1 /*- 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91 33 */ 34 35 /*- 36 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 37 * All rights reserved. 38 * 39 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 40 * 41 * Permission to use, copy, modify and distribute this software and 42 * its documentation is hereby granted, provided that both the copyright 43 * notice and this permission notice appear in all copies of the 44 * software, derivative works or modified versions, and any portions 45 * thereof, and that both notices appear in supporting documentation. 46 * 47 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 48 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 49 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 50 * 51 * Carnegie Mellon requests users of this software to return to 52 * 53 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 54 * School of Computer Science 55 * Carnegie Mellon University 56 * Pittsburgh PA 15213-3890 57 * 58 * any improvements or extensions that they make and grant Carnegie the 59 * rights to redistribute these changes. 60 */ 61 62 /* 63 * GENERAL RULES ON VM_PAGE MANIPULATION 64 * 65 * - a pageq mutex is required when adding or removing a page from a 66 * page queue (vm_page_queue[]), regardless of other mutexes or the 67 * busy state of a page. 68 * 69 * - a hash chain mutex is required when associating or disassociating 70 * a page from the VM PAGE CACHE hash table (vm_page_buckets), 71 * regardless of other mutexes or the busy state of a page. 72 * 73 * - either a hash chain mutex OR a busied page is required in order 74 * to modify the page flags. A hash chain mutex must be obtained in 75 * order to busy a page. A page's flags cannot be modified by a 76 * hash chain mutex if the page is marked busy. 77 * 78 * - The object memq mutex is held when inserting or removing 79 * pages from an object (vm_page_insert() or vm_page_remove()). This 80 * is different from the object's main mutex. 81 * 82 * Generally speaking, you have to be aware of side effects when running 83 * vm_page ops. A vm_page_lookup() will return with the hash chain 84 * locked, whether it was able to lookup the page or not. vm_page_free(), 85 * vm_page_cache(), vm_page_activate(), and a number of other routines 86 * will release the hash chain mutex for you. Intermediate manipulation 87 * routines such as vm_page_flag_set() expect the hash chain to be held 88 * on entry and the hash chain will remain held on return. 89 * 90 * pageq scanning can only occur with the pageq in question locked. 91 * We have a known bottleneck with the active queue, but the cache 92 * and free queues are actually arrays already. 93 */ 94 95 /* 96 * Resident memory management module. 97 */ 98 99 #include <sys/cdefs.h> 100 __FBSDID("$FreeBSD$"); 101 102 #include <sys/param.h> 103 #include <sys/systm.h> 104 #include <sys/lock.h> 105 #include <sys/kernel.h> 106 #include <sys/malloc.h> 107 #include <sys/mutex.h> 108 #include <sys/proc.h> 109 #include <sys/sysctl.h> 110 #include <sys/vmmeter.h> 111 #include <sys/vnode.h> 112 113 #include <vm/vm.h> 114 #include <vm/vm_param.h> 115 #include <vm/vm_kern.h> 116 #include <vm/vm_object.h> 117 #include <vm/vm_page.h> 118 #include <vm/vm_pageout.h> 119 #include <vm/vm_pager.h> 120 #include <vm/vm_extern.h> 121 #include <vm/uma.h> 122 #include <vm/uma_int.h> 123 124 #include <machine/md_var.h> 125 126 /* 127 * Associated with page of user-allocatable memory is a 128 * page structure. 129 */ 130 131 struct mtx vm_page_queue_mtx; 132 struct mtx vm_page_queue_free_mtx; 133 134 vm_page_t vm_page_array = 0; 135 int vm_page_array_size = 0; 136 long first_page = 0; 137 int vm_page_zero_count = 0; 138 139 static int boot_pages = UMA_BOOT_PAGES; 140 TUNABLE_INT("vm.boot_pages", &boot_pages); 141 SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0, 142 "number of pages allocated for bootstrapping the VM system"); 143 144 /* 145 * vm_set_page_size: 146 * 147 * Sets the page size, perhaps based upon the memory 148 * size. Must be called before any use of page-size 149 * dependent functions. 150 */ 151 void 152 vm_set_page_size(void) 153 { 154 if (cnt.v_page_size == 0) 155 cnt.v_page_size = PAGE_SIZE; 156 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) 157 panic("vm_set_page_size: page size not a power of two"); 158 } 159 160 /* 161 * vm_page_blacklist_lookup: 162 * 163 * See if a physical address in this page has been listed 164 * in the blacklist tunable. Entries in the tunable are 165 * separated by spaces or commas. If an invalid integer is 166 * encountered then the rest of the string is skipped. 167 */ 168 static int 169 vm_page_blacklist_lookup(char *list, vm_paddr_t pa) 170 { 171 vm_paddr_t bad; 172 char *cp, *pos; 173 174 for (pos = list; *pos != '\0'; pos = cp) { 175 bad = strtoq(pos, &cp, 0); 176 if (*cp != '\0') { 177 if (*cp == ' ' || *cp == ',') { 178 cp++; 179 if (cp == pos) 180 continue; 181 } else 182 break; 183 } 184 if (pa == trunc_page(bad)) 185 return (1); 186 } 187 return (0); 188 } 189 190 /* 191 * vm_page_startup: 192 * 193 * Initializes the resident memory module. 194 * 195 * Allocates memory for the page cells, and 196 * for the object/offset-to-page hash table headers. 197 * Each page cell is initialized and placed on the free list. 198 */ 199 vm_offset_t 200 vm_page_startup(vm_offset_t vaddr) 201 { 202 vm_offset_t mapped; 203 vm_size_t npages; 204 vm_paddr_t page_range; 205 vm_paddr_t new_end; 206 int i; 207 vm_paddr_t pa; 208 int nblocks; 209 vm_paddr_t last_pa; 210 char *list; 211 212 /* the biggest memory array is the second group of pages */ 213 vm_paddr_t end; 214 vm_paddr_t biggestsize; 215 int biggestone; 216 217 vm_paddr_t total; 218 219 total = 0; 220 biggestsize = 0; 221 biggestone = 0; 222 nblocks = 0; 223 vaddr = round_page(vaddr); 224 225 for (i = 0; phys_avail[i + 1]; i += 2) { 226 phys_avail[i] = round_page(phys_avail[i]); 227 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 228 } 229 230 for (i = 0; phys_avail[i + 1]; i += 2) { 231 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 232 233 if (size > biggestsize) { 234 biggestone = i; 235 biggestsize = size; 236 } 237 ++nblocks; 238 total += size; 239 } 240 241 end = phys_avail[biggestone+1]; 242 243 /* 244 * Initialize the locks. 