1 /* 2 * linux/mm/mlock.c 3 * 4 * (C) Copyright 1995 Linus Torvalds 5 * (C) Copyright 2002 Christoph Hellwig 6 */ 7 8 #include <linux/capability.h> 9 #include <linux/mman.h> 10 #include <linux/mm.h> 11 #include <linux/swap.h> 12 #include <linux/swapops.h> 13 #include <linux/pagemap.h> 14 #include <linux/pagevec.h> 15 #include <linux/mempolicy.h> 16 #include <linux/syscalls.h> 17 #include <linux/sched.h> 18 #include <linux/export.h> 19 #include <linux/rmap.h> 20 #include <linux/mmzone.h> 21 #include <linux/hugetlb.h> 22 #include <linux/memcontrol.h> 23 #include <linux/mm_inline.h> 24 25 #include "internal.h" 26 27 int can_do_mlock(void) 28 { 29 if (capable(CAP_IPC_LOCK)) 30 return 1; 31 if (rlimit(RLIMIT_MEMLOCK) != 0) 32 return 1; 33 return 0; 34 } 35 EXPORT_SYMBOL(can_do_mlock); 36 37 /* 38 * Mlocked pages are marked with PageMlocked() flag for efficient testing 39 * in vmscan and, possibly, the fault path; and to support semi-accurate 40 * statistics. 41 * 42 * An mlocked page [PageMlocked(page)] is unevictable. As such, it will 43 * be placed on the LRU "unevictable" list, rather than the [in]active lists. 44 * The unevictable list is an LRU sibling list to the [in]active lists. 45 * PageUnevictable is set to indicate the unevictable state. 46 * 47 * When lazy mlocking via vmscan, it is important to ensure that the 48 * vma's VM_LOCKED status is not concurrently being modified, otherwise we 49 * may have mlocked a page that is being munlocked. So lazy mlock must take 50 * the mmap_sem for read, and verify that the vma really is locked 51 * (see mm/rmap.c). 52 */ 53 54 /* 55 * LRU accounting for clear_page_mlock() 56 */ 57 void clear_page_mlock(struct page *page) 58 { 59 if (!TestClearPageMlocked(page)) 60 return; 61 62 mod_zone_page_state(page_zone(page), NR_MLOCK, 63 -hpage_nr_pages(page)); 64 count_vm_event(UNEVICTABLE_PGCLEARED); 65 if (!isolate_lru_page(page)) { 66 putback_lru_page(page); 67 } else { 68 /* 69 * We lost the race. the page already moved to evictable list. 70 */ 71 if (PageUnevictable(page)) 72 count_vm_event(UNEVICTABLE_PGSTRANDED); 73 } 74 } 75 76 /* 77 * Mark page as mlocked if not already. 78 * If page on LRU, isolate and putback to move to unevictable list. 79 */ 80 void mlock_vma_page(struct page *page) 81 { 82 BUG_ON(!PageLocked(page)); 83 84 if (!TestSetPageMlocked(page)) { 85 mod_zone_page_state(page_zone(page), NR_MLOCK, 86 hpage_nr_pages(page)); 87 count_vm_event(UNEVICTABLE_PGMLOCKED); 88 if (!isolate_lru_page(page)) 89 putback_lru_page(page); 90 } 91 } 92 93 /* 94 * Finish munlock after successful page isolation 95 * 96 * Page must be locked. This is a wrapper for try_to_munlock() 97 * and putback_lru_page() with munlock accounting. 98 */ 99 static void __munlock_isolated_page(struct page *page) 100 { 101 int ret = SWAP_AGAIN; 102 103 /* 104 * Optimization: if the page was mapped just once, that's our mapping 105 * and we don't need to check all the other vmas. 106 */ 107 if (page_mapcount(page) > 1) 108 ret = try_to_munlock(page); 109 110 /* Did try_to_unlock() succeed or punt? */ 111 if (ret != SWAP_MLOCK) 112 count_vm_event(UNEVICTABLE_PGMUNLOCKED); 113 114 putback_lru_page(page); 115 } 116 117 /* 118 * Accounting for page isolation fail during munlock 119 * 120 * Performs accounting when page isolation fails in munlock. There is nothing 121 * else to do because it means some other task has already removed the page 122 * from the LRU. putback_lru_page() will take care of removing the page from 123 * the unevictable list, if necessary. vmscan [page_referenced()] will move 124 * the page back to the unevictable list if some other vma has it mlocked. 