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_fbatch {
 32	local_lock_t lock;
 33	struct folio_batch fbatch;
 34};
 35
 36static DEFINE_PER_CPU(struct mlock_fbatch, mlock_fbatch) = {
 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 folios are marked with the PG_mlocked flag for efficient testing
 52 * in vmscan and, possibly, the fault path; and to support semi-accurate
 53 * statistics.
 54 *
 55 * An mlocked folio [folio_test_mlocked(folio)] is unevictable.  As such, it
 56 * will be ostensibly placed on the LRU "unevictable" list (actually no such
 57 * list exists), rather than the [in]active lists. PG_unevictable is set to
 58 * indicate the unevictable state.
 59 */
 60
 61static struct lruvec *__mlock_folio(struct folio *folio, struct lruvec *lruvec)
 62{
 63	/* There is nothing more we can do while it's off LRU */
 64	if (!folio_test_clear_lru(folio))
 65		return lruvec;
 66
 67	lruvec = folio_lruvec_relock_irq(folio, lruvec);
 68
 69	if (unlikely(folio_evictable(folio))) {
 70		/*
 71		 * This is a little surprising, but quite possible: PG_mlocked
 72		 * must have got cleared already by another CPU.  Could this
 73		 * folio be unevictable?  I'm not sure, but move it now if so.
 74		 */
 75		if (folio_test_unevictable(folio)) {
 76			lruvec_del_folio(lruvec, folio);
 77			folio_clear_unevictable(folio);
 78			lruvec_add_folio(lruvec, folio);
 79
 80			__count_vm_events(UNEVICTABLE_PGRESCUED,
 81					  folio_nr_pages(folio));
 82		}
 83		goto out;
 84	}
 85
 86	if (folio_test_unevictable(folio)) {
 87		if (folio_test_mlocked(folio))
 88			folio->mlock_count++;
 89		goto out;
 90	}
 91
 92	lruvec_del_folio(lruvec, folio);
 93	folio_clear_active(folio);
 94	folio_set_unevictable(folio);
 95	folio->mlock_count = !!folio_test_mlocked(folio);
 96	lruvec_add_folio(lruvec, folio);
 97	__count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio));
 98out:
 99	folio_set_lru(folio);
100	return lruvec;
101}
102
103static struct lruvec *__mlock_new_folio(struct folio *folio, struct lruvec *lruvec)
104{
105	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
106
107	lruvec = folio_lruvec_relock_irq(folio, lruvec);
108
109	/* As above, this is a little surprising, but possible */
110	if (unlikely(folio_evictable(folio)))
111		goto out;
112
113	folio_set_unevictable(folio);
114	folio->mlock_count = !!folio_test_mlocked(folio);
115	__count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio));
116out:
117	lruvec_add_folio(lruvec, folio);
118	folio_set_lru(folio);
119	return lruvec;
120}
121
122static struct lruvec *__munlock_folio(struct folio *folio, struct lruvec *lruvec)
123{
124	int nr_pages = folio_nr_pages(folio);
125	bool isolated = false;
126
127	if (!folio_test_clear_lru(folio))
128		goto munlock;
129
130	isolated = true;
131	lruvec = folio_lruvec_relock_irq(folio, lruvec);
132
133	if (folio_test_unevictable(folio)) {
134		/* Then mlock_count is maintained, but might undercount */
135		if (folio->mlock_count)
136			folio->mlock_count--;
137		if (folio->mlock_count)
138			goto out;
139	}
140	/* else assume that was the last mlock: reclaim will fix it if not */
141
142munlock:
143	if (folio_test_clear_mlocked(folio)) {
144		__zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
145		if (isolated || !folio_test_unevictable(folio))
146			__count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);
147		else
148			__count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
149	}
150
151	/* folio_evictable() has to be checked *after* clearing Mlocked */
152	if (isolated && folio_test_unevictable(folio) && folio_evictable(folio)) {
153		lruvec_del_folio(lruvec, folio);
154		folio_clear_unevictable(folio);
155		lruvec_add_folio(lruvec, folio);
156		__count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
157	}
158out:
159	if (isolated)
160		folio_set_lru(folio);
161	return lruvec;
162}
163
164/*
165 * Flags held in the low bits of a struct folio pointer on the mlock_fbatch.
