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->flags & PG_BUSY) == 0, 376 ("vm_page_busy: page already busy!!!")); 377 vm_page_flag_set(m, PG_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->flags & PG_WANTED) { 391 vm_page_flag_clear(m, PG_WANTED); 392 wakeup(m); 393 } 394 } 395 396 /* 397 * vm_page_wakeup: 398 * 399 * clear the PG_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->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 409 vm_page_flag_clear(m, PG_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 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 427 m->busy--; 428 if (m->busy == 0) 429 vm_page_flash(m); 430 } 431 432 /* 433 * Keep page from being freed by the page daemon 434 * much of the same effect as wiring, except much lower 435 * overhead and should be used only for *very* temporary 436 * holding ("wiring"). 437 */ 438 void 439 vm_page_hold(vm_page_t mem) 440 { 441 442 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 443 mem->hold_count++; 444 } 445 446 void 447 vm_page_unhold(vm_page_t mem) 448 { 449 450 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 451 --mem->hold_count; 452 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 453 if (mem->hold_count == 0 && VM_PAGE_INQUEUE2(mem, PQ_HOLD)) 454 vm_page_free_toq(mem); 455 } 456 457 /* 458 * vm_page_free: 459 * 460 * Free a page 461 * 462 * The clearing of PG_ZERO is a temporary safety until the code can be 463 * reviewed to determine that PG_ZERO is being properly cleared on 464 * write faults or maps. PG_ZERO was previously cleared in 465 * vm_page_alloc(). 466 */ 467 void 468 vm_page_free(vm_page_t m) 469 { 470 vm_page_flag_clear(m, PG_ZERO); 471 vm_page_free_toq(m); 472 vm_page_zero_idle_wakeup(); 473 } 474 475 /* 476 * vm_page_free_zero: 477 * 478 * Free a page to the zerod-pages queue 479 */ 480 void 481 vm_page_free_zero(vm_page_t m) 482 { 483 vm_page_flag_set(m, PG_ZERO); 484 vm_page_free_toq(m); 485 } 486 487 /* 488 * vm_page_sleep_if_busy: 489 * 490 * Sleep and release the page queues lock if PG_BUSY is set or, 491 * if also_m_busy is TRUE, busy is non-zero. Returns TRUE if the 492 * thread slept and the page queues lock was released. 493 * Otherwise, retains the page queues lock and returns FALSE. 494 */ 495 int 496 vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg) 497 { 498 vm_object_t object; 499 500 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 501 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 502 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 503 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 504 /* 505 * It's possible that while we sleep, the page will get 506 * unbusied and freed. If we are holding the object 507 * lock, we will assume we hold a reference to the object 508 * such that even if m->object changes, we can re-lock 509 * it. 510 */ 511 object = m->object; 512 VM_OBJECT_UNLOCK(object); 513 msleep(m, &vm_page_queue_mtx, PDROP | PVM, msg, 0); 514 VM_OBJECT_LOCK(object); 515 return (TRUE); 516 } 517 return (FALSE); 518 } 519 520 /* 521 * vm_page_dirty: 522 * 523 * make page all dirty 524 */ 525 void 526 vm_page_dirty(vm_page_t m) 527 { 528 KASSERT(VM_PAGE_GETKNOWNQUEUE1(m) != PQ_CACHE, 529 ("vm_page_dirty: page in cache!")); 530 KASSERT(VM_PAGE_GETKNOWNQUEUE1(m) != PQ_FREE, 531 ("vm_page_dirty: page is free!")); 532 m->dirty = VM_PAGE_BITS_ALL; 533 } 534 535 /* 536 * vm_page_splay: 537 * 538 * Implements Sleator and Tarjan's top-down splay algorithm. Returns 539 * the vm_page containing the given pindex. If, however, that 540 * pindex is not found in the vm_object, returns a vm_page that is 541 * adjacent to the pindex, coming before or after it. 542 */ 543 vm_page_t 544 vm_page_splay(vm_pindex_t pindex, vm_page_t root) 545 { 546 struct vm_page dummy; 547 vm_page_t lefttreemax, righttreemin, y; 548 549 if (root == NULL) 550 return (root); 551 lefttreemax = righttreemin = &dummy; 552 for (;; root = y) { 553 if (pindex < root->pindex) { 554 if ((y = root->left) == NULL) 555 break; 556 if (pindex < y->pindex) { 557 /* Rotate right. */ 558 root->left = y->right; 559 y->right = root; 560 root = y; 561 if ((y = root->left) == NULL) 562 break; 563 } 564 /* Link into the new root's right tree. */ 565 righttreemin->left = root; 566 righttreemin = root; 567 } else if (pindex > root->pindex) { 568 if ((y = root->right) == NULL) 569 break; 570 if (pindex > y->pindex) { 571 /* Rotate left. */ 572 root->right = y->left; 573 y->left = root; 574 root = y; 575 if ((y = root->right) == NULL) 576 break; 577 } 578 /* Link into the new root's left tree. */ 579 lefttreemax->right = root; 580 lefttreemax = root; 581 } else 582 break; 583 } 584 /* Assemble the new root. */ 585 lefttreemax->right = root->left; 586 righttreemin->left = root->right; 587 root->left = dummy.right; 588 root->right = dummy.left; 589 return (root); 590 } 591 592 /* 593 * vm_page_insert: [ internal use only ] 594 * 595 * Inserts the given mem entry into the object and object list. 596 * 597 * The pagetables are not updated but will presumably fault the page 598 * in if necessary, or if a kernel page the caller will at some point 599 * enter the page into the kernel's pmap. We are not allowed to block 600 * here so we *can't* do this anyway. 