245 */ 246 mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF | 247 MTX_RECURSE); 248 mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL, 249 MTX_SPIN); 250 251 /* 252 * Initialize the queue headers for the free queue, the active queue 253 * and the inactive queue. 254 */ 255 vm_pageq_init(); 256 257 /* 258 * Allocate memory for use when boot strapping the kernel memory 259 * allocator. 260 */ 261 new_end = end - (boot_pages * UMA_SLAB_SIZE); 262 new_end = trunc_page(new_end); 263 mapped = pmap_map(&vaddr, new_end, end, 264 VM_PROT_READ | VM_PROT_WRITE); 265 bzero((void *)mapped, end - new_end); 266 uma_startup((void *)mapped, boot_pages); 267 268 #if defined(__amd64__) || defined(__i386__) 269 /* 270 * Allocate a bitmap to indicate that a random physical page 271 * needs to be included in a minidump. 272 * 273 * The amd64 port needs this to indicate which direct map pages 274 * need to be dumped, via calls to dump_add_page()/dump_drop_page(). 275 * 276 * However, i386 still needs this workspace internally within the 277 * minidump code. In theory, they are not needed on i386, but are 278 * included should the sf_buf code decide to use them. 279 */ 280 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE; 281 vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY); 282 new_end -= vm_page_dump_size; 283 vm_page_dump = (void *)(uintptr_t)pmap_map(&vaddr, new_end, 284 new_end + vm_page_dump_size, VM_PROT_READ | VM_PROT_WRITE); 285 bzero((void *)vm_page_dump, vm_page_dump_size); 286 #endif 287 /* 288 * Compute the number of pages of memory that will be available for 289 * use (taking into account the overhead of a page structure per 290 * page). 291 */ 292 first_page = phys_avail[0] / PAGE_SIZE; 293 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 294 npages = (total - (page_range * sizeof(struct vm_page)) - 295 (end - new_end)) / PAGE_SIZE; 296 end = new_end; 297 298 /* 299 * Reserve an unmapped guard page to trap access to vm_page_array[-1]. 300 */ 301 vaddr += PAGE_SIZE; 302 303 /* 304 * Initialize the mem entry structures now, and put them in the free 305 * queue. 306 */ 307 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 308 mapped = pmap_map(&vaddr, new_end, end, 309 VM_PROT_READ | VM_PROT_WRITE); 310 vm_page_array = (vm_page_t) mapped; 311 #ifdef __amd64__ 312 /* 313 * pmap_map on amd64 comes out of the direct-map, not kvm like i386, 314 * so the pages must be tracked for a crashdump to include this data. 315 * This includes the vm_page_array and the early UMA bootstrap pages. 316 */ 317 for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE) 318 dump_add_page(pa); 319 #endif 320 phys_avail[biggestone + 1] = new_end; 321 322 /* 323 * Clear all of the page structures 324 */ 325 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 326 vm_page_array_size = page_range; 327 328 /* 329 * Construct the free queue(s) in descending order (by physical 330 * address) so that the first 16MB of physical memory is allocated 331 * last rather than first. On large-memory machines, this avoids 332 * the exhaustion of low physical memory before isa_dma_init has run. 333 */ 334 cnt.v_page_count = 0; 335 cnt.v_free_count = 0; 336 list = getenv("vm.blacklist"); 337 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 338 pa = phys_avail[i]; 339 last_pa = phys_avail[i + 1]; 340 while (pa < last_pa && npages-- > 0) { 341 if (list != NULL && 342 vm_page_blacklist_lookup(list, pa)) 343 printf("Skipping page with pa 0x%jx\n", 344 (uintmax_t)pa); 345 else 346 vm_pageq_add_new_page(pa); 347 pa += PAGE_SIZE; 348 } 349 } 350 freeenv(list); 351 return (vaddr); 352 } 353 354 void 355 vm_page_flag_set(vm_page_t m, unsigned short bits) 356 { 357 358 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 359 m->flags |= bits; 360 } 361 362 void 363 vm_page_flag_clear(vm_page_t m, unsigned short bits) 364 { 365 366 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 367 m->flags &= ~bits; 368 } 369 370 void 371 vm_page_busy(vm_page_t m) 372 { 373 374 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 375 KASSERT((m->oflags & VPO_BUSY) == 0, 376 ("vm_page_busy: page already busy!!!")); 377 m->oflags |= VPO_BUSY; 378 } 379 380 /* 381 * vm_page_flash: 382 * 383 * wakeup anyone waiting for the page. 384 */ 385 void 386 vm_page_flash(vm_page_t m) 387 { 388 389 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 390 if (m->oflags & VPO_WANTED) { 391 m->oflags &= ~VPO_WANTED; 392 wakeup(m); 393 } 394 } 395 396 /* 397 * vm_page_wakeup: 398 * 399 * clear the VPO_BUSY flag and wakeup anyone waiting for the 400 * page. 401 * 402 */ 403 void 404 vm_page_wakeup(vm_page_t m) 405 { 406 407 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 408 KASSERT(m->oflags & VPO_BUSY, ("vm_page_wakeup: page not busy!!!")); 409 m->oflags &= ~VPO_BUSY; 410 vm_page_flash(m); 411 } 412 413 void 414 vm_page_io_start(vm_page_t m) 415 { 416 417 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 418 m->busy++; 419 } 420 421 void 422 vm_page_io_finish(vm_page_t m) 423 { 424 425 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 426 m->busy--; 427 if (m->busy == 0) 428 vm_page_flash(m); 429 } 430 431 /* 432 * Keep page from being freed by the page daemon 433 * much of the same effect as wiring, except much lower 434 * overhead and should be used only for *very* temporary 435 * holding ("wiring"). 436 */ 437 void 438 vm_page_hold(vm_page_t mem) 439 { 440 441 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 442 mem->hold_count++; 443 } 444 445 void 446 vm_page_unhold(vm_page_t mem) 447 { 448 449 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 450 --mem->hold_count; 451 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 452 if (mem->hold_count == 0 && VM_PAGE_INQUEUE2(mem, PQ_HOLD)) 453 vm_page_free_toq(mem); 454 } 455 456 /* 457 * vm_page_free: 458 * 459 * Free a page 460 * 461 * The clearing of PG_ZERO is a temporary safety until the code can be 462 * reviewed to determine that PG_ZERO is being properly cleared on 463 * write faults or maps. PG_ZERO was previously cleared in 464 * vm_page_alloc(). 465 */ 466 void 467 vm_page_free(vm_page_t m) 468 { 469 vm_page_flag_clear(m, PG_ZERO); 470 vm_page_free_toq(m); 471 vm_page_zero_idle_wakeup(); 472 } 473 474 /* 475 * vm_page_free_zero: 476 * 477 * Free a page to the zerod-pages queue 478 */ 479 void 480 vm_page_free_zero(vm_page_t m) 481 { 482 vm_page_flag_set(m, PG_ZERO); 483 vm_page_free_toq(m); 484 } 485 486 /* 487 * vm_page_sleep: 488 * 489 * Sleep and release the page queues lock. 490 * 491 * The object containing the given page must be locked. 