[net-next-2.6.git] / mm / mremap.c

/*
 *	mm/mremap.c
 *
 *	(C) Copyright 1996 Linus Torvalds
 *
 *	Address space accounting code	<alan@lxorguk.ukuu.org.uk>
 *	(C) Copyright 2002 Red Hat Inc, All Rights Reserved
 */

#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/ksm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/highmem.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/mmu_notifier.h>

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

#include "internal.h"

static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;

	pgd = pgd_offset(mm, addr);
	if (pgd_none_or_clear_bad(pgd))
		return NULL;

	pud = pud_offset(pgd, addr);
	if (pud_none_or_clear_bad(pud))
		return NULL;

	pmd = pmd_offset(pud, addr);
	if (pmd_none_or_clear_bad(pmd))
		return NULL;

	return pmd;
}

static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;

	pgd = pgd_offset(mm, addr);
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return NULL;

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return NULL;

	if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
		return NULL;

	return pmd;
}

static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
		unsigned long old_addr, unsigned long old_end,
		struct vm_area_struct *new_vma, pmd_t *new_pmd,
		unsigned long new_addr)
{
	struct address_space *mapping = NULL;
	struct mm_struct *mm = vma->vm_mm;
	pte_t *old_pte, *new_pte, pte;
	spinlock_t *old_ptl, *new_ptl;
	unsigned long old_start;

	old_start = old_addr;
	mmu_notifier_invalidate_range_start(vma->vm_mm,
					    old_start, old_end);
	if (vma->vm_file) {
		/*
		 * Subtle point from Rajesh Venkatasubramanian: before
		 * moving file-based ptes, we must lock vmtruncate out,
		 * since it might clean the dst vma before the src vma,
		 * and we propagate stale pages into the dst afterward.
		 */
		mapping = vma->vm_file->f_mapping;
		spin_lock(&mapping->i_mmap_lock);
		if (new_vma->vm_truncate_count &&
		    new_vma->vm_truncate_count != vma->vm_truncate_count)
			new_vma->vm_truncate_count = 0;
	}

	/*
	 * We don't have to worry about the ordering of src and dst
	 * pte locks because exclusive mmap_sem prevents deadlock.
	 */
	old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
 	new_pte = pte_offset_map_nested(new_pmd, new_addr);
	new_ptl = pte_lockptr(mm, new_pmd);
	if (new_ptl != old_ptl)
		spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
	arch_enter_lazy_mmu_mode();

	for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
				   new_pte++, new_addr += PAGE_SIZE) {
		if (pte_none(*old_pte))
			continue;
		pte = ptep_clear_flush(vma, old_addr, old_pte);
		pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
		set_pte_at(mm, new_addr, new_pte, pte);
	}

	arch_leave_lazy_mmu_mode();
	if (new_ptl != old_ptl)
		spin_unlock(new_ptl);
	pte_unmap_nested(new_pte - 1);
	pte_unmap_unlock(old_pte - 1, old_ptl);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);
	mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
}

#define LATENCY_LIMIT	(64 * PAGE_SIZE)

unsigned long move_page_tables(struct vm_area_struct *vma,
		unsigned long old_addr, struct vm_area_struct *new_vma,
		unsigned long new_addr, unsigned long len)
{
	unsigned long extent, next, old_end;
	pmd_t *old_pmd, *new_pmd;

	old_end = old_addr + len;
	flush_cache_range(vma, old_addr, old_end);

