blob: d4855a682ab622863f85352a5353bd45fa1440e4 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@redhat.com>
7 */
8
9#include <linux/slab.h>
Alexey Dobriyan4af3c9c2007-10-16 23:29:23 -070010#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/mm.h>
12#include <linux/shm.h>
13#include <linux/mman.h>
14#include <linux/pagemap.h>
15#include <linux/swap.h>
16#include <linux/syscalls.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080017#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/init.h>
19#include <linux/file.h>
20#include <linux/fs.h>
21#include <linux/personality.h>
22#include <linux/security.h>
23#include <linux/hugetlb.h>
24#include <linux/profile.h>
25#include <linux/module.h>
26#include <linux/mount.h>
27#include <linux/mempolicy.h>
28#include <linux/rmap.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070029#include <linux/mmu_notifier.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31#include <asm/uaccess.h>
32#include <asm/cacheflush.h>
33#include <asm/tlb.h>
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +020034#include <asm/mmu_context.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
Jan Beulich42b77722008-07-23 21:27:10 -070036#include "internal.h"
37
Kirill Korotaev3a459752006-09-07 14:17:04 +040038#ifndef arch_mmap_check
39#define arch_mmap_check(addr, len, flags) (0)
40#endif
41
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -080042#ifndef arch_rebalance_pgtables
43#define arch_rebalance_pgtables(addr, len) (addr)
44#endif
45
Hugh Dickinse0da3822005-04-19 13:29:15 -070046static void unmap_region(struct mm_struct *mm,
47 struct vm_area_struct *vma, struct vm_area_struct *prev,
48 unsigned long start, unsigned long end);
49
Linus Torvalds1da177e2005-04-16 15:20:36 -070050/*
51 * WARNING: the debugging will use recursive algorithms so never enable this
52 * unless you know what you are doing.
53 */
54#undef DEBUG_MM_RB
55
56/* description of effects of mapping type and prot in current implementation.
57 * this is due to the limited x86 page protection hardware. The expected
58 * behavior is in parens:
59 *
60 * map_type prot
61 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
62 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
63 * w: (no) no w: (no) no w: (yes) yes w: (no) no
64 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
65 *
66 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
67 * w: (no) no w: (no) no w: (copy) copy w: (no) no
68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
69 *
70 */
71pgprot_t protection_map[16] = {
72 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
73 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
74};
75
Hugh Dickins804af2c2006-07-26 21:39:49 +010076pgprot_t vm_get_page_prot(unsigned long vm_flags)
77{
Dave Kleikampb845f312008-07-08 00:28:51 +100078 return __pgprot(pgprot_val(protection_map[vm_flags &
79 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
80 pgprot_val(arch_vm_get_page_prot(vm_flags)));
Hugh Dickins804af2c2006-07-26 21:39:49 +010081}
82EXPORT_SYMBOL(vm_get_page_prot);
83
Linus Torvalds1da177e2005-04-16 15:20:36 -070084int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
85int sysctl_overcommit_ratio = 50; /* default is 50% */
Christoph Lameterc3d8c142005-09-06 15:16:33 -070086int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
Alan Cox80119ef2008-05-23 13:04:31 -070087atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89/*
90 * Check that a process has enough memory to allocate a new virtual
91 * mapping. 0 means there is enough memory for the allocation to
92 * succeed and -ENOMEM implies there is not.
93 *
94 * We currently support three overcommit policies, which are set via the
95 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
96 *
97 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
98 * Additional code 2002 Jul 20 by Robert Love.
99 *
100 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
101 *
102 * Note this is a helper function intended to be used by LSMs which
103 * wish to use this logic.
104 */
Alan Cox34b4e4a2007-08-22 14:01:28 -0700105int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106{
107 unsigned long free, allowed;
108
109 vm_acct_memory(pages);
110
111 /*
112 * Sometimes we want to use more memory than we have
113 */
114 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
115 return 0;
116
117 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
118 unsigned long n;
119
Christoph Lameter347ce432006-06-30 01:55:35 -0700120 free = global_page_state(NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 free += nr_swap_pages;
122
123 /*
124 * Any slabs which are created with the
125 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
126 * which are reclaimable, under pressure. The dentry
127 * cache and most inode caches should fall into this
128 */
Christoph Lameter972d1a72006-09-25 23:31:51 -0700129 free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
131 /*
132 * Leave the last 3% for root
133 */
134 if (!cap_sys_admin)
135 free -= free / 32;
136
137 if (free > pages)
138 return 0;
139
140 /*
141 * nr_free_pages() is very expensive on large systems,
142 * only call if we're about to fail.
143 */
144 n = nr_free_pages();
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700145
146 /*
147 * Leave reserved pages. The pages are not for anonymous pages.
148 */
149 if (n <= totalreserve_pages)
150 goto error;
151 else
152 n -= totalreserve_pages;
153
154 /*
155 * Leave the last 3% for root
156 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 if (!cap_sys_admin)
158 n -= n / 32;
159 free += n;
160
161 if (free > pages)
162 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700163
164 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 }
166
167 allowed = (totalram_pages - hugetlb_total_pages())
168 * sysctl_overcommit_ratio / 100;
169 /*
170 * Leave the last 3% for root
171 */
172 if (!cap_sys_admin)
173 allowed -= allowed / 32;
174 allowed += total_swap_pages;
175
176 /* Don't let a single process grow too big:
177 leave 3% of the size of this process for other processes */
Alan Cox731572d2008-10-29 14:01:20 -0700178 if (mm)
179 allowed -= mm->total_vm / 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
Simon Derr2f60f8d2005-08-04 19:52:03 -0700181 /*
182 * cast `allowed' as a signed long because vm_committed_space
183 * sometimes has a negative value
184 */
Alan Cox80119ef2008-05-23 13:04:31 -0700185 if (atomic_long_read(&vm_committed_space) < (long)allowed)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700187error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 vm_unacct_memory(pages);
189
190 return -ENOMEM;
191}
192
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193/*
194 * Requires inode->i_mapping->i_mmap_lock
195 */
196static void __remove_shared_vm_struct(struct vm_area_struct *vma,
197 struct file *file, struct address_space *mapping)
198{
199 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800200 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 if (vma->vm_flags & VM_SHARED)
202 mapping->i_mmap_writable--;
203
204 flush_dcache_mmap_lock(mapping);
205 if (unlikely(vma->vm_flags & VM_NONLINEAR))
206 list_del_init(&vma->shared.vm_set.list);
207 else
208 vma_prio_tree_remove(vma, &mapping->i_mmap);
209 flush_dcache_mmap_unlock(mapping);
210}
211
212/*
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700213 * Unlink a file-based vm structure from its prio_tree, to hide
214 * vma from rmap and vmtruncate before freeing its page tables.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700216void unlink_file_vma(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217{
218 struct file *file = vma->vm_file;
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 if (file) {
221 struct address_space *mapping = file->f_mapping;
222 spin_lock(&mapping->i_mmap_lock);
223 __remove_shared_vm_struct(vma, file, mapping);
224 spin_unlock(&mapping->i_mmap_lock);
225 }
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700226}
227
228/*
229 * Close a vm structure and free it, returning the next.
230 */
231static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
232{
233 struct vm_area_struct *next = vma->vm_next;
234
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700235 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 if (vma->vm_ops && vma->vm_ops->close)
237 vma->vm_ops->close(vma);
Matt Helsley925d1c42008-04-29 01:01:36 -0700238 if (vma->vm_file) {
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700239 fput(vma->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -0700240 if (vma->vm_flags & VM_EXECUTABLE)
241 removed_exe_file_vma(vma->vm_mm);
242 }
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700243 mpol_put(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 kmem_cache_free(vm_area_cachep, vma);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700245 return next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246}
247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248asmlinkage unsigned long sys_brk(unsigned long brk)
249{
250 unsigned long rlim, retval;
251 unsigned long newbrk, oldbrk;
252 struct mm_struct *mm = current->mm;
Jiri Kosinaa5b45922008-06-05 22:46:05 -0700253 unsigned long min_brk;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
255 down_write(&mm->mmap_sem);
256
Jiri Kosinaa5b45922008-06-05 22:46:05 -0700257#ifdef CONFIG_COMPAT_BRK
258 min_brk = mm->end_code;
259#else
260 min_brk = mm->start_brk;
261#endif
262 if (brk < min_brk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 goto out;
Ram Gupta1e624192006-04-10 22:52:57 -0700264
265 /*
266 * Check against rlimit here. If this check is done later after the test
267 * of oldbrk with newbrk then it can escape the test and let the data
268 * segment grow beyond its set limit the in case where the limit is
269 * not page aligned -Ram Gupta
270 */
271 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
Jiri Kosinac1d171a2008-01-30 13:30:40 +0100272 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
273 (mm->end_data - mm->start_data) > rlim)
Ram Gupta1e624192006-04-10 22:52:57 -0700274 goto out;
275
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 newbrk = PAGE_ALIGN(brk);
277 oldbrk = PAGE_ALIGN(mm->brk);
278 if (oldbrk == newbrk)
279 goto set_brk;
280
281 /* Always allow shrinking brk. */
282 if (brk <= mm->brk) {
283 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
284 goto set_brk;
285 goto out;
286 }
287
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 /* Check against existing mmap mappings. */
289 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
