[mirror_ubuntu-zesty-kernel.git] / mm / madvise.c

/*
 *	linux/mm/madvise.c
 *
 * Copyright (C) 1999  Linus Torvalds
 * Copyright (C) 2002  Christoph Hellwig
 */

#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/mempolicy.h>
#include <linux/hugetlb.h>
#include <linux/sched.h>

/*
 * Any behaviour which results in changes to the vma->vm_flags needs to
 * take mmap_sem for writing. Others, which simply traverse vmas, need
 * to only take it for reading.
 */
static int madvise_need_mmap_write(int behavior)
{
	switch (behavior) {
	case MADV_REMOVE:
	case MADV_WILLNEED:
	case MADV_DONTNEED:
		return 0;
	default:
		/* be safe, default to 1. list exceptions explicitly */
		return 1;
	}
}

/*
 * We can potentially split a vm area into separate
 * areas, each area with its own behavior.
 */
static long madvise_behavior(struct vm_area_struct * vma,
		     struct vm_area_struct **prev,
		     unsigned long start, unsigned long end, int behavior)
{
	struct mm_struct * mm = vma->vm_mm;
	int error = 0;
	pgoff_t pgoff;
	int new_flags = vma->vm_flags;

	switch (behavior) {
	case MADV_NORMAL:
		new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
		break;
	case MADV_SEQUENTIAL:
		new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
		break;
	case MADV_RANDOM:
		new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
		break;
	case MADV_DONTFORK:
		new_flags |= VM_DONTCOPY;
		break;
	case MADV_DOFORK:
		new_flags &= ~VM_DONTCOPY;
		break;
	}

	if (new_flags == vma->vm_flags) {
		*prev = vma;
		goto out;
	}

	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
				vma->vm_file, pgoff, vma_policy(vma));
	if (*prev) {
		vma = *prev;
		goto success;
	}

	*prev = vma;

	if (start != vma->vm_start) {
		error = split_vma(mm, vma, start, 1);
		if (error)
			goto out;
	}

	if (end != vma->vm_end) {
		error = split_vma(mm, vma, end, 0);
		if (error)
			goto out;
	}

success:
	/*
	 * vm_flags is protected by the mmap_sem held in write mode.
	 */
	vma->vm_flags = new_flags;

out:
	if (error == -ENOMEM)
		error = -EAGAIN;
	return error;
}

/*
 * Schedule all required I/O operations.  Do not wait for completion.
 */
static long madvise_willneed(struct vm_area_struct * vma,
			     struct vm_area_struct ** prev,
			     unsigned long start, unsigned long end)
{
	struct file *file = vma->vm_file;

	if (!file)
		return -EBADF;

	if (file->f_mapping->a_ops->get_xip_mem) {
		/* no bad return value, but ignore advice */
		return 0;
	}

	*prev = vma;
	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	if (end > vma->vm_end)
		end = vma->vm_end;
	end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;

	force_page_cache_readahead(file->f_mapping, file, start, end - start);
	return 0;
}

/*
 * Application no longer needs these pages.  If the pages are dirty,
 * it's OK to just throw them away.  The app will be more careful about
 * data it wants to keep.  Be sure to free swap resources too.  The
 * zap_page_range call sets things up for shrink_active_list to actually free
 * these pages later if no one else has touched them in the meantime,
 * although we could add these pages to a global reuse list for
 * shrink_active_list to pick up before reclaiming other pages.
 *
 * NB: This interface discards data rather than pushes it out to swap,
 * as some implementations do.  This has performance implications for
 * applications like large transactional databases which want to discard
 * pages in anonymous maps after committing to backing store the data
 * that was kept in them.  There is no reason to write this data out to
 * the swap area if the application is discarding it.
 *
 * An interface that causes the system to free clean pages and flush
 * dirty pages is already available as msync(MS_INVALIDATE).
 */
static long madvise_dontneed(struct vm_area_struct * vma,
			     struct vm_area_struct ** prev,
			     unsigned long start, unsigned long end)
{
	*prev = vma;
	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
		return -EINVAL;

	if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
		struct zap_details details = {
			.nonlinear_vma = vma,
			.last_index = ULONG_MAX,
		};
		zap_page_range(vma, start, end - start, &details);
	} else
		zap_page_range(vma, start, end - start, NULL);
	return 0;
}

