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 * $FreeBSD$ 38 */ 39 40 /* 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 45 * 46 * Permission to use, copy, modify and distribute this software and 47 * its documentation is hereby granted, provided that both the copyright 48 * notice and this permission notice appear in all copies of the 49 * software, derivative works or modified versions, and any portions 50 * thereof, and that both notices appear in supporting documentation. 51 * 52 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 53 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 54 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 55 * 56 * Carnegie Mellon requests users of this software to return to 57 * 58 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 59 * School of Computer Science 60 * Carnegie Mellon University 61 * Pittsburgh PA 15213-3890 62 * 63 * any improvements or extensions that they make and grant Carnegie the 64 * rights to redistribute these changes. 65 */ 66 67 /* 68 * GENERAL RULES ON VM_PAGE MANIPULATION 69 * 70 * - a pageq mutex is required when adding or removing a page from a 71 * page queue (vm_page_queue[]), regardless of other mutexes or the 72 * busy state of a page. 73 * 74 * - a hash chain mutex is required when associating or disassociating 75 * a page from the VM PAGE CACHE hash table (vm_page_buckets), 76 * regardless of other mutexes or the busy state of a page. 77 * 78 * - either a hash chain mutex OR a busied page is required in order 79 * to modify the page flags. A hash chain mutex must be obtained in 80 * order to busy a page. A page's flags cannot be modified by a 81 * hash chain mutex if the page is marked busy. 82 * 83 * - The object memq mutex is held when inserting or removing 84 * pages from an object (vm_page_insert() or vm_page_remove()). This 85 * is different from the object's main mutex. 86 * 87 * Generally speaking, you have to be aware of side effects when running 88 * vm_page ops. A vm_page_lookup() will return with the hash chain 89 * locked, whether it was able to lookup the page or not. vm_page_free(), 90 * vm_page_cache(), vm_page_activate(), and a number of other routines 91 * will release the hash chain mutex for you. Intermediate manipulation 92 * routines such as vm_page_flag_set() expect the hash chain to be held 93 * on entry and the hash chain will remain held on return. 94 * 95 * pageq scanning can only occur with the pageq in question locked. 96 * We have a known bottleneck with the active queue, but the cache 97 * and free queues are actually arrays already. 98 */ 99 100 /* 101 * Resident memory management module. 102 */ 103 104 #include <sys/param.h> 105 #include <sys/systm.h> 106 #include <sys/lock.h> 107 #include <sys/malloc.h> 108 #include <sys/mutex.h> 109 #include <sys/proc.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 /* 125 * Associated with page of user-allocatable memory is a 126 * page structure. 127 */ 128 129 struct mtx vm_page_queue_mtx; 130 struct mtx vm_page_queue_free_mtx; 131 132 vm_page_t vm_page_array = 0; 133 int vm_page_array_size = 0; 134 long first_page = 0; 135 int vm_page_zero_count = 0; 136 137 /* 138 * vm_set_page_size: 139 * 140 * Sets the page size, perhaps based upon the memory 141 * size. Must be called before any use of page-size 142 * dependent functions. 143 */ 144 void 145 vm_set_page_size(void) 146 { 147 if (cnt.v_page_size == 0) 148 cnt.v_page_size = PAGE_SIZE; 149 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) 150 panic("vm_set_page_size: page size not a power of two"); 151 } 152 153 /* 154 * vm_page_startup: 155 * 156 * Initializes the resident memory module. 157 * 158 * Allocates memory for the page cells, and 159 * for the object/offset-to-page hash table headers. 160 * Each page cell is initialized and placed on the free list. 161 */ 162 vm_offset_t 163 vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 164 { 165 vm_offset_t mapped; 166 vm_size_t npages, page_range; 167 vm_offset_t new_end; 168 int i; 169 vm_offset_t pa; 170 int nblocks; 171 vm_offset_t last_pa; 172 173 /* the biggest memory array is the second group of pages */ 174 vm_offset_t end; 175 vm_offset_t biggestone, biggestsize; 176 177 vm_offset_t total; 178 vm_size_t bootpages; 179 180 total = 0; 181 biggestsize = 0; 182 biggestone = 0; 183 nblocks = 0; 184 vaddr = round_page(vaddr); 185 186 for (i = 0; phys_avail[i + 1]; i += 2) { 187 phys_avail[i] = round_page(phys_avail[i]); 188 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 189 } 190 191 for (i = 0; phys_avail[i + 1]; i += 2) { 192 vm_size_t size = phys_avail[i + 1] - phys_avail[i]; 193 194 if (size > biggestsize) { 195 biggestone = i; 196 biggestsize = size; 197 } 198 ++nblocks; 199 total += size; 200 } 201 202 end = phys_avail[biggestone+1]; 203 204 /* 205 * Initialize the locks. 206 */ 207 mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF); 208 mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL, 209 MTX_SPIN); 210 211 /* 212 * Initialize the queue headers for the free queue, the active queue 213 * and the inactive queue. 214 */ 215 vm_pageq_init(); 216 217 /* 218 * Allocate memory for use when boot strapping the kernel memory 219 * allocator. 220 */ 221 bootpages = UMA_BOOT_PAGES * UMA_SLAB_SIZE; 222 new_end = end - bootpages; 223 new_end = trunc_page(new_end); 224 mapped = pmap_map(&vaddr, new_end, end, 225 VM_PROT_READ | VM_PROT_WRITE); 226 bzero((caddr_t) mapped, end - new_end); 227 uma_startup((caddr_t)mapped); 228 229 /* 230 * Compute the number of pages of memory that will be available for 231 * use (taking into account the overhead of a page structure per 232 * page). 233 */ 234 first_page = phys_avail[0] / PAGE_SIZE; 235 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 236 npages = (total - (page_range * sizeof(struct vm_page)) - 237 (end - new_end)) / PAGE_SIZE; 238 end = new_end; 239 240 /* 241 * Initialize the mem entry structures now, and put them in the free 242 * queue. 