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 static struct mtx vm_page_buckets_mtx; 129 static struct vm_page **vm_page_buckets; /* Array of buckets */ 130 static int vm_page_bucket_count; /* How big is array? */ 131 static int vm_page_hash_mask; /* Mask for hash function */ 132 133 struct mtx vm_page_queue_mtx; 134 struct mtx vm_page_queue_free_mtx; 135 136 vm_page_t vm_page_array = 0; 137 int vm_page_array_size = 0; 138 long first_page = 0; 139 int vm_page_zero_count = 0; 140 141 /* 142 * vm_set_page_size: 143 * 144 * Sets the page size, perhaps based upon the memory 145 * size. Must be called before any use of page-size 146 * dependent functions. 147 */ 148 void 149 vm_set_page_size(void) 150 { 151 if (cnt.v_page_size == 0) 152 cnt.v_page_size = PAGE_SIZE; 153 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) 154 panic("vm_set_page_size: page size not a power of two"); 155 } 156 157 /* 158 * vm_page_startup: 159 * 160 * Initializes the resident memory module. 161 * 162 * Allocates memory for the page cells, and 163 * for the object/offset-to-page hash table headers. 164 * Each page cell is initialized and placed on the free list. 165 */ 166 vm_offset_t 167 vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 168 { 169 vm_offset_t mapped; 170 struct vm_page **bucket; 171 vm_size_t npages, page_range; 172 vm_offset_t new_end; 173 int i; 174 vm_offset_t pa; 175 int nblocks; 176 vm_offset_t last_pa; 177 178 /* the biggest memory array is the second group of pages */ 179 vm_offset_t end; 180 vm_offset_t biggestone, biggestsize; 181 182 vm_offset_t total; 183 vm_size_t bootpages; 184 185 total = 0; 186 biggestsize = 0; 187 biggestone = 0; 188 nblocks = 0; 189 vaddr = round_page(vaddr); 190 191 for (i = 0; phys_avail[i + 1]; i += 2) { 192 phys_avail[i] = round_page(phys_avail[i]); 193 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 194 } 195 196 for (i = 0; phys_avail[i + 1]; i += 2) { 197 vm_size_t size = phys_avail[i + 1] - phys_avail[i]; 198 199 if (size > biggestsize) { 200 biggestone = i; 201 biggestsize = size; 202 } 203 ++nblocks; 204 total += size; 205 } 206 207 end = phys_avail[biggestone+1]; 208 209 /* 210 * Initialize the locks. 211 */ 212 mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF); 213 mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL, 214 MTX_SPIN); 215 216 /* 217 * Initialize the queue headers for the free queue, the active queue 218 * and the inactive queue. 219 */ 220 vm_pageq_init(); 221 222 /* 223 * Allocate memory for use when boot strapping the kernel memory 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 end = new_end; 234 235 /* 236 * Allocate (and initialize) the hash table buckets. 237 * 238 * The number of buckets MUST BE a power of 2, and the actual value is 239 * the next power of 2 greater than the number of physical pages in 240 * the system. 241 * 242 * We make the hash table approximately 2x the number of pages to 243 * reduce the chain length. This is about the same size using the 244 * singly-linked list as the 1x hash table we were using before 245 * using TAILQ but the chain length will be smaller. 246 * 247 * Note: This computation can be tweaked if desired. 248 */ 249 if (vm_page_bucket_count == 0) { 250 vm_page_bucket_count = 1; 251 while (vm_page_bucket_count < atop(total)) 252 vm_page_bucket_count <<= 1; 253 } 254 vm_page_bucket_count <<= 1; 255 vm_page_hash_mask = vm_page_bucket_count - 1; 256 257 /* 258 * Validate these addresses. 259 */ 260 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 261 new_end = trunc_page(new_end); 262 mapped = pmap_map(&vaddr, new_end, end, 263 VM_PROT_READ | VM_PROT_WRITE); 264 bzero((caddr_t) mapped, end - new_end); 265 266 mtx_init(&vm_page_buckets_mtx, "vm page buckets mutex", NULL, MTX_SPIN); 267 vm_page_buckets = (struct vm_page **)mapped; 268 bucket = vm_page_buckets; 269 for (i = 0; i < vm_page_bucket_count; i++) { 270 *bucket = NULL; 271 bucket++; 272 } 273 274 /* 275 * Compute the number of pages of memory that will be available for 276 * use (taking into account the overhead of a page structure per 277 * page). 278 */ 279 first_page = phys_avail[0] / PAGE_SIZE; 280 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 281 npages = (total - (page_range * sizeof(struct vm_page)) - 282 (end - new_end)) / PAGE_SIZE; 283 end = new_end; 284 285 /* 286 * Initialize the mem entry structures now, and put them in the free 287 * queue. 288 */ 289 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 290 mapped = pmap_map(&vaddr, new_end, end, 291 VM_PROT_READ | VM_PROT_WRITE); 292 vm_page_array = (vm_page_t) mapped; 293 294 /* 295 * Clear all of the page structures 296 */ 297 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 298 vm_page_array_size = page_range; 299 300 /* 301 * Construct the free queue(s) in descending order (by physical 302 * address) so that the first 16MB of physical memory is allocated 303 * last rather than first. On large-memory machines, this avoids 304 * the exhaustion of low physical memory before isa_dmainit has run. 305 */ 306 cnt.v_page_count = 0; 307 cnt.v_free_count = 0; 308 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 309 pa = phys_avail[i]; 310 if (i == biggestone) 311 last_pa = new_end; 312 else 313 last_pa = phys_avail[i + 1]; 314 while (pa < last_pa && npages-- > 0) { 315 vm_pageq_add_new_page(pa); 316 pa += PAGE_SIZE; 317 } 318 } 319 return (vaddr); 320 } 321 322 /* 323 * vm_page_hash: 324 * 325 * Distributes the object/offset key pair among hash buckets. 326 * 327 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 328 * This routine may not block. 