1 files changed, 532 insertions, 77 deletions

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f8189a4b3e13..0f551a4a44cd 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/highmem.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
@@ -25,10 +26,10 @@
 #include <linux/rcupdate.h>
 #include <linux/pfn.h>
 #include <linux/kmemleak.h>
-
 #include <asm/atomic.h>
 #include <asm/uaccess.h>
 #include <asm/tlbflush.h>
+#include <asm/shmparam.h>
 
 
 /*** Page table manipulation functions ***/
@@ -168,11 +169,9 @@ static int vmap_page_range_noflush(unsigned long start, unsigned long end,
                 next = pgd_addr_end(addr, end);
                 err = vmap_pud_range(pgd, addr, next, prot, pages, &nr);
                 if (err)
-                        break;
+                        return err;
         } while (pgd++, addr = next, addr != end);
 
-        if (unlikely(err))
-                return err;
         return nr;
 }
 
@@ -186,7 +185,7 @@ static int vmap_page_range(unsigned long start, unsigned long end,
         return ret;
 }
 
-static inline int is_vmalloc_or_module_addr(const void *x)
+int is_vmalloc_or_module_addr(const void *x)
 {
         /*
          * ARM, x86-64 and sparc64 put modules in a special place,
@@ -265,6 +264,7 @@ struct vmap_area {
 static DEFINE_SPINLOCK(vmap_area_lock);
 static struct rb_root vmap_area_root = RB_ROOT;
 static LIST_HEAD(vmap_area_list);
+static unsigned long vmap_area_pcpu_hole;
 
 static struct vmap_area *__find_vmap_area(unsigned long addr)
 {
@@ -431,6 +431,15 @@ static void __free_vmap_area(struct vmap_area *va)
         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);
+
         call_rcu(&va->rcu_head, rcu_free_va);
 }
 
@@ -1038,6 +1047,9 @@ void __init vmalloc_init(void)
                 va->va_end = va->va_start + tmp->size;
                 __insert_vmap_area(va);
         }
+
+        vmap_area_pcpu_hole = VMALLOC_END;
+
         vmap_initialized = true;
 }
 
@@ -1122,14 +1134,34 @@ EXPORT_SYMBOL_GPL(map_vm_area);
 DEFINE_RWLOCK(vmlist_lock);
 struct vm_struct *vmlist;
 
+static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
+                              unsigned long flags, void *caller)
+{
+        struct vm_struct *tmp, **p;
+
+        vm->flags = flags;
+        vm->addr = (void *)va->va_start;
+        vm->size = va->va_end - va->va_start;
+        vm->caller = caller;
+        va->private = vm;
+        va->flags |= VM_VM_AREA;
+
+        write_lock(&vmlist_lock);
+        for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
+                if (tmp->addr >= vm->addr)
+                        break;
+        }
+        vm->next = *p;
+        *p = vm;
+        write_unlock(&vmlist_lock);
+}
+
 static 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)
+                unsigned long align, 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) {
@@ -1147,7 +1179,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
         if (unlikely(!size))
                 return NULL;
 
-        area = kmalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
+        area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
         if (unlikely(!area))
                 return NULL;
 
@@ -1162,32 +1194,14 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
                 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);
-
+        insert_vmalloc_vm(area, va, flags, caller);
         return area;
 }
 
 struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
                                 unsigned long start, unsigned long end)
 {
-        return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL,
+        return __get_vm_area_node(size, 1, flags, start, end, -1, GFP_KERNEL,
                                                 __builtin_return_address(0));
 }
 EXPORT_SYMBOL_GPL(__get_vm_area);
@@ -1196,7 +1210,7 @@ struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
                                        unsigned long start, unsigned long end,
                                        void *caller)
 {
-        return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL,
+        return __get_vm_area_node(size, 1, flags, start, end, -1, GFP_KERNEL,
                                   caller);
 }
 
@@ -1211,22 +1225,22 @@ struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
  */
 struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
 {
-        return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END,
+        return __get_vm_area_node(size, 1, 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,
+        return __get_vm_area_node(size, 1, 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));
+        return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
+                                  node, gfp_mask, __builtin_return_address(0));
 }
 
 static struct vm_struct *find_vm_area(const void *addr)
@@ -1256,17 +1270,21 @@ struct vm_struct *remove_vm_area(const void *addr)
         if (va && va->flags & VM_VM_AREA) {
                 struct vm_struct *vm = va->private;
                 struct vm_struct *tmp, **p;
-
-                vmap_debug_free_range(va->va_start, va->va_end);
-                free_unmap_vmap_area(va);
-                vm->size -= PAGE_SIZE;
-
+                /*
+                 * remove from list and disallow access to this vm_struct
+                 * before unmap. (address range confliction is maintained by
+                 * vmap.)
+                 */
                 write_lock(&vmlist_lock);
                 for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next)
                         ;
                 *p = tmp->next;
                 write_unlock(&vmlist_lock);
 
