1 /* 2 * linux/mm/nommu.c 3 * 4 * Replacement code for mm functions to support CPU's that don't 5 * have any form of memory management unit (thus no virtual memory). 6 * 7 * See Documentation/nommu-mmap.txt 8 * 9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com> 10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com> 11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org> 12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com> 13 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org> 14 */ 15 16 #include <linux/export.h> 17 #include <linux/mm.h> 18 #include <linux/mman.h> 19 #include <linux/swap.h> 20 #include <linux/file.h> 21 #include <linux/highmem.h> 22 #include <linux/pagemap.h> 23 #include <linux/slab.h> 24 #include <linux/vmalloc.h> 25 #include <linux/blkdev.h> 26 #include <linux/backing-dev.h> 27 #include <linux/mount.h> 28 #include <linux/personality.h> 29 #include <linux/security.h> 30 #include <linux/syscalls.h> 31 #include <linux/audit.h> 32 #include <linux/sched/sysctl.h> 33 34 #include <asm/uaccess.h> 35 #include <asm/tlb.h> 36 #include <asm/tlbflush.h> 37 #include <asm/mmu_context.h> 38 #include "internal.h" 39 40 #if 0 41 #define kenter(FMT, ...) \ 42 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 43 #define kleave(FMT, ...) \ 44 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 45 #define kdebug(FMT, ...) \ 46 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 47 #else 48 #define kenter(FMT, ...) \ 49 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 50 #define kleave(FMT, ...) \ 51 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 52 #define kdebug(FMT, ...) \ 53 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 54 #endif 55 56 void *high_memory; 57 struct page *mem_map; 58 unsigned long max_mapnr; 59 unsigned long num_physpages; 60 unsigned long highest_memmap_pfn; 61 struct percpu_counter vm_committed_as; 62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 63 int sysctl_overcommit_ratio = 50; /* default is 50% */ 64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 65 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 66 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ 67 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ 68 int heap_stack_gap = 0; 69 70 atomic_long_t mmap_pages_allocated; 71 72 /* 73 * The global memory commitment made in the system can be a metric 74 * that can be used to drive ballooning decisions when Linux is hosted 75 * as a guest. On Hyper-V, the host implements a policy engine for dynamically 76 * balancing memory across competing virtual machines that are hosted. 77 * Several metrics drive this policy engine including the guest reported 78 * memory commitment. 79 */ 80 unsigned long vm_memory_committed(void) 81 { 82 return percpu_counter_read_positive(&vm_committed_as); 83 } 84 85 EXPORT_SYMBOL_GPL(vm_memory_committed); 86 87 EXPORT_SYMBOL(mem_map); 88 EXPORT_SYMBOL(num_physpages); 89 90 /* list of mapped, potentially shareable regions */ 91 static struct kmem_cache *vm_region_jar; 92 struct rb_root nommu_region_tree = RB_ROOT; 93 DECLARE_RWSEM(nommu_region_sem); 94 95 const struct vm_operations_struct generic_file_vm_ops = { 96 }; 97 98 /* 99 * Return the total memory allocated for this pointer, not 100 * just what the caller asked for. 101 * 102 * Doesn't have to be accurate, i.e. may have races. 103 */ 104 unsigned int kobjsize(const void *objp) 105 { 106 struct page *page; 107 108 /* 109 * If the object we have should not have ksize performed on it, 110 * return size of 0 111 */ 112 if (!objp || !virt_addr_valid(objp)) 113 return 0; 114 115 page = virt_to_head_page(objp); 116 117 /* 118 * If the allocator sets PageSlab, we know the pointer came from 119 * kmalloc(). 120 */ 121 if (PageSlab(page)) 122 return ksize(objp); 123 124 /* 125 * If it's not a compound page, see if we have a matching VMA 126 * region. This test is intentionally done in reverse order, 127 * so if there's no VMA, we still fall through and hand back 128 * PAGE_SIZE for 0-order pages. 129 */ 130 if (!PageCompound(page)) { 131 struct vm_area_struct *vma; 132 133 vma = find_vma(current->mm, (unsigned long)objp); 134 if (vma) 135 return vma->vm_end - vma->vm_start; 136 } 137 138 /* 139 * The ksize() function is only guaranteed to work for pointers 140 * returned by kmalloc(). So handle arbitrary pointers here. 141 */ 142 return PAGE_SIZE << compound_order(page); 143 } 144 145 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 146 unsigned long start, unsigned long nr_pages, 147 unsigned int foll_flags, struct page **pages, 148 struct vm_area_struct **vmas, int *nonblocking) 149 { 150 struct vm_area_struct *vma; 151 unsigned long vm_flags; 152 int i; 153 154 /* calculate required read or write permissions. 155 * If FOLL_FORCE is set, we only require the "MAY" flags. 156 */ 157 vm_flags = (foll_flags & FOLL_WRITE) ? 158 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 159 vm_flags &= (foll_flags & FOLL_FORCE) ? 160 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 161 162 for (i = 0; i < nr_pages; i++) { 163 vma = find_vma(mm, start); 164 if (!vma) 165 goto finish_or_fault; 166 167 /* protect what we can, including chardevs */ 168 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 169 !(vm_flags & vma->vm_flags)) 170 goto finish_or_fault; 171 172 if (pages) { 173 pages[i] = virt_to_page(start); 174 if (pages[i]) 175 page_cache_get(pages[i]); 176 } 177 if (vmas) 178 vmas[i] = vma; 179 start = (start + PAGE_SIZE) & PAGE_MASK; 180 } 181 182 return i; 183 184 finish_or_fault: 185 return i ? : -EFAULT; 186 } 187 188 /* 189 * get a list of pages in an address range belonging to the specified process 190 * and indicate the VMA that covers each page 191 * - this is potentially dodgy as we may end incrementing the page count of a 192 * slab page or a secondary page from a compound page 193 * - don't permit access to VMAs that don't support it, such as I/O mappings 194 */ 195 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 196 unsigned long start, unsigned long nr_pages, 197 int write, int force, struct page **pages, 198 struct vm_area_struct **vmas) 199 { 200 int flags = 0; 201 202 if (write) 203 flags |= FOLL_WRITE; 204 if (force) 205 flags |= FOLL_FORCE; 206 207 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 208 NULL); 209 } 210 EXPORT_SYMBOL(get_user_pages); 211 212 /** 213 * follow_pfn - look up PFN at a user virtual address 214 * @vma: memory mapping 215 * @address: user virtual address 216 * @pfn: location to store found PFN 217 * 218 * Only IO mappings and raw PFN mappings are allowed. 219 * 220 * Returns zero and the pfn at @pfn on success, -ve otherwise. 221 */ 222 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 223 unsigned long *pfn) 224 { 225 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 226 return -EINVAL; 227 228 *pfn = address >> PAGE_SHIFT; 229 return 0; 230 } 231 EXPORT_SYMBOL(follow_pfn); 232 233 LIST_HEAD(vmap_area_list); 234 235 void vfree(const void *addr) 236 { 237 kfree(addr); 238 } 239 EXPORT_SYMBOL(vfree); 240 241 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 242 { 243 /* 244 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 245 * returns only a logical address. 