Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mlock.c
4 *
5 * (C) Copyright 1995 Linus Torvalds
6 * (C) Copyright 2002 Christoph Hellwig
7 */
8
9#include <linux/capability.h>
10#include <linux/mman.h>
11#include <linux/mm.h>
12#include <linux/sched/user.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/pagemap.h>
16#include <linux/pagevec.h>
17#include <linux/pagewalk.h>
18#include <linux/mempolicy.h>
19#include <linux/syscalls.h>
20#include <linux/sched.h>
21#include <linux/export.h>
22#include <linux/rmap.h>
23#include <linux/mmzone.h>
24#include <linux/hugetlb.h>
25#include <linux/memcontrol.h>
26#include <linux/mm_inline.h>
27#include <linux/secretmem.h>
28
29#include "internal.h"
30
31struct mlock_pvec {
32 local_lock_t lock;
33 struct pagevec vec;
34};
35
36static DEFINE_PER_CPU(struct mlock_pvec, mlock_pvec) = {
37 .lock = INIT_LOCAL_LOCK(lock),
38};
39
40bool can_do_mlock(void)
41{
42 if (rlimit(RLIMIT_MEMLOCK) != 0)
43 return true;
44 if (capable(CAP_IPC_LOCK))
45 return true;
46 return false;
47}
48EXPORT_SYMBOL(can_do_mlock);
49
50/*
51 * Mlocked pages are marked with PageMlocked() flag for efficient testing
52 * in vmscan and, possibly, the fault path; and to support semi-accurate
53 * statistics.
54 *
55 * An mlocked page [PageMlocked(page)] is unevictable. As such, it will
56 * be placed on the LRU "unevictable" list, rather than the [in]active lists.
57 * The unevictable list is an LRU sibling list to the [in]active lists.
58 * PageUnevictable is set to indicate the unevictable state.
59 */
60
61static struct lruvec *__mlock_page(struct page *page, struct lruvec *lruvec)
62{
63 /* There is nothing more we can do while it's off LRU */
64 if (!TestClearPageLRU(page))
65 return lruvec;
66
67 lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec);
68
69 if (unlikely(page_evictable(page))) {
70 /*
71 * This is a little surprising, but quite possible:
72 * PageMlocked must have got cleared already by another CPU.
73 * Could this page be on the Unevictable LRU? I'm not sure,
74 * but move it now if so.
75 */
76 if (PageUnevictable(page)) {
77 del_page_from_lru_list(page, lruvec);
78 ClearPageUnevictable(page);
79 add_page_to_lru_list(page, lruvec);
80 __count_vm_events(UNEVICTABLE_PGRESCUED,
81 thp_nr_pages(page));
82 }
83 goto out;
84 }
85
86 if (PageUnevictable(page)) {
87 if (PageMlocked(page))
88 page->mlock_count++;
89 goto out;
90 }
91
92 del_page_from_lru_list(page, lruvec);
93 ClearPageActive(page);
94 SetPageUnevictable(page);
95 page->mlock_count = !!PageMlocked(page);
96 add_page_to_lru_list(page, lruvec);
97 __count_vm_events(UNEVICTABLE_PGCULLED, thp_nr_pages(page));
98out:
99 SetPageLRU(page);
100 return lruvec;
101}
102
103static struct lruvec *__mlock_new_page(struct page *page, struct lruvec *lruvec)
104{
105 VM_BUG_ON_PAGE(PageLRU(page), page);
106
107 lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec);
108
109 /* As above, this is a little surprising, but possible */
110 if (unlikely(page_evictable(page)))
111 goto out;
112
113 SetPageUnevictable(page);
114 page->mlock_count = !!PageMlocked(page);
115 __count_vm_events(UNEVICTABLE_PGCULLED, thp_nr_pages(page));
116out:
117 add_page_to_lru_list(page, lruvec);
118 SetPageLRU(page);
119 return lruvec;
120}
121
122static struct lruvec *__munlock_page(struct page *page, struct lruvec *lruvec)
123{
124 int nr_pages = thp_nr_pages(page);
125 bool isolated = false;
126
127 if (!TestClearPageLRU(page))
128 goto munlock;
129
130 isolated = true;
131 lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec);
132
133 if (PageUnevictable(page)) {
134 /* Then mlock_count is maintained, but might undercount */
135 if (page->mlock_count)
136 page->mlock_count--;
137 if (page->mlock_count)
138 goto out;
139 }
140 /* else assume that was the last mlock: reclaim will fix it if not */
141
142munlock:
143 if (TestClearPageMlocked(page)) {
144 __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
145 if (isolated || !PageUnevictable(page))
146 __count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);
147 else
148 __count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
149 }
150
151 /* page_evictable() has to be checked *after* clearing Mlocked */
152 if (isolated && PageUnevictable(page) && page_evictable(page)) {
153 del_page_from_lru_list(page, lruvec);
154 ClearPageUnevictable(page);
155 add_page_to_lru_list(page, lruvec);
156 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
157 }
158out:
159 if (isolated)
160 SetPageLRU(page);
161 return lruvec;
162}
163
164/*
165 * Flags held in the low bits of a struct page pointer on the mlock_pvec.
166 */
167#define LRU_PAGE 0x1
168#define NEW_PAGE 0x2
169static inline struct page *mlock_lru(struct page *page)
170{
171 return (struct page *)((unsigned long)page + LRU_PAGE);
172}
173
174static inline struct page *mlock_new(struct page *page)
175{
176 return (struct page *)((unsigned long)page + NEW_PAGE);
177}
178
179/*
180 * mlock_pagevec() is derived from pagevec_lru_move_fn():
181 * perhaps that can make use of such page pointer flags in future,
182 * but for now just keep it for mlock. We could use three separate
183 * pagevecs instead, but one feels better (munlocking a full pagevec
184 * does not need to drain mlocking pagevecs first).
