vm_page.c revision 98849
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 98849 2002-06-26 03:37:47Z ken $ 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 */ 128static struct mtx vm_page_buckets_mtx; 129static struct vm_page **vm_page_buckets; /* Array of buckets */ 130static int vm_page_bucket_count; /* How big is array? */ 131static int vm_page_hash_mask; /* Mask for hash function */ 132 133vm_page_t vm_page_array = 0; 134int vm_page_array_size = 0; 135long first_page = 0; 136int vm_page_zero_count = 0; 137 138/* 139 * vm_set_page_size: 140 * 141 * Sets the page size, perhaps based upon the memory 142 * size. Must be called before any use of page-size 143 * dependent functions. 144 */ 145void 146vm_set_page_size(void) 147{ 148 if (cnt.v_page_size == 0) 149 cnt.v_page_size = PAGE_SIZE; 150 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) 151 panic("vm_set_page_size: page size not a power of two"); 152} 153 154/* 155 * vm_page_startup: 156 * 157 * Initializes the resident memory module. 158 * 159 * Allocates memory for the page cells, and 160 * for the object/offset-to-page hash table headers. 161 * Each page cell is initialized and placed on the free list. 162 */ 163vm_offset_t 164vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 165{ 166 vm_offset_t mapped; 167 struct vm_page **bucket; 168 vm_size_t npages, page_range; 169 vm_offset_t new_end; 170 int i; 171 vm_offset_t pa; 172 int nblocks; 173 vm_offset_t last_pa; 174 175 /* the biggest memory array is the second group of pages */ 176 vm_offset_t end; 177 vm_offset_t biggestone, biggestsize; 178 179 vm_offset_t total; 180 vm_size_t bootpages; 181 182 total = 0; 183 biggestsize = 0; 184 biggestone = 0; 185 nblocks = 0; 186 vaddr = round_page(vaddr); 187 188 for (i = 0; phys_avail[i + 1]; i += 2) { 189 phys_avail[i] = round_page(phys_avail[i]); 190 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 191 } 192 193 for (i = 0; phys_avail[i + 1]; i += 2) { 194 vm_size_t size = phys_avail[i + 1] - phys_avail[i]; 195 196 if (size > biggestsize) { 197 biggestone = i; 198 biggestsize = size; 199 } 200 ++nblocks; 201 total += size; 202 } 203 204 end = phys_avail[biggestone+1]; 205 206 /* 207 * Initialize the queue headers for the free queue, the active queue 208 * and the inactive queue. 209 */ 210 vm_pageq_init(); 211 212 /* 213 * Allocate memory for use when boot strapping the kernel memory allocator 214 */ 215 bootpages = UMA_BOOT_PAGES * UMA_SLAB_SIZE; 216 new_end = end - bootpages; 217 new_end = trunc_page(new_end); 218 mapped = pmap_map(&vaddr, new_end, end, 219 VM_PROT_READ | VM_PROT_WRITE); 220 bzero((caddr_t) mapped, end - new_end); 221 uma_startup((caddr_t)mapped); 222 223 end = new_end; 224 225 /* 226 * Allocate (and initialize) the hash table buckets. 227 * 228 * The number of buckets MUST BE a power of 2, and the actual value is 229 * the next power of 2 greater than the number of physical pages in 230 * the system. 231 * 232 * We make the hash table approximately 2x the number of pages to 233 * reduce the chain length. This is about the same size using the 234 * singly-linked list as the 1x hash table we were using before 235 * using TAILQ but the chain length will be smaller. 236 * 237 * Note: This computation can be tweaked if desired. 238 */ 239 if (vm_page_bucket_count == 0) { 240 vm_page_bucket_count = 1; 241 while (vm_page_bucket_count < atop(total)) 242 vm_page_bucket_count <<= 1; 243 } 244 vm_page_bucket_count <<= 1; 245 vm_page_hash_mask = vm_page_bucket_count - 1; 246 247 /* 248 * Validate these addresses. 249 */ 250 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 251 new_end = trunc_page(new_end); 252 mapped = pmap_map(&vaddr, new_end, end, 253 VM_PROT_READ | VM_PROT_WRITE); 254 bzero((caddr_t) mapped, end - new_end); 255 256 mtx_init(&vm_page_buckets_mtx, "vm page buckets mutex", NULL, MTX_SPIN); 257 vm_page_buckets = (struct vm_page **)mapped; 258 bucket = vm_page_buckets; 259 for (i = 0; i < vm_page_bucket_count; i++) { 260 *bucket = NULL; 261 bucket++; 262 } 263 264 /* 265 * Compute the number of pages of memory that will be available for 266 * use (taking into account the overhead of a page structure per 267 * page). 268 */ 269 first_page = phys_avail[0] / PAGE_SIZE; 270 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 271 npages = (total - (page_range * sizeof(struct vm_page)) - 272 (end - new_end)) / PAGE_SIZE; 273 end = new_end; 274 275 /* 276 * Initialize the mem entry structures now, and put them in the free 277 * queue. 278 */ 279 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 280 mapped = pmap_map(&vaddr, new_end, end, 281 VM_PROT_READ | VM_PROT_WRITE); 282 vm_page_array = (vm_page_t) mapped; 283 284 /* 285 * Clear all of the page structures 286 */ 287 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 288 vm_page_array_size = page_range; 289 290 /* 291 * Construct the free queue(s) in descending order (by physical 292 * address) so that the first 16MB of physical memory is allocated 293 * last rather than first. On large-memory machines, this avoids 294 * the exhaustion of low physical memory before isa_dmainit has run. 295 */ 296 cnt.v_page_count = 0; 297 cnt.v_free_count = 0; 298 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 299 pa = phys_avail[i]; 300 if (i == biggestone) 301 last_pa = new_end; 302 else 303 last_pa = phys_avail[i + 1]; 304 while (pa < last_pa && npages-- > 0) { 305 vm_pageq_add_new_page(pa); 306 pa += PAGE_SIZE; 307 } 308 } 309 return (vaddr); 310} 311 312/* 313 * vm_page_hash: 314 * 315 * Distributes the object/offset key pair among hash buckets. 