+                vmap_debug_free_range(va->va_start, va->va_end);
+                free_unmap_vmap_area(va);
+                vm->size -= PAGE_SIZE;
+
                 return vm;
         }
         return NULL;
@@ -1368,7 +1386,7 @@ void *vmap(struct page **pages, unsigned int count,
 
         might_sleep();
 
-        if (count > num_physpages)
+        if (count > totalram_pages)
                 return NULL;
 
         area = get_vm_area_caller((count << PAGE_SHIFT), flags,
@@ -1385,7 +1403,8 @@ void *vmap(struct page **pages, unsigned int count,
 }
 EXPORT_SYMBOL(vmap);
 
-static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+                            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)
@@ -1399,7 +1418,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
         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,
+                pages = __vmalloc_node(array_size, 1, gfp_mask | __GFP_ZERO,
                                 PAGE_KERNEL, node, caller);
                 area->flags |= VM_VPAGES;
         } else {
@@ -1458,6 +1477,7 @@ void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
 /**
  *      __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 -1
@@ -1467,19 +1487,20 @@ void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
  *      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)
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+                            gfp_t gfp_mask, pgprot_t prot,
+                            int node, void *caller)
 {
         struct vm_struct *area;
         void *addr;
         unsigned long real_size = size;
 
         size = PAGE_ALIGN(size);
-        if (!size || (size >> PAGE_SHIFT) > num_physpages)
+        if (!size || (size >> PAGE_SHIFT) > totalram_pages)
                 return NULL;
 
-        area = __get_vm_area_node(size, VM_ALLOC, VMALLOC_START, VMALLOC_END,
-                                                node, gfp_mask, caller);
+        area = __get_vm_area_node(size, align, VM_ALLOC, VMALLOC_START,
+                                  VMALLOC_END, node, gfp_mask, caller);
 
         if (!area)
                 return NULL;
@@ -1498,7 +1519,7 @@ static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
 
 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 {
-        return __vmalloc_node(size, gfp_mask, prot, -1,
+        return __vmalloc_node(size, 1, gfp_mask, prot, -1,
                                 __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__vmalloc);
@@ -1514,7 +1535,7 @@ EXPORT_SYMBOL(__vmalloc);
  */
 void *vmalloc(unsigned long size)
 {
-        return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
+        return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
                                         -1, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(vmalloc);
@@ -1531,7 +1552,8 @@ void *vmalloc_user(unsigned long size)
         struct vm_struct *area;
         void *ret;
 
-        ret = __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+        ret = __vmalloc_node(size, SHMLBA,
+                             GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
                              PAGE_KERNEL, -1, __builtin_return_address(0));
         if (ret) {
                 area = find_vm_area(ret);
@@ -1554,7 +1576,7 @@ EXPORT_SYMBOL(vmalloc_user);
  */
 void *vmalloc_node(unsigned long size, int node)
 {
-        return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
+        return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
                                         node, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(vmalloc_node);
@@ -1577,7 +1599,7 @@ EXPORT_SYMBOL(vmalloc_node);
 
 void *vmalloc_exec(unsigned long size)
 {
-        return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
+        return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
                               -1, __builtin_return_address(0));
 }
 
@@ -1598,7 +1620,7 @@ void *vmalloc_exec(unsigned long size)
  */
 void *vmalloc_32(unsigned long size)
 {
-        return __vmalloc_node(size, GFP_VMALLOC32, PAGE_KERNEL,
+        return __vmalloc_node(size, 1, GFP_VMALLOC32, PAGE_KERNEL,
                               -1, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(vmalloc_32);
@@ -1615,7 +1637,7 @@ void *vmalloc_32_user(unsigned long size)
         struct vm_struct *area;
         void *ret;
 
-        ret = __vmalloc_node(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
+        ret = __vmalloc_node(size, 1, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
                              -1, __builtin_return_address(0));
         if (ret) {
                 area = find_vm_area(ret);
@@ -1625,10 +1647,120 @@ void *vmalloc_32_user(unsigned long size)
 }
 EXPORT_SYMBOL(vmalloc_32_user);
 
