blob: c3924c7f00bead9d027b222e478a6a97462ac4c3 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/mlock.c
3 *
4 * (C) Copyright 1995 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 */
7
Randy.Dunlapc59ede72006-01-11 12:17:46 -08008#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/mman.h>
10#include <linux/mm.h>
Nick Pigginb291f002008-10-18 20:26:44 -070011#include <linux/swap.h>
12#include <linux/swapops.h>
13#include <linux/pagemap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/mempolicy.h>
15#include <linux/syscalls.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040016#include <linux/sched.h>
17#include <linux/module.h>
Nick Pigginb291f002008-10-18 20:26:44 -070018#include <linux/rmap.h>
19#include <linux/mmzone.h>
20#include <linux/hugetlb.h>
21
22#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040024int can_do_mlock(void)
25{
26 if (capable(CAP_IPC_LOCK))
27 return 1;
Jiri Slaby59e99e52010-03-05 13:41:44 -080028 if (rlimit(RLIMIT_MEMLOCK) != 0)
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040029 return 1;
30 return 0;
31}
32EXPORT_SYMBOL(can_do_mlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
Nick Pigginb291f002008-10-18 20:26:44 -070034/*
35 * Mlocked pages are marked with PageMlocked() flag for efficient testing
36 * in vmscan and, possibly, the fault path; and to support semi-accurate
37 * statistics.
38 *
39 * An mlocked page [PageMlocked(page)] is unevictable. As such, it will
40 * be placed on the LRU "unevictable" list, rather than the [in]active lists.
41 * The unevictable list is an LRU sibling list to the [in]active lists.
42 * PageUnevictable is set to indicate the unevictable state.
43 *
44 * When lazy mlocking via vmscan, it is important to ensure that the
45 * vma's VM_LOCKED status is not concurrently being modified, otherwise we
46 * may have mlocked a page that is being munlocked. So lazy mlock must take
47 * the mmap_sem for read, and verify that the vma really is locked
48 * (see mm/rmap.c).
49 */
50
51/*
52 * LRU accounting for clear_page_mlock()
53 */
54void __clear_page_mlock(struct page *page)
55{
56 VM_BUG_ON(!PageLocked(page));
57
58 if (!page->mapping) { /* truncated ? */
59 return;
60 }
61
Nick Piggin5344b7e2008-10-18 20:26:51 -070062 dec_zone_page_state(page, NR_MLOCK);
63 count_vm_event(UNEVICTABLE_PGCLEARED);
Nick Pigginb291f002008-10-18 20:26:44 -070064 if (!isolate_lru_page(page)) {
65 putback_lru_page(page);
66 } else {
67 /*
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -080068 * We lost the race. the page already moved to evictable list.
Nick Pigginb291f002008-10-18 20:26:44 -070069 */
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -080070 if (PageUnevictable(page))
Nick Piggin5344b7e2008-10-18 20:26:51 -070071 count_vm_event(UNEVICTABLE_PGSTRANDED);
Nick Pigginb291f002008-10-18 20:26:44 -070072 }
73}
74
75/*
76 * Mark page as mlocked if not already.
77 * If page on LRU, isolate and putback to move to unevictable list.
78 */
79void mlock_vma_page(struct page *page)
80{
81 BUG_ON(!PageLocked(page));
82
Nick Piggin5344b7e2008-10-18 20:26:51 -070083 if (!TestSetPageMlocked(page)) {
84 inc_zone_page_state(page, NR_MLOCK);
85 count_vm_event(UNEVICTABLE_PGMLOCKED);
86 if (!isolate_lru_page(page))
87 putback_lru_page(page);
88 }
Nick Pigginb291f002008-10-18 20:26:44 -070089}
90
Lee Schermerhorn6927c1d2009-12-14 17:59:55 -080091/**
92 * munlock_vma_page - munlock a vma page
93 * @page - page to be unlocked
Nick Pigginb291f002008-10-18 20:26:44 -070094 *
Lee Schermerhorn6927c1d2009-12-14 17:59:55 -080095 * called from munlock()/munmap() path with page supposedly on the LRU.
96 * When we munlock a page, because the vma where we found the page is being
97 * munlock()ed or munmap()ed, we want to check whether other vmas hold the
98 * page locked so that we can leave it on the unevictable lru list and not
99 * bother vmscan with it. However, to walk the page's rmap list in
100 * try_to_munlock() we must isolate the page from the LRU. If some other
101 * task has removed the page from the LRU, we won't be able to do that.
