| 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/mempolicy.h> |
| 15 | #include <linux/syscalls.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/export.h> |
| 18 | #include <linux/rmap.h> |
| 19 | #include <linux/mmzone.h> |
| 20 | #include <linux/hugetlb.h> |
| 21 | |
| 22 | #include "internal.h" |
| 23 | |
| 24 | int can_do_mlock(void) |
| 25 | { |
| 26 | if (capable(CAP_IPC_LOCK)) |
| 27 | return 1; |
| 28 | if (rlimit(RLIMIT_MEMLOCK) != 0) |
| 29 | return 1; |
| 30 | return 0; |
| 31 | } |
| 32 | EXPORT_SYMBOL(can_do_mlock); |
| 33 | |
| 34 | /* |
| 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 | */ |
| 54 | void clear_page_mlock(struct page *page) |
| 55 | { |
| 56 | if (!TestClearPageMlocked(page)) |
| 57 | return; |
| 58 | |
| 59 | mod_zone_page_state(page_zone(page), NR_MLOCK, |
| 60 | -hpage_nr_pages(page)); |
| 61 | count_vm_event(UNEVICTABLE_PGCLEARED); |
| 62 | if (!isolate_lru_page(page)) { |
| 63 | putback_lru_page(page); |
| 64 | } else { |
| 65 | /* |
| 66 | * We lost the race. the page already moved to evictable list. |
| 67 | */ |
| 68 | if (PageUnevictable(page)) |
| 69 | count_vm_event(UNEVICTABLE_PGSTRANDED); |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | /* |
| 74 | * Mark page as mlocked if not already. |
| 75 | * If page on LRU, isolate and putback to move to unevictable list. |
| 76 | */ |
| 77 | void mlock_vma_page(struct page *page) |
| 78 | { |
| 79 | /* Serialize with page migration */ |
| 80 | BUG_ON(!PageLocked(page)); |
| 81 | |
| 82 | if (!TestSetPageMlocked(page)) { |
| 83 | mod_zone_page_state(page_zone(page), NR_MLOCK, |
| 84 | hpage_nr_pages(page)); |
| 85 | count_vm_event(UNEVICTABLE_PGMLOCKED); |
| 86 | if (!isolate_lru_page(page)) |
| 87 | putback_lru_page(page); |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * munlock_vma_page - munlock a vma page |
| 93 | * @page - page to be unlocked |
| 94 | * |
| 95 | * 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. |
| 105 | */ |
| 106 | unsigned int munlock_vma_page(struct page *page) |
| 107 | { |
| 108 | unsigned int page_mask = 0; |
| 109 | |
| 110 | /* For try_to_munlock() and to serialize with page migration */ |
| 111 | BUG_ON(!PageLocked(page)); |
| 112 | |
| 113 | if (TestClearPageMlocked(page)) { |
| 114 | unsigned int nr_pages = hpage_nr_pages(page); |
| 115 | mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); |
| 116 | page_mask = nr_pages - 1; |
| 117 | if (!isolate_lru_page(page)) { |
| 118 | int ret = SWAP_AGAIN; |
| 119 | |
| 120 | /* |
| 121 | * Optimization: if the page was mapped just once, |
| 122 | * that's our mapping and we don't need to check all the |
| 123 | * other vmas. |
| 124 | */ |
| 125 | if (page_mapcount(page) > 1) |
| 126 | ret = try_to_munlock(page); |
| 127 | /* |
| 128 | * did try_to_unlock() succeed or punt? |
| 129 | */ |
| 130 | if (ret != SWAP_MLOCK) |
| 131 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); |
| 132 | |
| 133 | putback_lru_page(page); |
| 134 | } else { |
| 135 | /* |
| 136 | * Some other task has removed the page from the LRU. |
| 137 | * putback_lru_page() will take care of removing the |
| 138 | * page from the unevictable list, if necessary. |
| 139 | * vmscan [page_referenced()] will move the page back |
| 140 | * to the unevictable list if some other vma has it |
| 141 | * mlocked. |
| 142 | */ |
| 143 | if (PageUnevictable(page)) |
| 144 | count_vm_event(UNEVICTABLE_PGSTRANDED); |
| 145 | else |
| 146 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | return page_mask; |
| 151 | } |
| 152 | |
| 153 | /** |
