diff --git a/mm/mmap.c b/mm/mmap.c
new file mode 100644
index 0000000..a95ebda
--- /dev/null
+++ b/mm/mmap.c
@@ -0,0 +1,2082 @@
+/*
+ * mm/mmap.c
+ *
+ * Written by obz.
+ *
+ * Address space accounting code	<alan@redhat.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/hugetlb.h>
+#include <linux/profile.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/mempolicy.h>
+#include <linux/rmap.h>
+
+#include <asm/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/tlb.h>
+
+/*
+ * WARNING: the debugging will use recursive algorithms so never enable this
+ * unless you know what you are doing.
+ */
+#undef DEBUG_MM_RB
+
+/* description of effects of mapping type and prot in current implementation.
+ * this is due to the limited x86 page protection hardware.  The expected
+ * behavior is in parens:
+ *
+ * map_type	prot
+ *		PROT_NONE	PROT_READ	PROT_WRITE	PROT_EXEC
+ * MAP_SHARED	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
+ *		w: (no) no	w: (no) no	w: (yes) yes	w: (no) no
+ *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
+ *		
+ * MAP_PRIVATE	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
+ *		w: (no) no	w: (no) no	w: (copy) copy	w: (no) no
+ *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
+ *
+ */
+pgprot_t protection_map[16] = {
+	__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
+	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
+};
+
+int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
+int sysctl_overcommit_ratio = 50;	/* default is 50% */
+int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
+atomic_t vm_committed_space = ATOMIC_INIT(0);
+
+/*
+ * Check that a process has enough memory to allocate a new virtual
+ * mapping. 0 means there is enough memory for the allocation to
+ * succeed and -ENOMEM implies there is not.
+ *
+ * We currently support three overcommit policies, which are set via the
+ * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
+ *
+ * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
+ * Additional code 2002 Jul 20 by Robert Love.
+ *
+ * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
+ *
+ * Note this is a helper function intended to be used by LSMs which
+ * wish to use this logic.
+ */
+int __vm_enough_memory(long pages, int cap_sys_admin)
+{
+	unsigned long free, allowed;
+
+	vm_acct_memory(pages);
+
+	/*
+	 * Sometimes we want to use more memory than we have
+	 */
+	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
+		return 0;
+
+	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
+		unsigned long n;
+
+		free = get_page_cache_size();
+		free += nr_swap_pages;
+
+		/*
+		 * Any slabs which are created with the
+		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
+		 * which are reclaimable, under pressure.  The dentry
+		 * cache and most inode caches should fall into this
+		 */
+		free += atomic_read(&slab_reclaim_pages);
+
+		/*
+		 * Leave the last 3% for root
+		 */
+		if (!cap_sys_admin)
+			free -= free / 32;
+
+		if (free > pages)
+			return 0;
+
+		/*
+		 * nr_free_pages() is very expensive on large systems,
+		 * only call if we're about to fail.
+		 */
+		n = nr_free_pages();
+		if (!cap_sys_admin)
+			n -= n / 32;
+		free += n;
+
+		if (free > pages)
+			return 0;
+		vm_unacct_memory(pages);
+		return -ENOMEM;
+	}
+
+	allowed = (totalram_pages - hugetlb_total_pages())
+	       	* sysctl_overcommit_ratio / 100;
+	/*
+	 * Leave the last 3% for root
+	 */
+	if (!cap_sys_admin)
+		allowed -= allowed / 32;
+	allowed += total_swap_pages;
+
+	/* Don't let a single process grow too big:
+	   leave 3% of the size of this process for other processes */
+	allowed -= current->mm->total_vm / 32;
+
+	if (atomic_read(&vm_committed_space) < allowed)
+		return 0;
+
+	vm_unacct_memory(pages);
+
+	return -ENOMEM;
+}
+
+EXPORT_SYMBOL(sysctl_overcommit_memory);
+EXPORT_SYMBOL(sysctl_overcommit_ratio);
+EXPORT_SYMBOL(sysctl_max_map_count);
+EXPORT_SYMBOL(vm_committed_space);
+EXPORT_SYMBOL(__vm_enough_memory);
+
+/*
+ * Requires inode->i_mapping->i_mmap_lock
+ */
+static void __remove_shared_vm_struct(struct vm_area_struct *vma,
+		struct file *file, struct address_space *mapping)
+{
+	if (vma->vm_flags & VM_DENYWRITE)
+		atomic_inc(&file->f_dentry->d_inode->i_writecount);
+	if (vma->vm_flags & VM_SHARED)
+		mapping->i_mmap_writable--;
+
+	flush_dcache_mmap_lock(mapping);
+	if (unlikely(vma->vm_flags & VM_NONLINEAR))
+		list_del_init(&vma->shared.vm_set.list);
+	else
+		vma_prio_tree_remove(vma, &mapping->i_mmap);
+	flush_dcache_mmap_unlock(mapping);
+}
+
+/*
+ * Remove one vm structure and free it.
+ */
+static void remove_vm_struct(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+
+	might_sleep();
+	if (file) {
+		struct address_space *mapping = file->f_mapping;
+		spin_lock(&mapping->i_mmap_lock);
+		__remove_shared_vm_struct(vma, file, mapping);
+		spin_unlock(&mapping->i_mmap_lock);
+	}
+	if (vma->vm_ops && vma->vm_ops->close)
+		vma->vm_ops->close(vma);
+	if (file)
+		fput(file);
+	anon_vma_unlink(vma);
+	mpol_free(vma_policy(vma));
+	kmem_cache_free(vm_area_cachep, vma);
+}
+
+/*
+ *  sys_brk() for the most part doesn't need the global kernel
+ *  lock, except when an application is doing something nasty
+ *  like trying to un-brk an area that has already been mapped
+ *  to a regular file.  in this case, the unmapping will need
+ *  to invoke file system routines that need the global lock.
