1// SPDX-License-Identifier: GPL-2.0 2/* 3 * linux/mm/mlock.c 4 * 5 * (C) Copyright 1995 Linus Torvalds 6 * (C) Copyright 2002 Christoph Hellwig 7 */ 8 9#include <linux/capability.h> 10#include <linux/mman.h> 11#include <linux/mm.h> 12#include <linux/sched/user.h> 13#include <linux/swap.h> 14#include <linux/swapops.h> 15#include <linux/pagemap.h> 16#include <linux/pagevec.h> 17#include <linux/pagewalk.h> 18#include <linux/mempolicy.h> 19#include <linux/syscalls.h> 20#include <linux/sched.h> 21#include <linux/export.h> 22#include <linux/rmap.h> 23#include <linux/mmzone.h> 24#include <linux/hugetlb.h> 25#include <linux/memcontrol.h> 26#include <linux/mm_inline.h> 27#include <linux/secretmem.h> 28 29#include "internal.h" 30 31struct mlock_fbatch { 32 local_lock_t lock; 33 struct folio_batch fbatch; 34}; 35 36static DEFINE_PER_CPU(struct mlock_fbatch, mlock_fbatch) = { 37 .lock = INIT_LOCAL_LOCK(lock), 38}; 39 40bool can_do_mlock(void) 41{ 42 if (rlimit(RLIMIT_MEMLOCK) != 0) 43 return true; 44 if (capable(CAP_IPC_LOCK)) 45 return true; 46 return false; 47} 48EXPORT_SYMBOL(can_do_mlock); 49 50/* 51 * Mlocked folios are marked with the PG_mlocked flag for efficient testing 52 * in vmscan and, possibly, the fault path; and to support semi-accurate 53 * statistics. 54 * 55 * An mlocked folio [folio_test_mlocked(folio)] is unevictable. As such, it 56 * will be ostensibly placed on the LRU "unevictable" list (actually no such 57 * list exists), rather than the [in]active lists. PG_unevictable is set to 58 * indicate the unevictable state. 59 */ 60 61static struct lruvec *__mlock_folio(struct folio *folio, struct lruvec *lruvec) 62{ 63 /* There is nothing more we can do while it's off LRU */ 64 if (!folio_test_clear_lru(folio)) 65 return lruvec; 66 67 lruvec = folio_lruvec_relock_irq(folio, lruvec); 68 69 if (unlikely(folio_evictable(folio))) { 70 /* 71 * This is a little surprising, but quite possible: PG_mlocked 72 * must have got cleared already by another CPU. Could this 73 * folio be unevictable? I'm not sure, but move it now if so. 74 */ 75 if (folio_test_unevictable(folio)) { 76 lruvec_del_folio(lruvec, folio); 77 folio_clear_unevictable(folio); 78 lruvec_add_folio(lruvec, folio); 79 80 __count_vm_events(UNEVICTABLE_PGRESCUED, 81 folio_nr_pages(folio)); 82 } 83 goto out; 84 } 85 86 if (folio_test_unevictable(folio)) { 87 if (folio_test_mlocked(folio)) 88 folio->mlock_count++; 89 goto out; 90 } 91 92 lruvec_del_folio(lruvec, folio); 93 folio_clear_active(folio); 94 folio_set_unevictable(folio); 95 folio->mlock_count = !!folio_test_mlocked(folio); 96 lruvec_add_folio(lruvec, folio); 97 __count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio)); 98out: 99 folio_set_lru(folio); 100 return lruvec; 101} 102 103static struct lruvec *__mlock_new_folio(struct folio *folio, struct lruvec *lruvec) 104{ 105 VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); 106 107 lruvec = folio_lruvec_relock_irq(folio, lruvec); 108 109 /* As above, this is a little surprising, but possible */ 110 if (unlikely(folio_evictable(folio))) 111 goto out; 112 113 folio_set_unevictable(folio); 114 folio->mlock_count = !!folio_test_mlocked(folio); 115 __count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio)); 116out: 117 lruvec_add_folio(lruvec, folio); 118 