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 (rlimit(RLIMIT_MEMLOCK) != 0) 30 return 1; 31 if (capable(CAP_IPC_LOCK)) 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 /* Serialize with page migration */ 83 BUG_ON(!PageLocked(page)); 84 85 if (!TestSetPageMlocked(page)) { 86 mod_zone_page_state(page_zone(page), NR_MLOCK, 87 hpage_nr_pages(page)); 88 count_vm_event(UNEVICTABLE_PGMLOCKED); 89 if (!isolate_lru_page(page)) 90 putback_lru_page(page); 91 } 92 } 93 94 /* 95 * Isolate a page from LRU with optional get_page() pin. 96 * Assumes lru_lock already held and page already pinned. 97 */ 98 static bool __munlock_isolate_lru_page(struct page *page, bool getpage) 99 { 100 if (PageLRU(page)) { 101 struct lruvec *lruvec; 102 103 lruvec = mem_cgroup_page_lruvec(page, page_zone(page)); 104 if (getpage) 105 get_page(page); 106 ClearPageLRU(page); 107 del_page_from_lru_list(page, lruvec, page_lru(page)); 108 return true; 109 } 110 111 return false; 112 } 113 114 /* 115 * Finish munlock after successful page isolation 116 * 117 * Page must be locked. This is a wrapper for try_to_munlock() 118 * and putback_lru_page() with munlock accounting. 119 */ 120 static void __munlock_isolated_page(struct page *page) 121 { 122 int ret = SWAP_AGAIN; 123 124 /* 125 * Optimization: if the page was mapped just once, that's our mapping 126 * and we don't need to check all the other vmas. 127 */ 128 if (page_mapcount(page) > 1) 129 ret = try_to_munlock(page); 130 131 /* Did try_to_unlock() succeed or punt? */ 132 if (ret != SWAP_MLOCK) 133 count_vm_event(UNEVICTABLE_PGMUNLOCKED); 134 135 putback_lru_page(page); 136 } 137 138 /* 139 * Accounting for page isolation fail during munlock 140 * 141 * Performs accounting when page isolation fails in munlock. There is nothing 142 * else to do because it means some other task has already removed the page 143 * from the LRU. putback_lru_page() will take care of removing the page from 144 * the unevictable list, if necessary. vmscan [page_referenced()] will move 145 * the page back to the unevictable list if some other vma has it mlocked. 146 */ 147 static void __munlock_isolation_failed(struct page *page) 148 { 149 if (PageUnevictable(page)) 150 __count_vm_event(UNEVICTABLE_PGSTRANDED); 151 else 152 __count_vm_event(UNEVICTABLE_PGMUNLOCKED); 153 } 154 155 /** 156 * munlock_vma_page - munlock a vma page 157 * @page - page to be unlocked, either a normal page or THP page head 158 * 159 * returns the size of the page as a page mask (0 for normal page, 160 * HPAGE_PMD_NR - 1 for THP head page) 161 * 162 * called from munlock()/munmap() path with page supposedly on the LRU. 163 * When we munlock a page, because the vma where we found the page is being 164 * munlock()ed or munmap()ed, we want to check whether other vmas hold the 165 * page locked so that we can leave it on the unevictable lru list and not 166 * bother vmscan with it. However, to walk the page's rmap list in 167 * try_to_munlock() we must isolate the page from the LRU. If some other 168 * task has removed the page from the LRU, we won't be able to do that. 169 * So we clear the PageMlocked as we might not get another chance. If we 170 * can't isolate the page, we leave it for putback_lru_page() and vmscan 171 * [page_referenced()/try_to_unmap()] to deal with. 172 */ 173 unsigned int munlock_vma_page(struct page *page) 174 { 175 unsigned int nr_pages; 176 struct zone *zone = page_zone(page); 177 178 /* For try_to_munlock() and to serialize with page migration */ 179 BUG_ON(!PageLocked(page)); 180 181 /* 182 * Serialize with any parallel __split_huge_page_refcount() which 183 * might otherwise copy PageMlocked to part of the tail pages before 184 * we clear it in the head page. It also stabilizes hpage_nr_pages(). 