1 /* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7 /* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12 /* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23 /* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31 /* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41 #include <linux/kernel_stat.h> 42 #include <linux/mm.h> 43 #include <linux/sched/mm.h> 44 #include <linux/sched/coredump.h> 45 #include <linux/sched/numa_balancing.h> 46 #include <linux/sched/task.h> 47 #include <linux/hugetlb.h> 48 #include <linux/mman.h> 49 #include <linux/swap.h> 50 #include <linux/highmem.h> 51 #include <linux/pagemap.h> 52 #include <linux/memremap.h> 53 #include <linux/ksm.h> 54 #include <linux/rmap.h> 55 #include <linux/export.h> 56 #include <linux/delayacct.h> 57 #include <linux/init.h> 58 #include <linux/pfn_t.h> 59 #include <linux/writeback.h> 60 #include <linux/memcontrol.h> 61 #include <linux/mmu_notifier.h> 62 #include <linux/kallsyms.h> 63 #include <linux/swapops.h> 64 #include <linux/elf.h> 65 #include <linux/gfp.h> 66 #include <linux/migrate.h> 67 #include <linux/string.h> 68 #include <linux/dma-debug.h> 69 #include <linux/debugfs.h> 70 #include <linux/userfaultfd_k.h> 71 #include <linux/dax.h> 72 #include <linux/oom.h> 73 74 #include <asm/io.h> 75 #include <asm/mmu_context.h> 76 #include <asm/pgalloc.h> 77 #include <linux/uaccess.h> 78 #include <asm/tlb.h> 79 #include <asm/tlbflush.h> 80 #include <asm/pgtable.h> 81 82 #include "internal.h" 83 84 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 85 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 86 #endif 87 88 #ifndef CONFIG_NEED_MULTIPLE_NODES 89 /* use the per-pgdat data instead for discontigmem - mbligh */ 90 unsigned long max_mapnr; 91 EXPORT_SYMBOL(max_mapnr); 92 93 struct page *mem_map; 94 EXPORT_SYMBOL(mem_map); 95 #endif 96 97 /* 98 * A number of key systems in x86 including ioremap() rely on the assumption 99 * that high_memory defines the upper bound on direct map memory, then end 100 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 101 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 102 * and ZONE_HIGHMEM. 103 */ 104 void *high_memory; 105 EXPORT_SYMBOL(high_memory); 106 107 /* 108 * Randomize the address space (stacks, mmaps, brk, etc.). 109 * 110 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 111 * as ancient (libc5 based) binaries can segfault. ) 112 */ 113 int randomize_va_space __read_mostly = 114 #ifdef CONFIG_COMPAT_BRK 115 1; 116 #else 117 2; 118 #endif 119 120 static int __init disable_randmaps(char *s) 121 { 122 randomize_va_space = 0; 123 return 1; 124 } 125 __setup("norandmaps", disable_randmaps); 126 127 unsigned long zero_pfn __read_mostly; 128 EXPORT_SYMBOL(zero_pfn); 129 130 unsigned long highest_memmap_pfn __read_mostly; 131 132 /* 133 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 134 */ 135 static int __init init_zero_pfn(void) 136 { 137 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 138 return 0; 139 } 140 core_initcall(init_zero_pfn); 141 142 143 #if defined(SPLIT_RSS_COUNTING) 144 145 void sync_mm_rss(struct mm_struct *mm) 146 { 147 int i; 148 149 for (i = 0; i < NR_MM_COUNTERS; i++) { 150 if (current->rss_stat.count[i]) { 151 add_mm_counter(mm, i, current->rss_stat.count[i]); 152 current->rss_stat.count[i] = 0; 153 } 154 } 155 current->rss_stat.events = 0; 156 } 157 158 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 159 { 160 struct task_struct *task = current; 161 162 if (likely(task->mm == mm)) 163 task->rss_stat.count[member] += val; 164 else 165 add_mm_counter(mm, member, val); 166 } 167 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 168 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 169 170 /* sync counter once per 64 page faults */ 171 #define TASK_RSS_EVENTS_THRESH (64) 172 static void check_sync_rss_stat(struct task_struct *task) 173 { 174 if (unlikely(task != current)) 175 return; 176 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 177 sync_mm_rss(task->mm); 178 } 179 #else /* SPLIT_RSS_COUNTING */ 180 181 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 182 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 183 184 static void check_sync_rss_stat(struct task_struct *task) 185 { 186 } 187 188 #endif /* SPLIT_RSS_COUNTING */ 189 190 #ifdef HAVE_GENERIC_MMU_GATHER 191 192 static bool tlb_next_batch(struct mmu_gather *tlb) 193 { 194 struct mmu_gather_batch *batch; 195 196 batch = tlb->active; 197 if (batch->next) { 198 tlb->active = batch->next; 199 return true; 200 } 201 202 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 203 return false; 204 205 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 206 if (!batch) 207 return false; 208 209 tlb->batch_count++; 210 batch->next = NULL; 211 batch->nr = 0; 212 batch->max = MAX_GATHER_BATCH; 213 214 tlb->active->next = batch; 215 tlb->active = batch; 216 217 return true; 218 } 219 220 void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, 221 unsigned long start, unsigned long end) 222 { 223 tlb->mm = mm; 224 225 /* Is it from 0 to ~0? */ 226 tlb->fullmm = !(start | (end+1)); 227 tlb->need_flush_all = 0; 228 tlb->local.next = NULL; 229 tlb->local.nr = 0; 230 tlb->local.max = ARRAY_SIZE(tlb->__pages); 231 tlb->active = &tlb->local; 232 tlb->batch_count = 0; 233 234 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 235 tlb->batch = NULL; 236 #endif 237 tlb->page_size = 0; 238 239 __tlb_reset_range(tlb); 240 } 241 242 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) 243 { 244 if (!tlb->end) 245 return; 246 247 tlb_flush(tlb); 248 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end); 249 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 250 tlb_table_flush(tlb); 251 #endif 252 __tlb_reset_range(tlb); 253 } 254 255 static void tlb_flush_mmu_free(struct mmu_gather *tlb) 256 { 257 struct mmu_gather_batch *batch; 258 259 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) { 260 free_pages_and_swap_cache(batch->pages, batch->nr); 261 batch->nr = 0; 262 } 263 tlb->active = &tlb->local; 264 } 265 266 void tlb_flush_mmu(struct mmu_gather *tlb) 267 { 268 tlb_flush_mmu_tlbonly(tlb); 269 tlb_flush_mmu_free(tlb); 270 } 271 272 /* tlb_finish_mmu 273 * Called at the end of the shootdown operation to free up any resources 274 * that were required. 275 */ 276 void arch_tlb_finish_mmu(struct mmu_gather *tlb, 277 unsigned long start, unsigned long end, bool force) 278 { 279 struct mmu_gather_batch *batch, *next; 280 281 if (force) 282 __tlb_adjust_range(tlb, start, end - start); 283 284 tlb_flush_mmu(tlb); 285 286 /* keep the page table cache within bounds */ 287 check_pgt_cache(); 288 289 for (batch = tlb->local.next; batch; batch = next) { 290 next = batch->next; 291 free_pages((unsigned long)batch, 0); 292 } 293 tlb->local.next = NULL; 294 } 295 296 /* __tlb_remove_page 297 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 298 * handling the additional races in SMP caused by other CPUs caching valid 299 * mappings in their TLBs. Returns the number of free page slots left. 300 * When out of page slots we must call tlb_flush_mmu(). 301 *returns true if the caller should flush. 302 */ 303 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size) 304 { 305 struct mmu_gather_batch *batch; 306 307 VM_BUG_ON(!tlb->end); 308 VM_WARN_ON(tlb->page_size != page_size); 309 310 batch = tlb->active; 311 /* 312 * Add the page and check if we are full. If so 313 * force a flush. 314 */ 315 batch->pages[batch->nr++] = page; 316 if (batch->nr == batch->max) { 317 if (!tlb_next_batch(tlb)) 318 return true; 319 batch = tlb->active; 320 } 321 VM_BUG_ON_PAGE(batch->nr > batch->max, page); 322 323 return false; 324 } 325 326 #endif /* HAVE_GENERIC_MMU_GATHER */ 327 328 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 329 330 /* 331 * See the comment near struct mmu_table_batch. 332 */ 333 334 static void tlb_remove_table_smp_sync(void *arg) 335 { 336 /* Simply deliver the interrupt */ 337 } 338 339 static void tlb_remove_table_one(void *table) 340 { 341 /* 342 * This isn't an RCU grace period and hence the page-tables cannot be 343 * assumed to be actually RCU-freed. 344 * 345 * It is however sufficient for software page-table walkers that rely on 346 * IRQ disabling. See the comment near struct mmu_table_batch. 347 */ 348 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 349 __tlb_remove_table(table); 350 } 351 352 static void tlb_remove_table_rcu(struct rcu_head *head) 353 { 354 struct mmu_table_batch *batch; 355 int i; 356 357 batch = container_of(head, struct mmu_table_batch, rcu); 358 359 for (i = 0; i < batch->nr; i++) 360 __tlb_remove_table(batch->tables[i]); 361 362 free_page((unsigned long)batch); 363 } 364 365 void tlb_table_flush(struct mmu_gather *tlb) 366 { 367 struct mmu_table_batch **batch = &tlb->batch; 368 369 if (*batch) { 370 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 371 *batch = NULL; 372 } 373 } 374 375 void tlb_remove_table(struct mmu_gather *tlb, void *table) 376 { 377 struct mmu_table_batch **batch = &tlb->batch; 378 379 /* 380 * When there's less then two users of this mm there cannot be a 381 * concurrent page-table walk. 382 */ 383 if (atomic_read(&tlb->mm->mm_users) < 2) { 384 __tlb_remove_table(table); 385 return; 386 } 387 388 if (*batch == NULL) { 389 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 390 if (*batch == NULL) { 391 tlb_remove_table_one(table); 392 return; 393 } 394 (*batch)->nr = 0; 395 } 396 (*batch)->tables[(*batch)->nr++] = table; 397 if ((*batch)->nr == MAX_TABLE_BATCH) 398 tlb_table_flush(tlb); 399 } 400 401 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 402 403 /* tlb_gather_mmu 404 * Called to initialize an (on-stack) mmu_gather structure for page-table 405 * tear-down from @mm. The @fullmm argument is used when @mm is without 406 * users and we're going to destroy the full address space (exit/execve). 407 */ 408 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, 409 unsigned long start, unsigned long end) 410 { 411 arch_tlb_gather_mmu(tlb, mm, start, end); 412 inc_tlb_flush_pending(tlb->mm); 413 } 414 415 void tlb_finish_mmu(struct mmu_gather *tlb, 416 unsigned long start, unsigned long end) 417 { 418 /* 419 * If there are parallel threads are doing PTE changes on same range 420 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB 421 * flush by batching, a thread has stable TLB entry can fail to flush 422 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB 423 * forcefully if we detect parallel PTE batching threads. 424 */ 425 bool force = mm_tlb_flush_nested(tlb->mm); 426 427 arch_tlb_finish_mmu(tlb, start, end, force); 428 dec_tlb_flush_pending(tlb->mm); 429 } 430 431 /* 432 * Note: this doesn't free the actual pages themselves. That 433 * has been handled earlier when unmapping all the memory regions. 434 */ 435 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 436 unsigned long addr) 437 { 438 pgtable_t token = pmd_pgtable(*pmd); 439 pmd_clear(pmd); 440 pte_free_tlb(tlb, token, addr); 441 atomic_long_dec(&tlb->mm->nr_ptes); 442 } 443 444 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 445 unsigned long addr, unsigned long end, 446 unsigned long floor, unsigned long ceiling) 447 { 448 pmd_t *pmd; 449 unsigned long next; 450 unsigned long start; 451 452 start = addr; 453 pmd = pmd_offset(pud, addr); 454 do { 455 next = pmd_addr_end(addr, end); 456 if (pmd_none_or_clear_bad(pmd)) 457 continue; 458 free_pte_range(tlb, pmd, addr); 459 } while (pmd++, addr = next, addr != end); 460 461 start &= PUD_MASK; 462 if (start < floor) 463 return; 464 if (ceiling) { 465 ceiling &= PUD_MASK; 466 if (!ceiling) 467 return; 468 } 469 if (end - 1 > ceiling - 1) 470 return; 471 472 pmd = pmd_offset(pud, start); 473 pud_clear(pud); 474 pmd_free_tlb(tlb, pmd, start); 475 mm_dec_nr_pmds(tlb->mm); 476 } 477 478 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, 479 unsigned long addr, unsigned long end, 480 unsigned long floor, unsigned long ceiling) 481 { 482 pud_t *pud; 483 unsigned long next; 484 unsigned long start; 485 486 start = addr; 487 pud = pud_offset(p4d, addr); 488 do { 489 next = pud_addr_end(addr, end); 490 if (pud_none_or_clear_bad(pud)) 491 continue; 492 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 493 } while (pud++, addr = next, addr != end); 494 495 start &= P4D_MASK; 496 if (start < floor) 497 return; 498 if (ceiling) { 499 ceiling &= P4D_MASK; 500 if (!ceiling) 501 return; 502 } 503 if (end - 1 > ceiling - 1) 504 return; 505 506 pud = pud_offset(p4d, start); 507 p4d_clear(p4d); 508 pud_free_tlb(tlb, pud, start); 509 } 510 511 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, 512 unsigned long addr, unsigned long end, 513 unsigned long floor, unsigned long ceiling) 514 { 515 p4d_t *p4d; 516 unsigned long next; 517 unsigned long start; 518 519 start = addr; 520 p4d = p4d_offset(pgd, addr); 521 do { 522 next = p4d_addr_end(addr, end); 523 if (p4d_none_or_clear_bad(p4d)) 524 continue; 525 free_pud_range(tlb, p4d, addr, next, floor, ceiling); 526 } while (p4d++, addr = next, addr != end); 527 528 start &= PGDIR_MASK; 529 if (start < floor) 530 return; 531 if (ceiling) { 532 ceiling &= PGDIR_MASK; 533 if (!ceiling) 534 return; 535 } 536 if (end - 1 > ceiling - 1) 537 return; 538 539 p4d = p4d_offset(pgd, start); 540 pgd_clear(pgd); 541 p4d_free_tlb(tlb, p4d, start); 542 } 543 544 /* 545 * This function frees user-level page tables of a process. 546 */ 547 void free_pgd_range(struct mmu_gather *tlb, 548 unsigned long addr, unsigned long end, 549 unsigned long floor, unsigned long ceiling) 550 { 551 pgd_t *pgd; 552 unsigned long next; 553 554 /* 555 * The next few lines have given us lots of grief... 556 * 557 * Why are we testing PMD* at this top level? Because often 558 * there will be no work to do at all, and we'd prefer not to 559 * go all the way down to the bottom just to discover that. 560 * 561 * Why all these "- 1"s? Because 0 represents both the bottom 562 * of the address space and the top of it (using -1 for the 563 * top wouldn't help much: the masks would do the wrong thing). 564 * The rule is that addr 0 and floor 0 refer to the bottom of 565 * the address space, but end 0 and ceiling 0 refer to the top 566 * Comparisons need to use "end - 1" and "ceiling - 1" (though 567 * that end 0 case should be mythical). 568 * 569 * Wherever addr is brought up or ceiling brought down, we must 570 * be careful to reject "the opposite 0" before it confuses the 571 * subsequent tests. But what about where end is brought down 572 * by PMD_SIZE below? no, end can't go down to 0 there. 573 * 574 * Whereas we round start (addr) and ceiling down, by different 575 * masks at different levels, in order to test whether a table 576 * now has no other vmas using it, so can be freed, we don't 577 * bother to round floor or end up - the tests don't need that. 578 */ 579 580 addr &= PMD_MASK; 581 if (addr < floor) { 582 addr += PMD_SIZE; 583 if (!addr) 584 return; 585 } 586 if (ceiling) { 587 ceiling &= PMD_MASK; 588 if (!ceiling) 589 return; 590 } 591 if (end - 1 > ceiling - 1) 592 end -= PMD_SIZE; 593 if (addr > end - 1) 594 return; 595 /* 596 * We add page table cache pages with PAGE_SIZE, 597 * (see pte_free_tlb()), flush the tlb if we need 598 */ 599 tlb_remove_check_page_size_change(tlb, PAGE_SIZE); 600 pgd = pgd_offset(tlb->mm, addr); 601 do { 602 next = pgd_addr_end(addr, end); 603 if (pgd_none_or_clear_bad(pgd)) 604 continue; 605 free_p4d_range(tlb, pgd, addr, next, floor, ceiling); 606 } while (pgd++, addr = next, addr != end); 607 } 608 609 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 610 unsigned long floor, unsigned long ceiling) 611 { 612 while (vma) { 613 struct vm_area_struct *next = vma->vm_next; 614 unsigned long addr = vma->vm_start; 615 616 /* 617 * Hide vma from rmap and truncate_pagecache before freeing 618 * pgtables 619 */ 620 unlink_anon_vmas(vma); 621 unlink_file_vma(vma); 622 623 if (is_vm_hugetlb_page(vma)) { 624 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 625 floor, next ? next->vm_start : ceiling); 626 } else { 627 /* 628 * Optimization: gather nearby vmas into one call down 629 */ 630 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 631 && !is_vm_hugetlb_page(next)) { 632 vma = next; 633 next = vma->vm_next; 634 unlink_anon_vmas(vma); 635 unlink_file_vma(vma); 636 } 637 free_pgd_range(tlb, addr, vma->vm_end, 638 floor, next ? next->vm_start : ceiling); 639 } 640 vma = next; 641 } 642 } 643 644 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 645 { 646 spinlock_t *ptl; 647 pgtable_t new = pte_alloc_one(mm, address); 648 if (!new) 649 return -ENOMEM; 650 651 /* 652 * Ensure all pte setup (eg. pte page lock and page clearing) are 653 * visible before the pte is made visible to other CPUs by being 654 * put into page tables. 