blob: 456ec6f278897a560bd915e6d84297ac3de7ddef [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
Alan Cox046c6882009-01-05 14:06:29 +00006 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 */
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>
Ingo Molnarcdd6c482009-09-21 12:02:48 +020030#include <linux/perf_event.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32#include <asm/uaccess.h>
33#include <asm/cacheflush.h>
34#include <asm/tlb.h>
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +020035#include <asm/mmu_context.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Jan Beulich42b77722008-07-23 21:27:10 -070037#include "internal.h"
38
Kirill Korotaev3a459752006-09-07 14:17:04 +040039#ifndef arch_mmap_check
40#define arch_mmap_check(addr, len, flags) (0)
41#endif
42
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -080043#ifndef arch_rebalance_pgtables
44#define arch_rebalance_pgtables(addr, len) (addr)
45#endif
46
Hugh Dickinse0da3822005-04-19 13:29:15 -070047static void unmap_region(struct mm_struct *mm,
48 struct vm_area_struct *vma, struct vm_area_struct *prev,
49 unsigned long start, unsigned long end);
50
Linus Torvalds1da177e2005-04-16 15:20:36 -070051/*
52 * WARNING: the debugging will use recursive algorithms so never enable this
53 * unless you know what you are doing.
54 */
55#undef DEBUG_MM_RB
56
57/* description of effects of mapping type and prot in current implementation.
58 * this is due to the limited x86 page protection hardware. The expected
59 * behavior is in parens:
60 *
61 * map_type prot
62 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
63 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
64 * w: (no) no w: (no) no w: (yes) yes w: (no) no
65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
66 *
67 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
68 * w: (no) no w: (no) no w: (copy) copy w: (no) no
69 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
70 *
71 */
72pgprot_t protection_map[16] = {
73 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
74 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
75};
76
Hugh Dickins804af2c2006-07-26 21:39:49 +010077pgprot_t vm_get_page_prot(unsigned long vm_flags)
78{
Dave Kleikampb845f312008-07-08 00:28:51 +100079 return __pgprot(pgprot_val(protection_map[vm_flags &
80 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
81 pgprot_val(arch_vm_get_page_prot(vm_flags)));
Hugh Dickins804af2c2006-07-26 21:39:49 +010082}
83EXPORT_SYMBOL(vm_get_page_prot);
84
Linus Torvalds1da177e2005-04-16 15:20:36 -070085int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
86int sysctl_overcommit_ratio = 50; /* default is 50% */
Christoph Lameterc3d8c142005-09-06 15:16:33 -070087int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -070088struct percpu_counter vm_committed_as;
Linus Torvalds1da177e2005-04-16 15:20:36 -070089
90/*
91 * Check that a process has enough memory to allocate a new virtual
92 * mapping. 0 means there is enough memory for the allocation to
93 * succeed and -ENOMEM implies there is not.
94 *
95 * We currently support three overcommit policies, which are set via the
96 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
97 *
98 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
99 * Additional code 2002 Jul 20 by Robert Love.
100 *
101 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
102 *
103 * Note this is a helper function intended to be used by LSMs which
104 * wish to use this logic.
105 */
Alan Cox34b4e4a2007-08-22 14:01:28 -0700106int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
108 unsigned long free, allowed;
109
110 vm_acct_memory(pages);
111
112 /*
113 * Sometimes we want to use more memory than we have
114 */
115 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
116 return 0;
117
118 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
119 unsigned long n;
120
Christoph Lameter347ce432006-06-30 01:55:35 -0700121 free = global_page_state(NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 free += nr_swap_pages;
123
124 /*
125 * Any slabs which are created with the
126 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
127 * which are reclaimable, under pressure. The dentry
128 * cache and most inode caches should fall into this
129 */
Christoph Lameter972d1a72006-09-25 23:31:51 -0700130 free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
132 /*
133 * Leave the last 3% for root
134 */
135 if (!cap_sys_admin)
136 free -= free / 32;
137
138 if (free > pages)
139 return 0;
140
141 /*
142 * nr_free_pages() is very expensive on large systems,
143 * only call if we're about to fail.
144 */
145 n = nr_free_pages();
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700146
147 /*
148 * Leave reserved pages. The pages are not for anonymous pages.
149 */
150 if (n <= totalreserve_pages)
151 goto error;
152 else
153 n -= totalreserve_pages;
154
155 /*
156 * Leave the last 3% for root
157 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 if (!cap_sys_admin)
159 n -= n / 32;
160 free += n;
161
162 if (free > pages)
163 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700164
165 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 }
167
168 allowed = (totalram_pages - hugetlb_total_pages())
169 * sysctl_overcommit_ratio / 100;
170 /*
171 * Leave the last 3% for root
172 */
173 if (!cap_sys_admin)
174 allowed -= allowed / 32;
175 allowed += total_swap_pages;
176
177 /* Don't let a single process grow too big:
178 leave 3% of the size of this process for other processes */
Alan Cox731572d2008-10-29 14:01:20 -0700179 if (mm)
180 allowed -= mm->total_vm / 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -0700182 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700184error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 vm_unacct_memory(pages);
186
187 return -ENOMEM;
188}
189
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190/*
191 * Requires inode->i_mapping->i_mmap_lock
192 */
193static void __remove_shared_vm_struct(struct vm_area_struct *vma,
194 struct file *file, struct address_space *mapping)
195{
196 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800197 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 if (vma->vm_flags & VM_SHARED)
199 mapping->i_mmap_writable--;
200
201 flush_dcache_mmap_lock(mapping);
202 if (unlikely(vma->vm_flags & VM_NONLINEAR))
203 list_del_init(&vma->shared.vm_set.list);
204 else
205 vma_prio_tree_remove(vma, &mapping->i_mmap);
206 flush_dcache_mmap_unlock(mapping);
207}
208
209/*
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700210 * Unlink a file-based vm structure from its prio_tree, to hide
211 * vma from rmap and vmtruncate before freeing its page tables.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700213void unlink_file_vma(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
215 struct file *file = vma->vm_file;
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 if (file) {
218 struct address_space *mapping = file->f_mapping;
219 spin_lock(&mapping->i_mmap_lock);
220 __remove_shared_vm_struct(vma, file, mapping);
221 spin_unlock(&mapping->i_mmap_lock);
222 }
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700223}
224
225/*
226 * Close a vm structure and free it, returning the next.
227 */
228static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
229{
230 struct vm_area_struct *next = vma->vm_next;
231
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700232 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 if (vma->vm_ops && vma->vm_ops->close)
234 vma->vm_ops->close(vma);
Matt Helsley925d1c42008-04-29 01:01:36 -0700235 if (vma->vm_file) {
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700236 fput(vma->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -0700237 if (vma->vm_flags & VM_EXECUTABLE)
238 removed_exe_file_vma(vma->vm_mm);
239 }
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700240 mpol_put(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 kmem_cache_free(vm_area_cachep, vma);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700242 return next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243}
244
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100245SYSCALL_DEFINE1(brk, unsigned long, brk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246{
247 unsigned long rlim, retval;
248 unsigned long newbrk, oldbrk;
249 struct mm_struct *mm = current->mm;
Jiri Kosinaa5b45922008-06-05 22:46:05 -0700250 unsigned long min_brk;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251
252 down_write(&mm->mmap_sem);
253
Jiri Kosinaa5b45922008-06-05 22:46:05 -0700254#ifdef CONFIG_COMPAT_BRK
255 min_brk = mm->end_code;
256#else
257 min_brk = mm->start_brk;
258#endif
259 if (brk < min_brk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 goto out;
Ram Gupta1e624192006-04-10 22:52:57 -0700261
262 /*
263 * Check against rlimit here. If this check is done later after the test
264 * of oldbrk with newbrk then it can escape the test and let the data
265 * segment grow beyond its set limit the in case where the limit is
266 * not page aligned -Ram Gupta
267 */
Jiri Slaby59e99e52010-03-05 13:41:44 -0800268 rlim = rlimit(RLIMIT_DATA);
Jiri Kosinac1d171a2008-01-30 13:30:40 +0100269 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
270 (mm->end_data - mm->start_data) > rlim)
Ram Gupta1e624192006-04-10 22:52:57 -0700271 goto out;
272
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 newbrk = PAGE_ALIGN(brk);
274 oldbrk = PAGE_ALIGN(mm->brk);
275 if (oldbrk == newbrk)
276 goto set_brk;
277
278 /* Always allow shrinking brk. */
279 if (brk <= mm->brk) {
280 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
281 goto set_brk;
282 goto out;
283 }
284
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 /* Check against existing mmap mappings. */
286 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
287 goto out;
288
289 /* Ok, looks good - let it rip. */
290 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
291 goto out;
292set_brk:
293 mm->brk = brk;
294out:
295 retval = mm->brk;
296 up_write(&mm->mmap_sem);
297 return retval;
298}
299
300#ifdef DEBUG_MM_RB
301static int browse_rb(struct rb_root *root)
302{
303 int i = 0, j;
304 struct rb_node *nd, *pn = NULL;
305 unsigned long prev = 0, pend = 0;
306
307 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
308 struct vm_area_struct *vma;
309 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
310 if (vma->vm_start < prev)
311 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
312 if (vma->vm_start < pend)
313 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
314 if (vma->vm_start > vma->vm_end)
315 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
316 i++;
317 pn = nd;
David Millerd1af65d2007-02-28 20:13:13 -0800318 prev = vma->vm_start;
319 pend = vma->vm_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 }
321 j = 0;
322 for (nd = pn; nd; nd = rb_prev(nd)) {
323 j++;
324 }
325 if (i != j)
326 printk("backwards %d, forwards %d\n", j, i), i = 0;
327 return i;
328}
329
330void validate_mm(struct mm_struct *mm)
331{
332 int bug = 0;
333 int i = 0;
334 struct vm_area_struct *tmp = mm->mmap;
335 while (tmp) {
336 tmp = tmp->vm_next;
337 i++;
338 }
339 if (i != mm->map_count)
340 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
341 i = browse_rb(&mm->mm_rb);
342 if (i != mm->map_count)
343 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200344 BUG_ON(bug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345}
346#else
347#define validate_mm(mm) do { } while (0)
348#endif
349
350static struct vm_area_struct *
351find_vma_prepare(struct mm_struct *mm, unsigned long addr,
352 struct vm_area_struct **pprev, struct rb_node ***rb_link,
353 struct rb_node ** rb_parent)
354{
355 struct vm_area_struct * vma;
356 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
357
358 __rb_link = &mm->mm_rb.rb_node;
359 rb_prev = __rb_parent = NULL;
360 vma = NULL;
361
362 while (*__rb_link) {
363 struct vm_area_struct *vma_tmp;
364
365 __rb_parent = *__rb_link;
366 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
367
368 if (vma_tmp->vm_end > addr) {
369 vma = vma_tmp;
370 if (vma_tmp->vm_start <= addr)
Benny Halevydfe195f2008-08-05 13:01:41 -0700371 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 __rb_link = &__rb_parent->rb_left;
373 } else {
374 rb_prev = __rb_parent;
375 __rb_link = &__rb_parent->rb_right;
376 }
377 }
378
379 *pprev = NULL;
380 if (rb_prev)
381 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
382 *rb_link = __rb_link;
383 *rb_parent = __rb_parent;
384 return vma;
385}
386
387static inline void
388__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
389 struct vm_area_struct *prev, struct rb_node *rb_parent)
390{
391 if (prev) {
392 vma->vm_next = prev->vm_next;
393 prev->vm_next = vma;
394 } else {
395 mm->mmap = vma;
396 if (rb_parent)
397 vma->vm_next = rb_entry(rb_parent,
398 struct vm_area_struct, vm_rb);
399 else
400 vma->vm_next = NULL;
401 }
402}
403
404void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
405 struct rb_node **rb_link, struct rb_node *rb_parent)
406{
407 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
408 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
409}
410
Denys Vlasenkocb8f4882008-10-18 20:27:01 -0700411static void __vma_link_file(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412{
ZhenwenXu48aae422009-01-06 14:40:21 -0800413 struct file *file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414
415 file = vma->vm_file;
416 if (file) {
417 struct address_space *mapping = file->f_mapping;
418
419 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800420 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 if (vma->vm_flags & VM_SHARED)
422 mapping->i_mmap_writable++;
423
424 flush_dcache_mmap_lock(mapping);
425 if (unlikely(vma->vm_flags & VM_NONLINEAR))
426 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
427 else
428 vma_prio_tree_insert(vma, &mapping->i_mmap);
429 flush_dcache_mmap_unlock(mapping);
430 }
431}
432
433static void
434__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
435 struct vm_area_struct *prev, struct rb_node **rb_link,
436 struct rb_node *rb_parent)
437{
438 __vma_link_list(mm, vma, prev, rb_parent);
439 __vma_link_rb(mm, vma, rb_link, rb_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440}
441
442static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
443 struct vm_area_struct *prev, struct rb_node **rb_link,
444 struct rb_node *rb_parent)
445{
446 struct address_space *mapping = NULL;
447
448 if (vma->vm_file)
449 mapping = vma->vm_file->f_mapping;
450
451 if (mapping) {
452 spin_lock(&mapping->i_mmap_lock);
453 vma->vm_truncate_count = mapping->truncate_count;
454 }
455 anon_vma_lock(vma);
456
457 __vma_link(mm, vma, prev, rb_link, rb_parent);
458 __vma_link_file(vma);
459
460 anon_vma_unlock(vma);
461 if (mapping)
462 spin_unlock(&mapping->i_mmap_lock);
463
464 mm->map_count++;
465 validate_mm(mm);
466}
467
468/*
469 * Helper for vma_adjust in the split_vma insert case:
470 * insert vm structure into list and rbtree and anon_vma,
471 * but it has already been inserted into prio_tree earlier.