290 goto out;
291
292 /* Ok, looks good - let it rip. */
293 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
294 goto out;
295set_brk:
296 mm->brk = brk;
297out:
298 retval = mm->brk;
299 up_write(&mm->mmap_sem);
300 return retval;
301}
302
303#ifdef DEBUG_MM_RB
304static int browse_rb(struct rb_root *root)
305{
306 int i = 0, j;
307 struct rb_node *nd, *pn = NULL;
308 unsigned long prev = 0, pend = 0;
309
310 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
311 struct vm_area_struct *vma;
312 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
313 if (vma->vm_start < prev)
314 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
315 if (vma->vm_start < pend)
316 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
317 if (vma->vm_start > vma->vm_end)
318 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
319 i++;
320 pn = nd;
David Millerd1af65d2007-02-28 20:13:13 -0800321 prev = vma->vm_start;
322 pend = vma->vm_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 }
324 j = 0;
325 for (nd = pn; nd; nd = rb_prev(nd)) {
326 j++;
327 }
328 if (i != j)
329 printk("backwards %d, forwards %d\n", j, i), i = 0;
330 return i;
331}
332
333void validate_mm(struct mm_struct *mm)
334{
335 int bug = 0;
336 int i = 0;
337 struct vm_area_struct *tmp = mm->mmap;
338 while (tmp) {
339 tmp = tmp->vm_next;
340 i++;
341 }
342 if (i != mm->map_count)
343 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
344 i = browse_rb(&mm->mm_rb);
345 if (i != mm->map_count)
346 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200347 BUG_ON(bug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348}
349#else
350#define validate_mm(mm) do { } while (0)
351#endif
352
353static struct vm_area_struct *
354find_vma_prepare(struct mm_struct *mm, unsigned long addr,
355 struct vm_area_struct **pprev, struct rb_node ***rb_link,
356 struct rb_node ** rb_parent)
357{
358 struct vm_area_struct * vma;
359 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
360
361 __rb_link = &mm->mm_rb.rb_node;
362 rb_prev = __rb_parent = NULL;
363 vma = NULL;
364
365 while (*__rb_link) {
366 struct vm_area_struct *vma_tmp;
367
368 __rb_parent = *__rb_link;
369 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
370
371 if (vma_tmp->vm_end > addr) {
372 vma = vma_tmp;
373 if (vma_tmp->vm_start <= addr)
Benny Halevydfe195f2008-08-05 13:01:41 -0700374 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 __rb_link = &__rb_parent->rb_left;
376 } else {
377 rb_prev = __rb_parent;
378 __rb_link = &__rb_parent->rb_right;
379 }
380 }
381
382 *pprev = NULL;
383 if (rb_prev)
384 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
385 *rb_link = __rb_link;
386 *rb_parent = __rb_parent;
387 return vma;
388}
389
390static inline void
391__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
392 struct vm_area_struct *prev, struct rb_node *rb_parent)
393{
394 if (prev) {
395 vma->vm_next = prev->vm_next;
396 prev->vm_next = vma;
397 } else {
398 mm->mmap = vma;
399 if (rb_parent)
400 vma->vm_next = rb_entry(rb_parent,
401 struct vm_area_struct, vm_rb);
402 else
403 vma->vm_next = NULL;
404 }
405}
406
407void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
408 struct rb_node **rb_link, struct rb_node *rb_parent)
409{
410 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
411 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
412}
413
Denys Vlasenkocb8f4882008-10-18 20:27:01 -0700414static void __vma_link_file(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415{
416 struct file * file;
417
418 file = vma->vm_file;
419 if (file) {
420 struct address_space *mapping = file->f_mapping;
421
422 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800423 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 if (vma->vm_flags & VM_SHARED)
425 mapping->i_mmap_writable++;
426
427 flush_dcache_mmap_lock(mapping);
428 if (unlikely(vma->vm_flags & VM_NONLINEAR))
429 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
430 else
431 vma_prio_tree_insert(vma, &mapping->i_mmap);
432 flush_dcache_mmap_unlock(mapping);
433 }
434}
435
436static void
437__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
438 struct vm_area_struct *prev, struct rb_node **rb_link,
439 struct rb_node *rb_parent)
440{
441 __vma_link_list(mm, vma, prev, rb_parent);
442 __vma_link_rb(mm, vma, rb_link, rb_parent);
443 __anon_vma_link(vma);
444}
445
446static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
447 struct vm_area_struct *prev, struct rb_node **rb_link,
448 struct rb_node *rb_parent)
449{
450 struct address_space *mapping = NULL;
451
452 if (vma->vm_file)
453 mapping = vma->vm_file->f_mapping;
454
455 if (mapping) {
456 spin_lock(&mapping->i_mmap_lock);
457 vma->vm_truncate_count = mapping->truncate_count;
458 }
459 anon_vma_lock(vma);
460
461 __vma_link(mm, vma, prev, rb_link, rb_parent);
462 __vma_link_file(vma);
463
464 anon_vma_unlock(vma);
465 if (mapping)
466 spin_unlock(&mapping->i_mmap_lock);
467
468 mm->map_count++;
469 validate_mm(mm);
470}
471
472/*
473 * Helper for vma_adjust in the split_vma insert case:
474 * insert vm structure into list and rbtree and anon_vma,
475 * but it has already been inserted into prio_tree earlier.
476 */
477static void
478__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
479{
480 struct vm_area_struct * __vma, * prev;
481 struct rb_node ** rb_link, * rb_parent;
482
483 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200484 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 __vma_link(mm, vma, prev, rb_link, rb_parent);
486 mm->map_count++;
487}
488
489static inline void
490__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
491 struct vm_area_struct *prev)
492{
493 prev->vm_next = vma->vm_next;
494 rb_erase(&vma->vm_rb, &mm->mm_rb);
495 if (mm->mmap_cache == vma)
496 mm->mmap_cache = prev;
497}
498
499/*
500 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
501 * is already present in an i_mmap tree without adjusting the tree.
502 * The following helper function should be used when such adjustments
503 * are necessary. The "insert" vma (if any) is to be inserted
504 * before we drop the necessary locks.
505 */
506void vma_adjust(struct vm_area_struct *vma, unsigned long start,
507 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
508{
509 struct mm_struct *mm = vma->vm_mm;
510 struct vm_area_struct *next = vma->vm_next;
511 struct vm_area_struct *importer = NULL;
512 struct address_space *mapping = NULL;
513 struct prio_tree_root *root = NULL;
514 struct file *file = vma->vm_file;
515 struct anon_vma *anon_vma = NULL;
516 long adjust_next = 0;
517 int remove_next = 0;
518
519 if (next && !insert) {
520 if (end >= next->vm_end) {
521 /*
522 * vma expands, overlapping all the next, and
523 * perhaps the one after too (mprotect case 6).
524 */
525again: remove_next = 1 + (end > next->vm_end);
526 end = next->vm_end;
527 anon_vma = next->anon_vma;
528 importer = vma;
529 } else if (end > next->vm_start) {
530 /*
531 * vma expands, overlapping part of the next:
532 * mprotect case 5 shifting the boundary up.
533 */
534 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
535 anon_vma = next->anon_vma;
536 importer = vma;
537 } else if (end < vma->vm_end) {
538 /*
539 * vma shrinks, and !insert tells it's not
540 * split_vma inserting another: so it must be
541 * mprotect case 4 shifting the boundary down.
542 */
543 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
544 anon_vma = next->anon_vma;
545 importer = next;
546 }
547 }
548
549 if (file) {
550 mapping = file->f_mapping;
551 if (!(vma->vm_flags & VM_NONLINEAR))
552 root = &mapping->i_mmap;
553 spin_lock(&mapping->i_mmap_lock);
554 if (importer &&
555 vma->vm_truncate_count != next->vm_truncate_count) {
556 /*
557 * unmap_mapping_range might be in progress:
558 * ensure that the expanding vma is rescanned.
559 */
560 importer->vm_truncate_count = 0;
561 }
562 if (insert) {
563 insert->vm_truncate_count = vma->vm_truncate_count;
564 /*
565 * Put into prio_tree now, so instantiated pages
566 * are visible to arm/parisc __flush_dcache_page
567 * throughout; but we cannot insert into address
568 * space until vma start or end is updated.
569 */
570 __vma_link_file(insert);
571 }
572 }
573
574 /*
575 * When changing only vma->vm_end, we don't really need
576 * anon_vma lock: but is that case worth optimizing out?
577 */
578 if (vma->anon_vma)
579 anon_vma = vma->anon_vma;
580 if (anon_vma) {
581 spin_lock(&anon_vma->lock);
582 /*
583 * Easily overlooked: when mprotect shifts the boundary,
584 * make sure the expanding vma has anon_vma set if the
585 * shrinking vma had, to cover any anon pages imported.
586 */
587 if (importer && !importer->anon_vma) {
588 importer->anon_vma = anon_vma;
589 __anon_vma_link(importer);
590 }
591 }
592
593 if (root) {
594 flush_dcache_mmap_lock(mapping);
595 vma_prio_tree_remove(vma, root);
596 if (adjust_next)
597 vma_prio_tree_remove(next, root);
598 }
599
600 vma->vm_start = start;
601 vma->vm_end = end;
602 vma->vm_pgoff = pgoff;
603 if (adjust_next) {
604 next->vm_start += adjust_next << PAGE_SHIFT;
605 next->vm_pgoff += adjust_next;
606 }
607
608 if (root) {
609 if (adjust_next)
610 vma_prio_tree_insert(next, root);
611 vma_prio_tree_insert(vma, root);
612 flush_dcache_mmap_unlock(mapping);
613 }
614
615 if (remove_next) {
616 /*
617 * vma_merge has merged next into vma, and needs
618 * us to remove next before dropping the locks.
619 */
620 __vma_unlink(mm, next, vma);
621 if (file)
622 __remove_shared_vm_struct(next, file, mapping);
623 if (next->anon_vma)
624 __anon_vma_merge(vma, next);
625 } else if (insert) {
626 /*
627 * split_vma has split insert from vma, and needs
628 * us to insert it before dropping the locks
629 * (it may either follow vma or precede it).
630 */
631 __insert_vm_struct(mm, insert);
632 }
633
634 if (anon_vma)
635 spin_unlock(&anon_vma->lock);
636 if (mapping)
637 spin_unlock(&mapping->i_mmap_lock);
638
639 if (remove_next) {
Matt Helsley925d1c42008-04-29 01:01:36 -0700640 if (file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 fput(file);
Matt Helsley925d1c42008-04-29 01:01:36 -0700642 if (next->vm_flags & VM_EXECUTABLE)
643 removed_exe_file_vma(mm);
644 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 mm->map_count--;
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700646 mpol_put(vma_policy(next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 kmem_cache_free(vm_area_cachep, next);
648 /*
649 * In mprotect's case 6 (see comments on vma_merge),
650 * we must remove another next too. It would clutter
651 * up the code too much to do both in one go.
