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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
Rik van Rielba470de2008-10-18 20:26:50 -0700138/**
Hugh Dickins408e82b2009-09-21 17:03:23 -0700139 * __mlock_vma_pages_range() - mlock a range of pages in the vma.
Rik van Rielba470de2008-10-18 20:26:50 -0700140 * @vma: target vma
141 * @start: start address
142 * @end: end address
Nick Pigginb291f002008-10-18 20:26:44 -0700143 *
Hugh Dickins408e82b2009-09-21 17:03:23 -0700144 * This takes care of making the pages present too.
Nick Pigginb291f002008-10-18 20:26:44 -0700145 *
Rik van Rielba470de2008-10-18 20:26:50 -0700146 * return 0 on success, negative error code on error.
147 *
148 * vma->vm_mm->mmap_sem must be held for at least read.
Nick Pigginb291f002008-10-18 20:26:44 -0700149 */
Rik van Rielba470de2008-10-18 20:26:50 -0700150static long __mlock_vma_pages_range(struct vm_area_struct *vma,
Michel Lespinasse53a77062011-01-13 15:46:14 -0800151 unsigned long start, unsigned long end,
152 int *nonblocking)
Nick Pigginb291f002008-10-18 20:26:44 -0700153{
154 struct mm_struct *mm = vma->vm_mm;
155 unsigned long addr = start;
Nick Pigginb291f002008-10-18 20:26:44 -0700156 int nr_pages = (end - start) / PAGE_SIZE;
Hugh Dickins408e82b2009-09-21 17:03:23 -0700157 int gup_flags;
Nick Pigginb291f002008-10-18 20:26:44 -0700158
Rik van Rielba470de2008-10-18 20:26:50 -0700159 VM_BUG_ON(start & ~PAGE_MASK);
160 VM_BUG_ON(end & ~PAGE_MASK);
161 VM_BUG_ON(start < vma->vm_start);
162 VM_BUG_ON(end > vma->vm_end);
Hugh Dickins408e82b2009-09-21 17:03:23 -0700163 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
Rik van Rielba470de2008-10-18 20:26:50 -0700164
Linus Torvaldsa1fde082011-05-04 21:30:28 -0700165 gup_flags = FOLL_TOUCH | FOLL_MLOCK;
Michel Lespinasse5ecfda02011-01-13 15:46:09 -0800166 /*
167 * We want to touch writable mappings with a write fault in order
168 * to break COW, except for shared mappings because these don't COW
169 * and we would not want to dirty them for nothing.
170 */
171 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
Hugh Dickins58fa8792009-09-21 17:03:31 -0700172 gup_flags |= FOLL_WRITE;
Nick Pigginb291f002008-10-18 20:26:44 -0700173
Michel Lespinassefdf4c582011-01-31 17:03:41 -0800174 /*
175 * We want mlock to succeed for regions that have any permissions
176 * other than PROT_NONE.
177 */
178 if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
179 gup_flags |= FOLL_FORCE;
180
Michel Lespinasse53a77062011-01-13 15:46:14 -0800181 return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
182 NULL, NULL, nonblocking);
Lee Schermerhorn9978ad52008-10-18 20:26:56 -0700183}
184
185/*
186 * convert get_user_pages() return value to posix mlock() error
187 */
188static int __mlock_posix_error_return(long retval)
189{
190 if (retval == -EFAULT)
191 retval = -ENOMEM;
192 else if (retval == -ENOMEM)
193 retval = -EAGAIN;
194 return retval;
Nick Pigginb291f002008-10-18 20:26:44 -0700195}
196
Rik van Rielba470de2008-10-18 20:26:50 -0700197/**
198 * mlock_vma_pages_range() - mlock pages in specified vma range.
199 * @vma - the vma containing the specfied address range
200 * @start - starting address in @vma to mlock
201 * @end - end address [+1] in @vma to mlock
202 *
203 * For mmap()/mremap()/expansion of mlocked vma.
204 *
205 * return 0 on success for "normal" vmas.