655 * 656 * The other side of the story is the pointer chasing in the page 657 * table walking code (when walking the page table without locking; 658 * ie. most of the time). Fortunately, these data accesses consist 659 * of a chain of data-dependent loads, meaning most CPUs (alpha 660 * being the notable exception) will already guarantee loads are 661 * seen in-order. See the alpha page table accessors for the 662 * smp_read_barrier_depends() barriers in page table walking code. 663 */ 664 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 665 666 ptl = pmd_lock(mm, pmd); 667 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 668 atomic_long_inc(&mm->nr_ptes); 669 pmd_populate(mm, pmd, new); 670 new = NULL; 671 } 672 spin_unlock(ptl); 673 if (new) 674 pte_free(mm, new); 675 return 0; 676 } 677 678 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 679 { 680 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 681 if (!new) 682 return -ENOMEM; 683 684 smp_wmb(); /* See comment in __pte_alloc */ 685 686 spin_lock(&init_mm.page_table_lock); 687 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 688 pmd_populate_kernel(&init_mm, pmd, new); 689 new = NULL; 690 } 691 spin_unlock(&init_mm.page_table_lock); 692 if (new) 693 pte_free_kernel(&init_mm, new); 694 return 0; 695 } 696 697 static inline void init_rss_vec(int *rss) 698 { 699 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 700 } 701 702 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 703 { 704 int i; 705 706 if (current->mm == mm) 707 sync_mm_rss(mm); 708 for (i = 0; i < NR_MM_COUNTERS; i++) 709 if (rss[i]) 710 add_mm_counter(mm, i, rss[i]); 711 } 712 713 /* 714 * This function is called to print an error when a bad pte 715 * is found. For example, we might have a PFN-mapped pte in 716 * a region that doesn't allow it. 717 * 718 * The calling function must still handle the error. 719 */ 720 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 721 pte_t pte, struct page *page) 722 { 723 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 724 p4d_t *p4d = p4d_offset(pgd, addr); 725 pud_t *pud = pud_offset(p4d, addr); 726 pmd_t *pmd = pmd_offset(pud, addr); 727 struct address_space *mapping; 728 pgoff_t index; 729 static unsigned long resume; 730 static unsigned long nr_shown; 731 static unsigned long nr_unshown; 732 733 /* 734 * Allow a burst of 60 reports, then keep quiet for that minute; 735 * or allow a steady drip of one report per second. 736 */ 737 if (nr_shown == 60) { 738 if (time_before(jiffies, resume)) { 739 nr_unshown++; 740 return; 741 } 742 if (nr_unshown) { 743 pr_alert("BUG: Bad page map: %lu messages suppressed\n", 744 nr_unshown); 745 nr_unshown = 0; 746 } 747 nr_shown = 0; 748 } 749 if (nr_shown++ == 0) 750 resume = jiffies + 60 * HZ; 751 752 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 753 index = linear_page_index(vma, addr); 754 755 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 756 current->comm, 757 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 758 if (page) 759 dump_page(page, "bad pte"); 760 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 761 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 762 /* 763 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 764 */ 765 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n", 766 vma->vm_file, 767 vma->vm_ops ? vma->vm_ops->fault : NULL, 768 vma->vm_file ? vma->vm_file->f_op->mmap : NULL, 769 mapping ? mapping->a_ops->readpage : NULL); 770 dump_stack(); 771 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 772 } 773 774 /* 775 * vm_normal_page -- This function gets the "struct page" associated with a pte. 776 * 777 * "Special" mappings do not wish to be associated with a "struct page" (either 778 * it doesn't exist, or it exists but they don't want to touch it). In this 779 * case, NULL is returned here. "Normal" mappings do have a struct page. 780 * 781 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 782 * pte bit, in which case this function is trivial. Secondly, an architecture 783 * may not have a spare pte bit, which requires a more complicated scheme, 784 * described below. 785 * 786 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 787 * special mapping (even if there are underlying and valid "struct pages"). 788 * COWed pages of a VM_PFNMAP are always normal. 789 * 790 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 791 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 792 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 793 * mapping will always honor the rule 794 * 795 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 796 * 797 * And for normal mappings this is false. 798 * 799 * This restricts such mappings to be a linear translation from virtual address 800 * to pfn. To get around this restriction, we allow arbitrary mappings so long 801 * as the vma is not a COW mapping; in that case, we know that all ptes are 802 * special (because none can have been COWed). 803 * 804 * 805 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 806 * 807 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 808 * page" backing, however the difference is that _all_ pages with a struct 809 * page (that is, those where pfn_valid is true) are refcounted and considered 810 * normal pages by the VM. The disadvantage is that pages are refcounted 811 * (which can be slower and simply not an option for some PFNMAP users). The 812 * advantage is that we don't have to follow the strict linearity rule of 813 * PFNMAP mappings in order to support COWable mappings. 814 * 815 */ 816 #ifdef __HAVE_ARCH_PTE_SPECIAL 817 # define HAVE_PTE_SPECIAL 1 818 #else 819 # define HAVE_PTE_SPECIAL 0 820 #endif 821 struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 822 pte_t pte, bool with_public_device) 823 { 824 unsigned long pfn = pte_pfn(pte); 825 826 if (HAVE_PTE_SPECIAL) { 827 if (likely(!pte_special(pte))) 828 goto check_pfn; 829 if (vma->vm_ops && vma->vm_ops->find_special_page) 830 return vma->vm_ops->find_special_page(vma, addr); 831 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 832 return NULL; 833 if (is_zero_pfn(pfn)) 834 return NULL; 835 836 /* 837 * Device public pages are special pages (they are ZONE_DEVICE 838 * pages but different from persistent memory). They behave 839 * allmost like normal pages. The difference is that they are 840 * not on the lru and thus should never be involve with any- 841 * thing that involve lru manipulation (mlock, numa balancing, 842 * ...). 843 * 844 * This is why we still want to return NULL for such page from 845 * vm_normal_page() so that we do not have to special case all 846 * call site of vm_normal_page(). 847 */ 848 if (likely(pfn <= highest_memmap_pfn)) { 849 struct page *page = pfn_to_page(pfn); 850 851 if (is_device_public_page(page)) { 852 if (with_public_device) 853 return page; 854 return NULL; 855 } 856 } 857 print_bad_pte(vma, addr, pte, NULL); 858 return NULL; 859 } 860 861 /* !HAVE_PTE_SPECIAL case follows: */ 862 863 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 864 if (vma->vm_flags & VM_MIXEDMAP) { 865 if (!pfn_valid(pfn)) 866 return NULL; 867 goto out; 868 } else { 869 unsigned long off; 870 off = (addr - vma->vm_start) >> PAGE_SHIFT; 871 if (pfn == vma->vm_pgoff + off) 872 return NULL; 873 if (!is_cow_mapping(vma->vm_flags)) 874 return NULL; 875 } 876 } 877 878 if (is_zero_pfn(pfn)) 879 return NULL; 880 check_pfn: 881 if (unlikely(pfn > highest_memmap_pfn)) { 882 print_bad_pte(vma, addr, pte, NULL); 883 return NULL; 884 } 885 886 /* 887 * NOTE! We still have PageReserved() pages in the page tables. 888 * eg. VDSO mappings can cause them to exist. 889 */ 890 out: 891 return pfn_to_page(pfn); 892 } 893 894 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 895 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, 896 pmd_t pmd) 897 { 898 unsigned long pfn = pmd_pfn(pmd); 899 900 /* 901 * There is no pmd_special() but there may be special pmds, e.g. 902 * in a direct-access (dax) mapping, so let's just replicate the 903 * !HAVE_PTE_SPECIAL case from vm_normal_page() here. 904 */ 905 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 906 if (vma->vm_flags & VM_MIXEDMAP) { 907 if (!pfn_valid(pfn)) 908 return NULL; 909 goto out; 910 } else { 911 unsigned long off; 912 off = (addr - vma->vm_start) >> PAGE_SHIFT; 913 if (pfn == vma->vm_pgoff + off) 914 return NULL; 915 if (!is_cow_mapping(vma->vm_flags)) 916 return NULL; 917 } 918 } 919 920 if (is_zero_pfn(pfn)) 921 return NULL; 922 if (unlikely(pfn > highest_memmap_pfn)) 923 return NULL; 924 925 /* 926 * NOTE! We still have PageReserved() pages in the page tables. 927 * eg. VDSO mappings can cause them to exist. 928 */ 929 out: 930 return pfn_to_page(pfn); 931 } 932 #endif 933 934 /* 935 * copy one vm_area from one task to the other. Assumes the page tables 936 * already present in the new task to be cleared in the whole range 937 * covered by this vma. 938 */ 939 940 static inline unsigned long 941 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 942 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 943 unsigned long addr, int *rss) 944 { 945 unsigned long vm_flags = vma->vm_flags; 946 pte_t pte = *src_pte; 947 struct page *page; 948 949 /* pte contains position in swap or file, so copy. */ 950 if (unlikely(!pte_present(pte))) { 951 swp_entry_t entry = pte_to_swp_entry(pte); 952 953 if (likely(!non_swap_entry(entry))) { 954 if (swap_duplicate(entry) < 0) 955 return entry.val; 956 957 /* make sure dst_mm is on swapoff's mmlist. */ 958 if (unlikely(list_empty(&dst_mm->mmlist))) { 959 spin_lock(&mmlist_lock); 960 if (list_empty(&dst_mm->mmlist)) 961 list_add(&dst_mm->mmlist, 962 &src_mm->mmlist); 963 spin_unlock(&mmlist_lock); 964 } 965 rss[MM_SWAPENTS]++; 966 } else if (is_migration_entry(entry)) { 967 page = migration_entry_to_page(entry); 968 969 rss[mm_counter(page)]++; 970 971 if (is_write_migration_entry(entry) && 972 is_cow_mapping(vm_flags)) { 973 /* 974 * COW mappings require pages in both 975 * parent and child to be set to read. 976 */ 977 make_migration_entry_read(&entry); 978 pte = swp_entry_to_pte(entry); 979 if (pte_swp_soft_dirty(*src_pte)) 980 pte = pte_swp_mksoft_dirty(pte); 981 set_pte_at(src_mm, addr, src_pte, pte); 982 } 983 } else if (is_device_private_entry(entry)) { 984 page = device_private_entry_to_page(entry); 985 986 /* 987 * Update rss count even for unaddressable pages, as 988 * they should treated just like normal pages in this 989 * respect. 990 * 991 * We will likely want to have some new rss counters 992 * for unaddressable pages, at some point. But for now 993 * keep things as they are. 994 */ 995 get_page(page); 996 rss[mm_counter(page)]++; 997 page_dup_rmap(page, false); 998 999 /* 1000 * We do not preserve soft-dirty information, because so 1001 * far, checkpoint/restore is the only feature that 1002 * requires that. And checkpoint/restore does not work 1003 * when a device driver is involved (you cannot easily 1004 * save and restore device driver state). 1005 */ 1006 if (is_write_device_private_entry(entry) && 1007 is_cow_mapping(vm_flags)) { 1008 make_device_private_entry_read(&entry); 1009 pte = swp_entry_to_pte(entry); 1010 set_pte_at(src_mm, addr, src_pte, pte); 1011 } 1012 } 1013 goto out_set_pte; 1014 } 1015 1016 /* 1017 * If it's a COW mapping, write protect it both 1018 * in the parent and the child 1019 */ 1020 if (is_cow_mapping(vm_flags)) { 1021 ptep_set_wrprotect(src_mm, addr, src_pte); 1022 pte = pte_wrprotect(pte); 1023 } 1024 1025 /* 1026 * If it's a shared mapping, mark it clean in 1027 * the child 1028 */ 1029 if (vm_flags & VM_SHARED) 1030 pte = pte_mkclean(pte); 1031 pte = pte_mkold(pte); 1032 1033 page = vm_normal_page(vma, addr, pte); 1034 if (page) { 1035 get_page(page); 1036 page_dup_rmap(page, false); 1037 rss[mm_counter(page)]++; 1038 } else if (pte_devmap(pte)) { 1039 page = pte_page(pte); 1040 1041 /* 1042 * Cache coherent device memory behave like regular page and 1043 * not like persistent memory page. For more informations see 1044 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h 1045 */ 1046 if (is_device_public_page(page)) { 1047 get_page(page); 1048 page_dup_rmap(page, false); 1049 rss[mm_counter(page)]++; 1050 } 1051 } 1052 1053 out_set_pte: 1054 set_pte_at(dst_mm, addr, dst_pte, pte); 1055 return 0; 1056 } 1057 1058 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1059 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 1060 unsigned long addr, unsigned long end) 1061 { 1062 pte_t *orig_src_pte, *orig_dst_pte; 1063 pte_t *src_pte, *dst_pte; 1064 spinlock_t *src_ptl, *dst_ptl; 1065 int progress = 0; 1066 int rss[NR_MM_COUNTERS]; 1067 swp_entry_t entry = (swp_entry_t){0}; 1068 1069 again: 1070 init_rss_vec(rss); 1071 1072 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 1073 if (!dst_pte) 1074 return -ENOMEM; 1075 src_pte = pte_offset_map(src_pmd, addr); 1076 src_ptl = pte_lockptr(src_mm, src_pmd); 1077 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1078 orig_src_pte = src_pte; 1079 orig_dst_pte = dst_pte; 1080 arch_enter_lazy_mmu_mode(); 1081 1082 do { 1083 /* 1084 * We are holding two locks at this point - either of them 1085 * could generate latencies in another task on another CPU. 1086 */ 1087 if (progress >= 32) { 1088 progress = 0; 1089 if (need_resched() || 1090 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 1091 break; 1092 } 1093 if (pte_none(*src_pte)) { 1094 progress++; 1095 continue; 1096 } 1097 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 1098 vma, addr, rss); 1099 if (entry.val) 1100 break; 1101 progress += 8; 1102 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 1103 1104 arch_leave_lazy_mmu_mode(); 1105 spin_unlock(src_ptl); 1106 pte_unmap(orig_src_pte); 1107 add_mm_rss_vec(dst_mm, rss); 1108 pte_unmap_unlock(orig_dst_pte, dst_ptl); 1109 cond_resched(); 1110 1111 if (entry.val) { 1112 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 1113 return -ENOMEM; 1114 progress = 0; 1115 } 1116 if (addr != end) 1117 goto again; 1118 return 0; 1119 } 1120 1121 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1122 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 1123 unsigned long addr, unsigned long end) 1124 { 1125 pmd_t *src_pmd, *dst_pmd; 1126 unsigned long next; 1127 1128 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 1129 if (!dst_pmd) 1130 return -ENOMEM; 1131 src_pmd = pmd_offset(src_pud, addr); 1132 do { 1133 next = pmd_addr_end(addr, end); 1134 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) 1135 || pmd_devmap(*src_pmd)) { 1136 int err; 1137 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma); 1138 err = copy_huge_pmd(dst_mm, src_mm, 1139 dst_pmd, src_pmd, addr, vma); 1140 if (err == -ENOMEM) 1141 return -ENOMEM; 1142 if (!err) 1143 continue; 1144 /* fall through */ 1145 } 1146 if (pmd_none_or_clear_bad(src_pmd)) 1147 continue; 1148 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 1149 vma, addr, next)) 1150 return -ENOMEM; 1151 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 1152 return 0; 1153 } 1154 1155 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1156 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma, 1157 unsigned long addr, unsigned long end) 1158 { 1159 pud_t *src_pud, *dst_pud; 1160 unsigned long next; 1161 1162 dst_pud = pud_alloc(dst_mm, dst_p4d, addr); 1163 if (!dst_pud) 1164 return -ENOMEM; 1165 src_pud = pud_offset(src_p4d, addr); 1166 do { 1167 next = pud_addr_end(addr, end); 1168 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { 1169 int err; 1170 1171 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma); 1172 err = copy_huge_pud(dst_mm, src_mm, 1173 dst_pud, src_pud, addr, vma); 1174 if (err == -ENOMEM) 1175 return -ENOMEM; 1176 if (!err) 1177 continue; 1178 /* fall through */ 1179 } 1180 if (pud_none_or_clear_bad(src_pud)) 1181 continue; 1182 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1183 vma, addr, next)) 1184 return -ENOMEM; 1185 } while (dst_pud++, src_pud++, addr = next, addr != end); 1186 return 0; 1187 } 1188 1189 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1190 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 1191 unsigned long addr, unsigned long end) 1192 { 1193 p4d_t *src_p4d, *dst_p4d; 1194 unsigned long next; 1195 1196 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); 1197 if (!dst_p4d) 1198 return -ENOMEM; 1199 src_p4d = p4d_offset(src_pgd, addr); 1200 do { 1201 next = p4d_addr_end(addr, end); 1202 if (p4d_none_or_clear_bad(src_p4d)) 1203 continue; 1204 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d, 1205 vma, addr, next)) 1206 return -ENOMEM; 1207 } while (dst_p4d++, src_p4d++, addr = next, addr != end); 1208 return 0; 1209 } 1210 1211 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1212 struct vm_area_struct *vma) 1213 { 1214 pgd_t *src_pgd, *dst_pgd; 1215 unsigned long next; 1216 unsigned long addr = vma->vm_start; 1217 unsigned long end = vma->vm_end; 1218 unsigned long mmun_start; /* For mmu_notifiers */ 1219 unsigned long mmun_end; /* For mmu_notifiers */ 1220 bool is_cow; 1221 int ret; 1222 1223 /* 1224 * Don't copy ptes where a page fault will fill them correctly. 1225 * Fork becomes much lighter when there are big shared or private 1226 * readonly mappings. The tradeoff is that copy_page_range is more 1227 * efficient than faulting. 