memory.c revision daa88c8d214ca4ab2f1764b6e503cef4b3cde9b2
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/rmap.h> 49#include <linux/module.h> 50#include <linux/delayacct.h> 51#include <linux/init.h> 52#include <linux/writeback.h> 53 54#include <asm/pgalloc.h> 55#include <asm/uaccess.h> 56#include <asm/tlb.h> 57#include <asm/tlbflush.h> 58#include <asm/pgtable.h> 59 60#include <linux/swapops.h> 61#include <linux/elf.h> 62 63#ifndef CONFIG_NEED_MULTIPLE_NODES 64/* use the per-pgdat data instead for discontigmem - mbligh */ 65unsigned long max_mapnr; 66struct page *mem_map; 67 68EXPORT_SYMBOL(max_mapnr); 69EXPORT_SYMBOL(mem_map); 70#endif 71 72unsigned long num_physpages; 73/* 74 * A number of key systems in x86 including ioremap() rely on the assumption 75 * that high_memory defines the upper bound on direct map memory, then end 76 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 77 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 78 * and ZONE_HIGHMEM. 79 */ 80void * high_memory; 81unsigned long vmalloc_earlyreserve; 82 83EXPORT_SYMBOL(num_physpages); 84EXPORT_SYMBOL(high_memory); 85EXPORT_SYMBOL(vmalloc_earlyreserve); 86 87int randomize_va_space __read_mostly = 1; 88 89static int __init disable_randmaps(char *s) 90{ 91 randomize_va_space = 0; 92 return 1; 93} 94__setup("norandmaps", disable_randmaps); 95 96 97/* 98 * If a p?d_bad entry is found while walking page tables, report 99 * the error, before resetting entry to p?d_none. Usually (but 100 * very seldom) called out from the p?d_none_or_clear_bad macros. 101 */ 102 103void pgd_clear_bad(pgd_t *pgd) 104{ 105 pgd_ERROR(*pgd); 106 pgd_clear(pgd); 107} 108 109void pud_clear_bad(pud_t *pud) 110{ 111 pud_ERROR(*pud); 112 pud_clear(pud); 113} 114 115void pmd_clear_bad(pmd_t *pmd) 116{ 117 pmd_ERROR(*pmd); 118 pmd_clear(pmd); 119} 120 121/* 122 * Note: this doesn't free the actual pages themselves. That 123 * has been handled earlier when unmapping all the memory regions. 124 */ 125static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) 126{ 127 struct page *page = pmd_page(*pmd); 128 pmd_clear(pmd); 129 pte_lock_deinit(page); 130 pte_free_tlb(tlb, page); 131 dec_zone_page_state(page, NR_PAGETABLE); 132 tlb->mm->nr_ptes--; 133} 134 135static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 136 unsigned long addr, unsigned long end, 137 unsigned long floor, unsigned long ceiling) 138{ 139 pmd_t *pmd; 140 unsigned long next; 141 unsigned long start; 142 143 start = addr; 144 pmd = pmd_offset(pud, addr); 145 do { 146 next = pmd_addr_end(addr, end); 147 if (pmd_none_or_clear_bad(pmd)) 148 continue; 149 free_pte_range(tlb, pmd); 150 } while (pmd++, addr = next, addr != end); 151 152 start &= PUD_MASK; 153 if (start < floor) 154 return; 155 if (ceiling) { 156 ceiling &= PUD_MASK; 157 if (!ceiling) 158 return; 159 } 160 if (end - 1 > ceiling - 1) 161 return; 162 163 pmd = pmd_offset(pud, start); 164 pud_clear(pud); 165 pmd_free_tlb(tlb, pmd); 166} 167 168static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 169 unsigned long addr, unsigned long end, 170 unsigned long floor, unsigned long ceiling) 171{ 172 pud_t *pud; 173 unsigned long next; 174 unsigned long start; 175 176 start = addr; 177 pud = pud_offset(pgd, addr); 178 do { 179 next = pud_addr_end(addr, end); 180 if (pud_none_or_clear_bad(pud)) 181 continue; 182 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 183 } while (pud++, addr = next, addr != end); 184 185 start &= PGDIR_MASK; 186 if (start < floor) 187 return; 188 if (ceiling) { 189 ceiling &= PGDIR_MASK; 190 if (!ceiling) 191 return; 192 } 193 if (end - 1 > ceiling - 1) 194 return; 195 196 pud = pud_offset(pgd, start); 197 pgd_clear(pgd); 198 pud_free_tlb(tlb, pud); 199} 200 201/* 202 * This function frees user-level page tables of a process. 203 * 204 * Must be called with pagetable lock held. 205 */ 206void free_pgd_range(struct mmu_gather **tlb, 207 unsigned long addr, unsigned long end, 208 unsigned long floor, unsigned long ceiling) 209{ 210 pgd_t *pgd; 211 unsigned long next; 212 unsigned long start; 213 214 /* 215 * The next few lines have given us lots of grief... 216 * 217 * Why are we testing PMD* at this top level? Because often 218 * there will be no work to do at all, and we'd prefer not to 219 * go all the way down to the bottom just to discover that. 220 * 221 * Why all these "- 1"s? Because 0 represents both the bottom 222 * of the address space and the top of it (using -1 for the 223 * top wouldn't help much: the masks would do the wrong thing). 224 * The rule is that addr 0 and floor 0 refer to the bottom of 225 * the address space, but end 0 and ceiling 0 refer to the top 226 * Comparisons need to use "end - 1" and "ceiling - 1" (though 227 * that end 0 case should be mythical). 228 * 229 * Wherever addr is brought up or ceiling brought down, we must 230 * be careful to reject "the opposite 0" before it confuses the 231 * subsequent tests. But what about where end is brought down 232 * by PMD_SIZE below? no, end can't go down to 0 there. 233 * 234 * Whereas we round start (addr) and ceiling down, by different 235 * masks at different levels, in order to test whether a table 236 * now has no other vmas using it, so can be freed, we don't 237 * bother to round floor or end up - the tests don't need that. 238 */ 239 240 addr &= PMD_MASK; 241 if (addr < floor) { 242 addr += PMD_SIZE; 243 if (!addr) 244 return; 245 } 246 if (ceiling) { 247 ceiling &= PMD_MASK; 248 if (!ceiling) 249 return; 250 } 251 if (end - 1 > ceiling - 1) 252 end -= PMD_SIZE; 253 if (addr > end - 1) 254 return; 255 256 start = addr; 257 pgd = pgd_offset((*tlb)->mm, addr); 258 do { 259 next = pgd_addr_end(addr, end); 260 if (pgd_none_or_clear_bad(pgd)) 261 continue; 262 free_pud_range(*tlb, pgd, addr, next, floor, ceiling); 263 } while (pgd++, addr = next, addr != end); 264 265 if (!(*tlb)->fullmm) 266 flush_tlb_pgtables((*tlb)->mm, start, end); 267} 268 269void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, 270 unsigned long floor, unsigned long ceiling) 271{ 272 while (vma) { 273 struct vm_area_struct *next = vma->vm_next; 274 unsigned long addr = vma->vm_start; 275 276 /* 277 * Hide vma from rmap and vmtruncate before freeing pgtables 278 */ 279 anon_vma_unlink(vma); 280 unlink_file_vma(vma); 281 282 if (is_vm_hugetlb_page(vma)) { 283 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 284 floor, next? next->vm_start: ceiling); 285 } else { 286 /* 287 * Optimization: gather nearby vmas into one call down 288 */ 289 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 290 && !is_vm_hugetlb_page(next)) { 291 vma = next; 292 next = vma->vm_next; 293 anon_vma_unlink(vma); 294 unlink_file_vma(vma); 295 } 296 free_pgd_range(tlb, addr, vma->vm_end, 297 floor, next? next->vm_start: ceiling); 298 } 299 vma = next; 300 } 301} 302 303int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 304{ 305 struct page *new = pte_alloc_one(mm, address); 306 if (!new) 307 return -ENOMEM; 308 309 pte_lock_init(new); 310 spin_lock(&mm->page_table_lock); 311 if (pmd_present(*pmd)) { /* Another has populated it */ 312 pte_lock_deinit(new); 313 pte_free(new); 314 } else { 315 mm->nr_ptes++; 316 inc_zone_page_state(new, NR_PAGETABLE); 317 pmd_populate(mm, pmd, new); 318 } 319 spin_unlock(&mm->page_table_lock); 320 return 0; 321} 322 323int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 324{ 325 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 326 if (!new) 327 return -ENOMEM; 328 329 spin_lock(&init_mm.page_table_lock); 330 if (pmd_present(*pmd)) /* Another has populated it */ 331 pte_free_kernel(new); 332 else 333 pmd_populate_kernel(&init_mm, pmd, new); 334 spin_unlock(&init_mm.page_table_lock); 335 return 0; 336} 337 338static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 339{ 340 if (file_rss) 341 add_mm_counter(mm, file_rss, file_rss); 342 if (anon_rss) 343 add_mm_counter(mm, anon_rss, anon_rss); 344} 345 346/* 347 * This function is called to print an error when a bad pte 348 * is found. For example, we might have a PFN-mapped pte in 349 * a region that doesn't allow it. 350 * 351 * The calling function must still handle the error. 352 */ 353void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr) 354{ 355 printk(KERN_ERR "Bad pte = %08llx, process = %s, " 356 "vm_flags = %lx, vaddr = %lx\n", 357 (long long)pte_val(pte), 358 (vma->vm_mm == current->mm ? current->comm : "???"), 359 vma->vm_flags, vaddr); 360 dump_stack(); 361} 362 363static inline int is_cow_mapping(unsigned int flags) 364{ 365 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 366} 367 368/* 369 * This function gets the "struct page" associated with a pte. 370 * 371 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping 372 * will have each page table entry just pointing to a raw page frame 373 * number, and as far as the VM layer is concerned, those do not have 374 * pages associated with them - even if the PFN might point to memory 375 * that otherwise is perfectly fine and has a "struct page". 376 * 377 * The way we recognize those mappings is through the rules set up 378 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set, 379 * and the vm_pgoff will point to the first PFN mapped: thus every 380 * page that is a raw mapping will always honor the rule 381 * 382 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 383 * 384 * and if that isn't true, the page has been COW'ed (in which case it 385 * _does_ have a "struct page" associated with it even if it is in a 386 * VM_PFNMAP range). 