243 */ 244 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 245 mapped = pmap_map(&vaddr, new_end, end, 246 VM_PROT_READ | VM_PROT_WRITE); 247 vm_page_array = (vm_page_t) mapped; 248 249 /* 250 * Clear all of the page structures 251 */ 252 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 253 vm_page_array_size = page_range; 254 255 /* 256 * Construct the free queue(s) in descending order (by physical 257 * address) so that the first 16MB of physical memory is allocated 258 * last rather than first. On large-memory machines, this avoids 259 * the exhaustion of low physical memory before isa_dmainit has run. 260 */ 261 cnt.v_page_count = 0; 262 cnt.v_free_count = 0; 263 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 264 pa = phys_avail[i]; 265 if (i == biggestone) 266 last_pa = new_end; 267 else 268 last_pa = phys_avail[i + 1]; 269 while (pa < last_pa && npages-- > 0) { 270 vm_pageq_add_new_page(pa); 271 pa += PAGE_SIZE; 272 } 273 } 274 return (vaddr); 275 } 276 277 void 278 vm_page_flag_set(vm_page_t m, unsigned short bits) 279 { 280 281 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 282 m->flags |= bits; 283 } 284 285 void 286 vm_page_flag_clear(vm_page_t m, unsigned short bits) 287 { 288 289 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 290 m->flags &= ~bits; 291 } 292 293 void 294 vm_page_busy(vm_page_t m) 295 { 296 KASSERT((m->flags & PG_BUSY) == 0, 297 ("vm_page_busy: page already busy!!!")); 298 vm_page_flag_set(m, PG_BUSY); 299 } 300 301 /* 302 * vm_page_flash: 303 * 304 * wakeup anyone waiting for the page. 305 */ 306 void 307 vm_page_flash(vm_page_t m) 308 { 309 if (m->flags & PG_WANTED) { 310 vm_page_flag_clear(m, PG_WANTED); 311 wakeup(m); 312 } 313 } 314 315 /* 316 * vm_page_wakeup: 317 * 318 * clear the PG_BUSY flag and wakeup anyone waiting for the 319 * page. 320 * 321 */ 322 void 323 vm_page_wakeup(vm_page_t m) 324 { 325 KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 326 vm_page_flag_clear(m, PG_BUSY); 327 vm_page_flash(m); 328 } 329 330 /* 331 * 332 * 333 */ 334 void 335 vm_page_io_start(vm_page_t m) 336 { 337 338 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 339 m->busy++; 340 } 341 342 void 343 vm_page_io_finish(vm_page_t m) 344 { 345 346 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 347 m->busy--; 348 if (m->busy == 0) 349 vm_page_flash(m); 350 } 351 352 /* 353 * Keep page from being freed by the page daemon 354 * much of the same effect as wiring, except much lower 355 * overhead and should be used only for *very* temporary 356 * holding ("wiring"). 357 */ 358 void 359 vm_page_hold(vm_page_t mem) 360 { 361 362 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 363 mem->hold_count++; 364 } 365 366 void 367 vm_page_unhold(vm_page_t mem) 368 { 369 370 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 371 --mem->hold_count; 372 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 373 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 374 vm_page_free_toq(mem); 375 } 376 377 /* 378 * vm_page_copy: 379 * 380 * Copy one page to another 381 */ 382 void 383 vm_page_copy(vm_page_t src_m, vm_page_t dest_m) 384 { 385 pmap_copy_page(src_m, dest_m); 386 dest_m->valid = VM_PAGE_BITS_ALL; 387 } 388 389 /* 390 * vm_page_free: 391 * 392 * Free a page 393 * 394 * The clearing of PG_ZERO is a temporary safety until the code can be 395 * reviewed to determine that PG_ZERO is being properly cleared on 396 * write faults or maps. PG_ZERO was previously cleared in 397 * vm_page_alloc(). 398 */ 399 void 400 vm_page_free(vm_page_t m) 401 { 402 vm_page_flag_clear(m, PG_ZERO); 403 vm_page_free_toq(m); 404 vm_page_zero_idle_wakeup(); 405 } 406 407 /* 408 * vm_page_free_zero: 409 * 410 * Free a page to the zerod-pages queue 411 */ 412 void 413 vm_page_free_zero(vm_page_t m) 414 { 415 vm_page_flag_set(m, PG_ZERO); 416 vm_page_free_toq(m); 417 } 418 419 /* 420 * vm_page_sleep_if_busy: 421 * 422 * Sleep and release the page queues lock if PG_BUSY is set or, 423 * if also_m_busy is TRUE, busy is non-zero. Returns TRUE if the 424 * thread slept and the page queues lock was released. 425 * Otherwise, retains the page queues lock and returns FALSE. 426 */ 427 int 428 vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg) 429 { 430 431 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 432 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 433 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 434 msleep(m, &vm_page_queue_mtx, PDROP | PVM, msg, 0); 435 return (TRUE); 436 } 437 return (FALSE); 438 } 439 440 /* 441 * vm_page_dirty: 442 * 443 * make page all dirty 444 */ 445 void 446 vm_page_dirty(vm_page_t m) 447 { 448 KASSERT(m->queue - m->pc != PQ_CACHE, 449 ("vm_page_dirty: page in cache!")); 450 m->dirty = VM_PAGE_BITS_ALL; 451 } 452 453 /* 454 * vm_page_splay: 455 * 456 * Implements Sleator and Tarjan's top-down splay algorithm. Returns 457 * the vm_page containing the given pindex. If, however, that 458 * pindex is not found in the vm_object, returns a vm_page that is 459 * adjacent to the pindex, coming before or after it. 460 */ 461 vm_page_t 462 vm_page_splay(vm_pindex_t pindex, vm_page_t root) 463 { 464 struct vm_page dummy; 465 vm_page_t lefttreemax, righttreemin, y; 466 467 if (root == NULL) 468 return (root); 469 lefttreemax = righttreemin = &dummy; 470 for (;; root = y) { 471 if (pindex < root->pindex) { 472 if ((y = root->left) == NULL) 473 break; 474 if (pindex < y->pindex) { 475 /* Rotate right. */ 476 root->left = y->right; 477 y->right = root; 478 root = y; 479 if ((y = root->left) == NULL) 480 break; 481 } 482 /* Link into the new root's right tree. */ 483 righttreemin->left = root; 484 righttreemin = root; 485 } else if (pindex > root->pindex) { 486 if ((y = root->right) == NULL) 487 break; 488 if (pindex > y->pindex) { 489 /* Rotate left. */ 490 root->right = y->left; 491 y->left = root; 492 root = y; 493 if ((y = root->right) == NULL) 494 break; 495 } 496 /* Link into the new root's left tree. */ 497 lefttreemax->right = root; 498 lefttreemax = root; 499 } else 500 break; 501 } 502 /* Assemble the new root. */ 503 lefttreemax->right = root->left; 504 righttreemin->left = root->right; 505 root->left = dummy.right; 506 root->right = dummy.left; 507 return (root); 508 } 509 510 /* 511 * vm_page_insert: [ internal use only ] 512 * 513 * Inserts the given mem entry into the object and object list. 514 * 515 * The pagetables are not updated but will presumably fault the page 516 * in if necessary, or if a kernel page the caller will at some point 517 * enter the page into the kernel's pmap. We are not allowed to block 518 * here so we *can't* do this anyway. 