102 * So we clear the PageMlocked as we might not get another chance. If we
103 * can't isolate the page, we leave it for putback_lru_page() and vmscan
104 * [page_referenced()/try_to_unmap()] to deal with.
Nick Pigginb291f002008-10-18 20:26:44 -0700105 */
Hugh Dickins73848b42009-12-14 17:59:22 -0800106void munlock_vma_page(struct page *page)
Nick Pigginb291f002008-10-18 20:26:44 -0700107{
108 BUG_ON(!PageLocked(page));
109
Nick Piggin5344b7e2008-10-18 20:26:51 -0700110 if (TestClearPageMlocked(page)) {
111 dec_zone_page_state(page, NR_MLOCK);
112 if (!isolate_lru_page(page)) {
113 int ret = try_to_munlock(page);
114 /*
115 * did try_to_unlock() succeed or punt?
116 */
Hugh Dickins53f79ac2009-12-14 17:58:58 -0800117 if (ret != SWAP_MLOCK)
Nick Piggin5344b7e2008-10-18 20:26:51 -0700118 count_vm_event(UNEVICTABLE_PGMUNLOCKED);
119
120 putback_lru_page(page);
121 } else {
122 /*
Lee Schermerhorn6927c1d2009-12-14 17:59:55 -0800123 * Some other task has removed the page from the LRU.
124 * putback_lru_page() will take care of removing the
125 * page from the unevictable list, if necessary.
126 * vmscan [page_referenced()] will move the page back
127 * to the unevictable list if some other vma has it
128 * mlocked.
Nick Piggin5344b7e2008-10-18 20:26:51 -0700129 */
130 if (PageUnevictable(page))
131 count_vm_event(UNEVICTABLE_PGSTRANDED);
132 else
133 count_vm_event(UNEVICTABLE_PGMUNLOCKED);
134 }
Nick Pigginb291f002008-10-18 20:26:44 -0700135 }
136}
137
Linus Torvalds77983302010-08-20 16:39:25 -0700138static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
139{
140 return (vma->vm_flags & VM_GROWSDOWN) &&
141 (vma->vm_start == addr) &&
142 !vma_stack_continue(vma->vm_prev, addr);
143}
144
Rik van Rielba470de2008-10-18 20:26:50 -0700145/**
Hugh Dickins408e82b2009-09-21 17:03:23 -0700146 * __mlock_vma_pages_range() - mlock a range of pages in the vma.
Rik van Rielba470de2008-10-18 20:26:50 -0700147 * @vma: target vma
148 * @start: start address
149 * @end: end address
Nick Pigginb291f002008-10-18 20:26:44 -0700150 *
Hugh Dickins408e82b2009-09-21 17:03:23 -0700151 * This takes care of making the pages present too.
Nick Pigginb291f002008-10-18 20:26:44 -0700152 *
Rik van Rielba470de2008-10-18 20:26:50 -0700153 * return 0 on success, negative error code on error.
154 *
155 * vma->vm_mm->mmap_sem must be held for at least read.
Nick Pigginb291f002008-10-18 20:26:44 -0700156 */
Rik van Rielba470de2008-10-18 20:26:50 -0700157static long __mlock_vma_pages_range(struct vm_area_struct *vma,
Michel Lespinasse53a77062011-01-13 15:46:14 -0800158 unsigned long start, unsigned long end,
159 int *nonblocking)
Nick Pigginb291f002008-10-18 20:26:44 -0700160{
161 struct mm_struct *mm = vma->vm_mm;
162 unsigned long addr = start;
Nick Pigginb291f002008-10-18 20:26:44 -0700163 int nr_pages = (end - start) / PAGE_SIZE;
Hugh Dickins408e82b2009-09-21 17:03:23 -0700164 int gup_flags;
Nick Pigginb291f002008-10-18 20:26:44 -0700165
Rik van Rielba470de2008-10-18 20:26:50 -0700166 VM_BUG_ON(start & ~PAGE_MASK);
167 VM_BUG_ON(end & ~PAGE_MASK);
168 VM_BUG_ON(start < vma->vm_start);
169 VM_BUG_ON(end > vma->vm_end);
Hugh Dickins408e82b2009-09-21 17:03:23 -0700170 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
Rik van Rielba470de2008-10-18 20:26:50 -0700171
Michel Lespinasse5fdb2002011-01-13 15:46:12 -0800172 gup_flags = FOLL_TOUCH;
Michel Lespinasse5ecfda02011-01-13 15:46:09 -0800173 /*
174 * We want to touch writable mappings with a write fault in order
175 * to break COW, except for shared mappings because these don't COW
176 * and we would not want to dirty them for nothing.