387 */ 388struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) 389{ 390 unsigned long pfn = pte_pfn(pte); 391 392 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 393 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT; 394 if (pfn == vma->vm_pgoff + off) 395 return NULL; 396 if (!is_cow_mapping(vma->vm_flags)) 397 return NULL; 398 } 399 400 /* 401 * Add some anal sanity checks for now. Eventually, 402 * we should just do "return pfn_to_page(pfn)", but 403 * in the meantime we check that we get a valid pfn, 404 * and that the resulting page looks ok. 405 */ 406 if (unlikely(!pfn_valid(pfn))) { 407 print_bad_pte(vma, pte, addr); 408 return NULL; 409 } 410 411 /* 412 * NOTE! We still have PageReserved() pages in the page 413 * tables. 414 * 415 * The PAGE_ZERO() pages and various VDSO mappings can 416 * cause them to exist. 417 */ 418 return pfn_to_page(pfn); 419} 420 421/* 422 * copy one vm_area from one task to the other. Assumes the page tables 423 * already present in the new task to be cleared in the whole range 424 * covered by this vma. 425 */ 426 427static inline void 428copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 429 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 430 unsigned long addr, int *rss) 431{ 432 unsigned long vm_flags = vma->vm_flags; 433 pte_t pte = *src_pte; 434 struct page *page; 435 436 /* pte contains position in swap or file, so copy. */ 437 if (unlikely(!pte_present(pte))) { 438 if (!pte_file(pte)) { 439 swp_entry_t entry = pte_to_swp_entry(pte); 440 441 swap_duplicate(entry); 442 /* make sure dst_mm is on swapoff's mmlist. */ 443 if (unlikely(list_empty(&dst_mm->mmlist))) { 444 spin_lock(&mmlist_lock); 445 if (list_empty(&dst_mm->mmlist)) 446 list_add(&dst_mm->mmlist, 447 &src_mm->mmlist); 448 spin_unlock(&mmlist_lock); 449 } 450 if (is_write_migration_entry(entry) && 451 is_cow_mapping(vm_flags)) { 452 /* 453 * COW mappings require pages in both parent 454 * and child to be set to read. 455 */ 456 make_migration_entry_read(&entry); 457 pte = swp_entry_to_pte(entry); 458 set_pte_at(src_mm, addr, src_pte, pte); 459 } 460 } 461 goto out_set_pte; 462 } 463 464 /* 465 * If it's a COW mapping, write protect it both 466 * in the parent and the child 467 */ 468 if (is_cow_mapping(vm_flags)) { 469 ptep_set_wrprotect(src_mm, addr, src_pte); 470 pte = pte_wrprotect(pte); 471 } 472 473 /* 474 * If it's a shared mapping, mark it clean in 475 * the child 476 */ 477 if (vm_flags & VM_SHARED) 478 pte = pte_mkclean(pte); 479 pte = pte_mkold(pte); 480 481 page = vm_normal_page(vma, addr, pte); 482 if (page) { 483 get_page(page); 484 page_dup_rmap(page); 485 rss[!!PageAnon(page)]++; 486 } 487 488out_set_pte: 489 set_pte_at(dst_mm, addr, dst_pte, pte); 490} 491 492static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 493 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 494 unsigned long addr, unsigned long end) 495{ 496 pte_t *src_pte, *dst_pte; 497 spinlock_t *src_ptl, *dst_ptl; 498 int progress = 0; 499 int rss[2]; 500 501again: 502 rss[1] = rss[0] = 0; 503 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 504 if (!dst_pte) 505 return -ENOMEM; 506 src_pte = pte_offset_map_nested(src_pmd, addr); 507 src_ptl = pte_lockptr(src_mm, src_pmd); 508 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 509 arch_enter_lazy_mmu_mode(); 510 511 do { 512 /* 513 * We are holding two locks at this point - either of them 514 * could generate latencies in another task on another CPU. 515 */ 516 if (progress >= 32) { 517 progress = 0; 518 if (need_resched() || 519 need_lockbreak(src_ptl) || 520 need_lockbreak(dst_ptl)) 521 break; 522 } 523 if (pte_none(*src_pte)) { 524 progress++; 525 continue; 526 } 527 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 528 progress += 8; 529 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 530 531 arch_leave_lazy_mmu_mode(); 532 spin_unlock(src_ptl); 533 pte_unmap_nested(src_pte - 1); 534 add_mm_rss(dst_mm, rss[0], rss[1]); 535 pte_unmap_unlock(dst_pte - 1, dst_ptl); 536 cond_resched(); 537 if (addr != end) 538 goto again; 539 return 0; 540} 541 542static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 543 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 544 unsigned long addr, unsigned long end) 545{ 546 pmd_t *src_pmd, *dst_pmd; 547 unsigned long next; 548 549 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 550 if (!dst_pmd) 551 return -ENOMEM; 552 src_pmd = pmd_offset(src_pud, addr); 553 do { 554 next = pmd_addr_end(addr, end); 555 if (pmd_none_or_clear_bad(src_pmd)) 556 continue; 557 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 558 vma, addr, next)) 559 return -ENOMEM; 560 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 561 return 0; 562} 563 564static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 565 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 566 unsigned long addr, unsigned long end) 567{ 568 pud_t *src_pud, *dst_pud; 569 unsigned long next; 570 571 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 572 if (!dst_pud) 573 return -ENOMEM; 574 src_pud = pud_offset(src_pgd, addr); 575 do { 576 next = pud_addr_end(addr, end); 577 if (pud_none_or_clear_bad(src_pud)) 578 continue; 579 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 580 vma, addr, next)) 581 return -ENOMEM; 582 } while (dst_pud++, src_pud++, addr = next, addr != end); 583 return 0; 584} 585 586int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 587 struct vm_area_struct *vma) 588{ 589 pgd_t *src_pgd, *dst_pgd; 590 unsigned long next; 591 unsigned long addr = vma->vm_start; 592 unsigned long end = vma->vm_end; 593 594 /* 595 * Don't copy ptes where a page fault will fill them correctly. 596 * Fork becomes much lighter when there are big shared or private 597 * readonly mappings. The tradeoff is that copy_page_range is more 598 * efficient than faulting. 599 */ 600 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 601 if (!vma->anon_vma) 602 return 0; 603 } 604 605 if (is_vm_hugetlb_page(vma)) 606 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 607 608 dst_pgd = pgd_offset(dst_mm, addr); 609 src_pgd = pgd_offset(src_mm, addr); 610 do { 611 next = pgd_addr_end(addr, end); 612 if (pgd_none_or_clear_bad(src_pgd)) 613 continue; 614 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 615 vma, addr, next)) 616 return -ENOMEM; 617 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 618 return 0; 619} 620 621static unsigned long zap_pte_range(struct mmu_gather *tlb, 622 struct vm_area_struct *vma, pmd_t *pmd, 623 unsigned long addr, unsigned long end, 624 long *zap_work, struct zap_details *details) 625{ 626 struct mm_struct *mm = tlb->mm; 627 pte_t *pte; 628 spinlock_t *ptl; 629 int file_rss = 0; 630 int anon_rss = 0; 631 632 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 633 arch_enter_lazy_mmu_mode(); 634 do { 635 pte_t ptent = *pte; 636 if (pte_none(ptent)) { 637 (*zap_work)--; 638 continue; 639 } 640 641 (*zap_work) -= PAGE_SIZE; 642 643 if (pte_present(ptent)) { 644 struct page *page; 645 646 page = vm_normal_page(vma, addr, ptent); 647 if (unlikely(details) && page) { 648 /* 649 * unmap_shared_mapping_pages() wants to 650 * invalidate cache without truncating: 651 * unmap shared but keep private pages. 652 */ 653 if (details->check_mapping && 654 details->check_mapping != page->mapping) 655 continue; 656 /* 657 * Each page->index must be checked when 658 * invalidating or truncating nonlinear. 659 */ 660 if (details->nonlinear_vma && 661 (page->index < details->first_index || 662 page->index > details->last_index)) 663 continue; 664 } 665 ptent = ptep_get_and_clear_full(mm, addr, pte, 666 tlb->fullmm); 667 tlb_remove_tlb_entry(tlb, pte, addr); 668 if (unlikely(!page)) 669 continue; 670 if (unlikely(details) && details->nonlinear_vma 671 && linear_page_index(details->nonlinear_vma, 672 addr) != page->index) 673 set_pte_at(mm, addr, pte, 674 pgoff_to_pte(page->index)); 675 if (PageAnon(page)) 676 anon_rss--; 677 else { 678 if (pte_dirty(ptent)) 679 set_page_dirty(page); 680 if (pte_young(ptent)) 681 SetPageReferenced(page); 682 file_rss--; 683 } 684 page_remove_rmap(page, vma); 685 tlb_remove_page(tlb, page); 686 continue; 687 } 688 /* 689 * If details->check_mapping, we leave swap entries; 690 * if details->nonlinear_vma, we leave file entries. 691 */ 692 if (unlikely(details)) 693 continue; 694 if (!pte_file(ptent)) 695 free_swap_and_cache(pte_to_swp_entry(ptent)); 696 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 697 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 698 699 add_mm_rss(mm, file_rss, anon_rss); 700 arch_leave_lazy_mmu_mode(); 701 pte_unmap_unlock(pte - 1, ptl); 702 703 return addr; 704} 705 706static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 707 struct vm_area_struct *vma, pud_t *pud, 708 unsigned long addr, unsigned long end, 709 long *zap_work, struct zap_details *details) 710{ 711 pmd_t *pmd; 712 unsigned long next; 713 714 pmd = pmd_offset(pud, addr); 715 do { 716 next = pmd_addr_end(addr, end); 717 if (pmd_none_or_clear_bad(pmd)) { 718 (*zap_work)--; 719 continue; 720 } 721 next = zap_pte_range(tlb, vma, pmd, addr, next, 722 zap_work, details); 723 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 724 725 return addr; 726} 727 728static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 729 struct vm_area_struct *vma, pgd_t *pgd, 730 unsigned long addr, unsigned long end, 731 long *zap_work, struct zap_details *details) 732{ 733 pud_t *pud; 734 unsigned long next; 735 736 pud = pud_offset(pgd, addr); 737 do { 738 next = pud_addr_end(addr, end); 739 if (pud_none_or_clear_bad(pud)) { 740 (*zap_work)--; 741 continue; 742 } 743 next = zap_pmd_range(tlb, vma, pud, addr, next, 744 zap_work, details); 745 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 746 747 return addr; 748} 749 750static unsigned long unmap_page_range(struct mmu_gather *tlb, 751 struct vm_area_struct *vma, 752 unsigned long addr, unsigned long end, 753 long *zap_work, struct zap_details *details) 754{ 755 pgd_t *pgd; 756 unsigned long next; 757 758 if (details && !details->check_mapping && !details->nonlinear_vma) 759 details = NULL; 760 761 BUG_ON(addr >= end); 762 tlb_start_vma(tlb, vma); 763 pgd = pgd_offset(vma->vm_mm, addr); 764 do { 765 next = pgd_addr_end(addr, end); 766 if (pgd_none_or_clear_bad(pgd)) { 767 (*zap_work)--; 768 continue; 769 } 770 next = zap_pud_range(tlb, vma, pgd, addr, next, 771 zap_work, details); 772 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 773 tlb_end_vma(tlb, vma); 774 775 return addr; 776} 777 778#ifdef CONFIG_PREEMPT 779# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 780#else 781/* No preempt: go for improved straight-line efficiency */ 782# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 783#endif 784 785/** 786 * unmap_vmas - unmap a range of memory covered by a list of vma's 787 * @tlbp: address of the caller's struct mmu_gather 788 * @vma: the starting vma 789 * @start_addr: virtual address at which to start unmapping 790 * @end_addr: virtual address at which to end unmapping 791 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 792 * @details: details of nonlinear truncation or shared cache invalidation 793 * 794 * Returns the end address of the unmapping (restart addr if interrupted). 