[mirror_ubuntu-artful-kernel.git] / mm / mremap.c

/*
 *	mm/mremap.c
 *
 *	(C) Copyright 1996 Linus Torvalds
 *
 *	Address space accounting code	<alan@redhat.com>
 *	(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/mman.h>
#include <linux/swap.h>
#include <linux/fs.h>
#include <linux/highmem.h>
#include <linux/security.h>
#include <linux/syscalls.h>

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

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

	pgd = pgd_offset(mm, addr);
	if (pgd_none_or_clear_bad(pgd))
		goto end;

	pud = pud_offset(pgd, addr);
	if (pud_none_or_clear_bad(pud))
		goto end;

	pmd = pmd_offset(pud, addr);
	if (pmd_none_or_clear_bad(pmd))
		goto end;

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

static pte_t *get_one_pte_map(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 pte_offset_map(pmd, addr);
}

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

	pgd = pgd_offset(mm, addr);

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return NULL;
	pmd = pmd_alloc(mm, pud, addr);
	if (pmd)
		pte = pte_alloc_map(mm, pmd, addr);
	return pte;
}

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

	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;
	}
	spin_lock(&mm->page_table_lock);

	src = get_one_pte_map_nested(mm, old_addr);
	if (src) {
		/*
		 * Look to see whether alloc_one_pte_map needs to perform a
		 * memory allocation.  If it does then we need to drop the
		 * atomic kmap
		 */
		dst = get_one_pte_map(mm, new_addr);
		if (unlikely(!dst)) {
			pte_unmap_nested(src);
			if (mapping)
				spin_unlock(&mapping->i_mmap_lock);
			dst = alloc_one_pte_map(mm, new_addr);
			if (mapping && !spin_trylock(&mapping->i_mmap_lock)) {
				spin_unlock(&mm->page_table_lock);
				spin_lock(&mapping->i_mmap_lock);
				spin_lock(&mm->page_table_lock);
			}
			src = get_one_pte_map_nested(mm, old_addr);
		}
		/*
		 * Since alloc_one_pte_map can drop and re-acquire
		 * page_table_lock, we should re-check the src entry...
		 */
		if (src) {
			if (dst) {
				pte_t pte;
				pte = ptep_clear_flush(vma, old_addr, src);

				/* ZERO_PAGE can be dependant on virtual addr */
				pte = move_pte(pte, new_vma->vm_page_prot,
							old_addr, new_addr);
				set_pte_at(mm, new_addr, dst, pte);
			} else
				error = -ENOMEM;
			pte_unmap_nested(src);
		}
		if (dst)
			pte_unmap(dst);
	}
	spin_unlock(&mm->page_table_lock);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);
	return error;
}

static 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 offset;

	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.
	 */
	for (offset = 0; offset < len; offset += PAGE_SIZE) {
		if (move_one_page(vma, old_addr + offset,
				new_vma, new_addr + offset) < 0)
			break;
		cond_resched();
	}
	return offset;
}

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;
	int split = 0;

	/*
	 * 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;

	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
	 */
	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;
	}

	/* 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)
			make_pages_present(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 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 = do_munmap(current->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(current->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(current->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) {
		if (new_len > old_len)
			goto out;
	}
	if (vma->vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
		locked = current->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(current->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);