329 * 330 * We try to randomize the hash based on the object to spread the pages 331 * out in the hash table without it costing us too much. 332 */ 333 static __inline int 334 vm_page_hash(vm_object_t object, vm_pindex_t pindex) 335 { 336 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 337 338 return (i & vm_page_hash_mask); 339 } 340 341 void 342 vm_page_flag_set(vm_page_t m, unsigned short bits) 343 { 344 GIANT_REQUIRED; 345 m->flags |= bits; 346 } 347 348 void 349 vm_page_flag_clear(vm_page_t m, unsigned short bits) 350 { 351 GIANT_REQUIRED; 352 m->flags &= ~bits; 353 } 354 355 void 356 vm_page_busy(vm_page_t m) 357 { 358 KASSERT((m->flags & PG_BUSY) == 0, 359 ("vm_page_busy: page already busy!!!")); 360 vm_page_flag_set(m, PG_BUSY); 361 } 362 363 /* 364 * vm_page_flash: 365 * 366 * wakeup anyone waiting for the page. 367 */ 368 void 369 vm_page_flash(vm_page_t m) 370 { 371 if (m->flags & PG_WANTED) { 372 vm_page_flag_clear(m, PG_WANTED); 373 wakeup(m); 374 } 375 } 376 377 /* 378 * vm_page_wakeup: 379 * 380 * clear the PG_BUSY flag and wakeup anyone waiting for the 381 * page. 382 * 383 */ 384 void 385 vm_page_wakeup(vm_page_t m) 386 { 387 KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 388 vm_page_flag_clear(m, PG_BUSY); 389 vm_page_flash(m); 390 } 391 392 /* 393 * 394 * 395 */ 396 void 397 vm_page_io_start(vm_page_t m) 398 { 399 400 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 401 m->busy++; 402 } 403 404 void 405 vm_page_io_finish(vm_page_t m) 406 { 407 GIANT_REQUIRED; 408 m->busy--; 409 if (m->busy == 0) 410 vm_page_flash(m); 411 } 412 413 /* 414 * Keep page from being freed by the page daemon 415 * much of the same effect as wiring, except much lower 416 * overhead and should be used only for *very* temporary 417 * holding ("wiring"). 418 */ 419 void 420 vm_page_hold(vm_page_t mem) 421 { 422 GIANT_REQUIRED; 423 mem->hold_count++; 424 } 425 426 void 427 vm_page_unhold(vm_page_t mem) 428 { 429 GIANT_REQUIRED; 430 --mem->hold_count; 431 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 432 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 433 vm_page_free_toq(mem); 434 } 435 436 /* 437 * vm_page_protect: 438 * 439 * Reduce the protection of a page. This routine never raises the 440 * protection and therefore can be safely called if the page is already 441 * at VM_PROT_NONE (it will be a NOP effectively ). 442 */ 443 void 444 vm_page_protect(vm_page_t mem, int prot) 445 { 446 if (prot == VM_PROT_NONE) { 447 if (mem->flags & (PG_WRITEABLE|PG_MAPPED)) { 448 pmap_page_protect(mem, VM_PROT_NONE); 449 vm_page_flag_clear(mem, PG_WRITEABLE|PG_MAPPED); 450 } 451 } else if ((prot == VM_PROT_READ) && (mem->flags & PG_WRITEABLE)) { 452 pmap_page_protect(mem, VM_PROT_READ); 453 vm_page_flag_clear(mem, PG_WRITEABLE); 454 } 455 } 456 /* 457 * vm_page_zero_fill: 458 * 459 * Zero-fill the specified page. 460 * Written as a standard pagein routine, to 461 * be used by the zero-fill object. 462 */ 463 boolean_t 464 vm_page_zero_fill(vm_page_t m) 465 { 466 pmap_zero_page(m); 467 return (TRUE); 468 } 469 470 /* 471 * vm_page_zero_fill_area: 472 * 473 * Like vm_page_zero_fill but only fill the specified area. 474 */ 475 boolean_t 476 vm_page_zero_fill_area(vm_page_t m, int off, int size) 477 { 478 pmap_zero_page_area(m, off, size); 479 return (TRUE); 480 } 481 482 /* 483 * vm_page_copy: 484 * 485 * Copy one page to another 486 */ 487 void 488 vm_page_copy(vm_page_t src_m, vm_page_t dest_m) 489 { 490 pmap_copy_page(src_m, dest_m); 491 dest_m->valid = VM_PAGE_BITS_ALL; 492 } 493 494 /* 495 * vm_page_free: 496 * 497 * Free a page 498 * 499 * The clearing of PG_ZERO is a temporary safety until the code can be 500 * reviewed to determine that PG_ZERO is being properly cleared on 501 * write faults or maps. PG_ZERO was previously cleared in 502 * vm_page_alloc(). 503 */ 504 void 505 vm_page_free(vm_page_t m) 506 { 507 vm_page_flag_clear(m, PG_ZERO); 508 vm_page_free_toq(m); 509 vm_page_zero_idle_wakeup(); 510 } 511 512 /* 513 * vm_page_free_zero: 514 * 515 * Free a page to the zerod-pages queue 516 */ 517 void 518 vm_page_free_zero(vm_page_t m) 519 { 520 vm_page_flag_set(m, PG_ZERO); 521 vm_page_free_toq(m); 522 } 523 524 /* 525 * vm_page_sleep_busy: 526 * 527 * Wait until page is no longer PG_BUSY or (if also_m_busy is TRUE) 528 * m->busy is zero. Returns TRUE if it had to sleep ( including if 529 * it almost had to sleep and made temporary spl*() mods), FALSE 530 * otherwise. 531 * 532 * This routine assumes that interrupts can only remove the busy 533 * status from a page, not set the busy status or change it from 534 * PG_BUSY to m->busy or vise versa (which would create a timing 535 * window). 536 */ 537 int 538 vm_page_sleep_busy(vm_page_t m, int also_m_busy, const char *msg) 539 { 540 GIANT_REQUIRED; 541 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 542 int s = splvm(); 543 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 544 /* 545 * Page is busy. Wait and retry. 546 */ 547 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 548 tsleep(m, PVM, msg, 0); 549 } 550 splx(s); 551 return (TRUE); 552 /* not reached */ 553 } 554 return (FALSE); 555 } 556 557 /* 558 * vm_page_sleep_if_busy: 559 * 560 * Sleep and release the page queues lock if PG_BUSY is set or, 561 * if also_m_busy is TRUE, busy is non-zero. Returns TRUE if the 562 * thread slept and the page queues lock was released. 563 * Otherwise, retains the page queues lock and returns FALSE. 564 */ 565 int 566 vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg) 567 { 568 569 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 570 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 571 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 572 msleep(m, &vm_page_queue_mtx, PDROP | PVM, msg, 0); 573 return (TRUE); 574 } 575 return (FALSE); 576 } 577 578 /* 579 * vm_page_dirty: 580 * 581 * make page all dirty 582 */ 583 void 584 vm_page_dirty(vm_page_t m) 585 { 586 KASSERT(m->queue - m->pc != PQ_CACHE, 587 ("vm_page_dirty: page in cache!")); 588 m->dirty = VM_PAGE_BITS_ALL; 589 } 590 591 /* 592 * vm_page_undirty: 593 * 594 * Set page to not be dirty. Note: does not clear pmap modify bits 595 */ 596 void 597 vm_page_undirty(vm_page_t m) 598 { 599 m->dirty = 0; 600 } 601 602 /* 603 * vm_page_insert: [ internal use only ] 604 * 605 * Inserts the given mem entry into the object and object list. 606 * 607 * The pagetables are not updated but will presumably fault the page 608 * in if necessary, or if a kernel page the caller will at some point 609 * enter the page into the kernel's pmap. We are not allowed to block 610 * here so we *can't* do this anyway. 