316 * 317 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 318 * This routine may not block. 319 * 320 * We try to randomize the hash based on the object to spread the pages 321 * out in the hash table without it costing us too much. 322 */ 323static __inline int 324vm_page_hash(vm_object_t object, vm_pindex_t pindex) 325{ 326 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 327 328 return (i & vm_page_hash_mask); 329} 330 331void 332vm_page_flag_set(vm_page_t m, unsigned short bits) 333{ 334 GIANT_REQUIRED; 335 m->flags |= bits; 336} 337 338void 339vm_page_flag_clear(vm_page_t m, unsigned short bits) 340{ 341 GIANT_REQUIRED; 342 m->flags &= ~bits; 343} 344 345void 346vm_page_busy(vm_page_t m) 347{ 348 KASSERT((m->flags & PG_BUSY) == 0, 349 ("vm_page_busy: page already busy!!!")); 350 vm_page_flag_set(m, PG_BUSY); 351} 352 353/* 354 * vm_page_flash: 355 * 356 * wakeup anyone waiting for the page. 357 */ 358void 359vm_page_flash(vm_page_t m) 360{ 361 if (m->flags & PG_WANTED) { 362 vm_page_flag_clear(m, PG_WANTED); 363 wakeup(m); 364 } 365} 366 367/* 368 * vm_page_wakeup: 369 * 370 * clear the PG_BUSY flag and wakeup anyone waiting for the 371 * page. 372 * 373 */ 374void 375vm_page_wakeup(vm_page_t m) 376{ 377 KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!")); 378 vm_page_flag_clear(m, PG_BUSY); 379 vm_page_flash(m); 380} 381 382/* 383 * 384 * 385 */ 386void 387vm_page_io_start(vm_page_t m) 388{ 389 GIANT_REQUIRED; 390 m->busy++; 391} 392 393void 394vm_page_io_finish(vm_page_t m) 395{ 396 GIANT_REQUIRED; 397 m->busy--; 398 if (m->busy == 0) 399 vm_page_flash(m); 400} 401 402/* 403 * Keep page from being freed by the page daemon 404 * much of the same effect as wiring, except much lower 405 * overhead and should be used only for *very* temporary 406 * holding ("wiring"). 407 */ 408void 409vm_page_hold(vm_page_t mem) 410{ 411 GIANT_REQUIRED; 412 mem->hold_count++; 413} 414 415void 416vm_page_unhold(vm_page_t mem) 417{ 418 GIANT_REQUIRED; 419 --mem->hold_count; 420 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 421 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 422 vm_page_free_toq(mem); 423} 424 425/* 426 * vm_page_protect: 427 * 428 * Reduce the protection of a page. This routine never raises the 429 * protection and therefore can be safely called if the page is already 430 * at VM_PROT_NONE (it will be a NOP effectively ). 431 */ 432void 433vm_page_protect(vm_page_t mem, int prot) 434{ 435 if (prot == VM_PROT_NONE) { 436 if (mem->flags & (PG_WRITEABLE|PG_MAPPED)) { 437 pmap_page_protect(mem, VM_PROT_NONE); 438 vm_page_flag_clear(mem, PG_WRITEABLE|PG_MAPPED); 439 } 440 } else if ((prot == VM_PROT_READ) && (mem->flags & PG_WRITEABLE)) { 441 pmap_page_protect(mem, VM_PROT_READ); 442 vm_page_flag_clear(mem, PG_WRITEABLE); 443 } 444} 445/* 446 * vm_page_zero_fill: 447 * 448 * Zero-fill the specified page. 449 * Written as a standard pagein routine, to 450 * be used by the zero-fill object. 451 */ 452boolean_t 453vm_page_zero_fill(vm_page_t m) 454{ 455 pmap_zero_page(m); 456 return (TRUE); 457} 458 459/* 460 * vm_page_zero_fill_area: 461 * 462 * Like vm_page_zero_fill but only fill the specified area. 463 */ 464boolean_t 465vm_page_zero_fill_area(vm_page_t m, int off, int size) 466{ 467 pmap_zero_page_area(m, off, size); 468 return (TRUE); 469} 470 471/* 472 * vm_page_copy: 473 * 474 * Copy one page to another 475 */ 476void 477vm_page_copy(vm_page_t src_m, vm_page_t dest_m) 478{ 479 pmap_copy_page(src_m, dest_m); 480 dest_m->valid = VM_PAGE_BITS_ALL; 481} 482 483/* 484 * vm_page_free: 485 * 486 * Free a page 487 * 488 * The clearing of PG_ZERO is a temporary safety until the code can be 489 * reviewed to determine that PG_ZERO is being properly cleared on 490 * write faults or maps. PG_ZERO was previously cleared in 491 * vm_page_alloc(). 492 */ 493void 494vm_page_free(vm_page_t m) 495{ 496 vm_page_flag_clear(m, PG_ZERO); 497 vm_page_free_toq(m); 498 vm_page_zero_idle_wakeup(); 499} 500 501/* 502 * vm_page_free_zero: 503 * 504 * Free a page to the zerod-pages queue 505 */ 506void 507vm_page_free_zero(vm_page_t m) 508{ 509 vm_page_flag_set(m, PG_ZERO); 510 vm_page_free_toq(m); 511} 512 513/* 514 * vm_page_sleep_busy: 515 * 516 * Wait until page is no longer PG_BUSY or (if also_m_busy is TRUE) 517 * m->busy is zero. Returns TRUE if it had to sleep ( including if 518 * it almost had to sleep and made temporary spl*() mods), FALSE 519 * otherwise. 520 * 521 * This routine assumes that interrupts can only remove the busy 522 * status from a page, not set the busy status or change it from 523 * PG_BUSY to m->busy or vise versa (which would create a timing 524 * window). 525 */ 526int 527vm_page_sleep_busy(vm_page_t m, int also_m_busy, const char *msg) 528{ 529 GIANT_REQUIRED; 530 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 531 int s = splvm(); 532 if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) { 533 /* 534 * Page is busy. Wait and retry. 535 */ 536 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 537 tsleep(m, PVM, msg, 0); 538 } 539 splx(s); 540 return (TRUE); 541 /* not reached */ 542 } 543 return (FALSE); 544} 545/* 546 * vm_page_dirty: 547 * 548 * make page all dirty 549 */ 550void 551vm_page_dirty(vm_page_t m) 552{ 553 KASSERT(m->queue - m->pc != PQ_CACHE, 554 ("vm_page_dirty: page in cache!")); 555 m->dirty = VM_PAGE_BITS_ALL; 556} 557 558/* 559 * vm_page_undirty: 560 * 561 * Set page to not be dirty. Note: does not clear pmap modify bits 562 */ 563void 564vm_page_undirty(vm_page_t m) 565{ 566 m->dirty = 0; 567} 568 569/* 570 * vm_page_insert: [ internal use only ] 571 * 572 * Inserts the given mem entry into the object and object list. 573 * 574 * The pagetables are not updated but will presumably fault the page 575 * in if necessary, or if a kernel page the caller will at some point 576 * enter the page into the kernel's pmap. We are not allowed to block 577 * here so we *can't* do this anyway. 