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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91 37 */ 38 39 /* 40 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 41 * All rights reserved. 42 * 43 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 44 * 45 * Permission to use, copy, modify and distribute this software and 46 * its documentation is hereby granted, provided that both the copyright 47 * notice and this permission notice appear in all copies of the 48 * software, derivative works or modified versions, and any portions 49 * thereof, and that both notices appear in supporting documentation. 50 * 51 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 52 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 53 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 54 * 55 * Carnegie Mellon requests users of this software to return to 56 * 57 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 58 * School of Computer Science 59 * Carnegie Mellon University 60 * Pittsburgh PA 15213-3890 61 * 62 * any improvements or extensions that they make and grant Carnegie the 63 * rights to redistribute these changes. 64 */ 65 66 /* 67 * GENERAL RULES ON VM_PAGE MANIPULATION 68 * 69 * - a pageq mutex is required when adding or removing a page from a 70 * page queue (vm_page_queue[]), regardless of other mutexes or the 71 * busy state of a page. 72 * 73 * - a hash chain mutex is required when associating or disassociating 74 * a page from the VM PAGE CACHE hash table (vm_page_buckets), 75 * regardless of other mutexes or the busy state of a page. 76 * 77 * - either a hash chain mutex OR a busied page is required in order 78 * to modify the page flags. A hash chain mutex must be obtained in 79 * order to busy a page. A page's flags cannot be modified by a 80 * hash chain mutex if the page is marked busy. 81 * 82 * - The object memq mutex is held when inserting or removing 83 * pages from an object (vm_page_insert() or vm_page_remove()). This 84 * is different from the object's main mutex. 85 * 86 * Generally speaking, you have to be aware of side effects when running 87 * vm_page ops. A vm_page_lookup() will return with the hash chain 88 * locked, whether it was able to lookup the page or not. vm_page_free(), 89 * vm_page_cache(), vm_page_activate(), and a number of other routines 90 * will release the hash chain mutex for you. Intermediate manipulation 91 * routines such as vm_page_flag_set() expect the hash chain to be held 92 * on entry and the hash chain will remain held on return. 93 * 94 * pageq scanning can only occur with the pageq in question locked. 95 * We have a known bottleneck with the active queue, but the cache 96 * and free queues are actually arrays already. 97 */ 98 99 /* 100 * Resident memory management module. 101 */ 102 103 #include <sys/cdefs.h> 104 __FBSDID("$FreeBSD$"); 105 106 #include <sys/param.h> 107 #include <sys/systm.h> 108 #include <sys/lock.h> 109 #include <sys/malloc.h> 110 #include <sys/mutex.h> 111 #include <sys/proc.h> 112 #include <sys/vmmeter.h> 113 #include <sys/vnode.h> 114 115 #include <vm/vm.h> 116 #include <vm/vm_param.h> 117 #include <vm/vm_kern.h> 118 #include <vm/vm_object.h> 119 #include <vm/vm_page.h> 120 #include <vm/vm_pageout.h> 121 #include <vm/vm_pager.h> 122 #include <vm/vm_extern.h> 123 #include <vm/uma.h> 124 #include <vm/uma_int.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 /* 140 * vm_set_page_size: 141 * 142 * Sets the page size, perhaps based upon the memory 143 * size. Must be called before any use of page-size 144 * dependent functions. 145 */ 146 void 147 vm_set_page_size(void) 148 { 149 if (cnt.v_page_size == 0) 150 cnt.v_page_size = PAGE_SIZE; 151 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) 152 panic("vm_set_page_size: page size not a power of two"); 153 } 154 155 /* 156 * vm_page_startup: 157 * 158 * Initializes the resident memory module. 159 * 160 * Allocates memory for the page cells, and 161 * for the object/offset-to-page hash table headers. 162 * Each page cell is initialized and placed on the free list. 163 */ 164 vm_offset_t 165 vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 166 { 167 vm_offset_t mapped; 168 vm_size_t npages; 169 vm_paddr_t page_range; 170 vm_paddr_t new_end; 171 int i; 172 vm_paddr_t pa; 173 int nblocks; 174 vm_paddr_t last_pa; 175 176 /* the biggest memory array is the second group of pages */ 177 vm_paddr_t end; 178 vm_paddr_t biggestsize; 179 int biggestone; 180 181 vm_paddr_t total; 182 vm_size_t bootpages; 183 184 total = 0; 185 biggestsize = 0; 186 biggestone = 0; 187 nblocks = 0; 188 vaddr = round_page(vaddr); 189 190 for (i = 0; phys_avail[i + 1]; i += 2) { 191 phys_avail[i] = round_page(phys_avail[i]); 192 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 193 } 194 195 for (i = 0; phys_avail[i + 1]; i += 2) { 196 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 197 198 if (size > biggestsize) { 199 biggestone = i; 200 biggestsize = size; 201 } 202 ++nblocks; 203 total += size; 204 } 205 206 end = phys_avail[biggestone+1]; 207 208 /* 209 * Initialize the locks. 210 */ 211 mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF); 212 mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL, 213 MTX_SPIN); 214 215 /* 216 * Initialize the queue headers for the free queue, the active queue 217 * and the inactive queue. 218 */ 219 vm_pageq_init(); 220 221 /* 222 * Allocate memory for use when boot strapping the kernel memory 223 * allocator. 224 */ 225 bootpages = UMA_BOOT_PAGES * UMA_SLAB_SIZE; 226 new_end = end - bootpages; 227 new_end = trunc_page(new_end); 228 mapped = pmap_map(&vaddr, new_end, end, 229 VM_PROT_READ | VM_PROT_WRITE); 230 bzero((caddr_t) mapped, end - new_end); 231 uma_startup((caddr_t)mapped); 232 233 /* 234 * Compute the number of pages of memory that will be available for 235 * use (taking into account the overhead of a page structure per 236 * page). 