mm/mremap.c - pub/scm/linux/kernel/git/joro/linux - Git at Google

 /*
  *	linux/mm/remap.c
  *
  *	(C) Copyright 1996 Linus Torvalds
  */

 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 #include <linux/shm.h>
 #include <linux/mman.h>
 #include <linux/swap.h>
 #include <linux/fs.h>
 #include <linux/highmem.h>

 #include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>

 extern int vm_enough_memory(long pages);

 static inline pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr)
 {
 	pgd_t * pgd;
 	pmd_t * pmd;
 	pte_t * pte = NULL;

 	pgd = pgd_offset(mm, addr);
 	if (pgd_none(*pgd))
 		goto end;
 	if (pgd_bad(*pgd)) {
 		pgd_ERROR(*pgd);
 		pgd_clear(pgd);
 		goto end;
 	}

 	pmd = pmd_offset(pgd, addr);
 	if (pmd_none(*pmd))
 		goto end;
 	if (pmd_bad(*pmd)) {
 		pmd_ERROR(*pmd);
 		pmd_clear(pmd);
 		goto end;
 	}

 	pte = pte_offset_map_nested(pmd, addr);
 	if (pte_none(*pte)) {
 		pte_unmap_nested(pte);
 		pte = NULL;
 	}
 end:
 	return pte;
 }

 static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr)
 {
 	pmd_t * pmd;
 	pte_t * pte = NULL;

 	pmd = pmd_alloc(mm, pgd_offset(mm, addr), addr);
 	if (pmd)
 		pte = pte_alloc_map(mm, pmd, addr);
 	return pte;
 }

 static inline int copy_one_pte(struct mm_struct *mm, pte_t * src, pte_t * dst)
 {
 	int error = 0;
 	pte_t pte;

 	if (!pte_none(*src)) {
 		pte = ptep_get_and_clear(src);
 		if (!dst) {
 			/* No dest?  We must put it back. */
 			dst = src;
 			error++;
 		}
 		set_pte(dst, pte);
 	}
 	return error;
 }

 static int move_one_page(struct vm_area_struct *vma, unsigned long old_addr, unsigned long new_addr)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	int error = 0;
 	pte_t *src, *dst;

 	spin_lock(&mm->page_table_lock);
 	src = get_one_pte_map_nested(mm, old_addr);
 	if (src) {
 		dst = alloc_one_pte_map(mm, new_addr);
 		error = copy_one_pte(mm, src, dst);
 		pte_unmap_nested(src);
 		pte_unmap(dst);
 	}
 	flush_tlb_page(vma, old_addr);
 	spin_unlock(&mm->page_table_lock);
 	return error;
 }

 static int move_page_tables(struct vm_area_struct *vma,
 	unsigned long new_addr, unsigned long old_addr, unsigned long len)
 {
 	unsigned long offset = len;

 	flush_cache_range(vma, old_addr, old_addr + len);

 	/*
 	 * This is not the clever way to do this, but we're taking the
 	 * easy way out on the assumption that most remappings will be
 	 * only a few pages.. This also makes error recovery easier.
 	 */
 	while (offset) {
 		offset -= PAGE_SIZE;
 		if (move_one_page(vma, old_addr + offset, new_addr + offset))
 			goto oops_we_failed;
 	}
 	return 0;

 	/*
 	 * Ok, the move failed because we didn't have enough pages for
 	 * the new page table tree. This is unlikely, but we have to
 	 * take the possibility into account. In that case we just move
 	 * all the pages back (this will work, because we still have
 	 * the old page tables)
 	 */
 oops_we_failed:
 	flush_cache_range(vma, new_addr, new_addr + len);
 	while ((offset += PAGE_SIZE) < len)
 		move_one_page(vma, new_addr + offset, old_addr + offset);
 	zap_page_range(vma, new_addr, len);
 	return -1;
 }

 static inline unsigned long move_vma(struct vm_area_struct * vma,
 	unsigned long addr, unsigned long old_len, unsigned long new_len,
 	unsigned long new_addr)
 {
 	struct mm_struct * mm = vma->vm_mm;
 	struct vm_area_struct * new_vma, * next, * prev;
 	int allocated_vma;

 	new_vma = NULL;
 	next = find_vma_prev(mm, new_addr, &prev);
 	if (next) {
 		if (prev && prev->vm_end == new_addr &&
 		    can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
 			spin_lock(&mm->page_table_lock);
 			prev->vm_end = new_addr + new_len;
 			spin_unlock(&mm->page_table_lock);
 			new_vma = prev;
 			if (next != prev->vm_next)
 				BUG();
 			if (prev->vm_end == next->vm_start && can_vma_merge(next, prev->vm_flags)) {
 				spin_lock(&mm->page_table_lock);
 				prev->vm_end = next->vm_end;
 				__vma_unlink(mm, next, prev);
 				spin_unlock(&mm->page_table_lock);

