[linux-2.6-block.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/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(*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));

	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, bool need_rmap_locks)
{
	struct address_space *mapping = NULL;
	struct anon_vma *anon_vma = NULL;
	struct mm_struct *mm = vma->vm_mm;
	pte_t *old_pte, *new_pte, pte;
	spinlock_t *old_ptl, *new_ptl;

	/*
	 * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma
	 * locks to ensure that rmap will always observe either the old or the
	 * new ptes. This is the easiest way to avoid races with
	 * truncate_pagecache(), page migration, etc...
	 *
	 * When need_rmap_locks is false, we use other ways to avoid
	 * such races:
	 *
	 * - During exec() shift_arg_pages(), we use a specially tagged vma
	 *   which rmap call sites look for using is_vma_temporary_stack().
	 *
	 * - During mremap(), new_vma is often known to be placed after vma
	 *   in rmap traversal order. This ensures rmap will always observe
	 *   either the old pte, or the new pte, or both (the page table locks
	 *   serialize access to individual ptes, but only rmap traversal
	 *   order guarantees that we won't miss both the old and new ptes).
	 */
	if (need_rmap_locks) {
		if (vma->vm_file) {
			mapping = vma->vm_file->f_mapping;
			mutex_lock(&mapping->i_mmap_mutex);
		}
		if (vma->anon_vma) {
			anon_vma = vma->anon_vma;
			anon_vma_lock_write(anon_vma);
		}
	}

	/*
	 * 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_get_and_clear(mm, 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 (anon_vma)
		anon_vma_unlock(anon_vma);
	if (mapping)
		mutex_unlock(&mapping->i_mmap_mutex);
}

#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,
		bool need_rmap_locks)
{
	unsigned long extent, next, old_end;
	pmd_t *old_pmd, *new_pmd;
	bool need_flush = false;
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */

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

	mmun_start = old_addr;
	mmun_end   = old_end;
	mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);

	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
		cond_resched();
		next = (old_addr + PMD_SIZE) & PMD_MASK;
		/* even if next overflowed, extent below will be ok */
		extent = next - old_addr;
		if (extent > old_end - old_addr)
			extent = old_end - 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;
		if (pmd_trans_huge(*old_pmd)) {
			int err = 0;
			if (extent == HPAGE_PMD_SIZE)
				err = move_huge_pmd(vma, new_vma, old_addr,
						    new_addr, old_end,
						    old_pmd, new_pmd);
			if (err > 0) {
				need_flush = true;
				continue;
			} else if (!err) {
				split_huge_page_pmd(vma, old_addr, old_pmd);
			}
			VM_BUG_ON(pmd_trans_huge(*old_pmd));
		}
		if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
						      new_pmd, new_addr))
			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, need_rmap_locks);
		need_flush = true;
	}
	if (likely(need_flush))
		flush_tlb_range(vma, old_end-len, old_addr);

	mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);

	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;
	bool need_rmap_locks;

	/*
	 * 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,
			   &need_rmap_locks);
	if (!new_vma)
		return -ENOMEM;

	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
				     need_rmap_locks);
	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,
				 true);
		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;
	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;

	/* Need to be careful about a growing mapping */
	if (new_len > old_len) {
		unsigned long pgoff;

		if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
			goto Efault;
		pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
		pgoff += vma->vm_pgoff;
		if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
			goto Einval;
	}

	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_mm(mm, 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 = 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.
 */
SYSCALL_DEFINE5(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;

	down_write(&current->mm->mmap_sem);