177 */
178 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
Hugh Dickins58fa8792009-09-21 17:03:31 -0700179 gup_flags |= FOLL_WRITE;
Nick Pigginb291f002008-10-18 20:26:44 -0700180
Michel Lespinassefdf4c582011-01-31 17:03:41 -0800181 /*
182 * We want mlock to succeed for regions that have any permissions
183 * other than PROT_NONE.
184 */
185 if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
186 gup_flags |= FOLL_FORCE;
187
Michel Lespinasse5fdb2002011-01-13 15:46:12 -0800188 if (vma->vm_flags & VM_LOCKED)
189 gup_flags |= FOLL_MLOCK;
190
Linus Torvaldsd7824372010-08-15 11:35:52 -0700191 /* We don't try to access the guard page of a stack vma */
Linus Torvalds77983302010-08-20 16:39:25 -0700192 if (stack_guard_page(vma, start)) {
193 addr += PAGE_SIZE;
194 nr_pages--;
Linus Torvaldsd7824372010-08-15 11:35:52 -0700195 }
196
Michel Lespinasse53a77062011-01-13 15:46:14 -0800197 return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
198 NULL, NULL, nonblocking);
Lee Schermerhorn9978ad52008-10-18 20:26:56 -0700199}
200
201/*
202 * convert get_user_pages() return value to posix mlock() error
203 */
204static int __mlock_posix_error_return(long retval)
205{
206 if (retval == -EFAULT)
207 retval = -ENOMEM;
208 else if (retval == -ENOMEM)
209 retval = -EAGAIN;
210 return retval;
Nick Pigginb291f002008-10-18 20:26:44 -0700211}
212
Rik van Rielba470de2008-10-18 20:26:50 -0700213/**
214 * mlock_vma_pages_range() - mlock pages in specified vma range.
215 * @vma - the vma containing the specfied address range
216 * @start - starting address in @vma to mlock
217 * @end - end address [+1] in @vma to mlock
218 *
219 * For mmap()/mremap()/expansion of mlocked vma.
220 *
221 * return 0 on success for "normal" vmas.
222 *
223 * return number of pages [> 0] to be removed from locked_vm on success
224 * of "special" vmas.
Nick Pigginb291f002008-10-18 20:26:44 -0700225 */
Rik van Rielba470de2008-10-18 20:26:50 -0700226long mlock_vma_pages_range(struct vm_area_struct *vma,
Nick Pigginb291f002008-10-18 20:26:44 -0700227 unsigned long start, unsigned long end)
228{
229 int nr_pages = (end - start) / PAGE_SIZE;
230 BUG_ON(!(vma->vm_flags & VM_LOCKED));
231
232 /*
233 * filter unlockable vmas
234 */
235 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
236 goto no_mlock;
237
238 if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
239 is_vm_hugetlb_page(vma) ||
Lee Schermerhorn8edb08c2008-10-18 20:26:49 -0700240 vma == get_gate_vma(current))) {
Rik van Rielba470de2008-10-18 20:26:50 -0700241
Michel Lespinasse53a77062011-01-13 15:46:14 -0800242 __mlock_vma_pages_range(vma, start, end, NULL);
Hugh Dickinsd5b56232009-02-08 20:56:58 +0000243
244 /* Hide errors from mmap() and other callers */
245 return 0;
Lee Schermerhorn8edb08c2008-10-18 20:26:49 -0700246 }
Nick Pigginb291f002008-10-18 20:26:44 -0700247
248 /*
249 * User mapped kernel pages or huge pages:
250 * make these pages present to populate the ptes, but
251 * fall thru' to reset VM_LOCKED--no need to unlock, and
252 * return nr_pages so these don't get counted against task's
253 * locked limit. huge pages are already counted against
254 * locked vm limit.
255 */
256 make_pages_present(start, end);
257
258no_mlock:
259 vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
Rik van Rielba470de2008-10-18 20:26:50 -0700260 return nr_pages; /* error or pages NOT mlocked */
Nick Pigginb291f002008-10-18 20:26:44 -0700261}
262
Nick Pigginb291f002008-10-18 20:26:44 -0700263/*
Rik van Rielba470de2008-10-18 20:26:50 -0700264 * munlock_vma_pages_range() - munlock all pages in the vma range.'