652 */
653 if (remove_next == 2) {
654 next = vma->vm_next;
655 goto again;
656 }
657 }
658
659 validate_mm(mm);
660}
661
662/*
663 * If the vma has a ->close operation then the driver probably needs to release
664 * per-vma resources, so we don't attempt to merge those.
665 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666static inline int is_mergeable_vma(struct vm_area_struct *vma,
667 struct file *file, unsigned long vm_flags)
668{
669 if (vma->vm_flags != vm_flags)
670 return 0;
671 if (vma->vm_file != file)
672 return 0;
673 if (vma->vm_ops && vma->vm_ops->close)
674 return 0;
675 return 1;
676}
677
678static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
679 struct anon_vma *anon_vma2)
680{
681 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
682}
683
684/*
685 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
686 * in front of (at a lower virtual address and file offset than) the vma.
687 *
688 * We cannot merge two vmas if they have differently assigned (non-NULL)
689 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
690 *
691 * We don't check here for the merged mmap wrapping around the end of pagecache
692 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
693 * wrap, nor mmaps which cover the final page at index -1UL.
694 */
695static int
696can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
697 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
698{
699 if (is_mergeable_vma(vma, file, vm_flags) &&
700 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
701 if (vma->vm_pgoff == vm_pgoff)
702 return 1;
703 }
704 return 0;
705}
706
707/*
708 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
709 * beyond (at a higher virtual address and file offset than) the vma.
710 *
711 * We cannot merge two vmas if they have differently assigned (non-NULL)
712 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
713 */
714static int
715can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
716 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
717{
718 if (is_mergeable_vma(vma, file, vm_flags) &&
719 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
720 pgoff_t vm_pglen;
721 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
722 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
723 return 1;
724 }
725 return 0;
726}
727
728/*
729 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
730 * whether that can be merged with its predecessor or its successor.
731 * Or both (it neatly fills a hole).
732 *
733 * In most cases - when called for mmap, brk or mremap - [addr,end) is
734 * certain not to be mapped by the time vma_merge is called; but when
735 * called for mprotect, it is certain to be already mapped (either at
736 * an offset within prev, or at the start of next), and the flags of
737 * this area are about to be changed to vm_flags - and the no-change
738 * case has already been eliminated.
739 *
740 * The following mprotect cases have to be considered, where AAAA is
741 * the area passed down from mprotect_fixup, never extending beyond one
742 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
743 *
744 * AAAA AAAA AAAA AAAA
745 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
746 * cannot merge might become might become might become
747 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
748 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
749 * mremap move: PPPPNNNNNNNN 8
750 * AAAA
751 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
752 * might become case 1 below case 2 below case 3 below
753 *
754 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
755 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
756 */
757struct vm_area_struct *vma_merge(struct mm_struct *mm,
758 struct vm_area_struct *prev, unsigned long addr,
759 unsigned long end, unsigned long vm_flags,
760 struct anon_vma *anon_vma, struct file *file,
761 pgoff_t pgoff, struct mempolicy *policy)
762{
763 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
764 struct vm_area_struct *area, *next;
765
766 /*
767 * We later require that vma->vm_flags == vm_flags,
768 * so this tests vma->vm_flags & VM_SPECIAL, too.
769 */
770 if (vm_flags & VM_SPECIAL)
771 return NULL;
772
773 if (prev)
774 next = prev->vm_next;
775 else
776 next = mm->mmap;
777 area = next;
778 if (next && next->vm_end == end) /* cases 6, 7, 8 */
779 next = next->vm_next;
780
781 /*
782 * Can it merge with the predecessor?
783 */
784 if (prev && prev->vm_end == addr &&
785 mpol_equal(vma_policy(prev), policy) &&
786 can_vma_merge_after(prev, vm_flags,
787 anon_vma, file, pgoff)) {
788 /*
789 * OK, it can. Can we now merge in the successor as well?
790 */
791 if (next && end == next->vm_start &&
792 mpol_equal(policy, vma_policy(next)) &&
793 can_vma_merge_before(next, vm_flags,
794 anon_vma, file, pgoff+pglen) &&
795 is_mergeable_anon_vma(prev->anon_vma,
796 next->anon_vma)) {
797 /* cases 1, 6 */
798 vma_adjust(prev, prev->vm_start,
799 next->vm_end, prev->vm_pgoff, NULL);
800 } else /* cases 2, 5, 7 */
801 vma_adjust(prev, prev->vm_start,
802 end, prev->vm_pgoff, NULL);
803 return prev;
804 }
805
806 /*
807 * Can this new request be merged in front of next?
808 */
809 if (next && end == next->vm_start &&
810 mpol_equal(policy, vma_policy(next)) &&
811 can_vma_merge_before(next, vm_flags,
812 anon_vma, file, pgoff+pglen)) {
813 if (prev && addr < prev->vm_end) /* case 4 */
814 vma_adjust(prev, prev->vm_start,
815 addr, prev->vm_pgoff, NULL);
816 else /* cases 3, 8 */
817 vma_adjust(area, addr, next->vm_end,
818 next->vm_pgoff - pglen, NULL);
819 return area;
820 }
821
822 return NULL;
823}
824
825/*
826 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
827 * neighbouring vmas for a suitable anon_vma, before it goes off
828 * to allocate a new anon_vma. It checks because a repetitive
829 * sequence of mprotects and faults may otherwise lead to distinct
830 * anon_vmas being allocated, preventing vma merge in subsequent
831 * mprotect.
832 */
833struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
834{
835 struct vm_area_struct *near;
836 unsigned long vm_flags;
837
838 near = vma->vm_next;
839 if (!near)
840 goto try_prev;
841
842 /*
843 * Since only mprotect tries to remerge vmas, match flags
844 * which might be mprotected into each other later on.
845 * Neither mlock nor madvise tries to remerge at present,
846 * so leave their flags as obstructing a merge.
847 */
848 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
849 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
850
851 if (near->anon_vma && vma->vm_end == near->vm_start &&
852 mpol_equal(vma_policy(vma), vma_policy(near)) &&
853 can_vma_merge_before(near, vm_flags,
854 NULL, vma->vm_file, vma->vm_pgoff +
855 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
856 return near->anon_vma;
857try_prev:
858 /*
859 * It is potentially slow to have to call find_vma_prev here.
860 * But it's only on the first write fault on the vma, not
861 * every time, and we could devise a way to avoid it later
862 * (e.g. stash info in next's anon_vma_node when assigning
863 * an anon_vma, or when trying vma_merge). Another time.
864 */
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200865 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 if (!near)
867 goto none;
868
869 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
870 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
871
872 if (near->anon_vma && near->vm_end == vma->vm_start &&
873 mpol_equal(vma_policy(near), vma_policy(vma)) &&
874 can_vma_merge_after(near, vm_flags,
875 NULL, vma->vm_file, vma->vm_pgoff))
876 return near->anon_vma;
877none:
878 /*
879 * There's no absolute need to look only at touching neighbours:
880 * we could search further afield for "compatible" anon_vmas.
881 * But it would probably just be a waste of time searching,
882 * or lead to too many vmas hanging off the same anon_vma.
883 * We're trying to allow mprotect remerging later on,
884 * not trying to minimize memory used for anon_vmas.
885 */
886 return NULL;
887}
888
889#ifdef CONFIG_PROC_FS
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700890void vm_stat_account(struct mm_struct *mm, unsigned long flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 struct file *file, long pages)
892{
893 const unsigned long stack_flags
894 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
895
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 if (file) {
897 mm->shared_vm += pages;
898 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
899 mm->exec_vm += pages;
900 } else if (flags & stack_flags)
901 mm->stack_vm += pages;
902 if (flags & (VM_RESERVED|VM_IO))
903 mm->reserved_vm += pages;
904}
905#endif /* CONFIG_PROC_FS */
906
907/*
908 * The caller must hold down_write(current->mm->mmap_sem).
909 */
910
911unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
912 unsigned long len, unsigned long prot,
913 unsigned long flags, unsigned long pgoff)
914{
915 struct mm_struct * mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 struct inode *inode;
917 unsigned int vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 int accountable = 1;
Miklos Szeredi0165ab42007-07-15 23:38:26 -0700920 unsigned long reqprot = prot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 /*
923 * Does the application expect PROT_READ to imply PROT_EXEC?
924 *
925 * (the exception is when the underlying filesystem is noexec
926 * mounted, in which case we dont add PROT_EXEC.)
927 */
928 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800929 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 prot |= PROT_EXEC;
931
932 if (!len)
933 return -EINVAL;
934
Eric Paris7cd94142007-11-26 18:47:40 -0500935 if (!(flags & MAP_FIXED))
936 addr = round_hint_to_min(addr);
937
Kirill Korotaev3a459752006-09-07 14:17:04 +0400938 error = arch_mmap_check(addr, len, flags);
939 if (error)
940 return error;
941
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 /* Careful about overflows.. */
943 len = PAGE_ALIGN(len);
944 if (!len || len > TASK_SIZE)
945 return -ENOMEM;
946
947 /* offset overflow? */
948 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
949 return -EOVERFLOW;
950
951 /* Too many mappings? */
952 if (mm->map_count > sysctl_max_map_count)
953 return -ENOMEM;
954
955 /* Obtain the address to map to. we verify (or select) it and ensure
956 * that it represents a valid section of the address space.
957 */
958 addr = get_unmapped_area(file, addr, len, pgoff, flags);
959 if (addr & ~PAGE_MASK)
960 return addr;
961
962 /* Do simple checking here so the lower-level routines won't have
963 * to. we assume access permissions have been handled by the open
964 * of the memory object, so we don't do any here.
965 */
966 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
967 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
968
969 if (flags & MAP_LOCKED) {
970 if (!can_do_mlock())
971 return -EPERM;
972 vm_flags |= VM_LOCKED;
973 }
Rik van Rielba470de2008-10-18 20:26:50 -0700974
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 /* mlock MCL_FUTURE? */
976 if (vm_flags & VM_LOCKED) {
977 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -0700978 locked = len >> PAGE_SHIFT;
979 locked += mm->locked_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
Chris Wright93ea1d02005-05-01 08:58:38 -0700981 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
983 return -EAGAIN;
984 }
985
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800986 inode = file ? file->f_path.dentry->d_inode : NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987
988 if (file) {
989 switch (flags & MAP_TYPE) {
990 case MAP_SHARED:
991 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
992 return -EACCES;
993
994 /*
995 * Make sure we don't allow writing to an append-only
996 * file..