601 * 602 * The object and page must be locked. 603 * This routine may not block. 604 */ 605 void 606 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 607 { 608 vm_page_t root; 609 610 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 611 if (m->object != NULL) 612 panic("vm_page_insert: page already inserted"); 613 614 /* 615 * Record the object/offset pair in this page 616 */ 617 m->object = object; 618 m->pindex = pindex; 619 620 /* 621 * Now link into the object's ordered list of backed pages. 622 */ 623 root = object->root; 624 if (root == NULL) { 625 m->left = NULL; 626 m->right = NULL; 627 TAILQ_INSERT_TAIL(&object->memq, m, listq); 628 } else { 629 root = vm_page_splay(pindex, root); 630 if (pindex < root->pindex) { 631 m->left = root->left; 632 m->right = root; 633 root->left = NULL; 634 TAILQ_INSERT_BEFORE(root, m, listq); 635 } else if (pindex == root->pindex) 636 panic("vm_page_insert: offset already allocated"); 637 else { 638 m->right = root->right; 639 m->left = root; 640 root->right = NULL; 641 TAILQ_INSERT_AFTER(&object->memq, root, m, listq); 642 } 643 } 644 object->root = m; 645 object->generation++; 646 647 /* 648 * show that the object has one more resident page. 649 */ 650 object->resident_page_count++; 651 /* 652 * Hold the vnode until the last page is released. 653 */ 654 if (object->resident_page_count == 1 && object->type == OBJT_VNODE) 655 vhold((struct vnode *)object->handle); 656 657 /* 658 * Since we are inserting a new and possibly dirty page, 659 * update the object's OBJ_MIGHTBEDIRTY flag. 660 */ 661 if (m->flags & PG_WRITEABLE) 662 vm_object_set_writeable_dirty(object); 663 } 664 665 /* 666 * vm_page_remove: 667 * NOTE: used by device pager as well -wfj 668 * 669 * Removes the given mem entry from the object/offset-page 670 * table and the object page list, but do not invalidate/terminate 671 * the backing store. 672 * 673 * The object and page must be locked. 674 * The underlying pmap entry (if any) is NOT removed here. 675 * This routine may not block. 676 */ 677 void 678 vm_page_remove(vm_page_t m) 679 { 680 vm_object_t object; 681 vm_page_t root; 682 683 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 684 if ((object = m->object) == NULL) 685 return; 686 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 687 if (m->flags & PG_BUSY) { 688 vm_page_flag_clear(m, PG_BUSY); 689 vm_page_flash(m); 690 } 691 692 /* 693 * Now remove from the object's list of backed pages. 694 */ 695 if (m != object->root) 696 vm_page_splay(m->pindex, object->root); 697 if (m->left == NULL) 698 root = m->right; 699 else { 700 root = vm_page_splay(m->pindex, m->left); 701 root->right = m->right; 702 } 703 object->root = root; 704 TAILQ_REMOVE(&object->memq, m, listq); 705 706 /* 707 * And show that the object has one fewer resident page. 708 */ 709 object->resident_page_count--; 710 object->generation++; 711 /* 712 * The vnode may now be recycled. 713 */ 714 if (object->resident_page_count == 0 && object->type == OBJT_VNODE) 715 vdrop((struct vnode *)object->handle); 716 717 m->object = NULL; 718 } 719 720 /* 721 * vm_page_lookup: 722 * 723 * Returns the page associated with the object/offset 724 * pair specified; if none is found, NULL is returned. 725 * 726 * The object must be locked. 727 * This routine may not block. 728 * This is a critical path routine 729 */ 730 vm_page_t 731 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 732 { 733 vm_page_t m; 734 735 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 736 if ((m = object->root) != NULL && m->pindex != pindex) { 737 m = vm_page_splay(pindex, m); 738 if ((object->root = m)->pindex != pindex) 739 m = NULL; 740 } 741 return (m); 742 } 743 744 /* 745 * vm_page_rename: 746 * 747 * Move the given memory entry from its 748 * current object to the specified target object/offset. 749 * 750 * The object must be locked. 751 * This routine may not block. 752 * 753 * Note: swap associated with the page must be invalidated by the move. We 754 * have to do this for several reasons: (1) we aren't freeing the 755 * page, (2) we are dirtying the page, (3) the VM system is probably 756 * moving the page from object A to B, and will then later move 757 * the backing store from A to B and we can't have a conflict. 758 * 759 * Note: we *always* dirty the page. It is necessary both for the 760 * fact that we moved it, and because we may be invalidating 761 * swap. If the page is on the cache, we have to deactivate it 762 * or vm_page_dirty() will panic. Dirty pages are not allowed 763 * on the cache. 764 */ 765 void 766 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 767 { 768 769 vm_page_remove(m); 770 vm_page_insert(m, new_object, new_pindex); 771 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 772 vm_page_deactivate(m); 773 vm_page_dirty(m); 774 } 775 776 /* 777 * vm_page_select_cache: 778 * 779 * Move a page of the given color from the cache queue to the free 780 * queue. As pages might be found, but are not applicable, they are 781 * deactivated. 