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: src/sys/vm/vm_page.c,v 1.147.2.18 2002/03/10 05:03:19 alc Exp $ 38 * $DragonFly: src/sys/vm/vm_page.c,v 1.26 2004/09/17 10:02:12 dillon Exp $ 39 */ 40 41 /* 42 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 43 * All rights reserved. 44 * 45 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 46 * 47 * Permission to use, copy, modify and distribute this software and 48 * its documentation is hereby granted, provided that both the copyright 49 * notice and this permission notice appear in all copies of the 50 * software, derivative works or modified versions, and any portions 51 * thereof, and that both notices appear in supporting documentation. 52 * 53 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 54 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 55 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 56 * 57 * Carnegie Mellon requests users of this software to return to 58 * 59 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 60 * School of Computer Science 61 * Carnegie Mellon University 62 * Pittsburgh PA 15213-3890 63 * 64 * any improvements or extensions that they make and grant Carnegie the 65 * rights to redistribute these changes. 66 */ 67 /* 68 * Resident memory management module. The module manipulates 'VM pages'. 69 * A VM page is the core building block for memory management. 70 */ 71 72 #include <sys/param.h> 73 #include <sys/systm.h> 74 #include <sys/malloc.h> 75 #include <sys/proc.h> 76 #include <sys/vmmeter.h> 77 #include <sys/vnode.h> 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <sys/lock.h> 82 #include <vm/vm_kern.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_map.h> 85 #include <vm/vm_object.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_pageout.h> 88 #include <vm/vm_pager.h> 89 #include <vm/vm_extern.h> 90 #include <vm/vm_page2.h> 91 92 #include <sys/thread2.h> 93 94 static void vm_page_queue_init(void); 95 static void vm_page_free_wakeup(void); 96 static vm_page_t vm_page_select_cache(vm_object_t, vm_pindex_t); 97 static vm_page_t _vm_page_list_find2(int basequeue, int index); 98 99 static int vm_page_bucket_count; /* How big is array? */ 100 static int vm_page_hash_mask; /* Mask for hash function */ 101 static struct vm_page **vm_page_buckets; /* Array of buckets */ 102 static volatile int vm_page_bucket_generation; 103 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 104 105 static void 106 vm_page_queue_init(void) 107 { 108 int i; 109 110 for (i = 0; i < PQ_L2_SIZE; i++) 111 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 112 for (i = 0; i < PQ_L2_SIZE; i++) 113 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 114 115 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 116 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 117 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 118 /* PQ_NONE has no queue */ 119 120 for (i = 0; i < PQ_COUNT; i++) 121 TAILQ_INIT(&vm_page_queues[i].pl); 122 } 123 124 /* 125 * note: place in initialized data section? Is this necessary? 126 */ 127 long first_page = 0; 128 int vm_page_array_size = 0; 129 int vm_page_zero_count = 0; 130 vm_page_t vm_page_array = 0; 131 132 /* 133 * (low level boot) 134 * 135 * Sets the page size, perhaps based upon the memory size. 136 * Must be called before any use of page-size dependent functions. 137 */ 138 void 139 vm_set_page_size(void) 140 { 141 if (vmstats.v_page_size == 0) 142 vmstats.v_page_size = PAGE_SIZE; 143 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 144 panic("vm_set_page_size: page size not a power of two"); 145 } 146 147 /* 148 * (low level boot) 149 * 150 * Add a new page to the freelist for use by the system. New pages 151 * are added to both the head and tail of the associated free page 152 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 153 * requests pull 'recent' adds (higher physical addresses) first. 154 * 155 * Must be called at splhigh(). 156 */ 157 vm_page_t 158 vm_add_new_page(vm_paddr_t pa) 159 { 160 struct vpgqueues *vpq; 161 vm_page_t m; 162 163 ++vmstats.v_page_count; 164 ++vmstats.v_free_count; 165 m = PHYS_TO_VM_PAGE(pa); 166 m->phys_addr = pa; 167 m->flags = 0; 168 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 169 m->queue = m->pc + PQ_FREE; 170 171 vpq = &vm_page_queues[m->queue]; 172 if (vpq->flipflop) 173 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 174 else 175 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 176 vpq->flipflop = 1 - vpq->flipflop; 177 178 vm_page_queues[m->queue].lcnt++; 179 return (m); 180 } 181 182 /* 183 * (low level boot) 184 * 185 * Initializes the resident memory module. 