mmap.c 64.2 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5
/*
 * mm/mmap.c
 *
 * Written by obz.
 *
A
Alan Cox 已提交
6
 * Address space accounting code	<alan@lxorguk.ukuu.org.uk>
L
Linus Torvalds 已提交
7 8 9
 */

#include <linux/slab.h>
A
Alexey Dobriyan 已提交
10
#include <linux/backing-dev.h>
L
Linus Torvalds 已提交
11 12 13 14 15 16
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
17
#include <linux/capability.h>
L
Linus Torvalds 已提交
18 19 20 21 22 23 24 25 26 27 28
#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/profile.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
A
Andrea Arcangeli 已提交
29
#include <linux/mmu_notifier.h>
30
#include <linux/perf_event.h>
L
Linus Torvalds 已提交
31 32 33 34

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/tlb.h>
35
#include <asm/mmu_context.h>
L
Linus Torvalds 已提交
36

37 38
#include "internal.h"

39 40 41 42
#ifndef arch_mmap_check
#define arch_mmap_check(addr, len, flags)	(0)
#endif

43 44 45 46
#ifndef arch_rebalance_pgtables
#define arch_rebalance_pgtables(addr, len)		(addr)
#endif

47 48 49 50
static void unmap_region(struct mm_struct *mm,
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end);

L
Linus Torvalds 已提交
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
/*
 * WARNING: the debugging will use recursive algorithms so never enable this
 * unless you know what you are doing.
 */
#undef DEBUG_MM_RB

/* description of effects of mapping type and prot in current implementation.
 * this is due to the limited x86 page protection hardware.  The expected
 * behavior is in parens:
 *
 * map_type	prot
 *		PROT_NONE	PROT_READ	PROT_WRITE	PROT_EXEC
 * MAP_SHARED	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (yes) yes	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *		
 * MAP_PRIVATE	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (copy) copy	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *
 */
pgprot_t protection_map[16] = {
	__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
};

77 78
pgprot_t vm_get_page_prot(unsigned long vm_flags)
{
79 80 81
	return __pgprot(pgprot_val(protection_map[vm_flags &
				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
			pgprot_val(arch_vm_get_page_prot(vm_flags)));
82 83 84
}
EXPORT_SYMBOL(vm_get_page_prot);

L
Linus Torvalds 已提交
85 86
int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
int sysctl_overcommit_ratio = 50;	/* default is 50% */
87
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
88
struct percpu_counter vm_committed_as;
L
Linus Torvalds 已提交
89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105

/*
 * Check that a process has enough memory to allocate a new virtual
 * mapping. 0 means there is enough memory for the allocation to
 * succeed and -ENOMEM implies there is not.
 *
 * We currently support three overcommit policies, which are set via the
 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 *
 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 * Additional code 2002 Jul 20 by Robert Love.
 *
 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 *
 * Note this is a helper function intended to be used by LSMs which
 * wish to use this logic.
 */
106
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
L
Linus Torvalds 已提交
107 108 109 110 111 112 113 114 115 116 117 118 119 120
{
	unsigned long free, allowed;

	vm_acct_memory(pages);

	/*
	 * Sometimes we want to use more memory than we have
	 */
	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
		return 0;

	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
		unsigned long n;

121
		free = global_page_state(NR_FILE_PAGES);
L
Linus Torvalds 已提交
122 123 124 125 126 127 128 129
		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
130
		free += global_page_state(NR_SLAB_RECLAIMABLE);
L
Linus Torvalds 已提交
131 132 133 134 135 136 137 138 139 140 141 142 143 144 145

		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		/*
		 * nr_free_pages() is very expensive on large systems,
		 * only call if we're about to fail.
		 */
		n = nr_free_pages();
146 147 148 149 150 151 152 153 154 155 156 157

		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
		if (n <= totalreserve_pages)
			goto error;
		else
			n -= totalreserve_pages;

		/*
		 * Leave the last 3% for root
		 */
L
Linus Torvalds 已提交
158 159 160 161 162 163
		if (!cap_sys_admin)
			n -= n / 32;
		free += n;

		if (free > pages)
			return 0;
164 165

		goto error;
L
Linus Torvalds 已提交
166 167 168 169 170 171 172 173 174 175 176 177 178
	}

	allowed = (totalram_pages - hugetlb_total_pages())
	       	* sysctl_overcommit_ratio / 100;
	/*
	 * Leave the last 3% for root
	 */
	if (!cap_sys_admin)
		allowed -= allowed / 32;
	allowed += total_swap_pages;

	/* Don't let a single process grow too big:
	   leave 3% of the size of this process for other processes */
A
Alan Cox 已提交
179 180
	if (mm)
		allowed -= mm->total_vm / 32;
L
Linus Torvalds 已提交
181

182
	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
L
Linus Torvalds 已提交
183
		return 0;
184
error:
L
Linus Torvalds 已提交
185 186 187 188 189 190 191 192 193 194 195 196
	vm_unacct_memory(pages);

	return -ENOMEM;
}

/*
 * Requires inode->i_mapping->i_mmap_lock
 */
static void __remove_shared_vm_struct(struct vm_area_struct *vma,
		struct file *file, struct address_space *mapping)
{
	if (vma->vm_flags & VM_DENYWRITE)
197
		atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
L
Linus Torvalds 已提交
198 199 200 201 202 203 204 205 206 207 208 209
	if (vma->vm_flags & VM_SHARED)
		mapping->i_mmap_writable--;

	flush_dcache_mmap_lock(mapping);
	if (unlikely(vma->vm_flags & VM_NONLINEAR))
		list_del_init(&vma->shared.vm_set.list);
	else
		vma_prio_tree_remove(vma, &mapping->i_mmap);
	flush_dcache_mmap_unlock(mapping);
}

/*
210 211
 * Unlink a file-based vm structure from its prio_tree, to hide
 * vma from rmap and vmtruncate before freeing its page tables.
L
Linus Torvalds 已提交
212
 */
213
void unlink_file_vma(struct vm_area_struct *vma)
L
Linus Torvalds 已提交
214 215 216 217 218 219 220 221 222
{
	struct file *file = vma->vm_file;

	if (file) {
		struct address_space *mapping = file->f_mapping;
		spin_lock(&mapping->i_mmap_lock);
		__remove_shared_vm_struct(vma, file, mapping);
		spin_unlock(&mapping->i_mmap_lock);
	}
223 224 225 226 227 228 229 230 231 232
}

/*
 * Close a vm structure and free it, returning the next.
 */
static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *next = vma->vm_next;

	might_sleep();
L
Linus Torvalds 已提交
233 234
	if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);
M
Matt Helsley 已提交
235
	if (vma->vm_file) {
236
		fput(vma->vm_file);
M
Matt Helsley 已提交
237 238 239
		if (vma->vm_flags & VM_EXECUTABLE)
			removed_exe_file_vma(vma->vm_mm);
	}
240
	mpol_put(vma_policy(vma));
L
Linus Torvalds 已提交
241
	kmem_cache_free(vm_area_cachep, vma);
242
	return next;
L
Linus Torvalds 已提交
243 244
}

245
SYSCALL_DEFINE1(brk, unsigned long, brk)
L
Linus Torvalds 已提交
246 247 248 249
{
	unsigned long rlim, retval;
	unsigned long newbrk, oldbrk;
	struct mm_struct *mm = current->mm;
250
	unsigned long min_brk;
L
Linus Torvalds 已提交
251 252 253

	down_write(&mm->mmap_sem);

254 255 256 257 258 259
#ifdef CONFIG_COMPAT_BRK
	min_brk = mm->end_code;
#else
	min_brk = mm->start_brk;
#endif
	if (brk < min_brk)
L
Linus Torvalds 已提交
260
		goto out;
R
Ram Gupta 已提交
261 262 263 264 265 266 267 268

	/*
	 * Check against rlimit here. If this check is done later after the test
	 * of oldbrk with newbrk then it can escape the test and let the data
	 * segment grow beyond its set limit the in case where the limit is
	 * not page aligned -Ram Gupta
	 */
	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
J
Jiri Kosina 已提交
269 270
	if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
			(mm->end_data - mm->start_data) > rlim)
R
Ram Gupta 已提交
271 272
		goto out;

L
Linus Torvalds 已提交
273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317
	newbrk = PAGE_ALIGN(brk);
	oldbrk = PAGE_ALIGN(mm->brk);
	if (oldbrk == newbrk)
		goto set_brk;

