ClabureDB: Classified Bug-Reports Database

   /*
    *  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/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 <asm/atomic.h>
  #include <asm/uaccess.h>
  #include <asm/tlbflush.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(unsigned long addr, unsigned long end,
                                 pgprot_t prot, struct page **pages)
 {
         pgd_t *pgd;
         unsigned long next;
         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)
                         break;
         } while (pgd++, addr = next, addr != end);
         flush_cache_vmap(addr, end);
 
         if (unlikely(err))
                 return err;
         return nr;
 }
 
 static inline 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 */
         void *private;
         struct rcu_head rcu_head;
 };
 
 static DEFINE_SPINLOCK(vmap_area_lock);
 static struct rb_root vmap_area_root = RB_ROOT;
 static LIST_HEAD(vmap_area_list);
 
 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;
 
                 parent = *p;
                 tmp = rb_entry(parent, struct vmap_area, rb_node);
                 if (va->va_start < tmp->va_end)
                         p = &(*p)->rb_left;
                 else if (va->va_end > tmp->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;
 
         BUG_ON(size & ~PAGE_MASK);
 
         va = kmalloc_node(sizeof(struct vmap_area),
                         gfp_mask & GFP_RECLAIM_MASK, node);
         if (unlikely(!va))
                 return ERR_PTR(-ENOMEM);
 
 retry:
         addr = ALIGN(vstart, align);
 
         spin_lock(&vmap_area_lock);
         /* XXX: could have a last_hole cache */
         n = vmap_area_root.rb_node;
         if (n) {
                 struct vmap_area *first = NULL;
 
                 do {
                         struct vmap_area *tmp;
                         tmp = rb_entry(n, struct vmap_area, rb_node);
                         if (tmp->va_end >= addr) {
                                 if (!first && tmp->va_start < addr + size)
                                         first = tmp;
                                 n = n->rb_left;
                         } else {
                                 first = tmp;
                                 n = n->rb_right;
                         }
                 } while (n);
 
                 if (!first)
                         goto found;
 
                 if (first->va_end < addr) {
                         n = rb_next(&first->rb_node);
                         if (n)
                                 first = rb_entry(n, struct vmap_area, rb_node);
                         else
                                 goto found;
                 }
 
                 while (addr + size > first->va_start && addr + size <= vend) {
                         addr = ALIGN(first->va_end + PAGE_SIZE, align);
 
                         n = rb_next(&first->rb_node);
                         if (n)
                                 first = rb_entry(n, struct vmap_area, rb_node);
                         else
                                 goto found;
                 }
         }
 found:
         if (addr + size > vend) {
                 spin_unlock(&vmap_area_lock);
                 if (!purged) {
                         purge_vmap_area_lazy();
                         purged = 1;
                         goto retry;
                 }
                 if (printk_ratelimit())
                         printk(KERN_WARNING "vmap allocation failed: "
                                  "use vmalloc=<size> to increase size.\n");
                 return ERR_PTR(-EBUSY);
         }
 
         BUG_ON(addr & (align-1));
 
         va->va_start = addr;
         va->va_end = addr + size;
         va->flags = 0;
         __insert_vmap_area(va);
         spin_unlock(&vmap_area_lock);
 
         return va;
 }
 
 static void rcu_free_va(struct rcu_head *head)
 {
         struct vmap_area *va = container_of(head, struct vmap_area, rcu_head);
 
         kfree(va);
 }
 
 static void __free_vmap_area(struct vmap_area *va)
 {
         BUG_ON(RB_EMPTY_NODE(&va->rb_node));
         rb_erase(&va->rb_node, &vmap_area_root);
         RB_CLEAR_NODE(&va->rb_node);
         list_del_rcu(&va->list);
 
         call_rcu(&va->rcu_head, rcu_free_va);
 }
 
 /*
  * 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);
 
 /*
  * 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;
         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);
 
         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;
                         unmap_vmap_area(va);
                         list_add_tail(&va->purge_list, &valist);
                         va->flags |= VM_LAZY_FREEING;
                         va->flags &= ~VM_LAZY_FREE;
                 }
         }
         rcu_read_unlock();
 
         if (nr) {
                 BUG_ON(nr > atomic_read(&vmap_lazy_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(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 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)
 {
         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
  */
 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 / 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 list_head dirty;
         unsigned int nr_dirty;
 };
 