578 * 579 * The object and page must be locked, and must be splhigh. 580 * This routine may not block. 581 */ 582void 583vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 584{ 585 struct vm_page **bucket; 586 587 GIANT_REQUIRED; 588 589 if (m->object != NULL) 590 panic("vm_page_insert: already inserted"); 591 592 /* 593 * Record the object/offset pair in this page 594 */ 595 m->object = object; 596 m->pindex = pindex; 597 598 /* 599 * Insert it into the object_object/offset hash table 600 */ 601 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 602 mtx_lock_spin(&vm_page_buckets_mtx); 603 m->hnext = *bucket; 604 *bucket = m; 605 mtx_unlock_spin(&vm_page_buckets_mtx); 606 607 /* 608 * Now link into the object's list of backed pages. 609 */ 610 TAILQ_INSERT_TAIL(&object->memq, m, listq); 611 object->generation++; 612 613 /* 614 * show that the object has one more resident page. 615 */ 616 object->resident_page_count++; 617 618 /* 619 * Since we are inserting a new and possibly dirty page, 620 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 621 */ 622 if (m->flags & PG_WRITEABLE) 623 vm_object_set_writeable_dirty(object); 624} 625 626/* 627 * vm_page_remove: 628 * NOTE: used by device pager as well -wfj 629 * 630 * Removes the given mem entry from the object/offset-page 631 * table and the object page list, but do not invalidate/terminate 632 * the backing store. 633 * 634 * The object and page must be locked, and at splhigh. 635 * The underlying pmap entry (if any) is NOT removed here. 636 * This routine may not block. 637 */ 638void 639vm_page_remove(vm_page_t m) 640{ 641 vm_object_t object; 642 vm_page_t *bucket; 643 644 GIANT_REQUIRED; 645 646 if (m->object == NULL) 647 return; 648 649 if ((m->flags & PG_BUSY) == 0) { 650 panic("vm_page_remove: page not busy"); 651 } 652 653 /* 654 * Basically destroy the page. 655 */ 656 vm_page_wakeup(m); 657 658 object = m->object; 659 660 /* 661 * Remove from the object_object/offset hash table. The object 662 * must be on the hash queue, we will panic if it isn't 663 */ 664 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 665 mtx_lock_spin(&vm_page_buckets_mtx); 666 while (*bucket != m) { 667 if (*bucket == NULL) 668 panic("vm_page_remove(): page not found in hash"); 669 bucket = &(*bucket)->hnext; 670 } 671 *bucket = m->hnext; 672 m->hnext = NULL; 673 mtx_unlock_spin(&vm_page_buckets_mtx); 674 675 /* 676 * Now remove from the object's list of backed pages. 677 */ 678 TAILQ_REMOVE(&object->memq, m, listq); 679 680 /* 681 * And show that the object has one fewer resident page. 682 */ 683 object->resident_page_count--; 684 object->generation++; 685 686 m->object = NULL; 687} 688 689/* 690 * vm_page_lookup: 691 * 692 * Returns the page associated with the object/offset 693 * pair specified; if none is found, NULL is returned. 694 * 695 * The object must be locked. No side effects. 696 * This routine may not block. 697 * This is a critical path routine 698 */ 699vm_page_t 700vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 701{ 702 vm_page_t m; 703 struct vm_page **bucket; 704 705 /* 706 * Search the hash table for this object/offset pair 707 */ 708 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 709 mtx_lock_spin(&vm_page_buckets_mtx); 710 for (m = *bucket; m != NULL; m = m->hnext) 711 if (m->object == object && m->pindex == pindex) 712 break; 713 mtx_unlock_spin(&vm_page_buckets_mtx); 714 return (m); 715} 716 717/* 718 * vm_page_rename: 719 * 720 * Move the given memory entry from its 721 * current object to the specified target object/offset. 722 * 723 * The object must be locked. 724 * This routine may not block. 725 * 726 * Note: this routine will raise itself to splvm(), the caller need not. 727 * 728 * Note: swap associated with the page must be invalidated by the move. We 729 * have to do this for several reasons: (1) we aren't freeing the 730 * page, (2) we are dirtying the page, (3) the VM system is probably 731 * moving the page from object A to B, and will then later move 732 * the backing store from A to B and we can't have a conflict. 733 * 734 * Note: we *always* dirty the page. It is necessary both for the 735 * fact that we moved it, and because we may be invalidating 736 * swap. If the page is on the cache, we have to deactivate it 737 * or vm_page_dirty() will panic. Dirty pages are not allowed 738 * on the cache. 739 */ 740void 741vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 742{ 743 int s; 744 745 s = splvm(); 746 vm_page_remove(m); 747 vm_page_insert(m, new_object, new_pindex); 748 if (m->queue - m->pc == PQ_CACHE) 749 vm_page_deactivate(m); 750 vm_page_dirty(m); 751 splx(s); 752} 753 754/* 755 * vm_page_select_cache: 756 * 757 * Find a page on the cache queue with color optimization. As pages 758 * might be found, but not applicable, they are deactivated. This 759 * keeps us from using potentially busy cached pages. 760 * 761 * This routine must be called at splvm(). 762 * This routine may not block. 763 */ 764static vm_page_t 765vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 766{ 767 vm_page_t m; 768 769 GIANT_REQUIRED; 770 while (TRUE) { 771 m = vm_pageq_find( 772 PQ_CACHE, 773 (pindex + object->pg_color) & PQ_L2_MASK, 774 FALSE 775 ); 776 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 777 m->hold_count || m->wire_count)) { 778 vm_page_deactivate(m); 779 continue; 780 } 781 return m; 782 } 783} 784 785/* 786 * vm_page_select_free: 787 * 788 * Find a free or zero page, with specified preference. 