Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/mlock.c | |
3 | * | |
4 | * (C) Copyright 1995 Linus Torvalds | |
5 | * (C) Copyright 2002 Christoph Hellwig | |
6 | */ | |
7 | ||
c59ede7b | 8 | #include <linux/capability.h> |
1da177e4 LT |
9 | #include <linux/mman.h> |
10 | #include <linux/mm.h> | |
b291f000 NP |
11 | #include <linux/swap.h> |
12 | #include <linux/swapops.h> | |
13 | #include <linux/pagemap.h> | |
1da177e4 LT |
14 | #include <linux/mempolicy.h> |
15 | #include <linux/syscalls.h> | |
e8edc6e0 AD |
16 | #include <linux/sched.h> |
17 | #include <linux/module.h> | |
b291f000 NP |
18 | #include <linux/rmap.h> |
19 | #include <linux/mmzone.h> | |
20 | #include <linux/hugetlb.h> | |
21 | ||
22 | #include "internal.h" | |
1da177e4 | 23 | |
e8edc6e0 AD |
24 | int can_do_mlock(void) |
25 | { | |
26 | if (capable(CAP_IPC_LOCK)) | |
27 | return 1; | |
28 | if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0) | |
29 | return 1; | |
30 | return 0; | |
31 | } | |
32 | EXPORT_SYMBOL(can_do_mlock); | |
1da177e4 | 33 | |
b291f000 NP |
34 | #ifdef CONFIG_UNEVICTABLE_LRU |
35 | /* | |
36 | * Mlocked pages are marked with PageMlocked() flag for efficient testing | |
37 | * in vmscan and, possibly, the fault path; and to support semi-accurate | |
38 | * statistics. | |
39 | * | |
40 | * An mlocked page [PageMlocked(page)] is unevictable. As such, it will | |
41 | * be placed on the LRU "unevictable" list, rather than the [in]active lists. | |
42 | * The unevictable list is an LRU sibling list to the [in]active lists. | |
43 | * PageUnevictable is set to indicate the unevictable state. | |
44 | * | |
45 | * When lazy mlocking via vmscan, it is important to ensure that the | |
46 | * vma's VM_LOCKED status is not concurrently being modified, otherwise we | |
47 | * may have mlocked a page that is being munlocked. So lazy mlock must take | |
48 | * the mmap_sem for read, and verify that the vma really is locked | |
49 | * (see mm/rmap.c). | |
50 | */ | |
51 | ||
52 | /* | |
53 | * LRU accounting for clear_page_mlock() | |
54 | */ | |
55 | void __clear_page_mlock(struct page *page) | |
56 | { | |
57 | VM_BUG_ON(!PageLocked(page)); | |
58 | ||
59 | if (!page->mapping) { /* truncated ? */ | |
60 | return; | |
61 | } | |
62 | ||
5344b7e6 NP |
63 | dec_zone_page_state(page, NR_MLOCK); |
64 | count_vm_event(UNEVICTABLE_PGCLEARED); | |
b291f000 NP |
65 | if (!isolate_lru_page(page)) { |
66 | putback_lru_page(page); | |
67 | } else { | |
68 | /* | |
69 | * Page not on the LRU yet. Flush all pagevecs and retry. | |
70 | */ | |
71 | lru_add_drain_all(); | |
72 | if (!isolate_lru_page(page)) | |
73 | putback_lru_page(page); | |
5344b7e6 NP |
74 | else if (PageUnevictable(page)) |
75 | count_vm_event(UNEVICTABLE_PGSTRANDED); | |
76 | ||
b291f000 NP |
77 | } |
78 | } | |
79 | ||
80 | /* | |
81 | * Mark page as mlocked if not already. | |
82 | * If page on LRU, isolate and putback to move to unevictable list. | |
83 | */ | |
84 | void mlock_vma_page(struct page *page) | |
85 | { | |
86 | BUG_ON(!PageLocked(page)); | |
87 | ||
5344b7e6 NP |
88 | if (!TestSetPageMlocked(page)) { |
89 | inc_zone_page_state(page, NR_MLOCK); | |
90 | count_vm_event(UNEVICTABLE_PGMLOCKED); | |
91 | if (!isolate_lru_page(page)) | |
92 | putback_lru_page(page); | |
93 | } | |
b291f000 NP |
94 | } |
95 | ||
96 | /* | |