265 * @vma - vma containing range to be munlock()ed.
266 * @start - start address in @vma of the range
267 * @end - end of range in @vma.
268 *
269 * For mremap(), munmap() and exit().
270 *
271 * Called with @vma VM_LOCKED.
272 *
273 * Returns with VM_LOCKED cleared. Callers must be prepared to
274 * deal with this.
275 *
276 * We don't save and restore VM_LOCKED here because pages are
277 * still on lru. In unmap path, pages might be scanned by reclaim
278 * and re-mlocked by try_to_{munlock|unmap} before we unmap and
279 * free them. This will result in freeing mlocked pages.
Nick Pigginb291f002008-10-18 20:26:44 -0700280 */
Rik van Rielba470de2008-10-18 20:26:50 -0700281void munlock_vma_pages_range(struct vm_area_struct *vma,
Hugh Dickins408e82b2009-09-21 17:03:23 -0700282 unsigned long start, unsigned long end)
Nick Pigginb291f002008-10-18 20:26:44 -0700283{
Hugh Dickins408e82b2009-09-21 17:03:23 -0700284 unsigned long addr;
285
286 lru_add_drain();
Nick Pigginb291f002008-10-18 20:26:44 -0700287 vma->vm_flags &= ~VM_LOCKED;
Hugh Dickins408e82b2009-09-21 17:03:23 -0700288
289 for (addr = start; addr < end; addr += PAGE_SIZE) {
Hugh Dickins6e919712009-09-21 17:03:32 -0700290 struct page *page;
291 /*
292 * Although FOLL_DUMP is intended for get_dump_page(),
293 * it just so happens that its special treatment of the
294 * ZERO_PAGE (returning an error instead of doing get_page)
295 * suits munlock very well (and if somehow an abnormal page
296 * has sneaked into the range, we won't oops here: great).
297 */
298 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
299 if (page && !IS_ERR(page)) {
Hugh Dickins408e82b2009-09-21 17:03:23 -0700300 lock_page(page);
Hugh Dickins6e919712009-09-21 17:03:32 -0700301 /*
302 * Like in __mlock_vma_pages_range(),
303 * because we lock page here and migration is
304 * blocked by the elevated reference, we need
305 * only check for file-cache page truncation.
306 */
Hugh Dickins408e82b2009-09-21 17:03:23 -0700307 if (page->mapping)
308 munlock_vma_page(page);
309 unlock_page(page);
310 put_page(page);
311 }
312 cond_resched();
313 }
Nick Pigginb291f002008-10-18 20:26:44 -0700314}
315
316/*
317 * mlock_fixup - handle mlock[all]/munlock[all] requests.
318 *
319 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
320 * munlock is a no-op. However, for some special vmas, we go ahead and
321 * populate the ptes via make_pages_present().
322 *
323 * For vmas that pass the filters, merge/split as appropriate.
324 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
326 unsigned long start, unsigned long end, unsigned int newflags)
327{
Nick Pigginb291f002008-10-18 20:26:44 -0700328 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 pgoff_t pgoff;
Nick Pigginb291f002008-10-18 20:26:44 -0700330 int nr_pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 int ret = 0;
Nick Pigginb291f002008-10-18 20:26:44 -0700332 int lock = newflags & VM_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
Michel Lespinassefed067d2011-01-13 15:46:10 -0800334 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
335 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current))
Nick Pigginb291f002008-10-18 20:26:44 -0700336 goto out; /* don't set VM_LOCKED, don't count */
337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
339 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
340 vma->vm_file, pgoff, vma_policy(vma));
341 if (*prev) {
342 vma = *prev;
343 goto success;
344 }
345
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 if (start != vma->vm_start) {
347 ret = split_vma(mm, vma, start, 1);
348 if (ret)
349 goto out;
350 }
351
352 if (end != vma->vm_end) {
353 ret = split_vma(mm, vma, end, 0);
354 if (ret)
355 goto out;
356 }
357
358success:
359 /*
Nick Pigginb291f002008-10-18 20:26:44 -0700360 * Keep track of amount of locked VM.
361 */
362 nr_pages = (end - start) >> PAGE_SHIFT;
363 if (!lock)
364 nr_pages = -nr_pages;
365 mm->locked_vm += nr_pages;
366
367 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 * vm_flags is protected by the mmap_sem held in write mode.
