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/hugetlb.h> 44 #include <linux/mman.h> 45 #include <linux/swap.h> 46 #include <linux/highmem.h> 47 #include <linux/pagemap.h> 48 #include <linux/ksm.h> 49 #include <linux/rmap.h> 50 #include <linux/export.h> 51 #include <linux/delayacct.h> 52 #include <linux/init.h> 53 #include <linux/writeback.h> 54 #include <linux/memcontrol.h> 55 #include <linux/mmu_notifier.h> 56 #include <linux/kallsyms.h> 57 #include <linux/swapops.h> 58 #include <linux/elf.h> 59 #include <linux/gfp.h> 60 #include <linux/migrate.h> 61 #include <linux/string.h> 62 #include <linux/dma-debug.h> 63 #include <linux/debugfs.h> 64 65 #include <asm/io.h> 66 #include <asm/pgalloc.h> 67 #include <asm/uaccess.h> 68 #include <asm/tlb.h> 69 #include <asm/tlbflush.h> 70 #include <asm/pgtable.h> 71 72 #include "internal.h" 73 74 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 75 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 76 #endif 77 78 #ifndef CONFIG_NEED_MULTIPLE_NODES 79 /* use the per-pgdat data instead for discontigmem - mbligh */ 80 unsigned long max_mapnr; 81 struct page *mem_map; 82 83 EXPORT_SYMBOL(max_mapnr); 84 EXPORT_SYMBOL(mem_map); 85 #endif 86 87 /* 88 * A number of key systems in x86 including ioremap() rely on the assumption 89 * that high_memory defines the upper bound on direct map memory, then end 90 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 91 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 92 * and ZONE_HIGHMEM. 93 */ 94 void * high_memory; 95 96 EXPORT_SYMBOL(high_memory); 97 98 /* 99 * Randomize the address space (stacks, mmaps, brk, etc.). 100 * 101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 102 * as ancient (libc5 based) binaries can segfault. ) 103 */ 104 int randomize_va_space __read_mostly = 105 #ifdef CONFIG_COMPAT_BRK 106 1; 107 #else 108 2; 109 #endif 110 111 static int __init disable_randmaps(char *s) 112 { 113 randomize_va_space = 0; 114 return 1; 115 } 116 __setup("norandmaps", disable_randmaps); 117 118 unsigned long zero_pfn __read_mostly; 119 unsigned long highest_memmap_pfn __read_mostly; 120 121 /* 122 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 123 */ 124 static int __init init_zero_pfn(void) 125 { 126 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 127 return 0; 128 } 129 core_initcall(init_zero_pfn); 130 131 132 #if defined(SPLIT_RSS_COUNTING) 133 134 void sync_mm_rss(struct mm_struct *mm) 135 { 136 int i; 137 138 for (i = 0; i < NR_MM_COUNTERS; i++) { 139 if (current->rss_stat.count[i]) { 140 add_mm_counter(mm, i, current->rss_stat.count[i]); 141 current->rss_stat.count[i] = 0; 142 } 143 } 144 current->rss_stat.events = 0; 145 } 146 147 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 148 { 149 struct task_struct *task = current; 150 151 if (likely(task->mm == mm)) 152 task->rss_stat.count[member] += val; 153 else 154 add_mm_counter(mm, member, val); 155 } 156 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 157 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 158 159 /* sync counter once per 64 page faults */ 160 #define TASK_RSS_EVENTS_THRESH (64) 161 static void check_sync_rss_stat(struct task_struct *task) 162 { 163 if (unlikely(task != current)) 164 return; 165 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 166 sync_mm_rss(task->mm); 167 } 168 #else /* SPLIT_RSS_COUNTING */ 169 170 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 171 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 172 173 static void check_sync_rss_stat(struct task_struct *task) 174 { 175 } 176 177 #endif /* SPLIT_RSS_COUNTING */ 178 179 #ifdef HAVE_GENERIC_MMU_GATHER 180 181 static int tlb_next_batch(struct mmu_gather *tlb) 182 { 183 struct mmu_gather_batch *batch; 184 185 batch = tlb->active; 186 if (batch->next) { 187 tlb->active = batch->next; 188 return 1; 189 } 190 191 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 192 return 0; 193 194 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 195 if (!batch) 196 return 0; 197 198 tlb->batch_count++; 199 batch->next = NULL; 200 batch->nr = 0; 201 batch->max = MAX_GATHER_BATCH; 202 203 tlb->active->next = batch; 204 tlb->active = batch; 205 206 return 1; 207 } 208 209 /* tlb_gather_mmu 210 * Called to initialize an (on-stack) mmu_gather structure for page-table 211 * tear-down from @mm. The @fullmm argument is used when @mm is without 212 * users and we're going to destroy the full address space (exit/execve). 213 */ 214 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) 215 { 216 tlb->mm = mm; 217 218 /* Is it from 0 to ~0? */ 219 tlb->fullmm = !(start | (end+1)); 220 tlb->need_flush_all = 0; 221 tlb->start = start; 222 tlb->end = end; 223 tlb->need_flush = 0; 224 tlb->local.next = NULL; 225 tlb->local.nr = 0; 226 tlb->local.max = ARRAY_SIZE(tlb->__pages); 227 tlb->active = &tlb->local; 228 tlb->batch_count = 0; 229 230 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 231 tlb->batch = NULL; 232 #endif 233 } 234 235 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) 236 { 237 tlb->need_flush = 0; 238 tlb_flush(tlb); 239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 240 tlb_table_flush(tlb); 241 #endif 242 } 243 244 static void tlb_flush_mmu_free(struct mmu_gather *tlb) 245 { 246 struct mmu_gather_batch *batch; 247 248 for (batch = &tlb->local; batch; batch = batch->next) { 249 free_pages_and_swap_cache(batch->pages, batch->nr); 250 batch->nr = 0; 251 } 252 tlb->active = &tlb->local; 253 } 254 255 void tlb_flush_mmu(struct mmu_gather *tlb) 256 { 257 if (!tlb->need_flush) 258 return; 259 tlb_flush_mmu_tlbonly(tlb); 260 tlb_flush_mmu_free(tlb); 261 } 262 263 /* tlb_finish_mmu 264 * Called at the end of the shootdown operation to free up any resources 265 * that were required. 266 */ 267 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 268 { 269 struct mmu_gather_batch *batch, *next; 270 271 tlb_flush_mmu(tlb); 272 273 /* keep the page table cache within bounds */ 274 check_pgt_cache(); 275 276 for (batch = tlb->local.next; batch; batch = next) { 277 next = batch->next; 278 free_pages((unsigned long)batch, 0); 279 } 280 tlb->local.next = NULL; 281 } 282 283 /* __tlb_remove_page 284 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 285 * handling the additional races in SMP caused by other CPUs caching valid 286 * mappings in their TLBs. Returns the number of free page slots left. 287 * When out of page slots we must call tlb_flush_mmu(). 288 */ 289 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 290 { 291 struct mmu_gather_batch *batch; 292 293 VM_BUG_ON(!tlb->need_flush); 294 295 batch = tlb->active; 296 batch->pages[batch->nr++] = page; 297 if (batch->nr == batch->max) { 298 if (!tlb_next_batch(tlb)) 299 return 0; 300 batch = tlb->active; 301 } 302 VM_BUG_ON_PAGE(batch->nr > batch->max, page); 303 304 return batch->max - batch->nr; 305 } 306 307 #endif /* HAVE_GENERIC_MMU_GATHER */ 308 309 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 310 311 /* 312 * See the comment near struct mmu_table_batch. 313 */ 314 315 static void tlb_remove_table_smp_sync(void *arg) 316 { 317 /* Simply deliver the interrupt */ 318 } 319 320 static void tlb_remove_table_one(void *table) 321 { 322 /* 323 * This isn't an RCU grace period and hence the page-tables cannot be 324 * assumed to be actually RCU-freed. 325 * 326 * It is however sufficient for software page-table walkers that rely on 327 * IRQ disabling. See the comment near struct mmu_table_batch. 328 */ 329 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 330 __tlb_remove_table(table); 331 } 332 333 static void tlb_remove_table_rcu(struct rcu_head *head) 334 { 335 struct mmu_table_batch *batch; 336 int i; 337 338 batch = container_of(head, struct mmu_table_batch, rcu); 339 340 for (i = 0; i < batch->nr; i++) 341 __tlb_remove_table(batch->tables[i]); 342 343 free_page((unsigned long)batch); 344 } 345 346 void tlb_table_flush(struct mmu_gather *tlb) 347 { 348 struct mmu_table_batch **batch = &tlb->batch; 349 350 if (*batch) { 351 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 352 *batch = NULL; 353 } 354 } 355 356 void tlb_remove_table(struct mmu_gather *tlb, void *table) 357 { 358 struct mmu_table_batch **batch = &tlb->batch; 359 360 tlb->need_flush = 1; 361 362 /* 363 * When there's less then two users of this mm there cannot be a 364 * concurrent page-table walk. 365 */ 366 if (atomic_read(&tlb->mm->mm_users) < 2) { 367 __tlb_remove_table(table); 368 return; 369 } 370 371 if (*batch == NULL) { 372 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 373 if (*batch == NULL) { 374 tlb_remove_table_one(table); 375 return; 376 } 377 (*batch)->nr = 0; 378 } 379 (*batch)->tables[(*batch)->nr++] = table; 380 if ((*batch)->nr == MAX_TABLE_BATCH) 381 tlb_table_flush(tlb); 382 } 383 384 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 385 386 /* 387 * Note: this doesn't free the actual pages themselves. That 388 * has been handled earlier when unmapping all the memory regions. 389 */ 390 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 391 unsigned long addr) 392 { 393 pgtable_t token = pmd_pgtable(*pmd); 394 pmd_clear(pmd); 395 pte_free_tlb(tlb, token, addr); 396 atomic_long_dec(&tlb->mm->nr_ptes); 397 } 398 399 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 400 unsigned long addr, unsigned long end, 401 unsigned long floor, unsigned long ceiling) 402 { 403 pmd_t *pmd; 404 unsigned long next; 405 unsigned long start; 406 407 start = addr; 408 pmd = pmd_offset(pud, addr); 409 do { 410 next = pmd_addr_end(addr, end); 411 if (pmd_none_or_clear_bad(pmd)) 412 continue; 413 free_pte_range(tlb, pmd, addr); 414 } while (pmd++, addr = next, addr != end); 415 416 start &= PUD_MASK; 417 if (start < floor) 418 return; 419 if (ceiling) { 420 ceiling &= PUD_MASK; 421 if (!ceiling) 422 return; 423 } 424 if (end - 1 > ceiling - 1) 425 return; 426 427 pmd = pmd_offset(pud, start); 428 pud_clear(pud); 429 pmd_free_tlb(tlb, pmd, start); 430 } 431 432 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 433 unsigned long addr, unsigned long end, 434 unsigned long floor, unsigned long ceiling) 435 { 436 pud_t *pud; 437 unsigned long next; 438 unsigned long start; 439 440 start = addr; 441 pud = pud_offset(pgd, addr); 442 do { 443 next = pud_addr_end(addr, end); 444 if (pud_none_or_clear_bad(pud)) 445 continue; 446 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 447 } while (pud++, addr = next, addr != end); 448 449 start &= PGDIR_MASK; 450 if (start < floor) 451 return; 452 if (ceiling) { 453 ceiling &= PGDIR_MASK; 454 if (!ceiling) 455 return; 456 } 457 if (end - 1 > ceiling - 1) 458 return; 459 460 pud = pud_offset(pgd, start); 461 pgd_clear(pgd); 462 pud_free_tlb(tlb, pud, start); 463 } 464 465 /* 466 * This function frees user-level page tables of a process. 467 */ 468 void free_pgd_range(struct mmu_gather *tlb, 469 unsigned long addr, unsigned long end, 470 unsigned long floor, unsigned long ceiling) 471 { 472 pgd_t *pgd; 473 unsigned long next; 474 475 /* 476 * The next few lines have given us lots of grief... 477 * 478 * Why are we testing PMD* at this top level? Because often 479 * there will be no work to do at all, and we'd prefer not to 480 * go all the way down to the bottom just to discover that. 481 * 482 * Why all these "- 1"s? Because 0 represents both the bottom 483 * of the address space and the top of it (using -1 for the 484 * top wouldn't help much: the masks would do the wrong thing). 485 * The rule is that addr 0 and floor 0 refer to the bottom of 486 * the address space, but end 0 and ceiling 0 refer to the top 487 * Comparisons need to use "end - 1" and "ceiling - 1" (though 488 * that end 0 case should be mythical). 489 * 490 * Wherever addr is brought up or ceiling brought down, we must 491 * be careful to reject "the opposite 0" before it confuses the 492 * subsequent tests. But what about where end is brought down 493 * by PMD_SIZE below? no, end can't go down to 0 there. 494 * 495 * Whereas we round start (addr) and ceiling down, by different 496 * masks at different levels, in order to test whether a table 497 * now has no other vmas using it, so can be freed, we don't 498 * bother to round floor or end up - the tests don't need that. 499 */ 500 501 addr &= PMD_MASK; 502 if (addr < floor) { 503 addr += PMD_SIZE; 504 if (!addr) 505 return; 506 } 507 if (ceiling) { 508 ceiling &= PMD_MASK; 509 if (!ceiling) 510 return; 511 } 512 if (end - 1 > ceiling - 1) 513 end -= PMD_SIZE; 514 if (addr > end - 1) 515 return; 516 517 pgd = pgd_offset(tlb->mm, addr); 518 do { 519 next = pgd_addr_end(addr, end); 520 if (pgd_none_or_clear_bad(pgd)) 521 continue; 522 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 523 } while (pgd++, addr = next, addr != end); 524 } 525 526 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 527 unsigned long floor, unsigned long ceiling) 528 { 529 while (vma) { 530 struct vm_area_struct *next = vma->vm_next; 531 unsigned long addr = vma->vm_start; 532 533 /* 534 * Hide vma from rmap and truncate_pagecache before freeing 535 * pgtables 536 */ 537 unlink_anon_vmas(vma); 538 unlink_file_vma(vma); 539 540 if (is_vm_hugetlb_page(vma)) { 541 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 542 floor, next? next->vm_start: ceiling); 543 } else { 544 /* 545 * Optimization: gather nearby vmas into one call down 546 */ 547 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 548 && !is_vm_hugetlb_page(next)) { 549 vma = next; 550 next = vma->vm_next; 551 unlink_anon_vmas(vma); 552 unlink_file_vma(vma); 553 } 554 free_pgd_range(tlb, addr, vma->vm_end, 555 floor, next? next->vm_start: ceiling); 556 } 557 vma = next; 558 } 559 } 560 561 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 562 pmd_t *pmd, unsigned long address) 563 { 564 spinlock_t *ptl; 565 pgtable_t new = pte_alloc_one(mm, address); 566 int wait_split_huge_page; 567 if (!new) 568 return -ENOMEM; 569 570 /* 571 * Ensure all pte setup (eg. pte page lock and page clearing) are 572 * visible before the pte is made visible to other CPUs by being 573 * put into page tables. 