492 */ 493 void 494 vm_page_sleep(vm_page_t m, const char *msg) 495 { 496 497 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 498 if (!mtx_owned(&vm_page_queue_mtx)) 499 vm_page_lock_queues(); 500 vm_page_flag_set(m, PG_REFERENCED); 501 vm_page_unlock_queues(); 502 503 /* 504 * It's possible that while we sleep, the page will get 505 * unbusied and freed. If we are holding the object 506 * lock, we will assume we hold a reference to the object 507 * such that even if m->object changes, we can re-lock 508 * it. 509 */ 510 m->oflags |= VPO_WANTED; 511 msleep(m, VM_OBJECT_MTX(m->object), PVM, msg, 0); 512 } 513 514 /* 515 * vm_page_dirty: 516 * 517 * make page all dirty 518 */ 519 void 520 vm_page_dirty(vm_page_t m) 521 { 522 KASSERT(VM_PAGE_GETKNOWNQUEUE1(m) != PQ_CACHE, 523 ("vm_page_dirty: page in cache!")); 524 KASSERT(VM_PAGE_GETKNOWNQUEUE1(m) != PQ_FREE, 525 ("vm_page_dirty: page is free!")); 526 m->dirty = VM_PAGE_BITS_ALL; 527 } 528 529 /* 530 * vm_page_splay: 531 * 532 * Implements Sleator and Tarjan's top-down splay algorithm. Returns 533 * the vm_page containing the given pindex. If, however, that 534 * pindex is not found in the vm_object, returns a vm_page that is 535 * adjacent to the pindex, coming before or after it. 536 */ 537 vm_page_t 538 vm_page_splay(vm_pindex_t pindex, vm_page_t root) 539 { 540 struct vm_page dummy; 541 vm_page_t lefttreemax, righttreemin, y; 542 543 if (root == NULL) 544 return (root); 545 lefttreemax = righttreemin = &dummy; 546 for (;; root = y) { 547 if (pindex < root->pindex) { 548 if ((y = root->left) == NULL) 549 break; 550 if (pindex < y->pindex) { 551 /* Rotate right. */ 552 root->left = y->right; 553 y->right = root; 554 root = y; 555 if ((y = root->left) == NULL) 556 break; 557 } 558 /* Link into the new root's right tree. */ 559 righttreemin->left = root; 560 righttreemin = root; 561 } else if (pindex > root->pindex) { 562 if ((y = root->right) == NULL) 563 break; 564 if (pindex > y->pindex) { 565 /* Rotate left. */ 566 root->right = y->left; 567 y->left = root; 568 root = y; 569 if ((y = root->right) == NULL) 570 break; 571 } 572 /* Link into the new root's left tree. */ 573 lefttreemax->right = root; 574 lefttreemax = root; 575 } else 576 break; 577 } 578 /* Assemble the new root. */ 579 lefttreemax->right = root->left; 580 righttreemin->left = root->right; 581 root->left = dummy.right; 582 root->right = dummy.left; 583 return (root); 584 } 585 586 /* 587 * vm_page_insert: [ internal use only ] 588 * 589 * Inserts the given mem entry into the object and object list. 590 * 591 * The pagetables are not updated but will presumably fault the page 592 * in if necessary, or if a kernel page the caller will at some point 593 * enter the page into the kernel's pmap. We are not allowed to block 594 * here so we *can't* do this anyway. 595 * 596 * The object and page must be locked. 597 * This routine may not block. 598 */ 599 void 600 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 601 { 602 vm_page_t root; 603 604 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 605 if (m->object != NULL) 606 panic("vm_page_insert: page already inserted"); 607 608 /* 609 * Record the object/offset pair in this page 610 */ 611 m->object = object; 612 m->pindex = pindex; 613 614 /* 615 * Now link into the object's ordered list of backed pages. 616 */ 617 root = object->root; 618 if (root == NULL) { 619 m->left = NULL; 620 m->right = NULL; 621 TAILQ_INSERT_TAIL(&object->memq, m, listq); 622 } else { 623 root = vm_page_splay(pindex, root); 624 if (pindex < root->pindex) { 625 m->left = root->left; 626 m->right = root; 627 root->left = NULL; 628 TAILQ_INSERT_BEFORE(root, m, listq); 629 } else if (pindex == root->pindex) 630 panic("vm_page_insert: offset already allocated"); 631 else { 632 m->right = root->right; 633 m->left = root; 634 root->right = NULL; 635 TAILQ_INSERT_AFTER(&object->memq, root, m, listq); 636 } 637 } 638 object->root = m; 639 object->generation++; 640 641 /* 642 * show that the object has one more resident page. 643 */ 644 object->resident_page_count++; 645 /* 646 * Hold the vnode until the last page is released. 647 */ 648 if (object->resident_page_count == 1 && object->type == OBJT_VNODE) 649 vhold((struct vnode *)object->handle); 650 651 /* 652 * Since we are inserting a new and possibly dirty page, 653 * update the object's OBJ_MIGHTBEDIRTY flag. 654 */ 655 if (m->flags & PG_WRITEABLE) 656 vm_object_set_writeable_dirty(object); 657 } 658 659 /* 660 * vm_page_remove: 661 * NOTE: used by device pager as well -wfj 662 * 663 * Removes the given mem entry from the object/offset-page 664 * table and the object page list, but do not invalidate/terminate 665 * the backing store. 666 * 667 * The object and page must be locked. 668 * The underlying pmap entry (if any) is NOT removed here. 669 * This routine may not block. 670 */ 671 void 672 vm_page_remove(vm_page_t m) 673 { 674 vm_object_t object; 675 vm_page_t root; 676 677 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 678 if ((object = m->object) == NULL) 679 return; 680 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 681 if (m->oflags & VPO_BUSY) { 682 m->oflags &= ~VPO_BUSY; 683 vm_page_flash(m); 684 } 685 686 /* 687 * Now remove from the object's list of backed pages. 688 */ 689 if (m != object->root) 690 vm_page_splay(m->pindex, object->root); 691 if (m->left == NULL) 692 root = m->right; 693 else { 694 root = vm_page_splay(m->pindex, m->left); 695 root->right = m->right; 696 } 697 object->root = root; 698 TAILQ_REMOVE(&object->memq, m, listq); 699 700 /* 701 * And show that the object has one fewer resident page. 702 */ 703 object->resident_page_count--; 704 object->generation++; 705 /* 706 * The vnode may now be recycled. 707 */ 708 if (object->resident_page_count == 0 && object->type == OBJT_VNODE) 709 vdrop((struct vnode *)object->handle); 710 711 m->object = NULL; 712 } 713 714 /* 715 * vm_page_lookup: 716 * 717 * Returns the page associated with the object/offset 718 * pair specified; if none is found, NULL is returned. 719 * 720 * The object must be locked. 