[linux.git] / mm / mremap.c

/*
 *	mm/mremap.c
 *
 *	(C) Copyright 1996 Linus Torvalds
 *
 *	Address space accounting code	<[email protected]>
 *	(C) Copyright 2002 Red Hat Inc, All Rights Reserved
 */

#include <linux/mm.h>
#include <linux/hugetlb.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);
	split_huge_page_pmd(mm, pmd);
	if (pmd_none_or_clear_bad(pmd))
		return NULL;

	return pmd;
}

static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
			    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;

	VM_BUG_ON(pmd_trans_huge(*pmd));
	if (pmd_none(*pmd) && __pte_alloc(mm, vma, 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 truncate_pagecache
		 * 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(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(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, vma, 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;
}

static struct vm_area_struct *vma_to_resize(unsigned long addr,
	unsigned long old_len, unsigned long new_len, unsigned long *p)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma = find_vma(mm, addr);

	if (!vma || vma->vm_start > addr)
		goto Efault;

	if (is_vm_hugetlb_page(vma))
		goto Einval;

	/* We can't remap across vm area boundaries */
	if (old_len > vma->vm_end - addr)
		goto Efault;

	if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
		if (new_len > old_len)
			goto Efault;
	}

	if (vma->vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
		locked = mm->locked_vm << PAGE_SHIFT;
		lock_limit = rlimit(RLIMIT_MEMLOCK);
		locked += new_len - old_len;
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			goto Eagain;
	}

	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
		goto Enomem;

	if (vma->vm_flags & VM_ACCOUNT) {
		unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
		if (security_vm_enough_memory(charged))
			goto Efault;
		*p = charged;
	}

	return vma;

Efault:	/* very odd choice for most of the cases, but... */
	return ERR_PTR(-EFAULT);
Einval:
	return ERR_PTR(-EINVAL);
Enomem:
	return ERR_PTR(-ENOMEM);
Eagain:
	return ERR_PTR(-EAGAIN);
}

static unsigned long mremap_to(unsigned long addr,
	unsigned long old_len, unsigned long new_addr,
	unsigned long new_len)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long ret = -EINVAL;
	unsigned long charged = 0;
	unsigned long map_flags;

	if (new_addr & ~PAGE_MASK)
		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;

	if (old_len >= new_len) {
		ret = do_munmap(mm, addr+new_len, old_len - new_len);
		if (ret && old_len != new_len)
			goto out;
		old_len = new_len;
	}

	vma = vma_to_resize(addr, old_len, new_len, &charged);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto out;
	}

	map_flags = MAP_FIXED;
	if (vma->vm_flags & VM_MAYSHARE)
		map_flags |= MAP_SHARED;

	ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
				((addr - vma->vm_start) >> PAGE_SHIFT),
				map_flags);
	if (ret & ~PAGE_MASK)
		goto out1;

	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	if (!(ret & ~PAGE_MASK))
		goto out;
out1:
	vm_unacct_memory(charged);

out:
	return ret;
}

static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
{
	unsigned long end = vma->vm_end + delta;
	if (end < vma->vm_end) /* overflow */
		return 0;
	if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
		return 0;
	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
			      0, MAP_FIXED) & ~PAGE_MASK)
		return 0;
	return 1;
}

/*
 * 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;

	if (flags & MREMAP_FIXED) {
		if (flags & MREMAP_MAYMOVE)
			ret = mremap_to(addr, old_len, new_addr, new_len);
		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;
		goto out;
	}

	/*
	 * Ok, we need to grow..
	 */
	vma = vma_to_resize(addr, old_len, new_len, &charged);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto out;
	}

	/* old_len exactly to the end of the area..
	 */
	if (old_len == vma->vm_end - addr) {
		/* can we just expand the current mapping? */
		if (vma_expandable(vma, new_len - old_len)) {
			int pages = (new_len - old_len) >> PAGE_SHIFT;

			if (vma_adjust(vma, vma->vm_start, addr + new_len,
				       vma->vm_pgoff, NULL)) {
				ret = -ENOMEM;
				goto out;
			}