574 * 575 * The other side of the story is the pointer chasing in the page 576 * table walking code (when walking the page table without locking; 577 * ie. most of the time). Fortunately, these data accesses consist 578 * of a chain of data-dependent loads, meaning most CPUs (alpha 579 * being the notable exception) will already guarantee loads are 580 * seen in-order. See the alpha page table accessors for the 581 * smp_read_barrier_depends() barriers in page table walking code. 582 */ 583 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 584 585 ptl = pmd_lock(mm, pmd); 586 wait_split_huge_page = 0; 587 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 588 atomic_long_inc(&mm->nr_ptes); 589 pmd_populate(mm, pmd, new); 590 new = NULL; 591 } else if (unlikely(pmd_trans_splitting(*pmd))) 592 wait_split_huge_page = 1; 593 spin_unlock(ptl); 594 if (new) 595 pte_free(mm, new); 596 if (wait_split_huge_page) 597 wait_split_huge_page(vma->anon_vma, pmd); 598 return 0; 599 } 600 601 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 602 { 603 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 604 if (!new) 605 return -ENOMEM; 606 607 smp_wmb(); /* See comment in __pte_alloc */ 608 609 spin_lock(&init_mm.page_table_lock); 610 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 611 pmd_populate_kernel(&init_mm, pmd, new); 612 new = NULL; 613 } else 614 VM_BUG_ON(pmd_trans_splitting(*pmd)); 615 spin_unlock(&init_mm.page_table_lock); 616 if (new) 617 pte_free_kernel(&init_mm, new); 618 return 0; 619 } 620 621 static inline void init_rss_vec(int *rss) 622 { 623 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 624 } 625 626 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 627 { 628 int i; 629 630 if (current->mm == mm) 631 sync_mm_rss(mm); 632 for (i = 0; i < NR_MM_COUNTERS; i++) 633 if (rss[i]) 634 add_mm_counter(mm, i, rss[i]); 635 } 636 637 /* 638 * This function is called to print an error when a bad pte 639 * is found. For example, we might have a PFN-mapped pte in 640 * a region that doesn't allow it. 641 * 642 * The calling function must still handle the error. 643 */ 644 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 645 pte_t pte, struct page *page) 646 { 647 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 648 pud_t *pud = pud_offset(pgd, addr); 649 pmd_t *pmd = pmd_offset(pud, addr); 650 struct address_space *mapping; 651 pgoff_t index; 652 static unsigned long resume; 653 static unsigned long nr_shown; 654 static unsigned long nr_unshown; 655 656 /* 657 * Allow a burst of 60 reports, then keep quiet for that minute; 658 * or allow a steady drip of one report per second. 659 */ 660 if (nr_shown == 60) { 661 if (time_before(jiffies, resume)) { 662 nr_unshown++; 663 return; 664 } 665 if (nr_unshown) { 666 printk(KERN_ALERT 667 "BUG: Bad page map: %lu messages suppressed\n", 668 nr_unshown); 669 nr_unshown = 0; 670 } 671 nr_shown = 0; 672 } 673 if (nr_shown++ == 0) 674 resume = jiffies + 60 * HZ; 675 676 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 677 index = linear_page_index(vma, addr); 678 679 printk(KERN_ALERT 680 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 681 current->comm, 682 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 683 if (page) 684 dump_page(page, "bad pte"); 685 printk(KERN_ALERT 686 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 687 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 688 /* 689 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 690 */ 691 if (vma->vm_ops) 692 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", 693 vma->vm_ops->fault); 694 if (vma->vm_file) 695 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", 696 vma->vm_file->f_op->mmap); 697 dump_stack(); 698 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 699 } 700 701 /* 702 * vm_normal_page -- This function gets the "struct page" associated with a pte. 703 * 704 * "Special" mappings do not wish to be associated with a "struct page" (either 705 * it doesn't exist, or it exists but they don't want to touch it). In this 706 * case, NULL is returned here. "Normal" mappings do have a struct page. 707 * 708 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 709 * pte bit, in which case this function is trivial. Secondly, an architecture 710 * may not have a spare pte bit, which requires a more complicated scheme, 711 * described below. 712 * 713 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 714 * special mapping (even if there are underlying and valid "struct pages"). 715 * COWed pages of a VM_PFNMAP are always normal. 716 * 717 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 718 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 719 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 720 * mapping will always honor the rule 721 * 722 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 723 * 724 * And for normal mappings this is false. 725 * 726 * This restricts such mappings to be a linear translation from virtual address 727 * to pfn. To get around this restriction, we allow arbitrary mappings so long 728 * as the vma is not a COW mapping; in that case, we know that all ptes are 729 * special (because none can have been COWed). 730 * 731 * 732 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 733 * 734 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 735 * page" backing, however the difference is that _all_ pages with a struct 736 * page (that is, those where pfn_valid is true) are refcounted and considered 737 * normal pages by the VM. The disadvantage is that pages are refcounted 738 * (which can be slower and simply not an option for some PFNMAP users). The 739 * advantage is that we don't have to follow the strict linearity rule of 740 * PFNMAP mappings in order to support COWable mappings. 741 * 742 */ 743 #ifdef __HAVE_ARCH_PTE_SPECIAL 744 # define HAVE_PTE_SPECIAL 1 745 #else 746 # define HAVE_PTE_SPECIAL 0 747 #endif 748 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 749 pte_t pte) 750 { 751 unsigned long pfn = pte_pfn(pte); 752 753 if (HAVE_PTE_SPECIAL) { 754 if (likely(!pte_special(pte) || pte_numa(pte))) 755 goto check_pfn; 756 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 757 return NULL; 758 if (!is_zero_pfn(pfn)) 759 print_bad_pte(vma, addr, pte, NULL); 760 return NULL; 761 } 762 763 /* !HAVE_PTE_SPECIAL case follows: */ 764 765 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 766 if (vma->vm_flags & VM_MIXEDMAP) { 767 if (!pfn_valid(pfn)) 768 return NULL; 769 goto out; 770 } else { 771 unsigned long off; 772 off = (addr - vma->vm_start) >> PAGE_SHIFT; 773 if (pfn == vma->vm_pgoff + off) 774 return NULL; 775 if (!is_cow_mapping(vma->vm_flags)) 776 return NULL; 777 } 778 } 779 780 check_pfn: 781 if (unlikely(pfn > highest_memmap_pfn)) { 782 print_bad_pte(vma, addr, pte, NULL); 783 return NULL; 784 } 785 786 if (is_zero_pfn(pfn)) 787 return NULL; 788 789 /* 790 * NOTE! We still have PageReserved() pages in the page tables. 791 * eg. VDSO mappings can cause them to exist. 792 */ 793 out: 794 return pfn_to_page(pfn); 795 } 796 797 /* 798 * copy one vm_area from one task to the other. Assumes the page tables 799 * already present in the new task to be cleared in the whole range 800 * covered by this vma. 801 */ 802 803 static inline unsigned long 804 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 805 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 806 unsigned long addr, int *rss) 807 { 808 unsigned long vm_flags = vma->vm_flags; 809 pte_t pte = *src_pte; 810 struct page *page; 811 812 /* pte contains position in swap or file, so copy. */ 813 if (unlikely(!pte_present(pte))) { 814 if (!pte_file(pte)) { 815 swp_entry_t entry = pte_to_swp_entry(pte); 816 817 if (swap_duplicate(entry) < 0) 818 return entry.val; 819 820 /* make sure dst_mm is on swapoff's mmlist. */ 821 if (unlikely(list_empty(&dst_mm->mmlist))) { 822 spin_lock(&mmlist_lock); 823 if (list_empty(&dst_mm->mmlist)) 824 list_add(&dst_mm->mmlist, 825 &src_mm->mmlist); 826 spin_unlock(&mmlist_lock); 827 } 828 if (likely(!non_swap_entry(entry))) 829 rss[MM_SWAPENTS]++; 830 else if (is_migration_entry(entry)) { 831 page = migration_entry_to_page(entry); 832 833 if (PageAnon(page)) 834 rss[MM_ANONPAGES]++; 835 else 836 rss[MM_FILEPAGES]++; 837 838 if (is_write_migration_entry(entry) && 839 is_cow_mapping(vm_flags)) { 840 /* 841 * COW mappings require pages in both 842 * parent and child to be set to read. 843 */ 844 make_migration_entry_read(&entry); 845 pte = swp_entry_to_pte(entry); 846 if (pte_swp_soft_dirty(*src_pte)) 847 pte = pte_swp_mksoft_dirty(pte); 848 set_pte_at(src_mm, addr, src_pte, pte); 849 } 850 } 851 } 852 goto out_set_pte; 853 } 854 855 /* 856 * If it's a COW mapping, write protect it both 857 * in the parent and the child 858 */ 859 if (is_cow_mapping(vm_flags)) { 860 ptep_set_wrprotect(src_mm, addr, src_pte); 861 pte = pte_wrprotect(pte); 862 } 863 864 /* 865 * If it's a shared mapping, mark it clean in 866 * the child 867 */ 868 if (vm_flags & VM_SHARED) 869 pte = pte_mkclean(pte); 870 pte = pte_mkold(pte); 871 872 page = vm_normal_page(vma, addr, pte); 873 if (page) { 874 get_page(page); 875 page_dup_rmap(page); 876 if (PageAnon(page)) 877 rss[MM_ANONPAGES]++; 878 else 879 rss[MM_FILEPAGES]++; 880 } 881 882 out_set_pte: 883 set_pte_at(dst_mm, addr, dst_pte, pte); 884 return 0; 885 } 886 887 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 888 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 889 unsigned long addr, unsigned long end) 890 { 891 pte_t *orig_src_pte, *orig_dst_pte; 892 pte_t *src_pte, *dst_pte; 893 spinlock_t *src_ptl, *dst_ptl; 894 int progress = 0; 895 int rss[NR_MM_COUNTERS]; 896 swp_entry_t entry = (swp_entry_t){0}; 897 898 again: 899 init_rss_vec(rss); 900 901 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 902 if (!dst_pte) 903 return -ENOMEM; 904 src_pte = pte_offset_map(src_pmd, addr); 905 src_ptl = pte_lockptr(src_mm, src_pmd); 906 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 907 orig_src_pte = src_pte; 908 orig_dst_pte = dst_pte; 909 arch_enter_lazy_mmu_mode(); 910 911 do { 912 /* 913 * We are holding two locks at this point - either of them 914 * could generate latencies in another task on another CPU. 915 */ 916 if (progress >= 32) { 917 progress = 0; 918 if (need_resched() || 919 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 920 break; 921 } 922 if (pte_none(*src_pte)) { 923 progress++; 924 continue; 925 } 926 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 927 vma, addr, rss); 928 if (entry.val) 929 break; 930 progress += 8; 931 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 932 933 arch_leave_lazy_mmu_mode(); 934 spin_unlock(src_ptl); 935 pte_unmap(orig_src_pte); 936 add_mm_rss_vec(dst_mm, rss); 937 pte_unmap_unlock(orig_dst_pte, dst_ptl); 938 cond_resched(); 939 940 if (entry.val) { 941 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 942 return -ENOMEM; 943 progress = 0; 944 } 945 if (addr != end) 946 goto again; 947 return 0; 948 } 949 950 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 951 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 952 unsigned long addr, unsigned long end) 953 { 954 pmd_t *src_pmd, *dst_pmd; 955 unsigned long next; 956 957 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 958 if (!dst_pmd) 959 return -ENOMEM; 960 src_pmd = pmd_offset(src_pud, addr); 961 do { 962 next = pmd_addr_end(addr, end); 963 if (pmd_trans_huge(*src_pmd)) { 964 int err; 965 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 966 err = copy_huge_pmd(dst_mm, src_mm, 967 dst_pmd, src_pmd, addr, vma); 968 if (err == -ENOMEM) 969 return -ENOMEM; 970 if (!err) 971 continue; 972 /* fall through */ 973 } 974 if (pmd_none_or_clear_bad(src_pmd)) 975 continue; 976 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 977 vma, addr, next)) 978 return -ENOMEM; 979 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 980 return 0; 981 } 982 983 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 984 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 985 unsigned long addr, unsigned long end) 986 { 987 pud_t *src_pud, *dst_pud; 988 unsigned long next; 989 990 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 991 if (!dst_pud) 992 return -ENOMEM; 993 src_pud = pud_offset(src_pgd, addr); 994 do { 995 next = pud_addr_end(addr, end); 996 if (pud_none_or_clear_bad(src_pud)) 997 continue; 998 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 999 vma, addr, next)) 1000 return -ENOMEM; 1001 } while (dst_pud++, src_pud++, addr = next, addr != end); 1002 return 0; 1003 } 1004 1005 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1006 struct vm_area_struct *vma) 1007 { 1008 pgd_t *src_pgd, *dst_pgd; 1009 unsigned long next; 1010 unsigned long addr = vma->vm_start; 1011 unsigned long end = vma->vm_end; 1012 unsigned long mmun_start; /* For mmu_notifiers */ 1013 unsigned long mmun_end; /* For mmu_notifiers */ 1014 bool is_cow; 1015 int ret; 1016 1017 /* 1018 * Don't copy ptes where a page fault will fill them correctly. 1019 * Fork becomes much lighter when there are big shared or private 1020 * readonly mappings. The tradeoff is that copy_page_range is more 1021 * efficient than faulting. 