[linux.git] / mm / util.c

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/mman.h>
#include <linux/hugetlb.h>

#include <asm/uaccess.h>

#include "internal.h"

#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>

/**
 * kstrdup - allocate space for and copy an existing string
 * @s: the string to duplicate
 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 */
char *kstrdup(const char *s, gfp_t gfp)
{
	size_t len;
	char *buf;

	if (!s)
		return NULL;

	len = strlen(s) + 1;
	buf = kmalloc_track_caller(len, gfp);
	if (buf)
		memcpy(buf, s, len);
	return buf;
}
EXPORT_SYMBOL(kstrdup);

/**
 * kstrndup - allocate space for and copy an existing string
 * @s: the string to duplicate
 * @max: read at most @max chars from @s
 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 */
char *kstrndup(const char *s, size_t max, gfp_t gfp)
{
	size_t len;
	char *buf;

	if (!s)
		return NULL;

	len = strnlen(s, max);
	buf = kmalloc_track_caller(len+1, gfp);
	if (buf) {
		memcpy(buf, s, len);
		buf[len] = '\0';
	}
	return buf;
}
EXPORT_SYMBOL(kstrndup);

/**
 * kmemdup - duplicate region of memory
 *
 * @src: memory region to duplicate
 * @len: memory region length
 * @gfp: GFP mask to use
 */
void *kmemdup(const void *src, size_t len, gfp_t gfp)
{
	void *p;

	p = kmalloc_track_caller(len, gfp);
	if (p)
		memcpy(p, src, len);
	return p;
}
EXPORT_SYMBOL(kmemdup);

/**
 * memdup_user - duplicate memory region from user space
 *
 * @src: source address in user space
 * @len: number of bytes to copy
 *
 * Returns an ERR_PTR() on failure.
 */
void *memdup_user(const void __user *src, size_t len)
{
	void *p;

	/*
	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
	 * cause pagefault, which makes it pointless to use GFP_NOFS
	 * or GFP_ATOMIC.
	 */
	p = kmalloc_track_caller(len, GFP_KERNEL);
	if (!p)
		return ERR_PTR(-ENOMEM);

	if (copy_from_user(p, src, len)) {
		kfree(p);
		return ERR_PTR(-EFAULT);
	}

	return p;
}
EXPORT_SYMBOL(memdup_user);

static __always_inline void *__do_krealloc(const void *p, size_t new_size,
					   gfp_t flags)
{
	void *ret;
	size_t ks = 0;

	if (p)
		ks = ksize(p);

	if (ks >= new_size)
		return (void *)p;

	ret = kmalloc_track_caller(new_size, flags);
	if (ret && p)
		memcpy(ret, p, ks);

	return ret;
}

/**
 * __krealloc - like krealloc() but don't free @p.
 * @p: object to reallocate memory for.
 * @new_size: how many bytes of memory are required.
 * @flags: the type of memory to allocate.
 *
 * This function is like krealloc() except it never frees the originally
 * allocated buffer. Use this if you don't want to free the buffer immediately
 * like, for example, with RCU.
 */
void *__krealloc(const void *p, size_t new_size, gfp_t flags)
{
	if (unlikely(!new_size))
		return ZERO_SIZE_PTR;

	return __do_krealloc(p, new_size, flags);

}
EXPORT_SYMBOL(__krealloc);

/**
 * krealloc - reallocate memory. The contents will remain unchanged.
 * @p: object to reallocate memory for.
 * @new_size: how many bytes of memory are required.
 * @flags: the type of memory to allocate.
 *
 * The contents of the object pointed to are preserved up to the
 * lesser of the new and old sizes.  If @p is %NULL, krealloc()
 * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
 * %NULL pointer, the object pointed to is freed.
 */
void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
	void *ret;

	if (unlikely(!new_size)) {
		kfree(p);
		return ZERO_SIZE_PTR;
	}

	ret = __do_krealloc(p, new_size, flags);
	if (ret && p != ret)
		kfree(p);

	return ret;
}
EXPORT_SYMBOL(krealloc);