	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
		cond_resched();
		next = (old_addr + PMD_SIZE) & PMD_MASK;
		if (next - 1 > old_end)
			next = old_end;
		extent = next - old_addr;
		old_pmd = get_old_pmd(vma->vm_mm, old_addr);
		if (!old_pmd)
			continue;
		new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
		if (!new_pmd)
			break;
		next = (new_addr + PMD_SIZE) & PMD_MASK;
		if (extent > next - new_addr)
			extent = next - new_addr;
		if (extent > LATENCY_LIMIT)
			extent = LATENCY_LIMIT;
		move_ptes(vma, old_pmd, old_addr, old_addr + extent,
				new_vma, new_pmd, new_addr);
	}

	return len + old_addr - old_end;	/* how much done */
}

static unsigned long move_vma(struct vm_area_struct *vma,
		unsigned long old_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;
	unsigned long vm_flags = vma->vm_flags;
	unsigned long new_pgoff;
	unsigned long moved_len;
	unsigned long excess = 0;
	unsigned long hiwater_vm;
	int split = 0;
	int err;

	/*
	 * We'd prefer to avoid failure later on in do_munmap:
	 * which may split one vma into three before unmapping.
	 */
	if (mm->map_count >= sysctl_max_map_count - 3)
		return -ENOMEM;

	/*
	 * Advise KSM to break any KSM pages in the area to be moved:
	 * it would be confusing if they were to turn up at the new
	 * location, where they happen to coincide with different KSM
	 * pages recently unmapped.  But leave vma->vm_flags as it was,
	 * so KSM can come around to merge on vma and new_vma afterwards.
	 */
	err = ksm_madvise(vma, old_addr, old_addr + old_len,
						MADV_UNMERGEABLE, &vm_flags);
	if (err)
		return err;

	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
	if (!new_vma)
		return -ENOMEM;

	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
	if (moved_len < old_len) {
		/*
		 * On error, move entries back from new area to old,
		 * which will succeed since page tables still there,
		 * and then proceed to unmap new area instead of old.
		 */
		move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
		vma = new_vma;
		old_len = new_len;
		old_addr = new_addr;
		new_addr = -ENOMEM;
	}

	/* Conceal VM_ACCOUNT so old reservation is not undone */
	if (vm_flags & VM_ACCOUNT) {
		vma->vm_flags &= ~VM_ACCOUNT;
		excess = vma->vm_end - vma->vm_start - old_len;
		if (old_addr > vma->vm_start &&
		    old_addr + old_len < vma->vm_end)
			split = 1;
	}

	/*
	 * If we failed to move page tables we still do total_vm increment
	 * since do_munmap() will decrement it by old_len == new_len.
	 *
	 * Since total_vm is about to be raised artificially high for a
	 * moment, we need to restore high watermark afterwards: if stats
	 * are taken meanwhile, total_vm and hiwater_vm appear too high.
	 * If this were a serious issue, we'd add a flag to do_munmap().
	 */
	hiwater_vm = mm->hiwater_vm;
	mm->total_vm += new_len >> PAGE_SHIFT;
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);

	if (do_munmap(mm, old_addr, old_len) < 0) {
		/* OOM: unable to split vma, just get accounts right */
		vm_unacct_memory(excess >> PAGE_SHIFT);
		excess = 0;
	}
	mm->hiwater_vm = hiwater_vm;

	/* Restore VM_ACCOUNT if one or two pieces of vma left */
	if (excess) {
		vma->vm_flags |= VM_ACCOUNT;
		if (split)
			vma->vm_next->vm_flags |= VM_ACCOUNT;
	}

	if (vm_flags & VM_LOCKED) {
		mm->locked_vm += new_len >> PAGE_SHIFT;
		if (new_len > old_len)
			mlock_vma_pages_range(new_vma, new_addr + old_len,
						       new_addr + new_len);
	}

	return new_addr;
}

/*
 * 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 mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long ret = -EINVAL;
	unsigned long charged = 0;

	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);

	/*
	 * We allow a zero old-len as a special case
	 * for DOS-emu "duplicate shm area" thing. But
	 * a zero new-len is nonsensical.
	 */
	if (!new_len)
		goto out;

	/* 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;

		ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
		if (ret)
			goto out;

		ret = do_munmap(mm, new_addr, new_len);
		if (ret)
			goto out;
	}

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

	/*
	 * Ok, we need to grow..  or relocate.
	 */
	ret = -EFAULT;
	vma = find_vma(mm, addr);
	if (!vma || vma->vm_start > addr)
		goto out;
	if (is_vm_hugetlb_page(vma)) {
		ret = -EINVAL;
		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 | VM_PFNMAP)) {
		if (new_len > old_len)
			goto out;
	}
	if (vma->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 += new_len - old_len;
		ret = -EAGAIN;
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			goto out;
	}
	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
		ret = -ENOMEM;
		goto out;
	}

	if (vma->vm_flags & VM_ACCOUNT) {
		charged = (new_len - old_len) >> PAGE_SHIFT;
		if (security_vm_enough_memory(charged))
			goto out_nc;
	}

	/* 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;

			vma_adjust(vma, vma->vm_start,
				addr + new_len, vma->vm_pgoff, NULL);

			mm->total_vm += pages;
			vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
			if (vma->vm_flags & VM_LOCKED) {
				mm->locked_vm += pages;
				mlock_vma_pages_range(vma, 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_MAYSHARE)
				map_flags |= MAP_SHARED;

			new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
						vma->vm_pgoff, map_flags);
			if (new_addr & ~PAGE_MASK) {
				ret = new_addr;
				goto out;
			}

			ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
			if (ret)
				goto out;
		}
		ret = move_vma(vma, addr, old_len, new_len, new_addr);
	}
out:
	if (ret & ~PAGE_MASK)
		vm_unacct_memory(charged);
out_nc:
	return ret;
}