97 | * called from munlock()/munmap() path with page supposedly on the LRU. | |
98 | * | |
99 | * Note: unlike mlock_vma_page(), we can't just clear the PageMlocked | |
100 | * [in try_to_munlock()] and then attempt to isolate the page. We must | |
101 | * isolate the page to keep others from messing with its unevictable | |
102 | * and mlocked state while trying to munlock. However, we pre-clear the | |
103 | * mlocked state anyway as we might lose the isolation race and we might | |
104 | * not get another chance to clear PageMlocked. If we successfully | |
105 | * isolate the page and try_to_munlock() detects other VM_LOCKED vmas | |
106 | * mapping the page, it will restore the PageMlocked state, unless the page | |
107 | * is mapped in a non-linear vma. So, we go ahead and SetPageMlocked(), | |
108 | * perhaps redundantly. | |
109 | * If we lose the isolation race, and the page is mapped by other VM_LOCKED | |
110 | * vmas, we'll detect this in vmscan--via try_to_munlock() or try_to_unmap() | |
111 | * either of which will restore the PageMlocked state by calling | |
112 | * mlock_vma_page() above, if it can grab the vma's mmap sem. | |
113 | */ | |
114 | static void munlock_vma_page(struct page *page) | |
115 | { | |
116 | BUG_ON(!PageLocked(page)); | |
117 | ||
5344b7e6 NP |
118 | if (TestClearPageMlocked(page)) { |
119 | dec_zone_page_state(page, NR_MLOCK); | |
120 | if (!isolate_lru_page(page)) { | |
121 | int ret = try_to_munlock(page); | |
122 | /* | |
123 | * did try_to_unlock() succeed or punt? | |
124 | */ | |
125 | if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN) | |
126 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); | |
127 | ||
128 | putback_lru_page(page); | |
129 | } else { | |
130 | /* | |
131 | * We lost the race. let try_to_unmap() deal | |
132 | * with it. At least we get the page state and | |
133 | * mlock stats right. However, page is still on | |
134 | * the noreclaim list. We'll fix that up when | |
135 | * the page is eventually freed or we scan the | |
136 | * noreclaim list. | |
137 | */ | |
138 | if (PageUnevictable(page)) | |
139 | count_vm_event(UNEVICTABLE_PGSTRANDED); | |
140 | else | |
141 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); | |
142 | } | |
b291f000 NP |
143 | } |
144 | } | |
145 | ||
ba470de4 RR |
146 | /** |
147 | * __mlock_vma_pages_range() - mlock/munlock a range of pages in the vma. | |
148 | * @vma: target vma | |
149 | * @start: start address | |
150 | * @end: end address | |
151 | * @mlock: 0 indicate munlock, otherwise mlock. | |
152 | * | |
153 | * If @mlock == 0, unlock an mlocked range; | |
154 | * else mlock the range of pages. This takes care of making the pages present , | |
155 | * too. | |
b291f000 | 156 | * |
ba470de4 | 157 | * return 0 on success, negative error code on error. |
b291f000 | 158 | * |
ba470de4 | 159 | * vma->vm_mm->mmap_sem must be held for at least read. |
b291f000 | 160 | */ |
ba470de4 RR |
161 | static long __mlock_vma_pages_range(struct vm_area_struct *vma, |
162 | unsigned long start, unsigned long end, | |
163 | int mlock) | |
b291f000 NP |
164 | { |
165 | struct mm_struct *mm = vma->vm_mm; | |
166 | unsigned long addr = start; | |
167 | struct page *pages[16]; /* 16 gives a reasonable batch */ | |
b291f000 NP |
168 | int nr_pages = (end - start) / PAGE_SIZE; |
169 | int ret; | |