	/* Always allow shrinking brk. */
	if (brk <= mm->brk) {
		if (!do_munmap(mm, newbrk, oldbrk-newbrk))
			goto set_brk;
		goto out;
	}

	/* Check against existing mmap mappings. */
	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
		goto out;

	/* Ok, looks good - let it rip. */
	if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
		goto out;
set_brk:
	mm->brk = brk;
out:
	retval = mm->brk;
	up_write(&mm->mmap_sem);
	return retval;
}

#ifdef DEBUG_MM_RB
static int browse_rb(struct rb_root *root)
{
	int i = 0, j;
	struct rb_node *nd, *pn = NULL;
	unsigned long prev = 0, pend = 0;

	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
		struct vm_area_struct *vma;
		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
		if (vma->vm_start < prev)
			printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
		if (vma->vm_start < pend)
			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
		if (vma->vm_start > vma->vm_end)
			printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
		i++;
		pn = nd;
D
David Miller 已提交
318 319
		prev = vma->vm_start;
		pend = vma->vm_end;
L
Linus Torvalds 已提交
320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343
	}
	j = 0;
	for (nd = pn; nd; nd = rb_prev(nd)) {
		j++;
	}
	if (i != j)
		printk("backwards %d, forwards %d\n", j, i), i = 0;
	return i;
}

void validate_mm(struct mm_struct *mm)
{
	int bug = 0;
	int i = 0;
	struct vm_area_struct *tmp = mm->mmap;
	while (tmp) {
		tmp = tmp->vm_next;
		i++;
	}
	if (i != mm->map_count)
		printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
	i = browse_rb(&mm->mm_rb);
	if (i != mm->map_count)
		printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
344
	BUG_ON(bug);
L
Linus Torvalds 已提交
345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370
}
#else
#define validate_mm(mm) do { } while (0)
#endif

static struct vm_area_struct *
find_vma_prepare(struct mm_struct *mm, unsigned long addr,
		struct vm_area_struct **pprev, struct rb_node ***rb_link,
		struct rb_node ** rb_parent)
{
	struct vm_area_struct * vma;
	struct rb_node ** __rb_link, * __rb_parent, * rb_prev;

	__rb_link = &mm->mm_rb.rb_node;
	rb_prev = __rb_parent = NULL;
	vma = NULL;

	while (*__rb_link) {
		struct vm_area_struct *vma_tmp;

		__rb_parent = *__rb_link;
		vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);

		if (vma_tmp->vm_end > addr) {
			vma = vma_tmp;
			if (vma_tmp->vm_start <= addr)
371
				break;
L
Linus Torvalds 已提交
372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410
			__rb_link = &__rb_parent->rb_left;
		} else {
			rb_prev = __rb_parent;
			__rb_link = &__rb_parent->rb_right;
		}
	}

	*pprev = NULL;
	if (rb_prev)
		*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
	*rb_link = __rb_link;
	*rb_parent = __rb_parent;
	return vma;
}

static inline void
__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev, struct rb_node *rb_parent)
{
	if (prev) {
		vma->vm_next = prev->vm_next;
		prev->vm_next = vma;
	} else {
		mm->mmap = vma;
		if (rb_parent)
			vma->vm_next = rb_entry(rb_parent,
					struct vm_area_struct, vm_rb);
		else
			vma->vm_next = NULL;
	}
}

void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
		struct rb_node **rb_link, struct rb_node *rb_parent)
{
	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
}

D
Denys Vlasenko 已提交
411
static void __vma_link_file(struct vm_area_struct *vma)
L
Linus Torvalds 已提交
412
{
Z
ZhenwenXu 已提交
413
	struct file *file;
L
Linus Torvalds 已提交
414 415 416 417 418 419

	file = vma->vm_file;
	if (file) {
		struct address_space *mapping = file->f_mapping;

		if (vma->vm_flags & VM_DENYWRITE)
420
			atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
L
Linus Torvalds 已提交
421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473
		if (vma->vm_flags & VM_SHARED)
			mapping->i_mmap_writable++;

		flush_dcache_mmap_lock(mapping);
		if (unlikely(vma->vm_flags & VM_NONLINEAR))
			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
		else
			vma_prio_tree_insert(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}
}

static void
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
	struct vm_area_struct *prev, struct rb_node **rb_link,
	struct rb_node *rb_parent)
{
	__vma_link_list(mm, vma, prev, rb_parent);
	__vma_link_rb(mm, vma, rb_link, rb_parent);
	__anon_vma_link(vma);
}

static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
			struct vm_area_struct *prev, struct rb_node **rb_link,
			struct rb_node *rb_parent)
{
	struct address_space *mapping = NULL;

	if (vma->vm_file)
		mapping = vma->vm_file->f_mapping;

	if (mapping) {
		spin_lock(&mapping->i_mmap_lock);
		vma->vm_truncate_count = mapping->truncate_count;
	}
	anon_vma_lock(vma);

	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	anon_vma_unlock(vma);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);

	mm->map_count++;
	validate_mm(mm);
}

/*
 * Helper for vma_adjust in the split_vma insert case:
 * insert vm structure into list and rbtree and anon_vma,
 * but it has already been inserted into prio_tree earlier.
 */
Z
ZhenwenXu 已提交
474
static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
475
{
Z
ZhenwenXu 已提交
476 477
	struct vm_area_struct *__vma, *prev;
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
478 479

	__vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
480
	BUG_ON(__vma && __vma->vm_start < vma->vm_end);
L
Linus Torvalds 已提交
481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571
	__vma_link(mm, vma, prev, rb_link, rb_parent);
	mm->map_count++;
}

static inline void
__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev)
{
	prev->vm_next = vma->vm_next;
	rb_erase(&vma->vm_rb, &mm->mm_rb);
	if (mm->mmap_cache == vma)
		mm->mmap_cache = prev;
}

/*
 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 * is already present in an i_mmap tree without adjusting the tree.
 * The following helper function should be used when such adjustments
 * are necessary.  The "insert" vma (if any) is to be inserted
 * before we drop the necessary locks.
 */
void vma_adjust(struct vm_area_struct *vma, unsigned long start,
	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
{
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *next = vma->vm_next;
	struct vm_area_struct *importer = NULL;
	struct address_space *mapping = NULL;
	struct prio_tree_root *root = NULL;
	struct file *file = vma->vm_file;
	struct anon_vma *anon_vma = NULL;
	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
		if (end >= next->vm_end) {
			/*
			 * vma expands, overlapping all the next, and
			 * perhaps the one after too (mprotect case 6).
			 */
again:			remove_next = 1 + (end > next->vm_end);
			end = next->vm_end;
			anon_vma = next->anon_vma;
			importer = vma;
		} else if (end > next->vm_start) {
			/*
			 * vma expands, overlapping part of the next:
			 * mprotect case 5 shifting the boundary up.
			 */
			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
			anon_vma = next->anon_vma;
			importer = vma;
		} else if (end < vma->vm_end) {
			/*
			 * vma shrinks, and !insert tells it's not
			 * split_vma inserting another: so it must be
			 * mprotect case 4 shifting the boundary down.
			 */
			adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
			anon_vma = next->anon_vma;
			importer = next;
		}
	}

	if (file) {
		mapping = file->f_mapping;
		if (!(vma->vm_flags & VM_NONLINEAR))
			root = &mapping->i_mmap;
		spin_lock(&mapping->i_mmap_lock);
		if (importer &&
		    vma->vm_truncate_count != next->vm_truncate_count) {
			/*
			 * unmap_mapping_range might be in progress:
			 * ensure that the expanding vma is rescanned.
			 */
			importer->vm_truncate_count = 0;
		}
		if (insert) {
			insert->vm_truncate_count = vma->vm_truncate_count;
			/*
			 * Put into prio_tree now, so instantiated pages
			 * are visible to arm/parisc __flush_dcache_page
			 * throughout; but we cannot insert into address
			 * space until vma start or end is updated.
			 */
			__vma_link_file(insert);
		}
	}