166 */
167#define LRU_FOLIO 0x1
168#define NEW_FOLIO 0x2
169static inline struct folio *mlock_lru(struct folio *folio)
170{
171	return (struct folio *)((unsigned long)folio + LRU_FOLIO);
172}
173
174static inline struct folio *mlock_new(struct folio *folio)
175{
176	return (struct folio *)((unsigned long)folio + NEW_FOLIO);
177}
178
179/*
180 * mlock_folio_batch() is derived from folio_batch_move_lru(): perhaps that can
181 * make use of such folio pointer flags in future, but for now just keep it for
182 * mlock.  We could use three separate folio batches instead, but one feels
183 * better (munlocking a full folio batch does not need to drain mlocking folio
184 * batches first).
185 */
186static void mlock_folio_batch(struct folio_batch *fbatch)
187{
188	struct lruvec *lruvec = NULL;
189	unsigned long mlock;
190	struct folio *folio;
191	int i;
192
193	for (i = 0; i < folio_batch_count(fbatch); i++) {
194		folio = fbatch->folios[i];
195		mlock = (unsigned long)folio & (LRU_FOLIO | NEW_FOLIO);
196		folio = (struct folio *)((unsigned long)folio - mlock);
197		fbatch->folios[i] = folio;
198
199		if (mlock & LRU_FOLIO)
200			lruvec = __mlock_folio(folio, lruvec);
201		else if (mlock & NEW_FOLIO)
202			lruvec = __mlock_new_folio(folio, lruvec);
203		else
204			lruvec = __munlock_folio(folio, lruvec);
205	}
206
207	if (lruvec)
208		unlock_page_lruvec_irq(lruvec);
209	folios_put(fbatch);
210}
211
212void mlock_drain_local(void)
213{
214	struct folio_batch *fbatch;
215
216	local_lock(&mlock_fbatch.lock);
217	fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
218	if (folio_batch_count(fbatch))
219		mlock_folio_batch(fbatch);
220	local_unlock(&mlock_fbatch.lock);
221}
222
223void mlock_drain_remote(int cpu)
224{
225	struct folio_batch *fbatch;
226
227	WARN_ON_ONCE(cpu_online(cpu));
228	fbatch = &per_cpu(mlock_fbatch.fbatch, cpu);
229	if (folio_batch_count(fbatch))
230		mlock_folio_batch(fbatch);
231}
232
233bool need_mlock_drain(int cpu)
234{
235	return folio_batch_count(&per_cpu(mlock_fbatch.fbatch, cpu));
236}
237
238/**
239 * mlock_folio - mlock a folio already on (or temporarily off) LRU
240 * @folio: folio to be mlocked.
241 */
242void mlock_folio(struct folio *folio)
243{
244	struct folio_batch *fbatch;
245
246	local_lock(&mlock_fbatch.lock);
247	fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
248
249	if (!folio_test_set_mlocked(folio)) {
250		int nr_pages = folio_nr_pages(folio);
251
252		zone_stat_mod_folio(folio, NR_MLOCK, nr_pages);
253		__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
254	}
255
256	folio_get(folio);
257	if (!folio_batch_add(fbatch, mlock_lru(folio)) ||
258	    folio_test_large(folio) || lru_cache_disabled())
259		mlock_folio_batch(fbatch);
260	local_unlock(&mlock_fbatch.lock);
261}
262
263/**
264 * mlock_new_folio - mlock a newly allocated folio not yet on LRU
265 * @folio: folio to be mlocked, either normal or a THP head.
266 */
267void mlock_new_folio(struct folio *folio)
268{
269	struct folio_batch *fbatch;
270	int nr_pages = folio_nr_pages(folio);
271
272	local_lock(&mlock_fbatch.lock);
273	fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
274	folio_set_mlocked(folio);
275
276	zone_stat_mod_folio(folio, NR_MLOCK, nr_pages);
277	__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
278
279	folio_get(folio);
280	if (!folio_batch_add(fbatch, mlock_new(folio)) ||
281	    folio_test_large(folio) || lru_cache_disabled())
282		mlock_folio_batch(fbatch);
283	local_unlock(&mlock_fbatch.lock);
284}
285
286/**
287 * munlock_folio - munlock a folio
288 * @folio: folio to be munlocked, either normal or a THP head.