206 *
207 * return number of pages [> 0] to be removed from locked_vm on success
208 * of "special" vmas.
Nick Pigginb291f002008-10-18 20:26:44 -0700209 */
Rik van Rielba470de2008-10-18 20:26:50 -0700210long mlock_vma_pages_range(struct vm_area_struct *vma,
Nick Pigginb291f002008-10-18 20:26:44 -0700211 unsigned long start, unsigned long end)
212{
213 int nr_pages = (end - start) / PAGE_SIZE;
214 BUG_ON(!(vma->vm_flags & VM_LOCKED));
215
216 /*
217 * filter unlockable vmas
218 */
219 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
220 goto no_mlock;
221
222 if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
223 is_vm_hugetlb_page(vma) ||
Stephen Wilson31db58b2011-03-13 15:49:15 -0400224 vma == get_gate_vma(current->mm))) {
Rik van Rielba470de2008-10-18 20:26:50 -0700225
Michel Lespinasse53a77062011-01-13 15:46:14 -0800226 __mlock_vma_pages_range(vma, start, end, NULL);
Hugh Dickinsd5b56232009-02-08 20:56:58 +0000227
228 /* Hide errors from mmap() and other callers */
229 return 0;
Lee Schermerhorn8edb08c2008-10-18 20:26:49 -0700230 }
Nick Pigginb291f002008-10-18 20:26:44 -0700231
232 /*
233 * User mapped kernel pages or huge pages:
234 * make these pages present to populate the ptes, but
235 * fall thru' to reset VM_LOCKED--no need to unlock, and
236 * return nr_pages so these don't get counted against task's
237 * locked limit. huge pages are already counted against
238 * locked vm limit.
239 */
240 make_pages_present(start, end);
241
242no_mlock:
243 vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
Rik van Rielba470de2008-10-18 20:26:50 -0700244 return nr_pages; /* error or pages NOT mlocked */
Nick Pigginb291f002008-10-18 20:26:44 -0700245}
246
Nick Pigginb291f002008-10-18 20:26:44 -0700247/*
Rik van Rielba470de2008-10-18 20:26:50 -0700248 * munlock_vma_pages_range() - munlock all pages in the vma range.'
249 * @vma - vma containing range to be munlock()ed.
250 * @start - start address in @vma of the range
251 * @end - end of range in @vma.
252 *
253 * For mremap(), munmap() and exit().
254 *
255 * Called with @vma VM_LOCKED.
256 *
257 * Returns with VM_LOCKED cleared. Callers must be prepared to
258 * deal with this.
259 *
260 * We don't save and restore VM_LOCKED here because pages are
261 * still on lru. In unmap path, pages might be scanned by reclaim
262 * and re-mlocked by try_to_{munlock|unmap} before we unmap and
263 * free them. This will result in freeing mlocked pages.
Nick Pigginb291f002008-10-18 20:26:44 -0700264 */
Rik van Rielba470de2008-10-18 20:26:50 -0700265void munlock_vma_pages_range(struct vm_area_struct *vma,
Hugh Dickins408e82b2009-09-21 17:03:23 -0700266 unsigned long start, unsigned long end)
Nick Pigginb291f002008-10-18 20:26:44 -0700267{
Hugh Dickins408e82b2009-09-21 17:03:23 -0700268 unsigned long addr;
269
270 lru_add_drain();
Nick Pigginb291f002008-10-18 20:26:44 -0700271 vma->vm_flags &= ~VM_LOCKED;
Hugh Dickins408e82b2009-09-21 17:03:23 -0700272
273 for (addr = start; addr < end; addr += PAGE_SIZE) {
Hugh Dickins6e919712009-09-21 17:03:32 -0700274 struct page *page;
275 /*
276 * Although FOLL_DUMP is intended for get_dump_page(),
277 * it just so happens that its special treatment of the
278 * ZERO_PAGE (returning an error instead of doing get_page)
279 * suits munlock very well (and if somehow an abnormal page
280 * has sneaked into the range, we won't oops here: great).