1022 */ 1023 if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | 1024 VM_PFNMAP | VM_MIXEDMAP))) { 1025 if (!vma->anon_vma) 1026 return 0; 1027 } 1028 1029 if (is_vm_hugetlb_page(vma)) 1030 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1031 1032 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1033 /* 1034 * We do not free on error cases below as remove_vma 1035 * gets called on error from higher level routine 1036 */ 1037 ret = track_pfn_copy(vma); 1038 if (ret) 1039 return ret; 1040 } 1041 1042 /* 1043 * We need to invalidate the secondary MMU mappings only when 1044 * there could be a permission downgrade on the ptes of the 1045 * parent mm. And a permission downgrade will only happen if 1046 * is_cow_mapping() returns true. 1047 */ 1048 is_cow = is_cow_mapping(vma->vm_flags); 1049 mmun_start = addr; 1050 mmun_end = end; 1051 if (is_cow) 1052 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1053 mmun_end); 1054 1055 ret = 0; 1056 dst_pgd = pgd_offset(dst_mm, addr); 1057 src_pgd = pgd_offset(src_mm, addr); 1058 do { 1059 next = pgd_addr_end(addr, end); 1060 if (pgd_none_or_clear_bad(src_pgd)) 1061 continue; 1062 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 1063 vma, addr, next))) { 1064 ret = -ENOMEM; 1065 break; 1066 } 1067 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1068 1069 if (is_cow) 1070 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1071 return ret; 1072 } 1073 1074 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1075 struct vm_area_struct *vma, pmd_t *pmd, 1076 unsigned long addr, unsigned long end, 1077 struct zap_details *details) 1078 { 1079 struct mm_struct *mm = tlb->mm; 1080 int force_flush = 0; 1081 int rss[NR_MM_COUNTERS]; 1082 spinlock_t *ptl; 1083 pte_t *start_pte; 1084 pte_t *pte; 1085 1086 again: 1087 init_rss_vec(rss); 1088 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1089 pte = start_pte; 1090 arch_enter_lazy_mmu_mode(); 1091 do { 1092 pte_t ptent = *pte; 1093 if (pte_none(ptent)) { 1094 continue; 1095 } 1096 1097 if (pte_present(ptent)) { 1098 struct page *page; 1099 1100 page = vm_normal_page(vma, addr, ptent); 1101 if (unlikely(details) && page) { 1102 /* 1103 * unmap_shared_mapping_pages() wants to 1104 * invalidate cache without truncating: 1105 * unmap shared but keep private pages. 1106 */ 1107 if (details->check_mapping && 1108 details->check_mapping != page->mapping) 1109 continue; 1110 /* 1111 * Each page->index must be checked when 1112 * invalidating or truncating nonlinear. 1113 */ 1114 if (details->nonlinear_vma && 1115 (page->index < details->first_index || 1116 page->index > details->last_index)) 1117 continue; 1118 } 1119 ptent = ptep_get_and_clear_full(mm, addr, pte, 1120 tlb->fullmm); 1121 tlb_remove_tlb_entry(tlb, pte, addr); 1122 if (unlikely(!page)) 1123 continue; 1124 if (unlikely(details) && details->nonlinear_vma 1125 && linear_page_index(details->nonlinear_vma, 1126 addr) != page->index) { 1127 pte_t ptfile = pgoff_to_pte(page->index); 1128 if (pte_soft_dirty(ptent)) 1129 pte_file_mksoft_dirty(ptfile); 1130 set_pte_at(mm, addr, pte, ptfile); 1131 } 1132 if (PageAnon(page)) 1133 rss[MM_ANONPAGES]--; 1134 else { 1135 if (pte_dirty(ptent)) { 1136 force_flush = 1; 1137 set_page_dirty(page); 1138 } 1139 if (pte_young(ptent) && 1140 likely(!(vma->vm_flags & VM_SEQ_READ))) 1141 mark_page_accessed(page); 1142 rss[MM_FILEPAGES]--; 1143 } 1144 page_remove_rmap(page); 1145 if (unlikely(page_mapcount(page) < 0)) 1146 print_bad_pte(vma, addr, ptent, page); 1147 if (unlikely(!__tlb_remove_page(tlb, page))) { 1148 force_flush = 1; 1149 break; 1150 } 1151 continue; 1152 } 1153 /* 1154 * If details->check_mapping, we leave swap entries; 1155 * if details->nonlinear_vma, we leave file entries. 1156 */ 1157 if (unlikely(details)) 1158 continue; 1159 if (pte_file(ptent)) { 1160 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 1161 print_bad_pte(vma, addr, ptent, NULL); 1162 } else { 1163 swp_entry_t entry = pte_to_swp_entry(ptent); 1164 1165 if (!non_swap_entry(entry)) 1166 rss[MM_SWAPENTS]--; 1167 else if (is_migration_entry(entry)) { 1168 struct page *page; 1169 1170 page = migration_entry_to_page(entry); 1171 1172 if (PageAnon(page)) 1173 rss[MM_ANONPAGES]--; 1174 else 1175 rss[MM_FILEPAGES]--; 1176 } 1177 if (unlikely(!free_swap_and_cache(entry))) 1178 print_bad_pte(vma, addr, ptent, NULL); 1179 } 1180 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1181 } while (pte++, addr += PAGE_SIZE, addr != end); 1182 1183 add_mm_rss_vec(mm, rss); 1184 arch_leave_lazy_mmu_mode(); 1185 1186 /* Do the actual TLB flush before dropping ptl */ 1187 if (force_flush) { 1188 unsigned long old_end; 1189 1190 /* 1191 * Flush the TLB just for the previous segment, 1192 * then update the range to be the remaining 1193 * TLB range. 1194 */ 1195 old_end = tlb->end; 1196 tlb->end = addr; 1197 tlb_flush_mmu_tlbonly(tlb); 1198 tlb->start = addr; 1199 tlb->end = old_end; 1200 } 1201 pte_unmap_unlock(start_pte, ptl); 1202 1203 /* 1204 * If we forced a TLB flush (either due to running out of 1205 * batch buffers or because we needed to flush dirty TLB 1206 * entries before releasing the ptl), free the batched 1207 * memory too. Restart if we didn't do everything. 1208 */ 1209 if (force_flush) { 1210 force_flush = 0; 1211 tlb_flush_mmu_free(tlb); 1212 1213 if (addr != end) 1214 goto again; 1215 } 1216 1217 return addr; 1218 } 1219 1220 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1221 struct vm_area_struct *vma, pud_t *pud, 1222 unsigned long addr, unsigned long end, 1223 struct zap_details *details) 1224 { 1225 pmd_t *pmd; 1226 unsigned long next; 1227 1228 pmd = pmd_offset(pud, addr); 1229 do { 1230 next = pmd_addr_end(addr, end); 1231 if (pmd_trans_huge(*pmd)) { 1232 if (next - addr != HPAGE_PMD_SIZE) { 1233 #ifdef CONFIG_DEBUG_VM 1234 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { 1235 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", 1236 __func__, addr, end, 1237 vma->vm_start, 1238 vma->vm_end); 1239 BUG(); 1240 } 1241 #endif 1242 split_huge_page_pmd(vma, addr, pmd); 1243 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1244 goto next; 1245 /* fall through */ 1246 } 1247 /* 1248 * Here there can be other concurrent MADV_DONTNEED or 1249 * trans huge page faults running, and if the pmd is 1250 * none or trans huge it can change under us. This is 1251 * because MADV_DONTNEED holds the mmap_sem in read 1252 * mode. 1253 */ 1254 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1255 goto next; 1256 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1257 next: 1258 cond_resched(); 1259 } while (pmd++, addr = next, addr != end); 1260 1261 return addr; 1262 } 1263 1264 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1265 struct vm_area_struct *vma, pgd_t *pgd, 1266 unsigned long addr, unsigned long end, 1267 struct zap_details *details) 1268 { 1269 pud_t *pud; 1270 unsigned long next; 1271 1272 pud = pud_offset(pgd, addr); 1273 do { 1274 next = pud_addr_end(addr, end); 1275 if (pud_none_or_clear_bad(pud)) 1276 continue; 1277 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1278 } while (pud++, addr = next, addr != end); 1279 1280 return addr; 1281 } 1282 1283 static void unmap_page_range(struct mmu_gather *tlb, 1284 struct vm_area_struct *vma, 1285 unsigned long addr, unsigned long end, 1286 struct zap_details *details) 1287 { 1288 pgd_t *pgd; 1289 unsigned long next; 1290 1291 if (details && !details->check_mapping && !details->nonlinear_vma) 1292 details = NULL; 1293 1294 BUG_ON(addr >= end); 1295 mem_cgroup_uncharge_start(); 1296 tlb_start_vma(tlb, vma); 1297 pgd = pgd_offset(vma->vm_mm, addr); 1298 do { 1299 next = pgd_addr_end(addr, end); 1300 if (pgd_none_or_clear_bad(pgd)) 1301 continue; 1302 next = zap_pud_range(tlb, vma, pgd, addr, next, details); 1303 } while (pgd++, addr = next, addr != end); 1304 tlb_end_vma(tlb, vma); 1305 mem_cgroup_uncharge_end(); 1306 } 1307 1308 1309 static void unmap_single_vma(struct mmu_gather *tlb, 1310 struct vm_area_struct *vma, unsigned long start_addr, 1311 unsigned long end_addr, 1312 struct zap_details *details) 1313 { 1314 unsigned long start = max(vma->vm_start, start_addr); 1315 unsigned long end; 1316 1317 if (start >= vma->vm_end) 1318 return; 1319 end = min(vma->vm_end, end_addr); 1320 if (end <= vma->vm_start) 1321 return; 1322 1323 if (vma->vm_file) 1324 uprobe_munmap(vma, start, end); 1325 1326 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1327 untrack_pfn(vma, 0, 0); 1328 1329 if (start != end) { 1330 if (unlikely(is_vm_hugetlb_page(vma))) { 1331 /* 1332 * It is undesirable to test vma->vm_file as it 1333 * should be non-null for valid hugetlb area. 1334 * However, vm_file will be NULL in the error 1335 * cleanup path of mmap_region. When 1336 * hugetlbfs ->mmap method fails, 1337 * mmap_region() nullifies vma->vm_file 1338 * before calling this function to clean up. 1339 * Since no pte has actually been setup, it is 1340 * safe to do nothing in this case. 1341 */ 1342 if (vma->vm_file) { 1343 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 1344 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1345 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 1346 } 1347 } else 1348 unmap_page_range(tlb, vma, start, end, details); 1349 } 1350 } 1351 1352 /** 1353 * unmap_vmas - unmap a range of memory covered by a list of vma's 1354 * @tlb: address of the caller's struct mmu_gather 1355 * @vma: the starting vma 1356 * @start_addr: virtual address at which to start unmapping 1357 * @end_addr: virtual address at which to end unmapping 1358 * 1359 * Unmap all pages in the vma list. 1360 * 1361 * Only addresses between `start' and `end' will be unmapped. 1362 * 1363 * The VMA list must be sorted in ascending virtual address order. 1364 * 1365 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1366 * range after unmap_vmas() returns. So the only responsibility here is to 1367 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1368 * drops the lock and schedules. 1369 */ 1370 void unmap_vmas(struct mmu_gather *tlb, 1371 struct vm_area_struct *vma, unsigned long start_addr, 1372 unsigned long end_addr) 1373 { 1374 struct mm_struct *mm = vma->vm_mm; 1375 1376 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1377 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1378 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1379 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1380 } 1381 1382 /** 1383 * zap_page_range - remove user pages in a given range 1384 * @vma: vm_area_struct holding the applicable pages 1385 * @start: starting address of pages to zap 1386 * @size: number of bytes to zap 1387 * @details: details of nonlinear truncation or shared cache invalidation 1388 * 1389 * Caller must protect the VMA list 1390 */ 1391 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1392 unsigned long size, struct zap_details *details) 1393 { 1394 struct mm_struct *mm = vma->vm_mm; 1395 struct mmu_gather tlb; 1396 unsigned long end = start + size; 1397 1398 lru_add_drain(); 1399 tlb_gather_mmu(&tlb, mm, start, end); 1400 update_hiwater_rss(mm); 1401 mmu_notifier_invalidate_range_start(mm, start, end); 1402 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) 1403 unmap_single_vma(&tlb, vma, start, end, details); 1404 mmu_notifier_invalidate_range_end(mm, start, end); 1405 tlb_finish_mmu(&tlb, start, end); 1406 } 1407 1408 /** 1409 * zap_page_range_single - remove user pages in a given range 1410 * @vma: vm_area_struct holding the applicable pages 1411 * @address: starting address of pages to zap 1412 * @size: number of bytes to zap 1413 * @details: details of nonlinear truncation or shared cache invalidation 1414 * 1415 * The range must fit into one VMA. 1416 */ 1417 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1418 unsigned long size, struct zap_details *details) 1419 { 1420 struct mm_struct *mm = vma->vm_mm; 1421 struct mmu_gather tlb; 1422 unsigned long end = address + size; 1423 1424 lru_add_drain(); 1425 tlb_gather_mmu(&tlb, mm, address, end); 1426 update_hiwater_rss(mm); 1427 mmu_notifier_invalidate_range_start(mm, address, end); 1428 unmap_single_vma(&tlb, vma, address, end, details); 1429 mmu_notifier_invalidate_range_end(mm, address, end); 1430 tlb_finish_mmu(&tlb, address, end); 1431 } 1432 1433 /** 1434 * zap_vma_ptes - remove ptes mapping the vma 1435 * @vma: vm_area_struct holding ptes to be zapped 1436 * @address: starting address of pages to zap 1437 * @size: number of bytes to zap 1438 * 1439 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1440 * 1441 * The entire address range must be fully contained within the vma. 1442 * 1443 * Returns 0 if successful. 1444 */ 1445 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1446 unsigned long size) 1447 { 1448 if (address < vma->vm_start || address + size > vma->vm_end || 1449 !(vma->vm_flags & VM_PFNMAP)) 1450 return -1; 1451 zap_page_range_single(vma, address, size, NULL); 1452 return 0; 1453 } 1454 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1455 1456 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1457 spinlock_t **ptl) 1458 { 1459 pgd_t * pgd = pgd_offset(mm, addr); 1460 pud_t * pud = pud_alloc(mm, pgd, addr); 1461 if (pud) { 1462 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1463 if (pmd) { 1464 VM_BUG_ON(pmd_trans_huge(*pmd)); 1465 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1466 } 1467 } 1468 return NULL; 1469 } 1470 1471 /* 1472 * This is the old fallback for page remapping. 1473 * 1474 * For historical reasons, it only allows reserved pages. Only 1475 * old drivers should use this, and they needed to mark their 1476 * pages reserved for the old functions anyway. 1477 */ 1478 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1479 struct page *page, pgprot_t prot) 1480 { 1481 struct mm_struct *mm = vma->vm_mm; 1482 int retval; 1483 pte_t *pte; 1484 spinlock_t *ptl; 1485 1486 retval = -EINVAL; 1487 if (PageAnon(page)) 1488 goto out; 1489 retval = -ENOMEM; 1490 flush_dcache_page(page); 1491 pte = get_locked_pte(mm, addr, &ptl); 1492 if (!pte) 1493 goto out; 1494 retval = -EBUSY; 1495 if (!pte_none(*pte)) 1496 goto out_unlock; 1497 1498 /* Ok, finally just insert the thing.. */ 1499 get_page(page); 1500 inc_mm_counter_fast(mm, MM_FILEPAGES); 1501 page_add_file_rmap(page); 1502 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1503 1504 retval = 0; 1505 pte_unmap_unlock(pte, ptl); 1506 return retval; 1507 out_unlock: 1508 pte_unmap_unlock(pte, ptl); 1509 out: 1510 return retval; 1511 } 1512 1513 /** 1514 * vm_insert_page - insert single page into user vma 1515 * @vma: user vma to map to 1516 * @addr: target user address of this page 1517 * @page: source kernel page 1518 * 1519 * This allows drivers to insert individual pages they've allocated 1520 * into a user vma. 1521 * 1522 * The page has to be a nice clean _individual_ kernel allocation. 