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8#include <linux/capability.h>
9#include <linux/mman.h>
10#include <linux/mm.h>
11#include <linux/swap.h>
12#include <linux/swapops.h>
13#include <linux/pagemap.h>
14#include <linux/mempolicy.h>
15#include <linux/syscalls.h>
16#include <linux/sched.h>
17#include <linux/module.h>
18#include <linux/rmap.h>
19#include <linux/mmzone.h>
20#include <linux/hugetlb.h>
21
22#include "internal.h"
23
24int can_do_mlock(void)
25{
26 if (capable(CAP_IPC_LOCK))
27 return 1;
28 if (rlimit(RLIMIT_MEMLOCK) != 0)
29 return 1;
30 return 0;
31}
32EXPORT_SYMBOL(can_do_mlock);
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53
54void __clear_page_mlock(struct page *page)
55{
56 VM_BUG_ON(!PageLocked(page));
57
58 if (!page->mapping) {
59 return;
60 }
61
62 dec_zone_page_state(page, NR_MLOCK);
63 count_vm_event(UNEVICTABLE_PGCLEARED);
64 if (!isolate_lru_page(page)) {
65 putback_lru_page(page);
66 } else {
67
68
69
70 if (PageUnevictable(page))
71 count_vm_event(UNEVICTABLE_PGSTRANDED);
72 }
73}
74
75
76
77
78
79void mlock_vma_page(struct page *page)
80{
81 BUG_ON(!PageLocked(page));
82
83 if (!TestSetPageMlocked(page)) {
84 inc_zone_page_state(page, NR_MLOCK);
85 count_vm_event(UNEVICTABLE_PGMLOCKED);
86 if (!isolate_lru_page(page))
87 putback_lru_page(page);
88 }
89}
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105
106void munlock_vma_page(struct page *page)
107{
108 BUG_ON(!PageLocked(page));
109
110 if (TestClearPageMlocked(page)) {
111 dec_zone_page_state(page, NR_MLOCK);
112 if (!isolate_lru_page(page)) {
113 int ret = try_to_munlock(page);
114
115
116
117 if (ret != SWAP_MLOCK)
118 count_vm_event(UNEVICTABLE_PGMUNLOCKED);
119
120 putback_lru_page(page);
121 } else {
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129
130 if (PageUnevictable(page))
131 count_vm_event(UNEVICTABLE_PGSTRANDED);
132 else
133 count_vm_event(UNEVICTABLE_PGMUNLOCKED);
134 }
135 }
136}
137
138static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
139{
140 return (vma->vm_flags & VM_GROWSDOWN) &&
141 (vma->vm_start == addr) &&
142 !vma_stack_continue(vma->vm_prev, addr);
143}
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156
157static long __mlock_vma_pages_range(struct vm_area_struct *vma,
158 unsigned long start, unsigned long end,
159 int *nonblocking)
160{
161 struct mm_struct *mm = vma->vm_mm;
162 unsigned long addr = start;
163 int nr_pages = (end - start) / PAGE_SIZE;
164 int gup_flags;
165
166 VM_BUG_ON(start & ~PAGE_MASK);
167 VM_BUG_ON(end & ~PAGE_MASK);
168 VM_BUG_ON(start < vma->vm_start);
169 VM_BUG_ON(end > vma->vm_end);
170 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
171
172 gup_flags = FOLL_TOUCH;
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177
178 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
179 gup_flags |= FOLL_WRITE;
180
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184
185 if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
186 gup_flags |= FOLL_FORCE;
187
188 if (vma->vm_flags & VM_LOCKED)
189 gup_flags |= FOLL_MLOCK;
190
191
192 if (stack_guard_page(vma, start)) {
193 addr += PAGE_SIZE;
194 nr_pages--;
195 }
196
197 return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
198 NULL, NULL, nonblocking);
199}
200
201
202
203
204static int __mlock_posix_error_return(long retval)
205{
206 if (retval == -EFAULT)
207 retval = -ENOMEM;
208 else if (retval == -ENOMEM)
209 retval = -EAGAIN;
210 return retval;
211}
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225
226long mlock_vma_pages_range(struct vm_area_struct *vma,
227 unsigned long start, unsigned long end)
228{
229 int nr_pages = (end - start) / PAGE_SIZE;
230 BUG_ON(!(vma->vm_flags & VM_LOCKED));
231
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233
234
235 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
236 goto no_mlock;
237
238 if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