611 * 612 * The object and page must be locked, and must be splhigh. 613 * This routine may not block. 614 */ 615 void 616 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 617 { 618 struct vm_page **bucket; 619 620 GIANT_REQUIRED; 621 622 if (m->object != NULL) 623 panic("vm_page_insert: already inserted"); 624 625 /* 626 * Record the object/offset pair in this page 627 */ 628 m->object = object; 629 m->pindex = pindex; 630 631 /* 632 * Insert it into the object_object/offset hash table 633 */ 634 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 635 mtx_lock_spin(&vm_page_buckets_mtx); 636 m->hnext = *bucket; 637 *bucket = m; 638 mtx_unlock_spin(&vm_page_buckets_mtx); 639 640 /* 641 * Now link into the object's list of backed pages. 642 */ 643 TAILQ_INSERT_TAIL(&object->memq, m, listq); 644 object->generation++; 645 646 /* 647 * show that the object has one more resident page. 648 */ 649 object->resident_page_count++; 650 651 /* 652 * Since we are inserting a new and possibly dirty page, 653 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 654 */ 655 if (m->flags & PG_WRITEABLE) 656 vm_object_set_writeable_dirty(object); 657 } 658 659 /* 660 * vm_page_remove: 661 * NOTE: used by device pager as well -wfj 662 * 663 * Removes the given mem entry from the object/offset-page 664 * table and the object page list, but do not invalidate/terminate 665 * the backing store. 666 * 667 * The object and page must be locked, and at splhigh. 668 * The underlying pmap entry (if any) is NOT removed here. 669 * This routine may not block. 670 */ 671 void 672 vm_page_remove(vm_page_t m) 673 { 674 vm_object_t object; 675 vm_page_t *bucket; 676 677 GIANT_REQUIRED; 678 679 if (m->object == NULL) 680 return; 681 682 if ((m->flags & PG_BUSY) == 0) { 683 panic("vm_page_remove: page not busy"); 684 } 685 686 /* 687 * Basically destroy the page. 688 */ 689 vm_page_wakeup(m); 690 691 object = m->object; 692 693 /* 694 * Remove from the object_object/offset hash table. The object 695 * must be on the hash queue, we will panic if it isn't 696 */ 697 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 698 mtx_lock_spin(&vm_page_buckets_mtx); 699 while (*bucket != m) { 700 if (*bucket == NULL) 701 panic("vm_page_remove(): page not found in hash"); 702 bucket = &(*bucket)->hnext; 703 } 704 *bucket = m->hnext; 705 m->hnext = NULL; 706 mtx_unlock_spin(&vm_page_buckets_mtx); 707 708 /* 709 * Now remove from the object's list of backed pages. 710 */ 711 TAILQ_REMOVE(&object->memq, m, listq); 712 713 /* 714 * And show that the object has one fewer resident page. 715 */ 716 object->resident_page_count--; 717 object->generation++; 718 719 m->object = NULL; 720 } 721 722 /* 723 * vm_page_lookup: 724 * 725 * Returns the page associated with the object/offset 726 * pair specified; if none is found, NULL is returned. 727 * 728 * The object must be locked. No side effects. 729 * This routine may not block. 730 * This is a critical path routine 731 */ 732 vm_page_t 733 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 734 { 735 vm_page_t m; 736 struct vm_page **bucket; 737 738 /* 739 * Search the hash table for this object/offset pair 740 */ 741 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 742 mtx_lock_spin(&vm_page_buckets_mtx); 743 for (m = *bucket; m != NULL; m = m->hnext) 744 if (m->object == object && m->pindex == pindex) 745 break; 746 mtx_unlock_spin(&vm_page_buckets_mtx); 747 return (m); 748 } 749 750 /* 751 * vm_page_rename: 752 * 753 * Move the given memory entry from its 754 * current object to the specified target object/offset. 755 * 756 * The object must be locked. 757 * This routine may not block. 758 * 759 * Note: this routine will raise itself to splvm(), the caller need not. 760 * 761 * Note: swap associated with the page must be invalidated by the move. We 762 * have to do this for several reasons: (1) we aren't freeing the 763 * page, (2) we are dirtying the page, (3) the VM system is probably 764 * moving the page from object A to B, and will then later move 765 * the backing store from A to B and we can't have a conflict. 766 * 767 * Note: we *always* dirty the page. It is necessary both for the 768 * fact that we moved it, and because we may be invalidating 769 * swap. If the page is on the cache, we have to deactivate it 770 * or vm_page_dirty() will panic. Dirty pages are not allowed 771 * on the cache. 772 */ 773 void 774 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 775 { 776 int s; 777 778 s = splvm(); 779 vm_page_lock_queues(); 780 vm_page_remove(m); 781 vm_page_insert(m, new_object, new_pindex); 782 if (m->queue - m->pc == PQ_CACHE) 783 vm_page_deactivate(m); 784 vm_page_dirty(m); 785 vm_page_unlock_queues(); 786 splx(s); 787 } 788 789 /* 790 * vm_page_select_cache: 791 * 792 * Find a page on the cache queue with color optimization. As pages 793 * might be found, but not applicable, they are deactivated. This 794 * keeps us from using potentially busy cached pages. 795 * 796 * This routine must be called at splvm(). 797 * This routine may not block. 