369 * It's okay if try_to_unmap_one unmaps a page just after we
Nick Pigginb291f002008-10-18 20:26:44 -0700370 * set VM_LOCKED, __mlock_vma_pages_range will bring it back.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372
Michel Lespinassefed067d2011-01-13 15:46:10 -0800373 if (lock)
Hugh Dickins408e82b2009-09-21 17:03:23 -0700374 vma->vm_flags = newflags;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800375 else
Hugh Dickins408e82b2009-09-21 17:03:23 -0700376 munlock_vma_pages_range(vma, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378out:
Nick Pigginb291f002008-10-18 20:26:44 -0700379 *prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 return ret;
381}
382
383static int do_mlock(unsigned long start, size_t len, int on)
384{
385 unsigned long nstart, end, tmp;
386 struct vm_area_struct * vma, * prev;
387 int error;
388
Michel Lespinassefed067d2011-01-13 15:46:10 -0800389 VM_BUG_ON(start & ~PAGE_MASK);
390 VM_BUG_ON(len != PAGE_ALIGN(len));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 end = start + len;
392 if (end < start)
393 return -EINVAL;
394 if (end == start)
395 return 0;
396 vma = find_vma_prev(current->mm, start, &prev);
397 if (!vma || vma->vm_start > start)
398 return -ENOMEM;
399
400 if (start > vma->vm_start)
401 prev = vma;
402
403 for (nstart = start ; ; ) {
404 unsigned int newflags;
405
406 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
407
408 newflags = vma->vm_flags | VM_LOCKED;
409 if (!on)
410 newflags &= ~VM_LOCKED;
411
412 tmp = vma->vm_end;
413 if (tmp > end)
414 tmp = end;
415 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
416 if (error)
417 break;
418 nstart = tmp;
419 if (nstart < prev->vm_end)
420 nstart = prev->vm_end;
421 if (nstart >= end)
422 break;
423
424 vma = prev->vm_next;
425 if (!vma || vma->vm_start != nstart) {
426 error = -ENOMEM;
427 break;
428 }
429 }
430 return error;
431}
432
Michel Lespinassefed067d2011-01-13 15:46:10 -0800433static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
434{
435 struct mm_struct *mm = current->mm;
436 unsigned long end, nstart, nend;
437 struct vm_area_struct *vma = NULL;
Michel Lespinasse53a77062011-01-13 15:46:14 -0800438 int locked = 0;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800439 int ret = 0;
440
441 VM_BUG_ON(start & ~PAGE_MASK);
442 VM_BUG_ON(len != PAGE_ALIGN(len));
443 end = start + len;
444
Michel Lespinassefed067d2011-01-13 15:46:10 -0800445 for (nstart = start; nstart < end; nstart = nend) {
446 /*
447 * We want to fault in pages for [nstart; end) address range.
448 * Find first corresponding VMA.
449 */
Michel Lespinasse53a77062011-01-13 15:46:14 -0800450 if (!locked) {
451 locked = 1;
452 down_read(&mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800453 vma = find_vma(mm, nstart);
Michel Lespinasse53a77062011-01-13 15:46:14 -0800454 } else if (nstart >= vma->vm_end)
Michel Lespinassefed067d2011-01-13 15:46:10 -0800455 vma = vma->vm_next;
456 if (!vma || vma->vm_start >= end)
457 break;
458 /*
459 * Set [nstart; nend) to intersection of desired address
460 * range with the first VMA. Also, skip undesirable VMA types.
461 */
462 nend = min(end, vma->vm_end);
463 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
464 continue;
465 if (nstart < vma->vm_start)
466 nstart = vma->vm_start;
467 /*
Michel Lespinasse53a77062011-01-13 15:46:14 -0800468 * Now fault in a range of pages. __mlock_vma_pages_range()
469 * double checks the vma flags, so that it won't mlock pages
470 * if the vma was already munlocked.