185 */ 186 spin_lock_irq(&zone->lru_lock); 187 188 nr_pages = hpage_nr_pages(page); 189 if (!TestClearPageMlocked(page)) 190 goto unlock_out; 191 192 __mod_zone_page_state(zone, NR_MLOCK, -nr_pages); 193 194 if (__munlock_isolate_lru_page(page, true)) { 195 spin_unlock_irq(&zone->lru_lock); 196 __munlock_isolated_page(page); 197 goto out; 198 } 199 __munlock_isolation_failed(page); 200 201 unlock_out: 202 spin_unlock_irq(&zone->lru_lock); 203 204 out: 205 return nr_pages - 1; 206 } 207 208 /** 209 * __mlock_vma_pages_range() - mlock a range of pages in the vma. 210 * @vma: target vma 211 * @start: start address 212 * @end: end address 213 * @nonblocking: 214 * 215 * This takes care of making the pages present too. 216 * 217 * return 0 on success, negative error code on error. 218 * 219 * vma->vm_mm->mmap_sem must be held. 220 * 221 * If @nonblocking is NULL, it may be held for read or write and will 222 * be unperturbed. 223 * 224 * If @nonblocking is non-NULL, it must held for read only and may be 225 * released. If it's released, *@nonblocking will be set to 0. 226 */ 227 long __mlock_vma_pages_range(struct vm_area_struct *vma, 228 unsigned long start, unsigned long end, int *nonblocking) 229 { 230 struct mm_struct *mm = vma->vm_mm; 231 unsigned long nr_pages = (end - start) / PAGE_SIZE; 232 int gup_flags; 233 234 VM_BUG_ON(start & ~PAGE_MASK); 235 VM_BUG_ON(end & ~PAGE_MASK); 236 VM_BUG_ON_VMA(start < vma->vm_start, vma); 237 VM_BUG_ON_VMA(end > vma->vm_end, vma); 238 VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm); 239 240 gup_flags = FOLL_TOUCH | FOLL_MLOCK; 241 /* 242 * We want to touch writable mappings with a write fault in order 243 * to break COW, except for shared mappings because these don't COW 244 * and we would not want to dirty them for nothing. 245 */ 246 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE) 247 gup_flags |= FOLL_WRITE; 248 249 /* 250 * We want mlock to succeed for regions that have any permissions 251 * other than PROT_NONE. 252 */ 253 if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) 254 gup_flags |= FOLL_FORCE; 255 256 /* 257 * We made sure addr is within a VMA, so the following will 258 * not result in a stack expansion that recurses back here. 259 */ 260 return __get_user_pages(current, mm, start, nr_pages, gup_flags, 261 NULL, NULL, nonblocking); 262 } 263 264 /* 265 * convert get_user_pages() return value to posix mlock() error 266 */ 267 static int __mlock_posix_error_return(long retval) 268 { 269 if (retval == -EFAULT) 270 retval = -ENOMEM; 271 else if (retval == -ENOMEM) 272 retval = -EAGAIN; 273 return retval; 274 } 275 276 /* 277 * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec() 278 * 279 * The fast path is available only for evictable pages with single mapping. 280 * Then we can bypass the per-cpu pvec and get better performance. 281 * when mapcount > 1 we need try_to_munlock() which can fail. 282 * when !page_evictable(), we need the full redo logic of putback_lru_page to 283 * avoid leaving evictable page in unevictable list. 284 * 285 * In case of success, @page is added to @pvec and @pgrescued is incremented 286 * in case that the page was previously unevictable. @page is also unlocked. 287 */ 288 static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec, 289 int *pgrescued) 290 { 291 VM_BUG_ON_PAGE(PageLRU(page), page); 292 VM_BUG_ON_PAGE(!PageLocked(page), page); 293 294 if (page_mapcount(page) <= 1 && page_evictable(page)) { 295 pagevec_add(pvec, page); 296 if (TestClearPageUnevictable(page)) 297 (*pgrescued)++; 298 unlock_page(page); 299 return true; 300 } 301 302 return false; 303 } 304 305 /* 306 * Putback multiple evictable pages to the LRU 307 * 308 * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of 309 * the pages might have meanwhile become unevictable but that is OK. 310 */ 311 static void __putback_lru_fast(struct pagevec *pvec, int pgrescued) 312 { 313 count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec)); 314 /* 315 *__pagevec_lru_add() calls release_pages() so we don't call 316 * put_page() explicitly 317 */ 318 __pagevec_lru_add(pvec); 319 count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); 320 } 321 322 /* 323 * Munlock a batch of pages from the same zone 324 * 325 * The work is split to two main phases. First phase clears the Mlocked flag 326 * and attempts to isolate the pages, all under a single zone lru lock. 327 * The second phase finishes the munlock only for pages where isolation 328 * succeeded. 