	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;
			}

			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 = move_vma(vma, addr, old_len, new_len, new_addr);
	}
out:
	if (ret & ~PAGE_MASK)
		vm_unacct_memory(charged);
	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>
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);
37a1c49a	44	if (pmd_none(*pmd))
1da177e4 LT	45	return NULL;
1da177e4 LT	46
7be7a546	47	return pmd;
1da177e4 LT	48	}
1da177e4 LT	49
8ac1f832 AA	50	static pmd_t alloc_new_pmd(struct mm_struct mm, struct vm_area_struct *vma,
8ac1f832 AA	51	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
8ac1f832	66	VM_BUG_ON(pmd_trans_huge(*pmd));
c74df32c	67
7be7a546	68	return pmd;
1da177e4 LT	69	}
1da177e4 LT	70
7be7a546 HD	71	static void move_ptes(struct vm_area_struct vma, pmd_t old_pmd,
	72	unsigned long old_addr, unsigned long old_end,
	73	struct vm_area_struct new_vma, pmd_t new_pmd,
38a76013	74	unsigned long new_addr, bool need_rmap_locks)
1da177e4 LT	75	{
1da177e4 LT	76	struct address_space *mapping = NULL;
38a76013	77	struct anon_vma *anon_vma = NULL;
1da177e4	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;
1da177e4	81
38a76013 ML	82	/*
	83	* When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma
	84	* locks to ensure that rmap will always observe either the old or the
	85	* new ptes. This is the easiest way to avoid races with
	86	* truncate_pagecache(), page migration, etc...
	87	*
	88	* When need_rmap_locks is false, we use other ways to avoid
	89	* such races:
	90	*
	91	* - During exec() shift_arg_pages(), we use a specially tagged vma
	92	* which rmap call sites look for using is_vma_temporary_stack().
	93	*
	94	* - During mremap(), new_vma is often known to be placed after vma
	95	* in rmap traversal order. This ensures rmap will always observe
	96	* either the old pte, or the new pte, or both (the page table locks
	97	* serialize access to individual ptes, but only rmap traversal
	98	* order guarantees that we won't miss both the old and new ptes).
	99	*/
	100	if (need_rmap_locks) {
	101	if (vma->vm_file) {
	102	mapping = vma->vm_file->f_mapping;
	103	mutex_lock(&mapping->i_mmap_mutex);
	104	}
	105	if (vma->anon_vma) {
	106	anon_vma = vma->anon_vma;
4fc3f1d6	107	anon_vma_lock_write(anon_vma);
38a76013	108	}
1da177e4	109	}
1da177e4	110
4c21e2f2 HD	111	/*
	112	* We don't have to worry about the ordering of src and dst
	113	* pte locks because exclusive mmap_sem prevents deadlock.
	114	*/
c74df32c	115	old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
ece0e2b6	116	new_pte = pte_offset_map(new_pmd, new_addr);
4c21e2f2 HD	117	new_ptl = pte_lockptr(mm, new_pmd);
4c21e2f2 HD	118	if (new_ptl != old_ptl)
f20dc5f7	119	spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
6606c3e0	120	arch_enter_lazy_mmu_mode();
7be7a546 HD	121
	122	for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
	123	new_pte++, new_addr += PAGE_SIZE) {
	124	if (pte_none(*old_pte))
	125	continue;
7b6efc2b	126	pte = ptep_get_and_clear(mm, old_addr, old_pte);
7be7a546 HD	127	pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
7be7a546 HD	128	set_pte_at(mm, new_addr, new_pte, pte);
1da177e4	129	}
7be7a546	130
6606c3e0	131	arch_leave_lazy_mmu_mode();
4c21e2f2 HD	132	if (new_ptl != old_ptl)
4c21e2f2 HD	133	spin_unlock(new_ptl);
ece0e2b6	134	pte_unmap(new_pte - 1);
c74df32c	135	pte_unmap_unlock(old_pte - 1, old_ptl);
108d6642 ML	136	if (anon_vma)