246 */ 247 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 248 } 249 EXPORT_SYMBOL(__vmalloc); 250 251 void *vmalloc_user(unsigned long size) 252 { 253 void *ret; 254 255 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 256 PAGE_KERNEL); 257 if (ret) { 258 struct vm_area_struct *vma; 259 260 down_write(¤t->mm->mmap_sem); 261 vma = find_vma(current->mm, (unsigned long)ret); 262 if (vma) 263 vma->vm_flags |= VM_USERMAP; 264 up_write(¤t->mm->mmap_sem); 265 } 266 267 return ret; 268 } 269 EXPORT_SYMBOL(vmalloc_user); 270 271 struct page *vmalloc_to_page(const void *addr) 272 { 273 return virt_to_page(addr); 274 } 275 EXPORT_SYMBOL(vmalloc_to_page); 276 277 unsigned long vmalloc_to_pfn(const void *addr) 278 { 279 return page_to_pfn(virt_to_page(addr)); 280 } 281 EXPORT_SYMBOL(vmalloc_to_pfn); 282 283 long vread(char *buf, char *addr, unsigned long count) 284 { 285 memcpy(buf, addr, count); 286 return count; 287 } 288 289 long vwrite(char *buf, char *addr, unsigned long count) 290 { 291 /* Don't allow overflow */ 292 if ((unsigned long) addr + count < count) 293 count = -(unsigned long) addr; 294 295 memcpy(addr, buf, count); 296 return(count); 297 } 298 299 /* 300 * vmalloc - allocate virtually continguos memory 301 * 302 * @size: allocation size 303 * 304 * Allocate enough pages to cover @size from the page level 305 * allocator and map them into continguos kernel virtual space. 306 * 307 * For tight control over page level allocator and protection flags 308 * use __vmalloc() instead. 309 */ 310 void *vmalloc(unsigned long size) 311 { 312 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 313 } 314 EXPORT_SYMBOL(vmalloc); 315 316 /* 317 * vzalloc - allocate virtually continguos memory with zero fill 318 * 319 * @size: allocation size 320 * 321 * Allocate enough pages to cover @size from the page level 322 * allocator and map them into continguos kernel virtual space. 323 * The memory allocated is set to zero. 324 * 325 * For tight control over page level allocator and protection flags 326 * use __vmalloc() instead. 327 */ 328 void *vzalloc(unsigned long size) 329 { 330 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 331 PAGE_KERNEL); 332 } 333 EXPORT_SYMBOL(vzalloc); 334 335 /** 336 * vmalloc_node - allocate memory on a specific node 337 * @size: allocation size 338 * @node: numa node 339 * 340 * Allocate enough pages to cover @size from the page level 341 * allocator and map them into contiguous kernel virtual space. 342 * 343 * For tight control over page level allocator and protection flags 344 * use __vmalloc() instead. 345 */ 346 void *vmalloc_node(unsigned long size, int node) 347 { 348 return vmalloc(size); 349 } 350 EXPORT_SYMBOL(vmalloc_node); 351 352 /** 353 * vzalloc_node - allocate memory on a specific node with zero fill 354 * @size: allocation size 355 * @node: numa node 356 * 357 * Allocate enough pages to cover @size from the page level 358 * allocator and map them into contiguous kernel virtual space. 359 * The memory allocated is set to zero. 360 * 361 * For tight control over page level allocator and protection flags 362 * use __vmalloc() instead. 363 */ 364 void *vzalloc_node(unsigned long size, int node) 365 { 366 return vzalloc(size); 367 } 368 EXPORT_SYMBOL(vzalloc_node); 369 370 #ifndef PAGE_KERNEL_EXEC 371 # define PAGE_KERNEL_EXEC PAGE_KERNEL 372 #endif 373 374 /** 375 * vmalloc_exec - allocate virtually contiguous, executable memory 376 * @size: allocation size 377 * 378 * Kernel-internal function to allocate enough pages to cover @size 379 * the page level allocator and map them into contiguous and 380 * executable kernel virtual space. 381 * 382 * For tight control over page level allocator and protection flags 383 * use __vmalloc() instead. 384 */ 385 386 void *vmalloc_exec(unsigned long size) 387 { 388 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 389 } 390 391 /** 392 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 393 * @size: allocation size 394 * 395 * Allocate enough 32bit PA addressable pages to cover @size from the 396 * page level allocator and map them into continguos kernel virtual space. 397 */ 398 void *vmalloc_32(unsigned long size) 399 { 400 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 401 } 402 EXPORT_SYMBOL(vmalloc_32); 403 404 /** 405 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 406 * @size: allocation size 407 * 408 * The resulting memory area is 32bit addressable and zeroed so it can be 409 * mapped to userspace without leaking data. 410 * 411 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 412 * remap_vmalloc_range() are permissible. 413 */ 414 void *vmalloc_32_user(unsigned long size) 415 { 416 /* 417 * We'll have to sort out the ZONE_DMA bits for 64-bit, 418 * but for now this can simply use vmalloc_user() directly. 419 */ 420 return vmalloc_user(size); 421 } 422 EXPORT_SYMBOL(vmalloc_32_user); 423 424 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 425 { 426 BUG(); 427 return NULL; 428 } 429 EXPORT_SYMBOL(vmap); 430 431 void vunmap(const void *addr) 432 { 433 BUG(); 434 } 435 EXPORT_SYMBOL(vunmap); 436 437 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 438 { 439 BUG(); 440 return NULL; 441 } 442 EXPORT_SYMBOL(vm_map_ram); 443 444 void vm_unmap_ram(const void *mem, unsigned int count) 445 { 446 BUG(); 447 } 448 EXPORT_SYMBOL(vm_unmap_ram); 449 450 void vm_unmap_aliases(void) 451 { 452 } 453 EXPORT_SYMBOL_GPL(vm_unmap_aliases); 454 455 /* 456 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 457 * have one. 458 */ 459 void __attribute__((weak)) vmalloc_sync_all(void) 460 { 461 } 462 463 /** 464 * alloc_vm_area - allocate a range of kernel address space 465 * @size: size of the area 466 * 467 * Returns: NULL on failure, vm_struct on success 468 * 469 * This function reserves a range of kernel address space, and 470 * allocates pagetables to map that range. No actual mappings 471 * are created. If the kernel address space is not shared 472 * between processes, it syncs the pagetable across all 473 * processes. 474 */ 475 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) 476 { 477 BUG(); 478 return NULL; 479 } 480 EXPORT_SYMBOL_GPL(alloc_vm_area); 481 482 void free_vm_area(struct vm_struct *area) 483 { 484 BUG(); 485 } 486 EXPORT_SYMBOL_GPL(free_vm_area); 487 488 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 489 struct page *page) 490 { 491 return -EINVAL; 492 } 493 EXPORT_SYMBOL(vm_insert_page); 494 495 /* 496 * sys_brk() for the most part doesn't need the global kernel 497 * lock, except when an application is doing something nasty 498 * like trying to un-brk an area that has already been mapped 499 * to a regular file. in this case, the unmapping will need 500 * to invoke file system routines that need the global lock. 501 */ 502 SYSCALL_DEFINE1(brk, unsigned long, brk) 503 { 504 struct mm_struct *mm = current->mm; 505 506 if (brk < mm->start_brk || brk > mm->context.end_brk) 507 return mm->brk; 508 509 if (mm->brk == brk) 510 return mm->brk; 511 512 /* 513 * Always allow shrinking brk 514 */ 515 if (brk <= mm->brk) { 516 mm->brk = brk; 517 return brk; 518 } 519 520 /* 521 * Ok, looks good - let it rip. 522 */ 523 flush_icache_range(mm->brk, brk); 524 return mm->brk = brk; 525 } 526 527 /* 528 * initialise the VMA and region record slabs 529 */ 530 void __init mmap_init(void) 531 { 532 int ret; 533 534 ret = percpu_counter_init(&vm_committed_as, 0); 535 VM_BUG_ON(ret); 536 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 537 } 538 539 /* 540 * validate the region tree 541 * - the caller must hold the region lock 542 */ 543 #ifdef CONFIG_DEBUG_NOMMU_REGIONS 544 static noinline void validate_nommu_regions(void) 545 { 546 