329 * 330 * Note that the pagevec may be modified during the process. 331 */ 332 static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) 333 { 334 int i; 335 int nr = pagevec_count(pvec); 336 int delta_munlocked; 337 struct pagevec pvec_putback; 338 int pgrescued = 0; 339 340 pagevec_init(&pvec_putback, 0); 341 342 /* Phase 1: page isolation */ 343 spin_lock_irq(&zone->lru_lock); 344 for (i = 0; i < nr; i++) { 345 struct page *page = pvec->pages[i]; 346 347 if (TestClearPageMlocked(page)) { 348 /* 349 * We already have pin from follow_page_mask() 350 * so we can spare the get_page() here. 351 */ 352 if (__munlock_isolate_lru_page(page, false)) 353 continue; 354 else 355 __munlock_isolation_failed(page); 356 } 357 358 /* 359 * We won't be munlocking this page in the next phase 360 * but we still need to release the follow_page_mask() 361 * pin. We cannot do it under lru_lock however. If it's 362 * the last pin, __page_cache_release() would deadlock. 363 */ 364 pagevec_add(&pvec_putback, pvec->pages[i]); 365 pvec->pages[i] = NULL; 366 } 367 delta_munlocked = -nr + pagevec_count(&pvec_putback); 368 __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); 369 spin_unlock_irq(&zone->lru_lock); 370 371 /* Now we can release pins of pages that we are not munlocking */ 372 pagevec_release(&pvec_putback); 373 374 /* Phase 2: page munlock */ 375 for (i = 0; i < nr; i++) { 376 struct page *page = pvec->pages[i]; 377 378 if (page) { 379 lock_page(page); 380 if (!__putback_lru_fast_prepare(page, &pvec_putback, 381 &pgrescued)) { 382 /* 383 * Slow path. We don't want to lose the last 384 * pin before unlock_page() 385 */ 386 get_page(page); /* for putback_lru_page() */ 387 __munlock_isolated_page(page); 388 unlock_page(page); 389 put_page(page); /* from follow_page_mask() */ 390 } 391 } 392 } 393 394 /* 395 * Phase 3: page putback for pages that qualified for the fast path 396 * This will also call put_page() to return pin from follow_page_mask() 397 */ 398 if (pagevec_count(&pvec_putback)) 399 __putback_lru_fast(&pvec_putback, pgrescued); 400 } 401 402 /* 403 * Fill up pagevec for __munlock_pagevec using pte walk 404 * 405 * The function expects that the struct page corresponding to @start address is 406 * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone. 407 * 408 * The rest of @pvec is filled by subsequent pages within the same pmd and same 409 * zone, as long as the pte's are present and vm_normal_page() succeeds. These 410 * pages also get pinned. 411 * 412 * Returns the address of the next page that should be scanned. This equals 413 * @start + PAGE_SIZE when no page could be added by the pte walk. 414 */ 415 static unsigned long __munlock_pagevec_fill(struct pagevec *pvec, 416 struct vm_area_struct *vma, int zoneid, unsigned long start, 417 unsigned long end) 418 { 419 pte_t *pte; 420 spinlock_t *ptl; 421 422 /* 423 * Initialize pte walk starting at the already pinned page where we 424 * are sure that there is a pte, as it was pinned under the same 425 * mmap_sem write op. 426 */ 427 pte = get_locked_pte(vma->vm_mm, start, &ptl); 428 /* Make sure we do not cross the page table boundary */ 429 end = pgd_addr_end(start, end); 430 end = pud_addr_end(start, end); 431 end = pmd_addr_end(start, end); 432 433 /* The page next to the pinned page is