vm_page.c revision 92029
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: head/sys/vm/vm_page.c 92029 2002-03-10 21:52:48Z eivind $ 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> 121 122/* 123 * Associated with page of user-allocatable memory is a 124 * page structure. 125 */ 126static struct vm_page **vm_page_buckets; /* Array of buckets */ 127static int vm_page_bucket_count; /* How big is array? */ 128static int vm_page_hash_mask; /* Mask for hash function */ 129static volatile int vm_page_bucket_generation; 130static struct mtx vm_buckets_mtx[BUCKET_HASH_SIZE]; 131 132vm_page_t vm_page_array = 0; 133int vm_page_array_size = 0; 134long first_page = 0; 135int 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 */ 144void 145vm_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 */ 162vm_offset_t 163vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 164{ 165 vm_offset_t mapped; 166 struct vm_page **bucket; 167 vm_size_t npages, page_range; 168 vm_offset_t new_end; 169 int i; 170 vm_offset_t pa; 171 int nblocks; 172 vm_offset_t last_pa; 173 174 /* the biggest memory array is the second group of pages */ 175 vm_offset_t end; 176 vm_offset_t biggestone, biggestsize; 177 178 vm_offset_t total; 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 int 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 queue headers for the free queue, the active queue 206 * and the inactive queue. 207 */ 208 vm_pageq_init(); 209 210 /* 211 * Allocate (and initialize) the hash table buckets. 212 * 213 * The number of buckets MUST BE a power of 2, and the actual value is 214 * the next power of 2 greater than the number of physical pages in 215 * the system. 216 * 217 * We make the hash table approximately 2x the number of pages to 218 * reduce the chain length. This is about the same size using the 219 * singly-linked list as the 1x hash table we were using before 220 * using TAILQ but the chain length will be smaller. 221 * 222 * Note: This computation can be tweaked if desired. 223 */ 224 if (vm_page_bucket_count == 0) { 225 vm_page_bucket_count = 1; 226 while (vm_page_bucket_count < atop(total)) 227 vm_page_bucket_count <<= 1; 228 } 229 vm_page_bucket_count <<= 1; 230 vm_page_hash_mask = vm_page_bucket_count - 1; 231 232 /* 233 * Validate these addresses. 234 */ 235 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 236 new_end = trunc_page(new_end); 237 mapped = pmap_map(&vaddr, new_end, end, 238 VM_PROT_READ | VM_PROT_WRITE); 239 bzero((caddr_t) mapped, end - new_end); 240 241 vm_page_buckets = (struct vm_page **)mapped; 242 bucket = vm_page_buckets; 243 for (i = 0; i < vm_page_bucket_count; i++) { 244 *bucket = NULL; 245 bucket++; 246 } 247 for (i = 0; i < BUCKET_HASH_SIZE; ++i) 248 mtx_init(&vm_buckets_mtx[i], "vm buckets hash mutexes", MTX_DEF); 249 250 /* 251 * Compute the number of pages of memory that will be available for 252 * use (taking into account the overhead of a page structure per 253 * page). 254 */ 255 first_page = phys_avail[0] / PAGE_SIZE; 256 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 257 npages = (total - (page_range * sizeof(struct vm_page)) - 258 (end - new_end)) / PAGE_SIZE; 259 end = new_end; 260 261 /* 262 * Initialize the mem entry structures now, and put them in the free 263 * queue. 264 */ 265 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 266 mapped = pmap_map(&vaddr, new_end, end, 267 VM_PROT_READ | VM_PROT_WRITE); 268 vm_page_array = (vm_page_t) mapped; 269 270 /* 271 * Clear all of the page structures 272 */ 273 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 274 vm_page_array_size = page_range; 275 276 /* 277 * Construct the free queue(s) in descending order (by physical 278 * address) so that the first 16MB of physical memory is allocated 279 * last rather than first. On large-memory machines, this avoids 280 * the exhaustion of low physical memory before isa_dmainit has run. 281 */ 282 cnt.v_page_count = 0; 283 cnt.v_free_count = 0; 284 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 285 pa = phys_avail[i]; 286 if (i == biggestone) 287 last_pa = new_end; 288 else 289 last_pa = phys_avail[i + 1]; 290 while (pa < last_pa && npages-- > 0) { 291 vm_pageq_add_new_page(pa); 292 pa += PAGE_SIZE; 293 } 294 } 295 return (vaddr); 296} 297 298/* 299 * vm_page_hash: 300 * 301 * Distributes the object/offset key pair among hash buckets. 302 * 303 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 304 * This routine may not block. 305 * 306 * We try to randomize the hash based on the object to spread the pages 307 * out in the hash table without it costing us too much. 308 */ 309static __inline int 310vm_page_hash(vm_object_t object, vm_pindex_t pindex) 311{ 312 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 313 314 return (i & vm_page_hash_mask); 315} 316 317void 318vm_page_flag_set(vm_page_t m, unsigned short bits) 319{ 320 GIANT_REQUIRED; 321 m->flags |= bits; 322} 323 324void 325vm_page_flag_clear(vm_page_t m, unsigned short bits) 326{ 327 GIANT_REQUIRED; 328 m->flags &= ~bits; 329} 330 331void 332vm_page_busy(vm_page_t m) 333{ 334 KASSERT((m->flags & PG_BUSY) == 0, 335 ("vm_page_busy: page already busy!!!")); 336 vm_page_flag_set(m, PG_BUSY); 337} 338 339/* 340 * vm_page_flash: 341 * 342 * wakeup anyone waiting for the page. 343 */ 344void 