186 * 187 * Allocates memory for the page cells, and for the object/offset-to-page 188 * hash table headers. Each page cell is initialized and placed on the 189 * free list. 190 */ 191 vm_offset_t 192 vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr) 193 { 194 vm_offset_t mapped; 195 struct vm_page **bucket; 196 vm_size_t npages; 197 vm_paddr_t page_range; 198 vm_paddr_t new_end; 199 int i; 200 vm_paddr_t pa; 201 int nblocks; 202 vm_paddr_t last_pa; 203 204 /* the biggest memory array is the second group of pages */ 205 vm_paddr_t end; 206 vm_paddr_t biggestone, biggestsize; 207 208 vm_paddr_t total; 209 210 total = 0; 211 biggestsize = 0; 212 biggestone = 0; 213 nblocks = 0; 214 vaddr = round_page(vaddr); 215 216 for (i = 0; phys_avail[i + 1]; i += 2) { 217 phys_avail[i] = round_page(phys_avail[i]); 218 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 219 } 220 221 for (i = 0; phys_avail[i + 1]; i += 2) { 222 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 223 224 if (size > biggestsize) { 225 biggestone = i; 226 biggestsize = size; 227 } 228 ++nblocks; 229 total += size; 230 } 231 232 end = phys_avail[biggestone+1]; 233 234 /* 235 * Initialize the queue headers for the free queue, the active queue 236 * and the inactive queue. 237 */ 238 239 vm_page_queue_init(); 240 241 /* 242 * Allocate (and initialize) the hash table buckets. 243 * 244 * The number of buckets MUST BE a power of 2, and the actual value is 245 * the next power of 2 greater than the number of physical pages in 246 * the system. 247 * 248 * We make the hash table approximately 2x the number of pages to 249 * reduce the chain length. This is about the same size using the 250 * singly-linked list as the 1x hash table we were using before 251 * using TAILQ but the chain length will be smaller. 252 * 253 * Note: This computation can be tweaked if desired. 254 */ 255 vm_page_buckets = (struct vm_page **)vaddr; 256 bucket = vm_page_buckets; 257 if (vm_page_bucket_count == 0) { 258 vm_page_bucket_count = 1; 259 while (vm_page_bucket_count < atop(total)) 260 vm_page_bucket_count <<= 1; 261 } 262 vm_page_bucket_count <<= 1; 263 vm_page_hash_mask = vm_page_bucket_count - 1; 264 265 /* 266 * Validate these addresses. 267 */ 268 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 269 new_end = trunc_page(new_end); 270 mapped = round_page(vaddr); 271 vaddr = pmap_map(mapped, new_end, end, 272 VM_PROT_READ | VM_PROT_WRITE); 273 vaddr = round_page(vaddr); 274 bzero((caddr_t) mapped, vaddr - mapped); 275 276 for (i = 0; i < vm_page_bucket_count; i++) { 277 *bucket = NULL; 278 bucket++; 279 } 280 281 /* 282 * Compute the number of pages of memory that will be available for 283 * use (taking into account the overhead of a page structure per 284 * page). 285 */ 286 first_page = phys_avail[0] / PAGE_SIZE; 287 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 288 npages = (total - (page_range * sizeof(struct vm_page)) - 289 (end - new_end)) / PAGE_SIZE; 290 291 end = new_end; 292 293 /* 294 * Initialize the mem entry structures now, and put them in the free 295 * queue. 296 */ 297 vm_page_array = (vm_page_t) vaddr; 298 mapped = vaddr; 299 300 /* 301 * Validate these addresses. 302 */ 303 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 304 mapped = pmap_map(mapped, new_end, end, 305 VM_PROT_READ | VM_PROT_WRITE); 306 307 /* 308 * Clear all of the page structures 309 */ 310 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 311 vm_page_array_size = page_range; 312 313 /* 314 * Construct the free queue(s) in ascending order (by physical 315 * address) so that the first 16MB of physical memory is allocated 316 * last rather than first. On large-memory machines, this avoids 317 * the exhaustion of low physical memory before isa_dmainit has run. 318 */ 319 vmstats.v_page_count = 0; 320 vmstats.v_free_count = 0; 321 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 322 pa = phys_avail[i]; 323 if (i == biggestone) 324 last_pa = new_end; 325 else 326 last_pa = phys_avail[i + 1]; 327 while (pa < last_pa && npages-- > 0) { 328 vm_add_new_page(pa); 329 pa += PAGE_SIZE; 330 } 331 } 332 return (mapped); 333 } 334 335 /* 336 * Distributes the object/offset key pair among hash buckets. 