1228 */ 1229 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) && 1230 !vma->anon_vma) 1231 return 0; 1232 1233 if (is_vm_hugetlb_page(vma)) 1234 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1235 1236 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1237 /* 1238 * We do not free on error cases below as remove_vma 1239 * gets called on error from higher level routine 1240 */ 1241 ret = track_pfn_copy(vma); 1242 if (ret) 1243 return ret; 1244 } 1245 1246 /* 1247 * We need to invalidate the secondary MMU mappings only when 1248 * there could be a permission downgrade on the ptes of the 1249 * parent mm. And a permission downgrade will only happen if 1250 * is_cow_mapping() returns true. 1251 */ 1252 is_cow = is_cow_mapping(vma->vm_flags); 1253 mmun_start = addr; 1254 mmun_end = end; 1255 if (is_cow) 1256 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1257 mmun_end); 1258 1259 ret = 0; 1260 dst_pgd = pgd_offset(dst_mm, addr); 1261 src_pgd = pgd_offset(src_mm, addr); 1262 do { 1263 next = pgd_addr_end(addr, end); 1264 if (pgd_none_or_clear_bad(src_pgd)) 1265 continue; 1266 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd, 1267 vma, addr, next))) { 1268 ret = -ENOMEM; 1269 break; 1270 } 1271 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1272 1273 if (is_cow) 1274 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1275 return ret; 1276 } 1277 1278 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1279 struct vm_area_struct *vma, pmd_t *pmd, 1280 unsigned long addr, unsigned long end, 1281 struct zap_details *details) 1282 { 1283 struct mm_struct *mm = tlb->mm; 1284 int force_flush = 0; 1285 int rss[NR_MM_COUNTERS]; 1286 spinlock_t *ptl; 1287 pte_t *start_pte; 1288 pte_t *pte; 1289 swp_entry_t entry; 1290 1291 tlb_remove_check_page_size_change(tlb, PAGE_SIZE); 1292 again: 1293 init_rss_vec(rss); 1294 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1295 pte = start_pte; 1296 flush_tlb_batched_pending(mm); 1297 arch_enter_lazy_mmu_mode(); 1298 do { 1299 pte_t ptent = *pte; 1300 if (pte_none(ptent)) 1301 continue; 1302 1303 if (pte_present(ptent)) { 1304 struct page *page; 1305 1306 page = _vm_normal_page(vma, addr, ptent, true); 1307 if (unlikely(details) && page) { 1308 /* 1309 * unmap_shared_mapping_pages() wants to 1310 * invalidate cache without truncating: 1311 * unmap shared but keep private pages. 1312 */ 1313 if (details->check_mapping && 1314 details->check_mapping != page_rmapping(page)) 1315 continue; 1316 } 1317 ptent = ptep_get_and_clear_full(mm, addr, pte, 1318 tlb->fullmm); 1319 tlb_remove_tlb_entry(tlb, pte, addr); 1320 if (unlikely(!page)) 1321 continue; 1322 1323 if (!PageAnon(page)) { 1324 if (pte_dirty(ptent)) { 1325 force_flush = 1; 1326 set_page_dirty(page); 1327 } 1328 if (pte_young(ptent) && 1329 likely(!(vma->vm_flags & VM_SEQ_READ))) 1330 mark_page_accessed(page); 1331 } 1332 rss[mm_counter(page)]--; 1333 page_remove_rmap(page, false); 1334 if (unlikely(page_mapcount(page) < 0)) 1335 print_bad_pte(vma, addr, ptent, page); 1336 if (unlikely(__tlb_remove_page(tlb, page))) { 1337 force_flush = 1; 1338 addr += PAGE_SIZE; 1339 break; 1340 } 1341 continue; 1342 } 1343 1344 entry = pte_to_swp_entry(ptent); 1345 if (non_swap_entry(entry) && is_device_private_entry(entry)) { 1346 struct page *page = device_private_entry_to_page(entry); 1347 1348 if (unlikely(details && details->check_mapping)) { 1349 /* 1350 * unmap_shared_mapping_pages() wants to 1351 * invalidate cache without truncating: 1352 * unmap shared but keep private pages. 1353 */ 1354 if (details->check_mapping != 1355 page_rmapping(page)) 1356 continue; 1357 } 1358 1359 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1360 rss[mm_counter(page)]--; 1361 page_remove_rmap(page, false); 1362 put_page(page); 1363 continue; 1364 } 1365 1366 /* If details->check_mapping, we leave swap entries. */ 1367 if (unlikely(details)) 1368 continue; 1369 1370 entry = pte_to_swp_entry(ptent); 1371 if (!non_swap_entry(entry)) 1372 rss[MM_SWAPENTS]--; 1373 else if (is_migration_entry(entry)) { 1374 struct page *page; 1375 1376 page = migration_entry_to_page(entry); 1377 rss[mm_counter(page)]--; 1378 } 1379 if (unlikely(!free_swap_and_cache(entry))) 1380 print_bad_pte(vma, addr, ptent, NULL); 1381 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1382 } while (pte++, addr += PAGE_SIZE, addr != end); 1383 1384 add_mm_rss_vec(mm, rss); 1385 arch_leave_lazy_mmu_mode(); 1386 1387 /* Do the actual TLB flush before dropping ptl */ 1388 if (force_flush) 1389 tlb_flush_mmu_tlbonly(tlb); 1390 pte_unmap_unlock(start_pte, ptl); 1391 1392 /* 1393 * If we forced a TLB flush (either due to running out of 1394 * batch buffers or because we needed to flush dirty TLB 1395 * entries before releasing the ptl), free the batched 1396 * memory too. Restart if we didn't do everything. 1397 */ 1398 if (force_flush) { 1399 force_flush = 0; 1400 tlb_flush_mmu_free(tlb); 1401 if (addr != end) 1402 goto again; 1403 } 1404 1405 return addr; 1406 } 1407 1408 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1409 struct vm_area_struct *vma, pud_t *pud, 1410 unsigned long addr, unsigned long end, 1411 struct zap_details *details) 1412 { 1413 pmd_t *pmd; 1414 unsigned long next; 1415 1416 pmd = pmd_offset(pud, addr); 1417 do { 1418 next = pmd_addr_end(addr, end); 1419 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { 1420 if (next - addr != HPAGE_PMD_SIZE) { 1421 VM_BUG_ON_VMA(vma_is_anonymous(vma) && 1422 !rwsem_is_locked(&tlb->mm->mmap_sem), vma); 1423 __split_huge_pmd(vma, pmd, addr, false, NULL); 1424 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1425 goto next; 1426 /* fall through */ 1427 } 1428 /* 1429 * Here there can be other concurrent MADV_DONTNEED or 1430 * trans huge page faults running, and if the pmd is 1431 * none or trans huge it can change under us. This is 1432 * because MADV_DONTNEED holds the mmap_sem in read 1433 * mode. 1434 */ 1435 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1436 goto next; 1437 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1438 next: 1439 cond_resched(); 1440 } while (pmd++, addr = next, addr != end); 1441 1442 return addr; 1443 } 1444 1445 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1446 struct vm_area_struct *vma, p4d_t *p4d, 1447 unsigned long addr, unsigned long end, 1448 struct zap_details *details) 1449 { 1450 pud_t *pud; 1451 unsigned long next; 1452 1453 pud = pud_offset(p4d, addr); 1454 do { 1455 next = pud_addr_end(addr, end); 1456 if (pud_trans_huge(*pud) || pud_devmap(*pud)) { 1457 if (next - addr != HPAGE_PUD_SIZE) { 1458 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma); 1459 split_huge_pud(vma, pud, addr); 1460 } else if (zap_huge_pud(tlb, vma, pud, addr)) 1461 goto next; 1462 /* fall through */ 1463 } 1464 if (pud_none_or_clear_bad(pud)) 1465 continue; 1466 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1467 next: 1468 cond_resched(); 1469 } while (pud++, addr = next, addr != end); 1470 1471 return addr; 1472 } 1473 1474 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, 1475 struct vm_area_struct *vma, pgd_t *pgd, 1476 unsigned long addr, unsigned long end, 1477 struct zap_details *details) 1478 { 1479 p4d_t *p4d; 1480 unsigned long next; 1481 1482 p4d = p4d_offset(pgd, addr); 1483 do { 1484 next = p4d_addr_end(addr, end); 1485 if (p4d_none_or_clear_bad(p4d)) 1486 continue; 1487 next = zap_pud_range(tlb, vma, p4d, addr, next, details); 1488 } while (p4d++, addr = next, addr != end); 1489 1490 return addr; 1491 } 1492 1493 void unmap_page_range(struct mmu_gather *tlb, 1494 struct vm_area_struct *vma, 1495 unsigned long addr, unsigned long end, 1496 struct zap_details *details) 1497 { 1498 pgd_t *pgd; 1499 unsigned long next; 1500 1501 BUG_ON(addr >= end); 1502 tlb_start_vma(tlb, vma); 1503 pgd = pgd_offset(vma->vm_mm, addr); 1504 do { 1505 next = pgd_addr_end(addr, end); 1506 if (pgd_none_or_clear_bad(pgd)) 1507 continue; 1508 next = zap_p4d_range(tlb, vma, pgd, addr, next, details); 1509 } while (pgd++, addr = next, addr != end); 1510 tlb_end_vma(tlb, vma); 1511 } 1512 1513 1514 static void unmap_single_vma(struct mmu_gather *tlb, 1515 struct vm_area_struct *vma, unsigned long start_addr, 1516 unsigned long end_addr, 1517 struct zap_details *details) 1518 { 1519 unsigned long start = max(vma->vm_start, start_addr); 1520 unsigned long end; 1521 1522 if (start >= vma->vm_end) 1523 return; 1524 end = min(vma->vm_end, end_addr); 1525 if (end <= vma->vm_start) 1526 return; 1527 1528 if (vma->vm_file) 1529 uprobe_munmap(vma, start, end); 1530 1531 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1532 untrack_pfn(vma, 0, 0); 1533 1534 if (start != end) { 1535 if (unlikely(is_vm_hugetlb_page(vma))) { 1536 /* 1537 * It is undesirable to test vma->vm_file as it 1538 * should be non-null for valid hugetlb area. 1539 * However, vm_file will be NULL in the error 1540 * cleanup path of mmap_region. When 1541 * hugetlbfs ->mmap method fails, 1542 * mmap_region() nullifies vma->vm_file 1543 * before calling this function to clean up. 1544 * Since no pte has actually been setup, it is 1545 * safe to do nothing in this case. 1546 */ 1547 if (vma->vm_file) { 1548 i_mmap_lock_write(vma->vm_file->f_mapping); 1549 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1550 i_mmap_unlock_write(vma->vm_file->f_mapping); 1551 } 1552 } else 1553 unmap_page_range(tlb, vma, start, end, details); 1554 } 1555 } 1556 1557 /** 1558 * unmap_vmas - unmap a range of memory covered by a list of vma's 1559 * @tlb: address of the caller's struct mmu_gather 1560 * @vma: the starting vma 1561 * @start_addr: virtual address at which to start unmapping 1562 * @end_addr: virtual address at which to end unmapping 1563 * 1564 * Unmap all pages in the vma list. 1565 * 1566 * Only addresses between `start' and `end' will be unmapped. 1567 * 1568 * The VMA list must be sorted in ascending virtual address order. 1569 * 1570 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1571 * range after unmap_vmas() returns. So the only responsibility here is to 1572 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1573 * drops the lock and schedules. 1574 */ 1575 void unmap_vmas(struct mmu_gather *tlb, 1576 struct vm_area_struct *vma, unsigned long start_addr, 1577 unsigned long end_addr) 1578 { 1579 struct mm_struct *mm = vma->vm_mm; 1580 1581 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1582 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1583 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1584 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1585 } 1586 1587 /** 1588 * zap_page_range - remove user pages in a given range 1589 * @vma: vm_area_struct holding the applicable pages 1590 * @start: starting address of pages to zap 1591 * @size: number of bytes to zap 1592 * 1593 * Caller must protect the VMA list 1594 */ 1595 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1596 unsigned long size) 1597 { 1598 struct mm_struct *mm = vma->vm_mm; 1599 struct mmu_gather tlb; 1600 unsigned long end = start + size; 1601 1602 lru_add_drain(); 1603 tlb_gather_mmu(&tlb, mm, start, end); 1604 update_hiwater_rss(mm); 1605 mmu_notifier_invalidate_range_start(mm, start, end); 1606 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) { 1607 unmap_single_vma(&tlb, vma, start, end, NULL); 1608 1609 /* 1610 * zap_page_range does not specify whether mmap_sem should be 1611 * held for read or write. That allows parallel zap_page_range 1612 * operations to unmap a PTE and defer a flush meaning that 1613 * this call observes pte_none and fails to flush the TLB. 1614 * Rather than adding a complex API, ensure that no stale 1615 * TLB entries exist when this call returns. 1616 */ 1617 flush_tlb_range(vma, start, end); 1618 } 1619 1620 mmu_notifier_invalidate_range_end(mm, start, end); 1621 tlb_finish_mmu(&tlb, start, end); 1622 } 1623 1624 /** 1625 * zap_page_range_single - remove user pages in a given range 1626 * @vma: vm_area_struct holding the applicable pages 1627 * @address: starting address of pages to zap 1628 * @size: number of bytes to zap 1629 * @details: details of shared cache invalidation 1630 * 1631 * The range must fit into one VMA. 1632 */ 1633 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1634 unsigned long size, struct zap_details *details) 1635 { 1636 struct mm_struct *mm = vma->vm_mm; 1637 struct mmu_gather tlb; 1638 unsigned long end = address + size; 1639 1640 lru_add_drain(); 1641 tlb_gather_mmu(&tlb, mm, address, end); 1642 update_hiwater_rss(mm); 1643 mmu_notifier_invalidate_range_start(mm, address, end); 1644 unmap_single_vma(&tlb, vma, address, end, details); 1645 mmu_notifier_invalidate_range_end(mm, address, end); 1646 tlb_finish_mmu(&tlb, address, end); 1647 } 1648 1649 /** 1650 * zap_vma_ptes - remove ptes mapping the vma 1651 * @vma: vm_area_struct holding ptes to be zapped 1652 * @address: starting address of pages to zap 1653 * @size: number of bytes to zap 1654 * 1655 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1656 * 1657 * The entire address range must be fully contained within the vma. 1658 * 1659 * Returns 0 if successful. 1660 */ 1661 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1662 unsigned long size) 1663 { 1664 if (address < vma->vm_start || address + size > vma->vm_end || 1665 !(vma->vm_flags & VM_PFNMAP)) 1666 return -1; 1667 zap_page_range_single(vma, address, size, NULL); 1668 return 0; 1669 } 1670 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1671 1672 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1673 spinlock_t **ptl) 1674 { 1675 pgd_t *pgd; 1676 p4d_t *p4d; 1677 pud_t *pud; 1678 pmd_t *pmd; 1679 1680 pgd = pgd_offset(mm, addr); 1681 p4d = p4d_alloc(mm, pgd, addr); 1682 if (!p4d) 1683 return NULL; 1684 pud = pud_alloc(mm, p4d, addr); 1685 if (!pud) 1686 return NULL; 1687 pmd = pmd_alloc(mm, pud, addr); 1688 if (!pmd) 1689 return NULL; 1690 1691 VM_BUG_ON(pmd_trans_huge(*pmd)); 1692 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1693 } 1694 1695 /* 1696 * This is the old fallback for page remapping. 1697 * 1698 * For historical reasons, it only allows reserved pages. Only 1699 * old drivers should use this, and they needed to mark their 1700 * pages reserved for the old functions anyway. 1701 */ 1702 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1703 struct page *page, pgprot_t prot) 1704 { 1705 struct mm_struct *mm = vma->vm_mm; 1706 int retval; 1707 pte_t *pte; 1708 spinlock_t *ptl; 1709 1710 retval = -EINVAL; 1711 if (PageAnon(page)) 1712 goto out; 1713 retval = -ENOMEM; 1714 flush_dcache_page(page); 1715 pte = get_locked_pte(mm, addr, &ptl); 1716 if (!pte) 1717 goto out; 1718 retval = -EBUSY; 1719 if (!pte_none(*pte)) 1720 goto out_unlock; 1721 1722 /* Ok, finally just insert the thing.. */ 1723 get_page(page); 1724 inc_mm_counter_fast(mm, mm_counter_file(page)); 1725 page_add_file_rmap(page, false); 1726 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1727 1728 retval = 0; 1729 pte_unmap_unlock(pte, ptl); 1730 return retval; 1731 out_unlock: 1732 pte_unmap_unlock(pte, ptl); 1733 out: 1734 return retval; 1735 } 1736 1737 /** 1738 * vm_insert_page - insert single page into user vma 1739 * @vma: user vma to map to 1740 * @addr: target user address of this page 1741 * @page: source kernel page 1742 * 1743 * This allows drivers to insert individual pages they've allocated 1744 * into a user vma. 1745 * 1746 * The page has to be a nice clean _individual_ kernel allocation. 1747 * If you allocate a compound page, you need to have marked it as 1748 * such (__GFP_COMP), or manually just split the page up yourself 1749 * (see split_page()). 1750 * 1751 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1752 * took an arbitrary page protection parameter. This doesn't allow 1753 * that. Your vma protection will have to be set up correctly, which 1754 * means that if you want a shared writable mapping, you'd better 1755 * ask for a shared writable mapping! 1756 * 1757 * The page does not need to be reserved. 1758 * 1759 * Usually this function is called from f_op->mmap() handler 1760 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 1761 * Caller must set VM_MIXEDMAP on vma if it wants to call this 1762 * function from other places, for example from page-fault handler. 1763 */ 1764 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1765 struct page *page) 1766 { 1767 if (addr < vma->vm_start || addr >= vma->vm_end) 1768 return -EFAULT; 1769 if (!page_count(page)) 1770 return -EINVAL; 1771 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1772 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 1773 BUG_ON(vma->vm_flags & VM_PFNMAP); 1774 vma->vm_flags |= VM_MIXEDMAP; 1775 } 1776 return insert_page(vma, addr, page, vma->vm_page_prot); 1777 } 1778 EXPORT_SYMBOL(vm_insert_page); 1779 1780 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1781 pfn_t pfn, pgprot_t prot, bool mkwrite) 1782 { 1783 struct mm_struct *mm = vma->vm_mm; 1784 int retval; 1785 pte_t *pte, entry; 1786 spinlock_t *ptl; 1787 1788 retval = -ENOMEM; 1789 pte = get_locked_pte(mm, addr, &ptl); 1790 if (!pte) 1791 goto out; 1792 retval = -EBUSY; 1793 if (!pte_none(*pte)) { 1794 if (mkwrite) { 1795 /* 1796 * For read faults on private mappings the PFN passed 1797 * in may not match the PFN we have mapped if the 1798 * mapped PFN is a writeable COW page. In the mkwrite 1799 * case we are creating a writable PTE for a shared 1800 * mapping and we expect the PFNs to match. 1801 */ 1802 if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn))) 1803 goto out_unlock; 1804 entry = *pte; 1805 goto out_mkwrite; 1806 } else 1807 goto out_unlock; 1808 } 1809 1810 /* Ok, finally just insert the thing.. */ 1811 if (pfn_t_devmap(pfn)) 1812 entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); 1813 else 1814 entry = pte_mkspecial(pfn_t_pte(pfn, prot)); 1815 1816 out_mkwrite: 1817 if (mkwrite) { 1818 entry = pte_mkyoung(entry); 1819 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1820 } 1821 1822 set_pte_at(mm, addr, pte, entry); 1823 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 1824 1825 retval = 0; 1826 out_unlock: 1827 pte_unmap_unlock(pte, ptl); 1828 out: 1829 return retval; 1830 } 1831 1832 /** 1833 * vm_insert_pfn - insert single pfn into user vma 1834 * @vma: user vma to map to 1835 * @addr: target user address of this page 1836 * @pfn: source kernel pfn 1837 * 1838 * Similar to vm_insert_page, this allows drivers to insert individual pages 1839 * they've allocated into a user vma. Same comments apply. 