345vm_page_flash(vm_page_t m) 346{ 347 if (m->flags & PG_WANTED) { 348 vm_page_flag_clear(m, PG_WANTED); 349 wakeup(m); 350 } 351} 352 353/* 354 * vm_page_wakeup: 355 * 356 * clear the PG_BUSY flag and wakeup anyone waiting for the 357 * page. 358 * 359 */ 360void 361vm_page_wakeup(vm_page_t m) 362{ 363 KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 364 vm_page_flag_clear(m, PG_BUSY); 365 vm_page_flash(m); 366} 367 368/* 369 * 370 * 371 */ 372void 373vm_page_io_start(vm_page_t m) 374{ 375 GIANT_REQUIRED; 376 m->busy++; 377} 378 379void 380vm_page_io_finish(vm_page_t m) 381{ 382 GIANT_REQUIRED; 383 m->busy--; 384 if (m->busy == 0) 385 vm_page_flash(m); 386} 387 388/* 389 * Keep page from being freed by the page daemon 390 * much of the same effect as wiring, except much lower 391 * overhead and should be used only for *very* temporary 392 * holding ("wiring"). 393 */ 394void 395vm_page_hold(vm_page_t mem) 396{ 397 GIANT_REQUIRED; 398 mem->hold_count++; 399} 400 401void 402vm_page_unhold(vm_page_t mem) 403{ 404 GIANT_REQUIRED; 405 --mem->hold_count; 406 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 407 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 408 vm_page_free_toq(mem); 409} 410 411/* 412 * vm_page_protect: 413 * 414 * Reduce the protection of a page. This routine never raises the 415 * protection and therefore can be safely called if the page is already 416 * at VM_PROT_NONE (it will be a NOP effectively ). 417 */ 418void 419vm_page_protect(vm_page_t mem, int prot) 420{ 421 if (prot == VM_PROT_NONE) { 422 if (mem->flags & (PG_WRITEABLE|PG_MAPPED)) { 423 pmap_page_protect(mem, VM_PROT_NONE); 424 vm_page_flag_clear(mem, PG_WRITEABLE|PG_MAPPED); 425 } 426 } else if ((prot == VM_PROT_READ) && (mem->flags & PG_WRITEABLE)) { 427 pmap_page_protect(mem, VM_PROT_READ); 428 vm_page_flag_clear(mem, PG_WRITEABLE); 429 } 430} 431/* 432 * vm_page_zero_fill: 433 * 434 * Zero-fill the specified page. 435 * Written as a standard pagein routine, to 436 * be used by the zero-fill object. 437 */ 438boolean_t 439vm_page_zero_fill(vm_page_t m) 440{ 441 pmap_zero_page(VM_PAGE_TO_PHYS(m)); 442 return (TRUE); 443} 444 445/* 446 * vm_page_copy: 447 * 448 * Copy one page to another 449 */ 450void 451vm_page_copy(vm_page_t src_m, vm_page_t dest_m) 452{ 453 pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m)); 454 dest_m->valid = VM_PAGE_BITS_ALL; 455} 456 457/* 458 * vm_page_free: 459 * 460 * Free a page 461 * 462 * The clearing of PG_ZERO is a temporary safety until the code can be 463 * reviewed to determine that PG_ZERO is being properly cleared on 464 * write faults or maps. PG_ZERO was previously cleared in 465 * vm_page_alloc(). 466 */ 467void 468vm_page_free(vm_page_t m) 469{ 470 vm_page_flag_clear(m, PG_ZERO); 471 vm_page_free_toq(m); 472 vm_page_zero_idle_wakeup(); 473} 474 475/* 476 * vm_page_free_zero: 477 * 478 * Free a page to the zerod-pages queue 479 */ 480void 481vm_page_free_zero(vm_page_t m) 482{ 483 vm_page_flag_set(m, PG_ZERO); 484 vm_page_free_toq(m); 485} 486 487/* 488 * vm_page_sleep_busy: 489 * 490 * Wait until page is no longer PG_BUSY or (if also_m_busy is TRUE) 491 * m->busy is zero. Returns TRUE if it had to sleep ( including if 492 * it almost had to sleep and made temporary spl*() mods), FALSE 493 * otherwise. 494 * 495 * This routine assumes that interrupts can only remove the busy 496 * status from a page, not set the busy status or change it from 497 * PG_BUSY to m->busy or vise versa (which would create a timing 498 * window). 499 */ 500int 501vm_page_sleep_busy(vm_page_t m, int also_m_busy, const char *msg) 502{ 503 GIANT_REQUIRED; 504 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 505 int s = splvm(); 506 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 507 /* 508 * Page is busy. Wait and retry. 509 */ 510 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 511 tsleep(m, PVM, msg, 0); 512 } 513 splx(s); 514 return (TRUE); 515 /* not reached */ 516 } 517 return (FALSE); 518} 519/* 520 * vm_page_dirty: 521 * 522 * make page all dirty 523 */ 524void 525vm_page_dirty(vm_page_t m) 526{ 527 KASSERT(m->queue - m->pc != PQ_CACHE, 528 ("vm_page_dirty: page in cache!")); 529 m->dirty = VM_PAGE_BITS_ALL; 530} 531 532/* 533 * vm_page_undirty: 534 * 535 * Set page to not be dirty. Note: does not clear pmap modify bits 536 */ 537void 538vm_page_undirty(vm_page_t m) 539{ 540 m->dirty = 0; 541} 542 543/* 544 * vm_page_insert: [ internal use only ] 545 * 546 * Inserts the given mem entry into the object and object list. 547 * 548 * The pagetables are not updated but will presumably fault the page 549 * in if necessary, or if a kernel page the caller will at some point 550 * enter the page into the kernel's pmap. We are not allowed to block 551 * here so we *can't* do this anyway. 552 * 553 * The object and page must be locked, and must be splhigh. 554 * This routine may not block. 555 */ 556void 557vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 558{ 559 struct vm_page **bucket; 560 561 GIANT_REQUIRED; 562 563 if (m->object != NULL) 564 panic("vm_page_insert: already inserted"); 565 566 /* 567 * Record the object/offset pair in this page 568 */ 569 m->object = object; 570 m->pindex = pindex; 571 572 /* 573 * Insert it into the object_object/offset hash table 574 */ 575 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 576 m->hnext = *bucket; 577 *bucket = m; 578 vm_page_bucket_generation++; 579 580 /* 581 * Now link into the object's list of backed pages. 