	/*
	 * When changing only vma->vm_end, we don't really need
572
	 * anon_vma lock.
L
Linus Torvalds 已提交
573
	 */
574
	if (vma->anon_vma && (insert || importer || start != vma->vm_start))
L
Linus Torvalds 已提交
575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635
		anon_vma = vma->anon_vma;
	if (anon_vma) {
		spin_lock(&anon_vma->lock);
		/*
		 * Easily overlooked: when mprotect shifts the boundary,
		 * make sure the expanding vma has anon_vma set if the
		 * shrinking vma had, to cover any anon pages imported.
		 */
		if (importer && !importer->anon_vma) {
			importer->anon_vma = anon_vma;
			__anon_vma_link(importer);
		}
	}

	if (root) {
		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_remove(vma, root);
		if (adjust_next)
			vma_prio_tree_remove(next, root);
	}

	vma->vm_start = start;
	vma->vm_end = end;
	vma->vm_pgoff = pgoff;
	if (adjust_next) {
		next->vm_start += adjust_next << PAGE_SHIFT;
		next->vm_pgoff += adjust_next;
	}

	if (root) {
		if (adjust_next)
			vma_prio_tree_insert(next, root);
		vma_prio_tree_insert(vma, root);
		flush_dcache_mmap_unlock(mapping);
	}

	if (remove_next) {
		/*
		 * vma_merge has merged next into vma, and needs
		 * us to remove next before dropping the locks.
		 */
		__vma_unlink(mm, next, vma);
		if (file)
			__remove_shared_vm_struct(next, file, mapping);
		if (next->anon_vma)
			__anon_vma_merge(vma, next);
	} else if (insert) {
		/*
		 * split_vma has split insert from vma, and needs
		 * us to insert it before dropping the locks
		 * (it may either follow vma or precede it).
		 */
		__insert_vm_struct(mm, insert);
	}

	if (anon_vma)
		spin_unlock(&anon_vma->lock);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);

	if (remove_next) {
M
Matt Helsley 已提交
636
		if (file) {
L
Linus Torvalds 已提交
637
			fput(file);
M
Matt Helsley 已提交
638 639 640
			if (next->vm_flags & VM_EXECUTABLE)
				removed_exe_file_vma(mm);
		}
L
Linus Torvalds 已提交
641
		mm->map_count--;
642
		mpol_put(vma_policy(next));
L
Linus Torvalds 已提交
643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664
		kmem_cache_free(vm_area_cachep, next);
		/*
		 * In mprotect's case 6 (see comments on vma_merge),
		 * we must remove another next too. It would clutter
		 * up the code too much to do both in one go.
		 */
		if (remove_next == 2) {
			next = vma->vm_next;
			goto again;
		}
	}

	validate_mm(mm);
}

/*
 * If the vma has a ->close operation then the driver probably needs to release
 * per-vma resources, so we don't attempt to merge those.
 */
static inline int is_mergeable_vma(struct vm_area_struct *vma,
			struct file *file, unsigned long vm_flags)
{
H
Hugh Dickins 已提交
665 666
	/* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
	if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
L
Linus Torvalds 已提交
667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861
		return 0;
	if (vma->vm_file != file)
		return 0;
	if (vma->vm_ops && vma->vm_ops->close)
		return 0;
	return 1;
}

static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
					struct anon_vma *anon_vma2)
{
	return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * in front of (at a lower virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 *
 * We don't check here for the merged mmap wrapping around the end of pagecache
 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 * wrap, nor mmaps which cover the final page at index -1UL.
 */
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
		if (vma->vm_pgoff == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * beyond (at a higher virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 */
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
		pgoff_t vm_pglen;
		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 * whether that can be merged with its predecessor or its successor.
 * Or both (it neatly fills a hole).
 *
 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 * certain not to be mapped by the time vma_merge is called; but when
 * called for mprotect, it is certain to be already mapped (either at
 * an offset within prev, or at the start of next), and the flags of
 * this area are about to be changed to vm_flags - and the no-change
 * case has already been eliminated.
 *
 * The following mprotect cases have to be considered, where AAAA is
 * the area passed down from mprotect_fixup, never extending beyond one
 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 *
 *     AAAA             AAAA                AAAA          AAAA
 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 *    cannot merge    might become    might become    might become
 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 *    mremap move:                                    PPPPNNNNNNNN 8
 *        AAAA
 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 *    might become    case 1 below    case 2 below    case 3 below
 *
 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 */
struct vm_area_struct *vma_merge(struct mm_struct *mm,
			struct vm_area_struct *prev, unsigned long addr,
			unsigned long end, unsigned long vm_flags,
		     	struct anon_vma *anon_vma, struct file *file,
			pgoff_t pgoff, struct mempolicy *policy)
{
	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
	struct vm_area_struct *area, *next;

	/*
	 * We later require that vma->vm_flags == vm_flags,
	 * so this tests vma->vm_flags & VM_SPECIAL, too.
	 */
	if (vm_flags & VM_SPECIAL)
		return NULL;

	if (prev)
		next = prev->vm_next;
	else
		next = mm->mmap;
	area = next;
	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
		next = next->vm_next;

	/*
	 * Can it merge with the predecessor?
	 */
	if (prev && prev->vm_end == addr &&
  			mpol_equal(vma_policy(prev), policy) &&
			can_vma_merge_after(prev, vm_flags,
						anon_vma, file, pgoff)) {
		/*
		 * OK, it can.  Can we now merge in the successor as well?
		 */
		if (next && end == next->vm_start &&
				mpol_equal(policy, vma_policy(next)) &&
				can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen) &&
				is_mergeable_anon_vma(prev->anon_vma,
						      next->anon_vma)) {
							/* cases 1, 6 */
			vma_adjust(prev, prev->vm_start,
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
			vma_adjust(prev, prev->vm_start,
				end, prev->vm_pgoff, NULL);
		return prev;
	}

	/*
	 * Can this new request be merged in front of next?
	 */
	if (next && end == next->vm_start &&
 			mpol_equal(policy, vma_policy(next)) &&
			can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen)) {
		if (prev && addr < prev->vm_end)	/* case 4 */
			vma_adjust(prev, prev->vm_start,
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
			vma_adjust(area, addr, next->vm_end,
				next->vm_pgoff - pglen, NULL);
		return area;
	}

	return NULL;
}

/*
 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 * neighbouring vmas for a suitable anon_vma, before it goes off
 * to allocate a new anon_vma.  It checks because a repetitive
 * sequence of mprotects and faults may otherwise lead to distinct
 * anon_vmas being allocated, preventing vma merge in subsequent
 * mprotect.
 */
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *near;
	unsigned long vm_flags;

	near = vma->vm_next;
	if (!near)
		goto try_prev;

	/*
	 * Since only mprotect tries to remerge vmas, match flags
	 * which might be mprotected into each other later on.
	 * Neither mlock nor madvise tries to remerge at present,
	 * so leave their flags as obstructing a merge.
	 */
	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);

	if (near->anon_vma && vma->vm_end == near->vm_start &&
 			mpol_equal(vma_policy(vma), vma_policy(near)) &&
			can_vma_merge_before(near, vm_flags,
				NULL, vma->vm_file, vma->vm_pgoff +
				((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
		return near->anon_vma;
try_prev:
	/*
	 * It is potentially slow to have to call find_vma_prev here.
	 * But it's only on the first write fault on the vma, not
	 * every time, and we could devise a way to avoid it later
	 * (e.g. stash info in next's anon_vma_node when assigning
	 * an anon_vma, or when trying vma_merge).  Another time.
	 */
862
	BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
L
Linus Torvalds 已提交
863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886
	if (!near)
		goto none;

	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);

	if (near->anon_vma && near->vm_end == vma->vm_start &&
  			mpol_equal(vma_policy(near), vma_policy(vma)) &&
			can_vma_merge_after(near, vm_flags,
				NULL, vma->vm_file, vma->vm_pgoff))
		return near->anon_vma;
none:
	/*
	 * There's no absolute need to look only at touching neighbours:
	 * we could search further afield for "compatible" anon_vmas.
	 * But it would probably just be a waste of time searching,
	 * or lead to too many vmas hanging off the same anon_vma.
	 * We're trying to allow mprotect remerging later on,
	 * not trying to minimize memory used for anon_vmas.
	 */
	return NULL;
}

#ifdef CONFIG_PROC_FS
887
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
L
Linus Torvalds 已提交
888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

	if (file) {
		mm->shared_vm += pages;
		if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
			mm->exec_vm += pages;
	} else if (flags & stack_flags)
		mm->stack_vm += pages;
	if (flags & (VM_RESERVED|VM_IO))
		mm->reserved_vm += pages;
}
#endif /* CONFIG_PROC_FS */

/*
905
 * The caller must hold down_write(&current->mm->mmap_sem).
L
Linus Torvalds 已提交
906 907
 */