| 154 | * __mlock_vma_pages_range() - mlock a range of pages in the vma. |
| 155 | * @vma: target vma |
| 156 | * @start: start address |
| 157 | * @end: end address |
| 158 | * |
| 159 | * This takes care of making the pages present too. |
| 160 | * |
| 161 | * return 0 on success, negative error code on error. |
| 162 | * |
| 163 | * vma->vm_mm->mmap_sem must be held for at least read. |
| 164 | */ |
| 165 | long __mlock_vma_pages_range(struct vm_area_struct *vma, |
| 166 | unsigned long start, unsigned long end, int *nonblocking) |
| 167 | { |
| 168 | struct mm_struct *mm = vma->vm_mm; |
| 169 | unsigned long nr_pages = (end - start) / PAGE_SIZE; |
| 170 | int gup_flags; |
| 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 | |
| 178 | gup_flags = FOLL_TOUCH | FOLL_MLOCK; |
| 179 | /* |
| 180 | * We want to touch writable mappings with a write fault in order |
| 181 | * to break COW, except for shared mappings because these don't COW |
| 182 | * and we would not want to dirty them for nothing. |
| 183 | */ |
| 184 | if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE) |
| 185 | gup_flags |= FOLL_WRITE; |
| 186 | |
| 187 | /* |
| 188 | * We want mlock to succeed for regions that have any permissions |
| 189 | * other than PROT_NONE. |
| 190 | */ |
| 191 | if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) |
| 192 | gup_flags |= FOLL_FORCE; |
| 193 | |
| 194 | /* |
| 195 | * We made sure addr is within a VMA, so the following will |
| 196 | * not result in a stack expansion that recurses back here. |
| 197 | */ |
| 198 | return __get_user_pages(current, mm, start, nr_pages, gup_flags, |
| 199 | NULL, NULL, nonblocking); |
| 200 | } |
| 201 | |
| 202 | /* |
| 203 | * convert get_user_pages() return value to posix mlock() error |
| 204 | */ |
| 205 | static int __mlock_posix_error_return(long retval) |
| 206 | { |
| 207 | if (retval == -EFAULT) |
| 208 | retval = -ENOMEM; |
| 209 | else if (retval == -ENOMEM) |
| 210 | retval = -EAGAIN; |
| 211 | return retval; |
| 212 | } |
| 213 | |
| 214 | /* |
| 215 | * munlock_vma_pages_range() - munlock all pages in the vma range.' |
| 216 | * @vma - vma containing range to be munlock()ed. |
| 217 | * @start - start address in @vma of the range |
| 218 | * @end - end of range in @vma. |
| 219 | * |
| 220 | * For mremap(), munmap() and exit(). |
| 221 | * |
| 222 | * Called with @vma VM_LOCKED. |
| 223 | * |
| 224 | * Returns with VM_LOCKED cleared. Callers must be prepared to |
| 225 | * deal with this. |
| 226 | * |
| 227 | * We don't save and restore VM_LOCKED here because pages are |
| 228 | * still on lru. In unmap path, pages might be scanned by reclaim |
| 229 | * and re-mlocked by try_to_{munlock|unmap} before we unmap and |
| 230 | * free them. This will result in freeing mlocked pages. |
| 231 | */ |
| 232 | void munlock_vma_pages_range(struct vm_area_struct *vma, |
| 233 | unsigned long start, unsigned long end) |
| 234 | { |
| 235 | vma->vm_flags &= ~VM_LOCKED; |
| 236 | |
| 237 | while (start < end) { |
| 238 | struct page *page; |
| 239 | unsigned int page_mask, page_increm; |
| 240 | |
| 241 | /* |
| 242 | * Although FOLL_DUMP is intended for get_dump_page(), |
| 243 | * it just so happens that its special treatment of the |
| 244 | * ZERO_PAGE (returning an error instead of doing get_page) |
| 245 | * suits munlock very well (and if somehow an abnormal page |
| 246 | * has sneaked into the range, we won't oops here: great). |
| 247 | */ |
| 248 | page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP, |
| 249 | &page_mask); |
| 250 | if (page && !IS_ERR(page)) { |
| 251 | lock_page(page); |