struct vm_region *region, *last; 547 struct rb_node *p, *lastp; 548 549 lastp = rb_first(&nommu_region_tree); 550 if (!lastp) 551 return; 552 553 last = rb_entry(lastp, struct vm_region, vm_rb); 554 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 555 BUG_ON(unlikely(last->vm_top < last->vm_end)); 556 557 while ((p = rb_next(lastp))) { 558 region = rb_entry(p, struct vm_region, vm_rb); 559 last = rb_entry(lastp, struct vm_region, vm_rb); 560 561 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 562 BUG_ON(unlikely(region->vm_top < region->vm_end)); 563 BUG_ON(unlikely(region->vm_start < last->vm_top)); 564 565 lastp = p; 566 } 567 } 568 #else 569 static void validate_nommu_regions(void) 570 { 571 } 572 #endif 573 574 /* 575 * add a region into the global tree 576 */ 577 static void add_nommu_region(struct vm_region *region) 578 { 579 struct vm_region *pregion; 580 struct rb_node **p, *parent; 581 582 validate_nommu_regions(); 583 584 parent = NULL; 585 p = &nommu_region_tree.rb_node; 586 while (*p) { 587 parent = *p; 588 pregion = rb_entry(parent, struct vm_region, vm_rb); 589 if (region->vm_start < pregion->vm_start) 590 p = &(*p)->rb_left; 591 else if (region->vm_start > pregion->vm_start) 592 p = &(*p)->rb_right; 593 else if (pregion == region) 594 return; 595 else 596 BUG(); 597 } 598 599 rb_link_node(®ion->vm_rb, parent, p); 600 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 601 602 validate_nommu_regions(); 603 } 604 605 /* 606 * delete a region from the global tree 607 */ 608 static void delete_nommu_region(struct vm_region *region) 609 { 610 BUG_ON(!nommu_region_tree.rb_node); 611 612 validate_nommu_regions(); 613 rb_erase(®ion->vm_rb, &nommu_region_tree); 614 validate_nommu_regions(); 615 } 616 617 /* 618 * free a contiguous series of pages 619 */ 620 static void free_page_series(unsigned long from, unsigned long to) 621 { 622 for (; from < to; from += PAGE_SIZE) { 623 struct page *page = virt_to_page(from); 624 625 kdebug("- free %lx", from); 626 atomic_long_dec(&mmap_pages_allocated); 627 if (page_count(page) != 1) 628 kdebug("free page %p: refcount not one: %d", 629 page, page_count(page)); 630 put_page(page); 631 } 632 } 633 634 /* 635 * release a reference to a region 636 * - the caller must hold the region semaphore for writing, which this releases 637 * - the region may not have been added to the tree yet, in which case vm_top 638 * will equal vm_start 639 */ 640 static void __put_nommu_region(struct vm_region *region) 641 __releases(nommu_region_sem) 642 { 643 kenter("%p{%d}", region, region->vm_usage); 644 645 BUG_ON(!nommu_region_tree.rb_node); 646 647 if (--region->vm_usage == 0) { 648 if (region->vm_top > region->vm_start) 649 delete_nommu_region(region); 650 up_write(&nommu_region_sem); 651 652 if (region->vm_file) 653 fput(region->vm_file); 654 655 /* IO memory and memory shared directly out of the pagecache 656 * from ramfs/tmpfs mustn't be released here */ 657 if (region->vm_flags & VM_MAPPED_COPY) { 658 kdebug("free series"); 659 free_page_series(region->vm_start, region->vm_top); 660 } 661 kmem_cache_free(vm_region_jar, region); 662 } else { 663 up_write(&nommu_region_sem); 664 } 665 } 666 667 /* 668 * release a reference to a region 669 */ 670 static void put_nommu_region(struct vm_region *region) 671 { 672 down_write(&nommu_region_sem); 673 __put_nommu_region(region); 674 } 675 676 /* 677 * update protection on a vma 678 */ 679 static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 680 { 681 #ifdef CONFIG_MPU 682 struct mm_struct *mm = vma->vm_mm; 683 long start = vma->vm_start & PAGE_MASK; 684 while (start < vma->vm_end) { 685 protect_page(mm, start, flags); 686 start += PAGE_SIZE; 687 } 688 update_protections(mm); 689 #endif 690 } 691 692 /* 693 * add a VMA into a process's mm_struct in the appropriate place in the list 694 * and tree and add to the address space's page tree also if not an anonymous 695 * page 696 * - should be called with mm->mmap_sem held writelocked 697 */ 698 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 699 { 700 struct vm_area_struct *pvma, *prev; 701 struct address_space *mapping; 702 struct rb_node **p, *parent, *rb_prev; 703 704 kenter(",%p", vma); 705 706 BUG_ON(!vma->vm_region); 707 708 mm->map_count++; 709 vma->vm_mm = mm; 710 711 protect_vma(vma, vma->vm_flags); 712 713 /* add the VMA to the mapping */ 714 if (vma->vm_file) { 715 mapping = vma->vm_file->f_mapping; 716 717 mutex_lock(&mapping->i_mmap_mutex); 718 flush_dcache_mmap_lock(mapping); 719 vma_interval_tree_insert(vma, &mapping->i_mmap); 720 flush_dcache_mmap_unlock(mapping); 721 mutex_unlock(&mapping->i_mmap_mutex); 722 } 723 724 /* add the VMA to the tree */ 725 parent = rb_prev = NULL; 726 p = &mm->mm_rb.rb_node; 727 while (*p) { 728 parent = *p; 729 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 730 731 /* sort by: start addr, end addr, VMA struct addr in that order 732 * (the latter is necessary as we may get identical VMAs) */ 733 if (vma->vm_start < pvma->vm_start) 734 p = &(*p)->rb_left; 735 else if (vma->vm_start > pvma->vm_start) { 736 rb_prev = parent; 737 p = &(*p)->rb_right; 738 } else if (vma->vm_end < pvma->vm_end) 739 p = &(*p)->rb_left; 740 else if (vma->vm_end > pvma->vm_end) { 741 rb_prev = parent; 742 p = &(*p)->rb_right; 743 } else if (vma < pvma) 744 p = &(*p)->rb_left; 745 else if (vma > pvma) { 746 rb_prev = parent; 747 p = &(*p)->rb_right; 748 } else 749 BUG(); 750 } 751 752 rb_link_node(&vma->vm_rb, parent, p); 753 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 754 755 /* add VMA to the VMA list also */ 756 prev = NULL; 757 if (rb_prev) 758 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 759 760 __vma_link_list(mm, vma, prev, parent); 761 } 762 763 /* 764 * delete a VMA from its owning mm_struct and address space 765 */ 766 static void delete_vma_from_mm(struct vm_area_struct *vma) 767 { 768 struct address_space *mapping; 769 struct mm_struct *mm = vma->vm_mm; 770 771 kenter("%p", vma); 772 773 protect_vma(vma, 0); 774 775 mm->map_count--; 776 if (mm->mmap_cache == vma) 777 mm->mmap_cache = NULL; 778 779 /* remove the VMA from the mapping */ 780 if (vma->vm_file) { 781 mapping = vma->vm_file->f_mapping; 782 783 mutex_lock(&mapping->i_mmap_mutex); 784 flush_dcache_mmap_lock(mapping); 785 vma_interval_tree_remove(vma, &mapping->i_mmap); 786 flush_dcache_mmap_unlock(mapping); 787 mutex_unlock(&mapping->i_mmap_mutex); 788 } 789 790 /* remove from the MM's tree and list */ 791 rb_erase(&vma->vm_rb, &mm->mm_rb); 792 793 if (vma->vm_prev) 794 vma->vm_prev->vm_next = vma->vm_next; 795 else 796 mm->mmap = vma->vm_next; 797 798 if (vma->vm_next) 799 vma->vm_next->vm_prev = vma->vm_prev; 800 } 801 802 /* 803 * destroy a VMA record 804 */ 805 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 806 { 807 kenter("%p", vma); 808 if (vma->vm_ops && vma->vm_ops->close) 809 vma->vm_ops->close(vma); 810 if (vma->vm_file) 811 fput(vma->vm_file); 812 put_nommu_region(vma->vm_region); 813 kmem_cache_free(vm_area_cachep, vma); 814 } 815 816 /* 817 * look up the first VMA in which addr resides, NULL if none 818 * - should be called with mm->mmap_sem at least held readlocked 819 */ 820 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 821 { 822 struct vm_area_struct *vma; 823 824 /* check the cache first */ 825 vma = ACCESS_ONCE(mm->mmap_cache); 826 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 827 return vma; 828 829 /* trawl the list (there may be multiple