281 */
282 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
283 if (page && !IS_ERR(page)) {
Hugh Dickins408e82b2009-09-21 17:03:23 -0700284 lock_page(page);
Hugh Dickins6e919712009-09-21 17:03:32 -0700285 /*
286 * Like in __mlock_vma_pages_range(),
287 * because we lock page here and migration is
288 * blocked by the elevated reference, we need
289 * only check for file-cache page truncation.
290 */
Hugh Dickins408e82b2009-09-21 17:03:23 -0700291 if (page->mapping)
292 munlock_vma_page(page);
293 unlock_page(page);
294 put_page(page);
295 }
296 cond_resched();
297 }
Nick Pigginb291f002008-10-18 20:26:44 -0700298}
299
300/*
301 * mlock_fixup - handle mlock[all]/munlock[all] requests.
302 *
303 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
304 * munlock is a no-op. However, for some special vmas, we go ahead and
305 * populate the ptes via make_pages_present().
306 *
307 * For vmas that pass the filters, merge/split as appropriate.
308 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
KOSAKI Motohiroca16d142011-05-26 19:16:19 +0900310 unsigned long start, unsigned long end, vm_flags_t newflags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311{
Nick Pigginb291f002008-10-18 20:26:44 -0700312 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 pgoff_t pgoff;
Nick Pigginb291f002008-10-18 20:26:44 -0700314 int nr_pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 int ret = 0;
KOSAKI Motohiroca16d142011-05-26 19:16:19 +0900316 int lock = !!(newflags & VM_LOCKED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Michel Lespinassefed067d2011-01-13 15:46:10 -0800318 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
Stephen Wilson31db58b2011-03-13 15:49:15 -0400319 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
Nick Pigginb291f002008-10-18 20:26:44 -0700320 goto out; /* don't set VM_LOCKED, don't count */
321
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
323 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
324 vma->vm_file, pgoff, vma_policy(vma));
325 if (*prev) {
326 vma = *prev;
327 goto success;
328 }
329
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 if (start != vma->vm_start) {
331 ret = split_vma(mm, vma, start, 1);
332 if (ret)
333 goto out;
334 }
335
336 if (end != vma->vm_end) {
337 ret = split_vma(mm, vma, end, 0);
338 if (ret)
339 goto out;
340 }
341
342success:
343 /*
Nick Pigginb291f002008-10-18 20:26:44 -0700344 * Keep track of amount of locked VM.
345 */
346 nr_pages = (end - start) >> PAGE_SHIFT;
347 if (!lock)
348 nr_pages = -nr_pages;
349 mm->locked_vm += nr_pages;
350
351 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 * vm_flags is protected by the mmap_sem held in write mode.
353 * It's okay if try_to_unmap_one unmaps a page just after we
Nick Pigginb291f002008-10-18 20:26:44 -0700354 * set VM_LOCKED, __mlock_vma_pages_range will bring it back.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
Michel Lespinassefed067d2011-01-13 15:46:10 -0800357 if (lock)
Hugh Dickins408e82b2009-09-21 17:03:23 -0700358 vma->vm_flags = newflags;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800359 else
Hugh Dickins408e82b2009-09-21 17:03:23 -0700360 munlock_vma_pages_range(vma, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362out:
Nick Pigginb291f002008-10-18 20:26:44 -0700363 *prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 return ret;
365}
366
367static int do_mlock(unsigned long start, size_t len, int on)
368{
369 unsigned long nstart, end, tmp;
370 struct vm_area_struct * vma, * prev;
371 int error;
372
Michel Lespinassefed067d2011-01-13 15:46:10 -0800373 VM_BUG_ON(start & ~PAGE_MASK);
374 VM_BUG_ON(len != PAGE_ALIGN(len));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 end = start + len;
376 if (end < start)
377 return -EINVAL;
378 if (end == start)
379 return 0;
380 vma = find_vma_prev(current->mm, start, &prev);
381 if (!vma || vma->vm_start > start)
382 return -ENOMEM;
383
