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Root/mm/mlock.c

1	/*
2	* linux/mm/mlock.c
3	*
4	* (C) Copyright 1995 Linus Torvalds
5	* (C) Copyright 2002 Christoph Hellwig
6	*/
7
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/pagevec.h>
15	#include <linux/mempolicy.h>
16	#include <linux/syscalls.h>
17	#include <linux/sched.h>
18	#include <linux/export.h>
19	#include <linux/rmap.h>
20	#include <linux/mmzone.h>
21	#include <linux/hugetlb.h>
22	#include <linux/memcontrol.h>
23	#include <linux/mm_inline.h>
24
25	#include "internal.h"
26
27	int can_do_mlock(void)
28	{
29	if (capable(CAP_IPC_LOCK))
30	return 1;
31	if (rlimit(RLIMIT_MEMLOCK) != 0)
32	return 1;
33	return 0;
34	}
35	EXPORT_SYMBOL(can_do_mlock);
36
37	/*
38	* Mlocked pages are marked with PageMlocked() flag for efficient testing
39	* in vmscan and, possibly, the fault path; and to support semi-accurate
40	* statistics.
41	*
42	* An mlocked page [PageMlocked(page)] is unevictable. As such, it will
43	* be placed on the LRU "unevictable" list, rather than the [in]active lists.
44	* The unevictable list is an LRU sibling list to the [in]active lists.
45	* PageUnevictable is set to indicate the unevictable state.
46	*
47	* When lazy mlocking via vmscan, it is important to ensure that the
48	* vma's VM_LOCKED status is not concurrently being modified, otherwise we
49	* may have mlocked a page that is being munlocked. So lazy mlock must take
50	* the mmap_sem for read, and verify that the vma really is locked
51	* (see mm/rmap.c).
52	*/
53
54	/*
55	* LRU accounting for clear_page_mlock()
56	*/
57	void clear_page_mlock(struct page *page)
58	{
59	if (!TestClearPageMlocked(page))
60	return;
61
62	mod_zone_page_state(page_zone(page), NR_MLOCK,
63	-hpage_nr_pages(page));
64	count_vm_event(UNEVICTABLE_PGCLEARED);
65	if (!isolate_lru_page(page)) {
66	putback_lru_page(page);
67	} else {
68	/*
69	* We lost the race. the page already moved to evictable list.
70	*/
71	if (PageUnevictable(page))
72	count_vm_event(UNEVICTABLE_PGSTRANDED);
73	}
74	}
75
76	/*
77	* Mark page as mlocked if not already.
78	* If page on LRU, isolate and putback to move to unevictable list.
79	*/
80	void mlock_vma_page(struct page *page)
81	{
82	BUG_ON(!PageLocked(page));
83
84	if (!TestSetPageMlocked(page)) {
85	mod_zone_page_state(page_zone(page), NR_MLOCK,
86	hpage_nr_pages(page));
87	count_vm_event(UNEVICTABLE_PGMLOCKED);
88	if (!isolate_lru_page(page))
89	putback_lru_page(page);
90	}
91	}
92
93	/*
94	* Finish munlock after successful page isolation
95	*
96	* Page must be locked. This is a wrapper for try_to_munlock()
97	* and putback_lru_page() with munlock accounting.
98	*/
99	static void __munlock_isolated_page(struct page *page)
100	{
101	int ret = SWAP_AGAIN;
102
103	/*
104	* Optimization: if the page was mapped just once, that's our mapping
105	* and we don't need to check all the other vmas.
106	*/
107	if (page_mapcount(page) > 1)
108	ret = try_to_munlock(page);
109
110	/* Did try_to_unlock() succeed or punt? */
111	if (ret != SWAP_MLOCK)
112	count_vm_event(UNEVICTABLE_PGMUNLOCKED);
113
114	putback_lru_page(page);
115	}
116
117	/*
118	* Accounting for page isolation fail during munlock
119	*
120	* Performs accounting when page isolation fails in munlock. There is nothing
121	* else to do because it means some other task has already removed the page
122	* from the LRU. putback_lru_page() will take care of removing the page from
123	* the unevictable list, if necessary. vmscan [page_referenced()] will move
124	* the page back to the unevictable list if some other vma has it mlocked.
125	*/
126	static void __munlock_isolation_failed(struct page *page)
127	{
128	if (PageUnevictable(page))
129	count_vm_event(UNEVICTABLE_PGSTRANDED);
130	else
131	count_vm_event(UNEVICTABLE_PGMUNLOCKED);
132	}
133
134	/**
135	* munlock_vma_page - munlock a vma page
136	* @page - page to be unlocked
137	*
138	* called from munlock()/munmap() path with page supposedly on the LRU.