folio_set_lru(folio); 119 return lruvec; 120} 121 122static struct lruvec *__munlock_folio(struct folio *folio, struct lruvec *lruvec) 123{ 124 int nr_pages = folio_nr_pages(folio); 125 bool isolated = false; 126 127 if (!folio_test_clear_lru(folio)) 128 goto munlock; 129 130 isolated = true; 131 lruvec = folio_lruvec_relock_irq(folio, lruvec); 132 133 if (folio_test_unevictable(folio)) { 134 /* Then mlock_count is maintained, but might undercount */ 135 if (folio->mlock_count) 136 folio->mlock_count--; 137 if (folio->mlock_count) 138 goto out; 139 } 140 /* else assume that was the last mlock: reclaim will fix it if not */ 141 142munlock: 143 if (folio_test_clear_mlocked(folio)) { 144 __zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages); 145 if (isolated || !folio_test_unevictable(folio)) 146 __count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages); 147 else 148 __count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages); 149 } 150 151 /* folio_evictable() has to be checked *after* clearing Mlocked */ 152 if (isolated && folio_test_unevictable(folio) && folio_evictable(folio)) { 153 lruvec_del_folio(lruvec, folio); 154 folio_clear_unevictable(folio); 155 lruvec_add_folio(lruvec, folio); 156 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages); 157 } 158out: 159 if (isolated) 160 folio_set_lru(folio); 161 return lruvec; 162} 163 164/* 165 * Flags held in the low bits of a struct folio pointer on the mlock_fbatch. 166 */ 167#define LRU_FOLIO 0x1 168#define NEW_FOLIO 0x2 169static inline struct folio *mlock_lru(struct folio *folio) 170{ 171 return (struct folio *)((unsigned long)folio + LRU_FOLIO); 172} 173 174static inline struct folio *mlock_new(struct folio *folio) 175{ 176 return (struct folio *)((unsigned long)folio + NEW_FOLIO); 177} 178 179/* 180 * mlock_folio_batch() is derived from folio_batch_move_lru(): perhaps that can 181 * make use of such folio pointer flags in future, but for now just keep it for 182 * mlock. We could use three separate folio batches instead, but one feels 183 * better (munlocking a full folio batch does not need to drain mlocking folio 184 * batches first). 185 */ 186static void mlock_folio_batch(struct folio_batch *fbatch) 187{ 188 struct lruvec *lruvec = NULL; 189 unsigned long mlock; 190 struct folio *folio; 191 int i; 192 193 for (i = 0; i < folio_batch_count(fbatch); i++) { 194 folio = fbatch->folios[i]; 195 mlock = (unsigned long)folio & (LRU_FOLIO | NEW_FOLIO); 196 folio = (struct folio *)((unsigned long)folio - mlock); 197 fbatch->folios[i] = folio; 198 199 if (mlock & LRU_FOLIO) 200 lruvec = __mlock_folio(folio, lruvec); 201 else if (mlock & NEW_FOLIO) 202 lruvec = __mlock_new_folio(folio, lruvec); 203 else 204 lruvec = __munlock_folio(folio, lruvec); 205 } 206 207 if (lruvec) 208 unlock_page_lruvec_irq(lruvec); 209 folios_put(fbatch); 210} 211 212void mlock_drain_local(void) 213{ 214 struct folio_batch *fbatch; 215 216 local_lock(&mlock_fbatch.lock); 217 fbatch = this_cpu_ptr(&mlock_fbatch.fbatch); 218 if (folio_batch_count(fbatch)) 219 mlock_folio_batch(fbatch); 220 local_unlock(&mlock_fbatch.lock); 221} 222 223void mlock_drain_remote(int cpu) 224{ 225 struct folio_batch *fbatch; 226 227 WARN_ON_ONCE(cpu_online(cpu)); 228 fbatch = &per_cpu(mlock_fbatch.fbatch, cpu); 229 if (folio_batch_count(fbatch)) 230 mlock_folio_batch(fbatch); 231} 232 233bool need_mlock_drain(int cpu) 234{ 235 return folio_batch_count(&per_cpu(mlock_fbatch.fbatch, cpu)); 236} 237 238/** 239 * mlock_folio - mlock a folio already on (or temporarily off) LRU 240 * @folio: folio to be mlocked. 