SYSCALL_DEFINE5(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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* mm/mremap.c
	3	*
	4	* (C) Copyright 1996 Linus Torvalds
	5	*
046c6884	6	* Address space accounting code <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	7	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	8	*/
	9
	10	#include <linux/mm.h>
	11	#include <linux/hugetlb.h>
	12	#include <linux/slab.h>
	13	#include <linux/shm.h>
1ff82995	14	#include <linux/ksm.h>
1da177e4 LT	15	#include <linux/mman.h>
1da177e4 LT	16	#include <linux/swap.h>
c59ede7b	17	#include <linux/capability.h>
1da177e4 LT	18	#include <linux/fs.h>
	19	#include <linux/highmem.h>
	20	#include <linux/security.h>
	21	#include <linux/syscalls.h>
cddb8a5c	22	#include <linux/mmu_notifier.h>
1da177e4 LT	23
	24	#include <asm/uaccess.h>
	25	#include <asm/cacheflush.h>
	26	#include <asm/tlbflush.h>
	27
ba470de4 RR	28	#include "internal.h"
ba470de4 RR	29
7be7a546	30	static pmd_t get_old_pmd(struct mm_struct mm, unsigned long addr)
1da177e4 LT	31	{
	32	pgd_t *pgd;
	33	pud_t *pud;
	34	pmd_t *pmd;
	35
	36	pgd = pgd_offset(mm, addr);
	37	if (pgd_none_or_clear_bad(pgd))
	38	return NULL;
	39
	40	pud = pud_offset(pgd, addr);
	41	if (pud_none_or_clear_bad(pud))
	42	return NULL;
	43
	44	pmd = pmd_offset(pud, addr);
	45	if (pmd_none_or_clear_bad(pmd))
	46	return NULL;
	47
7be7a546	48	return pmd;
1da177e4 LT	49	}
1da177e4 LT	50
7be7a546	51	static pmd_t alloc_new_pmd(struct mm_struct mm, unsigned long addr)
1da177e4 LT	52	{
	53	pgd_t *pgd;
	54	pud_t *pud;
c74df32c	55	pmd_t *pmd;
1da177e4 LT	56
1da177e4 LT	57	pgd = pgd_offset(mm, addr);
1da177e4 LT	58	pud = pud_alloc(mm, pgd, addr);
1da177e4 LT	59	if (!pud)
c74df32c	60	return NULL;
7be7a546	61
1da177e4	62	pmd = pmd_alloc(mm, pud, addr);
7be7a546	63	if (!pmd)
c74df32c	64	return NULL;
7be7a546	65
1bb3630e	66	if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
c74df32c HD	67	return NULL;
c74df32c HD	68
7be7a546	69	return pmd;
1da177e4 LT	70	}
1da177e4 LT	71
7be7a546 HD	72	static void move_ptes(struct vm_area_struct vma, pmd_t old_pmd,
	73	unsigned long old_addr, unsigned long old_end,
	74	struct vm_area_struct new_vma, pmd_t new_pmd,
	75	unsigned long new_addr)
1da177e4 LT	76	{
	77	struct address_space *mapping = NULL;
	78	struct mm_struct *mm = vma->vm_mm;
7be7a546	79	pte_t old_pte, new_pte, pte;
4c21e2f2	80	spinlock_t old_ptl, new_ptl;
cddb8a5c	81	unsigned long old_start;
1da177e4	82
cddb8a5c AA	83	old_start = old_addr;
	84	mmu_notifier_invalidate_range_start(vma->vm_mm,
	85	old_start, old_end);
1da177e4 LT	86	if (vma->vm_file) {
	87	/*
	88	* Subtle point from Rajesh Venkatasubramanian: before
	89	* moving file-based ptes, we must lock vmtruncate out,
	90	* since it might clean the dst vma before the src vma,
	91	* and we propagate stale pages into the dst afterward.
	92	*/
	93	mapping = vma->vm_file->f_mapping;
	94	spin_lock(&mapping->i_mmap_lock);
	95	if (new_vma->vm_truncate_count &&
	96	new_vma->vm_truncate_count != vma->vm_truncate_count)
	97	new_vma->vm_truncate_count = 0;
	98	}
1da177e4	99
4c21e2f2 HD	100	/*
	101	* We don't have to worry about the ordering of src and dst
	102	* pte locks because exclusive mmap_sem prevents deadlock.
	103	*/
c74df32c HD	104	old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
c74df32c HD	105	new_pte = pte_offset_map_nested(new_pmd, new_addr);
4c21e2f2 HD	106	new_ptl = pte_lockptr(mm, new_pmd);
4c21e2f2 HD	107	if (new_ptl != old_ptl)
f20dc5f7	108	spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
6606c3e0	109	arch_enter_lazy_mmu_mode();
7be7a546 HD	110
	111	for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