237 */ 238 first_page = phys_avail[0] / PAGE_SIZE; 239 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 240 npages = (total - (page_range * sizeof(struct vm_page)) - 241 (end - new_end)) / PAGE_SIZE; 242 end = new_end; 243 244 /* 245 * Initialize the mem entry structures now, and put them in the free 246 * queue. 247 */ 248 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 249 mapped = pmap_map(&vaddr, new_end, end, 250 VM_PROT_READ | VM_PROT_WRITE); 251 vm_page_array = (vm_page_t) mapped; 252 phys_avail[biggestone + 1] = new_end; 253 254 /* 255 * Clear all of the page structures 256 */ 257 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 258 vm_page_array_size = page_range; 259 260 /* 261 * Construct the free queue(s) in descending order (by physical 262 * address) so that the first 16MB of physical memory is allocated 263 * last rather than first. On large-memory machines, this avoids 264 * the exhaustion of low physical memory before isa_dmainit has run. 265 */ 266 cnt.v_page_count = 0; 267 cnt.v_free_count = 0; 268 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 269 pa = phys_avail[i]; 270 last_pa = phys_avail[i + 1]; 271 while (pa < last_pa && npages-- > 0) { 272 vm_pageq_add_new_page(pa); 273 pa += PAGE_SIZE; 274 } 275 } 276 return (vaddr); 277 } 278 279 void 280 vm_page_flag_set(vm_page_t m, unsigned short bits) 281 { 282 283 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 284 m->flags |= bits; 285 } 286 287 void 288 vm_page_flag_clear(vm_page_t m, unsigned short bits) 289 { 290 291 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 292 m->flags &= ~bits; 293 } 294 295 void 296 vm_page_busy(vm_page_t m) 297 { 298 KASSERT((m->flags & PG_BUSY) == 0, 299 ("vm_page_busy: page already busy!!!")); 300 vm_page_flag_set(m, PG_BUSY); 301 } 302 303 /* 304 * vm_page_flash: 305 * 306 * wakeup anyone waiting for the page. 307 */ 308 void 309 vm_page_flash(vm_page_t m) 310 { 311 if (m->flags & PG_WANTED) { 312 vm_page_flag_clear(m, PG_WANTED); 313 wakeup(m); 314 } 315 } 316 317 /* 318 * vm_page_wakeup: 319 * 320 * clear the PG_BUSY flag and wakeup anyone waiting for the 321 * page. 322 * 323 */ 324 void 325 vm_page_wakeup(vm_page_t m) 326 { 327 KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 328 vm_page_flag_clear(m, PG_BUSY); 329 vm_page_flash(m); 330 } 331 332 void 333 vm_page_io_start(vm_page_t m) 334 { 335 336 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 337 m->busy++; 338 } 339 340 void 341 vm_page_io_finish(vm_page_t m) 342 { 343 344 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 345 m->busy--; 346 if (m->busy == 0) 347 vm_page_flash(m); 348 } 349 350 /* 351 * Keep page from being freed by the page daemon 352 * much of the same effect as wiring, except much lower 353 * overhead and should be used only for *very* temporary 354 * holding ("wiring"). 355 */ 356 void 357 vm_page_hold(vm_page_t mem) 358 { 359 360 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 361 mem->hold_count++; 362 } 363 364 void 365 vm_page_unhold(vm_page_t mem) 366 { 367 368 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 369 --mem->hold_count; 370 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 371 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 372 vm_page_free_toq(mem); 373 } 374 375 /* 376 * vm_page_free: 377 * 378 * Free a page 379 * 380 * The clearing of PG_ZERO is a temporary safety until the code can be 381 * reviewed to determine that PG_ZERO is being properly cleared on 382 * write faults or maps. PG_ZERO was previously cleared in 383 * vm_page_alloc(). 384 */ 385 void 386 vm_page_free(vm_page_t m) 387 { 388 vm_page_flag_clear(m, PG_ZERO); 389 vm_page_free_toq(m); 390 vm_page_zero_idle_wakeup(); 391 } 392 393 /* 394 * vm_page_free_zero: 395 * 396 * Free a page to the zerod-pages queue 397 */ 398 void 399 vm_page_free_zero(vm_page_t m) 400 { 401 vm_page_flag_set(m, PG_ZERO); 402 vm_page_free_toq(m); 403 } 404 405 /* 406 * vm_page_sleep_if_busy: 407 * 408 * Sleep and release the page queues lock if PG_BUSY is set or, 409 * if also_m_busy is TRUE, busy is non-zero. Returns TRUE if the 410 * thread slept and the page queues lock was released. 411 * Otherwise, retains the page queues lock and returns FALSE. 412 */ 413 int 414 vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg) 415 { 416 int is_object_locked; 417 418 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 419 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 420 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 421 /* 422 * Remove mtx_owned() after vm_object locking is finished. 423 */ 424 if ((is_object_locked = m->object != NULL && 425 mtx_owned(&m->object->mtx))) 426 mtx_unlock(&m->object->mtx); 427 msleep(m, &vm_page_queue_mtx, PDROP | PVM, msg, 0); 428 if (is_object_locked) 429 mtx_lock(&m->object->mtx); 430 return (TRUE); 431 } 432 return (FALSE); 433 } 434 435 /* 436 * vm_page_dirty: 437 * 438 * make page all dirty 439 */ 440 void 441 vm_page_dirty(vm_page_t m) 442 { 443 KASSERT(m->queue - m->pc != PQ_CACHE, 444 ("vm_page_dirty: page in cache!")); 445 KASSERT(m->queue - m->pc != PQ_FREE, 446 ("vm_page_dirty: page is free!")); 447 m->dirty = VM_PAGE_BITS_ALL; 448 } 449 450 /* 451 * vm_page_splay: 452 * 453 * Implements Sleator and Tarjan's top-down splay algorithm. Returns 454 * the vm_page containing the given pindex. If, however, that 455 * pindex is not found in the vm_object, returns a vm_page that is 456 * adjacent to the pindex, coming before or after it. 457 */ 458 vm_page_t 459 vm_page_splay(vm_pindex_t pindex, vm_page_t root) 460 { 461 struct vm_page dummy; 462 vm_page_t lefttreemax, righttreemin, y; 463 464 if (root == NULL) 465 return (root); 466 lefttreemax = righttreemin = &dummy; 467 for (;; root = y) { 468 if (pindex < root->pindex) { 469 if ((y = root->left) == NULL) 470 break; 471 if (pindex < y->pindex) { 472 /* Rotate right. */ 473 root->left = y->right; 474 y->right = root; 475 root = y; 476 if ((y = root->left) == NULL) 477 break; 478 } 479 /* Link into the new root's right tree. */ 480 righttreemin->left = root; 481 righttreemin = root; 482 } else if (pindex > root->pindex) { 483 if ((y = root->right) == NULL) 484 break; 485 if (pindex > y->pindex) { 486 /* Rotate left. */ 487 root->right = y->left; 488 y->left = root; 489 root = y; 490 if ((y = root->right) == NULL) 491 break; 492 } 493 /* Link into the new root's left tree. */ 494 lefttreemax->right = root; 495 lefttreemax = root; 496 } else 497 break; 498 } 499 /* Assemble the new root. */ 500 lefttreemax->right = root->left; 501 righttreemin->left = root->right; 502 root->left = dummy.right; 503 root->right = dummy.left; 504 return (root); 505 } 506 507 /* 508 * vm_page_insert: [ internal use only ] 509 * 510 * Inserts the given mem entry into the object and object list. 511 * 512 * The pagetables are not updated but will presumably fault the page 513 * in if necessary, or if a kernel page the caller will at some point 514 * enter the page into the kernel's pmap. We are not allowed to block 515 * here so we *can't* do this anyway. 516 * 517 * The object and page must be locked, and must be splhigh. 518 * This routine may not block. 519 */ 520 void 521 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 522 { 523 vm_page_t root; 524 525 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 526 if (m->object != NULL) 527 panic("vm_page_insert: already inserted"); 528 529 /* 530 * Record the object/offset pair in this page 531 */ 532 m->object = object; 533 m->pindex = pindex; 534 535 /* 536 * Now link into the object's ordered list of backed pages. 537 */ 538 root = object->root; 539 if (root == NULL) { 540 m->left = NULL; 541 m->right = NULL; 542 TAILQ_INSERT_TAIL(&object->memq, m, listq); 543 } else { 544 root = vm_page_splay(pindex, root); 545 if (pindex < root->pindex) { 546 m->left = root->left; 547 m->right = root; 548 root->left = NULL; 549 TAILQ_INSERT_BEFORE(root, m, listq); 550 } else { 551 m->right = root->right; 552 m->left = root; 553 root->right = NULL; 554 TAILQ_INSERT_AFTER(&object->memq, root, m, listq); 555 } 556 } 557 object->root = m; 558 object->generation++; 559 560 /* 561 * show that the object has one more resident page. 562 */ 563 object->resident_page_count++; 564 565 /* 566 * Since we are inserting a new and possibly dirty page, 567 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 568 */ 569 if (m->flags & PG_WRITEABLE) 570 vm_object_set_writeable_dirty(object); 571 } 572 573 /* 574 * vm_page_remove: 575 * NOTE: used by device pager as well -wfj 576 * 577 * Removes the given mem entry from the object/offset-page 578 * table and the object page list, but do not invalidate/terminate 579 * the backing store. 580 * 581 * The object and page must be locked, and at splhigh. 582 * The underlying pmap entry (if any) is NOT removed here. 583 * This routine may not block. 584 */ 585 void 586 vm_page_remove(vm_page_t m) 587 { 588 vm_object_t object; 589 vm_page_t root; 590 591 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 592 if (m->object == NULL) 593 return; 594 #ifndef __alpha__ 595 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 596 #endif 597 if ((m->flags & PG_BUSY) == 0) { 598 panic("vm_page_remove: page not busy"); 599 } 600 601 /* 602 * Basically destroy the page. 603 */ 604 vm_page_wakeup(m); 605 606 object = m->object; 607 608 /* 609 * Now remove from the object's list of backed pages. 610 */ 611 if (m != object->root) 612 vm_page_splay(m->pindex, object->root); 613 if (m->left == NULL) 614 root = m->right; 615 else { 616 root = vm_page_splay(m->pindex, m->left); 617 root->right = m->right; 618 } 619 object->root = root; 620 TAILQ_REMOVE(&object->memq, m, listq); 621 622 /* 623 * And show that the object has one fewer resident page. 624 */ 625 object->resident_page_count--; 626 object->generation++; 627 628 m->object = NULL; 629 } 630 631 /* 632 * vm_page_lookup: 633 * 634 * Returns the page associated with the object/offset 635 * pair specified; if none is found, NULL is returned. 636 * 637 * The object must be locked. 638 * This routine may not block. 639 * This is a critical path routine 640 */ 641 vm_page_t 642 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 643 { 644 vm_page_t m; 645 646 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 647 m = vm_page_splay(pindex, object->root); 648 if ((object->root = m) != NULL && m->pindex != pindex) 649 m = NULL; 650 return (m); 651 } 652 653 /* 654 * vm_page_rename: 655 * 656 * Move the given memory entry from its 657 * current object to the specified target object/offset. 658 * 659 * The object must be locked. 660 * This routine may not block. 661 * 662 * Note: this routine will raise itself to splvm(), the caller need not. 663 * 664 * Note: swap associated with the page must be invalidated by the move. We 665 * have to do this for several reasons: (1) we aren't freeing the 666 * page, (2) we are dirtying the page, (3) the VM system is probably 667 * moving the page from object A to B, and will then later move 668 * the backing store from A to B and we can't have a conflict. 669 * 670 * Note: we *always* dirty the page. It is necessary both for the 671 * fact that we moved it, and because we may be invalidating 672 * swap. If the page is on the cache, we have to deactivate it 673 * or vm_page_dirty() will panic. Dirty pages are not allowed 674 * on the cache. 675 */ 676 void 677 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 678 { 679 int s; 680 681 s = splvm(); 682 vm_page_remove(m); 683 vm_page_insert(m, new_object, new_pindex); 684 if (m->queue - m->pc == PQ_CACHE) 685 vm_page_deactivate(m); 686 vm_page_dirty(m); 687 splx(s); 688 } 689 690 /* 691 * vm_page_select_cache: 692 * 693 * Find a page on the cache queue with color optimization. As pages 694 * might be found, but not applicable, they are deactivated. This 695 * keeps us from using potentially busy cached pages. 696 * 697 * This routine must be called at splvm(). 698 * This routine may not block. 