582 */ 583 TAILQ_INSERT_TAIL(&object->memq, m, listq); 584 object->generation++; 585 586 /* 587 * show that the object has one more resident page. 588 */ 589 object->resident_page_count++; 590 591 /* 592 * Since we are inserting a new and possibly dirty page, 593 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 594 */ 595 if (m->flags & PG_WRITEABLE) 596 vm_object_set_writeable_dirty(object); 597} 598 599/* 600 * vm_page_remove: 601 * NOTE: used by device pager as well -wfj 602 * 603 * Removes the given mem entry from the object/offset-page 604 * table and the object page list, but do not invalidate/terminate 605 * the backing store. 606 * 607 * The object and page must be locked, and at splhigh. 608 * The underlying pmap entry (if any) is NOT removed here. 609 * This routine may not block. 610 */ 611void 612vm_page_remove(vm_page_t m) 613{ 614 vm_object_t object; 615 616 GIANT_REQUIRED; 617 618 if (m->object == NULL) 619 return; 620 621 if ((m->flags & PG_BUSY) == 0) { 622 panic("vm_page_remove: page not busy"); 623 } 624 625 /* 626 * Basically destroy the page. 627 */ 628 vm_page_wakeup(m); 629 630 object = m->object; 631 632 /* 633 * Remove from the object_object/offset hash table. The object 634 * must be on the hash queue, we will panic if it isn't 635 * 636 * Note: we must NULL-out m->hnext to prevent loops in detached 637 * buffers with vm_page_lookup(). 638 */ 639 { 640 struct vm_page **bucket; 641 642 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 643 while (*bucket != m) { 644 if (*bucket == NULL) 645 panic("vm_page_remove(): page not found in hash"); 646 bucket = &(*bucket)->hnext; 647 } 648 *bucket = m->hnext; 649 m->hnext = NULL; 650 vm_page_bucket_generation++; 651 } 652 653 /* 654 * Now remove from the object's list of backed pages. 655 */ 656 TAILQ_REMOVE(&object->memq, m, listq); 657 658 /* 659 * And show that the object has one fewer resident page. 660 */ 661 object->resident_page_count--; 662 object->generation++; 663 664 m->object = NULL; 665} 666 667/* 668 * vm_page_lookup: 669 * 670 * Returns the page associated with the object/offset 671 * pair specified; if none is found, NULL is returned. 672 * 673 * NOTE: the code below does not lock. It will operate properly if 674 * an interrupt makes a change, but the generation algorithm will not 675 * operate properly in an SMP environment where both cpu's are able to run 676 * kernel code simultaneously. 677 * 678 * The object must be locked. No side effects. 679 * This routine may not block. 680 * This is a critical path routine 681 */ 682vm_page_t 683vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 684{ 685 vm_page_t m; 686 struct vm_page **bucket; 687 int generation; 688 689 /* 690 * Search the hash table for this object/offset pair 691 */ 692retry: 693 generation = vm_page_bucket_generation; 694 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 695 for (m = *bucket; m != NULL; m = m->hnext) { 696 if ((m->object == object) && (m->pindex == pindex)) { 697 if (vm_page_bucket_generation != generation) 698 goto retry; 699 return (m); 700 } 701 } 702 if (vm_page_bucket_generation != generation) 703 goto retry; 704 return (NULL); 705} 706 707/* 708 * vm_page_rename: 709 * 710 * Move the given memory entry from its 711 * current object to the specified target object/offset. 712 * 713 * The object must be locked. 714 * This routine may not block. 715 * 716 * Note: this routine will raise itself to splvm(), the caller need not. 717 * 718 * Note: swap associated with the page must be invalidated by the move. We 719 * have to do this for several reasons: (1) we aren't freeing the 720 * page, (2) we are dirtying the page, (3) the VM system is probably 721 * moving the page from object A to B, and will then later move 722 * the backing store from A to B and we can't have a conflict. 723 * 724 * Note: we *always* dirty the page. It is necessary both for the 725 * fact that we moved it, and because we may be invalidating 726 * swap. If the page is on the cache, we have to deactivate it 727 * or vm_page_dirty() will panic. Dirty pages are not allowed 728 * on the cache. 729 */ 730void 731vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 732{ 733 int s; 734 735 s = splvm(); 736 vm_page_remove(m); 737 vm_page_insert(m, new_object, new_pindex); 738 if (m->queue - m->pc == PQ_CACHE) 739 vm_page_deactivate(m); 740 vm_page_dirty(m); 741 splx(s); 742} 743 744/* 745 * vm_page_select_cache: 746 * 747 * Find a page on the cache queue with color optimization. As pages 748 * might be found, but not applicable, they are deactivated. This 749 * keeps us from using potentially busy cached pages. 750 * 751 * This routine must be called at splvm(). 752 * This routine may not block. 753 */ 754static vm_page_t 755vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 756{ 757 vm_page_t m; 758 759 GIANT_REQUIRED; 760 while (TRUE) { 761 m = vm_pageq_find( 762 PQ_CACHE, 763 (pindex + object->pg_color) & PQ_L2_MASK, 764 FALSE 765 ); 766 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 767 m->hold_count || m->wire_count)) { 768 vm_page_deactivate(m); 769 continue; 770 } 771 return m; 772 } 773} 774 775/* 776 * vm_page_select_free: 777 * 778 * Find a free or zero page, with specified preference. 