ba470de4 RR |
170 | int gup_flags = 0; |
171 | ||
172 | VM_BUG_ON(start & ~PAGE_MASK); | |
173 | VM_BUG_ON(end & ~PAGE_MASK); | |
174 | VM_BUG_ON(start < vma->vm_start); | |
175 | VM_BUG_ON(end > vma->vm_end); | |
176 | VM_BUG_ON((!rwsem_is_locked(&mm->mmap_sem)) && | |
177 | (atomic_read(&mm->mm_users) != 0)); | |
178 | ||
179 | /* | |
180 | * mlock: don't page populate if page has PROT_NONE permission. | |
181 | * munlock: the pages always do munlock althrough | |
182 | * its has PROT_NONE permission. | |
183 | */ | |
184 | if (!mlock) | |
185 | gup_flags |= GUP_FLAGS_IGNORE_VMA_PERMISSIONS; | |
b291f000 | 186 | |
ba470de4 RR |
187 | if (vma->vm_flags & VM_WRITE) |
188 | gup_flags |= GUP_FLAGS_WRITE; | |
b291f000 NP |
189 | |
190 | lru_add_drain_all(); /* push cached pages to LRU */ | |
191 | ||
192 | while (nr_pages > 0) { | |
193 | int i; | |
194 | ||
195 | cond_resched(); | |
196 | ||
197 | /* | |
198 | * get_user_pages makes pages present if we are | |
199 | * setting mlock. and this extra reference count will | |
200 | * disable migration of this page. However, page may | |
201 | * still be truncated out from under us. | |
202 | */ | |
ba470de4 | 203 | ret = __get_user_pages(current, mm, addr, |
b291f000 | 204 | min_t(int, nr_pages, ARRAY_SIZE(pages)), |
ba470de4 | 205 | gup_flags, pages, NULL); |
b291f000 NP |
206 | /* |
207 | * This can happen for, e.g., VM_NONLINEAR regions before | |
208 | * a page has been allocated and mapped at a given offset, | |
209 | * or for addresses that map beyond end of a file. | |
210 | * We'll mlock the the pages if/when they get faulted in. | |
211 | */ | |
212 | if (ret < 0) | |
213 | break; | |
214 | if (ret == 0) { | |
215 | /* | |
216 | * We know the vma is there, so the only time | |
217 | * we cannot get a single page should be an | |
218 | * error (ret < 0) case. | |
219 | */ | |
220 | WARN_ON(1); | |
221 | break; | |
222 | } | |
223 | ||
224 | lru_add_drain(); /* push cached pages to LRU */ | |
225 | ||
226 | for (i = 0; i < ret; i++) { | |
227 | struct page *page = pages[i]; | |
228 | ||
229 | lock_page(page); | |
230 | /* | |
231 | * Because we lock page here and migration is blocked | |
232 | * by the elevated reference, we need only check for | |
233 | * page truncation (file-cache only). | |
234 | */ | |
ba470de4 RR |
235 | if (page->mapping) { |
236 | if (mlock) | |
237 | mlock_vma_page(page); | |
238 | else | |
239 | munlock_vma_page(page); | |
240 | } | |
b291f000 NP |
241 | unlock_page(page); |
242 | put_page(page); /* ref from get_user_pages() */ | |
243 | ||
244 | /* | |
245 | * here we assume that get_user_pages() has given us | |
246 | * a list of virtually contiguous pages. | |
247 | */ | |
248 | addr += PAGE_SIZE; /* for next get_user_pages() */ | |
249 | nr_pages--; | |
250 | } | |
251 | } | |
252 | ||
253 | lru_add_drain_all(); /* to update stats */ | |
254 | ||
255 | return 0; /* count entire vma as locked_vm */ | |
256 | } | |
257 | ||
b291f000 NP |
258 | #else /* CONFIG_UNEVICTABLE_LRU */ |
259 | ||
260 | /* | |
261 | * Just make pages present if VM_LOCKED. No-op if unlocking. | |
262 | */ | |
ba470de4 RR |
263 | static long __mlock_vma_pages_range(struct vm_area_struct *vma, |
264 | unsigned long start, unsigned long end, | |
265 | int mlock) | |
b291f000 | 266 | { |
ba470de4 | 267 | if (mlock && (vma->vm_flags & VM_LOCKED)) |