1840 * 1841 * This function should only be called from a vm_ops->fault handler, and 1842 * in that case the handler should return NULL. 1843 * 1844 * vma cannot be a COW mapping. 1845 * 1846 * As this is called only for pages that do not currently exist, we 1847 * do not need to flush old virtual caches or the TLB. 1848 */ 1849 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1850 unsigned long pfn) 1851 { 1852 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); 1853 } 1854 EXPORT_SYMBOL(vm_insert_pfn); 1855 1856 /** 1857 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot 1858 * @vma: user vma to map to 1859 * @addr: target user address of this page 1860 * @pfn: source kernel pfn 1861 * @pgprot: pgprot flags for the inserted page 1862 * 1863 * This is exactly like vm_insert_pfn, except that it allows drivers to 1864 * to override pgprot on a per-page basis. 1865 * 1866 * This only makes sense for IO mappings, and it makes no sense for 1867 * cow mappings. In general, using multiple vmas is preferable; 1868 * vm_insert_pfn_prot should only be used if using multiple VMAs is 1869 * impractical. 1870 */ 1871 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, 1872 unsigned long pfn, pgprot_t pgprot) 1873 { 1874 int ret; 1875 /* 1876 * Technically, architectures with pte_special can avoid all these 1877 * restrictions (same for remap_pfn_range). However we would like 1878 * consistency in testing and feature parity among all, so we should 1879 * try to keep these invariants in place for everybody. 1880 */ 1881 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1882 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1883 (VM_PFNMAP|VM_MIXEDMAP)); 1884 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1885 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1886 1887 if (addr < vma->vm_start || addr >= vma->vm_end) 1888 return -EFAULT; 1889 1890 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); 1891 1892 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, 1893 false); 1894 1895 return ret; 1896 } 1897 EXPORT_SYMBOL(vm_insert_pfn_prot); 1898 1899 static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1900 pfn_t pfn, bool mkwrite) 1901 { 1902 pgprot_t pgprot = vma->vm_page_prot; 1903 1904 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1905 1906 if (addr < vma->vm_start || addr >= vma->vm_end) 1907 return -EFAULT; 1908 1909 track_pfn_insert(vma, &pgprot, pfn); 1910 1911 /* 1912 * If we don't have pte special, then we have to use the pfn_valid() 1913 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1914 * refcount the page if pfn_valid is true (hence insert_page rather 1915 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1916 * without pte special, it would there be refcounted as a normal page. 1917 */ 1918 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { 1919 struct page *page; 1920 1921 /* 1922 * At this point we are committed to insert_page() 1923 * regardless of whether the caller specified flags that 1924 * result in pfn_t_has_page() == false. 1925 */ 1926 page = pfn_to_page(pfn_t_to_pfn(pfn)); 1927 return insert_page(vma, addr, page, pgprot); 1928 } 1929 return insert_pfn(vma, addr, pfn, pgprot, mkwrite); 1930 } 1931 1932 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1933 pfn_t pfn) 1934 { 1935 return __vm_insert_mixed(vma, addr, pfn, false); 1936 1937 } 1938 EXPORT_SYMBOL(vm_insert_mixed); 1939 1940 int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr, 1941 pfn_t pfn) 1942 { 1943 return __vm_insert_mixed(vma, addr, pfn, true); 1944 } 1945 EXPORT_SYMBOL(vm_insert_mixed_mkwrite); 1946 1947 /* 1948 * maps a range of physical memory into the requested pages. the old 1949 * mappings are removed. any references to nonexistent pages results 1950 * in null mappings (currently treated as "copy-on-access") 1951 */ 1952 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1953 unsigned long addr, unsigned long end, 1954 unsigned long pfn, pgprot_t prot) 1955 { 1956 pte_t *pte; 1957 spinlock_t *ptl; 1958 1959 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1960 if (!pte) 1961 return -ENOMEM; 1962 arch_enter_lazy_mmu_mode(); 1963 do { 1964 BUG_ON(!pte_none(*pte)); 1965 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1966 pfn++; 1967 } while (pte++, addr += PAGE_SIZE, addr != end); 1968 arch_leave_lazy_mmu_mode(); 1969 pte_unmap_unlock(pte - 1, ptl); 1970 return 0; 1971 } 1972 1973 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1974 unsigned long addr, unsigned long end, 1975 unsigned long pfn, pgprot_t prot) 1976 { 1977 pmd_t *pmd; 1978 unsigned long next; 1979 1980 pfn -= addr >> PAGE_SHIFT; 1981 pmd = pmd_alloc(mm, pud, addr); 1982 if (!pmd) 1983 return -ENOMEM; 1984 VM_BUG_ON(pmd_trans_huge(*pmd)); 1985 do { 1986 next = pmd_addr_end(addr, end); 1987 if (remap_pte_range(mm, pmd, addr, next, 1988 pfn + (addr >> PAGE_SHIFT), prot)) 1989 return -ENOMEM; 1990 } while (pmd++, addr = next, addr != end); 1991 return 0; 1992 } 1993 1994 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, 1995 unsigned long addr, unsigned long end, 1996 unsigned long pfn, pgprot_t prot) 1997 { 1998 pud_t *pud; 1999 unsigned long next; 2000 2001 pfn -= addr >> PAGE_SHIFT; 2002 pud = pud_alloc(mm, p4d, addr); 2003 if (!pud) 2004 return -ENOMEM; 2005 do { 2006 next = pud_addr_end(addr, end); 2007 if (remap_pmd_range(mm, pud, addr, next, 2008 pfn + (addr >> PAGE_SHIFT), prot)) 2009 return -ENOMEM; 2010 } while (pud++, addr = next, addr != end); 2011 return 0; 2012 } 2013 2014 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2015 unsigned long addr, unsigned long end, 2016 unsigned long pfn, pgprot_t prot) 2017 { 2018 p4d_t *p4d; 2019 unsigned long next; 2020 2021 pfn -= addr >> PAGE_SHIFT; 2022 p4d = p4d_alloc(mm, pgd, addr); 2023 if (!p4d) 2024 return -ENOMEM; 2025 do { 2026 next = p4d_addr_end(addr, end); 2027 if (remap_pud_range(mm, p4d, addr, next, 2028 pfn + (addr >> PAGE_SHIFT), prot)) 2029 return -ENOMEM; 2030 } while (p4d++, addr = next, addr != end); 2031 return 0; 2032 } 2033 2034 /** 2035 * remap_pfn_range - remap kernel memory to userspace 2036 * @vma: user vma to map to 2037 * @addr: target user address to start at 2038 * @pfn: physical address of kernel memory 2039 * @size: size of map area 2040 * @prot: page protection flags for this mapping 2041 * 2042 * Note: this is only safe if the mm semaphore is held when called. 2043 */ 2044 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2045 unsigned long pfn, unsigned long size, pgprot_t prot) 2046 { 2047 pgd_t *pgd; 2048 unsigned long next; 2049 unsigned long end = addr + PAGE_ALIGN(size); 2050 struct mm_struct *mm = vma->vm_mm; 2051 unsigned long remap_pfn = pfn; 2052 int err; 2053 2054 /* 2055 * Physically remapped pages are special. Tell the 2056 * rest of the world about it: 2057 * VM_IO tells people not to look at these pages 2058 * (accesses can have side effects). 2059 * VM_PFNMAP tells the core MM that the base pages are just 2060 * raw PFN mappings, and do not have a "struct page" associated 2061 * with them. 2062 * VM_DONTEXPAND 2063 * Disable vma merging and expanding with mremap(). 2064 * VM_DONTDUMP 2065 * Omit vma from core dump, even when VM_IO turned off. 2066 * 2067 * There's a horrible special case to handle copy-on-write 2068 * behaviour that some programs depend on. We mark the "original" 2069 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2070 * See vm_normal_page() for details. 2071 */ 2072 if (is_cow_mapping(vma->vm_flags)) { 2073 if (addr != vma->vm_start || end != vma->vm_end) 2074 return -EINVAL; 2075 vma->vm_pgoff = pfn; 2076 } 2077 2078 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size)); 2079 if (err) 2080 return -EINVAL; 2081 2082 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 2083 2084 BUG_ON(addr >= end); 2085 pfn -= addr >> PAGE_SHIFT; 2086 pgd = pgd_offset(mm, addr); 2087 flush_cache_range(vma, addr, end); 2088 do { 2089 next = pgd_addr_end(addr, end); 2090 err = remap_p4d_range(mm, pgd, addr, next, 2091 pfn + (addr >> PAGE_SHIFT), prot); 2092 if (err) 2093 break; 2094 } while (pgd++, addr = next, addr != end); 2095 2096 if (err) 2097 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size)); 2098 2099 return err; 2100 } 2101 EXPORT_SYMBOL(remap_pfn_range); 2102 2103 /** 2104 * vm_iomap_memory - remap memory to userspace 2105 * @vma: user vma to map to 2106 * @start: start of area 2107 * @len: size of area 2108 * 2109 * This is a simplified io_remap_pfn_range() for common driver use. The 2110 * driver just needs to give us the physical memory range to be mapped, 2111 * we'll figure out the rest from the vma information. 2112 * 2113 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 2114 * whatever write-combining details or similar. 2115 */ 2116 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 2117 { 2118 unsigned long vm_len, pfn, pages; 2119 2120 /* Check that the physical memory area passed in looks valid */ 2121 if (start + len < start) 2122 return -EINVAL; 2123 /* 2124 * You *really* shouldn't map things that aren't page-aligned, 2125 * but we've historically allowed it because IO memory might 2126 * just have smaller alignment. 2127 */ 2128 len += start & ~PAGE_MASK; 2129 pfn = start >> PAGE_SHIFT; 2130 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 2131 if (pfn + pages < pfn) 2132 return -EINVAL; 2133 2134 /* We start the mapping 'vm_pgoff' pages into the area */ 2135 if (vma->vm_pgoff > pages) 2136 return -EINVAL; 2137 pfn += vma->vm_pgoff; 2138 pages -= vma->vm_pgoff; 2139 2140 /* Can we fit all of the mapping? */ 2141 vm_len = vma->vm_end - vma->vm_start; 2142 if (vm_len >> PAGE_SHIFT > pages) 2143 return -EINVAL; 2144 2145 /* Ok, let it rip */ 2146 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 2147 } 2148 EXPORT_SYMBOL(vm_iomap_memory); 2149 2150 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2151 unsigned long addr, unsigned long end, 2152 pte_fn_t fn, void *data) 2153 { 2154 pte_t *pte; 2155 int err; 2156 pgtable_t token; 2157 spinlock_t *uninitialized_var(ptl); 2158 2159 pte = (mm == &init_mm) ? 2160 pte_alloc_kernel(pmd, addr) : 2161 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2162 if (!pte) 2163 return -ENOMEM; 2164 2165 BUG_ON(pmd_huge(*pmd)); 2166 2167 arch_enter_lazy_mmu_mode(); 2168 2169 token = pmd_pgtable(*pmd); 2170 2171 do { 2172 err = fn(pte++, token, addr, data); 2173 if (err) 2174 break; 2175 } while (addr += PAGE_SIZE, addr != end); 2176 2177 arch_leave_lazy_mmu_mode(); 2178 2179 if (mm != &init_mm) 2180 pte_unmap_unlock(pte-1, ptl); 2181 return err; 2182 } 2183 2184 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2185 unsigned long addr, unsigned long end, 2186 pte_fn_t fn, void *data) 2187 { 2188 pmd_t *pmd; 2189 unsigned long next; 2190 int err; 2191 2192 BUG_ON(pud_huge(*pud)); 2193 2194 pmd = pmd_alloc(mm, pud, addr); 2195 if (!pmd) 2196 return -ENOMEM; 2197 do { 2198 next = pmd_addr_end(addr, end); 2199 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2200 if (err) 2201 break; 2202 } while (pmd++, addr = next, addr != end); 2203 return err; 2204 } 2205 2206 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, 2207 unsigned long addr, unsigned long end, 2208 pte_fn_t fn, void *data) 2209 { 2210 pud_t *pud; 2211 unsigned long next; 2212 int err; 2213 2214 pud = pud_alloc(mm, p4d, addr); 2215 if (!pud) 2216 return -ENOMEM; 2217 do { 2218 next = pud_addr_end(addr, end); 2219 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2220 if (err) 2221 break; 2222 } while (pud++, addr = next, addr != end); 2223 return err; 2224 } 2225 2226 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2227 unsigned long addr, unsigned long end, 2228 pte_fn_t fn, void *data) 2229 { 2230 p4d_t *p4d; 2231 unsigned long next; 2232 int err; 2233 2234 p4d = p4d_alloc(mm, pgd, addr); 2235 if (!p4d) 2236 return -ENOMEM; 2237 do { 2238 next = p4d_addr_end(addr, end); 2239 err = apply_to_pud_range(mm, p4d, addr, next, fn, data); 2240 if (err) 2241 break; 2242 } while (p4d++, addr = next, addr != end); 2243 return err; 2244 } 2245 2246 /* 2247 * Scan a region of virtual memory, filling in page tables as necessary 2248 * and calling a provided function on each leaf page table. 2249 */ 2250 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2251 unsigned long size, pte_fn_t fn, void *data) 2252 { 2253 pgd_t *pgd; 2254 unsigned long next; 2255 unsigned long end = addr + size; 2256 int err; 2257 2258 if (WARN_ON(addr >= end)) 2259 return -EINVAL; 2260 2261 pgd = pgd_offset(mm, addr); 2262 do { 2263 next = pgd_addr_end(addr, end); 2264 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data); 2265 if (err) 2266 break; 2267 } while (pgd++, addr = next, addr != end); 2268 2269 return err; 2270 } 2271 EXPORT_SYMBOL_GPL(apply_to_page_range); 2272 2273 /* 2274 * handle_pte_fault chooses page fault handler according to an entry which was 2275 * read non-atomically. Before making any commitment, on those architectures 2276 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched 2277 * parts, do_swap_page must check under lock before unmapping the pte and 2278 * proceeding (but do_wp_page is only called after already making such a check; 2279 * and do_anonymous_page can safely check later on). 2280 */ 2281 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2282 pte_t *page_table, pte_t orig_pte) 2283 { 2284 int same = 1; 2285 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2286 if (sizeof(pte_t) > sizeof(unsigned long)) { 2287 spinlock_t *ptl = pte_lockptr(mm, pmd); 2288 spin_lock(ptl); 2289 same = pte_same(*page_table, orig_pte); 2290 spin_unlock(ptl); 2291 } 2292 #endif 2293 pte_unmap(page_table); 2294 return same; 2295 } 2296 2297 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2298 { 2299 debug_dma_assert_idle(src); 2300 2301 /* 2302 * If the source page was a PFN mapping, we don't have 2303 * a "struct page" for it. We do a best-effort copy by 2304 * just copying from the original user address. If that 2305 * fails, we just zero-fill it. Live with it. 2306 */ 2307 if (unlikely(!src)) { 2308 void *kaddr = kmap_atomic(dst); 2309 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2310 2311 /* 2312 * This really shouldn't fail, because the page is there 2313 * in the page tables. But it might just be unreadable, 2314 * in which case we just give up and fill the result with 2315 * zeroes. 2316 */ 2317 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2318 clear_page(kaddr); 2319 kunmap_atomic(kaddr); 2320 flush_dcache_page(dst); 2321 } else 2322 copy_user_highpage(dst, src, va, vma); 2323 } 2324 2325 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) 2326 { 2327 struct file *vm_file = vma->vm_file; 2328 2329 if (vm_file) 2330 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; 2331 2332 /* 2333 * Special mappings (e.g. VDSO) do not have any file so fake 2334 * a default GFP_KERNEL for them. 2335 */ 2336 return GFP_KERNEL; 2337 } 2338 2339 /* 2340 * Notify the address space that the page is about to become writable so that 2341 * it can prohibit this or wait for the page to get into an appropriate state. 2342 * 2343 * We do this without the lock held, so that it can sleep if it needs to. 2344 */ 2345 static int do_page_mkwrite(struct vm_fault *vmf) 2346 { 2347 int ret; 2348 struct page *page = vmf->page; 2349 unsigned int old_flags = vmf->flags; 2350 2351 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2352 2353 ret = vmf->vma->vm_ops->page_mkwrite(vmf); 2354 /* Restore original flags so that caller is not surprised */ 2355 vmf->flags = old_flags; 2356 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2357 return ret; 2358 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2359 lock_page(page); 2360 if (!page->mapping) { 2361 unlock_page(page); 2362 return 0; /* retry */ 2363 } 2364 ret |= VM_FAULT_LOCKED; 2365 } else 2366 VM_BUG_ON_PAGE(!PageLocked(page), page); 2367 return ret; 2368 } 2369 2370 /* 2371 * Handle dirtying of a page in shared file mapping on a write fault. 2372 * 2373 * The function expects the page to be locked and unlocks it. 2374 */ 2375 static void fault_dirty_shared_page(struct vm_area_struct *vma, 2376 struct page *page) 2377 { 2378 struct address_space *mapping; 2379 bool dirtied; 2380 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; 2381 2382 dirtied = set_page_dirty(page); 2383 VM_BUG_ON_PAGE(PageAnon(page), page); 2384 /* 2385 * Take a local copy of the address_space - page.mapping may be zeroed 2386 * by truncate after unlock_page(). The address_space itself remains 2387 * pinned by vma->vm_file's reference. We rely on unlock_page()'s 2388 * release semantics to prevent the compiler from undoing this copying. 