241 */ 242void mlock_folio(struct folio *folio) 243{ 244 struct folio_batch *fbatch; 245 246 local_lock(&mlock_fbatch.lock); 247 fbatch = this_cpu_ptr(&mlock_fbatch.fbatch); 248 249 if (!folio_test_set_mlocked(folio)) { 250 int nr_pages = folio_nr_pages(folio); 251 252 zone_stat_mod_folio(folio, NR_MLOCK, nr_pages); 253 __count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); 254 } 255 256 folio_get(folio); 257 if (!folio_batch_add(fbatch, mlock_lru(folio)) || 258 folio_test_large(folio) || lru_cache_disabled()) 259 mlock_folio_batch(fbatch); 260 local_unlock(&mlock_fbatch.lock); 261} 262 263/** 264 * mlock_new_folio - mlock a newly allocated folio not yet on LRU 265 * @folio: folio to be mlocked, either normal or a THP head. 266 */ 267void mlock_new_folio(struct folio *folio) 268{ 269 struct folio_batch *fbatch; 270 int nr_pages = folio_nr_pages(folio); 271 272 local_lock(&mlock_fbatch.lock); 273 fbatch = this_cpu_ptr(&mlock_fbatch.fbatch); 274 folio_set_mlocked(folio); 275 276 zone_stat_mod_folio(folio, NR_MLOCK, nr_pages); 277 __count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); 278 279 folio_get(folio); 280 if (!folio_batch_add(fbatch, mlock_new(folio)) || 281 folio_test_large(folio) || lru_cache_disabled()) 282 mlock_folio_batch(fbatch); 283 local_unlock(&mlock_fbatch.lock); 284} 285 286/** 287 * munlock_folio - munlock a folio 288 * @folio: folio to be munlocked, either normal or a THP head. 289 */ 290void munlock_folio(struct folio *folio) 291{ 292 struct folio_batch *fbatch; 293 294 local_lock(&mlock_fbatch.lock); 295 fbatch = this_cpu_ptr(&mlock_fbatch.fbatch); 296 /* 297 * folio_test_clear_mlocked(folio) must be left to __munlock_folio(), 298 * which will check whether the folio is multiply mlocked. 299 */ 300 folio_get(folio); 301 if (!folio_batch_add(fbatch, folio) || 302 folio_test_large(folio) || lru_cache_disabled()) 303 mlock_folio_batch(fbatch); 304 local_unlock(&mlock_fbatch.lock); 305} 306 307static inline unsigned int folio_mlock_step(struct folio *folio, 308 pte_t *pte, unsigned long addr, unsigned long end) 309{ 310 unsigned int count, i, nr = folio_nr_pages(folio); 311 unsigned long pfn = folio_pfn(folio); 312 pte_t ptent = ptep_get(pte); 313 314 if (!folio_test_large(folio)) 315 return 1; 316 317 count = pfn + nr - pte_pfn(ptent); 318 count = min_t(unsigned int, count, (end - addr) >> PAGE_SHIFT); 319 320 for (i = 0; i < count; i++, pte++) { 321 pte_t entry = ptep_get(pte); 322 323 if (!pte_present(entry)) 324 break; 325 if (pte_pfn(entry) - pfn >= nr) 326 break; 327 } 328 329 return i; 330} 331 332static inline bool allow_mlock_munlock(struct folio *folio, 333 struct vm_area_struct *vma, unsigned long start, 334 unsigned long end, unsigned int step) 335{ 336 /* 337 * For unlock, allow munlock large folio which is partially 338 * mapped to VMA. As it's possible that large folio is 339 * mlocked and VMA is split later. 340 * 341 * During memory pressure, such kind of large folio can 342 * be split. And the pages are not in VM_LOCKed VMA 343 * can be reclaimed. 