b291f000 NP |
268 | make_pages_present(start, end); |
269 | return 0; | |
270 | } | |
b291f000 NP |
271 | #endif /* CONFIG_UNEVICTABLE_LRU */ |
272 | ||
ba470de4 RR |
273 | /** |
274 | * mlock_vma_pages_range() - mlock pages in specified vma range. | |
275 | * @vma - the vma containing the specfied address range | |
276 | * @start - starting address in @vma to mlock | |
277 | * @end - end address [+1] in @vma to mlock | |
278 | * | |
279 | * For mmap()/mremap()/expansion of mlocked vma. | |
280 | * | |
281 | * return 0 on success for "normal" vmas. | |
282 | * | |
283 | * return number of pages [> 0] to be removed from locked_vm on success | |
284 | * of "special" vmas. | |
285 | * | |
286 | * return negative error if vma spanning @start-@range disappears while | |
287 | * mmap semaphore is dropped. Unlikely? | |
b291f000 | 288 | */ |
ba470de4 | 289 | long mlock_vma_pages_range(struct vm_area_struct *vma, |
b291f000 NP |
290 | unsigned long start, unsigned long end) |
291 | { | |
8edb08ca | 292 | struct mm_struct *mm = vma->vm_mm; |
b291f000 NP |
293 | int nr_pages = (end - start) / PAGE_SIZE; |
294 | BUG_ON(!(vma->vm_flags & VM_LOCKED)); | |
295 | ||
296 | /* | |
297 | * filter unlockable vmas | |
298 | */ | |
299 | if (vma->vm_flags & (VM_IO | VM_PFNMAP)) | |
300 | goto no_mlock; | |
301 | ||
302 | if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || | |
303 | is_vm_hugetlb_page(vma) || | |
8edb08ca | 304 | vma == get_gate_vma(current))) { |
ba470de4 | 305 | long error; |
8edb08ca | 306 | downgrade_write(&mm->mmap_sem); |
ba470de4 RR |
307 | |
308 | error = __mlock_vma_pages_range(vma, start, end, 1); | |
8edb08ca LS |
309 | |
310 | up_read(&mm->mmap_sem); | |
311 | /* vma can change or disappear */ | |
312 | down_write(&mm->mmap_sem); | |
313 | vma = find_vma(mm, start); | |
314 | /* non-NULL vma must contain @start, but need to check @end */ | |
315 | if (!vma || end > vma->vm_end) | |
ba470de4 RR |
316 | return -ENOMEM; |
317 | ||
318 | return 0; /* hide other errors from mmap(), et al */ | |
8edb08ca | 319 | } |
b291f000 NP |
320 | |
321 | /* | |
322 | * User mapped kernel pages or huge pages: | |
323 | * make these pages present to populate the ptes, but | |
324 | * fall thru' to reset VM_LOCKED--no need to unlock, and | |
325 | * return nr_pages so these don't get counted against task's | |
326 | * locked limit. huge pages are already counted against | |
327 | * locked vm limit. | |
328 | */ | |
329 | make_pages_present(start, end); | |
330 | ||
331 | no_mlock: | |
332 | vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */ | |
ba470de4 | 333 | return nr_pages; /* error or pages NOT mlocked */ |
b291f000 NP |
334 | } |
335 | ||
336 | ||
337 | /* | |
ba470de4 RR |
338 | * munlock_vma_pages_range() - munlock all pages in the vma range.' |
339 | * @vma - vma containing range to be munlock()ed. | |
340 | * @start - start address in @vma of the range | |
341 | * @end - end of range in @vma. | |
342 | * | |
343 | * For mremap(), munmap() and exit(). | |
344 | * | |
345 | * Called with @vma VM_LOCKED. | |
346 | * | |
347 | * Returns with VM_LOCKED cleared. Callers must be prepared to | |
348 | * deal with this. | |
349 | * | |
350 | * We don't save and restore VM_LOCKED here because pages are | |
351 | * still on lru. In unmap path, pages might be scanned by reclaim | |