 				mm->map_count--;
 				kmem_cache_free(vm_area_cachep, next);
 			}
 		} else if (next->vm_start == new_addr + new_len &&
 			   can_vma_merge(next, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
 			spin_lock(&mm->page_table_lock);
 			next->vm_start = new_addr;
 			spin_unlock(&mm->page_table_lock);
 			new_vma = next;
 		}
 	} else {
 		prev = find_vma(mm, new_addr-1);
 		if (prev && prev->vm_end == new_addr &&
 		    can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
 			spin_lock(&mm->page_table_lock);
 			prev->vm_end = new_addr + new_len;
 			spin_unlock(&mm->page_table_lock);
 			new_vma = prev;
 		}
 	}

 	allocated_vma = 0;
 	if (!new_vma) {
 		new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 		if (!new_vma)
 			goto out;
 		allocated_vma = 1;
 	}

 	if (!move_page_tables(vma, new_addr, addr, old_len)) {
 		if (allocated_vma) {
 			*new_vma = *vma;
 			new_vma->vm_start = new_addr;
 			new_vma->vm_end = new_addr+new_len;
 			new_vma->vm_pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
 			new_vma->vm_raend = 0;
 			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);
 			insert_vm_struct(current->mm, new_vma);
 		}
 		do_munmap(current->mm, addr, old_len);
 		current->mm->total_vm += new_len >> PAGE_SHIFT;
 		if (new_vma->vm_flags & VM_LOCKED) {
 			current->mm->locked_vm += new_len >> PAGE_SHIFT;
 			make_pages_present(new_vma->vm_start,
 					   new_vma->vm_end);
 		}
 		return new_addr;
 	}
 	if (allocated_vma)
 		kmem_cache_free(vm_area_cachep, new_vma);
  out:
 	return -ENOMEM;
 }

 /*
  * Expand (or shrink) an existing mapping, potentially moving it at the
  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
  *
  * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
  * This option implies MREMAP_MAYMOVE.
  */
 unsigned long do_mremap(unsigned long addr,
 	unsigned long old_len, unsigned long new_len,
 	unsigned long flags, unsigned long new_addr)
 {
 	struct vm_area_struct *vma;
 	unsigned long ret = -EINVAL;

 	if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
 		goto out;

 	if (addr & ~PAGE_MASK)
 		goto out;

 	old_len = PAGE_ALIGN(old_len);
 	new_len = PAGE_ALIGN(new_len);

 	/* new_addr is only valid if MREMAP_FIXED is specified */
 	if (flags & MREMAP_FIXED) {
 		if (new_addr & ~PAGE_MASK)
 			goto out;
 		if (!(flags & MREMAP_MAYMOVE))
 			goto out;

 		if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
 			goto out;

 		/* Check if the location we're moving into overlaps the
 		 * old location at all, and fail if it does.
 		 */
 		if ((new_addr <= addr) && (new_addr+new_len) > addr)
 			goto out;

 		if ((addr <= new_addr) && (addr+old_len) > new_addr)
 			goto out;

 		do_munmap(current->mm, new_addr, new_len);
 	}

 	/*
 	 * Always allow a shrinking remap: that just unmaps
 	 * the unnecessary pages..
 	 */
 	ret = addr;
 	if (old_len >= new_len) {
 		do_munmap(current->mm, addr+new_len, old_len - new_len);
 		if (!(flags & MREMAP_FIXED) || (new_addr == addr))
 			goto out;
 	}

 	/*
 	 * Ok, we need to grow..  or relocate.
 	 */
 	ret = -EFAULT;
 	vma = find_vma(current->mm, addr);
 	if (!vma || vma->vm_start > addr)
 		goto out;
 	/* We can't remap across vm area boundaries */
 	if (old_len > vma->vm_end - addr)
 		goto out;
 	if (vma->vm_flags & VM_DONTEXPAND) {
 		if (new_len > old_len)
 			goto out;
 	}
 	if (vma->vm_flags & VM_LOCKED) {
 		unsigned long locked = current->mm->locked_vm << PAGE_SHIFT;
 		locked += new_len - old_len;
 		ret = -EAGAIN;
 		if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
 			goto out;
 	}
 	ret = -ENOMEM;
 	if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
 	    > current->rlim[RLIMIT_AS].rlim_cur)
 		goto out;
 	/* Private writable mapping? Check memory availability.. */
 	if ((vma->vm_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE &&
 	    !(flags & MAP_NORESERVE)				 &&
 	    !vm_enough_memory((new_len - old_len) >> PAGE_SHIFT))
 		goto out;