/*
 * Application wants to free up the pages and associated backing store.
 * This is effectively punching a hole into the middle of a file.
 *
 * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
 * Other filesystems return -ENOSYS.
 */
static long madvise_remove(struct vm_area_struct *vma,
				struct vm_area_struct **prev,
				unsigned long start, unsigned long end)
{
	struct address_space *mapping;
	loff_t offset, endoff;
	int error;

	*prev = NULL;	/* tell sys_madvise we drop mmap_sem */

	if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
		return -EINVAL;

	if (!vma->vm_file || !vma->vm_file->f_mapping
		|| !vma->vm_file->f_mapping->host) {
			return -EINVAL;
	}

	if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
		return -EACCES;

	mapping = vma->vm_file->f_mapping;

	offset = (loff_t)(start - vma->vm_start)
			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
	endoff = (loff_t)(end - vma->vm_start - 1)
			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);

	/* vmtruncate_range needs to take i_mutex and i_alloc_sem */
	up_read(&current->mm->mmap_sem);
	error = vmtruncate_range(mapping->host, offset, endoff);
	down_read(&current->mm->mmap_sem);
	return error;
}

static long
madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
		unsigned long start, unsigned long end, int behavior)
{
	long error;

	switch (behavior) {
	case MADV_DOFORK:
		if (vma->vm_flags & VM_IO) {
			error = -EINVAL;
			break;
		}
	case MADV_DONTFORK:
	case MADV_NORMAL:
	case MADV_SEQUENTIAL:
	case MADV_RANDOM:
		error = madvise_behavior(vma, prev, start, end, behavior);
		break;
	case MADV_REMOVE:
		error = madvise_remove(vma, prev, start, end);
		break;

	case MADV_WILLNEED:
		error = madvise_willneed(vma, prev, start, end);
		break;

	case MADV_DONTNEED:
		error = madvise_dontneed(vma, prev, start, end);
		break;

	default:
		BUG();
		break;
	}
	return error;
}

static int
madvise_behavior_valid(int behavior)
{
	switch (behavior) {
	case MADV_DOFORK:
	case MADV_DONTFORK:
	case MADV_NORMAL:
	case MADV_SEQUENTIAL:
	case MADV_RANDOM:
	case MADV_REMOVE:
	case MADV_WILLNEED:
	case MADV_DONTNEED:
		return 1;

	default:
		return 0;
	}
}
/*
 * The madvise(2) system call.
 *
 * Applications can use madvise() to advise the kernel how it should
 * handle paging I/O in this VM area.  The idea is to help the kernel
 * use appropriate read-ahead and caching techniques.  The information
 * provided is advisory only, and can be safely disregarded by the
 * kernel without affecting the correct operation of the application.
 *
 * behavior values:
 *  MADV_NORMAL - the default behavior is to read clusters.  This
 *		results in some read-ahead and read-behind.
 *  MADV_RANDOM - the system should read the minimum amount of data
 *		on any access, since it is unlikely that the appli-
 *		cation will need more than what it asks for.
 *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
 *		once, so they can be aggressively read ahead, and
 *		can be freed soon after they are accessed.
 *  MADV_WILLNEED - the application is notifying the system to read
 *		some pages ahead.
 *  MADV_DONTNEED - the application is finished with the given range,
 *		so the kernel can free resources associated with it.
 *  MADV_REMOVE - the application wants to free up the given range of
 *		pages and associated backing store.
 *
 * return values:
 *  zero    - success
 *  -EINVAL - start + len < 0, start is not page-aligned,
 *		"behavior" is not a valid value, or application
 *		is attempting to release locked or shared pages.
 *  -ENOMEM - addresses in the specified range are not currently
 *		mapped, or are outside the AS of the process.
 *  -EIO    - an I/O error occurred while paging in data.
 *  -EBADF  - map exists, but area maps something that isn't a file.
 *  -EAGAIN - a kernel resource was temporarily unavailable.
 */
SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
{
	unsigned long end, tmp;
	struct vm_area_struct * vma, *prev;
	int unmapped_error = 0;
	int error = -EINVAL;
	int write;
	size_t len;

	if (!madvise_behavior_valid(behavior))
		return error;

	write = madvise_need_mmap_write(behavior);
	if (write)
		down_write(&current->mm->mmap_sem);
	else
		down_read(&current->mm->mmap_sem);

	if (start & ~PAGE_MASK)
		goto out;
	len = (len_in + ~PAGE_MASK) & PAGE_MASK;