352 | * and re-mlocked by try_to_{munlock|unmap} before we unmap and | |
353 | * free them. This will result in freeing mlocked pages. | |
b291f000 | 354 | */ |
ba470de4 RR |
355 | void munlock_vma_pages_range(struct vm_area_struct *vma, |
356 | unsigned long start, unsigned long end) | |
b291f000 NP |
357 | { |
358 | vma->vm_flags &= ~VM_LOCKED; | |
ba470de4 | 359 | __mlock_vma_pages_range(vma, start, end, 0); |
b291f000 NP |
360 | } |
361 | ||
362 | /* | |
363 | * mlock_fixup - handle mlock[all]/munlock[all] requests. | |
364 | * | |
365 | * Filters out "special" vmas -- VM_LOCKED never gets set for these, and | |
366 | * munlock is a no-op. However, for some special vmas, we go ahead and | |
367 | * populate the ptes via make_pages_present(). | |
368 | * | |
369 | * For vmas that pass the filters, merge/split as appropriate. | |
370 | */ | |
1da177e4 LT |
371 | static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, |
372 | unsigned long start, unsigned long end, unsigned int newflags) | |
373 | { | |
b291f000 | 374 | struct mm_struct *mm = vma->vm_mm; |
1da177e4 | 375 | pgoff_t pgoff; |
b291f000 | 376 | int nr_pages; |
1da177e4 | 377 | int ret = 0; |
b291f000 | 378 | int lock = newflags & VM_LOCKED; |
1da177e4 | 379 | |
b291f000 NP |
380 | if (newflags == vma->vm_flags || |
381 | (vma->vm_flags & (VM_IO | VM_PFNMAP))) | |
382 | goto out; /* don't set VM_LOCKED, don't count */ | |
383 | ||
384 | if ((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || | |
385 | is_vm_hugetlb_page(vma) || | |
386 | vma == get_gate_vma(current)) { | |
387 | if (lock) | |
388 | make_pages_present(start, end); | |
389 | goto out; /* don't set VM_LOCKED, don't count */ | |
1da177e4 LT |
390 | } |
391 | ||
392 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
393 | *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, | |
394 | vma->vm_file, pgoff, vma_policy(vma)); | |
395 | if (*prev) { | |
396 | vma = *prev; | |
397 | goto success; | |
398 | } | |
399 | ||
1da177e4 LT |
400 | if (start != vma->vm_start) { |
401 | ret = split_vma(mm, vma, start, 1); | |
402 | if (ret) | |
403 | goto out; | |
404 | } | |
405 | ||
406 | if (end != vma->vm_end) { | |
407 | ret = split_vma(mm, vma, end, 0); | |
408 | if (ret) | |
409 | goto out; | |
410 | } | |
411 | ||
412 | success: | |
b291f000 NP |
413 | /* |
414 | * Keep track of amount of locked VM. | |
415 | */ | |
416 | nr_pages = (end - start) >> PAGE_SHIFT; | |
417 | if (!lock) | |
418 | nr_pages = -nr_pages; | |
419 | mm->locked_vm += nr_pages; | |
420 | ||
1da177e4 LT |
421 | /* |
422 | * vm_flags is protected by the mmap_sem held in write mode. | |
423 | * It's okay if try_to_unmap_one unmaps a page just after we | |
b291f000 | 424 | * set VM_LOCKED, __mlock_vma_pages_range will bring it back. |
1da177e4 LT |
425 | */ |
426 | vma->vm_flags = newflags; | |
427 | ||
b291f000 | 428 | if (lock) { |
8edb08ca LS |
429 | /* |
430 | * mmap_sem is currently held for write. Downgrade the write | |
431 | * lock to a read lock so that other faults, mmap scans, ... | |
432 | * while we fault in all pages. | |
433 | */ | |
434 | downgrade_write(&mm->mmap_sem); | |
435 | ||
ba470de4 | 436 | ret = __mlock_vma_pages_range(vma, start, end, 1); |
b291f000 NP |
437 | if (ret > 0) { |
438 | mm->locked_vm -= ret; | |
439 | ret = 0; | |
440 | } | |