289 */
290void munlock_folio(struct folio *folio)
291{
292	struct folio_batch *fbatch;
293
294	local_lock(&mlock_fbatch.lock);
295	fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
296	/*
297	 * folio_test_clear_mlocked(folio) must be left to __munlock_folio(),
298	 * which will check whether the folio is multiply mlocked.
299	 */
300	folio_get(folio);
301	if (!folio_batch_add(fbatch, folio) ||
302	    folio_test_large(folio) || lru_cache_disabled())
303		mlock_folio_batch(fbatch);
304	local_unlock(&mlock_fbatch.lock);
305}
306
307static inline unsigned int folio_mlock_step(struct folio *folio,
308		pte_t *pte, unsigned long addr, unsigned long end)
309{
310	const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
311	unsigned int count = (end - addr) >> PAGE_SHIFT;
312	pte_t ptent = ptep_get(pte);
313
314	if (!folio_test_large(folio))
315		return 1;
316
317	return folio_pte_batch(folio, addr, pte, ptent, count, fpb_flags, NULL,
318			       NULL, NULL);
 
 
 
 
 
 
 
 
 
 
 
319}
320
321static inline bool allow_mlock_munlock(struct folio *folio,
322		struct vm_area_struct *vma, unsigned long start,
323		unsigned long end, unsigned int step)
324{
325	/*
326	 * For unlock, allow munlock large folio which is partially
327	 * mapped to VMA. As it's possible that large folio is
328	 * mlocked and VMA is split later.
329	 *
330	 * During memory pressure, such kind of large folio can
331	 * be split. And the pages are not in VM_LOCKed VMA
332	 * can be reclaimed.
333	 */
334	if (!(vma->vm_flags & VM_LOCKED))
335		return true;
336
337	/* folio_within_range() cannot take KSM, but any small folio is OK */
338	if (!folio_test_large(folio))
339		return true;
340
341	/* folio not in range [start, end), skip mlock */
342	if (!folio_within_range(folio, vma, start, end))
343		return false;
344
345	/* folio is not fully mapped, skip mlock */
346	if (step != folio_nr_pages(folio))
347		return false;
348
349	return true;
350}
351
352static int mlock_pte_range(pmd_t *pmd, unsigned long addr,
353			   unsigned long end, struct mm_walk *walk)
354
355{
356	struct vm_area_struct *vma = walk->vma;
357	spinlock_t *ptl;
358	pte_t *start_pte, *pte;
359	pte_t ptent;
360	struct folio *folio;
361	unsigned int step = 1;
362	unsigned long start = addr;
363
364	ptl = pmd_trans_huge_lock(pmd, vma);
365	if (ptl) {
366		if (!pmd_present(*pmd))
367			goto out;
368		if (is_huge_zero_pmd(*pmd))
369			goto out;
370		folio = pmd_folio(*pmd);
371		if (vma->vm_flags & VM_LOCKED)
372			mlock_folio(folio);
373		else
374			munlock_folio(folio);
375		goto out;
376	}
377
378	start_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
379	if (!start_pte) {
380		walk->action = ACTION_AGAIN;
381		return 0;
382	}
383
384	for (pte = start_pte; addr != end; pte++, addr += PAGE_SIZE) {
385		ptent = ptep_get(pte);
386		if (!pte_present(ptent))
387			continue;
388		folio = vm_normal_folio(vma, addr, ptent);
389		if (!folio || folio_is_zone_device(folio))
390			continue;
391
392		step = folio_mlock_step(folio, pte, addr, end);
393		if (!allow_mlock_munlock(folio, vma, start, end, step))
394			goto next_entry;
395
396		if (vma->vm_flags & VM_LOCKED)
397			mlock_folio(folio);
398		else
399			munlock_folio(folio);
400
401next_entry:
402		pte += step - 1;
403		addr += (step - 1) << PAGE_SHIFT;
404	}
405	pte_unmap(start_pte);
406out:
407	spin_unlock(ptl);
408	cond_resched();
409	return 0;
410}
411
412/*
413 * mlock_vma_pages_range() - mlock any pages already in the range,
414 *                           or munlock all pages in the range.