782 * 783 * This routine may not block. 784 */ 785 vm_page_t 786 vm_page_select_cache(int color) 787 { 788 vm_object_t object; 789 vm_page_t m; 790 boolean_t was_trylocked; 791 792 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 793 while ((m = vm_pageq_find(PQ_CACHE, color, FALSE)) != NULL) { 794 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 795 KASSERT(!pmap_page_is_mapped(m), 796 ("Found mapped cache page %p", m)); 797 KASSERT((m->flags & PG_UNMANAGED) == 0, 798 ("Found unmanaged cache page %p", m)); 799 KASSERT(m->wire_count == 0, ("Found wired cache page %p", m)); 800 if (m->hold_count == 0 && (object = m->object, 801 (was_trylocked = VM_OBJECT_TRYLOCK(object)) || 802 VM_OBJECT_LOCKED(object))) { 803 KASSERT((m->flags & PG_BUSY) == 0 && m->busy == 0, 804 ("Found busy cache page %p", m)); 805 vm_page_free(m); 806 if (was_trylocked) 807 VM_OBJECT_UNLOCK(object); 808 break; 809 } 810 vm_page_deactivate(m); 811 } 812 return (m); 813 } 814 815 /* 816 * vm_page_alloc: 817 * 818 * Allocate and return a memory cell associated 819 * with this VM object/offset pair. 820 * 821 * page_req classes: 822 * VM_ALLOC_NORMAL normal process request 823 * VM_ALLOC_SYSTEM system *really* needs a page 824 * VM_ALLOC_INTERRUPT interrupt time request 825 * VM_ALLOC_ZERO zero page 826 * 827 * This routine may not block. 828 * 829 * Additional special handling is required when called from an 830 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 831 * the page cache in this case. 832 */ 833 vm_page_t 834 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) 835 { 836 vm_page_t m = NULL; 837 int color, flags, page_req; 838 839 page_req = req & VM_ALLOC_CLASS_MASK; 840 KASSERT(curthread->td_intr_nesting_level == 0 || 841 page_req == VM_ALLOC_INTERRUPT, 842 ("vm_page_alloc(NORMAL|SYSTEM) in interrupt context")); 843 844 if ((req & VM_ALLOC_NOOBJ) == 0) { 845 KASSERT(object != NULL, 846 ("vm_page_alloc: NULL object.")); 847 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 848 color = (pindex + object->pg_color) & PQ_COLORMASK; 849 } else 850 color = pindex & PQ_COLORMASK; 851 852 /* 853 * The pager is allowed to eat deeper into the free page list. 854 */ 855 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 856 page_req = VM_ALLOC_SYSTEM; 857 }; 858 859 loop: 860 mtx_lock_spin(&vm_page_queue_free_mtx); 861 if (cnt.v_free_count > cnt.v_free_reserved || 862 (page_req == VM_ALLOC_SYSTEM && 863 cnt.v_cache_count == 0 && 864 cnt.v_free_count > cnt.v_interrupt_free_min) || 865 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0)) { 866 /* 867 * Allocate from the free queue if the number of free pages 868 * exceeds the minimum for the request class. 869 */ 870 m = vm_pageq_find(PQ_FREE, color, (req & VM_ALLOC_ZERO) != 0); 871 } else if (page_req != VM_ALLOC_INTERRUPT) { 872 mtx_unlock_spin(&vm_page_queue_free_mtx); 873 /* 874 * Allocatable from cache (non-interrupt only). On success, 875 * we must free the page and try again, thus ensuring that 876 * cnt.v_*_free_min counters are replenished. 877 */ 878 vm_page_lock_queues(); 879 if ((m = vm_page_select_cache(color)) == NULL) { 880 KASSERT(cnt.v_cache_count == 0, 881 ("vm_page_alloc: cache queue is missing %d pages", 882 cnt.v_cache_count)); 883 vm_page_unlock_queues(); 884 atomic_add_int(&vm_pageout_deficit, 1); 885 pagedaemon_wakeup(); 886 887 if (page_req != VM_ALLOC_SYSTEM) 888 return NULL; 889 890 mtx_lock_spin(&vm_page_queue_free_mtx); 891 if (cnt.v_free_count <= cnt.v_interrupt_free_min) { 892 mtx_unlock_spin(&vm_page_queue_free_mtx); 893 return (NULL); 894 } 895 m = vm_pageq_find(PQ_FREE, color, (req & VM_ALLOC_ZERO) != 0); 896 } else { 897 vm_page_unlock_queues(); 898 goto loop; 899 } 900 } else { 901 /* 902 * Not allocatable from cache from interrupt, give up. 903 */ 904 mtx_unlock_spin(&vm_page_queue_free_mtx); 905 atomic_add_int(&vm_pageout_deficit, 1); 906 pagedaemon_wakeup(); 907 return (NULL); 908 } 909 910 /* 911 * At this point we had better have found a good page. 912 */ 913 914 KASSERT( 915 m != NULL, 916 ("vm_page_alloc(): missing page on free queue") 917 ); 918 919 /* 920 * Remove from free queue 921 */ 922 vm_pageq_remove_nowakeup(m); 923 924 /* 925 * Initialize structure. Only the PG_ZERO flag is inherited. 926 */ 927 flags = PG_BUSY; 928 if (m->flags & PG_ZERO) { 929 vm_page_zero_count--; 930 if (req & VM_ALLOC_ZERO) 931 flags = PG_ZERO | PG_BUSY; 932 } 933 if (req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ)) 934 flags &= ~PG_BUSY; 935 m->flags = flags; 936 if (req & VM_ALLOC_WIRED) { 937 atomic_add_int(&cnt.v_wire_count, 1); 938 m->wire_count = 1; 939 } else 940 m->wire_count = 0; 941 m->hold_count = 0; 942 m->act_count = 0; 943 m->busy = 0; 944 m->valid = 0; 945 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 946 mtx_unlock_spin(&vm_page_queue_free_mtx); 947 948 if ((req & VM_ALLOC_NOOBJ) == 0) 949 vm_page_insert(m, object, pindex); 950 else 951 m->pindex = pindex; 952 953 /* 954 * Don't wakeup too often - wakeup the pageout daemon when 955 * we would be nearly out of memory. 