			current->mm->total_vm += pages;
			vm_stat_account(vma->vm_mm, vma->vm_flags,
							vma->vm_file, 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_MAYSHARE)
				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:
	if (ret & ~PAGE_MASK)
		vm_unacct_memory(charged);
out_nc:
	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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* mm/mremap.c
	3	*
	4	* (C) Copyright 1996 Linus Torvalds
	5	*
	6	* Address space accounting code <alan@redhat.com>
	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>
	14	#include <linux/mman.h>
	15	#include <linux/swap.h>
	16	#include <linux/fs.h>
	17	#include <linux/highmem.h>
	18	#include <linux/security.h>
	19	#include <linux/syscalls.h>
	20
	21	#include <asm/uaccess.h>
	22	#include <asm/cacheflush.h>
	23	#include <asm/tlbflush.h>
	24
	25	static pte_t get_one_pte_map_nested(struct mm_struct mm, unsigned long addr)
	26	{
	27	pgd_t *pgd;
	28	pud_t *pud;
	29	pmd_t *pmd;
	30	pte_t *pte = NULL;
	31
	32	pgd = pgd_offset(mm, addr);
	33	if (pgd_none_or_clear_bad(pgd))
	34	goto end;
	35
	36	pud = pud_offset(pgd, addr);
	37	if (pud_none_or_clear_bad(pud))
	38	goto end;
	39
	40	pmd = pmd_offset(pud, addr);
	41	if (pmd_none_or_clear_bad(pmd))
	42	goto end;
	43
	44	pte = pte_offset_map_nested(pmd, addr);
	45	if (pte_none(*pte)) {
	46	pte_unmap_nested(pte);
	47	pte = NULL;
	48	}
	49	end:
	50	return pte;
	51	}
	52
	53	static pte_t get_one_pte_map(struct mm_struct mm, unsigned long addr)
	54	{
	55	pgd_t *pgd;
	56	pud_t *pud;
	57	pmd_t *pmd;
	58
	59	pgd = pgd_offset(mm, addr);
	60	if (pgd_none_or_clear_bad(pgd))
	61	return NULL;
	62
	63	pud = pud_offset(pgd, addr);
	64	if (pud_none_or_clear_bad(pud))
65	return NULL;
66
67	pmd = pmd_offset(pud, addr);
68	if (pmd_none_or_clear_bad(pmd))
69	return NULL;
70
71	return pte_offset_map(pmd, addr);
72	}
73
74	static inline pte_t alloc_one_pte_map(struct mm_struct mm, unsigned long addr)
75	{
76	pgd_t *pgd;
77	pud_t *pud;
78	pmd_t *pmd;
79	pte_t *pte = NULL;
80
81	pgd = pgd_offset(mm, addr);
82
83	pud = pud_alloc(mm, pgd, addr);
84	if (!pud)
85	return NULL;
86	pmd = pmd_alloc(mm, pud, addr);
87	if (pmd)
88	pte = pte_alloc_map(mm, pmd, addr);
89	return pte;
90	}
91
92	static int
93	move_one_page(struct vm_area_struct *vma, unsigned long old_addr,
94	struct vm_area_struct *new_vma, unsigned long new_addr)
95	{
96	struct address_space *mapping = NULL;
97	struct mm_struct *mm = vma->vm_mm;
98	int error = 0;
99	pte_t src, dst;
100
101	if (vma->vm_file) {
102	/*
103	* Subtle point from Rajesh Venkatasubramanian: before
104	* moving file-based ptes, we must lock vmtruncate out,
105	* since it might clean the dst vma before the src vma,
106	* and we propagate stale pages into the dst afterward.
107	*/
108	mapping = vma->vm_file->f_mapping;
109	spin_lock(&mapping->i_mmap_lock);
110	if (new_vma->vm_truncate_count &&
111	new_vma->vm_truncate_count != vma->vm_truncate_count)
112	new_vma->vm_truncate_count = 0;
113	}
114	spin_lock(&mm->page_table_lock);
115
116	src = get_one_pte_map_nested(mm, old_addr);
117	if (src) {
118	/*
119	* Look to see whether alloc_one_pte_map needs to perform a
120	* memory allocation. If it does then we need to drop the
121	* atomic kmap
122	*/
123	dst = get_one_pte_map(mm, new_addr);
124	if (unlikely(!dst)) {
125	pte_unmap_nested(src);
126	if (mapping)
127	spin_unlock(&mapping->i_mmap_lock);
128	dst = alloc_one_pte_map(mm, new_addr);
129	if (mapping && !spin_trylock(&mapping->i_mmap_lock)) {
130	spin_unlock(&mm->page_table_lock);
131	spin_lock(&mapping->i_mmap_lock);
132	spin_lock(&mm->page_table_lock);
133	}
134	src = get_one_pte_map_nested(mm, old_addr);
135	}
136	/*
137	* Since alloc_one_pte_map can drop and re-acquire
138	* page_table_lock, we should re-check the src entry...
139	*/
140	if (src) {
141	if (dst) {
142	pte_t pte;
143	pte = ptep_clear_flush(vma, old_addr, src);
8b1f3124	144
9a61c349	145	/* ZERO_PAGE can be dependant on virtual addr */
8b1f3124 NP	146	pte = move_pte(pte, new_vma->vm_page_prot,
8b1f3124 NP	147	old_addr, new_addr);
1da177e4 LT	148	set_pte_at(mm, new_addr, dst, pte);
	149	} else
	150	error = -ENOMEM;
	151	pte_unmap_nested(src);