997 */
998 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
999 return -EACCES;
1000
1001 /*
1002 * Make sure there are no mandatory locks on the file.
1003 */
1004 if (locks_verify_locked(inode))
1005 return -EAGAIN;
1006
1007 vm_flags |= VM_SHARED | VM_MAYSHARE;
1008 if (!(file->f_mode & FMODE_WRITE))
1009 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1010
1011 /* fall through */
1012 case MAP_PRIVATE:
1013 if (!(file->f_mode & FMODE_READ))
1014 return -EACCES;
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001015 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds80c56062006-10-15 14:09:55 -07001016 if (vm_flags & VM_EXEC)
1017 return -EPERM;
1018 vm_flags &= ~VM_MAYEXEC;
1019 }
1020 if (is_file_hugepages(file))
1021 accountable = 0;
1022
1023 if (!file->f_op || !file->f_op->mmap)
1024 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 break;
1026
1027 default:
1028 return -EINVAL;
1029 }
1030 } else {
1031 switch (flags & MAP_TYPE) {
1032 case MAP_SHARED:
Tejun Heoce363942008-09-03 16:09:47 +02001033 /*
1034 * Ignore pgoff.
1035 */
1036 pgoff = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 vm_flags |= VM_SHARED | VM_MAYSHARE;
1038 break;
1039 case MAP_PRIVATE:
1040 /*
1041 * Set pgoff according to addr for anon_vma.
1042 */
1043 pgoff = addr >> PAGE_SHIFT;
1044 break;
1045 default:
1046 return -EINVAL;
1047 }
1048 }
1049
Eric Parised032182007-06-28 15:55:21 -04001050 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 if (error)
1052 return error;
Eric Parised032182007-06-28 15:55:21 -04001053
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001054 return mmap_region(file, addr, len, flags, vm_flags, pgoff,
1055 accountable);
1056}
1057EXPORT_SYMBOL(do_mmap_pgoff);
1058
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001059/*
1060 * Some shared mappigns will want the pages marked read-only
1061 * to track write events. If so, we'll downgrade vm_page_prot
1062 * to the private version (using protection_map[] without the
1063 * VM_SHARED bit).
1064 */
1065int vma_wants_writenotify(struct vm_area_struct *vma)
1066{
1067 unsigned int vm_flags = vma->vm_flags;
1068
1069 /* If it was private or non-writable, the write bit is already clear */
1070 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1071 return 0;
1072
1073 /* The backer wishes to know when pages are first written to? */
1074 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1075 return 1;
1076
1077 /* The open routine did something to the protections already? */
1078 if (pgprot_val(vma->vm_page_prot) !=
Coly Li3ed75eb2007-10-18 23:39:15 -07001079 pgprot_val(vm_get_page_prot(vm_flags)))
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001080 return 0;
1081
1082 /* Specialty mapping? */
1083 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1084 return 0;
1085
1086 /* Can the mapping track the dirty pages? */
1087 return vma->vm_file && vma->vm_file->f_mapping &&
1088 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1089}
1090
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001091unsigned long mmap_region(struct file *file, unsigned long addr,
1092 unsigned long len, unsigned long flags,
1093 unsigned int vm_flags, unsigned long pgoff,
1094 int accountable)
1095{
1096 struct mm_struct *mm = current->mm;
1097 struct vm_area_struct *vma, *prev;
1098 int correct_wcount = 0;
1099 int error;
1100 struct rb_node **rb_link, *rb_parent;
1101 unsigned long charged = 0;
1102 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1103
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 /* Clear old maps */
1105 error = -ENOMEM;
1106munmap_back:
1107 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1108 if (vma && vma->vm_start < addr + len) {
1109 if (do_munmap(mm, addr, len))
1110 return -ENOMEM;
1111 goto munmap_back;
1112 }
1113
1114 /* Check against address space limit. */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001115 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 return -ENOMEM;
1117
Andy Whitcroftcdfd4322008-07-23 21:27:28 -07001118 if (flags & MAP_NORESERVE)
1119 vm_flags |= VM_NORESERVE;
1120
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 if (accountable && (!(flags & MAP_NORESERVE) ||
1122 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1123 if (vm_flags & VM_SHARED) {
1124 /* Check memory availability in shmem_file_setup? */
1125 vm_flags |= VM_ACCOUNT;
1126 } else if (vm_flags & VM_WRITE) {
1127 /*
1128 * Private writable mapping: check memory availability
1129 */
1130 charged = len >> PAGE_SHIFT;
1131 if (security_vm_enough_memory(charged))
1132 return -ENOMEM;
1133 vm_flags |= VM_ACCOUNT;
1134 }
1135 }
1136
1137 /*
1138 * Can we just expand an old private anonymous mapping?
1139 * The VM_SHARED test is necessary because shmem_zero_setup
1140 * will create the file object for a shared anonymous map below.
1141 */
Rik van Rielba470de2008-10-18 20:26:50 -07001142 if (!file && !(vm_flags & VM_SHARED)) {
1143 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1144 NULL, NULL, pgoff, NULL);
1145 if (vma)
1146 goto out;
1147 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148
1149 /*
1150 * Determine the object being mapped and call the appropriate
1151 * specific mapper. the address has already been validated, but
1152 * not unmapped, but the maps are removed from the list.
1153 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08001154 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155 if (!vma) {
1156 error = -ENOMEM;
1157 goto unacct_error;
1158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159
1160 vma->vm_mm = mm;
1161 vma->vm_start = addr;
1162 vma->vm_end = addr + len;
1163 vma->vm_flags = vm_flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07001164 vma->vm_page_prot = vm_get_page_prot(vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 vma->vm_pgoff = pgoff;
1166
1167 if (file) {
1168 error = -EINVAL;
1169 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1170 goto free_vma;
1171 if (vm_flags & VM_DENYWRITE) {
1172 error = deny_write_access(file);
1173 if (error)
1174 goto free_vma;
1175 correct_wcount = 1;
1176 }
1177 vma->vm_file = file;
1178 get_file(file);
1179 error = file->f_op->mmap(file, vma);
1180 if (error)
1181 goto unmap_and_free_vma;
Matt Helsley925d1c42008-04-29 01:01:36 -07001182 if (vm_flags & VM_EXECUTABLE)
1183 added_exe_file_vma(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 } else if (vm_flags & VM_SHARED) {
1185 error = shmem_zero_setup(vma);
1186 if (error)
1187 goto free_vma;
1188 }
1189
1190 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1191 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1192 * that memory reservation must be checked; but that reservation
1193 * belongs to shared memory object, not to vma: so now clear it.
1194 */
1195 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1196 vma->vm_flags &= ~VM_ACCOUNT;
1197
1198 /* Can addr have changed??
1199 *
1200 * Answer: Yes, several device drivers can do it in their
1201 * f_op->mmap method. -DaveM
1202 */
1203 addr = vma->vm_start;
1204 pgoff = vma->vm_pgoff;
1205 vm_flags = vma->vm_flags;
1206
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001207 if (vma_wants_writenotify(vma))
Hugh Dickins1ddd4392007-10-22 20:45:12 -07001208 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001209
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001210 if (file && vma_merge(mm, prev, addr, vma->vm_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
Lee Schermerhornf0be3d32008-04-28 02:13:08 -07001212 mpol_put(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213 kmem_cache_free(vm_area_cachep, vma);
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001214 fput(file);
Matt Helsley925d1c42008-04-29 01:01:36 -07001215 if (vm_flags & VM_EXECUTABLE)
1216 removed_exe_file_vma(mm);
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001217 } else {
1218 vma_link(mm, vma, prev, rb_link, rb_parent);
1219 file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 }
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001221
1222 /* Once vma denies write, undo our temporary denial count */
1223 if (correct_wcount)
1224 atomic_inc(&inode->i_writecount);
1225out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 mm->total_vm += len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001227 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 if (vm_flags & VM_LOCKED) {
Rik van Rielba470de2008-10-18 20:26:50 -07001229 /*
1230 * makes pages present; downgrades, drops, reacquires mmap_sem
1231 */
1232 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
1233 if (nr_pages < 0)
1234 return nr_pages; /* vma gone! */
1235 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
1236 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
Nick Piggin54cb8822007-07-19 01:46:59 -07001237 make_pages_present(addr, addr + len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 return addr;
1239
1240unmap_and_free_vma:
1241 if (correct_wcount)
1242 atomic_inc(&inode->i_writecount);
1243 vma->vm_file = NULL;
1244 fput(file);
1245
1246 /* Undo any partial mapping done by a device driver. */
Hugh Dickinse0da3822005-04-19 13:29:15 -07001247 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1248 charged = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249free_vma:
1250 kmem_cache_free(vm_area_cachep, vma);
1251unacct_error:
1252 if (charged)
1253 vm_unacct_memory(charged);
1254 return error;
1255}
1256
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257/* Get an address range which is currently unmapped.
1258 * For shmat() with addr=0.
1259 *
1260 * Ugly calling convention alert:
1261 * Return value with the low bits set means error value,
1262 * ie
1263 * if (ret & ~PAGE_MASK)
1264 * error = ret;
1265 *
1266 * This function "knows" that -ENOMEM has the bits set.
1267 */
1268#ifndef HAVE_ARCH_UNMAPPED_AREA
1269unsigned long
1270arch_get_unmapped_area(struct file *filp, unsigned long addr,
1271 unsigned long len, unsigned long pgoff, unsigned long flags)
1272{
1273 struct mm_struct *mm = current->mm;
1274 struct vm_area_struct *vma;
1275 unsigned long start_addr;
1276
1277 if (len > TASK_SIZE)
1278 return -ENOMEM;
1279
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001280 if (flags & MAP_FIXED)
1281 return addr;
1282
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 if (addr) {
1284 addr = PAGE_ALIGN(addr);
1285 vma = find_vma(mm, addr);
1286 if (TASK_SIZE - len >= addr &&
1287 (!vma || addr + len <= vma->vm_start))
1288 return addr;
1289 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001290 if (len > mm->cached_hole_size) {
1291 start_addr = addr = mm->free_area_cache;
1292 } else {
1293 start_addr = addr = TASK_UNMAPPED_BASE;
1294 mm->cached_hole_size = 0;
1295 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296
1297full_search:
1298 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1299 /* At this point: (!vma || addr < vma->vm_end). */
1300 if (TASK_SIZE - len < addr) {
1301 /*
1302 * Start a new search - just in case we missed
1303 * some holes.