2389 */ 2390 mapping = page_rmapping(page); 2391 unlock_page(page); 2392 2393 if ((dirtied || page_mkwrite) && mapping) { 2394 /* 2395 * Some device drivers do not set page.mapping 2396 * but still dirty their pages 2397 */ 2398 balance_dirty_pages_ratelimited(mapping); 2399 } 2400 2401 if (!page_mkwrite) 2402 file_update_time(vma->vm_file); 2403 } 2404 2405 /* 2406 * Handle write page faults for pages that can be reused in the current vma 2407 * 2408 * This can happen either due to the mapping being with the VM_SHARED flag, 2409 * or due to us being the last reference standing to the page. In either 2410 * case, all we need to do here is to mark the page as writable and update 2411 * any related book-keeping. 2412 */ 2413 static inline void wp_page_reuse(struct vm_fault *vmf) 2414 __releases(vmf->ptl) 2415 { 2416 struct vm_area_struct *vma = vmf->vma; 2417 struct page *page = vmf->page; 2418 pte_t entry; 2419 /* 2420 * Clear the pages cpupid information as the existing 2421 * information potentially belongs to a now completely 2422 * unrelated process. 2423 */ 2424 if (page) 2425 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); 2426 2427 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 2428 entry = pte_mkyoung(vmf->orig_pte); 2429 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2430 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) 2431 update_mmu_cache(vma, vmf->address, vmf->pte); 2432 pte_unmap_unlock(vmf->pte, vmf->ptl); 2433 } 2434 2435 /* 2436 * Handle the case of a page which we actually need to copy to a new page. 2437 * 2438 * Called with mmap_sem locked and the old page referenced, but 2439 * without the ptl held. 2440 * 2441 * High level logic flow: 2442 * 2443 * - Allocate a page, copy the content of the old page to the new one. 2444 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. 2445 * - Take the PTL. If the pte changed, bail out and release the allocated page 2446 * - If the pte is still the way we remember it, update the page table and all 2447 * relevant references. This includes dropping the reference the page-table 2448 * held to the old page, as well as updating the rmap. 2449 * - In any case, unlock the PTL and drop the reference we took to the old page. 2450 */ 2451 static int wp_page_copy(struct vm_fault *vmf) 2452 { 2453 struct vm_area_struct *vma = vmf->vma; 2454 struct mm_struct *mm = vma->vm_mm; 2455 struct page *old_page = vmf->page; 2456 struct page *new_page = NULL; 2457 pte_t entry; 2458 int page_copied = 0; 2459 const unsigned long mmun_start = vmf->address & PAGE_MASK; 2460 const unsigned long mmun_end = mmun_start + PAGE_SIZE; 2461 struct mem_cgroup *memcg; 2462 2463 if (unlikely(anon_vma_prepare(vma))) 2464 goto oom; 2465 2466 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { 2467 new_page = alloc_zeroed_user_highpage_movable(vma, 2468 vmf->address); 2469 if (!new_page) 2470 goto oom; 2471 } else { 2472 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, 2473 vmf->address); 2474 if (!new_page) 2475 goto oom; 2476 cow_user_page(new_page, old_page, vmf->address, vma); 2477 } 2478 2479 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) 2480 goto oom_free_new; 2481 2482 __SetPageUptodate(new_page); 2483 2484 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2485 2486 /* 2487 * Re-check the pte - we dropped the lock 2488 */ 2489 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); 2490 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { 2491 if (old_page) { 2492 if (!PageAnon(old_page)) { 2493 dec_mm_counter_fast(mm, 2494 mm_counter_file(old_page)); 2495 inc_mm_counter_fast(mm, MM_ANONPAGES); 2496 } 2497 } else { 2498 inc_mm_counter_fast(mm, MM_ANONPAGES); 2499 } 2500 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 2501 entry = mk_pte(new_page, vma->vm_page_prot); 2502 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2503 /* 2504 * Clear the pte entry and flush it first, before updating the 2505 * pte with the new entry. This will avoid a race condition 2506 * seen in the presence of one thread doing SMC and another 2507 * thread doing COW. 2508 */ 2509 ptep_clear_flush_notify(vma, vmf->address, vmf->pte); 2510 page_add_new_anon_rmap(new_page, vma, vmf->address, false); 2511 mem_cgroup_commit_charge(new_page, memcg, false, false); 2512 lru_cache_add_active_or_unevictable(new_page, vma); 2513 /* 2514 * We call the notify macro here because, when using secondary 2515 * mmu page tables (such as kvm shadow page tables), we want the 2516 * new page to be mapped directly into the secondary page table. 2517 */ 2518 set_pte_at_notify(mm, vmf->address, vmf->pte, entry); 2519 update_mmu_cache(vma, vmf->address, vmf->pte); 2520 if (old_page) { 2521 /* 2522 * Only after switching the pte to the new page may 2523 * we remove the mapcount here. Otherwise another 2524 * process may come and find the rmap count decremented 2525 * before the pte is switched to the new page, and 2526 * "reuse" the old page writing into it while our pte 2527 * here still points into it and can be read by other 2528 * threads. 2529 * 2530 * The critical issue is to order this 2531 * page_remove_rmap with the ptp_clear_flush above. 2532 * Those stores are ordered by (if nothing else,) 2533 * the barrier present in the atomic_add_negative 2534 * in page_remove_rmap. 2535 * 2536 * Then the TLB flush in ptep_clear_flush ensures that 2537 * no process can access the old page before the 2538 * decremented mapcount is visible. And the old page 2539 * cannot be reused until after the decremented 2540 * mapcount is visible. So transitively, TLBs to 2541 * old page will be flushed before it can be reused. 2542 */ 2543 page_remove_rmap(old_page, false); 2544 } 2545 2546 /* Free the old page.. */ 2547 new_page = old_page; 2548 page_copied = 1; 2549 } else { 2550 mem_cgroup_cancel_charge(new_page, memcg, false); 2551 } 2552 2553 if (new_page) 2554 put_page(new_page); 2555 2556 pte_unmap_unlock(vmf->pte, vmf->ptl); 2557 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2558 if (old_page) { 2559 /* 2560 * Don't let another task, with possibly unlocked vma, 2561 * keep the mlocked page. 2562 */ 2563 if (page_copied && (vma->vm_flags & VM_LOCKED)) { 2564 lock_page(old_page); /* LRU manipulation */ 2565 if (PageMlocked(old_page)) 2566 munlock_vma_page(old_page); 2567 unlock_page(old_page); 2568 } 2569 put_page(old_page); 2570 } 2571 return page_copied ? VM_FAULT_WRITE : 0; 2572 oom_free_new: 2573 put_page(new_page); 2574 oom: 2575 if (old_page) 2576 put_page(old_page); 2577 return VM_FAULT_OOM; 2578 } 2579 2580 /** 2581 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE 2582 * writeable once the page is prepared 2583 * 2584 * @vmf: structure describing the fault 2585 * 2586 * This function handles all that is needed to finish a write page fault in a 2587 * shared mapping due to PTE being read-only once the mapped page is prepared. 2588 * It handles locking of PTE and modifying it. The function returns 2589 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE 2590 * lock. 2591 * 2592 * The function expects the page to be locked or other protection against 2593 * concurrent faults / writeback (such as DAX radix tree locks). 2594 */ 2595 int finish_mkwrite_fault(struct vm_fault *vmf) 2596 { 2597 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); 2598 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, 2599 &vmf->ptl); 2600 /* 2601 * We might have raced with another page fault while we released the 2602 * pte_offset_map_lock. 2603 */ 2604 if (!pte_same(*vmf->pte, vmf->orig_pte)) { 2605 pte_unmap_unlock(vmf->pte, vmf->ptl); 2606 return VM_FAULT_NOPAGE; 2607 } 2608 wp_page_reuse(vmf); 2609 return 0; 2610 } 2611 2612 /* 2613 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED 2614 * mapping 2615 */ 2616 static int wp_pfn_shared(struct vm_fault *vmf) 2617 { 2618 struct vm_area_struct *vma = vmf->vma; 2619 2620 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { 2621 int ret; 2622 2623 pte_unmap_unlock(vmf->pte, vmf->ptl); 2624 vmf->flags |= FAULT_FLAG_MKWRITE; 2625 ret = vma->vm_ops->pfn_mkwrite(vmf); 2626 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) 2627 return ret; 2628 return finish_mkwrite_fault(vmf); 2629 } 2630 wp_page_reuse(vmf); 2631 return VM_FAULT_WRITE; 2632 } 2633 2634 static int wp_page_shared(struct vm_fault *vmf) 2635 __releases(vmf->ptl) 2636 { 2637 struct vm_area_struct *vma = vmf->vma; 2638 2639 get_page(vmf->page); 2640 2641 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2642 int tmp; 2643 2644 pte_unmap_unlock(vmf->pte, vmf->ptl); 2645 tmp = do_page_mkwrite(vmf); 2646 if (unlikely(!tmp || (tmp & 2647 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2648 put_page(vmf->page); 2649 return tmp; 2650 } 2651 tmp = finish_mkwrite_fault(vmf); 2652 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2653 unlock_page(vmf->page); 2654 put_page(vmf->page); 2655 return tmp; 2656 } 2657 } else { 2658 wp_page_reuse(vmf); 2659 lock_page(vmf->page); 2660 } 2661 fault_dirty_shared_page(vma, vmf->page); 2662 put_page(vmf->page); 2663 2664 return VM_FAULT_WRITE; 2665 } 2666 2667 /* 2668 * This routine handles present pages, when users try to write 2669 * to a shared page. It is done by copying the page to a new address 2670 * and decrementing the shared-page counter for the old page. 2671 * 2672 * Note that this routine assumes that the protection checks have been 2673 * done by the caller (the low-level page fault routine in most cases). 2674 * Thus we can safely just mark it writable once we've done any necessary 2675 * COW. 2676 * 2677 * We also mark the page dirty at this point even though the page will 2678 * change only once the write actually happens. This avoids a few races, 2679 * and potentially makes it more efficient. 2680 * 2681 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2682 * but allow concurrent faults), with pte both mapped and locked. 2683 * We return with mmap_sem still held, but pte unmapped and unlocked. 2684 */ 2685 static int do_wp_page(struct vm_fault *vmf) 2686 __releases(vmf->ptl) 2687 { 2688 struct vm_area_struct *vma = vmf->vma; 2689 2690 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); 2691 if (!vmf->page) { 2692 /* 2693 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 2694 * VM_PFNMAP VMA. 2695 * 2696 * We should not cow pages in a shared writeable mapping. 2697 * Just mark the pages writable and/or call ops->pfn_mkwrite. 2698 */ 2699 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2700 (VM_WRITE|VM_SHARED)) 2701 return wp_pfn_shared(vmf); 2702 2703 pte_unmap_unlock(vmf->pte, vmf->ptl); 2704 return wp_page_copy(vmf); 2705 } 2706 2707 /* 2708 * Take out anonymous pages first, anonymous shared vmas are 2709 * not dirty accountable. 2710 */ 2711 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) { 2712 int total_map_swapcount; 2713 if (!trylock_page(vmf->page)) { 2714 get_page(vmf->page); 2715 pte_unmap_unlock(vmf->pte, vmf->ptl); 2716 lock_page(vmf->page); 2717 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 2718 vmf->address, &vmf->ptl); 2719 if (!pte_same(*vmf->pte, vmf->orig_pte)) { 2720 unlock_page(vmf->page); 2721 pte_unmap_unlock(vmf->pte, vmf->ptl); 2722 put_page(vmf->page); 2723 return 0; 2724 } 2725 put_page(vmf->page); 2726 } 2727 if (reuse_swap_page(vmf->page, &total_map_swapcount)) { 2728 if (total_map_swapcount == 1) { 2729 /* 2730 * The page is all ours. Move it to 2731 * our anon_vma so the rmap code will 2732 * not search our parent or siblings. 2733 * Protected against the rmap code by 2734 * the page lock. 2735 */ 2736 page_move_anon_rmap(vmf->page, vma); 2737 } 2738 unlock_page(vmf->page); 2739 wp_page_reuse(vmf); 2740 return VM_FAULT_WRITE; 2741 } 2742 unlock_page(vmf->page); 2743 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2744 (VM_WRITE|VM_SHARED))) { 2745 return wp_page_shared(vmf); 2746 } 2747 2748 /* 2749 * Ok, we need to copy. Oh, well.. 2750 */ 2751 get_page(vmf->page); 2752 2753 pte_unmap_unlock(vmf->pte, vmf->ptl); 2754 return wp_page_copy(vmf); 2755 } 2756 2757 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2758 unsigned long start_addr, unsigned long end_addr, 2759 struct zap_details *details) 2760 { 2761 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2762 } 2763 2764 static inline void unmap_mapping_range_tree(struct rb_root_cached *root, 2765 struct zap_details *details) 2766 { 2767 struct vm_area_struct *vma; 2768 pgoff_t vba, vea, zba, zea; 2769 2770 vma_interval_tree_foreach(vma, root, 2771 details->first_index, details->last_index) { 2772 2773 vba = vma->vm_pgoff; 2774 vea = vba + vma_pages(vma) - 1; 2775 zba = details->first_index; 2776 if (zba < vba) 2777 zba = vba; 2778 zea = details->last_index; 2779 if (zea > vea) 2780 zea = vea; 2781 2782 unmap_mapping_range_vma(vma, 2783 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2784 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2785 details); 2786 } 2787 } 2788 2789 /** 2790 * unmap_mapping_range - unmap the portion of all mmaps in the specified 2791 * address_space corresponding to the specified page range in the underlying 2792 * file. 2793 * 2794 * @mapping: the address space containing mmaps to be unmapped. 2795 * @holebegin: byte in first page to unmap, relative to the start of 2796 * the underlying file. This will be rounded down to a PAGE_SIZE 2797 * boundary. Note that this is different from truncate_pagecache(), which 2798 * must keep the partial page. In contrast, we must get rid of 2799 * partial pages. 2800 * @holelen: size of prospective hole in bytes. This will be rounded 2801 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2802 * end of the file. 2803 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2804 * but 0 when invalidating pagecache, don't throw away private data. 2805 */ 2806 void unmap_mapping_range(struct address_space *mapping, 2807 loff_t const holebegin, loff_t const holelen, int even_cows) 2808 { 2809 struct zap_details details = { }; 2810 pgoff_t hba = holebegin >> PAGE_SHIFT; 2811 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2812 2813 /* Check for overflow. */ 2814 if (sizeof(holelen) > sizeof(hlen)) { 2815 long long holeend = 2816 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2817 if (holeend & ~(long long)ULONG_MAX) 2818 hlen = ULONG_MAX - hba + 1; 2819 } 2820 2821 details.check_mapping = even_cows ? NULL : mapping; 2822 details.first_index = hba; 2823 details.last_index = hba + hlen - 1; 2824 if (details.last_index < details.first_index) 2825 details.last_index = ULONG_MAX; 2826 2827 i_mmap_lock_write(mapping); 2828 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) 2829 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2830 i_mmap_unlock_write(mapping); 2831 } 2832 EXPORT_SYMBOL(unmap_mapping_range); 2833 2834 /* 2835 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2836 * but allow concurrent faults), and pte mapped but not yet locked. 2837 * We return with pte unmapped and unlocked. 2838 * 2839 * We return with the mmap_sem locked or unlocked in the same cases 2840 * as does filemap_fault(). 2841 */ 2842 int do_swap_page(struct vm_fault *vmf) 2843 { 2844 struct vm_area_struct *vma = vmf->vma; 2845 struct page *page = NULL, *swapcache; 2846 struct mem_cgroup *memcg; 2847 struct vma_swap_readahead swap_ra; 2848 swp_entry_t entry; 2849 pte_t pte; 2850 int locked; 2851 int exclusive = 0; 2852 int ret = 0; 2853 bool vma_readahead = swap_use_vma_readahead(); 2854 2855 if (vma_readahead) 2856 page = swap_readahead_detect(vmf, &swap_ra); 2857 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) { 2858 if (page) 2859 put_page(page); 2860 goto out; 2861 } 2862 2863 entry = pte_to_swp_entry(vmf->orig_pte); 2864 if (unlikely(non_swap_entry(entry))) { 2865 if (is_migration_entry(entry)) { 2866 migration_entry_wait(vma->vm_mm, vmf->pmd, 2867 vmf->address); 2868 } else if (is_device_private_entry(entry)) { 2869 /* 2870 * For un-addressable device memory we call the pgmap 2871 * fault handler callback. The callback must migrate 2872 * the page back to some CPU accessible page. 2873 */ 2874 ret = device_private_entry_fault(vma, vmf->address, entry, 2875 vmf->flags, vmf->pmd); 2876 } else if (is_hwpoison_entry(entry)) { 2877 ret = VM_FAULT_HWPOISON; 2878 } else { 2879 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); 2880 ret = VM_FAULT_SIGBUS; 2881 } 2882 goto out; 2883 } 2884 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2885 if (!page) 2886 page = lookup_swap_cache(entry, vma_readahead ? vma : NULL, 2887 vmf->address); 2888 if (!page) { 2889 if (vma_readahead) 2890 page = do_swap_page_readahead(entry, 2891 GFP_HIGHUSER_MOVABLE, vmf, &swap_ra); 2892 else 2893 page = swapin_readahead(entry, 2894 GFP_HIGHUSER_MOVABLE, vma, vmf->address); 2895 if (!page) { 2896 /* 2897 * Back out if somebody else faulted in this pte 2898 * while we released the pte lock. 2899 */ 2900 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 2901 vmf->address, &vmf->ptl); 2902 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) 2903 ret = VM_FAULT_OOM; 2904 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2905 goto unlock; 2906 } 2907 2908 /* Had to read the page from swap area: Major fault */ 2909 ret = VM_FAULT_MAJOR; 2910 count_vm_event(PGMAJFAULT); 2911 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); 2912 } else if (PageHWPoison(page)) { 2913 /* 2914 * hwpoisoned dirty swapcache pages are kept for killing 2915 * owner processes (which may be unknown at hwpoison time) 2916 */ 2917 ret = VM_FAULT_HWPOISON; 2918 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2919 swapcache = page; 2920 goto out_release; 2921 } 2922 2923 swapcache = page; 2924 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags); 2925 2926 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2927 if (!locked) { 2928 ret |= VM_FAULT_RETRY; 2929 goto out_release; 2930 } 2931 2932 /* 2933 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2934 * release the swapcache from under us. The page pin, and pte_same 2935 * test below, are not enough to exclude that. Even if it is still 2936 * swapcache, we need to check that the page's swap has not changed. 