108d6642 ML	137	anon_vma_unlock(anon_vma);
1da177e4	138	if (mapping)
3d48ae45	139	mutex_unlock(&mapping->i_mmap_mutex);
1da177e4 LT	140	}
1da177e4 LT	141
7be7a546 HD	142	#define LATENCY_LIMIT (64 * PAGE_SIZE)
7be7a546 HD	143
b6a2fea3	144	unsigned long move_page_tables(struct vm_area_struct *vma,
1da177e4	145	unsigned long old_addr, struct vm_area_struct *new_vma,
38a76013 ML	146	unsigned long new_addr, unsigned long len,
38a76013 ML	147	bool need_rmap_locks)
1da177e4	148	{
7be7a546 HD	149	unsigned long extent, next, old_end;
7be7a546 HD	150	pmd_t old_pmd, new_pmd;
7b6efc2b	151	bool need_flush = false;
2ec74c3e SG	152	unsigned long mmun_start; /* For mmu_notifiers */
2ec74c3e SG	153	unsigned long mmun_end; /* For mmu_notifiers */
1da177e4	154
7be7a546 HD	155	old_end = old_addr + len;
7be7a546 HD	156	flush_cache_range(vma, old_addr, old_end);
1da177e4	157
2ec74c3e SG	158	mmun_start = old_addr;
	159	mmun_end = old_end;
	160	mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
7b6efc2b	161
7be7a546	162	for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
1da177e4	163	cond_resched();
7be7a546	164	next = (old_addr + PMD_SIZE) & PMD_MASK;
ebed4846	165	/* even if next overflowed, extent below will be ok */
7be7a546	166	extent = next - old_addr;
ebed4846 AA	167	if (extent > old_end - old_addr)
ebed4846 AA	168	extent = old_end - old_addr;
7be7a546 HD	169	old_pmd = get_old_pmd(vma->vm_mm, old_addr);
	170	if (!old_pmd)
	171	continue;
8ac1f832	172	new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
7be7a546 HD	173	if (!new_pmd)
7be7a546 HD	174	break;
37a1c49a AA	175	if (pmd_trans_huge(*old_pmd)) {
	176	int err = 0;
	177	if (extent == HPAGE_PMD_SIZE)
	178	err = move_huge_pmd(vma, new_vma, old_addr,
	179	new_addr, old_end,
	180	old_pmd, new_pmd);
	181	if (err > 0) {
	182	need_flush = true;
	183	continue;
	184	} else if (!err) {
e180377f	185	split_huge_page_pmd(vma, old_addr, old_pmd);
37a1c49a AA	186	}
	187	VM_BUG_ON(pmd_trans_huge(*old_pmd));
	188	}
	189	if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
	190	new_pmd, new_addr))
	191	break;
7be7a546 HD	192	next = (new_addr + PMD_SIZE) & PMD_MASK;
	193	if (extent > next - new_addr)
	194	extent = next - new_addr;
	195	if (extent > LATENCY_LIMIT)
	196	extent = LATENCY_LIMIT;
	197	move_ptes(vma, old_pmd, old_addr, old_addr + extent,
38a76013	198	new_vma, new_pmd, new_addr, need_rmap_locks);
7b6efc2b	199	need_flush = true;
1da177e4	200	}
7b6efc2b AA	201	if (likely(need_flush))
	202	flush_tlb_range(vma, old_end-len, old_addr);
	203
2ec74c3e	204	mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
7be7a546 HD	205
7be7a546 HD	206	return len + old_addr - old_end; /* how much done */
1da177e4 LT	207	}
	208
	209	static unsigned long move_vma(struct vm_area_struct *vma,
	210	unsigned long old_addr, unsigned long old_len,
	211	unsigned long new_len, unsigned long new_addr)
	212	{
	213	struct mm_struct *mm = vma->vm_mm;
	214	struct vm_area_struct *new_vma;
	215	unsigned long vm_flags = vma->vm_flags;
	216	unsigned long new_pgoff;
	217	unsigned long moved_len;
	218	unsigned long excess = 0;
365e9c87	219	unsigned long hiwater_vm;
1da177e4	220	int split = 0;
7103ad32	221	int err;
38a76013	222	bool need_rmap_locks;
1da177e4 LT	223
	224	/*
	225	* We'd prefer to avoid failure later on in do_munmap:
	226	* which may split one vma into three before unmapping.
	227	*/
	228	if (mm->map_count >= sysctl_max_map_count - 3)