	/* Check to see whether len was rounded up from small -ve to zero */
	if (len_in && !len)
		goto out;

	end = start + len;
	if (end < start)
		goto out;

	error = 0;
	if (end == start)
		goto out;

	/*
	 * If the interval [start,end) covers some unmapped address
	 * ranges, just ignore them, but return -ENOMEM at the end.
	 * - different from the way of handling in mlock etc.
	 */
	vma = find_vma_prev(current->mm, start, &prev);
	if (vma && start > vma->vm_start)
		prev = vma;

	for (;;) {
		/* Still start < end. */
		error = -ENOMEM;
		if (!vma)
			goto out;

		/* Here start < (end|vma->vm_end). */
		if (start < vma->vm_start) {
			unmapped_error = -ENOMEM;
			start = vma->vm_start;
			if (start >= end)
				goto out;
		}

		/* Here vma->vm_start <= start < (end|vma->vm_end) */
		tmp = vma->vm_end;
		if (end < tmp)
			tmp = end;

		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
		error = madvise_vma(vma, &prev, start, tmp, behavior);
		if (error)
			goto out;
		start = tmp;
		if (prev && start < prev->vm_end)
			start = prev->vm_end;
		error = unmapped_error;
		if (start >= end)
			goto out;
		if (prev)
			vma = prev->vm_next;
		else	/* madvise_remove dropped mmap_sem */
			vma = find_vma(current->mm, start);
	}
out:
	if (write)
		up_write(&current->mm->mmap_sem);
	else
		up_read(&current->mm->mmap_sem);