	112	new_pte++, new_addr += PAGE_SIZE) {
	113	if (pte_none(*old_pte))
	114	continue;
	115	pte = ptep_clear_flush(vma, old_addr, old_pte);
7be7a546 HD	116	pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
7be7a546 HD	117	set_pte_at(mm, new_addr, new_pte, pte);
1da177e4	118	}
7be7a546	119
6606c3e0	120	arch_leave_lazy_mmu_mode();
4c21e2f2 HD	121	if (new_ptl != old_ptl)
4c21e2f2 HD	122	spin_unlock(new_ptl);
7be7a546	123	pte_unmap_nested(new_pte - 1);
c74df32c	124	pte_unmap_unlock(old_pte - 1, old_ptl);
1da177e4 LT	125	if (mapping)
1da177e4 LT	126	spin_unlock(&mapping->i_mmap_lock);
cddb8a5c	127	mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
1da177e4 LT	128	}
1da177e4 LT	129
7be7a546 HD	130	#define LATENCY_LIMIT (64 * PAGE_SIZE)
7be7a546 HD	131
b6a2fea3	132	unsigned long move_page_tables(struct vm_area_struct *vma,
1da177e4 LT	133	unsigned long old_addr, struct vm_area_struct *new_vma,
	134	unsigned long new_addr, unsigned long len)
	135	{
7be7a546 HD	136	unsigned long extent, next, old_end;
7be7a546 HD	137	pmd_t old_pmd, new_pmd;
1da177e4	138
7be7a546 HD	139	old_end = old_addr + len;
7be7a546 HD	140	flush_cache_range(vma, old_addr, old_end);
1da177e4	141
7be7a546	142	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
1da177e4	143	cond_resched();
7be7a546 HD	144	next = (old_addr + PMD_SIZE) & PMD_MASK;
	145	if (next - 1 > old_end)
	146	next = old_end;
	147	extent = next - old_addr;
	148	old_pmd = get_old_pmd(vma->vm_mm, old_addr);
	149	if (!old_pmd)
	150	continue;
	151	new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
	152	if (!new_pmd)
	153	break;
	154	next = (new_addr + PMD_SIZE) & PMD_MASK;
	155	if (extent > next - new_addr)
	156	extent = next - new_addr;
	157	if (extent > LATENCY_LIMIT)
	158	extent = LATENCY_LIMIT;
	159	move_ptes(vma, old_pmd, old_addr, old_addr + extent,
	160	new_vma, new_pmd, new_addr);
1da177e4	161	}
7be7a546 HD	162
7be7a546 HD	163	return len + old_addr - old_end; /* how much done */
1da177e4 LT	164	}
	165
	166	static unsigned long move_vma(struct vm_area_struct *vma,
	167	unsigned long old_addr, unsigned long old_len,
	168	unsigned long new_len, unsigned long new_addr)
	169	{
	170	struct mm_struct *mm = vma->vm_mm;
	171	struct vm_area_struct *new_vma;
	172	unsigned long vm_flags = vma->vm_flags;
	173	unsigned long new_pgoff;
	174	unsigned long moved_len;
	175	unsigned long excess = 0;
365e9c87	176	unsigned long hiwater_vm;
1da177e4	177	int split = 0;
7103ad32	178	int err;
1da177e4 LT	179
	180	/*
	181	* We'd prefer to avoid failure later on in do_munmap:
	182	* which may split one vma into three before unmapping.
	183	*/
	184	if (mm->map_count >= sysctl_max_map_count - 3)
	185	return -ENOMEM;
	186
1ff82995 HD	187	/*
	188	* Advise KSM to break any KSM pages in the area to be moved:
	189	* it would be confusing if they were to turn up at the new
	190	* location, where they happen to coincide with different KSM
	191	* pages recently unmapped. But leave vma->vm_flags as it was,
	192	* so KSM can come around to merge on vma and new_vma afterwards.
	193	*/
7103ad32 HD	194	err = ksm_madvise(vma, old_addr, old_addr + old_len,
	195	MADV_UNMERGEABLE, &vm_flags);
	196	if (err)
	197	return err;
1ff82995	198
1da177e4 LT	199	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
	200	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
	201	if (!new_vma)
	202	return -ENOMEM;
	203
	204	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
	205	if (moved_len < old_len) {
	206	/*
	207	* On error, move entries back from new area to old,
	208	* which will succeed since page tables still there,
	209	* and then proceed to unmap new area instead of old.