mappings in which addr 830 * resides) */ 831 for (vma = mm->mmap; vma; vma = vma->vm_next) { 832 if (vma->vm_start > addr) 833 return NULL; 834 if (vma->vm_end > addr) { 835 mm->mmap_cache = vma; 836 return vma; 837 } 838 } 839 840 return NULL; 841 } 842 EXPORT_SYMBOL(find_vma); 843 844 /* 845 * find a VMA 846 * - we don't extend stack VMAs under NOMMU conditions 847 */ 848 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 849 { 850 return find_vma(mm, addr); 851 } 852 853 /* 854 * expand a stack to a given address 855 * - not supported under NOMMU conditions 856 */ 857 int expand_stack(struct vm_area_struct *vma, unsigned long address) 858 { 859 return -ENOMEM; 860 } 861 862 /* 863 * look up the first VMA exactly that exactly matches addr 864 * - should be called with mm->mmap_sem at least held readlocked 865 */ 866 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 867 unsigned long addr, 868 unsigned long len) 869 { 870 struct vm_area_struct *vma; 871 unsigned long end = addr + len; 872 873 /* check the cache first */ 874 vma = mm->mmap_cache; 875 if (vma && vma->vm_start == addr && vma->vm_end == end) 876 return vma; 877 878 /* trawl the list (there may be multiple mappings in which addr 879 * resides) */ 880 for (vma = mm->mmap; vma; vma = vma->vm_next) { 881 if (vma->vm_start < addr) 882 continue; 883 if (vma->vm_start > addr) 884 return NULL; 885 if (vma->vm_end == end) { 886 mm->mmap_cache = vma; 887 return vma; 888 } 889 } 890 891 return NULL; 892 } 893 894 /* 895 * determine whether a mapping should be permitted and, if so, what sort of 896 * mapping we're capable of supporting 897 */ 898 static int validate_mmap_request(struct file *file, 899 unsigned long addr, 900 unsigned long len, 901 unsigned long prot, 902 unsigned long flags, 903 unsigned long pgoff, 904 unsigned long *_capabilities) 905 { 906 unsigned long capabilities, rlen; 907 int ret; 908 909 /* do the simple checks first */ 910 if (flags & MAP_FIXED) { 911 printk(KERN_DEBUG 912 "%d: Can't do fixed-address/overlay mmap of RAM\n", 913 current->pid); 914 return -EINVAL; 915 } 916 917 if ((flags & MAP_TYPE) != MAP_PRIVATE && 918 (flags & MAP_TYPE) != MAP_SHARED) 919 return -EINVAL; 920 921 if (!len) 922 return -EINVAL; 923 924 /* Careful about overflows.. */ 925 rlen = PAGE_ALIGN(len); 926 if (!rlen || rlen > TASK_SIZE) 927 return -ENOMEM; 928 929 /* offset overflow? */ 930 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 931 return -EOVERFLOW; 932 933 if (file) { 934 /* validate file mapping requests */ 935 struct address_space *mapping; 936 937 /* files must support mmap */ 938 if (!file->f_op || !file->f_op->mmap) 939 return -ENODEV; 940 941 /* work out if what we've got could possibly be shared 942 * - we support chardevs that provide their own "memory" 943 * - we support files/blockdevs that are memory backed 944 */ 945 mapping = file->f_mapping; 946 if (!mapping) 947 mapping = file_inode(file)->i_mapping; 948 949 capabilities = 0; 950 if (mapping && mapping->backing_dev_info) 951 capabilities = mapping->backing_dev_info->capabilities; 952 953 if (!capabilities) { 954 /* no explicit capabilities set, so assume some 955 * defaults */ 956 switch (file_inode(file)->i_mode & S_IFMT) { 957 case S_IFREG: 958 case S_IFBLK: 959 capabilities = BDI_CAP_MAP_COPY; 960 break; 961 962 case S_IFCHR: 963 capabilities = 964 BDI_CAP_MAP_DIRECT | 965 BDI_CAP_READ_MAP | 966 BDI_CAP_WRITE_MAP; 967 break; 968 969 default: 970 return -EINVAL; 971 } 972 } 973 974 /* eliminate any capabilities that we can't support on this 975 * device */ 976 if (!file->f_op->get_unmapped_area) 977 capabilities &= ~BDI_CAP_MAP_DIRECT; 978 if (!file->f_op->read) 979 capabilities &= ~BDI_CAP_MAP_COPY; 980 981 /* The file shall have been opened with read permission. */ 982 if (!(file->f_mode & FMODE_READ)) 983 return -EACCES; 984 985 if (flags & MAP_SHARED) { 986 /* do checks for writing, appending and locking */ 987 if ((prot & PROT_WRITE) && 988 !(file->f_mode & FMODE_WRITE)) 989 return -EACCES; 990 991 if (IS_APPEND(file_inode(file)) && 992 (file->f_mode & FMODE_WRITE)) 993 return -EACCES; 994 995 if (locks_verify_locked(file_inode(file))) 996 return -EAGAIN; 997 998 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 999 return -ENODEV; 1000 1001 /* we mustn't privatise shared mappings */ 1002 capabilities &= ~BDI_CAP_MAP_COPY; 1003 } 1004 else { 1005 /* we're going to read the file into private memory we 1006 * allocate */ 1007 if (!(capabilities & BDI_CAP_MAP_COPY)) 1008 return -ENODEV; 1009 1010 /* we don't permit a private writable mapping to be 1011 * shared with the backing device */ 1012 if (prot & PROT_WRITE) 1013 capabilities &= ~BDI_CAP_MAP_DIRECT; 1014 } 1015 1016 if (capabilities & BDI_CAP_MAP_DIRECT) { 1017 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 1018 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 1019 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 1020 ) { 1021 capabilities &= ~BDI_CAP_MAP_DIRECT; 1022 if (flags & MAP_SHARED) { 1023 printk(KERN_WARNING 1024 "MAP_SHARED not completely supported on !MMU\n"); 1025 return -EINVAL; 1026 } 1027 } 1028 } 1029 1030 /* handle executable mappings and implied executable 1031 * mappings */ 1032 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1033 if (prot & PROT_EXEC) 1034 return -EPERM; 1035 } 1036 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 1037 /* handle implication of PROT_EXEC by PROT_READ */ 1038 if (current->personality & READ_IMPLIES_EXEC) { 1039 if (capabilities & BDI_CAP_EXEC_MAP) 1040 prot |= PROT_EXEC; 1041 } 1042 } 1043 else if ((prot & PROT_READ) && 1044 (prot & PROT_EXEC) && 1045 !(capabilities & BDI_CAP_EXEC_MAP) 1046 ) { 1047 /* backing file is not executable, try to copy */ 1048 capabilities &= ~BDI_CAP_MAP_DIRECT; 1049 } 1050 } 1051 else { 1052 /* anonymous mappings are always memory backed and can be 1053 * privately mapped 1054 */ 1055 capabilities = BDI_CAP_MAP_COPY; 1056 1057 /* handle PROT_EXEC implication by PROT_READ */ 1058 if ((prot & PROT_READ) && 1059 (current->personality & READ_IMPLIES_EXEC)) 1060 prot |= PROT_EXEC; 1061 } 1062 1063 /* allow the security API to have its say */ 1064 ret = security_mmap_addr(addr); 1065 if (ret < 0) 1066 return ret; 1067 1068 /* looks okay */ 1069 *_capabilities = capabilities; 1070 return 0; 1071 } 1072 1073 /* 1074 * we've determined that we can make the mapping, now translate what we 1075 * now know into VMA flags 1076 */ 1077 static unsigned long determine_vm_flags(struct file *file, 1078 unsigned long prot, 1079 unsigned long flags, 1080 unsigned long capabilities) 1081 { 1082 unsigned long vm_flags; 1083 1084 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1085 /* vm_flags |= mm->def_flags; */ 1086 1087 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1088 /* attempt to share read-only copies of mapped file chunks */ 1089 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1090 if (file && !