 	/* old_len exactly to the end of the area..
 	 * And we're not relocating the area.
 	 */
 	if (old_len == vma->vm_end - addr &&
 	    !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
 	    (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
 		unsigned long max_addr = TASK_SIZE;
 		if (vma->vm_next)
 			max_addr = vma->vm_next->vm_start;
 		/* can we just expand the current mapping? */
 		if (max_addr - addr >= new_len) {
 			int pages = (new_len - old_len) >> PAGE_SHIFT;
 			spin_lock(&vma->vm_mm->page_table_lock);
 			vma->vm_end = addr + new_len;
 			spin_unlock(&vma->vm_mm->page_table_lock);
 			current->mm->total_vm += pages;
 			if (vma->vm_flags & VM_LOCKED) {
 				current->mm->locked_vm += pages;
 				make_pages_present(addr + old_len,
 						   addr + new_len);
 			}
 			ret = addr;
 			goto out;
 		}
 	}

 	/*
 	 * We weren't able to just expand or shrink the area,
 	 * we need to create a new one and move it..
 	 */
 	ret = -ENOMEM;
 	if (flags & MREMAP_MAYMOVE) {
 		if (!(flags & MREMAP_FIXED)) {
 			unsigned long map_flags = 0;
 			if (vma->vm_flags & VM_SHARED)
 				map_flags |= MAP_SHARED;

 			new_addr = get_unmapped_area(vma->vm_file, 0, new_len, vma->vm_pgoff, map_flags);
 			ret = new_addr;
 			if (new_addr & ~PAGE_MASK)
 				goto out;
 		}
 		ret = move_vma(vma, addr, old_len, new_len, new_addr);
 	}
 out:
 	return ret;
 }

 asmlinkage unsigned long sys_mremap(unsigned long addr,
 	unsigned long old_len, unsigned long new_len,
 	unsigned long flags, unsigned long new_addr)
 {
 	unsigned long ret;

 	down_write(&current->mm->mmap_sem);
 	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
 	up_write(&current->mm->mmap_sem);
 	return ret;
 }
	/*
	* linux/mm/remap.c
	*
	* (C) Copyright 1996 Linus Torvalds
	*/

	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/smp_lock.h>
	#include <linux/shm.h>
	#include <linux/mman.h>
	#include <linux/swap.h>
	#include <linux/fs.h>
	#include <linux/highmem.h>

	#include <asm/uaccess.h>
	#include <asm/pgalloc.h>
	#include <asm/cacheflush.h>
	#include <asm/tlbflush.h>

	extern int vm_enough_memory(long pages);

	static inline pte_t get_one_pte_map_nested(struct mm_struct mm, unsigned long addr)
	{
	pgd_t * pgd;
	pmd_t * pmd;
	pte_t * pte = NULL;

	pgd = pgd_offset(mm, addr);
	if (pgd_none(*pgd))
	goto end;
	if (pgd_bad(*pgd)) {
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
	goto end;
	}

	pmd = pmd_offset(pgd, addr);
	if (pmd_none(*pmd))
	goto end;
	if (pmd_bad(*pmd)) {
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
	goto end;
	}

	pte = pte_offset_map_nested(pmd, addr);
	if (pte_none(*pte)) {
	pte_unmap_nested(pte);
	pte = NULL;
	}
	end:
	return pte;
	}

	static inline pte_t alloc_one_pte_map(struct mm_struct mm, unsigned long addr)
	{
	pmd_t * pmd;
	pte_t * pte = NULL;

	pmd = pmd_alloc(mm, pgd_offset(mm, addr), addr);
	if (pmd)
	pte = pte_alloc_map(mm, pmd, addr);
	return pte;
	}

	static inline int copy_one_pte(struct mm_struct mm, pte_t src, pte_t * dst)
	{
	int error = 0;
	pte_t pte;

	if (!pte_none(*src)) {
	pte = ptep_get_and_clear(src);
	if (!dst) {
	/* No dest? We must put it back. */
	dst = src;
	error++;
	}
	set_pte(dst, pte);
	}
	return error;
	}