956 */ 957 if (vm_paging_needed()) 958 pagedaemon_wakeup(); 959 960 return (m); 961 } 962 963 /* 964 * vm_wait: (also see VM_WAIT macro) 965 * 966 * Block until free pages are available for allocation 967 * - Called in various places before memory allocations. 968 */ 969 void 970 vm_wait(void) 971 { 972 973 vm_page_lock_queues(); 974 if (curproc == pageproc) { 975 vm_pageout_pages_needed = 1; 976 msleep(&vm_pageout_pages_needed, &vm_page_queue_mtx, 977 PDROP | PSWP, "VMWait", 0); 978 } else { 979 if (!vm_pages_needed) { 980 vm_pages_needed = 1; 981 wakeup(&vm_pages_needed); 982 } 983 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PVM, 984 "vmwait", 0); 985 } 986 } 987 988 /* 989 * vm_waitpfault: (also see VM_WAITPFAULT macro) 990 * 991 * Block until free pages are available for allocation 992 * - Called only in vm_fault so that processes page faulting 993 * can be easily tracked. 994 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 995 * processes will be able to grab memory first. Do not change 996 * this balance without careful testing first. 997 */ 998 void 999 vm_waitpfault(void) 1000 { 1001 1002 vm_page_lock_queues(); 1003 if (!vm_pages_needed) { 1004 vm_pages_needed = 1; 1005 wakeup(&vm_pages_needed); 1006 } 1007 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PUSER, 1008 "pfault", 0); 1009 } 1010 1011 /* 1012 * vm_page_activate: 1013 * 1014 * Put the specified page on the active list (if appropriate). 1015 * Ensure that act_count is at least ACT_INIT but do not otherwise 1016 * mess with it. 1017 * 1018 * The page queues must be locked. 1019 * This routine may not block. 1020 */ 1021 void 1022 vm_page_activate(vm_page_t m) 1023 { 1024 1025 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1026 if (VM_PAGE_GETKNOWNQUEUE2(m) != PQ_ACTIVE) { 1027 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1028 cnt.v_reactivated++; 1029 vm_pageq_remove(m); 1030 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1031 if (m->act_count < ACT_INIT) 1032 m->act_count = ACT_INIT; 1033 vm_pageq_enqueue(PQ_ACTIVE, m); 1034 } 1035 } else { 1036 if (m->act_count < ACT_INIT) 1037 m->act_count = ACT_INIT; 1038 } 1039 } 1040 1041 /* 1042 * vm_page_free_wakeup: 1043 * 1044 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 1045 * routine is called when a page has been added to the cache or free 1046 * queues. 1047 * 1048 * The page queues must be locked. 1049 * This routine may not block. 1050 */ 1051 static inline void 1052 vm_page_free_wakeup(void) 1053 { 1054 1055 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1056 /* 1057 * if pageout daemon needs pages, then tell it that there are 1058 * some free. 1059 */ 1060 if (vm_pageout_pages_needed && 1061 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 1062 wakeup(&vm_pageout_pages_needed); 1063 vm_pageout_pages_needed = 0; 1064 } 1065 /* 1066 * wakeup processes that are waiting on memory if we hit a 1067 * high water mark. And wakeup scheduler process if we have 1068 * lots of memory. this process will swapin processes. 1069 */ 1070 if (vm_pages_needed && !vm_page_count_min()) { 1071 vm_pages_needed = 0; 1072 wakeup(&cnt.v_free_count); 1073 } 1074 } 1075 1076 /* 1077 * vm_page_free_toq: 1078 * 1079 * Returns the given page to the PQ_FREE list, 1080 * disassociating it with any VM object. 1081 * 1082 * Object and page must be locked prior to entry. 1083 * This routine may not block. 1084 */ 1085 1086 void 1087 vm_page_free_toq(vm_page_t m) 1088 { 1089 struct vpgqueues *pq; 1090 1091 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1092 KASSERT(!pmap_page_is_mapped(m), 1093 ("vm_page_free_toq: freeing mapped page %p", m)); 1094 cnt.v_tfree++; 1095 1096 if (m->busy || VM_PAGE_INQUEUE1(m, PQ_FREE)) { 1097 printf( 1098 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1099 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1100 m->hold_count); 1101 if (VM_PAGE_INQUEUE1(m, PQ_FREE)) 1102 panic("vm_page_free: freeing free page"); 1103 else 1104 panic("vm_page_free: freeing busy page"); 1105 } 1106 1107 /* 1108 * unqueue, then remove page. Note that we cannot destroy 1109 * the page here because we do not want to call the pager's 1110 * callback routine until after we've put the page on the 1111 * appropriate free queue. 1112 */ 1113 vm_pageq_remove_nowakeup(m); 1114 vm_page_remove(m); 1115 1116 /* 1117 * If fictitious remove object association and 1118 * return, otherwise delay object association removal. 