+ */
+asmlinkage unsigned long sys_brk(unsigned long brk)
+{
+	unsigned long rlim, retval;
+	unsigned long newbrk, oldbrk;
+	struct mm_struct *mm = current->mm;
+
+	down_write(&mm->mmap_sem);
+
+	if (brk < mm->end_code)
+		goto out;
+	newbrk = PAGE_ALIGN(brk);
+	oldbrk = PAGE_ALIGN(mm->brk);
+	if (oldbrk == newbrk)
+		goto set_brk;
+
+	/* Always allow shrinking brk. */
+	if (brk <= mm->brk) {
+		if (!do_munmap(mm, newbrk, oldbrk-newbrk))
+			goto set_brk;
+		goto out;
+	}
+
+	/* Check against rlimit.. */
+	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
+	if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
+		goto out;
+
+	/* Check against existing mmap mappings. */
+	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
+		goto out;
+
+	/* Ok, looks good - let it rip. */
+	if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
+		goto out;
+set_brk:
+	mm->brk = brk;
+out:
+	retval = mm->brk;
+	up_write(&mm->mmap_sem);
+	return retval;
+}
+
+#ifdef DEBUG_MM_RB
+static int browse_rb(struct rb_root *root)
+{
+	int i = 0, j;
+	struct rb_node *nd, *pn = NULL;
+	unsigned long prev = 0, pend = 0;
+
+	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
+		struct vm_area_struct *vma;
+		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
+		if (vma->vm_start < prev)
+			printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
+		if (vma->vm_start < pend)
+			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
+		if (vma->vm_start > vma->vm_end)
+			printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
+		i++;
+		pn = nd;
+	}
+	j = 0;
+	for (nd = pn; nd; nd = rb_prev(nd)) {
+		j++;
+	}
+	if (i != j)
+		printk("backwards %d, forwards %d\n", j, i), i = 0;
+	return i;
+}
+
+void validate_mm(struct mm_struct *mm)
+{
+	int bug = 0;
+	int i = 0;
+	struct vm_area_struct *tmp = mm->mmap;
+	while (tmp) {
+		tmp = tmp->vm_next;
+		i++;
+	}
+	if (i != mm->map_count)
+		printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
+	i = browse_rb(&mm->mm_rb);
+	if (i != mm->map_count)
+		printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
+	if (bug)
+		BUG();
+}
+#else
+#define validate_mm(mm) do { } while (0)
+#endif
+
+static struct vm_area_struct *
+find_vma_prepare(struct mm_struct *mm, unsigned long addr,
+		struct vm_area_struct **pprev, struct rb_node ***rb_link,
+		struct rb_node ** rb_parent)
+{
+	struct vm_area_struct * vma;
+	struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
+
+	__rb_link = &mm->mm_rb.rb_node;
+	rb_prev = __rb_parent = NULL;
+	vma = NULL;
+
+	while (*__rb_link) {
+		struct vm_area_struct *vma_tmp;
+
+		__rb_parent = *__rb_link;
+		vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
+
+		if (vma_tmp->vm_end > addr) {
+			vma = vma_tmp;
+			if (vma_tmp->vm_start <= addr)
+				return vma;
+			__rb_link = &__rb_parent->rb_left;
+		} else {
+			rb_prev = __rb_parent;
+			__rb_link = &__rb_parent->rb_right;
+		}
+	}
+
+	*pprev = NULL;
+	if (rb_prev)
+		*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
+	*rb_link = __rb_link;
+	*rb_parent = __rb_parent;
+	return vma;
+}
+
+static inline void
+__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct vm_area_struct *prev, struct rb_node *rb_parent)
+{
+	if (prev) {
+		vma->vm_next = prev->vm_next;
+		prev->vm_next = vma;
+	} else {
+		mm->mmap = vma;
+		if (rb_parent)
+			vma->vm_next = rb_entry(rb_parent,
+					struct vm_area_struct, vm_rb);
+		else
+			vma->vm_next = NULL;
+	}
+}
+
+void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct rb_node **rb_link, struct rb_node *rb_parent)
+{
+	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
+	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
+}
+
+static inline void __vma_link_file(struct vm_area_struct *vma)
+{
+	struct file * file;
+
+	file = vma->vm_file;
+	if (file) {
+		struct address_space *mapping = file->f_mapping;
+
+		if (vma->vm_flags & VM_DENYWRITE)
+			atomic_dec(&file->f_dentry->d_inode->i_writecount);
+		if (vma->vm_flags & VM_SHARED)
+			mapping->i_mmap_writable++;
+
+		flush_dcache_mmap_lock(mapping);
+		if (unlikely(vma->vm_flags & VM_NONLINEAR))
+			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
+		else
+			vma_prio_tree_insert(vma, &mapping->i_mmap);
+		flush_dcache_mmap_unlock(mapping);
+	}
+}
+
+static void
+__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+	struct vm_area_struct *prev, struct rb_node **rb_link,
+	struct rb_node *rb_parent)
+{
+	__vma_link_list(mm, vma, prev, rb_parent);
+	__vma_link_rb(mm, vma, rb_link, rb_parent);
+	__anon_vma_link(vma);
+}
+
+static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+			struct vm_area_struct *prev, struct rb_node **rb_link,
+			struct rb_node *rb_parent)
+{
+	struct address_space *mapping = NULL;
+
+	if (vma->vm_file)
+		mapping = vma->vm_file->f_mapping;
+
+	if (mapping) {
+		spin_lock(&mapping->i_mmap_lock);
+		vma->vm_truncate_count = mapping->truncate_count;
+	}
+	anon_vma_lock(vma);
+
+	__vma_link(mm, vma, prev, rb_link, rb_parent);
+	__vma_link_file(vma);
+
+	anon_vma_unlock(vma);
+	if (mapping)
+		spin_unlock(&mapping->i_mmap_lock);
+
+	mm->map_count++;
+	validate_mm(mm);
+}
+
+/*
+ * Helper for vma_adjust in the split_vma insert case:
+ * insert vm structure into list and rbtree and anon_vma,
+ * but it has already been inserted into prio_tree earlier.
+ */
+static void
+__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
+{
+	struct vm_area_struct * __vma, * prev;
+	struct rb_node ** rb_link, * rb_parent;
+
+	__vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
+	if (__vma && __vma->vm_start < vma->vm_end)
+		BUG();
+	__vma_link(mm, vma, prev, rb_link, rb_parent);
+	mm->map_count++;
+}
+
+static inline void
+__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
+		struct vm_area_struct *prev)
+{
+	prev->vm_next = vma->vm_next;
+	rb_erase(&vma->vm_rb, &mm->mm_rb);
+	if (mm->mmap_cache == vma)
+		mm->mmap_cache = prev;
+}
+
+/*
+ * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
+ * is already present in an i_mmap tree without adjusting the tree.
+ * The following helper function should be used when such adjustments
+ * are necessary.  The "insert" vma (if any) is to be inserted
+ * before we drop the necessary locks.
+ */
+void vma_adjust(struct vm_area_struct *vma, unsigned long start,
+	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *next = vma->vm_next;
+	struct vm_area_struct *importer = NULL;
+	struct address_space *mapping = NULL;
+	struct prio_tree_root *root = NULL;
+	struct file *file = vma->vm_file;
+	struct anon_vma *anon_vma = NULL;
+	long adjust_next = 0;
+	int remove_next = 0;
+
+	if (next && !insert) {
+		if (end >= next->vm_end) {
+			/*
+			 * vma expands, overlapping all the next, and
+			 * perhaps the one after too (mprotect case 6).
+			 */
+again:			remove_next = 1 + (end > next->vm_end);
+			end = next->vm_end;
+			anon_vma = next->anon_vma;
+			importer = vma;
+		} else if (end > next->vm_start) {
+			/*
+			 * vma expands, overlapping part of the next:
+			 * mprotect case 5 shifting the boundary up.
+			 */
+			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
+			anon_vma = next->anon_vma;
+			importer = vma;
+		} else if (end < vma->vm_end) {
+			/*
+			 * vma shrinks, and !insert tells it's not
+			 * split_vma inserting another: so it must be
+			 * mprotect case 4 shifting the boundary down.
+			 */
+			adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
+			anon_vma = next->anon_vma;
+			importer = next;
+		}
+	}
+
+	if (file) {
+		mapping = file->f_mapping;
+		if (!(vma->vm_flags & VM_NONLINEAR))
+			root = &mapping->i_mmap;
+		spin_lock(&mapping->i_mmap_lock);
+		if (importer &&
+		    vma->vm_truncate_count != next->vm_truncate_count) {
+			/*
+			 * unmap_mapping_range might be in progress:
+			 * ensure that the expanding vma is rescanned.
+			 */
+			importer->vm_truncate_count = 0;
+		}
+		if (insert) {
+			insert->vm_truncate_count = vma->vm_truncate_count;
+			/*
+			 * Put into prio_tree now, so instantiated pages
+			 * are visible to arm/parisc __flush_dcache_page
+			 * throughout; but we cannot insert into address
+			 * space until vma start or end is updated.
+			 */
+			__vma_link_file(insert);
+		}
+	}
+
+	/*
+	 * When changing only vma->vm_end, we don't really need
+	 * anon_vma lock: but is that case worth optimizing out?
+	 */
+	if (vma->anon_vma)
+		anon_vma = vma->anon_vma;
+	if (anon_vma) {
+		spin_lock(&anon_vma->lock);
+		/*
+		 * Easily overlooked: when mprotect shifts the boundary,
+		 * make sure the expanding vma has anon_vma set if the
+		 * shrinking vma had, to cover any anon pages imported.