384 if (start > vma->vm_start)
385 prev = vma;
386
387 for (nstart = start ; ; ) {
KOSAKI Motohiroca16d142011-05-26 19:16:19 +0900388 vm_flags_t newflags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389
390 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
391
392 newflags = vma->vm_flags | VM_LOCKED;
393 if (!on)
394 newflags &= ~VM_LOCKED;
395
396 tmp = vma->vm_end;
397 if (tmp > end)
398 tmp = end;
399 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
400 if (error)
401 break;
402 nstart = tmp;
403 if (nstart < prev->vm_end)
404 nstart = prev->vm_end;
405 if (nstart >= end)
406 break;
407
408 vma = prev->vm_next;
409 if (!vma || vma->vm_start != nstart) {
410 error = -ENOMEM;
411 break;
412 }
413 }
414 return error;
415}
416
Michel Lespinassefed067d2011-01-13 15:46:10 -0800417static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
418{
419 struct mm_struct *mm = current->mm;
420 unsigned long end, nstart, nend;
421 struct vm_area_struct *vma = NULL;
Michel Lespinasse53a77062011-01-13 15:46:14 -0800422 int locked = 0;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800423 int ret = 0;
424
425 VM_BUG_ON(start & ~PAGE_MASK);
426 VM_BUG_ON(len != PAGE_ALIGN(len));
427 end = start + len;
428
Michel Lespinassefed067d2011-01-13 15:46:10 -0800429 for (nstart = start; nstart < end; nstart = nend) {
430 /*
431 * We want to fault in pages for [nstart; end) address range.
432 * Find first corresponding VMA.
433 */
Michel Lespinasse53a77062011-01-13 15:46:14 -0800434 if (!locked) {
435 locked = 1;
436 down_read(&mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800437 vma = find_vma(mm, nstart);
Michel Lespinasse53a77062011-01-13 15:46:14 -0800438 } else if (nstart >= vma->vm_end)
Michel Lespinassefed067d2011-01-13 15:46:10 -0800439 vma = vma->vm_next;
440 if (!vma || vma->vm_start >= end)
441 break;
442 /*
443 * Set [nstart; nend) to intersection of desired address
444 * range with the first VMA. Also, skip undesirable VMA types.
445 */
446 nend = min(end, vma->vm_end);
447 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
448 continue;
449 if (nstart < vma->vm_start)
450 nstart = vma->vm_start;
451 /*
Michel Lespinasse53a77062011-01-13 15:46:14 -0800452 * Now fault in a range of pages. __mlock_vma_pages_range()
453 * double checks the vma flags, so that it won't mlock pages
454 * if the vma was already munlocked.
Michel Lespinassefed067d2011-01-13 15:46:10 -0800455 */
Michel Lespinasse53a77062011-01-13 15:46:14 -0800456 ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
457 if (ret < 0) {
458 if (ignore_errors) {
459 ret = 0;
460 continue; /* continue at next VMA */
461 }
Michel Lespinasse5fdb2002011-01-13 15:46:12 -0800462 ret = __mlock_posix_error_return(ret);
463 break;
464 }
Michel Lespinasse53a77062011-01-13 15:46:14 -0800465 nend = nstart + ret * PAGE_SIZE;
466 ret = 0;
Michel Lespinassefed067d2011-01-13 15:46:10 -0800467 }
Michel Lespinasse53a77062011-01-13 15:46:14 -0800468 if (locked)
469 up_read(&mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800470 return ret; /* 0 or negative error code */
471}
472
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100473SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474{
475 unsigned long locked;
476 unsigned long lock_limit;
477 int error = -ENOMEM;
478
479 if (!can_do_mlock())
480 return -EPERM;
481
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -0800482 lru_add_drain_all(); /* flush pagevec */
483
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 down_write(&current->mm->mmap_sem);
485 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
486 start &= PAGE_MASK;
487
488 locked = len >> PAGE_SHIFT;
489 locked += current->mm->locked_vm;
490
Jiri Slaby59e99e52010-03-05 13:41:44 -0800491 lock_limit = rlimit(RLIMIT_MEMLOCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 lock_limit >>= PAGE_SHIFT;
493
494 /* check against resource limits */
495 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