185 */
186static void mlock_pagevec(struct pagevec *pvec)
187{
188 struct lruvec *lruvec = NULL;
189 unsigned long mlock;
190 struct page *page;
191 int i;
192
193 for (i = 0; i < pagevec_count(pvec); i++) {
194 page = pvec->pages[i];
195 mlock = (unsigned long)page & (LRU_PAGE | NEW_PAGE);
196 page = (struct page *)((unsigned long)page - mlock);
197 pvec->pages[i] = page;
198
199 if (mlock & LRU_PAGE)
200 lruvec = __mlock_page(page, lruvec);
201 else if (mlock & NEW_PAGE)
202 lruvec = __mlock_new_page(page, lruvec);
203 else
204 lruvec = __munlock_page(page, lruvec);
205 }
206
207 if (lruvec)
208 unlock_page_lruvec_irq(lruvec);
209 release_pages(pvec->pages, pvec->nr);
210 pagevec_reinit(pvec);
211}
212
213void mlock_page_drain_local(void)
214{
215 struct pagevec *pvec;
216
217 local_lock(&mlock_pvec.lock);
218 pvec = this_cpu_ptr(&mlock_pvec.vec);
219 if (pagevec_count(pvec))
220 mlock_pagevec(pvec);
221 local_unlock(&mlock_pvec.lock);
222}
223
224void mlock_page_drain_remote(int cpu)
225{
226 struct pagevec *pvec;
227
228 WARN_ON_ONCE(cpu_online(cpu));
229 pvec = &per_cpu(mlock_pvec.vec, cpu);
230 if (pagevec_count(pvec))
231 mlock_pagevec(pvec);
232}
233
234bool need_mlock_page_drain(int cpu)
235{
236 return pagevec_count(&per_cpu(mlock_pvec.vec, cpu));
237}
238
239/**
240 * mlock_folio - mlock a folio already on (or temporarily off) LRU
241 * @folio: folio to be mlocked.
242 */
243void mlock_folio(struct folio *folio)
244{
245 struct pagevec *pvec;
246
247 local_lock(&mlock_pvec.lock);
248 pvec = this_cpu_ptr(&mlock_pvec.vec);
249
250 if (!folio_test_set_mlocked(folio)) {
251 int nr_pages = folio_nr_pages(folio);
252
253 zone_stat_mod_folio(folio, NR_MLOCK, nr_pages);
254 __count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
255 }
256
257 folio_get(folio);
258 if (!pagevec_add(pvec, mlock_lru(&folio->page)) ||
259 folio_test_large(folio) || lru_cache_disabled())
260 mlock_pagevec(pvec);
261 local_unlock(&mlock_pvec.lock);
262}
263
264/**
265 * mlock_new_page - mlock a newly allocated page not yet on LRU
266 * @page: page to be mlocked, either a normal page or a THP head.
267 */
268void mlock_new_page(struct page *page)
269{
270 struct pagevec *pvec;
271 int nr_pages = thp_nr_pages(page);
272
273 local_lock(&mlock_pvec.lock);
274 pvec = this_cpu_ptr(&mlock_pvec.vec);
275 SetPageMlocked(page);
276 mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
277 __count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
278
279 get_page(page);
280 if (!pagevec_add(pvec, mlock_new(page)) ||
281 PageHead(page) || lru_cache_disabled())
282 mlock_pagevec(pvec);
283 local_unlock(&mlock_pvec.lock);
284}
285
286/**
287 * munlock_page - munlock a page
288 * @page: page to be munlocked, either a normal page or a THP head.
289 */
290void munlock_page(struct page *page)
291{
292 struct pagevec *pvec;
293
294 local_lock(&mlock_pvec.lock);
295 pvec = this_cpu_ptr(&mlock_pvec.vec);
296 /*
297 * TestClearPageMlocked(page) must be left to __munlock_page(),
298 * which will check whether the page is multiply mlocked.
299 */
300
301 get_page(page);
302 if (!pagevec_add(pvec, page) ||
303 PageHead(page) || lru_cache_disabled())
304 mlock_pagevec(pvec);
305 local_unlock(&mlock_pvec.lock);
306}
307
308static int mlock_pte_range(pmd_t *pmd, unsigned long addr,
309 unsigned long end, struct mm_walk *walk)
310
311{
312 struct vm_area_struct *vma = walk->vma;
313 spinlock_t *ptl;
314 pte_t *start_pte, *pte;
315 struct page *page;
316
317 ptl = pmd_trans_huge_lock(pmd, vma);
318 if (ptl) {
319 if (!pmd_present(*pmd))
320 goto out;
321 if (is_huge_zero_pmd(*pmd))
322 goto out;
323 page = pmd_page(*pmd);
324 if (vma->vm_flags & VM_LOCKED)
325 mlock_folio(page_folio(page));
326 else
327 munlock_page(page);
328 goto out;
329 }
330
331 start_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
332 for (pte = start_pte; addr != end; pte++, addr += PAGE_SIZE) {
333 if (!pte_present(*pte))
334 continue;
335 page = vm_normal_page(vma, addr, *pte);
336 if (!page || is_zone_device_page(page))
337 continue;
338 if (PageTransCompound(page))
339 continue;
340 if (vma->vm_flags & VM_LOCKED)
341 mlock_folio(page_folio(page));
342 else
343 munlock_page(page);
344 }
345 pte_unmap(start_pte);
346out:
347 spin_unlock(ptl);
348 cond_resched();
349 return 0;
350}
351
352/*
353 * mlock_vma_pages_range() - mlock any pages already in the range,
354 * or munlock all pages in the range.
355 * @vma - vma containing range to be mlock()ed or munlock()ed
356 * @start - start address in @vma of the range
357 * @end - end of range in @vma
358 * @newflags - the new set of flags for @vma.
359 *
360 * Called for mlock(), mlock2() and mlockall(), to set @vma VM_LOCKED;
361 * called for munlock() and munlockall(), to clear VM_LOCKED from @vma.
362 */
363static void mlock_vma_pages_range(struct vm_area_struct *vma,
364 unsigned long start, unsigned long end, vm_flags_t newflags)
365{
366 static const struct mm_walk_ops mlock_walk_ops = {
367 .pmd_entry = mlock_pte_range,
368 };
369
370 /*
371 * There is a slight chance that concurrent page migration,
372 * or page reclaim finding a page of this now-VM_LOCKED vma,
373 * will call mlock_vma_page() and raise page's mlock_count:
374 * double counting, leaving the page unevictable indefinitely.