415 * @vma - vma containing range to be mlock()ed or munlock()ed
416 * @start - start address in @vma of the range
417 * @end - end of range in @vma
418 * @newflags - the new set of flags for @vma.
419 *
420 * Called for mlock(), mlock2() and mlockall(), to set @vma VM_LOCKED;
421 * called for munlock() and munlockall(), to clear VM_LOCKED from @vma.
422 */
423static void mlock_vma_pages_range(struct vm_area_struct *vma,
424	unsigned long start, unsigned long end, vm_flags_t newflags)
425{
426	static const struct mm_walk_ops mlock_walk_ops = {
427		.pmd_entry = mlock_pte_range,
428		.walk_lock = PGWALK_WRLOCK_VERIFY,
429	};
430
431	/*
432	 * There is a slight chance that concurrent page migration,
433	 * or page reclaim finding a page of this now-VM_LOCKED vma,
434	 * will call mlock_vma_folio() and raise page's mlock_count:
435	 * double counting, leaving the page unevictable indefinitely.
436	 * Communicate this danger to mlock_vma_folio() with VM_IO,
437	 * which is a VM_SPECIAL flag not allowed on VM_LOCKED vmas.
438	 * mmap_lock is held in write mode here, so this weird
439	 * combination should not be visible to other mmap_lock users;
440	 * but WRITE_ONCE so rmap walkers must see VM_IO if VM_LOCKED.
441	 */
442	if (newflags & VM_LOCKED)
443		newflags |= VM_IO;
444	vma_start_write(vma);
445	vm_flags_reset_once(vma, newflags);
446
447	lru_add_drain();
448	walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL);
449	lru_add_drain();
450
451	if (newflags & VM_IO) {
452		newflags &= ~VM_IO;
453		vm_flags_reset_once(vma, newflags);
454	}
455}
456
457/*
458 * mlock_fixup  - handle mlock[all]/munlock[all] requests.
459 *
460 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
461 * munlock is a no-op.  However, for some special vmas, we go ahead and
462 * populate the ptes.
463 *
464 * For vmas that pass the filters, merge/split as appropriate.
465 */
466static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma,
467	       struct vm_area_struct **prev, unsigned long start,
468	       unsigned long end, vm_flags_t newflags)
469{
470	struct mm_struct *mm = vma->vm_mm;
471	int nr_pages;
472	int ret = 0;
473	vm_flags_t oldflags = vma->vm_flags;
474
475	if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
476	    is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
477	    vma_is_dax(vma) || vma_is_secretmem(vma) || (oldflags & VM_DROPPABLE))
478		/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
479		goto out;
480
481	vma = vma_modify_flags(vmi, *prev, vma, start, end, newflags);
482	if (IS_ERR(vma)) {
483		ret = PTR_ERR(vma);
484		goto out;
485	}
486
487	/*
488	 * Keep track of amount of locked VM.
489	 */
490	nr_pages = (end - start) >> PAGE_SHIFT;
491	if (!(newflags & VM_LOCKED))
492		nr_pages = -nr_pages;
493	else if (oldflags & VM_LOCKED)
494		nr_pages = 0;
495	mm->locked_vm += nr_pages;
496
497	/*
498	 * vm_flags is protected by the mmap_lock held in write mode.
499	 * It's okay if try_to_unmap_one unmaps a page just after we
500	 * set VM_LOCKED, populate_vma_page_range will bring it back.