+		 */
+		if (importer && !importer->anon_vma) {
+			importer->anon_vma = anon_vma;
+			__anon_vma_link(importer);
+		}
+	}
+
+	if (root) {
+		flush_dcache_mmap_lock(mapping);
+		vma_prio_tree_remove(vma, root);
+		if (adjust_next)
+			vma_prio_tree_remove(next, root);
+	}
+
+	vma->vm_start = start;
+	vma->vm_end = end;
+	vma->vm_pgoff = pgoff;
+	if (adjust_next) {
+		next->vm_start += adjust_next << PAGE_SHIFT;
+		next->vm_pgoff += adjust_next;
+	}
+
+	if (root) {
+		if (adjust_next)
+			vma_prio_tree_insert(next, root);
+		vma_prio_tree_insert(vma, root);
+		flush_dcache_mmap_unlock(mapping);
+	}
+
+	if (remove_next) {
+		/*
+		 * vma_merge has merged next into vma, and needs
+		 * us to remove next before dropping the locks.
+		 */
+		__vma_unlink(mm, next, vma);
+		if (file)
+			__remove_shared_vm_struct(next, file, mapping);
+		if (next->anon_vma)
+			__anon_vma_merge(vma, next);
+	} else if (insert) {
+		/*
+		 * split_vma has split insert from vma, and needs
+		 * us to insert it before dropping the locks
+		 * (it may either follow vma or precede it).
+		 */
+		__insert_vm_struct(mm, insert);
+	}
+
+	if (anon_vma)
+		spin_unlock(&anon_vma->lock);
+	if (mapping)
+		spin_unlock(&mapping->i_mmap_lock);
+
+	if (remove_next) {
+		if (file)
+			fput(file);
+		mm->map_count--;
+		mpol_free(vma_policy(next));
+		kmem_cache_free(vm_area_cachep, next);
+		/*
+		 * In mprotect's case 6 (see comments on vma_merge),
+		 * we must remove another next too. It would clutter
+		 * up the code too much to do both in one go.
+		 */
+		if (remove_next == 2) {
+			next = vma->vm_next;
+			goto again;
+		}
+	}
+
+	validate_mm(mm);
+}
+
+/*
+ * If the vma has a ->close operation then the driver probably needs to release
+ * per-vma resources, so we don't attempt to merge those.
+ */
+#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)
+
+static inline int is_mergeable_vma(struct vm_area_struct *vma,
+			struct file *file, unsigned long vm_flags)
+{
+	if (vma->vm_flags != vm_flags)
+		return 0;
+	if (vma->vm_file != file)
+		return 0;
+	if (vma->vm_ops && vma->vm_ops->close)
+		return 0;
+	return 1;
+}
+
+static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
+					struct anon_vma *anon_vma2)
+{
+	return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * in front of (at a lower virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ *
+ * We don't check here for the merged mmap wrapping around the end of pagecache
+ * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
+ * wrap, nor mmaps which cover the final page at index -1UL.
+ */
+static int
+can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
+	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+{
+	if (is_mergeable_vma(vma, file, vm_flags) &&
+	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
+		if (vma->vm_pgoff == vm_pgoff)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * beyond (at a higher virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ */
+static int
+can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
+	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+{
+	if (is_mergeable_vma(vma, file, vm_flags) &&
+	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
+		pgoff_t vm_pglen;
+		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
+ * whether that can be merged with its predecessor or its successor.
+ * Or both (it neatly fills a hole).
+ *
+ * In most cases - when called for mmap, brk or mremap - [addr,end) is
+ * certain not to be mapped by the time vma_merge is called; but when
+ * called for mprotect, it is certain to be already mapped (either at
+ * an offset within prev, or at the start of next), and the flags of
+ * this area are about to be changed to vm_flags - and the no-change
+ * case has already been eliminated.
+ *
+ * The following mprotect cases have to be considered, where AAAA is
+ * the area passed down from mprotect_fixup, never extending beyond one
+ * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
+ *
+ *     AAAA             AAAA                AAAA          AAAA
+ *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
+ *    cannot merge    might become    might become    might become
+ *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
+ *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
+ *    mremap move:                                    PPPPNNNNNNNN 8
+ *        AAAA
+ *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
+ *    might become    case 1 below    case 2 below    case 3 below
+ *
+ * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
+ * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
+ */
+struct vm_area_struct *vma_merge(struct mm_struct *mm,
+			struct vm_area_struct *prev, unsigned long addr,
+			unsigned long end, unsigned long vm_flags,
+		     	struct anon_vma *anon_vma, struct file *file,
+			pgoff_t pgoff, struct mempolicy *policy)
+{
+	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+	struct vm_area_struct *area, *next;
+
+	/*
+	 * We later require that vma->vm_flags == vm_flags,
+	 * so this tests vma->vm_flags & VM_SPECIAL, too.
+	 */
+	if (vm_flags & VM_SPECIAL)
+		return NULL;
+
+	if (prev)
+		next = prev->vm_next;
+	else
+		next = mm->mmap;
+	area = next;
+	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
+		next = next->vm_next;
+
+	/*
+	 * Can it merge with the predecessor?
+	 */
+	if (prev && prev->vm_end == addr &&
+  			mpol_equal(vma_policy(prev), policy) &&
+			can_vma_merge_after(prev, vm_flags,
+						anon_vma, file, pgoff)) {
+		/*
+		 * OK, it can.  Can we now merge in the successor as well?
+		 */
+		if (next && end == next->vm_start &&
+				mpol_equal(policy, vma_policy(next)) &&
+				can_vma_merge_before(next, vm_flags,
+					anon_vma, file, pgoff+pglen) &&
+				is_mergeable_anon_vma(prev->anon_vma,
+						      next->anon_vma)) {
+							/* cases 1, 6 */
+			vma_adjust(prev, prev->vm_start,
+				next->vm_end, prev->vm_pgoff, NULL);
+		} else					/* cases 2, 5, 7 */
+			vma_adjust(prev, prev->vm_start,
+				end, prev->vm_pgoff, NULL);
+		return prev;
+	}
+
+	/*
+	 * Can this new request be merged in front of next?
+	 */
+	if (next && end == next->vm_start &&
+ 			mpol_equal(policy, vma_policy(next)) &&
+			can_vma_merge_before(next, vm_flags,
+					anon_vma, file, pgoff+pglen)) {
+		if (prev && addr < prev->vm_end)	/* case 4 */
+			vma_adjust(prev, prev->vm_start,
+				addr, prev->vm_pgoff, NULL);
+		else					/* cases 3, 8 */
+			vma_adjust(area, addr, next->vm_end,
+				next->vm_pgoff - pglen, NULL);
+		return area;
+	}
+
+	return NULL;
+}
+
+/*
+ * find_mergeable_anon_vma is used by anon_vma_prepare, to check
+ * neighbouring vmas for a suitable anon_vma, before it goes off
+ * to allocate a new anon_vma.  It checks because a repetitive
+ * sequence of mprotects and faults may otherwise lead to distinct
+ * anon_vmas being allocated, preventing vma merge in subsequent
+ * mprotect.
+ */
+struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
+{
+	struct vm_area_struct *near;
+	unsigned long vm_flags;
+
+	near = vma->vm_next;
+	if (!near)
+		goto try_prev;
+
+	/*
+	 * Since only mprotect tries to remerge vmas, match flags
+	 * which might be mprotected into each other later on.
+	 * Neither mlock nor madvise tries to remerge at present,
+	 * so leave their flags as obstructing a merge.
+	 */
+	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
+	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
+
+	if (near->anon_vma && vma->vm_end == near->vm_start &&
+ 			mpol_equal(vma_policy(vma), vma_policy(near)) &&
+			can_vma_merge_before(near, vm_flags,
+				NULL, vma->vm_file, vma->vm_pgoff +
+				((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
+		return near->anon_vma;
+try_prev:
+	/*
+	 * It is potentially slow to have to call find_vma_prev here.