1523 * If you allocate a compound page, you need to have marked it as 1524 * such (__GFP_COMP), or manually just split the page up yourself 1525 * (see split_page()). 1526 * 1527 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1528 * took an arbitrary page protection parameter. This doesn't allow 1529 * that. Your vma protection will have to be set up correctly, which 1530 * means that if you want a shared writable mapping, you'd better 1531 * ask for a shared writable mapping! 1532 * 1533 * The page does not need to be reserved. 1534 * 1535 * Usually this function is called from f_op->mmap() handler 1536 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 1537 * Caller must set VM_MIXEDMAP on vma if it wants to call this 1538 * function from other places, for example from page-fault handler. 1539 */ 1540 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1541 struct page *page) 1542 { 1543 if (addr < vma->vm_start || addr >= vma->vm_end) 1544 return -EFAULT; 1545 if (!page_count(page)) 1546 return -EINVAL; 1547 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1548 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 1549 BUG_ON(vma->vm_flags & VM_PFNMAP); 1550 vma->vm_flags |= VM_MIXEDMAP; 1551 } 1552 return insert_page(vma, addr, page, vma->vm_page_prot); 1553 } 1554 EXPORT_SYMBOL(vm_insert_page); 1555 1556 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1557 unsigned long pfn, pgprot_t prot) 1558 { 1559 struct mm_struct *mm = vma->vm_mm; 1560 int retval; 1561 pte_t *pte, entry; 1562 spinlock_t *ptl; 1563 1564 retval = -ENOMEM; 1565 pte = get_locked_pte(mm, addr, &ptl); 1566 if (!pte) 1567 goto out; 1568 retval = -EBUSY; 1569 if (!pte_none(*pte)) 1570 goto out_unlock; 1571 1572 /* Ok, finally just insert the thing.. */ 1573 entry = pte_mkspecial(pfn_pte(pfn, prot)); 1574 set_pte_at(mm, addr, pte, entry); 1575 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 1576 1577 retval = 0; 1578 out_unlock: 1579 pte_unmap_unlock(pte, ptl); 1580 out: 1581 return retval; 1582 } 1583 1584 /** 1585 * vm_insert_pfn - insert single pfn into user vma 1586 * @vma: user vma to map to 1587 * @addr: target user address of this page 1588 * @pfn: source kernel pfn 1589 * 1590 * Similar to vm_insert_page, this allows drivers to insert individual pages 1591 * they've allocated into a user vma. Same comments apply. 1592 * 1593 * This function should only be called from a vm_ops->fault handler, and 1594 * in that case the handler should return NULL. 1595 * 1596 * vma cannot be a COW mapping. 1597 * 1598 * As this is called only for pages that do not currently exist, we 1599 * do not need to flush old virtual caches or the TLB. 1600 */ 1601 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1602 unsigned long pfn) 1603 { 1604 int ret; 1605 pgprot_t pgprot = vma->vm_page_prot; 1606 /* 1607 * Technically, architectures with pte_special can avoid all these 1608 * restrictions (same for remap_pfn_range). However we would like 1609 * consistency in testing and feature parity among all, so we should 1610 * try to keep these invariants in place for everybody. 1611 */ 1612 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1613 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1614 (VM_PFNMAP|VM_MIXEDMAP)); 1615 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1616 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1617 1618 if (addr < vma->vm_start || addr >= vma->vm_end) 1619 return -EFAULT; 1620 if (track_pfn_insert(vma, &pgprot, pfn)) 1621 return -EINVAL; 1622 1623 ret = insert_pfn(vma, addr, pfn, pgprot); 1624 1625 return ret; 1626 } 1627 EXPORT_SYMBOL(vm_insert_pfn); 1628 1629 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1630 unsigned long pfn) 1631 { 1632 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1633 1634 if (addr < vma->vm_start || addr >= vma->vm_end) 1635 return -EFAULT; 1636 1637 /* 1638 * If we don't have pte special, then we have to use the pfn_valid() 1639 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1640 * refcount the page if pfn_valid is true (hence insert_page rather 1641 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1642 * without pte special, it would there be refcounted as a normal page. 1643 */ 1644 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 1645 struct page *page; 1646 1647 page = pfn_to_page(pfn); 1648 return insert_page(vma, addr, page, vma->vm_page_prot); 1649 } 1650 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 1651 } 1652 EXPORT_SYMBOL(vm_insert_mixed); 1653 1654 /* 1655 * maps a range of physical memory into the requested pages. the old 1656 * mappings are removed. any references to nonexistent pages results 1657 * in null mappings (currently treated as "copy-on-access") 1658 */ 1659 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1660 unsigned long addr, unsigned long end, 1661 unsigned long pfn, pgprot_t prot) 1662 { 1663 pte_t *pte; 1664 spinlock_t *ptl; 1665 1666 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1667 if (!pte) 1668 return -ENOMEM; 1669 arch_enter_lazy_mmu_mode(); 1670 do { 1671 BUG_ON(!pte_none(*pte)); 1672 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1673 pfn++; 1674 } while (pte++, addr += PAGE_SIZE, addr != end); 1675 arch_leave_lazy_mmu_mode(); 1676 pte_unmap_unlock(pte - 1, ptl); 1677 return 0; 1678 } 1679 1680 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1681 unsigned long addr, unsigned long end, 1682 unsigned long pfn, pgprot_t prot) 1683 { 1684 pmd_t *pmd; 1685 unsigned long next; 1686 1687 pfn -= addr >> PAGE_SHIFT; 1688 pmd = pmd_alloc(mm, pud, addr); 1689 if (!pmd) 1690 return -ENOMEM; 1691 VM_BUG_ON(pmd_trans_huge(*pmd)); 1692 do { 1693 next = pmd_addr_end(addr, end); 1694 if (remap_pte_range(mm, pmd, addr, next, 1695 pfn + (addr >> PAGE_SHIFT), prot)) 1696 return -ENOMEM; 1697 } while (pmd++, addr = next, addr != end); 1698 return 0; 1699 } 1700 1701 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1702 unsigned long addr, unsigned long end, 1703 unsigned long pfn, pgprot_t prot) 1704 { 1705 pud_t *pud; 1706 unsigned long next; 1707 1708 pfn -= addr >> PAGE_SHIFT; 1709 pud = pud_alloc(mm, pgd, addr); 1710 if (!pud) 1711 return -ENOMEM; 1712 do { 1713 next = pud_addr_end(addr, end); 1714 if (remap_pmd_range(mm, pud, addr, next, 1715 pfn + (addr >> PAGE_SHIFT), prot)) 1716 return -ENOMEM; 1717 } while (pud++, addr = next, addr != end); 1718 return 0; 1719 } 1720 1721 /** 1722 * remap_pfn_range - remap kernel memory to userspace 1723 * @vma: user vma to map to 1724 * @addr: target user address to start at 1725 * @pfn: physical address of kernel memory 1726 * @size: size of map area 1727 * @prot: page protection flags for this mapping 1728 * 1729 * Note: this is only safe if the mm semaphore is held when called. 1730 */ 1731 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1732 unsigned long pfn, unsigned long size, pgprot_t prot) 1733 { 1734 pgd_t *pgd; 1735 unsigned long next; 1736 unsigned long end = addr + PAGE_ALIGN(size); 1737 struct mm_struct *mm = vma->vm_mm; 1738 int err; 1739 1740 /* 1741 * Physically remapped pages are special. Tell the 1742 * rest of the world about it: 1743 * VM_IO tells people not to look at these pages 1744 * (accesses can have side effects). 1745 * VM_PFNMAP tells the core MM that the base pages are just 1746 * raw PFN mappings, and do not have a "struct page" associated 1747 * with them. 1748 * VM_DONTEXPAND 1749 * Disable vma merging and expanding with mremap(). 1750 * VM_DONTDUMP 1751 * Omit vma from core dump, even when VM_IO turned off. 1752 * 1753 * There's a horrible special case to handle copy-on-write 1754 * behaviour that some programs depend on. We mark the "original" 1755 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1756 * See vm_normal_page() for details. 1757 */ 1758 if (is_cow_mapping(vma->vm_flags)) { 1759 if (addr != vma->vm_start || end != vma->vm_end) 1760 return -EINVAL; 1761 vma->vm_pgoff = pfn; 1762 } 1763 1764 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); 1765 if (err) 1766 return -EINVAL; 1767 1768 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 1769 1770 BUG_ON(addr >= end); 1771 pfn -= addr >> PAGE_SHIFT; 1772 pgd = pgd_offset(mm, addr); 1773 flush_cache_range(vma, addr, end); 1774 do { 1775 next = pgd_addr_end(addr, end); 1776 err = remap_pud_range(mm, pgd, addr, next, 1777 pfn + (addr >> PAGE_SHIFT), prot); 1778 if (err) 1779 break; 1780 } while (pgd++, addr = next, addr != end); 1781 1782 if (err) 1783 untrack_pfn(vma, pfn, PAGE_ALIGN(size)); 1784 1785 return err; 1786 } 1787 EXPORT_SYMBOL(remap_pfn_range); 1788 1789 /** 1790 * vm_iomap_memory - remap memory to userspace 1791 * @vma: user vma to map to 1792 * @start: start of area 1793 * @len: size of area 1794 * 1795 * This is a simplified io_remap_pfn_range() for common driver use. The 1796 * driver just needs to give us the physical memory range to be mapped, 1797 * we'll figure out the rest from the vma information. 1798 * 1799 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 1800 * whatever write-combining details or similar. 1801 */ 1802 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 1803 { 1804 unsigned long vm_len, pfn, pages; 1805 1806 /* Check that the physical memory area passed in looks valid */ 1807 if (start + len < start) 1808 return -EINVAL; 1809 /* 1810 * You *really* shouldn't map things that aren't page-aligned, 1811 * but we've historically allowed it because IO memory might 1812 * just have smaller alignment. 1813 */ 1814 len += start & ~PAGE_MASK; 1815 pfn = start >> PAGE_SHIFT; 1816 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 1817 if (pfn + pages < pfn) 1818 return -EINVAL; 1819 1820 /* We start the mapping 'vm_pgoff' pages into the area */ 1821 if (vma->vm_pgoff > pages) 1822 return -EINVAL; 1823 pfn += vma->vm_pgoff; 1824 pages -= vma->vm_pgoff; 1825 1826 /* Can we fit all of the mapping? */ 1827 vm_len = vma->vm_end - vma->vm_start; 1828 if (vm_len >> PAGE_SHIFT > pages) 1829 return -EINVAL; 1830 1831 /* Ok, let it rip */ 1832 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 1833 } 1834 EXPORT_SYMBOL(vm_iomap_memory); 1835 1836 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1837 unsigned long addr, unsigned long end, 1838 pte_fn_t fn, void *data) 1839 { 1840 pte_t *pte; 1841 int err; 1842 pgtable_t token; 1843 spinlock_t *uninitialized_var(ptl); 1844 1845 pte = (mm == &init_mm) ? 1846 pte_alloc_kernel(pmd, addr) : 1847 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1848 if (!pte) 1849 return -ENOMEM; 1850 1851 BUG_ON(pmd_huge(*pmd)); 1852 1853 arch_enter_lazy_mmu_mode(); 1854 1855 token = pmd_pgtable(*pmd); 1856 1857 do { 1858 err = fn(pte++, token, addr, data); 1859 if (err) 1860 break; 1861 } while (addr += PAGE_SIZE, addr != end); 1862 1863 arch_leave_lazy_mmu_mode(); 1864 1865 if (mm != &init_mm) 1866 pte_unmap_unlock(pte-1, ptl); 1867 return err; 1868 } 1869 1870 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1871 unsigned long addr, unsigned long end, 1872 pte_fn_t fn, void *data) 1873 { 1874 pmd_t *pmd; 1875 unsigned long next; 1876 int err; 1877 1878 BUG_ON(pud_huge(*pud)); 1879 1880 pmd = pmd_alloc(mm, pud, addr); 1881 if (!pmd) 1882 return -ENOMEM; 1883 do { 1884 next = pmd_addr_end(addr, end); 1885 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1886 if (err) 1887 break; 1888 } while (pmd++, addr = next, addr != end); 1889 return err; 1890 } 1891 1892 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1893 unsigned long addr, unsigned long end, 1894 pte_fn_t fn, void *data) 1895 { 1896 pud_t *pud; 1897 unsigned long next; 1898 int err; 1899 1900 pud = pud_alloc(mm, pgd, addr); 1901 if (!pud) 1902 return -ENOMEM; 1903 do { 1904 next = pud_addr_end(addr, end); 1905 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1906 if (err) 1907 break; 1908 } while (pud++, addr = next, addr != end); 1909 return err; 1910 } 1911 1912 /* 1913 * Scan a region of virtual memory, filling in page tables as necessary 1914 * and calling a provided function on each leaf page table. 1915 */ 1916 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1917 unsigned long size, pte_fn_t fn, void *data) 1918 { 1919 pgd_t *pgd; 1920 unsigned long next; 1921 unsigned long end = addr + size; 1922 int err; 1923 1924 BUG_ON(addr >= end); 1925 pgd = pgd_offset(mm, addr); 1926 do { 1927 next = pgd_addr_end(addr, end); 1928 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1929 if (err) 1930 break; 1931 } while (pgd++, addr = next, addr != end); 1932 1933 return err; 1934 } 1935 EXPORT_SYMBOL_GPL(apply_to_page_range); 1936 1937 /* 1938 * handle_pte_fault chooses page fault handler according to an entry 1939 * which was read non-atomically. Before making any commitment, on 1940 * those architectures or configurations (e.g. i386 with PAE) which 1941 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 1942 * must check under lock before unmapping the pte and proceeding 1943 * (but do_wp_page is only called after already making such a check; 1944 * and do_anonymous_page can safely check later on). 1945 */ 1946 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1947 pte_t *page_table, pte_t orig_pte) 1948 { 1949 int same = 1; 1950 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1951 if (sizeof(pte_t) > sizeof(unsigned long)) { 1952 spinlock_t *ptl = pte_lockptr(mm, pmd); 1953 spin_lock(ptl); 1954 same = pte_same(*page_table, orig_pte); 1955 spin_unlock(ptl); 1956 } 1957 #endif 1958 pte_unmap(page_table); 1959 return same; 1960 } 1961 1962 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1963 { 1964 debug_dma_assert_idle(src); 1965 1966 /* 1967 * If the source page was a PFN mapping, we don't have 1968 * a "struct page" for it. We do a best-effort copy by 1969 * just copying from the original user address. If that 1970 * fails, we just zero-fill it. Live with it. 1971 */ 1972 if (unlikely(!src)) { 1973 void *kaddr = kmap_atomic(dst); 1974 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1975 1976 /* 1977 * This really shouldn't fail, because the page is there 1978 * in the page tables. But it might just be unreadable, 1979 * in which case we just give up and fill the result with 1980 * zeroes. 