344 */ 345 if (!(vma->vm_flags & VM_LOCKED)) 346 return true; 347 348 /* folio_within_range() cannot take KSM, but any small folio is OK */ 349 if (!folio_test_large(folio)) 350 return true; 351 352 /* folio not in range [start, end), skip mlock */ 353 if (!folio_within_range(folio, vma, start, end)) 354 return false; 355 356 /* folio is not fully mapped, skip mlock */ 357 if (step != folio_nr_pages(folio)) 358 return false; 359 360 return true; 361} 362 363static int mlock_pte_range(pmd_t *pmd, unsigned long addr, 364 unsigned long end, struct mm_walk *walk) 365 366{ 367 struct vm_area_struct *vma = walk->vma; 368 spinlock_t *ptl; 369 pte_t *start_pte, *pte; 370 pte_t ptent; 371 struct folio *folio; 372 unsigned int step = 1; 373 unsigned long start = addr; 374 375 ptl = pmd_trans_huge_lock(pmd, vma); 376 if (ptl) { 377 if (!pmd_present(*pmd)) 378 goto out; 379 if (is_huge_zero_pmd(*pmd)) 380 goto out; 381 folio = page_folio(pmd_page(*pmd)); 382 if (vma->vm_flags & VM_LOCKED) 383 mlock_folio(folio); 384 else 385 munlock_folio(folio); 386 goto out; 387 } 388 389 start_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 390 if (!start_pte) { 391 walk->action = ACTION_AGAIN; 392 return 0; 393 } 394 395 for (pte = start_pte; addr != end; pte++, addr += PAGE_SIZE) { 396 ptent = ptep_get(pte); 397 if (!pte_present(ptent)) 398 continue; 399 folio = vm_normal_folio(vma, addr, ptent); 400 if (!folio || folio_is_zone_device(folio)) 401 continue; 402 403 step = folio_mlock_step(folio, pte, addr, end); 404 if (!allow_mlock_munlock(folio, vma, start, end, step)) 405 goto next_entry; 406 407 if (vma->vm_flags & VM_LOCKED) 408 mlock_folio(folio); 409 else 410 munlock_folio(folio); 411 412next_entry: 413 pte += step - 1; 414 addr += (step - 1) << PAGE_SHIFT; 415 } 416 pte_unmap(start_pte); 417out: 418 spin_unlock(ptl); 419 cond_resched(); 420 return 0; 421} 422 423/* 424 * mlock_vma_pages_range() - mlock any pages already in the range, 425 * or munlock all pages in the range. 426 * @vma - vma containing range to be mlock()ed or munlock()ed 427 * @start - start address in @vma of the range 428 * @end - end of range in @vma 429 * @newflags - the new set of flags for @vma. 430 * 431 * Called for mlock(), mlock2() and mlockall(), to set @vma VM_LOCKED; 432 * called for munlock() and munlockall(), to clear VM_LOCKED from @vma. 433 */ 434static void mlock_vma_pages_range(struct vm_area_struct *vma, 435 unsigned long start, unsigned long end, vm_flags_t newflags) 436{ 437 static const struct mm_walk_ops mlock_walk_ops = { 438 .pmd_entry = mlock_pte_range, 439 .walk_lock = PGWALK_WRLOCK_VERIFY, 440 }; 441 442 /* 443 * There is a slight chance that concurrent page migration, 444 * or page reclaim finding a page of this now-VM_LOCKED vma, 445 * will call mlock_vma_folio() and raise page's mlock_count: 446 * double counting, leaving the page unevictable indefinitely. 447 * Communicate this danger to mlock_vma_folio() with VM_IO, 448 * which is a VM_SPECIAL flag not allowed on VM_LOCKED vmas. 449 * mmap_lock is held in write mode here, so this weird 450 * combination should not be visible to other mmap_lock users; 451 * but WRITE_ONCE so rmap walkers must see VM_IO if VM_LOCKED. 