			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) {
		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 +
					((addr - vma->vm_start) >> PAGE_SHIFT),
					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);
	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 <[email protected]>
1da177e4 LT	7	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	8	*/
	9
	10	#include <linux/mm.h>
	11	#include <linux/hugetlb.h>
1da177e4	12	#include <linux/shm.h>
1ff82995	13	#include <linux/ksm.h>
1da177e4 LT	14	#include <linux/mman.h>
1da177e4 LT	15	#include <linux/swap.h>
c59ede7b	16	#include <linux/capability.h>
1da177e4 LT	17	#include <linux/fs.h>
	18	#include <linux/highmem.h>
	19	#include <linux/security.h>
	20	#include <linux/syscalls.h>
cddb8a5c	21	#include <linux/mmu_notifier.h>
1da177e4 LT	22
	23	#include <asm/uaccess.h>
	24	#include <asm/cacheflush.h>
	25	#include <asm/tlbflush.h>
	26
ba470de4 RR	27	#include "internal.h"
ba470de4 RR	28
7be7a546	29	static pmd_t get_old_pmd(struct mm_struct mm, unsigned long addr)
1da177e4 LT	30	{
	31	pgd_t *pgd;
	32	pud_t *pud;
	33	pmd_t *pmd;
	34
	35	pgd = pgd_offset(mm, addr);
	36	if (pgd_none_or_clear_bad(pgd))
	37	return NULL;
	38
	39	pud = pud_offset(pgd, addr);
	40	if (pud_none_or_clear_bad(pud))
	41	return NULL;
	42
	43	pmd = pmd_offset(pud, addr);
bae9c19b	44	split_huge_page_pmd(mm, pmd);
1da177e4 LT	45	if (pmd_none_or_clear_bad(pmd))
	46	return NULL;
	47
7be7a546	48	return pmd;
1da177e4 LT	49	}
1da177e4 LT	50
8ac1f832 AA	51	static pmd_t alloc_new_pmd(struct mm_struct mm, struct vm_area_struct *vma,
8ac1f832 AA	52	unsigned long addr)
1da177e4 LT	53	{
	54	pgd_t *pgd;
	55	pud_t *pud;
c74df32c	56	pmd_t *pmd;
1da177e4 LT	57
1da177e4 LT	58	pgd = pgd_offset(mm, addr);
1da177e4 LT	59	pud = pud_alloc(mm, pgd, addr);
1da177e4 LT	60	if (!pud)
c74df32c	61	return NULL;
7be7a546	62
1da177e4	63	pmd = pmd_alloc(mm, pud, addr);
7be7a546	64	if (!pmd)
c74df32c	65	return NULL;
7be7a546	66
8ac1f832 AA	67	VM_BUG_ON(pmd_trans_huge(*pmd));
8ac1f832 AA	68	if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
c74df32c HD	69	return NULL;
c74df32c HD	70
7be7a546	71	return pmd;
1da177e4 LT	72	}
1da177e4 LT	73
7be7a546 HD	74	static void move_ptes(struct vm_area_struct vma, pmd_t old_pmd,
	75	unsigned long old_addr, unsigned long old_end,
	76	struct vm_area_struct new_vma, pmd_t new_pmd,
	77	unsigned long new_addr)
1da177e4 LT	78	{
	79	struct address_space *mapping = NULL;
	80	struct mm_struct *mm = vma->vm_mm;
7be7a546	81	pte_t old_pte, new_pte, pte;
4c21e2f2	82	spinlock_t old_ptl, new_ptl;
cddb8a5c	83	unsigned long old_start;
1da177e4	84
cddb8a5c AA	85	old_start = old_addr;
	86	mmu_notifier_invalidate_range_start(vma->vm_mm,
	87	old_start, old_end);
1da177e4 LT	88	if (vma->vm_file) {
	89	/*
	90	* Subtle point from Rajesh Venkatasubramanian: before
25d9e2d1 NP	91	* moving file-based ptes, we must lock truncate_pagecache
25d9e2d1 NP	92	* out, since it might clean the dst vma before the src vma,
1da177e4 LT	93	* and we propagate stale pages into the dst afterward.
	94	*/
	95	mapping = vma->vm_file->f_mapping;
	96	spin_lock(&mapping->i_mmap_lock);
	97	if (new_vma->vm_truncate_count &&
	98	new_vma->vm_truncate_count != vma->vm_truncate_count)
	99	new_vma->vm_truncate_count = 0;
	100	}
1da177e4	101
4c21e2f2 HD	102	/*
	103	* We don't have to worry about the ordering of src and dst