472 */
ZhenwenXu48aae422009-01-06 14:40:21 -0800473static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474{
ZhenwenXu48aae422009-01-06 14:40:21 -0800475 struct vm_area_struct *__vma, *prev;
476 struct rb_node **rb_link, *rb_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
478 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200479 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 __vma_link(mm, vma, prev, rb_link, rb_parent);
481 mm->map_count++;
482}
483
484static inline void
485__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
486 struct vm_area_struct *prev)
487{
488 prev->vm_next = vma->vm_next;
489 rb_erase(&vma->vm_rb, &mm->mm_rb);
490 if (mm->mmap_cache == vma)
491 mm->mmap_cache = prev;
492}
493
494/*
495 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
496 * is already present in an i_mmap tree without adjusting the tree.
497 * The following helper function should be used when such adjustments
498 * are necessary. The "insert" vma (if any) is to be inserted
499 * before we drop the necessary locks.
500 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800501int vma_adjust(struct vm_area_struct *vma, unsigned long start,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
503{
504 struct mm_struct *mm = vma->vm_mm;
505 struct vm_area_struct *next = vma->vm_next;
506 struct vm_area_struct *importer = NULL;
507 struct address_space *mapping = NULL;
508 struct prio_tree_root *root = NULL;
509 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 long adjust_next = 0;
511 int remove_next = 0;
512
513 if (next && !insert) {
Linus Torvalds287d97a2010-04-10 15:22:30 -0700514 struct vm_area_struct *exporter = NULL;
515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 if (end >= next->vm_end) {
517 /*
518 * vma expands, overlapping all the next, and
519 * perhaps the one after too (mprotect case 6).
520 */
521again: remove_next = 1 + (end > next->vm_end);
522 end = next->vm_end;
Linus Torvalds287d97a2010-04-10 15:22:30 -0700523 exporter = next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 importer = vma;
525 } else if (end > next->vm_start) {
526 /*
527 * vma expands, overlapping part of the next:
528 * mprotect case 5 shifting the boundary up.
529 */
530 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
Linus Torvalds287d97a2010-04-10 15:22:30 -0700531 exporter = next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 importer = vma;
533 } else if (end < vma->vm_end) {
534 /*
535 * vma shrinks, and !insert tells it's not
536 * split_vma inserting another: so it must be
537 * mprotect case 4 shifting the boundary down.
538 */
539 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
Linus Torvalds287d97a2010-04-10 15:22:30 -0700540 exporter = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 importer = next;
542 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
Rik van Riel5beb4932010-03-05 13:42:07 -0800544 /*
545 * Easily overlooked: when mprotect shifts the boundary,
546 * make sure the expanding vma has anon_vma set if the
547 * shrinking vma had, to cover any anon pages imported.
548 */
Linus Torvalds287d97a2010-04-10 15:22:30 -0700549 if (exporter && exporter->anon_vma && !importer->anon_vma) {
550 if (anon_vma_clone(importer, exporter))
Rik van Riel5beb4932010-03-05 13:42:07 -0800551 return -ENOMEM;
Linus Torvalds287d97a2010-04-10 15:22:30 -0700552 importer->anon_vma = exporter->anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800553 }
554 }
555
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 if (file) {
557 mapping = file->f_mapping;
558 if (!(vma->vm_flags & VM_NONLINEAR))
559 root = &mapping->i_mmap;
560 spin_lock(&mapping->i_mmap_lock);
561 if (importer &&
562 vma->vm_truncate_count != next->vm_truncate_count) {
563 /*
564 * unmap_mapping_range might be in progress:
565 * ensure that the expanding vma is rescanned.
566 */
567 importer->vm_truncate_count = 0;
568 }
569 if (insert) {
570 insert->vm_truncate_count = vma->vm_truncate_count;
571 /*
572 * Put into prio_tree now, so instantiated pages
573 * are visible to arm/parisc __flush_dcache_page
574 * throughout; but we cannot insert into address
575 * space until vma start or end is updated.
576 */
577 __vma_link_file(insert);
578 }
579 }
580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 if (root) {
582 flush_dcache_mmap_lock(mapping);
583 vma_prio_tree_remove(vma, root);
584 if (adjust_next)
585 vma_prio_tree_remove(next, root);
586 }
587
588 vma->vm_start = start;
589 vma->vm_end = end;
590 vma->vm_pgoff = pgoff;
591 if (adjust_next) {
592 next->vm_start += adjust_next << PAGE_SHIFT;
593 next->vm_pgoff += adjust_next;
594 }
595
596 if (root) {
597 if (adjust_next)
598 vma_prio_tree_insert(next, root);
599 vma_prio_tree_insert(vma, root);
600 flush_dcache_mmap_unlock(mapping);
601 }
602
603 if (remove_next) {
604 /*
605 * vma_merge has merged next into vma, and needs
606 * us to remove next before dropping the locks.
607 */
608 __vma_unlink(mm, next, vma);
609 if (file)
610 __remove_shared_vm_struct(next, file, mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 } else if (insert) {
612 /*
613 * split_vma has split insert from vma, and needs
614 * us to insert it before dropping the locks
615 * (it may either follow vma or precede it).
616 */
617 __insert_vm_struct(mm, insert);
618 }
619
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 if (mapping)
621 spin_unlock(&mapping->i_mmap_lock);
622
623 if (remove_next) {
Matt Helsley925d1c42008-04-29 01:01:36 -0700624 if (file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 fput(file);
Matt Helsley925d1c42008-04-29 01:01:36 -0700626 if (next->vm_flags & VM_EXECUTABLE)
627 removed_exe_file_vma(mm);
628 }
Rik van Riel5beb4932010-03-05 13:42:07 -0800629 if (next->anon_vma)
630 anon_vma_merge(vma, next);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 mm->map_count--;
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700632 mpol_put(vma_policy(next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 kmem_cache_free(vm_area_cachep, next);
634 /*
635 * In mprotect's case 6 (see comments on vma_merge),
636 * we must remove another next too. It would clutter
637 * up the code too much to do both in one go.
638 */
639 if (remove_next == 2) {
640 next = vma->vm_next;
641 goto again;
642 }
643 }
644
645 validate_mm(mm);
Rik van Riel5beb4932010-03-05 13:42:07 -0800646
647 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648}
649
650/*
651 * If the vma has a ->close operation then the driver probably needs to release
652 * per-vma resources, so we don't attempt to merge those.
653 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654static inline int is_mergeable_vma(struct vm_area_struct *vma,
655 struct file *file, unsigned long vm_flags)
656{
Hugh Dickins8314c4f2009-09-21 17:02:25 -0700657 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
658 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 return 0;
660 if (vma->vm_file != file)
661 return 0;
662 if (vma->vm_ops && vma->vm_ops->close)
663 return 0;
664 return 1;
665}
666
667static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
668 struct anon_vma *anon_vma2)
669{
670 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
671}
672
673/*
674 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
675 * in front of (at a lower virtual address and file offset than) the vma.
676 *
677 * We cannot merge two vmas if they have differently assigned (non-NULL)
678 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
679 *
680 * We don't check here for the merged mmap wrapping around the end of pagecache
681 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
682 * wrap, nor mmaps which cover the final page at index -1UL.
683 */
684static int
685can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
686 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
687{
688 if (is_mergeable_vma(vma, file, vm_flags) &&
689 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
690 if (vma->vm_pgoff == vm_pgoff)
691 return 1;
692 }
693 return 0;
694}
695
696/*
697 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
698 * beyond (at a higher virtual address and file offset than) the vma.
699 *
700 * We cannot merge two vmas if they have differently assigned (non-NULL)
701 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
702 */
703static int
704can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
705 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
706{
707 if (is_mergeable_vma(vma, file, vm_flags) &&
708 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
709 pgoff_t vm_pglen;
710 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
711 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
712 return 1;
713 }
714 return 0;
715}
716
717/*
718 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
719 * whether that can be merged with its predecessor or its successor.
720 * Or both (it neatly fills a hole).
721 *
722 * In most cases - when called for mmap, brk or mremap - [addr,end) is
723 * certain not to be mapped by the time vma_merge is called; but when
724 * called for mprotect, it is certain to be already mapped (either at
725 * an offset within prev, or at the start of next), and the flags of
726 * this area are about to be changed to vm_flags - and the no-change
727 * case has already been eliminated.
728 *
729 * The following mprotect cases have to be considered, where AAAA is
730 * the area passed down from mprotect_fixup, never extending beyond one
731 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
732 *
733 * AAAA AAAA AAAA AAAA
734 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
735 * cannot merge might become might become might become
736 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
737 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
738 * mremap move: PPPPNNNNNNNN 8
739 * AAAA
740 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
741 * might become case 1 below case 2 below case 3 below
742 *
743 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
744 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
745 */
746struct vm_area_struct *vma_merge(struct mm_struct *mm,
747 struct vm_area_struct *prev, unsigned long addr,
748 unsigned long end, unsigned long vm_flags,
749 struct anon_vma *anon_vma, struct file *file,
750 pgoff_t pgoff, struct mempolicy *policy)
751{
752 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
753 struct vm_area_struct *area, *next;
Rik van Riel5beb4932010-03-05 13:42:07 -0800754 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
756 /*
757 * We later require that vma->vm_flags == vm_flags,
758 * so this tests vma->vm_flags & VM_SPECIAL, too.