	229	return -ENOMEM;
	230
1ff82995 HD	231	/*
	232	* Advise KSM to break any KSM pages in the area to be moved:
	233	* it would be confusing if they were to turn up at the new
	234	* location, where they happen to coincide with different KSM
	235	* pages recently unmapped. But leave vma->vm_flags as it was,
	236	* so KSM can come around to merge on vma and new_vma afterwards.
	237	*/
7103ad32 HD	238	err = ksm_madvise(vma, old_addr, old_addr + old_len,
	239	MADV_UNMERGEABLE, &vm_flags);
	240	if (err)
	241	return err;
1ff82995	242
1da177e4	243	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
38a76013 ML	244	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
38a76013 ML	245	&need_rmap_locks);
1da177e4 LT	246	if (!new_vma)
	247	return -ENOMEM;
	248
38a76013 ML	249	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
38a76013 ML	250	need_rmap_locks);
1da177e4 LT	251	if (moved_len < old_len) {
	252	/*
	253	* On error, move entries back from new area to old,
	254	* which will succeed since page tables still there,
	255	* and then proceed to unmap new area instead of old.
	256	*/
38a76013 ML	257	move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
38a76013 ML	258	true);
1da177e4 LT	259	vma = new_vma;
	260	old_len = new_len;
	261	old_addr = new_addr;
	262	new_addr = -ENOMEM;
	263	}
	264
	265	/* Conceal VM_ACCOUNT so old reservation is not undone */
	266	if (vm_flags & VM_ACCOUNT) {
	267	vma->vm_flags &= ~VM_ACCOUNT;
	268	excess = vma->vm_end - vma->vm_start - old_len;
	269	if (old_addr > vma->vm_start &&
	270	old_addr + old_len < vma->vm_end)
	271	split = 1;
	272	}
	273
71799062	274	/*
365e9c87 HD	275	* If we failed to move page tables we still do total_vm increment
	276	* since do_munmap() will decrement it by old_len == new_len.
	277	*
	278	* Since total_vm is about to be raised artificially high for a
	279	* moment, we need to restore high watermark afterwards: if stats
	280	* are taken meanwhile, total_vm and hiwater_vm appear too high.
	281	* If this were a serious issue, we'd add a flag to do_munmap().
71799062	282	*/
365e9c87	283	hiwater_vm = mm->hiwater_vm;
ab50b8ed	284	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
71799062	285
1da177e4 LT	286	if (do_munmap(mm, old_addr, old_len) < 0) {
	287	/* OOM: unable to split vma, just get accounts right */
	288	vm_unacct_memory(excess >> PAGE_SHIFT);
	289	excess = 0;
	290	}
365e9c87	291	mm->hiwater_vm = hiwater_vm;
1da177e4 LT	292
	293	/* Restore VM_ACCOUNT if one or two pieces of vma left */
	294	if (excess) {
	295	vma->vm_flags \|= VM_ACCOUNT;
	296	if (split)
	297	vma->vm_next->vm_flags \|= VM_ACCOUNT;
	298	}
	299
1da177e4 LT	300	if (vm_flags & VM_LOCKED) {
	301	mm->locked_vm += new_len >> PAGE_SHIFT;
	302	if (new_len > old_len)
ba470de4 RR	303	mlock_vma_pages_range(new_vma, new_addr + old_len,
ba470de4 RR	304	new_addr + new_len);
1da177e4 LT	305	}
	306
	307	return new_addr;
	308	}
	309
54f5de70 AV	310	static struct vm_area_struct *vma_to_resize(unsigned long addr,
	311	unsigned long old_len, unsigned long new_len, unsigned long *p)
	312	{
	313	struct mm_struct *mm = current->mm;
	314	struct vm_area_struct *vma = find_vma(mm, addr);
	315
	316	if (!vma \|\| vma->vm_start > addr)
	317	goto Efault;
	318
	319	if (is_vm_hugetlb_page(vma))
	320	goto Einval;
	321
	322	/* We can't remap across vm area boundaries */
	323	if (old_len > vma->vm_end - addr)
	324	goto Efault;
	325