/**
 * kzfree - like kfree but zero memory
 * @p: object to free memory of
 *
 * The memory of the object @p points to is zeroed before freed.
 * If @p is %NULL, kzfree() does nothing.
 *
 * Note: this function zeroes the whole allocated buffer which can be a good
 * deal bigger than the requested buffer size passed to kmalloc(). So be
 * careful when using this function in performance sensitive code.
 */
void kzfree(const void *p)
{
	size_t ks;
	void *mem = (void *)p;

	if (unlikely(ZERO_OR_NULL_PTR(mem)))
		return;
	ks = ksize(mem);
	memset(mem, 0, ks);
	kfree(mem);
}
EXPORT_SYMBOL(kzfree);

/*
 * strndup_user - duplicate an existing string from user space
 * @s: The string to duplicate
 * @n: Maximum number of bytes to copy, including the trailing NUL.
 */
char *strndup_user(const char __user *s, long n)
{
	char *p;
	long length;

	length = strnlen_user(s, n);

	if (!length)
		return ERR_PTR(-EFAULT);

	if (length > n)
		return ERR_PTR(-EINVAL);

	p = memdup_user(s, length);

	if (IS_ERR(p))
		return p;

	p[length - 1] = '\0';

	return p;
}
EXPORT_SYMBOL(strndup_user);

void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev, struct rb_node *rb_parent)
{
	struct vm_area_struct *next;

	vma->vm_prev = prev;
	if (prev) {
		next = prev->vm_next;
		prev->vm_next = vma;
	} else {
		mm->mmap = vma;
		if (rb_parent)
			next = rb_entry(rb_parent,
					struct vm_area_struct, vm_rb);
		else
			next = NULL;
	}
	vma->vm_next = next;
	if (next)
		next->vm_prev = vma;
}

/* Check if the vma is being used as a stack by this task */
static int vm_is_stack_for_task(struct task_struct *t,
				struct vm_area_struct *vma)
{
	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
}

/*
 * Check if the vma is being used as a stack.
 * If is_group is non-zero, check in the entire thread group or else
 * just check in the current task. Returns the pid of the task that
 * the vma is stack for.
 */
pid_t vm_is_stack(struct task_struct *task,
		  struct vm_area_struct *vma, int in_group)
{
	pid_t ret = 0;

	if (vm_is_stack_for_task(task, vma))
		return task->pid;

	if (in_group) {
		struct task_struct *t;
		rcu_read_lock();
		if (!pid_alive(task))
			goto done;

		t = task;
		do {
			if (vm_is_stack_for_task(t, vma)) {
				ret = t->pid;
				goto done;
			}
		} while_each_thread(task, t);
done:
		rcu_read_unlock();
	}

	return ret;
}

#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm)
{
	mm->mmap_base = TASK_UNMAPPED_BASE;
	mm->get_unmapped_area = arch_get_unmapped_area;
}
#endif

/*
 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
 * back to the regular GUP.
 * If the architecture not support this function, simply return with no
 * page pinned
 */
int __weak __get_user_pages_fast(unsigned long start,
				 int nr_pages, int write, struct page **pages)
{
	return 0;
}
EXPORT_SYMBOL_GPL(__get_user_pages_fast);

/**
 * get_user_pages_fast() - pin user pages in memory
 * @start:	starting user address
 * @nr_pages:	number of pages from start to pin
 * @write:	whether pages will be written to
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long.
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno.
 *
 * get_user_pages_fast provides equivalent functionality to get_user_pages,
 * operating on current and current->mm, with force=0 and vma=NULL. However
 * unlike get_user_pages, it must be called without mmap_sem held.
 *
 * get_user_pages_fast may take mmap_sem and page table locks, so no
 * assumptions can be made about lack of locking. get_user_pages_fast is to be
 * implemented in a way that is advantageous (vs get_user_pages()) when the
 * user memory area is already faulted in and present in ptes. However if the
 * pages have to be faulted in, it may turn out to be slightly slower so
 * callers need to carefully consider what to use. On many architectures,
 * get_user_pages_fast simply falls back to get_user_pages.
 */
int __weak get_user_pages_fast(unsigned long start,
				int nr_pages, int write, struct page **pages)
{
	struct mm_struct *mm = current->mm;
	int ret;