(prot & PROT_WRITE)) 1091 vm_flags |= VM_MAYSHARE; 1092 } else { 1093 /* overlay a shareable mapping on the backing device or inode 1094 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1095 * romfs/cramfs */ 1096 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); 1097 if (flags & MAP_SHARED) 1098 vm_flags |= VM_SHARED; 1099 } 1100 1101 /* refuse to let anyone share private mappings with this process if 1102 * it's being traced - otherwise breakpoints set in it may interfere 1103 * with another untraced process 1104 */ 1105 if ((flags & MAP_PRIVATE) && current->ptrace) 1106 vm_flags &= ~VM_MAYSHARE; 1107 1108 return vm_flags; 1109 } 1110 1111 /* 1112 * set up a shared mapping on a file (the driver or filesystem provides and 1113 * pins the storage) 1114 */ 1115 static int do_mmap_shared_file(struct vm_area_struct *vma) 1116 { 1117 int ret; 1118 1119 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1120 if (ret == 0) { 1121 vma->vm_region->vm_top = vma->vm_region->vm_end; 1122 return 0; 1123 } 1124 if (ret != -ENOSYS) 1125 return ret; 1126 1127 /* getting -ENOSYS indicates that direct mmap isn't possible (as 1128 * opposed to tried but failed) so we can only give a suitable error as 1129 * it's not possible to make a private copy if MAP_SHARED was given */ 1130 return -ENODEV; 1131 } 1132 1133 /* 1134 * set up a private mapping or an anonymous shared mapping 1135 */ 1136 static int do_mmap_private(struct vm_area_struct *vma, 1137 struct vm_region *region, 1138 unsigned long len, 1139 unsigned long capabilities) 1140 { 1141 struct page *pages; 1142 unsigned long total, point, n; 1143 void *base; 1144 int ret, order; 1145 1146 /* invoke the file's mapping function so that it can keep track of 1147 * shared mappings on devices or memory 1148 * - VM_MAYSHARE will be set if it may attempt to share 1149 */ 1150 if (capabilities & BDI_CAP_MAP_DIRECT) { 1151 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1152 if (ret == 0) { 1153 /* shouldn't return success if we're not sharing */ 1154 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1155 vma->vm_region->vm_top = vma->vm_region->vm_end; 1156 return 0; 1157 } 1158 if (ret != -ENOSYS) 1159 return ret; 1160 1161 /* getting an ENOSYS error indicates that direct mmap isn't 1162 * possible (as opposed to tried but failed) so we'll try to 1163 * make a private copy of the data and map that instead */ 1164 } 1165 1166 1167 /* allocate some memory to hold the mapping 1168 * - note that this may not return a page-aligned address if the object 1169 * we're allocating is smaller than a page 1170 */ 1171 order = get_order(len); 1172 kdebug("alloc order %d for %lx", order, len); 1173 1174 pages = alloc_pages(GFP_KERNEL, order); 1175 if (!pages) 1176 goto enomem; 1177 1178 total = 1 << order; 1179 atomic_long_add(total, &mmap_pages_allocated); 1180 1181 point = len >> PAGE_SHIFT; 1182 1183 /* we allocated a power-of-2 sized page set, so we may want to trim off 1184 * the excess */ 1185 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1186 while (total > point) { 1187 order = ilog2(total - point); 1188 n = 1 << order; 1189 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1190 atomic_long_sub(n, &mmap_pages_allocated); 1191 total -= n; 1192 set_page_refcounted(pages + total); 1193 __free_pages(pages + total, order); 1194 } 1195 } 1196 1197 for (point = 1; point < total; point++) 1198 set_page_refcounted(&pages[point]); 1199 1200 base = page_address(pages); 1201 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1202 region->vm_start = (unsigned long) base; 1203 region->vm_end = region->vm_start + len; 1204 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1205 1206 vma->vm_start = region->vm_start; 1207 vma->vm_end = region->vm_start + len; 1208 1209 if (vma->vm_file) { 1210 /* read the contents of a file into the copy */ 1211 mm_segment_t old_fs; 1212 loff_t fpos; 1213 1214 fpos = vma->vm_pgoff; 1215 fpos <<= PAGE_SHIFT; 1216 1217 old_fs = get_fs(); 1218 set_fs(KERNEL_DS); 1219 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); 1220 set_fs(old_fs); 1221 1222 if (ret < 0) 1223 goto error_free; 1224 1225 /* clear the last little bit */ 1226 if (ret < len) 1227 memset(base + ret, 0, len - ret); 1228 1229 } 1230 1231 return 0; 1232 1233 error_free: 1234 free_page_series(region->vm_start, region->vm_top); 1235 region->vm_start = vma->vm_start = 0; 1236 region->vm_end = vma->vm_end = 0; 1237 region->vm_top = 0; 1238 return ret; 1239 1240 enomem: 1241 printk("Allocation of length %lu from process %d (%s) failed\n", 1242 len, current->pid, current->comm); 1243 show_free_areas(0); 1244 return -ENOMEM; 1245 } 1246 1247 /* 1248 * handle mapping creation for uClinux 1249 */ 1250 unsigned long do_mmap_pgoff(struct file *file, 1251 unsigned long addr, 1252 unsigned long len, 1253 unsigned long prot, 1254 unsigned long flags, 1255 unsigned long pgoff, 1256 unsigned long *populate) 1257 { 1258 struct vm_area_struct *vma; 1259 struct vm_region *region; 1260 struct rb_node *rb; 1261 unsigned long capabilities, vm_flags, result; 1262 int ret; 1263 1264 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1265 1266 *populate = 0; 1267 1268 /* decide whether we should attempt the mapping, and if so what sort of 1269 * mapping */ 1270 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1271 &capabilities); 1272 if (ret < 0) { 1273 kleave(" = %d [val]", ret); 1274 return ret; 1275 } 1276 1277 /* we ignore the address hint */ 1278 addr = 0; 1279 len = PAGE_ALIGN(len); 1280 1281 /* we've determined that we can make the mapping, now translate what we 1282 * now know into VMA flags */ 1283 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1284 1285 /* we're going to need to record the mapping */ 1286 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1287 if (!region) 1288 goto error_getting_region; 1289 1290 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1291 if (!vma) 1292 goto error_getting_vma; 1293 1294 region->vm_usage = 1; 1295 region->vm_flags = vm_flags; 1296 region->vm_pgoff = pgoff; 1297 1298 INIT_LIST_HEAD(&vma->anon_vma_chain); 1299 vma->vm_flags = vm_flags; 1300 vma->vm_pgoff = pgoff; 1301 1302 if (file) { 1303 region->vm_file = get_file(file); 1304 vma->vm_file = get_file(file); 1305 } 1306 1307 down_write(&nommu_region_sem); 1308 1309 /* if we want to share, we need to check for regions created by other 1310 * mmap() calls that overlap with our proposed mapping 1311 * - we can only share with a superset match on most regular files 1312 * - shared mappings on character devices and memory backed files are 1313 * permitted to overlap inexactly as far as we are concerned for in 1314 * these cases, sharing is handled in the driver or filesystem rather 1315 * than here 1316 */ 1317 if (vm_flags & VM_MAYSHARE) { 1318 struct vm_region *pregion; 1319 unsigned long pglen, rpglen, pgend, rpgend, start; 1320 1321 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1322 pgend = pgoff + pglen; 1323 1324 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1325 pregion = rb_entry(rb, struct vm_region, vm_rb); 1326 1327 if (!