982134ba LT	326	/* Need to be careful about a growing mapping */
	327	if (new_len > old_len) {
	328	unsigned long pgoff;
	329
	330	if (vma->vm_flags & (VM_DONTEXPAND \| VM_PFNMAP))
54f5de70	331	goto Efault;
982134ba LT	332	pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
	333	pgoff += vma->vm_pgoff;
	334	if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
	335	goto Einval;
54f5de70 AV	336	}
	337
	338	if (vma->vm_flags & VM_LOCKED) {
	339	unsigned long locked, lock_limit;
	340	locked = mm->locked_vm << PAGE_SHIFT;
59e99e5b	341	lock_limit = rlimit(RLIMIT_MEMLOCK);
54f5de70 AV	342	locked += new_len - old_len;
	343	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
	344	goto Eagain;
	345	}
	346
	347	if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
	348	goto Enomem;
	349
	350	if (vma->vm_flags & VM_ACCOUNT) {
	351	unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
191c5424	352	if (security_vm_enough_memory_mm(mm, charged))
54f5de70 AV	353	goto Efault;
	354	*p = charged;
	355	}
	356
	357	return vma;
	358
	359	Efault: /* very odd choice for most of the cases, but... */
	360	return ERR_PTR(-EFAULT);
	361	Einval:
	362	return ERR_PTR(-EINVAL);
	363	Enomem:
	364	return ERR_PTR(-ENOMEM);
	365	Eagain:
	366	return ERR_PTR(-EAGAIN);
	367	}
	368
ecc1a899 AV	369	static unsigned long mremap_to(unsigned long addr,
	370	unsigned long old_len, unsigned long new_addr,
	371	unsigned long new_len)
	372	{
	373	struct mm_struct *mm = current->mm;
	374	struct vm_area_struct *vma;
	375	unsigned long ret = -EINVAL;
	376	unsigned long charged = 0;
097eed10	377	unsigned long map_flags;
ecc1a899 AV	378
	379	if (new_addr & ~PAGE_MASK)
	380	goto out;
	381
	382	if (new_len > TASK_SIZE \|\| new_addr > TASK_SIZE - new_len)
	383	goto out;
	384
	385	/* Check if the location we're moving into overlaps the
	386	* old location at all, and fail if it does.
	387	*/
	388	if ((new_addr <= addr) && (new_addr+new_len) > addr)
	389	goto out;
	390
	391	if ((addr <= new_addr) && (addr+old_len) > new_addr)
	392	goto out;
	393
ecc1a899 AV	394	ret = do_munmap(mm, new_addr, new_len);
	395	if (ret)
	396	goto out;
	397
	398	if (old_len >= new_len) {
	399	ret = do_munmap(mm, addr+new_len, old_len - new_len);
	400	if (ret && old_len != new_len)
	401	goto out;
	402	old_len = new_len;
	403	}
	404
	405	vma = vma_to_resize(addr, old_len, new_len, &charged);
	406	if (IS_ERR(vma)) {
	407	ret = PTR_ERR(vma);
	408	goto out;
	409	}
	410
097eed10 AV	411	map_flags = MAP_FIXED;
	412	if (vma->vm_flags & VM_MAYSHARE)
	413	map_flags \|= MAP_SHARED;
9206de95	414
097eed10 AV	415	ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
	416	((addr - vma->vm_start) >> PAGE_SHIFT),
	417	map_flags);
ecc1a899	418	if (ret & ~PAGE_MASK)
097eed10 AV	419	goto out1;
	420
	421	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	422	if (!(ret & ~PAGE_MASK))
	423	goto out;
	424	out1:
	425	vm_unacct_memory(charged);
ecc1a899 AV	426
	427	out:
	428	return ret;
	429	}
	430
1a0ef85f AV	431	static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
1a0ef85f AV	432	{
f106af4e	433	unsigned long end = vma->vm_end + delta;
9206de95	434	if (end < vma->vm_end) /* overflow */
f106af4e	435	return 0;
9206de95	436	if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
f106af4e AV	437	return 0;
	438	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
	439	0, MAP_FIXED) & ~PAGE_MASK)
1a0ef85f	440	return 0;
1a0ef85f AV	441	return 1;
	442	}
	443
