2 files changed, 77 insertions, 2 deletions

diff --git a/mm/util.c b/mm/util.c
index 78f3783bdcc8..bf340d806868 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -6,7 +6,6 @@
 
 /**
  * kstrdup - allocate space for and copy an existing string
- *
  * @s: the string to duplicate
  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
  */
@@ -27,6 +26,30 @@ char *kstrdup(const char *s, gfp_t gfp)
 EXPORT_SYMBOL(kstrdup);
 
 /**
+ * kstrndup - allocate space for and copy an existing string
+ * @s: the string to duplicate
+ * @max: read at most @max chars from @s
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ */
+char *kstrndup(const char *s, size_t max, gfp_t gfp)
+{
+        size_t len;
+        char *buf;
+
+        if (!s)
+                return NULL;
+
+        len = strnlen(s, max);
+        buf = kmalloc_track_caller(len+1, gfp);
+        if (buf) {
+                memcpy(buf, s, len);
+                buf[len] = '\0';
+        }
+        return buf;
+}
+EXPORT_SYMBOL(kstrndup);
+
+/**
  * kmemdup - duplicate region of memory
  *
  * @src: memory region to duplicate
@@ -80,7 +103,6 @@ EXPORT_SYMBOL(krealloc);
 
 /*
  * strndup_user - duplicate an existing string from user space
- *
  * @s: The string to duplicate
  * @n: Maximum number of bytes to copy, including the trailing NUL.
  */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8e05a11155c9..3130c343088f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -767,3 +767,56 @@ EXPORT_SYMBOL(remap_vmalloc_range);
 void  __attribute__((weak)) vmalloc_sync_all(void)
 {
 }
+
+
+static int f(pte_t *pte, struct page *pmd_page, 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(size, VM_IOREMAP);
+        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);