699 */ 700 vm_page_t 701 vm_page_select_cache(int color) 702 { 703 vm_page_t m; 704 705 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 706 while (TRUE) { 707 m = vm_pageq_find(PQ_CACHE, color, FALSE); 708 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 709 m->hold_count || m->wire_count || 710 (!VM_OBJECT_TRYLOCK(m->object) && 711 !VM_OBJECT_LOCKED(m->object)))) { 712 vm_page_deactivate(m); 713 continue; 714 } 715 return m; 716 } 717 } 718 719 /* 720 * vm_page_alloc: 721 * 722 * Allocate and return a memory cell associated 723 * with this VM object/offset pair. 724 * 725 * page_req classes: 726 * VM_ALLOC_NORMAL normal process request 727 * VM_ALLOC_SYSTEM system *really* needs a page 728 * VM_ALLOC_INTERRUPT interrupt time request 729 * VM_ALLOC_ZERO zero page 730 * 731 * This routine may not block. 732 * 733 * Additional special handling is required when called from an 734 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 735 * the page cache in this case. 736 */ 737 vm_page_t 738 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) 739 { 740 vm_object_t m_object; 741 vm_page_t m = NULL; 742 int color, flags, page_req, s; 743 744 page_req = req & VM_ALLOC_CLASS_MASK; 745 746 if ((req & VM_ALLOC_NOOBJ) == 0) { 747 KASSERT(object != NULL, 748 ("vm_page_alloc: NULL object.")); 749 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 750 KASSERT(!vm_page_lookup(object, pindex), 751 ("vm_page_alloc: page already allocated")); 752 color = (pindex + object->pg_color) & PQ_L2_MASK; 753 } else 754 color = pindex & PQ_L2_MASK; 755 756 /* 757 * The pager is allowed to eat deeper into the free page list. 758 */ 759 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 760 page_req = VM_ALLOC_SYSTEM; 761 }; 762 763 s = splvm(); 764 loop: 765 mtx_lock_spin(&vm_page_queue_free_mtx); 766 if (cnt.v_free_count > cnt.v_free_reserved || 767 (page_req == VM_ALLOC_SYSTEM && 768 cnt.v_cache_count == 0 && 769 cnt.v_free_count > cnt.v_interrupt_free_min) || 770 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0)) { 771 /* 772 * Allocate from the free queue if the number of free pages 773 * exceeds the minimum for the request class. 774 */ 775 m = vm_pageq_find(PQ_FREE, color, (req & VM_ALLOC_ZERO) != 0); 776 } else if (page_req != VM_ALLOC_INTERRUPT) { 777 mtx_unlock_spin(&vm_page_queue_free_mtx); 778 /* 779 * Allocatable from cache (non-interrupt only). On success, 780 * we must free the page and try again, thus ensuring that 781 * cnt.v_*_free_min counters are replenished. 782 */ 783 vm_page_lock_queues(); 784 if ((m = vm_page_select_cache(color)) == NULL) { 785 vm_page_unlock_queues(); 786 splx(s); 787 #if defined(DIAGNOSTIC) 788 if (cnt.v_cache_count > 0) 789 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", cnt.v_cache_count); 790 #endif 791 atomic_add_int(&vm_pageout_deficit, 1); 792 pagedaemon_wakeup(); 793 return (NULL); 794 } 795 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 796 m_object = m->object; 797 VM_OBJECT_LOCK_ASSERT(m_object, MA_OWNED); 798 vm_page_busy(m); 799 pmap_remove_all(m); 800 vm_page_free(m); 801 vm_page_unlock_queues(); 802 if (m_object != object) 803 VM_OBJECT_UNLOCK(m_object); 804 goto loop; 805 } else { 806 /* 807 * Not allocatable from cache from interrupt, give up. 808 */ 809 mtx_unlock_spin(&vm_page_queue_free_mtx); 810 splx(s); 811 atomic_add_int(&vm_pageout_deficit, 1); 812 pagedaemon_wakeup(); 813 return (NULL); 814 } 815 816 /* 817 * At this point we had better have found a good page. 818 */ 819 820 KASSERT( 821 m != NULL, 822 ("vm_page_alloc(): missing page on free queue\n") 823 ); 824 825 /* 826 * Remove from free queue 827 */ 828 829 vm_pageq_remove_nowakeup(m); 830 831 /* 832 * Initialize structure. Only the PG_ZERO flag is inherited. 833 */ 834 flags = PG_BUSY; 835 if (m->flags & PG_ZERO) { 836 vm_page_zero_count--; 837 if (req & VM_ALLOC_ZERO) 838 flags = PG_ZERO | PG_BUSY; 839 } 840 m->flags = flags; 841 if (req & VM_ALLOC_WIRED) { 842 atomic_add_int(&cnt.v_wire_count, 1); 843 m->wire_count = 1; 844 } else 845 m->wire_count = 0; 846 m->hold_count = 0; 847 m->act_count = 0; 848 m->busy = 0; 849 m->valid = 0; 850 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 851 mtx_unlock_spin(&vm_page_queue_free_mtx); 852 853 /* 854 * vm_page_insert() is safe prior to the splx(). Note also that 855 * inserting a page here does not insert it into the pmap (which 856 * could cause us to block allocating memory). We cannot block 857 * anywhere. 858 */ 859 if ((req & VM_ALLOC_NOOBJ) == 0) 860 vm_page_insert(m, object, pindex); 861 else 862 m->pindex = pindex; 863 864 /* 865 * Don't wakeup too often - wakeup the pageout daemon when 866 * we would be nearly out of memory. 867 */ 868 if (vm_paging_needed()) 869 pagedaemon_wakeup(); 870 871 splx(s); 872 return (m); 873 } 874 875 /* 876 * vm_wait: (also see VM_WAIT macro) 877 * 878 * Block until free pages are available for allocation 879 * - Called in various places before memory allocations. 880 */ 881 void 882 vm_wait(void) 883 { 884 int s; 885 886 s = splvm(); 887 vm_page_lock_queues(); 888 if (curproc == pageproc) { 889 vm_pageout_pages_needed = 1; 890 msleep(&vm_pageout_pages_needed, &vm_page_queue_mtx, 891 PDROP | PSWP, "VMWait", 0); 892 } else { 893 if (!vm_pages_needed) { 894 vm_pages_needed = 1; 895 wakeup(&vm_pages_needed); 896 } 897 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PVM, 898 "vmwait", 0); 899 } 900 splx(s); 901 } 902 903 /* 904 * vm_waitpfault: (also see VM_WAITPFAULT macro) 905 * 906 * Block until free pages are available for allocation 907 * - Called only in vm_fault so that processes page faulting 908 * can be easily tracked. 909 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 910 * processes will be able to grab memory first. Do not change 911 * this balance without careful testing first. 912 */ 913 void 914 vm_waitpfault(void) 915 { 916 int s; 917 918 s = splvm(); 919 vm_page_lock_queues(); 920 if (!vm_pages_needed) { 921 vm_pages_needed = 1; 922 wakeup(&vm_pages_needed); 923 } 924 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PUSER, 925 "pfault", 0); 926 splx(s); 927 } 928 929 /* 930 * vm_page_activate: 931 * 932 * Put the specified page on the active list (if appropriate). 