Z
ZhenwenXu 已提交
908
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
Linus Torvalds 已提交
909 910 911 912 913 914 915
			unsigned long len, unsigned long prot,
			unsigned long flags, unsigned long pgoff)
{
	struct mm_struct * mm = current->mm;
	struct inode *inode;
	unsigned int vm_flags;
	int error;
M
Miklos Szeredi 已提交
916
	unsigned long reqprot = prot;
L
Linus Torvalds 已提交
917 918 919 920 921 922 923 924

	/*
	 * Does the application expect PROT_READ to imply PROT_EXEC?
	 *
	 * (the exception is when the underlying filesystem is noexec
	 *  mounted, in which case we dont add PROT_EXEC.)
	 */
	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
925
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
L
Linus Torvalds 已提交
926 927 928 929 930
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

931 932 933
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

L
Linus Torvalds 已提交
934 935
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
936
	if (!len)
L
Linus Torvalds 已提交
937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960
		return -ENOMEM;

	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
               return -EOVERFLOW;

	/* Too many mappings? */
	if (mm->map_count > sysctl_max_map_count)
		return -ENOMEM;

	/* Obtain the address to map to. we verify (or select) it and ensure
	 * that it represents a valid section of the address space.
	 */
	addr = get_unmapped_area(file, addr, len, pgoff, flags);
	if (addr & ~PAGE_MASK)
		return addr;

	/* Do simple checking here so the lower-level routines won't have
	 * to. we assume access permissions have been handled by the open
	 * of the memory object, so we don't do any here.
	 */
	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;

H
Huang Shijie 已提交
961
	if (flags & MAP_LOCKED)
L
Linus Torvalds 已提交
962 963
		if (!can_do_mlock())
			return -EPERM;
964

L
Linus Torvalds 已提交
965 966 967
	/* mlock MCL_FUTURE? */
	if (vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
968 969
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
L
Linus Torvalds 已提交
970
		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
971
		lock_limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
972 973 974 975
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

976
	inode = file ? file->f_path.dentry->d_inode : NULL;
L
Linus Torvalds 已提交
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004

	if (file) {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
			if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure we don't allow writing to an append-only
			 * file..
			 */
			if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure there are no mandatory locks on the file.
			 */
			if (locks_verify_locked(inode))
				return -EAGAIN;

			vm_flags |= VM_SHARED | VM_MAYSHARE;
			if (!(file->f_mode & FMODE_WRITE))
				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);

			/* fall through */
		case MAP_PRIVATE:
			if (!(file->f_mode & FMODE_READ))
				return -EACCES;
1005
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
1006 1007 1008 1009 1010 1011 1012
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

			if (!file->f_op || !file->f_op->mmap)
				return -ENODEV;
L
Linus Torvalds 已提交
1013 1014 1015 1016 1017 1018 1019 1020
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1021 1022 1023 1024
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
L
Linus Torvalds 已提交
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
			vm_flags |= VM_SHARED | VM_MAYSHARE;
			break;
		case MAP_PRIVATE:
			/*
			 * Set pgoff according to addr for anon_vma.
			 */
			pgoff = addr >> PAGE_SHIFT;
			break;
		default:
			return -EINVAL;
		}
	}

1038
	error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
L
Linus Torvalds 已提交
1039 1040
	if (error)
		return error;
1041

1042
	return mmap_region(file, addr, len, flags, vm_flags, pgoff);
M
Miklos Szeredi 已提交
1043 1044 1045
}
EXPORT_SYMBOL(do_mmap_pgoff);

A
Alexey Dobriyan 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
/*
 * Some shared mappigns will want the pages marked read-only
 * to track write events. If so, we'll downgrade vm_page_prot
 * to the private version (using protection_map[] without the
 * VM_SHARED bit).
 */
int vma_wants_writenotify(struct vm_area_struct *vma)
{
	unsigned int vm_flags = vma->vm_flags;

	/* If it was private or non-writable, the write bit is already clear */
	if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
		return 0;

	/* The backer wishes to know when pages are first written to? */
	if (vma->vm_ops && vma->vm_ops->page_mkwrite)
		return 1;

	/* The open routine did something to the protections already? */
	if (pgprot_val(vma->vm_page_prot) !=
1066
	    pgprot_val(vm_get_page_prot(vm_flags)))
A
Alexey Dobriyan 已提交
1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
		return 0;

	/* Specialty mapping? */
	if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
		return 0;

	/* Can the mapping track the dirty pages? */
	return vma->vm_file && vma->vm_file->f_mapping &&
		mapping_cap_account_dirty(vma->vm_file->f_mapping);
}

1078 1079
/*
 * We account for memory if it's a private writeable mapping,
1080
 * not hugepages and VM_NORESERVE wasn't set.
1081
 */
1082
static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1083
{
1084 1085 1086 1087 1088 1089 1090
	/*
	 * hugetlb has its own accounting separate from the core VM
	 * VM_HUGETLB may not be set yet so we cannot check for that flag.
	 */
	if (file && is_file_hugepages(file))
		return 0;

1091 1092 1093
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

M
Miklos Szeredi 已提交
1094 1095
unsigned long mmap_region(struct file *file, unsigned long addr,
			  unsigned long len, unsigned long flags,
1096
			  unsigned int vm_flags, unsigned long pgoff)
M
Miklos Szeredi 已提交
1097 1098 1099 1100 1101 1102 1103 1104 1105
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
	int correct_wcount = 0;
	int error;
	struct rb_node **rb_link, *rb_parent;
	unsigned long charged = 0;
	struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;

L
Linus Torvalds 已提交
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	if (vma && vma->vm_start < addr + len) {
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

	/* Check against address space limit. */
A
akpm@osdl.org 已提交
1117
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
1118 1119
		return -ENOMEM;

1120 1121
	/*
	 * Set 'VM_NORESERVE' if we should not account for the
1122
	 * memory use of this mapping.
1123
	 */
1124 1125 1126 1127 1128 1129 1130 1131 1132
	if ((flags & MAP_NORESERVE)) {
		/* We honor MAP_NORESERVE if allowed to overcommit */
		if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
			vm_flags |= VM_NORESERVE;

		/* hugetlb applies strict overcommit unless MAP_NORESERVE */
		if (file && is_file_hugepages(file))
			vm_flags |= VM_NORESERVE;
	}
1133

1134 1135 1136
	/*
	 * Private writable mapping: check memory availability
	 */
1137
	if (accountable_mapping(file, vm_flags)) {
1138 1139 1140 1141
		charged = len >> PAGE_SHIFT;
		if (security_vm_enough_memory(charged))
			return -ENOMEM;
		vm_flags |= VM_ACCOUNT;
L
Linus Torvalds 已提交
1142 1143 1144
	}

	/*
1145
	 * Can we just expand an old mapping?
L
Linus Torvalds 已提交
1146
	 */
1147 1148 1149
	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
	if (vma)
		goto out;
L
Linus Torvalds 已提交
1150 1151 1152 1153 1154 1155

	/*
	 * Determine the object being mapped and call the appropriate
	 * specific mapper. the address has already been validated, but
	 * not unmapped, but the maps are removed from the list.
	 */
P
Pekka Enberg 已提交
1156
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1157 1158 1159 1160 1161 1162 1163 1164 1165
	if (!vma) {
		error = -ENOMEM;
		goto unacct_error;
	}

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_flags = vm_flags;
1166
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
Linus Torvalds 已提交
1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
	vma->vm_pgoff = pgoff;

	if (file) {
		error = -EINVAL;
		if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
			goto free_vma;
		if (vm_flags & VM_DENYWRITE) {
			error = deny_write_access(file);
			if (error)
				goto free_vma;
			correct_wcount = 1;
		}
		vma->vm_file = file;
		get_file(file);
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
M
Matt Helsley 已提交
1184 1185
		if (vm_flags & VM_EXECUTABLE)
			added_exe_file_vma(mm);
1186 1187 1188 1189 1190 1191 1192 1193 1194

		/* Can addr have changed??
		 *
		 * Answer: Yes, several device drivers can do it in their
		 *         f_op->mmap method. -DaveM
		 */
		addr = vma->vm_start;
		pgoff = vma->vm_pgoff;
		vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
1195 1196 1197 1198 1199 1200
	} else if (vm_flags & VM_SHARED) {
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

1201
	if (vma_wants_writenotify(vma))
1202
		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1203

1204 1205
	vma_link(mm, vma, prev, rb_link, rb_parent);
	file = vma->vm_file;
1206 1207 1208 1209 1210