1304 */
1305 if (start_addr != TASK_UNMAPPED_BASE) {
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001306 addr = TASK_UNMAPPED_BASE;
1307 start_addr = addr;
1308 mm->cached_hole_size = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 goto full_search;
1310 }
1311 return -ENOMEM;
1312 }
1313 if (!vma || addr + len <= vma->vm_start) {
1314 /*
1315 * Remember the place where we stopped the search:
1316 */
1317 mm->free_area_cache = addr + len;
1318 return addr;
1319 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001320 if (addr + mm->cached_hole_size < vma->vm_start)
1321 mm->cached_hole_size = vma->vm_start - addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 addr = vma->vm_end;
1323 }
1324}
1325#endif
1326
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001327void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328{
1329 /*
1330 * Is this a new hole at the lowest possible address?
1331 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001332 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1333 mm->free_area_cache = addr;
1334 mm->cached_hole_size = ~0UL;
1335 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336}
1337
1338/*
1339 * This mmap-allocator allocates new areas top-down from below the
1340 * stack's low limit (the base):
1341 */
1342#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1343unsigned long
1344arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1345 const unsigned long len, const unsigned long pgoff,
1346 const unsigned long flags)
1347{
1348 struct vm_area_struct *vma;
1349 struct mm_struct *mm = current->mm;
1350 unsigned long addr = addr0;
1351
1352 /* requested length too big for entire address space */
1353 if (len > TASK_SIZE)
1354 return -ENOMEM;
1355
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001356 if (flags & MAP_FIXED)
1357 return addr;
1358
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 /* requesting a specific address */
1360 if (addr) {
1361 addr = PAGE_ALIGN(addr);
1362 vma = find_vma(mm, addr);
1363 if (TASK_SIZE - len >= addr &&
1364 (!vma || addr + len <= vma->vm_start))
1365 return addr;
1366 }
1367
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001368 /* check if free_area_cache is useful for us */
1369 if (len <= mm->cached_hole_size) {
1370 mm->cached_hole_size = 0;
1371 mm->free_area_cache = mm->mmap_base;
1372 }
1373
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 /* either no address requested or can't fit in requested address hole */
1375 addr = mm->free_area_cache;
1376
1377 /* make sure it can fit in the remaining address space */
Linus Torvalds49a43872005-05-18 15:39:33 -07001378 if (addr > len) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 vma = find_vma(mm, addr-len);
1380 if (!vma || addr <= vma->vm_start)
1381 /* remember the address as a hint for next time */
1382 return (mm->free_area_cache = addr-len);
1383 }
1384
Chris Wright73219d12005-06-21 17:14:52 -07001385 if (mm->mmap_base < len)
1386 goto bottomup;
1387
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 addr = mm->mmap_base-len;
1389
1390 do {
1391 /*
1392 * Lookup failure means no vma is above this address,
1393 * else if new region fits below vma->vm_start,
1394 * return with success:
1395 */
1396 vma = find_vma(mm, addr);
1397 if (!vma || addr+len <= vma->vm_start)
1398 /* remember the address as a hint for next time */
1399 return (mm->free_area_cache = addr);
1400
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001401 /* remember the largest hole we saw so far */
1402 if (addr + mm->cached_hole_size < vma->vm_start)
1403 mm->cached_hole_size = vma->vm_start - addr;
1404
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 /* try just below the current vma->vm_start */
1406 addr = vma->vm_start-len;
Linus Torvalds49a43872005-05-18 15:39:33 -07001407 } while (len < vma->vm_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408
Chris Wright73219d12005-06-21 17:14:52 -07001409bottomup:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 /*
1411 * A failed mmap() very likely causes application failure,
1412 * so fall back to the bottom-up function here. This scenario
1413 * can happen with large stack limits and large mmap()
1414 * allocations.
1415 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001416 mm->cached_hole_size = ~0UL;
1417 mm->free_area_cache = TASK_UNMAPPED_BASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1419 /*
1420 * Restore the topdown base:
1421 */
1422 mm->free_area_cache = mm->mmap_base;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001423 mm->cached_hole_size = ~0UL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424
1425 return addr;
1426}
1427#endif
1428
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001429void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430{
1431 /*
1432 * Is this a new hole at the highest possible address?
1433 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001434 if (addr > mm->free_area_cache)
1435 mm->free_area_cache = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436
1437 /* dont allow allocations above current base */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001438 if (mm->free_area_cache > mm->mmap_base)
1439 mm->free_area_cache = mm->mmap_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440}
1441
1442unsigned long
1443get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1444 unsigned long pgoff, unsigned long flags)
1445{
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001446 unsigned long (*get_area)(struct file *, unsigned long,
1447 unsigned long, unsigned long, unsigned long);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001449 get_area = current->mm->get_unmapped_area;
1450 if (file && file->f_op && file->f_op->get_unmapped_area)
1451 get_area = file->f_op->get_unmapped_area;
1452 addr = get_area(file, addr, len, pgoff, flags);
1453 if (IS_ERR_VALUE(addr))
1454 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455
Linus Torvalds07ab67c2005-05-19 22:43:37 -07001456 if (addr > TASK_SIZE - len)
1457 return -ENOMEM;
1458 if (addr & ~PAGE_MASK)
1459 return -EINVAL;
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001460
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -08001461 return arch_rebalance_pgtables(addr, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462}
1463
1464EXPORT_SYMBOL(get_unmapped_area);
1465
1466/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1467struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1468{
1469 struct vm_area_struct *vma = NULL;
1470
1471 if (mm) {
1472 /* Check the cache first. */
1473 /* (Cache hit rate is typically around 35%.) */
1474 vma = mm->mmap_cache;
1475 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1476 struct rb_node * rb_node;
1477
1478 rb_node = mm->mm_rb.rb_node;
1479 vma = NULL;
1480
1481 while (rb_node) {
1482 struct vm_area_struct * vma_tmp;
1483
1484 vma_tmp = rb_entry(rb_node,
1485 struct vm_area_struct, vm_rb);
1486
1487 if (vma_tmp->vm_end > addr) {
1488 vma = vma_tmp;
1489 if (vma_tmp->vm_start <= addr)
1490 break;
1491 rb_node = rb_node->rb_left;
1492 } else
1493 rb_node = rb_node->rb_right;
1494 }
1495 if (vma)
1496 mm->mmap_cache = vma;
1497 }
1498 }
1499 return vma;
1500}
1501
1502EXPORT_SYMBOL(find_vma);
1503
1504/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1505struct vm_area_struct *
1506find_vma_prev(struct mm_struct *mm, unsigned long addr,
1507 struct vm_area_struct **pprev)
1508{
1509 struct vm_area_struct *vma = NULL, *prev = NULL;
1510 struct rb_node * rb_node;
1511 if (!mm)
1512 goto out;
1513
1514 /* Guard against addr being lower than the first VMA */
1515 vma = mm->mmap;
1516
1517 /* Go through the RB tree quickly. */
1518 rb_node = mm->mm_rb.rb_node;
1519
1520 while (rb_node) {
1521 struct vm_area_struct *vma_tmp;
1522 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1523
1524 if (addr < vma_tmp->vm_end) {
1525 rb_node = rb_node->rb_left;
1526 } else {
1527 prev = vma_tmp;
1528 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1529 break;
1530 rb_node = rb_node->rb_right;
1531 }
1532 }
1533
1534out:
1535 *pprev = prev;
1536 return prev ? prev->vm_next : vma;
1537}
1538
1539/*
1540 * Verify that the stack growth is acceptable and
1541 * update accounting. This is shared with both the
1542 * grow-up and grow-down cases.
1543 */
1544static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1545{
1546 struct mm_struct *mm = vma->vm_mm;
1547 struct rlimit *rlim = current->signal->rlim;
Adam Litke0d59a012007-01-30 14:35:39 -08001548 unsigned long new_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549
1550 /* address space limit tests */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001551 if (!may_expand_vm(mm, grow))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 return -ENOMEM;
1553
1554 /* Stack limit test */
1555 if (size > rlim[RLIMIT_STACK].rlim_cur)
1556 return -ENOMEM;
1557
1558 /* mlock limit tests */
1559 if (vma->vm_flags & VM_LOCKED) {
1560 unsigned long locked;
1561 unsigned long limit;
1562 locked = mm->locked_vm + grow;
1563 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1564 if (locked > limit && !capable(CAP_IPC_LOCK))
1565 return -ENOMEM;
1566 }
1567
Adam Litke0d59a012007-01-30 14:35:39 -08001568 /* Check to ensure the stack will not grow into a hugetlb-only region */
1569 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1570 vma->vm_end - size;
1571 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1572 return -EFAULT;
1573
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 /*
1575 * Overcommit.. This must be the final test, as it will
1576 * update security statistics.
1577 */
1578 if (security_vm_enough_memory(grow))
1579 return -ENOMEM;
1580
1581 /* Ok, everything looks good - let it rip */
1582 mm->total_vm += grow;
1583 if (vma->vm_flags & VM_LOCKED)
1584 mm->locked_vm += grow;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001585 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 return 0;
1587}
1588
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001589#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590/*
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001591 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1592 * vma is the last one with address > vma->vm_end. Have to extend vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 */
Matthew Wilcox9ab88512005-11-18 16:16:42 -05001594#ifndef CONFIG_IA64
Denys Vlasenkocb8f4882008-10-18 20:27:01 -07001595static
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001596#endif
1597int expand_upwards(struct vm_area_struct *vma, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598{
1599 int error;
1600
1601 if (!(vma->vm_flags & VM_GROWSUP))
1602 return -EFAULT;
1603
1604 /*
1605 * We must make sure the anon_vma is allocated
1606 * so that the anon_vma locking is not a noop.