	104	* pte locks because exclusive mmap_sem prevents deadlock.
	105	*/
c74df32c	106	old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
ece0e2b6	107	new_pte = pte_offset_map(new_pmd, new_addr);
4c21e2f2 HD	108	new_ptl = pte_lockptr(mm, new_pmd);
4c21e2f2 HD	109	if (new_ptl != old_ptl)
f20dc5f7	110	spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
6606c3e0	111	arch_enter_lazy_mmu_mode();
7be7a546 HD	112
	113	for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
	114	new_pte++, new_addr += PAGE_SIZE) {
	115	if (pte_none(*old_pte))
	116	continue;
	117	pte = ptep_clear_flush(vma, old_addr, old_pte);
7be7a546 HD	118	pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
7be7a546 HD	119	set_pte_at(mm, new_addr, new_pte, pte);
1da177e4	120	}
7be7a546	121
6606c3e0	122	arch_leave_lazy_mmu_mode();
4c21e2f2 HD	123	if (new_ptl != old_ptl)
4c21e2f2 HD	124	spin_unlock(new_ptl);
ece0e2b6	125	pte_unmap(new_pte - 1);
c74df32c	126	pte_unmap_unlock(old_pte - 1, old_ptl);
1da177e4 LT	127	if (mapping)
1da177e4 LT	128	spin_unlock(&mapping->i_mmap_lock);
cddb8a5c	129	mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
1da177e4 LT	130	}
1da177e4 LT	131
7be7a546 HD	132	#define LATENCY_LIMIT (64 * PAGE_SIZE)
7be7a546 HD	133
b6a2fea3	134	unsigned long move_page_tables(struct vm_area_struct *vma,
1da177e4 LT	135	unsigned long old_addr, struct vm_area_struct *new_vma,
	136	unsigned long new_addr, unsigned long len)
	137	{
7be7a546 HD	138	unsigned long extent, next, old_end;
7be7a546 HD	139	pmd_t old_pmd, new_pmd;
1da177e4	140
7be7a546 HD	141	old_end = old_addr + len;
7be7a546 HD	142	flush_cache_range(vma, old_addr, old_end);
1da177e4	143
7be7a546	144	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
1da177e4	145	cond_resched();
7be7a546 HD	146	next = (old_addr + PMD_SIZE) & PMD_MASK;
	147	if (next - 1 > old_end)
	148	next = old_end;
	149	extent = next - old_addr;
	150	old_pmd = get_old_pmd(vma->vm_mm, old_addr);
	151	if (!old_pmd)
	152	continue;
8ac1f832	153	new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
7be7a546 HD	154	if (!new_pmd)
	155	break;
	156	next = (new_addr + PMD_SIZE) & PMD_MASK;
	157	if (extent > next - new_addr)
	158	extent = next - new_addr;
	159	if (extent > LATENCY_LIMIT)
	160	extent = LATENCY_LIMIT;
	161	move_ptes(vma, old_pmd, old_addr, old_addr + extent,
	162	new_vma, new_pmd, new_addr);
1da177e4	163	}
7be7a546 HD	164
7be7a546 HD	165	return len + old_addr - old_end; /* how much done */
1da177e4 LT	166	}
	167
	168	static unsigned long move_vma(struct vm_area_struct *vma,
	169	unsigned long old_addr, unsigned long old_len,
	170	unsigned long new_len, unsigned long new_addr)
	171	{
	172	struct mm_struct *mm = vma->vm_mm;
	173	struct vm_area_struct *new_vma;
	174	unsigned long vm_flags = vma->vm_flags;
	175	unsigned long new_pgoff;
	176	unsigned long moved_len;
	177	unsigned long excess = 0;
365e9c87	178	unsigned long hiwater_vm;
1da177e4	179	int split = 0;
7103ad32	180	int err;
1da177e4 LT	181
	182	/*
	183	* We'd prefer to avoid failure later on in do_munmap:
	184	* which may split one vma into three before unmapping.
	185	*/
	186	if (mm->map_count >= sysctl_max_map_count - 3)
	187	return -ENOMEM;
	188
1ff82995 HD	189	/*
	190	* Advise KSM to break any KSM pages in the area to be moved:
	191	* it would be confusing if they were to turn up at the new