759 */
760 if (vm_flags & VM_SPECIAL)
761 return NULL;
762
763 if (prev)
764 next = prev->vm_next;
765 else
766 next = mm->mmap;
767 area = next;
768 if (next && next->vm_end == end) /* cases 6, 7, 8 */
769 next = next->vm_next;
770
771 /*
772 * Can it merge with the predecessor?
773 */
774 if (prev && prev->vm_end == addr &&
775 mpol_equal(vma_policy(prev), policy) &&
776 can_vma_merge_after(prev, vm_flags,
777 anon_vma, file, pgoff)) {
778 /*
779 * OK, it can. Can we now merge in the successor as well?
780 */
781 if (next && end == next->vm_start &&
782 mpol_equal(policy, vma_policy(next)) &&
783 can_vma_merge_before(next, vm_flags,
784 anon_vma, file, pgoff+pglen) &&
785 is_mergeable_anon_vma(prev->anon_vma,
786 next->anon_vma)) {
787 /* cases 1, 6 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800788 err = vma_adjust(prev, prev->vm_start,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 next->vm_end, prev->vm_pgoff, NULL);
790 } else /* cases 2, 5, 7 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800791 err = vma_adjust(prev, prev->vm_start,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 end, prev->vm_pgoff, NULL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800793 if (err)
794 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 return prev;
796 }
797
798 /*
799 * Can this new request be merged in front of next?
800 */
801 if (next && end == next->vm_start &&
802 mpol_equal(policy, vma_policy(next)) &&
803 can_vma_merge_before(next, vm_flags,
804 anon_vma, file, pgoff+pglen)) {
805 if (prev && addr < prev->vm_end) /* case 4 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800806 err = vma_adjust(prev, prev->vm_start,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 addr, prev->vm_pgoff, NULL);
808 else /* cases 3, 8 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800809 err = vma_adjust(area, addr, next->vm_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 next->vm_pgoff - pglen, NULL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800811 if (err)
812 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 return area;
814 }
815
816 return NULL;
817}
818
819/*
Linus Torvaldsd0e9fe12010-04-10 10:36:19 -0700820 * Rough compatbility check to quickly see if it's even worth looking
821 * at sharing an anon_vma.
822 *
823 * They need to have the same vm_file, and the flags can only differ
824 * in things that mprotect may change.
825 *
826 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
827 * we can merge the two vma's. For example, we refuse to merge a vma if
828 * there is a vm_ops->close() function, because that indicates that the
829 * driver is doing some kind of reference counting. But that doesn't
830 * really matter for the anon_vma sharing case.
831 */
832static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
833{
834 return a->vm_end == b->vm_start &&
835 mpol_equal(vma_policy(a), vma_policy(b)) &&
836 a->vm_file == b->vm_file &&
837 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
838 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
839}
840
841/*
842 * Do some basic sanity checking to see if we can re-use the anon_vma
843 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
844 * the same as 'old', the other will be the new one that is trying
845 * to share the anon_vma.
846 *
847 * NOTE! This runs with mm_sem held for reading, so it is possible that
848 * the anon_vma of 'old' is concurrently in the process of being set up
849 * by another page fault trying to merge _that_. But that's ok: if it
850 * is being set up, that automatically means that it will be a singleton
851 * acceptable for merging, so we can do all of this optimistically. But
852 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
853 *
854 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
855 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
856 * is to return an anon_vma that is "complex" due to having gone through
857 * a fork).
858 *
859 * We also make sure that the two vma's are compatible (adjacent,
860 * and with the same memory policies). That's all stable, even with just
861 * a read lock on the mm_sem.
862 */
863static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
864{
865 if (anon_vma_compatible(a, b)) {
866 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
867
868 if (anon_vma && list_is_singular(&old->anon_vma_chain))
869 return anon_vma;
870 }
871 return NULL;
872}
873
874/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
876 * neighbouring vmas for a suitable anon_vma, before it goes off
877 * to allocate a new anon_vma. It checks because a repetitive
878 * sequence of mprotects and faults may otherwise lead to distinct
879 * anon_vmas being allocated, preventing vma merge in subsequent
880 * mprotect.
881 */
882struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
883{
Linus Torvaldsd0e9fe12010-04-10 10:36:19 -0700884 struct anon_vma *anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 struct vm_area_struct *near;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886
887 near = vma->vm_next;
888 if (!near)
889 goto try_prev;
890
Linus Torvaldsd0e9fe12010-04-10 10:36:19 -0700891 anon_vma = reusable_anon_vma(near, vma, near);
892 if (anon_vma)
893 return anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894try_prev:
895 /*
896 * It is potentially slow to have to call find_vma_prev here.
897 * But it's only on the first write fault on the vma, not
898 * every time, and we could devise a way to avoid it later
899 * (e.g. stash info in next's anon_vma_node when assigning
900 * an anon_vma, or when trying vma_merge). Another time.
901 */
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200902 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 if (!near)
904 goto none;
905
Linus Torvaldsd0e9fe12010-04-10 10:36:19 -0700906 anon_vma = reusable_anon_vma(near, near, vma);
907 if (anon_vma)
908 return anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909none:
910 /*
911 * There's no absolute need to look only at touching neighbours:
912 * we could search further afield for "compatible" anon_vmas.
913 * But it would probably just be a waste of time searching,
914 * or lead to too many vmas hanging off the same anon_vma.
915 * We're trying to allow mprotect remerging later on,
916 * not trying to minimize memory used for anon_vmas.
917 */
918 return NULL;
919}
920
921#ifdef CONFIG_PROC_FS
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700922void vm_stat_account(struct mm_struct *mm, unsigned long flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 struct file *file, long pages)
924{
925 const unsigned long stack_flags
926 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
927
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 if (file) {
929 mm->shared_vm += pages;
930 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
931 mm->exec_vm += pages;
932 } else if (flags & stack_flags)
933 mm->stack_vm += pages;
934 if (flags & (VM_RESERVED|VM_IO))
935 mm->reserved_vm += pages;
936}
937#endif /* CONFIG_PROC_FS */
938
939/*
Jianjun Kong27f5de72009-09-17 19:26:26 -0700940 * The caller must hold down_write(&current->mm->mmap_sem).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 */
942
ZhenwenXu48aae422009-01-06 14:40:21 -0800943unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 unsigned long len, unsigned long prot,
945 unsigned long flags, unsigned long pgoff)
946{
947 struct mm_struct * mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 struct inode *inode;
949 unsigned int vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 int error;
Miklos Szeredi0165ab42007-07-15 23:38:26 -0700951 unsigned long reqprot = prot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 /*
954 * Does the application expect PROT_READ to imply PROT_EXEC?
955 *
956 * (the exception is when the underlying filesystem is noexec
957 * mounted, in which case we dont add PROT_EXEC.)
958 */
959 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800960 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 prot |= PROT_EXEC;
962
963 if (!len)
964 return -EINVAL;
965
Eric Paris7cd94142007-11-26 18:47:40 -0500966 if (!(flags & MAP_FIXED))
967 addr = round_hint_to_min(addr);
968
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 /* Careful about overflows.. */
970 len = PAGE_ALIGN(len);
Al Viro9206de92009-12-03 15:23:11 -0500971 if (!len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 return -ENOMEM;
973
974 /* offset overflow? */
975 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
976 return -EOVERFLOW;
977
978 /* Too many mappings? */
979 if (mm->map_count > sysctl_max_map_count)
980 return -ENOMEM;
981
982 /* Obtain the address to map to. we verify (or select) it and ensure
983 * that it represents a valid section of the address space.
984 */
985 addr = get_unmapped_area(file, addr, len, pgoff, flags);
986 if (addr & ~PAGE_MASK)
987 return addr;
988
989 /* Do simple checking here so the lower-level routines won't have
990 * to. we assume access permissions have been handled by the open
991 * of the memory object, so we don't do any here.
992 */
993 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
994 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
995
Huang Shijiecdf7b342009-09-21 17:03:36 -0700996 if (flags & MAP_LOCKED)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 if (!can_do_mlock())
998 return -EPERM;
Rik van Rielba470de2008-10-18 20:26:50 -0700999
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 /* mlock MCL_FUTURE? */
1001 if (vm_flags & VM_LOCKED) {
1002 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -07001003 locked = len >> PAGE_SHIFT;
1004 locked += mm->locked_vm;
Jiri Slaby59e99e52010-03-05 13:41:44 -08001005 lock_limit = rlimit(RLIMIT_MEMLOCK);
Chris Wright93ea1d02005-05-01 08:58:38 -07001006 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1008 return -EAGAIN;
1009 }
1010
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001011 inode = file ? file->f_path.dentry->d_inode : NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012
1013 if (file) {
1014 switch (flags & MAP_TYPE) {
1015 case MAP_SHARED:
1016 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1017 return -EACCES;
1018
1019 /*
1020 * Make sure we don't allow writing to an append-only
1021 * file..
1022 */
1023 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1024 return -EACCES;
1025
1026 /*
1027 * Make sure there are no mandatory locks on the file.
1028 */
1029 if (locks_verify_locked(inode))
1030 return -EAGAIN;
1031
1032 vm_flags |= VM_SHARED | VM_MAYSHARE;
1033 if (!(file->f_mode & FMODE_WRITE))
1034 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1035
1036 /* fall through */
1037 case MAP_PRIVATE:
1038 if (!(file->f_mode & FMODE_READ))
1039 return -EACCES;
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001040 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds80c56062006-10-15 14:09:55 -07001041 if (vm_flags & VM_EXEC)
1042 return -EPERM;
1043 vm_flags &= ~VM_MAYEXEC;
1044 }
Linus Torvalds80c56062006-10-15 14:09:55 -07001045
1046 if (!file->f_op || !file->f_op->mmap)
1047 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 break;
1049
1050 default:
1051 return -EINVAL;
1052 }
1053 } else {
1054 switch (flags & MAP_TYPE) {
1055 case MAP_SHARED:
Tejun Heoce363942008-09-03 16:09:47 +02001056 /*
1057 * Ignore pgoff.
1058 */
1059 pgoff = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 vm_flags |= VM_SHARED | VM_MAYSHARE;
1061 break;
1062 case MAP_PRIVATE:
1063 /*
1064 * Set pgoff according to addr for anon_vma.
