/*
   *  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/signal.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/notifier.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 <linux/compiler.h>

  #include <linux/llist.h>

  #include <linux/bitops.h>

  #include <linux/uaccess.h>

  #include <asm/tlbflush.h>

  #include <asm/shmparam.h>

  #include "internal.h"

  struct vfree_deferred {
  	struct llist_head list;
  	struct work_struct wq;
  };
  static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);
  
  static void __vunmap(const void *, int);
  
  static void free_work(struct work_struct *w)
  {
  	struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);

  	struct llist_node *t, *llnode;
  
  	llist_for_each_safe(llnode, t, llist_del_all(&p->list))
  		__vunmap((void *)llnode, 1);

  }

  /*** 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_clear_huge(pmd))
  			continue;

  		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(p4d_t *p4d, unsigned long addr, unsigned long end)

  {
  	pud_t *pud;
  	unsigned long next;

  	pud = pud_offset(p4d, addr);

  	do {
  		next = pud_addr_end(addr, end);

  		if (pud_clear_huge(pud))
  			continue;

  		if (pud_none_or_clear_bad(pud))
  			continue;
  		vunmap_pmd_range(pud, addr, next);
  	} while (pud++, addr = next, addr != end);
  }

  static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
  {
  	p4d_t *p4d;
  	unsigned long next;
  
  	p4d = p4d_offset(pgd, addr);
  	do {
  		next = p4d_addr_end(addr, end);
  		if (p4d_clear_huge(p4d))
  			continue;
  		if (p4d_none_or_clear_bad(p4d))
  			continue;
  		vunmap_pud_range(p4d, addr, next);
  	} while (p4d++, 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_p4d_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(p4d_t *p4d, 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, p4d, 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;
  }

  static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
  		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
  {
  	p4d_t *p4d;
  	unsigned long next;
  
  	p4d = p4d_alloc(&init_mm, pgd, addr);
  	if (!p4d)
  		return -ENOMEM;
  	do {
  		next = p4d_addr_end(addr, end);
  		if (vmap_pud_range(p4d, addr, next, prot, pages, nr))
  			return -ENOMEM;
  	} while (p4d++, 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_p4d_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);

  	p4d_t *p4d;
  	pud_t *pud;
  	pmd_t *pmd;
  	pte_t *ptep, pte;

  	/*
  	 * 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))
  		return NULL;
  	p4d = p4d_offset(pgd, addr);
  	if (p4d_none(*p4d))
  		return NULL;
  	pud = pud_offset(p4d, addr);

  
  	/*
  	 * Don't dereference bad PUD or PMD (below) entries. This will also
  	 * identify huge mappings, which we may encounter on architectures
  	 * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be
  	 * identified as vmalloc addresses by is_vmalloc_addr(), but are
  	 * not [unambiguously] associated with a struct page, so there is
  	 * no correct value to return for them.
  	 */
  	WARN_ON_ONCE(pud_bad(*pud));
  	if (pud_none(*pud) || pud_bad(*pud))

  		return NULL;
  	pmd = pmd_offset(pud, addr);

  	WARN_ON_ONCE(pmd_bad(*pmd));
  	if (pmd_none(*pmd) || pmd_bad(*pmd))

  		return NULL;
  
  	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	0x02

  #define VM_VM_AREA	0x04

  static DEFINE_SPINLOCK(vmap_area_lock);

  /* Export for kexec only */
  LIST_HEAD(vmap_area_list);

  static LLIST_HEAD(vmap_purge_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_end)

  			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 */

  	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);

  static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);

  /*
   * 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(offset_in_page(size));

  	BUG_ON(!is_power_of_2(align));

  	might_sleep();

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

  	/*
  	 * Only scan the relevant parts containing pointers to other objects
  	 * to avoid false negatives.
  	 */
  	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);

  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 < addr)

  			goto overflow;
  
  	} else {
  		addr = ALIGN(vstart, align);

  		if (addr + size < 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 < addr)

  			goto overflow;

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

  			goto found;

  		first = list_next_entry(first, 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(!IS_ALIGNED(va->va_start, align));

  	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 (gfpflags_allow_blocking(gfp_mask)) {
  		unsigned long freed = 0;
  		blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
  		if (freed > 0) {
  			purged = 0;
  			goto retry;
  		}
  	}

  	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())

  		pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size
  ",
  			size);

  	kfree(va);
  	return ERR_PTR(-EBUSY);

  }

  int register_vmap_purge_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_register(&vmap_notify_list, nb);
  }
  EXPORT_SYMBOL_GPL(register_vmap_purge_notifier);
  
  int unregister_vmap_purge_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
  }
  EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);

  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);
  }
  
  /*
   * 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);

  /*
   * Serialize vmap purging.  There is no actual criticial section protected
   * by this look, but we want to avoid concurrent calls for performance
   * reasons and to make the pcpu_get_vm_areas more deterministic.
   */

  static DEFINE_MUTEX(vmap_purge_lock);

  /* 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.