501	 */
502	if ((newflags & VM_LOCKED) && (oldflags & VM_LOCKED)) {
503		/* No work to do, and mlocking twice would be wrong */
504		vma_start_write(vma);
505		vm_flags_reset(vma, newflags);
506	} else {
507		mlock_vma_pages_range(vma, start, end, newflags);
508	}
509out:
510	*prev = vma;
511	return ret;
512}
513
514static int apply_vma_lock_flags(unsigned long start, size_t len,
515				vm_flags_t flags)
516{
517	unsigned long nstart, end, tmp;
518	struct vm_area_struct *vma, *prev;
519	VMA_ITERATOR(vmi, current->mm, start);
520
521	VM_BUG_ON(offset_in_page(start));
522	VM_BUG_ON(len != PAGE_ALIGN(len));
523	end = start + len;
524	if (end < start)
525		return -EINVAL;
526	if (end == start)
527		return 0;
528	vma = vma_iter_load(&vmi);
529	if (!vma)
530		return -ENOMEM;
531
532	prev = vma_prev(&vmi);
533	if (start > vma->vm_start)
534		prev = vma;
535
536	nstart = start;
537	tmp = vma->vm_start;
538	for_each_vma_range(vmi, vma, end) {
539		int error;
540		vm_flags_t newflags;
541
542		if (vma->vm_start != tmp)
543			return -ENOMEM;
544
545		newflags = vma->vm_flags & ~VM_LOCKED_MASK;
546		newflags |= flags;
547		/* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
548		tmp = vma->vm_end;
549		if (tmp > end)
550			tmp = end;
551		error = mlock_fixup(&vmi, vma, &prev, nstart, tmp, newflags);
552		if (error)
553			return error;
554		tmp = vma_iter_end(&vmi);
555		nstart = tmp;
556	}
557
558	if (tmp < end)
559		return -ENOMEM;
560
561	return 0;
562}
563
564/*
565 * Go through vma areas and sum size of mlocked
566 * vma pages, as return value.
567 * Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT)
568 * is also counted.
569 * Return value: previously mlocked page counts
570 */
571static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
572		unsigned long start, size_t len)
573{
574	struct vm_area_struct *vma;
575	unsigned long count = 0;
576	unsigned long end;
577	VMA_ITERATOR(vmi, mm, start);
578
579	/* Don't overflow past ULONG_MAX */
580	if (unlikely(ULONG_MAX - len < start))
581		end = ULONG_MAX;
582	else
583		end = start + len;
584
585	for_each_vma_range(vmi, vma, end) {
586		if (vma->vm_flags & VM_LOCKED) {
587			if (start > vma->vm_start)
588				count -= (start - vma->vm_start);
589			if (end < vma->vm_end) {
590				count += end - vma->vm_start;
591				break;
592			}
593			count += vma->vm_end - vma->vm_start;
594		}
595	}
596
597	return count >> PAGE_SHIFT;
598}
599
600/*
601 * convert get_user_pages() return value to posix mlock() error
602 */
603static int __mlock_posix_error_return(long retval)
604{
605	if (retval == -EFAULT)
606		retval = -ENOMEM;
607	else if (retval == -ENOMEM)
608		retval = -EAGAIN;
609	return retval;
610}
611
612static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t flags)
613{
614	unsigned long locked;
615	unsigned long lock_limit;
616	int error = -ENOMEM;
617
618	start = untagged_addr(start);
619
620	if (!can_do_mlock())
621		return -EPERM;
622
623	len = PAGE_ALIGN(len + (offset_in_page(start)));
624	start &= PAGE_MASK;
625
626	lock_limit = rlimit(RLIMIT_MEMLOCK);
627	lock_limit >>= PAGE_SHIFT;
628	locked = len >> PAGE_SHIFT;
629
630	if (mmap_write_lock_killable(current->mm))
631		return -EINTR;
632
633	locked += current->mm->locked_vm;
634	if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) {
635		/*
636		 * It is possible that the regions requested intersect with
637		 * previously mlocked areas, that part area in "mm->locked_vm"
638		 * should not be counted to new mlock increment count. So check
639		 * and adjust locked count if necessary.
640		 */
641		locked -= count_mm_mlocked_page_nr(current->mm,
642				start, len);
643	}
644
645	/* check against resource limits */
646	if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
647		error = apply_vma_lock_flags(start, len, flags);
648
649	mmap_write_unlock(current->mm);
650	if (error)
651		return error;
652
653	error = __mm_populate(start, len, 0);
654	if (error)
655		return __mlock_posix_error_return(error);
656	return 0;
657}
658
659SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
660{
661	return do_mlock(start, len, VM_LOCKED);
662}
663
664SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
665{
666	vm_flags_t vm_flags = VM_LOCKED;
667
668	if (flags & ~MLOCK_ONFAULT)
669		return -EINVAL;
670
671	if (flags & MLOCK_ONFAULT)
672		vm_flags |= VM_LOCKONFAULT;
673
674	return do_mlock(start, len, vm_flags);
675}
676
677SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
678{
679	int ret;
680
681	start = untagged_addr(start);
682
683	len = PAGE_ALIGN(len + (offset_in_page(start)));
684	start &= PAGE_MASK;
685
686	if (mmap_write_lock_killable(current->mm))
687		return -EINTR;
688	ret = apply_vma_lock_flags(start, len, 0);
689	mmap_write_unlock(current->mm);
690
691	return ret;
692}
693
694/*
695 * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall)
696 * and translate into the appropriate modifications to mm->def_flags and/or the
697 * flags for all current VMAs.