| 252 | lru_add_drain(); |
| 253 | /* |
| 254 | * Any THP page found by follow_page_mask() may have |
| 255 | * gotten split before reaching munlock_vma_page(), |
| 256 | * so we need to recompute the page_mask here. |
| 257 | */ |
| 258 | page_mask = munlock_vma_page(page); |
| 259 | unlock_page(page); |
| 260 | put_page(page); |
| 261 | } |
| 262 | page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); |
| 263 | start += page_increm * PAGE_SIZE; |
| 264 | cond_resched(); |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * mlock_fixup - handle mlock[all]/munlock[all] requests. |
| 270 | * |
| 271 | * Filters out "special" vmas -- VM_LOCKED never gets set for these, and |
| 272 | * munlock is a no-op. However, for some special vmas, we go ahead and |
| 273 | * populate the ptes. |
| 274 | * |
| 275 | * For vmas that pass the filters, merge/split as appropriate. |
| 276 | */ |
| 277 | static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, |
| 278 | unsigned long start, unsigned long end, vm_flags_t newflags) |
| 279 | { |
| 280 | struct mm_struct *mm = vma->vm_mm; |
| 281 | pgoff_t pgoff; |
| 282 | int nr_pages; |
| 283 | int ret = 0; |
| 284 | int lock = !!(newflags & VM_LOCKED); |
| 285 | |
| 286 | if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) || |
| 287 | is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm)) |
| 288 | goto out; /* don't set VM_LOCKED, don't count */ |
| 289 | |
| 290 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
| 291 | *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, |
| 292 | vma->vm_file, pgoff, vma_policy(vma), |
| 293 | vma_get_anon_name(vma)); |
| 294 | if (*prev) { |
| 295 | vma = *prev; |
| 296 | goto success; |
| 297 | } |
| 298 | |
| 299 | if (start != vma->vm_start) { |
| 300 | ret = split_vma(mm, vma, start, 1); |
| 301 | if (ret) |
| 302 | goto out; |
| 303 | } |
| 304 | |
| 305 | if (end != vma->vm_end) { |
| 306 | ret = split_vma(mm, vma, end, 0); |
| 307 | if (ret) |
| 308 | goto out; |
| 309 | } |
| 310 | |
| 311 | success: |
| 312 | /* |
| 313 | * Keep track of amount of locked VM. |
| 314 | */ |
| 315 | nr_pages = (end - start) >> PAGE_SHIFT; |
| 316 | if (!lock) |
| 317 | nr_pages = -nr_pages; |
| 318 | mm->locked_vm += nr_pages; |
| 319 | |
| 320 | /* |
| 321 | * vm_flags is protected by the mmap_sem held in write mode. |
| 322 | * It's okay if try_to_unmap_one unmaps a page just after we |
| 323 | * set VM_LOCKED, __mlock_vma_pages_range will bring it back. |
| 324 | */ |
| 325 | |
| 326 | if (lock) |
| 327 | vma->vm_flags = newflags; |
| 328 | else |
| 329 | munlock_vma_pages_range(vma, start, end); |
| 330 | |
| 331 | out: |
| 332 | *prev = vma; |
| 333 | return ret; |
| 334 | } |
| 335 | |
| 336 | static int do_mlock(unsigned long start, size_t len, int on) |
| 337 | { |
| 338 | unsigned long nstart, end, tmp; |
| 339 | struct vm_area_struct * vma, * prev; |
| 340 | int error; |
| 341 | |
| 342 | VM_BUG_ON(start & ~PAGE_MASK); |
| 343 | VM_BUG_ON(len != PAGE_ALIGN(len)); |
| 344 | end = start + len; |
| 345 | if (end < start) |
| 346 | return -EINVAL; |
| 347 | if (end == start) |
| 348 | return 0; |
| 349 | vma = find_vma(current->mm, start); |
| 350 | if (!vma || vma->vm_start > start) |
| 351 | return -ENOMEM; |
| 352 | |
| 353 | prev = vma->vm_prev; |
| 354 | if (start > vma->vm_start) |
| 355 | prev = vma; |
| 356 | |
| 357 | for (nstart = start ; ; ) { |
| 358 | vm_flags_t newflags; |
| 359 | |
| 360 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
| 361 | |
| 362 | newflags = vma->vm_flags & ~VM_LOCKED; |
| 363 | if (on) |