2937 */ 2938 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 2939 goto out_page; 2940 2941 page = ksm_might_need_to_copy(page, vma, vmf->address); 2942 if (unlikely(!page)) { 2943 ret = VM_FAULT_OOM; 2944 page = swapcache; 2945 goto out_page; 2946 } 2947 2948 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, 2949 &memcg, false)) { 2950 ret = VM_FAULT_OOM; 2951 goto out_page; 2952 } 2953 2954 /* 2955 * Back out if somebody else already faulted in this pte. 2956 */ 2957 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 2958 &vmf->ptl); 2959 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) 2960 goto out_nomap; 2961 2962 if (unlikely(!PageUptodate(page))) { 2963 ret = VM_FAULT_SIGBUS; 2964 goto out_nomap; 2965 } 2966 2967 /* 2968 * The page isn't present yet, go ahead with the fault. 2969 * 2970 * Be careful about the sequence of operations here. 2971 * To get its accounting right, reuse_swap_page() must be called 2972 * while the page is counted on swap but not yet in mapcount i.e. 2973 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2974 * must be called after the swap_free(), or it will never succeed. 2975 */ 2976 2977 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 2978 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS); 2979 pte = mk_pte(page, vma->vm_page_prot); 2980 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) { 2981 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2982 vmf->flags &= ~FAULT_FLAG_WRITE; 2983 ret |= VM_FAULT_WRITE; 2984 exclusive = RMAP_EXCLUSIVE; 2985 } 2986 flush_icache_page(vma, page); 2987 if (pte_swp_soft_dirty(vmf->orig_pte)) 2988 pte = pte_mksoft_dirty(pte); 2989 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); 2990 vmf->orig_pte = pte; 2991 if (page == swapcache) { 2992 do_page_add_anon_rmap(page, vma, vmf->address, exclusive); 2993 mem_cgroup_commit_charge(page, memcg, true, false); 2994 activate_page(page); 2995 } else { /* ksm created a completely new copy */ 2996 page_add_new_anon_rmap(page, vma, vmf->address, false); 2997 mem_cgroup_commit_charge(page, memcg, false, false); 2998 lru_cache_add_active_or_unevictable(page, vma); 2999 } 3000 3001 swap_free(entry); 3002 if (mem_cgroup_swap_full(page) || 3003 (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3004 try_to_free_swap(page); 3005 unlock_page(page); 3006 if (page != swapcache) { 3007 /* 3008 * Hold the lock to avoid the swap entry to be reused 3009 * until we take the PT lock for the pte_same() check 3010 * (to avoid false positives from pte_same). For 3011 * further safety release the lock after the swap_free 3012 * so that the swap count won't change under a 3013 * parallel locked swapcache. 3014 */ 3015 unlock_page(swapcache); 3016 put_page(swapcache); 3017 } 3018 3019 if (vmf->flags & FAULT_FLAG_WRITE) { 3020 ret |= do_wp_page(vmf); 3021 if (ret & VM_FAULT_ERROR) 3022 ret &= VM_FAULT_ERROR; 3023 goto out; 3024 } 3025 3026 /* No need to invalidate - it was non-present before */ 3027 update_mmu_cache(vma, vmf->address, vmf->pte); 3028 unlock: 3029 pte_unmap_unlock(vmf->pte, vmf->ptl); 3030 out: 3031 return ret; 3032 out_nomap: 3033 mem_cgroup_cancel_charge(page, memcg, false); 3034 pte_unmap_unlock(vmf->pte, vmf->ptl); 3035 out_page: 3036 unlock_page(page); 3037 out_release: 3038 put_page(page); 3039 if (page != swapcache) { 3040 unlock_page(swapcache); 3041 put_page(swapcache); 3042 } 3043 return ret; 3044 } 3045 3046 /* 3047 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3048 * but allow concurrent faults), and pte mapped but not yet locked. 3049 * We return with mmap_sem still held, but pte unmapped and unlocked. 3050 */ 3051 static int do_anonymous_page(struct vm_fault *vmf) 3052 { 3053 struct vm_area_struct *vma = vmf->vma; 3054 struct mem_cgroup *memcg; 3055 struct page *page; 3056 int ret = 0; 3057 pte_t entry; 3058 3059 /* File mapping without ->vm_ops ? */ 3060 if (vma->vm_flags & VM_SHARED) 3061 return VM_FAULT_SIGBUS; 3062 3063 /* 3064 * Use pte_alloc() instead of pte_alloc_map(). We can't run 3065 * pte_offset_map() on pmds where a huge pmd might be created 3066 * from a different thread. 3067 * 3068 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when 3069 * parallel threads are excluded by other means. 3070 * 3071 * Here we only have down_read(mmap_sem). 3072 */ 3073 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address)) 3074 return VM_FAULT_OOM; 3075 3076 /* See the comment in pte_alloc_one_map() */ 3077 if (unlikely(pmd_trans_unstable(vmf->pmd))) 3078 return 0; 3079 3080 /* Use the zero-page for reads */ 3081 if (!(vmf->flags & FAULT_FLAG_WRITE) && 3082 !mm_forbids_zeropage(vma->vm_mm)) { 3083 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), 3084 vma->vm_page_prot)); 3085 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 3086 vmf->address, &vmf->ptl); 3087 if (!pte_none(*vmf->pte)) 3088 goto unlock; 3089 ret = check_stable_address_space(vma->vm_mm); 3090 if (ret) 3091 goto unlock; 3092 /* Deliver the page fault to userland, check inside PT lock */ 3093 if (userfaultfd_missing(vma)) { 3094 pte_unmap_unlock(vmf->pte, vmf->ptl); 3095 return handle_userfault(vmf, VM_UFFD_MISSING); 3096 } 3097 goto setpte; 3098 } 3099 3100 /* Allocate our own private page. */ 3101 if (unlikely(anon_vma_prepare(vma))) 3102 goto oom; 3103 page = alloc_zeroed_user_highpage_movable(vma, vmf->address); 3104 if (!page) 3105 goto oom; 3106 3107 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false)) 3108 goto oom_free_page; 3109 3110 /* 3111 * The memory barrier inside __SetPageUptodate makes sure that 3112 * preceeding stores to the page contents become visible before 3113 * the set_pte_at() write. 3114 */ 3115 __SetPageUptodate(page); 3116 3117 entry = mk_pte(page, vma->vm_page_prot); 3118 if (vma->vm_flags & VM_WRITE) 3119 entry = pte_mkwrite(pte_mkdirty(entry)); 3120 3121 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3122 &vmf->ptl); 3123 if (!pte_none(*vmf->pte)) 3124 goto release; 3125 3126 ret = check_stable_address_space(vma->vm_mm); 3127 if (ret) 3128 goto release; 3129 3130 /* Deliver the page fault to userland, check inside PT lock */ 3131 if (userfaultfd_missing(vma)) { 3132 pte_unmap_unlock(vmf->pte, vmf->ptl); 3133 mem_cgroup_cancel_charge(page, memcg, false); 3134 put_page(page); 3135 return handle_userfault(vmf, VM_UFFD_MISSING); 3136 } 3137 3138 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3139 page_add_new_anon_rmap(page, vma, vmf->address, false); 3140 mem_cgroup_commit_charge(page, memcg, false, false); 3141 lru_cache_add_active_or_unevictable(page, vma); 3142 setpte: 3143 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); 3144 3145 /* No need to invalidate - it was non-present before */ 3146 update_mmu_cache(vma, vmf->address, vmf->pte); 3147 unlock: 3148 pte_unmap_unlock(vmf->pte, vmf->ptl); 3149 return ret; 3150 release: 3151 mem_cgroup_cancel_charge(page, memcg, false); 3152 put_page(page); 3153 goto unlock; 3154 oom_free_page: 3155 put_page(page); 3156 oom: 3157 return VM_FAULT_OOM; 3158 } 3159 3160 /* 3161 * The mmap_sem must have been held on entry, and may have been 3162 * released depending on flags and vma->vm_ops->fault() return value. 3163 * See filemap_fault() and __lock_page_retry(). 3164 */ 3165 static int __do_fault(struct vm_fault *vmf) 3166 { 3167 struct vm_area_struct *vma = vmf->vma; 3168 int ret; 3169 3170 ret = vma->vm_ops->fault(vmf); 3171 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | 3172 VM_FAULT_DONE_COW))) 3173 return ret; 3174 3175 if (unlikely(PageHWPoison(vmf->page))) { 3176 if (ret & VM_FAULT_LOCKED) 3177 unlock_page(vmf->page); 3178 put_page(vmf->page); 3179 vmf->page = NULL; 3180 return VM_FAULT_HWPOISON; 3181 } 3182 3183 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3184 lock_page(vmf->page); 3185 else 3186 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); 3187 3188 return ret; 3189 } 3190 3191 /* 3192 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set. 3193 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check 3194 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly 3195 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output. 3196 */ 3197 static int pmd_devmap_trans_unstable(pmd_t *pmd) 3198 { 3199 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd); 3200 } 3201 3202 static int pte_alloc_one_map(struct vm_fault *vmf) 3203 { 3204 struct vm_area_struct *vma = vmf->vma; 3205 3206 if (!pmd_none(*vmf->pmd)) 3207 goto map_pte; 3208 if (vmf->prealloc_pte) { 3209 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 3210 if (unlikely(!pmd_none(*vmf->pmd))) { 3211 spin_unlock(vmf->ptl); 3212 goto map_pte; 3213 } 3214 3215 atomic_long_inc(&vma->vm_mm->nr_ptes); 3216 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); 3217 spin_unlock(vmf->ptl); 3218 vmf->prealloc_pte = NULL; 3219 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) { 3220 return VM_FAULT_OOM; 3221 } 3222 map_pte: 3223 /* 3224 * If a huge pmd materialized under us just retry later. Use 3225 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of 3226 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge 3227 * under us and then back to pmd_none, as a result of MADV_DONTNEED 3228 * running immediately after a huge pmd fault in a different thread of 3229 * this mm, in turn leading to a misleading pmd_trans_huge() retval. 3230 * All we have to ensure is that it is a regular pmd that we can walk 3231 * with pte_offset_map() and we can do that through an atomic read in 3232 * C, which is what pmd_trans_unstable() provides. 3233 */ 3234 if (pmd_devmap_trans_unstable(vmf->pmd)) 3235 return VM_FAULT_NOPAGE; 3236 3237 /* 3238 * At this point we know that our vmf->pmd points to a page of ptes 3239 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge() 3240 * for the duration of the fault. If a racing MADV_DONTNEED runs and 3241 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still 3242 * be valid and we will re-check to make sure the vmf->pte isn't 3243 * pte_none() under vmf->ptl protection when we return to 3244 * alloc_set_pte(). 3245 */ 3246 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3247 &vmf->ptl); 3248 return 0; 3249 } 3250 3251 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE 3252 3253 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1) 3254 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, 3255 unsigned long haddr) 3256 { 3257 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) != 3258 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK)) 3259 return false; 3260 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) 3261 return false; 3262 return true; 3263 } 3264 3265 static void deposit_prealloc_pte(struct vm_fault *vmf) 3266 { 3267 struct vm_area_struct *vma = vmf->vma; 3268 3269 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); 3270 /* 3271 * We are going to consume the prealloc table, 3272 * count that as nr_ptes. 3273 */ 3274 atomic_long_inc(&vma->vm_mm->nr_ptes); 3275 vmf->prealloc_pte = NULL; 3276 } 3277 3278 static int do_set_pmd(struct vm_fault *vmf, struct page *page) 3279 { 3280 struct vm_area_struct *vma = vmf->vma; 3281 bool write = vmf->flags & FAULT_FLAG_WRITE; 3282 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 3283 pmd_t entry; 3284 int i, ret; 3285 3286 if (!transhuge_vma_suitable(vma, haddr)) 3287 return VM_FAULT_FALLBACK; 3288 3289 ret = VM_FAULT_FALLBACK; 3290 page = compound_head(page); 3291 3292 /* 3293 * Archs like ppc64 need additonal space to store information 3294 * related to pte entry. Use the preallocated table for that. 3295 */ 3296 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { 3297 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address); 3298 if (!vmf->prealloc_pte) 3299 return VM_FAULT_OOM; 3300 smp_wmb(); /* See comment in __pte_alloc() */ 3301 } 3302 3303 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 3304 if (unlikely(!pmd_none(*vmf->pmd))) 3305 goto out; 3306 3307 for (i = 0; i < HPAGE_PMD_NR; i++) 3308 flush_icache_page(vma, page + i); 3309 3310 entry = mk_huge_pmd(page, vma->vm_page_prot); 3311 if (write) 3312 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 3313 3314 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR); 3315 page_add_file_rmap(page, true); 3316 /* 3317 * deposit and withdraw with pmd lock held 3318 */ 3319 if (arch_needs_pgtable_deposit()) 3320 deposit_prealloc_pte(vmf); 3321 3322 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 3323 3324 update_mmu_cache_pmd(vma, haddr, vmf->pmd); 3325 3326 /* fault is handled */ 3327 ret = 0; 3328 count_vm_event(THP_FILE_MAPPED); 3329 out: 3330 spin_unlock(vmf->ptl); 3331 return ret; 3332 } 3333 #else 3334 static int do_set_pmd(struct vm_fault *vmf, struct page *page) 3335 { 3336 BUILD_BUG(); 3337 return 0; 3338 } 3339 #endif 3340 3341 /** 3342 * alloc_set_pte - setup new PTE entry for given page and add reverse page 3343 * mapping. If needed, the fucntion allocates page table or use pre-allocated. 3344 * 3345 * @vmf: fault environment 3346 * @memcg: memcg to charge page (only for private mappings) 3347 * @page: page to map 3348 * 3349 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on 3350 * return. 3351 * 3352 * Target users are page handler itself and implementations of 3353 * vm_ops->map_pages. 3354 */ 3355 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, 3356 struct page *page) 3357 { 3358 struct vm_area_struct *vma = vmf->vma; 3359 bool write = vmf->flags & FAULT_FLAG_WRITE; 3360 pte_t entry; 3361 int ret; 3362 3363 if (pmd_none(*vmf->pmd) && PageTransCompound(page) && 3364 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) { 3365 /* THP on COW? */ 3366 VM_BUG_ON_PAGE(memcg, page); 3367 3368 ret = do_set_pmd(vmf, page); 3369 if (ret != VM_FAULT_FALLBACK) 3370 return ret; 3371 } 3372 3373 if (!vmf->pte) { 3374 ret = pte_alloc_one_map(vmf); 3375 if (ret) 3376 return ret; 3377 } 3378 3379 /* Re-check under ptl */ 3380 if (unlikely(!pte_none(*vmf->pte))) 3381 return VM_FAULT_NOPAGE; 3382 3383 flush_icache_page(vma, page); 3384 entry = mk_pte(page, vma->vm_page_prot); 3385 if (write) 3386 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3387 /* copy-on-write page */ 3388 if (write && !(vma->vm_flags & VM_SHARED)) { 3389 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3390 page_add_new_anon_rmap(page, vma, vmf->address, false); 3391 mem_cgroup_commit_charge(page, memcg, false, false); 3392 lru_cache_add_active_or_unevictable(page, vma); 3393 } else { 3394 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); 3395 page_add_file_rmap(page, false); 3396 } 3397 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); 3398 3399 /* no need to invalidate: a not-present page won't be cached */ 3400 update_mmu_cache(vma, vmf->address, vmf->pte); 3401 3402 return 0; 3403 } 3404 3405 3406 /** 3407 * finish_fault - finish page fault once we have prepared the page to fault 3408 * 3409 * @vmf: structure describing the fault 3410 * 3411 * This function handles all that is needed to finish a page fault once the 3412 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for 3413 * given page, adds reverse page mapping, handles memcg charges and LRU 3414 * addition. The function returns 0 on success, VM_FAULT_ code in case of 3415 * error. 3416 * 3417 * The function expects the page to be locked and on success it consumes a 3418 * reference of a page being mapped (for the PTE which maps it). 3419 */ 3420 int finish_fault(struct vm_fault *vmf) 3421 { 3422 struct page *page; 3423 int ret = 0; 3424 3425 /* Did we COW the page? */ 3426 if ((vmf->flags & FAULT_FLAG_WRITE) && 3427 !(vmf->vma->vm_flags & VM_SHARED)) 3428 page = vmf->cow_page; 3429 else 3430 page = vmf->page; 3431 3432 /* 3433 * check even for read faults because we might have lost our CoWed 3434 * page 3435 */ 3436 if (!(vmf->vma->vm_flags & VM_SHARED)) 3437 ret = check_stable_address_space(vmf->vma->vm_mm); 3438 if (!ret) 3439 ret = alloc_set_pte(vmf, vmf->memcg, page); 3440 if (vmf->pte) 3441 pte_unmap_unlock(vmf->pte, vmf->ptl); 3442 return ret; 3443 } 3444 3445 static unsigned long fault_around_bytes __read_mostly = 3446 rounddown_pow_of_two(65536); 3447 3448 #ifdef CONFIG_DEBUG_FS 3449 static int fault_around_bytes_get(void *data, u64 *val) 3450 { 3451 *val = fault_around_bytes; 3452 return 0; 3453 } 3454 3455 /* 3456 * fault_around_pages() and fault_around_mask() expects fault_around_bytes 3457 * rounded down to nearest page order. It's what do_fault_around() expects to 3458 * see. 3459 */ 3460 static int fault_around_bytes_set(void *data, u64 val) 3461 { 3462 if (val / PAGE_SIZE > PTRS_PER_PTE) 3463 return -EINVAL; 3464 if (val > PAGE_SIZE) 3465 fault_around_bytes = rounddown_pow_of_two(val); 3466 else 3467 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ 3468 return 0; 3469 } 3470 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, 3471 fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); 3472 3473 static int __init fault_around_debugfs(void) 3474 { 3475 void *ret; 3476 3477 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL, 3478 &fault_around_bytes_fops); 3479 if (!ret) 3480 pr_warn("Failed to create fault_around_bytes in debugfs"); 3481 return 0; 3482 } 3483 late_initcall(fault_around_debugfs); 3484 #endif 3485 3486 /* 3487 * do_fault_around() tries to map few pages around the fault address. The hope 3488 * is that the pages will be needed soon and this will lower the number of 3489 * faults to handle. 