+/*
+ * small helper routine , copy contents to buf from addr.
+ * If the page is not present, fill zero.
+ */
+
+static int aligned_vread(char *buf, char *addr, unsigned long count)
+{
+        struct page *p;
+        int copied = 0;
+
+        while (count) {
+                unsigned long offset, length;
+
+                offset = (unsigned long)addr & ~PAGE_MASK;
+                length = PAGE_SIZE - offset;
+                if (length > count)
+                        length = count;
+                p = vmalloc_to_page(addr);
+                /*
+                 * To do safe access to this _mapped_ area, we need
+                 * lock. But adding lock here means that we need to add
+                 * overhead of vmalloc()/vfree() calles for this _debug_
+                 * interface, rarely used. Instead of that, we'll use
+                 * kmap() and get small overhead in this access function.
+                 */
+                if (p) {
+                        /*
+                         * we can expect USER0 is not used (see vread/vwrite's
+                         * function description)
+                         */
+                        void *map = kmap_atomic(p, KM_USER0);
+                        memcpy(buf, map + offset, length);
+                        kunmap_atomic(map, KM_USER0);
+                } else
+                        memset(buf, 0, length);
+
+                addr += length;
+                buf += length;
+                copied += length;
+                count -= length;
+        }
+        return copied;
+}
+
+static int aligned_vwrite(char *buf, char *addr, unsigned long count)
+{
+        struct page *p;
+        int copied = 0;
+
+        while (count) {
+                unsigned long offset, length;
+
+                offset = (unsigned long)addr & ~PAGE_MASK;
+                length = PAGE_SIZE - offset;
+                if (length > count)
+                        length = count;
+                p = vmalloc_to_page(addr);
+                /*
+                 * To do safe access to this _mapped_ area, we need
+                 * lock. But adding lock here means that we need to add
+                 * overhead of vmalloc()/vfree() calles for this _debug_
+                 * interface, rarely used. Instead of that, we'll use
+                 * kmap() and get small overhead in this access function.
+                 */
+                if (p) {
+                        /*
+                         * we can expect USER0 is not used (see vread/vwrite's
+                         * function description)
+                         */
+                        void *map = kmap_atomic(p, KM_USER0);
+                        memcpy(map + offset, buf, length);
+                        kunmap_atomic(map, KM_USER0);
+                }
+                addr += length;
+                buf += length;
+                copied += length;
+                count -= length;
+        }
+        return copied;
+}
+
+/**
+ *      vread() -  read vmalloc area in a safe way.
+ *      @buf:           buffer for reading data
+ *      @addr:          vm address.
+ *      @count:         number of bytes to be read.
+ *
+ *      Returns # of bytes which addr and buf should be increased.
+ *      (same number to @count). Returns 0 if [addr...addr+count) doesn't
+ *      includes any intersect with alive vmalloc area.
+ *
+ *      This function checks that addr is a valid vmalloc'ed area, and
+ *      copy data from that area to a given buffer. If the given memory range
+ *      of [addr...addr+count) includes some valid address, data is copied to
+ *      proper area of @buf. If there are memory holes, they'll be zero-filled.
+ *      IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *      If [addr...addr+count) doesn't includes any intersects with alive
+ *      vm_struct area, returns 0.
+ *      @buf should be kernel's buffer. Because this function uses KM_USER0,
+ *      the caller should guarantee KM_USER0 is not used.
+ *
+ *      Note: In usual ops, vread() is never necessary because the caller
+ *      should know vmalloc() area is valid and can use memcpy().
+ *      This is for routines which have to access vmalloc area without
+ *      any informaion, as /dev/kmem.
+ *
+ */
+
 long vread(char *buf, char *addr, unsigned long count)
 {
         struct vm_struct *tmp;
         char *vaddr, *buf_start = buf;
+        unsigned long buflen = count;
         unsigned long n;
 