(pregion->vm_flags & VM_MAYSHARE)) 1328 continue; 1329 1330 /* search for overlapping mappings on the same file */ 1331 if (file_inode(pregion->vm_file) != 1332 file_inode(file)) 1333 continue; 1334 1335 if (pregion->vm_pgoff >= pgend) 1336 continue; 1337 1338 rpglen = pregion->vm_end - pregion->vm_start; 1339 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1340 rpgend = pregion->vm_pgoff + rpglen; 1341 if (pgoff >= rpgend) 1342 continue; 1343 1344 /* handle inexactly overlapping matches between 1345 * mappings */ 1346 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1347 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1348 /* new mapping is not a subset of the region */ 1349 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1350 goto sharing_violation; 1351 continue; 1352 } 1353 1354 /* we've found a region we can share */ 1355 pregion->vm_usage++; 1356 vma->vm_region = pregion; 1357 start = pregion->vm_start; 1358 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1359 vma->vm_start = start; 1360 vma->vm_end = start + len; 1361 1362 if (pregion->vm_flags & VM_MAPPED_COPY) { 1363 kdebug("share copy"); 1364 vma->vm_flags |= VM_MAPPED_COPY; 1365 } else { 1366 kdebug("share mmap"); 1367 ret = do_mmap_shared_file(vma); 1368 if (ret < 0) { 1369 vma->vm_region = NULL; 1370 vma->vm_start = 0; 1371 vma->vm_end = 0; 1372 pregion->vm_usage--; 1373 pregion = NULL; 1374 goto error_just_free; 1375 } 1376 } 1377 fput(region->vm_file); 1378 kmem_cache_free(vm_region_jar, region); 1379 region = pregion; 1380 result = start; 1381 goto share; 1382 } 1383 1384 /* obtain the address at which to make a shared mapping 1385 * - this is the hook for quasi-memory character devices to 1386 * tell us the location of a shared mapping 1387 */ 1388 if (capabilities & BDI_CAP_MAP_DIRECT) { 1389 addr = file->f_op->get_unmapped_area(file, addr, len, 1390 pgoff, flags); 1391 if (IS_ERR_VALUE(addr)) { 1392 ret = addr; 1393 if (ret != -ENOSYS) 1394 goto error_just_free; 1395 1396 /* the driver refused to tell us where to site 1397 * the mapping so we'll have to attempt to copy 1398 * it */ 1399 ret = -ENODEV; 1400 if (!(capabilities & BDI_CAP_MAP_COPY)) 1401 goto error_just_free; 1402 1403 capabilities &= ~BDI_CAP_MAP_DIRECT; 1404 } else { 1405 vma->vm_start = region->vm_start = addr; 1406 vma->vm_end = region->vm_end = addr + len; 1407 } 1408 } 1409 } 1410 1411 vma->vm_region = region; 1412 1413 /* set up the mapping 1414 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set 1415 */ 1416 if (file && vma->vm_flags & VM_SHARED) 1417 ret = do_mmap_shared_file(vma); 1418 else 1419 ret = do_mmap_private(vma, region, len, capabilities); 1420 if (ret < 0) 1421 goto error_just_free; 1422 add_nommu_region(region); 1423 1424 /* clear anonymous mappings that don't ask for uninitialized data */ 1425 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) 1426 memset((void *)region->vm_start, 0, 1427 region->vm_end - region->vm_start); 1428 1429 /* okay... we have a mapping; now we have to register it */ 1430 result = vma->vm_start; 1431 1432 current->mm->total_vm += len >> PAGE_SHIFT; 1433 1434 share: 1435 add_vma_to_mm(current->mm, vma); 1436 1437 /* we flush the region from the icache only when the first executable 1438 * mapping of it is made */ 1439 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1440 flush_icache_range(region->vm_start, region->vm_end); 1441 region->vm_icache_flushed = true; 1442 } 1443 1444 up_write(&nommu_region_sem); 1445 1446 kleave(" = %lx", result); 1447 return result; 1448 1449 error_just_free: 1450 up_write(&nommu_region_sem); 1451 error: 1452 if (region->vm_file) 1453 fput(region->vm_file); 1454 kmem_cache_free(vm_region_jar, region); 1455 if (vma->vm_file) 1456 fput(vma->vm_file); 1457 kmem_cache_free(vm_area_cachep, vma); 1458 kleave(" = %d", ret); 1459 return ret; 1460 1461 sharing_violation: 1462 up_write(&nommu_region_sem); 1463 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1464 ret = -EINVAL; 1465 goto error; 1466 1467 error_getting_vma: 1468 kmem_cache_free(vm_region_jar, region); 1469 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1470 " from process %d failed\n", 1471 len, current->pid); 1472 show_free_areas(0); 1473 return -ENOMEM; 1474 1475 error_getting_region: 1476 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1477 " from process %d failed\n", 1478 len, current->pid); 1479 show_free_areas(0); 1480 return -ENOMEM; 1481 } 1482 1483 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1484 unsigned long, prot, unsigned long, flags, 1485 unsigned long, fd, unsigned long, pgoff) 1486 { 1487 struct file *file = NULL; 1488 unsigned long retval = -EBADF; 1489 1490 audit_mmap_fd(fd, flags); 1491 if (!(flags & MAP_ANONYMOUS)) { 1492 file = fget(fd); 1493 if (!file) 1494 goto out; 1495 } 1496 1497 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1498 1499 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1500 1501 if (file) 1502 fput(file); 1503 out: 1504 return retval; 1505 } 1506 1507 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1508 struct mmap_arg_struct { 1509 unsigned long addr; 1510 unsigned long len; 1511 unsigned long prot; 1512 unsigned long flags; 1513 unsigned long fd; 1514 unsigned long offset; 1515 }; 1516 1517 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1518 { 1519 struct mmap_arg_struct a; 1520 1521 if (copy_from_user(&a, arg, sizeof(a))) 1522 return -EFAULT; 1523 if (a.offset & ~PAGE_MASK) 1524 return -EINVAL; 1525 1526 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1527 a.offset >> PAGE_SHIFT); 1528 } 1529 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1530 1531 /* 1532 * split a vma into two pieces at address 'addr', a new vma is allocated either 1533 * for the first part or the tail. 1534 */ 1535 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1536 unsigned long addr, int new_below) 1537 { 1538 struct vm_area_struct *new; 1539 struct vm_region *region; 1540 unsigned long npages; 1541 1542 kenter(""); 1543 1544 /* we're only permitted to split anonymous regions (these should have 1545 * only a single usage on the region) */ 1546 if (vma->vm_file) 1547 return -ENOMEM; 1548 1549 if (mm->map_count >= sysctl_max_map_count) 1550 return -ENOMEM; 1551 1552 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1553 if (!region) 1554 return -ENOMEM; 1555 1556 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1557 if (!new) { 1558 kmem_cache_free(vm_region_jar, region); 1559 return -ENOMEM; 1560 } 1561 1562 /* most fields are the same, copy all, and then fixup */ 1563 *new = *vma; 1564 *region = *vma->vm_region; 1565 new->vm_region = region; 1566 1567 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1568 1569 if (new_below) { 1570 region->vm_top = region->vm_end = new->vm_end = addr; 1571 } else { 1572 region->vm_start = new->vm_start = addr; 1573 region->vm_pgoff = new->vm_pgoff += npages; 1574 } 1575 1576 if (new->vm_ops && new->vm_ops->open) 1577 new->vm_ops->open(new); 1578 1579 delete_vma_from_mm(vma); 1580 down_write(&nommu_region_sem); 1581 delete_nommu_region(vma->vm_region); 1582 if (new_below) { 1583 vma->vm_region->vm_start = vma->vm_start = addr; 1584 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1585 } else { 1586 vma->vm_region->vm_end = vma->vm_end = addr; 1587 vma->vm_region->vm_top = addr; 1588 } 1589 add_nommu_region(vma->vm_region); 1590 add_nommu_region(new->vm_region); 1591 up_write(&nommu_region_sem); 1592 add_vma_to_mm(mm, vma); 1593 add_vma_to_mm(mm, new); 1594 return 0; 1595 } 1596 1597 /* 1598 * shrink a VMA by removing the specified chunk from either the beginning or 1599 * the end 1600 */ 1601 static int shrink_vma(struct mm_struct *mm, 1602 struct vm_area_struct *vma, 1603 unsigned long from, unsigned long to) 1604 { 1605 struct vm_region *region; 1606 1607 kenter(""); 1608 1609 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1610 * and list */ 1611 delete_vma_from_mm(vma); 1612 if (from > vma->vm_start) 1613 vma->vm_end = from; 1614 else 1615 vma->vm_start = to; 1616 add_vma_to_mm(mm, vma); 1617 1618 /* cut the backing region down to size */ 1619 region = vma->vm_region; 1620 BUG_ON(region->vm_usage != 1); 1621 1622 down_write(&nommu_region_sem); 1623 delete_nommu_region(region); 1624 if (from > region->vm_start) { 1625 to = region->vm_top; 1626 region->vm_top = region->vm_end = from; 