1981 */ 1982 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1983 clear_page(kaddr); 1984 kunmap_atomic(kaddr); 1985 flush_dcache_page(dst); 1986 } else 1987 copy_user_highpage(dst, src, va, vma); 1988 } 1989 1990 /* 1991 * Notify the address space that the page is about to become writable so that 1992 * it can prohibit this or wait for the page to get into an appropriate state. 1993 * 1994 * We do this without the lock held, so that it can sleep if it needs to. 1995 */ 1996 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page, 1997 unsigned long address) 1998 { 1999 struct vm_fault vmf; 2000 int ret; 2001 2002 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2003 vmf.pgoff = page->index; 2004 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2005 vmf.page = page; 2006 2007 ret = vma->vm_ops->page_mkwrite(vma, &vmf); 2008 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2009 return ret; 2010 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2011 lock_page(page); 2012 if (!page->mapping) { 2013 unlock_page(page); 2014 return 0; /* retry */ 2015 } 2016 ret |= VM_FAULT_LOCKED; 2017 } else 2018 VM_BUG_ON_PAGE(!PageLocked(page), page); 2019 return ret; 2020 } 2021 2022 /* 2023 * This routine handles present pages, when users try to write 2024 * to a shared page. It is done by copying the page to a new address 2025 * and decrementing the shared-page counter for the old page. 2026 * 2027 * Note that this routine assumes that the protection checks have been 2028 * done by the caller (the low-level page fault routine in most cases). 2029 * Thus we can safely just mark it writable once we've done any necessary 2030 * COW. 2031 * 2032 * We also mark the page dirty at this point even though the page will 2033 * change only once the write actually happens. This avoids a few races, 2034 * and potentially makes it more efficient. 2035 * 2036 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2037 * but allow concurrent faults), with pte both mapped and locked. 2038 * We return with mmap_sem still held, but pte unmapped and unlocked. 2039 */ 2040 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2041 unsigned long address, pte_t *page_table, pmd_t *pmd, 2042 spinlock_t *ptl, pte_t orig_pte) 2043 __releases(ptl) 2044 { 2045 struct page *old_page, *new_page = NULL; 2046 pte_t entry; 2047 int ret = 0; 2048 int page_mkwrite = 0; 2049 struct page *dirty_page = NULL; 2050 unsigned long mmun_start = 0; /* For mmu_notifiers */ 2051 unsigned long mmun_end = 0; /* For mmu_notifiers */ 2052 2053 old_page = vm_normal_page(vma, address, orig_pte); 2054 if (!old_page) { 2055 /* 2056 * VM_MIXEDMAP !pfn_valid() case 2057 * 2058 * We should not cow pages in a shared writeable mapping. 2059 * Just mark the pages writable as we can't do any dirty 2060 * accounting on raw pfn maps. 2061 */ 2062 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2063 (VM_WRITE|VM_SHARED)) 2064 goto reuse; 2065 goto gotten; 2066 } 2067 2068 /* 2069 * Take out anonymous pages first, anonymous shared vmas are 2070 * not dirty accountable. 2071 */ 2072 if (PageAnon(old_page) && !PageKsm(old_page)) { 2073 if (!trylock_page(old_page)) { 2074 page_cache_get(old_page); 2075 pte_unmap_unlock(page_table, ptl); 2076 lock_page(old_page); 2077 page_table = pte_offset_map_lock(mm, pmd, address, 2078 &ptl); 2079 if (!pte_same(*page_table, orig_pte)) { 2080 unlock_page(old_page); 2081 goto unlock; 2082 } 2083 page_cache_release(old_page); 2084 } 2085 if (reuse_swap_page(old_page)) { 2086 /* 2087 * The page is all ours. Move it to our anon_vma so 2088 * the rmap code will not search our parent or siblings. 2089 * Protected against the rmap code by the page lock. 2090 */ 2091 page_move_anon_rmap(old_page, vma, address); 2092 unlock_page(old_page); 2093 goto reuse; 2094 } 2095 unlock_page(old_page); 2096 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2097 (VM_WRITE|VM_SHARED))) { 2098 /* 2099 * Only catch write-faults on shared writable pages, 2100 * read-only shared pages can get COWed by 2101 * get_user_pages(.write=1, .force=1). 2102 */ 2103 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2104 int tmp; 2105 page_cache_get(old_page); 2106 pte_unmap_unlock(page_table, ptl); 2107 tmp = do_page_mkwrite(vma, old_page, address); 2108 if (unlikely(!tmp || (tmp & 2109 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2110 page_cache_release(old_page); 2111 return tmp; 2112 } 2113 /* 2114 * Since we dropped the lock we need to revalidate 2115 * the PTE as someone else may have changed it. If 2116 * they did, we just return, as we can count on the 2117 * MMU to tell us if they didn't also make it writable. 2118 */ 2119 page_table = pte_offset_map_lock(mm, pmd, address, 2120 &ptl); 2121 if (!pte_same(*page_table, orig_pte)) { 2122 unlock_page(old_page); 2123 goto unlock; 2124 } 2125 2126 page_mkwrite = 1; 2127 } 2128 dirty_page = old_page; 2129 get_page(dirty_page); 2130 2131 reuse: 2132 /* 2133 * Clear the pages cpupid information as the existing 2134 * information potentially belongs to a now completely 2135 * unrelated process. 2136 */ 2137 if (old_page) 2138 page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1); 2139 2140 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2141 entry = pte_mkyoung(orig_pte); 2142 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2143 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2144 update_mmu_cache(vma, address, page_table); 2145 pte_unmap_unlock(page_table, ptl); 2146 ret |= VM_FAULT_WRITE; 2147 2148 if (!dirty_page) 2149 return ret; 2150 2151 /* 2152 * Yes, Virginia, this is actually required to prevent a race 2153 * with clear_page_dirty_for_io() from clearing the page dirty 2154 * bit after it clear all dirty ptes, but before a racing 2155 * do_wp_page installs a dirty pte. 2156 * 2157 * do_shared_fault is protected similarly. 2158 */ 2159 if (!page_mkwrite) { 2160 wait_on_page_locked(dirty_page); 2161 set_page_dirty_balance(dirty_page); 2162 /* file_update_time outside page_lock */ 2163 if (vma->vm_file) 2164 file_update_time(vma->vm_file); 2165 } 2166 put_page(dirty_page); 2167 if (page_mkwrite) { 2168 struct address_space *mapping = dirty_page->mapping; 2169 2170 set_page_dirty(dirty_page); 2171 unlock_page(dirty_page); 2172 page_cache_release(dirty_page); 2173 if (mapping) { 2174 /* 2175 * Some device drivers do not set page.mapping 2176 * but still dirty their pages 2177 */ 2178 balance_dirty_pages_ratelimited(mapping); 2179 } 2180 } 2181 2182 return ret; 2183 } 2184 2185 /* 2186 * Ok, we need to copy. Oh, well.. 2187 */ 2188 page_cache_get(old_page); 2189 gotten: 2190 pte_unmap_unlock(page_table, ptl); 2191 2192 if (unlikely(anon_vma_prepare(vma))) 2193 goto oom; 2194 2195 if (is_zero_pfn(pte_pfn(orig_pte))) { 2196 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2197 if (!new_page) 2198 goto oom; 2199 } else { 2200 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2201 if (!new_page) 2202 goto oom; 2203 cow_user_page(new_page, old_page, address, vma); 2204 } 2205 __SetPageUptodate(new_page); 2206 2207 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) 2208 goto oom_free_new; 2209 2210 mmun_start = address & PAGE_MASK; 2211 mmun_end = mmun_start + PAGE_SIZE; 2212 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2213 2214 /* 2215 * Re-check the pte - we dropped the lock 2216 */ 2217 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2218 if (likely(pte_same(*page_table, orig_pte))) { 2219 if (old_page) { 2220 if (!PageAnon(old_page)) { 2221 dec_mm_counter_fast(mm, MM_FILEPAGES); 2222 inc_mm_counter_fast(mm, MM_ANONPAGES); 2223 } 2224 } else 2225 inc_mm_counter_fast(mm, MM_ANONPAGES); 2226 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2227 entry = mk_pte(new_page, vma->vm_page_prot); 2228 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2229 /* 2230 * Clear the pte entry and flush it first, before updating the 2231 * pte with the new entry. This will avoid a race condition 2232 * seen in the presence of one thread doing SMC and another 2233 * thread doing COW. 2234 */ 2235 ptep_clear_flush(vma, address, page_table); 2236 page_add_new_anon_rmap(new_page, vma, address); 2237 /* 2238 * We call the notify macro here because, when using secondary 2239 * mmu page tables (such as kvm shadow page tables), we want the 2240 * new page to be mapped directly into the secondary page table. 2241 */ 2242 set_pte_at_notify(mm, address, page_table, entry); 2243 update_mmu_cache(vma, address, page_table); 2244 if (old_page) { 2245 /* 2246 * Only after switching the pte to the new page may 2247 * we remove the mapcount here. Otherwise another 2248 * process may come and find the rmap count decremented 2249 * before the pte is switched to the new page, and 2250 * "reuse" the old page writing into it while our pte 2251 * here still points into it and can be read by other 2252 * threads. 2253 * 2254 * The critical issue is to order this 2255 * page_remove_rmap with the ptp_clear_flush above. 2256 * Those stores are ordered by (if nothing else,) 2257 * the barrier present in the atomic_add_negative 2258 * in page_remove_rmap. 2259 * 2260 * Then the TLB flush in ptep_clear_flush ensures that 2261 * no process can access the old page before the 2262 * decremented mapcount is visible. And the old page 2263 * cannot be reused until after the decremented 2264 * mapcount is visible. So transitively, TLBs to 2265 * old page will be flushed before it can be reused. 2266 */ 2267 page_remove_rmap(old_page); 2268 } 2269 2270 /* Free the old page.. */ 2271 new_page = old_page; 2272 ret |= VM_FAULT_WRITE; 2273 } else 2274 mem_cgroup_uncharge_page(new_page); 2275 2276 if (new_page) 2277 page_cache_release(new_page); 2278 unlock: 2279 pte_unmap_unlock(page_table, ptl); 2280 if (mmun_end > mmun_start) 2281 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2282 if (old_page) { 2283 /* 2284 * Don't let another task, with possibly unlocked vma, 2285 * keep the mlocked page. 2286 */ 2287 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2288 lock_page(old_page); /* LRU manipulation */ 2289 munlock_vma_page(old_page); 2290 unlock_page(old_page); 2291 } 2292 page_cache_release(old_page); 2293 } 2294 return ret; 2295 oom_free_new: 2296 page_cache_release(new_page); 2297 oom: 2298 if (old_page) 2299 page_cache_release(old_page); 2300 return VM_FAULT_OOM; 2301 } 2302 2303 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2304 unsigned long start_addr, unsigned long end_addr, 2305 struct zap_details *details) 2306 { 2307 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2308 } 2309 2310 static inline void unmap_mapping_range_tree(struct rb_root *root, 2311 struct zap_details *details) 2312 { 2313 struct vm_area_struct *vma; 2314 pgoff_t vba, vea, zba, zea; 2315 2316 vma_interval_tree_foreach(vma, root, 2317 details->first_index, details->last_index) { 2318 2319 vba = vma->vm_pgoff; 2320 vea = vba + vma_pages(vma) - 1; 2321 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2322 zba = details->first_index; 2323 if (zba < vba) 2324 zba = vba; 2325 zea = details->last_index; 2326 if (zea > vea) 2327 zea = vea; 2328 2329 unmap_mapping_range_vma(vma, 2330 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2331 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2332 details); 2333 } 2334 } 2335 2336 static inline void unmap_mapping_range_list(struct list_head *head, 2337 struct zap_details *details) 2338 { 2339 struct vm_area_struct *vma; 2340 2341 /* 2342 * In nonlinear VMAs there is no correspondence between virtual address 2343 * offset and file offset. So we must perform an exhaustive search 2344 * across *all* the pages in each nonlinear VMA, not just the pages 2345 * whose virtual address lies outside the file truncation point. 2346 */ 2347 list_for_each_entry(vma, head, shared.nonlinear) { 2348 details->nonlinear_vma = vma; 2349 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); 2350 } 2351 } 2352 2353 /** 2354 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2355 * @mapping: the address space containing mmaps to be unmapped. 2356 * @holebegin: byte in first page to unmap, relative to the start of 2357 * the underlying file. This will be rounded down to a PAGE_SIZE 2358 * boundary. Note that this is different from truncate_pagecache(), which 2359 * must keep the partial page. In contrast, we must get rid of 2360 * partial pages. 2361 * @holelen: size of prospective hole in bytes. This will be rounded 2362 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2363 * end of the file. 2364 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2365 * but 0 when invalidating pagecache, don't throw away private data. 2366 */ 2367 void unmap_mapping_range(struct address_space *mapping, 2368 loff_t const holebegin, loff_t const holelen, int even_cows) 2369 { 2370 struct zap_details details; 2371 pgoff_t hba = holebegin >> PAGE_SHIFT; 2372 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2373 2374 /* Check for overflow. */ 2375 if (sizeof(holelen) > sizeof(hlen)) { 2376 long long holeend = 2377 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2378 if (holeend & ~(long long)ULONG_MAX) 2379 hlen = ULONG_MAX - hba + 1; 2380 } 2381 2382 details.check_mapping = even_cows? NULL: mapping; 2383 details.nonlinear_vma = NULL; 2384 details.first_index = hba; 2385 details.last_index = hba + hlen - 1; 2386 if (details.last_index < details.first_index) 2387 details.last_index = ULONG_MAX; 2388 2389 2390 mutex_lock(&mapping->i_mmap_mutex); 2391 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) 2392 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2393 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2394 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2395 mutex_unlock(&mapping->i_mmap_mutex); 2396 } 2397 EXPORT_SYMBOL(unmap_mapping_range); 2398 2399 /* 2400 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2401 * but allow concurrent faults), and pte mapped but not yet locked. 