         /* Don't allow overflow */
@@ -1636,7 +1768,7 @@ long vread(char *buf, char *addr, unsigned long count)
                 count = -(unsigned long) addr;
 
         read_lock(&vmlist_lock);
-        for (tmp = vmlist; tmp; tmp = tmp->next) {
+        for (tmp = vmlist; count && tmp; tmp = tmp->next) {
                 vaddr = (char *) tmp->addr;
                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
                         continue;
@@ -1649,32 +1781,72 @@ long vread(char *buf, char *addr, unsigned long count)
                         count--;
                 }
                 n = vaddr + tmp->size - PAGE_SIZE - addr;
-                do {
-                        if (count == 0)
-                                goto finished;
-                        *buf = *addr;
-                        buf++;
-                        addr++;
-                        count--;
-                } while (--n > 0);
+                if (n > count)
+                        n = count;
+                if (!(tmp->flags & VM_IOREMAP))
+                        aligned_vread(buf, addr, n);
+                else /* IOREMAP area is treated as memory hole */
+                        memset(buf, 0, n);
+                buf += n;
+                addr += n;
+                count -= n;
         }
 finished:
         read_unlock(&vmlist_lock);
-        return buf - buf_start;
+
+        if (buf == buf_start)
+                return 0;
+        /* zero-fill memory holes */
+        if (buf != buf_start + buflen)
+                memset(buf, 0, buflen - (buf - buf_start));
+
+        return buflen;
 }
 
+/**
+ *      vwrite() -  write vmalloc area in a safe way.
+ *      @buf:           buffer for source data
+ *      @addr:          vm address.
+ *      @count:         number of bytes to be read.
+ *
+ *      Returns # of bytes which addr and buf should be incresed.
+ *      (same number to @count).
+ *      If [addr...addr+count) doesn't includes any intersect with valid
+ *      vmalloc area, returns 0.
+ *
+ *      This function checks that addr is a valid vmalloc'ed area, and
+ *      copy data from a buffer to the given addr. If specified range of
+ *      [addr...addr+count) includes some valid address, data is copied from
+ *      proper area of @buf. If there are memory holes, no copy to hole.
+ *      IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *      If [addr...addr+count) doesn't includes any intersects with alive
+ *      vm_struct area, returns 0.
+ *      @buf should be kernel's buffer. Because this function uses KM_USER0,
+ *      the caller should guarantee KM_USER0 is not used.
+ *
+ *      Note: In usual ops, vwrite() is never necessary because the caller
+ *      should know vmalloc() area is valid and can use memcpy().
+ *      This is for routines which have to access vmalloc area without
+ *      any informaion, as /dev/kmem.
+ *
+ *      The caller should guarantee KM_USER1 is not used.
+ */
+
 long vwrite(char *buf, char *addr, unsigned long count)
 {
         struct vm_struct *tmp;
-        char *vaddr, *buf_start = buf;
-        unsigned long n;
+        char *vaddr;
+        unsigned long n, buflen;
+        int copied = 0;
 
         /* Don't allow overflow */
         if ((unsigned long) addr + count < count)
                 count = -(unsigned long) addr;
+        buflen = count;
 
         read_lock(&vmlist_lock);
-        for (tmp = vmlist; tmp; tmp = tmp->next) {
+        for (tmp = vmlist; count && tmp; tmp = tmp->next) {
                 vaddr = (char *) tmp->addr;
                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
                         continue;
@@ -1686,18 +1858,21 @@ long vwrite(char *buf, char *addr, unsigned long count)
                         count--;
                 }
                 n = vaddr + tmp->size - PAGE_SIZE - addr;
-                do {
-                        if (count == 0)
-                                goto finished;
-                        *addr = *buf;
-                        buf++;
-                        addr++;
-                        count--;
-                } while (--n > 0);
+                if (n > count)
+                        n = count;
+                if (!(tmp->flags & VM_IOREMAP)) {
+                        aligned_vwrite(buf, addr, n);
+                        copied++;
+                }
+                buf += n;
+                addr += n;
+                count -= n;
         }
 finished:
         read_unlock(&vmlist_lock);
-        return buf - buf_start;
+        if (!copied)
+                return 0;
+        return buflen;
 }
 
 /**
@@ -1818,6 +1993,286 @@ void free_vm_area(struct vm_struct *area)
 }
 EXPORT_SYMBOL_GPL(free_vm_area);
 