452 */ 453 if (newflags & VM_LOCKED) 454 newflags |= VM_IO; 455 vma_start_write(vma); 456 vm_flags_reset_once(vma, newflags); 457 458 lru_add_drain(); 459 walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL); 460 lru_add_drain(); 461 462 if (newflags & VM_IO) { 463 newflags &= ~VM_IO; 464 vm_flags_reset_once(vma, newflags); 465 } 466} 467 468/* 469 * mlock_fixup - handle mlock[all]/munlock[all] requests. 470 * 471 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and 472 * munlock is a no-op. However, for some special vmas, we go ahead and 473 * populate the ptes. 474 * 475 * For vmas that pass the filters, merge/split as appropriate. 476 */ 477static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma, 478 struct vm_area_struct **prev, unsigned long start, 479 unsigned long end, vm_flags_t newflags) 480{ 481 struct mm_struct *mm = vma->vm_mm; 482 int nr_pages; 483 int ret = 0; 484 vm_flags_t oldflags = vma->vm_flags; 485 486 if (newflags == oldflags || (oldflags & VM_SPECIAL) || 487 is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) || 488 vma_is_dax(vma) || vma_is_secretmem(vma)) 489 /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */ 490 goto out; 491 492 vma = vma_modify_flags(vmi, *prev, vma, start, end, newflags); 493 if (IS_ERR(vma)) { 494 ret = PTR_ERR(vma); 495 goto out; 496 } 497 498 /* 499 * Keep track of amount of locked VM. 500 */ 501 nr_pages = (end - start) >> PAGE_SHIFT; 502 if (!(newflags & VM_LOCKED)) 503 nr_pages = -nr_pages; 504 else if (oldflags & VM_LOCKED) 505 nr_pages = 0; 506 mm->locked_vm += nr_pages; 507 508 /* 509 * vm_flags is protected by the mmap_lock held in write mode. 510 * It's okay if try_to_unmap_one unmaps a page just after we 511 * set VM_LOCKED, populate_vma_page_range will bring it back. 512 */ 513 if ((newflags & VM_LOCKED) && (oldflags & VM_LOCKED)) { 514 /* No work to do, and mlocking twice would be wrong */ 515 vma_start_write(vma); 516 vm_flags_reset(vma, newflags); 517 } else { 518 mlock_vma_pages_range(vma, start, end, newflags); 519 } 520out: 521 *prev = vma; 522 return ret; 523} 524 525static int apply_vma_lock_flags(unsigned long start, size_t len, 526 vm_flags_t flags) 527{ 528 unsigned long nstart, end, tmp; 529 struct vm_area_struct *vma, *prev; 530 VMA_ITERATOR(vmi, current->mm, start); 531 532 VM_BUG_ON(offset_in_page(start)); 533 VM_BUG_ON(len != PAGE_ALIGN(len)); 534 end = start + len; 535 if (end < start) 536 return -EINVAL; 537 if (end == start) 538 return 0; 539 vma = vma_iter_load(&vmi); 540 if (!vma) 541 return -ENOMEM; 542 543 prev = vma_prev(&vmi); 544 if (start > vma->vm_start) 545 prev = vma; 546 547 nstart = start; 548 tmp = vma->vm_start; 549 for_each_vma_range(vmi, vma, end) { 550 int error; 551 vm_flags_t newflags; 552 553 if (vma->vm_start != tmp) 554 return -ENOMEM; 555 556 newflags = vma->vm_flags & ~VM_LOCKED_MASK; 557 newflags |= flags; 558 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ 559 tmp = vma->vm_end; 560 if (tmp > end) 561 tmp = end; 562 error = mlock_fixup(&vmi, vma, &prev, nstart, tmp, newflags); 563 if (error) 564 return error; 565 tmp = vma_iter_end(&vmi); 566 nstart = tmp; 567 } 568 569 if (tmp < end) 570 return -ENOMEM; 571 572 return 0; 573} 574 575/* 576 * Go through vma areas and sum size of mlocked 577 * vma pages, as return value. 