519 * 520 * The object and page must be locked, and must be splhigh. 521 * This routine may not block. 522 */ 523 void 524 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 525 { 526 vm_page_t root; 527 528 if (m->object != NULL) 529 panic("vm_page_insert: already inserted"); 530 531 /* 532 * Record the object/offset pair in this page 533 */ 534 m->object = object; 535 m->pindex = pindex; 536 537 mtx_assert(object == kmem_object ? &object->mtx : &Giant, MA_OWNED); 538 /* 539 * Now link into the object's ordered list of backed pages. 540 */ 541 root = object->root; 542 if (root == NULL) { 543 m->left = NULL; 544 m->right = NULL; 545 TAILQ_INSERT_TAIL(&object->memq, m, listq); 546 } else { 547 root = vm_page_splay(pindex, root); 548 if (pindex < root->pindex) { 549 m->left = root->left; 550 m->right = root; 551 root->left = NULL; 552 TAILQ_INSERT_BEFORE(root, m, listq); 553 } else { 554 m->right = root->right; 555 m->left = root; 556 root->right = NULL; 557 TAILQ_INSERT_AFTER(&object->memq, root, m, listq); 558 } 559 } 560 object->root = m; 561 object->generation++; 562 563 /* 564 * show that the object has one more resident page. 565 */ 566 object->resident_page_count++; 567 568 /* 569 * Since we are inserting a new and possibly dirty page, 570 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 571 */ 572 if (m->flags & PG_WRITEABLE) 573 vm_object_set_writeable_dirty(object); 574 } 575 576 /* 577 * vm_page_remove: 578 * NOTE: used by device pager as well -wfj 579 * 580 * Removes the given mem entry from the object/offset-page 581 * table and the object page list, but do not invalidate/terminate 582 * the backing store. 583 * 584 * The object and page must be locked, and at splhigh. 585 * The underlying pmap entry (if any) is NOT removed here. 586 * This routine may not block. 587 */ 588 void 589 vm_page_remove(vm_page_t m) 590 { 591 vm_object_t object; 592 vm_page_t root; 593 594 GIANT_REQUIRED; 595 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 596 if (m->object == NULL) 597 return; 598 599 if ((m->flags & PG_BUSY) == 0) { 600 panic("vm_page_remove: page not busy"); 601 } 602 603 /* 604 * Basically destroy the page. 605 */ 606 vm_page_wakeup(m); 607 608 object = m->object; 609 610 /* 611 * Now remove from the object's list of backed pages. 612 */ 613 if (m != object->root) 614 vm_page_splay(m->pindex, object->root); 615 if (m->left == NULL) 616 root = m->right; 617 else { 618 root = vm_page_splay(m->pindex, m->left); 619 root->right = m->right; 620 } 621 object->root = root; 622 TAILQ_REMOVE(&object->memq, m, listq); 623 624 /* 625 * And show that the object has one fewer resident page. 626 */ 627 object->resident_page_count--; 628 object->generation++; 629 630 m->object = NULL; 631 } 632 633 /* 634 * vm_page_lookup: 635 * 636 * Returns the page associated with the object/offset 637 * pair specified; if none is found, NULL is returned. 638 * 639 * The object must be locked. 640 * This routine may not block. 641 * This is a critical path routine 642 */ 643 vm_page_t 644 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 645 { 646 vm_page_t m; 647 648 mtx_assert(object == kmem_object ? &object->mtx : &Giant, MA_OWNED); 649 m = vm_page_splay(pindex, object->root); 650 if ((object->root = m) != NULL && m->pindex != pindex) 651 m = NULL; 652 return (m); 653 } 654 655 /* 656 * vm_page_rename: 657 * 658 * Move the given memory entry from its 659 * current object to the specified target object/offset. 660 * 661 * The object must be locked. 662 * This routine may not block. 663 * 664 * Note: this routine will raise itself to splvm(), the caller need not. 665 * 666 * Note: swap associated with the page must be invalidated by the move. We 667 * have to do this for several reasons: (1) we aren't freeing the 668 * page, (2) we are dirtying the page, (3) the VM system is probably 669 * moving the page from object A to B, and will then later move 670 * the backing store from A to B and we can't have a conflict. 671 * 672 * Note: we *always* dirty the page. It is necessary both for the 673 * fact that we moved it, and because we may be invalidating 674 * swap. If the page is on the cache, we have to deactivate it 675 * or vm_page_dirty() will panic. Dirty pages are not allowed 676 * on the cache. 677 */ 678 void 679 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 680 { 681 int s; 682 683 s = splvm(); 684 vm_page_remove(m); 685 vm_page_insert(m, new_object, new_pindex); 686 if (m->queue - m->pc == PQ_CACHE) 687 vm_page_deactivate(m); 688 vm_page_dirty(m); 689 splx(s); 690 } 691 692 /* 693 * vm_page_select_cache: 694 * 695 * Find a page on the cache queue with color optimization. As pages 696 * might be found, but not applicable, they are deactivated. This 697 * keeps us from using potentially busy cached pages. 698 * 699 * This routine must be called at splvm(). 700 * This routine may not block. 701 */ 702 static vm_page_t 703 vm_page_select_cache(vm_pindex_t color) 704 { 705 vm_page_t m; 706 707 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 708 while (TRUE) { 709 m = vm_pageq_find(PQ_CACHE, color & PQ_L2_MASK, FALSE); 710 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 711 m->hold_count || m->wire_count)) { 712 vm_page_deactivate(m); 713 continue; 714 } 715 return m; 716 } 717 } 718 719 /* 720 * vm_page_select_free: 721 * 722 * Find a free or zero page, with specified preference. 