337 * 338 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 339 * This routine may not block. 340 * 341 * We try to randomize the hash based on the object to spread the pages 342 * out in the hash table without it costing us too much. 343 */ 344 static __inline int 345 vm_page_hash(vm_object_t object, vm_pindex_t pindex) 346 { 347 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 348 349 return(i & vm_page_hash_mask); 350 } 351 352 /* 353 * The opposite of vm_page_hold(). A page can be freed while being held, 354 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 355 * in this case to actually free it once the hold count drops to 0. 356 * 357 * This routine must be called at splvm(). 358 */ 359 void 360 vm_page_unhold(vm_page_t mem) 361 { 362 --mem->hold_count; 363 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 364 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) 365 vm_page_free_toq(mem); 366 } 367 368 /* 369 * Inserts the given mem entry into the object and object list. 370 * 371 * The pagetables are not updated but will presumably fault the page 372 * in if necessary, or if a kernel page the caller will at some point 373 * enter the page into the kernel's pmap. We are not allowed to block 374 * here so we *can't* do this anyway. 375 * 376 * This routine may not block. 377 * This routine must be called at splvm(). 378 */ 379 void 380 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 381 { 382 struct vm_page **bucket; 383 384 if (m->object != NULL) 385 panic("vm_page_insert: already inserted"); 386 387 /* 388 * Record the object/offset pair in this page 389 */ 390 m->object = object; 391 m->pindex = pindex; 392 393 /* 394 * Insert it into the object_object/offset hash table 395 */ 396 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 397 m->hnext = *bucket; 398 *bucket = m; 399 vm_page_bucket_generation++; 400 401 /* 402 * Now link into the object's list of backed pages. 403 */ 404 TAILQ_INSERT_TAIL(&object->memq, m, listq); 405 object->generation++; 406 407 /* 408 * show that the object has one more resident page. 409 */ 410 object->resident_page_count++; 411 412 /* 413 * Since we are inserting a new and possibly dirty page, 414 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 415 */ 416 if (m->flags & PG_WRITEABLE) 417 vm_object_set_writeable_dirty(object); 418 } 419 420 /* 421 * Removes the given vm_page_t from the global (object,index) hash table 422 * and from the object's memq. 423 * 424 * The underlying pmap entry (if any) is NOT removed here. 425 * This routine may not block. 426 * 427 * The page must be BUSY and will remain BUSY on return. No spl needs to be 428 * held on call to this routine. 429 * 430 * note: FreeBSD side effect was to unbusy the page on return. We leave 431 * it busy. 432 */ 433 void 434 vm_page_remove(vm_page_t m) 435 { 436 vm_object_t object; 437 struct vm_page **bucket; 438 439 if (m->object == NULL) 440 return; 441 442 if ((m->flags & PG_BUSY) == 0) 443 panic("vm_page_remove: page not busy"); 444 445 object = m->object; 446 447 /* 448 * Remove from the object_object/offset hash table. The object 449 * must be on the hash queue, we will panic if it isn't 450 * 451 * Note: we must NULL-out m->hnext to prevent loops in detached 452 * buffers with vm_page_lookup(). 453 */ 454 crit_enter(); 455 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 456 while (*bucket != m) { 457 if (*bucket == NULL) 458 panic("vm_page_remove(): page not found in hash"); 459 bucket = &(*bucket)->hnext; 460 } 461 *bucket = m->hnext; 462 m->hnext = NULL; 463 vm_page_bucket_generation++; 464 465 /* 466 * Now remove from the object's list of backed pages. 467 */ 468 TAILQ_REMOVE(&object->memq, m, listq); 469 470 /* 471 * And show that the object has one fewer resident page. 472 */ 473 object->resident_page_count--; 474 object->generation++; 475 476 m->object = NULL; 477 crit_exit(); 478 } 479 480 /* 481 * Locate and return the page at (object, pindex), or NULL if the 482 * page could not be found. 