	210	*/
	211	move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
	212	vma = new_vma;
	213	old_len = new_len;
	214	old_addr = new_addr;
	215	new_addr = -ENOMEM;
	216	}
	217
	218	/* Conceal VM_ACCOUNT so old reservation is not undone */
	219	if (vm_flags & VM_ACCOUNT) {
	220	vma->vm_flags &= ~VM_ACCOUNT;
	221	excess = vma->vm_end - vma->vm_start - old_len;
	222	if (old_addr > vma->vm_start &&
	223	old_addr + old_len < vma->vm_end)
	224	split = 1;
	225	}
	226
71799062	227	/*
365e9c87 HD	228	* If we failed to move page tables we still do total_vm increment
	229	* since do_munmap() will decrement it by old_len == new_len.
	230	*
	231	* Since total_vm is about to be raised artificially high for a
	232	* moment, we need to restore high watermark afterwards: if stats
	233	* are taken meanwhile, total_vm and hiwater_vm appear too high.
	234	* If this were a serious issue, we'd add a flag to do_munmap().
71799062	235	*/
365e9c87	236	hiwater_vm = mm->hiwater_vm;
71799062	237	mm->total_vm += new_len >> PAGE_SHIFT;
ab50b8ed	238	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
71799062	239
1da177e4 LT	240	if (do_munmap(mm, old_addr, old_len) < 0) {
	241	/* OOM: unable to split vma, just get accounts right */
	242	vm_unacct_memory(excess >> PAGE_SHIFT);
	243	excess = 0;
	244	}
365e9c87	245	mm->hiwater_vm = hiwater_vm;
1da177e4 LT	246
	247	/* Restore VM_ACCOUNT if one or two pieces of vma left */
	248	if (excess) {
	249	vma->vm_flags \|= VM_ACCOUNT;
	250	if (split)
	251	vma->vm_next->vm_flags \|= VM_ACCOUNT;
	252	}
	253
1da177e4 LT	254	if (vm_flags & VM_LOCKED) {
	255	mm->locked_vm += new_len >> PAGE_SHIFT;
	256	if (new_len > old_len)
ba470de4 RR	257	mlock_vma_pages_range(new_vma, new_addr + old_len,
ba470de4 RR	258	new_addr + new_len);
1da177e4 LT	259	}
	260
	261	return new_addr;
	262	}
	263
	264	/*
	265	* Expand (or shrink) an existing mapping, potentially moving it at the
	266	* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
	267	*
	268	* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
	269	* This option implies MREMAP_MAYMOVE.
	270	*/
	271	unsigned long do_mremap(unsigned long addr,
	272	unsigned long old_len, unsigned long new_len,
	273	unsigned long flags, unsigned long new_addr)
	274	{
d0de32d9	275	struct mm_struct *mm = current->mm;
1da177e4 LT	276	struct vm_area_struct *vma;
	277	unsigned long ret = -EINVAL;
	278	unsigned long charged = 0;
	279
	280	if (flags & ~(MREMAP_FIXED \| MREMAP_MAYMOVE))
	281	goto out;
	282
	283	if (addr & ~PAGE_MASK)
	284	goto out;
	285
	286	old_len = PAGE_ALIGN(old_len);
	287	new_len = PAGE_ALIGN(new_len);
	288
	289	/*
	290	* We allow a zero old-len as a special case
	291	* for DOS-emu "duplicate shm area" thing. But
	292	* a zero new-len is nonsensical.
	293	*/
	294	if (!new_len)
	295	goto out;
	296
	297	/* new_addr is only valid if MREMAP_FIXED is specified */
	298	if (flags & MREMAP_FIXED) {
	299	if (new_addr & ~PAGE_MASK)
	300	goto out;
	301	if (!(flags & MREMAP_MAYMOVE))
	302	goto out;
	303
	304	if (new_len > TASK_SIZE \|\| new_addr > TASK_SIZE - new_len)
	305	goto out;
	306
	307	/* Check if the location we're moving into overlaps the
	308	* old location at all, and fail if it does.
	309	*/
	310	if ((new_addr <= addr) && (new_addr+new_len) > addr)
	311	goto out;
	312
	313	if ((addr <= new_addr) && (addr+old_len) > new_addr)
	314	goto out;
	315
c80544dc	316	ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
ed032189 EP	317	if (ret)
	318	goto out;
	319
d0de32d9	320	ret = do_munmap(mm, new_addr, new_len);
1da177e4 LT	321	if (ret)
	322	goto out;
	323	}
	324
	325	/*
	326	* Always allow a shrinking remap: that just unmaps