	down_read(&mm->mmap_sem);
	ret = get_user_pages(current, mm, start, nr_pages,
					write, 0, pages, NULL);
	up_read(&mm->mmap_sem);

	return ret;
}
EXPORT_SYMBOL_GPL(get_user_pages_fast);

unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
	unsigned long len, unsigned long prot,
	unsigned long flag, unsigned long pgoff)
{
	unsigned long ret;
	struct mm_struct *mm = current->mm;
	unsigned long populate;

	ret = security_mmap_file(file, prot, flag);
	if (!ret) {
		down_write(&mm->mmap_sem);
		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
				    &populate);
		up_write(&mm->mmap_sem);
		if (populate)
			mm_populate(ret, populate);
	}
	return ret;
}

unsigned long vm_mmap(struct file *file, unsigned long addr,
	unsigned long len, unsigned long prot,
	unsigned long flag, unsigned long offset)
{
	if (unlikely(offset + PAGE_ALIGN(len) < offset))
		return -EINVAL;
	if (unlikely(offset & ~PAGE_MASK))
		return -EINVAL;

	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
}
EXPORT_SYMBOL(vm_mmap);

struct address_space *page_mapping(struct page *page)
{
	struct address_space *mapping = page->mapping;

	/* This happens if someone calls flush_dcache_page on slab page */
	if (unlikely(PageSlab(page)))
		return NULL;

	if (unlikely(PageSwapCache(page))) {
		swp_entry_t entry;

		entry.val = page_private(page);
		mapping = swap_address_space(entry);
	} else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
		mapping = NULL;
	return mapping;
}

int overcommit_ratio_handler(struct ctl_table *table, int write,
			     void __user *buffer, size_t *lenp,
			     loff_t *ppos)
{
	int ret;

	ret = proc_dointvec(table, write, buffer, lenp, ppos);
	if (ret == 0 && write)
		sysctl_overcommit_kbytes = 0;
	return ret;
}

int overcommit_kbytes_handler(struct ctl_table *table, int write,
			     void __user *buffer, size_t *lenp,
			     loff_t *ppos)
{
	int ret;

	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
	if (ret == 0 && write)
		sysctl_overcommit_ratio = 0;
	return ret;
}

/*
 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
 */
unsigned long vm_commit_limit(void)
{
	unsigned long allowed;

	if (sysctl_overcommit_kbytes)
		allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
	else
		allowed = ((totalram_pages - hugetlb_total_pages())
			   * sysctl_overcommit_ratio / 100);
	allowed += total_swap_pages;