483 * 484 * This routine will operate properly without spl protection, but 485 * the returned page could be in flux if it is busy. Because an 486 * interrupt can race a caller's busy check (unbusying and freeing the 487 * page we return before the caller is able to check the busy bit), 488 * the caller should generally call this routine at splvm(). 489 * 490 * Callers may call this routine without spl protection if they know 491 * 'for sure' that the page will not be ripped out from under them 492 * by an interrupt. 493 */ 494 vm_page_t 495 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 496 { 497 vm_page_t m; 498 struct vm_page **bucket; 499 int generation; 500 501 /* 502 * Search the hash table for this object/offset pair 503 */ 504 retry: 505 generation = vm_page_bucket_generation; 506 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 507 for (m = *bucket; m != NULL; m = m->hnext) { 508 if ((m->object == object) && (m->pindex == pindex)) { 509 if (vm_page_bucket_generation != generation) 510 goto retry; 511 return (m); 512 } 513 } 514 if (vm_page_bucket_generation != generation) 515 goto retry; 516 return (NULL); 517 } 518 519 /* 520 * vm_page_rename() 521 * 522 * Move the given memory entry from its current object to the specified 523 * target object/offset. 524 * 525 * The object must be locked. 526 * This routine may not block. 527 * 528 * Note: This routine will raise itself to splvm(), the caller need not. 529 * 530 * Note: Swap associated with the page must be invalidated by the move. We 531 * have to do this for several reasons: (1) we aren't freeing the 532 * page, (2) we are dirtying the page, (3) the VM system is probably 533 * moving the page from object A to B, and will then later move 534 * the backing store from A to B and we can't have a conflict. 535 * 536 * Note: We *always* dirty the page. It is necessary both for the 537 * fact that we moved it, and because we may be invalidating 538 * swap. If the page is on the cache, we have to deactivate it 539 * or vm_page_dirty() will panic. Dirty pages are not allowed 540 * on the cache. 541 */ 542 void 543 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 544 { 545 crit_enter(); 546 vm_page_remove(m); 547 vm_page_insert(m, new_object, new_pindex); 548 if (m->queue - m->pc == PQ_CACHE) 549 vm_page_deactivate(m); 550 vm_page_dirty(m); 551 vm_page_wakeup(m); 552 crit_exit(); 553 } 554 555 /* 556 * vm_page_unqueue() without any wakeup. This routine is used when a page 557 * is being moved between queues or otherwise is to remain BUSYied by the 558 * caller. 559 * 560 * This routine must be called at splhigh(). 561 * This routine may not block. 562 */ 563 void 564 vm_page_unqueue_nowakeup(vm_page_t m) 565 { 566 int queue = m->queue; 567 struct vpgqueues *pq; 568 569 if (queue != PQ_NONE) { 570 pq = &vm_page_queues[queue]; 571 m->queue = PQ_NONE; 572 TAILQ_REMOVE(&pq->pl, m, pageq); 573 (*pq->cnt)--; 574 pq->lcnt--; 575 } 576 } 577 578 /* 579 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 580 * if necessary. 581 * 582 * This routine must be called at splhigh(). 583 * This routine may not block. 584 */ 585 void 586 vm_page_unqueue(vm_page_t m) 587 { 588 int queue = m->queue; 589 struct vpgqueues *pq; 590 591 if (queue != PQ_NONE) { 592 m->queue = PQ_NONE; 593 pq = &vm_page_queues[queue]; 594 TAILQ_REMOVE(&pq->pl, m, pageq); 595 (*pq->cnt)--; 596 pq->lcnt--; 597 if ((queue - m->pc) == PQ_CACHE) { 598 if (vm_paging_needed()) 599 pagedaemon_wakeup(); 600 } 601 } 602 } 603 604 /* 605 * vm_page_list_find() 606 * 607 * Find a page on the specified queue with color optimization. 608 * 609 * The page coloring optimization attempts to locate a page that does 610 * not overload other nearby pages in the object in the cpu's L1 or L2 611 * caches. We need this optimization because cpu caches tend to be 612 * physical caches, while object spaces tend to be virtual. 613 * 614 * This routine must be called at splvm(). 615 * This routine may not block. 