798 */ 799 static vm_page_t 800 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 801 { 802 vm_page_t m; 803 804 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 805 while (TRUE) { 806 m = vm_pageq_find( 807 PQ_CACHE, 808 (pindex + object->pg_color) & PQ_L2_MASK, 809 FALSE 810 ); 811 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 812 m->hold_count || m->wire_count)) { 813 vm_page_deactivate(m); 814 continue; 815 } 816 return m; 817 } 818 } 819 820 /* 821 * vm_page_select_free: 822 * 823 * Find a free or zero page, with specified preference. 824 * 825 * This routine must be called at splvm(). 826 * This routine may not block. 827 */ 828 static __inline vm_page_t 829 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 830 { 831 vm_page_t m; 832 833 m = vm_pageq_find( 834 PQ_FREE, 835 (pindex + object->pg_color) & PQ_L2_MASK, 836 prefer_zero 837 ); 838 return (m); 839 } 840 841 /* 842 * vm_page_alloc: 843 * 844 * Allocate and return a memory cell associated 845 * with this VM object/offset pair. 846 * 847 * page_req classes: 848 * VM_ALLOC_NORMAL normal process request 849 * VM_ALLOC_SYSTEM system *really* needs a page 850 * VM_ALLOC_INTERRUPT interrupt time request 851 * VM_ALLOC_ZERO zero page 852 * 853 * This routine may not block. 854 * 855 * Additional special handling is required when called from an 856 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 857 * the page cache in this case. 858 */ 859 vm_page_t 860 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) 861 { 862 vm_page_t m = NULL; 863 int page_req, s; 864 865 GIANT_REQUIRED; 866 867 KASSERT(!vm_page_lookup(object, pindex), 868 ("vm_page_alloc: page already allocated")); 869 870 page_req = req & VM_ALLOC_CLASS_MASK; 871 872 /* 873 * The pager is allowed to eat deeper into the free page list. 874 */ 875 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 876 page_req = VM_ALLOC_SYSTEM; 877 }; 878 879 s = splvm(); 880 loop: 881 mtx_lock_spin(&vm_page_queue_free_mtx); 882 if (cnt.v_free_count > cnt.v_free_reserved) { 883 /* 884 * Allocate from the free queue if there are plenty of pages 885 * in it. 886 */ 887 m = vm_page_select_free(object, pindex, 888 (req & VM_ALLOC_ZERO) != 0); 889 } else if ( 890 (page_req == VM_ALLOC_SYSTEM && 891 cnt.v_cache_count == 0 && 892 cnt.v_free_count > cnt.v_interrupt_free_min) || 893 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0) 894 ) { 895 /* 896 * Interrupt or system, dig deeper into the free list. 897 */ 898 m = vm_page_select_free(object, pindex, FALSE); 899 } else if (page_req != VM_ALLOC_INTERRUPT) { 900 mtx_unlock_spin(&vm_page_queue_free_mtx); 901 /* 902 * Allocatable from cache (non-interrupt only). On success, 903 * we must free the page and try again, thus ensuring that 904 * cnt.v_*_free_min counters are replenished. 905 */ 906 vm_page_lock_queues(); 907 if ((m = vm_page_select_cache(object, pindex)) == NULL) { 908 vm_page_unlock_queues(); 909 splx(s); 910 #if defined(DIAGNOSTIC) 911 if (cnt.v_cache_count > 0) 912 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", cnt.v_cache_count); 913 #endif 914 vm_pageout_deficit++; 915 pagedaemon_wakeup(); 916 return (NULL); 917 } 918 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 919 vm_page_busy(m); 920 vm_page_protect(m, VM_PROT_NONE); 921 vm_page_free(m); 922 vm_page_unlock_queues(); 923 goto loop; 924 } else { 925 /* 926 * Not allocatable from cache from interrupt, give up. 927 */ 928 mtx_unlock_spin(&vm_page_queue_free_mtx); 929 splx(s); 930 vm_pageout_deficit++; 931 pagedaemon_wakeup(); 932 return (NULL); 933 } 934 935 /* 936 * At this point we had better have found a good page. 937 */ 938 939 KASSERT( 940 m != NULL, 941 ("vm_page_alloc(): missing page on free queue\n") 942 ); 943 944 /* 945 * Remove from free queue 946 */ 947 948 vm_pageq_remove_nowakeup(m); 949 950 /* 951 * Initialize structure. Only the PG_ZERO flag is inherited. 952 */ 953 if (m->flags & PG_ZERO) { 954 vm_page_zero_count--; 955 m->flags = PG_ZERO | PG_BUSY; 956 } else { 957 m->flags = PG_BUSY; 958 } 959 if (req & VM_ALLOC_WIRED) { 960 cnt.v_wire_count++; 961 m->flags |= PG_MAPPED; /* XXX this does not belong here */ 962 m->wire_count = 1; 963 } else 964 m->wire_count = 0; 965 m->hold_count = 0; 966 m->act_count = 0; 967 m->busy = 0; 968 m->valid = 0; 969 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 970 mtx_unlock_spin(&vm_page_queue_free_mtx); 971 972 /* 973 * vm_page_insert() is safe prior to the splx(). Note also that 974 * inserting a page here does not insert it into the pmap (which 975 * could cause us to block allocating memory). We cannot block 976 * anywhere. 977 */ 978 vm_page_insert(m, object, pindex); 979 980 /* 981 * Don't wakeup too often - wakeup the pageout daemon when 982 * we would be nearly out of memory. 983 */ 984 if (vm_paging_needed()) 985 pagedaemon_wakeup(); 986 987 splx(s); 988 return (m); 989 } 990 991 /* 992 * vm_wait: (also see VM_WAIT macro) 993 * 994 * Block until free pages are available for allocation 995 * - Called in various places before memory allocations. 996 */ 997 void 998 vm_wait(void) 999 { 1000 int s; 1001 1002 s = splvm(); 1003 if (curproc == pageproc) { 1004 vm_pageout_pages_needed = 1; 1005 tsleep(&vm_pageout_pages_needed, PSWP, "VMWait", 0); 1006 } else { 1007 if (!vm_pages_needed) { 1008 vm_pages_needed = 1; 1009 wakeup(&vm_pages_needed); 1010 } 1011 tsleep(&cnt.v_free_count, PVM, "vmwait", 0); 1012 } 1013 splx(s); 1014 } 1015 1016 /* 1017 * vm_waitpfault: (also see VM_WAITPFAULT macro) 1018 * 1019 * Block until free pages are available for allocation 1020 * - Called only in vm_fault so that processes page faulting 1021 * can be easily tracked. 1022 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 1023 * processes will be able to grab memory first. Do not change 1024 * this balance without careful testing first. 1025 */ 1026 void 1027 vm_waitpfault(void) 1028 { 1029 int s; 1030 1031 s = splvm(); 1032 if (!vm_pages_needed) { 1033 vm_pages_needed = 1; 1034 wakeup(&vm_pages_needed); 1035 } 1036 tsleep(&cnt.v_free_count, PUSER, "pfault", 0); 1037 splx(s); 1038 } 1039 1040 /* 1041 * vm_page_activate: 1042 * 1043 * Put the specified page on the active list (if appropriate). 