	return error;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/mm/madvise.c
	3	*
	4	* Copyright (C) 1999 Linus Torvalds
	5	* Copyright (C) 2002 Christoph Hellwig
	6	*/
	7
	8	#include <linux/mman.h>
	9	#include <linux/pagemap.h>
	10	#include <linux/syscalls.h>
05b74384	11	#include <linux/mempolicy.h>
1da177e4	12	#include <linux/hugetlb.h>
e8edc6e0	13	#include <linux/sched.h>
1da177e4	14
0a27a14a NP	15	/*
	16	* Any behaviour which results in changes to the vma->vm_flags needs to
	17	* take mmap_sem for writing. Others, which simply traverse vmas, need
	18	* to only take it for reading.
	19	*/
	20	static int madvise_need_mmap_write(int behavior)
	21	{
	22	switch (behavior) {
	23	case MADV_REMOVE:
	24	case MADV_WILLNEED:
	25	case MADV_DONTNEED:
	26	return 0;
	27	default:
	28	/* be safe, default to 1. list exceptions explicitly */
	29	return 1;
	30	}
	31	}
	32
1da177e4 LT	33	/*
	34	* We can potentially split a vm area into separate
	35	* areas, each area with its own behavior.
	36	*/
05b74384 PM	37	static long madvise_behavior(struct vm_area_struct * vma,
	38	struct vm_area_struct **prev,
	39	unsigned long start, unsigned long end, int behavior)
1da177e4 LT	40	{
	41	struct mm_struct * mm = vma->vm_mm;
	42	int error = 0;
05b74384	43	pgoff_t pgoff;
f8225661	44	int new_flags = vma->vm_flags;
e798c6e8 PM	45
e798c6e8 PM	46	switch (behavior) {
f8225661 MT	47	case MADV_NORMAL:
	48	new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
	49	break;
e798c6e8	50	case MADV_SEQUENTIAL:
f8225661	51	new_flags = (new_flags & ~VM_RAND_READ) \| VM_SEQ_READ;
e798c6e8 PM	52	break;
e798c6e8 PM	53	case MADV_RANDOM:
f8225661	54	new_flags = (new_flags & ~VM_SEQ_READ) \| VM_RAND_READ;
e798c6e8	55	break;
f8225661 MT	56	case MADV_DONTFORK:
	57	new_flags \|= VM_DONTCOPY;
	58	break;
	59	case MADV_DOFORK:
	60	new_flags &= ~VM_DONTCOPY;
e798c6e8 PM	61	break;
	62	}
	63
05b74384 PM	64	if (new_flags == vma->vm_flags) {
05b74384 PM	65	*prev = vma;
836d5ffd	66	goto out;
05b74384 PM	67	}
	68
	69	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	70	prev = vma_merge(mm, prev, start, end, new_flags, vma->anon_vma,
	71	vma->vm_file, pgoff, vma_policy(vma));
	72	if (*prev) {
	73	vma = *prev;
	74	goto success;
	75	}
	76
	77	*prev = vma;
1da177e4 LT	78
	79	if (start != vma->vm_start) {
	80	error = split_vma(mm, vma, start, 1);
	81	if (error)
	82	goto out;
	83	}
	84
	85	if (end != vma->vm_end) {
	86	error = split_vma(mm, vma, end, 0);
	87	if (error)
	88	goto out;
	89	}
	90
836d5ffd	91	success:
1da177e4 LT	92	/*
	93	* vm_flags is protected by the mmap_sem held in write mode.
	94	*/
e798c6e8	95	vma->vm_flags = new_flags;
1da177e4 LT	96
	97	out:
	98	if (error == -ENOMEM)
	99	error = -EAGAIN;
	100	return error;
	101	}
	102
	103	/*
	104	* Schedule all required I/O operations. Do not wait for completion.
	105	*/
	106	static long madvise_willneed(struct vm_area_struct * vma,
05b74384	107	struct vm_area_struct ** prev,
1da177e4 LT	108	unsigned long start, unsigned long end)
	109	{
	110	struct file *file = vma->vm_file;
	111
1bef4003 S	112	if (!file)
	113	return -EBADF;
	114
70688e4d	115	if (file->f_mapping->a_ops->get_xip_mem) {
fe77ba6f CO	116	/* no bad return value, but ignore advice */
	117	return 0;
	118	}
	119
05b74384	120	*prev = vma;
1da177e4 LT	121	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	122	if (end > vma->vm_end)
	123	end = vma->vm_end;
	124	end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	125
f7e839dd	126	force_page_cache_readahead(file->f_mapping, file, start, end - start);
1da177e4 LT	127	return 0;
	128	}
	129
	130	/*
	131	* Application no longer needs these pages. If the pages are dirty,
	132	* it's OK to just throw them away. The app will be more careful about
	133	* data it wants to keep. Be sure to free swap resources too. The
7e6cbea3	134	* zap_page_range call sets things up for shrink_active_list to actually free
1da177e4 LT	135	* these pages later if no one else has touched them in the meantime,
1da177e4 LT	136	* although we could add these pages to a global reuse list for
7e6cbea3	137	* shrink_active_list to pick up before reclaiming other pages.
1da177e4 LT	138	*
	139	* NB: This interface discards data rather than pushes it out to swap,