375 * Communicate this danger to mlock_vma_page() with VM_IO,
376 * which is a VM_SPECIAL flag not allowed on VM_LOCKED vmas.
377 * mmap_lock is held in write mode here, so this weird
378 * combination should not be visible to other mmap_lock users;
379 * but WRITE_ONCE so rmap walkers must see VM_IO if VM_LOCKED.
380 */
381 if (newflags & VM_LOCKED)
382 newflags |= VM_IO;
383 WRITE_ONCE(vma->vm_flags, newflags);
384
385 lru_add_drain();
386 walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL);
387 lru_add_drain();
388
389 if (newflags & VM_IO) {
390 newflags &= ~VM_IO;
391 WRITE_ONCE(vma->vm_flags, newflags);
392 }
393}
394
395/*
396 * mlock_fixup - handle mlock[all]/munlock[all] requests.
397 *
398 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
399 * munlock is a no-op. However, for some special vmas, we go ahead and
400 * populate the ptes.
401 *
402 * For vmas that pass the filters, merge/split as appropriate.
403 */
404static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
405 unsigned long start, unsigned long end, vm_flags_t newflags)
406{
407 struct mm_struct *mm = vma->vm_mm;
408 pgoff_t pgoff;
409 int nr_pages;
410 int ret = 0;
411 vm_flags_t oldflags = vma->vm_flags;
412
413 if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
414 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
415 vma_is_dax(vma) || vma_is_secretmem(vma))
416 /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
417 goto out;
418
419 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
420 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
421 vma->vm_file, pgoff, vma_policy(vma),
422 vma->vm_userfaultfd_ctx, anon_vma_name(vma));
423 if (*prev) {
424 vma = *prev;
425 goto success;
426 }
427
428 if (start != vma->vm_start) {
429 ret = split_vma(mm, vma, start, 1);
430 if (ret)
431 goto out;
432 }
433
434 if (end != vma->vm_end) {
435 ret = split_vma(mm, vma, end, 0);
436 if (ret)
437 goto out;
438 }
439
440success:
441 /*
442 * Keep track of amount of locked VM.
443 */
444 nr_pages = (end - start) >> PAGE_SHIFT;
445 if (!(newflags & VM_LOCKED))
446 nr_pages = -nr_pages;
447 else if (oldflags & VM_LOCKED)
448 nr_pages = 0;
449 mm->locked_vm += nr_pages;
450
451 /*
452 * vm_flags is protected by the mmap_lock held in write mode.
453 * It's okay if try_to_unmap_one unmaps a page just after we
454 * set VM_LOCKED, populate_vma_page_range will bring it back.
455 */
456
457 if ((newflags & VM_LOCKED) && (oldflags & VM_LOCKED)) {
458 /* No work to do, and mlocking twice would be wrong */
459 vma->vm_flags = newflags;
460 } else {
461 mlock_vma_pages_range(vma, start, end, newflags);
462 }
463out:
464 *prev = vma;
465 return ret;
466}
467
468static int apply_vma_lock_flags(unsigned long start, size_t len,
469 vm_flags_t flags)
470{
471 unsigned long nstart, end, tmp;
472 struct vm_area_struct *vma, *prev;
473 int error;
474 MA_STATE(mas, ¤t->mm->mm_mt, start, start);
475
476 VM_BUG_ON(offset_in_page(start));
477 VM_BUG_ON(len != PAGE_ALIGN(len));
478 end = start + len;
479 if (end < start)
480 return -EINVAL;
481 if (end == start)
482 return 0;
483 vma = mas_walk(&mas);
484 if (!vma)
485 return -ENOMEM;
486
487 if (start > vma->vm_start)
488 prev = vma;
489 else
490 prev = mas_prev(&mas, 0);
491
492 for (nstart = start ; ; ) {
493 vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
494
495 newflags |= flags;
496
497 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
498 tmp = vma->vm_end;
499 if (tmp > end)
500 tmp = end;
501 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
502 if (error)
503 break;
504 nstart = tmp;
505 if (nstart < prev->vm_end)
506 nstart = prev->vm_end;
507 if (nstart >= end)
508 break;
509
510 vma = find_vma(prev->vm_mm, prev->vm_end);
511 if (!vma || vma->vm_start != nstart) {
512 error = -ENOMEM;
513 break;
514 }
515 }
516 return error;
517}
518
519/*
520 * Go through vma areas and sum size of mlocked
521 * vma pages, as return value.
522 * Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT)
523 * is also counted.
524 * Return value: previously mlocked page counts
525 */
526static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
527 unsigned long start, size_t len)
528{
529 struct vm_area_struct *vma;
530 unsigned long count = 0;
531 unsigned long end;
532 VMA_ITERATOR(vmi, mm, start);
533
534 /* Don't overflow past ULONG_MAX */
535 if (unlikely(ULONG_MAX - len < start))
536 end = ULONG_MAX;
537 else
538 end = start + len;
539
540 for_each_vma_range(vmi, vma, end) {
541 if (vma->vm_flags & VM_LOCKED) {
542 if (start > vma->vm_start)
543 count -= (start - vma->vm_start);
544 if (end < vma->vm_end) {
545 count += end - vma->vm_start;
546 break;
547 }
548 count += vma->vm_end - vma->vm_start;
549 }
550 }
551
552 return count >> PAGE_SHIFT;
553}
554
555/*
556 * convert get_user_pages() return value to posix mlock() error
557 */
558static int __mlock_posix_error_return(long retval)
559{
560 if (retval == -EFAULT)
561 retval = -ENOMEM;
562 else if (retval == -ENOMEM)
563 retval = -EAGAIN;
564 return retval;
565}
566
567static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t flags)
568{
569 unsigned long locked;
570 unsigned long lock_limit;
571 int error = -ENOMEM;
572
573 start = untagged_addr(start);
574
575 if (!can_do_mlock())
576 return -EPERM;
577
578 len = PAGE_ALIGN(len + (offset_in_page(start)));
579 start &= PAGE_MASK;
580
581 lock_limit = rlimit(RLIMIT_MEMLOCK);
582 lock_limit >>= PAGE_SHIFT;
583 locked = len >> PAGE_SHIFT;
584
585 if (mmap_write_lock_killable(current->mm))
586 return -EINTR;
587
588 locked += current->mm->locked_vm;
589 if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) {
590 /*
591 * It is possible that the regions requested intersect with
592 * previously mlocked areas, that part area in "mm->locked_vm"
593 * should not be counted to new mlock increment count. So check
594 * and adjust locked count if necessary.