	192	* location, where they happen to coincide with different KSM
	193	* pages recently unmapped. But leave vma->vm_flags as it was,
	194	* so KSM can come around to merge on vma and new_vma afterwards.
	195	*/
7103ad32 HD	196	err = ksm_madvise(vma, old_addr, old_addr + old_len,
	197	MADV_UNMERGEABLE, &vm_flags);
	198	if (err)
	199	return err;
1ff82995	200
1da177e4 LT	201	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
	202	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
	203	if (!new_vma)
	204	return -ENOMEM;
	205
	206	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
	207	if (moved_len < old_len) {
	208	/*
	209	* On error, move entries back from new area to old,
	210	* which will succeed since page tables still there,
	211	* and then proceed to unmap new area instead of old.
	212	*/
	213	move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
	214	vma = new_vma;
	215	old_len = new_len;
	216	old_addr = new_addr;
	217	new_addr = -ENOMEM;
	218	}
	219
	220	/* Conceal VM_ACCOUNT so old reservation is not undone */
	221	if (vm_flags & VM_ACCOUNT) {
	222	vma->vm_flags &= ~VM_ACCOUNT;
	223	excess = vma->vm_end - vma->vm_start - old_len;
	224	if (old_addr > vma->vm_start &&
	225	old_addr + old_len < vma->vm_end)
	226	split = 1;
	227	}
	228
71799062	229	/*
365e9c87 HD	230	* If we failed to move page tables we still do total_vm increment
	231	* since do_munmap() will decrement it by old_len == new_len.
	232	*
	233	* Since total_vm is about to be raised artificially high for a
	234	* moment, we need to restore high watermark afterwards: if stats
	235	* are taken meanwhile, total_vm and hiwater_vm appear too high.
	236	* If this were a serious issue, we'd add a flag to do_munmap().
71799062	237	*/
365e9c87	238	hiwater_vm = mm->hiwater_vm;
71799062	239	mm->total_vm += new_len >> PAGE_SHIFT;
ab50b8ed	240	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
71799062	241
1da177e4 LT	242	if (do_munmap(mm, old_addr, old_len) < 0) {
	243	/* OOM: unable to split vma, just get accounts right */
	244	vm_unacct_memory(excess >> PAGE_SHIFT);
	245	excess = 0;
	246	}
365e9c87	247	mm->hiwater_vm = hiwater_vm;
1da177e4 LT	248
	249	/* Restore VM_ACCOUNT if one or two pieces of vma left */
	250	if (excess) {
	251	vma->vm_flags \|= VM_ACCOUNT;
	252	if (split)
	253	vma->vm_next->vm_flags \|= VM_ACCOUNT;
	254	}
	255
1da177e4 LT	256	if (vm_flags & VM_LOCKED) {
	257	mm->locked_vm += new_len >> PAGE_SHIFT;
	258	if (new_len > old_len)
ba470de4 RR	259	mlock_vma_pages_range(new_vma, new_addr + old_len,
ba470de4 RR	260	new_addr + new_len);
1da177e4 LT	261	}
	262
	263	return new_addr;
	264	}
	265
54f5de70 AV	266	static struct vm_area_struct *vma_to_resize(unsigned long addr,
	267	unsigned long old_len, unsigned long new_len, unsigned long *p)
	268	{
	269	struct mm_struct *mm = current->mm;
	270	struct vm_area_struct *vma = find_vma(mm, addr);
	271
	272	if (!vma \|\| vma->vm_start > addr)
	273	goto Efault;
	274
	275	if (is_vm_hugetlb_page(vma))
	276	goto Einval;
	277
	278	/* We can't remap across vm area boundaries */
	279	if (old_len > vma->vm_end - addr)
	280	goto Efault;
	281
	282	if (vma->vm_flags & (VM_DONTEXPAND \| VM_PFNMAP)) {
	283	if (new_len > old_len)
	284	goto Efault;
	285	}
	286
	287	if (vma->vm_flags & VM_LOCKED) {
	288	unsigned long locked, lock_limit;
	289	locked = mm->locked_vm << PAGE_SHIFT;
59e99e5b	290	lock_limit = rlimit(RLIMIT_MEMLOCK);