721 * This routine may not block. 722 * This is a critical path routine 723 */ 724 vm_page_t 725 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 726 { 727 vm_page_t m; 728 729 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 730 if ((m = object->root) != NULL && m->pindex != pindex) { 731 m = vm_page_splay(pindex, m); 732 if ((object->root = m)->pindex != pindex) 733 m = NULL; 734 } 735 return (m); 736 } 737 738 /* 739 * vm_page_rename: 740 * 741 * Move the given memory entry from its 742 * current object to the specified target object/offset. 743 * 744 * The object must be locked. 745 * This routine may not block. 746 * 747 * Note: swap associated with the page must be invalidated by the move. We 748 * have to do this for several reasons: (1) we aren't freeing the 749 * page, (2) we are dirtying the page, (3) the VM system is probably 750 * moving the page from object A to B, and will then later move 751 * the backing store from A to B and we can't have a conflict. 752 * 753 * Note: we *always* dirty the page. It is necessary both for the 754 * fact that we moved it, and because we may be invalidating 755 * swap. If the page is on the cache, we have to deactivate it 756 * or vm_page_dirty() will panic. Dirty pages are not allowed 757 * on the cache. 758 */ 759 void 760 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 761 { 762 763 vm_page_remove(m); 764 vm_page_insert(m, new_object, new_pindex); 765 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 766 vm_page_deactivate(m); 767 vm_page_dirty(m); 768 } 769 770 /* 771 * vm_page_select_cache: 772 * 773 * Move a page of the given color from the cache queue to the free 774 * queue. As pages might be found, but are not applicable, they are 775 * deactivated. 776 * 777 * This routine may not block. 778 */ 779 vm_page_t 780 vm_page_select_cache(int color) 781 { 782 vm_object_t object; 783 vm_page_t m; 784 boolean_t was_trylocked; 785 786 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 787 while ((m = vm_pageq_find(PQ_CACHE, color, FALSE)) != NULL) { 788 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 789 KASSERT(!pmap_page_is_mapped(m), 790 ("Found mapped cache page %p", m)); 791 KASSERT((m->flags & PG_UNMANAGED) == 0, 792 ("Found unmanaged cache page %p", m)); 793 KASSERT(m->wire_count == 0, ("Found wired cache page %p", m)); 794 if (m->hold_count == 0 && (object = m->object, 795 (was_trylocked = VM_OBJECT_TRYLOCK(object)) || 796 VM_OBJECT_LOCKED(object))) { 797 KASSERT((m->oflags & VPO_BUSY) == 0 && m->busy == 0, 798 ("Found busy cache page %p", m)); 799 vm_page_free(m); 800 if (was_trylocked) 801 VM_OBJECT_UNLOCK(object); 802 break; 803 } 804 vm_page_deactivate(m); 805 } 806 return (m); 807 } 808 809 /* 810 * vm_page_alloc: 811 * 812 * Allocate and return a memory cell associated 813 * with this VM object/offset pair. 814 * 815 * page_req classes: 816 * VM_ALLOC_NORMAL normal process request 817 * VM_ALLOC_SYSTEM system *really* needs a page 818 * VM_ALLOC_INTERRUPT interrupt time request 819 * VM_ALLOC_ZERO zero page 820 * 821 * This routine may not block. 822 * 823 * Additional special handling is required when called from an 824 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 825 * the page cache in this case. 826 */ 827 vm_page_t 828 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) 829 { 830 vm_page_t m = NULL; 831 int color, flags, page_req; 832 833 page_req = req & VM_ALLOC_CLASS_MASK; 834 KASSERT(curthread->td_intr_nesting_level == 0 || 835 page_req == VM_ALLOC_INTERRUPT, 836 ("vm_page_alloc(NORMAL|SYSTEM) in interrupt context")); 837 838 if ((req & VM_ALLOC_NOOBJ) == 0) { 839 KASSERT(object != NULL, 840 ("vm_page_alloc: NULL object.")); 841 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 842 color = (pindex + object->pg_color) & PQ_COLORMASK; 843 } else 844 color = pindex & PQ_COLORMASK; 845 846 /* 847 * The pager is allowed to eat deeper into the free page list. 848 */ 849 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 850 page_req = VM_ALLOC_SYSTEM; 851 }; 852 853 loop: 854 mtx_lock_spin(&vm_page_queue_free_mtx); 855 if (cnt.v_free_count > cnt.v_free_reserved || 856 (page_req == VM_ALLOC_SYSTEM && 857 cnt.v_cache_count == 0 && 858 cnt.v_free_count > cnt.v_interrupt_free_min) || 859 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0)) { 860 /* 861 * Allocate from the free queue if the number of free pages 862 * exceeds the minimum for the request class. 863 */ 864 m = vm_pageq_find(PQ_FREE, color, (req & VM_ALLOC_ZERO) != 0); 865 } else if (page_req != VM_ALLOC_INTERRUPT) { 866 mtx_unlock_spin(&vm_page_queue_free_mtx); 867 /* 868 * Allocatable from cache (non-interrupt only). On success, 869 * we must free the page and try again, thus ensuring that 870 * cnt.v_*_free_min counters are replenished. 871 */ 872 vm_page_lock_queues(); 873 if ((m = vm_page_select_cache(color)) == NULL) { 874 KASSERT(cnt.v_cache_count == 0, 875 ("vm_page_alloc: cache queue is missing %d pages", 876 cnt.v_cache_count)); 877 vm_page_unlock_queues(); 878 atomic_add_int(&vm_pageout_deficit, 1); 879 pagedaemon_wakeup(); 880 881 if (page_req != VM_ALLOC_SYSTEM) 882 return (NULL); 883 884 mtx_lock_spin(&vm_page_queue_free_mtx); 885 if (cnt.v_free_count <= cnt.v_interrupt_free_min) { 886 mtx_unlock_spin(&vm_page_queue_free_mtx); 887 return (NULL); 888 } 889 m = vm_pageq_find(PQ_FREE, color, (req & VM_ALLOC_ZERO) != 0); 890 } else { 891 vm_page_unlock_queues(); 892 goto loop; 893 } 894 } else { 895 /* 896 * Not allocatable from cache from interrupt, give up. 897 */ 898 mtx_unlock_spin(&vm_page_queue_free_mtx); 899 atomic_add_int(&vm_pageout_deficit, 1); 900 pagedaemon_wakeup(); 901 return (NULL); 902 } 903 904 /* 905 * At this point we had better have found a good page. 906 */ 907 908 KASSERT( 909 m != NULL, 910 ("vm_page_alloc(): missing page on free queue") 911 ); 912 913 /* 914 * Remove from free queue 915 */ 916 vm_pageq_remove_nowakeup(m); 917 918 /* 919 * Initialize structure. Only the PG_ZERO flag is inherited. 