779 * 780 * This routine must be called at splvm(). 781 * This routine may not block. 782 */ 783static __inline vm_page_t 784vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 785{ 786 vm_page_t m; 787 788 m = vm_pageq_find( 789 PQ_FREE, 790 (pindex + object->pg_color) & PQ_L2_MASK, 791 prefer_zero 792 ); 793 return (m); 794} 795 796/* 797 * vm_page_alloc: 798 * 799 * Allocate and return a memory cell associated 800 * with this VM object/offset pair. 801 * 802 * page_req classes: 803 * VM_ALLOC_NORMAL normal process request 804 * VM_ALLOC_SYSTEM system *really* needs a page 805 * VM_ALLOC_INTERRUPT interrupt time request 806 * VM_ALLOC_ZERO zero page 807 * 808 * This routine may not block. 809 * 810 * Additional special handling is required when called from an 811 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 812 * the page cache in this case. 813 */ 814vm_page_t 815vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 816{ 817 vm_page_t m = NULL; 818 int s; 819 820 GIANT_REQUIRED; 821 822 KASSERT(!vm_page_lookup(object, pindex), 823 ("vm_page_alloc: page already allocated")); 824 825 /* 826 * The pager is allowed to eat deeper into the free page list. 827 */ 828 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 829 page_req = VM_ALLOC_SYSTEM; 830 }; 831 832 s = splvm(); 833 834loop: 835 if (cnt.v_free_count > cnt.v_free_reserved) { 836 /* 837 * Allocate from the free queue if there are plenty of pages 838 * in it. 839 */ 840 if (page_req == VM_ALLOC_ZERO) 841 m = vm_page_select_free(object, pindex, TRUE); 842 else 843 m = vm_page_select_free(object, pindex, FALSE); 844 } else if ( 845 (page_req == VM_ALLOC_SYSTEM && 846 cnt.v_cache_count == 0 && 847 cnt.v_free_count > cnt.v_interrupt_free_min) || 848 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0) 849 ) { 850 /* 851 * Interrupt or system, dig deeper into the free list. 852 */ 853 m = vm_page_select_free(object, pindex, FALSE); 854 } else if (page_req != VM_ALLOC_INTERRUPT) { 855 /* 856 * Allocatable from cache (non-interrupt only). On success, 857 * we must free the page and try again, thus ensuring that 858 * cnt.v_*_free_min counters are replenished. 859 */ 860 m = vm_page_select_cache(object, pindex); 861 if (m == NULL) { 862 splx(s); 863#if defined(DIAGNOSTIC) 864 if (cnt.v_cache_count > 0) 865 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", cnt.v_cache_count); 866#endif 867 vm_pageout_deficit++; 868 pagedaemon_wakeup(); 869 return (NULL); 870 } 871 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 872 vm_page_busy(m); 873 vm_page_protect(m, VM_PROT_NONE); 874 vm_page_free(m); 875 goto loop; 876 } else { 877 /* 878 * Not allocatable from cache from interrupt, give up. 879 */ 880 splx(s); 881 vm_pageout_deficit++; 882 pagedaemon_wakeup(); 883 return (NULL); 884 } 885 886 /* 887 * At this point we had better have found a good page. 888 */ 889 890 KASSERT( 891 m != NULL, 892 ("vm_page_alloc(): missing page on free queue\n") 893 ); 894 895 /* 896 * Remove from free queue 897 */ 898 899 vm_pageq_remove_nowakeup(m); 900 901 /* 902 * Initialize structure. Only the PG_ZERO flag is inherited. 903 */ 904 if (m->flags & PG_ZERO) { 905 vm_page_zero_count--; 906 m->flags = PG_ZERO | PG_BUSY; 907 } else { 908 m->flags = PG_BUSY; 909 } 910 m->wire_count = 0; 911 m->hold_count = 0; 912 m->act_count = 0; 913 m->busy = 0; 914 m->valid = 0; 915 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 916 917 /* 918 * vm_page_insert() is safe prior to the splx(). Note also that 919 * inserting a page here does not insert it into the pmap (which 920 * could cause us to block allocating memory). We cannot block 921 * anywhere. 922 */ 923 vm_page_insert(m, object, pindex); 924 925 /* 926 * Don't wakeup too often - wakeup the pageout daemon when 927 * we would be nearly out of memory. 928 */ 929 if (vm_paging_needed()) 930 pagedaemon_wakeup(); 931 932 splx(s); 933 return (m); 934} 935 936/* 937 * vm_wait: (also see VM_WAIT macro) 938 * 939 * Block until free pages are available for allocation 940 * - Called in various places before memory allocations. 941 */ 942void 943vm_wait(void) 944{ 945 int s; 946 947 s = splvm(); 948 if (curproc == pageproc) { 949 vm_pageout_pages_needed = 1; 950 tsleep(&vm_pageout_pages_needed, PSWP, "VMWait", 0); 951 } else { 952 if (!vm_pages_needed) { 953 vm_pages_needed = 1; 954 wakeup(&vm_pages_needed); 955 } 956 tsleep(&cnt.v_free_count, PVM, "vmwait", 0); 957 } 958 splx(s); 959} 960 961/* 962 * vm_waitpfault: (also see VM_WAITPFAULT macro) 963 * 964 * Block until free pages are available for allocation 965 * - Called only in vm_fault so that processes page faulting 966 * can be easily tracked. 967 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 968 * processes will be able to grab memory first. Do not change 969 * this balance without careful testing first. 970 */ 971void 972vm_waitpfault(void) 973{ 974 int s; 975 976 s = splvm(); 977 if (!vm_pages_needed) { 978 vm_pages_needed = 1; 979 wakeup(&vm_pages_needed); 980 } 981 tsleep(&cnt.v_free_count, PUSER, "pfault", 0); 982 splx(s); 983} 984 985/* 986 * vm_page_activate: 987 * 988 * Put the specified page on the active list (if appropriate). 