1607 */
1608 if (unlikely(anon_vma_prepare(vma)))
1609 return -ENOMEM;
1610 anon_vma_lock(vma);
1611
1612 /*
1613 * vma->vm_start/vm_end cannot change under us because the caller
1614 * is required to hold the mmap_sem in read mode. We need the
1615 * anon_vma lock to serialize against concurrent expand_stacks.
Helge Deller06b32f32006-12-19 19:28:33 +01001616 * Also guard against wrapping around to address 0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 */
Helge Deller06b32f32006-12-19 19:28:33 +01001618 if (address < PAGE_ALIGN(address+4))
1619 address = PAGE_ALIGN(address+4);
1620 else {
1621 anon_vma_unlock(vma);
1622 return -ENOMEM;
1623 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 error = 0;
1625
1626 /* Somebody else might have raced and expanded it already */
1627 if (address > vma->vm_end) {
1628 unsigned long size, grow;
1629
1630 size = address - vma->vm_start;
1631 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1632
1633 error = acct_stack_growth(vma, size, grow);
1634 if (!error)
1635 vma->vm_end = address;
1636 }
1637 anon_vma_unlock(vma);
1638 return error;
1639}
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001640#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1641
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642/*
1643 * vma is the first one with address < vma->vm_start. Have to extend vma.
1644 */
Denys Vlasenkocb8f4882008-10-18 20:27:01 -07001645static int expand_downwards(struct vm_area_struct *vma,
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001646 unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647{
1648 int error;
1649
1650 /*
1651 * We must make sure the anon_vma is allocated
1652 * so that the anon_vma locking is not a noop.
1653 */
1654 if (unlikely(anon_vma_prepare(vma)))
1655 return -ENOMEM;
Eric Paris88694772007-11-26 18:47:26 -05001656
1657 address &= PAGE_MASK;
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01001658 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
Eric Paris88694772007-11-26 18:47:26 -05001659 if (error)
1660 return error;
1661
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 anon_vma_lock(vma);
1663
1664 /*
1665 * vma->vm_start/vm_end cannot change under us because the caller
1666 * is required to hold the mmap_sem in read mode. We need the
1667 * anon_vma lock to serialize against concurrent expand_stacks.
1668 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669
1670 /* Somebody else might have raced and expanded it already */
1671 if (address < vma->vm_start) {
1672 unsigned long size, grow;
1673
1674 size = vma->vm_end - address;
1675 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1676
1677 error = acct_stack_growth(vma, size, grow);
1678 if (!error) {
1679 vma->vm_start = address;
1680 vma->vm_pgoff -= grow;
1681 }
1682 }
1683 anon_vma_unlock(vma);
1684 return error;
1685}
1686
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001687int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1688{
1689 return expand_downwards(vma, address);
1690}
1691
1692#ifdef CONFIG_STACK_GROWSUP
1693int expand_stack(struct vm_area_struct *vma, unsigned long address)
1694{
1695 return expand_upwards(vma, address);
1696}
1697
1698struct vm_area_struct *
1699find_extend_vma(struct mm_struct *mm, unsigned long addr)
1700{
1701 struct vm_area_struct *vma, *prev;
1702
1703 addr &= PAGE_MASK;
1704 vma = find_vma_prev(mm, addr, &prev);
1705 if (vma && (vma->vm_start <= addr))
1706 return vma;
Denys Vlasenko1c127182008-11-12 01:24:41 +01001707 if (!prev || expand_stack(prev, addr))
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001708 return NULL;
Rik van Rielba470de2008-10-18 20:26:50 -07001709 if (prev->vm_flags & VM_LOCKED) {
1710 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
1711 return NULL; /* vma gone! */
1712 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001713 return prev;
1714}
1715#else
1716int expand_stack(struct vm_area_struct *vma, unsigned long address)
1717{
1718 return expand_downwards(vma, address);
1719}
1720
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721struct vm_area_struct *
1722find_extend_vma(struct mm_struct * mm, unsigned long addr)
1723{
1724 struct vm_area_struct * vma;
1725 unsigned long start;
1726
1727 addr &= PAGE_MASK;
1728 vma = find_vma(mm,addr);
1729 if (!vma)
1730 return NULL;
1731 if (vma->vm_start <= addr)
1732 return vma;
1733 if (!(vma->vm_flags & VM_GROWSDOWN))
1734 return NULL;
1735 start = vma->vm_start;
1736 if (expand_stack(vma, addr))
1737 return NULL;
Rik van Rielba470de2008-10-18 20:26:50 -07001738 if (vma->vm_flags & VM_LOCKED) {
1739 if (mlock_vma_pages_range(vma, addr, start) < 0)
1740 return NULL; /* vma gone! */
1741 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 return vma;
1743}
1744#endif
1745
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746/*
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001747 * Ok - we have the memory areas we should free on the vma list,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 * so release them, and do the vma updates.
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001749 *
1750 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001752static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753{
Hugh Dickins365e9c872005-10-29 18:16:18 -07001754 /* Update high watermark before we lower total_vm */
1755 update_hiwater_vm(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756 do {
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001757 long nrpages = vma_pages(vma);
1758
1759 mm->total_vm -= nrpages;
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001760 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07001761 vma = remove_vma(vma);
Hugh Dickins146425a2005-04-19 13:29:18 -07001762 } while (vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 validate_mm(mm);
1764}
1765
1766/*
1767 * Get rid of page table information in the indicated region.
1768 *
Paolo 'Blaisorblade' Giarrussof10df682005-09-21 09:55:37 -07001769 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 */
1771static void unmap_region(struct mm_struct *mm,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001772 struct vm_area_struct *vma, struct vm_area_struct *prev,
1773 unsigned long start, unsigned long end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774{
Hugh Dickinse0da3822005-04-19 13:29:15 -07001775 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 struct mmu_gather *tlb;
1777 unsigned long nr_accounted = 0;
1778
1779 lru_add_drain();
1780 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickins365e9c872005-10-29 18:16:18 -07001781 update_hiwater_rss(mm);
Hugh Dickins508034a2005-10-29 18:16:30 -07001782 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 vm_unacct_memory(nr_accounted);
Jan Beulich42b77722008-07-23 21:27:10 -07001784 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001785 next? next->vm_start: 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 tlb_finish_mmu(tlb, start, end);
1787}
1788
1789/*
1790 * Create a list of vma's touched by the unmap, removing them from the mm's
1791 * vma list as we go..
1792 */
1793static void
1794detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1795 struct vm_area_struct *prev, unsigned long end)
1796{
1797 struct vm_area_struct **insertion_point;
1798 struct vm_area_struct *tail_vma = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001799 unsigned long addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800
1801 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1802 do {
1803 rb_erase(&vma->vm_rb, &mm->mm_rb);
1804 mm->map_count--;
1805 tail_vma = vma;
1806 vma = vma->vm_next;
1807 } while (vma && vma->vm_start < end);
1808 *insertion_point = vma;
1809 tail_vma->vm_next = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001810 if (mm->unmap_area == arch_unmap_area)
1811 addr = prev ? prev->vm_end : mm->mmap_base;
1812 else
1813 addr = vma ? vma->vm_start : mm->mmap_base;
1814 mm->unmap_area(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 mm->mmap_cache = NULL; /* Kill the cache. */
1816}
1817
1818/*
1819 * Split a vma into two pieces at address 'addr', a new vma is allocated
Michael Opdenacker59c51592007-05-09 08:57:56 +02001820 * either for the first part or the tail.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 */
1822int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1823 unsigned long addr, int new_below)
1824{
1825 struct mempolicy *pol;
1826 struct vm_area_struct *new;
1827
Andi Kleena5516432008-07-23 21:27:41 -07001828 if (is_vm_hugetlb_page(vma) && (addr &
1829 ~(huge_page_mask(hstate_vma(vma)))))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 return -EINVAL;
1831
1832 if (mm->map_count >= sysctl_max_map_count)
1833 return -ENOMEM;
1834
Christoph Lametere94b1762006-12-06 20:33:17 -08001835 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 if (!new)
1837 return -ENOMEM;
1838
1839 /* most fields are the same, copy all, and then fixup */
1840 *new = *vma;
1841
1842 if (new_below)
1843 new->vm_end = addr;
1844 else {
1845 new->vm_start = addr;
1846 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1847 }
1848
Lee Schermerhorn846a16b2008-04-28 02:13:09 -07001849 pol = mpol_dup(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850 if (IS_ERR(pol)) {
1851 kmem_cache_free(vm_area_cachep, new);
1852 return PTR_ERR(pol);
1853 }
1854 vma_set_policy(new, pol);
1855
Matt Helsley925d1c42008-04-29 01:01:36 -07001856 if (new->vm_file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 get_file(new->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -07001858 if (vma->vm_flags & VM_EXECUTABLE)
1859 added_exe_file_vma(mm);
1860 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861
1862 if (new->vm_ops && new->vm_ops->open)
1863 new->vm_ops->open(new);
1864
1865 if (new_below)
1866 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1867 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1868 else
1869 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1870
1871 return 0;
1872}
1873
1874/* Munmap is split into 2 main parts -- this part which finds
1875 * what needs doing, and the areas themselves, which do the
1876 * work. This now handles partial unmappings.
1877 * Jeremy Fitzhardinge <jeremy@goop.org>
1878 */
1879int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1880{
1881 unsigned long end;
Hugh Dickins146425a2005-04-19 13:29:18 -07001882 struct vm_area_struct *vma, *prev, *last;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883
1884 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1885 return -EINVAL;
1886
1887 if ((len = PAGE_ALIGN(len)) == 0)
1888 return -EINVAL;
1889
1890 /* Find the first overlapping VMA */
Hugh Dickins146425a2005-04-19 13:29:18 -07001891 vma = find_vma_prev(mm, start, &prev);
1892 if (!vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 return 0;
Hugh Dickins146425a2005-04-19 13:29:18 -07001894 /* we have start < vma->vm_end */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895
1896 /* if it doesn't overlap, we have nothing.. */
1897 end = start + len;
Hugh Dickins146425a2005-04-19 13:29:18 -07001898 if (vma->vm_start >= end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 return 0;
1900
1901 /*
1902 * If we need to split any vma, do it now to save pain later.