920 */ 921 flags = 0; 922 if (m->flags & PG_ZERO) { 923 vm_page_zero_count--; 924 if (req & VM_ALLOC_ZERO) 925 flags = PG_ZERO; 926 } 927 m->flags = flags; 928 if (req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ)) 929 m->oflags = 0; 930 else 931 m->oflags = VPO_BUSY; 932 if (req & VM_ALLOC_WIRED) { 933 atomic_add_int(&cnt.v_wire_count, 1); 934 m->wire_count = 1; 935 } else 936 m->wire_count = 0; 937 m->hold_count = 0; 938 m->act_count = 0; 939 m->busy = 0; 940 m->valid = 0; 941 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 942 mtx_unlock_spin(&vm_page_queue_free_mtx); 943 944 if ((req & VM_ALLOC_NOOBJ) == 0) 945 vm_page_insert(m, object, pindex); 946 else 947 m->pindex = pindex; 948 949 /* 950 * Don't wakeup too often - wakeup the pageout daemon when 951 * we would be nearly out of memory. 952 */ 953 if (vm_paging_needed()) 954 pagedaemon_wakeup(); 955 956 return (m); 957 } 958 959 /* 960 * vm_wait: (also see VM_WAIT macro) 961 * 962 * Block until free pages are available for allocation 963 * - Called in various places before memory allocations. 964 */ 965 void 966 vm_wait(void) 967 { 968 969 vm_page_lock_queues(); 970 if (curproc == pageproc) { 971 vm_pageout_pages_needed = 1; 972 msleep(&vm_pageout_pages_needed, &vm_page_queue_mtx, 973 PDROP | PSWP, "VMWait", 0); 974 } else { 975 if (!vm_pages_needed) { 976 vm_pages_needed = 1; 977 wakeup(&vm_pages_needed); 978 } 979 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PVM, 980 "vmwait", 0); 981 } 982 } 983 984 /* 985 * vm_waitpfault: (also see VM_WAITPFAULT macro) 986 * 987 * Block until free pages are available for allocation 988 * - Called only in vm_fault so that processes page faulting 989 * can be easily tracked. 990 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 991 * processes will be able to grab memory first. Do not change 992 * this balance without careful testing first. 993 */ 994 void 995 vm_waitpfault(void) 996 { 997 998 vm_page_lock_queues(); 999 if (!vm_pages_needed) { 1000 vm_pages_needed = 1; 1001 wakeup(&vm_pages_needed); 1002 } 1003 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PUSER, 1004 "pfault", 0); 1005 } 1006 1007 /* 1008 * vm_page_activate: 1009 * 1010 * Put the specified page on the active list (if appropriate). 1011 * Ensure that act_count is at least ACT_INIT but do not otherwise 1012 * mess with it. 1013 * 1014 * The page queues must be locked. 1015 * This routine may not block. 1016 */ 1017 void 1018 vm_page_activate(vm_page_t m) 1019 { 1020 1021 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1022 if (VM_PAGE_GETKNOWNQUEUE2(m) != PQ_ACTIVE) { 1023 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1024 cnt.v_reactivated++; 1025 vm_pageq_remove(m); 1026 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1027 if (m->act_count < ACT_INIT) 1028 m->act_count = ACT_INIT; 1029 vm_pageq_enqueue(PQ_ACTIVE, m); 1030 } 1031 } else { 1032 if (m->act_count < ACT_INIT) 1033 m->act_count = ACT_INIT; 1034 } 1035 } 1036 1037 /* 1038 * vm_page_free_wakeup: 1039 * 1040 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 1041 * routine is called when a page has been added to the cache or free 1042 * queues. 1043 * 1044 * The page queues must be locked. 1045 * This routine may not block. 1046 */ 1047 static inline void 1048 vm_page_free_wakeup(void) 1049 { 1050 1051 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1052 /* 1053 * if pageout daemon needs pages, then tell it that there are 1054 * some free. 1055 */ 1056 if (vm_pageout_pages_needed && 1057 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 1058 wakeup(&vm_pageout_pages_needed); 1059 vm_pageout_pages_needed = 0; 1060 } 1061 /* 1062 * wakeup processes that are waiting on memory if we hit a 1063 * high water mark. And wakeup scheduler process if we have 1064 * lots of memory. this process will swapin processes. 1065 */ 1066 if (vm_pages_needed && !vm_page_count_min()) { 1067 vm_pages_needed = 0; 1068 wakeup(&cnt.v_free_count); 1069 } 1070 } 1071 1072 /* 1073 * vm_page_free_toq: 1074 * 1075 * Returns the given page to the PQ_FREE list, 1076 * disassociating it with any VM object. 1077 * 1078 * Object and page must be locked prior to entry. 1079 * This routine may not block. 1080 */ 1081 1082 void 1083 vm_page_free_toq(vm_page_t m) 1084 { 1085 struct vpgqueues *pq; 1086 1087 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1088 KASSERT(!pmap_page_is_mapped(m), 1089 ("vm_page_free_toq: freeing mapped page %p", m)); 1090 cnt.v_tfree++; 1091 1092 if (m->busy || VM_PAGE_INQUEUE1(m, PQ_FREE)) { 1093 printf( 1094 "vm_page_free: pindex(%lu), busy(%d), VPO_BUSY(%d), hold(%d)\n", 1095 (u_long)m->pindex, m->busy, (m->oflags & VPO_BUSY) ? 1 : 0, 1096 m->hold_count); 1097 if (VM_PAGE_INQUEUE1(m, PQ_FREE)) 1098 panic("vm_page_free: freeing free page"); 1099 else 1100 panic("vm_page_free: freeing busy page"); 1101 } 1102 1103 /* 1104 * unqueue, then remove page. Note that we cannot destroy 1105 * the page here because we do not want to call the pager's 1106 * callback routine until after we've put the page on the 1107 * appropriate free queue. 1108 */ 1109 vm_pageq_remove_nowakeup(m); 1110 vm_page_remove(m); 1111 1112 /* 1113 * If fictitious remove object association and 1114 * return, otherwise delay object association removal. 1115 */ 1116 if ((m->flags & PG_FICTITIOUS) != 0) { 1117 return; 1118 } 1119 1120 m->valid = 0; 1121 vm_page_undirty(m); 1122 1123 if (m->wire_count != 0) { 1124 if (m->wire_count > 1) { 1125 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1126 m->wire_count, (long)m->pindex); 1127 } 1128 panic("vm_page_free: freeing wired page"); 1129 } 1130 if (m->hold_count != 0) { 1131 m->flags &= ~PG_ZERO; 1132 VM_PAGE_SETQUEUE2(m, PQ_HOLD); 1133 } else 1134 VM_PAGE_SETQUEUE1(m, PQ_FREE); 1135 pq = &vm_page_queues[VM_PAGE_GETQUEUE(m)]; 1136 mtx_lock_spin(&vm_page_queue_free_mtx); 1137 pq->lcnt++; 1138 ++(*pq->cnt); 1139 1140 /* 1141 * Put zero'd pages on the end ( where we look for zero'd pages 1142 * first ) and non-zerod pages at the head. 1143 */ 1144 if (m->flags & PG_ZERO) { 1145 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1146 ++vm_page_zero_count; 1147 } else { 1148 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1149 } 1150 mtx_unlock_spin(&vm_page_queue_free_mtx); 1151 vm_page_free_wakeup(); 1152 } 1153 1154 /* 1155 * vm_page_unmanage: 1156 * 1157 * Prevent PV management from being done on the page. The page is 1158 * removed from the paging queues as if it were wired, and as a 1159 * consequence of no longer being managed the pageout daemon will not 1160 * touch it (since there is no way to locate the pte mappings for the 1161 * page). madvise() calls that mess with the pmap will also no longer 1162 * operate on the page. 1163 * 1164 * Beyond that the page is still reasonably 'normal'. Freeing the page 1165 * will clear the flag. 1166 * 1167 * This routine is used by OBJT_PHYS objects - objects using unswappable 1168 * physical memory as backing store rather then swap-backed memory and 1169 * will eventually be extended to support 4MB unmanaged physical 1170 * mappings. 