989 * Ensure that act_count is at least ACT_INIT but do not otherwise 990 * mess with it. 991 * 992 * The page queues must be locked. 993 * This routine may not block. 994 */ 995void 996vm_page_activate(vm_page_t m) 997{ 998 int s; 999 1000 GIANT_REQUIRED; 1001 s = splvm(); 1002 if (m->queue != PQ_ACTIVE) { 1003 if ((m->queue - m->pc) == PQ_CACHE) 1004 cnt.v_reactivated++; 1005 vm_pageq_remove(m); 1006 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1007 if (m->act_count < ACT_INIT) 1008 m->act_count = ACT_INIT; 1009 vm_pageq_enqueue(PQ_ACTIVE, m); 1010 } 1011 } else { 1012 if (m->act_count < ACT_INIT) 1013 m->act_count = ACT_INIT; 1014 } 1015 splx(s); 1016} 1017 1018/* 1019 * vm_page_free_wakeup: 1020 * 1021 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 1022 * routine is called when a page has been added to the cache or free 1023 * queues. 1024 * 1025 * This routine may not block. 1026 * This routine must be called at splvm() 1027 */ 1028static __inline void 1029vm_page_free_wakeup(void) 1030{ 1031 /* 1032 * if pageout daemon needs pages, then tell it that there are 1033 * some free. 1034 */ 1035 if (vm_pageout_pages_needed && 1036 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 1037 wakeup(&vm_pageout_pages_needed); 1038 vm_pageout_pages_needed = 0; 1039 } 1040 /* 1041 * wakeup processes that are waiting on memory if we hit a 1042 * high water mark. And wakeup scheduler process if we have 1043 * lots of memory. this process will swapin processes. 1044 */ 1045 if (vm_pages_needed && !vm_page_count_min()) { 1046 vm_pages_needed = 0; 1047 wakeup(&cnt.v_free_count); 1048 } 1049} 1050 1051/* 1052 * vm_page_free_toq: 1053 * 1054 * Returns the given page to the PQ_FREE list, 1055 * disassociating it with any VM object. 1056 * 1057 * Object and page must be locked prior to entry. 1058 * This routine may not block. 1059 */ 1060 1061void 1062vm_page_free_toq(vm_page_t m) 1063{ 1064 int s; 1065 struct vpgqueues *pq; 1066 vm_object_t object = m->object; 1067 1068 GIANT_REQUIRED; 1069 s = splvm(); 1070 cnt.v_tfree++; 1071 1072 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1073 printf( 1074 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1075 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1076 m->hold_count); 1077 if ((m->queue - m->pc) == PQ_FREE) 1078 panic("vm_page_free: freeing free page"); 1079 else 1080 panic("vm_page_free: freeing busy page"); 1081 } 1082 1083 /* 1084 * unqueue, then remove page. Note that we cannot destroy 1085 * the page here because we do not want to call the pager's 1086 * callback routine until after we've put the page on the 1087 * appropriate free queue. 1088 */ 1089 vm_pageq_remove_nowakeup(m); 1090 vm_page_remove(m); 1091 1092 /* 1093 * If fictitious remove object association and 1094 * return, otherwise delay object association removal. 1095 */ 1096 if ((m->flags & PG_FICTITIOUS) != 0) { 1097 splx(s); 1098 return; 1099 } 1100 1101 m->valid = 0; 1102 vm_page_undirty(m); 1103 1104 if (m->wire_count != 0) { 1105 if (m->wire_count > 1) { 1106 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1107 m->wire_count, (long)m->pindex); 1108 } 1109 panic("vm_page_free: freeing wired page\n"); 1110 } 1111 1112 /* 1113 * If we've exhausted the object's resident pages we want to free 1114 * it up. 1115 */ 1116 if (object && 1117 (object->type == OBJT_VNODE) && 1118 ((object->flags & OBJ_DEAD) == 0) 1119 ) { 1120 struct vnode *vp = (struct vnode *)object->handle; 1121 1122 if (vp && VSHOULDFREE(vp)) 1123 vfree(vp); 1124 } 1125 1126 /* 1127 * Clear the UNMANAGED flag when freeing an unmanaged page. 1128 */ 1129 if (m->flags & PG_UNMANAGED) { 1130 m->flags &= ~PG_UNMANAGED; 1131 } else { 1132#ifdef __alpha__ 1133 pmap_page_is_free(m); 1134#endif 1135 } 1136 1137 if (m->hold_count != 0) { 1138 m->flags &= ~PG_ZERO; 1139 m->queue = PQ_HOLD; 1140 } else 1141 m->queue = PQ_FREE + m->pc; 1142 pq = &vm_page_queues[m->queue]; 1143 pq->lcnt++; 1144 ++(*pq->cnt); 1145 1146 /* 1147 * Put zero'd pages on the end ( where we look for zero'd pages 1148 * first ) and non-zerod pages at the head. 1149 */ 1150 if (m->flags & PG_ZERO) { 1151 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1152 ++vm_page_zero_count; 1153 } else { 1154 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1155 } 1156 vm_page_free_wakeup(); 1157 splx(s); 1158} 1159 1160/* 1161 * vm_page_unmanage: 1162 * 1163 * Prevent PV management from being done on the page. The page is 1164 * removed from the paging queues as if it were wired, and as a 1165 * consequence of no longer being managed the pageout daemon will not 1166 * touch it (since there is no way to locate the pte mappings for the 1167 * page). madvise() calls that mess with the pmap will also no longer 1168 * operate on the page. 1169 * 1170 * Beyond that the page is still reasonably 'normal'. Freeing the page 1171 * will clear the flag. 1172 * 1173 * This routine is used by OBJT_PHYS objects - objects using unswappable 1174 * physical memory as backing store rather then swap-backed memory and 1175 * will eventually be extended to support 4MB unmanaged physical 1176 * mappings. 