595 */
596 locked -= count_mm_mlocked_page_nr(current->mm,
597 start, len);
598 }
599
600 /* check against resource limits */
601 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
602 error = apply_vma_lock_flags(start, len, flags);
603
604 mmap_write_unlock(current->mm);
605 if (error)
606 return error;
607
608 error = __mm_populate(start, len, 0);
609 if (error)
610 return __mlock_posix_error_return(error);
611 return 0;
612}
613
614SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
615{
616 return do_mlock(start, len, VM_LOCKED);
617}
618
619SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
620{
621 vm_flags_t vm_flags = VM_LOCKED;
622
623 if (flags & ~MLOCK_ONFAULT)
624 return -EINVAL;
625
626 if (flags & MLOCK_ONFAULT)
627 vm_flags |= VM_LOCKONFAULT;
628
629 return do_mlock(start, len, vm_flags);
630}
631
632SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
633{
634 int ret;
635
636 start = untagged_addr(start);
637
638 len = PAGE_ALIGN(len + (offset_in_page(start)));
639 start &= PAGE_MASK;
640
641 if (mmap_write_lock_killable(current->mm))
642 return -EINTR;
643 ret = apply_vma_lock_flags(start, len, 0);
644 mmap_write_unlock(current->mm);
645
646 return ret;
647}
648
649/*
650 * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall)
651 * and translate into the appropriate modifications to mm->def_flags and/or the
652 * flags for all current VMAs.
653 *
654 * There are a couple of subtleties with this. If mlockall() is called multiple
655 * times with different flags, the values do not necessarily stack. If mlockall
656 * is called once including the MCL_FUTURE flag and then a second time without
657 * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags.
658 */
659static int apply_mlockall_flags(int flags)
660{
661 MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
662 struct vm_area_struct *vma, *prev = NULL;
663 vm_flags_t to_add = 0;
664
665 current->mm->def_flags &= VM_LOCKED_CLEAR_MASK;
666 if (flags & MCL_FUTURE) {
667 current->mm->def_flags |= VM_LOCKED;
668
669 if (flags & MCL_ONFAULT)
670 current->mm->def_flags |= VM_LOCKONFAULT;
671
672 if (!(flags & MCL_CURRENT))
673 goto out;
674 }
675
676 if (flags & MCL_CURRENT) {
677 to_add |= VM_LOCKED;
678 if (flags & MCL_ONFAULT)
679 to_add |= VM_LOCKONFAULT;
680 }
681
682 mas_for_each(&mas, vma, ULONG_MAX) {
683 vm_flags_t newflags;
684
685 newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
686 newflags |= to_add;
687
688 /* Ignore errors */
689 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
690 mas_pause(&mas);
691 cond_resched();
692 }
693out:
694 return 0;
695}
696
697SYSCALL_DEFINE1(mlockall, int, flags)
698{
699 unsigned long lock_limit;
700 int ret;
701
702 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) ||
703 flags == MCL_ONFAULT)
704 return -EINVAL;
705
706 if (!can_do_mlock())
707 return -EPERM;
708
709 lock_limit = rlimit(RLIMIT_MEMLOCK);
710 lock_limit >>= PAGE_SHIFT;
711
712 if (mmap_write_lock_killable(current->mm))
713 return -EINTR;
714
715 ret = -ENOMEM;
716 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
717 capable(CAP_IPC_LOCK))
718 ret = apply_mlockall_flags(flags);
719 mmap_write_unlock(current->mm);
720 if (!ret && (flags & MCL_CURRENT))
721 mm_populate(0, TASK_SIZE);
722
723 return ret;
724}
725
726SYSCALL_DEFINE0(munlockall)
727{
728 int ret;
729
730 if (mmap_write_lock_killable(current->mm))
731 return -EINTR;
732 ret = apply_mlockall_flags(0);
733 mmap_write_unlock(current->mm);
734 return ret;
735}
736
737/*
738 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
739 * shm segments) get accounted against the user_struct instead.
740 */
741static DEFINE_SPINLOCK(shmlock_user_lock);
742
743int user_shm_lock(size_t size, struct ucounts *ucounts)
744{
745 unsigned long lock_limit, locked;
746 long memlock;
747 int allowed = 0;
748
749 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
750 lock_limit = rlimit(RLIMIT_MEMLOCK);
751 if (lock_limit != RLIM_INFINITY)
752 lock_limit >>= PAGE_SHIFT;
753 spin_lock(&shmlock_user_lock);
754 memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
755
756 if ((memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) {
757 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
758 goto out;
759 }
760 if (!get_ucounts(ucounts)) {
761 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
762 allowed = 0;
763 goto out;
764 }
765 allowed = 1;
766out:
767 spin_unlock(&shmlock_user_lock);
768 return allowed;
769}
770
771void user_shm_unlock(size_t size, struct ucounts *ucounts)
772{
773 spin_lock(&shmlock_user_lock);
774 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
775 spin_unlock(&shmlock_user_lock);
776 put_ucounts(ucounts);
777}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mlock.c
4 *
5 * (C) Copyright 1995 Linus Torvalds
6 * (C) Copyright 2002 Christoph Hellwig
7 */
8
9#include <linux/capability.h>
10#include <linux/mman.h>
11#include <linux/mm.h>
12#include <linux/sched/user.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/pagemap.h>
16#include <linux/pagevec.h>
17#include <linux/mempolicy.h>
18#include <linux/syscalls.h>
19#include <linux/sched.h>
20#include <linux/export.h>
21#include <linux/rmap.h>
22#include <linux/mmzone.h>
23#include <linux/hugetlb.h>
24#include <linux/memcontrol.h>
25#include <linux/mm_inline.h>
26#include <linux/secretmem.h>
27
28#include "internal.h"
29
30bool can_do_mlock(void)
31{
32 if (rlimit(RLIMIT_MEMLOCK) != 0)
33 return true;
34 if (capable(CAP_IPC_LOCK))
35 return true;
36 return false;
37}
38EXPORT_SYMBOL(can_do_mlock);
39
40/*
41 * Mlocked pages are marked with PageMlocked() flag for efficient testing
42 * in vmscan and, possibly, the fault path; and to support semi-accurate
43 * statistics.