+	 * But it's only on the first write fault on the vma, not
+	 * every time, and we could devise a way to avoid it later
+	 * (e.g. stash info in next's anon_vma_node when assigning
+	 * an anon_vma, or when trying vma_merge).  Another time.
+	 */
+	if (find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma)
+		BUG();
+	if (!near)
+		goto none;
+
+	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
+	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
+
+	if (near->anon_vma && near->vm_end == vma->vm_start &&
+  			mpol_equal(vma_policy(near), vma_policy(vma)) &&
+			can_vma_merge_after(near, vm_flags,
+				NULL, vma->vm_file, vma->vm_pgoff))
+		return near->anon_vma;
+none:
+	/*
+	 * There's no absolute need to look only at touching neighbours:
+	 * we could search further afield for "compatible" anon_vmas.
+	 * But it would probably just be a waste of time searching,
+	 * or lead to too many vmas hanging off the same anon_vma.
+	 * We're trying to allow mprotect remerging later on,
+	 * not trying to minimize memory used for anon_vmas.
+	 */
+	return NULL;
+}
+
+#ifdef CONFIG_PROC_FS
+void __vm_stat_account(struct mm_struct *mm, unsigned long flags,
+						struct file *file, long pages)
+{
+	const unsigned long stack_flags
+		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
+
+#ifdef CONFIG_HUGETLB
+	if (flags & VM_HUGETLB) {
+		if (!(flags & VM_DONTCOPY))
+			mm->shared_vm += pages;
+		return;
+	}
+#endif /* CONFIG_HUGETLB */
+
+	if (file) {
+		mm->shared_vm += pages;
+		if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
+			mm->exec_vm += pages;
+	} else if (flags & stack_flags)
+		mm->stack_vm += pages;
+	if (flags & (VM_RESERVED|VM_IO))
+		mm->reserved_vm += pages;
+}
+#endif /* CONFIG_PROC_FS */
+
+/*
+ * The caller must hold down_write(current->mm->mmap_sem).
+ */
+
+unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
+			unsigned long len, unsigned long prot,
+			unsigned long flags, unsigned long pgoff)
+{
+	struct mm_struct * mm = current->mm;
+	struct vm_area_struct * vma, * prev;
+	struct inode *inode;
+	unsigned int vm_flags;
+	int correct_wcount = 0;
+	int error;
+	struct rb_node ** rb_link, * rb_parent;
+	int accountable = 1;
+	unsigned long charged = 0, reqprot = prot;
+
+	if (file) {
+		if (is_file_hugepages(file))
+			accountable = 0;
+
+		if (!file->f_op || !file->f_op->mmap)
+			return -ENODEV;
+
+		if ((prot & PROT_EXEC) &&
+		    (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
+			return -EPERM;
+	}
+	/*
+	 * Does the application expect PROT_READ to imply PROT_EXEC?
+	 *
+	 * (the exception is when the underlying filesystem is noexec
+	 *  mounted, in which case we dont add PROT_EXEC.)
+	 */
+	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+		if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
+			prot |= PROT_EXEC;
+
+	if (!len)
+		return -EINVAL;
+
+	/* Careful about overflows.. */
+	len = PAGE_ALIGN(len);
+	if (!len || len > TASK_SIZE)
+		return -ENOMEM;
+
+	/* offset overflow? */
+	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
+               return -EOVERFLOW;
+
+	/* Too many mappings? */
+	if (mm->map_count > sysctl_max_map_count)
+		return -ENOMEM;
+
+	/* Obtain the address to map to. we verify (or select) it and ensure
+	 * that it represents a valid section of the address space.
+	 */
+	addr = get_unmapped_area(file, addr, len, pgoff, flags);
+	if (addr & ~PAGE_MASK)
+		return addr;
+
+	/* Do simple checking here so the lower-level routines won't have
+	 * to. we assume access permissions have been handled by the open
+	 * of the memory object, so we don't do any here.
+	 */
+	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
+			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+
+	if (flags & MAP_LOCKED) {
+		if (!can_do_mlock())
+			return -EPERM;
+		vm_flags |= VM_LOCKED;
+	}
+	/* mlock MCL_FUTURE? */
+	if (vm_flags & VM_LOCKED) {
+		unsigned long locked, lock_limit;
+		locked = mm->locked_vm << PAGE_SHIFT;
+		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+		locked += len;
+		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+			return -EAGAIN;
+	}
+
+	inode = file ? file->f_dentry->d_inode : NULL;
+
+	if (file) {
+		switch (flags & MAP_TYPE) {
+		case MAP_SHARED:
+			if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
+				return -EACCES;
+
+			/*
+			 * Make sure we don't allow writing to an append-only
+			 * file..
+			 */
+			if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
+				return -EACCES;
+
+			/*
+			 * Make sure there are no mandatory locks on the file.
+			 */
+			if (locks_verify_locked(inode))
+				return -EAGAIN;
+
+			vm_flags |= VM_SHARED | VM_MAYSHARE;
+			if (!(file->f_mode & FMODE_WRITE))
+				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
+
+			/* fall through */
+		case MAP_PRIVATE:
+			if (!(file->f_mode & FMODE_READ))
+				return -EACCES;
+			break;
+
+		default:
+			return -EINVAL;
+		}
+	} else {
+		switch (flags & MAP_TYPE) {
+		case MAP_SHARED:
+			vm_flags |= VM_SHARED | VM_MAYSHARE;
+			break;
+		case MAP_PRIVATE:
+			/*
+			 * Set pgoff according to addr for anon_vma.
+			 */
+			pgoff = addr >> PAGE_SHIFT;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	error = security_file_mmap(file, reqprot, prot, flags);
+	if (error)
+		return error;
+		
+	/* Clear old maps */
+	error = -ENOMEM;
+munmap_back:
+	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
+	if (vma && vma->vm_start < addr + len) {
+		if (do_munmap(mm, addr, len))
+			return -ENOMEM;
+		goto munmap_back;
+	}
+
+	/* Check against address space limit. */
+	if ((mm->total_vm << PAGE_SHIFT) + len
+	    > current->signal->rlim[RLIMIT_AS].rlim_cur)
+		return -ENOMEM;
+
+	if (accountable && (!(flags & MAP_NORESERVE) ||
+			    sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
+		if (vm_flags & VM_SHARED) {
+			/* Check memory availability in shmem_file_setup? */
+			vm_flags |= VM_ACCOUNT;
+		} else if (vm_flags & VM_WRITE) {
+			/*
+			 * Private writable mapping: check memory availability
+			 */
+			charged = len >> PAGE_SHIFT;
+			if (security_vm_enough_memory(charged))
+				return -ENOMEM;
+			vm_flags |= VM_ACCOUNT;
+		}
+	}
+
+	/*
+	 * Can we just expand an old private anonymous mapping?
+	 * The VM_SHARED test is necessary because shmem_zero_setup
+	 * will create the file object for a shared anonymous map below.
+	 */
+	if (!file && !(vm_flags & VM_SHARED) &&
+	    vma_merge(mm, prev, addr, addr + len, vm_flags,
+					NULL, NULL, pgoff, NULL))
+		goto out;
+
+	/*
+	 * Determine the object being mapped and call the appropriate
+	 * specific mapper. the address has already been validated, but
+	 * not unmapped, but the maps are removed from the list.