723 * 724 * This routine must be called at splvm(). 725 * This routine may not block. 726 */ 727 static __inline vm_page_t 728 vm_page_select_free(vm_pindex_t color, boolean_t prefer_zero) 729 { 730 vm_page_t m; 731 732 m = vm_pageq_find(PQ_FREE, color & PQ_L2_MASK, prefer_zero); 733 return (m); 734 } 735 736 /* 737 * vm_page_alloc: 738 * 739 * Allocate and return a memory cell associated 740 * with this VM object/offset pair. 741 * 742 * page_req classes: 743 * VM_ALLOC_NORMAL normal process request 744 * VM_ALLOC_SYSTEM system *really* needs a page 745 * VM_ALLOC_INTERRUPT interrupt time request 746 * VM_ALLOC_ZERO zero page 747 * 748 * This routine may not block. 749 * 750 * Additional special handling is required when called from an 751 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 752 * the page cache in this case. 753 */ 754 vm_page_t 755 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) 756 { 757 vm_page_t m = NULL; 758 vm_pindex_t color; 759 int flags, page_req, s; 760 761 page_req = req & VM_ALLOC_CLASS_MASK; 762 763 if ((req & VM_ALLOC_NOOBJ) == 0) { 764 KASSERT(object != NULL, 765 ("vm_page_alloc: NULL object.")); 766 mtx_assert(object == kmem_object ? &object->mtx : &Giant, 767 MA_OWNED); 768 KASSERT(!vm_page_lookup(object, pindex), 769 ("vm_page_alloc: page already allocated")); 770 color = pindex + object->pg_color; 771 } else 772 color = pindex; 773 774 /* 775 * The pager is allowed to eat deeper into the free page list. 776 */ 777 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 778 page_req = VM_ALLOC_SYSTEM; 779 }; 780 781 s = splvm(); 782 loop: 783 mtx_lock_spin(&vm_page_queue_free_mtx); 784 if (cnt.v_free_count > cnt.v_free_reserved || 785 (page_req == VM_ALLOC_SYSTEM && 786 cnt.v_cache_count == 0 && 787 cnt.v_free_count > cnt.v_interrupt_free_min) || 788 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0)) { 789 /* 790 * Allocate from the free queue if the number of free pages 791 * exceeds the minimum for the request class. 792 */ 793 m = vm_page_select_free(color, (req & VM_ALLOC_ZERO) != 0); 794 } else if (page_req != VM_ALLOC_INTERRUPT) { 795 mtx_unlock_spin(&vm_page_queue_free_mtx); 796 /* 797 * Allocatable from cache (non-interrupt only). On success, 798 * we must free the page and try again, thus ensuring that 799 * cnt.v_*_free_min counters are replenished. 800 */ 801 vm_page_lock_queues(); 802 if ((m = vm_page_select_cache(color)) == NULL) { 803 vm_page_unlock_queues(); 804 splx(s); 805 #if defined(DIAGNOSTIC) 806 if (cnt.v_cache_count > 0) 807 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", cnt.v_cache_count); 808 #endif 809 atomic_add_int(&vm_pageout_deficit, 1); 810 pagedaemon_wakeup(); 811 return (NULL); 812 } 813 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 814 vm_page_busy(m); 815 pmap_remove_all(m); 816 vm_page_free(m); 817 vm_page_unlock_queues(); 818 goto loop; 819 } else { 820 /* 821 * Not allocatable from cache from interrupt, give up. 822 */ 823 mtx_unlock_spin(&vm_page_queue_free_mtx); 824 splx(s); 825 atomic_add_int(&vm_pageout_deficit, 1); 826 pagedaemon_wakeup(); 827 return (NULL); 828 } 829 830 /* 831 * At this point we had better have found a good page. 832 */ 833 834 KASSERT( 835 m != NULL, 836 ("vm_page_alloc(): missing page on free queue\n") 837 ); 838 839 /* 840 * Remove from free queue 841 */ 842 843 vm_pageq_remove_nowakeup(m); 844 845 /* 846 * Initialize structure. Only the PG_ZERO flag is inherited. 847 */ 848 flags = PG_BUSY; 849 if (m->flags & PG_ZERO) { 850 vm_page_zero_count--; 851 if (req & VM_ALLOC_ZERO) 852 flags = PG_ZERO | PG_BUSY; 853 } 854 m->flags = flags; 855 if (req & VM_ALLOC_WIRED) { 856 atomic_add_int(&cnt.v_wire_count, 1); 857 m->wire_count = 1; 858 } else 859 m->wire_count = 0; 860 m->hold_count = 0; 861 m->act_count = 0; 862 m->busy = 0; 863 m->valid = 0; 864 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 865 mtx_unlock_spin(&vm_page_queue_free_mtx); 866 867 /* 868 * vm_page_insert() is safe prior to the splx(). Note also that 869 * inserting a page here does not insert it into the pmap (which 870 * could cause us to block allocating memory). We cannot block 871 * anywhere. 872 */ 873 if ((req & VM_ALLOC_NOOBJ) == 0) 874 vm_page_insert(m, object, pindex); 875 876 /* 877 * Don't wakeup too often - wakeup the pageout daemon when 878 * we would be nearly out of memory. 879 */ 880 if (vm_paging_needed()) 881 pagedaemon_wakeup(); 882 883 splx(s); 884 return (m); 885 } 886 887 /* 888 * vm_wait: (also see VM_WAIT macro) 889 * 890 * Block until free pages are available for allocation 891 * - Called in various places before memory allocations. 892 */ 893 void 894 vm_wait(void) 895 { 896 int s; 897 898 s = splvm(); 899 vm_page_lock_queues(); 900 if (curproc == pageproc) { 901 vm_pageout_pages_needed = 1; 902 msleep(&vm_pageout_pages_needed, &vm_page_queue_mtx, 903 PDROP | PSWP, "VMWait", 0); 904 } else { 905 if (!vm_pages_needed) { 906 vm_pages_needed = 1; 907 wakeup(&vm_pages_needed); 908 } 909 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PVM, 910 "vmwait", 0); 911 } 912 splx(s); 913 } 914 915 /* 916 * vm_waitpfault: (also see VM_WAITPFAULT macro) 917 * 918 * Block until free pages are available for allocation 919 * - Called only in vm_fault so that processes page faulting 920 * can be easily tracked. 921 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 922 * processes will be able to grab memory first. Do not change 923 * this balance without careful testing first. 924 */ 925 void 926 vm_waitpfault(void) 927 { 928 int s; 929 930 s = splvm(); 931 vm_page_lock_queues(); 932 if (!vm_pages_needed) { 933 vm_pages_needed = 1; 934 wakeup(&vm_pages_needed); 935 } 936 msleep(&cnt.v_free_count, &vm_page_queue_mtx, PDROP | PUSER, 937 "pfault", 0); 938 splx(s); 939 } 940 941 /* 942 * vm_page_activate: 943 * 944 * Put the specified page on the active list (if appropriate). 