int s_show(struct seq_file *m, void *p)
  {
  	struct vm_struct *v = p;

  	seq_printf(m, "0x%pK-0x%pK %7ld",

  		v->addr, v->addr + v->size, v->size);

  	if (v->caller)
  		seq_printf(m, " %pS", v->caller);

  	if (v->nr_pages)
  		seq_printf(m, " pages=%d", v->nr_pages);
  
  	if (v->phys_addr)

  		seq_printf(m, " phys=%llx", (unsigned long long)v->phys_addr);

  
  	if (v->flags & VM_IOREMAP)
  		seq_printf(m, " ioremap");
  
  	if (v->flags & VM_ALLOC)
  		seq_printf(m, " vmalloc");
  
  	if (v->flags & VM_MAP)
  		seq_printf(m, " vmap");
  
  	if (v->flags & VM_USERMAP)
  		seq_printf(m, " user");
  
  	if (v->flags & VM_VPAGES)
  		seq_printf(m, " vpages");

  	show_numa_info(m, v);

  	seq_putc(m, '
  ');
  	return 0;
  }

  static const struct seq_operations vmalloc_op = {

  	.start = s_start,
  	.next = s_next,
  	.stop = s_stop,
  	.show = s_show,
  };

  
  static int vmalloc_open(struct inode *inode, struct file *file)
  {
  	unsigned int *ptr = NULL;
  	int ret;

  	if (IS_ENABLED(CONFIG_NUMA)) {

  		ptr = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);

  		if (ptr == NULL)
  			return -ENOMEM;
  	}

  	ret = seq_open(file, &vmalloc_op);
  	if (!ret) {
  		struct seq_file *m = file->private_data;
  		m->private = ptr;
  	} else
  		kfree(ptr);
  	return ret;
  }
  
  static const struct file_operations proc_vmalloc_operations = {
  	.open		= vmalloc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release_private,
  };
  
  static int __init proc_vmalloc_init(void)
  {
  	proc_create("vmallocinfo", S_IRUSR, NULL, &proc_vmalloc_operations);
  	return 0;
  }
  module_init(proc_vmalloc_init);

  #endif