	152	}
	153	if (dst)
	154	pte_unmap(dst);
	155	}
	156	spin_unlock(&mm->page_table_lock);
	157	if (mapping)
	158	spin_unlock(&mapping->i_mmap_lock);
	159	return error;
	160	}
	161
	162	static unsigned long move_page_tables(struct vm_area_struct *vma,
	163	unsigned long old_addr, struct vm_area_struct *new_vma,
	164	unsigned long new_addr, unsigned long len)
	165	{
	166	unsigned long offset;
	167
	168	flush_cache_range(vma, old_addr, old_addr + len);
	169
	170	/*
	171	* This is not the clever way to do this, but we're taking the
	172	* easy way out on the assumption that most remappings will be
	173	* only a few pages.. This also makes error recovery easier.
	174	*/
	175	for (offset = 0; offset < len; offset += PAGE_SIZE) {
	176	if (move_one_page(vma, old_addr + offset,
	177	new_vma, new_addr + offset) < 0)
	178	break;
	179	cond_resched();
	180	}
	181	return offset;
	182	}
	183
	184	static unsigned long move_vma(struct vm_area_struct *vma,
	185	unsigned long old_addr, unsigned long old_len,
	186	unsigned long new_len, unsigned long new_addr)
	187	{
	188	struct mm_struct *mm = vma->vm_mm;
	189	struct vm_area_struct *new_vma;
	190	unsigned long vm_flags = vma->vm_flags;
	191	unsigned long new_pgoff;
	192	unsigned long moved_len;
	193	unsigned long excess = 0;
	194	int split = 0;
	195
	196	/*
	197	* We'd prefer to avoid failure later on in do_munmap:
	198	* which may split one vma into three before unmapping.
	199	*/
	200	if (mm->map_count >= sysctl_max_map_count - 3)
	201	return -ENOMEM;
	202
	203	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
	204	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
	205	if (!new_vma)
	206	return -ENOMEM;
	207
	208	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
	209	if (moved_len < old_len) {
	210	/*
	211	* On error, move entries back from new area to old,
212	* which will succeed since page tables still there,
213	* and then proceed to unmap new area instead of old.
214	*/
215	move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
216	vma = new_vma;
217	old_len = new_len;
218	old_addr = new_addr;
219	new_addr = -ENOMEM;
220	}
221
222	/* Conceal VM_ACCOUNT so old reservation is not undone */
223	if (vm_flags & VM_ACCOUNT) {
224	vma->vm_flags &= ~VM_ACCOUNT;
225	excess = vma->vm_end - vma->vm_start - old_len;
226	if (old_addr > vma->vm_start &&
227	old_addr + old_len < vma->vm_end)
228	split = 1;
229	}
230
71799062 KK	231	/*
	232	* if we failed to move page tables we still do total_vm increment
	233	* since do_munmap() will decrement it by old_len == new_len
	234	*/
	235	mm->total_vm += new_len >> PAGE_SHIFT;
ab50b8ed	236	vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
71799062	237
1da177e4 LT	238	if (do_munmap(mm, old_addr, old_len) < 0) {
	239	/* OOM: unable to split vma, just get accounts right */
	240	vm_unacct_memory(excess >> PAGE_SHIFT);
	241	excess = 0;
	242	}
	243
	244	/* Restore VM_ACCOUNT if one or two pieces of vma left */
	245	if (excess) {
	246	vma->vm_flags \|= VM_ACCOUNT;
	247	if (split)
	248	vma->vm_next->vm_flags \|= VM_ACCOUNT;
	249	}
	250
1da177e4 LT	251	if (vm_flags & VM_LOCKED) {
	252	mm->locked_vm += new_len >> PAGE_SHIFT;
	253	if (new_len > old_len)
	254	make_pages_present(new_addr + old_len,
	255	new_addr + new_len);
	256	}
	257
	258	return new_addr;
	259	}
	260
	261	/*
	262	* Expand (or shrink) an existing mapping, potentially moving it at the
	263	* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
	264	*
	265	* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
	266	* This option implies MREMAP_MAYMOVE.
	267	*/
	268	unsigned long do_mremap(unsigned long addr,
	269	unsigned long old_len, unsigned long new_len,
	270	unsigned long flags, unsigned long new_addr)
	271	{
	272	struct vm_area_struct *vma;
	273	unsigned long ret = -EINVAL;
	274	unsigned long charged = 0;
	275
	276	if (flags & ~(MREMAP_FIXED \| MREMAP_MAYMOVE))
	277	goto out;
	278
	279	if (addr & ~PAGE_MASK)
	280	goto out;
	281
	282	old_len = PAGE_ALIGN(old_len);
	283	new_len = PAGE_ALIGN(new_len);
	284
	285	/*
	286	* We allow a zero old-len as a special case
	287	* for DOS-emu "duplicate shm area" thing. But