| 364 | newflags |= VM_LOCKED; |
| 365 | |
| 366 | tmp = vma->vm_end; |
| 367 | if (tmp > end) |
| 368 | tmp = end; |
| 369 | error = mlock_fixup(vma, &prev, nstart, tmp, newflags); |
| 370 | if (error) |
| 371 | break; |
| 372 | nstart = tmp; |
| 373 | if (nstart < prev->vm_end) |
| 374 | nstart = prev->vm_end; |
| 375 | if (nstart >= end) |
| 376 | break; |
| 377 | |
| 378 | vma = prev->vm_next; |
| 379 | if (!vma || vma->vm_start != nstart) { |
| 380 | error = -ENOMEM; |
| 381 | break; |
| 382 | } |
| 383 | } |
| 384 | return error; |
| 385 | } |
| 386 | |
| 387 | /* |
| 388 | * __mm_populate - populate and/or mlock pages within a range of address space. |
| 389 | * |
| 390 | * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap |
| 391 | * flags. VMAs must be already marked with the desired vm_flags, and |
| 392 | * mmap_sem must not be held. |
| 393 | */ |
| 394 | int __mm_populate(unsigned long start, unsigned long len, int ignore_errors) |
| 395 | { |
| 396 | struct mm_struct *mm = current->mm; |
| 397 | unsigned long end, nstart, nend; |
| 398 | struct vm_area_struct *vma = NULL; |
| 399 | int locked = 0; |
| 400 | long ret = 0; |
| 401 | |
| 402 | VM_BUG_ON(start & ~PAGE_MASK); |
| 403 | VM_BUG_ON(len != PAGE_ALIGN(len)); |
| 404 | end = start + len; |
| 405 | |
| 406 | for (nstart = start; nstart < end; nstart = nend) { |
| 407 | /* |
| 408 | * We want to fault in pages for [nstart; end) address range. |
| 409 | * Find first corresponding VMA. |
| 410 | */ |
| 411 | if (!locked) { |
| 412 | locked = 1; |
| 413 | down_read(&mm->mmap_sem); |
| 414 | vma = find_vma(mm, nstart); |
| 415 | } else if (nstart >= vma->vm_end) |
| 416 | vma = vma->vm_next; |
| 417 | if (!vma || vma->vm_start >= end) |
| 418 | break; |
| 419 | /* |
| 420 | * Set [nstart; nend) to intersection of desired address |
| 421 | * range with the first VMA. Also, skip undesirable VMA types. |
| 422 | */ |
| 423 | nend = min(end, vma->vm_end); |
| 424 | if (vma->vm_flags & (VM_IO | VM_PFNMAP)) |
| 425 | continue; |
| 426 | if (nstart < vma->vm_start) |
| 427 | nstart = vma->vm_start; |
| 428 | /* |
| 429 | * Now fault in a range of pages. __mlock_vma_pages_range() |
| 430 | * double checks the vma flags, so that it won't mlock pages |
| 431 | * if the vma was already munlocked. |
| 432 | */ |
| 433 | ret = __mlock_vma_pages_range(vma, nstart, nend, &locked); |
| 434 | if (ret < 0) { |
| 435 | if (ignore_errors) { |
| 436 | ret = 0; |
| 437 | continue; /* continue at next VMA */ |
| 438 | } |
| 439 | ret = __mlock_posix_error_return(ret); |
| 440 | break; |
| 441 | } |
| 442 | nend = nstart + ret * PAGE_SIZE; |
| 443 | ret = 0; |
| 444 | } |
| 445 | if (locked) |
| 446 | up_read(&mm->mmap_sem); |
| 447 | return ret; /* 0 or negative error code */ |
| 448 | } |
| 449 | |
| 450 | SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) |
| 451 | { |
| 452 | unsigned long locked; |
| 453 | unsigned long lock_limit; |
| 454 | int error = -ENOMEM; |
| 455 | |
| 456 | if (!can_do_mlock()) |
| 457 | return -EPERM; |
| 458 | |
| 459 | lru_add_drain_all(); /* flush pagevec */ |
| 460 | |
| 461 | down_write(¤t->mm->mmap_sem); |
| 462 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 463 | start &= PAGE_MASK; |
| 464 | |
| 465 | locked = len >> PAGE_SHIFT; |
| 466 | locked += current->mm->locked_vm; |
| 467 | |
| 468 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
| 469 | lock_limit >>= PAGE_SHIFT; |
| 470 | |
| 471 | /* check against resource limits */ |
| 472 | if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) |
| 473 | error = do_mlock(start, len, 1); |