616 * 617 * Note that this routine is carefully inlined. A non-inlined version 618 * is available for outside callers but the only critical path is 619 * from within this source file. 620 */ 621 static __inline 622 vm_page_t 623 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 624 { 625 vm_page_t m; 626 627 if (prefer_zero) 628 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 629 else 630 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 631 if (m == NULL) 632 m = _vm_page_list_find2(basequeue, index); 633 return(m); 634 } 635 636 static vm_page_t 637 _vm_page_list_find2(int basequeue, int index) 638 { 639 int i; 640 vm_page_t m = NULL; 641 struct vpgqueues *pq; 642 643 pq = &vm_page_queues[basequeue]; 644 645 /* 646 * Note that for the first loop, index+i and index-i wind up at the 647 * same place. Even though this is not totally optimal, we've already 648 * blown it by missing the cache case so we do not care. 649 */ 650 651 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 652 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 653 break; 654 655 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 656 break; 657 } 658 return(m); 659 } 660 661 vm_page_t 662 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 663 { 664 return(_vm_page_list_find(basequeue, index, prefer_zero)); 665 } 666 667 /* 668 * Find a page on the cache queue with color optimization. As pages 669 * might be found, but not applicable, they are deactivated. This 670 * keeps us from using potentially busy cached pages. 671 * 672 * This routine must be called at splvm(). 673 * This routine may not block. 674 */ 675 vm_page_t 676 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 677 { 678 vm_page_t m; 679 680 while (TRUE) { 681 m = _vm_page_list_find( 682 PQ_CACHE, 683 (pindex + object->pg_color) & PQ_L2_MASK, 684 FALSE 685 ); 686 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 687 m->hold_count || m->wire_count)) { 688 vm_page_deactivate(m); 689 continue; 690 } 691 return m; 692 } 693 /* not reached */ 694 } 695 696 /* 697 * Find a free or zero page, with specified preference. We attempt to 698 * inline the nominal case and fall back to _vm_page_select_free() 699 * otherwise. 700 * 701 * This routine must be called at splvm(). 702 * This routine may not block. 703 */ 704 static __inline vm_page_t 705 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 706 { 707 vm_page_t m; 708 709 m = _vm_page_list_find( 710 PQ_FREE, 711 (pindex + object->pg_color) & PQ_L2_MASK, 712 prefer_zero 713 ); 714 return(m); 715 } 716 717 /* 718 * vm_page_alloc() 719 * 720 * Allocate and return a memory cell associated with this VM object/offset 721 * pair. 722 * 723 * page_req classes: 724 * 725 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 726 * VM_ALLOC_SYSTEM greater free drain 727 * VM_ALLOC_INTERRUPT allow free list to be completely drained 728 * VM_ALLOC_ZERO advisory request for pre-zero'd page 729 * 730 * The object must be locked. 731 * This routine may not block. 732 * The returned page will be marked PG_BUSY 733 * 734 * Additional special handling is required when called from an interrupt 735 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 736 * in this case. 737 */ 738 vm_page_t 739 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 740 { 741 vm_page_t m = NULL; 742 743 KASSERT(!vm_page_lookup(object, pindex), 744 ("vm_page_alloc: page already allocated")); 745 KKASSERT(page_req & 746 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 747 748 /* 749 * The pager is allowed to eat deeper into the free page list. 750 */ 751 if (curthread == pagethread) 752 page_req |= VM_ALLOC_SYSTEM; 753 754 crit_enter(); 755 loop: 756 if (vmstats.v_free_count > vmstats.v_free_reserved || 757 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 758 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 759 vmstats.v_free_count > vmstats.v_interrupt_free_min) 760 ) { 761 /* 762 * The free queue has sufficient free pages to take one out. 763 */ 764 if (page_req & VM_ALLOC_ZERO) 765 m = vm_page_select_free(object, pindex, TRUE); 766 else 767 m = vm_page_select_free(object, pindex, FALSE); 768 } else if (page_req & VM_ALLOC_NORMAL) { 769 /* 770 * Allocatable from the cache (non-interrupt only). On 771 * success, we must free the page and try again, thus 772 * ensuring that vmstats.v_*_free_min counters are replenished. 