125 */ 126 static void __munlock_isolation_failed(struct page *page) 127 { 128 if (PageUnevictable(page)) 129 count_vm_event(UNEVICTABLE_PGSTRANDED); 130 else 131 count_vm_event(UNEVICTABLE_PGMUNLOCKED); 132 } 133 134 /** 135 * munlock_vma_page - munlock a vma page 136 * @page - page to be unlocked, either a normal page or THP page head 137 * 138 * returns the size of the page as a page mask (0 for normal page, 139 * HPAGE_PMD_NR - 1 for THP head page) 140 * 141 * called from munlock()/munmap() path with page supposedly on the LRU. 142 * When we munlock a page, because the vma where we found the page is being 143 * munlock()ed or munmap()ed, we want to check whether other vmas hold the 144 * page locked so that we can leave it on the unevictable lru list and not 145 * bother vmscan with it. However, to walk the page's rmap list in 146 * try_to_munlock() we must isolate the page from the LRU. If some other 147 * task has removed the page from the LRU, we won't be able to do that. 148 * So we clear the PageMlocked as we might not get another chance. If we 149 * can't isolate the page, we leave it for putback_lru_page() and vmscan 150 * [page_referenced()/try_to_unmap()] to deal with. 151 */ 152 unsigned int munlock_vma_page(struct page *page) 153 { 154 unsigned int nr_pages; 155 156 BUG_ON(!PageLocked(page)); 157 158 if (TestClearPageMlocked(page)) { 159 nr_pages = hpage_nr_pages(page); 160 mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); 161 if (!isolate_lru_page(page)) 162 __munlock_isolated_page(page); 163 else 164 __munlock_isolation_failed(page); 165 } else { 166 nr_pages = hpage_nr_pages(page); 167 } 168 169 /* 170 * Regardless of the original PageMlocked flag, we determine nr_pages 171 * after touching the flag. This leaves a possible race with a THP page 172 * split, such that a whole THP page was munlocked, but nr_pages == 1. 173 * Returning a smaller mask due to that is OK, the worst that can 174 * happen is subsequent useless scanning of the former tail pages. 175 * The NR_MLOCK accounting can however become broken. 176 */ 177 return nr_pages - 1; 178 } 179 180 /** 181 * __mlock_vma_pages_range() - mlock a range of pages in the vma. 182 * @vma: target vma 183 * @start: start address 184 * @end: end address 185 * 186 * This takes care of making the pages present too. 187 * 188 * return 0 on success, negative error code on error. 189 * 190 * vma->vm_mm->mmap_sem must be held for at least read. 191 */ 192 long __mlock_vma_pages_range(struct vm_area_struct *vma, 193 unsigned long start, unsigned long end, int *nonblocking) 194 { 195 struct mm_struct *mm = vma->vm_mm; 196 unsigned long nr_pages = (end - start) / PAGE_SIZE; 197 int gup_flags; 198 199 VM_BUG_ON(start & ~PAGE_MASK); 200 VM_BUG_ON(end & ~PAGE_MASK); 201 VM_BUG_ON(start < vma->vm_start); 202 VM_BUG_ON(end > vma->vm_end); 203 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); 204 205 gup_flags = FOLL_TOUCH | FOLL_MLOCK; 206 /* 207 * We want to touch writable mappings with a write fault in order 208 * to break COW, except for shared mappings because these don't COW 209 * and we would not want to dirty them for nothing. 