Michel Lespinassefed067d2011-01-13 15:46:10 -0800471 */
Michel Lespinasse53a77062011-01-13 15:46:14 -0800472 ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
473 if (ret < 0) {
474 if (ignore_errors) {
475 ret = 0;
476 continue; /* continue at next VMA */
477 }
Michel Lespinasse5fdb2002011-01-13 15:46:12 -0800478 ret = __mlock_posix_error_return(ret);
479 break;
480 }
Michel Lespinasse53a77062011-01-13 15:46:14 -0800481 nend = nstart + ret * PAGE_SIZE;
482 ret = 0;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800483 }
Michel Lespinasse53a77062011-01-13 15:46:14 -0800484 if (locked)
485 up_read(&mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800486 return ret; /* 0 or negative error code */
487}
488
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100489SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490{
491 unsigned long locked;
492 unsigned long lock_limit;
493 int error = -ENOMEM;
494
495 if (!can_do_mlock())
496 return -EPERM;
497
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -0800498 lru_add_drain_all(); /* flush pagevec */
499
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 down_write(&current->mm->mmap_sem);
501 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
502 start &= PAGE_MASK;
503
504 locked = len >> PAGE_SHIFT;
505 locked += current->mm->locked_vm;
506
Jiri Slaby59e99e52010-03-05 13:41:44 -0800507 lock_limit = rlimit(RLIMIT_MEMLOCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 lock_limit >>= PAGE_SHIFT;
509
510 /* check against resource limits */
511 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
512 error = do_mlock(start, len, 1);
513 up_write(&current->mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800514 if (!error)
515 error = do_mlock_pages(start, len, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 return error;
517}
518
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100519SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520{
521 int ret;
522
523 down_write(&current->mm->mmap_sem);
524 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
525 start &= PAGE_MASK;
526 ret = do_mlock(start, len, 0);
527 up_write(&current->mm->mmap_sem);
528 return ret;
529}
530
531static int do_mlockall(int flags)
532{
533 struct vm_area_struct * vma, * prev = NULL;
534 unsigned int def_flags = 0;
535
536 if (flags & MCL_FUTURE)
537 def_flags = VM_LOCKED;
538 current->mm->def_flags = def_flags;
539 if (flags == MCL_FUTURE)
540 goto out;
541
542 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
543 unsigned int newflags;
544
545 newflags = vma->vm_flags | VM_LOCKED;
546 if (!(flags & MCL_CURRENT))
547 newflags &= ~VM_LOCKED;
548
549 /* Ignore errors */
550 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
551 }
552out:
553 return 0;
554}
555
Heiko Carstens3480b252009-01-14 14:14:16 +0100556SYSCALL_DEFINE1(mlockall, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557{
558 unsigned long lock_limit;
559 int ret = -EINVAL;
560
561 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
562 goto out;
563
564 ret = -EPERM;
565 if (!can_do_mlock())
566 goto out;
567
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -0800568 lru_add_drain_all(); /* flush pagevec */
569
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 down_write(&current->mm->mmap_sem);
571
Jiri Slaby59e99e52010-03-05 13:41:44 -0800572 lock_limit = rlimit(RLIMIT_MEMLOCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 lock_limit >>= PAGE_SHIFT;
574
575 ret = -ENOMEM;
576 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
577 capable(CAP_IPC_LOCK))
578 ret = do_mlockall(flags);
579 up_write(&current->mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800580 if (!ret && (flags & MCL_CURRENT)) {
581 /* Ignore errors */
582 do_mlock_pages(0, TASK_SIZE, 1);
583 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584out:
585 return ret;
586}
587
Heiko Carstens3480b252009-01-14 14:14:16 +0100588SYSCALL_DEFINE0(munlockall)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589{
590 int ret;
591
592 down_write(&current->mm->mmap_sem);
593 ret = do_mlockall(0);
594 up_write(&current->mm->mmap_sem);
595 return ret;
596}
597
598/*
599 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
600 * shm segments) get accounted against the user_struct instead.
601 */
602static DEFINE_SPINLOCK(shmlock_user_lock);
603
604int user_shm_lock(size_t size, struct user_struct *user)
605{
606 unsigned long lock_limit, locked;
607 int allowed = 0;
608
609 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
Jiri Slaby59e99e52010-03-05 13:41:44 -0800610 lock_limit = rlimit(RLIMIT_MEMLOCK);
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700611 if (lock_limit == RLIM_INFINITY)
612 allowed = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 lock_limit >>= PAGE_SHIFT;
614 spin_lock(&shmlock_user_lock);
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700615 if (!allowed &&
616 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 goto out;
618 get_uid(user);
619 user->locked_shm += locked;
620 allowed = 1;
621out:
622 spin_unlock(&shmlock_user_lock);
623 return allowed;
624}
625
626void user_shm_unlock(size_t size, struct user_struct *user)
627{
628 spin_lock(&shmlock_user_lock);
629 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
630 spin_unlock(&shmlock_user_lock);
631 free_uid(user);
632}