578 * Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT) 579 * is also counted. 580 * Return value: previously mlocked page counts 581 */ 582static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm, 583 unsigned long start, size_t len) 584{ 585 struct vm_area_struct *vma; 586 unsigned long count = 0; 587 unsigned long end; 588 VMA_ITERATOR(vmi, mm, start); 589 590 /* Don't overflow past ULONG_MAX */ 591 if (unlikely(ULONG_MAX - len < start)) 592 end = ULONG_MAX; 593 else 594 end = start + len; 595 596 for_each_vma_range(vmi, vma, end) { 597 if (vma->vm_flags & VM_LOCKED) { 598 if (start > vma->vm_start) 599 count -= (start - vma->vm_start); 600 if (end < vma->vm_end) { 601 count += end - vma->vm_start; 602 break; 603 } 604 count += vma->vm_end - vma->vm_start; 605 } 606 } 607 608 return count >> PAGE_SHIFT; 609} 610 611/* 612 * convert get_user_pages() return value to posix mlock() error 613 */ 614static int __mlock_posix_error_return(long retval) 615{ 616 if (retval == -EFAULT) 617 retval = -ENOMEM; 618 else if (retval == -ENOMEM) 619 retval = -EAGAIN; 620 return retval; 621} 622 623static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t flags) 624{ 625 unsigned long locked; 626 unsigned long lock_limit; 627 int error = -ENOMEM; 628 629 start = untagged_addr(start); 630 631 if (!can_do_mlock()) 632 return -EPERM; 633 634 len = PAGE_ALIGN(len + (offset_in_page(start))); 635 start &= PAGE_MASK; 636 637 lock_limit = rlimit(RLIMIT_MEMLOCK); 638 lock_limit >>= PAGE_SHIFT; 639 locked = len >> PAGE_SHIFT; 640 641 if (mmap_write_lock_killable(current->mm)) 642 return -EINTR; 643 644 locked += current->mm->locked_vm; 645 if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) { 646 /* 647 * It is possible that the regions requested intersect with 648 * previously mlocked areas, that part area in "mm->locked_vm" 649 * should not be counted to new mlock increment count. So check 650 * and adjust locked count if necessary. 651 */ 652 locked -= count_mm_mlocked_page_nr(current->mm, 653 start, len); 654 } 655 656 /* check against resource limits */ 657 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) 658 error = apply_vma_lock_flags(start, len, flags); 659 660 mmap_write_unlock(current->mm); 661 if (error) 662 return error; 663 664 error = __mm_populate(start, len, 0); 665 if (error) 666 return __mlock_posix_error_return(error); 667 return 0; 668} 669 670SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) 671{ 672 return do_mlock(start, len, VM_LOCKED); 673} 674 675SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) 676{ 677 vm_flags_t vm_flags = VM_LOCKED; 678 679 if (flags & ~MLOCK_ONFAULT) 680 return -EINVAL; 681 682 if (flags & MLOCK_ONFAULT) 683 vm_flags |= VM_LOCKONFAULT; 684 685 return do_mlock(start, len, vm_flags); 686} 687 688SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) 689{ 690 int ret; 691 692 start = untagged_addr(start); 693 694 len = PAGE_ALIGN(len + (offset_in_page(start))); 695 start &= PAGE_MASK; 696 697 if (mmap_write_lock_killable(current->mm)) 698 return -EINTR; 699 ret = apply_vma_lock_flags(start, len, 0); 700 mmap_write_unlock(current->mm); 701 702 return ret; 703} 704 705/* 706 * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall) 707 * and translate into the appropriate modifications to mm->def_flags and/or the 