945 * Ensure that act_count is at least ACT_INIT but do not otherwise 946 * mess with it. 947 * 948 * The page queues must be locked. 949 * This routine may not block. 950 */ 951 void 952 vm_page_activate(vm_page_t m) 953 { 954 int s; 955 956 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 957 s = splvm(); 958 if (m->queue != PQ_ACTIVE) { 959 if ((m->queue - m->pc) == PQ_CACHE) 960 cnt.v_reactivated++; 961 vm_pageq_remove(m); 962 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 963 if (m->act_count < ACT_INIT) 964 m->act_count = ACT_INIT; 965 vm_pageq_enqueue(PQ_ACTIVE, m); 966 } 967 } else { 968 if (m->act_count < ACT_INIT) 969 m->act_count = ACT_INIT; 970 } 971 splx(s); 972 } 973 974 /* 975 * vm_page_free_wakeup: 976 * 977 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 978 * routine is called when a page has been added to the cache or free 979 * queues. 980 * 981 * This routine may not block. 982 * This routine must be called at splvm() 983 */ 984 static __inline void 985 vm_page_free_wakeup(void) 986 { 987 988 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 989 /* 990 * if pageout daemon needs pages, then tell it that there are 991 * some free. 992 */ 993 if (vm_pageout_pages_needed && 994 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 995 wakeup(&vm_pageout_pages_needed); 996 vm_pageout_pages_needed = 0; 997 } 998 /* 999 * wakeup processes that are waiting on memory if we hit a 1000 * high water mark. And wakeup scheduler process if we have 1001 * lots of memory. this process will swapin processes. 1002 */ 1003 if (vm_pages_needed && !vm_page_count_min()) { 1004 vm_pages_needed = 0; 1005 wakeup(&cnt.v_free_count); 1006 } 1007 } 1008 1009 /* 1010 * vm_page_free_toq: 1011 * 1012 * Returns the given page to the PQ_FREE list, 1013 * disassociating it with any VM object. 1014 * 1015 * Object and page must be locked prior to entry. 1016 * This routine may not block. 1017 */ 1018 1019 void 1020 vm_page_free_toq(vm_page_t m) 1021 { 1022 int s; 1023 struct vpgqueues *pq; 1024 vm_object_t object = m->object; 1025 1026 GIANT_REQUIRED; 1027 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1028 s = splvm(); 1029 cnt.v_tfree++; 1030 1031 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1032 printf( 1033 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1034 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1035 m->hold_count); 1036 if ((m->queue - m->pc) == PQ_FREE) 1037 panic("vm_page_free: freeing free page"); 1038 else 1039 panic("vm_page_free: freeing busy page"); 1040 } 1041 1042 /* 1043 * unqueue, then remove page. Note that we cannot destroy 1044 * the page here because we do not want to call the pager's 1045 * callback routine until after we've put the page on the 1046 * appropriate free queue. 1047 */ 1048 vm_pageq_remove_nowakeup(m); 1049 vm_page_remove(m); 1050 1051 /* 1052 * If fictitious remove object association and 1053 * return, otherwise delay object association removal. 1054 */ 1055 if ((m->flags & PG_FICTITIOUS) != 0) { 1056 splx(s); 1057 return; 1058 } 1059 1060 m->valid = 0; 1061 vm_page_undirty(m); 1062 1063 if (m->wire_count != 0) { 1064 if (m->wire_count > 1) { 1065 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1066 m->wire_count, (long)m->pindex); 1067 } 1068 panic("vm_page_free: freeing wired page\n"); 1069 } 1070 1071 /* 1072 * If we've exhausted the object's resident pages we want to free 1073 * it up. 1074 */ 1075 if (object && 1076 (object->type == OBJT_VNODE) && 1077 ((object->flags & OBJ_DEAD) == 0) 1078 ) { 1079 struct vnode *vp = (struct vnode *)object->handle; 1080 1081 if (vp) { 1082 VI_LOCK(vp); 1083 if (VSHOULDFREE(vp)) 1084 vfree(vp); 1085 VI_UNLOCK(vp); 1086 } 1087 } 1088 1089 /* 1090 * Clear the UNMANAGED flag when freeing an unmanaged page. 1091 */ 1092 if (m->flags & PG_UNMANAGED) { 1093 m->flags &= ~PG_UNMANAGED; 1094 } else { 1095 #ifdef __alpha__ 1096 pmap_page_is_free(m); 1097 #endif 1098 } 1099 1100 if (m->hold_count != 0) { 1101 m->flags &= ~PG_ZERO; 1102 m->queue = PQ_HOLD; 1103 } else 1104 m->queue = PQ_FREE + m->pc; 1105 pq = &vm_page_queues[m->queue]; 1106 mtx_lock_spin(&vm_page_queue_free_mtx); 1107 pq->lcnt++; 1108 ++(*pq->cnt); 1109 1110 /* 1111 * Put zero'd pages on the end ( where we look for zero'd pages 1112 * first ) and non-zerod pages at the head. 1113 */ 1114 if (m->flags & PG_ZERO) { 1115 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1116 ++vm_page_zero_count; 1117 } else { 1118 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1119 } 1120 mtx_unlock_spin(&vm_page_queue_free_mtx); 1121 vm_page_free_wakeup(); 1122 splx(s); 1123 } 1124 1125 /* 1126 * vm_page_unmanage: 1127 * 1128 * Prevent PV management from being done on the page. The page is 1129 * removed from the paging queues as if it were wired, and as a 1130 * consequence of no longer being managed the pageout daemon will not 1131 * touch it (since there is no way to locate the pte mappings for the 1132 * page). madvise() calls that mess with the pmap will also no longer 1133 * operate on the page. 1134 * 1135 * Beyond that the page is still reasonably 'normal'. Freeing the page 1136 * will clear the flag. 1137 * 1138 * This routine is used by OBJT_PHYS objects - objects using unswappable 1139 * physical memory as backing store rather then swap-backed memory and 1140 * will eventually be extended to support 4MB unmanaged physical 1141 * mappings. 1142 */ 1143 void 1144 vm_page_unmanage(vm_page_t m) 1145 { 1146 int s; 1147 1148 s = splvm(); 1149 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1150 if ((m->flags & PG_UNMANAGED) == 0) { 1151 if (m->wire_count == 0) 1152 vm_pageq_remove(m); 1153 } 1154 vm_page_flag_set(m, PG_UNMANAGED); 1155 splx(s); 1156 } 1157 1158 /* 1159 * vm_page_wire: 1160 * 1161 * Mark this page as wired down by yet 1162 * another map, removing it from paging queues 1163 * as necessary. 