	140	* as some implementations do. This has performance implications for
	141	* applications like large transactional databases which want to discard
	142	* pages in anonymous maps after committing to backing store the data
	143	* that was kept in them. There is no reason to write this data out to
	144	* the swap area if the application is discarding it.
	145	*
	146	* An interface that causes the system to free clean pages and flush
	147	* dirty pages is already available as msync(MS_INVALIDATE).
	148	*/
	149	static long madvise_dontneed(struct vm_area_struct * vma,
05b74384	150	struct vm_area_struct ** prev,
1da177e4 LT	151	unsigned long start, unsigned long end)
1da177e4 LT	152	{
05b74384	153	*prev = vma;
6aab341e	154	if (vma->vm_flags & (VM_LOCKED\|VM_HUGETLB\|VM_PFNMAP))
1da177e4 LT	155	return -EINVAL;
	156
	157	if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
	158	struct zap_details details = {
	159	.nonlinear_vma = vma,
	160	.last_index = ULONG_MAX,
	161	};
	162	zap_page_range(vma, start, end - start, &details);
	163	} else
	164	zap_page_range(vma, start, end - start, NULL);
	165	return 0;
	166	}
	167
f6b3ec23 BP	168	/*
	169	* Application wants to free up the pages and associated backing store.
	170	* This is effectively punching a hole into the middle of a file.
	171	*
	172	* NOTE: Currently, only shmfs/tmpfs is supported for this operation.
	173	* Other filesystems return -ENOSYS.
	174	*/
	175	static long madvise_remove(struct vm_area_struct *vma,
00e9fa2d	176	struct vm_area_struct **prev,
f6b3ec23 BP	177	unsigned long start, unsigned long end)
	178	{
	179	struct address_space *mapping;
90ed52eb HD	180	loff_t offset, endoff;
90ed52eb HD	181	int error;
f6b3ec23	182
90ed52eb	183	prev = NULL; / tell sys_madvise we drop mmap_sem */
00e9fa2d	184
f6b3ec23 BP	185	if (vma->vm_flags & (VM_LOCKED\|VM_NONLINEAR\|VM_HUGETLB))
	186	return -EINVAL;
	187
	188	if (!vma->vm_file \|\| !vma->vm_file->f_mapping
	189	\|\| !vma->vm_file->f_mapping->host) {
	190	return -EINVAL;
	191	}
	192
69cf0fac HD	193	if ((vma->vm_flags & (VM_SHARED\|VM_WRITE)) != (VM_SHARED\|VM_WRITE))
	194	return -EACCES;
	195
f6b3ec23 BP	196	mapping = vma->vm_file->f_mapping;
	197
	198	offset = (loff_t)(start - vma->vm_start)
	199	+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
	200	endoff = (loff_t)(end - vma->vm_start - 1)
	201	+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
90ed52eb HD	202
90ed52eb HD	203	/* vmtruncate_range needs to take i_mutex and i_alloc_sem */
0a27a14a	204	up_read(&current->mm->mmap_sem);
90ed52eb	205	error = vmtruncate_range(mapping->host, offset, endoff);
0a27a14a	206	down_read(&current->mm->mmap_sem);
90ed52eb	207	return error;
f6b3ec23 BP	208	}
f6b3ec23 BP	209
165cd402	210	static long
	211	madvise_vma(struct vm_area_struct vma, struct vm_area_struct *prev,
	212	unsigned long start, unsigned long end, int behavior)
1da177e4	213	{
1bef4003	214	long error;
165cd402	215
1da177e4	216	switch (behavior) {
f8225661 MT	217	case MADV_DOFORK:
	218	if (vma->vm_flags & VM_IO) {
	219	error = -EINVAL;
	220	break;
	221	}
	222	case MADV_DONTFORK:
1da177e4 LT	223	case MADV_NORMAL:
	224	case MADV_SEQUENTIAL:
	225	case MADV_RANDOM:
05b74384	226	error = madvise_behavior(vma, prev, start, end, behavior);
1da177e4	227	break;
f6b3ec23	228	case MADV_REMOVE:
00e9fa2d	229	error = madvise_remove(vma, prev, start, end);
f6b3ec23	230	break;
1da177e4 LT	231
1da177e4 LT	232	case MADV_WILLNEED:
05b74384	233	error = madvise_willneed(vma, prev, start, end);
1da177e4 LT	234	break;
	235
	236	case MADV_DONTNEED:
05b74384	237	error = madvise_dontneed(vma, prev, start, end);
1da177e4 LT	238	break;
	239
	240	default:
75927af8	241	BUG();
1da177e4 LT	242	break;
1da177e4 LT	243	}
1da177e4 LT	244	return error;
	245	}
	246
75927af8 NP	247	static int
	248	madvise_behavior_valid(int behavior)
	249	{
	250	switch (behavior) {
	251	case MADV_DOFORK:
	252	case MADV_DONTFORK:
	253	case MADV_NORMAL:
	254	case MADV_SEQUENTIAL:
	255	case MADV_RANDOM:
	256	case MADV_REMOVE:
	257	case MADV_WILLNEED:
	258	case MADV_DONTNEED:
	259	return 1;
	260
	261	default:
	262	return 0;
	263	}
	264	}
1da177e4 LT	265	/*
	266	* The madvise(2) system call.
	267	*
	268	* Applications can use madvise() to advise the kernel how it should