	288	* a zero new-len is nonsensical.
	289	*/
	290	if (!new_len)
	291	goto out;
	292
	293	/* new_addr is only valid if MREMAP_FIXED is specified */
	294	if (flags & MREMAP_FIXED) {
	295	if (new_addr & ~PAGE_MASK)
	296	goto out;
	297	if (!(flags & MREMAP_MAYMOVE))
	298	goto out;
	299
	300	if (new_len > TASK_SIZE \|\| new_addr > TASK_SIZE - new_len)
	301	goto out;
	302
	303	/* Check if the location we're moving into overlaps the
	304	* old location at all, and fail if it does.
	305	*/
	306	if ((new_addr <= addr) && (new_addr+new_len) > addr)
	307	goto out;
	308
	309	if ((addr <= new_addr) && (addr+old_len) > new_addr)
	310	goto out;
	311
	312	ret = do_munmap(current->mm, new_addr, new_len);
	313	if (ret)
	314	goto out;
315	}
316
317	/*
318	* Always allow a shrinking remap: that just unmaps
319	* the unnecessary pages..
320	* do_munmap does all the needed commit accounting
321	*/
322	if (old_len >= new_len) {
323	ret = do_munmap(current->mm, addr+new_len, old_len - new_len);
324	if (ret && old_len != new_len)
325	goto out;
326	ret = addr;
327	if (!(flags & MREMAP_FIXED) \|\| (new_addr == addr))
328	goto out;
329	old_len = new_len;
330	}
331
332	/*
333	* Ok, we need to grow.. or relocate.
334	*/
335	ret = -EFAULT;
336	vma = find_vma(current->mm, addr);
337	if (!vma \|\| vma->vm_start > addr)
338	goto out;
339	if (is_vm_hugetlb_page(vma)) {
340	ret = -EINVAL;
341	goto out;
342	}
343	/* We can't remap across vm area boundaries */
344	if (old_len > vma->vm_end - addr)
345	goto out;
346	if (vma->vm_flags & VM_DONTEXPAND) {
347	if (new_len > old_len)
348	goto out;
349	}
350	if (vma->vm_flags & VM_LOCKED) {
351	unsigned long locked, lock_limit;
352	locked = current->mm->locked_vm << PAGE_SHIFT;
353	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
354	locked += new_len - old_len;
355	ret = -EAGAIN;
356	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
357	goto out;
358	}
119f657c	359	if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) {
119f657c	360	ret = -ENOMEM;
1da177e4	361	goto out;
119f657c	362	}
1da177e4 LT	363
	364	if (vma->vm_flags & VM_ACCOUNT) {
	365	charged = (new_len - old_len) >> PAGE_SHIFT;
	366	if (security_vm_enough_memory(charged))
	367	goto out_nc;
	368	}
	369
	370	/* old_len exactly to the end of the area..
	371	* And we're not relocating the area.
	372	*/
	373	if (old_len == vma->vm_end - addr &&
	374	!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
	375	(old_len != new_len \|\| !(flags & MREMAP_MAYMOVE))) {
	376	unsigned long max_addr = TASK_SIZE;
	377	if (vma->vm_next)
	378	max_addr = vma->vm_next->vm_start;
	379	/* can we just expand the current mapping? */
	380	if (max_addr - addr >= new_len) {
	381	int pages = (new_len - old_len) >> PAGE_SHIFT;
	382
	383	vma_adjust(vma, vma->vm_start,
	384	addr + new_len, vma->vm_pgoff, NULL);
	385
	386	current->mm->total_vm += pages;
ab50b8ed	387	vm_stat_account(vma->vm_mm, vma->vm_flags,
1da177e4 LT	388	vma->vm_file, pages);
	389	if (vma->vm_flags & VM_LOCKED) {
	390	current->mm->locked_vm += pages;
	391	make_pages_present(addr + old_len,
	392	addr + new_len);
	393	}
	394	ret = addr;
	395	goto out;
	396	}
	397	}
	398
	399	/*
	400	* We weren't able to just expand or shrink the area,
	401	* we need to create a new one and move it..
	402	*/
	403	ret = -ENOMEM;
	404	if (flags & MREMAP_MAYMOVE) {
	405	if (!(flags & MREMAP_FIXED)) {
	406	unsigned long map_flags = 0;
	407	if (vma->vm_flags & VM_MAYSHARE)
	408	map_flags \|= MAP_SHARED;
	409
	410	new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
	411	vma->vm_pgoff, map_flags);
	412	ret = new_addr;
	413	if (new_addr & ~PAGE_MASK)
	414	goto out;
	415	}
	416	ret = move_vma(vma, addr, old_len, new_len, new_addr);
	417	}
	418	out:
	419	if (ret & ~PAGE_MASK)
	420	vm_unacct_memory(charged);
	421	out_nc:
	422	return ret;
	423	}
	424
	425	asmlinkage unsigned long sys_mremap(unsigned long addr,
	426	unsigned long old_len, unsigned long new_len,
	427	unsigned long flags, unsigned long new_addr)
	428	{
	429	unsigned long ret;
	430
	431	down_write(&current->mm->mmap_sem);
	432	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	433	up_write(&current->mm->mmap_sem);
	434	return ret;
	435	}