the first we will try to get */ 434 start += PAGE_SIZE; 435 while (start < end) { 436 struct page *page = NULL; 437 pte++; 438 if (pte_present(*pte)) 439 page = vm_normal_page(vma, start, *pte); 440 /* 441 * Break if page could not be obtained or the page's node+zone does not 442 * match 443 */ 444 if (!page || page_zone_id(page) != zoneid) 445 break; 446 447 get_page(page); 448 /* 449 * Increase the address that will be returned *before* the 450 * eventual break due to pvec becoming full by adding the page 451 */ 452 start += PAGE_SIZE; 453 if (pagevec_add(pvec, page) == 0) 454 break; 455 } 456 pte_unmap_unlock(pte, ptl); 457 return start; 458 } 459 460 /* 461 * munlock_vma_pages_range() - munlock all pages in the vma range.' 462 * @vma - vma containing range to be munlock()ed. 463 * @start - start address in @vma of the range 464 * @end - end of range in @vma. 465 * 466 * For mremap(), munmap() and exit(). 467 * 468 * Called with @vma VM_LOCKED. 469 * 470 * Returns with VM_LOCKED cleared. Callers must be prepared to 471 * deal with this. 472 * 473 * We don't save and restore VM_LOCKED here because pages are 474 * still on lru. In unmap path, pages might be scanned by reclaim 475 * and re-mlocked by try_to_{munlock|unmap} before we unmap and 476 * free them. This will result in freeing mlocked pages. 477 */ 478 void munlock_vma_pages_range(struct vm_area_struct *vma, 479 unsigned long start, unsigned long end) 480 { 481 vma->vm_flags &= ~VM_LOCKED; 482 483 while (start < end) { 484 struct page *page = NULL; 485 unsigned int page_mask; 486 unsigned long page_increm; 487 struct pagevec pvec; 488 struct zone *zone; 489 int zoneid; 490 491 pagevec_init(&pvec, 0); 492 /* 493 * Although FOLL_DUMP is intended for get_dump_page(), 494 * it just so happens that its special treatment of the 495 * ZERO_PAGE (returning an error instead of doing get_page) 496 * suits munlock very well (and if somehow an abnormal page 497 * has sneaked into the range, we won't oops here: great). 498 */ 499 page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP, 500 &page_mask); 501 502 if (page && !IS_ERR(page)) { 503 if (PageTransHuge(page)) { 504 lock_page(page); 505 /* 506 * Any THP page found by follow_page_mask() may 507 * have gotten split before reaching 508 * munlock_vma_page(), so we need to recompute 509 * the page_mask here. 510 */ 511 page_mask = munlock_vma_page(page); 512 unlock_page(page); 513 put_page(page); /* follow_page_mask() */ 514 } else { 515 /* 516 * Non-huge pages are handled in batches via 517 * pagevec. The pin from follow_page_mask() 518 * prevents them from collapsing by THP. 519 */ 520 pagevec_add(&pvec, page); 521 zone = page_zone(page); 522 zoneid = page_zone_id(page); 523 524 /* 525 * Try to fill the rest of pagevec using fast 526 * pte walk. This will also update start to 527 * the next page to process. Then munlock the 528 * pagevec. 529 */ 530 start = __munlock_pagevec_fill(&pvec, vma, 531 zoneid, start, end); 532 __munlock_pagevec(&pvec, zone); 533 goto next; 534 } 535 } 536 /* It's a bug to munlock in the middle of a THP page */ 537 VM_BUG_ON((start >> PAGE_SHIFT) & page_mask); 538 page_increm = 1 + page_mask; 539 start += page_increm * PAGE_SIZE; 540 next: 541 cond_resched(); 542 } 543 } 544 545 /* 546 * mlock_fixup - handle mlock[all]/munlock[all] requests. 547 * 548 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and 549 * munlock is a no-op. However, for some special vmas, we go ahead and 550 * populate the ptes. 551 * 552 * For vmas that pass the filters, merge/split as appropriate. 553 */ 554 static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, 555 unsigned long start, unsigned long end, vm_flags_t newflags) 556 { 557 struct mm_struct *mm = vma->vm_mm; 558 pgoff_t pgoff; 559 int nr_pages; 560 int ret = 0; 561 int lock = !!