789 * 790 * This routine must be called at splvm(). 791 * This routine may not block. 792 */ 793static __inline vm_page_t 794vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 795{ 796 vm_page_t m; 797 798 m = vm_pageq_find( 799 PQ_FREE, 800 (pindex + object->pg_color) & PQ_L2_MASK, 801 prefer_zero 802 ); 803 return (m); 804} 805 806/* 807 * vm_page_alloc: 808 * 809 * Allocate and return a memory cell associated 810 * with this VM object/offset pair. 811 * 812 * page_req classes: 813 * VM_ALLOC_NORMAL normal process request 814 * VM_ALLOC_SYSTEM system *really* needs a page 815 * VM_ALLOC_INTERRUPT interrupt time request 816 * VM_ALLOC_ZERO zero page 817 * 818 * This routine may not block. 819 * 820 * Additional special handling is required when called from an 821 * interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with 822 * the page cache in this case. 823 */ 824vm_page_t 825vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 826{ 827 vm_page_t m = NULL; 828 boolean_t prefer_zero; 829 int s; 830 831 GIANT_REQUIRED; 832 833 KASSERT(!vm_page_lookup(object, pindex), 834 ("vm_page_alloc: page already allocated")); 835 836 prefer_zero = (page_req & VM_ALLOC_ZERO) != 0 ? TRUE : FALSE; 837 page_req &= ~VM_ALLOC_ZERO; 838 839 /* 840 * The pager is allowed to eat deeper into the free page list. 841 */ 842 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { 843 page_req = VM_ALLOC_SYSTEM; 844 }; 845 846 s = splvm(); 847 848loop: 849 if (cnt.v_free_count > cnt.v_free_reserved) { 850 /* 851 * Allocate from the free queue if there are plenty of pages 852 * in it. 853 */ 854 855 m = vm_page_select_free(object, pindex, prefer_zero); 856 } else if ( 857 (page_req == VM_ALLOC_SYSTEM && 858 cnt.v_cache_count == 0 && 859 cnt.v_free_count > cnt.v_interrupt_free_min) || 860 (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count > 0) 861 ) { 862 /* 863 * Interrupt or system, dig deeper into the free list. 864 */ 865 m = vm_page_select_free(object, pindex, FALSE); 866 } else if (page_req != VM_ALLOC_INTERRUPT) { 867 /* 868 * Allocatable from cache (non-interrupt only). On success, 869 * we must free the page and try again, thus ensuring that 870 * cnt.v_*_free_min counters are replenished. 871 */ 872 m = vm_page_select_cache(object, pindex); 873 if (m == NULL) { 874 splx(s); 875#if defined(DIAGNOSTIC) 876 if (cnt.v_cache_count > 0) 877 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", cnt.v_cache_count); 878#endif 879 vm_pageout_deficit++; 880 pagedaemon_wakeup(); 881 return (NULL); 882 } 883 KASSERT(m->dirty == 0, ("Found dirty cache page %p", m)); 884 vm_page_busy(m); 885 vm_page_protect(m, VM_PROT_NONE); 886 vm_page_free(m); 887 goto loop; 888 } else { 889 /* 890 * Not allocatable from cache from interrupt, give up. 891 */ 892 splx(s); 893 vm_pageout_deficit++; 894 pagedaemon_wakeup(); 895 return (NULL); 896 } 897 898 /* 899 * At this point we had better have found a good page. 900 */ 901 902 KASSERT( 903 m != NULL, 904 ("vm_page_alloc(): missing page on free queue\n") 905 ); 906 907 /* 908 * Remove from free queue 909 */ 910 911 vm_pageq_remove_nowakeup(m); 912 913 /* 914 * Initialize structure. Only the PG_ZERO flag is inherited. 915 */ 916 if (m->flags & PG_ZERO) { 917 vm_page_zero_count--; 918 m->flags = PG_ZERO | PG_BUSY; 919 } else { 920 m->flags = PG_BUSY; 921 } 922 m->wire_count = 0; 923 m->hold_count = 0; 924 m->act_count = 0; 925 m->busy = 0; 926 m->valid = 0; 927 KASSERT(m->dirty == 0, ("vm_page_alloc: free/cache page %p was dirty", m)); 928 929 /* 930 * vm_page_insert() is safe prior to the splx(). Note also that 931 * inserting a page here does not insert it into the pmap (which 932 * could cause us to block allocating memory). We cannot block 933 * anywhere. 934 */ 935 vm_page_insert(m, object, pindex); 936 937 /* 938 * Don't wakeup too often - wakeup the pageout daemon when 939 * we would be nearly out of memory. 940 */ 941 if (vm_paging_needed()) 942 pagedaemon_wakeup(); 943 944 splx(s); 945 return (m); 946} 947 948/* 949 * vm_wait: (also see VM_WAIT macro) 950 * 951 * Block until free pages are available for allocation 952 * - Called in various places before memory allocations. 953 */ 954void 955vm_wait(void) 956{ 957 int s; 958 959 s = splvm(); 960 if (curproc == pageproc) { 961 vm_pageout_pages_needed = 1; 962 tsleep(&vm_pageout_pages_needed, PSWP, "VMWait", 0); 963 } else { 964 if (!vm_pages_needed) { 965 vm_pages_needed = 1; 966 wakeup(&vm_pages_needed); 967 } 968 tsleep(&cnt.v_free_count, PVM, "vmwait", 0); 969 } 970 splx(s); 971} 972 973/* 974 * vm_waitpfault: (also see VM_WAITPFAULT macro) 975 * 976 * Block until free pages are available for allocation 977 * - Called only in vm_fault so that processes page faulting 978 * can be easily tracked. 979 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing 980 * processes will be able to grab memory first. Do not change 981 * this balance without careful testing first. 982 */ 983void 984vm_waitpfault(void) 985{ 986 int s; 987 988 s = splvm(); 989 if (!vm_pages_needed) { 990 vm_pages_needed = 1; 991 wakeup(&vm_pages_needed); 992 } 993 tsleep(&cnt.v_free_count, PUSER, "pfault", 0); 994 splx(s); 995} 996 997/* 998 * vm_page_activate: 999 * 1000 * Put the specified page on the active list (if appropriate). 1001 * Ensure that act_count is at least ACT_INIT but do not otherwise 1002 * mess with it. 1003 * 1004 * The page queues must be locked. 1005 * This routine may not block. 