2402 * We return with mmap_sem still held, but pte unmapped and unlocked. 2403 */ 2404 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2405 unsigned long address, pte_t *page_table, pmd_t *pmd, 2406 unsigned int flags, pte_t orig_pte) 2407 { 2408 spinlock_t *ptl; 2409 struct page *page, *swapcache; 2410 swp_entry_t entry; 2411 pte_t pte; 2412 int locked; 2413 struct mem_cgroup *ptr; 2414 int exclusive = 0; 2415 int ret = 0; 2416 2417 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2418 goto out; 2419 2420 entry = pte_to_swp_entry(orig_pte); 2421 if (unlikely(non_swap_entry(entry))) { 2422 if (is_migration_entry(entry)) { 2423 migration_entry_wait(mm, pmd, address); 2424 } else if (is_hwpoison_entry(entry)) { 2425 ret = VM_FAULT_HWPOISON; 2426 } else { 2427 print_bad_pte(vma, address, orig_pte, NULL); 2428 ret = VM_FAULT_SIGBUS; 2429 } 2430 goto out; 2431 } 2432 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2433 page = lookup_swap_cache(entry); 2434 if (!page) { 2435 page = swapin_readahead(entry, 2436 GFP_HIGHUSER_MOVABLE, vma, address); 2437 if (!page) { 2438 /* 2439 * Back out if somebody else faulted in this pte 2440 * while we released the pte lock. 2441 */ 2442 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2443 if (likely(pte_same(*page_table, orig_pte))) 2444 ret = VM_FAULT_OOM; 2445 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2446 goto unlock; 2447 } 2448 2449 /* Had to read the page from swap area: Major fault */ 2450 ret = VM_FAULT_MAJOR; 2451 count_vm_event(PGMAJFAULT); 2452 mem_cgroup_count_vm_event(mm, PGMAJFAULT); 2453 } else if (PageHWPoison(page)) { 2454 /* 2455 * hwpoisoned dirty swapcache pages are kept for killing 2456 * owner processes (which may be unknown at hwpoison time) 2457 */ 2458 ret = VM_FAULT_HWPOISON; 2459 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2460 swapcache = page; 2461 goto out_release; 2462 } 2463 2464 swapcache = page; 2465 locked = lock_page_or_retry(page, mm, flags); 2466 2467 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2468 if (!locked) { 2469 ret |= VM_FAULT_RETRY; 2470 goto out_release; 2471 } 2472 2473 /* 2474 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2475 * release the swapcache from under us. The page pin, and pte_same 2476 * test below, are not enough to exclude that. Even if it is still 2477 * swapcache, we need to check that the page's swap has not changed. 2478 */ 2479 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 2480 goto out_page; 2481 2482 page = ksm_might_need_to_copy(page, vma, address); 2483 if (unlikely(!page)) { 2484 ret = VM_FAULT_OOM; 2485 page = swapcache; 2486 goto out_page; 2487 } 2488 2489 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 2490 ret = VM_FAULT_OOM; 2491 goto out_page; 2492 } 2493 2494 /* 2495 * Back out if somebody else already faulted in this pte. 2496 */ 2497 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2498 if (unlikely(!pte_same(*page_table, orig_pte))) 2499 goto out_nomap; 2500 2501 if (unlikely(!PageUptodate(page))) { 2502 ret = VM_FAULT_SIGBUS; 2503 goto out_nomap; 2504 } 2505 2506 /* 2507 * The page isn't present yet, go ahead with the fault. 2508 * 2509 * Be careful about the sequence of operations here. 2510 * To get its accounting right, reuse_swap_page() must be called 2511 * while the page is counted on swap but not yet in mapcount i.e. 2512 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2513 * must be called after the swap_free(), or it will never succeed. 2514 * Because delete_from_swap_page() may be called by reuse_swap_page(), 2515 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 2516 * in page->private. In this case, a record in swap_cgroup is silently 2517 * discarded at swap_free(). 2518 */ 2519 2520 inc_mm_counter_fast(mm, MM_ANONPAGES); 2521 dec_mm_counter_fast(mm, MM_SWAPENTS); 2522 pte = mk_pte(page, vma->vm_page_prot); 2523 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 2524 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2525 flags &= ~FAULT_FLAG_WRITE; 2526 ret |= VM_FAULT_WRITE; 2527 exclusive = 1; 2528 } 2529 flush_icache_page(vma, page); 2530 if (pte_swp_soft_dirty(orig_pte)) 2531 pte = pte_mksoft_dirty(pte); 2532 set_pte_at(mm, address, page_table, pte); 2533 if (page == swapcache) 2534 do_page_add_anon_rmap(page, vma, address, exclusive); 2535 else /* ksm created a completely new copy */ 2536 page_add_new_anon_rmap(page, vma, address); 2537 /* It's better to call commit-charge after rmap is established */ 2538 mem_cgroup_commit_charge_swapin(page, ptr); 2539 2540 swap_free(entry); 2541 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 2542 try_to_free_swap(page); 2543 unlock_page(page); 2544 if (page != swapcache) { 2545 /* 2546 * Hold the lock to avoid the swap entry to be reused 2547 * until we take the PT lock for the pte_same() check 2548 * (to avoid false positives from pte_same). For 2549 * further safety release the lock after the swap_free 2550 * so that the swap count won't change under a 2551 * parallel locked swapcache. 2552 */ 2553 unlock_page(swapcache); 2554 page_cache_release(swapcache); 2555 } 2556 2557 if (flags & FAULT_FLAG_WRITE) { 2558 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2559 if (ret & VM_FAULT_ERROR) 2560 ret &= VM_FAULT_ERROR; 2561 goto out; 2562 } 2563 2564 /* No need to invalidate - it was non-present before */ 2565 update_mmu_cache(vma, address, page_table); 2566 unlock: 2567 pte_unmap_unlock(page_table, ptl); 2568 out: 2569 return ret; 2570 out_nomap: 2571 mem_cgroup_cancel_charge_swapin(ptr); 2572 pte_unmap_unlock(page_table, ptl); 2573 out_page: 2574 unlock_page(page); 2575 out_release: 2576 page_cache_release(page); 2577 if (page != swapcache) { 2578 unlock_page(swapcache); 2579 page_cache_release(swapcache); 2580 } 2581 return ret; 2582 } 2583 2584 /* 2585 * This is like a special single-page "expand_{down|up}wards()", 2586 * except we must first make sure that 'address{-|+}PAGE_SIZE' 2587 * doesn't hit another vma. 2588 */ 2589 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 2590 { 2591 address &= PAGE_MASK; 2592 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 2593 struct vm_area_struct *prev = vma->vm_prev; 2594 2595 /* 2596 * Is there a mapping abutting this one below? 2597 * 2598 * That's only ok if it's the same stack mapping 2599 * that has gotten split.. 2600 */ 2601 if (prev && prev->vm_end == address) 2602 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 2603 2604 expand_downwards(vma, address - PAGE_SIZE); 2605 } 2606 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 2607 struct vm_area_struct *next = vma->vm_next; 2608 2609 /* As VM_GROWSDOWN but s/below/above/ */ 2610 if (next && next->vm_start == address + PAGE_SIZE) 2611 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 2612 2613 expand_upwards(vma, address + PAGE_SIZE); 2614 } 2615 return 0; 2616 } 2617 2618 /* 2619 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2620 * but allow concurrent faults), and pte mapped but not yet locked. 2621 * We return with mmap_sem still held, but pte unmapped and unlocked. 2622 */ 2623 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2624 unsigned long address, pte_t *page_table, pmd_t *pmd, 2625 unsigned int flags) 2626 { 2627 struct page *page; 2628 spinlock_t *ptl; 2629 pte_t entry; 2630 2631 pte_unmap(page_table); 2632 2633 /* Check if we need to add a guard page to the stack */ 2634 if (check_stack_guard_page(vma, address) < 0) 2635 return VM_FAULT_SIGBUS; 2636 2637 /* Use the zero-page for reads */ 2638 if (!(flags & FAULT_FLAG_WRITE)) { 2639 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 2640 vma->vm_page_prot)); 2641 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2642 if (!pte_none(*page_table)) 2643 goto unlock; 2644 goto setpte; 2645 } 2646 2647 /* Allocate our own private page. */ 2648 if (unlikely(anon_vma_prepare(vma))) 2649 goto oom; 2650 page = alloc_zeroed_user_highpage_movable(vma, address); 2651 if (!page) 2652 goto oom; 2653 /* 2654 * The memory barrier inside __SetPageUptodate makes sure that 2655 * preceeding stores to the page contents become visible before 2656 * the set_pte_at() write. 2657 */ 2658 __SetPageUptodate(page); 2659 2660 if (mem_cgroup_charge_anon(page, mm, GFP_KERNEL)) 2661 goto oom_free_page; 2662 2663 entry = mk_pte(page, vma->vm_page_prot); 2664 if (vma->vm_flags & VM_WRITE) 2665 entry = pte_mkwrite(pte_mkdirty(entry)); 2666 2667 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2668 if (!pte_none(*page_table)) 2669 goto release; 2670 2671 inc_mm_counter_fast(mm, MM_ANONPAGES); 2672 page_add_new_anon_rmap(page, vma, address); 2673 setpte: 2674 set_pte_at(mm, address, page_table, entry); 2675 2676 /* No need to invalidate - it was non-present before */ 2677 update_mmu_cache(vma, address, page_table); 2678 unlock: 2679 pte_unmap_unlock(page_table, ptl); 2680 return 0; 2681 release: 2682 mem_cgroup_uncharge_page(page); 2683 page_cache_release(page); 2684 goto unlock; 2685 oom_free_page: 2686 page_cache_release(page); 2687 oom: 2688 return VM_FAULT_OOM; 2689 } 2690 2691 static int __do_fault(struct vm_area_struct *vma, unsigned long address, 2692 pgoff_t pgoff, unsigned int flags, struct page **page) 2693 { 2694 struct vm_fault vmf; 2695 int ret; 2696 2697 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2698 vmf.pgoff = pgoff; 2699 vmf.flags = flags; 2700 vmf.page = NULL; 2701 2702 ret = vma->vm_ops->fault(vma, &vmf); 2703 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2704 return ret; 2705 2706 if (unlikely(PageHWPoison(vmf.page))) { 2707 if (ret & VM_FAULT_LOCKED) 2708 unlock_page(vmf.page); 2709 page_cache_release(vmf.page); 2710 return VM_FAULT_HWPOISON; 2711 } 2712 2713 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2714 lock_page(vmf.page); 2715 else 2716 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page); 2717 2718 *page = vmf.page; 2719 return ret; 2720 } 2721 2722 /** 2723 * do_set_pte - setup new PTE entry for given page and add reverse page mapping. 2724 * 2725 * @vma: virtual memory area 2726 * @address: user virtual address 2727 * @page: page to map 2728 * @pte: pointer to target page table entry 2729 * @write: true, if new entry is writable 2730 * @anon: true, if it's anonymous page 2731 * 2732 * Caller must hold page table lock relevant for @pte. 2733 * 2734 * Target users are page handler itself and implementations of 2735 * vm_ops->map_pages. 2736 */ 2737 void do_set_pte(struct vm_area_struct *vma, unsigned long address, 2738 struct page *page, pte_t *pte, bool write, bool anon) 2739 { 2740 pte_t entry; 2741 2742 flush_icache_page(vma, page); 2743 entry = mk_pte(page, vma->vm_page_prot); 2744 if (write) 2745 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2746 else if (pte_file(*pte) && pte_file_soft_dirty(*pte)) 2747 pte_mksoft_dirty(entry); 2748 if (anon) { 2749 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 2750 page_add_new_anon_rmap(page, vma, address); 2751 } else { 2752 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES); 2753 page_add_file_rmap(page); 2754 } 2755 set_pte_at(vma->vm_mm, address, pte, entry); 2756 2757 /* no need to invalidate: a not-present page won't be cached */ 2758 update_mmu_cache(vma, address, pte); 2759 } 2760 2761 static unsigned long fault_around_bytes = 65536; 2762 2763 /* 2764 * fault_around_pages() and fault_around_mask() round down fault_around_bytes 2765 * to nearest page order. It's what do_fault_around() expects to see. 2766 */ 2767 static inline unsigned long fault_around_pages(void) 2768 { 2769 return rounddown_pow_of_two(fault_around_bytes) / PAGE_SIZE; 2770 } 2771 2772 static inline unsigned long fault_around_mask(void) 2773 { 2774 return ~(rounddown_pow_of_two(fault_around_bytes) - 1) & PAGE_MASK; 2775 } 2776 2777 2778 #ifdef CONFIG_DEBUG_FS 2779 static int fault_around_bytes_get(void *data, u64 *val) 2780 { 2781 *val = fault_around_bytes; 2782 return 0; 2783 } 2784 2785 static int fault_around_bytes_set(void *data, u64 val) 2786 { 2787 if (val / PAGE_SIZE > PTRS_PER_PTE) 2788 return -EINVAL; 2789 fault_around_bytes = val; 2790 return 0; 2791 } 2792 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops, 2793 fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); 2794 2795 static int __init fault_around_debugfs(void) 2796 { 2797 void *ret; 2798 2799 ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL, 2800 &fault_around_bytes_fops); 2801 if (!ret) 2802 pr_warn("Failed to create fault_around_bytes in debugfs"); 2803 return 0; 2804 } 2805 late_initcall(fault_around_debugfs); 2806 #endif 2807 2808 /* 2809 * do_fault_around() tries to map few pages around the fault address. The hope 2810 * is that the pages will be needed soon and this will lower the number of 2811 * faults to handle. 2812 * 2813 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's 2814 * not ready to be mapped: not up-to-date, locked, etc. 2815 * 2816 * This function is called with the page table lock taken. In the split ptlock 2817 * case the page table lock only protects only those entries which belong to 2818 * the page table corresponding to the fault address. 2819 * 2820 * This function doesn't cross the VMA boundaries, in order to call map_pages() 2821 * only once. 2822 * 2823 * fault_around_pages() defines how many pages we'll try to map. 2824 * do_fault_around() expects it to return a power of two less than or equal to 2825 * PTRS_PER_PTE. 2826 * 2827 * The virtual address of the area that we map is naturally aligned to the 2828 * fault_around_pages() value (and therefore to page order). This way it's 2829 * easier to guarantee that we don't cross page table boundaries. 