44 *
45 * An mlocked page [PageMlocked(page)] is unevictable. As such, it will
46 * be placed on the LRU "unevictable" list, rather than the [in]active lists.
47 * The unevictable list is an LRU sibling list to the [in]active lists.
48 * PageUnevictable is set to indicate the unevictable state.
49 *
50 * When lazy mlocking via vmscan, it is important to ensure that the
51 * vma's VM_LOCKED status is not concurrently being modified, otherwise we
52 * may have mlocked a page that is being munlocked. So lazy mlock must take
53 * the mmap_lock for read, and verify that the vma really is locked
54 * (see mm/rmap.c).
55 */
56
57/*
58 * LRU accounting for clear_page_mlock()
59 */
60void clear_page_mlock(struct page *page)
61{
62 int nr_pages;
63
64 if (!TestClearPageMlocked(page))
65 return;
66
67 nr_pages = thp_nr_pages(page);
68 mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
69 count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
70 /*
71 * The previous TestClearPageMlocked() corresponds to the smp_mb()
72 * in __pagevec_lru_add_fn().
73 *
74 * See __pagevec_lru_add_fn for more explanation.
75 */
76 if (!isolate_lru_page(page)) {
77 putback_lru_page(page);
78 } else {
79 /*
80 * We lost the race. the page already moved to evictable list.
81 */
82 if (PageUnevictable(page))
83 count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
84 }
85}
86
87/*
88 * Mark page as mlocked if not already.
89 * If page on LRU, isolate and putback to move to unevictable list.
90 */
91void mlock_vma_page(struct page *page)
92{
93 /* Serialize with page migration */
94 BUG_ON(!PageLocked(page));
95
96 VM_BUG_ON_PAGE(PageTail(page), page);
97 VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
98
99 if (!TestSetPageMlocked(page)) {
100 int nr_pages = thp_nr_pages(page);
101
102 mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
103 count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
104 if (!isolate_lru_page(page))
105 putback_lru_page(page);
106 }
107}
108
109/*
110 * Finish munlock after successful page isolation
111 *
112 * Page must be locked. This is a wrapper for page_mlock()
113 * and putback_lru_page() with munlock accounting.
114 */
115static void __munlock_isolated_page(struct page *page)
116{
117 /*
118 * Optimization: if the page was mapped just once, that's our mapping
119 * and we don't need to check all the other vmas.
120 */
121 if (page_mapcount(page) > 1)
122 page_mlock(page);
123
124 /* Did try_to_unlock() succeed or punt? */
125 if (!PageMlocked(page))
126 count_vm_events(UNEVICTABLE_PGMUNLOCKED, thp_nr_pages(page));
127
128 putback_lru_page(page);
129}
130
131/*
132 * Accounting for page isolation fail during munlock
133 *
134 * Performs accounting when page isolation fails in munlock. There is nothing
135 * else to do because it means some other task has already removed the page
136 * from the LRU. putback_lru_page() will take care of removing the page from
137 * the unevictable list, if necessary. vmscan [page_referenced()] will move
138 * the page back to the unevictable list if some other vma has it mlocked.
139 */
140static void __munlock_isolation_failed(struct page *page)
141{
142 int nr_pages = thp_nr_pages(page);
143
144 if (PageUnevictable(page))
145 __count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
146 else
147 __count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);
148}
149
150/**
151 * munlock_vma_page - munlock a vma page
152 * @page: page to be unlocked, either a normal page or THP page head
153 *
154 * returns the size of the page as a page mask (0 for normal page,
155 * HPAGE_PMD_NR - 1 for THP head page)
156 *
157 * called from munlock()/munmap() path with page supposedly on the LRU.
158 * When we munlock a page, because the vma where we found the page is being
159 * munlock()ed or munmap()ed, we want to check whether other vmas hold the
160 * page locked so that we can leave it on the unevictable lru list and not
161 * bother vmscan with it. However, to walk the page's rmap list in
162 * page_mlock() we must isolate the page from the LRU. If some other
163 * task has removed the page from the LRU, we won't be able to do that.
164 * So we clear the PageMlocked as we might not get another chance. If we
165 * can't isolate the page, we leave it for putback_lru_page() and vmscan
166 * [page_referenced()/try_to_unmap()] to deal with.
167 */
168unsigned int munlock_vma_page(struct page *page)
169{
170 int nr_pages;
171
172 /* For page_mlock() and to serialize with page migration */
173 BUG_ON(!PageLocked(page));
174 VM_BUG_ON_PAGE(PageTail(page), page);
175
176 if (!TestClearPageMlocked(page)) {
177 /* Potentially, PTE-mapped THP: do not skip the rest PTEs */
178 return 0;
179 }
180
181 nr_pages = thp_nr_pages(page);
182 mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
183
184 if (!isolate_lru_page(page))
185 __munlock_isolated_page(page);
186 else
187 __munlock_isolation_failed(page);
188
189 return nr_pages - 1;
190}
191
192/*
193 * convert get_user_pages() return value to posix mlock() error
194 */
195static int __mlock_posix_error_return(long retval)
196{
197 if (retval == -EFAULT)
198 retval = -ENOMEM;
199 else if (retval == -ENOMEM)
200 retval = -EAGAIN;
201 return retval;
202}
203
204/*
205 * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
206 *
207 * The fast path is available only for evictable pages with single mapping.
208 * Then we can bypass the per-cpu pvec and get better performance.
209 * when mapcount > 1 we need page_mlock() which can fail.
210 * when !page_evictable(), we need the full redo logic of putback_lru_page to
211 * avoid leaving evictable page in unevictable list.
212 *
213 * In case of success, @page is added to @pvec and @pgrescued is incremented
214 * in case that the page was previously unevictable. @page is also unlocked.