	/* Once vma denies write, undo our temporary denial count */
	if (correct_wcount)
		atomic_inc(&inode->i_writecount);
out:
1211
	perf_event_mmap(vma);
1212

L
Linus Torvalds 已提交
1213
	mm->total_vm += len >> PAGE_SHIFT;
1214
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
1215
	if (vm_flags & VM_LOCKED) {
1216 1217 1218 1219 1220 1221 1222 1223
		/*
		 * makes pages present; downgrades, drops, reacquires mmap_sem
		 */
		long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
		if (nr_pages < 0)
			return nr_pages;	/* vma gone! */
		mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
	} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1224
		make_pages_present(addr, addr + len);
L
Linus Torvalds 已提交
1225 1226 1227 1228 1229 1230 1231 1232 1233
	return addr;

unmap_and_free_vma:
	if (correct_wcount)
		atomic_inc(&inode->i_writecount);
	vma->vm_file = NULL;
	fput(file);

	/* Undo any partial mapping done by a device driver. */
1234 1235
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
L
Linus Torvalds 已提交
1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266
free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

/* Get an address range which is currently unmapped.
 * For shmat() with addr=0.
 *
 * Ugly calling convention alert:
 * Return value with the low bits set means error value,
 * ie
 *	if (ret & ~PAGE_MASK)
 *		error = ret;
 *
 * This function "knows" that -ENOMEM has the bits set.
 */
#ifndef HAVE_ARCH_UNMAPPED_AREA
unsigned long
arch_get_unmapped_area(struct file *filp, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long start_addr;

	if (len > TASK_SIZE)
		return -ENOMEM;

1267 1268 1269
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1270 1271 1272 1273 1274 1275 1276
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}
1277 1278 1279 1280 1281 1282
	if (len > mm->cached_hole_size) {
	        start_addr = addr = mm->free_area_cache;
	} else {
	        start_addr = addr = TASK_UNMAPPED_BASE;
	        mm->cached_hole_size = 0;
	}
L
Linus Torvalds 已提交
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292

full_search:
	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
		/* At this point:  (!vma || addr < vma->vm_end). */
		if (TASK_SIZE - len < addr) {
			/*
			 * Start a new search - just in case we missed
			 * some holes.
			 */
			if (start_addr != TASK_UNMAPPED_BASE) {
1293 1294 1295
				addr = TASK_UNMAPPED_BASE;
			        start_addr = addr;
				mm->cached_hole_size = 0;
L
Linus Torvalds 已提交
1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306
				goto full_search;
			}
			return -ENOMEM;
		}
		if (!vma || addr + len <= vma->vm_start) {
			/*
			 * Remember the place where we stopped the search:
			 */
			mm->free_area_cache = addr + len;
			return addr;
		}
1307 1308
		if (addr + mm->cached_hole_size < vma->vm_start)
		        mm->cached_hole_size = vma->vm_start - addr;
L
Linus Torvalds 已提交
1309 1310 1311 1312 1313
		addr = vma->vm_end;
	}
}
#endif	

1314
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1315 1316 1317 1318
{
	/*
	 * Is this a new hole at the lowest possible address?
	 */
1319 1320 1321 1322
	if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
		mm->free_area_cache = addr;
		mm->cached_hole_size = ~0UL;
	}
L
Linus Torvalds 已提交
1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342
}

/*
 * This mmap-allocator allocates new areas top-down from below the
 * stack's low limit (the base):
 */
#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
			  const unsigned long len, const unsigned long pgoff,
			  const unsigned long flags)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm = current->mm;
	unsigned long addr = addr0;

	/* requested length too big for entire address space */
	if (len > TASK_SIZE)
		return -ENOMEM;

1343 1344 1345
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1346 1347 1348 1349 1350 1351 1352 1353 1354
	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

1355 1356 1357 1358 1359 1360
	/* check if free_area_cache is useful for us */
	if (len <= mm->cached_hole_size) {
 	        mm->cached_hole_size = 0;
 		mm->free_area_cache = mm->mmap_base;
 	}

L
Linus Torvalds 已提交
1361 1362 1363 1364
	/* either no address requested or can't fit in requested address hole */
	addr = mm->free_area_cache;

	/* make sure it can fit in the remaining address space */
1365
	if (addr > len) {
L
Linus Torvalds 已提交
1366 1367 1368 1369 1370 1371
		vma = find_vma(mm, addr-len);
		if (!vma || addr <= vma->vm_start)
			/* remember the address as a hint for next time */
			return (mm->free_area_cache = addr-len);
	}

1372 1373 1374
	if (mm->mmap_base < len)
		goto bottomup;

L
Linus Torvalds 已提交
1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387
	addr = mm->mmap_base-len;

	do {
		/*
		 * Lookup failure means no vma is above this address,
		 * else if new region fits below vma->vm_start,
		 * return with success:
		 */
		vma = find_vma(mm, addr);
		if (!vma || addr+len <= vma->vm_start)
			/* remember the address as a hint for next time */
			return (mm->free_area_cache = addr);

1388 1389 1390 1391
 		/* remember the largest hole we saw so far */
 		if (addr + mm->cached_hole_size < vma->vm_start)
 		        mm->cached_hole_size = vma->vm_start - addr;

L
Linus Torvalds 已提交
1392 1393
		/* try just below the current vma->vm_start */
		addr = vma->vm_start-len;
1394
	} while (len < vma->vm_start);
L
Linus Torvalds 已提交
1395

1396
bottomup:
L
Linus Torvalds 已提交
1397 1398 1399 1400 1401 1402
	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
1403 1404
	mm->cached_hole_size = ~0UL;
  	mm->free_area_cache = TASK_UNMAPPED_BASE;
L
Linus Torvalds 已提交
1405 1406 1407 1408 1409
	addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
	/*
	 * Restore the topdown base:
	 */
	mm->free_area_cache = mm->mmap_base;
1410
	mm->cached_hole_size = ~0UL;
L
Linus Torvalds 已提交
1411 1412 1413 1414 1415

	return addr;
}
#endif

1416
void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1417 1418 1419 1420
{
	/*
	 * Is this a new hole at the highest possible address?
	 */
1421 1422
	if (addr > mm->free_area_cache)
		mm->free_area_cache = addr;
L
Linus Torvalds 已提交
1423 1424

	/* dont allow allocations above current base */
1425 1426
	if (mm->free_area_cache > mm->mmap_base)
		mm->free_area_cache = mm->mmap_base;
L
Linus Torvalds 已提交
1427 1428 1429 1430 1431 1432
}

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
1433 1434 1435
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

1436 1437 1438 1439 1440 1441 1442 1443
	unsigned long error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

	/* Careful about overflows.. */
	if (len > TASK_SIZE)
		return -ENOMEM;

1444 1445 1446 1447 1448 1449
	get_area = current->mm->get_unmapped_area;
	if (file && file->f_op && file->f_op->get_unmapped_area)
		get_area = file->f_op->get_unmapped_area;
	addr = get_area(file, addr, len, pgoff, flags);
	if (IS_ERR_VALUE(addr))
		return addr;
L
Linus Torvalds 已提交
1450

1451 1452 1453 1454
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
1455

1456
	return arch_rebalance_pgtables(addr, len);
L
Linus Torvalds 已提交
1457 1458 1459 1460 1461
}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
ZhenwenXu 已提交
1462
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504
{
	struct vm_area_struct *vma = NULL;

	if (mm) {
		/* Check the cache first. */
		/* (Cache hit rate is typically around 35%.) */
		vma = mm->mmap_cache;
		if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
			struct rb_node * rb_node;

			rb_node = mm->mm_rb.rb_node;
			vma = NULL;

			while (rb_node) {
				struct vm_area_struct * vma_tmp;

				vma_tmp = rb_entry(rb_node,
						struct vm_area_struct, vm_rb);

				if (vma_tmp->vm_end > addr) {
					vma = vma_tmp;
					if (vma_tmp->vm_start <= addr)
						break;
					rb_node = rb_node->rb_left;
				} else
					rb_node = rb_node->rb_right;
			}
			if (vma)
				mm->mmap_cache = vma;
		}
	}
	return vma;
}

EXPORT_SYMBOL(find_vma);

/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
			struct vm_area_struct **pprev)
{
	struct vm_area_struct *vma = NULL, *prev = NULL;
Z
ZhenwenXu 已提交
1505
	struct rb_node *rb_node;
L
Linus Torvalds 已提交
1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
	if (!mm)
		goto out;