	return allowed;
}


/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
Commit	Line	Data
16d69265	1	#include <linux/mm.h>
30992c97 MM	2	#include <linux/slab.h>
30992c97 MM	3	#include <linux/string.h>
3b32123d	4	#include <linux/compiler.h>
b95f1b31	5	#include <linux/export.h>
96840aa0	6	#include <linux/err.h>
3b8f14b4	7	#include <linux/sched.h>
eb36c587	8	#include <linux/security.h>
9800339b	9	#include <linux/swap.h>
33806f06	10	#include <linux/swapops.h>
00619bcc JM	11	#include <linux/mman.h>
	12	#include <linux/hugetlb.h>
	13
96840aa0	14	#include <asm/uaccess.h>
30992c97	15
6038def0 NK	16	#include "internal.h"
6038def0 NK	17
a8d154b0	18	#define CREATE_TRACE_POINTS
ad8d75ff	19	#include <trace/events/kmem.h>
a8d154b0	20
30992c97	21	/**
30992c97	22	* kstrdup - allocate space for and copy an existing string
30992c97 MM	23	* @s: the string to duplicate
	24	* @gfp: the GFP mask used in the kmalloc() call when allocating memory
	25	*/
	26	char kstrdup(const char s, gfp_t gfp)
	27	{
	28	size_t len;
	29	char *buf;
	30
	31	if (!s)
	32	return NULL;
	33
	34	len = strlen(s) + 1;
1d2c8eea	35	buf = kmalloc_track_caller(len, gfp);
30992c97 MM	36	if (buf)
	37	memcpy(buf, s, len);
	38	return buf;
	39	}
	40	EXPORT_SYMBOL(kstrdup);
96840aa0	41
1e66df3e JF	42	/**
	43	* kstrndup - allocate space for and copy an existing string
	44	* @s: the string to duplicate
	45	* @max: read at most @max chars from @s
	46	* @gfp: the GFP mask used in the kmalloc() call when allocating memory
	47	*/
	48	char kstrndup(const char s, size_t max, gfp_t gfp)
	49	{
	50	size_t len;
	51	char *buf;
	52
	53	if (!s)
	54	return NULL;
	55
	56	len = strnlen(s, max);
	57	buf = kmalloc_track_caller(len+1, gfp);
	58	if (buf) {
	59	memcpy(buf, s, len);
	60	buf[len] = '\0';
	61	}
	62	return buf;
	63	}
	64	EXPORT_SYMBOL(kstrndup);
	65
1a2f67b4 AD	66	/**
	67	* kmemdup - duplicate region of memory
	68	*
	69	* @src: memory region to duplicate
	70	* @len: memory region length
	71	* @gfp: GFP mask to use
	72	*/
	73	void kmemdup(const void src, size_t len, gfp_t gfp)
	74	{
	75	void *p;
	76
1d2c8eea	77	p = kmalloc_track_caller(len, gfp);
1a2f67b4 AD	78	if (p)
	79	memcpy(p, src, len);
	80	return p;
	81	}
	82	EXPORT_SYMBOL(kmemdup);
	83
610a77e0 LZ	84	/**
	85	* memdup_user - duplicate memory region from user space
	86	*
	87	* @src: source address in user space
	88	* @len: number of bytes to copy
	89	*
	90	* Returns an ERR_PTR() on failure.
	91	*/
	92	void memdup_user(const void __user src, size_t len)
	93	{
	94	void *p;
	95
	96	/*
	97	* Always use GFP_KERNEL, since copy_from_user() can sleep and
	98	* cause pagefault, which makes it pointless to use GFP_NOFS
	99	* or GFP_ATOMIC.
	100	*/
	101	p = kmalloc_track_caller(len, GFP_KERNEL);
	102	if (!p)
	103	return ERR_PTR(-ENOMEM);
	104
	105	if (copy_from_user(p, src, len)) {
	106	kfree(p);
	107	return ERR_PTR(-EFAULT);
	108	}
	109
	110	return p;
	111	}
	112	EXPORT_SYMBOL(memdup_user);
	113
e21827aa EG	114	static __always_inline void __do_krealloc(const void p, size_t new_size,
	115	gfp_t flags)
	116	{
	117	void *ret;
	118	size_t ks = 0;
	119
	120	if (p)
	121	ks = ksize(p);
	122
	123	if (ks >= new_size)
	124	return (void *)p;
	125
	126	ret = kmalloc_track_caller(new_size, flags);
	127	if (ret && p)
	128	memcpy(ret, p, ks);
	129
	130	return ret;
	131	}
	132
ef2ad80c	133	/**
93bc4e89	134	* __krealloc - like krealloc() but don't free @p.