1119 */ 1120 if ((m->flags & PG_FICTITIOUS) != 0) { 1121 return; 1122 } 1123 1124 m->valid = 0; 1125 vm_page_undirty(m); 1126 1127 if (m->wire_count != 0) { 1128 if (m->wire_count > 1) { 1129 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1130 m->wire_count, (long)m->pindex); 1131 } 1132 panic("vm_page_free: freeing wired page"); 1133 } 1134 1135 /* 1136 * Clear the UNMANAGED flag when freeing an unmanaged page. 1137 */ 1138 if (m->flags & PG_UNMANAGED) { 1139 m->flags &= ~PG_UNMANAGED; 1140 } 1141 1142 if (m->hold_count != 0) { 1143 m->flags &= ~PG_ZERO; 1144 VM_PAGE_SETQUEUE2(m, PQ_HOLD); 1145 } else 1146 VM_PAGE_SETQUEUE1(m, PQ_FREE); 1147 pq = &vm_page_queues[VM_PAGE_GETQUEUE(m)]; 1148 mtx_lock_spin(&vm_page_queue_free_mtx); 1149 pq->lcnt++; 1150 ++(*pq->cnt); 1151 1152 /* 1153 * Put zero'd pages on the end ( where we look for zero'd pages 1154 * first ) and non-zerod pages at the head. 1155 */ 1156 if (m->flags & PG_ZERO) { 1157 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1158 ++vm_page_zero_count; 1159 } else { 1160 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1161 } 1162 mtx_unlock_spin(&vm_page_queue_free_mtx); 1163 vm_page_free_wakeup(); 1164 } 1165 1166 /* 1167 * vm_page_unmanage: 1168 * 1169 * Prevent PV management from being done on the page. The page is 1170 * removed from the paging queues as if it were wired, and as a 1171 * consequence of no longer being managed the pageout daemon will not 1172 * touch it (since there is no way to locate the pte mappings for the 1173 * page). madvise() calls that mess with the pmap will also no longer 1174 * operate on the page. 1175 * 1176 * Beyond that the page is still reasonably 'normal'. Freeing the page 1177 * will clear the flag. 1178 * 1179 * This routine is used by OBJT_PHYS objects - objects using unswappable 1180 * physical memory as backing store rather then swap-backed memory and 1181 * will eventually be extended to support 4MB unmanaged physical 1182 * mappings. 1183 */ 1184 void 1185 vm_page_unmanage(vm_page_t m) 1186 { 1187 1188 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1189 if ((m->flags & PG_UNMANAGED) == 0) { 1190 if (m->wire_count == 0) 1191 vm_pageq_remove(m); 1192 } 1193 vm_page_flag_set(m, PG_UNMANAGED); 1194 } 1195 1196 /* 1197 * vm_page_wire: 1198 * 1199 * Mark this page as wired down by yet 1200 * another map, removing it from paging queues 1201 * as necessary. 1202 * 1203 * The page queues must be locked. 1204 * This routine may not block. 1205 */ 1206 void 1207 vm_page_wire(vm_page_t m) 1208 { 1209 1210 /* 1211 * Only bump the wire statistics if the page is not already wired, 1212 * and only unqueue the page if it is on some queue (if it is unmanaged 1213 * it is already off the queues). 1214 */ 1215 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1216 if (m->flags & PG_FICTITIOUS) 1217 return; 1218 if (m->wire_count == 0) { 1219 if ((m->flags & PG_UNMANAGED) == 0) 1220 vm_pageq_remove(m); 1221 atomic_add_int(&cnt.v_wire_count, 1); 1222 } 1223 m->wire_count++; 1224 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1225 } 1226 1227 /* 1228 * vm_page_unwire: 1229 * 1230 * Release one wiring of this page, potentially 1231 * enabling it to be paged again. 1232 * 1233 * Many pages placed on the inactive queue should actually go 1234 * into the cache, but it is difficult to figure out which. What 1235 * we do instead, if the inactive target is well met, is to put 1236 * clean pages at the head of the inactive queue instead of the tail. 1237 * This will cause them to be moved to the cache more quickly and 1238 * if not actively re-referenced, freed more quickly. If we just 1239 * stick these pages at the end of the inactive queue, heavy filesystem 1240 * meta-data accesses can cause an unnecessary paging load on memory bound 1241 * processes. This optimization causes one-time-use metadata to be 1242 * reused more quickly. 1243 * 1244 * BUT, if we are in a low-memory situation we have no choice but to 1245 * put clean pages on the cache queue. 1246 * 1247 * A number of routines use vm_page_unwire() to guarantee that the page 1248 * will go into either the inactive or active queues, and will NEVER 1249 * be placed in the cache - for example, just after dirtying a page. 1250 * dirty pages in the cache are not allowed. 1251 * 1252 * The page queues must be locked. 1253 * This routine may not block. 1254 */ 1255 void 1256 vm_page_unwire(vm_page_t m, int activate) 1257 { 1258 1259 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1260 if (m->flags & PG_FICTITIOUS) 1261 return; 1262 if (m->wire_count > 0) { 1263 m->wire_count--; 1264 if (m->wire_count == 0) { 1265 atomic_subtract_int(&cnt.v_wire_count, 1); 1266 if (m->flags & PG_UNMANAGED) { 1267 ; 1268 } else if (activate) 1269 vm_pageq_enqueue(PQ_ACTIVE, m); 1270 else { 1271 vm_page_flag_clear(m, PG_WINATCFLS); 1272 vm_pageq_enqueue(PQ_INACTIVE, m); 1273 } 1274 } 1275 } else { 1276 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1277 } 1278 } 1279 1280 1281 /* 1282 * Move the specified page to the inactive queue. If the page has 1283 * any associated swap, the swap is deallocated. 1284 * 1285 * Normally athead is 0 resulting in LRU operation. athead is set 1286 * to 1 if we want this page to be 'as if it were placed in the cache', 1287 * except without unmapping it from the process address space. 1288 * 1289 * This routine may not block. 