795 * 796 * Unmap all pages in the vma list. 797 * 798 * We aim to not hold locks for too long (for scheduling latency reasons). 799 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 800 * return the ending mmu_gather to the caller. 801 * 802 * Only addresses between `start' and `end' will be unmapped. 803 * 804 * The VMA list must be sorted in ascending virtual address order. 805 * 806 * unmap_vmas() assumes that the caller will flush the whole unmapped address 807 * range after unmap_vmas() returns. So the only responsibility here is to 808 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 809 * drops the lock and schedules. 810 */ 811unsigned long unmap_vmas(struct mmu_gather **tlbp, 812 struct vm_area_struct *vma, unsigned long start_addr, 813 unsigned long end_addr, unsigned long *nr_accounted, 814 struct zap_details *details) 815{ 816 long zap_work = ZAP_BLOCK_SIZE; 817 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 818 int tlb_start_valid = 0; 819 unsigned long start = start_addr; 820 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 821 int fullmm = (*tlbp)->fullmm; 822 823 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 824 unsigned long end; 825 826 start = max(vma->vm_start, start_addr); 827 if (start >= vma->vm_end) 828 continue; 829 end = min(vma->vm_end, end_addr); 830 if (end <= vma->vm_start) 831 continue; 832 833 if (vma->vm_flags & VM_ACCOUNT) 834 *nr_accounted += (end - start) >> PAGE_SHIFT; 835 836 while (start != end) { 837 if (!tlb_start_valid) { 838 tlb_start = start; 839 tlb_start_valid = 1; 840 } 841 842 if (unlikely(is_vm_hugetlb_page(vma))) { 843 unmap_hugepage_range(vma, start, end); 844 zap_work -= (end - start) / 845 (HPAGE_SIZE / PAGE_SIZE); 846 start = end; 847 } else 848 start = unmap_page_range(*tlbp, vma, 849 start, end, &zap_work, details); 850 851 if (zap_work > 0) { 852 BUG_ON(start != end); 853 break; 854 } 855 856 tlb_finish_mmu(*tlbp, tlb_start, start); 857 858 if (need_resched() || 859 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 860 if (i_mmap_lock) { 861 *tlbp = NULL; 862 goto out; 863 } 864 cond_resched(); 865 } 866 867 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 868 tlb_start_valid = 0; 869 zap_work = ZAP_BLOCK_SIZE; 870 } 871 } 872out: 873 return start; /* which is now the end (or restart) address */ 874} 875 876/** 877 * zap_page_range - remove user pages in a given range 878 * @vma: vm_area_struct holding the applicable pages 879 * @address: starting address of pages to zap 880 * @size: number of bytes to zap 881 * @details: details of nonlinear truncation or shared cache invalidation 882 */ 883unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 884 unsigned long size, struct zap_details *details) 885{ 886 struct mm_struct *mm = vma->vm_mm; 887 struct mmu_gather *tlb; 888 unsigned long end = address + size; 889 unsigned long nr_accounted = 0; 890 891 lru_add_drain(); 892 tlb = tlb_gather_mmu(mm, 0); 893 update_hiwater_rss(mm); 894 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 895 if (tlb) 896 tlb_finish_mmu(tlb, address, end); 897 return end; 898} 899 900/* 901 * Do a quick page-table lookup for a single page. 902 */ 903struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 904 unsigned int flags) 905{ 906 pgd_t *pgd; 907 pud_t *pud; 908 pmd_t *pmd; 909 pte_t *ptep, pte; 910 spinlock_t *ptl; 911 struct page *page; 912 struct mm_struct *mm = vma->vm_mm; 913 914 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 915 if (!IS_ERR(page)) { 916 BUG_ON(flags & FOLL_GET); 917 goto out; 918 } 919 920 page = NULL; 921 pgd = pgd_offset(mm, address); 922 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 923 goto no_page_table; 924 925 pud = pud_offset(pgd, address); 926 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 927 goto no_page_table; 928 929 pmd = pmd_offset(pud, address); 930 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 931 goto no_page_table; 932 933 if (pmd_huge(*pmd)) { 934 BUG_ON(flags & FOLL_GET); 935 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 936 goto out; 937 } 938 939 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 940 if (!ptep) 941 goto out; 942 943 pte = *ptep; 944 if (!pte_present(pte)) 945 goto unlock; 946 if ((flags & FOLL_WRITE) && !pte_write(pte)) 947 goto unlock; 948 page = vm_normal_page(vma, address, pte); 949 if (unlikely(!page)) 950 goto unlock; 951 952 if (flags & FOLL_GET) 953 get_page(page); 954 if (flags & FOLL_TOUCH) { 955 if ((flags & FOLL_WRITE) && 956 !pte_dirty(pte) && !PageDirty(page)) 957 set_page_dirty(page); 958 mark_page_accessed(page); 959 } 960unlock: 961 pte_unmap_unlock(ptep, ptl); 962out: 963 return page; 964 965no_page_table: 966 /* 967 * When core dumping an enormous anonymous area that nobody 968 * has touched so far, we don't want to allocate page tables. 969 */ 970 if (flags & FOLL_ANON) { 971 page = ZERO_PAGE(address); 972 if (flags & FOLL_GET) 973 get_page(page); 974 BUG_ON(flags & FOLL_WRITE); 975 } 976 return page; 977} 978 979int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 980 unsigned long start, int len, int write, int force, 981 struct page **pages, struct vm_area_struct **vmas) 982{ 983 int i; 984 unsigned int vm_flags; 985 986 /* 987 * Require read or write permissions. 988 * If 'force' is set, we only require the "MAY" flags. 989 */ 990 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 991 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 992 i = 0; 993 994 do { 995 struct vm_area_struct *vma; 996 unsigned int foll_flags; 997 998 vma = find_extend_vma(mm, start); 999 if (!vma && in_gate_area(tsk, start)) { 1000 unsigned long pg = start & PAGE_MASK; 1001 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 1002 pgd_t *pgd; 1003 pud_t *pud; 1004 pmd_t *pmd; 1005 pte_t *pte; 1006 if (write) /* user gate pages are read-only */ 1007 return i ? : -EFAULT; 1008 if (pg > TASK_SIZE) 1009 pgd = pgd_offset_k(pg); 1010 else 1011 pgd = pgd_offset_gate(mm, pg); 1012 BUG_ON(pgd_none(*pgd)); 1013 pud = pud_offset(pgd, pg); 1014 BUG_ON(pud_none(*pud)); 1015 pmd = pmd_offset(pud, pg); 1016 if (pmd_none(*pmd)) 1017 return i ? : -EFAULT; 1018 pte = pte_offset_map(pmd, pg); 1019 if (pte_none(*pte)) { 1020 pte_unmap(pte); 1021 return i ? : -EFAULT; 1022 } 1023 if (pages) { 1024 struct page *page = vm_normal_page(gate_vma, start, *pte); 1025 pages[i] = page; 1026 if (page) 1027 get_page(page); 1028 } 1029 pte_unmap(pte); 1030 if (vmas) 1031 vmas[i] = gate_vma; 1032 i++; 1033 start += PAGE_SIZE; 1034 len--; 1035 continue; 1036 } 1037 1038 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP)) 1039 || !(vm_flags & vma->vm_flags)) 1040 return i ? : -EFAULT; 1041 1042 if (is_vm_hugetlb_page(vma)) { 1043 i = follow_hugetlb_page(mm, vma, pages, vmas, 1044 &start, &len, i); 1045 continue; 1046 } 1047 1048 foll_flags = FOLL_TOUCH; 1049 if (pages) 1050 foll_flags |= FOLL_GET; 1051 if (!write && !(vma->vm_flags & VM_LOCKED) && 1052 (!vma->vm_ops || !vma->vm_ops->nopage)) 1053 foll_flags |= FOLL_ANON; 1054 1055 do { 1056 struct page *page; 1057 1058 if (write) 1059 foll_flags |= FOLL_WRITE; 1060 1061 cond_resched(); 1062 while (!(page = follow_page(vma, start, foll_flags))) { 1063 int ret; 1064 ret = __handle_mm_fault(mm, vma, start, 1065 foll_flags & FOLL_WRITE); 1066 /* 1067 * The VM_FAULT_WRITE bit tells us that do_wp_page has 1068 * broken COW when necessary, even if maybe_mkwrite 1069 * decided not to set pte_write. We can thus safely do 1070 * subsequent page lookups as if they were reads. 