	/* Guard against addr being lower than the first VMA */
	vma = mm->mmap;

	/* Go through the RB tree quickly. */
	rb_node = mm->mm_rb.rb_node;

	while (rb_node) {
		struct vm_area_struct *vma_tmp;
		vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);

		if (addr < vma_tmp->vm_end) {
			rb_node = rb_node->rb_left;
		} else {
			prev = vma_tmp;
			if (!prev->vm_next || (addr < prev->vm_next->vm_end))
				break;
			rb_node = rb_node->rb_right;
		}
	}

out:
	*pprev = prev;
	return prev ? prev->vm_next : vma;
}

/*
 * Verify that the stack growth is acceptable and
 * update accounting. This is shared with both the
 * grow-up and grow-down cases.
 */
Z
ZhenwenXu 已提交
1539
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
1540 1541 1542
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
1543
	unsigned long new_start;
L
Linus Torvalds 已提交
1544 1545

	/* address space limit tests */
A
akpm@osdl.org 已提交
1546
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562
		return -ENOMEM;

	/* Stack limit test */
	if (size > rlim[RLIMIT_STACK].rlim_cur)
		return -ENOMEM;

	/* mlock limit tests */
	if (vma->vm_flags & VM_LOCKED) {
		unsigned long locked;
		unsigned long limit;
		locked = mm->locked_vm + grow;
		limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

1563 1564 1565 1566 1567 1568
	/* Check to ensure the stack will not grow into a hugetlb-only region */
	new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
			vma->vm_end - size;
	if (is_hugepage_only_range(vma->vm_mm, new_start, size))
		return -EFAULT;

L
Linus Torvalds 已提交
1569 1570 1571 1572
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
1573
	if (security_vm_enough_memory_mm(mm, grow))
L
Linus Torvalds 已提交
1574 1575 1576 1577 1578 1579
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	mm->total_vm += grow;
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
1580
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
1581 1582 1583
	return 0;
}

H
Hugh Dickins 已提交
1584
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
1585
/*
H
Hugh Dickins 已提交
1586 1587
 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
 * vma is the last one with address > vma->vm_end.  Have to extend vma.
L
Linus Torvalds 已提交
1588
 */
1589
#ifndef CONFIG_IA64
D
Denys Vlasenko 已提交
1590
static
H
Hugh Dickins 已提交
1591 1592
#endif
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610
{
	int error;

	if (!(vma->vm_flags & VM_GROWSUP))
		return -EFAULT;

	/*
	 * We must make sure the anon_vma is allocated
	 * so that the anon_vma locking is not a noop.
	 */
	if (unlikely(anon_vma_prepare(vma)))
		return -ENOMEM;
	anon_vma_lock(vma);

	/*
	 * vma->vm_start/vm_end cannot change under us because the caller
	 * is required to hold the mmap_sem in read mode.  We need the
	 * anon_vma lock to serialize against concurrent expand_stacks.
1611
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
1612
	 */
1613 1614 1615 1616 1617 1618
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
		anon_vma_unlock(vma);
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634
	error = 0;

	/* Somebody else might have raced and expanded it already */
	if (address > vma->vm_end) {
		unsigned long size, grow;

		size = address - vma->vm_start;
		grow = (address - vma->vm_end) >> PAGE_SHIFT;

		error = acct_stack_growth(vma, size, grow);
		if (!error)
			vma->vm_end = address;
	}
	anon_vma_unlock(vma);
	return error;
}
H
Hugh Dickins 已提交
1635 1636
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
1637 1638 1639
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
D
Denys Vlasenko 已提交
1640
static int expand_downwards(struct vm_area_struct *vma,
1641
				   unsigned long address)
L
Linus Torvalds 已提交
1642 1643 1644 1645 1646 1647 1648 1649 1650
{
	int error;

	/*
	 * We must make sure the anon_vma is allocated
	 * so that the anon_vma locking is not a noop.
	 */
	if (unlikely(anon_vma_prepare(vma)))
		return -ENOMEM;
1651 1652

	address &= PAGE_MASK;
1653
	error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1654 1655 1656
	if (error)
		return error;

L
Linus Torvalds 已提交
1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681
	anon_vma_lock(vma);

	/*
	 * vma->vm_start/vm_end cannot change under us because the caller
	 * is required to hold the mmap_sem in read mode.  We need the
	 * anon_vma lock to serialize against concurrent expand_stacks.
	 */

	/* Somebody else might have raced and expanded it already */
	if (address < vma->vm_start) {
		unsigned long size, grow;

		size = vma->vm_end - address;
		grow = (vma->vm_start - address) >> PAGE_SHIFT;

		error = acct_stack_growth(vma, size, grow);
		if (!error) {
			vma->vm_start = address;
			vma->vm_pgoff -= grow;
		}
	}
	anon_vma_unlock(vma);
	return error;
}

1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701
int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
{
	return expand_downwards(vma, address);
}

#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return expand_upwards(vma, address);
}

struct vm_area_struct *
find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
	struct vm_area_struct *vma, *prev;

	addr &= PAGE_MASK;
	vma = find_vma_prev(mm, addr, &prev);
	if (vma && (vma->vm_start <= addr))
		return vma;
1702
	if (!prev || expand_stack(prev, addr))
1703
		return NULL;
1704 1705 1706 1707
	if (prev->vm_flags & VM_LOCKED) {
		if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
			return NULL;	/* vma gone! */
	}
1708 1709 1710 1711 1712 1713 1714 1715
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732
struct vm_area_struct *
find_extend_vma(struct mm_struct * mm, unsigned long addr)
{
	struct vm_area_struct * vma;
	unsigned long start;

	addr &= PAGE_MASK;
	vma = find_vma(mm,addr);
	if (!vma)
		return NULL;
	if (vma->vm_start <= addr)
		return vma;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		return NULL;
	start = vma->vm_start;
	if (expand_stack(vma, addr))
		return NULL;
1733 1734 1735 1736
	if (vma->vm_flags & VM_LOCKED) {
		if (mlock_vma_pages_range(vma, addr, start) < 0)
			return NULL;	/* vma gone! */
	}
L
Linus Torvalds 已提交
1737 1738 1739 1740 1741
	return vma;
}
#endif

/*
1742
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
1743
 * so release them, and do the vma updates.
1744 1745
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
1746
 */
1747
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
1748
{
1749 1750
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
1751
	do {
1752 1753 1754 1755
		long nrpages = vma_pages(vma);

		mm->total_vm -= nrpages;
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1756
		vma = remove_vma(vma);
1757
	} while (vma);
L
Linus Torvalds 已提交
1758 1759 1760 1761 1762 1763
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
1764
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
1765 1766
 */
static void unmap_region(struct mm_struct *mm,
1767 1768
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
1769
{
1770
	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
1771 1772 1773 1774 1775
	struct mmu_gather *tlb;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
1776
	update_hiwater_rss(mm);
1777
	unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
L
Linus Torvalds 已提交
1778
	vm_unacct_memory(nr_accounted);
1779
	free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1780
				 next? next->vm_start: 0);
L
Linus Torvalds 已提交
1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793
	tlb_finish_mmu(tlb, start, end);
}

/*
 * Create a list of vma's touched by the unmap, removing them from the mm's
 * vma list as we go..
 */
static void
detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
	struct vm_area_struct *prev, unsigned long end)
{
	struct vm_area_struct **insertion_point;
	struct vm_area_struct *tail_vma = NULL;
1794
	unsigned long addr;
L
Linus Torvalds 已提交
1795 1796 1797 1798 1799 1800 1801 1802 1803 1804

	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
	do {
		rb_erase(&vma->vm_rb, &mm->mm_rb);
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
	tail_vma->vm_next = NULL;
1805 1806 1807 1808 1809
	if (mm->unmap_area == arch_unmap_area)
		addr = prev ? prev->vm_end : mm->mmap_base;
	else
		addr = vma ?  vma->vm_start : mm->mmap_base;
	mm->unmap_area(mm, addr);
L
Linus Torvalds 已提交
1810 1811 1812 1813 1814
	mm->mmap_cache = NULL;		/* Kill the cache. */
}

/*
 * Split a vma into two pieces at address 'addr', a new vma is allocated
1815
 * either for the first part or the tail.
L
Linus Torvalds 已提交
1816 1817 1818 1819 1820 1821 1822
 */
int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
	      unsigned long addr, int new_below)
{
	struct mempolicy *pol;
	struct vm_area_struct *new;