1290 */ 1291 static inline void 1292 _vm_page_deactivate(vm_page_t m, int athead) 1293 { 1294 1295 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1296 1297 /* 1298 * Ignore if already inactive. 1299 */ 1300 if (VM_PAGE_INQUEUE2(m, PQ_INACTIVE)) 1301 return; 1302 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1303 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1304 cnt.v_reactivated++; 1305 vm_page_flag_clear(m, PG_WINATCFLS); 1306 vm_pageq_remove(m); 1307 if (athead) 1308 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1309 else 1310 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1311 VM_PAGE_SETQUEUE2(m, PQ_INACTIVE); 1312 vm_page_queues[PQ_INACTIVE].lcnt++; 1313 cnt.v_inactive_count++; 1314 } 1315 } 1316 1317 void 1318 vm_page_deactivate(vm_page_t m) 1319 { 1320 _vm_page_deactivate(m, 0); 1321 } 1322 1323 /* 1324 * vm_page_try_to_cache: 1325 * 1326 * Returns 0 on failure, 1 on success 1327 */ 1328 int 1329 vm_page_try_to_cache(vm_page_t m) 1330 { 1331 1332 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1333 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1334 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1335 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1336 return (0); 1337 } 1338 pmap_remove_all(m); 1339 if (m->dirty) 1340 return (0); 1341 vm_page_cache(m); 1342 return (1); 1343 } 1344 1345 /* 1346 * vm_page_try_to_free() 1347 * 1348 * Attempt to free the page. If we cannot free it, we do nothing. 1349 * 1 is returned on success, 0 on failure. 1350 */ 1351 int 1352 vm_page_try_to_free(vm_page_t m) 1353 { 1354 1355 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1356 if (m->object != NULL) 1357 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1358 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1359 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1360 return (0); 1361 } 1362 pmap_remove_all(m); 1363 if (m->dirty) 1364 return (0); 1365 vm_page_free(m); 1366 return (1); 1367 } 1368 1369 /* 1370 * vm_page_cache 1371 * 1372 * Put the specified page onto the page cache queue (if appropriate). 1373 * 1374 * This routine may not block. 1375 */ 1376 void 1377 vm_page_cache(vm_page_t m) 1378 { 1379 1380 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1381 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1382 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1383 m->hold_count || m->wire_count) { 1384 printf("vm_page_cache: attempting to cache busy page\n"); 1385 return; 1386 } 1387 if (VM_PAGE_INQUEUE1(m, PQ_CACHE)) 1388 return; 1389 1390 /* 1391 * Remove all pmaps and indicate that the page is not 1392 * writeable or mapped. 1393 */ 1394 pmap_remove_all(m); 1395 if (m->dirty != 0) { 1396 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1397 (long)m->pindex); 1398 } 1399 vm_pageq_remove_nowakeup(m); 1400 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1401 vm_page_free_wakeup(); 1402 } 1403 1404 /* 1405 * vm_page_dontneed 1406 * 1407 * Cache, deactivate, or do nothing as appropriate. This routine 1408 * is typically used by madvise() MADV_DONTNEED. 1409 * 1410 * Generally speaking we want to move the page into the cache so 1411 * it gets reused quickly. However, this can result in a silly syndrome 1412 * due to the page recycling too quickly. Small objects will not be 1413 * fully cached. On the otherhand, if we move the page to the inactive 1414 * queue we wind up with a problem whereby very large objects 1415 * unnecessarily blow away our inactive and cache queues. 1416 * 1417 * The solution is to move the pages based on a fixed weighting. We 1418 * either leave them alone, deactivate them, or move them to the cache, 1419 * where moving them to the cache has the highest weighting. 1420 * By forcing some pages into other queues we eventually force the 1421 * system to balance the queues, potentially recovering other unrelated 1422 * space from active. The idea is to not force this to happen too 1423 * often. 1424 */ 1425 void 1426 vm_page_dontneed(vm_page_t m) 1427 { 1428 static int dnweight; 1429 int dnw; 1430 int head; 1431 1432 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1433 dnw = ++dnweight; 1434 1435 /* 1436 * occassionally leave the page alone 1437 */ 1438 if ((dnw & 0x01F0) == 0 || 1439 VM_PAGE_INQUEUE2(m, PQ_INACTIVE) || 1440 VM_PAGE_INQUEUE1(m, PQ_CACHE) 1441 ) { 1442 if (m->act_count >= ACT_INIT) 1443 --m->act_count; 1444 return; 1445 } 1446 1447 if (m->dirty == 0 && pmap_is_modified(m)) 1448 vm_page_dirty(m); 1449 1450 if (m->dirty || (dnw & 0x0070) == 0) { 1451 /* 1452 * Deactivate the page 3 times out of 32. 1453 */ 1454 head = 0; 1455 } else { 1456 /* 1457 * Cache the page 28 times out of every 32. Note that 1458 * the page is deactivated instead of cached, but placed 1459 * at the head of the queue instead of the tail. 1460 */ 1461 head = 1; 1462 } 1463 _vm_page_deactivate(m, head); 1464 } 1465 1466 /* 1467 * Grab a page, waiting until we are waken up due to the page 1468 * changing state. We keep on waiting, if the page continues 1469 * to be in the object. If the page doesn't exist, first allocate it 1470 * and then conditionally zero it. 1471 * 1472 * This routine may block. 