+	 */
+	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+	if (!vma) {
+		error = -ENOMEM;
+		goto unacct_error;
+	}
+	memset(vma, 0, sizeof(*vma));
+
+	vma->vm_mm = mm;
+	vma->vm_start = addr;
+	vma->vm_end = addr + len;
+	vma->vm_flags = vm_flags;
+	vma->vm_page_prot = protection_map[vm_flags & 0x0f];
+	vma->vm_pgoff = pgoff;
+
+	if (file) {
+		error = -EINVAL;
+		if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+			goto free_vma;
+		if (vm_flags & VM_DENYWRITE) {
+			error = deny_write_access(file);
+			if (error)
+				goto free_vma;
+			correct_wcount = 1;
+		}
+		vma->vm_file = file;
+		get_file(file);
+		error = file->f_op->mmap(file, vma);
+		if (error)
+			goto unmap_and_free_vma;
+	} else if (vm_flags & VM_SHARED) {
+		error = shmem_zero_setup(vma);
+		if (error)
+			goto free_vma;
+	}
+
+	/* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
+	 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
+	 * that memory reservation must be checked; but that reservation
+	 * belongs to shared memory object, not to vma: so now clear it.
+	 */
+	if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
+		vma->vm_flags &= ~VM_ACCOUNT;
+
+	/* Can addr have changed??
+	 *
+	 * Answer: Yes, several device drivers can do it in their
+	 *         f_op->mmap method. -DaveM
+	 */
+	addr = vma->vm_start;
+	pgoff = vma->vm_pgoff;
+	vm_flags = vma->vm_flags;
+
+	if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
+			vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
+		file = vma->vm_file;
+		vma_link(mm, vma, prev, rb_link, rb_parent);
+		if (correct_wcount)
+			atomic_inc(&inode->i_writecount);
+	} else {
+		if (file) {
+			if (correct_wcount)
+				atomic_inc(&inode->i_writecount);
+			fput(file);
+		}
+		mpol_free(vma_policy(vma));
+		kmem_cache_free(vm_area_cachep, vma);
+	}
+out:	
+	mm->total_vm += len >> PAGE_SHIFT;
+	__vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
+	if (vm_flags & VM_LOCKED) {
+		mm->locked_vm += len >> PAGE_SHIFT;
+		make_pages_present(addr, addr + len);
+	}
+	if (flags & MAP_POPULATE) {
+		up_write(&mm->mmap_sem);
+		sys_remap_file_pages(addr, len, 0,
+					pgoff, flags & MAP_NONBLOCK);
+		down_write(&mm->mmap_sem);
+	}
+	return addr;
+
+unmap_and_free_vma:
+	if (correct_wcount)
+		atomic_inc(&inode->i_writecount);
+	vma->vm_file = NULL;
+	fput(file);
+
+	/* Undo any partial mapping done by a device driver. */
+	zap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
+free_vma:
+	kmem_cache_free(vm_area_cachep, vma);
+unacct_error:
+	if (charged)
+		vm_unacct_memory(charged);
+	return error;
+}
+
+EXPORT_SYMBOL(do_mmap_pgoff);
+
+/* Get an address range which is currently unmapped.
+ * For shmat() with addr=0.
+ *
+ * Ugly calling convention alert:
+ * Return value with the low bits set means error value,
+ * ie
+ *	if (ret & ~PAGE_MASK)
+ *		error = ret;
+ *
+ * This function "knows" that -ENOMEM has the bits set.
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA
+unsigned long
+arch_get_unmapped_area(struct file *filp, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long start_addr;
+
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma(mm, addr);
+		if (TASK_SIZE - len >= addr &&
+		    (!vma || addr + len <= vma->vm_start))
+			return addr;
+	}
+	start_addr = addr = mm->free_area_cache;
+
+full_search:
+	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+		/* At this point:  (!vma || addr < vma->vm_end). */
+		if (TASK_SIZE - len < addr) {
+			/*
+			 * Start a new search - just in case we missed
+			 * some holes.
+			 */
+			if (start_addr != TASK_UNMAPPED_BASE) {
+				start_addr = addr = TASK_UNMAPPED_BASE;
+				goto full_search;
+			}
+			return -ENOMEM;
+		}
+		if (!vma || addr + len <= vma->vm_start) {
+			/*
+			 * Remember the place where we stopped the search:
+			 */
+			mm->free_area_cache = addr + len;
+			return addr;
+		}
+		addr = vma->vm_end;
+	}
+}
+#endif	
+
+void arch_unmap_area(struct vm_area_struct *area)
+{
+	/*
+	 * Is this a new hole at the lowest possible address?
+	 */
+	if (area->vm_start >= TASK_UNMAPPED_BASE &&
+			area->vm_start < area->vm_mm->free_area_cache)
+		area->vm_mm->free_area_cache = area->vm_start;
+}
+
+/*
+ * This mmap-allocator allocates new areas top-down from below the
+ * stack's low limit (the base):
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+			  const unsigned long len, const unsigned long pgoff,
+			  const unsigned long flags)
+{
+	struct vm_area_struct *vma;
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = addr0;
+
+	/* requested length too big for entire address space */
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	/* requesting a specific address */
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma(mm, addr);
+		if (TASK_SIZE - len >= addr &&
+				(!vma || addr + len <= vma->vm_start))
+			return addr;
+	}
+
+	/* either no address requested or can't fit in requested address hole */
+	addr = mm->free_area_cache;
+
+	/* make sure it can fit in the remaining address space */
+	if (addr >= len) {
+		vma = find_vma(mm, addr-len);
+		if (!vma || addr <= vma->vm_start)
+			/* remember the address as a hint for next time */
+			return (mm->free_area_cache = addr-len);
+	}
+
+	addr = mm->mmap_base-len;
+
+	do {
+		/*
+		 * Lookup failure means no vma is above this address,
+		 * else if new region fits below vma->vm_start,
+		 * return with success:
+		 */
+		vma = find_vma(mm, addr);
+		if (!vma || addr+len <= vma->vm_start)
+			/* remember the address as a hint for next time */
+			return (mm->free_area_cache = addr);
+
+		/* try just below the current vma->vm_start */
+		addr = vma->vm_start-len;
+	} while (len <= vma->vm_start);
+
+	/*
+	 * A failed mmap() very likely causes application failure,
+	 * so fall back to the bottom-up function here. This scenario
+	 * can happen with large stack limits and large mmap()
+	 * allocations.
+	 */
+	mm->free_area_cache = TASK_UNMAPPED_BASE;
+	addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+	/*
+	 * Restore the topdown base:
+	 */
+	mm->free_area_cache = mm->mmap_base;
+
+	return addr;
+}
+#endif
+
+void arch_unmap_area_topdown(struct vm_area_struct *area)
+{
+	/*
+	 * Is this a new hole at the highest possible address?
+	 */
+	if (area->vm_end > area->vm_mm->free_area_cache)
+		area->vm_mm->free_area_cache = area->vm_end;
+
+	/* dont allow allocations above current base */
+	if (area->vm_mm->free_area_cache > area->vm_mm->mmap_base)
+		area->vm_mm->free_area_cache = area->vm_mm->mmap_base;
+}
+
+unsigned long
+get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
+		unsigned long pgoff, unsigned long flags)
+{
+	if (flags & MAP_FIXED) {
+		unsigned long ret;
+
+		if (addr > TASK_SIZE - len)
+			return -ENOMEM;
+		if (addr & ~PAGE_MASK)
+			return -EINVAL;
+		if (file && is_file_hugepages(file))  {
+			/*
+			 * Check if the given range is hugepage aligned, and
+			 * can be made suitable for hugepages.
+			 */
+			ret = prepare_hugepage_range(addr, len);
+		} else {
+			/*
+			 * Ensure that a normal request is not falling in a
+			 * reserved hugepage range.  For some archs like IA-64,
+			 * there is a separate region for hugepages.