1065 */
1066 pgoff = addr >> PAGE_SHIFT;
1067 break;
1068 default:
1069 return -EINVAL;
1070 }
1071 }
1072
Eric Parised032182007-06-28 15:55:21 -04001073 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 if (error)
1075 return error;
Eric Parised032182007-06-28 15:55:21 -04001076
Mel Gorman5a6fe122009-02-10 14:02:27 +00001077 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001078}
1079EXPORT_SYMBOL(do_mmap_pgoff);
1080
Hugh Dickins66f0dc42009-12-30 20:17:34 +00001081SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1082 unsigned long, prot, unsigned long, flags,
1083 unsigned long, fd, unsigned long, pgoff)
1084{
1085 struct file *file = NULL;
1086 unsigned long retval = -EBADF;
1087
1088 if (!(flags & MAP_ANONYMOUS)) {
1089 if (unlikely(flags & MAP_HUGETLB))
1090 return -EINVAL;
1091 file = fget(fd);
1092 if (!file)
1093 goto out;
1094 } else if (flags & MAP_HUGETLB) {
1095 struct user_struct *user = NULL;
1096 /*
1097 * VM_NORESERVE is used because the reservations will be
1098 * taken when vm_ops->mmap() is called
1099 * A dummy user value is used because we are not locking
1100 * memory so no accounting is necessary
1101 */
1102 len = ALIGN(len, huge_page_size(&default_hstate));
1103 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1104 &user, HUGETLB_ANONHUGE_INODE);
1105 if (IS_ERR(file))
1106 return PTR_ERR(file);
1107 }
1108
1109 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1110
1111 down_write(&current->mm->mmap_sem);
1112 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1113 up_write(&current->mm->mmap_sem);
1114
1115 if (file)
1116 fput(file);
1117out:
1118 return retval;
1119}
1120
Christoph Hellwiga4679372010-03-10 15:21:15 -08001121#ifdef __ARCH_WANT_SYS_OLD_MMAP
1122struct mmap_arg_struct {
1123 unsigned long addr;
1124 unsigned long len;
1125 unsigned long prot;
1126 unsigned long flags;
1127 unsigned long fd;
1128 unsigned long offset;
1129};
1130
1131SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1132{
1133 struct mmap_arg_struct a;
1134
1135 if (copy_from_user(&a, arg, sizeof(a)))
1136 return -EFAULT;
1137 if (a.offset & ~PAGE_MASK)
1138 return -EINVAL;
1139
1140 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1141 a.offset >> PAGE_SHIFT);
1142}
1143#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1144
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001145/*
1146 * Some shared mappigns will want the pages marked read-only
1147 * to track write events. If so, we'll downgrade vm_page_prot
1148 * to the private version (using protection_map[] without the
1149 * VM_SHARED bit).
1150 */
1151int vma_wants_writenotify(struct vm_area_struct *vma)
1152{
1153 unsigned int vm_flags = vma->vm_flags;
1154
1155 /* If it was private or non-writable, the write bit is already clear */
1156 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1157 return 0;
1158
1159 /* The backer wishes to know when pages are first written to? */
1160 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1161 return 1;
1162
1163 /* The open routine did something to the protections already? */
1164 if (pgprot_val(vma->vm_page_prot) !=
Coly Li3ed75eb2007-10-18 23:39:15 -07001165 pgprot_val(vm_get_page_prot(vm_flags)))
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001166 return 0;
1167
1168 /* Specialty mapping? */
1169 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1170 return 0;
1171
1172 /* Can the mapping track the dirty pages? */
1173 return vma->vm_file && vma->vm_file->f_mapping &&
1174 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1175}
1176
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001177/*
1178 * We account for memory if it's a private writeable mapping,
Mel Gorman5a6fe122009-02-10 14:02:27 +00001179 * not hugepages and VM_NORESERVE wasn't set.
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001180 */
Mel Gorman5a6fe122009-02-10 14:02:27 +00001181static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001182{
Mel Gorman5a6fe122009-02-10 14:02:27 +00001183 /*
1184 * hugetlb has its own accounting separate from the core VM
1185 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1186 */
1187 if (file && is_file_hugepages(file))
1188 return 0;
1189
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001190 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1191}
1192
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001193unsigned long mmap_region(struct file *file, unsigned long addr,
1194 unsigned long len, unsigned long flags,
Mel Gorman5a6fe122009-02-10 14:02:27 +00001195 unsigned int vm_flags, unsigned long pgoff)
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001196{
1197 struct mm_struct *mm = current->mm;
1198 struct vm_area_struct *vma, *prev;
1199 int correct_wcount = 0;
1200 int error;
1201 struct rb_node **rb_link, *rb_parent;
1202 unsigned long charged = 0;
1203 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1204
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 /* Clear old maps */
1206 error = -ENOMEM;
1207munmap_back:
1208 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1209 if (vma && vma->vm_start < addr + len) {
1210 if (do_munmap(mm, addr, len))
1211 return -ENOMEM;
1212 goto munmap_back;
1213 }
1214
1215 /* Check against address space limit. */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001216 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 return -ENOMEM;
1218
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001219 /*
1220 * Set 'VM_NORESERVE' if we should not account for the
Mel Gorman5a6fe122009-02-10 14:02:27 +00001221 * memory use of this mapping.
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001222 */
Mel Gorman5a6fe122009-02-10 14:02:27 +00001223 if ((flags & MAP_NORESERVE)) {
1224 /* We honor MAP_NORESERVE if allowed to overcommit */
1225 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1226 vm_flags |= VM_NORESERVE;
1227
1228 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1229 if (file && is_file_hugepages(file))
1230 vm_flags |= VM_NORESERVE;
1231 }
Andy Whitcroftcdfd4322008-07-23 21:27:28 -07001232
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001233 /*
1234 * Private writable mapping: check memory availability
1235 */
Mel Gorman5a6fe122009-02-10 14:02:27 +00001236 if (accountable_mapping(file, vm_flags)) {
Linus Torvaldsfc8744a2009-01-31 15:08:56 -08001237 charged = len >> PAGE_SHIFT;
1238 if (security_vm_enough_memory(charged))
1239 return -ENOMEM;
1240 vm_flags |= VM_ACCOUNT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 }
1242
1243 /*
Linus Torvaldsde33c8d2009-01-29 17:46:42 -08001244 * Can we just expand an old mapping?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 */
Linus Torvaldsde33c8d2009-01-29 17:46:42 -08001246 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1247 if (vma)
1248 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
1250 /*
1251 * Determine the object being mapped and call the appropriate
1252 * specific mapper. the address has already been validated, but
1253 * not unmapped, but the maps are removed from the list.
1254 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08001255 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 if (!vma) {
1257 error = -ENOMEM;
1258 goto unacct_error;
1259 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
1261 vma->vm_mm = mm;
1262 vma->vm_start = addr;
1263 vma->vm_end = addr + len;
1264 vma->vm_flags = vm_flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07001265 vma->vm_page_prot = vm_get_page_prot(vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 vma->vm_pgoff = pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -08001267 INIT_LIST_HEAD(&vma->anon_vma_chain);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268
1269 if (file) {
1270 error = -EINVAL;
1271 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1272 goto free_vma;
1273 if (vm_flags & VM_DENYWRITE) {
1274 error = deny_write_access(file);
1275 if (error)
1276 goto free_vma;
1277 correct_wcount = 1;
1278 }
1279 vma->vm_file = file;
1280 get_file(file);
1281 error = file->f_op->mmap(file, vma);
1282 if (error)
1283 goto unmap_and_free_vma;
Matt Helsley925d1c42008-04-29 01:01:36 -07001284 if (vm_flags & VM_EXECUTABLE)
1285 added_exe_file_vma(mm);
Huang Shijief8dbf0a72009-09-21 17:03:41 -07001286
1287 /* Can addr have changed??
1288 *
1289 * Answer: Yes, several device drivers can do it in their
1290 * f_op->mmap method. -DaveM
1291 */
1292 addr = vma->vm_start;
1293 pgoff = vma->vm_pgoff;
1294 vm_flags = vma->vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 } else if (vm_flags & VM_SHARED) {
1296 error = shmem_zero_setup(vma);
1297 if (error)
1298 goto free_vma;
1299 }
1300
Magnus Dammc9d0bf22009-12-14 17:59:49 -08001301 if (vma_wants_writenotify(vma)) {
1302 pgprot_t pprot = vma->vm_page_prot;
1303
1304 /* Can vma->vm_page_prot have changed??
1305 *
1306 * Answer: Yes, drivers may have changed it in their
1307 * f_op->mmap method.
1308 *
1309 * Ensures that vmas marked as uncached stay that way.
1310 */
Hugh Dickins1ddd4392007-10-22 20:45:12 -07001311 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
Magnus Dammc9d0bf22009-12-14 17:59:49 -08001312 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1313 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1314 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001315
Linus Torvaldsde33c8d2009-01-29 17:46:42 -08001316 vma_link(mm, vma, prev, rb_link, rb_parent);
1317 file = vma->vm_file;
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001318
1319 /* Once vma denies write, undo our temporary denial count */
1320 if (correct_wcount)
1321 atomic_inc(&inode->i_writecount);
1322out:
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001323 perf_event_mmap(vma);
Peter Zijlstra0a4a9392009-03-30 19:07:05 +02001324
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 mm->total_vm += len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001326 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 if (vm_flags & VM_LOCKED) {
KOSAKI Motohiro06f9d8c2010-03-05 13:41:43 -08001328 if (!mlock_vma_pages_range(vma, addr, addr + len))
1329 mm->locked_vm += (len >> PAGE_SHIFT);
Rik van Rielba470de2008-10-18 20:26:50 -07001330 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
Nick Piggin54cb8822007-07-19 01:46:59 -07001331 make_pages_present(addr, addr + len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 return addr;
1333
1334unmap_and_free_vma:
1335 if (correct_wcount)
1336 atomic_inc(&inode->i_writecount);
1337 vma->vm_file = NULL;
1338 fput(file);
1339
1340 /* Undo any partial mapping done by a device driver. */
Hugh Dickinse0da3822005-04-19 13:29:15 -07001341 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1342 charged = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343free_vma:
1344 kmem_cache_free(vm_area_cachep, vma);
1345unacct_error:
1346 if (charged)
1347 vm_unacct_memory(charged);
1348 return error;
1349}
1350
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351/* Get an address range which is currently unmapped.
1352 * For shmat() with addr=0.
1353 *
1354 * Ugly calling convention alert:
1355 * Return value with the low bits set means error value,
1356 * ie
1357 * if (ret & ~PAGE_MASK)
1358 * error = ret;
1359 *
1360 * This function "knows" that -ENOMEM has the bits set.
1361 */
1362#ifndef HAVE_ARCH_UNMAPPED_AREA
1363unsigned long
1364arch_get_unmapped_area(struct file *filp, unsigned long addr,
1365 unsigned long len, unsigned long pgoff, unsigned long flags)
1366{
1367 struct mm_struct *mm = current->mm;
1368 struct vm_area_struct *vma;
1369 unsigned long start_addr;
1370
1371 if (len > TASK_SIZE)
1372 return -ENOMEM;
1373
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001374 if (flags & MAP_FIXED)
1375 return addr;
1376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 if (addr) {
1378 addr = PAGE_ALIGN(addr);
1379 vma = find_vma(mm, addr);
1380 if (TASK_SIZE - len >= addr &&
1381 (!vma || addr + len <= vma->vm_start))
1382 return addr;
1383 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001384 if (len > mm->cached_hole_size) {
1385 start_addr = addr = mm->free_area_cache;
1386 } else {
1387 start_addr = addr = TASK_UNMAPPED_BASE;
1388 mm->cached_hole_size = 0;
1389 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
1391full_search:
1392 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1393 /* At this point: (!vma || addr < vma->vm_end). */
1394 if (TASK_SIZE - len < addr) {
1395 /*
1396 * Start a new search - just in case we missed
1397 * some holes.