1044 * Ensure that act_count is at least ACT_INIT but do not otherwise 1045 * mess with it. 1046 * 1047 * The page queues must be locked. 1048 * This routine may not block. 1049 */ 1050 void 1051 vm_page_activate(vm_page_t m) 1052 { 1053 int s; 1054 1055 GIANT_REQUIRED; 1056 s = splvm(); 1057 if (m->queue != PQ_ACTIVE) { 1058 if ((m->queue - m->pc) == PQ_CACHE) 1059 cnt.v_reactivated++; 1060 vm_pageq_remove(m); 1061 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1062 if (m->act_count < ACT_INIT) 1063 m->act_count = ACT_INIT; 1064 vm_pageq_enqueue(PQ_ACTIVE, m); 1065 } 1066 } else { 1067 if (m->act_count < ACT_INIT) 1068 m->act_count = ACT_INIT; 1069 } 1070 splx(s); 1071 } 1072 1073 /* 1074 * vm_page_free_wakeup: 1075 * 1076 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 1077 * routine is called when a page has been added to the cache or free 1078 * queues. 1079 * 1080 * This routine may not block. 1081 * This routine must be called at splvm() 1082 */ 1083 static __inline void 1084 vm_page_free_wakeup(void) 1085 { 1086 /* 1087 * if pageout daemon needs pages, then tell it that there are 1088 * some free. 1089 */ 1090 if (vm_pageout_pages_needed && 1091 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 1092 wakeup(&vm_pageout_pages_needed); 1093 vm_pageout_pages_needed = 0; 1094 } 1095 /* 1096 * wakeup processes that are waiting on memory if we hit a 1097 * high water mark. And wakeup scheduler process if we have 1098 * lots of memory. this process will swapin processes. 1099 */ 1100 if (vm_pages_needed && !vm_page_count_min()) { 1101 vm_pages_needed = 0; 1102 wakeup(&cnt.v_free_count); 1103 } 1104 } 1105 1106 /* 1107 * vm_page_free_toq: 1108 * 1109 * Returns the given page to the PQ_FREE list, 1110 * disassociating it with any VM object. 1111 * 1112 * Object and page must be locked prior to entry. 1113 * This routine may not block. 1114 */ 1115 1116 void 1117 vm_page_free_toq(vm_page_t m) 1118 { 1119 int s; 1120 struct vpgqueues *pq; 1121 vm_object_t object = m->object; 1122 1123 GIANT_REQUIRED; 1124 s = splvm(); 1125 cnt.v_tfree++; 1126 1127 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1128 printf( 1129 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1130 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1131 m->hold_count); 1132 if ((m->queue - m->pc) == PQ_FREE) 1133 panic("vm_page_free: freeing free page"); 1134 else 1135 panic("vm_page_free: freeing busy page"); 1136 } 1137 1138 /* 1139 * unqueue, then remove page. Note that we cannot destroy 1140 * the page here because we do not want to call the pager's 1141 * callback routine until after we've put the page on the 1142 * appropriate free queue. 1143 */ 1144 vm_pageq_remove_nowakeup(m); 1145 vm_page_remove(m); 1146 1147 /* 1148 * If fictitious remove object association and 1149 * return, otherwise delay object association removal. 1150 */ 1151 if ((m->flags & PG_FICTITIOUS) != 0) { 1152 splx(s); 1153 return; 1154 } 1155 1156 m->valid = 0; 1157 vm_page_undirty(m); 1158 1159 if (m->wire_count != 0) { 1160 if (m->wire_count > 1) { 1161 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1162 m->wire_count, (long)m->pindex); 1163 } 1164 panic("vm_page_free: freeing wired page\n"); 1165 } 1166 1167 /* 1168 * If we've exhausted the object's resident pages we want to free 1169 * it up. 1170 */ 1171 if (object && 1172 (object->type == OBJT_VNODE) && 1173 ((object->flags & OBJ_DEAD) == 0) 1174 ) { 1175 struct vnode *vp = (struct vnode *)object->handle; 1176 1177 if (vp && VSHOULDFREE(vp)) 1178 vfree(vp); 1179 } 1180 1181 /* 1182 * Clear the UNMANAGED flag when freeing an unmanaged page. 1183 */ 1184 if (m->flags & PG_UNMANAGED) { 1185 m->flags &= ~PG_UNMANAGED; 1186 } else { 1187 #ifdef __alpha__ 1188 pmap_page_is_free(m); 1189 #endif 1190 } 1191 1192 if (m->hold_count != 0) { 1193 m->flags &= ~PG_ZERO; 1194 m->queue = PQ_HOLD; 1195 } else 1196 m->queue = PQ_FREE + m->pc; 1197 pq = &vm_page_queues[m->queue]; 1198 mtx_lock_spin(&vm_page_queue_free_mtx); 1199 pq->lcnt++; 1200 ++(*pq->cnt); 1201 1202 /* 1203 * Put zero'd pages on the end ( where we look for zero'd pages 1204 * first ) and non-zerod pages at the head. 1205 */ 1206 if (m->flags & PG_ZERO) { 1207 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1208 ++vm_page_zero_count; 1209 } else { 1210 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1211 } 1212 mtx_unlock_spin(&vm_page_queue_free_mtx); 1213 vm_page_free_wakeup(); 1214 splx(s); 1215 } 1216 1217 /* 1218 * vm_page_unmanage: 1219 * 1220 * Prevent PV management from being done on the page. The page is 1221 * removed from the paging queues as if it were wired, and as a 1222 * consequence of no longer being managed the pageout daemon will not 1223 * touch it (since there is no way to locate the pte mappings for the 1224 * page). madvise() calls that mess with the pmap will also no longer 1225 * operate on the page. 1226 * 1227 * Beyond that the page is still reasonably 'normal'. Freeing the page 1228 * will clear the flag. 1229 * 1230 * This routine is used by OBJT_PHYS objects - objects using unswappable 1231 * physical memory as backing store rather then swap-backed memory and 1232 * will eventually be extended to support 4MB unmanaged physical 1233 * mappings. 1234 */ 1235 void 1236 vm_page_unmanage(vm_page_t m) 1237 { 1238 int s; 1239 1240 s = splvm(); 1241 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1242 if ((m->flags & PG_UNMANAGED) == 0) { 1243 if (m->wire_count == 0) 1244 vm_pageq_remove(m); 1245 } 1246 vm_page_flag_set(m, PG_UNMANAGED); 1247 splx(s); 1248 } 1249 1250 /* 1251 * vm_page_wire: 1252 * 1253 * Mark this page as wired down by yet 1254 * another map, removing it from paging queues 1255 * as necessary. 1256 * 1257 * The page queues must be locked. 