(newflags & VM_LOCKED); 562 563 if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) || 564 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm)) 565 goto out; /* don't set VM_LOCKED, don't count */ 566 567 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); 568 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, 569 vma->vm_file, pgoff, vma_policy(vma)); 570 if (*prev) { 571 vma = *prev; 572 goto success; 573 } 574 575 if (start != vma->vm_start) { 576 ret = split_vma(mm, vma, start, 1); 577 if (ret) 578 goto out; 579 } 580 581 if (end != vma->vm_end) { 582 ret = split_vma(mm, vma, end, 0); 583 if (ret) 584 goto out; 585 } 586 587 success: 588 /* 589 * Keep track of amount of locked VM. 590 */ 591 nr_pages = (end - start) >> PAGE_SHIFT; 592 if (!lock) 593 nr_pages = -nr_pages; 594 mm->locked_vm += nr_pages; 595 596 /* 597 * vm_flags is protected by the mmap_sem held in write mode. 598 * It's okay if try_to_unmap_one unmaps a page just after we 599 * set VM_LOCKED, __mlock_vma_pages_range will bring it back. 600 */ 601 602 if (lock) 603 vma->vm_flags = newflags; 604 else 605 munlock_vma_pages_range(vma, start, end); 606 607 out: 608 *prev = vma; 609 return ret; 610 } 611 612 static int do_mlock(unsigned long start, size_t len, int on) 613 { 614 unsigned long nstart, end, tmp; 615 struct vm_area_struct * vma, * prev; 616 int error; 617 618 VM_BUG_ON(start & ~PAGE_MASK); 619 VM_BUG_ON(len != PAGE_ALIGN(len)); 620 end = start + len; 621 if (end < start) 622 return -EINVAL; 623 if (end == start) 624 return 0; 625 vma = find_vma(current->mm, start); 626 if (!vma || vma->vm_start > start) 627 return -ENOMEM; 628 629 prev = vma->vm_prev; 630 if (start > vma->vm_start) 631 prev = vma; 632 633 for (nstart = start ; ; ) { 634 vm_flags_t newflags; 635 636 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ 637 638 newflags = vma->vm_flags & ~VM_LOCKED; 639 if (on) 640 newflags |= VM_LOCKED; 641 642 tmp = vma->vm_end; 643 if (tmp > end) 644 tmp = end; 645 error = mlock_fixup(vma, &prev, nstart, tmp, newflags); 646 if (error) 647 break; 648 nstart = tmp; 649 if (nstart < prev->vm_end) 650 nstart = prev->vm_end; 651 if (nstart >= end) 652 break; 653 654 vma = prev->vm_next; 655 if (!vma || vma->vm_start != nstart) { 656 error = -ENOMEM; 657 break; 658 } 659 } 660 return error; 661 } 662 663 /* 664 * __mm_populate - populate and/or mlock pages within a range of address space. 665 * 666 * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap 667 * flags. VMAs must be already marked with the desired vm_flags, and 668 * mmap_sem must not be held. 669 */ 670 int __mm_populate(unsigned long start, unsigned long len, int ignore_errors) 671 { 672 struct mm_struct *mm = current->mm; 673 unsigned long end, nstart, nend; 674 struct vm_area_struct *vma = NULL; 675 int locked = 0; 676 long ret = 0; 677 678 VM_BUG_ON(start & ~PAGE_MASK); 679 VM_BUG_ON(len != PAGE_ALIGN(len)); 680 end = start + len; 681 682 for (nstart = start; nstart < end; nstart = nend) { 683 /* 684 * We want to fault in pages for [nstart; end) address range. 685 * Find first corresponding VMA. 686 */ 687 if (!locked) { 688 locked = 1; 689 down_read(&mm->mmap_sem); 690 vma = find_vma(mm, nstart); 691 } else if (nstart >= vma->vm_end) 692 vma = vma->vm_next; 693 if (!vma || vma->vm_start >= end) 694 break; 695 /* 696 * Set [nstart; nend) to intersection of desired address 697 * range with the first VMA. Also, skip undesirable VMA types. 698 */ 699 nend = min(end, vma->vm_end); 700 if (vma->vm_flags & (VM_IO | VM_PFNMAP)) 701 continue; 702 if (nstart < vma->vm_start) 703 nstart = vma->vm_start; 704 /* 705 * Now fault in a range of pages. __mlock_vma_pages_range() 706 * double checks the vma flags, so that it won't mlock pages 707 * if the vma was already munlocked. 