210 */ 211 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE) 212 gup_flags |= FOLL_WRITE; 213 214 /* 215 * We want mlock to succeed for regions that have any permissions 216 * other than PROT_NONE. 217 */ 218 if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) 219 gup_flags |= FOLL_FORCE; 220 221 /* 222 * We made sure addr is within a VMA, so the following will 223 * not result in a stack expansion that recurses back here. 224 */ 225 return __get_user_pages(current, mm, start, nr_pages, gup_flags, 226 NULL, NULL, nonblocking); 227 } 228 229 /* 230 * convert get_user_pages() return value to posix mlock() error 231 */ 232 static int __mlock_posix_error_return(long retval) 233 { 234 if (retval == -EFAULT) 235 retval = -ENOMEM; 236 else if (retval == -ENOMEM) 237 retval = -EAGAIN; 238 return retval; 239 } 240 241 /* 242 * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec() 243 * 244 * The fast path is available only for evictable pages with single mapping. 245 * Then we can bypass the per-cpu pvec and get better performance. 246 * when mapcount > 1 we need try_to_munlock() which can fail. 247 * when !page_evictable(), we need the full redo logic of putback_lru_page to 248 * avoid leaving evictable page in unevictable list. 249 * 250 * In case of success, @page is added to @pvec and @pgrescued is incremented 251 * in case that the page was previously unevictable. @page is also unlocked. 252 */ 253 static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec, 254 int *pgrescued) 255 { 256 VM_BUG_ON(PageLRU(page)); 257 VM_BUG_ON(!PageLocked(page)); 258 259 if (page_mapcount(page) <= 1 && page_evictable(page)) { 260 pagevec_add(pvec, page); 261 if (TestClearPageUnevictable(page)) 262 (*pgrescued)++; 263 unlock_page(page); 264 return true; 265 } 266 267 return false; 268 } 269 270 /* 271 * Putback multiple evictable pages to the LRU 272 * 273 * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of 274 * the pages might have meanwhile become unevictable but that is OK. 275 */ 276 static void __putback_lru_fast(struct pagevec *pvec, int pgrescued) 277 { 278 count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec)); 279 /* 280 *__pagevec_lru_add() calls release_pages() so we don't call 281 * put_page() explicitly 282 */ 283 __pagevec_lru_add(pvec); 284 count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); 285 } 286 287 /* 288 * Munlock a batch of pages from the same zone 289 * 290 * The work is split to two main phases. First phase clears the Mlocked flag 291 * and attempts to isolate the pages, all under a single zone lru lock. 292 * The second phase finishes the munlock only for pages where isolation 293 * succeeded. 294 * 295 * Note that the pagevec may be modified during the process. 296 */ 297 static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) 298 { 299 int i; 300 int nr = pagevec_count(pvec); 301 int delta_munlocked; 302 struct pagevec pvec_putback; 303 int pgrescued = 0; 304 305 pagevec_init(&pvec_putback, 0); 306 307 /* Phase 1: page isolation */ 308 spin_lock_irq(&zone->lru_lock); 309 for (i = 0; i < nr; i++) { 310 struct page *page = pvec->pages[i]; 311 312 if (TestClearPageMlocked(page)) { 313 struct lruvec *lruvec; 314 int lru; 315 316 if (PageLRU(page)) { 317 lruvec = mem_cgroup_page_lruvec(page, zone); 318 lru = page_lru(page); 319 /* 320 * We already have pin from follow_page_mask() 321 * so we can spare the get_page() here. 322 */ 323 ClearPageLRU(page); 324 del_page_from_lru_list(page, lruvec, lru); 325 } else { 326 __munlock_isolation_failed(page); 327 goto skip_munlock; 328 } 329 330 } else { 331 skip_munlock: 332 /* 333 * We won't be munlocking this page in the next phase 334 * but we still need to release the follow_page_mask() 335 * pin. We cannot do it under lru_lock however. If it's 336 * the last pin, __page_cache_release would deadlock. 