1071 */ 1072 if (ret & VM_FAULT_WRITE) 1073 foll_flags &= ~FOLL_WRITE; 1074 1075 switch (ret & ~VM_FAULT_WRITE) { 1076 case VM_FAULT_MINOR: 1077 tsk->min_flt++; 1078 break; 1079 case VM_FAULT_MAJOR: 1080 tsk->maj_flt++; 1081 break; 1082 case VM_FAULT_SIGBUS: 1083 return i ? i : -EFAULT; 1084 case VM_FAULT_OOM: 1085 return i ? i : -ENOMEM; 1086 default: 1087 BUG(); 1088 } 1089 cond_resched(); 1090 } 1091 if (pages) { 1092 pages[i] = page; 1093 1094 flush_anon_page(vma, page, start); 1095 flush_dcache_page(page); 1096 } 1097 if (vmas) 1098 vmas[i] = vma; 1099 i++; 1100 start += PAGE_SIZE; 1101 len--; 1102 } while (len && start < vma->vm_end); 1103 } while (len); 1104 return i; 1105} 1106EXPORT_SYMBOL(get_user_pages); 1107 1108static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1109 unsigned long addr, unsigned long end, pgprot_t prot) 1110{ 1111 pte_t *pte; 1112 spinlock_t *ptl; 1113 int err = 0; 1114 1115 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1116 if (!pte) 1117 return -EAGAIN; 1118 arch_enter_lazy_mmu_mode(); 1119 do { 1120 struct page *page = ZERO_PAGE(addr); 1121 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot)); 1122 1123 if (unlikely(!pte_none(*pte))) { 1124 err = -EEXIST; 1125 pte++; 1126 break; 1127 } 1128 page_cache_get(page); 1129 page_add_file_rmap(page); 1130 inc_mm_counter(mm, file_rss); 1131 set_pte_at(mm, addr, pte, zero_pte); 1132 } while (pte++, addr += PAGE_SIZE, addr != end); 1133 arch_leave_lazy_mmu_mode(); 1134 pte_unmap_unlock(pte - 1, ptl); 1135 return err; 1136} 1137 1138static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, 1139 unsigned long addr, unsigned long end, pgprot_t prot) 1140{ 1141 pmd_t *pmd; 1142 unsigned long next; 1143 int err; 1144 1145 pmd = pmd_alloc(mm, pud, addr); 1146 if (!pmd) 1147 return -EAGAIN; 1148 do { 1149 next = pmd_addr_end(addr, end); 1150 err = zeromap_pte_range(mm, pmd, addr, next, prot); 1151 if (err) 1152 break; 1153 } while (pmd++, addr = next, addr != end); 1154 return err; 1155} 1156 1157static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1158 unsigned long addr, unsigned long end, pgprot_t prot) 1159{ 1160 pud_t *pud; 1161 unsigned long next; 1162 int err; 1163 1164 pud = pud_alloc(mm, pgd, addr); 1165 if (!pud) 1166 return -EAGAIN; 1167 do { 1168 next = pud_addr_end(addr, end); 1169 err = zeromap_pmd_range(mm, pud, addr, next, prot); 1170 if (err) 1171 break; 1172 } while (pud++, addr = next, addr != end); 1173 return err; 1174} 1175 1176int zeromap_page_range(struct vm_area_struct *vma, 1177 unsigned long addr, unsigned long size, pgprot_t prot) 1178{ 1179 pgd_t *pgd; 1180 unsigned long next; 1181 unsigned long end = addr + size; 1182 struct mm_struct *mm = vma->vm_mm; 1183 int err; 1184 1185 BUG_ON(addr >= end); 1186 pgd = pgd_offset(mm, addr); 1187 flush_cache_range(vma, addr, end); 1188 do { 1189 next = pgd_addr_end(addr, end); 1190 err = zeromap_pud_range(mm, pgd, addr, next, prot); 1191 if (err) 1192 break; 1193 } while (pgd++, addr = next, addr != end); 1194 return err; 1195} 1196 1197pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl) 1198{ 1199 pgd_t * pgd = pgd_offset(mm, addr); 1200 pud_t * pud = pud_alloc(mm, pgd, addr); 1201 if (pud) { 1202 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1203 if (pmd) 1204 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1205 } 1206 return NULL; 1207} 1208 1209/* 1210 * This is the old fallback for page remapping. 1211 * 1212 * For historical reasons, it only allows reserved pages. Only 1213 * old drivers should use this, and they needed to mark their 1214 * pages reserved for the old functions anyway. 1215 */ 1216static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot) 1217{ 1218 int retval; 1219 pte_t *pte; 1220 spinlock_t *ptl; 1221 1222 retval = -EINVAL; 1223 if (PageAnon(page)) 1224 goto out; 1225 retval = -ENOMEM; 1226 flush_dcache_page(page); 1227 pte = get_locked_pte(mm, addr, &ptl); 1228 if (!pte) 1229 goto out; 1230 retval = -EBUSY; 1231 if (!pte_none(*pte)) 1232 goto out_unlock; 1233 1234 /* Ok, finally just insert the thing.. */ 1235 get_page(page); 1236 inc_mm_counter(mm, file_rss); 1237 page_add_file_rmap(page); 1238 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1239 1240 retval = 0; 1241out_unlock: 1242 pte_unmap_unlock(pte, ptl); 1243out: 1244 return retval; 1245} 1246 1247/** 1248 * vm_insert_page - insert single page into user vma 1249 * @vma: user vma to map to 1250 * @addr: target user address of this page 1251 * @page: source kernel page 1252 * 1253 * This allows drivers to insert individual pages they've allocated 1254 * into a user vma. 1255 * 1256 * The page has to be a nice clean _individual_ kernel allocation. 1257 * If you allocate a compound page, you need to have marked it as 1258 * such (__GFP_COMP), or manually just split the page up yourself 1259 * (see split_page()). 1260 * 1261 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1262 * took an arbitrary page protection parameter. This doesn't allow 1263 * that. Your vma protection will have to be set up correctly, which 1264 * means that if you want a shared writable mapping, you'd better 1265 * ask for a shared writable mapping! 1266 * 1267 * The page does not need to be reserved. 1268 */ 1269int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page) 1270{ 1271 if (addr < vma->vm_start || addr >= vma->vm_end) 1272 return -EFAULT; 1273 if (!page_count(page)) 1274 return -EINVAL; 1275 vma->vm_flags |= VM_INSERTPAGE; 1276 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot); 1277} 1278EXPORT_SYMBOL(vm_insert_page); 1279 1280/* 1281 * maps a range of physical memory into the requested pages. the old 1282 * mappings are removed. any references to nonexistent pages results 1283 * in null mappings (currently treated as "copy-on-access") 1284 */ 1285static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1286 unsigned long addr, unsigned long end, 1287 unsigned long pfn, pgprot_t prot) 1288{ 1289 pte_t *pte; 1290 spinlock_t *ptl; 1291 1292 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1293 if (!pte) 1294 return -ENOMEM; 1295 arch_enter_lazy_mmu_mode(); 1296 do { 1297 BUG_ON(!pte_none(*pte)); 1298 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1299 pfn++; 1300 } while (pte++, addr += PAGE_SIZE, addr != end); 1301 arch_leave_lazy_mmu_mode(); 1302 pte_unmap_unlock(pte - 1, ptl); 1303 return 0; 1304} 1305 1306static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1307 unsigned long addr, unsigned long end, 1308 unsigned long pfn, pgprot_t prot) 1309{ 1310 pmd_t *pmd; 1311 unsigned long next; 1312 1313 pfn -= addr >> PAGE_SHIFT; 1314 pmd = pmd_alloc(mm, pud, addr); 1315 if (!pmd) 1316 return -ENOMEM; 1317 do { 1318 next = pmd_addr_end(addr, end); 1319 if (remap_pte_range(mm, pmd, addr, next, 1320 pfn + (addr >> PAGE_SHIFT), prot)) 1321 return -ENOMEM; 1322 } while (pmd++, addr = next, addr != end); 1323 return 0; 1324} 1325 1326static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1327 unsigned long addr, unsigned long end, 1328 unsigned long pfn, pgprot_t prot) 1329{ 1330 pud_t *pud; 1331 unsigned long next; 1332 1333 pfn -= addr >> PAGE_SHIFT; 1334 pud = pud_alloc(mm, pgd, addr); 1335 if (!pud) 1336 return -ENOMEM; 1337 do { 1338 next = pud_addr_end(addr, end); 1339 if (remap_pmd_range(mm, pud, addr, next, 1340 pfn + (addr >> PAGE_SHIFT), prot)) 1341 return -ENOMEM; 1342 } while (pud++, addr = next, addr != end); 1343 return 0; 1344} 1345 1346/** 1347 * remap_pfn_range - remap kernel memory to userspace 1348 * @vma: user vma to map to 1349 * @addr: target user address to start at 1350 * @pfn: physical address of kernel memory 1351 * @size: size of map area 1352 * @prot: page protection flags for this mapping 1353 * 1354 * Note: this is only safe if the mm semaphore is held when called. 1355 */ 1356int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1357 unsigned long pfn, unsigned long size, pgprot_t prot) 1358{ 1359 pgd_t *pgd; 1360 unsigned long next; 1361 unsigned long end = addr + PAGE_ALIGN(size); 1362 struct mm_struct *mm = vma->vm_mm; 1363 int err; 1364 1365 /* 1366 * Physically remapped pages are special. Tell the 1367 * rest of the world about it: 1368 * VM_IO tells people not to look at these pages 1369 * (accesses can have side effects). 1370 * VM_RESERVED is specified all over the place, because 1371 * in 2.4 it kept swapout's vma scan off this vma; but 1372 * in 2.6 the LRU scan won't even find its pages, so this 1373 * flag means no more than count its pages in reserved_vm, 1374 * and omit it from core dump, even when VM_IO turned off. 1375 * VM_PFNMAP tells the core MM that the base pages are just 1376 * raw PFN mappings, and do not have a "struct page" associated 1377 * with them. 1378 * 1379 * There's a horrible special case to handle copy-on-write 1380 * behaviour that some programs depend on. We mark the "original" 1381 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1382 */ 1383 if (is_cow_mapping(vma->vm_flags)) { 1384 if (addr != vma->vm_start || end != vma->vm_end) 1385 return -EINVAL; 1386 vma->vm_pgoff = pfn; 1387 } 1388 1389 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1390 1391 BUG_ON(addr >= end); 1392 pfn -= addr >> PAGE_SHIFT; 1393 pgd = pgd_offset(mm, addr); 1394 flush_cache_range(vma, addr, end); 1395 do { 1396 next = pgd_addr_end(addr, end); 1397 err = remap_pud_range(mm, pgd, addr, next, 1398 pfn + (addr >> PAGE_SHIFT), prot); 1399 if (err) 1400 break; 1401 } while (pgd++, addr = next, addr != end); 1402 return err; 1403} 1404EXPORT_SYMBOL(remap_pfn_range); 1405 1406/* 1407 * handle_pte_fault chooses page fault handler according to an entry 1408 * which was read non-atomically. Before making any commitment, on 1409 * those architectures or configurations (e.g. i386 with PAE) which 1410 * might give a mix of unmatched parts, do_swap_page and do_file_page 1411 * must check under lock before unmapping the pte and proceeding 1412 * (but do_wp_page is only called after already making such a check; 1413 * and do_anonymous_page and do_no_page can safely check later on). 1414 */ 1415static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1416 pte_t *page_table, pte_t orig_pte) 1417{ 1418 int same = 1; 1419#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1420 if (sizeof(pte_t) > sizeof(unsigned long)) { 1421 spinlock_t *ptl = pte_lockptr(mm, pmd); 1422 spin_lock(ptl); 1423 same = pte_same(*page_table, orig_pte); 1424 spin_unlock(ptl); 1425 } 1426#endif 1427 pte_unmap(page_table); 1428 return same; 1429} 1430 1431/* 1432 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1433 * servicing faults for write access. In the normal case, do always want 1434 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1435 * that do not have writing enabled, when used by access_process_vm. 1436 */ 1437static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1438{ 1439 if (likely(vma->vm_flags & VM_WRITE)) 1440 pte = pte_mkwrite(pte); 1441 return pte; 1442} 1443 1444static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1445{ 1446 /* 1447 * If the source page was a PFN mapping, we don't have 1448 * a "struct page" for it. We do a best-effort copy by 1449 * just copying from the original user address. If that 1450 * fails, we just zero-fill it. Live with it. 1451 */ 1452 if (unlikely(!src)) { 1453 void *kaddr = kmap_atomic(dst, KM_USER0); 1454 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1455 1456 /* 1457 * This really shouldn't fail, because the page is there 1458 * in the page tables. But it might just be unreadable, 1459 * in which case we just give up and fill the result with 1460 * zeroes. 