1258 * This routine may not block. 1259 */ 1260 void 1261 vm_page_wire(vm_page_t m) 1262 { 1263 int s; 1264 1265 /* 1266 * Only bump the wire statistics if the page is not already wired, 1267 * and only unqueue the page if it is on some queue (if it is unmanaged 1268 * it is already off the queues). 1269 */ 1270 s = splvm(); 1271 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1272 if (m->wire_count == 0) { 1273 if ((m->flags & PG_UNMANAGED) == 0) 1274 vm_pageq_remove(m); 1275 cnt.v_wire_count++; 1276 } 1277 m->wire_count++; 1278 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1279 splx(s); 1280 vm_page_flag_set(m, PG_MAPPED); /* XXX this does not belong here */ 1281 } 1282 1283 /* 1284 * vm_page_unwire: 1285 * 1286 * Release one wiring of this page, potentially 1287 * enabling it to be paged again. 1288 * 1289 * Many pages placed on the inactive queue should actually go 1290 * into the cache, but it is difficult to figure out which. What 1291 * we do instead, if the inactive target is well met, is to put 1292 * clean pages at the head of the inactive queue instead of the tail. 1293 * This will cause them to be moved to the cache more quickly and 1294 * if not actively re-referenced, freed more quickly. If we just 1295 * stick these pages at the end of the inactive queue, heavy filesystem 1296 * meta-data accesses can cause an unnecessary paging load on memory bound 1297 * processes. This optimization causes one-time-use metadata to be 1298 * reused more quickly. 1299 * 1300 * BUT, if we are in a low-memory situation we have no choice but to 1301 * put clean pages on the cache queue. 1302 * 1303 * A number of routines use vm_page_unwire() to guarantee that the page 1304 * will go into either the inactive or active queues, and will NEVER 1305 * be placed in the cache - for example, just after dirtying a page. 1306 * dirty pages in the cache are not allowed. 1307 * 1308 * The page queues must be locked. 1309 * This routine may not block. 1310 */ 1311 void 1312 vm_page_unwire(vm_page_t m, int activate) 1313 { 1314 int s; 1315 1316 s = splvm(); 1317 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1318 if (m->wire_count > 0) { 1319 m->wire_count--; 1320 if (m->wire_count == 0) { 1321 cnt.v_wire_count--; 1322 if (m->flags & PG_UNMANAGED) { 1323 ; 1324 } else if (activate) 1325 vm_pageq_enqueue(PQ_ACTIVE, m); 1326 else { 1327 vm_page_flag_clear(m, PG_WINATCFLS); 1328 vm_pageq_enqueue(PQ_INACTIVE, m); 1329 } 1330 } 1331 } else { 1332 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1333 } 1334 splx(s); 1335 } 1336 1337 1338 /* 1339 * Move the specified page to the inactive queue. If the page has 1340 * any associated swap, the swap is deallocated. 1341 * 1342 * Normally athead is 0 resulting in LRU operation. athead is set 1343 * to 1 if we want this page to be 'as if it were placed in the cache', 1344 * except without unmapping it from the process address space. 1345 * 1346 * This routine may not block. 1347 */ 1348 static __inline void 1349 _vm_page_deactivate(vm_page_t m, int athead) 1350 { 1351 int s; 1352 1353 GIANT_REQUIRED; 1354 /* 1355 * Ignore if already inactive. 1356 */ 1357 if (m->queue == PQ_INACTIVE) 1358 return; 1359 1360 s = splvm(); 1361 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1362 if ((m->queue - m->pc) == PQ_CACHE) 1363 cnt.v_reactivated++; 1364 vm_page_flag_clear(m, PG_WINATCFLS); 1365 vm_pageq_remove(m); 1366 if (athead) 1367 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1368 else 1369 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1370 m->queue = PQ_INACTIVE; 1371 vm_page_queues[PQ_INACTIVE].lcnt++; 1372 cnt.v_inactive_count++; 1373 } 1374 splx(s); 1375 } 1376 1377 void 1378 vm_page_deactivate(vm_page_t m) 1379 { 1380 _vm_page_deactivate(m, 0); 1381 } 1382 1383 /* 1384 * vm_page_try_to_cache: 1385 * 1386 * Returns 0 on failure, 1 on success 1387 */ 1388 int 1389 vm_page_try_to_cache(vm_page_t m) 1390 { 1391 1392 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1393 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1394 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1395 return (0); 1396 } 1397 vm_page_test_dirty(m); 1398 if (m->dirty) 1399 return (0); 1400 vm_page_cache(m); 1401 return (1); 1402 } 1403 1404 /* 1405 * vm_page_try_to_free() 1406 * 1407 * Attempt to free the page. If we cannot free it, we do nothing. 1408 * 1 is returned on success, 0 on failure. 1409 */ 1410 int 1411 vm_page_try_to_free(vm_page_t m) 1412 { 1413 1414 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1415 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1416 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1417 return (0); 1418 } 1419 vm_page_test_dirty(m); 1420 if (m->dirty) 1421 return (0); 1422 vm_page_busy(m); 1423 vm_page_protect(m, VM_PROT_NONE); 1424 vm_page_free(m); 1425 return (1); 1426 } 1427 1428 /* 1429 * vm_page_cache 1430 * 1431 * Put the specified page onto the page cache queue (if appropriate). 1432 * 1433 * This routine may not block. 1434 */ 1435 void 1436 vm_page_cache(vm_page_t m) 1437 { 1438 int s; 1439 1440 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1441 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || m->wire_count) { 1442 printf("vm_page_cache: attempting to cache busy page\n"); 1443 return; 1444 } 1445 if ((m->queue - m->pc) == PQ_CACHE) 1446 return; 1447 1448 /* 1449 * Remove all pmaps and indicate that the page is not 1450 * writeable or mapped. 1451 */ 1452 vm_page_protect(m, VM_PROT_NONE); 1453 if (m->dirty != 0) { 1454 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1455 (long)m->pindex); 1456 } 1457 s = splvm(); 1458 vm_pageq_remove_nowakeup(m); 1459 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1460 vm_page_free_wakeup(); 1461 splx(s); 1462 } 1463 1464 /* 1465 * vm_page_dontneed 1466 * 1467 * Cache, deactivate, or do nothing as appropriate. This routine 1468 * is typically used by madvise() MADV_DONTNEED. 