3490 * 3491 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's 3492 * not ready to be mapped: not up-to-date, locked, etc. 3493 * 3494 * This function is called with the page table lock taken. In the split ptlock 3495 * case the page table lock only protects only those entries which belong to 3496 * the page table corresponding to the fault address. 3497 * 3498 * This function doesn't cross the VMA boundaries, in order to call map_pages() 3499 * only once. 3500 * 3501 * fault_around_pages() defines how many pages we'll try to map. 3502 * do_fault_around() expects it to return a power of two less than or equal to 3503 * PTRS_PER_PTE. 3504 * 3505 * The virtual address of the area that we map is naturally aligned to the 3506 * fault_around_pages() value (and therefore to page order). This way it's 3507 * easier to guarantee that we don't cross page table boundaries. 3508 */ 3509 static int do_fault_around(struct vm_fault *vmf) 3510 { 3511 unsigned long address = vmf->address, nr_pages, mask; 3512 pgoff_t start_pgoff = vmf->pgoff; 3513 pgoff_t end_pgoff; 3514 int off, ret = 0; 3515 3516 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; 3517 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; 3518 3519 vmf->address = max(address & mask, vmf->vma->vm_start); 3520 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 3521 start_pgoff -= off; 3522 3523 /* 3524 * end_pgoff is either end of page table or end of vma 3525 * or fault_around_pages() from start_pgoff, depending what is nearest. 3526 */ 3527 end_pgoff = start_pgoff - 3528 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 3529 PTRS_PER_PTE - 1; 3530 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1, 3531 start_pgoff + nr_pages - 1); 3532 3533 if (pmd_none(*vmf->pmd)) { 3534 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm, 3535 vmf->address); 3536 if (!vmf->prealloc_pte) 3537 goto out; 3538 smp_wmb(); /* See comment in __pte_alloc() */ 3539 } 3540 3541 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); 3542 3543 /* Huge page is mapped? Page fault is solved */ 3544 if (pmd_trans_huge(*vmf->pmd)) { 3545 ret = VM_FAULT_NOPAGE; 3546 goto out; 3547 } 3548 3549 /* ->map_pages() haven't done anything useful. Cold page cache? */ 3550 if (!vmf->pte) 3551 goto out; 3552 3553 /* check if the page fault is solved */ 3554 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT); 3555 if (!pte_none(*vmf->pte)) 3556 ret = VM_FAULT_NOPAGE; 3557 pte_unmap_unlock(vmf->pte, vmf->ptl); 3558 out: 3559 vmf->address = address; 3560 vmf->pte = NULL; 3561 return ret; 3562 } 3563 3564 static int do_read_fault(struct vm_fault *vmf) 3565 { 3566 struct vm_area_struct *vma = vmf->vma; 3567 int ret = 0; 3568 3569 /* 3570 * Let's call ->map_pages() first and use ->fault() as fallback 3571 * if page by the offset is not ready to be mapped (cold cache or 3572 * something). 3573 */ 3574 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { 3575 ret = do_fault_around(vmf); 3576 if (ret) 3577 return ret; 3578 } 3579 3580 ret = __do_fault(vmf); 3581 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3582 return ret; 3583 3584 ret |= finish_fault(vmf); 3585 unlock_page(vmf->page); 3586 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3587 put_page(vmf->page); 3588 return ret; 3589 } 3590 3591 static int do_cow_fault(struct vm_fault *vmf) 3592 { 3593 struct vm_area_struct *vma = vmf->vma; 3594 int ret; 3595 3596 if (unlikely(anon_vma_prepare(vma))) 3597 return VM_FAULT_OOM; 3598 3599 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); 3600 if (!vmf->cow_page) 3601 return VM_FAULT_OOM; 3602 3603 if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL, 3604 &vmf->memcg, false)) { 3605 put_page(vmf->cow_page); 3606 return VM_FAULT_OOM; 3607 } 3608 3609 ret = __do_fault(vmf); 3610 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3611 goto uncharge_out; 3612 if (ret & VM_FAULT_DONE_COW) 3613 return ret; 3614 3615 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); 3616 __SetPageUptodate(vmf->cow_page); 3617 3618 ret |= finish_fault(vmf); 3619 unlock_page(vmf->page); 3620 put_page(vmf->page); 3621 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3622 goto uncharge_out; 3623 return ret; 3624 uncharge_out: 3625 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false); 3626 put_page(vmf->cow_page); 3627 return ret; 3628 } 3629 3630 static int do_shared_fault(struct vm_fault *vmf) 3631 { 3632 struct vm_area_struct *vma = vmf->vma; 3633 int ret, tmp; 3634 3635 ret = __do_fault(vmf); 3636 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3637 return ret; 3638 3639 /* 3640 * Check if the backing address space wants to know that the page is 3641 * about to become writable 3642 */ 3643 if (vma->vm_ops->page_mkwrite) { 3644 unlock_page(vmf->page); 3645 tmp = do_page_mkwrite(vmf); 3646 if (unlikely(!tmp || 3647 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 3648 put_page(vmf->page); 3649 return tmp; 3650 } 3651 } 3652 3653 ret |= finish_fault(vmf); 3654 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 3655 VM_FAULT_RETRY))) { 3656 unlock_page(vmf->page); 3657 put_page(vmf->page); 3658 return ret; 3659 } 3660 3661 fault_dirty_shared_page(vma, vmf->page); 3662 return ret; 3663 } 3664 3665 /* 3666 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3667 * but allow concurrent faults). 3668 * The mmap_sem may have been released depending on flags and our 3669 * return value. See filemap_fault() and __lock_page_or_retry(). 3670 */ 3671 static int do_fault(struct vm_fault *vmf) 3672 { 3673 struct vm_area_struct *vma = vmf->vma; 3674 int ret; 3675 3676 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */ 3677 if (!vma->vm_ops->fault) 3678 ret = VM_FAULT_SIGBUS; 3679 else if (!(vmf->flags & FAULT_FLAG_WRITE)) 3680 ret = do_read_fault(vmf); 3681 else if (!(vma->vm_flags & VM_SHARED)) 3682 ret = do_cow_fault(vmf); 3683 else 3684 ret = do_shared_fault(vmf); 3685 3686 /* preallocated pagetable is unused: free it */ 3687 if (vmf->prealloc_pte) { 3688 pte_free(vma->vm_mm, vmf->prealloc_pte); 3689 vmf->prealloc_pte = NULL; 3690 } 3691 return ret; 3692 } 3693 3694 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3695 unsigned long addr, int page_nid, 3696 int *flags) 3697 { 3698 get_page(page); 3699 3700 count_vm_numa_event(NUMA_HINT_FAULTS); 3701 if (page_nid == numa_node_id()) { 3702 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3703 *flags |= TNF_FAULT_LOCAL; 3704 } 3705 3706 return mpol_misplaced(page, vma, addr); 3707 } 3708 3709 static int do_numa_page(struct vm_fault *vmf) 3710 { 3711 struct vm_area_struct *vma = vmf->vma; 3712 struct page *page = NULL; 3713 int page_nid = -1; 3714 int last_cpupid; 3715 int target_nid; 3716 bool migrated = false; 3717 pte_t pte; 3718 bool was_writable = pte_savedwrite(vmf->orig_pte); 3719 int flags = 0; 3720 3721 /* 3722 * The "pte" at this point cannot be used safely without 3723 * validation through pte_unmap_same(). It's of NUMA type but 3724 * the pfn may be screwed if the read is non atomic. 3725 */ 3726 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); 3727 spin_lock(vmf->ptl); 3728 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { 3729 pte_unmap_unlock(vmf->pte, vmf->ptl); 3730 goto out; 3731 } 3732 3733 /* 3734 * Make it present again, Depending on how arch implementes non 3735 * accessible ptes, some can allow access by kernel mode. 3736 */ 3737 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte); 3738 pte = pte_modify(pte, vma->vm_page_prot); 3739 pte = pte_mkyoung(pte); 3740 if (was_writable) 3741 pte = pte_mkwrite(pte); 3742 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte); 3743 update_mmu_cache(vma, vmf->address, vmf->pte); 3744 3745 page = vm_normal_page(vma, vmf->address, pte); 3746 if (!page) { 3747 pte_unmap_unlock(vmf->pte, vmf->ptl); 3748 return 0; 3749 } 3750 3751 /* TODO: handle PTE-mapped THP */ 3752 if (PageCompound(page)) { 3753 pte_unmap_unlock(vmf->pte, vmf->ptl); 3754 return 0; 3755 } 3756 3757 /* 3758 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as 3759 * much anyway since they can be in shared cache state. This misses 3760 * the case where a mapping is writable but the process never writes 3761 * to it but pte_write gets cleared during protection updates and 3762 * pte_dirty has unpredictable behaviour between PTE scan updates, 3763 * background writeback, dirty balancing and application behaviour. 3764 */ 3765 if (!pte_write(pte)) 3766 flags |= TNF_NO_GROUP; 3767 3768 /* 3769 * Flag if the page is shared between multiple address spaces. This 3770 * is later used when determining whether to group tasks together 3771 */ 3772 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 3773 flags |= TNF_SHARED; 3774 3775 last_cpupid = page_cpupid_last(page); 3776 page_nid = page_to_nid(page); 3777 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid, 3778 &flags); 3779 pte_unmap_unlock(vmf->pte, vmf->ptl); 3780 if (target_nid == -1) { 3781 put_page(page); 3782 goto out; 3783 } 3784 3785 /* Migrate to the requested node */ 3786 migrated = migrate_misplaced_page(page, vma, target_nid); 3787 if (migrated) { 3788 page_nid = target_nid; 3789 flags |= TNF_MIGRATED; 3790 } else 3791 flags |= TNF_MIGRATE_FAIL; 3792 3793 out: 3794 if (page_nid != -1) 3795 task_numa_fault(last_cpupid, page_nid, 1, flags); 3796 return 0; 3797 } 3798 3799 static inline int create_huge_pmd(struct vm_fault *vmf) 3800 { 3801 if (vma_is_anonymous(vmf->vma)) 3802 return do_huge_pmd_anonymous_page(vmf); 3803 if (vmf->vma->vm_ops->huge_fault) 3804 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 3805 return VM_FAULT_FALLBACK; 3806 } 3807 3808 static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd) 3809 { 3810 if (vma_is_anonymous(vmf->vma)) 3811 return do_huge_pmd_wp_page(vmf, orig_pmd); 3812 if (vmf->vma->vm_ops->huge_fault) 3813 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 3814 3815 /* COW handled on pte level: split pmd */ 3816 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma); 3817 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL); 3818 3819 return VM_FAULT_FALLBACK; 3820 } 3821 3822 static inline bool vma_is_accessible(struct vm_area_struct *vma) 3823 { 3824 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE); 3825 } 3826 3827 static int create_huge_pud(struct vm_fault *vmf) 3828 { 3829 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3830 /* No support for anonymous transparent PUD pages yet */ 3831 if (vma_is_anonymous(vmf->vma)) 3832 return VM_FAULT_FALLBACK; 3833 if (vmf->vma->vm_ops->huge_fault) 3834 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 3835 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 3836 return VM_FAULT_FALLBACK; 3837 } 3838 3839 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) 3840 { 3841 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3842 /* No support for anonymous transparent PUD pages yet */ 3843 if (vma_is_anonymous(vmf->vma)) 3844 return VM_FAULT_FALLBACK; 3845 if (vmf->vma->vm_ops->huge_fault) 3846 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 3847 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 3848 return VM_FAULT_FALLBACK; 3849 } 3850 3851 /* 3852 * These routines also need to handle stuff like marking pages dirty 3853 * and/or accessed for architectures that don't do it in hardware (most 3854 * RISC architectures). The early dirtying is also good on the i386. 3855 * 3856 * There is also a hook called "update_mmu_cache()" that architectures 3857 * with external mmu caches can use to update those (ie the Sparc or 3858 * PowerPC hashed page tables that act as extended TLBs). 3859 * 3860 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow 3861 * concurrent faults). 3862 * 3863 * The mmap_sem may have been released depending on flags and our return value. 3864 * See filemap_fault() and __lock_page_or_retry(). 3865 */ 3866 static int handle_pte_fault(struct vm_fault *vmf) 3867 { 3868 pte_t entry; 3869 3870 if (unlikely(pmd_none(*vmf->pmd))) { 3871 /* 3872 * Leave __pte_alloc() until later: because vm_ops->fault may 3873 * want to allocate huge page, and if we expose page table 3874 * for an instant, it will be difficult to retract from 3875 * concurrent faults and from rmap lookups. 3876 */ 3877 vmf->pte = NULL; 3878 } else { 3879 /* See comment in pte_alloc_one_map() */ 3880 if (pmd_devmap_trans_unstable(vmf->pmd)) 3881 return 0; 3882 /* 3883 * A regular pmd is established and it can't morph into a huge 3884 * pmd from under us anymore at this point because we hold the 3885 * mmap_sem read mode and khugepaged takes it in write mode. 3886 * So now it's safe to run pte_offset_map(). 3887 */ 3888 vmf->pte = pte_offset_map(vmf->pmd, vmf->address); 3889 vmf->orig_pte = *vmf->pte; 3890 3891 /* 3892 * some architectures can have larger ptes than wordsize, 3893 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and 3894 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic 3895 * accesses. The code below just needs a consistent view 3896 * for the ifs and we later double check anyway with the 3897 * ptl lock held. So here a barrier will do. 3898 */ 3899 barrier(); 3900 if (pte_none(vmf->orig_pte)) { 3901 pte_unmap(vmf->pte); 3902 vmf->pte = NULL; 3903 } 3904 } 3905 3906 if (!vmf->pte) { 3907 if (vma_is_anonymous(vmf->vma)) 3908 return do_anonymous_page(vmf); 3909 else 3910 return do_fault(vmf); 3911 } 3912 3913 if (!pte_present(vmf->orig_pte)) 3914 return do_swap_page(vmf); 3915 3916 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) 3917 return do_numa_page(vmf); 3918 3919 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); 3920 spin_lock(vmf->ptl); 3921 entry = vmf->orig_pte; 3922 if (unlikely(!pte_same(*vmf->pte, entry))) 3923 goto unlock; 3924 if (vmf->flags & FAULT_FLAG_WRITE) { 3925 if (!pte_write(entry)) 3926 return do_wp_page(vmf); 3927 entry = pte_mkdirty(entry); 3928 } 3929 entry = pte_mkyoung(entry); 3930 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, 3931 vmf->flags & FAULT_FLAG_WRITE)) { 3932 update_mmu_cache(vmf->vma, vmf->address, vmf->pte); 3933 } else { 3934 /* 3935 * This is needed only for protection faults but the arch code 3936 * is not yet telling us if this is a protection fault or not. 3937 * This still avoids useless tlb flushes for .text page faults 3938 * with threads. 3939 */ 3940 if (vmf->flags & FAULT_FLAG_WRITE) 3941 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address); 3942 } 3943 unlock: 3944 pte_unmap_unlock(vmf->pte, vmf->ptl); 3945 return 0; 3946 } 3947 3948 /* 3949 * By the time we get here, we already hold the mm semaphore 3950 * 3951 * The mmap_sem may have been released depending on flags and our 3952 * return value. See filemap_fault() and __lock_page_or_retry(). 3953 */ 3954 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 3955 unsigned int flags) 3956 { 3957 struct vm_fault vmf = { 3958 .vma = vma, 3959 .address = address & PAGE_MASK, 3960 .flags = flags, 3961 .pgoff = linear_page_index(vma, address), 3962 .gfp_mask = __get_fault_gfp_mask(vma), 3963 }; 3964 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3965 struct mm_struct *mm = vma->vm_mm; 3966 pgd_t *pgd; 3967 p4d_t *p4d; 3968 int ret; 3969 3970 pgd = pgd_offset(mm, address); 3971 p4d = p4d_alloc(mm, pgd, address); 3972 if (!p4d) 3973 return VM_FAULT_OOM; 3974 3975 vmf.pud = pud_alloc(mm, p4d, address); 3976 if (!vmf.pud) 3977 return VM_FAULT_OOM; 3978 if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) { 3979 ret = create_huge_pud(&vmf); 3980 if (!(ret & VM_FAULT_FALLBACK)) 3981 return ret; 3982 } else { 3983 pud_t orig_pud = *vmf.pud; 3984 3985 barrier(); 3986 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { 3987 3988 /* NUMA case for anonymous PUDs would go here */ 3989 3990 if (dirty && !pud_write(orig_pud)) { 3991 ret = wp_huge_pud(&vmf, orig_pud); 3992 if (!(ret & VM_FAULT_FALLBACK)) 3993 return ret; 3994 } else { 3995 huge_pud_set_accessed(&vmf, orig_pud); 3996 return 0; 3997 } 3998 } 3999 } 4000 4001 vmf.pmd = pmd_alloc(mm, vmf.pud, address); 4002 if (!vmf.pmd) 4003 return VM_FAULT_OOM; 4004 if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) { 4005 ret = create_huge_pmd(&vmf); 4006 if (!(ret & VM_FAULT_FALLBACK)) 4007 return ret; 4008 } else { 4009 pmd_t orig_pmd = *vmf.pmd; 4010 4011 barrier(); 4012 if (unlikely(is_swap_pmd(orig_pmd))) { 4013 VM_BUG_ON(thp_migration_supported() && 4014 !is_pmd_migration_entry(orig_pmd)); 4015 if (is_pmd_migration_entry(orig_pmd)) 4016 pmd_migration_entry_wait(mm, vmf.pmd); 4017 return 0; 4018 } 4019 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) { 4020 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma)) 4021 return do_huge_pmd_numa_page(&vmf, orig_pmd); 4022 4023 if (dirty && !pmd_write(orig_pmd)) { 4024 ret = wp_huge_pmd(&vmf, orig_pmd); 4025 if (!