1398 */
1399 if (start_addr != TASK_UNMAPPED_BASE) {
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001400 addr = TASK_UNMAPPED_BASE;
1401 start_addr = addr;
1402 mm->cached_hole_size = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 goto full_search;
1404 }
1405 return -ENOMEM;
1406 }
1407 if (!vma || addr + len <= vma->vm_start) {
1408 /*
1409 * Remember the place where we stopped the search:
1410 */
1411 mm->free_area_cache = addr + len;
1412 return addr;
1413 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001414 if (addr + mm->cached_hole_size < vma->vm_start)
1415 mm->cached_hole_size = vma->vm_start - addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 addr = vma->vm_end;
1417 }
1418}
1419#endif
1420
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001421void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422{
1423 /*
1424 * Is this a new hole at the lowest possible address?
1425 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001426 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1427 mm->free_area_cache = addr;
1428 mm->cached_hole_size = ~0UL;
1429 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430}
1431
1432/*
1433 * This mmap-allocator allocates new areas top-down from below the
1434 * stack's low limit (the base):
1435 */
1436#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1437unsigned long
1438arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1439 const unsigned long len, const unsigned long pgoff,
1440 const unsigned long flags)
1441{
1442 struct vm_area_struct *vma;
1443 struct mm_struct *mm = current->mm;
1444 unsigned long addr = addr0;
1445
1446 /* requested length too big for entire address space */
1447 if (len > TASK_SIZE)
1448 return -ENOMEM;
1449
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001450 if (flags & MAP_FIXED)
1451 return addr;
1452
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 /* requesting a specific address */
1454 if (addr) {
1455 addr = PAGE_ALIGN(addr);
1456 vma = find_vma(mm, addr);
1457 if (TASK_SIZE - len >= addr &&
1458 (!vma || addr + len <= vma->vm_start))
1459 return addr;
1460 }
1461
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001462 /* check if free_area_cache is useful for us */
1463 if (len <= mm->cached_hole_size) {
1464 mm->cached_hole_size = 0;
1465 mm->free_area_cache = mm->mmap_base;
1466 }
1467
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 /* either no address requested or can't fit in requested address hole */
1469 addr = mm->free_area_cache;
1470
1471 /* make sure it can fit in the remaining address space */
Linus Torvalds49a43872005-05-18 15:39:33 -07001472 if (addr > len) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 vma = find_vma(mm, addr-len);
1474 if (!vma || addr <= vma->vm_start)
1475 /* remember the address as a hint for next time */
1476 return (mm->free_area_cache = addr-len);
1477 }
1478
Chris Wright73219d12005-06-21 17:14:52 -07001479 if (mm->mmap_base < len)
1480 goto bottomup;
1481
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482 addr = mm->mmap_base-len;
1483
1484 do {
1485 /*
1486 * Lookup failure means no vma is above this address,
1487 * else if new region fits below vma->vm_start,
1488 * return with success:
1489 */
1490 vma = find_vma(mm, addr);
1491 if (!vma || addr+len <= vma->vm_start)
1492 /* remember the address as a hint for next time */
1493 return (mm->free_area_cache = addr);
1494
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001495 /* remember the largest hole we saw so far */
1496 if (addr + mm->cached_hole_size < vma->vm_start)
1497 mm->cached_hole_size = vma->vm_start - addr;
1498
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 /* try just below the current vma->vm_start */
1500 addr = vma->vm_start-len;
Linus Torvalds49a43872005-05-18 15:39:33 -07001501 } while (len < vma->vm_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502
Chris Wright73219d12005-06-21 17:14:52 -07001503bottomup:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 /*
1505 * A failed mmap() very likely causes application failure,
1506 * so fall back to the bottom-up function here. This scenario
1507 * can happen with large stack limits and large mmap()
1508 * allocations.
1509 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001510 mm->cached_hole_size = ~0UL;
1511 mm->free_area_cache = TASK_UNMAPPED_BASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1513 /*
1514 * Restore the topdown base:
1515 */
1516 mm->free_area_cache = mm->mmap_base;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001517 mm->cached_hole_size = ~0UL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518
1519 return addr;
1520}
1521#endif
1522
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001523void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524{
1525 /*
1526 * Is this a new hole at the highest possible address?
1527 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001528 if (addr > mm->free_area_cache)
1529 mm->free_area_cache = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
1531 /* dont allow allocations above current base */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001532 if (mm->free_area_cache > mm->mmap_base)
1533 mm->free_area_cache = mm->mmap_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534}
1535
1536unsigned long
1537get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1538 unsigned long pgoff, unsigned long flags)
1539{
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001540 unsigned long (*get_area)(struct file *, unsigned long,
1541 unsigned long, unsigned long, unsigned long);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542
Al Viro9206de92009-12-03 15:23:11 -05001543 unsigned long error = arch_mmap_check(addr, len, flags);
1544 if (error)
1545 return error;
1546
1547 /* Careful about overflows.. */
1548 if (len > TASK_SIZE)
1549 return -ENOMEM;
1550
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001551 get_area = current->mm->get_unmapped_area;
1552 if (file && file->f_op && file->f_op->get_unmapped_area)
1553 get_area = file->f_op->get_unmapped_area;
1554 addr = get_area(file, addr, len, pgoff, flags);
1555 if (IS_ERR_VALUE(addr))
1556 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557
Linus Torvalds07ab67c2005-05-19 22:43:37 -07001558 if (addr > TASK_SIZE - len)
1559 return -ENOMEM;
1560 if (addr & ~PAGE_MASK)
1561 return -EINVAL;
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001562
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -08001563 return arch_rebalance_pgtables(addr, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564}
1565
1566EXPORT_SYMBOL(get_unmapped_area);
1567
1568/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
ZhenwenXu48aae422009-01-06 14:40:21 -08001569struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570{
1571 struct vm_area_struct *vma = NULL;
1572
1573 if (mm) {
1574 /* Check the cache first. */
1575 /* (Cache hit rate is typically around 35%.) */
1576 vma = mm->mmap_cache;
1577 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1578 struct rb_node * rb_node;
1579
1580 rb_node = mm->mm_rb.rb_node;
1581 vma = NULL;
1582
1583 while (rb_node) {
1584 struct vm_area_struct * vma_tmp;
1585
1586 vma_tmp = rb_entry(rb_node,
1587 struct vm_area_struct, vm_rb);
1588
1589 if (vma_tmp->vm_end > addr) {
1590 vma = vma_tmp;
1591 if (vma_tmp->vm_start <= addr)
1592 break;
1593 rb_node = rb_node->rb_left;
1594 } else
1595 rb_node = rb_node->rb_right;
1596 }
1597 if (vma)
1598 mm->mmap_cache = vma;
1599 }
1600 }
1601 return vma;
1602}
1603
1604EXPORT_SYMBOL(find_vma);
1605
1606/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1607struct vm_area_struct *
1608find_vma_prev(struct mm_struct *mm, unsigned long addr,
1609 struct vm_area_struct **pprev)
1610{
1611 struct vm_area_struct *vma = NULL, *prev = NULL;
ZhenwenXu48aae422009-01-06 14:40:21 -08001612 struct rb_node *rb_node;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 if (!mm)
1614 goto out;
1615
1616 /* Guard against addr being lower than the first VMA */
1617 vma = mm->mmap;
1618
1619 /* Go through the RB tree quickly. */
1620 rb_node = mm->mm_rb.rb_node;
1621
1622 while (rb_node) {
1623 struct vm_area_struct *vma_tmp;
1624 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1625
1626 if (addr < vma_tmp->vm_end) {
1627 rb_node = rb_node->rb_left;
1628 } else {
1629 prev = vma_tmp;
1630 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1631 break;
1632 rb_node = rb_node->rb_right;
1633 }
1634 }
1635
1636out:
1637 *pprev = prev;
1638 return prev ? prev->vm_next : vma;
1639}
1640
1641/*
1642 * Verify that the stack growth is acceptable and
1643 * update accounting. This is shared with both the
1644 * grow-up and grow-down cases.
1645 */
ZhenwenXu48aae422009-01-06 14:40:21 -08001646static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647{
1648 struct mm_struct *mm = vma->vm_mm;
1649 struct rlimit *rlim = current->signal->rlim;
Adam Litke0d59a012007-01-30 14:35:39 -08001650 unsigned long new_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
1652 /* address space limit tests */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001653 if (!may_expand_vm(mm, grow))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654 return -ENOMEM;
1655
1656 /* Stack limit test */
Jiri Slaby59e99e52010-03-05 13:41:44 -08001657 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 return -ENOMEM;
1659
1660 /* mlock limit tests */
1661 if (vma->vm_flags & VM_LOCKED) {
1662 unsigned long locked;
1663 unsigned long limit;
1664 locked = mm->locked_vm + grow;
Jiri Slaby59e99e52010-03-05 13:41:44 -08001665 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1666 limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 if (locked > limit && !capable(CAP_IPC_LOCK))
1668 return -ENOMEM;
1669 }
1670
Adam Litke0d59a012007-01-30 14:35:39 -08001671 /* Check to ensure the stack will not grow into a hugetlb-only region */
1672 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1673 vma->vm_end - size;
1674 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1675 return -EFAULT;
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 /*
1678 * Overcommit.. This must be the final test, as it will
1679 * update security statistics.
1680 */
Hugh Dickins05fa1992009-04-16 21:58:12 +01001681 if (security_vm_enough_memory_mm(mm, grow))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 return -ENOMEM;
1683
1684 /* Ok, everything looks good - let it rip */
1685 mm->total_vm += grow;
1686 if (vma->vm_flags & VM_LOCKED)
1687 mm->locked_vm += grow;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001688 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 return 0;
1690}
1691
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001692#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693/*
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001694 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1695 * vma is the last one with address > vma->vm_end. Have to extend vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 */
Matthew Wilcox9ab88512005-11-18 16:16:42 -05001697#ifndef CONFIG_IA64
Denys Vlasenkocb8f4882008-10-18 20:27:01 -07001698static
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001699#endif
1700int expand_upwards(struct vm_area_struct *vma, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701{
1702 int error;
1703
1704 if (!(vma->vm_flags & VM_GROWSUP))
1705 return -EFAULT;
1706
1707 /*
1708 * We must make sure the anon_vma is allocated
1709 * so that the anon_vma locking is not a noop.
1710 */
1711 if (unlikely(anon_vma_prepare(vma)))
1712 return -ENOMEM;
1713 anon_vma_lock(vma);
1714
1715 /*
1716 * vma->vm_start/vm_end cannot change under us because the caller
1717 * is required to hold the mmap_sem in read mode. We need the
1718 * anon_vma lock to serialize against concurrent expand_stacks.
Helge Deller06b32f32006-12-19 19:28:33 +01001719 * Also guard against wrapping around to address 0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 */
Helge Deller06b32f32006-12-19 19:28:33 +01001721 if (address < PAGE_ALIGN(address+4))
1722 address = PAGE_ALIGN(address+4);
1723 else {
1724 anon_vma_unlock(vma);
1725 return -ENOMEM;
1726 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 error = 0;
1728
1729 /* Somebody else might have raced and expanded it already */
1730 if (address > vma->vm_end) {
1731 unsigned long size, grow;
1732
1733 size = address - vma->vm_start;
1734 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1735
1736 error = acct_stack_growth(vma, size, grow);
1737 if (!error)
1738 vma->vm_end = address;
1739 }
1740 anon_vma_unlock(vma);
1741 return error;
1742}
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001743#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1744
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745/*
1746 * vma is the first one with address < vma->vm_start. Have to extend vma.