239 is_vm_hugetlb_page(vma) ||
240 vma == get_gate_vma(current))) {
241
242 __mlock_vma_pages_range(vma, start, end, NULL);
243
244
245 return 0;
246 }
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255
256 make_pages_present(start, end);
257
258no_mlock:
259 vma->vm_flags &= ~VM_LOCKED;
260 return nr_pages;
261}
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281void munlock_vma_pages_range(struct vm_area_struct *vma,
282 unsigned long start, unsigned long end)
283{
284 unsigned long addr;
285
286 lru_add_drain();
287 vma->vm_flags &= ~VM_LOCKED;
288
289 for (addr = start; addr < end; addr += PAGE_SIZE) {
290 struct page *page;
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298 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
299 if (page && !IS_ERR(page)) {
300 lock_page(page);
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305
306
307 if (page->mapping)
308 munlock_vma_page(page);
309 unlock_page(page);
310 put_page(page);
311 }
312 cond_resched();
313 }
314}
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324
325static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
326 unsigned long start, unsigned long end, unsigned int newflags)
327{
328 struct mm_struct *mm = vma->vm_mm;
329 pgoff_t pgoff;
330 int nr_pages;
331 int ret = 0;
332 int lock = newflags & VM_LOCKED;
333
334 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
335 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current))
336 goto out;
337
338 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
339 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
340 vma->vm_file, pgoff, vma_policy(vma));
341 if (*prev) {
342 vma = *prev;
343 goto success;
344 }
345
346 if (start != vma->vm_start) {
347 ret = split_vma(mm, vma, start, 1);
348 if (ret)
349 goto out;
350 }
351
352 if (end != vma->vm_end) {
353 ret = split_vma(mm, vma, end, 0);
354 if (ret)
355 goto out;
356 }
357
358success:
359
360
361
362 nr_pages = (end - start) >> PAGE_SHIFT;
363 if (!lock)
364 nr_pages = -nr_pages;
365 mm->locked_vm += nr_pages;
366
367
368
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370
371
372
373 if (lock)
374 vma->vm_flags = newflags;
375 else
376 munlock_vma_pages_range(vma, start, end);
377
378out:
379 *prev = vma;
380 return ret;
381}
382
383static int do_mlock(unsigned long start, size_t len, int on)
384{
385 unsigned long nstart, end, tmp;
386 struct vm_area_struct * vma, * prev;
387 int error;
388
389 VM_BUG_ON(start & ~PAGE_MASK);
390 VM_BUG_ON(len != PAGE_ALIGN(len));
391 end = start + len;
392 if (end < start)
393 return -EINVAL;
394 if (end == start)
395 return 0;
396 vma = find_vma_prev(current->mm, start, &prev);
397 if (!vma || vma->vm_start > start)
398 return -ENOMEM;
399
400 if (start > vma->vm_start)
401 prev = vma;
402
403 for (nstart = start ; ; ) {
404 unsigned int newflags;
405
406
407
408 newflags = vma->vm_flags | VM_LOCKED;
409 if (!on)
410 newflags &= ~VM_LOCKED;
411
412 tmp = vma->vm_end;
413 if (tmp > end)
414 tmp = end;
415 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
416 if (error)
417 break;
418 nstart = tmp;
419 if (nstart < prev->vm_end)
420 nstart = prev->vm_end;
421 if (nstart >= end)
422 break;
423
424 vma = prev->vm_next;
425 if (!vma || vma->vm_start != nstart) {
426 error = -ENOMEM;
427 break;
428 }
429 }
430 return error;
431}
432
433static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
434{
435 struct mm_struct *mm = current->mm;
436 unsigned long end, nstart, nend;
437 struct vm_area_struct *vma = NULL;
438 int locked = 0;
439 int ret = 0;
440
441 VM_BUG_ON(start & ~PAGE_MASK);
442 VM_BUG_ON(len != PAGE_ALIGN(len));
443 end = start + len;
444
445 for (nstart = start; nstart < end; nstart = nend) {
446
447
448
449
450 if (!locked) {
451 locked = 1;
452 down_read(&mm->mmap_sem);
453 vma = find_vma(mm, nstart);
454 } else if (nstart >= vma->vm_end)
455 vma = vma->vm_next;