1171 */ 1172 void 1173 vm_page_unmanage(vm_page_t m) 1174 { 1175 1176 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1177 if ((m->flags & PG_UNMANAGED) == 0) { 1178 if (m->wire_count == 0) 1179 vm_pageq_remove(m); 1180 } 1181 vm_page_flag_set(m, PG_UNMANAGED); 1182 } 1183 1184 /* 1185 * vm_page_wire: 1186 * 1187 * Mark this page as wired down by yet 1188 * another map, removing it from paging queues 1189 * as necessary. 1190 * 1191 * The page queues must be locked. 1192 * This routine may not block. 1193 */ 1194 void 1195 vm_page_wire(vm_page_t m) 1196 { 1197 1198 /* 1199 * Only bump the wire statistics if the page is not already wired, 1200 * and only unqueue the page if it is on some queue (if it is unmanaged 1201 * it is already off the queues). 1202 */ 1203 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1204 if (m->flags & PG_FICTITIOUS) 1205 return; 1206 if (m->wire_count == 0) { 1207 if ((m->flags & PG_UNMANAGED) == 0) 1208 vm_pageq_remove(m); 1209 atomic_add_int(&cnt.v_wire_count, 1); 1210 } 1211 m->wire_count++; 1212 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1213 } 1214 1215 /* 1216 * vm_page_unwire: 1217 * 1218 * Release one wiring of this page, potentially 1219 * enabling it to be paged again. 1220 * 1221 * Many pages placed on the inactive queue should actually go 1222 * into the cache, but it is difficult to figure out which. What 1223 * we do instead, if the inactive target is well met, is to put 1224 * clean pages at the head of the inactive queue instead of the tail. 1225 * This will cause them to be moved to the cache more quickly and 1226 * if not actively re-referenced, freed more quickly. If we just 1227 * stick these pages at the end of the inactive queue, heavy filesystem 1228 * meta-data accesses can cause an unnecessary paging load on memory bound 1229 * processes. This optimization causes one-time-use metadata to be 1230 * reused more quickly. 1231 * 1232 * BUT, if we are in a low-memory situation we have no choice but to 1233 * put clean pages on the cache queue. 1234 * 1235 * A number of routines use vm_page_unwire() to guarantee that the page 1236 * will go into either the inactive or active queues, and will NEVER 1237 * be placed in the cache - for example, just after dirtying a page. 1238 * dirty pages in the cache are not allowed. 1239 * 1240 * The page queues must be locked. 1241 * This routine may not block. 1242 */ 1243 void 1244 vm_page_unwire(vm_page_t m, int activate) 1245 { 1246 1247 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1248 if (m->flags & PG_FICTITIOUS) 1249 return; 1250 if (m->wire_count > 0) { 1251 m->wire_count--; 1252 if (m->wire_count == 0) { 1253 atomic_subtract_int(&cnt.v_wire_count, 1); 1254 if (m->flags & PG_UNMANAGED) { 1255 ; 1256 } else if (activate) 1257 vm_pageq_enqueue(PQ_ACTIVE, m); 1258 else { 1259 vm_page_flag_clear(m, PG_WINATCFLS); 1260 vm_pageq_enqueue(PQ_INACTIVE, m); 1261 } 1262 } 1263 } else { 1264 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1265 } 1266 } 1267 1268 1269 /* 1270 * Move the specified page to the inactive queue. If the page has 1271 * any associated swap, the swap is deallocated. 1272 * 1273 * Normally athead is 0 resulting in LRU operation. athead is set 1274 * to 1 if we want this page to be 'as if it were placed in the cache', 1275 * except without unmapping it from the process address space. 1276 * 1277 * This routine may not block. 1278 */ 1279 static inline void 1280 _vm_page_deactivate(vm_page_t m, int athead) 1281 { 1282 1283 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1284 1285 /* 1286 * Ignore if already inactive. 1287 */ 1288 if (VM_PAGE_INQUEUE2(m, PQ_INACTIVE)) 1289 return; 1290 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1291 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1292 cnt.v_reactivated++; 1293 vm_page_flag_clear(m, PG_WINATCFLS); 1294 vm_pageq_remove(m); 1295 if (athead) 1296 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1297 else 1298 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1299 VM_PAGE_SETQUEUE2(m, PQ_INACTIVE); 1300 vm_page_queues[PQ_INACTIVE].lcnt++; 1301 cnt.v_inactive_count++; 1302 } 1303 } 1304 1305 void 1306 vm_page_deactivate(vm_page_t m) 1307 { 1308 _vm_page_deactivate(m, 0); 1309 } 1310 1311 /* 1312 * vm_page_try_to_cache: 1313 * 1314 * Returns 0 on failure, 1 on success 1315 */ 1316 int 1317 vm_page_try_to_cache(vm_page_t m) 1318 { 1319 1320 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1321 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1322 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1323 (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) { 1324 return (0); 1325 } 1326 pmap_remove_all(m); 1327 if (m->dirty) 1328 return (0); 1329 vm_page_cache(m); 1330 return (1); 1331 } 1332 1333 /* 1334 * vm_page_try_to_free() 1335 * 1336 * Attempt to free the page. If we cannot free it, we do nothing. 1337 * 1 is returned on success, 0 on failure. 1338 */ 1339 int 1340 vm_page_try_to_free(vm_page_t m) 1341 { 1342 1343 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1344 if (m->object != NULL) 1345 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1346 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1347 (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) { 1348 return (0); 1349 } 1350 pmap_remove_all(m); 1351 if (m->dirty) 1352 return (0); 1353 vm_page_free(m); 1354 return (1); 1355 } 1356 1357 /* 1358 * vm_page_cache 1359 * 1360 * Put the specified page onto the page cache queue (if appropriate). 1361 * 1362 * This routine may not block. 1363 */ 1364 void 1365 vm_page_cache(vm_page_t m) 1366 { 1367 1368 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1369 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1370 if ((m->flags & PG_UNMANAGED) || (m->oflags & VPO_BUSY) || m->busy || 1371 m->hold_count || m->wire_count) { 1372 printf("vm_page_cache: attempting to cache busy page\n"); 1373 return; 1374 } 1375 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1376 return; 1377 1378 /* 1379 * Remove all pmaps and indicate that the page is not 1380 * writeable or mapped. 