773 */ 774 #ifdef INVARIANTS 775 if (curthread->td_preempted) { 776 printf("vm_page_alloc(): warning, attempt to allocate" 777 " cache page from preempting interrupt\n"); 778 m = NULL; 779 } else { 780 m = vm_page_select_cache(object, pindex); 781 } 782 #else 783 m = vm_page_select_cache(object, pindex); 784 #endif 785 /* 786 * On success move the page into the free queue and loop. 787 */ 788 if (m != NULL) { 789 KASSERT(m->dirty == 0, 790 ("Found dirty cache page %p", m)); 791 vm_page_busy(m); 792 vm_page_protect(m, VM_PROT_NONE); 793 vm_page_free(m); 794 goto loop; 795 } 796 797 /* 798 * On failure return NULL 799 */ 800 crit_exit(); 801 #if defined(DIAGNOSTIC) 802 if (vmstats.v_cache_count > 0) 803 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 804 #endif 805 vm_pageout_deficit++; 806 pagedaemon_wakeup(); 807 return (NULL); 808 } else { 809 /* 810 * No pages available, wakeup the pageout daemon and give up. 811 */ 812 crit_exit(); 813 vm_pageout_deficit++; 814 pagedaemon_wakeup(); 815 return (NULL); 816 } 817 818 /* 819 * Good page found. The page has not yet been busied. We are in 820 * a critical section. 821 */ 822 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 823 824 /* 825 * Remove from free queue 826 */ 827 vm_page_unqueue_nowakeup(m); 828 829 /* 830 * Initialize structure. Only the PG_ZERO flag is inherited. Set 831 * the page PG_BUSY 832 */ 833 if (m->flags & PG_ZERO) { 834 vm_page_zero_count--; 835 m->flags = PG_ZERO | PG_BUSY; 836 } else { 837 m->flags = PG_BUSY; 838 } 839 m->wire_count = 0; 840 m->hold_count = 0; 841 m->act_count = 0; 842 m->busy = 0; 843 m->valid = 0; 844 KASSERT(m->dirty == 0, 845 ("vm_page_alloc: free/cache page %p was dirty", m)); 846 847 /* 848 * vm_page_insert() is safe prior to the crit_exit(). Note also that 849 * inserting a page here does not insert it into the pmap (which 850 * could cause us to block allocating memory). We cannot block 851 * anywhere. 852 */ 853 vm_page_insert(m, object, pindex); 854 855 /* 856 * Don't wakeup too often - wakeup the pageout daemon when 857 * we would be nearly out of memory. 858 */ 859 if (vm_paging_needed()) 860 pagedaemon_wakeup(); 861 862 crit_exit(); 863 864 /* 865 * A PG_BUSY page is returned. 866 */ 867 return (m); 868 } 869 870 /* 871 * Block until free pages are available for allocation, called in various 872 * places before memory allocations. 873 */ 874 void 875 vm_wait(void) 876 { 877 int s; 878 879 s = splvm(); 880 if (curthread == pagethread) { 881 vm_pageout_pages_needed = 1; 882 tsleep(&vm_pageout_pages_needed, 0, "VMWait", 0); 883 } else { 884 if (!vm_pages_needed) { 885 vm_pages_needed = 1; 886 wakeup(&vm_pages_needed); 887 } 888 tsleep(&vmstats.v_free_count, 0, "vmwait", 0); 889 } 890 splx(s); 891 } 892 893 /* 894 * Block until free pages are available for allocation 895 * 896 * Called only in vm_fault so that processes page faulting can be 897 * easily tracked. 898 * 899 * Sleeps at a lower priority than vm_wait() so that vm_wait()ing 900 * processes will be able to grab memory first. Do not change 901 * this balance without careful testing first. 902 */ 903 void 904 vm_waitpfault(void) 905 { 906 int s; 907 908 s = splvm(); 909 if (!vm_pages_needed) { 910 vm_pages_needed = 1; 911 wakeup(&vm_pages_needed); 912 } 913 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 914 splx(s); 915 } 916 917 /* 918 * Put the specified page on the active list (if appropriate). Ensure 919 * that act_count is at least ACT_INIT but do not otherwise mess with it. 920 * 921 * The page queues must be locked. 922 * This routine may not block. 923 */ 924 void 925 vm_page_activate(vm_page_t m) 926 { 927 crit_enter(); 928 if (m->queue != PQ_ACTIVE) { 929 if ((m->queue - m->pc) == PQ_CACHE) 930 mycpu->gd_cnt.v_reactivated++; 931 932 vm_page_unqueue(m); 933 934 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 935 m->queue = PQ_ACTIVE; 936 vm_page_queues[PQ_ACTIVE].lcnt++; 937 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 938 m, pageq); 939 if (m->act_count < ACT_INIT) 940 m->act_count = ACT_INIT; 941 vmstats.v_active_count++; 942 } 943 } else { 944 if (m->act_count < ACT_INIT) 945 m->act_count = ACT_INIT; 946 } 947 crit_exit(); 948 } 949 950 /* 951 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 952 * routine is called when a page has been added to the cache or free 953 * queues. 954 * 955 * This routine may not block. 956 * This routine must be called at splvm() 957 */ 958 static __inline void 959 vm_page_free_wakeup(void) 960 { 961 /* 962 * if pageout daemon needs pages, then tell it that there are 963 * some free. 964 */ 965 if (vm_pageout_pages_needed && 966 vmstats.v_cache_count + vmstats.v_free_count >= 967 vmstats.v_pageout_free_min 968 ) { 969 wakeup(&vm_pageout_pages_needed); 970 vm_pageout_pages_needed = 0; 971 } 972 973 /* 974 * wakeup processes that are waiting on memory if we hit a 975 * high water mark. And wakeup scheduler process if we have 976 * lots of memory. this process will swapin processes. 