	327	* the unnecessary pages..
	328	* do_munmap does all the needed commit accounting
	329	*/
	330	if (old_len >= new_len) {
d0de32d9	331	ret = do_munmap(mm, addr+new_len, old_len - new_len);
1da177e4 LT	332	if (ret && old_len != new_len)
	333	goto out;
	334	ret = addr;
	335	if (!(flags & MREMAP_FIXED) \|\| (new_addr == addr))
	336	goto out;
	337	old_len = new_len;
	338	}
	339
	340	/*
	341	* Ok, we need to grow.. or relocate.
	342	*/
	343	ret = -EFAULT;
d0de32d9	344	vma = find_vma(mm, addr);
1da177e4 LT	345	if (!vma \|\| vma->vm_start > addr)
	346	goto out;
	347	if (is_vm_hugetlb_page(vma)) {
	348	ret = -EINVAL;
	349	goto out;
	350	}
	351	/* We can't remap across vm area boundaries */
	352	if (old_len > vma->vm_end - addr)
	353	goto out;
4d7672b4	354	if (vma->vm_flags & (VM_DONTEXPAND \| VM_PFNMAP)) {
1da177e4 LT	355	if (new_len > old_len)
	356	goto out;
	357	}
	358	if (vma->vm_flags & VM_LOCKED) {
	359	unsigned long locked, lock_limit;
d0de32d9	360	locked = mm->locked_vm << PAGE_SHIFT;
1da177e4 LT	361	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
	362	locked += new_len - old_len;
	363	ret = -EAGAIN;
	364	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
	365	goto out;
	366	}
d0de32d9	367	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
119f657c	368	ret = -ENOMEM;
1da177e4	369	goto out;
119f657c	370	}
1da177e4 LT	371
	372	if (vma->vm_flags & VM_ACCOUNT) {
	373	charged = (new_len - old_len) >> PAGE_SHIFT;
	374	if (security_vm_enough_memory(charged))
	375	goto out_nc;
	376	}
	377
	378	/* old_len exactly to the end of the area..
	379	* And we're not relocating the area.
	380	*/
	381	if (old_len == vma->vm_end - addr &&
	382	!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
	383	(old_len != new_len \|\| !(flags & MREMAP_MAYMOVE))) {
	384	unsigned long max_addr = TASK_SIZE;
	385	if (vma->vm_next)
	386	max_addr = vma->vm_next->vm_start;
	387	/* can we just expand the current mapping? */
	388	if (max_addr - addr >= new_len) {
	389	int pages = (new_len - old_len) >> PAGE_SHIFT;
	390
	391	vma_adjust(vma, vma->vm_start,
	392	addr + new_len, vma->vm_pgoff, NULL);
	393
d0de32d9 HD	394	mm->total_vm += pages;
d0de32d9 HD	395	vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
1da177e4	396	if (vma->vm_flags & VM_LOCKED) {
d0de32d9	397	mm->locked_vm += pages;
ba470de4	398	mlock_vma_pages_range(vma, addr + old_len,
1da177e4 LT	399	addr + new_len);
	400	}
	401	ret = addr;
	402	goto out;
	403	}
	404	}
	405
	406	/*
	407	* We weren't able to just expand or shrink the area,
	408	* we need to create a new one and move it..
	409	*/
	410	ret = -ENOMEM;
	411	if (flags & MREMAP_MAYMOVE) {
	412	if (!(flags & MREMAP_FIXED)) {
	413	unsigned long map_flags = 0;
	414	if (vma->vm_flags & VM_MAYSHARE)
	415	map_flags \|= MAP_SHARED;
	416
	417	new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
	418	vma->vm_pgoff, map_flags);
ed032189 EP	419	if (new_addr & ~PAGE_MASK) {
	420	ret = new_addr;
	421	goto out;
	422	}
	423
c80544dc	424	ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
ed032189	425	if (ret)
1da177e4 LT	426	goto out;
	427	}
	428	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	429	}
	430	out:
	431	if (ret & ~PAGE_MASK)
	432	vm_unacct_memory(charged);
	433	out_nc:
	434	return ret;
	435	}
	436
6a6160a7 HC	437	SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
	438	unsigned long, new_len, unsigned long, flags,
	439	unsigned long, new_addr)
1da177e4 LT	440	{
	441	unsigned long ret;
	442
	443	down_write(&current->mm->mmap_sem);
	444	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	445	up_write(&current->mm->mmap_sem);
	446	return ret;
	447	}