933 * Ensure that act_count is at least ACT_INIT but do not otherwise 934 * mess with it. 935 * 936 * The page queues must be locked. 937 * This routine may not block. 938 */ 939 void 940 vm_page_activate(vm_page_t m) 941 { 942 int s; 943 944 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 945 s = splvm(); 946 if (m->queue != PQ_ACTIVE) { 947 if ((m->queue - m->pc) == PQ_CACHE) 948 cnt.v_reactivated++; 949 vm_pageq_remove(m); 950 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 951 if (m->act_count < ACT_INIT) 952 m->act_count = ACT_INIT; 953 vm_pageq_enqueue(PQ_ACTIVE, m); 954 } 955 } else { 956 if (m->act_count < ACT_INIT) 957 m->act_count = ACT_INIT; 958 } 959 splx(s); 960 } 961 962 /* 963 * vm_page_free_wakeup: 964 * 965 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 966 * routine is called when a page has been added to the cache or free 967 * queues. 968 * 969 * This routine may not block. 970 * This routine must be called at splvm() 971 */ 972 static __inline void 973 vm_page_free_wakeup(void) 974 { 975 976 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 977 /* 978 * if pageout daemon needs pages, then tell it that there are 979 * some free. 980 */ 981 if (vm_pageout_pages_needed && 982 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 983 wakeup(&vm_pageout_pages_needed); 984 vm_pageout_pages_needed = 0; 985 } 986 /* 987 * wakeup processes that are waiting on memory if we hit a 988 * high water mark. And wakeup scheduler process if we have 989 * lots of memory. this process will swapin processes. 990 */ 991 if (vm_pages_needed && !vm_page_count_min()) { 992 vm_pages_needed = 0; 993 wakeup(&cnt.v_free_count); 994 } 995 } 996 997 /* 998 * vm_page_free_toq: 999 * 1000 * Returns the given page to the PQ_FREE list, 1001 * disassociating it with any VM object. 1002 * 1003 * Object and page must be locked prior to entry. 1004 * This routine may not block. 1005 */ 1006 1007 void 1008 vm_page_free_toq(vm_page_t m) 1009 { 1010 int s; 1011 struct vpgqueues *pq; 1012 vm_object_t object = m->object; 1013 1014 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1015 s = splvm(); 1016 cnt.v_tfree++; 1017 1018 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1019 printf( 1020 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1021 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1022 m->hold_count); 1023 if ((m->queue - m->pc) == PQ_FREE) 1024 panic("vm_page_free: freeing free page"); 1025 else 1026 panic("vm_page_free: freeing busy page"); 1027 } 1028 1029 /* 1030 * unqueue, then remove page. Note that we cannot destroy 1031 * the page here because we do not want to call the pager's 1032 * callback routine until after we've put the page on the 1033 * appropriate free queue. 1034 */ 1035 vm_pageq_remove_nowakeup(m); 1036 vm_page_remove(m); 1037 1038 /* 1039 * If fictitious remove object association and 1040 * return, otherwise delay object association removal. 1041 */ 1042 if ((m->flags & PG_FICTITIOUS) != 0) { 1043 splx(s); 1044 return; 1045 } 1046 1047 m->valid = 0; 1048 vm_page_undirty(m); 1049 1050 if (m->wire_count != 0) { 1051 if (m->wire_count > 1) { 1052 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1053 m->wire_count, (long)m->pindex); 1054 } 1055 panic("vm_page_free: freeing wired page\n"); 1056 } 1057 1058 /* 1059 * If we've exhausted the object's resident pages we want to free 1060 * it up. 1061 */ 1062 if (object && 1063 (object->type == OBJT_VNODE) && 1064 ((object->flags & OBJ_DEAD) == 0) 1065 ) { 1066 struct vnode *vp = (struct vnode *)object->handle; 1067 1068 if (vp) { 1069 VI_LOCK(vp); 1070 if (VSHOULDFREE(vp)) 1071 vfree(vp); 1072 VI_UNLOCK(vp); 1073 } 1074 } 1075 1076 /* 1077 * Clear the UNMANAGED flag when freeing an unmanaged page. 1078 */ 1079 if (m->flags & PG_UNMANAGED) { 1080 m->flags &= ~PG_UNMANAGED; 1081 } 1082 1083 if (m->hold_count != 0) { 1084 m->flags &= ~PG_ZERO; 1085 m->queue = PQ_HOLD; 1086 } else 1087 m->queue = PQ_FREE + m->pc; 1088 pq = &vm_page_queues[m->queue]; 1089 mtx_lock_spin(&vm_page_queue_free_mtx); 1090 pq->lcnt++; 1091 ++(*pq->cnt); 1092 1093 /* 1094 * Put zero'd pages on the end ( where we look for zero'd pages 1095 * first ) and non-zerod pages at the head. 1096 */ 1097 if (m->flags & PG_ZERO) { 1098 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1099 ++vm_page_zero_count; 1100 } else { 1101 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1102 } 1103 mtx_unlock_spin(&vm_page_queue_free_mtx); 1104 vm_page_free_wakeup(); 1105 splx(s); 1106 } 1107 1108 /* 1109 * vm_page_unmanage: 1110 * 1111 * Prevent PV management from being done on the page. The page is 1112 * removed from the paging queues as if it were wired, and as a 1113 * consequence of no longer being managed the pageout daemon will not 1114 * touch it (since there is no way to locate the pte mappings for the 1115 * page). madvise() calls that mess with the pmap will also no longer 1116 * operate on the page. 1117 * 1118 * Beyond that the page is still reasonably 'normal'. Freeing the page 1119 * will clear the flag. 1120 * 1121 * This routine is used by OBJT_PHYS objects - objects using unswappable 1122 * physical memory as backing store rather then swap-backed memory and 1123 * will eventually be extended to support 4MB unmanaged physical 1124 * mappings. 1125 */ 1126 void 1127 vm_page_unmanage(vm_page_t m) 1128 { 1129 int s; 1130 1131 s = splvm(); 1132 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1133 if ((m->flags & PG_UNMANAGED) == 0) { 1134 if (m->wire_count == 0) 1135 vm_pageq_remove(m); 1136 } 1137 vm_page_flag_set(m, PG_UNMANAGED); 1138 splx(s); 1139 } 1140 1141 /* 1142 * vm_page_wire: 1143 * 1144 * Mark this page as wired down by yet 1145 * another map, removing it from paging queues 1146 * as necessary. 1147 * 1148 * The page queues must be locked. 1149 * This routine may not block. 