1006 */ 1007void 1008vm_page_activate(vm_page_t m) 1009{ 1010 int s; 1011 1012 GIANT_REQUIRED; 1013 s = splvm(); 1014 if (m->queue != PQ_ACTIVE) { 1015 if ((m->queue - m->pc) == PQ_CACHE) 1016 cnt.v_reactivated++; 1017 vm_pageq_remove(m); 1018 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1019 if (m->act_count < ACT_INIT) 1020 m->act_count = ACT_INIT; 1021 vm_pageq_enqueue(PQ_ACTIVE, m); 1022 } 1023 } else { 1024 if (m->act_count < ACT_INIT) 1025 m->act_count = ACT_INIT; 1026 } 1027 splx(s); 1028} 1029 1030/* 1031 * vm_page_free_wakeup: 1032 * 1033 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 1034 * routine is called when a page has been added to the cache or free 1035 * queues. 1036 * 1037 * This routine may not block. 1038 * This routine must be called at splvm() 1039 */ 1040static __inline void 1041vm_page_free_wakeup(void) 1042{ 1043 /* 1044 * if pageout daemon needs pages, then tell it that there are 1045 * some free. 1046 */ 1047 if (vm_pageout_pages_needed && 1048 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { 1049 wakeup(&vm_pageout_pages_needed); 1050 vm_pageout_pages_needed = 0; 1051 } 1052 /* 1053 * wakeup processes that are waiting on memory if we hit a 1054 * high water mark. And wakeup scheduler process if we have 1055 * lots of memory. this process will swapin processes. 1056 */ 1057 if (vm_pages_needed && !vm_page_count_min()) { 1058 vm_pages_needed = 0; 1059 wakeup(&cnt.v_free_count); 1060 } 1061} 1062 1063/* 1064 * vm_page_free_toq: 1065 * 1066 * Returns the given page to the PQ_FREE list, 1067 * disassociating it with any VM object. 1068 * 1069 * Object and page must be locked prior to entry. 1070 * This routine may not block. 1071 */ 1072 1073void 1074vm_page_free_toq(vm_page_t m) 1075{ 1076 int s; 1077 struct vpgqueues *pq; 1078 vm_object_t object = m->object; 1079 1080 GIANT_REQUIRED; 1081 s = splvm(); 1082 cnt.v_tfree++; 1083 1084 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1085 printf( 1086 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1087 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1088 m->hold_count); 1089 if ((m->queue - m->pc) == PQ_FREE) 1090 panic("vm_page_free: freeing free page"); 1091 else 1092 panic("vm_page_free: freeing busy page"); 1093 } 1094 1095 /* 1096 * unqueue, then remove page. Note that we cannot destroy 1097 * the page here because we do not want to call the pager's 1098 * callback routine until after we've put the page on the 1099 * appropriate free queue. 1100 */ 1101 vm_pageq_remove_nowakeup(m); 1102 vm_page_remove(m); 1103 1104 /* 1105 * If fictitious remove object association and 1106 * return, otherwise delay object association removal. 1107 */ 1108 if ((m->flags & PG_FICTITIOUS) != 0) { 1109 splx(s); 1110 return; 1111 } 1112 1113 m->valid = 0; 1114 vm_page_undirty(m); 1115 1116 if (m->wire_count != 0) { 1117 if (m->wire_count > 1) { 1118 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1119 m->wire_count, (long)m->pindex); 1120 } 1121 panic("vm_page_free: freeing wired page\n"); 1122 } 1123 1124 /* 1125 * If we've exhausted the object's resident pages we want to free 1126 * it up. 1127 */ 1128 if (object && 1129 (object->type == OBJT_VNODE) && 1130 ((object->flags & OBJ_DEAD) == 0) 1131 ) { 1132 struct vnode *vp = (struct vnode *)object->handle; 1133 1134 if (vp && VSHOULDFREE(vp)) 1135 vfree(vp); 1136 } 1137 1138 /* 1139 * Clear the UNMANAGED flag when freeing an unmanaged page. 1140 */ 1141 if (m->flags & PG_UNMANAGED) { 1142 m->flags &= ~PG_UNMANAGED; 1143 } else { 1144#ifdef __alpha__ 1145 pmap_page_is_free(m); 1146#endif 1147 } 1148 1149 if (m->hold_count != 0) { 1150 m->flags &= ~PG_ZERO; 1151 m->queue = PQ_HOLD; 1152 } else 1153 m->queue = PQ_FREE + m->pc; 1154 pq = &vm_page_queues[m->queue]; 1155 pq->lcnt++; 1156 ++(*pq->cnt); 1157 1158 /* 1159 * Put zero'd pages on the end ( where we look for zero'd pages 1160 * first ) and non-zerod pages at the head. 1161 */ 1162 if (m->flags & PG_ZERO) { 1163 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1164 ++vm_page_zero_count; 1165 } else { 1166 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1167 } 1168 vm_page_free_wakeup(); 1169 splx(s); 1170} 1171 1172/* 1173 * vm_page_unmanage: 1174 * 1175 * Prevent PV management from being done on the page. The page is 1176 * removed from the paging queues as if it were wired, and as a 1177 * consequence of no longer being managed the pageout daemon will not 1178 * touch it (since there is no way to locate the pte mappings for the 1179 * page). madvise() calls that mess with the pmap will also no longer 1180 * operate on the page. 1181 * 1182 * Beyond that the page is still reasonably 'normal'. Freeing the page 1183 * will clear the flag. 1184 * 1185 * This routine is used by OBJT_PHYS objects - objects using unswappable 1186 * physical memory as backing store rather then swap-backed memory and 1187 * will eventually be extended to support 4MB unmanaged physical 1188 * mappings. 1189 */ 1190void 1191vm_page_unmanage(vm_page_t m) 1192{ 1193 int s; 1194 1195 s = splvm(); 1196 if ((m->flags & PG_UNMANAGED) == 0) { 1197 if (m->wire_count == 0) 1198 vm_pageq_remove(m); 1199 } 1200 vm_page_flag_set(m, PG_UNMANAGED); 1201 splx(s); 1202} 1203 1204/* 1205 * vm_page_wire: 1206 * 1207 * Mark this page as wired down by yet 1208 * another map, removing it from paging queues 1209 * as necessary. 1210 * 1211 * The page queues must be locked. 1212 * This routine may not block. 1213 */ 1214void 1215vm_page_wire(vm_page_t m) 1216{ 1217 int s; 1218 1219 /* 1220 * Only bump the wire statistics if the page is not already wired, 1221 * and only unqueue the page if it is on some queue (if it is unmanaged 1222 * it is already off the queues). 