1469 * 1470 * Generally speaking we want to move the page into the cache so 1471 * it gets reused quickly. However, this can result in a silly syndrome 1472 * due to the page recycling too quickly. Small objects will not be 1473 * fully cached. On the otherhand, if we move the page to the inactive 1474 * queue we wind up with a problem whereby very large objects 1475 * unnecessarily blow away our inactive and cache queues. 1476 * 1477 * The solution is to move the pages based on a fixed weighting. We 1478 * either leave them alone, deactivate them, or move them to the cache, 1479 * where moving them to the cache has the highest weighting. 1480 * By forcing some pages into other queues we eventually force the 1481 * system to balance the queues, potentially recovering other unrelated 1482 * space from active. The idea is to not force this to happen too 1483 * often. 1484 */ 1485 void 1486 vm_page_dontneed(vm_page_t m) 1487 { 1488 static int dnweight; 1489 int dnw; 1490 int head; 1491 1492 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 1493 dnw = ++dnweight; 1494 1495 /* 1496 * occassionally leave the page alone 1497 */ 1498 if ((dnw & 0x01F0) == 0 || 1499 m->queue == PQ_INACTIVE || 1500 m->queue - m->pc == PQ_CACHE 1501 ) { 1502 if (m->act_count >= ACT_INIT) 1503 --m->act_count; 1504 return; 1505 } 1506 1507 if (m->dirty == 0) 1508 vm_page_test_dirty(m); 1509 1510 if (m->dirty || (dnw & 0x0070) == 0) { 1511 /* 1512 * Deactivate the page 3 times out of 32. 1513 */ 1514 head = 0; 1515 } else { 1516 /* 1517 * Cache the page 28 times out of every 32. Note that 1518 * the page is deactivated instead of cached, but placed 1519 * at the head of the queue instead of the tail. 1520 */ 1521 head = 1; 1522 } 1523 _vm_page_deactivate(m, head); 1524 } 1525 1526 /* 1527 * Grab a page, waiting until we are waken up due to the page 1528 * changing state. We keep on waiting, if the page continues 1529 * to be in the object. If the page doesn't exist, allocate it. 1530 * 1531 * This routine may block. 1532 */ 1533 vm_page_t 1534 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1535 { 1536 vm_page_t m; 1537 int s, generation; 1538 1539 GIANT_REQUIRED; 1540 retrylookup: 1541 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1542 if (m->busy || (m->flags & PG_BUSY)) { 1543 generation = object->generation; 1544 1545 s = splvm(); 1546 while ((object->generation == generation) && 1547 (m->busy || (m->flags & PG_BUSY))) { 1548 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1549 tsleep(m, PVM, "pgrbwt", 0); 1550 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1551 splx(s); 1552 return NULL; 1553 } 1554 } 1555 splx(s); 1556 goto retrylookup; 1557 } else { 1558 vm_page_lock_queues(); 1559 if (allocflags & VM_ALLOC_WIRED) 1560 vm_page_wire(m); 1561 vm_page_busy(m); 1562 vm_page_unlock_queues(); 1563 return m; 1564 } 1565 } 1566 1567 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1568 if (m == NULL) { 1569 VM_WAIT; 1570 if ((allocflags & VM_ALLOC_RETRY) == 0) 1571 return NULL; 1572 goto retrylookup; 1573 } 1574 1575 return m; 1576 } 1577 1578 /* 1579 * Mapping function for valid bits or for dirty bits in 1580 * a page. May not block. 1581 * 1582 * Inputs are required to range within a page. 1583 */ 1584 __inline int 1585 vm_page_bits(int base, int size) 1586 { 1587 int first_bit; 1588 int last_bit; 1589 1590 KASSERT( 1591 base + size <= PAGE_SIZE, 1592 ("vm_page_bits: illegal base/size %d/%d", base, size) 1593 ); 1594 1595 if (size == 0) /* handle degenerate case */ 1596 return (0); 1597 1598 first_bit = base >> DEV_BSHIFT; 1599 last_bit = (base + size - 1) >> DEV_BSHIFT; 1600 1601 return ((2 << last_bit) - (1 << first_bit)); 1602 } 1603 1604 /* 1605 * vm_page_set_validclean: 1606 * 1607 * Sets portions of a page valid and clean. The arguments are expected 1608 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1609 * of any partial chunks touched by the range. The invalid portion of 1610 * such chunks will be zero'd. 1611 * 1612 * This routine may not block. 1613 * 1614 * (base + size) must be less then or equal to PAGE_SIZE. 1615 */ 1616 void 1617 vm_page_set_validclean(vm_page_t m, int base, int size) 1618 { 1619 int pagebits; 1620 int frag; 1621 int endoff; 1622 1623 GIANT_REQUIRED; 1624 if (size == 0) /* handle degenerate case */ 1625 return; 1626 1627 /* 1628 * If the base is not DEV_BSIZE aligned and the valid 1629 * bit is clear, we have to zero out a portion of the 1630 * first block. 1631 */ 1632 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1633 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1634 pmap_zero_page_area(m, frag, base - frag); 1635 1636 /* 1637 * If the ending offset is not DEV_BSIZE aligned and the 1638 * valid bit is clear, we have to zero out a portion of 1639 * the last block. 1640 */ 1641 endoff = base + size; 1642 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1643 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1644 pmap_zero_page_area(m, endoff, 1645 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1646 1647 /* 1648 * Set valid, clear dirty bits. If validating the entire 1649 * page we can safely clear the pmap modify bit. We also 1650 * use this opportunity to clear the PG_NOSYNC flag. If a process 1651 * takes a write fault on a MAP_NOSYNC memory area the flag will 1652 * be set again. 1653 * 1654 * We set valid bits inclusive of any overlap, but we can only 1655 * clear dirty bits for DEV_BSIZE chunks that are fully within 1656 * the range. 