8edb08ca LS |
441 | /* |
442 | * Need to reacquire mmap sem in write mode, as our callers | |
443 | * expect this. We have no support for atomically upgrading | |
444 | * a sem to write, so we need to check for ranges while sem | |
445 | * is unlocked. | |
446 | */ | |
447 | up_read(&mm->mmap_sem); | |
448 | /* vma can change or disappear */ | |
449 | down_write(&mm->mmap_sem); | |
450 | *prev = find_vma(mm, start); | |
451 | /* non-NULL *prev must contain @start, but need to check @end */ | |
452 | if (!(*prev) || end > (*prev)->vm_end) | |
ba470de4 | 453 | ret = -ENOMEM; |
8edb08ca LS |
454 | } else { |
455 | /* | |
456 | * TODO: for unlocking, pages will already be resident, so | |
457 | * we don't need to wait for allocations/reclaim/pagein, ... | |
458 | * However, unlocking a very large region can still take a | |
459 | * while. Should we downgrade the semaphore for both lock | |
460 | * AND unlock ? | |
461 | */ | |
ba470de4 | 462 | __mlock_vma_pages_range(vma, start, end, 0); |
8edb08ca | 463 | } |
1da177e4 | 464 | |
1da177e4 | 465 | out: |
b291f000 | 466 | *prev = vma; |
1da177e4 LT |
467 | return ret; |
468 | } | |
469 | ||
470 | static int do_mlock(unsigned long start, size_t len, int on) | |
471 | { | |
472 | unsigned long nstart, end, tmp; | |
473 | struct vm_area_struct * vma, * prev; | |
474 | int error; | |
475 | ||
476 | len = PAGE_ALIGN(len); | |
477 | end = start + len; | |
478 | if (end < start) | |
479 | return -EINVAL; | |
480 | if (end == start) | |
481 | return 0; | |
482 | vma = find_vma_prev(current->mm, start, &prev); | |
483 | if (!vma || vma->vm_start > start) | |
484 | return -ENOMEM; | |
485 | ||
486 | if (start > vma->vm_start) | |
487 | prev = vma; | |
488 | ||
489 | for (nstart = start ; ; ) { | |
490 | unsigned int newflags; | |
491 | ||
492 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ | |
493 | ||
494 | newflags = vma->vm_flags | VM_LOCKED; | |
495 | if (!on) | |
496 | newflags &= ~VM_LOCKED; | |
497 | ||
498 | tmp = vma->vm_end; | |
499 | if (tmp > end) | |
500 | tmp = end; | |
501 | error = mlock_fixup(vma, &prev, nstart, tmp, newflags); | |
502 | if (error) | |
503 | break; | |
504 | nstart = tmp; | |
505 | if (nstart < prev->vm_end) | |
506 | nstart = prev->vm_end; | |
507 | if (nstart >= end) | |
508 | break; | |
509 | ||
510 | vma = prev->vm_next; | |
511 | if (!vma || vma->vm_start != nstart) { | |
512 | error = -ENOMEM; | |
513 | break; | |
514 | } | |
515 | } | |
516 | return error; | |
517 | } | |
518 | ||
519 | asmlinkage long sys_mlock(unsigned long start, size_t len) | |
520 | { | |
521 | unsigned long locked; | |
522 | unsigned long lock_limit; | |
523 | int error = -ENOMEM; | |
524 | ||
525 | if (!can_do_mlock()) | |
526 | return -EPERM; | |
527 | ||
528 | down_write(¤t->mm->mmap_sem); | |
529 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); | |
530 | start &= PAGE_MASK; | |
531 | ||
532 | locked = len >> PAGE_SHIFT; | |
533 | locked += current->mm->locked_vm; | |
534 | ||
535 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; | |
536 | lock_limit >>= PAGE_SHIFT; | |
537 | ||
538 | /* check against resource limits */ | |
539 | if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) | |
540 | error = do_mlock(start, len, 1); | |
541 | up_write(¤t->mm->mmap_sem); | |
542 | return error; | |
543 | } | |
544 | ||