496 error = do_mlock(start, len, 1);
497 up_write(&current->mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800498 if (!error)
499 error = do_mlock_pages(start, len, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 return error;
501}
502
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100503SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504{
505 int ret;
506
507 down_write(&current->mm->mmap_sem);
508 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
509 start &= PAGE_MASK;
510 ret = do_mlock(start, len, 0);
511 up_write(&current->mm->mmap_sem);
512 return ret;
513}
514
515static int do_mlockall(int flags)
516{
517 struct vm_area_struct * vma, * prev = NULL;
518 unsigned int def_flags = 0;
519
520 if (flags & MCL_FUTURE)
521 def_flags = VM_LOCKED;
522 current->mm->def_flags = def_flags;
523 if (flags == MCL_FUTURE)
524 goto out;
525
526 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
KOSAKI Motohiroca16d142011-05-26 19:16:19 +0900527 vm_flags_t newflags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528
529 newflags = vma->vm_flags | VM_LOCKED;
530 if (!(flags & MCL_CURRENT))
531 newflags &= ~VM_LOCKED;
532
533 /* Ignore errors */
534 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
535 }
536out:
537 return 0;
538}
539
Heiko Carstens3480b252009-01-14 14:14:16 +0100540SYSCALL_DEFINE1(mlockall, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
542 unsigned long lock_limit;
543 int ret = -EINVAL;
544
545 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
546 goto out;
547
548 ret = -EPERM;
549 if (!can_do_mlock())
550 goto out;
551
Christoph Lameterdf9d6982011-10-31 17:09:35 -0700552 if (flags & MCL_CURRENT)
553 lru_add_drain_all(); /* flush pagevec */
KOSAKI Motohiro8891d6d2008-11-12 13:26:53 -0800554
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 down_write(&current->mm->mmap_sem);
556
Jiri Slaby59e99e52010-03-05 13:41:44 -0800557 lock_limit = rlimit(RLIMIT_MEMLOCK);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 lock_limit >>= PAGE_SHIFT;
559
560 ret = -ENOMEM;
561 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
562 capable(CAP_IPC_LOCK))
563 ret = do_mlockall(flags);
564 up_write(&current->mm->mmap_sem);
Michel Lespinassefed067d2011-01-13 15:46:10 -0800565 if (!ret && (flags & MCL_CURRENT)) {
566 /* Ignore errors */
567 do_mlock_pages(0, TASK_SIZE, 1);
568 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569out:
570 return ret;
571}
572
Heiko Carstens3480b252009-01-14 14:14:16 +0100573SYSCALL_DEFINE0(munlockall)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574{
575 int ret;
576
577 down_write(&current->mm->mmap_sem);
578 ret = do_mlockall(0);
579 up_write(&current->mm->mmap_sem);
580 return ret;
581}
582
583/*
584 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
585 * shm segments) get accounted against the user_struct instead.
586 */
587static DEFINE_SPINLOCK(shmlock_user_lock);
588
589int user_shm_lock(size_t size, struct user_struct *user)
590{
591 unsigned long lock_limit, locked;
592 int allowed = 0;
593
594 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
Jiri Slaby59e99e52010-03-05 13:41:44 -0800595 lock_limit = rlimit(RLIMIT_MEMLOCK);
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700596 if (lock_limit == RLIM_INFINITY)
597 allowed = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 lock_limit >>= PAGE_SHIFT;
599 spin_lock(&shmlock_user_lock);
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700600 if (!allowed &&
601 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 goto out;
603 get_uid(user);
604 user->locked_shm += locked;
605 allowed = 1;
606out:
607 spin_unlock(&shmlock_user_lock);
608 return allowed;
609}
610
611void user_shm_unlock(size_t size, struct user_struct *user)
612{
613 spin_lock(&shmlock_user_lock);
614 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
615 spin_unlock(&shmlock_user_lock);
616 free_uid(user);
617}