1473 */ 1474 vm_page_t 1475 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1476 { 1477 vm_page_t m; 1478 1479 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1480 retrylookup: 1481 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1482 vm_page_lock_queues(); 1483 if (m->busy || (m->flags & PG_BUSY)) { 1484 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1485 VM_OBJECT_UNLOCK(object); 1486 msleep(m, &vm_page_queue_mtx, PDROP | PVM, "pgrbwt", 0); 1487 VM_OBJECT_LOCK(object); 1488 if ((allocflags & VM_ALLOC_RETRY) == 0) 1489 return (NULL); 1490 goto retrylookup; 1491 } else { 1492 if (allocflags & VM_ALLOC_WIRED) 1493 vm_page_wire(m); 1494 if ((allocflags & VM_ALLOC_NOBUSY) == 0) 1495 vm_page_busy(m); 1496 vm_page_unlock_queues(); 1497 return (m); 1498 } 1499 } 1500 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1501 if (m == NULL) { 1502 VM_OBJECT_UNLOCK(object); 1503 VM_WAIT; 1504 VM_OBJECT_LOCK(object); 1505 if ((allocflags & VM_ALLOC_RETRY) == 0) 1506 return (NULL); 1507 goto retrylookup; 1508 } 1509 if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0) 1510 pmap_zero_page(m); 1511 return (m); 1512 } 1513 1514 /* 1515 * Mapping function for valid bits or for dirty bits in 1516 * a page. May not block. 1517 * 1518 * Inputs are required to range within a page. 1519 */ 1520 inline int 1521 vm_page_bits(int base, int size) 1522 { 1523 int first_bit; 1524 int last_bit; 1525 1526 KASSERT( 1527 base + size <= PAGE_SIZE, 1528 ("vm_page_bits: illegal base/size %d/%d", base, size) 1529 ); 1530 1531 if (size == 0) /* handle degenerate case */ 1532 return (0); 1533 1534 first_bit = base >> DEV_BSHIFT; 1535 last_bit = (base + size - 1) >> DEV_BSHIFT; 1536 1537 return ((2 << last_bit) - (1 << first_bit)); 1538 } 1539 1540 /* 1541 * vm_page_set_validclean: 1542 * 1543 * Sets portions of a page valid and clean. The arguments are expected 1544 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1545 * of any partial chunks touched by the range. The invalid portion of 1546 * such chunks will be zero'd. 1547 * 1548 * This routine may not block. 1549 * 1550 * (base + size) must be less then or equal to PAGE_SIZE. 1551 */ 1552 void 1553 vm_page_set_validclean(vm_page_t m, int base, int size) 1554 { 1555 int pagebits; 1556 int frag; 1557 int endoff; 1558 1559 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1560 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1561 if (size == 0) /* handle degenerate case */ 1562 return; 1563 1564 /* 1565 * If the base is not DEV_BSIZE aligned and the valid 1566 * bit is clear, we have to zero out a portion of the 1567 * first block. 1568 */ 1569 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1570 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1571 pmap_zero_page_area(m, frag, base - frag); 1572 1573 /* 1574 * If the ending offset is not DEV_BSIZE aligned and the 1575 * valid bit is clear, we have to zero out a portion of 1576 * the last block. 1577 */ 1578 endoff = base + size; 1579 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1580 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1581 pmap_zero_page_area(m, endoff, 1582 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1583 1584 /* 1585 * Set valid, clear dirty bits. If validating the entire 1586 * page we can safely clear the pmap modify bit. We also 1587 * use this opportunity to clear the PG_NOSYNC flag. If a process 1588 * takes a write fault on a MAP_NOSYNC memory area the flag will 1589 * be set again. 1590 * 1591 * We set valid bits inclusive of any overlap, but we can only 1592 * clear dirty bits for DEV_BSIZE chunks that are fully within 1593 * the range. 1594 */ 1595 pagebits = vm_page_bits(base, size); 1596 m->valid |= pagebits; 1597 #if 0 /* NOT YET */ 1598 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1599 frag = DEV_BSIZE - frag; 1600 base += frag; 1601 size -= frag; 1602 if (size < 0) 1603 size = 0; 1604 } 1605 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1606 #endif 1607 m->dirty &= ~pagebits; 1608 if (base == 0 && size == PAGE_SIZE) { 1609 pmap_clear_modify(m); 1610 vm_page_flag_clear(m, PG_NOSYNC); 1611 } 1612 } 1613 1614 void 1615 vm_page_clear_dirty(vm_page_t m, int base, int size) 1616 { 1617 1618 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1619 m->dirty &= ~vm_page_bits(base, size); 1620 } 1621 1622 /* 1623 * vm_page_set_invalid: 1624 * 1625 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1626 * valid and dirty bits for the effected areas are cleared. 1627 * 1628 * May not block. 1629 */ 1630 void 1631 vm_page_set_invalid(vm_page_t m, int base, int size) 1632 { 1633 int bits; 1634 1635 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1636 bits = vm_page_bits(base, size); 1637 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1638 if (m->valid == VM_PAGE_BITS_ALL && bits != 0) 1639 pmap_remove_all(m); 1640 m->valid &= ~bits; 1641 m->dirty &= ~bits; 1642 m->object->generation++; 1643 } 1644 1645 /* 1646 * vm_page_zero_invalid() 1647 * 1648 * The kernel assumes that the invalid portions of a page contain 1649 * garbage, but such pages can be mapped into memory by user code. 1650 * When this occurs, we must zero out the non-valid portions of the 1651 * page so user code sees what it expects. 