1747 */
Denys Vlasenkocb8f4882008-10-18 20:27:01 -07001748static int expand_downwards(struct vm_area_struct *vma,
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001749 unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750{
1751 int error;
1752
1753 /*
1754 * We must make sure the anon_vma is allocated
1755 * so that the anon_vma locking is not a noop.
1756 */
1757 if (unlikely(anon_vma_prepare(vma)))
1758 return -ENOMEM;
Eric Paris88694772007-11-26 18:47:26 -05001759
1760 address &= PAGE_MASK;
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01001761 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
Eric Paris88694772007-11-26 18:47:26 -05001762 if (error)
1763 return error;
1764
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 anon_vma_lock(vma);
1766
1767 /*
1768 * vma->vm_start/vm_end cannot change under us because the caller
1769 * is required to hold the mmap_sem in read mode. We need the
1770 * anon_vma lock to serialize against concurrent expand_stacks.
1771 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772
1773 /* Somebody else might have raced and expanded it already */
1774 if (address < vma->vm_start) {
1775 unsigned long size, grow;
1776
1777 size = vma->vm_end - address;
1778 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1779
1780 error = acct_stack_growth(vma, size, grow);
1781 if (!error) {
1782 vma->vm_start = address;
1783 vma->vm_pgoff -= grow;
1784 }
1785 }
1786 anon_vma_unlock(vma);
1787 return error;
1788}
1789
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001790int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1791{
1792 return expand_downwards(vma, address);
1793}
1794
1795#ifdef CONFIG_STACK_GROWSUP
1796int expand_stack(struct vm_area_struct *vma, unsigned long address)
1797{
1798 return expand_upwards(vma, address);
1799}
1800
1801struct vm_area_struct *
1802find_extend_vma(struct mm_struct *mm, unsigned long addr)
1803{
1804 struct vm_area_struct *vma, *prev;
1805
1806 addr &= PAGE_MASK;
1807 vma = find_vma_prev(mm, addr, &prev);
1808 if (vma && (vma->vm_start <= addr))
1809 return vma;
Denys Vlasenko1c127182008-11-12 01:24:41 +01001810 if (!prev || expand_stack(prev, addr))
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001811 return NULL;
Rik van Rielba470de2008-10-18 20:26:50 -07001812 if (prev->vm_flags & VM_LOCKED) {
KOSAKI Motohiroc58267c2010-03-05 13:41:43 -08001813 mlock_vma_pages_range(prev, addr, prev->vm_end);
Rik van Rielba470de2008-10-18 20:26:50 -07001814 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001815 return prev;
1816}
1817#else
1818int expand_stack(struct vm_area_struct *vma, unsigned long address)
1819{
1820 return expand_downwards(vma, address);
1821}
1822
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823struct vm_area_struct *
1824find_extend_vma(struct mm_struct * mm, unsigned long addr)
1825{
1826 struct vm_area_struct * vma;
1827 unsigned long start;
1828
1829 addr &= PAGE_MASK;
1830 vma = find_vma(mm,addr);
1831 if (!vma)
1832 return NULL;
1833 if (vma->vm_start <= addr)
1834 return vma;
1835 if (!(vma->vm_flags & VM_GROWSDOWN))
1836 return NULL;
1837 start = vma->vm_start;
1838 if (expand_stack(vma, addr))
1839 return NULL;
Rik van Rielba470de2008-10-18 20:26:50 -07001840 if (vma->vm_flags & VM_LOCKED) {
KOSAKI Motohiroc58267c2010-03-05 13:41:43 -08001841 mlock_vma_pages_range(vma, addr, start);
Rik van Rielba470de2008-10-18 20:26:50 -07001842 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 return vma;
1844}
1845#endif
1846
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847/*
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001848 * Ok - we have the memory areas we should free on the vma list,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 * so release them, and do the vma updates.
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001850 *
1851 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001853static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854{
Hugh Dickins365e9c872005-10-29 18:16:18 -07001855 /* Update high watermark before we lower total_vm */
1856 update_hiwater_vm(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 do {
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001858 long nrpages = vma_pages(vma);
1859
1860 mm->total_vm -= nrpages;
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001861 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07001862 vma = remove_vma(vma);
Hugh Dickins146425a2005-04-19 13:29:18 -07001863 } while (vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001864 validate_mm(mm);
1865}
1866
1867/*
1868 * Get rid of page table information in the indicated region.
1869 *
Paolo 'Blaisorblade' Giarrussof10df682005-09-21 09:55:37 -07001870 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 */
1872static void unmap_region(struct mm_struct *mm,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001873 struct vm_area_struct *vma, struct vm_area_struct *prev,
1874 unsigned long start, unsigned long end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875{
Hugh Dickinse0da3822005-04-19 13:29:15 -07001876 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 struct mmu_gather *tlb;
1878 unsigned long nr_accounted = 0;
1879
1880 lru_add_drain();
1881 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickins365e9c872005-10-29 18:16:18 -07001882 update_hiwater_rss(mm);
Hugh Dickins508034a2005-10-29 18:16:30 -07001883 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884 vm_unacct_memory(nr_accounted);
Jan Beulich42b77722008-07-23 21:27:10 -07001885 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001886 next? next->vm_start: 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887 tlb_finish_mmu(tlb, start, end);
1888}
1889
1890/*
1891 * Create a list of vma's touched by the unmap, removing them from the mm's
1892 * vma list as we go..
1893 */
1894static void
1895detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1896 struct vm_area_struct *prev, unsigned long end)
1897{
1898 struct vm_area_struct **insertion_point;
1899 struct vm_area_struct *tail_vma = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001900 unsigned long addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901
1902 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1903 do {
1904 rb_erase(&vma->vm_rb, &mm->mm_rb);
1905 mm->map_count--;
1906 tail_vma = vma;
1907 vma = vma->vm_next;
1908 } while (vma && vma->vm_start < end);
1909 *insertion_point = vma;
1910 tail_vma->vm_next = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001911 if (mm->unmap_area == arch_unmap_area)
1912 addr = prev ? prev->vm_end : mm->mmap_base;
1913 else
1914 addr = vma ? vma->vm_start : mm->mmap_base;
1915 mm->unmap_area(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916 mm->mmap_cache = NULL; /* Kill the cache. */
1917}
1918
1919/*
KOSAKI Motohiro659ace52009-12-14 17:57:56 -08001920 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1921 * munmap path where it doesn't make sense to fail.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 */
KOSAKI Motohiro659ace52009-12-14 17:57:56 -08001923static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 unsigned long addr, int new_below)
1925{
1926 struct mempolicy *pol;
1927 struct vm_area_struct *new;
Rik van Riel5beb4932010-03-05 13:42:07 -08001928 int err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929
Andi Kleena5516432008-07-23 21:27:41 -07001930 if (is_vm_hugetlb_page(vma) && (addr &
1931 ~(huge_page_mask(hstate_vma(vma)))))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 return -EINVAL;
1933
Christoph Lametere94b1762006-12-06 20:33:17 -08001934 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 if (!new)
Rik van Riel5beb4932010-03-05 13:42:07 -08001936 goto out_err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
1938 /* most fields are the same, copy all, and then fixup */
1939 *new = *vma;
1940
Rik van Riel5beb4932010-03-05 13:42:07 -08001941 INIT_LIST_HEAD(&new->anon_vma_chain);
1942
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 if (new_below)
1944 new->vm_end = addr;
1945 else {
1946 new->vm_start = addr;
1947 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1948 }
1949
Lee Schermerhorn846a16b2008-04-28 02:13:09 -07001950 pol = mpol_dup(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 if (IS_ERR(pol)) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001952 err = PTR_ERR(pol);
1953 goto out_free_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 }
1955 vma_set_policy(new, pol);
1956
Rik van Riel5beb4932010-03-05 13:42:07 -08001957 if (anon_vma_clone(new, vma))
1958 goto out_free_mpol;
1959
Matt Helsley925d1c42008-04-29 01:01:36 -07001960 if (new->vm_file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 get_file(new->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -07001962 if (vma->vm_flags & VM_EXECUTABLE)
1963 added_exe_file_vma(mm);
1964 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965
1966 if (new->vm_ops && new->vm_ops->open)
1967 new->vm_ops->open(new);
1968
1969 if (new_below)
Rik van Riel5beb4932010-03-05 13:42:07 -08001970 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1972 else
Rik van Riel5beb4932010-03-05 13:42:07 -08001973 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974
Rik van Riel5beb4932010-03-05 13:42:07 -08001975 /* Success. */
1976 if (!err)
1977 return 0;
1978
1979 /* Clean everything up if vma_adjust failed. */
Rik van Riel58927532010-04-26 12:33:03 -04001980 if (new->vm_ops && new->vm_ops->close)
1981 new->vm_ops->close(new);
Rik van Riel5beb4932010-03-05 13:42:07 -08001982 if (new->vm_file) {
1983 if (vma->vm_flags & VM_EXECUTABLE)
1984 removed_exe_file_vma(mm);
1985 fput(new->vm_file);
1986 }
1987 out_free_mpol:
1988 mpol_put(pol);
1989 out_free_vma:
1990 kmem_cache_free(vm_area_cachep, new);
1991 out_err:
1992 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993}
1994
KOSAKI Motohiro659ace52009-12-14 17:57:56 -08001995/*
1996 * Split a vma into two pieces at address 'addr', a new vma is allocated
1997 * either for the first part or the tail.
1998 */
1999int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2000 unsigned long addr, int new_below)
2001{
2002 if (mm->map_count >= sysctl_max_map_count)
2003 return -ENOMEM;
2004
2005 return __split_vma(mm, vma, addr, new_below);
2006}
2007
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008/* Munmap is split into 2 main parts -- this part which finds
2009 * what needs doing, and the areas themselves, which do the
2010 * work. This now handles partial unmappings.
2011 * Jeremy Fitzhardinge <jeremy@goop.org>
2012 */
2013int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2014{
2015 unsigned long end;
Hugh Dickins146425a2005-04-19 13:29:18 -07002016 struct vm_area_struct *vma, *prev, *last;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017
2018 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2019 return -EINVAL;
2020
2021 if ((len = PAGE_ALIGN(len)) == 0)
2022 return -EINVAL;
2023
2024 /* Find the first overlapping VMA */
Hugh Dickins146425a2005-04-19 13:29:18 -07002025 vma = find_vma_prev(mm, start, &prev);
2026 if (!vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027 return 0;
Hugh Dickins146425a2005-04-19 13:29:18 -07002028 /* we have start < vma->vm_end */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002029
2030 /* if it doesn't overlap, we have nothing.. */
2031 end = start + len;
Hugh Dickins146425a2005-04-19 13:29:18 -07002032 if (vma->vm_start >= end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 return 0;
2034
2035 /*
2036 * If we need to split any vma, do it now to save pain later.
2037 *
2038 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2039 * unmapped vm_area_struct will remain in use: so lower split_vma
2040 * places tmp vma above, and higher split_vma places tmp vma below.