1823 1824
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
1825 1826 1827 1828 1829
		return -EINVAL;

	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;

1830
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843
	if (!new)
		return -ENOMEM;

	/* most fields are the same, copy all, and then fixup */
	*new = *vma;

	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

1844
	pol = mpol_dup(vma_policy(vma));
L
Linus Torvalds 已提交
1845 1846 1847 1848 1849 1850
	if (IS_ERR(pol)) {
		kmem_cache_free(vm_area_cachep, new);
		return PTR_ERR(pol);
	}
	vma_set_policy(new, pol);

M
Matt Helsley 已提交
1851
	if (new->vm_file) {
L
Linus Torvalds 已提交
1852
		get_file(new->vm_file);
M
Matt Helsley 已提交
1853 1854 1855
		if (vma->vm_flags & VM_EXECUTABLE)
			added_exe_file_vma(mm);
	}
L
Linus Torvalds 已提交
1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876

	if (new->vm_ops && new->vm_ops->open)
		new->vm_ops->open(new);

	if (new_below)
		vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
		vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);

	return 0;
}

/* Munmap is split into 2 main parts -- this part which finds
 * what needs doing, and the areas themselves, which do the
 * work.  This now handles partial unmappings.
 * Jeremy Fitzhardinge <jeremy@goop.org>
 */
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
	unsigned long end;
1877
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
1878 1879 1880 1881 1882 1883 1884 1885

	if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
		return -EINVAL;

	if ((len = PAGE_ALIGN(len)) == 0)
		return -EINVAL;

	/* Find the first overlapping VMA */
1886 1887
	vma = find_vma_prev(mm, start, &prev);
	if (!vma)
L
Linus Torvalds 已提交
1888
		return 0;
1889
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
1890 1891 1892

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
1893
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
1894 1895 1896 1897 1898 1899 1900 1901 1902
		return 0;

	/*
	 * If we need to split any vma, do it now to save pain later.
	 *
	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
	 * unmapped vm_area_struct will remain in use: so lower split_vma
	 * places tmp vma above, and higher split_vma places tmp vma below.
	 */
1903 1904
	if (start > vma->vm_start) {
		int error = split_vma(mm, vma, start, 0);
L
Linus Torvalds 已提交
1905 1906
		if (error)
			return error;
1907
		prev = vma;
L
Linus Torvalds 已提交
1908 1909 1910 1911 1912 1913 1914 1915 1916
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
		int error = split_vma(mm, last, end, 1);
		if (error)
			return error;
	}
1917
	vma = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
1918

1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932
	/*
	 * unlock any mlock()ed ranges before detaching vmas
	 */
	if (mm->locked_vm) {
		struct vm_area_struct *tmp = vma;
		while (tmp && tmp->vm_start < end) {
			if (tmp->vm_flags & VM_LOCKED) {
				mm->locked_vm -= vma_pages(tmp);
				munlock_vma_pages_all(tmp);
			}
			tmp = tmp->vm_next;
		}
	}

L
Linus Torvalds 已提交
1933 1934 1935
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
1936 1937
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
1938 1939

	/* Fix up all other VM information */
1940
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
1941 1942 1943 1944 1945 1946

	return 0;
}

EXPORT_SYMBOL(do_munmap);

1947
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
L
Linus Torvalds 已提交
1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961
{
	int ret;
	struct mm_struct *mm = current->mm;

	profile_munmap(addr);

	down_write(&mm->mmap_sem);
	ret = do_munmap(mm, addr, len);
	up_write(&mm->mmap_sem);
	return ret;
}

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
1962
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981
	if (unlikely(down_read_trylock(&mm->mmap_sem))) {
		WARN_ON(1);
		up_read(&mm->mmap_sem);
	}
#endif
}

/*
 *  this is really a simplified "do_mmap".  it only handles
 *  anonymous maps.  eventually we may be able to do some
 *  brk-specific accounting here.
 */
unsigned long do_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct * mm = current->mm;
	struct vm_area_struct * vma, * prev;
	unsigned long flags;
	struct rb_node ** rb_link, * rb_parent;
	pgoff_t pgoff = addr >> PAGE_SHIFT;
1982
	int error;
L
Linus Torvalds 已提交
1983 1984 1985 1986 1987

	len = PAGE_ALIGN(len);
	if (!len)
		return addr;

1988
	error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
1989 1990 1991
	if (error)
		return error;

1992 1993
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

A
Al Viro 已提交
1994 1995
	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
	if (error & ~PAGE_MASK)
1996 1997
		return error;

L
Linus Torvalds 已提交
1998 1999 2000 2001 2002
	/*
	 * mlock MCL_FUTURE?
	 */
	if (mm->def_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
2003 2004
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
L
Linus Torvalds 已提交
2005
		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2006
		lock_limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

	/*
	 * mm->mmap_sem is required to protect against another thread
	 * changing the mappings in case we sleep.
	 */
	verify_mm_writelocked(mm);

	/*
	 * Clear old maps.  this also does some error checking for us
	 */
 munmap_back:
	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	if (vma && vma->vm_start < addr + len) {
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

	/* Check against address space limits *after* clearing old maps... */
A
akpm@osdl.org 已提交
2029
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2030 2031 2032 2033 2034 2035 2036 2037 2038
		return -ENOMEM;

	if (mm->map_count > sysctl_max_map_count)
		return -ENOMEM;

	if (security_vm_enough_memory(len >> PAGE_SHIFT))
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2039 2040 2041
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2042 2043 2044 2045 2046
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2047
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2048 2049 2050 2051 2052 2053 2054 2055 2056 2057
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2058
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2059 2060 2061 2062
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
	mm->total_vm += len >> PAGE_SHIFT;
	if (flags & VM_LOCKED) {
2063 2064
		if (!mlock_vma_pages_range(vma, addr, addr + len))
			mm->locked_vm += (len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
2065 2066 2067 2068 2069 2070 2071 2072 2073 2074
	}
	return addr;
}

EXPORT_SYMBOL(do_brk);

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
	struct mmu_gather *tlb;
2075
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2076
	unsigned long nr_accounted = 0;
2077
	unsigned long end;
L
Linus Torvalds 已提交
2078

2079
	/* mm's last user has gone, and its about to be pulled down */
A
Andrea Arcangeli 已提交
2080
	mmu_notifier_release(mm);
2081

2082 2083 2084 2085 2086 2087 2088 2089
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
2090 2091 2092

	arch_exit_mmap(mm);

2093
	vma = mm->mmap;
2094 2095 2096
	if (!vma)	/* Can happen if dup_mmap() received an OOM */
		return;

L
Linus Torvalds 已提交
2097 2098
	lru_add_drain();
	flush_cache_mm(mm);
2099
	tlb = tlb_gather_mmu(mm, 1);
2100
	/* update_hiwater_rss(mm) here? but nobody should be looking */
2101
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2102
	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
L
Linus Torvalds 已提交
2103
	vm_unacct_memory(nr_accounted);
H
Hugh Dickins 已提交
2104

2105
	free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2106
	tlb_finish_mmu(tlb, 0, end);
L
Linus Torvalds 已提交
2107 2108

	/*
2109 2110
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2111
	 */
2112 2113
	while (vma)
		vma = remove_vma(vma);
2114

2115
	BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
 * then i_mmap_lock is taken here.
 */
int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
	struct vm_area_struct * __vma, * prev;
	struct rb_node ** rb_link, * rb_parent;

	/*
	 * The vm_pgoff of a purely anonymous vma should be irrelevant
	 * until its first write fault, when page's anon_vma and index
	 * are set.  But now set the vm_pgoff it will almost certainly
	 * end up with (unless mremap moves it elsewhere before that
	 * first wfault), so /proc/pid/maps tells a consistent story.
	 *
	 * By setting it to reflect the virtual start address of the
	 * vma, merges and splits can happen in a seamless way, just
	 * using the existing file pgoff checks and manipulations.
	 * Similarly in do_mmap_pgoff and in do_brk.
	 */
	if (!vma->vm_file) {
		BUG_ON(vma->anon_vma);
		vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
	}
	__vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
	if (__vma && __vma->vm_start < vma->vm_end)
		return -ENOMEM;
2146
	if ((vma->vm_flags & VM_ACCOUNT) &&
2147
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2148
		return -ENOMEM;
L
Linus Torvalds 已提交
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184
	vma_link(mm, vma, prev, rb_link, rb_parent);
	return 0;
}