1150 */ 1151 void 1152 vm_page_wire(vm_page_t m) 1153 { 1154 int s; 1155 1156 /* 1157 * Only bump the wire statistics if the page is not already wired, 1158 * and only unqueue the page if it is on some queue (if it is unmanaged 1159 * it is already off the queues). 1160 */ 1161 s = splvm(); 1162 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1163 if (m->wire_count == 0) { 1164 if ((m->flags & PG_UNMANAGED) == 0) 1165 vm_pageq_remove(m); 1166 atomic_add_int(&cnt.v_wire_count, 1); 1167 } 1168 m->wire_count++; 1169 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1170 splx(s); 1171 } 1172 1173 /* 1174 * vm_page_unwire: 1175 * 1176 * Release one wiring of this page, potentially 1177 * enabling it to be paged again. 1178 * 1179 * Many pages placed on the inactive queue should actually go 1180 * into the cache, but it is difficult to figure out which. What 1181 * we do instead, if the inactive target is well met, is to put 1182 * clean pages at the head of the inactive queue instead of the tail. 1183 * This will cause them to be moved to the cache more quickly and 1184 * if not actively re-referenced, freed more quickly. If we just 1185 * stick these pages at the end of the inactive queue, heavy filesystem 1186 * meta-data accesses can cause an unnecessary paging load on memory bound 1187 * processes. This optimization causes one-time-use metadata to be 1188 * reused more quickly. 1189 * 1190 * BUT, if we are in a low-memory situation we have no choice but to 1191 * put clean pages on the cache queue. 1192 * 1193 * A number of routines use vm_page_unwire() to guarantee that the page 1194 * will go into either the inactive or active queues, and will NEVER 1195 * be placed in the cache - for example, just after dirtying a page. 1196 * dirty pages in the cache are not allowed. 1197 * 1198 * The page queues must be locked. 1199 * This routine may not block. 1200 */ 1201 void 1202 vm_page_unwire(vm_page_t m, int activate) 1203 { 1204 int s; 1205 1206 s = splvm(); 1207 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1208 if (m->wire_count > 0) { 1209 m->wire_count--; 1210 if (m->wire_count == 0) { 1211 atomic_subtract_int(&cnt.v_wire_count, 1); 1212 if (m->flags & PG_UNMANAGED) { 1213 ; 1214 } else if (activate) 1215 vm_pageq_enqueue(PQ_ACTIVE, m); 1216 else { 1217 vm_page_flag_clear(m, PG_WINATCFLS); 1218 vm_pageq_enqueue(PQ_INACTIVE, m); 1219 } 1220 } 1221 } else { 1222 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1223 } 1224 splx(s); 1225 } 1226 1227 1228 /* 1229 * Move the specified page to the inactive queue. If the page has 1230 * any associated swap, the swap is deallocated. 1231 * 1232 * Normally athead is 0 resulting in LRU operation. athead is set 1233 * to 1 if we want this page to be 'as if it were placed in the cache', 1234 * except without unmapping it from the process address space. 1235 * 1236 * This routine may not block. 1237 */ 1238 static __inline void 1239 _vm_page_deactivate(vm_page_t m, int athead) 1240 { 1241 int s; 1242 1243 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1244 /* 1245 * Ignore if already inactive. 1246 */ 1247 if (m->queue == PQ_INACTIVE) 1248 return; 1249 1250 s = splvm(); 1251 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1252 if ((m->queue - m->pc) == PQ_CACHE) 1253 cnt.v_reactivated++; 1254 vm_page_flag_clear(m, PG_WINATCFLS); 1255 vm_pageq_remove(m); 1256 if (athead) 1257 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1258 else 1259 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1260 m->queue = PQ_INACTIVE; 1261 vm_page_queues[PQ_INACTIVE].lcnt++; 1262 cnt.v_inactive_count++; 1263 } 1264 splx(s); 1265 } 1266 1267 void 1268 vm_page_deactivate(vm_page_t m) 1269 { 1270 _vm_page_deactivate(m, 0); 1271 } 1272 1273 /* 1274 * vm_page_try_to_cache: 1275 * 1276 * Returns 0 on failure, 1 on success 1277 */ 1278 int 1279 vm_page_try_to_cache(vm_page_t m) 1280 { 1281 1282 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1283 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1284 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1285 return (0); 1286 } 1287 vm_page_test_dirty(m); 1288 if (m->dirty) 1289 return (0); 1290 vm_page_cache(m); 1291 return (1); 1292 } 1293 1294 /* 1295 * vm_page_try_to_free() 1296 * 1297 * Attempt to free the page. If we cannot free it, we do nothing. 1298 * 1 is returned on success, 0 on failure. 1299 */ 1300 int 1301 vm_page_try_to_free(vm_page_t m) 1302 { 1303 1304 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1305 if (m->object != NULL) 1306 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1307 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1308 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1309 return (0); 1310 } 1311 vm_page_test_dirty(m); 1312 if (m->dirty) 1313 return (0); 1314 vm_page_busy(m); 1315 pmap_remove_all(m); 1316 vm_page_free(m); 1317 return (1); 1318 } 1319 1320 /* 1321 * vm_page_cache 1322 * 1323 * Put the specified page onto the page cache queue (if appropriate). 1324 * 1325 * This routine may not block. 1326 */ 1327 void 1328 vm_page_cache(vm_page_t m) 1329 { 1330 int s; 1331 1332 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1333 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1334 m->hold_count || m->wire_count) { 1335 printf("vm_page_cache: attempting to cache busy page\n"); 1336 return; 1337 } 1338 if ((m->queue - m->pc) == PQ_CACHE) 1339 return; 1340 1341 /* 1342 * Remove all pmaps and indicate that the page is not 1343 * writeable or mapped. 1344 */ 1345 pmap_remove_all(m); 1346 if (m->dirty != 0) { 1347 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1348 (long)m->pindex); 1349 } 1350 s = splvm(); 1351 vm_pageq_remove_nowakeup(m); 1352 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1353 vm_page_free_wakeup(); 1354 splx(s); 1355 } 1356 1357 /* 1358 * vm_page_dontneed 1359 * 1360 * Cache, deactivate, or do nothing as appropriate. This routine 1361 * is typically used by madvise() MADV_DONTNEED. 