2041 */
Hugh Dickins146425a2005-04-19 13:29:18 -07002042 if (start > vma->vm_start) {
KOSAKI Motohiro659ace52009-12-14 17:57:56 -08002043 int error;
2044
2045 /*
2046 * Make sure that map_count on return from munmap() will
2047 * not exceed its limit; but let map_count go just above
2048 * its limit temporarily, to help free resources as expected.
2049 */
2050 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2051 return -ENOMEM;
2052
2053 error = __split_vma(mm, vma, start, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054 if (error)
2055 return error;
Hugh Dickins146425a2005-04-19 13:29:18 -07002056 prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 }
2058
2059 /* Does it split the last one? */
2060 last = find_vma(mm, end);
2061 if (last && end > last->vm_start) {
KOSAKI Motohiro659ace52009-12-14 17:57:56 -08002062 int error = __split_vma(mm, last, end, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 if (error)
2064 return error;
2065 }
Hugh Dickins146425a2005-04-19 13:29:18 -07002066 vma = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067
2068 /*
Rik van Rielba470de2008-10-18 20:26:50 -07002069 * unlock any mlock()ed ranges before detaching vmas
2070 */
2071 if (mm->locked_vm) {
2072 struct vm_area_struct *tmp = vma;
2073 while (tmp && tmp->vm_start < end) {
2074 if (tmp->vm_flags & VM_LOCKED) {
2075 mm->locked_vm -= vma_pages(tmp);
2076 munlock_vma_pages_all(tmp);
2077 }
2078 tmp = tmp->vm_next;
2079 }
2080 }
2081
2082 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083 * Remove the vma's, and unmap the actual pages
2084 */
Hugh Dickins146425a2005-04-19 13:29:18 -07002085 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2086 unmap_region(mm, vma, prev, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087
2088 /* Fix up all other VM information */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07002089 remove_vma_list(mm, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090
2091 return 0;
2092}
2093
2094EXPORT_SYMBOL(do_munmap);
2095
Heiko Carstens6a6160a2009-01-14 14:14:15 +01002096SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097{
2098 int ret;
2099 struct mm_struct *mm = current->mm;
2100
2101 profile_munmap(addr);
2102
2103 down_write(&mm->mmap_sem);
2104 ret = do_munmap(mm, addr, len);
2105 up_write(&mm->mmap_sem);
2106 return ret;
2107}
2108
2109static inline void verify_mm_writelocked(struct mm_struct *mm)
2110{
Paul E. McKenneya241ec62005-10-30 15:03:12 -08002111#ifdef CONFIG_DEBUG_VM
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2113 WARN_ON(1);
2114 up_read(&mm->mmap_sem);
2115 }
2116#endif
2117}
2118
2119/*
2120 * this is really a simplified "do_mmap". it only handles
2121 * anonymous maps. eventually we may be able to do some
2122 * brk-specific accounting here.
2123 */
2124unsigned long do_brk(unsigned long addr, unsigned long len)
2125{
2126 struct mm_struct * mm = current->mm;
2127 struct vm_area_struct * vma, * prev;
2128 unsigned long flags;
2129 struct rb_node ** rb_link, * rb_parent;
2130 pgoff_t pgoff = addr >> PAGE_SHIFT;
Kirill Korotaev3a459752006-09-07 14:17:04 +04002131 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132
2133 len = PAGE_ALIGN(len);
2134 if (!len)
2135 return addr;
2136
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01002137 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
Eric Paris5a211a52007-12-04 11:06:55 -05002138 if (error)
2139 return error;
2140
Kirill Korotaev3a459752006-09-07 14:17:04 +04002141 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2142
Al Viro2c6a10162009-12-03 19:40:46 -05002143 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2144 if (error & ~PAGE_MASK)
Kirill Korotaev3a459752006-09-07 14:17:04 +04002145 return error;
2146
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147 /*
2148 * mlock MCL_FUTURE?
2149 */
2150 if (mm->def_flags & VM_LOCKED) {
2151 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -07002152 locked = len >> PAGE_SHIFT;
2153 locked += mm->locked_vm;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002154 lock_limit = rlimit(RLIMIT_MEMLOCK);
Chris Wright93ea1d02005-05-01 08:58:38 -07002155 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2157 return -EAGAIN;
2158 }
2159
2160 /*
2161 * mm->mmap_sem is required to protect against another thread
2162 * changing the mappings in case we sleep.
2163 */
2164 verify_mm_writelocked(mm);
2165
2166 /*
2167 * Clear old maps. this also does some error checking for us
2168 */
2169 munmap_back:
2170 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2171 if (vma && vma->vm_start < addr + len) {
2172 if (do_munmap(mm, addr, len))
2173 return -ENOMEM;
2174 goto munmap_back;
2175 }
2176
2177 /* Check against address space limits *after* clearing old maps... */
akpm@osdl.org119f6572005-05-01 08:58:35 -07002178 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 return -ENOMEM;
2180
2181 if (mm->map_count > sysctl_max_map_count)
2182 return -ENOMEM;
2183
2184 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2185 return -ENOMEM;
2186
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187 /* Can we just expand an old private anonymous mapping? */
Rik van Rielba470de2008-10-18 20:26:50 -07002188 vma = vma_merge(mm, prev, addr, addr + len, flags,
2189 NULL, NULL, pgoff, NULL);
2190 if (vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 goto out;
2192
2193 /*
2194 * create a vma struct for an anonymous mapping
2195 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08002196 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 if (!vma) {
2198 vm_unacct_memory(len >> PAGE_SHIFT);
2199 return -ENOMEM;
2200 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201
Rik van Riel5beb4932010-03-05 13:42:07 -08002202 INIT_LIST_HEAD(&vma->anon_vma_chain);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 vma->vm_mm = mm;
2204 vma->vm_start = addr;
2205 vma->vm_end = addr + len;
2206 vma->vm_pgoff = pgoff;
2207 vma->vm_flags = flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07002208 vma->vm_page_prot = vm_get_page_prot(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209 vma_link(mm, vma, prev, rb_link, rb_parent);
2210out:
2211 mm->total_vm += len >> PAGE_SHIFT;
2212 if (flags & VM_LOCKED) {
Rik van Rielba470de2008-10-18 20:26:50 -07002213 if (!mlock_vma_pages_range(vma, addr, addr + len))
2214 mm->locked_vm += (len >> PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215 }
2216 return addr;
2217}
2218
2219EXPORT_SYMBOL(do_brk);
2220
2221/* Release all mmaps. */
2222void exit_mmap(struct mm_struct *mm)
2223{
2224 struct mmu_gather *tlb;
Rik van Rielba470de2008-10-18 20:26:50 -07002225 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002226 unsigned long nr_accounted = 0;
Hugh Dickinsee39b372005-04-19 13:29:15 -07002227 unsigned long end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +02002229 /* mm's last user has gone, and its about to be pulled down */
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07002230 mmu_notifier_release(mm);
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +02002231
Rik van Rielba470de2008-10-18 20:26:50 -07002232 if (mm->locked_vm) {
2233 vma = mm->mmap;
2234 while (vma) {
2235 if (vma->vm_flags & VM_LOCKED)
2236 munlock_vma_pages_all(vma);
2237 vma = vma->vm_next;
2238 }
2239 }
Jeremy Fitzhardinge9480c532009-02-11 13:04:41 -08002240
2241 arch_exit_mmap(mm);
2242
Rik van Rielba470de2008-10-18 20:26:50 -07002243 vma = mm->mmap;
Jeremy Fitzhardinge9480c532009-02-11 13:04:41 -08002244 if (!vma) /* Can happen if dup_mmap() received an OOM */
2245 return;
2246
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 lru_add_drain();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 flush_cache_mm(mm);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002249 tlb = tlb_gather_mmu(mm, 1);
Oleg Nesterov901608d2009-01-06 14:40:29 -08002250 /* update_hiwater_rss(mm) here? but nobody should be looking */
Hugh Dickinse0da3822005-04-19 13:29:15 -07002251 /* Use -1 here to ensure all VMAs in the mm are unmapped */
Hugh Dickins508034a2005-10-29 18:16:30 -07002252 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002253 vm_unacct_memory(nr_accounted);
Hugh Dickins9ba69292009-09-21 17:02:20 -07002254
Jan Beulich42b77722008-07-23 21:27:10 -07002255 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
Hugh Dickinsee39b372005-04-19 13:29:15 -07002256 tlb_finish_mmu(tlb, 0, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 /*
Hugh Dickins8f4f8c12005-10-29 18:16:29 -07002259 * Walk the list again, actually closing and freeing it,
2260 * with preemption enabled, without holding any MM locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07002262 while (vma)
2263 vma = remove_vma(vma);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002264
Hugh Dickinse2cdef82005-04-19 13:29:19 -07002265 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266}
2267
2268/* Insert vm structure into process list sorted by address
2269 * and into the inode's i_mmap tree. If vm_file is non-NULL
2270 * then i_mmap_lock is taken here.
2271 */
2272int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2273{
2274 struct vm_area_struct * __vma, * prev;
2275 struct rb_node ** rb_link, * rb_parent;
2276
2277 /*
2278 * The vm_pgoff of a purely anonymous vma should be irrelevant
2279 * until its first write fault, when page's anon_vma and index
2280 * are set. But now set the vm_pgoff it will almost certainly
2281 * end up with (unless mremap moves it elsewhere before that
2282 * first wfault), so /proc/pid/maps tells a consistent story.
2283 *
2284 * By setting it to reflect the virtual start address of the
2285 * vma, merges and splits can happen in a seamless way, just
2286 * using the existing file pgoff checks and manipulations.
2287 * Similarly in do_mmap_pgoff and in do_brk.
2288 */
2289 if (!vma->vm_file) {
2290 BUG_ON(vma->anon_vma);
2291 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2292 }
2293 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2294 if (__vma && __vma->vm_start < vma->vm_end)
2295 return -ENOMEM;
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002296 if ((vma->vm_flags & VM_ACCOUNT) &&
Alan Cox34b4e4a2007-08-22 14:01:28 -07002297 security_vm_enough_memory_mm(mm, vma_pages(vma)))
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002298 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299 vma_link(mm, vma, prev, rb_link, rb_parent);
2300 return 0;
2301}
2302
2303/*
2304 * Copy the vma structure to a new location in the same mm,
2305 * prior to moving page table entries, to effect an mremap move.
2306 */
2307struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2308 unsigned long addr, unsigned long len, pgoff_t pgoff)
2309{
2310 struct vm_area_struct *vma = *vmap;
2311 unsigned long vma_start = vma->vm_start;
2312 struct mm_struct *mm = vma->vm_mm;
2313 struct vm_area_struct *new_vma, *prev;
2314 struct rb_node **rb_link, *rb_parent;
2315 struct mempolicy *pol;
2316
2317 /*
2318 * If anonymous vma has not yet been faulted, update new pgoff
2319 * to match new location, to increase its chance of merging.