	269	* handle paging I/O in this VM area. The idea is to help the kernel
	270	* use appropriate read-ahead and caching techniques. The information
	271	* provided is advisory only, and can be safely disregarded by the
	272	* kernel without affecting the correct operation of the application.
	273	*
	274	* behavior values:
	275	* MADV_NORMAL - the default behavior is to read clusters. This
	276	* results in some read-ahead and read-behind.
	277	* MADV_RANDOM - the system should read the minimum amount of data
	278	* on any access, since it is unlikely that the appli-
	279	* cation will need more than what it asks for.
	280	* MADV_SEQUENTIAL - pages in the given range will probably be accessed
	281	* once, so they can be aggressively read ahead, and
	282	* can be freed soon after they are accessed.
	283	* MADV_WILLNEED - the application is notifying the system to read
	284	* some pages ahead.
	285	* MADV_DONTNEED - the application is finished with the given range,
	286	* so the kernel can free resources associated with it.
f6b3ec23 BP	287	* MADV_REMOVE - the application wants to free up the given range of
f6b3ec23 BP	288	* pages and associated backing store.
1da177e4 LT	289	*
	290	* return values:
	291	* zero - success
	292	* -EINVAL - start + len < 0, start is not page-aligned,
	293	* "behavior" is not a valid value, or application
	294	* is attempting to release locked or shared pages.
	295	* -ENOMEM - addresses in the specified range are not currently
	296	* mapped, or are outside the AS of the process.
	297	* -EIO - an I/O error occurred while paging in data.
	298	* -EBADF - map exists, but area maps something that isn't a file.
	299	* -EAGAIN - a kernel resource was temporarily unavailable.
	300	*/
3480b257	301	SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1da177e4	302	{
05b74384 PM	303	unsigned long end, tmp;
05b74384 PM	304	struct vm_area_struct * vma, *prev;
1da177e4 LT	305	int unmapped_error = 0;
1da177e4 LT	306	int error = -EINVAL;
f7977793	307	int write;
1da177e4 LT	308	size_t len;
1da177e4 LT	309
75927af8 NP	310	if (!madvise_behavior_valid(behavior))
	311	return error;
	312
f7977793 JB	313	write = madvise_need_mmap_write(behavior);
f7977793 JB	314	if (write)
0a27a14a NP	315	down_write(&current->mm->mmap_sem);
	316	else
	317	down_read(&current->mm->mmap_sem);
1da177e4 LT	318
	319	if (start & ~PAGE_MASK)
	320	goto out;
	321	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
	322
	323	/* Check to see whether len was rounded up from small -ve to zero */
	324	if (len_in && !len)
	325	goto out;
	326
	327	end = start + len;
	328	if (end < start)
	329	goto out;
	330
	331	error = 0;
	332	if (end == start)
	333	goto out;
	334
	335	/*
	336	* If the interval [start,end) covers some unmapped address
	337	* ranges, just ignore them, but return -ENOMEM at the end.
05b74384	338	* - different from the way of handling in mlock etc.
1da177e4	339	*/
05b74384	340	vma = find_vma_prev(current->mm, start, &prev);
836d5ffd HD	341	if (vma && start > vma->vm_start)
	342	prev = vma;
	343
1da177e4 LT	344	for (;;) {
	345	/* Still start < end. */
	346	error = -ENOMEM;
	347	if (!vma)
	348	goto out;
	349
05b74384	350	/* Here start < (end\|vma->vm_end). */
1da177e4 LT	351	if (start < vma->vm_start) {
	352	unmapped_error = -ENOMEM;
	353	start = vma->vm_start;
05b74384 PM	354	if (start >= end)
05b74384 PM	355	goto out;
1da177e4 LT	356	}
1da177e4 LT	357
05b74384 PM	358	/* Here vma->vm_start <= start < (end\|vma->vm_end) */
	359	tmp = vma->vm_end;
	360	if (end < tmp)
	361	tmp = end;
1da177e4	362
05b74384 PM	363	/* Here vma->vm_start <= start < tmp <= (end\|vma->vm_end). */
05b74384 PM	364	error = madvise_vma(vma, &prev, start, tmp, behavior);
1da177e4 LT	365	if (error)
1da177e4 LT	366	goto out;
05b74384	367	start = tmp;
90ed52eb	368	if (prev && start < prev->vm_end)
05b74384 PM	369	start = prev->vm_end;
	370	error = unmapped_error;
	371	if (start >= end)
	372	goto out;
90ed52eb HD	373	if (prev)
	374	vma = prev->vm_next;
	375	else /* madvise_remove dropped mmap_sem */
	376	vma = find_vma(current->mm, start);
1da177e4	377	}
1da177e4	378	out:
f7977793	379	if (write)
0a27a14a NP	380	up_write(&current->mm->mmap_sem);
	381	else
	382	up_read(&current->mm->mmap_sem);
	383
1da177e4 LT	384	return error;
1da177e4 LT	385	}