1652 * 1653 * Pages are most often semi-valid when the end of a file is mapped 1654 * into memory and the file's size is not page aligned. 1655 */ 1656 void 1657 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1658 { 1659 int b; 1660 int i; 1661 1662 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1663 /* 1664 * Scan the valid bits looking for invalid sections that 1665 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1666 * valid bit may be set ) have already been zerod by 1667 * vm_page_set_validclean(). 1668 */ 1669 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1670 if (i == (PAGE_SIZE / DEV_BSIZE) || 1671 (m->valid & (1 << i)) 1672 ) { 1673 if (i > b) { 1674 pmap_zero_page_area(m, 1675 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1676 } 1677 b = i + 1; 1678 } 1679 } 1680 1681 /* 1682 * setvalid is TRUE when we can safely set the zero'd areas 1683 * as being valid. We can do this if there are no cache consistancy 1684 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1685 */ 1686 if (setvalid) 1687 m->valid = VM_PAGE_BITS_ALL; 1688 } 1689 1690 /* 1691 * vm_page_is_valid: 1692 * 1693 * Is (partial) page valid? Note that the case where size == 0 1694 * will return FALSE in the degenerate case where the page is 1695 * entirely invalid, and TRUE otherwise. 1696 * 1697 * May not block. 1698 */ 1699 int 1700 vm_page_is_valid(vm_page_t m, int base, int size) 1701 { 1702 int bits = vm_page_bits(base, size); 1703 1704 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1705 if (m->valid && ((m->valid & bits) == bits)) 1706 return 1; 1707 else 1708 return 0; 1709 } 1710 1711 /* 1712 * update dirty bits from pmap/mmu. May not block. 1713 */ 1714 void 1715 vm_page_test_dirty(vm_page_t m) 1716 { 1717 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1718 vm_page_dirty(m); 1719 } 1720 } 1721 1722 int so_zerocp_fullpage = 0; 1723 1724 void 1725 vm_page_cowfault(vm_page_t m) 1726 { 1727 vm_page_t mnew; 1728 vm_object_t object; 1729 vm_pindex_t pindex; 1730 1731 object = m->object; 1732 pindex = m->pindex; 1733 1734 retry_alloc: 1735 pmap_remove_all(m); 1736 vm_page_remove(m); 1737 mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL); 1738 if (mnew == NULL) { 1739 vm_page_insert(m, object, pindex); 1740 vm_page_unlock_queues(); 1741 VM_OBJECT_UNLOCK(object); 1742 VM_WAIT; 1743 VM_OBJECT_LOCK(object); 1744 vm_page_lock_queues(); 1745 goto retry_alloc; 1746 } 1747 1748 if (m->cow == 0) { 1749 /* 1750 * check to see if we raced with an xmit complete when 1751 * waiting to allocate a page. If so, put things back 1752 * the way they were 1753 */ 1754 vm_page_free(mnew); 1755 vm_page_insert(m, object, pindex); 1756 } else { /* clear COW & copy page */ 1757 if (!so_zerocp_fullpage) 1758 pmap_copy_page(m, mnew); 1759 mnew->valid = VM_PAGE_BITS_ALL; 1760 vm_page_dirty(mnew); 1761 vm_page_flag_clear(mnew, PG_BUSY); 1762 mnew->wire_count = m->wire_count - m->cow; 1763 m->wire_count = m->cow; 1764 } 1765 } 1766 1767 void 1768 vm_page_cowclear(vm_page_t m) 1769 { 1770 1771 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1772 if (m->cow) { 1773 m->cow--; 1774 /* 1775 * let vm_fault add back write permission lazily 1776 */ 1777 } 1778 /* 1779 * sf_buf_free() will free the page, so we needn't do it here 1780 */ 1781 } 1782 1783 void 1784 vm_page_cowsetup(vm_page_t m) 1785 { 1786 1787 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1788 m->cow++; 1789 pmap_page_protect(m, VM_PROT_READ); 1790 } 1791 1792 #include "opt_ddb.h" 1793 #ifdef DDB 1794 #include <sys/kernel.h> 1795 1796 #include <ddb/ddb.h> 1797 1798 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1799 { 1800 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1801 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1802 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1803 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1804 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1805 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1806 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1807 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1808 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1809 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1810 } 1811 1812 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1813 { 1814 int i; 1815 db_printf("PQ_FREE:"); 1816 for (i = 0; i < PQ_NUMCOLORS; i++) { 1817 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1818 } 1819 db_printf("\n"); 1820 1821 db_printf("PQ_CACHE:"); 1822 for (i = 0; i < PQ_NUMCOLORS; i++) { 1823 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1824 } 1825 db_printf("\n"); 1826 1827 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1828 vm_page_queues[PQ_ACTIVE].lcnt, 1829 vm_page_queues[PQ_INACTIVE].lcnt); 1830 } 1831 #endif /* DDB */ 1832