545 | asmlinkage long sys_munlock(unsigned long start, size_t len) | |
546 | { | |
547 | int ret; | |
548 | ||
549 | down_write(¤t->mm->mmap_sem); | |
550 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); | |
551 | start &= PAGE_MASK; | |
552 | ret = do_mlock(start, len, 0); | |
553 | up_write(¤t->mm->mmap_sem); | |
554 | return ret; | |
555 | } | |
556 | ||
557 | static int do_mlockall(int flags) | |
558 | { | |
559 | struct vm_area_struct * vma, * prev = NULL; | |
560 | unsigned int def_flags = 0; | |
561 | ||
562 | if (flags & MCL_FUTURE) | |
563 | def_flags = VM_LOCKED; | |
564 | current->mm->def_flags = def_flags; | |
565 | if (flags == MCL_FUTURE) | |
566 | goto out; | |
567 | ||
568 | for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { | |
569 | unsigned int newflags; | |
570 | ||
571 | newflags = vma->vm_flags | VM_LOCKED; | |
572 | if (!(flags & MCL_CURRENT)) | |
573 | newflags &= ~VM_LOCKED; | |
574 | ||
575 | /* Ignore errors */ | |
576 | mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); | |
577 | } | |
578 | out: | |
579 | return 0; | |
580 | } | |
581 | ||
582 | asmlinkage long sys_mlockall(int flags) | |
583 | { | |
584 | unsigned long lock_limit; | |
585 | int ret = -EINVAL; | |
586 | ||
587 | if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) | |
588 | goto out; | |
589 | ||
590 | ret = -EPERM; | |
591 | if (!can_do_mlock()) | |
592 | goto out; | |
593 | ||
594 | down_write(¤t->mm->mmap_sem); | |
595 | ||
596 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; | |
597 | lock_limit >>= PAGE_SHIFT; | |
598 | ||
599 | ret = -ENOMEM; | |
600 | if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || | |
601 | capable(CAP_IPC_LOCK)) | |
602 | ret = do_mlockall(flags); | |
603 | up_write(¤t->mm->mmap_sem); | |
604 | out: | |
605 | return ret; | |
606 | } | |
607 | ||
608 | asmlinkage long sys_munlockall(void) | |
609 | { | |
610 | int ret; | |
611 | ||
612 | down_write(¤t->mm->mmap_sem); | |
613 | ret = do_mlockall(0); | |
614 | up_write(¤t->mm->mmap_sem); | |
615 | return ret; | |
616 | } | |
617 | ||
618 | /* | |
619 | * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB | |
620 | * shm segments) get accounted against the user_struct instead. | |
621 | */ | |
622 | static DEFINE_SPINLOCK(shmlock_user_lock); | |
623 | ||
624 | int user_shm_lock(size_t size, struct user_struct *user) | |
625 | { | |
626 | unsigned long lock_limit, locked; | |
627 | int allowed = 0; | |
628 | ||
629 | locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
630 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; | |
5ed44a40 HB |
631 | if (lock_limit == RLIM_INFINITY) |
632 | allowed = 1; | |
1da177e4 LT |
633 | lock_limit >>= PAGE_SHIFT; |
634 | spin_lock(&shmlock_user_lock); | |
5ed44a40 HB |
635 | if (!allowed && |
636 | locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) | |
1da177e4 LT |
637 | goto out; |
638 | get_uid(user); | |
639 | user->locked_shm += locked; | |
640 | allowed = 1; | |
641 | out: | |
642 | spin_unlock(&shmlock_user_lock); | |
643 | return allowed; | |
644 | } | |
645 | ||
646 | void user_shm_unlock(size_t size, struct user_struct *user) | |
647 | { | |
648 | spin_lock(&shmlock_user_lock); | |
649 | user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
650 | spin_unlock(&shmlock_user_lock); | |
651 | free_uid(user); | |
652 | } |