 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);
         union {
                 struct {
                         struct list_head free_list;
                         struct list_head dirty_list;
                 };
                 struct rcu_head rcu_head;
         };
 };
 
 /* 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 (unlikely(IS_ERR(va))) {
                 kfree(vb);
                 return ERR_PTR(PTR_ERR(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);
         INIT_LIST_HEAD(&vb->dirty_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(&vb->free_list, &vbq->free);
         spin_unlock(&vbq->lock);
         put_cpu_var(vmap_cpu_blocks);
 
         return vb;
 }
 
 static void rcu_free_vb(struct rcu_head *head)
 {
         struct vmap_block *vb = container_of(head, struct vmap_block, rcu_head);
 
         kfree(vb);
 }
 
 static void free_vmap_block(struct vmap_block *vb)
 {
         struct vmap_block *tmp;
         unsigned long vb_idx;
 
         spin_lock(&vb->vbq->lock);
         if (!list_empty(&vb->free_list))
                 list_del(&vb->free_list);
         if (!list_empty(&vb->dirty_list))
                 list_del(&vb->dirty_list);
         spin_unlock(&vb->vbq->lock);
 
         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_unmap_vmap_area_noflush(vb->va);
         call_rcu(&vb->rcu_head, rcu_free_vb);
 }
 
 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;
 
         BUG_ON(size & ~PAGE_MASK);
         BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
         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);
                 i = bitmap_find_free_region(vb->alloc_map,
                                                 VMAP_BBMAP_BITS, order);
 
                 if (i >= 0) {
                         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_init(&vb->free_list);
                                 spin_unlock(&vbq->lock);
                         }
                         spin_unlock(&vb->lock);
                         break;
                 }
                 spin_unlock(&vb->lock);
         }
         put_cpu_var(vmap_cpu_blocks);
         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);
 
         spin_lock(&vb->lock);
         bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order);
         if (!vb->dirty) {
                 spin_lock(&vb->vbq->lock);
                 list_add(&vb->dirty_list, &vb->vbq->dirty);
                 spin_unlock(&vb->vbq->lock);
         }
         vb->dirty += 1UL << order;
         if (vb->dirty == VMAP_BBMAP_BITS) {
                 BUG_ON(vb->free || !list_empty(&vb->free_list));
                 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);
                                 vunmap_page_range(s, e);
                                 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);
 
         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);
 
 void __init vmalloc_init(void)
 {
         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);
                 INIT_LIST_HEAD(&vbq->dirty);
                 vbq->nr_dirty = 0;
         }
 
         vmap_initialized = true;
 }
 
 void unmap_kernel_range(unsigned long addr, unsigned long size)
 {
         unsigned long end = addr + size;
         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 struct vm_struct *__get_vm_area_node(unsigned long size,
                unsigned long flags, unsigned long start, unsigned long end,
                int node, gfp_t gfp_mask, void *caller)
{
        static struct vmap_area *va;
        struct vm_struct *area;
        struct vm_struct *tmp, **p;
        unsigned long align = 1;

        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 = kmalloc_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;
        }

        area->flags = flags;
        area->addr = (void *)va->va_start;
        area->size = size;
        area->pages = NULL;
        area->nr_pages = 0;
        area->phys_addr = 0;
        area->caller = caller;
        va->private = area;
        va->flags |= VM_VM_AREA;

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

        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, flags, start, end, -1, GFP_KERNEL,
                                                __builtin_return_address(0));
}
EXPORT_SYMBOL_GPL(__get_vm_area);

/**
 *        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, flags, VMALLOC_START, VMALLOC_END,
                                -1, GFP_KERNEL, __builtin_return_address(0));
}

struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
                                void *caller)
{
        return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END,
                                                -1, GFP_KERNEL, caller);
}

struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags,
                                   int node, gfp_t gfp_mask)
{
        return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
                                  gfp_mask, __builtin_return_address(0));
}

static 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->private;

        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->private;
                struct vm_struct *tmp, **p;
                free_unmap_vmap_area(va);
                vm->size -= PAGE_SIZE;

                write_lock(&vmlist_lock);
                for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next)
                        ;
                *p = tmp->next;
                write_unlock(&vmlist_lock);