1461 */ 1462 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1463 memset(kaddr, 0, PAGE_SIZE); 1464 kunmap_atomic(kaddr, KM_USER0); 1465 flush_dcache_page(dst); 1466 return; 1467 1468 } 1469 copy_user_highpage(dst, src, va, vma); 1470} 1471 1472/* 1473 * This routine handles present pages, when users try to write 1474 * to a shared page. It is done by copying the page to a new address 1475 * and decrementing the shared-page counter for the old page. 1476 * 1477 * Note that this routine assumes that the protection checks have been 1478 * done by the caller (the low-level page fault routine in most cases). 1479 * Thus we can safely just mark it writable once we've done any necessary 1480 * COW. 1481 * 1482 * We also mark the page dirty at this point even though the page will 1483 * change only once the write actually happens. This avoids a few races, 1484 * and potentially makes it more efficient. 1485 * 1486 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1487 * but allow concurrent faults), with pte both mapped and locked. 1488 * We return with mmap_sem still held, but pte unmapped and unlocked. 1489 */ 1490static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1491 unsigned long address, pte_t *page_table, pmd_t *pmd, 1492 spinlock_t *ptl, pte_t orig_pte) 1493{ 1494 struct page *old_page, *new_page; 1495 pte_t entry; 1496 int reuse = 0, ret = VM_FAULT_MINOR; 1497 struct page *dirty_page = NULL; 1498 1499 old_page = vm_normal_page(vma, address, orig_pte); 1500 if (!old_page) 1501 goto gotten; 1502 1503 /* 1504 * Take out anonymous pages first, anonymous shared vmas are 1505 * not dirty accountable. 1506 */ 1507 if (PageAnon(old_page)) { 1508 if (!TestSetPageLocked(old_page)) { 1509 reuse = can_share_swap_page(old_page); 1510 unlock_page(old_page); 1511 } 1512 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1513 (VM_WRITE|VM_SHARED))) { 1514 /* 1515 * Only catch write-faults on shared writable pages, 1516 * read-only shared pages can get COWed by 1517 * get_user_pages(.write=1, .force=1). 1518 */ 1519 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 1520 /* 1521 * Notify the address space that the page is about to 1522 * become writable so that it can prohibit this or wait 1523 * for the page to get into an appropriate state. 1524 * 1525 * We do this without the lock held, so that it can 1526 * sleep if it needs to. 1527 */ 1528 page_cache_get(old_page); 1529 pte_unmap_unlock(page_table, ptl); 1530 1531 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0) 1532 goto unwritable_page; 1533 1534 /* 1535 * Since we dropped the lock we need to revalidate 1536 * the PTE as someone else may have changed it. If 1537 * they did, we just return, as we can count on the 1538 * MMU to tell us if they didn't also make it writable. 1539 */ 1540 page_table = pte_offset_map_lock(mm, pmd, address, 1541 &ptl); 1542 page_cache_release(old_page); 1543 if (!pte_same(*page_table, orig_pte)) 1544 goto unlock; 1545 } 1546 dirty_page = old_page; 1547 get_page(dirty_page); 1548 reuse = 1; 1549 } 1550 1551 if (reuse) { 1552 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1553 entry = pte_mkyoung(orig_pte); 1554 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1555 ptep_set_access_flags(vma, address, page_table, entry, 1); 1556 update_mmu_cache(vma, address, entry); 1557 lazy_mmu_prot_update(entry); 1558 ret |= VM_FAULT_WRITE; 1559 goto unlock; 1560 } 1561 1562 /* 1563 * Ok, we need to copy. Oh, well.. 1564 */ 1565 page_cache_get(old_page); 1566gotten: 1567 pte_unmap_unlock(page_table, ptl); 1568 1569 if (unlikely(anon_vma_prepare(vma))) 1570 goto oom; 1571 if (old_page == ZERO_PAGE(address)) { 1572 new_page = alloc_zeroed_user_highpage(vma, address); 1573 if (!new_page) 1574 goto oom; 1575 } else { 1576 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1577 if (!new_page) 1578 goto oom; 1579 cow_user_page(new_page, old_page, address, vma); 1580 } 1581 1582 /* 1583 * Re-check the pte - we dropped the lock 1584 */ 1585 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1586 if (likely(pte_same(*page_table, orig_pte))) { 1587 if (old_page) { 1588 page_remove_rmap(old_page, vma); 1589 if (!PageAnon(old_page)) { 1590 dec_mm_counter(mm, file_rss); 1591 inc_mm_counter(mm, anon_rss); 1592 } 1593 } else 1594 inc_mm_counter(mm, anon_rss); 1595 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1596 entry = mk_pte(new_page, vma->vm_page_prot); 1597 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1598 lazy_mmu_prot_update(entry); 1599 /* 1600 * Clear the pte entry and flush it first, before updating the 1601 * pte with the new entry. This will avoid a race condition 1602 * seen in the presence of one thread doing SMC and another 1603 * thread doing COW. 1604 */ 1605 ptep_clear_flush(vma, address, page_table); 1606 set_pte_at(mm, address, page_table, entry); 1607 update_mmu_cache(vma, address, entry); 1608 lru_cache_add_active(new_page); 1609 page_add_new_anon_rmap(new_page, vma, address); 1610 1611 /* Free the old page.. */ 1612 new_page = old_page; 1613 ret |= VM_FAULT_WRITE; 1614 } 1615 if (new_page) 1616 page_cache_release(new_page); 1617 if (old_page) 1618 page_cache_release(old_page); 1619unlock: 1620 pte_unmap_unlock(page_table, ptl); 1621 if (dirty_page) { 1622 set_page_dirty_balance(dirty_page); 1623 put_page(dirty_page); 1624 } 1625 return ret; 1626oom: 1627 if (old_page) 1628 page_cache_release(old_page); 1629 return VM_FAULT_OOM; 1630 1631unwritable_page: 1632 page_cache_release(old_page); 1633 return VM_FAULT_SIGBUS; 1634} 1635 1636/* 1637 * Helper functions for unmap_mapping_range(). 1638 * 1639 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1640 * 1641 * We have to restart searching the prio_tree whenever we drop the lock, 1642 * since the iterator is only valid while the lock is held, and anyway 1643 * a later vma might be split and reinserted earlier while lock dropped. 1644 * 1645 * The list of nonlinear vmas could be handled more efficiently, using 1646 * a placeholder, but handle it in the same way until a need is shown. 1647 * It is important to search the prio_tree before nonlinear list: a vma 1648 * may become nonlinear and be shifted from prio_tree to nonlinear list 1649 * while the lock is dropped; but never shifted from list to prio_tree. 1650 * 1651 * In order to make forward progress despite restarting the search, 1652 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1653 * quickly skip it next time around. Since the prio_tree search only 1654 * shows us those vmas affected by unmapping the range in question, we 1655 * can't efficiently keep all vmas in step with mapping->truncate_count: 1656 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1657 * mapping->truncate_count and vma->vm_truncate_count are protected by 1658 * i_mmap_lock. 1659 * 1660 * In order to make forward progress despite repeatedly restarting some 1661 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1662 * and restart from that address when we reach that vma again. It might 1663 * have been split or merged, shrunk or extended, but never shifted: so 1664 * restart_addr remains valid so long as it remains in the vma's range. 1665 * unmap_mapping_range forces truncate_count to leap over page-aligned 1666 * values so we can save vma's restart_addr in its truncate_count field. 1667 */ 1668#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1669 1670static void reset_vma_truncate_counts(struct address_space *mapping) 1671{ 1672 struct vm_area_struct *vma; 1673 struct prio_tree_iter iter; 1674 1675 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1676 vma->vm_truncate_count = 0; 1677 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1678 vma->vm_truncate_count = 0; 1679} 1680 1681static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1682 unsigned long start_addr, unsigned long end_addr, 1683 struct zap_details *details) 1684{ 1685 unsigned long restart_addr; 1686 int need_break; 1687 1688again: 1689 restart_addr = vma->vm_truncate_count; 1690 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1691 start_addr = restart_addr; 1692 if (start_addr >= end_addr) { 1693 /* Top of vma has been split off since last time */ 1694 vma->vm_truncate_count = details->truncate_count; 1695 return 0; 1696 } 1697 } 1698 1699 restart_addr = zap_page_range(vma, start_addr, 1700 end_addr - start_addr, details); 1701 need_break = need_resched() || 1702 need_lockbreak(details->i_mmap_lock); 1703 1704 if (restart_addr >= end_addr) { 1705 /* We have now completed this vma: mark it so */ 1706 vma->vm_truncate_count = details->truncate_count; 1707 if (!need_break) 1708 return 0; 1709 } else { 1710 /* Note restart_addr in vma's truncate_count field */ 1711 vma->vm_truncate_count = restart_addr; 1712 if (!need_break) 1713 goto again; 1714 } 1715 1716 spin_unlock(details->i_mmap_lock); 1717 cond_resched(); 1718 spin_lock(details->i_mmap_lock); 1719 return -EINTR; 1720} 1721 1722static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1723 struct zap_details *details) 1724{ 1725 struct vm_area_struct *vma; 1726 struct prio_tree_iter iter; 1727 pgoff_t vba, vea, zba, zea; 1728 1729restart: 1730 vma_prio_tree_foreach(vma, &iter, root, 1731 details->first_index, details->last_index) { 1732 /* Skip quickly over those we have already dealt with */ 1733 if (vma->vm_truncate_count == details->truncate_count) 1734 continue; 1735 1736 vba = vma->vm_pgoff; 1737 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1738 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1739 zba = details->first_index; 1740 if (zba < vba) 1741 zba = vba; 1742 zea = details->last_index; 1743 if (zea > vea) 1744 zea = vea; 1745 1746 if (unmap_mapping_range_vma(vma, 1747 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1748 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1749 details) < 0) 1750 goto restart; 1751 } 1752} 1753 1754static inline void unmap_mapping_range_list(struct list_head *head, 1755 struct zap_details *details) 1756{ 1757 struct vm_area_struct *vma; 1758 1759 /* 1760 * In nonlinear VMAs there is no correspondence between virtual address 1761 * offset and file offset. So we must perform an exhaustive search 1762 * across *all* the pages in each nonlinear VMA, not just the pages 1763 * whose virtual address lies outside the file truncation point. 