	static int move_one_page(struct vm_area_struct *vma, unsigned long old_addr, unsigned long new_addr)
	{
	struct mm_struct *mm = vma->vm_mm;
	int error = 0;
	pte_t src, dst;

	spin_lock(&mm->page_table_lock);
	src = get_one_pte_map_nested(mm, old_addr);
	if (src) {
	dst = alloc_one_pte_map(mm, new_addr);
	error = copy_one_pte(mm, src, dst);
	pte_unmap_nested(src);
	pte_unmap(dst);
	}
	flush_tlb_page(vma, old_addr);
	spin_unlock(&mm->page_table_lock);
	return error;
	}

	static int move_page_tables(struct vm_area_struct *vma,
	unsigned long new_addr, unsigned long old_addr, unsigned long len)
	{
	unsigned long offset = len;

	flush_cache_range(vma, old_addr, old_addr + len);

	/*
	* This is not the clever way to do this, but we're taking the
	* easy way out on the assumption that most remappings will be
	* only a few pages.. This also makes error recovery easier.
	*/
	while (offset) {
	offset -= PAGE_SIZE;
	if (move_one_page(vma, old_addr + offset, new_addr + offset))
	goto oops_we_failed;
	}
	return 0;

	/*
	* Ok, the move failed because we didn't have enough pages for
	* the new page table tree. This is unlikely, but we have to
	* take the possibility into account. In that case we just move
	* all the pages back (this will work, because we still have
	* the old page tables)
	*/
	oops_we_failed:
	flush_cache_range(vma, new_addr, new_addr + len);
	while ((offset += PAGE_SIZE) < len)
	move_one_page(vma, new_addr + offset, old_addr + offset);
	zap_page_range(vma, new_addr, len);
	return -1;
	}

	static inline unsigned long move_vma(struct vm_area_struct * vma,
	unsigned long addr, unsigned long old_len, unsigned long new_len,
	unsigned long new_addr)
	{
	struct mm_struct * mm = vma->vm_mm;
	struct vm_area_struct * new_vma, * next, * prev;
	int allocated_vma;

	new_vma = NULL;
	next = find_vma_prev(mm, new_addr, &prev);
	if (next) {
	if (prev && prev->vm_end == new_addr &&
	can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
	spin_lock(&mm->page_table_lock);
	prev->vm_end = new_addr + new_len;
	spin_unlock(&mm->page_table_lock);
	new_vma = prev;
	if (next != prev->vm_next)
	BUG();
	if (prev->vm_end == next->vm_start && can_vma_merge(next, prev->vm_flags)) {
	spin_lock(&mm->page_table_lock);
	prev->vm_end = next->vm_end;
	__vma_unlink(mm, next, prev);
	spin_unlock(&mm->page_table_lock);

	mm->map_count--;
	kmem_cache_free(vm_area_cachep, next);
	}
	} else if (next->vm_start == new_addr + new_len &&
	can_vma_merge(next, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
	spin_lock(&mm->page_table_lock);
	next->vm_start = new_addr;
	spin_unlock(&mm->page_table_lock);
	new_vma = next;
	}
	} else {
	prev = find_vma(mm, new_addr-1);
	if (prev && prev->vm_end == new_addr &&
	can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
	spin_lock(&mm->page_table_lock);
	prev->vm_end = new_addr + new_len;
	spin_unlock(&mm->page_table_lock);
	new_vma = prev;
	}
	}

	allocated_vma = 0;
	if (!new_vma) {
	new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
	if (!new_vma)
	goto out;
	allocated_vma = 1;
	}

	if (!move_page_tables(vma, new_addr, addr, old_len)) {
	if (allocated_vma) {
	new_vma = vma;
	new_vma->vm_start = new_addr;
	new_vma->vm_end = new_addr+new_len;
	new_vma->vm_pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
	new_vma->vm_raend = 0;
	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);
	insert_vm_struct(current->mm, new_vma);
	}
	do_munmap(current->mm, addr, old_len);
	current->mm->total_vm += new_len >> PAGE_SHIFT;
	if (new_vma->vm_flags & VM_LOCKED) {
	current->mm->locked_vm += new_len >> PAGE_SHIFT;
	make_pages_present(new_vma->vm_start,
	new_vma->vm_end);
	}
	return new_addr;
	}
	if (allocated_vma)
	kmem_cache_free(vm_area_cachep, new_vma);
	out:
	return -ENOMEM;
	}