ef2ad80c CL	135	* @p: object to reallocate memory for.
	136	* @new_size: how many bytes of memory are required.
	137	* @flags: the type of memory to allocate.
	138	*
93bc4e89 PE	139	* This function is like krealloc() except it never frees the originally
	140	* allocated buffer. Use this if you don't want to free the buffer immediately
	141	* like, for example, with RCU.
ef2ad80c	142	*/
93bc4e89	143	void __krealloc(const void p, size_t new_size, gfp_t flags)
ef2ad80c	144	{
93bc4e89	145	if (unlikely(!new_size))
6cb8f913	146	return ZERO_SIZE_PTR;
ef2ad80c	147
e21827aa	148	return __do_krealloc(p, new_size, flags);
ef8b4520	149
93bc4e89 PE	150	}
	151	EXPORT_SYMBOL(__krealloc);
	152
	153	/**
	154	* krealloc - reallocate memory. The contents will remain unchanged.
	155	* @p: object to reallocate memory for.
	156	* @new_size: how many bytes of memory are required.
	157	* @flags: the type of memory to allocate.
	158	*
	159	* The contents of the object pointed to are preserved up to the
	160	* lesser of the new and old sizes. If @p is %NULL, krealloc()
0db10c8e	161	* behaves exactly like kmalloc(). If @new_size is 0 and @p is not a
93bc4e89 PE	162	* %NULL pointer, the object pointed to is freed.
	163	*/
	164	void krealloc(const void p, size_t new_size, gfp_t flags)
	165	{
	166	void *ret;
	167
	168	if (unlikely(!new_size)) {
ef2ad80c	169	kfree(p);
93bc4e89	170	return ZERO_SIZE_PTR;
ef2ad80c	171	}
93bc4e89	172
e21827aa	173	ret = __do_krealloc(p, new_size, flags);
93bc4e89 PE	174	if (ret && p != ret)
	175	kfree(p);
	176
ef2ad80c CL	177	return ret;
	178	}
	179	EXPORT_SYMBOL(krealloc);
	180
3ef0e5ba JW	181	/**
	182	* kzfree - like kfree but zero memory
	183	* @p: object to free memory of
	184	*
	185	* The memory of the object @p points to is zeroed before freed.
	186	* If @p is %NULL, kzfree() does nothing.
a234bdc9 PE	187	*
	188	* Note: this function zeroes the whole allocated buffer which can be a good
	189	* deal bigger than the requested buffer size passed to kmalloc(). So be
	190	* careful when using this function in performance sensitive code.
3ef0e5ba JW	191	*/
	192	void kzfree(const void *p)
	193	{
	194	size_t ks;
	195	void mem = (void )p;
	196
	197	if (unlikely(ZERO_OR_NULL_PTR(mem)))
	198	return;
	199	ks = ksize(mem);
	200	memset(mem, 0, ks);
	201	kfree(mem);
	202	}
	203	EXPORT_SYMBOL(kzfree);
	204
96840aa0 DA	205	/*
96840aa0 DA	206	* strndup_user - duplicate an existing string from user space
96840aa0 DA	207	* @s: The string to duplicate
	208	* @n: Maximum number of bytes to copy, including the trailing NUL.
	209	*/
	210	char strndup_user(const char __user s, long n)
	211	{
	212	char *p;
	213	long length;
	214
	215	length = strnlen_user(s, n);
	216
	217	if (!length)
	218	return ERR_PTR(-EFAULT);
	219
	220	if (length > n)
	221	return ERR_PTR(-EINVAL);
	222
90d74045	223	p = memdup_user(s, length);
96840aa0	224
90d74045 JL	225	if (IS_ERR(p))
90d74045 JL	226	return p;
96840aa0 DA	227
	228	p[length - 1] = '\0';
	229
	230	return p;
	231	}
	232	EXPORT_SYMBOL(strndup_user);
16d69265	233
6038def0 NK	234	void __vma_link_list(struct mm_struct mm, struct vm_area_struct vma,
	235	struct vm_area_struct prev, struct rb_node rb_parent)
	236	{
	237	struct vm_area_struct *next;
	238
	239	vma->vm_prev = prev;
	240	if (prev) {
	241	next = prev->vm_next;
	242	prev->vm_next = vma;
	243	} else {
	244	mm->mmap = vma;
	245	if (rb_parent)
	246	next = rb_entry(rb_parent,