1764 */ 1765restart: 1766 list_for_each_entry(vma, head, shared.vm_set.list) { 1767 /* Skip quickly over those we have already dealt with */ 1768 if (vma->vm_truncate_count == details->truncate_count) 1769 continue; 1770 details->nonlinear_vma = vma; 1771 if (unmap_mapping_range_vma(vma, vma->vm_start, 1772 vma->vm_end, details) < 0) 1773 goto restart; 1774 } 1775} 1776 1777/** 1778 * unmap_mapping_range - unmap the portion of all mmaps 1779 * in the specified address_space corresponding to the specified 1780 * page range in the underlying file. 1781 * @mapping: the address space containing mmaps to be unmapped. 1782 * @holebegin: byte in first page to unmap, relative to the start of 1783 * the underlying file. This will be rounded down to a PAGE_SIZE 1784 * boundary. Note that this is different from vmtruncate(), which 1785 * must keep the partial page. In contrast, we must get rid of 1786 * partial pages. 1787 * @holelen: size of prospective hole in bytes. This will be rounded 1788 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1789 * end of the file. 1790 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1791 * but 0 when invalidating pagecache, don't throw away private data. 1792 */ 1793void unmap_mapping_range(struct address_space *mapping, 1794 loff_t const holebegin, loff_t const holelen, int even_cows) 1795{ 1796 struct zap_details details; 1797 pgoff_t hba = holebegin >> PAGE_SHIFT; 1798 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1799 1800 /* Check for overflow. */ 1801 if (sizeof(holelen) > sizeof(hlen)) { 1802 long long holeend = 1803 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1804 if (holeend & ~(long long)ULONG_MAX) 1805 hlen = ULONG_MAX - hba + 1; 1806 } 1807 1808 details.check_mapping = even_cows? NULL: mapping; 1809 details.nonlinear_vma = NULL; 1810 details.first_index = hba; 1811 details.last_index = hba + hlen - 1; 1812 if (details.last_index < details.first_index) 1813 details.last_index = ULONG_MAX; 1814 details.i_mmap_lock = &mapping->i_mmap_lock; 1815 1816 spin_lock(&mapping->i_mmap_lock); 1817 1818 /* serialize i_size write against truncate_count write */ 1819 smp_wmb(); 1820 /* Protect against page faults, and endless unmapping loops */ 1821 mapping->truncate_count++; 1822 /* 1823 * For archs where spin_lock has inclusive semantics like ia64 1824 * this smp_mb() will prevent to read pagetable contents 1825 * before the truncate_count increment is visible to 1826 * other cpus. 1827 */ 1828 smp_mb(); 1829 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1830 if (mapping->truncate_count == 0) 1831 reset_vma_truncate_counts(mapping); 1832 mapping->truncate_count++; 1833 } 1834 details.truncate_count = mapping->truncate_count; 1835 1836 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1837 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1838 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1839 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1840 spin_unlock(&mapping->i_mmap_lock); 1841} 1842EXPORT_SYMBOL(unmap_mapping_range); 1843 1844/** 1845 * vmtruncate - unmap mappings "freed" by truncate() syscall 1846 * @inode: inode of the file used 1847 * @offset: file offset to start truncating 1848 * 1849 * NOTE! We have to be ready to update the memory sharing 1850 * between the file and the memory map for a potential last 1851 * incomplete page. Ugly, but necessary. 1852 */ 1853int vmtruncate(struct inode * inode, loff_t offset) 1854{ 1855 struct address_space *mapping = inode->i_mapping; 1856 unsigned long limit; 1857 1858 if (inode->i_size < offset) 1859 goto do_expand; 1860 /* 1861 * truncation of in-use swapfiles is disallowed - it would cause 1862 * subsequent swapout to scribble on the now-freed blocks. 1863 */ 1864 if (IS_SWAPFILE(inode)) 1865 goto out_busy; 1866 i_size_write(inode, offset); 1867 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1868 truncate_inode_pages(mapping, offset); 1869 goto out_truncate; 1870 1871do_expand: 1872 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1873 if (limit != RLIM_INFINITY && offset > limit) 1874 goto out_sig; 1875 if (offset > inode->i_sb->s_maxbytes) 1876 goto out_big; 1877 i_size_write(inode, offset); 1878 1879out_truncate: 1880 if (inode->i_op && inode->i_op->truncate) 1881 inode->i_op->truncate(inode); 1882 return 0; 1883out_sig: 1884 send_sig(SIGXFSZ, current, 0); 1885out_big: 1886 return -EFBIG; 1887out_busy: 1888 return -ETXTBSY; 1889} 1890EXPORT_SYMBOL(vmtruncate); 1891 1892int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 1893{ 1894 struct address_space *mapping = inode->i_mapping; 1895 1896 /* 1897 * If the underlying filesystem is not going to provide 1898 * a way to truncate a range of blocks (punch a hole) - 1899 * we should return failure right now. 1900 */ 1901 if (!inode->i_op || !inode->i_op->truncate_range) 1902 return -ENOSYS; 1903 1904 mutex_lock(&inode->i_mutex); 1905 down_write(&inode->i_alloc_sem); 1906 unmap_mapping_range(mapping, offset, (end - offset), 1); 1907 truncate_inode_pages_range(mapping, offset, end); 1908 inode->i_op->truncate_range(inode, offset, end); 1909 up_write(&inode->i_alloc_sem); 1910 mutex_unlock(&inode->i_mutex); 1911 1912 return 0; 1913} 1914 1915/** 1916 * swapin_readahead - swap in pages in hope we need them soon 1917 * @entry: swap entry of this memory 1918 * @addr: address to start 1919 * @vma: user vma this addresses belong to 1920 * 1921 * Primitive swap readahead code. We simply read an aligned block of 1922 * (1 << page_cluster) entries in the swap area. This method is chosen 1923 * because it doesn't cost us any seek time. We also make sure to queue 1924 * the 'original' request together with the readahead ones... 1925 * 1926 * This has been extended to use the NUMA policies from the mm triggering 1927 * the readahead. 1928 * 1929 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 1930 */ 1931void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 1932{ 1933#ifdef CONFIG_NUMA 1934 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 1935#endif 1936 int i, num; 1937 struct page *new_page; 1938 unsigned long offset; 1939 1940 /* 1941 * Get the number of handles we should do readahead io to. 1942 */ 1943 num = valid_swaphandles(entry, &offset); 1944 for (i = 0; i < num; offset++, i++) { 1945 /* Ok, do the async read-ahead now */ 1946 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 1947 offset), vma, addr); 1948 if (!new_page) 1949 break; 1950 page_cache_release(new_page); 1951#ifdef CONFIG_NUMA 1952 /* 1953 * Find the next applicable VMA for the NUMA policy. 1954 */ 1955 addr += PAGE_SIZE; 1956 if (addr == 0) 1957 vma = NULL; 1958 if (vma) { 1959 if (addr >= vma->vm_end) { 1960 vma = next_vma; 1961 next_vma = vma ? vma->vm_next : NULL; 1962 } 1963 if (vma && addr < vma->vm_start) 1964 vma = NULL; 1965 } else { 1966 if (next_vma && addr >= next_vma->vm_start) { 1967 vma = next_vma; 1968 next_vma = vma->vm_next; 1969 } 1970 } 1971#endif 1972 } 1973 lru_add_drain(); /* Push any new pages onto the LRU now */ 1974} 1975 1976/* 1977 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1978 * but allow concurrent faults), and pte mapped but not yet locked. 1979 * We return with mmap_sem still held, but pte unmapped and unlocked. 