(ret & VM_FAULT_FALLBACK)) 4026 return ret; 4027 } else { 4028 huge_pmd_set_accessed(&vmf, orig_pmd); 4029 return 0; 4030 } 4031 } 4032 } 4033 4034 return handle_pte_fault(&vmf); 4035 } 4036 4037 /* 4038 * By the time we get here, we already hold the mm semaphore 4039 * 4040 * The mmap_sem may have been released depending on flags and our 4041 * return value. See filemap_fault() and __lock_page_or_retry(). 4042 */ 4043 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 4044 unsigned int flags) 4045 { 4046 int ret; 4047 4048 __set_current_state(TASK_RUNNING); 4049 4050 count_vm_event(PGFAULT); 4051 count_memcg_event_mm(vma->vm_mm, PGFAULT); 4052 4053 /* do counter updates before entering really critical section. */ 4054 check_sync_rss_stat(current); 4055 4056 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, 4057 flags & FAULT_FLAG_INSTRUCTION, 4058 flags & FAULT_FLAG_REMOTE)) 4059 return VM_FAULT_SIGSEGV; 4060 4061 /* 4062 * Enable the memcg OOM handling for faults triggered in user 4063 * space. Kernel faults are handled more gracefully. 4064 */ 4065 if (flags & FAULT_FLAG_USER) 4066 mem_cgroup_oom_enable(); 4067 4068 if (unlikely(is_vm_hugetlb_page(vma))) 4069 ret = hugetlb_fault(vma->vm_mm, vma, address, flags); 4070 else 4071 ret = __handle_mm_fault(vma, address, flags); 4072 4073 if (flags & FAULT_FLAG_USER) { 4074 mem_cgroup_oom_disable(); 4075 /* 4076 * The task may have entered a memcg OOM situation but 4077 * if the allocation error was handled gracefully (no 4078 * VM_FAULT_OOM), there is no need to kill anything. 4079 * Just clean up the OOM state peacefully. 4080 */ 4081 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 4082 mem_cgroup_oom_synchronize(false); 4083 } 4084 4085 return ret; 4086 } 4087 EXPORT_SYMBOL_GPL(handle_mm_fault); 4088 4089 #ifndef __PAGETABLE_P4D_FOLDED 4090 /* 4091 * Allocate p4d page table. 4092 * We've already handled the fast-path in-line. 4093 */ 4094 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 4095 { 4096 p4d_t *new = p4d_alloc_one(mm, address); 4097 if (!new) 4098 return -ENOMEM; 4099 4100 smp_wmb(); /* See comment in __pte_alloc */ 4101 4102 spin_lock(&mm->page_table_lock); 4103 if (pgd_present(*pgd)) /* Another has populated it */ 4104 p4d_free(mm, new); 4105 else 4106 pgd_populate(mm, pgd, new); 4107 spin_unlock(&mm->page_table_lock); 4108 return 0; 4109 } 4110 #endif /* __PAGETABLE_P4D_FOLDED */ 4111 4112 #ifndef __PAGETABLE_PUD_FOLDED 4113 /* 4114 * Allocate page upper directory. 4115 * We've already handled the fast-path in-line. 4116 */ 4117 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) 4118 { 4119 pud_t *new = pud_alloc_one(mm, address); 4120 if (!new) 4121 return -ENOMEM; 4122 4123 smp_wmb(); /* See comment in __pte_alloc */ 4124 4125 spin_lock(&mm->page_table_lock); 4126 #ifndef __ARCH_HAS_5LEVEL_HACK 4127 if (p4d_present(*p4d)) /* Another has populated it */ 4128 pud_free(mm, new); 4129 else 4130 p4d_populate(mm, p4d, new); 4131 #else 4132 if (pgd_present(*p4d)) /* Another has populated it */ 4133 pud_free(mm, new); 4134 else 4135 pgd_populate(mm, p4d, new); 4136 #endif /* __ARCH_HAS_5LEVEL_HACK */ 4137 spin_unlock(&mm->page_table_lock); 4138 return 0; 4139 } 4140 #endif /* __PAGETABLE_PUD_FOLDED */ 4141 4142 #ifndef __PAGETABLE_PMD_FOLDED 4143 /* 4144 * Allocate page middle directory. 4145 * We've already handled the fast-path in-line. 4146 */ 4147 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 4148 { 4149 spinlock_t *ptl; 4150 pmd_t *new = pmd_alloc_one(mm, address); 4151 if (!new) 4152 return -ENOMEM; 4153 4154 smp_wmb(); /* See comment in __pte_alloc */ 4155 4156 ptl = pud_lock(mm, pud); 4157 #ifndef __ARCH_HAS_4LEVEL_HACK 4158 if (!pud_present(*pud)) { 4159 mm_inc_nr_pmds(mm); 4160 pud_populate(mm, pud, new); 4161 } else /* Another has populated it */ 4162 pmd_free(mm, new); 4163 #else 4164 if (!pgd_present(*pud)) { 4165 mm_inc_nr_pmds(mm); 4166 pgd_populate(mm, pud, new); 4167 } else /* Another has populated it */ 4168 pmd_free(mm, new); 4169 #endif /* __ARCH_HAS_4LEVEL_HACK */ 4170 spin_unlock(ptl); 4171 return 0; 4172 } 4173 #endif /* __PAGETABLE_PMD_FOLDED */ 4174 4175 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, 4176 unsigned long *start, unsigned long *end, 4177 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) 4178 { 4179 pgd_t *pgd; 4180 p4d_t *p4d; 4181 pud_t *pud; 4182 pmd_t *pmd; 4183 pte_t *ptep; 4184 4185 pgd = pgd_offset(mm, address); 4186 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 4187 goto out; 4188 4189 p4d = p4d_offset(pgd, address); 4190 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d))) 4191 goto out; 4192 4193 pud = pud_offset(p4d, address); 4194 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 4195 goto out; 4196 4197 pmd = pmd_offset(pud, address); 4198 VM_BUG_ON(pmd_trans_huge(*pmd)); 4199 4200 if (pmd_huge(*pmd)) { 4201 if (!pmdpp) 4202 goto out; 4203 4204 if (start && end) { 4205 *start = address & PMD_MASK; 4206 *end = *start + PMD_SIZE; 4207 mmu_notifier_invalidate_range_start(mm, *start, *end); 4208 } 4209 *ptlp = pmd_lock(mm, pmd); 4210 if (pmd_huge(*pmd)) { 4211 *pmdpp = pmd; 4212 return 0; 4213 } 4214 spin_unlock(*ptlp); 4215 if (start && end) 4216 mmu_notifier_invalidate_range_end(mm, *start, *end); 4217 } 4218 4219 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 4220 goto out; 4221 4222 if (start && end) { 4223 *start = address & PAGE_MASK; 4224 *end = *start + PAGE_SIZE; 4225 mmu_notifier_invalidate_range_start(mm, *start, *end); 4226 } 4227 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 4228 if (!pte_present(*ptep)) 4229 goto unlock; 4230 *ptepp = ptep; 4231 return 0; 4232 unlock: 4233 pte_unmap_unlock(ptep, *ptlp); 4234 if (start && end) 4235 mmu_notifier_invalidate_range_end(mm, *start, *end); 4236 out: 4237 return -EINVAL; 4238 } 4239 4240 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 4241 pte_t **ptepp, spinlock_t **ptlp) 4242 { 4243 int res; 4244 4245 /* (void) is needed to make gcc happy */ 4246 (void) __cond_lock(*ptlp, 4247 !(res = __follow_pte_pmd(mm, address, NULL, NULL, 4248 ptepp, NULL, ptlp))); 4249 return res; 4250 } 4251 4252 int follow_pte_pmd(struct mm_struct *mm, unsigned long address, 4253 unsigned long *start, unsigned long *end, 4254 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) 4255 { 4256 int res; 4257 4258 /* (void) is needed to make gcc happy */ 4259 (void) __cond_lock(*ptlp, 4260 !(res = __follow_pte_pmd(mm, address, start, end, 4261 ptepp, pmdpp, ptlp))); 4262 return res; 4263 } 4264 EXPORT_SYMBOL(follow_pte_pmd); 4265 4266 /** 4267 * follow_pfn - look up PFN at a user virtual address 4268 * @vma: memory mapping 4269 * @address: user virtual address 4270 * @pfn: location to store found PFN 4271 * 4272 * Only IO mappings and raw PFN mappings are allowed. 4273 * 4274 * Returns zero and the pfn at @pfn on success, -ve otherwise. 4275 */ 4276 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 4277 unsigned long *pfn) 4278 { 4279 int ret = -EINVAL; 4280 spinlock_t *ptl; 4281 pte_t *ptep; 4282 4283 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4284 return ret; 4285 4286 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 4287 if (ret) 4288 return ret; 4289 *pfn = pte_pfn(*ptep); 4290 pte_unmap_unlock(ptep, ptl); 4291 return 0; 4292 } 4293 EXPORT_SYMBOL(follow_pfn); 4294 4295 #ifdef CONFIG_HAVE_IOREMAP_PROT 4296 int follow_phys(struct vm_area_struct *vma, 4297 unsigned long address, unsigned int flags, 4298 unsigned long *prot, resource_size_t *phys) 4299 { 4300 int ret = -EINVAL; 4301 pte_t *ptep, pte; 4302 spinlock_t *ptl; 4303 4304 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4305 goto out; 4306 4307 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 4308 goto out; 4309 pte = *ptep; 4310 4311 if ((flags & FOLL_WRITE) && !pte_write(pte)) 4312 goto unlock; 4313 4314 *prot = pgprot_val(pte_pgprot(pte)); 4315 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 4316 4317 ret = 0; 4318 unlock: 4319 pte_unmap_unlock(ptep, ptl); 4320 out: 4321 return ret; 4322 } 4323 4324 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 4325 void *buf, int len, int write) 4326 { 4327 resource_size_t phys_addr; 4328 unsigned long prot = 0; 4329 void __iomem *maddr; 4330 int offset = addr & (PAGE_SIZE-1); 4331 4332 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 4333 return -EINVAL; 4334 4335 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); 4336 if (write) 4337 memcpy_toio(maddr + offset, buf, len); 4338 else 4339 memcpy_fromio(buf, maddr + offset, len); 4340 iounmap(maddr); 4341 4342 return len; 4343 } 4344 EXPORT_SYMBOL_GPL(generic_access_phys); 4345 #endif 4346 4347 /* 4348 * Access another process' address space as given in mm. If non-NULL, use the 4349 * given task for page fault accounting. 4350 */ 4351 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 4352 unsigned long addr, void *buf, int len, unsigned int gup_flags) 4353 { 4354 struct vm_area_struct *vma; 4355 void *old_buf = buf; 4356 int write = gup_flags & FOLL_WRITE; 4357 4358 down_read(&mm->mmap_sem); 4359 /* ignore errors, just check how much was successfully transferred */ 4360 while (len) { 4361 int bytes, ret, offset; 4362 void *maddr; 4363 struct page *page = NULL; 4364 4365 ret = get_user_pages_remote(tsk, mm, addr, 1, 4366 gup_flags, &page, &vma, NULL); 4367 if (ret <= 0) { 4368 #ifndef CONFIG_HAVE_IOREMAP_PROT 4369 break; 4370 #else 4371 /* 4372 * Check if this is a VM_IO | VM_PFNMAP VMA, which 4373 * we can access using slightly different code. 4374 */ 4375 vma = find_vma(mm, addr); 4376 if (!vma || vma->vm_start > addr) 4377 break; 4378 if (vma->vm_ops && vma->vm_ops->access) 4379 ret = vma->vm_ops->access(vma, addr, buf, 4380 len, write); 4381 if (ret <= 0) 4382 break; 4383 bytes = ret; 4384 #endif 4385 } else { 4386 bytes = len; 4387 offset = addr & (PAGE_SIZE-1); 4388 if (bytes > PAGE_SIZE-offset) 4389 bytes = PAGE_SIZE-offset; 4390 4391 maddr = kmap(page); 4392 if (write) { 4393 copy_to_user_page(vma, page, addr, 4394 maddr + offset, buf, bytes); 4395 set_page_dirty_lock(page); 4396 } else { 4397 copy_from_user_page(vma, page, addr, 4398 buf, maddr + offset, bytes); 4399 } 4400 kunmap(page); 4401 put_page(page); 4402 } 4403 len -= bytes; 4404 buf += bytes; 4405 addr += bytes; 4406 } 4407 up_read(&mm->mmap_sem); 4408 4409 return buf - old_buf; 4410 } 4411 4412 /** 4413 * access_remote_vm - access another process' address space 4414 * @mm: the mm_struct of the target address space 4415 * @addr: start address to access 4416 * @buf: source or destination buffer 4417 * @len: number of bytes to transfer 4418 * @gup_flags: flags modifying lookup behaviour 4419 * 4420 * The caller must hold a reference on @mm. 4421 */ 4422 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 4423 void *buf, int len, unsigned int gup_flags) 4424 { 4425 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags); 4426 } 4427 4428 /* 4429 * Access another process' address space. 4430 * Source/target buffer must be kernel space, 4431 * Do not walk the page table directly, use get_user_pages 4432 */ 4433 int access_process_vm(struct task_struct *tsk, unsigned long addr, 4434 void *buf, int len, unsigned int gup_flags) 4435 { 4436 struct mm_struct *mm; 4437 int ret; 4438 4439 mm = get_task_mm(tsk); 4440 if (!mm) 4441 return 0; 4442 4443 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags); 4444 4445 mmput(mm); 4446 4447 return ret; 4448 } 4449 EXPORT_SYMBOL_GPL(access_process_vm); 4450 4451 /* 4452 * Print the name of a VMA. 4453 */ 4454 void print_vma_addr(char *prefix, unsigned long ip) 4455 { 4456 struct mm_struct *mm = current->mm; 4457 struct vm_area_struct *vma; 4458 4459 /* 4460 * Do not print if we are in atomic 4461 * contexts (in exception stacks, etc.): 4462 */ 4463 if (preempt_count()) 4464 return; 4465 4466 down_read(&mm->mmap_sem); 4467 vma = find_vma(mm, ip); 4468 if (vma && vma->vm_file) { 4469 struct file *f = vma->vm_file; 4470 char *buf = (char *)__get_free_page(GFP_KERNEL); 4471 if (buf) { 4472 char *p; 4473 4474 p = file_path(f, buf, PAGE_SIZE); 4475 if (IS_ERR(p)) 4476 p = "?"; 4477 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 4478 vma->vm_start, 4479 vma->vm_end - vma->vm_start); 4480 free_page((unsigned long)buf); 4481 } 4482 } 4483 up_read(&mm->mmap_sem); 4484 } 4485 4486 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 4487 void __might_fault(const char *file, int line) 4488 { 4489 /* 4490 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 4491 * holding the mmap_sem, this is safe because kernel memory doesn't 4492 * get paged out, therefore we'll never actually fault, and the 4493 * below annotations will generate false positives. 4494 */ 4495 if (uaccess_kernel()) 4496 return; 4497 if (pagefault_disabled()) 4498 return; 4499 __might_sleep(file, line, 0); 4500 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) 4501 if (current->mm) 4502 might_lock_read(¤t->mm->mmap_sem); 4503 #endif 4504 } 4505 EXPORT_SYMBOL(__might_fault); 4506 #endif 4507 4508 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 4509 static void clear_gigantic_page(struct page *page, 4510 unsigned long addr, 4511 unsigned int pages_per_huge_page) 4512 { 4513 int i; 4514 struct page *p = page; 4515 4516 might_sleep(); 4517 for (i = 0; i < pages_per_huge_page; 4518 i++, p = mem_map_next(p, page, i)) { 4519 cond_resched(); 4520 clear_user_highpage(p, addr + i * PAGE_SIZE); 4521 } 4522 } 4523 void clear_huge_page(struct page *page, 4524 unsigned long addr_hint, unsigned int pages_per_huge_page) 4525 { 4526 int i, n, base, l; 4527 unsigned long addr = addr_hint & 4528 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); 4529 4530 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4531 clear_gigantic_page(page, addr, pages_per_huge_page); 4532 return; 4533 } 4534 4535 /* Clear sub-page to access last to keep its cache lines hot */ 4536 might_sleep(); 4537 n = (addr_hint - addr) / PAGE_SIZE; 4538 if (2 * n <= pages_per_huge_page) { 4539 /* If sub-page to access in first half of huge page */ 4540 base = 0; 4541 l = n; 4542 /* Clear sub-pages at the end of huge page */ 4543 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { 4544 cond_resched(); 4545 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4546 } 4547 } else { 4548 /* If sub-page to access in second half of huge page */ 4549 base = pages_per_huge_page - 2 * (pages_per_huge_page - n); 4550 l = pages_per_huge_page - n; 4551 /* Clear sub-pages at the begin of huge page */ 4552 for (i = 0; i < base; i++) { 4553 cond_resched(); 4554 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4555 } 4556 } 4557 /* 4558 * Clear remaining sub-pages in left-right-left-right pattern 4559 * towards the sub-page to access 4560 */ 4561 for (i = 0; i < l; i++) { 4562 int left_idx = base + i; 4563 int right_idx = base + 2 * l - 1 - i; 4564 4565 cond_resched(); 4566 clear_user_highpage(page + left_idx, 4567 addr + left_idx * PAGE_SIZE); 4568 cond_resched(); 4569 clear_user_highpage(page + right_idx, 4570 addr + right_idx * PAGE_SIZE); 4571 } 4572 } 4573 4574 static void copy_user_gigantic_page(struct page *dst, struct page *src, 4575 unsigned long addr, 4576 struct vm_area_struct *vma, 4577 unsigned int pages_per_huge_page) 4578 { 4579 int i; 4580 struct page *dst_base = dst; 4581 struct page *src_base = src; 4582 4583 for (i = 0; i < pages_per_huge_page; ) { 4584 cond_resched(); 4585 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 4586 4587 i++; 4588 dst = mem_map_next(dst, dst_base, i); 4589 src = mem_map_next(src, src_base, i); 4590 } 4591 } 4592 4593 void copy_user_huge_page(struct page *dst, struct page *src, 4594 unsigned long addr, struct vm_area_struct *vma, 4595 unsigned int pages_per_huge_page) 4596 { 4597 int i; 4598 4599 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4600 copy_user_gigantic_page(dst, src, addr, vma, 4601 pages_per_huge_page); 4602 return; 4603 } 4604 4605 might_sleep(); 4606 for (i = 0; i < pages_per_huge_page; i++) { 4607 cond_resched(); 4608 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 4609 } 4610 } 4611 4612 long copy_huge_page_from_user(struct page *dst_page, 4613 const void __user *usr_src, 4614 unsigned int pages_per_huge_page, 4615 bool allow_pagefault) 4616 { 4617 void *src = (void *)usr_src; 4618 void *page_kaddr; 4619 unsigned long i, rc = 0; 4620 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; 4621 4622 for (i = 0; i < pages_per_huge_page; i++) { 4623 if (allow_pagefault) 4624 page_kaddr = kmap(dst_page + i); 4625 else 4626 page_kaddr = kmap_atomic(dst_page + i); 4627 rc = copy_from_user(page_kaddr, 4628 (const void __user *)(src + i * PAGE_SIZE), 4629 PAGE_SIZE); 4630 if (allow_pagefault) 4631 kunmap(dst_page + i); 4632 else 4633 kunmap_atomic(page_kaddr); 4634 4635 ret_val -= (PAGE_SIZE - rc); 4636 if (rc) 4637 break; 4638 4639 cond_resched(); 4640 } 4641 return ret_val; 4642 } 4643 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 4644 4645 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 4646 4647 static struct kmem_cache *page_ptl_cachep; 4648 4649 void __init ptlock_cache_init(void) 4650 { 4651 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 4652 SLAB_PANIC, NULL); 4653 } 4654 4655 bool ptlock_alloc(struct page *page) 4656 { 4657 spinlock_t *ptl; 4658 4659 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 4660 if (!ptl) 4661 return false; 4662 page->ptl = ptl; 4663 return true; 4664 } 4665 4666 void ptlock_free(struct page *page) 4667 { 4668 kmem_cache_free(page_ptl_cachep, page->ptl); 4669 } 4670 #endif 4671