	247	struct vm_area_struct, vm_rb);
	248	else
	249	next = NULL;
	250	}
	251	vma->vm_next = next;
	252	if (next)
	253	next->vm_prev = vma;
	254	}
	255
b7643757 SP	256	/* Check if the vma is being used as a stack by this task */
	257	static int vm_is_stack_for_task(struct task_struct *t,
	258	struct vm_area_struct *vma)
	259	{
	260	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
	261	}
	262
	263	/*
	264	* Check if the vma is being used as a stack.
	265	* If is_group is non-zero, check in the entire thread group or else
	266	* just check in the current task. Returns the pid of the task that
	267	* the vma is stack for.
	268	*/
	269	pid_t vm_is_stack(struct task_struct *task,
	270	struct vm_area_struct *vma, int in_group)
	271	{
	272	pid_t ret = 0;
	273
	274	if (vm_is_stack_for_task(task, vma))
	275	return task->pid;
	276
	277	if (in_group) {
	278	struct task_struct *t;
	279	rcu_read_lock();
	280	if (!pid_alive(task))
	281	goto done;
	282
	283	t = task;
	284	do {
	285	if (vm_is_stack_for_task(t, vma)) {
	286	ret = t->pid;
	287	goto done;
	288	}
	289	} while_each_thread(task, t);
	290	done:
	291	rcu_read_unlock();
	292	}
	293
	294	return ret;
	295	}
	296
efc1a3b1	297	#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
16d69265 AM	298	void arch_pick_mmap_layout(struct mm_struct *mm)
	299	{
	300	mm->mmap_base = TASK_UNMAPPED_BASE;
	301	mm->get_unmapped_area = arch_get_unmapped_area;
16d69265 AM	302	}
16d69265 AM	303	#endif
912985dc	304
45888a0c XG	305	/*
	306	* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
	307	* back to the regular GUP.
25985edc	308	* If the architecture not support this function, simply return with no
45888a0c XG	309	* page pinned
45888a0c XG	310	*/
3b32123d	311	int __weak __get_user_pages_fast(unsigned long start,
45888a0c XG	312	int nr_pages, int write, struct page **pages)
	313	{
	314	return 0;
	315	}
	316	EXPORT_SYMBOL_GPL(__get_user_pages_fast);
	317
9de100d0 AG	318	/**
	319	* get_user_pages_fast() - pin user pages in memory
	320	* @start: starting user address
	321	* @nr_pages: number of pages from start to pin
	322	* @write: whether pages will be written to
	323	* @pages: array that receives pointers to the pages pinned.
	324	* Should be at least nr_pages long.
	325	*
9de100d0 AG	326	* Returns number of pages pinned. This may be fewer than the number
	327	* requested. If nr_pages is 0 or negative, returns 0. If no pages
	328	* were pinned, returns -errno.
d2bf6be8 NP	329	*
	330	* get_user_pages_fast provides equivalent functionality to get_user_pages,
	331	* operating on current and current->mm, with force=0 and vma=NULL. However
	332	* unlike get_user_pages, it must be called without mmap_sem held.
	333	*
	334	* get_user_pages_fast may take mmap_sem and page table locks, so no
	335	* assumptions can be made about lack of locking. get_user_pages_fast is to be
	336	* implemented in a way that is advantageous (vs get_user_pages()) when the
	337	* user memory area is already faulted in and present in ptes. However if the
	338	* pages have to be faulted in, it may turn out to be slightly slower so
	339	* callers need to carefully consider what to use. On many architectures,
	340	* get_user_pages_fast simply falls back to get_user_pages.
9de100d0	341	*/
3b32123d	342	int __weak get_user_pages_fast(unsigned long start,
912985dc RR	343	int nr_pages, int write, struct page **pages)