1164 * 1165 * The page queues must be locked. 1166 * This routine may not block. 1167 */ 1168 void 1169 vm_page_wire(vm_page_t m) 1170 { 1171 int s; 1172 1173 /* 1174 * Only bump the wire statistics if the page is not already wired, 1175 * and only unqueue the page if it is on some queue (if it is unmanaged 1176 * it is already off the queues). 1177 */ 1178 s = splvm(); 1179 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1180 if (m->wire_count == 0) { 1181 if ((m->flags & PG_UNMANAGED) == 0) 1182 vm_pageq_remove(m); 1183 atomic_add_int(&cnt.v_wire_count, 1); 1184 } 1185 m->wire_count++; 1186 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1187 splx(s); 1188 } 1189 1190 /* 1191 * vm_page_unwire: 1192 * 1193 * Release one wiring of this page, potentially 1194 * enabling it to be paged again. 1195 * 1196 * Many pages placed on the inactive queue should actually go 1197 * into the cache, but it is difficult to figure out which. What 1198 * we do instead, if the inactive target is well met, is to put 1199 * clean pages at the head of the inactive queue instead of the tail. 1200 * This will cause them to be moved to the cache more quickly and 1201 * if not actively re-referenced, freed more quickly. If we just 1202 * stick these pages at the end of the inactive queue, heavy filesystem 1203 * meta-data accesses can cause an unnecessary paging load on memory bound 1204 * processes. This optimization causes one-time-use metadata to be 1205 * reused more quickly. 1206 * 1207 * BUT, if we are in a low-memory situation we have no choice but to 1208 * put clean pages on the cache queue. 1209 * 1210 * A number of routines use vm_page_unwire() to guarantee that the page 1211 * will go into either the inactive or active queues, and will NEVER 1212 * be placed in the cache - for example, just after dirtying a page. 1213 * dirty pages in the cache are not allowed. 1214 * 1215 * The page queues must be locked. 1216 * This routine may not block. 1217 */ 1218 void 1219 vm_page_unwire(vm_page_t m, int activate) 1220 { 1221 int s; 1222 1223 s = splvm(); 1224 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1225 if (m->wire_count > 0) { 1226 m->wire_count--; 1227 if (m->wire_count == 0) { 1228 atomic_subtract_int(&cnt.v_wire_count, 1); 1229 if (m->flags & PG_UNMANAGED) { 1230 ; 1231 } else if (activate) 1232 vm_pageq_enqueue(PQ_ACTIVE, m); 1233 else { 1234 vm_page_flag_clear(m, PG_WINATCFLS); 1235 vm_pageq_enqueue(PQ_INACTIVE, m); 1236 } 1237 } 1238 } else { 1239 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1240 } 1241 splx(s); 1242 } 1243 1244 1245 /* 1246 * Move the specified page to the inactive queue. If the page has 1247 * any associated swap, the swap is deallocated. 1248 * 1249 * Normally athead is 0 resulting in LRU operation. athead is set 1250 * to 1 if we want this page to be 'as if it were placed in the cache', 1251 * except without unmapping it from the process address space. 1252 * 1253 * This routine may not block. 1254 */ 1255 static __inline void 1256 _vm_page_deactivate(vm_page_t m, int athead) 1257 { 1258 int s; 1259 1260 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1261 /* 1262 * Ignore if already inactive. 1263 */ 1264 if (m->queue == PQ_INACTIVE) 1265 return; 1266 1267 s = splvm(); 1268 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1269 if ((m->queue - m->pc) == PQ_CACHE) 1270 cnt.v_reactivated++; 1271 vm_page_flag_clear(m, PG_WINATCFLS); 1272 vm_pageq_remove(m); 1273 if (athead) 1274 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1275 else 1276 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1277 m->queue = PQ_INACTIVE; 1278 vm_page_queues[PQ_INACTIVE].lcnt++; 1279 cnt.v_inactive_count++; 1280 } 1281 splx(s); 1282 } 1283 1284 void 1285 vm_page_deactivate(vm_page_t m) 1286 { 1287 _vm_page_deactivate(m, 0); 1288 } 1289 1290 /* 1291 * vm_page_try_to_cache: 1292 * 1293 * Returns 0 on failure, 1 on success 1294 */ 1295 int 1296 vm_page_try_to_cache(vm_page_t m) 1297 { 1298 1299 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1300 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1301 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1302 return (0); 1303 } 1304 vm_page_test_dirty(m); 1305 if (m->dirty) 1306 return (0); 1307 vm_page_cache(m); 1308 return (1); 1309 } 1310 1311 /* 1312 * vm_page_try_to_free() 1313 * 1314 * Attempt to free the page. If we cannot free it, we do nothing. 1315 * 1 is returned on success, 0 on failure. 1316 */ 1317 int 1318 vm_page_try_to_free(vm_page_t m) 1319 { 1320 1321 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1322 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1323 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1324 return (0); 1325 } 1326 vm_page_test_dirty(m); 1327 if (m->dirty) 1328 return (0); 1329 vm_page_busy(m); 1330 pmap_remove_all(m); 1331 vm_page_free(m); 1332 return (1); 1333 } 1334 1335 /* 1336 * vm_page_cache 1337 * 1338 * Put the specified page onto the page cache queue (if appropriate). 1339 * 1340 * This routine may not block. 1341 */ 1342 void 1343 vm_page_cache(vm_page_t m) 1344 { 1345 int s; 1346 1347 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1348 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || m->wire_count) { 1349 printf("vm_page_cache: attempting to cache busy page\n"); 1350 return; 1351 } 1352 if ((m->queue - m->pc) == PQ_CACHE) 1353 return; 1354 1355 /* 1356 * Remove all pmaps and indicate that the page is not 1357 * writeable or mapped. 1358 */ 1359 pmap_remove_all(m); 1360 if (m->dirty != 0) { 1361 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1362 (long)m->pindex); 1363 } 1364 s = splvm(); 1365 vm_pageq_remove_nowakeup(m); 1366 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1367 vm_page_free_wakeup(); 1368 splx(s); 1369 } 1370 1371 /* 1372 * vm_page_dontneed 1373 * 1374 * Cache, deactivate, or do nothing as appropriate. This routine 1375 * is typically used by madvise() MADV_DONTNEED. 