139	* When we munlock a page, because the vma where we found the page is being
140	* munlock()ed or munmap()ed, we want to check whether other vmas hold the
141	* page locked so that we can leave it on the unevictable lru list and not
142	* bother vmscan with it. However, to walk the page's rmap list in
143	* try_to_munlock() we must isolate the page from the LRU. If some other
144	* task has removed the page from the LRU, we won't be able to do that.
145	* So we clear the PageMlocked as we might not get another chance. If we
146	* can't isolate the page, we leave it for putback_lru_page() and vmscan
147	* [page_referenced()/try_to_unmap()] to deal with.
148	*/
149	unsigned int munlock_vma_page(struct page *page)
150	{
151	unsigned int page_mask = 0;
152
153	BUG_ON(!PageLocked(page));
154
155	if (TestClearPageMlocked(page)) {
156	unsigned int nr_pages = hpage_nr_pages(page);
157	mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
158	page_mask = nr_pages - 1;
159	if (!isolate_lru_page(page))
160	__munlock_isolated_page(page);
161	else
162	__munlock_isolation_failed(page);
163	}
164
165	return page_mask;
166	}
167
168	/**
169	* __mlock_vma_pages_range() - mlock a range of pages in the vma.
170	* @vma: target vma
171	* @start: start address
172	* @end: end address
173	*
174	* This takes care of making the pages present too.
175	*
176	* return 0 on success, negative error code on error.
177	*
178	* vma->vm_mm->mmap_sem must be held for at least read.
179	*/
180	long __mlock_vma_pages_range(struct vm_area_struct *vma,
181	unsigned long start, unsigned long end, int *nonblocking)
182	{
183	struct mm_struct *mm = vma->vm_mm;
184	unsigned long nr_pages = (end - start) / PAGE_SIZE;
185	int gup_flags;
186
187	VM_BUG_ON(start & ~PAGE_MASK);
188	VM_BUG_ON(end & ~PAGE_MASK);
189	VM_BUG_ON(start < vma->vm_start);
190	VM_BUG_ON(end > vma->vm_end);
191	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
192
193	gup_flags = FOLL_TOUCH \| FOLL_MLOCK;
194	/*
195	* We want to touch writable mappings with a write fault in order
196	* to break COW, except for shared mappings because these don't COW
197	* and we would not want to dirty them for nothing.
198	*/
199	if ((vma->vm_flags & (VM_WRITE \| VM_SHARED)) == VM_WRITE)
200	gup_flags \|= FOLL_WRITE;
201
202	/*
203	* We want mlock to succeed for regions that have any permissions
204	* other than PROT_NONE.
205	*/
206	if (vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC))
207	gup_flags \|= FOLL_FORCE;
208
209	/*
210	* We made sure addr is within a VMA, so the following will
211	* not result in a stack expansion that recurses back here.
212	*/
213	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
214	NULL, NULL, nonblocking);
215	}
216
217	/*
218	* convert get_user_pages() return value to posix mlock() error
219	*/
220	static int __mlock_posix_error_return(long retval)
221	{
222	if (retval == -EFAULT)
223	retval = -ENOMEM;
224	else if (retval == -ENOMEM)
225	retval = -EAGAIN;
226	return retval;
227	}
228
229	/*
230	* Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
231	*
232	* The fast path is available only for evictable pages with single mapping.
233	* Then we can bypass the per-cpu pvec and get better performance.
234	* when mapcount > 1 we need try_to_munlock() which can fail.
235	* when !page_evictable(), we need the full redo logic of putback_lru_page to
236	* avoid leaving evictable page in unevictable list.
237	*
238	* In case of success, @page is added to @pvec and @pgrescued is incremented
239	* in case that the page was previously unevictable. @page is also unlocked.
240	*/
241	static bool __putback_lru_fast_prepare(struct page page, struct pagevec pvec,
242	int *pgrescued)
243	{
244	VM_BUG_ON(PageLRU(page));
245	VM_BUG_ON(!PageLocked(page));
246
247	if (page_mapcount(page) <= 1 && page_evictable(page)) {
248	pagevec_add(pvec, page);
249	if (TestClearPageUnevictable(page))
250	(*pgrescued)++;
251	unlock_page(page);
252	return true;
253	}
254
255	return false;
256	}
257
258	/*
259	* Putback multiple evictable pages to the LRU
260	*
261	* Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
262	* the pages might have meanwhile become unevictable but that is OK.