1381 */ 1382 pmap_remove_all(m); 1383 if (m->dirty != 0) { 1384 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1385 (long)m->pindex); 1386 } 1387 vm_pageq_remove_nowakeup(m); 1388 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1389 vm_page_free_wakeup(); 1390 } 1391 1392 /* 1393 * vm_page_dontneed 1394 * 1395 * Cache, deactivate, or do nothing as appropriate. This routine 1396 * is typically used by madvise() MADV_DONTNEED. 1397 * 1398 * Generally speaking we want to move the page into the cache so 1399 * it gets reused quickly. However, this can result in a silly syndrome 1400 * due to the page recycling too quickly. Small objects will not be 1401 * fully cached. On the otherhand, if we move the page to the inactive 1402 * queue we wind up with a problem whereby very large objects 1403 * unnecessarily blow away our inactive and cache queues. 1404 * 1405 * The solution is to move the pages based on a fixed weighting. We 1406 * either leave them alone, deactivate them, or move them to the cache, 1407 * where moving them to the cache has the highest weighting. 1408 * By forcing some pages into other queues we eventually force the 1409 * system to balance the queues, potentially recovering other unrelated 1410 * space from active. The idea is to not force this to happen too 1411 * often. 1412 */ 1413 void 1414 vm_page_dontneed(vm_page_t m) 1415 { 1416 static int dnweight; 1417 int dnw; 1418 int head; 1419 1420 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1421 dnw = ++dnweight; 1422 1423 /* 1424 * occassionally leave the page alone 1425 */ 1426 if ((dnw & 0x01F0) == 0 || 1427 VM_PAGE_INQUEUE2(m, PQ_INACTIVE) || 1428 VM_PAGE_INQUEUE1(m, PQ_CACHE) 1429 ) { 1430 if (m->act_count >= ACT_INIT) 1431 --m->act_count; 1432 return; 1433 } 1434 1435 if (m->dirty == 0 && pmap_is_modified(m)) 1436 vm_page_dirty(m); 1437 1438 if (m->dirty || (dnw & 0x0070) == 0) { 1439 /* 1440 * Deactivate the page 3 times out of 32. 1441 */ 1442 head = 0; 1443 } else { 1444 /* 1445 * Cache the page 28 times out of every 32. Note that 1446 * the page is deactivated instead of cached, but placed 1447 * at the head of the queue instead of the tail. 1448 */ 1449 head = 1; 1450 } 1451 _vm_page_deactivate(m, head); 1452 } 1453 1454 /* 1455 * Grab a page, waiting until we are waken up due to the page 1456 * changing state. We keep on waiting, if the page continues 1457 * to be in the object. If the page doesn't exist, first allocate it 1458 * and then conditionally zero it. 1459 * 1460 * This routine may block. 1461 */ 1462 vm_page_t 1463 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1464 { 1465 vm_page_t m; 1466 1467 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1468 retrylookup: 1469 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1470 if (vm_page_sleep_if_busy(m, TRUE, "pgrbwt")) { 1471 if ((allocflags & VM_ALLOC_RETRY) == 0) 1472 return (NULL); 1473 goto retrylookup; 1474 } else { 1475 if ((allocflags & VM_ALLOC_WIRED) != 0) { 1476 vm_page_lock_queues(); 1477 vm_page_wire(m); 1478 vm_page_unlock_queues(); 1479 } 1480 if ((allocflags & VM_ALLOC_NOBUSY) == 0) 1481 vm_page_busy(m); 1482 return (m); 1483 } 1484 } 1485 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1486 if (m == NULL) { 1487 VM_OBJECT_UNLOCK(object); 1488 VM_WAIT; 1489 VM_OBJECT_LOCK(object); 1490 if ((allocflags & VM_ALLOC_RETRY) == 0) 1491 return (NULL); 1492 goto retrylookup; 1493 } 1494 if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0) 1495 pmap_zero_page(m); 1496 return (m); 1497 } 1498 1499 /* 1500 * Mapping function for valid bits or for dirty bits in 1501 * a page. May not block. 1502 * 1503 * Inputs are required to range within a page. 1504 */ 1505 inline int 1506 vm_page_bits(int base, int size) 1507 { 1508 int first_bit; 1509 int last_bit; 1510 1511 KASSERT( 1512 base + size <= PAGE_SIZE, 1513 ("vm_page_bits: illegal base/size %d/%d", base, size) 1514 ); 1515 1516 if (size == 0) /* handle degenerate case */ 1517 return (0); 1518 1519 first_bit = base >> DEV_BSHIFT; 1520 last_bit = (base + size - 1) >> DEV_BSHIFT; 1521 1522 return ((2 << last_bit) - (1 << first_bit)); 1523 } 1524 1525 /* 1526 * vm_page_set_validclean: 1527 * 1528 * Sets portions of a page valid and clean. The arguments are expected 1529 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1530 * of any partial chunks touched by the range. The invalid portion of 1531 * such chunks will be zero'd. 1532 * 1533 * This routine may not block. 1534 * 1535 * (base + size) must be less then or equal to PAGE_SIZE. 1536 */ 1537 void 1538 vm_page_set_validclean(vm_page_t m, int base, int size) 1539 { 1540 int pagebits; 1541 int frag; 1542 int endoff; 1543 1544 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1545 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1546 if (size == 0) /* handle degenerate case */ 1547 return; 1548 1549 /* 1550 * If the base is not DEV_BSIZE aligned and the valid 1551 * bit is clear, we have to zero out a portion of the 1552 * first block. 1553 */ 1554 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1555 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1556 pmap_zero_page_area(m, frag, base - frag); 1557 1558 /* 1559 * If the ending offset is not DEV_BSIZE aligned and the 1560 * valid bit is clear, we have to zero out a portion of 1561 * the last block. 1562 */ 1563 endoff = base + size; 1564 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1565 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1566 pmap_zero_page_area(m, endoff, 1567 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1568 1569 /* 1570 * Set valid, clear dirty bits. If validating the entire 1571 * page we can safely clear the pmap modify bit. We also 1572 * use this opportunity to clear the VPO_NOSYNC flag. If a process 1573 * takes a write fault on a MAP_NOSYNC memory area the flag will 1574 * be set again. 1575 * 1576 * We set valid bits inclusive of any overlap, but we can only 1577 * clear dirty bits for DEV_BSIZE chunks that are fully within 1578 * the range. 