1980 */ 1981static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 1982 unsigned long address, pte_t *page_table, pmd_t *pmd, 1983 int write_access, pte_t orig_pte) 1984{ 1985 spinlock_t *ptl; 1986 struct page *page; 1987 swp_entry_t entry; 1988 pte_t pte; 1989 int ret = VM_FAULT_MINOR; 1990 1991 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1992 goto out; 1993 1994 entry = pte_to_swp_entry(orig_pte); 1995 if (is_migration_entry(entry)) { 1996 migration_entry_wait(mm, pmd, address); 1997 goto out; 1998 } 1999 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2000 page = lookup_swap_cache(entry); 2001 if (!page) { 2002 grab_swap_token(); /* Contend for token _before_ read-in */ 2003 swapin_readahead(entry, address, vma); 2004 page = read_swap_cache_async(entry, vma, address); 2005 if (!page) { 2006 /* 2007 * Back out if somebody else faulted in this pte 2008 * while we released the pte lock. 2009 */ 2010 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2011 if (likely(pte_same(*page_table, orig_pte))) 2012 ret = VM_FAULT_OOM; 2013 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2014 goto unlock; 2015 } 2016 2017 /* Had to read the page from swap area: Major fault */ 2018 ret = VM_FAULT_MAJOR; 2019 count_vm_event(PGMAJFAULT); 2020 } 2021 2022 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2023 mark_page_accessed(page); 2024 lock_page(page); 2025 2026 /* 2027 * Back out if somebody else already faulted in this pte. 2028 */ 2029 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2030 if (unlikely(!pte_same(*page_table, orig_pte))) 2031 goto out_nomap; 2032 2033 if (unlikely(!PageUptodate(page))) { 2034 ret = VM_FAULT_SIGBUS; 2035 goto out_nomap; 2036 } 2037 2038 /* The page isn't present yet, go ahead with the fault. */ 2039 2040 inc_mm_counter(mm, anon_rss); 2041 pte = mk_pte(page, vma->vm_page_prot); 2042 if (write_access && can_share_swap_page(page)) { 2043 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2044 write_access = 0; 2045 } 2046 2047 flush_icache_page(vma, page); 2048 set_pte_at(mm, address, page_table, pte); 2049 page_add_anon_rmap(page, vma, address); 2050 2051 swap_free(entry); 2052 if (vm_swap_full()) 2053 remove_exclusive_swap_page(page); 2054 unlock_page(page); 2055 2056 if (write_access) { 2057 if (do_wp_page(mm, vma, address, 2058 page_table, pmd, ptl, pte) == VM_FAULT_OOM) 2059 ret = VM_FAULT_OOM; 2060 goto out; 2061 } 2062 2063 /* No need to invalidate - it was non-present before */ 2064 update_mmu_cache(vma, address, pte); 2065 lazy_mmu_prot_update(pte); 2066unlock: 2067 pte_unmap_unlock(page_table, ptl); 2068out: 2069 return ret; 2070out_nomap: 2071 pte_unmap_unlock(page_table, ptl); 2072 unlock_page(page); 2073 page_cache_release(page); 2074 return ret; 2075} 2076 2077/* 2078 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2079 * but allow concurrent faults), and pte mapped but not yet locked. 2080 * We return with mmap_sem still held, but pte unmapped and unlocked. 2081 */ 2082static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2083 unsigned long address, pte_t *page_table, pmd_t *pmd, 2084 int write_access) 2085{ 2086 struct page *page; 2087 spinlock_t *ptl; 2088 pte_t entry; 2089 2090 if (write_access) { 2091 /* Allocate our own private page. */ 2092 pte_unmap(page_table); 2093 2094 if (unlikely(anon_vma_prepare(vma))) 2095 goto oom; 2096 page = alloc_zeroed_user_highpage(vma, address); 2097 if (!page) 2098 goto oom; 2099 2100 entry = mk_pte(page, vma->vm_page_prot); 2101 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2102 2103 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2104 if (!pte_none(*page_table)) 2105 goto release; 2106 inc_mm_counter(mm, anon_rss); 2107 lru_cache_add_active(page); 2108 page_add_new_anon_rmap(page, vma, address); 2109 } else { 2110 /* Map the ZERO_PAGE - vm_page_prot is readonly */ 2111 page = ZERO_PAGE(address); 2112 page_cache_get(page); 2113 entry = mk_pte(page, vma->vm_page_prot); 2114 2115 ptl = pte_lockptr(mm, pmd); 2116 spin_lock(ptl); 2117 if (!pte_none(*page_table)) 2118 goto release; 2119 inc_mm_counter(mm, file_rss); 2120 page_add_file_rmap(page); 2121 } 2122 2123 set_pte_at(mm, address, page_table, entry); 2124 2125 /* No need to invalidate - it was non-present before */ 2126 update_mmu_cache(vma, address, entry); 2127 lazy_mmu_prot_update(entry); 2128unlock: 2129 pte_unmap_unlock(page_table, ptl); 2130 return VM_FAULT_MINOR; 2131release: 2132 page_cache_release(page); 2133 goto unlock; 2134oom: 2135 return VM_FAULT_OOM; 2136} 2137 2138/* 2139 * do_no_page() tries to create a new page mapping. It aggressively 2140 * tries to share with existing pages, but makes a separate copy if 2141 * the "write_access" parameter is true in order to avoid the next 2142 * page fault. 2143 * 2144 * As this is called only for pages that do not currently exist, we 2145 * do not need to flush old virtual caches or the TLB. 2146 * 2147 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2148 * but allow concurrent faults), and pte mapped but not yet locked. 2149 * We return with mmap_sem still held, but pte unmapped and unlocked. 2150 */ 2151static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2152 unsigned long address, pte_t *page_table, pmd_t *pmd, 2153 int write_access) 2154{ 2155 spinlock_t *ptl; 2156 struct page *new_page; 2157 struct address_space *mapping = NULL; 2158 pte_t entry; 2159 unsigned int sequence = 0; 2160 int ret = VM_FAULT_MINOR; 2161 int anon = 0; 2162 struct page *dirty_page = NULL; 2163 2164 pte_unmap(page_table); 2165 BUG_ON(vma->vm_flags & VM_PFNMAP); 2166 2167 if (vma->vm_file) { 2168 mapping = vma->vm_file->f_mapping; 2169 sequence = mapping->truncate_count; 2170 smp_rmb(); /* serializes i_size against truncate_count */ 2171 } 2172retry: 2173 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 2174 /* 2175 * No smp_rmb is needed here as long as there's a full 2176 * spin_lock/unlock sequence inside the ->nopage callback 2177 * (for the pagecache lookup) that acts as an implicit 2178 * smp_mb() and prevents the i_size read to happen 2179 * after the next truncate_count read. 2180 */ 2181 2182 /* no page was available -- either SIGBUS, OOM or REFAULT */ 2183 if (unlikely(new_page == NOPAGE_SIGBUS)) 2184 return VM_FAULT_SIGBUS; 2185 else if (unlikely(new_page == NOPAGE_OOM)) 2186 return VM_FAULT_OOM; 2187 else if (unlikely(new_page == NOPAGE_REFAULT)) 2188 return VM_FAULT_MINOR; 2189 2190 /* 2191 * Should we do an early C-O-W break? 2192 */ 2193 if (write_access) { 2194 if (!(vma->vm_flags & VM_SHARED)) { 2195 struct page *page; 2196 2197 if (unlikely(anon_vma_prepare(vma))) 2198 goto oom; 2199 page = alloc_page_vma(GFP_HIGHUSER, vma, address); 2200 if (!page) 2201 goto oom; 2202 copy_user_highpage(page, new_page, address, vma); 2203 page_cache_release(new_page); 2204 new_page = page; 2205 anon = 1; 2206 2207 } else { 2208 /* if the page will be shareable, see if the backing 2209 * address space wants to know that the page is about 2210 * to become writable */ 2211 if (vma->vm_ops->page_mkwrite && 2212 vma->vm_ops->page_mkwrite(vma, new_page) < 0 2213 ) { 2214 page_cache_release(new_page); 2215 return VM_FAULT_SIGBUS; 2216 } 2217 } 2218 } 2219 2220 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2221 /* 2222 * For a file-backed vma, someone could have truncated or otherwise 2223 * invalidated this page. If unmap_mapping_range got called, 2224 * retry getting the page. 2225 */ 2226 if (mapping && unlikely(sequence != mapping->truncate_count)) { 2227 pte_unmap_unlock(page_table, ptl); 2228 page_cache_release(new_page); 2229 cond_resched(); 2230 sequence = mapping->truncate_count; 2231 smp_rmb(); 2232 goto retry; 2233 } 2234 2235 /* 2236 * This silly early PAGE_DIRTY setting removes a race 2237 * due to the bad i386 page protection. But it's valid 2238 * for other architectures too. 2239 * 2240 * Note that if write_access is true, we either now have 2241 * an exclusive copy of the page, or this is a shared mapping, 2242 * so we can make it writable and dirty to avoid having to 2243 * handle that later. 2244 */ 2245 /* Only go through if we didn't race with anybody else... */ 2246 if (pte_none(*page_table)) { 2247 flush_icache_page(vma, new_page); 2248 entry = mk_pte(new_page, vma->vm_page_prot); 2249 if (write_access) 2250 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2251 set_pte_at(mm, address, page_table, entry); 2252 if (anon) { 2253 inc_mm_counter(mm, anon_rss); 2254 lru_cache_add_active(new_page); 2255 page_add_new_anon_rmap(new_page, vma, address); 2256 } else { 2257 inc_mm_counter(mm, file_rss); 2258 page_add_file_rmap(new_page); 2259 if (write_access) { 2260 dirty_page = new_page; 2261 get_page(dirty_page); 2262 } 2263 } 2264 } else { 2265 /* One of our sibling threads was faster, back out. */ 2266 page_cache_release(new_page); 2267 goto unlock; 2268 } 2269 2270 /* no need to invalidate: a not-present page shouldn't be cached */ 2271 update_mmu_cache(vma, address, entry); 2272 lazy_mmu_prot_update(entry); 2273unlock: 2274 pte_unmap_unlock(page_table, ptl); 2275 if (dirty_page) { 2276 set_page_dirty_balance(dirty_page); 2277 put_page(dirty_page); 2278 } 2279 return ret; 2280oom: 2281 page_cache_release(new_page); 2282 return VM_FAULT_OOM; 2283} 2284 2285/* 2286 * do_no_pfn() tries to create a new page mapping for a page without 2287 * a struct_page backing it 2288 * 2289 * As this is called only for pages that do not currently exist, we 2290 * do not need to flush old virtual caches or the TLB. 2291 * 2292 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2293 * but allow concurrent faults), and pte mapped but not yet locked. 2294 * We return with mmap_sem still held, but pte unmapped and unlocked. 2295 * 2296 * It is expected that the ->nopfn handler always returns the same pfn 2297 * for a given virtual mapping. 2298 * 2299 * Mark this `noinline' to prevent it from bloating the main pagefault code. 2300 */ 2301static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma, 2302 unsigned long address, pte_t *page_table, pmd_t *pmd, 2303 int write_access) 2304{ 2305 spinlock_t *ptl; 2306 pte_t entry; 2307 unsigned long pfn; 2308 int ret = VM_FAULT_MINOR; 2309 2310 pte_unmap(page_table); 2311 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 2312 BUG_ON(is_cow_mapping(vma->vm_flags)); 2313 2314 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK); 2315 if (pfn == NOPFN_OOM) 2316 return VM_FAULT_OOM; 2317 if (pfn == NOPFN_SIGBUS) 2318 return VM_FAULT_SIGBUS; 2319 2320 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2321 2322 /* Only go through if we didn't race with anybody else... */ 2323 if (pte_none(*page_table)) { 2324 entry = pfn_pte(pfn, vma->vm_page_prot); 2325 if (write_access) 2326 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2327 set_pte_at(mm, address, page_table, entry); 2328 } 2329 pte_unmap_unlock(page_table, ptl); 2330 return ret; 2331} 2332 2333/* 2334 * Fault of a previously existing named mapping. Repopulate the pte 2335 * from the encoded file_pte if possible. This enables swappable 2336 * nonlinear vmas. 2337 * 2338 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2339 * but allow concurrent faults), and pte mapped but not yet locked. 