977 */ 978 if (vm_pages_needed && !vm_page_count_min()) { 979 vm_pages_needed = 0; 980 wakeup(&vmstats.v_free_count); 981 } 982 } 983 984 /* 985 * vm_page_free_toq: 986 * 987 * Returns the given page to the PQ_FREE list, disassociating it with 988 * any VM object. 989 * 990 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 991 * return (the page will have been freed). No particular spl is required 992 * on entry. 993 * 994 * This routine may not block. 995 */ 996 void 997 vm_page_free_toq(vm_page_t m) 998 { 999 struct vpgqueues *pq; 1000 1001 crit_enter(); 1002 mycpu->gd_cnt.v_tfree++; 1003 1004 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1005 printf( 1006 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1007 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1008 m->hold_count); 1009 if ((m->queue - m->pc) == PQ_FREE) 1010 panic("vm_page_free: freeing free page"); 1011 else 1012 panic("vm_page_free: freeing busy page"); 1013 } 1014 1015 /* 1016 * unqueue, then remove page. Note that we cannot destroy 1017 * the page here because we do not want to call the pager's 1018 * callback routine until after we've put the page on the 1019 * appropriate free queue. 1020 */ 1021 vm_page_unqueue_nowakeup(m); 1022 vm_page_remove(m); 1023 1024 /* 1025 * No further management of fictitious pages occurs beyond object 1026 * and queue removal. 1027 */ 1028 if ((m->flags & PG_FICTITIOUS) != 0) { 1029 vm_page_wakeup(m); 1030 crit_exit(); 1031 return; 1032 } 1033 1034 m->valid = 0; 1035 vm_page_undirty(m); 1036 1037 if (m->wire_count != 0) { 1038 if (m->wire_count > 1) { 1039 panic( 1040 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1041 m->wire_count, (long)m->pindex); 1042 } 1043 panic("vm_page_free: freeing wired page"); 1044 } 1045 1046 /* 1047 * Clear the UNMANAGED flag when freeing an unmanaged page. 1048 */ 1049 if (m->flags & PG_UNMANAGED) { 1050 m->flags &= ~PG_UNMANAGED; 1051 } else { 1052 #ifdef __alpha__ 1053 pmap_page_is_free(m); 1054 #endif 1055 } 1056 1057 if (m->hold_count != 0) { 1058 m->flags &= ~PG_ZERO; 1059 m->queue = PQ_HOLD; 1060 } else { 1061 m->queue = PQ_FREE + m->pc; 1062 } 1063 pq = &vm_page_queues[m->queue]; 1064 pq->lcnt++; 1065 ++(*pq->cnt); 1066 1067 /* 1068 * Put zero'd pages on the end ( where we look for zero'd pages 1069 * first ) and non-zerod pages at the head. 1070 */ 1071 if (m->flags & PG_ZERO) { 1072 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1073 ++vm_page_zero_count; 1074 } else { 1075 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1076 } 1077 vm_page_wakeup(m); 1078 vm_page_free_wakeup(); 1079 crit_exit(); 1080 } 1081 1082 /* 1083 * vm_page_unmanage() 1084 * 1085 * Prevent PV management from being done on the page. The page is 1086 * removed from the paging queues as if it were wired, and as a 1087 * consequence of no longer being managed the pageout daemon will not 1088 * touch it (since there is no way to locate the pte mappings for the 1089 * page). madvise() calls that mess with the pmap will also no longer 1090 * operate on the page. 1091 * 1092 * Beyond that the page is still reasonably 'normal'. Freeing the page 1093 * will clear the flag. 1094 * 1095 * This routine is used by OBJT_PHYS objects - objects using unswappable 1096 * physical memory as backing store rather then swap-backed memory and 1097 * will eventually be extended to support 4MB unmanaged physical 1098 * mappings. 1099 */ 1100 void 1101 vm_page_unmanage(vm_page_t m) 1102 { 1103 int s; 1104 1105 s = splvm(); 1106 if ((m->flags & PG_UNMANAGED) == 0) { 1107 if (m->wire_count == 0) 1108 vm_page_unqueue(m); 1109 } 1110 vm_page_flag_set(m, PG_UNMANAGED); 1111 splx(s); 1112 } 1113 1114 /* 1115 * Mark this page as wired down by yet another map, removing it from 1116 * paging queues as necessary. 1117 * 1118 * The page queues must be locked. 1119 * This routine may not block. 