1376 * 1377 * Generally speaking we want to move the page into the cache so 1378 * it gets reused quickly. However, this can result in a silly syndrome 1379 * due to the page recycling too quickly. Small objects will not be 1380 * fully cached. On the otherhand, if we move the page to the inactive 1381 * queue we wind up with a problem whereby very large objects 1382 * unnecessarily blow away our inactive and cache queues. 1383 * 1384 * The solution is to move the pages based on a fixed weighting. We 1385 * either leave them alone, deactivate them, or move them to the cache, 1386 * where moving them to the cache has the highest weighting. 1387 * By forcing some pages into other queues we eventually force the 1388 * system to balance the queues, potentially recovering other unrelated 1389 * space from active. The idea is to not force this to happen too 1390 * often. 1391 */ 1392 void 1393 vm_page_dontneed(vm_page_t m) 1394 { 1395 static int dnweight; 1396 int dnw; 1397 int head; 1398 1399 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1400 dnw = ++dnweight; 1401 1402 /* 1403 * occassionally leave the page alone 1404 */ 1405 if ((dnw & 0x01F0) == 0 || 1406 m->queue == PQ_INACTIVE || 1407 m->queue - m->pc == PQ_CACHE 1408 ) { 1409 if (m->act_count >= ACT_INIT) 1410 --m->act_count; 1411 return; 1412 } 1413 1414 if (m->dirty == 0) 1415 vm_page_test_dirty(m); 1416 1417 if (m->dirty || (dnw & 0x0070) == 0) { 1418 /* 1419 * Deactivate the page 3 times out of 32. 1420 */ 1421 head = 0; 1422 } else { 1423 /* 1424 * Cache the page 28 times out of every 32. Note that 1425 * the page is deactivated instead of cached, but placed 1426 * at the head of the queue instead of the tail. 1427 */ 1428 head = 1; 1429 } 1430 _vm_page_deactivate(m, head); 1431 } 1432 1433 /* 1434 * Grab a page, waiting until we are waken up due to the page 1435 * changing state. We keep on waiting, if the page continues 1436 * to be in the object. If the page doesn't exist, allocate it. 1437 * 1438 * This routine may block. 1439 */ 1440 vm_page_t 1441 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1442 { 1443 vm_page_t m; 1444 int s, generation; 1445 1446 GIANT_REQUIRED; 1447 retrylookup: 1448 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1449 vm_page_lock_queues(); 1450 if (m->busy || (m->flags & PG_BUSY)) { 1451 generation = object->generation; 1452 1453 s = splvm(); 1454 while ((object->generation == generation) && 1455 (m->busy || (m->flags & PG_BUSY))) { 1456 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1457 msleep(m, &vm_page_queue_mtx, PVM, "pgrbwt", 0); 1458 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1459 vm_page_unlock_queues(); 1460 splx(s); 1461 return NULL; 1462 } 1463 } 1464 vm_page_unlock_queues(); 1465 splx(s); 1466 goto retrylookup; 1467 } else { 1468 if (allocflags & VM_ALLOC_WIRED) 1469 vm_page_wire(m); 1470 vm_page_busy(m); 1471 vm_page_unlock_queues(); 1472 return m; 1473 } 1474 } 1475 1476 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1477 if (m == NULL) { 1478 VM_WAIT; 1479 if ((allocflags & VM_ALLOC_RETRY) == 0) 1480 return NULL; 1481 goto retrylookup; 1482 } 1483 1484 return m; 1485 } 1486 1487 /* 1488 * Mapping function for valid bits or for dirty bits in 1489 * a page. May not block. 1490 * 1491 * Inputs are required to range within a page. 1492 */ 1493 __inline int 1494 vm_page_bits(int base, int size) 1495 { 1496 int first_bit; 1497 int last_bit; 1498 1499 KASSERT( 1500 base + size <= PAGE_SIZE, 1501 ("vm_page_bits: illegal base/size %d/%d", base, size) 1502 ); 1503 1504 if (size == 0) /* handle degenerate case */ 1505 return (0); 1506 1507 first_bit = base >> DEV_BSHIFT; 1508 last_bit = (base + size - 1) >> DEV_BSHIFT; 1509 1510 return ((2 << last_bit) - (1 << first_bit)); 1511 } 1512 1513 /* 1514 * vm_page_set_validclean: 1515 * 1516 * Sets portions of a page valid and clean. The arguments are expected 1517 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1518 * of any partial chunks touched by the range. The invalid portion of 1519 * such chunks will be zero'd. 1520 * 1521 * This routine may not block. 1522 * 1523 * (base + size) must be less then or equal to PAGE_SIZE. 1524 */ 1525 void 1526 vm_page_set_validclean(vm_page_t m, int base, int size) 1527 { 1528 int pagebits; 1529 int frag; 1530 int endoff; 1531 1532 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1533 if (size == 0) /* handle degenerate case */ 1534 return; 1535 1536 /* 1537 * If the base is not DEV_BSIZE aligned and the valid 1538 * bit is clear, we have to zero out a portion of the 1539 * first block. 1540 */ 1541 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1542 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1543 pmap_zero_page_area(m, frag, base - frag); 1544 1545 /* 1546 * If the ending offset is not DEV_BSIZE aligned and the 1547 * valid bit is clear, we have to zero out a portion of 1548 * the last block. 1549 */ 1550 endoff = base + size; 1551 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1552 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1553 pmap_zero_page_area(m, endoff, 1554 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1555 1556 /* 1557 * Set valid, clear dirty bits. If validating the entire 1558 * page we can safely clear the pmap modify bit. We also 1559 * use this opportunity to clear the PG_NOSYNC flag. If a process 1560 * takes a write fault on a MAP_NOSYNC memory area the flag will 1561 * be set again. 1562 * 1563 * We set valid bits inclusive of any overlap, but we can only 1564 * clear dirty bits for DEV_BSIZE chunks that are fully within 1565 * the range. 