1177 */ 1178void 1179vm_page_unmanage(vm_page_t m) 1180{ 1181 int s; 1182 1183 s = splvm(); 1184 if ((m->flags & PG_UNMANAGED) == 0) { 1185 if (m->wire_count == 0) 1186 vm_pageq_remove(m); 1187 } 1188 vm_page_flag_set(m, PG_UNMANAGED); 1189 splx(s); 1190} 1191 1192/* 1193 * vm_page_wire: 1194 * 1195 * Mark this page as wired down by yet 1196 * another map, removing it from paging queues 1197 * as necessary. 1198 * 1199 * The page queues must be locked. 1200 * This routine may not block. 1201 */ 1202void 1203vm_page_wire(vm_page_t m) 1204{ 1205 int s; 1206 1207 /* 1208 * Only bump the wire statistics if the page is not already wired, 1209 * and only unqueue the page if it is on some queue (if it is unmanaged 1210 * it is already off the queues). 1211 */ 1212 s = splvm(); 1213 if (m->wire_count == 0) { 1214 if ((m->flags & PG_UNMANAGED) == 0) 1215 vm_pageq_remove(m); 1216 cnt.v_wire_count++; 1217 } 1218 m->wire_count++; 1219 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1220 splx(s); 1221 vm_page_flag_set(m, PG_MAPPED); 1222} 1223 1224/* 1225 * vm_page_unwire: 1226 * 1227 * Release one wiring of this page, potentially 1228 * enabling it to be paged again. 1229 * 1230 * Many pages placed on the inactive queue should actually go 1231 * into the cache, but it is difficult to figure out which. What 1232 * we do instead, if the inactive target is well met, is to put 1233 * clean pages at the head of the inactive queue instead of the tail. 1234 * This will cause them to be moved to the cache more quickly and 1235 * if not actively re-referenced, freed more quickly. If we just 1236 * stick these pages at the end of the inactive queue, heavy filesystem 1237 * meta-data accesses can cause an unnecessary paging load on memory bound 1238 * processes. This optimization causes one-time-use metadata to be 1239 * reused more quickly. 1240 * 1241 * BUT, if we are in a low-memory situation we have no choice but to 1242 * put clean pages on the cache queue. 1243 * 1244 * A number of routines use vm_page_unwire() to guarantee that the page 1245 * will go into either the inactive or active queues, and will NEVER 1246 * be placed in the cache - for example, just after dirtying a page. 1247 * dirty pages in the cache are not allowed. 1248 * 1249 * The page queues must be locked. 1250 * This routine may not block. 1251 */ 1252void 1253vm_page_unwire(vm_page_t m, int activate) 1254{ 1255 int s; 1256 1257 s = splvm(); 1258 1259 if (m->wire_count > 0) { 1260 m->wire_count--; 1261 if (m->wire_count == 0) { 1262 cnt.v_wire_count--; 1263 if (m->flags & PG_UNMANAGED) { 1264 ; 1265 } else if (activate) 1266 vm_pageq_enqueue(PQ_ACTIVE, m); 1267 else { 1268 vm_page_flag_clear(m, PG_WINATCFLS); 1269 vm_pageq_enqueue(PQ_INACTIVE, m); 1270 } 1271 } 1272 } else { 1273 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1274 } 1275 splx(s); 1276} 1277 1278 1279/* 1280 * Move the specified page to the inactive queue. If the page has 1281 * any associated swap, the swap is deallocated. 1282 * 1283 * Normally athead is 0 resulting in LRU operation. athead is set 1284 * to 1 if we want this page to be 'as if it were placed in the cache', 1285 * except without unmapping it from the process address space. 1286 * 1287 * This routine may not block. 1288 */ 1289static __inline void 1290_vm_page_deactivate(vm_page_t m, int athead) 1291{ 1292 int s; 1293 1294 GIANT_REQUIRED; 1295 /* 1296 * Ignore if already inactive. 1297 */ 1298 if (m->queue == PQ_INACTIVE) 1299 return; 1300 1301 s = splvm(); 1302 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1303 if ((m->queue - m->pc) == PQ_CACHE) 1304 cnt.v_reactivated++; 1305 vm_page_flag_clear(m, PG_WINATCFLS); 1306 vm_pageq_remove(m); 1307 if (athead) 1308 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1309 else 1310 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1311 m->queue = PQ_INACTIVE; 1312 vm_page_queues[PQ_INACTIVE].lcnt++; 1313 cnt.v_inactive_count++; 1314 } 1315 splx(s); 1316} 1317 1318void 1319vm_page_deactivate(vm_page_t m) 1320{ 1321 _vm_page_deactivate(m, 0); 1322} 1323 1324/* 1325 * vm_page_try_to_cache: 1326 * 1327 * Returns 0 on failure, 1 on success 1328 */ 1329int 1330vm_page_try_to_cache(vm_page_t m) 1331{ 1332 GIANT_REQUIRED; 1333 1334 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1335 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1336 return (0); 1337 } 1338 vm_page_test_dirty(m); 1339 if (m->dirty) 1340 return (0); 1341 vm_page_cache(m); 1342 return (1); 1343} 1344 1345/* 1346 * vm_page_try_to_free() 1347 * 1348 * Attempt to free the page. If we cannot free it, we do nothing. 1349 * 1 is returned on success, 0 on failure. 1350 */ 1351int 1352vm_page_try_to_free(vm_page_t m) 1353{ 1354 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1355 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1356 return (0); 1357 } 1358 vm_page_test_dirty(m); 1359 if (m->dirty) 1360 return (0); 1361 vm_page_busy(m); 1362 vm_page_protect(m, VM_PROT_NONE); 1363 vm_page_free(m); 1364 return (1); 1365} 1366 1367/* 1368 * vm_page_cache 1369 * 1370 * Put the specified page onto the page cache queue (if appropriate). 1371 * 1372 * This routine may not block. 1373 */ 1374void 1375vm_page_cache(vm_page_t m) 1376{ 1377 int s; 1378 1379 GIANT_REQUIRED; 1380 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || m->wire_count) { 1381 printf("vm_page_cache: attempting to cache busy page\n"); 1382 return; 1383 } 1384 if ((m->queue - m->pc) == PQ_CACHE) 1385 return; 1386 1387 /* 1388 * Remove all pmaps and indicate that the page is not 1389 * writeable or mapped. 