337 */ 338 pagevec_add(&pvec_putback, pvec->pages[i]); 339 pvec->pages[i] = NULL; 340 } 341 } 342 delta_munlocked = -nr + pagevec_count(&pvec_putback); 343 __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); 344 spin_unlock_irq(&zone->lru_lock); 345 346 /* Now we can release pins of pages that we are not munlocking */ 347 pagevec_release(&pvec_putback); 348 349 /* Phase 2: page munlock */ 350 for (i = 0; i < nr; i++) { 351 struct page *page = pvec->pages[i]; 352 353 if (page) { 354 lock_page(page); 355 if (!__putback_lru_fast_prepare(page, &pvec_putback, 356 &pgrescued)) { 357 /* 358 * Slow path. We don't want to lose the last 359 * pin before unlock_page() 360 */ 361 get_page(page); /* for putback_lru_page() */ 362 __munlock_isolated_page(page); 363 unlock_page(page); 364 put_page(page); /* from follow_page_mask() */ 365 } 366 } 367 } 368 369 /* 370 * Phase 3: page putback for pages that qualified for the fast path 371 * This will also call put_page() to return pin from follow_page_mask() 372 */ 373 if (pagevec_count(&pvec_putback)) 374 __putback_lru_fast(&pvec_putback, pgrescued); 375 } 376 377 /* 378 * Fill up pagevec for __munlock_pagevec using pte walk 379 * 380 * The function expects that the struct page corresponding to @start address is 381 * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone. 382 * 383 * The rest of @pvec is filled by subsequent pages within the same pmd and same 384 * zone, as long as the pte's are present and vm_normal_page() succeeds. These 385 * pages also get pinned. 386 * 387 * Returns the address of the next page that should be scanned. This equals 388 * @start + PAGE_SIZE when no page could be added by the pte walk. 389 */ 390 static unsigned long __munlock_pagevec_fill(struct pagevec *pvec, 391 struct vm_area_struct *vma, int zoneid, unsigned long start, 392 unsigned long end) 393 { 394 pte_t *pte; 395 spinlock_t *ptl; 396 397 /* 398 * Initialize pte walk starting at the already pinned page where we 399 * are sure that there is a pte, as it was pinned under the same 400 * mmap_sem write op. 401 */ 402 pte = get_locked_pte(vma->vm_mm, start, &ptl); 403 /* Make sure we do not cross the page table boundary */ 404 end = pgd_addr_end(start, end); 405 end = pud_addr_end(start, end); 406 end = pmd_addr_end(start, end); 407 408 /* The page next to the pinned page is the first we will try to get */ 409 start += PAGE_SIZE; 410 while (start < end) { 411 struct page *page = NULL; 412 pte++; 413 if (pte_present(*pte)) 414 page = vm_normal_page(vma, start, *pte); 415 /* 416 * Break if page could not be obtained or the page's node+zone does not 417 * match 418 */ 419 if (!page || page_zone_id(page) != zoneid) 420 break; 421 422 get_page(page); 423 /* 424 * Increase the address that will be returned *before* the 425 * eventual break due to pvec becoming full by adding the page 426 */ 427 start += PAGE_SIZE; 428 if (pagevec_add(pvec, page) == 0) 429 break; 430 } 431 pte_unmap_unlock(pte, ptl); 432 return start; 433 } 434 435 /* 436 * munlock_vma_pages_range() - munlock all pages in the vma range.' 437 * @vma - vma containing range to be munlock()ed. 438 * @start - start address in @vma of the range 439 * @end - end of range in @vma. 440 * 441 * For mremap(), munmap() and exit(). 442 * 443 * Called with @vma VM_LOCKED. 