	344	{
	345	struct mm_struct *mm = current->mm;
	346	int ret;
	347
	348	down_read(&mm->mmap_sem);
	349	ret = get_user_pages(current, mm, start, nr_pages,
	350	write, 0, pages, NULL);
	351	up_read(&mm->mmap_sem);
	352
	353	return ret;
	354	}
	355	EXPORT_SYMBOL_GPL(get_user_pages_fast);
ca2b84cb	356
eb36c587 AV	357	unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
	358	unsigned long len, unsigned long prot,
	359	unsigned long flag, unsigned long pgoff)
	360	{
	361	unsigned long ret;
	362	struct mm_struct *mm = current->mm;
41badc15	363	unsigned long populate;
eb36c587 AV	364
	365	ret = security_mmap_file(file, prot, flag);
	366	if (!ret) {
	367	down_write(&mm->mmap_sem);
bebeb3d6 ML	368	ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
bebeb3d6 ML	369	&populate);
eb36c587	370	up_write(&mm->mmap_sem);
41badc15 ML	371	if (populate)
41badc15 ML	372	mm_populate(ret, populate);
eb36c587 AV	373	}
	374	return ret;
	375	}
	376
	377	unsigned long vm_mmap(struct file *file, unsigned long addr,
	378	unsigned long len, unsigned long prot,
	379	unsigned long flag, unsigned long offset)
	380	{
	381	if (unlikely(offset + PAGE_ALIGN(len) < offset))
	382	return -EINVAL;
	383	if (unlikely(offset & ~PAGE_MASK))
	384	return -EINVAL;
	385
	386	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
	387	}
	388	EXPORT_SYMBOL(vm_mmap);
	389
9800339b SL	390	struct address_space page_mapping(struct page page)
	391	{
	392	struct address_space *mapping = page->mapping;
	393
03e5ac2f MP	394	/* This happens if someone calls flush_dcache_page on slab page */
	395	if (unlikely(PageSlab(page)))
	396	return NULL;
	397
33806f06 SL	398	if (unlikely(PageSwapCache(page))) {
	399	swp_entry_t entry;
	400
	401	entry.val = page_private(page);
	402	mapping = swap_address_space(entry);
d2cf5ad6	403	} else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
9800339b SL	404	mapping = NULL;
	405	return mapping;
	406	}
	407
49f0ce5f JM	408	int overcommit_ratio_handler(struct ctl_table *table, int write,
	409	void __user buffer, size_t lenp,
	410	loff_t *ppos)
	411	{
	412	int ret;
	413
	414	ret = proc_dointvec(table, write, buffer, lenp, ppos);
	415	if (ret == 0 && write)
	416	sysctl_overcommit_kbytes = 0;
	417	return ret;
	418	}
	419
	420	int overcommit_kbytes_handler(struct ctl_table *table, int write,
	421	void __user buffer, size_t lenp,
	422	loff_t *ppos)
	423	{
	424	int ret;
	425
	426	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
	427	if (ret == 0 && write)
	428	sysctl_overcommit_ratio = 0;
	429	return ret;
	430	}
	431
00619bcc JM	432	/*
	433	* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
	434	*/
	435	unsigned long vm_commit_limit(void)
	436	{
49f0ce5f JM	437	unsigned long allowed;
	438
	439	if (sysctl_overcommit_kbytes)
	440	allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
	441	else
	442	allowed = ((totalram_pages - hugetlb_total_pages())
	443	* sysctl_overcommit_ratio / 100);
	444	allowed += total_swap_pages;
	445
	446	return allowed;
00619bcc JM	447	}
	448
	449
ca2b84cb	450	/* Tracepoints definitions. */
ca2b84cb EGM	451	EXPORT_TRACEPOINT_SYMBOL(kmalloc);
	452	EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
	453	EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
	454	EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
	455	EXPORT_TRACEPOINT_SYMBOL(kfree);
	456	EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);