1223 */ 1224 s = splvm(); 1225 if (m->wire_count == 0) { 1226 if ((m->flags & PG_UNMANAGED) == 0) 1227 vm_pageq_remove(m); 1228 cnt.v_wire_count++; 1229 } 1230 m->wire_count++; 1231 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); 1232 splx(s); 1233 vm_page_flag_set(m, PG_MAPPED); 1234} 1235 1236/* 1237 * vm_page_unwire: 1238 * 1239 * Release one wiring of this page, potentially 1240 * enabling it to be paged again. 1241 * 1242 * Many pages placed on the inactive queue should actually go 1243 * into the cache, but it is difficult to figure out which. What 1244 * we do instead, if the inactive target is well met, is to put 1245 * clean pages at the head of the inactive queue instead of the tail. 1246 * This will cause them to be moved to the cache more quickly and 1247 * if not actively re-referenced, freed more quickly. If we just 1248 * stick these pages at the end of the inactive queue, heavy filesystem 1249 * meta-data accesses can cause an unnecessary paging load on memory bound 1250 * processes. This optimization causes one-time-use metadata to be 1251 * reused more quickly. 1252 * 1253 * BUT, if we are in a low-memory situation we have no choice but to 1254 * put clean pages on the cache queue. 1255 * 1256 * A number of routines use vm_page_unwire() to guarantee that the page 1257 * will go into either the inactive or active queues, and will NEVER 1258 * be placed in the cache - for example, just after dirtying a page. 1259 * dirty pages in the cache are not allowed. 1260 * 1261 * The page queues must be locked. 1262 * This routine may not block. 1263 */ 1264void 1265vm_page_unwire(vm_page_t m, int activate) 1266{ 1267 int s; 1268 1269 s = splvm(); 1270 1271 if (m->wire_count > 0) { 1272 m->wire_count--; 1273 if (m->wire_count == 0) { 1274 cnt.v_wire_count--; 1275 if (m->flags & PG_UNMANAGED) { 1276 ; 1277 } else if (activate) 1278 vm_pageq_enqueue(PQ_ACTIVE, m); 1279 else { 1280 vm_page_flag_clear(m, PG_WINATCFLS); 1281 vm_pageq_enqueue(PQ_INACTIVE, m); 1282 } 1283 } 1284 } else { 1285 panic("vm_page_unwire: invalid wire count: %d\n", m->wire_count); 1286 } 1287 splx(s); 1288} 1289 1290 1291/* 1292 * Move the specified page to the inactive queue. If the page has 1293 * any associated swap, the swap is deallocated. 1294 * 1295 * Normally athead is 0 resulting in LRU operation. athead is set 1296 * to 1 if we want this page to be 'as if it were placed in the cache', 1297 * except without unmapping it from the process address space. 1298 * 1299 * This routine may not block. 1300 */ 1301static __inline void 1302_vm_page_deactivate(vm_page_t m, int athead) 1303{ 1304 int s; 1305 1306 GIANT_REQUIRED; 1307 /* 1308 * Ignore if already inactive. 1309 */ 1310 if (m->queue == PQ_INACTIVE) 1311 return; 1312 1313 s = splvm(); 1314 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1315 if ((m->queue - m->pc) == PQ_CACHE) 1316 cnt.v_reactivated++; 1317 vm_page_flag_clear(m, PG_WINATCFLS); 1318 vm_pageq_remove(m); 1319 if (athead) 1320 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1321 else 1322 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1323 m->queue = PQ_INACTIVE; 1324 vm_page_queues[PQ_INACTIVE].lcnt++; 1325 cnt.v_inactive_count++; 1326 } 1327 splx(s); 1328} 1329 1330void 1331vm_page_deactivate(vm_page_t m) 1332{ 1333 _vm_page_deactivate(m, 0); 1334} 1335 1336/* 1337 * vm_page_try_to_cache: 1338 * 1339 * Returns 0 on failure, 1 on success 1340 */ 1341int 1342vm_page_try_to_cache(vm_page_t m) 1343{ 1344 GIANT_REQUIRED; 1345 1346 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1347 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1348 return (0); 1349 } 1350 vm_page_test_dirty(m); 1351 if (m->dirty) 1352 return (0); 1353 vm_page_cache(m); 1354 return (1); 1355} 1356 1357/* 1358 * vm_page_try_to_free() 1359 * 1360 * Attempt to free the page. If we cannot free it, we do nothing. 1361 * 1 is returned on success, 0 on failure. 1362 */ 1363int 1364vm_page_try_to_free(vm_page_t m) 1365{ 1366 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1367 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1368 return (0); 1369 } 1370 vm_page_test_dirty(m); 1371 if (m->dirty) 1372 return (0); 1373 vm_page_busy(m); 1374 vm_page_protect(m, VM_PROT_NONE); 1375 vm_page_free(m); 1376 return (1); 1377} 1378 1379/* 1380 * vm_page_cache 1381 * 1382 * Put the specified page onto the page cache queue (if appropriate). 1383 * 1384 * This routine may not block. 1385 */ 1386void 1387vm_page_cache(vm_page_t m) 1388{ 1389 int s; 1390 1391 GIANT_REQUIRED; 1392 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || m->wire_count) { 1393 printf("vm_page_cache: attempting to cache busy page\n"); 1394 return; 1395 } 1396 if ((m->queue - m->pc) == PQ_CACHE) 1397 return; 1398 1399 /* 1400 * Remove all pmaps and indicate that the page is not 1401 * writeable or mapped. 1402 */ 1403 vm_page_protect(m, VM_PROT_NONE); 1404 if (m->dirty != 0) { 1405 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1406 (long)m->pindex); 1407 } 1408 s = splvm(); 1409 vm_pageq_remove_nowakeup(m); 1410 vm_pageq_enqueue(PQ_CACHE + m->pc, m); 1411 vm_page_free_wakeup(); 1412 splx(s); 1413} 1414 1415/* 1416 * vm_page_dontneed 1417 * 1418 * Cache, deactivate, or do nothing as appropriate. This routine 1419 * is typically used by madvise() MADV_DONTNEED. 1420 * 1421 * Generally speaking we want to move the page into the cache so 1422 * it gets reused quickly. However, this can result in a silly syndrome 1423 * due to the page recycling too quickly. Small objects will not be 1424 * fully cached. On the otherhand, if we move the page to the inactive 1425 * queue we wind up with a problem whereby very large objects 1426 * unnecessarily blow away our inactive and cache queues. 