1627 } else { 1628 region->vm_start = to; 1629 } 1630 add_nommu_region(region); 1631 up_write(&nommu_region_sem); 1632 1633 free_page_series(from, to); 1634 return 0; 1635 } 1636 1637 /* 1638 * release a mapping 1639 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1640 * VMA, though it need not cover the whole VMA 1641 */ 1642 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1643 { 1644 struct vm_area_struct *vma; 1645 unsigned long end; 1646 int ret; 1647 1648 kenter(",%lx,%zx", start, len); 1649 1650 len = PAGE_ALIGN(len); 1651 if (len == 0) 1652 return -EINVAL; 1653 1654 end = start + len; 1655 1656 /* find the first potentially overlapping VMA */ 1657 vma = find_vma(mm, start); 1658 if (!vma) { 1659 static int limit = 0; 1660 if (limit < 5) { 1661 printk(KERN_WARNING 1662 "munmap of memory not mmapped by process %d" 1663 " (%s): 0x%lx-0x%lx\n", 1664 current->pid, current->comm, 1665 start, start + len - 1); 1666 limit++; 1667 } 1668 return -EINVAL; 1669 } 1670 1671 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1672 if (vma->vm_file) { 1673 do { 1674 if (start > vma->vm_start) { 1675 kleave(" = -EINVAL [miss]"); 1676 return -EINVAL; 1677 } 1678 if (end == vma->vm_end) 1679 goto erase_whole_vma; 1680 vma = vma->vm_next; 1681 } while (vma); 1682 kleave(" = -EINVAL [split file]"); 1683 return -EINVAL; 1684 } else { 1685 /* the chunk must be a subset of the VMA found */ 1686 if (start == vma->vm_start && end == vma->vm_end) 1687 goto erase_whole_vma; 1688 if (start < vma->vm_start || end > vma->vm_end) { 1689 kleave(" = -EINVAL [superset]"); 1690 return -EINVAL; 1691 } 1692 if (start & ~PAGE_MASK) { 1693 kleave(" = -EINVAL [unaligned start]"); 1694 return -EINVAL; 1695 } 1696 if (end != vma->vm_end && end & ~PAGE_MASK) { 1697 kleave(" = -EINVAL [unaligned split]"); 1698 return -EINVAL; 1699 } 1700 if (start != vma->vm_start && end != vma->vm_end) { 1701 ret = split_vma(mm, vma, start, 1); 1702 if (ret < 0) { 1703 kleave(" = %d [split]", ret); 1704 return ret; 1705 } 1706 } 1707 return shrink_vma(mm, vma, start, end); 1708 } 1709 1710 erase_whole_vma: 1711 delete_vma_from_mm(vma); 1712 delete_vma(mm, vma); 1713 kleave(" = 0"); 1714 return 0; 1715 } 1716 EXPORT_SYMBOL(do_munmap); 1717 1718 int vm_munmap(unsigned long addr, size_t len) 1719 { 1720 struct mm_struct *mm = current->mm; 1721 int ret; 1722 1723 down_write(&mm->mmap_sem); 1724 ret = do_munmap(mm, addr, len); 1725 up_write(&mm->mmap_sem); 1726 return ret; 1727 } 1728 EXPORT_SYMBOL(vm_munmap); 1729 1730 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1731 { 1732 return vm_munmap(addr, len); 1733 } 1734 1735 /* 1736 * release all the mappings made in a process's VM space 1737 */ 1738 void exit_mmap(struct mm_struct *mm) 1739 { 1740 struct vm_area_struct *vma; 1741 1742 if (!mm) 1743 return; 1744 1745 kenter(""); 1746 1747 mm->total_vm = 0; 1748 1749 while ((vma = mm->mmap)) { 1750 mm->mmap = vma->vm_next; 1751 delete_vma_from_mm(vma); 1752 delete_vma(mm, vma); 1753 cond_resched(); 1754 } 1755 1756 kleave(""); 1757 } 1758 1759 unsigned long vm_brk(unsigned long addr, unsigned long len) 1760 { 1761 return -ENOMEM; 1762 } 1763 1764 /* 1765 * expand (or shrink) an existing mapping, potentially moving it at the same 1766 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1767 * 1768 * under NOMMU conditions, we only permit changing a mapping's size, and only 1769 * as long as it stays within the region allocated by do_mmap_private() and the 1770 * block is not shareable 1771 * 1772 * MREMAP_FIXED is not supported under NOMMU conditions 1773 */ 1774 static unsigned long do_mremap(unsigned long addr, 1775 unsigned long old_len, unsigned long new_len, 1776 unsigned long flags, unsigned long new_addr) 1777 { 1778 struct vm_area_struct *vma; 1779 1780 /* insanity checks first */ 1781 old_len = PAGE_ALIGN(old_len); 1782 new_len = PAGE_ALIGN(new_len); 1783 if (old_len == 0 || new_len == 0) 1784 return (unsigned long) -EINVAL; 1785 1786 if (addr & ~PAGE_MASK) 1787 return -EINVAL; 1788 1789 if (flags & MREMAP_FIXED && new_addr != addr) 1790 return (unsigned long) -EINVAL; 1791 1792 vma = find_vma_exact(current->mm, addr, old_len); 1793 if (!vma) 1794 return (unsigned long) -EINVAL; 1795 1796 if (vma->vm_end != vma->vm_start + old_len) 1797 return (unsigned long) -EFAULT; 1798 1799 if (vma->vm_flags & VM_MAYSHARE) 1800 return (unsigned long) -EPERM; 1801 1802 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1803 return (unsigned long) -ENOMEM; 1804 1805 /* all checks complete - do it */ 1806 vma->vm_end = vma->vm_start + new_len; 1807 return vma->vm_start; 1808 } 1809 1810 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1811 unsigned long, new_len, unsigned long, flags, 1812 unsigned long, new_addr) 1813 { 1814 unsigned long ret; 1815 1816 down_write(¤t->mm->mmap_sem); 1817 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1818 up_write(¤t->mm->mmap_sem); 1819 return ret; 1820 } 1821 1822 struct page *follow_page_mask(struct vm_area_struct *vma, 1823 unsigned long address, unsigned int flags, 1824 unsigned int *page_mask) 1825 { 1826 *page_mask = 0; 1827 return NULL; 1828 } 1829 1830 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1831 unsigned long pfn, unsigned long size, pgprot_t prot) 1832 { 1833 if (addr != (pfn << PAGE_SHIFT)) 1834 return -EINVAL; 1835 1836 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 1837 return 0; 1838 } 1839 EXPORT_SYMBOL(remap_pfn_range); 1840 1841 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 1842 { 1843 unsigned long pfn = start >> PAGE_SHIFT; 1844 unsigned long vm_len = vma->vm_end - vma->vm_start; 1845 1846 pfn += vma->vm_pgoff; 1847 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 1848 } 1849 EXPORT_SYMBOL(vm_iomap_memory); 1850 1851 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1852 unsigned long pgoff) 1853 { 1854 unsigned int size = vma->vm_end - vma->vm_start; 1855 1856 if (!(vma->vm_flags & VM_USERMAP)) 1857 return -EINVAL; 1858 1859 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1860 vma->vm_end = vma->vm_start + size; 1861 1862 return 0; 1863 } 1864 EXPORT_SYMBOL(remap_vmalloc_range); 1865 1866 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1867 unsigned long len, unsigned long pgoff, unsigned long flags) 1868 { 1869 return -ENOMEM; 1870 } 1871 1872 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1873 { 1874 } 1875 1876 void unmap_mapping_range(struct address_space *mapping, 1877 loff_t const holebegin, loff_t const holelen, 1878 int even_cows) 1879 { 1880 } 1881 EXPORT_SYMBOL(unmap_mapping_range); 1882 1883 /* 1884 * Check that a process has enough memory to allocate a new virtual 1885 * mapping. 0 means there is enough memory for the allocation to 1886 * succeed and -ENOMEM implies there is not. 1887 * 1888 * We currently support three overcommit policies, which are set via the 1889 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1890 * 1891 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1892 * Additional code 2002 Jul 20 by Robert Love. 1893 * 1894 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1895 * 1896 * Note this is a helper function intended to be used by LSMs which 1897 * wish to use this logic. 