1da177e4 LT	444	/*
	445	* Expand (or shrink) an existing mapping, potentially moving it at the
	446	* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
	447	*
	448	* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
	449	* This option implies MREMAP_MAYMOVE.
	450	*/
63a81db1 AV	451	SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
	452	unsigned long, new_len, unsigned long, flags,
	453	unsigned long, new_addr)
1da177e4	454	{
d0de32d9	455	struct mm_struct *mm = current->mm;
1da177e4 LT	456	struct vm_area_struct *vma;
	457	unsigned long ret = -EINVAL;
	458	unsigned long charged = 0;
	459
63a81db1 AV	460	down_write(&current->mm->mmap_sem);
63a81db1 AV	461
1da177e4 LT	462	if (flags & ~(MREMAP_FIXED \| MREMAP_MAYMOVE))
	463	goto out;
	464
	465	if (addr & ~PAGE_MASK)
	466	goto out;
	467
	468	old_len = PAGE_ALIGN(old_len);
	469	new_len = PAGE_ALIGN(new_len);
	470
	471	/*
	472	* We allow a zero old-len as a special case
	473	* for DOS-emu "duplicate shm area" thing. But
	474	* a zero new-len is nonsensical.
	475	*/
	476	if (!new_len)
	477	goto out;
	478
1da177e4	479	if (flags & MREMAP_FIXED) {
ecc1a899 AV	480	if (flags & MREMAP_MAYMOVE)
	481	ret = mremap_to(addr, old_len, new_addr, new_len);
	482	goto out;
1da177e4 LT	483	}
	484
	485	/*
	486	* Always allow a shrinking remap: that just unmaps
	487	* the unnecessary pages..
	488	* do_munmap does all the needed commit accounting
	489	*/
	490	if (old_len >= new_len) {
d0de32d9	491	ret = do_munmap(mm, addr+new_len, old_len - new_len);
1da177e4 LT	492	if (ret && old_len != new_len)
	493	goto out;
	494	ret = addr;
ecc1a899	495	goto out;
1da177e4 LT	496	}
	497
	498	/*
ecc1a899	499	* Ok, we need to grow..
1da177e4	500	*/
54f5de70 AV	501	vma = vma_to_resize(addr, old_len, new_len, &charged);
	502	if (IS_ERR(vma)) {
	503	ret = PTR_ERR(vma);
1da177e4	504	goto out;
119f657c	505	}
1da177e4	506
1da177e4	507	/* old_len exactly to the end of the area..
1da177e4	508	*/
ecc1a899	509	if (old_len == vma->vm_end - addr) {
1da177e4	510	/* can we just expand the current mapping? */
1a0ef85f	511	if (vma_expandable(vma, new_len - old_len)) {
1da177e4 LT	512	int pages = (new_len - old_len) >> PAGE_SHIFT;
1da177e4 LT	513
5beb4930 RR	514	if (vma_adjust(vma, vma->vm_start, addr + new_len,
	515	vma->vm_pgoff, NULL)) {
	516	ret = -ENOMEM;
	517	goto out;
	518	}
1da177e4	519
d0de32d9	520	vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
1da177e4	521	if (vma->vm_flags & VM_LOCKED) {
d0de32d9	522	mm->locked_vm += pages;
ba470de4	523	mlock_vma_pages_range(vma, addr + old_len,
1da177e4 LT	524	addr + new_len);
	525	}
	526	ret = addr;
	527	goto out;
	528	}
	529	}
	530
	531	/*
	532	* We weren't able to just expand or shrink the area,
	533	* we need to create a new one and move it..
	534	*/
	535	ret = -ENOMEM;
	536	if (flags & MREMAP_MAYMOVE) {
ecc1a899 AV	537	unsigned long map_flags = 0;
	538	if (vma->vm_flags & VM_MAYSHARE)
	539	map_flags \|= MAP_SHARED;
	540
	541	new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
93587414 AV	542	vma->vm_pgoff +
	543	((addr - vma->vm_start) >> PAGE_SHIFT),
	544	map_flags);
ecc1a899 AV	545	if (new_addr & ~PAGE_MASK) {
	546	ret = new_addr;
	547	goto out;
1da177e4	548	}
ecc1a899	549
1da177e4 LT	550	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	551	}
	552	out:
	553	if (ret & ~PAGE_MASK)
	554	vm_unacct_memory(charged);
1da177e4 LT	555	up_write(&current->mm->mmap_sem);
	556	return ret;
	557	}