263	*/
264	static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
265	{
266	count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
267	/*
268	*__pagevec_lru_add() calls release_pages() so we don't call
269	* put_page() explicitly
270	*/
271	__pagevec_lru_add(pvec);
272	count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
273	}
274
275	/*
276	* Munlock a batch of pages from the same zone
277	*
278	* The work is split to two main phases. First phase clears the Mlocked flag
279	* and attempts to isolate the pages, all under a single zone lru lock.
280	* The second phase finishes the munlock only for pages where isolation
281	* succeeded.
282	*
283	* Note that the pagevec may be modified during the process.
284	*/
285	static void __munlock_pagevec(struct pagevec pvec, struct zone zone)
286	{
287	int i;
288	int nr = pagevec_count(pvec);
289	int delta_munlocked = -nr;
290	struct pagevec pvec_putback;
291	int pgrescued = 0;
292
293	/* Phase 1: page isolation */
294	spin_lock_irq(&zone->lru_lock);
295	for (i = 0; i < nr; i++) {
296	struct page *page = pvec->pages[i];
297
298	if (TestClearPageMlocked(page)) {
299	struct lruvec *lruvec;
300	int lru;
301
302	if (PageLRU(page)) {
303	lruvec = mem_cgroup_page_lruvec(page, zone);
304	lru = page_lru(page);
305	/*
306	* We already have pin from follow_page_mask()
307	* so we can spare the get_page() here.
308	*/
309	ClearPageLRU(page);
310	del_page_from_lru_list(page, lruvec, lru);
311	} else {
312	__munlock_isolation_failed(page);
313	goto skip_munlock;
314	}
315
316	} else {
317	skip_munlock:
318	/*
319	* We won't be munlocking this page in the next phase
320	* but we still need to release the follow_page_mask()
321	* pin.
322	*/
323	pvec->pages[i] = NULL;
324	put_page(page);
325	delta_munlocked++;
326	}
327	}
328	__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
329	spin_unlock_irq(&zone->lru_lock);
330
331	/* Phase 2: page munlock */
332	pagevec_init(&pvec_putback, 0);
333	for (i = 0; i < nr; i++) {
334	struct page *page = pvec->pages[i];
335
336	if (page) {
337	lock_page(page);
338	if (!__putback_lru_fast_prepare(page, &pvec_putback,
339	&pgrescued)) {
340	/*
341	* Slow path. We don't want to lose the last
342	* pin before unlock_page()
343	*/
344	get_page(page); /* for putback_lru_page() */
345	__munlock_isolated_page(page);
346	unlock_page(page);
347	put_page(page); /* from follow_page_mask() */
348	}
349	}
350	}
351
352	/*
353	* Phase 3: page putback for pages that qualified for the fast path
354	* This will also call put_page() to return pin from follow_page_mask()
355	*/
356	if (pagevec_count(&pvec_putback))
357	__putback_lru_fast(&pvec_putback, pgrescued);
358	}
359
360	/*
361	* Fill up pagevec for __munlock_pagevec using pte walk
362	*
363	* The function expects that the struct page corresponding to @start address is
364	* a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
365	*
366	* The rest of @pvec is filled by subsequent pages within the same pmd and same
367	* zone, as long as the pte's are present and vm_normal_page() succeeds. These
368	* pages also get pinned.
369	*
370	* Returns the address of the next page that should be scanned. This equals
371	* @start + PAGE_SIZE when no page could be added by the pte walk.
372	*/
373	static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
374	struct vm_area_struct *vma, int zoneid, unsigned long start,
375	unsigned long end)
376	{
377	pte_t *pte;
378	spinlock_t *ptl;
379
380	/*
381	* Initialize pte walk starting at the already pinned page where we
382	* are sure that there is a pte, as it was pinned under the same
383	* mmap_sem write op.