444 * 445 * Returns with VM_LOCKED cleared. Callers must be prepared to 446 * deal with this. 447 * 448 * We don't save and restore VM_LOCKED here because pages are 449 * still on lru. In unmap path, pages might be scanned by reclaim 450 * and re-mlocked by try_to_{munlock|unmap} before we unmap and 451 * free them. This will result in freeing mlocked pages. 452 */ 453 void munlock_vma_pages_range(struct vm_area_struct *vma, 454 unsigned long start, unsigned long end) 455 { 456 vma->vm_flags &= ~VM_LOCKED; 457 458 while (start < end) { 459 struct page *page = NULL; 460 unsigned int page_mask; 461 unsigned long page_increm; 462 struct pagevec pvec; 463 struct zone *zone; 464 int zoneid; 465 466 pagevec_init(&pvec, 0); 467 /* 468 * Although FOLL_DUMP is intended for get_dump_page(), 469 * it just so happens that its special treatment of the 470 * ZERO_PAGE (returning an error instead of doing get_page) 471 * suits munlock very well (and if somehow an abnormal page 472 * has sneaked into the range, we won't oops here: great). 473 */ 474 page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP, 475 &page_mask); 476 477 if (page && !IS_ERR(page)) { 478 if (PageTransHuge(page)) { 479 lock_page(page); 480 /* 481 * Any THP page found by follow_page_mask() may 482 * have gotten split before reaching 483 * munlock_vma_page(), so we need to recompute 484 * the page_mask here. 485 */ 486 page_mask = munlock_vma_page(page); 487 unlock_page(page); 488 put_page(page); /* follow_page_mask() */ 489 } else { 490 /* 491 * Non-huge pages are handled in batches via 492 * pagevec. The pin from follow_page_mask() 493 * prevents them from collapsing by THP. 494 */ 495 pagevec_add(&pvec, page); 496 zone = page_zone(page); 497 zoneid = page_zone_id(page); 498 499 /* 500 * Try to fill the rest of pagevec using fast 501 * pte walk. This will also update start to 502 * the next page to process. Then munlock the 503 * pagevec. 504 */ 505 start = __munlock_pagevec_fill(&pvec, vma, 506 zoneid, start, end); 507 __munlock_pagevec(&pvec, zone); 508 goto next; 509 } 510 } 511 /* It's a bug to munlock in the middle of a THP page */ 512 VM_BUG_ON((start >> PAGE_SHIFT) & page_mask); 513 page_increm = 1 + page_mask; 514 start += page_increm * PAGE_SIZE; 515 next: 516 cond_resched(); 517 } 518 } 519 520 /* 521 * mlock_fixup - handle mlock[all]/munlock[all] requests. 522 * 523 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and 524 * munlock is a no-op. However, for some special vmas, we go ahead and 525 * populate the ptes. 526 * 527 * For vmas that pass the filters, merge/split as appropriate. 528 */ 529 static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, 530 unsigned long start, unsigned long end, vm_flags_t newflags) 531 { 532 struct mm_struct *mm = vma->vm_mm; 533 pgoff_t pgoff; 534 int nr_pages; 535 int ret = 0; 536 int lock = !!(newflags & VM_LOCKED); 537 538 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) || 539 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm)) 540 goto out; /* don't set VM_LOCKED, don't count */ 541 542 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); 543 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, 544 vma->vm_file, pgoff, vma_policy(vma)); 545 if (*prev) { 546 vma = *prev; 547 goto success; 548 } 549 550 if (start != vma->vm_start) { 551 ret = split_vma(mm, vma, start, 1); 552 if (ret) 553 goto out; 554 } 555 556 if (end != vma->vm_end) { 557 ret = split_vma(mm, vma, end, 0); 558 if (ret) 559 goto out; 560 } 561 562 success: 563 /* 564 * Keep track of amount of locked VM. 565 */ 