54f5de70 AV	291	locked += new_len - old_len;
	292	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
	293	goto Eagain;
	294	}
	295
	296	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
	297	goto Enomem;
	298
	299	if (vma->vm_flags & VM_ACCOUNT) {
	300	unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
	301	if (security_vm_enough_memory(charged))
	302	goto Efault;
	303	*p = charged;
	304	}
	305
	306	return vma;
	307
	308	Efault: /* very odd choice for most of the cases, but... */
	309	return ERR_PTR(-EFAULT);
	310	Einval:
	311	return ERR_PTR(-EINVAL);
	312	Enomem:
	313	return ERR_PTR(-ENOMEM);
	314	Eagain:
	315	return ERR_PTR(-EAGAIN);
	316	}
	317
ecc1a899 AV	318	static unsigned long mremap_to(unsigned long addr,
	319	unsigned long old_len, unsigned long new_addr,
	320	unsigned long new_len)
	321	{
	322	struct mm_struct *mm = current->mm;
	323	struct vm_area_struct *vma;
	324	unsigned long ret = -EINVAL;
	325	unsigned long charged = 0;
097eed10	326	unsigned long map_flags;
ecc1a899 AV	327
	328	if (new_addr & ~PAGE_MASK)
	329	goto out;
	330
	331	if (new_len > TASK_SIZE \|\| new_addr > TASK_SIZE - new_len)
	332	goto out;
	333
	334	/* Check if the location we're moving into overlaps the
	335	* old location at all, and fail if it does.
	336	*/
	337	if ((new_addr <= addr) && (new_addr+new_len) > addr)
	338	goto out;
	339
	340	if ((addr <= new_addr) && (addr+old_len) > new_addr)
	341	goto out;
	342
	343	ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
	344	if (ret)
	345	goto out;
	346
	347	ret = do_munmap(mm, new_addr, new_len);
	348	if (ret)
	349	goto out;
	350
	351	if (old_len >= new_len) {
	352	ret = do_munmap(mm, addr+new_len, old_len - new_len);
	353	if (ret && old_len != new_len)
	354	goto out;
	355	old_len = new_len;
	356	}
	357
	358	vma = vma_to_resize(addr, old_len, new_len, &charged);
	359	if (IS_ERR(vma)) {
	360	ret = PTR_ERR(vma);
	361	goto out;
	362	}
	363
097eed10 AV	364	map_flags = MAP_FIXED;
	365	if (vma->vm_flags & VM_MAYSHARE)
	366	map_flags \|= MAP_SHARED;
9206de95	367
097eed10 AV	368	ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
	369	((addr - vma->vm_start) >> PAGE_SHIFT),
	370	map_flags);
ecc1a899	371	if (ret & ~PAGE_MASK)
097eed10 AV	372	goto out1;
	373
	374	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	375	if (!(ret & ~PAGE_MASK))
	376	goto out;
	377	out1:
	378	vm_unacct_memory(charged);
ecc1a899 AV	379
	380	out:
	381	return ret;
	382	}
	383
1a0ef85f AV	384	static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
1a0ef85f AV	385	{
f106af4e	386	unsigned long end = vma->vm_end + delta;
9206de95	387	if (end < vma->vm_end) /* overflow */
f106af4e	388	return 0;
9206de95	389	if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
f106af4e AV	390	return 0;
	391	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
	392	0, MAP_FIXED) & ~PAGE_MASK)
1a0ef85f	393	return 0;
1a0ef85f AV	394	return 1;
	395	}
	396
1da177e4 LT	397	/*
	398	* Expand (or shrink) an existing mapping, potentially moving it at the
	399	* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
	400	*
	401	* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
	402	* This option implies MREMAP_MAYMOVE.
	403	*/
	404	unsigned long do_mremap(unsigned long addr,
	405	unsigned long old_len, unsigned long new_len,
	406	unsigned long flags, unsigned long new_addr)
	407	{