384	*/
385	pte = get_locked_pte(vma->vm_mm, start, &ptl);
386	/* Make sure we do not cross the page table boundary */
387	end = pgd_addr_end(start, end);
388	end = pud_addr_end(start, end);
389	end = pmd_addr_end(start, end);
390
391	/* The page next to the pinned page is the first we will try to get */
392	start += PAGE_SIZE;
393	while (start < end) {
394	struct page *page = NULL;
395	pte++;
396	if (pte_present(*pte))
397	page = vm_normal_page(vma, start, *pte);
398	/*
399	* Break if page could not be obtained or the page's node+zone does not
400	* match
401	*/
402	if (!page \|\| page_zone_id(page) != zoneid)
403	break;
404
405	get_page(page);
406	/*
407	* Increase the address that will be returned before the
408	* eventual break due to pvec becoming full by adding the page
409	*/
410	start += PAGE_SIZE;
411	if (pagevec_add(pvec, page) == 0)
412	break;
413	}
414	pte_unmap_unlock(pte, ptl);
415	return start;
416	}
417
418	/*
419	* munlock_vma_pages_range() - munlock all pages in the vma range.'
420	* @vma - vma containing range to be munlock()ed.
421	* @start - start address in @vma of the range
422	* @end - end of range in @vma.
423	*
424	* For mremap(), munmap() and exit().
425	*
426	* Called with @vma VM_LOCKED.
427	*
428	* Returns with VM_LOCKED cleared. Callers must be prepared to
429	* deal with this.
430	*
431	* We don't save and restore VM_LOCKED here because pages are
432	* still on lru. In unmap path, pages might be scanned by reclaim
433	* and re-mlocked by try_to_{munlock\|unmap} before we unmap and
434	* free them. This will result in freeing mlocked pages.
435	*/
436	void munlock_vma_pages_range(struct vm_area_struct *vma,
437	unsigned long start, unsigned long end)
438	{
439	vma->vm_flags &= ~VM_LOCKED;
440
441	while (start < end) {
442	struct page *page = NULL;
443	unsigned int page_mask, page_increm;
444	struct pagevec pvec;
445	struct zone *zone;
446	int zoneid;
447
448	pagevec_init(&pvec, 0);
449	/*
450	* Although FOLL_DUMP is intended for get_dump_page(),
451	* it just so happens that its special treatment of the
452	* ZERO_PAGE (returning an error instead of doing get_page)
453	* suits munlock very well (and if somehow an abnormal page
454	* has sneaked into the range, we won't oops here: great).
455	*/
456	page = follow_page_mask(vma, start, FOLL_GET \| FOLL_DUMP,
457	&page_mask);
458
459	if (page && !IS_ERR(page)) {
460	if (PageTransHuge(page)) {
461	lock_page(page);
462	/*
463	* Any THP page found by follow_page_mask() may
464	* have gotten split before reaching
465	* munlock_vma_page(), so we need to recompute
466	* the page_mask here.
467	*/
468	page_mask = munlock_vma_page(page);
469	unlock_page(page);
470	put_page(page); /* follow_page_mask() */
471	} else {
472	/*
473	* Non-huge pages are handled in batches via
474	* pagevec. The pin from follow_page_mask()
475	* prevents them from collapsing by THP.
476	*/
477	pagevec_add(&pvec, page);
478	zone = page_zone(page);
479	zoneid = page_zone_id(page);
480
481	/*
482	* Try to fill the rest of pagevec using fast
483	* pte walk. This will also update start to
484	* the next page to process. Then munlock the
485	* pagevec.
486	*/
487	start = __munlock_pagevec_fill(&pvec, vma,
488	zoneid, start, end);
489	__munlock_pagevec(&pvec, zone);
490	goto next;
491	}
492	}
493	page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
494	start += page_increm * PAGE_SIZE;
495	next:
496	cond_resched();
497	}
498	}
499
500	/*
501	* mlock_fixup - handle mlock[all]/munlock[all] requests.
502	*
503	* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
504	* munlock is a no-op. However, for some special vmas, we go ahead and
505	* populate the ptes.
506	*
507	* For vmas that pass the filters, merge/split as appropriate.
508	*/
509	static int mlock_fixup(struct vm_area_struct vma, struct vm_area_struct *prev,
510	unsigned long start, unsigned long end, vm_flags_t newflags)
511	{
512	struct mm_struct *mm = vma->vm_mm;
513	pgoff_t pgoff;
514	int nr_pages;
515	int ret = 0;
516	int lock = !!(newflags & VM_LOCKED);
517
518	if (newflags == vma->vm_flags \|\| (vma->vm_flags & VM_SPECIAL) \|\|
519	is_vm_hugetlb_page(vma) \|\| vma == get_gate_vma(current->mm))
520	goto out; /* don't set VM_LOCKED, don't count */
521
522	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
523	prev = vma_merge(mm, prev, start, end, newflags, vma->anon_vma,
524	vma->vm_file, pgoff, vma_policy(vma));
525	if (*prev) {
526	vma = *prev;
527	goto success;
528	}
529
530	if (start != vma->vm_start) {
531	ret = split_vma(mm, vma, start, 1);
532	if (ret)
533	goto out;
534	}
535
536	if (end != vma->vm_end) {
537	ret = split_vma(mm, vma, end, 0);
538	if (ret)
539	goto out;
540	}
541
542	success:
543	/*
544	* Keep track of amount of locked VM.