2320 */
2321 if (!vma->vm_file && !vma->anon_vma)
2322 pgoff = addr >> PAGE_SHIFT;
2323
2324 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2325 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2326 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2327 if (new_vma) {
2328 /*
2329 * Source vma may have been merged into new_vma
2330 */
2331 if (vma_start >= new_vma->vm_start &&
2332 vma_start < new_vma->vm_end)
2333 *vmap = new_vma;
2334 } else {
Christoph Lametere94b1762006-12-06 20:33:17 -08002335 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336 if (new_vma) {
2337 *new_vma = *vma;
Lee Schermerhorn846a16b2008-04-28 02:13:09 -07002338 pol = mpol_dup(vma_policy(vma));
Rik van Riel5beb4932010-03-05 13:42:07 -08002339 if (IS_ERR(pol))
2340 goto out_free_vma;
2341 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2342 if (anon_vma_clone(new_vma, vma))
2343 goto out_free_mempol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344 vma_set_policy(new_vma, pol);
2345 new_vma->vm_start = addr;
2346 new_vma->vm_end = addr + len;
2347 new_vma->vm_pgoff = pgoff;
Matt Helsley925d1c42008-04-29 01:01:36 -07002348 if (new_vma->vm_file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349 get_file(new_vma->vm_file);
Matt Helsley925d1c42008-04-29 01:01:36 -07002350 if (vma->vm_flags & VM_EXECUTABLE)
2351 added_exe_file_vma(mm);
2352 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353 if (new_vma->vm_ops && new_vma->vm_ops->open)
2354 new_vma->vm_ops->open(new_vma);
2355 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2356 }
2357 }
2358 return new_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08002359
2360 out_free_mempol:
2361 mpol_put(pol);
2362 out_free_vma:
2363 kmem_cache_free(vm_area_cachep, new_vma);
2364 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365}
akpm@osdl.org119f6572005-05-01 08:58:35 -07002366
2367/*
2368 * Return true if the calling process may expand its vm space by the passed
2369 * number of pages
2370 */
2371int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2372{
2373 unsigned long cur = mm->total_vm; /* pages */
2374 unsigned long lim;
2375
Jiri Slaby59e99e52010-03-05 13:41:44 -08002376 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
akpm@osdl.org119f6572005-05-01 08:58:35 -07002377
2378 if (cur + npages > lim)
2379 return 0;
2380 return 1;
2381}
Roland McGrathfa5dc222007-02-08 14:20:41 -08002382
2383
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002384static int special_mapping_fault(struct vm_area_struct *vma,
2385 struct vm_fault *vmf)
Roland McGrathfa5dc222007-02-08 14:20:41 -08002386{
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002387 pgoff_t pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002388 struct page **pages;
2389
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002390 /*
2391 * special mappings have no vm_file, and in that case, the mm
2392 * uses vm_pgoff internally. So we have to subtract it from here.
2393 * We are allowed to do this because we are the mm; do not copy
2394 * this code into drivers!
2395 */
2396 pgoff = vmf->pgoff - vma->vm_pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002397
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002398 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2399 pgoff--;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002400
2401 if (*pages) {
2402 struct page *page = *pages;
2403 get_page(page);
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002404 vmf->page = page;
2405 return 0;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002406 }
2407
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002408 return VM_FAULT_SIGBUS;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002409}
2410
2411/*
2412 * Having a close hook prevents vma merging regardless of flags.
2413 */
2414static void special_mapping_close(struct vm_area_struct *vma)
2415{
2416}
2417
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04002418static const struct vm_operations_struct special_mapping_vmops = {
Roland McGrathfa5dc222007-02-08 14:20:41 -08002419 .close = special_mapping_close,
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002420 .fault = special_mapping_fault,
Roland McGrathfa5dc222007-02-08 14:20:41 -08002421};
2422
2423/*
2424 * Called with mm->mmap_sem held for writing.
2425 * Insert a new vma covering the given region, with the given flags.
2426 * Its pages are supplied by the given array of struct page *.
2427 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2428 * The region past the last page supplied will always produce SIGBUS.
2429 * The array pointer and the pages it points to are assumed to stay alive
2430 * for as long as this mapping might exist.
2431 */
2432int install_special_mapping(struct mm_struct *mm,
2433 unsigned long addr, unsigned long len,
2434 unsigned long vm_flags, struct page **pages)
2435{
2436 struct vm_area_struct *vma;
2437
2438 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2439 if (unlikely(vma == NULL))
2440 return -ENOMEM;
2441
Rik van Riel5beb4932010-03-05 13:42:07 -08002442 INIT_LIST_HEAD(&vma->anon_vma_chain);
Roland McGrathfa5dc222007-02-08 14:20:41 -08002443 vma->vm_mm = mm;
2444 vma->vm_start = addr;
2445 vma->vm_end = addr + len;
2446
Nick Piggin2f987352008-02-02 03:08:53 +01002447 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
Coly Li3ed75eb2007-10-18 23:39:15 -07002448 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
Roland McGrathfa5dc222007-02-08 14:20:41 -08002449
2450 vma->vm_ops = &special_mapping_vmops;
2451 vma->vm_private_data = pages;
2452
2453 if (unlikely(insert_vm_struct(mm, vma))) {
2454 kmem_cache_free(vm_area_cachep, vma);
2455 return -ENOMEM;
2456 }
2457
2458 mm->total_vm += len >> PAGE_SHIFT;
2459
Ingo Molnarcdd6c482009-09-21 12:02:48 +02002460 perf_event_mmap(vma);
Peter Zijlstra089dd792009-06-05 14:04:55 +02002461
Roland McGrathfa5dc222007-02-08 14:20:41 -08002462 return 0;
2463}
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002464
2465static DEFINE_MUTEX(mm_all_locks_mutex);
2466
Peter Zijlstra454ed842008-08-11 09:30:25 +02002467static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002468{
2469 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2470 /*
2471 * The LSB of head.next can't change from under us
2472 * because we hold the mm_all_locks_mutex.
2473 */
Peter Zijlstra454ed842008-08-11 09:30:25 +02002474 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002475 /*
2476 * We can safely modify head.next after taking the
2477 * anon_vma->lock. If some other vma in this mm shares
2478 * the same anon_vma we won't take it again.
2479 *
2480 * No need of atomic instructions here, head.next
2481 * can't change from under us thanks to the
2482 * anon_vma->lock.
2483 */
2484 if (__test_and_set_bit(0, (unsigned long *)
2485 &anon_vma->head.next))
2486 BUG();
2487 }
2488}
2489
Peter Zijlstra454ed842008-08-11 09:30:25 +02002490static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002491{
2492 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2493 /*
2494 * AS_MM_ALL_LOCKS can't change from under us because
2495 * we hold the mm_all_locks_mutex.
2496 *
2497 * Operations on ->flags have to be atomic because
2498 * even if AS_MM_ALL_LOCKS is stable thanks to the
2499 * mm_all_locks_mutex, there may be other cpus
2500 * changing other bitflags in parallel to us.
2501 */
2502 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2503 BUG();
Peter Zijlstra454ed842008-08-11 09:30:25 +02002504 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002505 }
2506}
2507
2508/*
2509 * This operation locks against the VM for all pte/vma/mm related
2510 * operations that could ever happen on a certain mm. This includes
2511 * vmtruncate, try_to_unmap, and all page faults.
2512 *
2513 * The caller must take the mmap_sem in write mode before calling
2514 * mm_take_all_locks(). The caller isn't allowed to release the
2515 * mmap_sem until mm_drop_all_locks() returns.
2516 *
2517 * mmap_sem in write mode is required in order to block all operations
2518 * that could modify pagetables and free pages without need of
2519 * altering the vma layout (for example populate_range() with
2520 * nonlinear vmas). It's also needed in write mode to avoid new
2521 * anon_vmas to be associated with existing vmas.
2522 *
2523 * A single task can't take more than one mm_take_all_locks() in a row
2524 * or it would deadlock.
2525 *
2526 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2527 * mapping->flags avoid to take the same lock twice, if more than one
2528 * vma in this mm is backed by the same anon_vma or address_space.
2529 *
2530 * We can take all the locks in random order because the VM code
2531 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2532 * takes more than one of them in a row. Secondly we're protected
2533 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2534 *
2535 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2536 * that may have to take thousand of locks.
2537 *
2538 * mm_take_all_locks() can fail if it's interrupted by signals.
2539 */
2540int mm_take_all_locks(struct mm_struct *mm)
2541{
2542 struct vm_area_struct *vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08002543 struct anon_vma_chain *avc;
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002544 int ret = -EINTR;
2545
2546 BUG_ON(down_read_trylock(&mm->mmap_sem));
2547
2548 mutex_lock(&mm_all_locks_mutex);
2549
2550 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2551 if (signal_pending(current))
2552 goto out_unlock;
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002553 if (vma->vm_file && vma->vm_file->f_mapping)
Peter Zijlstra454ed842008-08-11 09:30:25 +02002554 vm_lock_mapping(mm, vma->vm_file->f_mapping);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002555 }
Peter Zijlstra7cd5a022008-08-11 09:30:25 +02002556
2557 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2558 if (signal_pending(current))
2559 goto out_unlock;
2560 if (vma->anon_vma)
Rik van Riel5beb4932010-03-05 13:42:07 -08002561 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2562 vm_lock_anon_vma(mm, avc->anon_vma);
Peter Zijlstra7cd5a022008-08-11 09:30:25 +02002563 }
2564
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002565 ret = 0;
2566
2567out_unlock:
2568 if (ret)
2569 mm_drop_all_locks(mm);
2570
2571 return ret;
2572}
2573
2574static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2575{
2576 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2577 /*
2578 * The LSB of head.next can't change to 0 from under
2579 * us because we hold the mm_all_locks_mutex.
2580 *
2581 * We must however clear the bitflag before unlocking
2582 * the vma so the users using the anon_vma->head will
2583 * never see our bitflag.
2584 *
2585 * No need of atomic instructions here, head.next
2586 * can't change from under us until we release the
2587 * anon_vma->lock.
2588 */
2589 if (!__test_and_clear_bit(0, (unsigned long *)
2590 &anon_vma->head.next))
2591 BUG();
2592 spin_unlock(&anon_vma->lock);
2593 }
2594}
2595
2596static void vm_unlock_mapping(struct address_space *mapping)
2597{
2598 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2599 /*
2600 * AS_MM_ALL_LOCKS can't change to 0 from under us
2601 * because we hold the mm_all_locks_mutex.
2602 */
2603 spin_unlock(&mapping->i_mmap_lock);
2604 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2605 &mapping->flags))
2606 BUG();
2607 }
2608}
2609
2610/*
2611 * The mmap_sem cannot be released by the caller until
2612 * mm_drop_all_locks() returns.
2613 */
2614void mm_drop_all_locks(struct mm_struct *mm)
2615{
2616 struct vm_area_struct *vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08002617 struct anon_vma_chain *avc;
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002618
2619 BUG_ON(down_read_trylock(&mm->mmap_sem));
2620 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2621
2622 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2623 if (vma->anon_vma)
Rik van Riel5beb4932010-03-05 13:42:07 -08002624 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2625 vm_unlock_anon_vma(avc->anon_vma);
Andrea Arcangeli7906d002008-07-28 15:46:26 -07002626 if (vma->vm_file && vma->vm_file->f_mapping)
2627 vm_unlock_mapping(vma->vm_file->f_mapping);
2628 }
2629
2630 mutex_unlock(&mm_all_locks_mutex);
2631}
David Howells8feae132009-01-08 12:04:47 +00002632
2633/*
2634 * initialise the VMA slab
2635 */
2636void __init mmap_init(void)
2637{
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -07002638 int ret;
2639
2640 ret = percpu_counter_init(&vm_committed_as, 0);
2641 VM_BUG_ON(ret);
David Howells8feae132009-01-08 12:04:47 +00002642}