215 */
216static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
217 int *pgrescued)
218{
219 VM_BUG_ON_PAGE(PageLRU(page), page);
220 VM_BUG_ON_PAGE(!PageLocked(page), page);
221
222 if (page_mapcount(page) <= 1 && page_evictable(page)) {
223 pagevec_add(pvec, page);
224 if (TestClearPageUnevictable(page))
225 (*pgrescued)++;
226 unlock_page(page);
227 return true;
228 }
229
230 return false;
231}
232
233/*
234 * Putback multiple evictable pages to the LRU
235 *
236 * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
237 * the pages might have meanwhile become unevictable but that is OK.
238 */
239static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
240{
241 count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
242 /*
243 *__pagevec_lru_add() calls release_pages() so we don't call
244 * put_page() explicitly
245 */
246 __pagevec_lru_add(pvec);
247 count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
248}
249
250/*
251 * Munlock a batch of pages from the same zone
252 *
253 * The work is split to two main phases. First phase clears the Mlocked flag
254 * and attempts to isolate the pages, all under a single zone lru lock.
255 * The second phase finishes the munlock only for pages where isolation
256 * succeeded.
257 *
258 * Note that the pagevec may be modified during the process.
259 */
260static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
261{
262 int i;
263 int nr = pagevec_count(pvec);
264 int delta_munlocked = -nr;
265 struct pagevec pvec_putback;
266 struct lruvec *lruvec = NULL;
267 int pgrescued = 0;
268
269 pagevec_init(&pvec_putback);
270
271 /* Phase 1: page isolation */
272 for (i = 0; i < nr; i++) {
273 struct page *page = pvec->pages[i];
274
275 if (TestClearPageMlocked(page)) {
276 /*
277 * We already have pin from follow_page_mask()
278 * so we can spare the get_page() here.
279 */
280 if (TestClearPageLRU(page)) {
281 lruvec = relock_page_lruvec_irq(page, lruvec);
282 del_page_from_lru_list(page, lruvec);
283 continue;
284 } else
285 __munlock_isolation_failed(page);
286 } else {
287 delta_munlocked++;
288 }
289
290 /*
291 * We won't be munlocking this page in the next phase
292 * but we still need to release the follow_page_mask()
293 * pin. We cannot do it under lru_lock however. If it's
294 * the last pin, __page_cache_release() would deadlock.
295 */
296 pagevec_add(&pvec_putback, pvec->pages[i]);
297 pvec->pages[i] = NULL;
298 }
299 if (lruvec) {
300 __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
301 unlock_page_lruvec_irq(lruvec);
302 } else if (delta_munlocked) {
303 mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
304 }
305
306 /* Now we can release pins of pages that we are not munlocking */
307 pagevec_release(&pvec_putback);
308
309 /* Phase 2: page munlock */
310 for (i = 0; i < nr; i++) {
311 struct page *page = pvec->pages[i];
312
313 if (page) {
314 lock_page(page);
315 if (!__putback_lru_fast_prepare(page, &pvec_putback,
316 &pgrescued)) {
317 /*
318 * Slow path. We don't want to lose the last
319 * pin before unlock_page()
320 */
321 get_page(page); /* for putback_lru_page() */
322 __munlock_isolated_page(page);
323 unlock_page(page);
324 put_page(page); /* from follow_page_mask() */
325 }
326 }
327 }
328
329 /*
330 * Phase 3: page putback for pages that qualified for the fast path
331 * This will also call put_page() to return pin from follow_page_mask()
332 */
333 if (pagevec_count(&pvec_putback))
334 __putback_lru_fast(&pvec_putback, pgrescued);
335}
336
337/*
338 * Fill up pagevec for __munlock_pagevec using pte walk
339 *
340 * The function expects that the struct page corresponding to @start address is
341 * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
342 *
343 * The rest of @pvec is filled by subsequent pages within the same pmd and same
344 * zone, as long as the pte's are present and vm_normal_page() succeeds. These
345 * pages also get pinned.
346 *
347 * Returns the address of the next page that should be scanned. This equals
348 * @start + PAGE_SIZE when no page could be added by the pte walk.
349 */
350static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
351 struct vm_area_struct *vma, struct zone *zone,
352 unsigned long start, unsigned long end)
353{
354 pte_t *pte;
355 spinlock_t *ptl;
356
357 /*
358 * Initialize pte walk starting at the already pinned page where we
359 * are sure that there is a pte, as it was pinned under the same
360 * mmap_lock write op.
361 */
362 pte = get_locked_pte(vma->vm_mm, start, &ptl);
363 /* Make sure we do not cross the page table boundary */
364 end = pgd_addr_end(start, end);
365 end = p4d_addr_end(start, end);
366 end = pud_addr_end(start, end);
367 end = pmd_addr_end(start, end);
368
369 /* The page next to the pinned page is the first we will try to get */
370 start += PAGE_SIZE;
371 while (start < end) {
372 struct page *page = NULL;
373 pte++;
374 if (pte_present(*pte))
375 page = vm_normal_page(vma, start, *pte);
376 /*
377 * Break if page could not be obtained or the page's node+zone does not
378 * match
379 */
380 if (!page || page_zone(page) != zone)
381 break;
382
383 /*
384 * Do not use pagevec for PTE-mapped THP,
385 * munlock_vma_pages_range() will handle them.
386 */
387 if (PageTransCompound(page))
388 break;
389
390 get_page(page);
391 /*
392 * Increase the address that will be returned *before* the
393 * eventual break due to pvec becoming full by adding the page
394 */
395 start += PAGE_SIZE;
396 if (pagevec_add(pvec, page) == 0)
397 break;
398 }
399 pte_unmap_unlock(pte, ptl);
400 return start;
401}
402
403/*
404 * munlock_vma_pages_range() - munlock all pages in the vma range.'
405 * @vma - vma containing range to be munlock()ed.
406 * @start - start address in @vma of the range
407 * @end - end of range in @vma.
408 *
409 * For mremap(), munmap() and exit().
410 *
411 * Called with @vma VM_LOCKED.
412 *
413 * Returns with VM_LOCKED cleared. Callers must be prepared to
414 * deal with this.