+			 */
+			ret = is_hugepage_only_range(current->mm, addr, len);
+		}
+		if (ret)
+			return -EINVAL;
+		return addr;
+	}
+
+	if (file && file->f_op && file->f_op->get_unmapped_area)
+		return file->f_op->get_unmapped_area(file, addr, len,
+						pgoff, flags);
+
+	return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
+EXPORT_SYMBOL(get_unmapped_area);
+
+/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
+struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
+{
+	struct vm_area_struct *vma = NULL;
+
+	if (mm) {
+		/* Check the cache first. */
+		/* (Cache hit rate is typically around 35%.) */
+		vma = mm->mmap_cache;
+		if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
+			struct rb_node * rb_node;
+
+			rb_node = mm->mm_rb.rb_node;
+			vma = NULL;
+
+			while (rb_node) {
+				struct vm_area_struct * vma_tmp;
+
+				vma_tmp = rb_entry(rb_node,
+						struct vm_area_struct, vm_rb);
+
+				if (vma_tmp->vm_end > addr) {
+					vma = vma_tmp;
+					if (vma_tmp->vm_start <= addr)
+						break;
+					rb_node = rb_node->rb_left;
+				} else
+					rb_node = rb_node->rb_right;
+			}
+			if (vma)
+				mm->mmap_cache = vma;
+		}
+	}
+	return vma;
+}
+
+EXPORT_SYMBOL(find_vma);
+
+/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
+struct vm_area_struct *
+find_vma_prev(struct mm_struct *mm, unsigned long addr,
+			struct vm_area_struct **pprev)
+{
+	struct vm_area_struct *vma = NULL, *prev = NULL;
+	struct rb_node * rb_node;
+	if (!mm)
+		goto out;
+
+	/* Guard against addr being lower than the first VMA */
+	vma = mm->mmap;
+
+	/* Go through the RB tree quickly. */
+	rb_node = mm->mm_rb.rb_node;
+
+	while (rb_node) {
+		struct vm_area_struct *vma_tmp;
+		vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+
+		if (addr < vma_tmp->vm_end) {
+			rb_node = rb_node->rb_left;
+		} else {
+			prev = vma_tmp;
+			if (!prev->vm_next || (addr < prev->vm_next->vm_end))
+				break;
+			rb_node = rb_node->rb_right;
+		}
+	}
+
+out:
+	*pprev = prev;
+	return prev ? prev->vm_next : vma;
+}
+
+/*
+ * Verify that the stack growth is acceptable and
+ * update accounting. This is shared with both the
+ * grow-up and grow-down cases.
+ */
+static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct rlimit *rlim = current->signal->rlim;
+
+	/* address space limit tests */
+	if (mm->total_vm + grow > rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT)
+		return -ENOMEM;
+
+	/* Stack limit test */
+	if (size > rlim[RLIMIT_STACK].rlim_cur)
+		return -ENOMEM;
+
+	/* mlock limit tests */
+	if (vma->vm_flags & VM_LOCKED) {
+		unsigned long locked;
+		unsigned long limit;
+		locked = mm->locked_vm + grow;
+		limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+		if (locked > limit && !capable(CAP_IPC_LOCK))
+			return -ENOMEM;
+	}
+
+	/*
+	 * Overcommit..  This must be the final test, as it will
+	 * update security statistics.
+	 */
+	if (security_vm_enough_memory(grow))
+		return -ENOMEM;
+
+	/* Ok, everything looks good - let it rip */
+	mm->total_vm += grow;
+	if (vma->vm_flags & VM_LOCKED)
+		mm->locked_vm += grow;
+	__vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
+	return 0;
+}
+
+#ifdef CONFIG_STACK_GROWSUP
+/*
+ * vma is the first one with address > vma->vm_end.  Have to extend vma.
+ */
+int expand_stack(struct vm_area_struct * vma, unsigned long address)
+{
+	int error;
+
+	if (!(vma->vm_flags & VM_GROWSUP))
+		return -EFAULT;
+
+	/*
+	 * We must make sure the anon_vma is allocated
+	 * so that the anon_vma locking is not a noop.
+	 */
+	if (unlikely(anon_vma_prepare(vma)))
+		return -ENOMEM;
+	anon_vma_lock(vma);
+
+	/*
+	 * vma->vm_start/vm_end cannot change under us because the caller
+	 * is required to hold the mmap_sem in read mode.  We need the
+	 * anon_vma lock to serialize against concurrent expand_stacks.
+	 */
+	address += 4 + PAGE_SIZE - 1;
+	address &= PAGE_MASK;
+	error = 0;
+
+	/* Somebody else might have raced and expanded it already */
+	if (address > vma->vm_end) {
+		unsigned long size, grow;
+
+		size = address - vma->vm_start;
+		grow = (address - vma->vm_end) >> PAGE_SHIFT;
+
+		error = acct_stack_growth(vma, size, grow);
+		if (!error)
+			vma->vm_end = address;
+	}
+	anon_vma_unlock(vma);
+	return error;
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+	struct vm_area_struct *vma, *prev;
+
+	addr &= PAGE_MASK;
+	vma = find_vma_prev(mm, addr, &prev);
+	if (vma && (vma->vm_start <= addr))
+		return vma;
+	if (!prev || expand_stack(prev, addr))
+		return NULL;
+	if (prev->vm_flags & VM_LOCKED) {
+		make_pages_present(addr, prev->vm_end);
+	}
+	return prev;
+}
+#else
+/*
+ * vma is the first one with address < vma->vm_start.  Have to extend vma.
+ */
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+	int error;
+
+	/*
+	 * We must make sure the anon_vma is allocated
+	 * so that the anon_vma locking is not a noop.
+	 */
+	if (unlikely(anon_vma_prepare(vma)))
+		return -ENOMEM;
+	anon_vma_lock(vma);
+
+	/*
+	 * vma->vm_start/vm_end cannot change under us because the caller
+	 * is required to hold the mmap_sem in read mode.  We need the
+	 * anon_vma lock to serialize against concurrent expand_stacks.
+	 */
+	address &= PAGE_MASK;
+	error = 0;
+
+	/* Somebody else might have raced and expanded it already */
+	if (address < vma->vm_start) {
+		unsigned long size, grow;
+
+		size = vma->vm_end - address;
+		grow = (vma->vm_start - address) >> PAGE_SHIFT;
+
+		error = acct_stack_growth(vma, size, grow);
+		if (!error) {
+			vma->vm_start = address;
+			vma->vm_pgoff -= grow;
+		}
+	}
+	anon_vma_unlock(vma);
+	return error;
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct * mm, unsigned long addr)
+{
+	struct vm_area_struct * vma;
+	unsigned long start;
+
+	addr &= PAGE_MASK;
+	vma = find_vma(mm,addr);
+	if (!vma)
+		return NULL;
+	if (vma->vm_start <= addr)
+		return vma;
+	if (!(vma->vm_flags & VM_GROWSDOWN))
+		return NULL;
+	start = vma->vm_start;
+	if (expand_stack(vma, addr))
+		return NULL;
+	if (vma->vm_flags & VM_LOCKED) {
+		make_pages_present(addr, start);
+	}
+	return vma;
+}
+#endif
+
+/*
+ * Try to free as many page directory entries as we can,
+ * without having to work very hard at actually scanning
+ * the page tables themselves.
+ *
+ * Right now we try to free page tables if we have a nice
+ * PGDIR-aligned area that got free'd up. We could be more
+ * granular if we want to, but this is fast and simple,
+ * and covers the bad cases.
+ *
+ * "prev", if it exists, points to a vma before the one
+ * we just free'd - but there's no telling how much before.