1427 * 1428 * The solution is to move the pages based on a fixed weighting. We 1429 * either leave them alone, deactivate them, or move them to the cache, 1430 * where moving them to the cache has the highest weighting. 1431 * By forcing some pages into other queues we eventually force the 1432 * system to balance the queues, potentially recovering other unrelated 1433 * space from active. The idea is to not force this to happen too 1434 * often. 1435 */ 1436void 1437vm_page_dontneed(vm_page_t m) 1438{ 1439 static int dnweight; 1440 int dnw; 1441 int head; 1442 1443 GIANT_REQUIRED; 1444 dnw = ++dnweight; 1445 1446 /* 1447 * occassionally leave the page alone 1448 */ 1449 if ((dnw & 0x01F0) == 0 || 1450 m->queue == PQ_INACTIVE || 1451 m->queue - m->pc == PQ_CACHE 1452 ) { 1453 if (m->act_count >= ACT_INIT) 1454 --m->act_count; 1455 return; 1456 } 1457 1458 if (m->dirty == 0) 1459 vm_page_test_dirty(m); 1460 1461 if (m->dirty || (dnw & 0x0070) == 0) { 1462 /* 1463 * Deactivate the page 3 times out of 32. 1464 */ 1465 head = 0; 1466 } else { 1467 /* 1468 * Cache the page 28 times out of every 32. Note that 1469 * the page is deactivated instead of cached, but placed 1470 * at the head of the queue instead of the tail. 1471 */ 1472 head = 1; 1473 } 1474 _vm_page_deactivate(m, head); 1475} 1476 1477/* 1478 * Grab a page, waiting until we are waken up due to the page 1479 * changing state. We keep on waiting, if the page continues 1480 * to be in the object. If the page doesn't exist, allocate it. 1481 * 1482 * This routine may block. 1483 */ 1484vm_page_t 1485vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1486{ 1487 vm_page_t m; 1488 int s, generation; 1489 1490 GIANT_REQUIRED; 1491retrylookup: 1492 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1493 if (m->busy || (m->flags & PG_BUSY)) { 1494 generation = object->generation; 1495 1496 s = splvm(); 1497 while ((object->generation == generation) && 1498 (m->busy || (m->flags & PG_BUSY))) { 1499 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1500 tsleep(m, PVM, "pgrbwt", 0); 1501 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1502 splx(s); 1503 return NULL; 1504 } 1505 } 1506 splx(s); 1507 goto retrylookup; 1508 } else { 1509 vm_page_busy(m); 1510 return m; 1511 } 1512 } 1513 1514 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1515 if (m == NULL) { 1516 VM_WAIT; 1517 if ((allocflags & VM_ALLOC_RETRY) == 0) 1518 return NULL; 1519 goto retrylookup; 1520 } 1521 1522 return m; 1523} 1524 1525/* 1526 * Mapping function for valid bits or for dirty bits in 1527 * a page. May not block. 1528 * 1529 * Inputs are required to range within a page. 1530 */ 1531__inline int 1532vm_page_bits(int base, int size) 1533{ 1534 int first_bit; 1535 int last_bit; 1536 1537 KASSERT( 1538 base + size <= PAGE_SIZE, 1539 ("vm_page_bits: illegal base/size %d/%d", base, size) 1540 ); 1541 1542 if (size == 0) /* handle degenerate case */ 1543 return (0); 1544 1545 first_bit = base >> DEV_BSHIFT; 1546 last_bit = (base + size - 1) >> DEV_BSHIFT; 1547 1548 return ((2 << last_bit) - (1 << first_bit)); 1549} 1550 1551/* 1552 * vm_page_set_validclean: 1553 * 1554 * Sets portions of a page valid and clean. The arguments are expected 1555 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1556 * of any partial chunks touched by the range. The invalid portion of 1557 * such chunks will be zero'd. 1558 * 1559 * This routine may not block. 1560 * 1561 * (base + size) must be less then or equal to PAGE_SIZE. 1562 */ 1563void 1564vm_page_set_validclean(vm_page_t m, int base, int size) 1565{ 1566 int pagebits; 1567 int frag; 1568 int endoff; 1569 1570 GIANT_REQUIRED; 1571 if (size == 0) /* handle degenerate case */ 1572 return; 1573 1574 /* 1575 * If the base is not DEV_BSIZE aligned and the valid 1576 * bit is clear, we have to zero out a portion of the 1577 * first block. 1578 */ 1579 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1580 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) 1581 pmap_zero_page_area(m, frag, base - frag); 1582 1583 /* 1584 * If the ending offset is not DEV_BSIZE aligned and the 1585 * valid bit is clear, we have to zero out a portion of 1586 * the last block. 1587 */ 1588 endoff = base + size; 1589 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1590 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) 1591 pmap_zero_page_area(m, endoff, 1592 DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); 1593 1594 /* 1595 * Set valid, clear dirty bits. If validating the entire 1596 * page we can safely clear the pmap modify bit. We also 1597 * use this opportunity to clear the PG_NOSYNC flag. If a process 1598 * takes a write fault on a MAP_NOSYNC memory area the flag will 1599 * be set again. 1600 * 1601 * We set valid bits inclusive of any overlap, but we can only 1602 * clear dirty bits for DEV_BSIZE chunks that are fully within 1603 * the range. 1604 */ 1605 pagebits = vm_page_bits(base, size); 1606 m->valid |= pagebits; 1607#if 0 /* NOT YET */ 1608 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1609 frag = DEV_BSIZE - frag; 1610 base += frag; 1611 size -= frag; 1612 if (size < 0) 1613 size = 0; 1614 } 1615 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1616#endif 1617 m->dirty &= ~pagebits; 1618 if (base == 0 && size == PAGE_SIZE) { 1619 pmap_clear_modify(m); 1620 vm_page_flag_clear(m, PG_NOSYNC); 1621 } 1622} 1623 1624#if 0 1625 1626void 1627vm_page_set_dirty(vm_page_t m, int base, int size) 1628{ 1629 m->dirty |= vm_page_bits(base, size); 1630} 1631 1632#endif 1633 1634void 1635vm_page_clear_dirty(vm_page_t m, int base, int size) 1636{ 1637 GIANT_REQUIRED; 1638 m->dirty &= ~vm_page_bits(base, size); 1639} 1640 1641/* 1642 * vm_page_set_invalid: 1643 * 1644 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1645 * valid and dirty bits for the effected areas are cleared. 