   */

  static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)

  {

  	struct llist_node *valist;

  	struct vmap_area *va;

  	struct vmap_area *n_va;

  	bool do_free = false;

  	lockdep_assert_held(&vmap_purge_lock);

  	valist = llist_del_all(&vmap_purge_list);
  	llist_for_each_entry(va, valist, purge_list) {

  		if (va->va_start < start)
  			start = va->va_start;
  		if (va->va_end > end)
  			end = va->va_end;

  		do_free = true;

  	}

  	if (!do_free)

  		return false;

  	flush_tlb_kernel_range(start, end);

  	spin_lock(&vmap_area_lock);

  	llist_for_each_entry_safe(va, n_va, valist, purge_list) {
  		int nr = (va->va_end - va->va_start) >> PAGE_SHIFT;

  		__free_vmap_area(va);

  		atomic_sub(nr, &vmap_lazy_nr);
  		cond_resched_lock(&vmap_area_lock);
  	}

  	spin_unlock(&vmap_area_lock);
  	return true;

  }
  
  /*

   * 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)
  {

  	if (mutex_trylock(&vmap_purge_lock)) {

  		__purge_vmap_area_lazy(ULONG_MAX, 0);

  		mutex_unlock(&vmap_purge_lock);

  	}

  }
  
  /*

   * Kick off a purge of the outstanding lazy areas.
   */
  static void purge_vmap_area_lazy(void)
  {

  	mutex_lock(&vmap_purge_lock);

  	purge_fragmented_blocks_allcpus();
  	__purge_vmap_area_lazy(ULONG_MAX, 0);

  	mutex_unlock(&vmap_purge_lock);

  }
  
  /*

   * 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)

  {

  	int nr_lazy;
  
  	nr_lazy = atomic_add_return((va->va_end - va->va_start) >> PAGE_SHIFT,
  				    &vmap_lazy_nr);
  
  	/* After this point, we may free va at any time */
  	llist_add(&va->purge_list, &vmap_purge_list);
  
  	if (unlikely(nr_lazy > lazy_max_pages()))

  		try_purge_vmap_area_lazy();

  }

  /*
   * 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);

  	unmap_vmap_area(va);

  	if (debug_pagealloc_enabled())
  		flush_tlb_kernel_range(va->va_start, va->va_end);

  	free_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;
  }

  /*** 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;

  	unsigned long free, dirty;

  	unsigned long dirty_min, dirty_max; /*< dirty range */

  	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 void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
  {
  	unsigned long addr;
  
  	addr = va_start + (pages_off << PAGE_SHIFT);
  	BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
  	return (void *)addr;
  }
  
  /**
   * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
   *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
   * @order:    how many 2^order pages should be occupied in newly allocated block
   * @gfp_mask: flags for the page level allocator
   *
   * Returns: virtual address in a newly allocated block or ERR_PTR(-errno)
   */
  static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)

  {
  	struct vmap_block_queue *vbq;
  	struct vmap_block *vb;
  	struct vmap_area *va;
  	unsigned long vb_idx;
  	int node, err;

  	void *vaddr;

  
  	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);
  	}

  	vaddr = vmap_block_vaddr(va->va_start, 0);

  	spin_lock_init(&vb->lock);
  	vb->va = va;

  	/* At least something should be left free */
  	BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
  	vb->free = VMAP_BBMAP_BITS - (1UL << order);

  	vb->dirty = 0;

  	vb->dirty_min = VMAP_BBMAP_BITS;
  	vb->dirty_max = 0;

  	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);

  	spin_lock(&vbq->lock);

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

  	spin_unlock(&vbq->lock);

  	put_cpu_var(vmap_block_queue);

  	return vaddr;

  }

  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 */

  			vb->dirty_min = 0;
  			vb->dirty_max = 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_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;

  	void *vaddr = NULL;

  	unsigned int order;

  	BUG_ON(offset_in_page(size));

  	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);

  	rcu_read_lock();
  	vbq = &get_cpu_var(vmap_block_queue);
  	list_for_each_entry_rcu(vb, &vbq->free, free_list) {

  		unsigned long pages_off;

  
  		spin_lock(&vb->lock);

  		if (vb->free < (1UL << order)) {
  			spin_unlock(&vb->lock);
  			continue;
  		}

  		pages_off = VMAP_BBMAP_BITS - vb->free;
  		vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);