545	*/
546	nr_pages = (end - start) >> PAGE_SHIFT;
547	if (!lock)
548	nr_pages = -nr_pages;
549	mm->locked_vm += nr_pages;
550
551	/*
552	* vm_flags is protected by the mmap_sem held in write mode.
553	* It's okay if try_to_unmap_one unmaps a page just after we
554	* set VM_LOCKED, __mlock_vma_pages_range will bring it back.
555	*/
556
557	if (lock)
558	vma->vm_flags = newflags;
559	else
560	munlock_vma_pages_range(vma, start, end);
561
562	out:
563	*prev = vma;
564	return ret;
565	}
566
567	static int do_mlock(unsigned long start, size_t len, int on)
568	{
569	unsigned long nstart, end, tmp;
570	struct vm_area_struct * vma, * prev;
571	int error;
572
573	VM_BUG_ON(start & ~PAGE_MASK);
574	VM_BUG_ON(len != PAGE_ALIGN(len));
575	end = start + len;
576	if (end < start)
577	return -EINVAL;
578	if (end == start)
579	return 0;
580	vma = find_vma(current->mm, start);
581	if (!vma \|\| vma->vm_start > start)
582	return -ENOMEM;
583
584	prev = vma->vm_prev;
585	if (start > vma->vm_start)
586	prev = vma;
587
588	for (nstart = start ; ; ) {
589	vm_flags_t newflags;
590
591	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
592
593	newflags = vma->vm_flags & ~VM_LOCKED;
594	if (on)
595	newflags \|= VM_LOCKED;
596
597	tmp = vma->vm_end;
598	if (tmp > end)
599	tmp = end;
600	error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
601	if (error)
602	break;
603	nstart = tmp;
604	if (nstart < prev->vm_end)
605	nstart = prev->vm_end;
606	if (nstart >= end)
607	break;
608
609	vma = prev->vm_next;
610	if (!vma \|\| vma->vm_start != nstart) {
611	error = -ENOMEM;
612	break;
613	}
614	}
615	return error;
616	}
617
618	/*
619	* __mm_populate - populate and/or mlock pages within a range of address space.
620	*
621	* This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
622	* flags. VMAs must be already marked with the desired vm_flags, and
623	* mmap_sem must not be held.
624	*/
625	int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
626	{
627	struct mm_struct *mm = current->mm;
628	unsigned long end, nstart, nend;
629	struct vm_area_struct *vma = NULL;
630	int locked = 0;
631	long ret = 0;
632
633	VM_BUG_ON(start & ~PAGE_MASK);
634	VM_BUG_ON(len != PAGE_ALIGN(len));
635	end = start + len;
636
637	for (nstart = start; nstart < end; nstart = nend) {
638	/*
639	* We want to fault in pages for [nstart; end) address range.
640	* Find first corresponding VMA.
641	*/
642	if (!locked) {
643	locked = 1;
644	down_read(&mm->mmap_sem);
645	vma = find_vma(mm, nstart);
646	} else if (nstart >= vma->vm_end)
647	vma = vma->vm_next;
648	if (!vma \|\| vma->vm_start >= end)
649	break;
650	/*
651	* Set [nstart; nend) to intersection of desired address
652	* range with the first VMA. Also, skip undesirable VMA types.
653	*/
654	nend = min(end, vma->vm_end);
655	if (vma->vm_flags & (VM_IO \| VM_PFNMAP))
656	continue;
657	if (nstart < vma->vm_start)
658	nstart = vma->vm_start;
659	/*
660	* Now fault in a range of pages. __mlock_vma_pages_range()
661	* double checks the vma flags, so that it won't mlock pages
662	* if the vma was already munlocked.