566 nr_pages = (end - start) >> PAGE_SHIFT; 567 if (!lock) 568 nr_pages = -nr_pages; 569 mm->locked_vm += nr_pages; 570 571 /* 572 * vm_flags is protected by the mmap_sem held in write mode. 573 * It's okay if try_to_unmap_one unmaps a page just after we 574 * set VM_LOCKED, __mlock_vma_pages_range will bring it back. 575 */ 576 577 if (lock) 578 vma->vm_flags = newflags; 579 else 580 munlock_vma_pages_range(vma, start, end); 581 582 out: 583 *prev = vma; 584 return ret; 585 } 586 587 static int do_mlock(unsigned long start, size_t len, int on) 588 { 589 unsigned long nstart, end, tmp; 590 struct vm_area_struct * vma, * prev; 591 int error; 592 593 VM_BUG_ON(start & ~PAGE_MASK); 594 VM_BUG_ON(len != PAGE_ALIGN(len)); 595 end = start + len; 596 if (end < start) 597 return -EINVAL; 598 if (end == start) 599 return 0; 600 vma = find_vma(current->mm, start); 601 if (!vma || vma->vm_start > start) 602 return -ENOMEM; 603 604 prev = vma->vm_prev; 605 if (start > vma->vm_start) 606 prev = vma; 607 608 for (nstart = start ; ; ) { 609 vm_flags_t newflags; 610 611 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ 612 613 newflags = vma->vm_flags & ~VM_LOCKED; 614 if (on) 615 newflags |= VM_LOCKED; 616 617 tmp = vma->vm_end; 618 if (tmp > end) 619 tmp = end; 620 error = mlock_fixup(vma, &prev, nstart, tmp, newflags); 621 if (error) 622 break; 623 nstart = tmp; 624 if (nstart < prev->vm_end) 625 nstart = prev->vm_end; 626 if (nstart >= end) 627 break; 628 629 vma = prev->vm_next; 630 if (!vma || vma->vm_start != nstart) { 631 error = -ENOMEM; 632 break; 633 } 634 } 635 return error; 636 } 637 638 /* 639 * __mm_populate - populate and/or mlock pages within a range of address space. 640 * 641 * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap 642 * flags. VMAs must be already marked with the desired vm_flags, and 643 * mmap_sem must not be held. 644 */ 645 int __mm_populate(unsigned long start, unsigned long len, int ignore_errors) 646 { 647 struct mm_struct *mm = current->mm; 648 unsigned long end, nstart, nend; 649 struct vm_area_struct *vma = NULL; 650 int locked = 0; 651 long ret = 0; 652 653 VM_BUG_ON(start & ~PAGE_MASK); 654 VM_BUG_ON(len != PAGE_ALIGN(len)); 655 end = start + len; 656 657 for (nstart = start; nstart < end; nstart = nend) { 658 /* 659 * We want to fault in pages for [nstart; end) address range. 660 * Find first corresponding VMA. 661 */ 662 if (!locked) { 663 locked = 1; 664 down_read(&mm->mmap_sem); 665 vma = find_vma(mm, nstart); 666 } else if (nstart >= vma->vm_end) 667 vma = vma->vm_next; 668 if (!vma || vma->vm_start >= end) 669 break; 670 /* 671 * Set [nstart; nend) to intersection of desired address 672 * range with the first VMA. Also, skip undesirable VMA types. 673 */ 674 nend = min(end, vma->vm_end); 675 if (vma->vm_flags & (VM_IO | VM_PFNMAP)) 676 continue; 677 if (nstart < vma->vm_start) 678 nstart = vma->vm_start; 679 /* 680 * Now fault in a range of pages. __mlock_vma_pages_range() 681 * double checks the vma flags, so that it won't mlock pages 682 * if the vma was already munlocked. 