1566 */ 1567 pagebits = vm_page_bits(base, size); 1568 m->valid |= pagebits; 1569 #if 0 /* NOT YET */ 1570 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1571 frag = DEV_BSIZE - frag; 1572 base += frag; 1573 size -= frag; 1574 if (size < 0) 1575 size = 0; 1576 } 1577 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1578 #endif 1579 m->dirty &= ~pagebits; 1580 if (base == 0 && size == PAGE_SIZE) { 1581 pmap_clear_modify(m); 1582 vm_page_flag_clear(m, PG_NOSYNC); 1583 } 1584 } 1585 1586 #if 0 1587 1588 void 1589 vm_page_set_dirty(vm_page_t m, int base, int size) 1590 { 1591 m->dirty |= vm_page_bits(base, size); 1592 } 1593 1594 #endif 1595 1596 void 1597 vm_page_clear_dirty(vm_page_t m, int base, int size) 1598 { 1599 GIANT_REQUIRED; 1600 m->dirty &= ~vm_page_bits(base, size); 1601 } 1602 1603 /* 1604 * vm_page_set_invalid: 1605 * 1606 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1607 * valid and dirty bits for the effected areas are cleared. 1608 * 1609 * May not block. 1610 */ 1611 void 1612 vm_page_set_invalid(vm_page_t m, int base, int size) 1613 { 1614 int bits; 1615 1616 GIANT_REQUIRED; 1617 bits = vm_page_bits(base, size); 1618 m->valid &= ~bits; 1619 m->dirty &= ~bits; 1620 m->object->generation++; 1621 } 1622 1623 /* 1624 * vm_page_zero_invalid() 1625 * 1626 * The kernel assumes that the invalid portions of a page contain 1627 * garbage, but such pages can be mapped into memory by user code. 1628 * When this occurs, we must zero out the non-valid portions of the 1629 * page so user code sees what it expects. 1630 * 1631 * Pages are most often semi-valid when the end of a file is mapped 1632 * into memory and the file's size is not page aligned. 1633 */ 1634 void 1635 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1636 { 1637 int b; 1638 int i; 1639 1640 /* 1641 * Scan the valid bits looking for invalid sections that 1642 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1643 * valid bit may be set ) have already been zerod by 1644 * vm_page_set_validclean(). 1645 */ 1646 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1647 if (i == (PAGE_SIZE / DEV_BSIZE) || 1648 (m->valid & (1 << i)) 1649 ) { 1650 if (i > b) { 1651 pmap_zero_page_area(m, 1652 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1653 } 1654 b = i + 1; 1655 } 1656 } 1657 1658 /* 1659 * setvalid is TRUE when we can safely set the zero'd areas 1660 * as being valid. We can do this if there are no cache consistancy 1661 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1662 */ 1663 if (setvalid) 1664 m->valid = VM_PAGE_BITS_ALL; 1665 } 1666 1667 /* 1668 * vm_page_is_valid: 1669 * 1670 * Is (partial) page valid? Note that the case where size == 0 1671 * will return FALSE in the degenerate case where the page is 1672 * entirely invalid, and TRUE otherwise. 1673 * 1674 * May not block. 1675 */ 1676 int 1677 vm_page_is_valid(vm_page_t m, int base, int size) 1678 { 1679 int bits = vm_page_bits(base, size); 1680 1681 if (m->valid && ((m->valid & bits) == bits)) 1682 return 1; 1683 else 1684 return 0; 1685 } 1686 1687 /* 1688 * update dirty bits from pmap/mmu. May not block. 1689 */ 1690 void 1691 vm_page_test_dirty(vm_page_t m) 1692 { 1693 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1694 vm_page_dirty(m); 1695 } 1696 } 1697 1698 int so_zerocp_fullpage = 0; 1699 1700 void 1701 vm_page_cowfault(vm_page_t m) 1702 { 1703 vm_page_t mnew; 1704 vm_object_t object; 1705 vm_pindex_t pindex; 1706 1707 object = m->object; 1708 pindex = m->pindex; 1709 vm_page_busy(m); 1710 1711 retry_alloc: 1712 vm_page_remove(m); 1713 /* 1714 * An interrupt allocation is requested because the page 1715 * queues lock is held. 1716 */ 1717 mnew = vm_page_alloc(object, pindex, VM_ALLOC_INTERRUPT); 1718 if (mnew == NULL) { 1719 vm_page_insert(m, object, pindex); 1720 vm_page_unlock_queues(); 1721 VM_WAIT; 1722 vm_page_lock_queues(); 1723 goto retry_alloc; 1724 } 1725 1726 if (m->cow == 0) { 1727 /* 1728 * check to see if we raced with an xmit complete when 1729 * waiting to allocate a page. If so, put things back 1730 * the way they were 1731 */ 1732 vm_page_busy(mnew); 1733 vm_page_free(mnew); 1734 vm_page_insert(m, object, pindex); 1735 } else { /* clear COW & copy page */ 1736 if (so_zerocp_fullpage) { 1737 mnew->valid = VM_PAGE_BITS_ALL; 1738 } else { 1739 vm_page_copy(m, mnew); 1740 } 1741 vm_page_dirty(mnew); 1742 vm_page_flag_clear(mnew, PG_BUSY); 1743 } 1744 } 1745 1746 void 1747 vm_page_cowclear(vm_page_t m) 1748 { 1749 1750 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1751 if (m->cow) { 1752 m->cow--; 1753 /* 1754 * let vm_fault add back write permission lazily 1755 */ 1756 } 1757 /* 1758 * sf_buf_free() will free the page, so we needn't do it here 1759 */ 1760 } 1761 1762 void 1763 vm_page_cowsetup(vm_page_t m) 1764 { 1765 1766 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1767 m->cow++; 1768 pmap_page_protect(m, VM_PROT_READ); 1769 } 1770 1771 #include "opt_ddb.h" 1772 #ifdef DDB 1773 #include <sys/kernel.h> 1774 1775 #include <ddb/ddb.h> 1776 1777 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1778 { 1779 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1780 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1781 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1782 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1783 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1784 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1785 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1786 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1787 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1788 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1789 } 1790 1791 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1792 { 1793 int i; 1794 db_printf("PQ_FREE:"); 1795 for (i = 0; i < PQ_L2_SIZE; i++) { 1796 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1797 } 1798 db_printf("\n"); 1799 1800 db_printf("PQ_CACHE:"); 1801 for (i = 0; i < PQ_L2_SIZE; i++) { 1802 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1803 } 1804 db_printf("\n"); 1805 1806 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1807 vm_page_queues[PQ_ACTIVE].lcnt, 1808 vm_page_queues[PQ_INACTIVE].lcnt); 1809 } 1810 #endif /* DDB */ 1811