+ */
+static void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev,
+	unsigned long start, unsigned long end)
+{
+	unsigned long first = start & PGDIR_MASK;
+	unsigned long last = end + PGDIR_SIZE - 1;
+	struct mm_struct *mm = tlb->mm;
+
+	if (last > MM_VM_SIZE(mm) || last < end)
+		last = MM_VM_SIZE(mm);
+
+	if (!prev) {
+		prev = mm->mmap;
+		if (!prev)
+			goto no_mmaps;
+		if (prev->vm_end > start) {
+			if (last > prev->vm_start)
+				last = prev->vm_start;
+			goto no_mmaps;
+		}
+	}
+	for (;;) {
+		struct vm_area_struct *next = prev->vm_next;
+
+		if (next) {
+			if (next->vm_start < start) {
+				prev = next;
+				continue;
+			}
+			if (last > next->vm_start)
+				last = next->vm_start;
+		}
+		if (prev->vm_end > first)
+			first = prev->vm_end;
+		break;
+	}
+no_mmaps:
+	if (last < first)	/* for arches with discontiguous pgd indices */
+		return;
+	if (first < FIRST_USER_PGD_NR * PGDIR_SIZE)
+		first = FIRST_USER_PGD_NR * PGDIR_SIZE;
+	/* No point trying to free anything if we're in the same pte page */
+	if ((first & PMD_MASK) < (last & PMD_MASK)) {
+		clear_page_range(tlb, first, last);
+		flush_tlb_pgtables(mm, first, last);
+	}
+}
+
+/* Normal function to fix up a mapping
+ * This function is the default for when an area has no specific
+ * function.  This may be used as part of a more specific routine.
+ *
+ * By the time this function is called, the area struct has been
+ * removed from the process mapping list.
+ */
+static void unmap_vma(struct mm_struct *mm, struct vm_area_struct *area)
+{
+	size_t len = area->vm_end - area->vm_start;
+
+	area->vm_mm->total_vm -= len >> PAGE_SHIFT;
+	if (area->vm_flags & VM_LOCKED)
+		area->vm_mm->locked_vm -= len >> PAGE_SHIFT;
+	vm_stat_unaccount(area);
+	area->vm_mm->unmap_area(area);
+	remove_vm_struct(area);
+}
+
+/*
+ * Update the VMA and inode share lists.
+ *
+ * Ok - we have the memory areas we should free on the 'free' list,
+ * so release them, and do the vma updates.
+ */
+static void unmap_vma_list(struct mm_struct *mm,
+	struct vm_area_struct *mpnt)
+{
+	do {
+		struct vm_area_struct *next = mpnt->vm_next;
+		unmap_vma(mm, mpnt);
+		mpnt = next;
+	} while (mpnt != NULL);
+	validate_mm(mm);
+}
+
+/*
+ * Get rid of page table information in the indicated region.
+ *
+ * Called with the page table lock held.
+ */
+static void unmap_region(struct mm_struct *mm,
+	struct vm_area_struct *vma,
+	struct vm_area_struct *prev,
+	unsigned long start,
+	unsigned long end)
+{
+	struct mmu_gather *tlb;
+	unsigned long nr_accounted = 0;
+
+	lru_add_drain();
+	tlb = tlb_gather_mmu(mm, 0);
+	unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted, NULL);
+	vm_unacct_memory(nr_accounted);
+
+	if (is_hugepage_only_range(mm, start, end - start))
+		hugetlb_free_pgtables(tlb, prev, start, end);
+	else
+		free_pgtables(tlb, prev, start, end);
+	tlb_finish_mmu(tlb, start, end);
+}
+
+/*
+ * Create a list of vma's touched by the unmap, removing them from the mm's
+ * vma list as we go..
+ */
+static void
+detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
+	struct vm_area_struct *prev, unsigned long end)
+{
+	struct vm_area_struct **insertion_point;
+	struct vm_area_struct *tail_vma = NULL;
+
+	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
+	do {
+		rb_erase(&vma->vm_rb, &mm->mm_rb);
+		mm->map_count--;
+		tail_vma = vma;
+		vma = vma->vm_next;
+	} while (vma && vma->vm_start < end);
+	*insertion_point = vma;
+	tail_vma->vm_next = NULL;
+	mm->mmap_cache = NULL;		/* Kill the cache. */
+}
+
+/*
+ * Split a vma into two pieces at address 'addr', a new vma is allocated
+ * either for the first part or the the tail.
+ */
+int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
+	      unsigned long addr, int new_below)
+{
+	struct mempolicy *pol;
+	struct vm_area_struct *new;
+
+	if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
+		return -EINVAL;
+
+	if (mm->map_count >= sysctl_max_map_count)
+		return -ENOMEM;
+
+	new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	/* most fields are the same, copy all, and then fixup */
+	*new = *vma;
+
+	if (new_below)
+		new->vm_end = addr;
+	else {
+		new->vm_start = addr;
+		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
+	}
+
+	pol = mpol_copy(vma_policy(vma));
+	if (IS_ERR(pol)) {
+		kmem_cache_free(vm_area_cachep, new);
+		return PTR_ERR(pol);
+	}
+	vma_set_policy(new, pol);
+
+	if (new->vm_file)
+		get_file(new->vm_file);
+
+	if (new->vm_ops && new->vm_ops->open)
+		new->vm_ops->open(new);
+
+	if (new_below)
+		vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
+			((addr - new->vm_start) >> PAGE_SHIFT), new);
+	else
+		vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
+
+	return 0;
+}
+
+/* Munmap is split into 2 main parts -- this part which finds
+ * what needs doing, and the areas themselves, which do the
+ * work.  This now handles partial unmappings.
+ * Jeremy Fitzhardinge <jeremy@goop.org>
+ */
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+{
+	unsigned long end;
+	struct vm_area_struct *mpnt, *prev, *last;
+
+	if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
+		return -EINVAL;
+
+	if ((len = PAGE_ALIGN(len)) == 0)
+		return -EINVAL;
+
+	/* Find the first overlapping VMA */
+	mpnt = find_vma_prev(mm, start, &prev);
+	if (!mpnt)
+		return 0;
+	/* we have  start < mpnt->vm_end  */
+
+	/* if it doesn't overlap, we have nothing.. */
+	end = start + len;
+	if (mpnt->vm_start >= end)
+		return 0;
+
+	/*
+	 * If we need to split any vma, do it now to save pain later.
+	 *
+	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
+	 * unmapped vm_area_struct will remain in use: so lower split_vma
+	 * places tmp vma above, and higher split_vma places tmp vma below.
+	 */
+	if (start > mpnt->vm_start) {
+		int error = split_vma(mm, mpnt, start, 0);
+		if (error)
+			return error;
+		prev = mpnt;
+	}
+
+	/* Does it split the last one? */
+	last = find_vma(mm, end);
+	if (last && end > last->vm_start) {
+		int error = split_vma(mm, last, end, 1);
+		if (error)
+			return error;
+	}
+	mpnt = prev? prev->vm_next: mm->mmap;
+
+	/*
+	 * Remove the vma's, and unmap the actual pages
+	 */
+	detach_vmas_to_be_unmapped(mm, mpnt, prev, end);
+	spin_lock(&mm->page_table_lock);
+	unmap_region(mm, mpnt, prev, start, end);
+	spin_unlock(&mm->page_table_lock);
+
+	/* Fix up all other VM information */
+	unmap_vma_list(mm, mpnt);
+
+	return 0;
+}
+
+EXPORT_SYMBOL(do_munmap);
+
+asmlinkage long sys_munmap(unsigned long addr, size_t len)
+{
+	int ret;
+	struct mm_struct *mm = current->mm;
+
+	profile_munmap(addr);
+
+	down_write(&mm->mmap_sem);
+	ret = do_munmap(mm, addr, len);
+	up_write(&mm->mmap_sem);
+	return ret;
+}
+
+static inline void verify_mm_writelocked(struct mm_struct *mm)
+{
+#ifdef CONFIG_DEBUG_KERNEL
+	if (unlikely(down_read_trylock(&mm->mmap_sem))) {
+		WARN_ON(1);
+		up_read(&mm->mmap_sem);
+	}
+#endif
+}
+
+/*
+ *  this is really a simplified "do_mmap".  it only handles
+ *  anonymous maps.  eventually we may be able to do some
+ *  brk-specific accounting here.