698 *
699 * There are a couple of subtleties with this.  If mlockall() is called multiple
700 * times with different flags, the values do not necessarily stack.  If mlockall
701 * is called once including the MCL_FUTURE flag and then a second time without
702 * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags.
703 */
704static int apply_mlockall_flags(int flags)
705{
706	VMA_ITERATOR(vmi, current->mm, 0);
707	struct vm_area_struct *vma, *prev = NULL;
708	vm_flags_t to_add = 0;
709
710	current->mm->def_flags &= ~VM_LOCKED_MASK;
711	if (flags & MCL_FUTURE) {
712		current->mm->def_flags |= VM_LOCKED;
713
714		if (flags & MCL_ONFAULT)
715			current->mm->def_flags |= VM_LOCKONFAULT;
716
717		if (!(flags & MCL_CURRENT))
718			goto out;
719	}
720
721	if (flags & MCL_CURRENT) {
722		to_add |= VM_LOCKED;
723		if (flags & MCL_ONFAULT)
724			to_add |= VM_LOCKONFAULT;
725	}
726
727	for_each_vma(vmi, vma) {
728		int error;
729		vm_flags_t newflags;
730
731		newflags = vma->vm_flags & ~VM_LOCKED_MASK;
732		newflags |= to_add;
733
734		error = mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end,
735				    newflags);
736		/* Ignore errors, but prev needs fixing up. */
737		if (error)
738			prev = vma;
739		cond_resched();
740	}
741out:
742	return 0;
743}
744
745SYSCALL_DEFINE1(mlockall, int, flags)
746{
747	unsigned long lock_limit;
748	int ret;
749
750	if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) ||
751	    flags == MCL_ONFAULT)
752		return -EINVAL;
753
754	if (!can_do_mlock())
755		return -EPERM;
756
757	lock_limit = rlimit(RLIMIT_MEMLOCK);
758	lock_limit >>= PAGE_SHIFT;
759
760	if (mmap_write_lock_killable(current->mm))
761		return -EINTR;
762
763	ret = -ENOMEM;
764	if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
765	    capable(CAP_IPC_LOCK))
766		ret = apply_mlockall_flags(flags);
767	mmap_write_unlock(current->mm);
768	if (!ret && (flags & MCL_CURRENT))
769		mm_populate(0, TASK_SIZE);
770
771	return ret;
772}
773
774SYSCALL_DEFINE0(munlockall)
775{
776	int ret;
777
778	if (mmap_write_lock_killable(current->mm))
779		return -EINTR;
780	ret = apply_mlockall_flags(0);
781	mmap_write_unlock(current->mm);
782	return ret;
783}
784
785/*
786 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
787 * shm segments) get accounted against the user_struct instead.
788 */
789static DEFINE_SPINLOCK(shmlock_user_lock);
790
791int user_shm_lock(size_t size, struct ucounts *ucounts)
792{
793	unsigned long lock_limit, locked;
794	long memlock;
795	int allowed = 0;
796
797	locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
798	lock_limit = rlimit(RLIMIT_MEMLOCK);
799	if (lock_limit != RLIM_INFINITY)
800		lock_limit >>= PAGE_SHIFT;
801	spin_lock(&shmlock_user_lock);
802	memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
803
804	if ((memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) {
805		dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
806		goto out;
807	}
808	if (!get_ucounts(ucounts)) {
809		dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
810		allowed = 0;
811		goto out;
812	}
813	allowed = 1;
814out:
815	spin_unlock(&shmlock_user_lock);
816	return allowed;
817}
818
819void user_shm_unlock(size_t size, struct ucounts *ucounts)
820{
821	spin_lock(&shmlock_user_lock);
822	dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
823	spin_unlock(&shmlock_user_lock);
824	put_ucounts(ucounts);
825}