663	*/
664	ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
665	if (ret < 0) {
666	if (ignore_errors) {
667	ret = 0;
668	continue; /* continue at next VMA */
669	}
670	ret = __mlock_posix_error_return(ret);
671	break;
672	}
673	nend = nstart + ret * PAGE_SIZE;
674	ret = 0;
675	}
676	if (locked)
677	up_read(&mm->mmap_sem);
678	return ret; /* 0 or negative error code */
679	}
680
681	SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
682	{
683	unsigned long locked;
684	unsigned long lock_limit;
685	int error = -ENOMEM;
686
687	if (!can_do_mlock())
688	return -EPERM;
689
690	lru_add_drain_all(); /* flush pagevec */
691
692	down_write(&current->mm->mmap_sem);
693	len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
694	start &= PAGE_MASK;
695
696	locked = len >> PAGE_SHIFT;
697	locked += current->mm->locked_vm;
698
699	lock_limit = rlimit(RLIMIT_MEMLOCK);
700	lock_limit >>= PAGE_SHIFT;
701
702	/* check against resource limits */
703	if ((locked <= lock_limit) \|\| capable(CAP_IPC_LOCK))
704	error = do_mlock(start, len, 1);
705	up_write(&current->mm->mmap_sem);
706	if (!error)
707	error = __mm_populate(start, len, 0);
708	return error;
709	}
710
711	SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
712	{
713	int ret;
714
715	down_write(&current->mm->mmap_sem);
716	len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
717	start &= PAGE_MASK;
718	ret = do_mlock(start, len, 0);
719	up_write(&current->mm->mmap_sem);
720	return ret;
721	}
722
723	static int do_mlockall(int flags)
724	{
725	struct vm_area_struct * vma, * prev = NULL;
726
727	if (flags & MCL_FUTURE)
728	current->mm->def_flags \|= VM_LOCKED;
729	else
730	current->mm->def_flags &= ~VM_LOCKED;
731	if (flags == MCL_FUTURE)
732	goto out;
733
734	for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
735	vm_flags_t newflags;
736
737	newflags = vma->vm_flags & ~VM_LOCKED;
738	if (flags & MCL_CURRENT)
739	newflags \|= VM_LOCKED;
740
741	/* Ignore errors */
742	mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
743	cond_resched();
744	}
745	out:
746	return 0;
747	}
748
749	SYSCALL_DEFINE1(mlockall, int, flags)
750	{
751	unsigned long lock_limit;
752	int ret = -EINVAL;
753
754	if (!flags \|\| (flags & ~(MCL_CURRENT \| MCL_FUTURE)))
755	goto out;
756
757	ret = -EPERM;
758	if (!can_do_mlock())
759	goto out;
760
761	if (flags & MCL_CURRENT)
762	lru_add_drain_all(); /* flush pagevec */
763
764	down_write(&current->mm->mmap_sem);
765
766	lock_limit = rlimit(RLIMIT_MEMLOCK);
767	lock_limit >>= PAGE_SHIFT;
768
769	ret = -ENOMEM;
770	if (!(flags & MCL_CURRENT) \|\| (current->mm->total_vm <= lock_limit) \|\|
771	capable(CAP_IPC_LOCK))
772	ret = do_mlockall(flags);
773	up_write(&current->mm->mmap_sem);
774	if (!ret && (flags & MCL_CURRENT))
775	mm_populate(0, TASK_SIZE);
776	out:
777	return ret;
778	}
779
780	SYSCALL_DEFINE0(munlockall)
781	{
782	int ret;
783
784	down_write(&current->mm->mmap_sem);
785	ret = do_mlockall(0);
786	up_write(&current->mm->mmap_sem);
787	return ret;
788	}
789
790	/*
791	* Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
792	* shm segments) get accounted against the user_struct instead.
793	*/
794	static DEFINE_SPINLOCK(shmlock_user_lock);
795
796	int user_shm_lock(size_t size, struct user_struct *user)
797	{
798	unsigned long lock_limit, locked;
799	int allowed = 0;
800
801	locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
802	lock_limit = rlimit(RLIMIT_MEMLOCK);
803	if (lock_limit == RLIM_INFINITY)
804	allowed = 1;
805	lock_limit >>= PAGE_SHIFT;
806	spin_lock(&shmlock_user_lock);
807	if (!allowed &&
808	locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
809	goto out;
810	get_uid(user);
811	user->locked_shm += locked;
812	allowed = 1;
813	out:
814	spin_unlock(&shmlock_user_lock);
815	return allowed;
816	}
817
818	void user_shm_unlock(size_t size, struct user_struct *user)
819	{
820	spin_lock(&shmlock_user_lock);
821	user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
822	spin_unlock(&shmlock_user_lock);
823	free_uid(user);
824	}
825

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