1657 */ 1658 pagebits = vm_page_bits(base, size); 1659 m->valid |= pagebits; 1660 #if 0 /* NOT YET */ 1661 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1662 frag = DEV_BSIZE - frag; 1663 base += frag; 1664 size -= frag; 1665 if (size < 0) 1666 size = 0; 1667 } 1668 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1669 #endif 1670 m->dirty &= ~pagebits; 1671 if (base == 0 && size == PAGE_SIZE) { 1672 pmap_clear_modify(m); 1673 vm_page_flag_clear(m, PG_NOSYNC); 1674 } 1675 } 1676 1677 #if 0 1678 1679 void 1680 vm_page_set_dirty(vm_page_t m, int base, int size) 1681 { 1682 m->dirty |= vm_page_bits(base, size); 1683 } 1684 1685 #endif 1686 1687 void 1688 vm_page_clear_dirty(vm_page_t m, int base, int size) 1689 { 1690 GIANT_REQUIRED; 1691 m->dirty &= ~vm_page_bits(base, size); 1692 } 1693 1694 /* 1695 * vm_page_set_invalid: 1696 * 1697 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1698 * valid and dirty bits for the effected areas are cleared. 1699 * 1700 * May not block. 1701 */ 1702 void 1703 vm_page_set_invalid(vm_page_t m, int base, int size) 1704 { 1705 int bits; 1706 1707 GIANT_REQUIRED; 1708 bits = vm_page_bits(base, size); 1709 m->valid &= ~bits; 1710 m->dirty &= ~bits; 1711 m->object->generation++; 1712 } 1713 1714 /* 1715 * vm_page_zero_invalid() 1716 * 1717 * The kernel assumes that the invalid portions of a page contain 1718 * garbage, but such pages can be mapped into memory by user code. 1719 * When this occurs, we must zero out the non-valid portions of the 1720 * page so user code sees what it expects. 1721 * 1722 * Pages are most often semi-valid when the end of a file is mapped 1723 * into memory and the file's size is not page aligned. 1724 */ 1725 void 1726 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1727 { 1728 int b; 1729 int i; 1730 1731 /* 1732 * Scan the valid bits looking for invalid sections that 1733 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1734 * valid bit may be set ) have already been zerod by 1735 * vm_page_set_validclean(). 1736 */ 1737 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1738 if (i == (PAGE_SIZE / DEV_BSIZE) || 1739 (m->valid & (1 << i)) 1740 ) { 1741 if (i > b) { 1742 pmap_zero_page_area(m, 1743 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1744 } 1745 b = i + 1; 1746 } 1747 } 1748 1749 /* 1750 * setvalid is TRUE when we can safely set the zero'd areas 1751 * as being valid. We can do this if there are no cache consistancy 1752 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1753 */ 1754 if (setvalid) 1755 m->valid = VM_PAGE_BITS_ALL; 1756 } 1757 1758 /* 1759 * vm_page_is_valid: 1760 * 1761 * Is (partial) page valid? Note that the case where size == 0 1762 * will return FALSE in the degenerate case where the page is 1763 * entirely invalid, and TRUE otherwise. 1764 * 1765 * May not block. 1766 */ 1767 int 1768 vm_page_is_valid(vm_page_t m, int base, int size) 1769 { 1770 int bits = vm_page_bits(base, size); 1771 1772 if (m->valid && ((m->valid & bits) == bits)) 1773 return 1; 1774 else 1775 return 0; 1776 } 1777 1778 /* 1779 * update dirty bits from pmap/mmu. May not block. 1780 */ 1781 void 1782 vm_page_test_dirty(vm_page_t m) 1783 { 1784 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1785 vm_page_dirty(m); 1786 } 1787 } 1788 1789 int so_zerocp_fullpage = 0; 1790 1791 void 1792 vm_page_cowfault(vm_page_t m) 1793 { 1794 vm_page_t mnew; 1795 vm_object_t object; 1796 vm_pindex_t pindex; 1797 1798 object = m->object; 1799 pindex = m->pindex; 1800 vm_page_busy(m); 1801 1802 retry_alloc: 1803 vm_page_remove(m); 1804 mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL); 1805 if (mnew == NULL) { 1806 vm_page_insert(m, object, pindex); 1807 VM_WAIT; 1808 goto retry_alloc; 1809 } 1810 1811 if (m->cow == 0) { 1812 /* 1813 * check to see if we raced with an xmit complete when 1814 * waiting to allocate a page. If so, put things back 1815 * the way they were 1816 */ 1817 vm_page_busy(mnew); 1818 vm_page_free(mnew); 1819 vm_page_insert(m, object, pindex); 1820 } else { /* clear COW & copy page */ 1821 if (so_zerocp_fullpage) { 1822 mnew->valid = VM_PAGE_BITS_ALL; 1823 } else { 1824 vm_page_copy(m, mnew); 1825 } 1826 vm_page_dirty(mnew); 1827 vm_page_flag_clear(mnew, PG_BUSY); 1828 } 1829 } 1830 1831 void 1832 vm_page_cowclear(vm_page_t m) 1833 { 1834 1835 /* XXX KDM find out if giant is required here. */ 1836 GIANT_REQUIRED; 1837 if (m->cow) { 1838 atomic_subtract_int(&m->cow, 1); 1839 /* 1840 * let vm_fault add back write permission lazily 1841 */ 1842 } 1843 /* 1844 * sf_buf_free() will free the page, so we needn't do it here 1845 */ 1846 } 1847 1848 void 1849 vm_page_cowsetup(vm_page_t m) 1850 { 1851 /* XXX KDM find out if giant is required here */ 1852 GIANT_REQUIRED; 1853 atomic_add_int(&m->cow, 1); 1854 vm_page_protect(m, VM_PROT_READ); 1855 } 1856 1857 #include "opt_ddb.h" 1858 #ifdef DDB 1859 #include <sys/kernel.h> 1860 1861 #include <ddb/ddb.h> 1862 1863 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1864 { 1865 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1866 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1867 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1868 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1869 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1870 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1871 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1872 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1873 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1874 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1875 } 1876 1877 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1878 { 1879 int i; 1880 db_printf("PQ_FREE:"); 1881 for (i = 0; i < PQ_L2_SIZE; i++) { 1882 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1883 } 1884 db_printf("\n"); 1885 1886 db_printf("PQ_CACHE:"); 1887 for (i = 0; i < PQ_L2_SIZE; i++) { 1888 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1889 } 1890 db_printf("\n"); 1891 1892 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1893 vm_page_queues[PQ_ACTIVE].lcnt, 1894 vm_page_queues[PQ_INACTIVE].lcnt); 1895 } 1896 #endif /* DDB */ 1897