/*
 * Copy the vma structure to a new location in the same mm,
 * prior to moving page table entries, to effect an mremap move.
 */
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
	unsigned long addr, unsigned long len, pgoff_t pgoff)
{
	struct vm_area_struct *vma = *vmap;
	unsigned long vma_start = vma->vm_start;
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *new_vma, *prev;
	struct rb_node **rb_link, *rb_parent;
	struct mempolicy *pol;

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
	if (!vma->vm_file && !vma->anon_vma)
		pgoff = addr >> PAGE_SHIFT;

	find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	if (new_vma) {
		/*
		 * Source vma may have been merged into new_vma
		 */
		if (vma_start >= new_vma->vm_start &&
		    vma_start < new_vma->vm_end)
			*vmap = new_vma;
	} else {
2185
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2186 2187
		if (new_vma) {
			*new_vma = *vma;
2188
			pol = mpol_dup(vma_policy(vma));
L
Linus Torvalds 已提交
2189 2190 2191 2192 2193 2194 2195 2196
			if (IS_ERR(pol)) {
				kmem_cache_free(vm_area_cachep, new_vma);
				return NULL;
			}
			vma_set_policy(new_vma, pol);
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
M
Matt Helsley 已提交
2197
			if (new_vma->vm_file) {
L
Linus Torvalds 已提交
2198
				get_file(new_vma->vm_file);
M
Matt Helsley 已提交
2199 2200 2201
				if (vma->vm_flags & VM_EXECUTABLE)
					added_exe_file_vma(mm);
			}
L
Linus Torvalds 已提交
2202 2203 2204 2205 2206 2207 2208
			if (new_vma->vm_ops && new_vma->vm_ops->open)
				new_vma->vm_ops->open(new_vma);
			vma_link(mm, new_vma, prev, rb_link, rb_parent);
		}
	}
	return new_vma;
}
A
akpm@osdl.org 已提交
2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224

/*
 * Return true if the calling process may expand its vm space by the passed
 * number of pages
 */
int may_expand_vm(struct mm_struct *mm, unsigned long npages)
{
	unsigned long cur = mm->total_vm;	/* pages */
	unsigned long lim;

	lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;

	if (cur + npages > lim)
		return 0;
	return 1;
}
2225 2226


N
Nick Piggin 已提交
2227 2228
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2229
{
N
Nick Piggin 已提交
2230
	pgoff_t pgoff;
2231 2232
	struct page **pages;

N
Nick Piggin 已提交
2233 2234 2235 2236 2237 2238 2239
	/*
	 * special mappings have no vm_file, and in that case, the mm
	 * uses vm_pgoff internally. So we have to subtract it from here.
	 * We are allowed to do this because we are the mm; do not copy
	 * this code into drivers!
	 */
	pgoff = vmf->pgoff - vma->vm_pgoff;
2240

N
Nick Piggin 已提交
2241 2242
	for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
		pgoff--;
2243 2244 2245 2246

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
N
Nick Piggin 已提交
2247 2248
		vmf->page = page;
		return 0;
2249 2250
	}

N
Nick Piggin 已提交
2251
	return VM_FAULT_SIGBUS;
2252 2253 2254 2255 2256 2257 2258 2259 2260
}

/*
 * Having a close hook prevents vma merging regardless of flags.
 */
static void special_mapping_close(struct vm_area_struct *vma)
{
}

2261
static const struct vm_operations_struct special_mapping_vmops = {
2262
	.close = special_mapping_close,
N
Nick Piggin 已提交
2263
	.fault = special_mapping_fault,
2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288
};

/*
 * Called with mm->mmap_sem held for writing.
 * Insert a new vma covering the given region, with the given flags.
 * Its pages are supplied by the given array of struct page *.
 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
 * The region past the last page supplied will always produce SIGBUS.
 * The array pointer and the pages it points to are assumed to stay alive
 * for as long as this mapping might exist.
 */
int install_special_mapping(struct mm_struct *mm,
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
	struct vm_area_struct *vma;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (unlikely(vma == NULL))
		return -ENOMEM;

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

2289
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2290
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301

	vma->vm_ops = &special_mapping_vmops;
	vma->vm_private_data = pages;

	if (unlikely(insert_vm_struct(mm, vma))) {
		kmem_cache_free(vm_area_cachep, vma);
		return -ENOMEM;
	}

	mm->total_vm += len >> PAGE_SHIFT;

2302
	perf_event_mmap(vma);
2303

2304 2305
	return 0;
}
2306 2307 2308

static DEFINE_MUTEX(mm_all_locks_mutex);

2309
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2310 2311 2312 2313 2314 2315
{
	if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
2316
		spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331
		/*
		 * We can safely modify head.next after taking the
		 * anon_vma->lock. If some other vma in this mm shares
		 * the same anon_vma we won't take it again.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us thanks to the
		 * anon_vma->lock.
		 */
		if (__test_and_set_bit(0, (unsigned long *)
				       &anon_vma->head.next))
			BUG();
	}
}

2332
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345
{
	if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
		/*
		 * AS_MM_ALL_LOCKS can't change from under us because
		 * we hold the mm_all_locks_mutex.
		 *
		 * Operations on ->flags have to be atomic because
		 * even if AS_MM_ALL_LOCKS is stable thanks to the
		 * mm_all_locks_mutex, there may be other cpus
		 * changing other bitflags in parallel to us.
		 */
		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
			BUG();
2346
		spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394
	}
}

/*
 * This operation locks against the VM for all pte/vma/mm related
 * operations that could ever happen on a certain mm. This includes
 * vmtruncate, try_to_unmap, and all page faults.
 *
 * The caller must take the mmap_sem in write mode before calling
 * mm_take_all_locks(). The caller isn't allowed to release the
 * mmap_sem until mm_drop_all_locks() returns.
 *
 * mmap_sem in write mode is required in order to block all operations
 * that could modify pagetables and free pages without need of
 * altering the vma layout (for example populate_range() with
 * nonlinear vmas). It's also needed in write mode to avoid new
 * anon_vmas to be associated with existing vmas.
 *
 * A single task can't take more than one mm_take_all_locks() in a row
 * or it would deadlock.
 *
 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
 * mapping->flags avoid to take the same lock twice, if more than one
 * vma in this mm is backed by the same anon_vma or address_space.
 *
 * We can take all the locks in random order because the VM code
 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
 * takes more than one of them in a row. Secondly we're protected
 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
 *
 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
 * that may have to take thousand of locks.
 *
 * mm_take_all_locks() can fail if it's interrupted by signals.
 */
int mm_take_all_locks(struct mm_struct *mm)
{
	struct vm_area_struct *vma;
	int ret = -EINTR;

	BUG_ON(down_read_trylock(&mm->mmap_sem));

	mutex_lock(&mm_all_locks_mutex);

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->vm_file && vma->vm_file->f_mapping)
2395
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
2396
	}
2397 2398 2399 2400 2401 2402

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
			vm_lock_anon_vma(mm, vma->anon_vma);
2403
	}
2404

2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469
	ret = 0;

out_unlock:
	if (ret)
		mm_drop_all_locks(mm);

	return ret;
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
	if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
		/*
		 * The LSB of head.next can't change to 0 from under
		 * us because we hold the mm_all_locks_mutex.
		 *
		 * We must however clear the bitflag before unlocking
		 * the vma so the users using the anon_vma->head will
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
		 * anon_vma->lock.
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
					  &anon_vma->head.next))
			BUG();
		spin_unlock(&anon_vma->lock);
	}
}

static void vm_unlock_mapping(struct address_space *mapping)
{
	if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
		/*
		 * AS_MM_ALL_LOCKS can't change to 0 from under us
		 * because we hold the mm_all_locks_mutex.
		 */
		spin_unlock(&mapping->i_mmap_lock);
		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
					&mapping->flags))
			BUG();
	}
}

/*
 * The mmap_sem cannot be released by the caller until
 * mm_drop_all_locks() returns.
 */
void mm_drop_all_locks(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	BUG_ON(down_read_trylock(&mm->mmap_sem));
	BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (vma->anon_vma)
			vm_unlock_anon_vma(vma->anon_vma);
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}
2470 2471 2472 2473 2474 2475

/*
 * initialise the VMA slab
 */
void __init mmap_init(void)
{
2476 2477 2478 2479
	int ret;

	ret = percpu_counter_init(&vm_committed_as, 0);
	VM_BUG_ON(ret);
2480
}