                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)\n", addr);
                return;
        }

        area = remove_vm_area(addr);
        if (unlikely(!area)) {
                WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
                                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());
        __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());
        __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;

        if (count > num_physpages)
                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, gfp_t gfp_mask, pgprot_t prot,
                            int node, void *caller);
static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
                                 pgprot_t prot, int node, void *caller)
{
        struct page **pages;
        unsigned int nr_pages, array_size, i;

        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, gfp_mask | __GFP_ZERO,
                                PAGE_KERNEL, node, caller);
                area->flags |= VM_VPAGES;
        } else {
                pages = kmalloc_node(array_size,
                                (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO,
                                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;

                if (node < 0)
                        page = alloc_page(gfp_mask);
                else
                        page = alloc_pages_node(node, gfp_mask, 0);

                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:
        vfree(area->addr);
        return NULL;
}

void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
{
        return __vmalloc_area_node(area, gfp_mask, prot, -1,
                                        __builtin_return_address(0));
}

/**
 *        __vmalloc_node  -  allocate virtually contiguous memory
 *        @size:                allocation size
 *        @gfp_mask:        flags for the page level allocator
 *        @prot:                protection mask for the allocated pages
 *        @node:                node to use for allocation or -1
 *        @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, gfp_t gfp_mask, pgprot_t prot,
                                                int node, void *caller)
{
        struct vm_struct *area;

        size = PAGE_ALIGN(size);
        if (!size || (size >> PAGE_SHIFT) > num_physpages)
                return NULL;

        area = __get_vm_area_node(size, VM_ALLOC, VMALLOC_START, VMALLOC_END,
                                                node, gfp_mask, caller);

        if (!area)
                return NULL;

        return __vmalloc_area_node(area, gfp_mask, prot, node, caller);
}

void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
{
        return __vmalloc_node(size, gfp_mask, prot, -1,
                                __builtin_return_address(0));
}
EXPORT_SYMBOL(__vmalloc);

/**
 *        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(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
                                        -1, __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc);

/**
 * 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(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
        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, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
                                        node, __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc_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(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
}

#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(size, GFP_VMALLOC32, PAGE_KERNEL);
}
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(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL);
        if (ret) {
                area = find_vm_area(ret);
                area->flags |= VM_USERMAP;
        }
        return ret;
}
EXPORT_SYMBOL(vmalloc_32_user);

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

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

        read_lock(&vmlist_lock);
        for (tmp = vmlist; 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;
                do {
                        if (count == 0)
                                goto finished;
                        *buf = *addr;
                        buf++;
                        addr++;
                        count--;
                } while (--n > 0);
        }
finished:
        read_unlock(&vmlist_lock);
        return buf - buf_start;
}

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

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

        read_lock(&vmlist_lock);
        for (tmp = vmlist; 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;
                do {
                        if (count == 0)
                                goto finished;
                        *addr = *buf;
                        buf++;
                        addr++;
                        count--;
                } while (--n > 0);
        }
finished:
        read_unlock(&vmlist_lock);
        return buf - buf_start;
}

/**
 *        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);

        /* Prevent "things" like memory migration? VM_flags need a cleanup... */
        vma->vm_flags |= VM_RESERVED;

        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)
{
        /* apply_to_page_range() does all the hard work. */
        return 0;
}

/**
 *        alloc_vm_area - allocate a range of kernel address space
 *        @size:                size of the area
 *
 *        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 the kernel address space is not shared
 *        between processes, it syncs the pagetable across all
 *        processes.
 */
struct vm_struct *alloc_vm_area(size_t size)
{
        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,
                                area->size, f, NULL)) {
                free_vm_area(area);
                return NULL;
        }

        /* Make sure the pagetables are constructed in process kernel
           mappings */
        vmalloc_sync_all();

        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_PROC_FS
static void *s_start(struct seq_file *m, loff_t *pos)
{
        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)
{
        read_unlock(&vmlist_lock);
}

static void show_numa_info(struct seq_file *m, struct vm_struct *v)
{
        if (NUMA_BUILD) {
                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%p-0x%p %7ld",
                v->addr, v->addr + v->size, v->size);

        if (v->caller) {
                char buff[KSYM_SYMBOL_LEN];

                seq_putc(m, ' ');
                sprint_symbol(buff, (unsigned long)v->caller);
                seq_puts(m, buff);
        }

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

        if (v->phys_addr)
                seq_printf(m, " phys=%lx", 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, '\n');
        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 (NUMA_BUILD)
                ptr = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);
        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