2830 */ 2831 static void do_fault_around(struct vm_area_struct *vma, unsigned long address, 2832 pte_t *pte, pgoff_t pgoff, unsigned int flags) 2833 { 2834 unsigned long start_addr; 2835 pgoff_t max_pgoff; 2836 struct vm_fault vmf; 2837 int off; 2838 2839 start_addr = max(address & fault_around_mask(), vma->vm_start); 2840 off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 2841 pte -= off; 2842 pgoff -= off; 2843 2844 /* 2845 * max_pgoff is either end of page table or end of vma 2846 * or fault_around_pages() from pgoff, depending what is nearest. 2847 */ 2848 max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 2849 PTRS_PER_PTE - 1; 2850 max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1, 2851 pgoff + fault_around_pages() - 1); 2852 2853 /* Check if it makes any sense to call ->map_pages */ 2854 while (!pte_none(*pte)) { 2855 if (++pgoff > max_pgoff) 2856 return; 2857 start_addr += PAGE_SIZE; 2858 if (start_addr >= vma->vm_end) 2859 return; 2860 pte++; 2861 } 2862 2863 vmf.virtual_address = (void __user *) start_addr; 2864 vmf.pte = pte; 2865 vmf.pgoff = pgoff; 2866 vmf.max_pgoff = max_pgoff; 2867 vmf.flags = flags; 2868 vma->vm_ops->map_pages(vma, &vmf); 2869 } 2870 2871 static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2872 unsigned long address, pmd_t *pmd, 2873 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2874 { 2875 struct page *fault_page; 2876 spinlock_t *ptl; 2877 pte_t *pte; 2878 int ret = 0; 2879 2880 /* 2881 * Let's call ->map_pages() first and use ->fault() as fallback 2882 * if page by the offset is not ready to be mapped (cold cache or 2883 * something). 2884 */ 2885 if (vma->vm_ops->map_pages && fault_around_pages() > 1) { 2886 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2887 do_fault_around(vma, address, pte, pgoff, flags); 2888 if (!pte_same(*pte, orig_pte)) 2889 goto unlock_out; 2890 pte_unmap_unlock(pte, ptl); 2891 } 2892 2893 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2894 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2895 return ret; 2896 2897 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2898 if (unlikely(!pte_same(*pte, orig_pte))) { 2899 pte_unmap_unlock(pte, ptl); 2900 unlock_page(fault_page); 2901 page_cache_release(fault_page); 2902 return ret; 2903 } 2904 do_set_pte(vma, address, fault_page, pte, false, false); 2905 unlock_page(fault_page); 2906 unlock_out: 2907 pte_unmap_unlock(pte, ptl); 2908 return ret; 2909 } 2910 2911 static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2912 unsigned long address, pmd_t *pmd, 2913 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2914 { 2915 struct page *fault_page, *new_page; 2916 spinlock_t *ptl; 2917 pte_t *pte; 2918 int ret; 2919 2920 if (unlikely(anon_vma_prepare(vma))) 2921 return VM_FAULT_OOM; 2922 2923 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2924 if (!new_page) 2925 return VM_FAULT_OOM; 2926 2927 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) { 2928 page_cache_release(new_page); 2929 return VM_FAULT_OOM; 2930 } 2931 2932 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2933 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2934 goto uncharge_out; 2935 2936 copy_user_highpage(new_page, fault_page, address, vma); 2937 __SetPageUptodate(new_page); 2938 2939 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2940 if (unlikely(!pte_same(*pte, orig_pte))) { 2941 pte_unmap_unlock(pte, ptl); 2942 unlock_page(fault_page); 2943 page_cache_release(fault_page); 2944 goto uncharge_out; 2945 } 2946 do_set_pte(vma, address, new_page, pte, true, true); 2947 pte_unmap_unlock(pte, ptl); 2948 unlock_page(fault_page); 2949 page_cache_release(fault_page); 2950 return ret; 2951 uncharge_out: 2952 mem_cgroup_uncharge_page(new_page); 2953 page_cache_release(new_page); 2954 return ret; 2955 } 2956 2957 static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2958 unsigned long address, pmd_t *pmd, 2959 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2960 { 2961 struct page *fault_page; 2962 struct address_space *mapping; 2963 spinlock_t *ptl; 2964 pte_t *pte; 2965 int dirtied = 0; 2966 int ret, tmp; 2967 2968 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2969 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2970 return ret; 2971 2972 /* 2973 * Check if the backing address space wants to know that the page is 2974 * about to become writable 2975 */ 2976 if (vma->vm_ops->page_mkwrite) { 2977 unlock_page(fault_page); 2978 tmp = do_page_mkwrite(vma, fault_page, address); 2979 if (unlikely(!tmp || 2980 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2981 page_cache_release(fault_page); 2982 return tmp; 2983 } 2984 } 2985 2986 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2987 if (unlikely(!pte_same(*pte, orig_pte))) { 2988 pte_unmap_unlock(pte, ptl); 2989 unlock_page(fault_page); 2990 page_cache_release(fault_page); 2991 return ret; 2992 } 2993 do_set_pte(vma, address, fault_page, pte, true, false); 2994 pte_unmap_unlock(pte, ptl); 2995 2996 if (set_page_dirty(fault_page)) 2997 dirtied = 1; 2998 mapping = fault_page->mapping; 2999 unlock_page(fault_page); 3000 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { 3001 /* 3002 * Some device drivers do not set page.mapping but still 3003 * dirty their pages 3004 */ 3005 balance_dirty_pages_ratelimited(mapping); 3006 } 3007 3008 /* file_update_time outside page_lock */ 3009 if (vma->vm_file && !vma->vm_ops->page_mkwrite) 3010 file_update_time(vma->vm_file); 3011 3012 return ret; 3013 } 3014 3015 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3016 unsigned long address, pte_t *page_table, pmd_t *pmd, 3017 unsigned int flags, pte_t orig_pte) 3018 { 3019 pgoff_t pgoff = (((address & PAGE_MASK) 3020 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3021 3022 pte_unmap(page_table); 3023 if (!(flags & FAULT_FLAG_WRITE)) 3024 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3025 orig_pte); 3026 if (!(vma->vm_flags & VM_SHARED)) 3027 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3028 orig_pte); 3029 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3030 } 3031 3032 /* 3033 * Fault of a previously existing named mapping. Repopulate the pte 3034 * from the encoded file_pte if possible. This enables swappable 3035 * nonlinear vmas. 3036 * 3037 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3038 * but allow concurrent faults), and pte mapped but not yet locked. 3039 * We return with mmap_sem still held, but pte unmapped and unlocked. 3040 */ 3041 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3042 unsigned long address, pte_t *page_table, pmd_t *pmd, 3043 unsigned int flags, pte_t orig_pte) 3044 { 3045 pgoff_t pgoff; 3046 3047 flags |= FAULT_FLAG_NONLINEAR; 3048 3049 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3050 return 0; 3051 3052 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3053 /* 3054 * Page table corrupted: show pte and kill process. 3055 */ 3056 print_bad_pte(vma, address, orig_pte, NULL); 3057 return VM_FAULT_SIGBUS; 3058 } 3059 3060 pgoff = pte_to_pgoff(orig_pte); 3061 if (!(flags & FAULT_FLAG_WRITE)) 3062 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3063 orig_pte); 3064 if (!(vma->vm_flags & VM_SHARED)) 3065 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3066 orig_pte); 3067 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3068 } 3069 3070 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3071 unsigned long addr, int page_nid, 3072 int *flags) 3073 { 3074 get_page(page); 3075 3076 count_vm_numa_event(NUMA_HINT_FAULTS); 3077 if (page_nid == numa_node_id()) { 3078 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3079 *flags |= TNF_FAULT_LOCAL; 3080 } 3081 3082 return mpol_misplaced(page, vma, addr); 3083 } 3084 3085 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3086 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) 3087 { 3088 struct page *page = NULL; 3089 spinlock_t *ptl; 3090 int page_nid = -1; 3091 int last_cpupid; 3092 int target_nid; 3093 bool migrated = false; 3094 int flags = 0; 3095 3096 /* 3097 * The "pte" at this point cannot be used safely without 3098 * validation through pte_unmap_same(). It's of NUMA type but 3099 * the pfn may be screwed if the read is non atomic. 3100 * 3101 * ptep_modify_prot_start is not called as this is clearing 3102 * the _PAGE_NUMA bit and it is not really expected that there 3103 * would be concurrent hardware modifications to the PTE. 3104 */ 3105 ptl = pte_lockptr(mm, pmd); 3106 spin_lock(ptl); 3107 if (unlikely(!pte_same(*ptep, pte))) { 3108 pte_unmap_unlock(ptep, ptl); 3109 goto out; 3110 } 3111 3112 pte = pte_mknonnuma(pte); 3113 set_pte_at(mm, addr, ptep, pte); 3114 update_mmu_cache(vma, addr, ptep); 3115 3116 page = vm_normal_page(vma, addr, pte); 3117 if (!page) { 3118 pte_unmap_unlock(ptep, ptl); 3119 return 0; 3120 } 3121 BUG_ON(is_zero_pfn(page_to_pfn(page))); 3122 3123 /* 3124 * Avoid grouping on DSO/COW pages in specific and RO pages 3125 * in general, RO pages shouldn't hurt as much anyway since 3126 * they can be in shared cache state. 3127 */ 3128 if (!pte_write(pte)) 3129 flags |= TNF_NO_GROUP; 3130 3131 /* 3132 * Flag if the page is shared between multiple address spaces. This 3133 * is later used when determining whether to group tasks together 3134 */ 3135 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 3136 flags |= TNF_SHARED; 3137 3138 last_cpupid = page_cpupid_last(page); 3139 page_nid = page_to_nid(page); 3140 target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags); 3141 pte_unmap_unlock(ptep, ptl); 3142 if (target_nid == -1) { 3143 put_page(page); 3144 goto out; 3145 } 3146 3147 /* Migrate to the requested node */ 3148 migrated = migrate_misplaced_page(page, vma, target_nid); 3149 if (migrated) { 3150 page_nid = target_nid; 3151 flags |= TNF_MIGRATED; 3152 } 3153 3154 out: 3155 if (page_nid != -1) 3156 task_numa_fault(last_cpupid, page_nid, 1, flags); 3157 return 0; 3158 } 3159 3160 /* 3161 * These routines also need to handle stuff like marking pages dirty 3162 * and/or accessed for architectures that don't do it in hardware (most 3163 * RISC architectures). The early dirtying is also good on the i386. 3164 * 3165 * There is also a hook called "update_mmu_cache()" that architectures 3166 * with external mmu caches can use to update those (ie the Sparc or 3167 * PowerPC hashed page tables that act as extended TLBs). 3168 * 3169 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3170 * but allow concurrent faults), and pte mapped but not yet locked. 3171 * We return with mmap_sem still held, but pte unmapped and unlocked. 3172 */ 3173 static int handle_pte_fault(struct mm_struct *mm, 3174 struct vm_area_struct *vma, unsigned long address, 3175 pte_t *pte, pmd_t *pmd, unsigned int flags) 3176 { 3177 pte_t entry; 3178 spinlock_t *ptl; 3179 3180 entry = *pte; 3181 if (!pte_present(entry)) { 3182 if (pte_none(entry)) { 3183 if (vma->vm_ops) { 3184 if (likely(vma->vm_ops->fault)) 3185 return do_linear_fault(mm, vma, address, 3186 pte, pmd, flags, entry); 3187 } 3188 return do_anonymous_page(mm, vma, address, 3189 pte, pmd, flags); 3190 } 3191 if (pte_file(entry)) 3192 return do_nonlinear_fault(mm, vma, address, 3193 pte, pmd, flags, entry); 3194 return do_swap_page(mm, vma, address, 3195 pte, pmd, flags, entry); 3196 } 3197 3198 if (pte_numa(entry)) 3199 return do_numa_page(mm, vma, address, entry, pte, pmd); 3200 3201 ptl = pte_lockptr(mm, pmd); 3202 spin_lock(ptl); 3203 if (unlikely(!pte_same(*pte, entry))) 3204 goto unlock; 3205 if (flags & FAULT_FLAG_WRITE) { 3206 if (!pte_write(entry)) 3207 return do_wp_page(mm, vma, address, 3208 pte, pmd, ptl, entry); 3209 entry = pte_mkdirty(entry); 3210 } 3211 entry = pte_mkyoung(entry); 3212 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3213 update_mmu_cache(vma, address, pte); 3214 } else { 3215 /* 3216 * This is needed only for protection faults but the arch code 3217 * is not yet telling us if this is a protection fault or not. 3218 * This still avoids useless tlb flushes for .text page faults 3219 * with threads. 3220 */ 3221 if (flags & FAULT_FLAG_WRITE) 3222 flush_tlb_fix_spurious_fault(vma, address); 3223 } 3224 unlock: 3225 pte_unmap_unlock(pte, ptl); 3226 return 0; 3227 } 3228 3229 /* 3230 * By the time we get here, we already hold the mm semaphore 3231 */ 3232 static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3233 unsigned long address, unsigned int flags) 3234 { 3235 pgd_t *pgd; 3236 pud_t *pud; 3237 pmd_t *pmd; 3238 pte_t *pte; 3239 3240 if (unlikely(is_vm_hugetlb_page(vma))) 3241 return hugetlb_fault(mm, vma, address, flags); 3242 3243 pgd = pgd_offset(mm, address); 3244 pud = pud_alloc(mm, pgd, address); 3245 if (!pud) 3246 return VM_FAULT_OOM; 3247 pmd = pmd_alloc(mm, pud, address); 3248 if (!pmd) 3249 return VM_FAULT_OOM; 3250 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3251 int ret = VM_FAULT_FALLBACK; 3252 if (!vma->vm_ops) 3253 ret = do_huge_pmd_anonymous_page(mm, vma, address, 3254 pmd, flags); 3255 if (!(ret & VM_FAULT_FALLBACK)) 3256 return ret; 3257 } else { 3258 pmd_t orig_pmd = *pmd; 3259 int ret; 3260 3261 barrier(); 3262 if (pmd_trans_huge(orig_pmd)) { 3263 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3264 3265 /* 3266 * If the pmd is splitting, return and retry the 3267 * the fault. Alternative: wait until the split 3268 * is done, and goto retry. 3269 */ 3270 if (pmd_trans_splitting(orig_pmd)) 3271 return 0; 3272 3273 if (pmd_numa(orig_pmd)) 3274 return do_huge_pmd_numa_page(mm, vma, address, 3275 orig_pmd, pmd); 3276 3277 if (dirty && !pmd_write(orig_pmd)) { 3278 ret = do_huge_pmd_wp_page(mm, vma, address, pmd, 3279 orig_pmd); 3280 if (!(ret & VM_FAULT_FALLBACK)) 3281 return ret; 3282 } else { 3283 huge_pmd_set_accessed(mm, vma, address, pmd, 3284 orig_pmd, dirty); 3285 return 0; 3286 } 3287 } 3288 } 3289 3290 /* 3291 * Use __pte_alloc instead of pte_alloc_map, because we can't 3292 * run pte_offset_map on the pmd, if an huge pmd could 3293 * materialize from under us from a different thread. 