1390 */ 1391 vm_page_protect(m, VM_PROT_NONE); 1392 if (m->dirty != 0) { 1393 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1394 (long)m->pindex); 1395 } 1396 s = splvm(); 1397 vm_pageq_remove_nowakeup(m); 1398 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1399 vm_page_free_wakeup(); 1400 splx(s); 1401} 1402 1403/* 1404 * vm_page_dontneed 1405 * 1406 * Cache, deactivate, or do nothing as appropriate. This routine 1407 * is typically used by madvise() MADV_DONTNEED. 1408 * 1409 * Generally speaking we want to move the page into the cache so 1410 * it gets reused quickly. However, this can result in a silly syndrome 1411 * due to the page recycling too quickly. Small objects will not be 1412 * fully cached. On the otherhand, if we move the page to the inactive 1413 * queue we wind up with a problem whereby very large objects 1414 * unnecessarily blow away our inactive and cache queues. 1415 * 1416 * The solution is to move the pages based on a fixed weighting. We 1417 * either leave them alone, deactivate them, or move them to the cache, 1418 * where moving them to the cache has the highest weighting. 1419 * By forcing some pages into other queues we eventually force the 1420 * system to balance the queues, potentially recovering other unrelated 1421 * space from active. The idea is to not force this to happen too 1422 * often. 1423 */ 1424void 1425vm_page_dontneed(vm_page_t m) 1426{ 1427 static int dnweight; 1428 int dnw; 1429 int head; 1430 1431 GIANT_REQUIRED; 1432 dnw = ++dnweight; 1433 1434 /* 1435 * occassionally leave the page alone 1436 */ 1437 if ((dnw & 0x01F0) == 0 || 1438 m->queue == PQ_INACTIVE || 1439 m->queue - m->pc == PQ_CACHE 1440 ) { 1441 if (m->act_count >= ACT_INIT) 1442 --m->act_count; 1443 return; 1444 } 1445 1446 if (m->dirty == 0) 1447 vm_page_test_dirty(m); 1448 1449 if (m->dirty || (dnw & 0x0070) == 0) { 1450 /* 1451 * Deactivate the page 3 times out of 32. 1452 */ 1453 head = 0; 1454 } else { 1455 /* 1456 * Cache the page 28 times out of every 32. Note that 1457 * the page is deactivated instead of cached, but placed 1458 * at the head of the queue instead of the tail. 1459 */ 1460 head = 1; 1461 } 1462 _vm_page_deactivate(m, head); 1463} 1464 1465/* 1466 * Grab a page, waiting until we are waken up due to the page 1467 * changing state. We keep on waiting, if the page continues 1468 * to be in the object. If the page doesn't exist, allocate it. 1469 * 1470 * This routine may block. 1471 */ 1472vm_page_t 1473vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1474{ 1475 vm_page_t m; 1476 int s, generation; 1477 1478 GIANT_REQUIRED; 1479retrylookup: 1480 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1481 if (m->busy || (m->flags & PG_BUSY)) { 1482 generation = object->generation; 1483 1484 s = splvm(); 1485 while ((object->generation == generation) && 1486 (m->busy || (m->flags & PG_BUSY))) { 1487 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1488 tsleep(m, PVM, "pgrbwt", 0); 1489 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1490 splx(s); 1491 return NULL; 1492 } 1493 } 1494 splx(s); 1495 goto retrylookup; 1496 } else { 1497 vm_page_busy(m); 1498 return m; 1499 } 1500 } 1501 1502 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1503 if (m == NULL) { 1504 VM_WAIT; 1505 if ((allocflags & VM_ALLOC_RETRY) == 0) 1506 return NULL; 1507 goto retrylookup; 1508 } 1509 1510 return m; 1511} 1512 1513/* 1514 * Mapping function for valid bits or for dirty bits in 1515 * a page. May not block. 1516 * 1517 * Inputs are required to range within a page. 1518 */ 1519__inline int 1520vm_page_bits(int base, int size) 1521{ 1522 int first_bit; 1523 int last_bit; 1524 1525 KASSERT( 1526 base + size <= PAGE_SIZE, 1527 ("vm_page_bits: illegal base/size %d/%d", base, size) 1528 ); 1529 1530 if (size == 0) /* handle degenerate case */ 1531 return (0); 1532 1533 first_bit = base >> DEV_BSHIFT; 1534 last_bit = (base + size - 1) >> DEV_BSHIFT; 1535 1536 return ((2 << last_bit) - (1 << first_bit)); 1537} 1538 1539/* 1540 * vm_page_set_validclean: 1541 * 1542 * Sets portions of a page valid and clean. The arguments are expected 1543 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1544 * of any partial chunks touched by the range. The invalid portion of 1545 * such chunks will be zero'd. 1546 * 1547 * This routine may not block. 1548 * 1549 * (base + size) must be less then or equal to PAGE_SIZE. 1550 */ 1551void 1552vm_page_set_validclean(vm_page_t m, int base, int size) 1553{ 1554 int pagebits; 1555 int frag; 1556 int endoff; 1557 1558 GIANT_REQUIRED; 1559 if (size == 0) /* handle degenerate case */ 1560 return; 1561 1562 /* 1563 * If the base is not DEV_BSIZE aligned and the valid 1564 * bit is clear, we have to zero out a portion of the 1565 * first block. 1566 */ 1567 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1568 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1569 ) { 1570 pmap_zero_page_area( 1571 VM_PAGE_TO_PHYS(m), 1572 frag, 1573 base - frag 1574 ); 1575 } 1576 1577 /* 1578 * If the ending offset is not DEV_BSIZE aligned and the 1579 * valid bit is clear, we have to zero out a portion of 1580 * the last block. 