1362 * 1363 * Generally speaking we want to move the page into the cache so 1364 * it gets reused quickly. However, this can result in a silly syndrome 1365 * due to the page recycling too quickly. Small objects will not be 1366 * fully cached. On the otherhand, if we move the page to the inactive 1367 * queue we wind up with a problem whereby very large objects 1368 * unnecessarily blow away our inactive and cache queues. 1369 * 1370 * The solution is to move the pages based on a fixed weighting. We 1371 * either leave them alone, deactivate them, or move them to the cache, 1372 * where moving them to the cache has the highest weighting. 1373 * By forcing some pages into other queues we eventually force the 1374 * system to balance the queues, potentially recovering other unrelated 1375 * space from active. The idea is to not force this to happen too 1376 * often. 1377 */ 1378 void 1379 vm_page_dontneed(vm_page_t m) 1380 { 1381 static int dnweight; 1382 int dnw; 1383 int head; 1384 1385 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1386 dnw = ++dnweight; 1387 1388 /* 1389 * occassionally leave the page alone 1390 */ 1391 if ((dnw & 0x01F0) == 0 || 1392 m->queue == PQ_INACTIVE || 1393 m->queue - m->pc == PQ_CACHE 1394 ) { 1395 if (m->act_count >= ACT_INIT) 1396 --m->act_count; 1397 return; 1398 } 1399 1400 if (m->dirty == 0) 1401 vm_page_test_dirty(m); 1402 1403 if (m->dirty || (dnw & 0x0070) == 0) { 1404 /* 1405 * Deactivate the page 3 times out of 32. 1406 */ 1407 head = 0; 1408 } else { 1409 /* 1410 * Cache the page 28 times out of every 32. Note that 1411 * the page is deactivated instead of cached, but placed 1412 * at the head of the queue instead of the tail. 1413 */ 1414 head = 1; 1415 } 1416 _vm_page_deactivate(m, head); 1417 } 1418 1419 /* 1420 * Grab a page, waiting until we are waken up due to the page 1421 * changing state. We keep on waiting, if the page continues 1422 * to be in the object. If the page doesn't exist, allocate it. 1423 * 1424 * This routine may block. 1425 */ 1426 vm_page_t 1427 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1428 { 1429 vm_page_t m; 1430 int s, generation; 1431 1432 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1433 retrylookup: 1434 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1435 vm_page_lock_queues(); 1436 if (m->busy || (m->flags & PG_BUSY)) { 1437 generation = object->generation; 1438 1439 s = splvm(); 1440 while ((object->generation == generation) && 1441 (m->busy || (m->flags & PG_BUSY))) { 1442 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1443 VM_OBJECT_UNLOCK(object); 1444 msleep(m, &vm_page_queue_mtx, PDROP | PVM, "pgrbwt", 0); 1445 VM_OBJECT_LOCK(object); 1446 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1447 splx(s); 1448 return NULL; 1449 } 1450 vm_page_lock_queues(); 1451 } 1452 vm_page_unlock_queues(); 1453 splx(s); 1454 goto retrylookup; 1455 } else { 1456 if (allocflags & VM_ALLOC_WIRED) 1457 vm_page_wire(m); 1458 vm_page_busy(m); 1459 vm_page_unlock_queues(); 1460 return m; 1461 } 1462 } 1463 1464 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1465 if (m == NULL) { 1466 VM_OBJECT_UNLOCK(object); 1467 VM_WAIT; 1468 VM_OBJECT_LOCK(object); 1469 if ((allocflags & VM_ALLOC_RETRY) == 0) 1470 return NULL; 1471 goto retrylookup; 1472 } 1473 1474 return m; 1475 } 1476 1477 /* 1478 * Mapping function for valid bits or for dirty bits in 1479 * a page. May not block. 1480 * 1481 * Inputs are required to range within a page. 1482 */ 1483 __inline int 1484 vm_page_bits(int base, int size) 1485 { 1486 int first_bit; 1487 int last_bit; 1488 1489 KASSERT( 1490 base + size <= PAGE_SIZE, 1491 ("vm_page_bits: illegal base/size %d/%d", base, size) 1492 ); 1493 1494 if (size == 0) /* handle degenerate case */ 1495 return (0); 1496 1497 first_bit = base >> DEV_BSHIFT; 1498 last_bit = (base + size - 1) >> DEV_BSHIFT; 1499 1500 return ((2 << last_bit) - (1 << first_bit)); 1501 } 1502 1503 /* 1504 * vm_page_set_validclean: 1505 * 1506 * Sets portions of a page valid and clean. The arguments are expected 1507 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1508 * of any partial chunks touched by the range. The invalid portion of 1509 * such chunks will be zero'd. 1510 * 1511 * This routine may not block. 1512 * 1513 * (base + size) must be less then or equal to PAGE_SIZE. 1514 */ 1515 void 1516 vm_page_set_validclean(vm_page_t m, int base, int size) 1517 { 1518 int pagebits; 1519 int frag; 1520 int endoff; 1521 1522 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1523 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1524 if (size == 0) /* handle degenerate case */ 1525 return; 1526 1527 /* 1528 * If the base is not DEV_BSIZE aligned and the valid 1529 * bit is clear, we have to zero out a portion of the 1530 * first block. 1531 */ 1532 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1533 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1534 pmap_zero_page_area(m, frag, base - frag); 1535 1536 /* 1537 * If the ending offset is not DEV_BSIZE aligned and the 1538 * valid bit is clear, we have to zero out a portion of 1539 * the last block. 1540 */ 1541 endoff = base + size; 1542 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1543 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1544 pmap_zero_page_area(m, endoff, 1545 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1546 1547 /* 1548 * Set valid, clear dirty bits. If validating the entire 1549 * page we can safely clear the pmap modify bit. We also 1550 * use this opportunity to clear the PG_NOSYNC flag. If a process 1551 * takes a write fault on a MAP_NOSYNC memory area the flag will 1552 * be set again. 1553 * 1554 * We set valid bits inclusive of any overlap, but we can only 1555 * clear dirty bits for DEV_BSIZE chunks that are fully within 1556 * the range. 