3294 */ 3295 if (unlikely(pmd_none(*pmd)) && 3296 unlikely(__pte_alloc(mm, vma, pmd, address))) 3297 return VM_FAULT_OOM; 3298 /* if an huge pmd materialized from under us just retry later */ 3299 if (unlikely(pmd_trans_huge(*pmd))) 3300 return 0; 3301 /* 3302 * A regular pmd is established and it can't morph into a huge pmd 3303 * from under us anymore at this point because we hold the mmap_sem 3304 * read mode and khugepaged takes it in write mode. So now it's 3305 * safe to run pte_offset_map(). 3306 */ 3307 pte = pte_offset_map(pmd, address); 3308 3309 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3310 } 3311 3312 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3313 unsigned long address, unsigned int flags) 3314 { 3315 int ret; 3316 3317 __set_current_state(TASK_RUNNING); 3318 3319 count_vm_event(PGFAULT); 3320 mem_cgroup_count_vm_event(mm, PGFAULT); 3321 3322 /* do counter updates before entering really critical section. */ 3323 check_sync_rss_stat(current); 3324 3325 /* 3326 * Enable the memcg OOM handling for faults triggered in user 3327 * space. Kernel faults are handled more gracefully. 3328 */ 3329 if (flags & FAULT_FLAG_USER) 3330 mem_cgroup_oom_enable(); 3331 3332 ret = __handle_mm_fault(mm, vma, address, flags); 3333 3334 if (flags & FAULT_FLAG_USER) { 3335 mem_cgroup_oom_disable(); 3336 /* 3337 * The task may have entered a memcg OOM situation but 3338 * if the allocation error was handled gracefully (no 3339 * VM_FAULT_OOM), there is no need to kill anything. 3340 * Just clean up the OOM state peacefully. 3341 */ 3342 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 3343 mem_cgroup_oom_synchronize(false); 3344 } 3345 3346 return ret; 3347 } 3348 3349 #ifndef __PAGETABLE_PUD_FOLDED 3350 /* 3351 * Allocate page upper directory. 3352 * We've already handled the fast-path in-line. 3353 */ 3354 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3355 { 3356 pud_t *new = pud_alloc_one(mm, address); 3357 if (!new) 3358 return -ENOMEM; 3359 3360 smp_wmb(); /* See comment in __pte_alloc */ 3361 3362 spin_lock(&mm->page_table_lock); 3363 if (pgd_present(*pgd)) /* Another has populated it */ 3364 pud_free(mm, new); 3365 else 3366 pgd_populate(mm, pgd, new); 3367 spin_unlock(&mm->page_table_lock); 3368 return 0; 3369 } 3370 #endif /* __PAGETABLE_PUD_FOLDED */ 3371 3372 #ifndef __PAGETABLE_PMD_FOLDED 3373 /* 3374 * Allocate page middle directory. 3375 * We've already handled the fast-path in-line. 3376 */ 3377 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3378 { 3379 pmd_t *new = pmd_alloc_one(mm, address); 3380 if (!new) 3381 return -ENOMEM; 3382 3383 smp_wmb(); /* See comment in __pte_alloc */ 3384 3385 spin_lock(&mm->page_table_lock); 3386 #ifndef __ARCH_HAS_4LEVEL_HACK 3387 if (pud_present(*pud)) /* Another has populated it */ 3388 pmd_free(mm, new); 3389 else 3390 pud_populate(mm, pud, new); 3391 #else 3392 if (pgd_present(*pud)) /* Another has populated it */ 3393 pmd_free(mm, new); 3394 else 3395 pgd_populate(mm, pud, new); 3396 #endif /* __ARCH_HAS_4LEVEL_HACK */ 3397 spin_unlock(&mm->page_table_lock); 3398 return 0; 3399 } 3400 #endif /* __PAGETABLE_PMD_FOLDED */ 3401 3402 #if !defined(__HAVE_ARCH_GATE_AREA) 3403 3404 #if defined(AT_SYSINFO_EHDR) 3405 static struct vm_area_struct gate_vma; 3406 3407 static int __init gate_vma_init(void) 3408 { 3409 gate_vma.vm_mm = NULL; 3410 gate_vma.vm_start = FIXADDR_USER_START; 3411 gate_vma.vm_end = FIXADDR_USER_END; 3412 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3413 gate_vma.vm_page_prot = __P101; 3414 3415 return 0; 3416 } 3417 __initcall(gate_vma_init); 3418 #endif 3419 3420 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 3421 { 3422 #ifdef AT_SYSINFO_EHDR 3423 return &gate_vma; 3424 #else 3425 return NULL; 3426 #endif 3427 } 3428 3429 int in_gate_area_no_mm(unsigned long addr) 3430 { 3431 #ifdef AT_SYSINFO_EHDR 3432 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3433 return 1; 3434 #endif 3435 return 0; 3436 } 3437 3438 #endif /* __HAVE_ARCH_GATE_AREA */ 3439 3440 static int __follow_pte(struct mm_struct *mm, unsigned long address, 3441 pte_t **ptepp, spinlock_t **ptlp) 3442 { 3443 pgd_t *pgd; 3444 pud_t *pud; 3445 pmd_t *pmd; 3446 pte_t *ptep; 3447 3448 pgd = pgd_offset(mm, address); 3449 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3450 goto out; 3451 3452 pud = pud_offset(pgd, address); 3453 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3454 goto out; 3455 3456 pmd = pmd_offset(pud, address); 3457 VM_BUG_ON(pmd_trans_huge(*pmd)); 3458 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3459 goto out; 3460 3461 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3462 if (pmd_huge(*pmd)) 3463 goto out; 3464 3465 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3466 if (!ptep) 3467 goto out; 3468 if (!pte_present(*ptep)) 3469 goto unlock; 3470 *ptepp = ptep; 3471 return 0; 3472 unlock: 3473 pte_unmap_unlock(ptep, *ptlp); 3474 out: 3475 return -EINVAL; 3476 } 3477 3478 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 3479 pte_t **ptepp, spinlock_t **ptlp) 3480 { 3481 int res; 3482 3483 /* (void) is needed to make gcc happy */ 3484 (void) __cond_lock(*ptlp, 3485 !(res = __follow_pte(mm, address, ptepp, ptlp))); 3486 return res; 3487 } 3488 3489 /** 3490 * follow_pfn - look up PFN at a user virtual address 3491 * @vma: memory mapping 3492 * @address: user virtual address 3493 * @pfn: location to store found PFN 3494 * 3495 * Only IO mappings and raw PFN mappings are allowed. 3496 * 3497 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3498 */ 3499 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3500 unsigned long *pfn) 3501 { 3502 int ret = -EINVAL; 3503 spinlock_t *ptl; 3504 pte_t *ptep; 3505 3506 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3507 return ret; 3508 3509 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3510 if (ret) 3511 return ret; 3512 *pfn = pte_pfn(*ptep); 3513 pte_unmap_unlock(ptep, ptl); 3514 return 0; 3515 } 3516 EXPORT_SYMBOL(follow_pfn); 3517 3518 #ifdef CONFIG_HAVE_IOREMAP_PROT 3519 int follow_phys(struct vm_area_struct *vma, 3520 unsigned long address, unsigned int flags, 3521 unsigned long *prot, resource_size_t *phys) 3522 { 3523 int ret = -EINVAL; 3524 pte_t *ptep, pte; 3525 spinlock_t *ptl; 3526 3527 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3528 goto out; 3529 3530 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3531 goto out; 3532 pte = *ptep; 3533 3534 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3535 goto unlock; 3536 3537 *prot = pgprot_val(pte_pgprot(pte)); 3538 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3539 3540 ret = 0; 3541 unlock: 3542 pte_unmap_unlock(ptep, ptl); 3543 out: 3544 return ret; 3545 } 3546 3547 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3548 void *buf, int len, int write) 3549 { 3550 resource_size_t phys_addr; 3551 unsigned long prot = 0; 3552 void __iomem *maddr; 3553 int offset = addr & (PAGE_SIZE-1); 3554 3555 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3556 return -EINVAL; 3557 3558 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3559 if (write) 3560 memcpy_toio(maddr + offset, buf, len); 3561 else 3562 memcpy_fromio(buf, maddr + offset, len); 3563 iounmap(maddr); 3564 3565 return len; 3566 } 3567 EXPORT_SYMBOL_GPL(generic_access_phys); 3568 #endif 3569 3570 /* 3571 * Access another process' address space as given in mm. If non-NULL, use the 3572 * given task for page fault accounting. 3573 */ 3574 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 3575 unsigned long addr, void *buf, int len, int write) 3576 { 3577 struct vm_area_struct *vma; 3578 void *old_buf = buf; 3579 3580 down_read(&mm->mmap_sem); 3581 /* ignore errors, just check how much was successfully transferred */ 3582 while (len) { 3583 int bytes, ret, offset; 3584 void *maddr; 3585 struct page *page = NULL; 3586 3587 ret = get_user_pages(tsk, mm, addr, 1, 3588 write, 1, &page, &vma); 3589 if (ret <= 0) { 3590 /* 3591 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3592 * we can access using slightly different code. 3593 */ 3594 #ifdef CONFIG_HAVE_IOREMAP_PROT 3595 vma = find_vma(mm, addr); 3596 if (!vma || vma->vm_start > addr) 3597 break; 3598 if (vma->vm_ops && vma->vm_ops->access) 3599 ret = vma->vm_ops->access(vma, addr, buf, 3600 len, write); 3601 if (ret <= 0) 3602 #endif 3603 break; 3604 bytes = ret; 3605 } else { 3606 bytes = len; 3607 offset = addr & (PAGE_SIZE-1); 3608 if (bytes > PAGE_SIZE-offset) 3609 bytes = PAGE_SIZE-offset; 3610 3611 maddr = kmap(page); 3612 if (write) { 3613 copy_to_user_page(vma, page, addr, 3614 maddr + offset, buf, bytes); 3615 set_page_dirty_lock(page); 3616 } else { 3617 copy_from_user_page(vma, page, addr, 3618 buf, maddr + offset, bytes); 3619 } 3620 kunmap(page); 3621 page_cache_release(page); 3622 } 3623 len -= bytes; 3624 buf += bytes; 3625 addr += bytes; 3626 } 3627 up_read(&mm->mmap_sem); 3628 3629 return buf - old_buf; 3630 } 3631 3632 /** 3633 * access_remote_vm - access another process' address space 3634 * @mm: the mm_struct of the target address space 3635 * @addr: start address to access 3636 * @buf: source or destination buffer 3637 * @len: number of bytes to transfer 3638 * @write: whether the access is a write 3639 * 3640 * The caller must hold a reference on @mm. 3641 */ 3642 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 3643 void *buf, int len, int write) 3644 { 3645 return __access_remote_vm(NULL, mm, addr, buf, len, write); 3646 } 3647 3648 /* 3649 * Access another process' address space. 3650 * Source/target buffer must be kernel space, 3651 * Do not walk the page table directly, use get_user_pages 3652 */ 3653 int access_process_vm(struct task_struct *tsk, unsigned long addr, 3654 void *buf, int len, int write) 3655 { 3656 struct mm_struct *mm; 3657 int ret; 3658 3659 mm = get_task_mm(tsk); 3660 if (!mm) 3661 return 0; 3662 3663 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 3664 mmput(mm); 3665 3666 return ret; 3667 } 3668 3669 /* 3670 * Print the name of a VMA. 3671 */ 3672 void print_vma_addr(char *prefix, unsigned long ip) 3673 { 3674 struct mm_struct *mm = current->mm; 3675 struct vm_area_struct *vma; 3676 3677 /* 3678 * Do not print if we are in atomic 3679 * contexts (in exception stacks, etc.): 3680 */ 3681 if (preempt_count()) 3682 return; 3683 3684 down_read(&mm->mmap_sem); 3685 vma = find_vma(mm, ip); 3686 if (vma && vma->vm_file) { 3687 struct file *f = vma->vm_file; 3688 char *buf = (char *)__get_free_page(GFP_KERNEL); 3689 if (buf) { 3690 char *p; 3691 3692 p = d_path(&f->f_path, buf, PAGE_SIZE); 3693 if (IS_ERR(p)) 3694 p = "?"; 3695 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 3696 vma->vm_start, 3697 vma->vm_end - vma->vm_start); 3698 free_page((unsigned long)buf); 3699 } 3700 } 3701 up_read(&mm->mmap_sem); 3702 } 3703 3704 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 3705 void might_fault(void) 3706 { 3707 /* 3708 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3709 * holding the mmap_sem, this is safe because kernel memory doesn't 3710 * get paged out, therefore we'll never actually fault, and the 3711 * below annotations will generate false positives. 3712 */ 3713 if (segment_eq(get_fs(), KERNEL_DS)) 3714 return; 3715 3716 /* 3717 * it would be nicer only to annotate paths which are not under 3718 * pagefault_disable, however that requires a larger audit and 3719 * providing helpers like get_user_atomic. 3720 */ 3721 if (in_atomic()) 3722 return; 3723 3724 __might_sleep(__FILE__, __LINE__, 0); 3725 3726 if (current->mm) 3727 might_lock_read(¤t->mm->mmap_sem); 3728 } 3729 EXPORT_SYMBOL(might_fault); 3730 #endif 3731 3732 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 3733 static void clear_gigantic_page(struct page *page, 3734 unsigned long addr, 3735 unsigned int pages_per_huge_page) 3736 { 3737 int i; 3738 struct page *p = page; 3739 3740 might_sleep(); 3741 for (i = 0; i < pages_per_huge_page; 3742 i++, p = mem_map_next(p, page, i)) { 3743 cond_resched(); 3744 clear_user_highpage(p, addr + i * PAGE_SIZE); 3745 } 3746 } 3747 void clear_huge_page(struct page *page, 3748 unsigned long addr, unsigned int pages_per_huge_page) 3749 { 3750 int i; 3751 3752 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3753 clear_gigantic_page(page, addr, pages_per_huge_page); 3754 return; 3755 } 3756 3757 might_sleep(); 3758 for (i = 0; i < pages_per_huge_page; i++) { 3759 cond_resched(); 3760 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 3761 } 3762 } 3763 3764 static void copy_user_gigantic_page(struct page *dst, struct page *src, 3765 unsigned long addr, 3766 struct vm_area_struct *vma, 3767 unsigned int pages_per_huge_page) 3768 { 3769 int i; 3770 struct page *dst_base = dst; 3771 struct page *src_base = src; 3772 3773 for (i = 0; i < pages_per_huge_page; ) { 3774 cond_resched(); 3775 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 3776 3777 i++; 3778 dst = mem_map_next(dst, dst_base, i); 3779 src = mem_map_next(src, src_base, i); 3780 } 3781 } 3782 3783 void copy_user_huge_page(struct page *dst, struct page *src, 3784 unsigned long addr, struct vm_area_struct *vma, 3785 unsigned int pages_per_huge_page) 3786 { 3787 int i; 3788 3789 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3790 copy_user_gigantic_page(dst, src, addr, vma, 3791 pages_per_huge_page); 3792 return; 3793 } 3794 3795 might_sleep(); 3796 for (i = 0; i < pages_per_huge_page; i++) { 3797 cond_resched(); 3798 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 3799 } 3800 } 3801 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 3802 3803 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 3804 3805 static struct kmem_cache *page_ptl_cachep; 3806 3807 void __init ptlock_cache_init(void) 3808 { 3809 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 3810 SLAB_PANIC, NULL); 3811 } 3812 3813 bool ptlock_alloc(struct page *page) 3814 { 3815 spinlock_t *ptl; 3816 3817 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 3818 if (!ptl) 3819 return false; 3820 page->ptl = ptl; 3821 return true; 3822 } 3823 3824 void ptlock_free(struct page *page) 3825 { 3826 kmem_cache_free(page_ptl_cachep, page->ptl); 3827 } 3828 #endif 3829