1903 *
1904 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1905 * unmapped vm_area_struct will remain in use: so lower split_vma
1906 * places tmp vma above, and higher split_vma places tmp vma below.
1907 */
Hugh Dickins146425a2005-04-19 13:29:18 -07001908 if (start > vma->vm_start) {
1909 int error = split_vma(mm, vma, start, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 if (error)
1911 return error;
Hugh Dickins146425a2005-04-19 13:29:18 -07001912 prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 }
1914
1915 /* Does it split the last one? */
1916 last = find_vma(mm, end);
1917 if (last && end > last->vm_start) {
1918 int error = split_vma(mm, last, end, 1);
1919 if (error)
1920 return error;
1921 }
Hugh Dickins146425a2005-04-19 13:29:18 -07001922 vma = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923
1924 /*
Rik van Rielba470de2008-10-18 20:26:50 -07001925 * unlock any mlock()ed ranges before detaching vmas
1926 */
1927 if (mm->locked_vm) {
1928 struct vm_area_struct *tmp = vma;
1929 while (tmp && tmp->vm_start < end) {
1930 if (tmp->vm_flags & VM_LOCKED) {
1931 mm->locked_vm -= vma_pages(tmp);
1932 munlock_vma_pages_all(tmp);
1933 }
1934 tmp = tmp->vm_next;
1935 }
1936 }
1937
1938 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 * Remove the vma's, and unmap the actual pages
1940 */
Hugh Dickins146425a2005-04-19 13:29:18 -07001941 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1942 unmap_region(mm, vma, prev, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943
1944 /* Fix up all other VM information */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001945 remove_vma_list(mm, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946
1947 return 0;
1948}
1949
1950EXPORT_SYMBOL(do_munmap);
1951
1952asmlinkage long sys_munmap(unsigned long addr, size_t len)
1953{
1954 int ret;
1955 struct mm_struct *mm = current->mm;
1956
1957 profile_munmap(addr);
1958
1959 down_write(&mm->mmap_sem);
1960 ret = do_munmap(mm, addr, len);
1961 up_write(&mm->mmap_sem);
1962 return ret;
1963}
1964
1965static inline void verify_mm_writelocked(struct mm_struct *mm)
1966{
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001967#ifdef CONFIG_DEBUG_VM
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1969 WARN_ON(1);
1970 up_read(&mm->mmap_sem);
1971 }
1972#endif
1973}
1974
1975/*
1976 * this is really a simplified "do_mmap". it only handles
1977 * anonymous maps. eventually we may be able to do some
1978 * brk-specific accounting here.
1979 */
1980unsigned long do_brk(unsigned long addr, unsigned long len)
1981{
1982 struct mm_struct * mm = current->mm;
1983 struct vm_area_struct * vma, * prev;
1984 unsigned long flags;
1985 struct rb_node ** rb_link, * rb_parent;
1986 pgoff_t pgoff = addr >> PAGE_SHIFT;
Kirill Korotaev3a459752006-09-07 14:17:04 +04001987 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988
1989 len = PAGE_ALIGN(len);
1990 if (!len)
1991 return addr;
1992
1993 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1994 return -EINVAL;
1995
Hugh Dickinscd2579d2006-11-14 13:43:38 +00001996 if (is_hugepage_only_range(mm, addr, len))
1997 return -EINVAL;
David Gibsoncb07c9a2006-11-14 02:03:38 -08001998
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01001999 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
Eric Paris5a211a52007-12-04 11:06:55 -05002000 if (error)
2001 return error;
2002
Kirill Korotaev3a459752006-09-07 14:17:04 +04002003 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2004
2005 error = arch_mmap_check(addr, len, flags);
2006 if (error)
2007 return error;
2008
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 /*
2010 * mlock MCL_FUTURE?
2011 */
2012 if (mm->def_flags & VM_LOCKED) {
2013 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -07002014 locked = len >> PAGE_SHIFT;
2015 locked += mm->locked_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
Chris Wright93ea1d02005-05-01 08:58:38 -07002017 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2019 return -EAGAIN;
2020 }
2021
2022 /*
2023 * mm->mmap_sem is required to protect against another thread
2024 * changing the mappings in case we sleep.
2025 */
2026 verify_mm_writelocked(mm);
2027
2028 /*
2029 * Clear old maps. this also does some error checking for us
2030 */
2031 munmap_back:
2032 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2033 if (vma && vma->vm_start < addr + len) {
2034 if (do_munmap(mm, addr, len))
2035 return -ENOMEM;
2036 goto munmap_back;
2037 }
2038
2039 /* Check against address space limits *after* clearing old maps... */
akpm@osdl.org119f6572005-05-01 08:58:35 -07002040 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041 return -ENOMEM;
2042
2043 if (mm->map_count > sysctl_max_map_count)
2044 return -ENOMEM;
2045
2046 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2047 return -ENOMEM;
2048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 /* Can we just expand an old private anonymous mapping? */
Rik van Rielba470de2008-10-18 20:26:50 -07002050 vma = vma_merge(mm, prev, addr, addr + len, flags,
2051 NULL, NULL, pgoff, NULL);
2052 if (vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 goto out;
2054
2055 /*
2056 * create a vma struct for an anonymous mapping
2057 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08002058 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059 if (!vma) {
2060 vm_unacct_memory(len >> PAGE_SHIFT);
2061 return -ENOMEM;
2062 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063
2064 vma->vm_mm = mm;
2065 vma->vm_start = addr;
2066 vma->vm_end = addr + len;
2067 vma->vm_pgoff = pgoff;
2068 vma->vm_flags = flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07002069 vma->vm_page_prot = vm_get_page_prot(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 vma_link(mm, vma, prev, rb_link, rb_parent);
2071out:
2072 mm->total_vm += len >> PAGE_SHIFT;
2073 if (flags & VM_LOCKED) {
Rik van Rielba470de2008-10-18 20:26:50 -07002074 if (!mlock_vma_pages_range(vma, addr, addr + len))
2075 mm->locked_vm += (len >> PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076 }
2077 return addr;
2078}
2079
2080EXPORT_SYMBOL(do_brk);
2081
2082/* Release all mmaps. */
2083void exit_mmap(struct mm_struct *mm)
2084{
2085 struct mmu_gather *tlb;
Rik van Rielba470de2008-10-18 20:26:50 -07002086 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 unsigned long nr_accounted = 0;
Hugh Dickinsee39b372005-04-19 13:29:15 -07002088 unsigned long end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +02002090 /* mm's last user has gone, and its about to be pulled down */
2091 arch_exit_mmap(mm);
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07002092 mmu_notifier_release(mm);
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +02002093
Rik van Rielba470de2008-10-18 20:26:50 -07002094 if (mm->locked_vm) {
2095 vma = mm->mmap;
2096 while (vma) {
2097 if (vma->vm_flags & VM_LOCKED)
2098 munlock_vma_pages_all(vma);
2099 vma = vma->vm_next;
2100 }
2101 }
2102 vma = mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103 lru_add_drain();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002104 flush_cache_mm(mm);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002105 tlb = tlb_gather_mmu(mm, 1);
Hugh Dickins365e9c872005-10-29 18:16:18 -07002106 /* Don't update_hiwater_rss(mm) here, do_exit already did */
Hugh Dickinse0da3822005-04-19 13:29:15 -07002107 /* Use -1 here to ensure all VMAs in the mm are unmapped */
Hugh Dickins508034a2005-10-29 18:16:30 -07002108 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 vm_unacct_memory(nr_accounted);
Jan Beulich42b77722008-07-23 21:27:10 -07002110 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
Hugh Dickinsee39b372005-04-19 13:29:15 -07002111 tlb_finish_mmu(tlb, 0, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 /*
Hugh Dickins8f4f8c12005-10-29 18:16:29 -07002114 * Walk the list again, actually closing and freeing it,
2115 * with preemption enabled, without holding any MM locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002116 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07002117 while (vma)
2118 vma = remove_vma(vma);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002119
Hugh Dickinse2cdef82005-04-19 13:29:19 -07002120 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121}
2122
2123/* Insert vm structure into process list sorted by address
2124 * and into the inode's i_mmap tree. If vm_file is non-NULL
2125 * then i_mmap_lock is taken here.
2126 */
2127int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2128{
2129 struct vm_area_struct * __vma, * prev;
2130 struct rb_node ** rb_link, * rb_parent;
2131
2132 /*
2133 * The vm_pgoff of a purely anonymous vma should be irrelevant
2134 * until its first write fault, when page's anon_vma and index
2135 * are set. But now set the vm_pgoff it will almost certainly
2136 * end up with (unless mremap moves it elsewhere before that
2137 * first wfault), so /proc/pid/maps tells a consistent story.
2138 *
2139 * By setting it to reflect the virtual start address of the
2140 * vma, merges and splits can happen in a seamless way, just
2141 * using the existing file pgoff checks and manipulations.
2142 * Similarly in do_mmap_pgoff and in do_brk.
2143 */
2144 if (!vma->vm_file) {
2145 BUG_ON(vma->anon_vma);
2146 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2147 }
2148 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2149 if (__vma && __vma->vm_start < vma->vm_end)
2150 return -ENOMEM;
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002151 if ((vma->vm_flags & VM_ACCOUNT) &&
Alan Cox34b4e4a2007-08-22 14:01:28 -07002152 security_vm_enough_memory_mm(mm, vma_pages(vma)))
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002153 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154 vma_link(mm, vma, prev, rb_link, rb_parent);
2155 return 0;
2156}
2157
2158/*
2159 * Copy the vma structure to a new location in the same mm,
2160 * prior to moving page table entries, to effect an mremap move.
2161 */
2162struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2163 unsigned long addr, unsigned long len, pgoff_t pgoff)
2164{
2165 struct vm_area_struct *vma = *vmap;
2166 unsigned long vma_start = vma->vm_start;
2167 struct mm_struct *mm = vma->vm_mm;
2168 struct vm_area_struct *new_vma, *prev;
2169 struct rb_node **rb_link, *rb_parent;
2170 struct mempolicy *pol;
2171
2172 /*
2173 * If anonymous vma has not yet been faulted, update new pgoff
2174 * to match new location, to increase its chance of merging.