683 */ 684 ret = __mlock_vma_pages_range(vma, nstart, nend, &locked); 685 if (ret < 0) { 686 if (ignore_errors) { 687 ret = 0; 688 continue; /* continue at next VMA */ 689 } 690 ret = __mlock_posix_error_return(ret); 691 break; 692 } 693 nend = nstart + ret * PAGE_SIZE; 694 ret = 0; 695 } 696 if (locked) 697 up_read(&mm->mmap_sem); 698 return ret; /* 0 or negative error code */ 699 } 700 701 SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) 702 { 703 unsigned long locked; 704 unsigned long lock_limit; 705 int error = -ENOMEM; 706 707 if (!can_do_mlock()) 708 return -EPERM; 709 710 lru_add_drain_all(); /* flush pagevec */ 711 712 down_write(¤t->mm->mmap_sem); 713 len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); 714 start &= PAGE_MASK; 715 716 locked = len >> PAGE_SHIFT; 717 locked += current->mm->locked_vm; 718 719 lock_limit = rlimit(RLIMIT_MEMLOCK); 720 lock_limit >>= PAGE_SHIFT; 721 722 /* check against resource limits */ 723 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) 724 error = do_mlock(start, len, 1); 725 up_write(¤t->mm->mmap_sem); 726 if (!error) 727 error = __mm_populate(start, len, 0); 728 return error; 729 } 730 731 SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) 732 { 733 int ret; 734 735 down_write(¤t->mm->mmap_sem); 736 len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); 737 start &= PAGE_MASK; 738 ret = do_mlock(start, len, 0); 739 up_write(¤t->mm->mmap_sem); 740 return ret; 741 } 742 743 static int do_mlockall(int flags) 744 { 745 struct vm_area_struct * vma, * prev = NULL; 746 747 if (flags & MCL_FUTURE) 748 current->mm->def_flags |= VM_LOCKED; 749 else 750 current->mm->def_flags &= ~VM_LOCKED; 751 if (flags == MCL_FUTURE) 752 goto out; 753 754 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { 755 vm_flags_t newflags; 756 757 newflags = vma->vm_flags & ~VM_LOCKED; 758 if (flags & MCL_CURRENT) 759 newflags |= VM_LOCKED; 760 761 /* Ignore errors */ 762 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); 763 cond_resched(); 764 } 765 out: 766 return 0; 767 } 768 769 SYSCALL_DEFINE1(mlockall, int, flags) 770 { 771 unsigned long lock_limit; 772 int ret = -EINVAL; 773 774 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) 775 goto out; 776 777 ret = -EPERM; 778 if (!can_do_mlock()) 779 goto out; 780 781 if (flags & MCL_CURRENT) 782 lru_add_drain_all(); /* flush pagevec */ 783 784 down_write(¤t->mm->mmap_sem); 785 786 lock_limit = rlimit(RLIMIT_MEMLOCK); 787 lock_limit >>= PAGE_SHIFT; 788 789 ret = -ENOMEM; 790 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || 791 capable(CAP_IPC_LOCK)) 792 ret = do_mlockall(flags); 793 up_write(¤t->mm->mmap_sem); 794 if (!ret && (flags & MCL_CURRENT)) 795 mm_populate(0, TASK_SIZE); 796 out: 797 return ret; 798 } 799 800 SYSCALL_DEFINE0(munlockall) 801 { 802 int ret; 803 804 down_write(¤t->mm->mmap_sem); 805 ret = do_mlockall(0); 806 up_write(¤t->mm->mmap_sem); 807 return ret; 808 } 809 810 /* 811 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB 812 * shm segments) get accounted against the user_struct instead. 813 */ 814 static DEFINE_SPINLOCK(shmlock_user_lock); 815 816 int user_shm_lock(size_t size, struct user_struct *user) 817 { 818 unsigned long lock_limit, locked; 819 int allowed = 0; 820 821 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 822 lock_limit = rlimit(RLIMIT_MEMLOCK); 823 if (lock_limit == RLIM_INFINITY) 824 allowed = 1; 825 lock_limit >>= PAGE_SHIFT; 826 spin_lock(&shmlock_user_lock); 827 if (!allowed && 828 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) 829 goto out; 830 get_uid(user); 831 user->locked_shm += locked; 832 allowed = 1; 833 out: 834 spin_unlock(&shmlock_user_lock); 835 return allowed; 836 } 837 838 void user_shm_unlock(size_t size, struct user_struct *user) 839 { 840 spin_lock(&shmlock_user_lock); 841 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 842 spin_unlock(&shmlock_user_lock); 843 free_uid(user); 844 } 845