+static struct vmap_area *node_to_va(struct rb_node *n)
+{
+        return n ? rb_entry(n, struct vmap_area, rb_node) : NULL;
+}
+
+/**
+ * pvm_find_next_prev - find the next and prev vmap_area surrounding @end
+ * @end: target address
+ * @pnext: out arg for the next vmap_area
+ * @pprev: out arg for the previous vmap_area
+ *
+ * Returns: %true if either or both of next and prev are found,
+ *          %false if no vmap_area exists
+ *
+ * Find vmap_areas end addresses of which enclose @end.  ie. if not
+ * NULL, *pnext->va_end > @end and *pprev->va_end <= @end.
+ */
+static bool pvm_find_next_prev(unsigned long end,
+                               struct vmap_area **pnext,
+                               struct vmap_area **pprev)
+{
+        struct rb_node *n = vmap_area_root.rb_node;
+        struct vmap_area *va = NULL;
+
+        while (n) {
+                va = rb_entry(n, struct vmap_area, rb_node);
+                if (end < va->va_end)
+                        n = n->rb_left;
+                else if (end > va->va_end)
+                        n = n->rb_right;
+                else
+                        break;
+        }
+
+        if (!va)
+                return false;
+
+        if (va->va_end > end) {
+                *pnext = va;
+                *pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+        } else {
+                *pprev = va;
+                *pnext = node_to_va(rb_next(&(*pprev)->rb_node));
+        }
+        return true;
+}
+
+/**
+ * pvm_determine_end - find the highest aligned address between two vmap_areas
+ * @pnext: in/out arg for the next vmap_area
+ * @pprev: in/out arg for the previous vmap_area
+ * @align: alignment
+ *
+ * Returns: determined end address
+ *
+ * Find the highest aligned address between *@pnext and *@pprev below
+ * VMALLOC_END.  *@pnext and *@pprev are adjusted so that the aligned
+ * down address is between the end addresses of the two vmap_areas.
+ *
+ * Please note that the address returned by this function may fall
+ * inside *@pnext vmap_area.  The caller is responsible for checking
+ * that.
+ */
+static unsigned long pvm_determine_end(struct vmap_area **pnext,
+                                       struct vmap_area **pprev,
+                                       unsigned long align)
+{
+        const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+        unsigned long addr;
+
+        if (*pnext)
+                addr = min((*pnext)->va_start & ~(align - 1), vmalloc_end);
+        else
+                addr = vmalloc_end;
+
+        while (*pprev && (*pprev)->va_end > addr) {
+                *pnext = *pprev;
+                *pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+        }
+
+        return addr;
+}
+
+/**
+ * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
+ * @offsets: array containing offset of each area
+ * @sizes: array containing size of each area
+ * @nr_vms: the number of areas to allocate
+ * @align: alignment, all entries in @offsets and @sizes must be aligned to this
+ * @gfp_mask: allocation mask
+ *
+ * Returns: kmalloc'd vm_struct pointer array pointing to allocated
+ *          vm_structs on success, %NULL on failure
+ *
+ * Percpu allocator wants to use congruent vm areas so that it can
+ * maintain the offsets among percpu areas.  This function allocates
+ * congruent vmalloc areas for it.  These areas tend to be scattered
+ * pretty far, distance between two areas easily going up to
+ * gigabytes.  To avoid interacting with regular vmallocs, these areas
+ * are allocated from top.
+ *
+ * Despite its complicated look, this allocator is rather simple.  It
+ * does everything top-down and scans areas from the end looking for
+ * matching slot.  While scanning, if any of the areas overlaps with
+ * existing vmap_area, the base address is pulled down to fit the
+ * area.  Scanning is repeated till all the areas fit and then all
+ * necessary data structres are inserted and the result is returned.
+ */
+struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
+                                     const size_t *sizes, int nr_vms,
+                                     size_t align, gfp_t gfp_mask)
+{
+        const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
+        const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+        struct vmap_area **vas, *prev, *next;
+        struct vm_struct **vms;
+        int area, area2, last_area, term_area;
+        unsigned long base, start, end, last_end;
+        bool purged = false;
+
+        gfp_mask &= GFP_RECLAIM_MASK;
+
+        /* verify parameters and allocate data structures */
+        BUG_ON(align & ~PAGE_MASK || !is_power_of_2(align));
+        for (last_area = 0, area = 0; area < nr_vms; area++) {
+                start = offsets[area];
+                end = start + sizes[area];
+
+                /* is everything aligned properly? */
+                BUG_ON(!IS_ALIGNED(offsets[area], align));
+                BUG_ON(!IS_ALIGNED(sizes[area], align));
+
+                /* detect the area with the highest address */
+                if (start > offsets[last_area])
+                        last_area = area;