  		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;

  	}

  	put_cpu_var(vmap_block_queue);

  	rcu_read_unlock();

  	/* Allocate new block if nothing was found */
  	if (!vaddr)
  		vaddr = new_vmap_block(order, gfp_mask);

  	return vaddr;

  }
  
  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(offset_in_page(size));

  	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);

  	offset >>= PAGE_SHIFT;

  
  	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);

  	if (debug_pagealloc_enabled())
  		flush_tlb_kernel_range((unsigned long)addr,
  					(unsigned long)addr + size);

  	spin_lock(&vb->lock);

  
  	/* Expand dirty range */
  	vb->dirty_min = min(vb->dirty_min, offset);
  	vb->dirty_max = max(vb->dirty_max, offset + (1UL << 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;

  	might_sleep();

  	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) {

  			spin_lock(&vb->lock);

  			if (vb->dirty) {
  				unsigned long va_start = vb->va->va_start;

  				unsigned long s, e;

  				s = va_start + (vb->dirty_min << PAGE_SHIFT);
  				e = va_start + (vb->dirty_max << PAGE_SHIFT);

  				start = min(s, start);
  				end   = max(e, end);

  				flush = 1;

  			}
  			spin_unlock(&vb->lock);
  		}
  		rcu_read_unlock();
  	}

  	mutex_lock(&vmap_purge_lock);

  	purge_fragmented_blocks_allcpus();
  	if (!__purge_vmap_area_lazy(start, end) && flush)
  		flush_tlb_kernel_range(start, end);

  	mutex_unlock(&vmap_purge_lock);

  }
  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 = (unsigned long)count << PAGE_SHIFT;

  	unsigned long addr = (unsigned long)mem;

  	struct vmap_area *va;

  	might_sleep();

  	BUG_ON(!addr);
  	BUG_ON(addr < VMALLOC_START);
  	BUG_ON(addr > VMALLOC_END);

  	BUG_ON(!PAGE_ALIGNED(addr));

  	if (likely(count <= VMAP_MAX_ALLOC)) {

  		debug_check_no_locks_freed(mem, size);

  		vb_free(mem, size);

  		return;
  	}
  
  	va = find_vmap_area(addr);
  	BUG_ON(!va);

  	debug_check_no_locks_freed((void *)va->va_start,
  				    (va->va_end - va->va_start));

  	free_unmap_vmap_area(va);

  }
  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

   *

   * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
   * faster than vmap so it's good.  But if you mix long-life and short-life
   * objects with vm_map_ram(), it could consume lots of address space through
   * fragmentation (especially on a 32bit machine).  You could see failures in
   * the end.  Please use this function for short-lived objects.
   *

   * 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 = (unsigned long)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);

  static struct vm_struct *vmlist __initdata;

  /**

   * 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;

  		struct vfree_deferred *p;

  
  		vbq = &per_cpu(vmap_block_queue, i);
  		spin_lock_init(&vbq->lock);
  		INIT_LIST_HEAD(&vbq->free);

  		p = &per_cpu(vfree_deferred, i);
  		init_llist_head(&p->list);
  		INIT_WORK(&p->wq, free_work);

  	}

  	/* 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);
  }

  EXPORT_SYMBOL_GPL(unmap_kernel_range);

  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 + get_vm_area_size(area);

  	int err;

  	err = vmap_page_range(addr, end, prot, pages);

  	return err > 0 ? 0 : err;

  }
  EXPORT_SYMBOL_GPL(map_vm_area);

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

  			      unsigned long flags, const void *caller)

  {

  	spin_lock(&vmap_area_lock);

  	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;

  	spin_unlock(&vmap_area_lock);

  }

  static void clear_vm_uninitialized_flag(struct vm_struct *vm)

  {

  	/*

  	 * Before removing VM_UNINITIALIZED,

  	 * we should make sure that vm has proper values.
  	 * Pair with smp_rmb() in show_numa_info().
  	 */
  	smp_wmb();

  	vm->flags &= ~VM_UNINITIALIZED;

  }

  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());

  	size = PAGE_ALIGN(size);

  	if (unlikely(!size))
  		return NULL;

  	if (flags & VM_IOREMAP)
  		align = 1ul << clamp_t(int, get_count_order_long(size),
  				       PAGE_SHIFT, IOREMAP_MAX_ORDER);

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

  	if (unlikely(!area))
  		return NULL;

  	if (!(flags & VM_NO_GUARD))
  		size += PAGE_SIZE;

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

  	}

  	setup_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;

  	might_sleep();