	/*
	* Expand (or shrink) an existing mapping, potentially moving it at the
	* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
	*
	* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
	* This option implies MREMAP_MAYMOVE.
	*/
	unsigned long do_mremap(unsigned long addr,
	unsigned long old_len, unsigned long new_len,
	unsigned long flags, unsigned long new_addr)
	{
	struct vm_area_struct *vma;
	unsigned long ret = -EINVAL;

	if (flags & ~(MREMAP_FIXED \| MREMAP_MAYMOVE))
	goto out;

	if (addr & ~PAGE_MASK)
	goto out;

	old_len = PAGE_ALIGN(old_len);
	new_len = PAGE_ALIGN(new_len);

	/* new_addr is only valid if MREMAP_FIXED is specified */
	if (flags & MREMAP_FIXED) {
	if (new_addr & ~PAGE_MASK)
	goto out;
	if (!(flags & MREMAP_MAYMOVE))
	goto out;

	if (new_len > TASK_SIZE \|\| new_addr > TASK_SIZE - new_len)
	goto out;

	/* Check if the location we're moving into overlaps the
	* old location at all, and fail if it does.
	*/
	if ((new_addr <= addr) && (new_addr+new_len) > addr)
	goto out;

	if ((addr <= new_addr) && (addr+old_len) > new_addr)
	goto out;

	do_munmap(current->mm, new_addr, new_len);
	}

	/*
	* Always allow a shrinking remap: that just unmaps
	* the unnecessary pages..
	*/
	ret = addr;
	if (old_len >= new_len) {
	do_munmap(current->mm, addr+new_len, old_len - new_len);
	if (!(flags & MREMAP_FIXED) \|\| (new_addr == addr))
	goto out;
	}

	/*
	* Ok, we need to grow.. or relocate.
	*/
	ret = -EFAULT;
	vma = find_vma(current->mm, addr);
	if (!vma \|\| vma->vm_start > addr)
	goto out;
	/* We can't remap across vm area boundaries */
	if (old_len > vma->vm_end - addr)
	goto out;
	if (vma->vm_flags & VM_DONTEXPAND) {
	if (new_len > old_len)
	goto out;
	}
	if (vma->vm_flags & VM_LOCKED) {
	unsigned long locked = current->mm->locked_vm << PAGE_SHIFT;
	locked += new_len - old_len;
	ret = -EAGAIN;
	if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
	goto out;
	}
	ret = -ENOMEM;
	if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
	> current->rlim[RLIMIT_AS].rlim_cur)
	goto out;
	/* Private writable mapping? Check memory availability.. */
	if ((vma->vm_flags & (VM_SHARED \| VM_WRITE)) == VM_WRITE &&
	!(flags & MAP_NORESERVE) &&
	!vm_enough_memory((new_len - old_len) >> PAGE_SHIFT))
	goto out;

	/* old_len exactly to the end of the area..
	* And we're not relocating the area.
	*/
	if (old_len == vma->vm_end - addr &&
	!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
	(old_len != new_len \|\| !(flags & MREMAP_MAYMOVE))) {
	unsigned long max_addr = TASK_SIZE;
	if (vma->vm_next)
	max_addr = vma->vm_next->vm_start;
	/* can we just expand the current mapping? */
	if (max_addr - addr >= new_len) {
	int pages = (new_len - old_len) >> PAGE_SHIFT;
	spin_lock(&vma->vm_mm->page_table_lock);
	vma->vm_end = addr + new_len;
	spin_unlock(&vma->vm_mm->page_table_lock);
	current->mm->total_vm += pages;
	if (vma->vm_flags & VM_LOCKED) {
	current->mm->locked_vm += pages;
	make_pages_present(addr + old_len,
	addr + new_len);
	}
	ret = addr;
	goto out;
	}
	}

	/*
	* We weren't able to just expand or shrink the area,
	* we need to create a new one and move it..
	*/
	ret = -ENOMEM;
	if (flags & MREMAP_MAYMOVE) {
	if (!(flags & MREMAP_FIXED)) {
	unsigned long map_flags = 0;
	if (vma->vm_flags & VM_SHARED)
	map_flags \|= MAP_SHARED;

	new_addr = get_unmapped_area(vma->vm_file, 0, new_len, vma->vm_pgoff, map_flags);
	ret = new_addr;
	if (new_addr & ~PAGE_MASK)
	goto out;
	}
	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	}
	out:
	return ret;
	}

	asmlinkage unsigned long sys_mremap(unsigned long addr,
	unsigned long old_len, unsigned long new_len,
	unsigned long flags, unsigned long new_addr)
	{
	unsigned long ret;

	down_write(&current->mm->mmap_sem);
	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	up_write(&current->mm->mmap_sem);
	return ret;
	}