708 */ 709 ret = __mlock_vma_pages_range(vma, nstart, nend, &locked); 710 if (ret < 0) { 711 if (ignore_errors) { 712 ret = 0; 713 continue; /* continue at next VMA */ 714 } 715 ret = __mlock_posix_error_return(ret); 716 break; 717 } 718 nend = nstart + ret * PAGE_SIZE; 719 ret = 0; 720 } 721 if (locked) 722 up_read(&mm->mmap_sem); 723 return ret; /* 0 or negative error code */ 724 } 725 726 SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) 727 { 728 unsigned long locked; 729 unsigned long lock_limit; 730 int error = -ENOMEM; 731 732 if (!can_do_mlock()) 733 return -EPERM; 734 735 lru_add_drain_all(); /* flush pagevec */ 736 737 len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); 738 start &= PAGE_MASK; 739 740 lock_limit = rlimit(RLIMIT_MEMLOCK); 741 lock_limit >>= PAGE_SHIFT; 742 locked = len >> PAGE_SHIFT; 743 744 down_write(¤t->mm->mmap_sem); 745 746 locked += current->mm->locked_vm; 747 748 /* check against resource limits */ 749 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) 750 error = do_mlock(start, len, 1); 751 752 up_write(¤t->mm->mmap_sem); 753 if (!error) 754 error = __mm_populate(start, len, 0); 755 return error; 756 } 757 758 SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) 759 { 760 int ret; 761 762 len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); 763 start &= PAGE_MASK; 764 765 down_write(¤t->mm->mmap_sem); 766 ret = do_mlock(start, len, 0); 767 up_write(¤t->mm->mmap_sem); 768 769 return ret; 770 } 771 772 static int do_mlockall(int flags) 773 { 774 struct vm_area_struct * vma, * prev = NULL; 775 776 if (flags & MCL_FUTURE) 777 current->mm->def_flags |= VM_LOCKED; 778 else 779 current->mm->def_flags &= ~VM_LOCKED; 780 if (flags == MCL_FUTURE) 781 goto out; 782 783 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { 784 vm_flags_t newflags; 785 786 newflags = vma->vm_flags & ~VM_LOCKED; 787 if (flags & MCL_CURRENT) 788 newflags |= VM_LOCKED; 789 790 /* Ignore errors */ 791 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); 792 cond_resched_rcu_qs(); 793 } 794 out: 795 return 0; 796 } 797 798 SYSCALL_DEFINE1(mlockall, int, flags) 799 { 800 unsigned long lock_limit; 801 int ret = -EINVAL; 802 803 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) 804 goto out; 805 806 ret = -EPERM; 807 if (!can_do_mlock()) 808 goto out; 809 810 if (flags & MCL_CURRENT) 811 lru_add_drain_all(); /* flush pagevec */ 812 813 lock_limit = rlimit(RLIMIT_MEMLOCK); 814 lock_limit >>= PAGE_SHIFT; 815 816 ret = -ENOMEM; 817 down_write(¤t->mm->mmap_sem); 818 819 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || 820 capable(CAP_IPC_LOCK)) 821 ret = do_mlockall(flags); 822 up_write(¤t->mm->mmap_sem); 823 if (!ret && (flags & MCL_CURRENT)) 824 mm_populate(0, TASK_SIZE); 825 out: 826 return ret; 827 } 828 829 SYSCALL_DEFINE0(munlockall) 830 { 831 int ret; 832 833 down_write(¤t->mm->mmap_sem); 834 ret = do_mlockall(0); 835 up_write(¤t->mm->mmap_sem); 836 return ret; 837 } 838 839 /* 840 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB 841 * shm segments) get accounted against the user_struct instead. 842 */ 843 static DEFINE_SPINLOCK(shmlock_user_lock); 844 845 int user_shm_lock(size_t size, struct user_struct *user) 846 { 847 unsigned long lock_limit, locked; 848 int allowed = 0; 849 850 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 851 lock_limit = rlimit(RLIMIT_MEMLOCK); 852 if (lock_limit == RLIM_INFINITY) 853 allowed = 1; 854 lock_limit >>= PAGE_SHIFT; 855 spin_lock(&shmlock_user_lock); 856 if (!allowed && 857 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) 858 goto out; 859 get_uid(user); 860 user->locked_shm += locked; 861 allowed = 1; 862 out: 863 spin_unlock(&shmlock_user_lock); 864 return allowed; 865 } 866 867 void user_shm_unlock(size_t size, struct user_struct *user) 868 { 869 spin_lock(&shmlock_user_lock); 870 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 871 spin_unlock(&shmlock_user_lock); 872 free_uid(user); 873 } 874