| 474 | up_write(¤t->mm->mmap_sem); |
| 475 | if (!error) |
| 476 | error = __mm_populate(start, len, 0); |
| 477 | return error; |
| 478 | } |
| 479 | |
| 480 | SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) |
| 481 | { |
| 482 | int ret; |
| 483 | |
| 484 | down_write(¤t->mm->mmap_sem); |
| 485 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 486 | start &= PAGE_MASK; |
| 487 | ret = do_mlock(start, len, 0); |
| 488 | up_write(¤t->mm->mmap_sem); |
| 489 | return ret; |
| 490 | } |
| 491 | |
| 492 | static int do_mlockall(int flags) |
| 493 | { |
| 494 | struct vm_area_struct * vma, * prev = NULL; |
| 495 | |
| 496 | if (flags & MCL_FUTURE) |
| 497 | current->mm->def_flags |= VM_LOCKED; |
| 498 | else |
| 499 | current->mm->def_flags &= ~VM_LOCKED; |
| 500 | if (flags == MCL_FUTURE) |
| 501 | goto out; |
| 502 | |
| 503 | for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { |
| 504 | vm_flags_t newflags; |
| 505 | |
| 506 | newflags = vma->vm_flags & ~VM_LOCKED; |
| 507 | if (flags & MCL_CURRENT) |
| 508 | newflags |= VM_LOCKED; |
| 509 | |
| 510 | /* Ignore errors */ |
| 511 | mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); |
| 512 | } |
| 513 | out: |
| 514 | return 0; |
| 515 | } |
| 516 | |
| 517 | SYSCALL_DEFINE1(mlockall, int, flags) |
| 518 | { |
| 519 | unsigned long lock_limit; |
| 520 | int ret = -EINVAL; |
| 521 | |
| 522 | if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) |
| 523 | goto out; |
| 524 | |
| 525 | ret = -EPERM; |
| 526 | if (!can_do_mlock()) |
| 527 | goto out; |
| 528 | |
| 529 | if (flags & MCL_CURRENT) |
| 530 | lru_add_drain_all(); /* flush pagevec */ |
| 531 | |
| 532 | down_write(¤t->mm->mmap_sem); |
| 533 | |
| 534 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
| 535 | lock_limit >>= PAGE_SHIFT; |
| 536 | |
| 537 | ret = -ENOMEM; |
| 538 | if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || |
| 539 | capable(CAP_IPC_LOCK)) |
| 540 | ret = do_mlockall(flags); |
| 541 | up_write(¤t->mm->mmap_sem); |
| 542 | if (!ret && (flags & MCL_CURRENT)) |
| 543 | mm_populate(0, TASK_SIZE); |
| 544 | out: |
| 545 | return ret; |
| 546 | } |
| 547 | |
| 548 | SYSCALL_DEFINE0(munlockall) |
| 549 | { |
| 550 | int ret; |
| 551 | |
| 552 | down_write(¤t->mm->mmap_sem); |
| 553 | ret = do_mlockall(0); |
| 554 | up_write(¤t->mm->mmap_sem); |
| 555 | return ret; |
| 556 | } |
| 557 | |
| 558 | /* |
| 559 | * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB |
| 560 | * shm segments) get accounted against the user_struct instead. |
| 561 | */ |
| 562 | static DEFINE_SPINLOCK(shmlock_user_lock); |
| 563 | |
| 564 | int user_shm_lock(size_t size, struct user_struct *user) |
| 565 | { |
| 566 | unsigned long lock_limit, locked; |
| 567 | int allowed = 0; |
| 568 | |
| 569 | locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 570 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
| 571 | if (lock_limit == RLIM_INFINITY) |
| 572 | allowed = 1; |
| 573 | lock_limit >>= PAGE_SHIFT; |
| 574 | spin_lock(&shmlock_user_lock); |
| 575 | if (!allowed && |
| 576 | locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) |
| 577 | goto out; |
| 578 | get_uid(user); |
| 579 | user->locked_shm += locked; |
| 580 | allowed = 1; |
| 581 | out: |
| 582 | spin_unlock(&shmlock_user_lock); |
| 583 | return allowed; |
| 584 | } |
| 585 | |
| 586 | void user_shm_unlock(size_t size, struct user_struct *user) |
| 587 | { |
| 588 | spin_lock(&shmlock_user_lock); |
| 589 | user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 590 | spin_unlock(&shmlock_user_lock); |
| 591 | free_uid(user); |
| 592 | } |