2175 */
2176 if (!vma->vm_file && !vma->anon_vma)
2177 pgoff = addr >> PAGE_SHIFT;
2178
2179 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2180 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2181 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2182 if (new_vma) {
2183 /*
2184 * Source vma may have been merged into new_vma
2185 */
2186 if (vma_start >= new_vma->vm_start &&
2187 vma_start < new_vma->vm_end)
2188 *vmap = new_vma;
2189 } else {
Christoph Lametere94b1762006-12-06 20:33:17 -08002190 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 if (new_vma) {
2192 *new_vma = *vma;
Lee Schermerhorn846a16b2008-04-28 02:13:09 -07002193 pol = mpol_dup(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194 if (IS_ERR(pol)) {
2195 kmem_cache_free(vm_area_cachep, new_vma);
2196 return NULL;
2197 }
2198 vma_set_policy(new_vma, pol);
2199 new_vma->vm_start = addr;
2200 new_vma->vm_end = addr + len;
2201 new_vma->vm_pgoff = pgoff;
Matt Helsley925d1c42008-04-29 01:01:36 -07002202 if (new_vma->vm_file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 get_file(new_vma->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -07002204 if (vma->vm_flags & VM_EXECUTABLE)
2205 added_exe_file_vma(mm);
2206 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 if (new_vma->vm_ops && new_vma->vm_ops->open)
2208 new_vma->vm_ops->open(new_vma);
2209 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2210 }
2211 }
2212 return new_vma;
2213}
akpm@osdl.org119f6572005-05-01 08:58:35 -07002214
2215/*
2216 * Return true if the calling process may expand its vm space by the passed
2217 * number of pages
2218 */
2219int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2220{
2221 unsigned long cur = mm->total_vm; /* pages */
2222 unsigned long lim;
2223
2224 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2225
2226 if (cur + npages > lim)
2227 return 0;
2228 return 1;
2229}
Roland McGrathfa5dc222007-02-08 14:20:41 -08002230
2231
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002232static int special_mapping_fault(struct vm_area_struct *vma,
2233 struct vm_fault *vmf)
Roland McGrathfa5dc222007-02-08 14:20:41 -08002234{
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002235 pgoff_t pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002236 struct page **pages;
2237
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002238 /*
2239 * special mappings have no vm_file, and in that case, the mm
2240 * uses vm_pgoff internally. So we have to subtract it from here.
2241 * We are allowed to do this because we are the mm; do not copy
2242 * this code into drivers!
2243 */
2244 pgoff = vmf->pgoff - vma->vm_pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002245
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002246 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2247 pgoff--;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002248
2249 if (*pages) {
2250 struct page *page = *pages;
2251 get_page(page);
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002252 vmf->page = page;
2253 return 0;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002254 }
2255
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002256 return VM_FAULT_SIGBUS;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002257}
2258
2259/*
2260 * Having a close hook prevents vma merging regardless of flags.
2261 */
2262static void special_mapping_close(struct vm_area_struct *vma)
2263{
2264}
2265
2266static struct vm_operations_struct special_mapping_vmops = {
2267 .close = special_mapping_close,
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002268 .fault = special_mapping_fault,
Roland McGrathfa5dc222007-02-08 14:20:41 -08002269};
2270
2271/*
2272 * Called with mm->mmap_sem held for writing.
2273 * Insert a new vma covering the given region, with the given flags.
2274 * Its pages are supplied by the given array of struct page *.
2275 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2276 * The region past the last page supplied will always produce SIGBUS.
2277 * The array pointer and the pages it points to are assumed to stay alive
2278 * for as long as this mapping might exist.
2279 */
2280int install_special_mapping(struct mm_struct *mm,
2281 unsigned long addr, unsigned long len,
2282 unsigned long vm_flags, struct page **pages)
2283{
2284 struct vm_area_struct *vma;
2285
2286 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2287 if (unlikely(vma == NULL))
2288 return -ENOMEM;
2289
2290 vma->vm_mm = mm;
2291 vma->vm_start = addr;
2292 vma->vm_end = addr + len;
2293
Nick Piggin2f987352008-02-02 03:08:53 +01002294 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
Coly Li3ed75eb2007-10-18 23:39:15 -07002295 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
Roland McGrathfa5dc222007-02-08 14:20:41 -08002296
2297 vma->vm_ops = &special_mapping_vmops;
2298 vma->vm_private_data = pages;
2299
2300 if (unlikely(insert_vm_struct(mm, vma))) {
2301 kmem_cache_free(vm_area_cachep, vma);
2302 return -ENOMEM;
2303 }
2304
2305 mm->total_vm += len >> PAGE_SHIFT;
2306
2307 return 0;
2308}
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002309
2310static DEFINE_MUTEX(mm_all_locks_mutex);
2311
Peter Zijlstra454ed842008-08-11 09:30:25 +02002312static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002313{
2314 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2315 /*
2316 * The LSB of head.next can't change from under us
2317 * because we hold the mm_all_locks_mutex.
2318 */
Peter Zijlstra454ed842008-08-11 09:30:25 +02002319 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002320 /*
2321 * We can safely modify head.next after taking the
2322 * anon_vma->lock. If some other vma in this mm shares
2323 * the same anon_vma we won't take it again.
2324 *
2325 * No need of atomic instructions here, head.next
2326 * can't change from under us thanks to the
2327 * anon_vma->lock.
2328 */
2329 if (__test_and_set_bit(0, (unsigned long *)
2330 &anon_vma->head.next))
2331 BUG();
2332 }
2333}
2334
Peter Zijlstra454ed842008-08-11 09:30:25 +02002335static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002336{
2337 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2338 /*
2339 * AS_MM_ALL_LOCKS can't change from under us because
2340 * we hold the mm_all_locks_mutex.
2341 *
2342 * Operations on ->flags have to be atomic because
2343 * even if AS_MM_ALL_LOCKS is stable thanks to the
2344 * mm_all_locks_mutex, there may be other cpus
2345 * changing other bitflags in parallel to us.
2346 */
2347 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2348 BUG();
Peter Zijlstra454ed842008-08-11 09:30:25 +02002349 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002350 }
2351}
2352
2353/*
2354 * This operation locks against the VM for all pte/vma/mm related
2355 * operations that could ever happen on a certain mm. This includes
2356 * vmtruncate, try_to_unmap, and all page faults.
2357 *
2358 * The caller must take the mmap_sem in write mode before calling
2359 * mm_take_all_locks(). The caller isn't allowed to release the
2360 * mmap_sem until mm_drop_all_locks() returns.
2361 *
2362 * mmap_sem in write mode is required in order to block all operations
2363 * that could modify pagetables and free pages without need of
2364 * altering the vma layout (for example populate_range() with
2365 * nonlinear vmas). It's also needed in write mode to avoid new
2366 * anon_vmas to be associated with existing vmas.
2367 *
2368 * A single task can't take more than one mm_take_all_locks() in a row
2369 * or it would deadlock.
2370 *
2371 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2372 * mapping->flags avoid to take the same lock twice, if more than one
2373 * vma in this mm is backed by the same anon_vma or address_space.
2374 *
2375 * We can take all the locks in random order because the VM code
2376 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2377 * takes more than one of them in a row. Secondly we're protected
2378 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2379 *
2380 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2381 * that may have to take thousand of locks.
2382 *
2383 * mm_take_all_locks() can fail if it's interrupted by signals.
2384 */
2385int mm_take_all_locks(struct mm_struct *mm)
2386{
2387 struct vm_area_struct *vma;
2388 int ret = -EINTR;
2389
2390 BUG_ON(down_read_trylock(&mm->mmap_sem));
2391
2392 mutex_lock(&mm_all_locks_mutex);
2393
2394 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2395 if (signal_pending(current))
2396 goto out_unlock;
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002397 if (vma->vm_file && vma->vm_file->f_mapping)
Peter Zijlstra454ed842008-08-11 09:30:25 +02002398 vm_lock_mapping(mm, vma->vm_file->f_mapping);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002399 }
Peter Zijlstra7cd5a022008-08-11 09:30:25 +02002400
2401 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2402 if (signal_pending(current))
2403 goto out_unlock;
2404 if (vma->anon_vma)
2405 vm_lock_anon_vma(mm, vma->anon_vma);
2406 }
2407
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002408 ret = 0;
2409
2410out_unlock:
2411 if (ret)
2412 mm_drop_all_locks(mm);
2413
2414 return ret;
2415}
2416
2417static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2418{
2419 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2420 /*
2421 * The LSB of head.next can't change to 0 from under
2422 * us because we hold the mm_all_locks_mutex.
2423 *
2424 * We must however clear the bitflag before unlocking
2425 * the vma so the users using the anon_vma->head will
2426 * never see our bitflag.
2427 *
2428 * No need of atomic instructions here, head.next
2429 * can't change from under us until we release the
2430 * anon_vma->lock.
2431 */
2432 if (!__test_and_clear_bit(0, (unsigned long *)
2433 &anon_vma->head.next))
2434 BUG();
2435 spin_unlock(&anon_vma->lock);
2436 }
2437}
2438
2439static void vm_unlock_mapping(struct address_space *mapping)
2440{
2441 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2442 /*
2443 * AS_MM_ALL_LOCKS can't change to 0 from under us
2444 * because we hold the mm_all_locks_mutex.
2445 */
2446 spin_unlock(&mapping->i_mmap_lock);
2447 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2448 &mapping->flags))
2449 BUG();
2450 }
2451}
2452
2453/*
2454 * The mmap_sem cannot be released by the caller until
2455 * mm_drop_all_locks() returns.
2456 */
2457void mm_drop_all_locks(struct mm_struct *mm)
2458{
2459 struct vm_area_struct *vma;
2460
2461 BUG_ON(down_read_trylock(&mm->mmap_sem));
2462 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2463
2464 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2465 if (vma->anon_vma)
2466 vm_unlock_anon_vma(vma->anon_vma);
2467 if (vma->vm_file && vma->vm_file->f_mapping)
2468 vm_unlock_mapping(vma->vm_file->f_mapping);
2469 }
2470
2471 mutex_unlock(&mm_all_locks_mutex);
2472}