1579 */ 1580 pagebits = vm_page_bits(base, size); 1581 m->valid |= pagebits; 1582 #if 0 /* NOT YET */ 1583 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1584 frag = DEV_BSIZE - frag; 1585 base += frag; 1586 size -= frag; 1587 if (size < 0) 1588 size = 0; 1589 } 1590 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1591 #endif 1592 m->dirty &= ~pagebits; 1593 if (base == 0 && size == PAGE_SIZE) { 1594 pmap_clear_modify(m); 1595 m->oflags &= ~VPO_NOSYNC; 1596 } 1597 } 1598 1599 void 1600 vm_page_clear_dirty(vm_page_t m, int base, int size) 1601 { 1602 1603 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1604 m->dirty &= ~vm_page_bits(base, size); 1605 } 1606 1607 /* 1608 * vm_page_set_invalid: 1609 * 1610 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1611 * valid and dirty bits for the effected areas are cleared. 1612 * 1613 * May not block. 1614 */ 1615 void 1616 vm_page_set_invalid(vm_page_t m, int base, int size) 1617 { 1618 int bits; 1619 1620 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1621 bits = vm_page_bits(base, size); 1622 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1623 if (m->valid == VM_PAGE_BITS_ALL && bits != 0) 1624 pmap_remove_all(m); 1625 m->valid &= ~bits; 1626 m->dirty &= ~bits; 1627 m->object->generation++; 1628 } 1629 1630 /* 1631 * vm_page_zero_invalid() 1632 * 1633 * The kernel assumes that the invalid portions of a page contain 1634 * garbage, but such pages can be mapped into memory by user code. 1635 * When this occurs, we must zero out the non-valid portions of the 1636 * page so user code sees what it expects. 1637 * 1638 * Pages are most often semi-valid when the end of a file is mapped 1639 * into memory and the file's size is not page aligned. 1640 */ 1641 void 1642 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1643 { 1644 int b; 1645 int i; 1646 1647 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1648 /* 1649 * Scan the valid bits looking for invalid sections that 1650 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1651 * valid bit may be set ) have already been zerod by 1652 * vm_page_set_validclean(). 1653 */ 1654 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1655 if (i == (PAGE_SIZE / DEV_BSIZE) || 1656 (m->valid & (1 << i)) 1657 ) { 1658 if (i > b) { 1659 pmap_zero_page_area(m, 1660 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1661 } 1662 b = i + 1; 1663 } 1664 } 1665 1666 /* 1667 * setvalid is TRUE when we can safely set the zero'd areas 1668 * as being valid. We can do this if there are no cache consistancy 1669 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1670 */ 1671 if (setvalid) 1672 m->valid = VM_PAGE_BITS_ALL; 1673 } 1674 1675 /* 1676 * vm_page_is_valid: 1677 * 1678 * Is (partial) page valid? Note that the case where size == 0 1679 * will return FALSE in the degenerate case where the page is 1680 * entirely invalid, and TRUE otherwise. 1681 * 1682 * May not block. 1683 */ 1684 int 1685 vm_page_is_valid(vm_page_t m, int base, int size) 1686 { 1687 int bits = vm_page_bits(base, size); 1688 1689 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1690 if (m->valid && ((m->valid & bits) == bits)) 1691 return 1; 1692 else 1693 return 0; 1694 } 1695 1696 /* 1697 * update dirty bits from pmap/mmu. May not block. 1698 */ 1699 void 1700 vm_page_test_dirty(vm_page_t m) 1701 { 1702 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1703 vm_page_dirty(m); 1704 } 1705 } 1706 1707 int so_zerocp_fullpage = 0; 1708 1709 void 1710 vm_page_cowfault(vm_page_t m) 1711 { 1712 vm_page_t mnew; 1713 vm_object_t object; 1714 vm_pindex_t pindex; 1715 1716 object = m->object; 1717 pindex = m->pindex; 1718 1719 retry_alloc: 1720 pmap_remove_all(m); 1721 vm_page_remove(m); 1722 mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 1723 if (mnew == NULL) { 1724 vm_page_insert(m, object, pindex); 1725 vm_page_unlock_queues(); 1726 VM_OBJECT_UNLOCK(object); 1727 VM_WAIT; 1728 VM_OBJECT_LOCK(object); 1729 vm_page_lock_queues(); 1730 goto retry_alloc; 1731 } 1732 1733 if (m->cow == 0) { 1734 /* 1735 * check to see if we raced with an xmit complete when 1736 * waiting to allocate a page. If so, put things back 1737 * the way they were 1738 */ 1739 vm_page_free(mnew); 1740 vm_page_insert(m, object, pindex); 1741 } else { /* clear COW & copy page */ 1742 if (!so_zerocp_fullpage) 1743 pmap_copy_page(m, mnew); 1744 mnew->valid = VM_PAGE_BITS_ALL; 1745 vm_page_dirty(mnew); 1746 mnew->wire_count = m->wire_count - m->cow; 1747 m->wire_count = m->cow; 1748 } 1749 } 1750 1751 void 1752 vm_page_cowclear(vm_page_t m) 1753 { 1754 1755 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1756 if (m->cow) { 1757 m->cow--; 1758 /* 1759 * let vm_fault add back write permission lazily 1760 */ 1761 } 1762 /* 1763 * sf_buf_free() will free the page, so we needn't do it here 1764 */ 1765 } 1766 1767 void 1768 vm_page_cowsetup(vm_page_t m) 1769 { 1770 1771 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1772 m->cow++; 1773 pmap_remove_write(m); 1774 } 1775 1776 #include "opt_ddb.h" 1777 #ifdef DDB 1778 #include <sys/kernel.h> 1779 1780 #include <ddb/ddb.h> 1781 1782 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1783 { 1784 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1785 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1786 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1787 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1788 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1789 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1790 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1791 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1792 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1793 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1794 } 1795 1796 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1797 { 1798 int i; 1799 db_printf("PQ_FREE:"); 1800 for (i = 0; i < PQ_NUMCOLORS; i++) { 1801 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1802 } 1803 db_printf("\n"); 1804 1805 db_printf("PQ_CACHE:"); 1806 for (i = 0; i < PQ_NUMCOLORS; i++) { 1807 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1808 } 1809 db_printf("\n"); 1810 1811 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1812 vm_page_queues[PQ_ACTIVE].lcnt, 1813 vm_page_queues[PQ_INACTIVE].lcnt); 1814 } 1815 #endif /* DDB */ 1816