+ */
+unsigned long do_brk(unsigned long addr, unsigned long len)
+{
+	struct mm_struct * mm = current->mm;
+	struct vm_area_struct * vma, * prev;
+	unsigned long flags;
+	struct rb_node ** rb_link, * rb_parent;
+	pgoff_t pgoff = addr >> PAGE_SHIFT;
+
+	len = PAGE_ALIGN(len);
+	if (!len)
+		return addr;
+
+	if ((addr + len) > TASK_SIZE || (addr + len) < addr)
+		return -EINVAL;
+
+	/*
+	 * mlock MCL_FUTURE?
+	 */
+	if (mm->def_flags & VM_LOCKED) {
+		unsigned long locked, lock_limit;
+		locked = mm->locked_vm << PAGE_SHIFT;
+		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+		locked += len;
+		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+			return -EAGAIN;
+	}
+
+	/*
+	 * mm->mmap_sem is required to protect against another thread
+	 * changing the mappings in case we sleep.
+	 */
+	verify_mm_writelocked(mm);
+
+	/*
+	 * Clear old maps.  this also does some error checking for us
+	 */
+ munmap_back:
+	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
+	if (vma && vma->vm_start < addr + len) {
+		if (do_munmap(mm, addr, len))
+			return -ENOMEM;
+		goto munmap_back;
+	}
+
+	/* Check against address space limits *after* clearing old maps... */
+	if ((mm->total_vm << PAGE_SHIFT) + len
+	    > current->signal->rlim[RLIMIT_AS].rlim_cur)
+		return -ENOMEM;
+
+	if (mm->map_count > sysctl_max_map_count)
+		return -ENOMEM;
+
+	if (security_vm_enough_memory(len >> PAGE_SHIFT))
+		return -ENOMEM;
+
+	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+
+	/* Can we just expand an old private anonymous mapping? */
+	if (vma_merge(mm, prev, addr, addr + len, flags,
+					NULL, NULL, pgoff, NULL))
+		goto out;
+
+	/*
+	 * create a vma struct for an anonymous mapping
+	 */
+	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+	if (!vma) {
+		vm_unacct_memory(len >> PAGE_SHIFT);
+		return -ENOMEM;
+	}
+	memset(vma, 0, sizeof(*vma));
+
+	vma->vm_mm = mm;
+	vma->vm_start = addr;
+	vma->vm_end = addr + len;
+	vma->vm_pgoff = pgoff;
+	vma->vm_flags = flags;
+	vma->vm_page_prot = protection_map[flags & 0x0f];
+	vma_link(mm, vma, prev, rb_link, rb_parent);
+out:
+	mm->total_vm += len >> PAGE_SHIFT;
+	if (flags & VM_LOCKED) {
+		mm->locked_vm += len >> PAGE_SHIFT;
+		make_pages_present(addr, addr + len);
+	}
+	return addr;
+}
+
+EXPORT_SYMBOL(do_brk);
+
+/* Release all mmaps. */
+void exit_mmap(struct mm_struct *mm)
+{
+	struct mmu_gather *tlb;
+	struct vm_area_struct *vma;
+	unsigned long nr_accounted = 0;
+
+	lru_add_drain();
+
+	spin_lock(&mm->page_table_lock);
+
+	tlb = tlb_gather_mmu(mm, 1);
+	flush_cache_mm(mm);
+	/* Use ~0UL here to ensure all VMAs in the mm are unmapped */
+	mm->map_count -= unmap_vmas(&tlb, mm, mm->mmap, 0,
+					~0UL, &nr_accounted, NULL);
+	vm_unacct_memory(nr_accounted);
+	BUG_ON(mm->map_count);	/* This is just debugging */
+	clear_page_range(tlb, FIRST_USER_PGD_NR * PGDIR_SIZE, MM_VM_SIZE(mm));
+	
+	tlb_finish_mmu(tlb, 0, MM_VM_SIZE(mm));
+
+	vma = mm->mmap;
+	mm->mmap = mm->mmap_cache = NULL;
+	mm->mm_rb = RB_ROOT;
+	set_mm_counter(mm, rss, 0);
+	mm->total_vm = 0;
+	mm->locked_vm = 0;
+
+	spin_unlock(&mm->page_table_lock);
+
+	/*
+	 * Walk the list again, actually closing and freeing it
+	 * without holding any MM locks.
+	 */
+	while (vma) {
+		struct vm_area_struct *next = vma->vm_next;
+		remove_vm_struct(vma);
+		vma = next;
+	}
+}
+
+/* Insert vm structure into process list sorted by address
+ * and into the inode's i_mmap tree.  If vm_file is non-NULL
+ * then i_mmap_lock is taken here.
+ */
+int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
+{
+	struct vm_area_struct * __vma, * prev;
+	struct rb_node ** rb_link, * rb_parent;
+
+	/*
+	 * The vm_pgoff of a purely anonymous vma should be irrelevant
+	 * until its first write fault, when page's anon_vma and index
+	 * are set.  But now set the vm_pgoff it will almost certainly
+	 * end up with (unless mremap moves it elsewhere before that
+	 * first wfault), so /proc/pid/maps tells a consistent story.
+	 *
+	 * By setting it to reflect the virtual start address of the
+	 * vma, merges and splits can happen in a seamless way, just
+	 * using the existing file pgoff checks and manipulations.
+	 * Similarly in do_mmap_pgoff and in do_brk.
+	 */
+	if (!vma->vm_file) {
+		BUG_ON(vma->anon_vma);
+		vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
+	}
+	__vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
+	if (__vma && __vma->vm_start < vma->vm_end)
+		return -ENOMEM;
+	vma_link(mm, vma, prev, rb_link, rb_parent);
+	return 0;
+}
+
+/*
+ * Copy the vma structure to a new location in the same mm,
+ * prior to moving page table entries, to effect an mremap move.
+ */
+struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
+	unsigned long addr, unsigned long len, pgoff_t pgoff)
+{
+	struct vm_area_struct *vma = *vmap;
+	unsigned long vma_start = vma->vm_start;
+	struct mm_struct *mm = vma->vm_mm;
+	struct vm_area_struct *new_vma, *prev;
+	struct rb_node **rb_link, *rb_parent;
+	struct mempolicy *pol;
+
+	/*
+	 * If anonymous vma has not yet been faulted, update new pgoff
+	 * to match new location, to increase its chance of merging.
+	 */
+	if (!vma->vm_file && !vma->anon_vma)
+		pgoff = addr >> PAGE_SHIFT;
+
+	find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
+	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
+			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
+	if (new_vma) {
+		/*
+		 * Source vma may have been merged into new_vma
+		 */
+		if (vma_start >= new_vma->vm_start &&
+		    vma_start < new_vma->vm_end)
+			*vmap = new_vma;
+	} else {
+		new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+		if (new_vma) {
+			*new_vma = *vma;
+			pol = mpol_copy(vma_policy(vma));
+			if (IS_ERR(pol)) {
+				kmem_cache_free(vm_area_cachep, new_vma);
+				return NULL;
+			}
+			vma_set_policy(new_vma, pol);
+			new_vma->vm_start = addr;
+			new_vma->vm_end = addr + len;
+			new_vma->vm_pgoff = pgoff;
+			if (new_vma->vm_file)
+				get_file(new_vma->vm_file);
+			if (new_vma->vm_ops && new_vma->vm_ops->open)
+				new_vma->vm_ops->open(new_vma);
+			vma_link(mm, new_vma, prev, rb_link, rb_parent);
+		}
+	}
+	return new_vma;
+}