1581 */ 1582 endoff = base + size; 1583 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1584 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1585 ) { 1586 pmap_zero_page_area( 1587 VM_PAGE_TO_PHYS(m), 1588 endoff, 1589 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1590 ); 1591 } 1592 1593 /* 1594 * Set valid, clear dirty bits. If validating the entire 1595 * page we can safely clear the pmap modify bit. We also 1596 * use this opportunity to clear the PG_NOSYNC flag. If a process 1597 * takes a write fault on a MAP_NOSYNC memory area the flag will 1598 * be set again. 1599 * 1600 * We set valid bits inclusive of any overlap, but we can only 1601 * clear dirty bits for DEV_BSIZE chunks that are fully within 1602 * the range. 1603 */ 1604 pagebits = vm_page_bits(base, size); 1605 m->valid |= pagebits; 1606#if 0 /* NOT YET */ 1607 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1608 frag = DEV_BSIZE - frag; 1609 base += frag; 1610 size -= frag; 1611 if (size < 0) 1612 size = 0; 1613 } 1614 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1615#endif 1616 m->dirty &= ~pagebits; 1617 if (base == 0 && size == PAGE_SIZE) { 1618 pmap_clear_modify(m); 1619 vm_page_flag_clear(m, PG_NOSYNC); 1620 } 1621} 1622 1623#if 0 1624 1625void 1626vm_page_set_dirty(vm_page_t m, int base, int size) 1627{ 1628 m->dirty |= vm_page_bits(base, size); 1629} 1630 1631#endif 1632 1633void 1634vm_page_clear_dirty(vm_page_t m, int base, int size) 1635{ 1636 GIANT_REQUIRED; 1637 m->dirty &= ~vm_page_bits(base, size); 1638} 1639 1640/* 1641 * vm_page_set_invalid: 1642 * 1643 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1644 * valid and dirty bits for the effected areas are cleared. 1645 * 1646 * May not block. 1647 */ 1648void 1649vm_page_set_invalid(vm_page_t m, int base, int size) 1650{ 1651 int bits; 1652 1653 GIANT_REQUIRED; 1654 bits = vm_page_bits(base, size); 1655 m->valid &= ~bits; 1656 m->dirty &= ~bits; 1657 m->object->generation++; 1658} 1659 1660/* 1661 * vm_page_zero_invalid() 1662 * 1663 * The kernel assumes that the invalid portions of a page contain 1664 * garbage, but such pages can be mapped into memory by user code. 1665 * When this occurs, we must zero out the non-valid portions of the 1666 * page so user code sees what it expects. 1667 * 1668 * Pages are most often semi-valid when the end of a file is mapped 1669 * into memory and the file's size is not page aligned. 1670 */ 1671void 1672vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1673{ 1674 int b; 1675 int i; 1676 1677 /* 1678 * Scan the valid bits looking for invalid sections that 1679 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1680 * valid bit may be set ) have already been zerod by 1681 * vm_page_set_validclean(). 1682 */ 1683 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1684 if (i == (PAGE_SIZE / DEV_BSIZE) || 1685 (m->valid & (1 << i)) 1686 ) { 1687 if (i > b) { 1688 pmap_zero_page_area( 1689 VM_PAGE_TO_PHYS(m), 1690 b << DEV_BSHIFT, 1691 (i - b) << DEV_BSHIFT 1692 ); 1693 } 1694 b = i + 1; 1695 } 1696 } 1697 1698 /* 1699 * setvalid is TRUE when we can safely set the zero'd areas 1700 * as being valid. We can do this if there are no cache consistancy 1701 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1702 */ 1703 if (setvalid) 1704 m->valid = VM_PAGE_BITS_ALL; 1705} 1706 1707/* 1708 * vm_page_is_valid: 1709 * 1710 * Is (partial) page valid? Note that the case where size == 0 1711 * will return FALSE in the degenerate case where the page is 1712 * entirely invalid, and TRUE otherwise. 1713 * 1714 * May not block. 1715 */ 1716int 1717vm_page_is_valid(vm_page_t m, int base, int size) 1718{ 1719 int bits = vm_page_bits(base, size); 1720 1721 if (m->valid && ((m->valid & bits) == bits)) 1722 return 1; 1723 else 1724 return 0; 1725} 1726 1727/* 1728 * update dirty bits from pmap/mmu. May not block. 1729 */ 1730void 1731vm_page_test_dirty(vm_page_t m) 1732{ 1733 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1734 vm_page_dirty(m); 1735 } 1736} 1737 1738#include "opt_ddb.h" 1739#ifdef DDB 1740#include <sys/kernel.h> 1741 1742#include <ddb/ddb.h> 1743 1744DB_SHOW_COMMAND(page, vm_page_print_page_info) 1745{ 1746 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1747 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1748 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1749 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1750 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1751 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1752 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1753 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1754 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1755 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1756} 1757 1758DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1759{ 1760 int i; 1761 db_printf("PQ_FREE:"); 1762 for (i = 0; i < PQ_L2_SIZE; i++) { 1763 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1764 } 1765 db_printf("\n"); 1766 1767 db_printf("PQ_CACHE:"); 1768 for (i = 0; i < PQ_L2_SIZE; i++) { 1769 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1770 } 1771 db_printf("\n"); 1772 1773 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1774 vm_page_queues[PQ_ACTIVE].lcnt, 1775 vm_page_queues[PQ_INACTIVE].lcnt); 1776} 1777#endif /* DDB */ 1778