1898 */ 1899 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1900 { 1901 unsigned long free, allowed, reserve; 1902 1903 vm_acct_memory(pages); 1904 1905 /* 1906 * Sometimes we want to use more memory than we have 1907 */ 1908 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1909 return 0; 1910 1911 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1912 free = global_page_state(NR_FREE_PAGES); 1913 free += global_page_state(NR_FILE_PAGES); 1914 1915 /* 1916 * shmem pages shouldn't be counted as free in this 1917 * case, they can't be purged, only swapped out, and 1918 * that won't affect the overall amount of available 1919 * memory in the system. 1920 */ 1921 free -= global_page_state(NR_SHMEM); 1922 1923 free += get_nr_swap_pages(); 1924 1925 /* 1926 * Any slabs which are created with the 1927 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1928 * which are reclaimable, under pressure. The dentry 1929 * cache and most inode caches should fall into this 1930 */ 1931 free += global_page_state(NR_SLAB_RECLAIMABLE); 1932 1933 /* 1934 * Leave reserved pages. The pages are not for anonymous pages. 1935 */ 1936 if (free <= totalreserve_pages) 1937 goto error; 1938 else 1939 free -= totalreserve_pages; 1940 1941 /* 1942 * Reserve some for root 1943 */ 1944 if (!cap_sys_admin) 1945 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); 1946 1947 if (free > pages) 1948 return 0; 1949 1950 goto error; 1951 } 1952 1953 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1954 /* 1955 * Reserve some 3% for root 1956 */ 1957 if (!cap_sys_admin) 1958 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); 1959 allowed += total_swap_pages; 1960 1961 /* 1962 * Don't let a single process grow so big a user can't recover 1963 */ 1964 if (mm) { 1965 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); 1966 allowed -= min(mm->total_vm / 32, reserve); 1967 } 1968 1969 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1970 return 0; 1971 1972 error: 1973 vm_unacct_memory(pages); 1974 1975 return -ENOMEM; 1976 } 1977 1978 int in_gate_area_no_mm(unsigned long addr) 1979 { 1980 return 0; 1981 } 1982 1983 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1984 { 1985 BUG(); 1986 return 0; 1987 } 1988 EXPORT_SYMBOL(filemap_fault); 1989 1990 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr, 1991 unsigned long size, pgoff_t pgoff) 1992 { 1993 BUG(); 1994 return 0; 1995 } 1996 EXPORT_SYMBOL(generic_file_remap_pages); 1997 1998 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 1999 unsigned long addr, void *buf, int len, int write) 2000 { 2001 struct vm_area_struct *vma; 2002 2003 down_read(&mm->mmap_sem); 2004 2005 /* the access must start within one of the target process's mappings */ 2006 vma = find_vma(mm, addr); 2007 if (vma) { 2008 /* don't overrun this mapping */ 2009 if (addr + len >= vma->vm_end) 2010 len = vma->vm_end - addr; 2011 2012 /* only read or write mappings where it is permitted */ 2013 if (write && vma->vm_flags & VM_MAYWRITE) 2014 copy_to_user_page(vma, NULL, addr, 2015 (void *) addr, buf, len); 2016 else if (!write && vma->vm_flags & VM_MAYREAD) 2017 copy_from_user_page(vma, NULL, addr, 2018 buf, (void *) addr, len); 2019 else 2020 len = 0; 2021 } else { 2022 len = 0; 2023 } 2024 2025 up_read(&mm->mmap_sem); 2026 2027 return len; 2028 } 2029 2030 /** 2031 * @access_remote_vm - access another process' address space 2032 * @mm: the mm_struct of the target address space 2033 * @addr: start address to access 2034 * @buf: source or destination buffer 2035 * @len: number of bytes to transfer 2036 * @write: whether the access is a write 2037 * 2038 * The caller must hold a reference on @mm. 2039 */ 2040 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 2041 void *buf, int len, int write) 2042 { 2043 return __access_remote_vm(NULL, mm, addr, buf, len, write); 2044 } 2045 2046 /* 2047 * Access another process' address space. 2048 * - source/target buffer must be kernel space 2049 */ 2050 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2051 { 2052 struct mm_struct *mm; 2053 2054 if (addr + len < addr) 2055 return 0; 2056 2057 mm = get_task_mm(tsk); 2058 if (!mm) 2059 return 0; 2060 2061 len = __access_remote_vm(tsk, mm, addr, buf, len, write); 2062 2063 mmput(mm); 2064 return len; 2065 } 2066 2067 /** 2068 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 2069 * @inode: The inode to check 2070 * @size: The current filesize of the inode 2071 * @newsize: The proposed filesize of the inode 2072 * 2073 * Check the shared mappings on an inode on behalf of a shrinking truncate to 2074 * make sure that that any outstanding VMAs aren't broken and then shrink the 2075 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't 2076 * automatically grant mappings that are too large. 2077 */ 2078 int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 2079 size_t newsize) 2080 { 2081 struct vm_area_struct *vma; 2082 struct vm_region *region; 2083 pgoff_t low, high; 2084 size_t r_size, r_top; 2085 2086 low = newsize >> PAGE_SHIFT; 2087 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 2088 2089 down_write(&nommu_region_sem); 2090 mutex_lock(&inode->i_mapping->i_mmap_mutex); 2091 2092 /* search for VMAs that fall within the dead zone */ 2093 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { 2094 /* found one - only interested if it's shared out of the page 2095 * cache */ 2096 if (vma->vm_flags & VM_SHARED) { 2097 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2098 up_write(&nommu_region_sem); 2099 return -ETXTBSY; /* not quite true, but near enough */ 2100 } 2101 } 2102 2103 /* reduce any regions that overlap the dead zone - if in existence, 2104 * these will be pointed to by VMAs that don't overlap the dead zone 2105 * 2106 * we don't check for any regions that start beyond the EOF as there 2107 * shouldn't be any 2108 */ 2109 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 2110 0, ULONG_MAX) { 2111 if (!(vma->vm_flags & VM_SHARED)) 2112 continue; 2113 2114 region = vma->vm_region; 2115 r_size = region->vm_top - region->vm_start; 2116 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 2117 2118 if (r_top > newsize) { 2119 region->vm_top -= r_top - newsize; 2120 if (region->vm_end > region->vm_top) 2121 region->vm_end = region->vm_top; 2122 } 2123 } 2124 2125 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2126 up_write(&nommu_region_sem); 2127 return 0; 2128 } 2129 2130 /* 2131 * Initialise sysctl_user_reserve_kbytes. 2132 * 2133 * This is intended to prevent a user from starting a single memory hogging 2134 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER 2135 * mode. 2136 * 2137 * The default value is min(3% of free memory, 128MB) 2138 * 128MB is enough to recover with sshd/login, bash, and top/kill. 2139 */ 2140 static int __meminit init_user_reserve(void) 2141 { 2142 unsigned long free_kbytes; 2143 2144 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 2145 2146 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); 2147 return 0; 2148 } 2149 module_init(init_user_reserve) 2150 2151 /* 2152 * Initialise sysctl_admin_reserve_kbytes. 2153 * 2154 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin 2155 * to log in and kill a memory hogging process. 2156 * 2157 * Systems with more than 256MB will reserve 8MB, enough to recover 2158 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will 2159 * only reserve 3% of free pages by default. 2160 */ 2161 static int __meminit init_admin_reserve(void) 2162 { 2163 unsigned long free_kbytes; 2164 2165 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 2166 2167 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); 2168 return 0; 2169 } 2170 module_init(init_admin_reserve) 2171