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

  		struct vm_struct *vm = va->vm;

  		spin_lock(&vmap_area_lock);
  		va->vm = NULL;
  		va->flags &= ~VM_VM_AREA;

  		va->flags |= VM_LAZY_FREE;

  		spin_unlock(&vmap_area_lock);

  		kasan_free_shadow(vm);

  		free_unmap_vmap_area(va);

  		return vm;
  	}
  	return NULL;

  }

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

  {
  	struct vm_struct *area;
  
  	if (!addr)
  		return;

  	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)
  ",

  			addr))

  		return;

  	area = find_vmap_area((unsigned long)addr)->vm;

  	if (unlikely(!area)) {

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

  				addr);

  		return;
  	}

  	debug_check_no_locks_freed(area->addr, get_vm_area_size(area));
  	debug_check_no_obj_freed(area->addr, get_vm_area_size(area));

  	remove_vm_area(addr);

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

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

  			__free_pages(page, 0);

  		}

  		kvfree(area->pages);

  	}
  
  	kfree(area);
  	return;
  }

  
  static inline void __vfree_deferred(const void *addr)
  {
  	/*
  	 * Use raw_cpu_ptr() because this can be called from preemptible
  	 * context. Preemption is absolutely fine here, because the llist_add()
  	 * implementation is lockless, so it works even if we are adding to
  	 * nother cpu's list.  schedule_work() should be fine with this too.
  	 */
  	struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);
  
  	if (llist_add((struct llist_node *)addr, &p->list))
  		schedule_work(&p->wq);
  }
  
  /**
   *	vfree_atomic  -  release memory allocated by vmalloc()
   *	@addr:		memory base address
   *
   *	This one is just like vfree() but can be called in any atomic context
   *	except NMIs.
   */
  void vfree_atomic(const void *addr)
  {
  	BUG_ON(in_nmi());
  
  	kmemleak_free(addr);
  
  	if (!addr)
  		return;
  	__vfree_deferred(addr);
  }

  /**
   *	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 NMI context (strictly speaking, only if we don't
   *	have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
   *	conventions for vfree() arch-depenedent would be a really bad idea)

   *

   *	NOTE: assumes that the object at @addr has a size >= sizeof(llist_node)

   */

  void vfree(const void *addr)

  {

  	BUG_ON(in_nmi());

  
  	kmemleak_free(addr);

  	if (!addr)
  		return;

  	if (unlikely(in_interrupt()))
  		__vfree_deferred(addr);
  	else

  		__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();

  	if (addr)
  		__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;

  	unsigned long size;		/* In bytes */

  	might_sleep();

  	if (count > totalram_pages)

  		return NULL;

  	size = (unsigned long)count << PAGE_SHIFT;
  	area = get_vm_area_caller(size, 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)

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

  	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;

  	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
  	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
  					0 :
  					__GFP_HIGHMEM;

  	nr_pages = get_vm_area_size(area) >> 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|highmem_mask,

  				PAGE_KERNEL, node, area->caller);

  	} else {

  		pages = kmalloc_node(array_size, nested_gfp, node);

  	}

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

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

  		struct page *page;

  		if (node == NUMA_NO_NODE)

  			page = alloc_page(alloc_mask|highmem_mask);

  		else

  			page = alloc_pages_node(node, alloc_mask|highmem_mask, 0);

  
  		if (unlikely(!page)) {

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

  		area->pages[i] = page;

  		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))

  			cond_resched();

  	}

  	if (map_vm_area(area, prot, pages))

  		goto fail;
  	return area->addr;
  
  fail:

  	warn_alloc(gfp_mask, NULL,

  			  "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

   *	@vm_flags:	additional vm area flags (e.g. %VM_NO_GUARD)

   *	@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, unsigned long vm_flags, 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_UNINITIALIZED |
  				vm_flags, start, end, node, gfp_mask, caller);

  	if (!area)

  		goto fail;

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

  	if (!addr)

  		return NULL;

  
  	/*

  	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
  	 * flag. It means that vm_struct is not fully initialized.

  	 * Now, it is fully initialized, so remove this flag here.

  	 */

  	clear_vm_uninitialized_flag(area);

  	kmemleak_vmalloc(area, size, gfp_mask);

  
  	return addr;

  
  fail:

  	warn_alloc(gfp_mask, NULL,

  			  "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.

   *

   *	Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL

   *	and __GFP_NOFAIL are not supported
   *
   *	Any use of gfp flags outside of GFP_KERNEL should be consulted
   *	with mm people.
   *

   */

  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, 0, 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));
  }
  
  
  void *__vmalloc_node_flags_caller(unsigned long size, int node, gfp_t flags,
  				  void *caller)
  {
  	return __vmalloc_node(size, 1, flags, PAGE_KERNEL, node, caller);
  }

  /**
   *	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.
   *