1646 * 1647 * May not block. 1648 */ 1649void 1650vm_page_set_invalid(vm_page_t m, int base, int size) 1651{ 1652 int bits; 1653 1654 GIANT_REQUIRED; 1655 bits = vm_page_bits(base, size); 1656 m->valid &= ~bits; 1657 m->dirty &= ~bits; 1658 m->object->generation++; 1659} 1660 1661/* 1662 * vm_page_zero_invalid() 1663 * 1664 * The kernel assumes that the invalid portions of a page contain 1665 * garbage, but such pages can be mapped into memory by user code. 1666 * When this occurs, we must zero out the non-valid portions of the 1667 * page so user code sees what it expects. 1668 * 1669 * Pages are most often semi-valid when the end of a file is mapped 1670 * into memory and the file's size is not page aligned. 1671 */ 1672void 1673vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1674{ 1675 int b; 1676 int i; 1677 1678 /* 1679 * Scan the valid bits looking for invalid sections that 1680 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1681 * valid bit may be set ) have already been zerod by 1682 * vm_page_set_validclean(). 1683 */ 1684 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1685 if (i == (PAGE_SIZE / DEV_BSIZE) || 1686 (m->valid & (1 << i)) 1687 ) { 1688 if (i > b) { 1689 pmap_zero_page_area(m, 1690 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); 1691 } 1692 b = i + 1; 1693 } 1694 } 1695 1696 /* 1697 * setvalid is TRUE when we can safely set the zero'd areas 1698 * as being valid. We can do this if there are no cache consistancy 1699 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1700 */ 1701 if (setvalid) 1702 m->valid = VM_PAGE_BITS_ALL; 1703} 1704 1705/* 1706 * vm_page_is_valid: 1707 * 1708 * Is (partial) page valid? Note that the case where size == 0 1709 * will return FALSE in the degenerate case where the page is 1710 * entirely invalid, and TRUE otherwise. 1711 * 1712 * May not block. 1713 */ 1714int 1715vm_page_is_valid(vm_page_t m, int base, int size) 1716{ 1717 int bits = vm_page_bits(base, size); 1718 1719 if (m->valid && ((m->valid & bits) == bits)) 1720 return 1; 1721 else 1722 return 0; 1723} 1724 1725/* 1726 * update dirty bits from pmap/mmu. May not block. 1727 */ 1728void 1729vm_page_test_dirty(vm_page_t m) 1730{ 1731 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1732 vm_page_dirty(m); 1733 } 1734} 1735 1736int so_zerocp_fullpage = 0; 1737 1738void 1739vm_page_cowfault(vm_page_t m) 1740{ 1741 vm_page_t mnew; 1742 vm_object_t object; 1743 vm_pindex_t pindex; 1744 1745 object = m->object; 1746 pindex = m->pindex; 1747 vm_page_busy(m); 1748 1749 retry_alloc: 1750 vm_page_remove(m); 1751 mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL); 1752 if (mnew == NULL) { 1753 vm_page_insert(m, object, pindex); 1754 VM_WAIT; 1755 goto retry_alloc; 1756 } 1757 1758 if (m->cow == 0) { 1759 /* 1760 * check to see if we raced with an xmit complete when 1761 * waiting to allocate a page. If so, put things back 1762 * the way they were 1763 */ 1764 vm_page_busy(mnew); 1765 vm_page_free(mnew); 1766 vm_page_insert(m, object, pindex); 1767 } else { /* clear COW & copy page */ 1768 if (so_zerocp_fullpage) { 1769 mnew->valid = VM_PAGE_BITS_ALL; 1770 } else { 1771 vm_page_copy(m, mnew); 1772 } 1773 vm_page_dirty(mnew); 1774 vm_page_flag_clear(mnew, PG_BUSY); 1775 } 1776 vm_page_wakeup(m); /*unbusy the page */ 1777} 1778 1779void 1780vm_page_cowclear(vm_page_t m) 1781{ 1782 1783 /* XXX KDM find out if giant is required here. */ 1784 GIANT_REQUIRED; 1785 if (m->cow) { 1786 atomic_subtract_int(&m->cow, 1); 1787 /* 1788 * let vm_fault add back write permission lazily 1789 */ 1790 } 1791 /* 1792 * sf_buf_free() will free the page, so we needn't do it here 1793 */ 1794} 1795 1796void 1797vm_page_cowsetup(vm_page_t m) 1798{ 1799 /* XXX KDM find out if giant is required here */ 1800 GIANT_REQUIRED; 1801 atomic_add_int(&m->cow, 1); 1802 vm_page_protect(m, VM_PROT_READ); 1803} 1804 1805#include "opt_ddb.h" 1806#ifdef DDB 1807#include <sys/kernel.h> 1808 1809#include <ddb/ddb.h> 1810 1811DB_SHOW_COMMAND(page, vm_page_print_page_info) 1812{ 1813 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); 1814 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); 1815 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); 1816 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); 1817 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); 1818 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); 1819 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); 1820 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); 1821 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); 1822 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); 1823} 1824 1825DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1826{ 1827 int i; 1828 db_printf("PQ_FREE:"); 1829 for (i = 0; i < PQ_L2_SIZE; i++) { 1830 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1831 } 1832 db_printf("\n"); 1833 1834 db_printf("PQ_CACHE:"); 1835 for (i = 0; i < PQ_L2_SIZE; i++) { 1836 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1837 } 1838 db_printf("\n"); 1839 1840 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1841 vm_page_queues[PQ_ACTIVE].lcnt, 1842 vm_page_queues[PQ_INACTIVE].lcnt); 1843} 1844#endif /* DDB */ 1845