415 *
416 * We don't save and restore VM_LOCKED here because pages are
417 * still on lru. In unmap path, pages might be scanned by reclaim
418 * and re-mlocked by page_mlock/try_to_unmap before we unmap and
419 * free them. This will result in freeing mlocked pages.
420 */
421void munlock_vma_pages_range(struct vm_area_struct *vma,
422 unsigned long start, unsigned long end)
423{
424 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
425
426 while (start < end) {
427 struct page *page;
428 unsigned int page_mask = 0;
429 unsigned long page_increm;
430 struct pagevec pvec;
431 struct zone *zone;
432
433 pagevec_init(&pvec);
434 /*
435 * Although FOLL_DUMP is intended for get_dump_page(),
436 * it just so happens that its special treatment of the
437 * ZERO_PAGE (returning an error instead of doing get_page)
438 * suits munlock very well (and if somehow an abnormal page
439 * has sneaked into the range, we won't oops here: great).
440 */
441 page = follow_page(vma, start, FOLL_GET | FOLL_DUMP);
442
443 if (page && !IS_ERR(page)) {
444 if (PageTransTail(page)) {
445 VM_BUG_ON_PAGE(PageMlocked(page), page);
446 put_page(page); /* follow_page_mask() */
447 } else if (PageTransHuge(page)) {
448 lock_page(page);
449 /*
450 * Any THP page found by follow_page_mask() may
451 * have gotten split before reaching
452 * munlock_vma_page(), so we need to compute
453 * the page_mask here instead.
454 */
455 page_mask = munlock_vma_page(page);
456 unlock_page(page);
457 put_page(page); /* follow_page_mask() */
458 } else {
459 /*
460 * Non-huge pages are handled in batches via
461 * pagevec. The pin from follow_page_mask()
462 * prevents them from collapsing by THP.
463 */
464 pagevec_add(&pvec, page);
465 zone = page_zone(page);
466
467 /*
468 * Try to fill the rest of pagevec using fast
469 * pte walk. This will also update start to
470 * the next page to process. Then munlock the
471 * pagevec.
472 */
473 start = __munlock_pagevec_fill(&pvec, vma,
474 zone, start, end);
475 __munlock_pagevec(&pvec, zone);
476 goto next;
477 }
478 }
479 page_increm = 1 + page_mask;
480 start += page_increm * PAGE_SIZE;
481next:
482 cond_resched();
483 }
484}
485
486/*
487 * mlock_fixup - handle mlock[all]/munlock[all] requests.
488 *
489 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
490 * munlock is a no-op. However, for some special vmas, we go ahead and
491 * populate the ptes.
492 *
493 * For vmas that pass the filters, merge/split as appropriate.
494 */
495static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
496 unsigned long start, unsigned long end, vm_flags_t newflags)
497{
498 struct mm_struct *mm = vma->vm_mm;
499 pgoff_t pgoff;
500 int nr_pages;
501 int ret = 0;
502 int lock = !!(newflags & VM_LOCKED);
503 vm_flags_t old_flags = vma->vm_flags;
504
505 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
506 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
507 vma_is_dax(vma) || vma_is_secretmem(vma))
508 /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
509 goto out;
510
511 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
512 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
513 vma->vm_file, pgoff, vma_policy(vma),
514 vma->vm_userfaultfd_ctx);
515 if (*prev) {
516 vma = *prev;
517 goto success;
518 }
519
520 if (start != vma->vm_start) {
521 ret = split_vma(mm, vma, start, 1);
522 if (ret)
523 goto out;
524 }
525
526 if (end != vma->vm_end) {
527 ret = split_vma(mm, vma, end, 0);
528 if (ret)
529 goto out;
530 }
531
532success:
533 /*
534 * Keep track of amount of locked VM.
535 */
536 nr_pages = (end - start) >> PAGE_SHIFT;
537 if (!lock)
538 nr_pages = -nr_pages;
539 else if (old_flags & VM_LOCKED)
540 nr_pages = 0;
541 mm->locked_vm += nr_pages;
542
543 /*
544 * vm_flags is protected by the mmap_lock held in write mode.
545 * It's okay if try_to_unmap_one unmaps a page just after we
546 * set VM_LOCKED, populate_vma_page_range will bring it back.
547 */
548
549 if (lock)
550 vma->vm_flags = newflags;
551 else
552 munlock_vma_pages_range(vma, start, end);
553
554out:
555 *prev = vma;
556 return ret;
557}
558
559static int apply_vma_lock_flags(unsigned long start, size_t len,
560 vm_flags_t flags)
561{
562 unsigned long nstart, end, tmp;
563 struct vm_area_struct *vma, *prev;
564 int error;
565
566 VM_BUG_ON(offset_in_page(start));
567 VM_BUG_ON(len != PAGE_ALIGN(len));
568 end = start + len;
569 if (end < start)
570 return -EINVAL;
571 if (end == start)
572 return 0;
573 vma = find_vma(current->mm, start);
574 if (!vma || vma->vm_start > start)
575 return -ENOMEM;
576
577 prev = vma->vm_prev;
578 if (start > vma->vm_start)
579 prev = vma;
580
581 for (nstart = start ; ; ) {
582 vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
583
584 newflags |= flags;
585
586 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
587 tmp = vma->vm_end;
588 if (tmp > end)
589 tmp = end;
590 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
591 if (error)
592 break;
593 nstart = tmp;
594 if (nstart < prev->vm_end)
595 nstart = prev->vm_end;
596 if (nstart >= end)
597 break;
598
599 vma = prev->vm_next;
600 if (!vma || vma->vm_start != nstart) {
601 error = -ENOMEM;
602 break;
603 }
604 }
605 return error;
606}
607
608/*
609 * Go through vma areas and sum size of mlocked
610 * vma pages, as return value.
611 * Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT)
612 * is also counted.