2340 * We return with mmap_sem still held, but pte unmapped and unlocked. 2341 */ 2342static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, 2343 unsigned long address, pte_t *page_table, pmd_t *pmd, 2344 int write_access, pte_t orig_pte) 2345{ 2346 pgoff_t pgoff; 2347 int err; 2348 2349 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2350 return VM_FAULT_MINOR; 2351 2352 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 2353 /* 2354 * Page table corrupted: show pte and kill process. 2355 */ 2356 print_bad_pte(vma, orig_pte, address); 2357 return VM_FAULT_OOM; 2358 } 2359 /* We can then assume vm->vm_ops && vma->vm_ops->populate */ 2360 2361 pgoff = pte_to_pgoff(orig_pte); 2362 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, 2363 vma->vm_page_prot, pgoff, 0); 2364 if (err == -ENOMEM) 2365 return VM_FAULT_OOM; 2366 if (err) 2367 return VM_FAULT_SIGBUS; 2368 return VM_FAULT_MAJOR; 2369} 2370 2371/* 2372 * These routines also need to handle stuff like marking pages dirty 2373 * and/or accessed for architectures that don't do it in hardware (most 2374 * RISC architectures). The early dirtying is also good on the i386. 2375 * 2376 * There is also a hook called "update_mmu_cache()" that architectures 2377 * with external mmu caches can use to update those (ie the Sparc or 2378 * PowerPC hashed page tables that act as extended TLBs). 2379 * 2380 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2381 * but allow concurrent faults), and pte mapped but not yet locked. 2382 * We return with mmap_sem still held, but pte unmapped and unlocked. 2383 */ 2384static inline int handle_pte_fault(struct mm_struct *mm, 2385 struct vm_area_struct *vma, unsigned long address, 2386 pte_t *pte, pmd_t *pmd, int write_access) 2387{ 2388 pte_t entry; 2389 pte_t old_entry; 2390 spinlock_t *ptl; 2391 2392 old_entry = entry = *pte; 2393 if (!pte_present(entry)) { 2394 if (pte_none(entry)) { 2395 if (vma->vm_ops) { 2396 if (vma->vm_ops->nopage) 2397 return do_no_page(mm, vma, address, 2398 pte, pmd, 2399 write_access); 2400 if (unlikely(vma->vm_ops->nopfn)) 2401 return do_no_pfn(mm, vma, address, pte, 2402 pmd, write_access); 2403 } 2404 return do_anonymous_page(mm, vma, address, 2405 pte, pmd, write_access); 2406 } 2407 if (pte_file(entry)) 2408 return do_file_page(mm, vma, address, 2409 pte, pmd, write_access, entry); 2410 return do_swap_page(mm, vma, address, 2411 pte, pmd, write_access, entry); 2412 } 2413 2414 ptl = pte_lockptr(mm, pmd); 2415 spin_lock(ptl); 2416 if (unlikely(!pte_same(*pte, entry))) 2417 goto unlock; 2418 if (write_access) { 2419 if (!pte_write(entry)) 2420 return do_wp_page(mm, vma, address, 2421 pte, pmd, ptl, entry); 2422 entry = pte_mkdirty(entry); 2423 } 2424 entry = pte_mkyoung(entry); 2425 if (!pte_same(old_entry, entry)) { 2426 ptep_set_access_flags(vma, address, pte, entry, write_access); 2427 update_mmu_cache(vma, address, entry); 2428 lazy_mmu_prot_update(entry); 2429 } else { 2430 /* 2431 * This is needed only for protection faults but the arch code 2432 * is not yet telling us if this is a protection fault or not. 2433 * This still avoids useless tlb flushes for .text page faults 2434 * with threads. 2435 */ 2436 if (write_access) 2437 flush_tlb_page(vma, address); 2438 } 2439unlock: 2440 pte_unmap_unlock(pte, ptl); 2441 return VM_FAULT_MINOR; 2442} 2443 2444/* 2445 * By the time we get here, we already hold the mm semaphore 2446 */ 2447int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2448 unsigned long address, int write_access) 2449{ 2450 pgd_t *pgd; 2451 pud_t *pud; 2452 pmd_t *pmd; 2453 pte_t *pte; 2454 2455 __set_current_state(TASK_RUNNING); 2456 2457 count_vm_event(PGFAULT); 2458 2459 if (unlikely(is_vm_hugetlb_page(vma))) 2460 return hugetlb_fault(mm, vma, address, write_access); 2461 2462 pgd = pgd_offset(mm, address); 2463 pud = pud_alloc(mm, pgd, address); 2464 if (!pud) 2465 return VM_FAULT_OOM; 2466 pmd = pmd_alloc(mm, pud, address); 2467 if (!pmd) 2468 return VM_FAULT_OOM; 2469 pte = pte_alloc_map(mm, pmd, address); 2470 if (!pte) 2471 return VM_FAULT_OOM; 2472 2473 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2474} 2475 2476EXPORT_SYMBOL_GPL(__handle_mm_fault); 2477 2478#ifndef __PAGETABLE_PUD_FOLDED 2479/* 2480 * Allocate page upper directory. 2481 * We've already handled the fast-path in-line. 2482 */ 2483int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2484{ 2485 pud_t *new = pud_alloc_one(mm, address); 2486 if (!new) 2487 return -ENOMEM; 2488 2489 spin_lock(&mm->page_table_lock); 2490 if (pgd_present(*pgd)) /* Another has populated it */ 2491 pud_free(new); 2492 else 2493 pgd_populate(mm, pgd, new); 2494 spin_unlock(&mm->page_table_lock); 2495 return 0; 2496} 2497#else 2498/* Workaround for gcc 2.96 */ 2499int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2500{ 2501 return 0; 2502} 2503#endif /* __PAGETABLE_PUD_FOLDED */ 2504 2505#ifndef __PAGETABLE_PMD_FOLDED 2506/* 2507 * Allocate page middle directory. 2508 * We've already handled the fast-path in-line. 2509 */ 2510int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2511{ 2512 pmd_t *new = pmd_alloc_one(mm, address); 2513 if (!new) 2514 return -ENOMEM; 2515 2516 spin_lock(&mm->page_table_lock); 2517#ifndef __ARCH_HAS_4LEVEL_HACK 2518 if (pud_present(*pud)) /* Another has populated it */ 2519 pmd_free(new); 2520 else 2521 pud_populate(mm, pud, new); 2522#else 2523 if (pgd_present(*pud)) /* Another has populated it */ 2524 pmd_free(new); 2525 else 2526 pgd_populate(mm, pud, new); 2527#endif /* __ARCH_HAS_4LEVEL_HACK */ 2528 spin_unlock(&mm->page_table_lock); 2529 return 0; 2530} 2531#else 2532/* Workaround for gcc 2.96 */ 2533int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2534{ 2535 return 0; 2536} 2537#endif /* __PAGETABLE_PMD_FOLDED */ 2538 2539int make_pages_present(unsigned long addr, unsigned long end) 2540{ 2541 int ret, len, write; 2542 struct vm_area_struct * vma; 2543 2544 vma = find_vma(current->mm, addr); 2545 if (!vma) 2546 return -1; 2547 write = (vma->vm_flags & VM_WRITE) != 0; 2548 BUG_ON(addr >= end); 2549 BUG_ON(end > vma->vm_end); 2550 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; 2551 ret = get_user_pages(current, current->mm, addr, 2552 len, write, 0, NULL, NULL); 2553 if (ret < 0) 2554 return ret; 2555 return ret == len ? 0 : -1; 2556} 2557 2558/* 2559 * Map a vmalloc()-space virtual address to the physical page. 2560 */ 2561struct page * vmalloc_to_page(void * vmalloc_addr) 2562{ 2563 unsigned long addr = (unsigned long) vmalloc_addr; 2564 struct page *page = NULL; 2565 pgd_t *pgd = pgd_offset_k(addr); 2566 pud_t *pud; 2567 pmd_t *pmd; 2568 pte_t *ptep, pte; 2569 2570 if (!pgd_none(*pgd)) { 2571 pud = pud_offset(pgd, addr); 2572 if (!pud_none(*pud)) { 2573 pmd = pmd_offset(pud, addr); 2574 if (!pmd_none(*pmd)) { 2575 ptep = pte_offset_map(pmd, addr); 2576 pte = *ptep; 2577 if (pte_present(pte)) 2578 page = pte_page(pte); 2579 pte_unmap(ptep); 2580 } 2581 } 2582 } 2583 return page; 2584} 2585 2586EXPORT_SYMBOL(vmalloc_to_page); 2587 2588/* 2589 * Map a vmalloc()-space virtual address to the physical page frame number. 2590 */ 2591unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2592{ 2593 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2594} 2595 2596EXPORT_SYMBOL(vmalloc_to_pfn); 2597 2598#if !defined(__HAVE_ARCH_GATE_AREA) 2599 2600#if defined(AT_SYSINFO_EHDR) 2601static struct vm_area_struct gate_vma; 2602 2603static int __init gate_vma_init(void) 2604{ 2605 gate_vma.vm_mm = NULL; 2606 gate_vma.vm_start = FIXADDR_USER_START; 2607 gate_vma.vm_end = FIXADDR_USER_END; 2608 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 2609 gate_vma.vm_page_prot = __P101; 2610 /* 2611 * Make sure the vDSO gets into every core dump. 2612 * Dumping its contents makes post-mortem fully interpretable later 2613 * without matching up the same kernel and hardware config to see 2614 * what PC values meant. 2615 */ 2616 gate_vma.vm_flags |= VM_ALWAYSDUMP; 2617 return 0; 2618} 2619__initcall(gate_vma_init); 2620#endif 2621 2622struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2623{ 2624#ifdef AT_SYSINFO_EHDR 2625 return &gate_vma; 2626#else 2627 return NULL; 2628#endif 2629} 2630 2631int in_gate_area_no_task(unsigned long addr) 2632{ 2633#ifdef AT_SYSINFO_EHDR 2634 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2635 return 1; 2636#endif 2637 return 0; 2638} 2639 2640#endif /* __HAVE_ARCH_GATE_AREA */ 2641 2642/* 2643 * Access another process' address space. 2644 * Source/target buffer must be kernel space, 2645 * Do not walk the page table directly, use get_user_pages 2646 */ 2647int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2648{ 2649 struct mm_struct *mm; 2650 struct vm_area_struct *vma; 2651 struct page *page; 2652 void *old_buf = buf; 2653 2654 mm = get_task_mm(tsk); 2655 if (!mm) 2656 return 0; 2657 2658 down_read(&mm->mmap_sem); 2659 /* ignore errors, just check how much was sucessfully transfered */ 2660 while (len) { 2661 int bytes, ret, offset; 2662 void *maddr; 2663 2664 ret = get_user_pages(tsk, mm, addr, 1, 2665 write, 1, &page, &vma); 2666 if (ret <= 0) 2667 break; 2668 2669 bytes = len; 2670 offset = addr & (PAGE_SIZE-1); 2671 if (bytes > PAGE_SIZE-offset) 2672 bytes = PAGE_SIZE-offset; 2673 2674 maddr = kmap(page); 2675 if (write) { 2676 copy_to_user_page(vma, page, addr, 2677 maddr + offset, buf, bytes); 2678 set_page_dirty_lock(page); 2679 } else { 2680 copy_from_user_page(vma, page, addr, 2681 buf, maddr + offset, bytes); 2682 } 2683 kunmap(page); 2684 page_cache_release(page); 2685 len -= bytes; 2686 buf += bytes; 2687 addr += bytes; 2688 } 2689 up_read(&mm->mmap_sem); 2690 mmput(mm); 2691 2692 return buf - old_buf; 2693} 2694