d0de32d9	408	struct mm_struct *mm = current->mm;
1da177e4 LT	409	struct vm_area_struct *vma;
	410	unsigned long ret = -EINVAL;
	411	unsigned long charged = 0;
	412
	413	if (flags & ~(MREMAP_FIXED \| MREMAP_MAYMOVE))
	414	goto out;
	415
	416	if (addr & ~PAGE_MASK)
	417	goto out;
	418
	419	old_len = PAGE_ALIGN(old_len);
	420	new_len = PAGE_ALIGN(new_len);
	421
	422	/*
	423	* We allow a zero old-len as a special case
	424	* for DOS-emu "duplicate shm area" thing. But
	425	* a zero new-len is nonsensical.
	426	*/
	427	if (!new_len)
	428	goto out;
	429
1da177e4	430	if (flags & MREMAP_FIXED) {
ecc1a899 AV	431	if (flags & MREMAP_MAYMOVE)
	432	ret = mremap_to(addr, old_len, new_addr, new_len);
	433	goto out;
1da177e4 LT	434	}
	435
	436	/*
	437	* Always allow a shrinking remap: that just unmaps
	438	* the unnecessary pages..
	439	* do_munmap does all the needed commit accounting
	440	*/
	441	if (old_len >= new_len) {
d0de32d9	442	ret = do_munmap(mm, addr+new_len, old_len - new_len);
1da177e4 LT	443	if (ret && old_len != new_len)
	444	goto out;
	445	ret = addr;
ecc1a899	446	goto out;
1da177e4 LT	447	}
	448
	449	/*
ecc1a899	450	* Ok, we need to grow..
1da177e4	451	*/
54f5de70 AV	452	vma = vma_to_resize(addr, old_len, new_len, &charged);
	453	if (IS_ERR(vma)) {
	454	ret = PTR_ERR(vma);
1da177e4	455	goto out;
119f657c	456	}
1da177e4	457
1da177e4	458	/* old_len exactly to the end of the area..
1da177e4	459	*/
ecc1a899	460	if (old_len == vma->vm_end - addr) {
1da177e4	461	/* can we just expand the current mapping? */
1a0ef85f	462	if (vma_expandable(vma, new_len - old_len)) {
1da177e4 LT	463	int pages = (new_len - old_len) >> PAGE_SHIFT;
1da177e4 LT	464
5beb4930 RR	465	if (vma_adjust(vma, vma->vm_start, addr + new_len,
	466	vma->vm_pgoff, NULL)) {
	467	ret = -ENOMEM;
	468	goto out;
	469	}
1da177e4	470
d0de32d9 HD	471	mm->total_vm += pages;
d0de32d9 HD	472	vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
1da177e4	473	if (vma->vm_flags & VM_LOCKED) {
d0de32d9	474	mm->locked_vm += pages;
ba470de4	475	mlock_vma_pages_range(vma, addr + old_len,
1da177e4 LT	476	addr + new_len);
	477	}
	478	ret = addr;
	479	goto out;
	480	}
	481	}
	482
	483	/*
	484	* We weren't able to just expand or shrink the area,
	485	* we need to create a new one and move it..
	486	*/
	487	ret = -ENOMEM;
	488	if (flags & MREMAP_MAYMOVE) {
ecc1a899 AV	489	unsigned long map_flags = 0;
	490	if (vma->vm_flags & VM_MAYSHARE)
	491	map_flags \|= MAP_SHARED;
	492
	493	new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
93587414 AV	494	vma->vm_pgoff +
	495	((addr - vma->vm_start) >> PAGE_SHIFT),
	496	map_flags);
ecc1a899 AV	497	if (new_addr & ~PAGE_MASK) {
	498	ret = new_addr;
	499	goto out;
1da177e4	500	}
ecc1a899 AV	501
	502	ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
	503	if (ret)
	504	goto out;
1da177e4 LT	505	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	506	}
	507	out:
	508	if (ret & ~PAGE_MASK)
	509	vm_unacct_memory(charged);
1da177e4 LT	510	return ret;
	511	}
	512
6a6160a7 HC	513	SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
	514	unsigned long, new_len, unsigned long, flags,
	515	unsigned long, new_addr)
1da177e4 LT	516	{
	517	unsigned long ret;
	518
	519	down_write(&current->mm->mmap_sem);
	520	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	521	up_write(&current->mm->mmap_sem);
	522	return ret;
	523	}