456 if (!vma || vma->vm_start >= end)
457 break;
458
459
460
461
462 nend = min(end, vma->vm_end);
463 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
464 continue;
465 if (nstart < vma->vm_start)
466 nstart = vma->vm_start;
467
468
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470
471
472 ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
473 if (ret < 0) {
474 if (ignore_errors) {
475 ret = 0;
476 continue;
477 }
478 ret = __mlock_posix_error_return(ret);
479 break;
480 }
481 nend = nstart + ret * PAGE_SIZE;
482 ret = 0;
483 }
484 if (locked)
485 up_read(&mm->mmap_sem);
486 return ret;
487}
488
489SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
490{
491 unsigned long locked;
492 unsigned long lock_limit;
493 int error = -ENOMEM;
494
495 if (!can_do_mlock())
496 return -EPERM;
497
498 lru_add_drain_all();
499
500 down_write(¤t->mm->mmap_sem);
501 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
502 start &= PAGE_MASK;
503
504 locked = len >> PAGE_SHIFT;
505 locked += current->mm->locked_vm;
506
507 lock_limit = rlimit(RLIMIT_MEMLOCK);
508 lock_limit >>= PAGE_SHIFT;
509
510
511 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
512 error = do_mlock(start, len, 1);
513 up_write(¤t->mm->mmap_sem);
514 if (!error)
515 error = do_mlock_pages(start, len, 0);
516 return error;
517}
518
519SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
520{
521 int ret;
522
523 down_write(¤t->mm->mmap_sem);
524 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
525 start &= PAGE_MASK;
526 ret = do_mlock(start, len, 0);
527 up_write(¤t->mm->mmap_sem);
528 return ret;
529}
530
531static int do_mlockall(int flags)
532{
533 struct vm_area_struct * vma, * prev = NULL;
534 unsigned int def_flags = 0;
535
536 if (flags & MCL_FUTURE)
537 def_flags = VM_LOCKED;
538 current->mm->def_flags = def_flags;
539 if (flags == MCL_FUTURE)
540 goto out;
541
542 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
543 unsigned int newflags;
544
545 newflags = vma->vm_flags | VM_LOCKED;
546 if (!(flags & MCL_CURRENT))
547 newflags &= ~VM_LOCKED;
548
549
550 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
551 }
552out:
553 return 0;
554}
555
556SYSCALL_DEFINE1(mlockall, int, flags)
557{
558 unsigned long lock_limit;
559 int ret = -EINVAL;
560
561 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
562 goto out;
563
564 ret = -EPERM;
565 if (!can_do_mlock())
566 goto out;
567
568 lru_add_drain_all();
569
570 down_write(¤t->mm->mmap_sem);
571
572 lock_limit = rlimit(RLIMIT_MEMLOCK);
573 lock_limit >>= PAGE_SHIFT;
574
575 ret = -ENOMEM;
576 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
577 capable(CAP_IPC_LOCK))
578 ret = do_mlockall(flags);
579 up_write(¤t->mm->mmap_sem);
580 if (!ret && (flags & MCL_CURRENT)) {
581
582 do_mlock_pages(0, TASK_SIZE, 1);
583 }
584out:
585 return ret;
586}
587
588SYSCALL_DEFINE0(munlockall)
589{
590 int ret;
591
592 down_write(¤t->mm->mmap_sem);
593 ret = do_mlockall(0);
594 up_write(¤t->mm->mmap_sem);
595 return ret;
596}
597
598
599
600
601
602static DEFINE_SPINLOCK(shmlock_user_lock);
603
604int user_shm_lock(size_t size, struct user_struct *user)
605{
606 unsigned long lock_limit, locked;
607 int allowed = 0;
608
609 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
610 lock_limit = rlimit(RLIMIT_MEMLOCK);
611 if (lock_limit == RLIM_INFINITY)
612 allowed = 1;
613 lock_limit >>= PAGE_SHIFT;
614 spin_lock(&shmlock_user_lock);
615 if (!allowed &&
616 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
617 goto out;
618 get_uid(user);
619 user->locked_shm += locked;
620 allowed = 1;
621out:
622 spin_unlock(&shmlock_user_lock);
623 return allowed;
624}
625
626void user_shm_unlock(size_t size, struct user_struct *user)
627{
628 spin_lock(&shmlock_user_lock);
629 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
630 spin_unlock(&shmlock_user_lock);
631 free_uid(user);
632}
633