+
+                for (area2 = 0; area2 < nr_vms; area2++) {
+                        unsigned long start2 = offsets[area2];
+                        unsigned long end2 = start2 + sizes[area2];
+
+                        if (area2 == area)
+                                continue;
+
+                        BUG_ON(start2 >= start && start2 < end);
+                        BUG_ON(end2 <= end && end2 > start);
+                }
+        }
+        last_end = offsets[last_area] + sizes[last_area];
+
+        if (vmalloc_end - vmalloc_start < last_end) {
+                WARN_ON(true);
+                return NULL;
+        }
+
+        vms = kzalloc(sizeof(vms[0]) * nr_vms, gfp_mask);
+        vas = kzalloc(sizeof(vas[0]) * nr_vms, gfp_mask);
+        if (!vas || !vms)
+                goto err_free;
+
+        for (area = 0; area < nr_vms; area++) {
+                vas[area] = kzalloc(sizeof(struct vmap_area), gfp_mask);
+                vms[area] = kzalloc(sizeof(struct vm_struct), gfp_mask);
+                if (!vas[area] || !vms[area])
+                        goto err_free;
+        }
+retry:
+        spin_lock(&vmap_area_lock);
+
+        /* start scanning - we scan from the top, begin with the last area */
+        area = term_area = last_area;
+        start = offsets[area];
+        end = start + sizes[area];
+
+        if (!pvm_find_next_prev(vmap_area_pcpu_hole, &next, &prev)) {
+                base = vmalloc_end - last_end;
+                goto found;
+        }
+        base = pvm_determine_end(&next, &prev, align) - end;
+
+        while (true) {
+                BUG_ON(next && next->va_end <= base + end);
+                BUG_ON(prev && prev->va_end > base + end);
+
+                /*
+                 * base might have underflowed, add last_end before
+                 * comparing.
+                 */
+                if (base + last_end < vmalloc_start + last_end) {
+                        spin_unlock(&vmap_area_lock);
+                        if (!purged) {
+                                purge_vmap_area_lazy();
+                                purged = true;
+                                goto retry;
+                        }
+                        goto err_free;
+                }
+
+                /*
+                 * If next overlaps, move base downwards so that it's
+                 * right below next and then recheck.
+                 */
+                if (next && next->va_start < base + end) {
+                        base = pvm_determine_end(&next, &prev, align) - end;
+                        term_area = area;
+                        continue;
+                }
+
+                /*
+                 * If prev overlaps, shift down next and prev and move
+                 * base so that it's right below new next and then
+                 * recheck.
+                 */
+                if (prev && prev->va_end > base + start)  {
+                        next = prev;
+                        prev = node_to_va(rb_prev(&next->rb_node));
+                        base = pvm_determine_end(&next, &prev, align) - end;
+                        term_area = area;
+                        continue;
+                }
+
+                /*
+                 * This area fits, move on to the previous one.  If
+                 * the previous one is the terminal one, we're done.
+                 */
+                area = (area + nr_vms - 1) % nr_vms;
+                if (area == term_area)
+                        break;
+                start = offsets[area];
+                end = start + sizes[area];
+                pvm_find_next_prev(base + end, &next, &prev);
+        }
+found:
+        /* we've found a fitting base, insert all va's */
+        for (area = 0; area < nr_vms; area++) {
+                struct vmap_area *va = vas[area];
+
+                va->va_start = base + offsets[area];
+                va->va_end = va->va_start + sizes[area];
+                __insert_vmap_area(va);
+        }
+
+        vmap_area_pcpu_hole = base + offsets[last_area];
+
+        spin_unlock(&vmap_area_lock);
+
+        /* insert all vm's */
+        for (area = 0; area < nr_vms; area++)
+                insert_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
+                                  pcpu_get_vm_areas);
+
+        kfree(vas);
+        return vms;
+
+err_free:
+        for (area = 0; area < nr_vms; area++) {
+                if (vas)
+                        kfree(vas[area]);
+                if (vms)
+                        kfree(vms[area]);
+        }
+        kfree(vas);
+        kfree(vms);
+        return NULL;
+}
+
+/**
+ * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
+ * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
+ * @nr_vms: the number of allocated areas
+ *
+ * Free vm_structs and the array allocated by pcpu_get_vm_areas().
+ */
+void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
+{
+        int i;
+
+        for (i = 0; i < nr_vms; i++)
+                free_vm_area(vms[i]);
+        kfree(vms);
+}
 
 #ifdef CONFIG_PROC_FS
 static void *s_start(struct seq_file *m, loff_t *pos)