1557 */ 1558 pagebits = vm_page_bits(base, size); 1559 m->valid |= pagebits; 1560 #if 0 /* NOT YET */ 1561 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1562 frag = DEV_BSIZE - frag; 1563 base += frag; 1564 size -= frag; 1565 if (size < 0) 1566 size = 0; 1567 } 1568 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1569 #endif 1570 m->dirty &= ~pagebits; 1571 if (base == 0 && size == PAGE_SIZE) { 1572 pmap_clear_modify(m); 1573 vm_page_flag_clear(m, PG_NOSYNC); 1574 } 1575 } 1576 1577 void 1578 vm_page_clear_dirty(vm_page_t m, int base, int size) 1579 { 1580 1581 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1582 m->dirty &= ~vm_page_bits(base, size); 1583 } 1584 1585 /* 1586 * vm_page_set_invalid: 1587 * 1588 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1589 * valid and dirty bits for the effected areas are cleared. 1590 * 1591 * May not block. 1592 */ 1593 void 1594 vm_page_set_invalid(vm_page_t m, int base, int size) 1595 { 1596 int bits; 1597 1598 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1599 bits = vm_page_bits(base, size); 1600 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1601 m->valid &= ~bits; 1602 m->dirty &= ~bits; 1603 m->object->generation++; 1604 } 1605 1606 /* 1607 * vm_page_zero_invalid() 1608 * 1609 * The kernel assumes that the invalid portions of a page contain 1610 * garbage, but such pages can be mapped into memory by user code. 1611 * When this occurs, we must zero out the non-valid portions of the 1612 * page so user code sees what it expects. 1613 * 1614 * Pages are most often semi-valid when the end of a file is mapped 1615 * into memory and the file's size is not page aligned. 1616 */ 1617 void 1618 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1619 { 1620 int b; 1621 int i; 1622 1623 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1624 /* 1625 * Scan the valid bits looking for invalid sections that 1626 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1627 * valid bit may be set ) have already been zerod by 1628 * vm_page_set_validclean(). 1629 */ 1630 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1631 if (i == (PAGE_SIZE / DEV_BSIZE) || 1632 (m->valid & (1 << i)) 1633 ) { 1634 if (i > b) { 1635 pmap_zero_page_area(m, 1636 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1637 } 1638 b = i + 1; 1639 } 1640 } 1641 1642 /* 1643 * setvalid is TRUE when we can safely set the zero'd areas 1644 * as being valid. We can do this if there are no cache consistancy 1645 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1646 */ 1647 if (setvalid) 1648 m->valid = VM_PAGE_BITS_ALL; 1649 } 1650 1651 /* 1652 * vm_page_is_valid: 1653 * 1654 * Is (partial) page valid? Note that the case where size == 0 1655 * will return FALSE in the degenerate case where the page is 1656 * entirely invalid, and TRUE otherwise. 1657 * 1658 * May not block. 1659 */ 1660 int 1661 vm_page_is_valid(vm_page_t m, int base, int size) 1662 { 1663 int bits = vm_page_bits(base, size); 1664 1665 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1666 if (m->valid && ((m->valid & bits) == bits)) 1667 return 1; 1668 else 1669 return 0; 1670 } 1671 1672 /* 1673 * update dirty bits from pmap/mmu. May not block. 1674 */ 1675 void 1676 vm_page_test_dirty(vm_page_t m) 1677 { 1678 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1679 vm_page_dirty(m); 1680 } 1681 } 1682 1683 int so_zerocp_fullpage = 0; 1684 1685 void 1686 vm_page_cowfault(vm_page_t m) 1687 { 1688 vm_page_t mnew; 1689 vm_object_t object; 1690 vm_pindex_t pindex; 1691 1692 object = m->object; 1693 pindex = m->pindex; 1694 vm_page_busy(m); 1695 1696 retry_alloc: 1697 vm_page_remove(m); 1698 /* 1699 * An interrupt allocation is requested because the page 1700 * queues lock is held. 1701 */ 1702 mnew = vm_page_alloc(object, pindex, VM_ALLOC_INTERRUPT); 1703 if (mnew == NULL) { 1704 vm_page_insert(m, object, pindex); 1705 vm_page_unlock_queues(); 1706 VM_OBJECT_UNLOCK(object); 1707 VM_WAIT; 1708 VM_OBJECT_LOCK(object); 1709 vm_page_lock_queues(); 1710 goto retry_alloc; 1711 } 1712 1713 if (m->cow == 0) { 1714 /* 1715 * check to see if we raced with an xmit complete when 1716 * waiting to allocate a page. If so, put things back 1717 * the way they were 1718 */ 1719 vm_page_busy(mnew); 1720 vm_page_free(mnew); 1721 vm_page_insert(m, object, pindex); 1722 } else { /* clear COW & copy page */ 1723 if (!so_zerocp_fullpage) 1724 pmap_copy_page(m, mnew); 1725 mnew->valid = VM_PAGE_BITS_ALL; 1726 vm_page_dirty(mnew); 1727 vm_page_flag_clear(mnew, PG_BUSY); 1728 } 1729 } 1730 1731 void 1732 vm_page_cowclear(vm_page_t m) 1733 { 1734 1735 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1736 if (m->cow) { 1737 m->cow--; 1738 /* 1739 * let vm_fault add back write permission lazily 1740 */ 1741 } 1742 /* 1743 * sf_buf_free() will free the page, so we needn't do it here 1744 */ 1745 } 1746 1747 void 1748 vm_page_cowsetup(vm_page_t m) 1749 { 1750 1751 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1752 m->cow++; 1753 pmap_page_protect(m, VM_PROT_READ); 1754 } 1755 1756 #include "opt_ddb.h" 1757 #ifdef DDB 1758 #include <sys/kernel.h> 1759 1760 #include <ddb/ddb.h> 1761 1762 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1763 { 1764 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1765 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1766 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1767 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1768 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1769 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1770 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1771 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1772 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1773 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1774 } 1775 1776 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1777 { 1778 int i; 1779 db_printf("PQ_FREE:"); 1780 for (i = 0; i < PQ_L2_SIZE; i++) { 1781 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1782 } 1783 db_printf("\n"); 1784 1785 db_printf("PQ_CACHE:"); 1786 for (i = 0; i < PQ_L2_SIZE; i++) { 1787 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1788 } 1789 db_printf("\n"); 1790 1791 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1792 vm_page_queues[PQ_ACTIVE].lcnt, 1793 vm_page_queues[PQ_INACTIVE].lcnt); 1794 } 1795 #endif /* DDB */ 1796