613 * Return value: previously mlocked page counts
614 */
615static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
616 unsigned long start, size_t len)
617{
618 struct vm_area_struct *vma;
619 unsigned long count = 0;
620
621 if (mm == NULL)
622 mm = current->mm;
623
624 vma = find_vma(mm, start);
625 if (vma == NULL)
626 return 0;
627
628 for (; vma ; vma = vma->vm_next) {
629 if (start >= vma->vm_end)
630 continue;
631 if (start + len <= vma->vm_start)
632 break;
633 if (vma->vm_flags & VM_LOCKED) {
634 if (start > vma->vm_start)
635 count -= (start - vma->vm_start);
636 if (start + len < vma->vm_end) {
637 count += start + len - vma->vm_start;
638 break;
639 }
640 count += vma->vm_end - vma->vm_start;
641 }
642 }
643
644 return count >> PAGE_SHIFT;
645}
646
647static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t flags)
648{
649 unsigned long locked;
650 unsigned long lock_limit;
651 int error = -ENOMEM;
652
653 start = untagged_addr(start);
654
655 if (!can_do_mlock())
656 return -EPERM;
657
658 len = PAGE_ALIGN(len + (offset_in_page(start)));
659 start &= PAGE_MASK;
660
661 lock_limit = rlimit(RLIMIT_MEMLOCK);
662 lock_limit >>= PAGE_SHIFT;
663 locked = len >> PAGE_SHIFT;
664
665 if (mmap_write_lock_killable(current->mm))
666 return -EINTR;
667
668 locked += current->mm->locked_vm;
669 if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) {
670 /*
671 * It is possible that the regions requested intersect with
672 * previously mlocked areas, that part area in "mm->locked_vm"
673 * should not be counted to new mlock increment count. So check
674 * and adjust locked count if necessary.
675 */
676 locked -= count_mm_mlocked_page_nr(current->mm,
677 start, len);
678 }
679
680 /* check against resource limits */
681 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
682 error = apply_vma_lock_flags(start, len, flags);
683
684 mmap_write_unlock(current->mm);
685 if (error)
686 return error;
687
688 error = __mm_populate(start, len, 0);
689 if (error)
690 return __mlock_posix_error_return(error);
691 return 0;
692}
693
694SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
695{
696 return do_mlock(start, len, VM_LOCKED);
697}
698
699SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
700{
701 vm_flags_t vm_flags = VM_LOCKED;
702
703 if (flags & ~MLOCK_ONFAULT)
704 return -EINVAL;
705
706 if (flags & MLOCK_ONFAULT)
707 vm_flags |= VM_LOCKONFAULT;
708
709 return do_mlock(start, len, vm_flags);
710}
711
712SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
713{
714 int ret;
715
716 start = untagged_addr(start);
717
718 len = PAGE_ALIGN(len + (offset_in_page(start)));
719 start &= PAGE_MASK;
720
721 if (mmap_write_lock_killable(current->mm))
722 return -EINTR;
723 ret = apply_vma_lock_flags(start, len, 0);
724 mmap_write_unlock(current->mm);
725
726 return ret;
727}
728
729/*
730 * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall)
731 * and translate into the appropriate modifications to mm->def_flags and/or the
732 * flags for all current VMAs.
733 *
734 * There are a couple of subtleties with this. If mlockall() is called multiple
735 * times with different flags, the values do not necessarily stack. If mlockall
736 * is called once including the MCL_FUTURE flag and then a second time without
737 * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags.
738 */
739static int apply_mlockall_flags(int flags)
740{
741 struct vm_area_struct *vma, *prev = NULL;
742 vm_flags_t to_add = 0;
743
744 current->mm->def_flags &= VM_LOCKED_CLEAR_MASK;
745 if (flags & MCL_FUTURE) {
746 current->mm->def_flags |= VM_LOCKED;
747
748 if (flags & MCL_ONFAULT)
749 current->mm->def_flags |= VM_LOCKONFAULT;
750
751 if (!(flags & MCL_CURRENT))
752 goto out;
753 }
754
755 if (flags & MCL_CURRENT) {
756 to_add |= VM_LOCKED;
757 if (flags & MCL_ONFAULT)
758 to_add |= VM_LOCKONFAULT;
759 }
760
761 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
762 vm_flags_t newflags;
763
764 newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
765 newflags |= to_add;
766
767 /* Ignore errors */
768 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
769 cond_resched();
770 }
771out:
772 return 0;
773}
774
775SYSCALL_DEFINE1(mlockall, int, flags)
776{
777 unsigned long lock_limit;
778 int ret;
779
780 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) ||
781 flags == MCL_ONFAULT)
782 return -EINVAL;
783
784 if (!can_do_mlock())
785 return -EPERM;
786
787 lock_limit = rlimit(RLIMIT_MEMLOCK);
788 lock_limit >>= PAGE_SHIFT;
789
790 if (mmap_write_lock_killable(current->mm))
791 return -EINTR;
792
793 ret = -ENOMEM;
794 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
795 capable(CAP_IPC_LOCK))
796 ret = apply_mlockall_flags(flags);
797 mmap_write_unlock(current->mm);
798 if (!ret && (flags & MCL_CURRENT))
799 mm_populate(0, TASK_SIZE);
800
801 return ret;
802}
803
804SYSCALL_DEFINE0(munlockall)
805{
806 int ret;
807
808 if (mmap_write_lock_killable(current->mm))
809 return -EINTR;
810 ret = apply_mlockall_flags(0);
811 mmap_write_unlock(current->mm);
812 return ret;
813}
814
815/*
816 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
817 * shm segments) get accounted against the user_struct instead.
818 */
819static DEFINE_SPINLOCK(shmlock_user_lock);
820
821int user_shm_lock(size_t size, struct ucounts *ucounts)
822{
823 unsigned long lock_limit, locked;
824 long memlock;
825 int allowed = 0;
826
827 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
828 lock_limit = rlimit(RLIMIT_MEMLOCK);
829 if (lock_limit == RLIM_INFINITY)
830 allowed = 1;
831 lock_limit >>= PAGE_SHIFT;
832 spin_lock(&shmlock_user_lock);
833 memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
834
835 if (!allowed && (memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) {
836 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
837 goto out;
838 }
839 if (!get_ucounts(ucounts)) {
840 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
841 goto out;
842 }
843 allowed = 1;
844out:
845 spin_unlock(&shmlock_user_lock);
846 return allowed;
847}
848
849void user_shm_unlock(size_t size, struct ucounts *ucounts)
850{
851 spin_lock(&shmlock_user_lock);
852 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
853 spin_unlock(&shmlock_user_lock);
854 put_ucounts(ucounts);
855}