708 * flags for all current VMAs. 709 * 710 * There are a couple of subtleties with this. If mlockall() is called multiple 711 * times with different flags, the values do not necessarily stack. If mlockall 712 * is called once including the MCL_FUTURE flag and then a second time without 713 * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags. 714 */ 715static int apply_mlockall_flags(int flags) 716{ 717 VMA_ITERATOR(vmi, current->mm, 0); 718 struct vm_area_struct *vma, *prev = NULL; 719 vm_flags_t to_add = 0; 720 721 current->mm->def_flags &= ~VM_LOCKED_MASK; 722 if (flags & MCL_FUTURE) { 723 current->mm->def_flags |= VM_LOCKED; 724 725 if (flags & MCL_ONFAULT) 726 current->mm->def_flags |= VM_LOCKONFAULT; 727 728 if (!(flags & MCL_CURRENT)) 729 goto out; 730 } 731 732 if (flags & MCL_CURRENT) { 733 to_add |= VM_LOCKED; 734 if (flags & MCL_ONFAULT) 735 to_add |= VM_LOCKONFAULT; 736 } 737 738 for_each_vma(vmi, vma) { 739 vm_flags_t newflags; 740 741 newflags = vma->vm_flags & ~VM_LOCKED_MASK; 742 newflags |= to_add; 743 744 /* Ignore errors */ 745 mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end, 746 newflags); 747 cond_resched(); 748 } 749out: 750 return 0; 751} 752 753SYSCALL_DEFINE1(mlockall, int, flags) 754{ 755 unsigned long lock_limit; 756 int ret; 757 758 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) || 759 flags == MCL_ONFAULT) 760 return -EINVAL; 761 762 if (!can_do_mlock()) 763 return -EPERM; 764 765 lock_limit = rlimit(RLIMIT_MEMLOCK); 766 lock_limit >>= PAGE_SHIFT; 767 768 if (mmap_write_lock_killable(current->mm)) 769 return -EINTR; 770 771 ret = -ENOMEM; 772 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || 773 capable(CAP_IPC_LOCK)) 774 ret = apply_mlockall_flags(flags); 775 mmap_write_unlock(current->mm); 776 if (!ret && (flags & MCL_CURRENT)) 777 mm_populate(0, TASK_SIZE); 778 779 return ret; 780} 781 782SYSCALL_DEFINE0(munlockall) 783{ 784 int ret; 785 786 if (mmap_write_lock_killable(current->mm)) 787 return -EINTR; 788 ret = apply_mlockall_flags(0); 789 mmap_write_unlock(current->mm); 790 return ret; 791} 792 793/* 794 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB 795 * shm segments) get accounted against the user_struct instead. 796 */ 797static DEFINE_SPINLOCK(shmlock_user_lock); 798 799int user_shm_lock(size_t size, struct ucounts *ucounts) 800{ 801 unsigned long lock_limit, locked; 802 long memlock; 803 int allowed = 0; 804 805 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 806 lock_limit = rlimit(RLIMIT_MEMLOCK); 807 if (lock_limit != RLIM_INFINITY) 808 lock_limit >>= PAGE_SHIFT; 809 spin_lock(&shmlock_user_lock); 810 memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); 811 812 if ((memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) { 813 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); 814 goto out; 815 } 816 if (!get_ucounts(ucounts)) { 817 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); 818 allowed = 0; 819 goto out; 820 } 821 allowed = 1; 822out: 823 spin_unlock(&shmlock_user_lock); 824 return allowed; 825} 826 827void user_shm_unlock(size_t size, struct ucounts *ucounts) 828{ 829 spin_lock(&shmlock_user_lock); 830 dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT); 831 spin_unlock(&shmlock_user_lock); 832 put_ucounts(ucounts); 833} 834