1120 */ 1121 void 1122 vm_page_wire(vm_page_t m) 1123 { 1124 int s; 1125 1126 /* 1127 * Only bump the wire statistics if the page is not already wired, 1128 * and only unqueue the page if it is on some queue (if it is unmanaged 1129 * it is already off the queues). Don't do anything with fictitious 1130 * pages because they are always wired. 1131 */ 1132 s = splvm(); 1133 if ((m->flags & PG_FICTITIOUS) == 0) { 1134 if (m->wire_count == 0) { 1135 if ((m->flags & PG_UNMANAGED) == 0) 1136 vm_page_unqueue(m); 1137 vmstats.v_wire_count++; 1138 } 1139 m->wire_count++; 1140 KASSERT(m->wire_count != 0, 1141 ("vm_page_wire: wire_count overflow m=%p", m)); 1142 } 1143 splx(s); 1144 vm_page_flag_set(m, PG_MAPPED); 1145 } 1146 1147 /* 1148 * Release one wiring of this page, potentially enabling it to be paged again. 1149 * 1150 * Many pages placed on the inactive queue should actually go 1151 * into the cache, but it is difficult to figure out which. What 1152 * we do instead, if the inactive target is well met, is to put 1153 * clean pages at the head of the inactive queue instead of the tail. 1154 * This will cause them to be moved to the cache more quickly and 1155 * if not actively re-referenced, freed more quickly. If we just 1156 * stick these pages at the end of the inactive queue, heavy filesystem 1157 * meta-data accesses can cause an unnecessary paging load on memory bound 1158 * processes. This optimization causes one-time-use metadata to be 1159 * reused more quickly. 1160 * 1161 * BUT, if we are in a low-memory situation we have no choice but to 1162 * put clean pages on the cache queue. 1163 * 1164 * A number of routines use vm_page_unwire() to guarantee that the page 1165 * will go into either the inactive or active queues, and will NEVER 1166 * be placed in the cache - for example, just after dirtying a page. 1167 * dirty pages in the cache are not allowed. 1168 * 1169 * The page queues must be locked. 1170 * This routine may not block. 1171 */ 1172 void 1173 vm_page_unwire(vm_page_t m, int activate) 1174 { 1175 int s; 1176 1177 s = splvm(); 1178 if (m->flags & PG_FICTITIOUS) { 1179 /* do nothing */ 1180 } else if (m->wire_count <= 0) { 1181 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1182 } else { 1183 if (--m->wire_count == 0) { 1184 --vmstats.v_wire_count; 1185 if (m->flags & PG_UNMANAGED) { 1186 ; 1187 } else if (activate) { 1188 TAILQ_INSERT_TAIL( 1189 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1190 m->queue = PQ_ACTIVE; 1191 vm_page_queues[PQ_ACTIVE].lcnt++; 1192 vmstats.v_active_count++; 1193 } else { 1194 vm_page_flag_clear(m, PG_WINATCFLS); 1195 TAILQ_INSERT_TAIL( 1196 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1197 m->queue = PQ_INACTIVE; 1198 vm_page_queues[PQ_INACTIVE].lcnt++; 1199 vmstats.v_inactive_count++; 1200 } 1201 } 1202 } 1203 splx(s); 1204 } 1205 1206 1207 /* 1208 * Move the specified page to the inactive queue. If the page has 1209 * any associated swap, the swap is deallocated. 1210 * 1211 * Normally athead is 0 resulting in LRU operation. athead is set 1212 * to 1 if we want this page to be 'as if it were placed in the cache', 1213 * except without unmapping it from the process address space. 1214 * 1215 * This routine may not block. 1216 */ 1217 static __inline void 1218 _vm_page_deactivate(vm_page_t m, int athead) 1219 { 1220 int s; 1221 1222 /* 1223 * Ignore if already inactive. 1224 */ 1225 if (m->queue == PQ_INACTIVE) 1226 return; 1227 1228 s = splvm(); 1229 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1230 if ((m->queue - m->pc) == PQ_CACHE) 1231 mycpu->gd_cnt.v_reactivated++; 1232 vm_page_flag_clear(m, PG_WINATCFLS); 1233 vm_page_unqueue(m); 1234 if (athead) 1235 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1236 else 1237 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1238 m->queue = PQ_INACTIVE; 1239 vm_page_queues[PQ_INACTIVE].lcnt++; 1240 vmstats.v_inactive_count++; 1241 } 1242 splx(s); 1243 } 1244 1245 void 1246 vm_page_deactivate(vm_page_t m) 1247 { 1248 _vm_page_deactivate(m, 0); 1249 } 1250 1251 /* 1252 * vm_page_try_to_cache: 1253 * 1254 * Returns 0 on failure, 1 on success 1255 */ 1256 int 1257 vm_page_try_to_cache(vm_page_t m) 1258 { 1259 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1260 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1261 return(0); 1262 } 1263 vm_page_test_dirty(m); 1264 if (m->dirty) 1265 return(0); 1266 vm_page_cache(m); 1267 return(1); 1268 } 1269 1270 /* 1271 * Attempt to free the page. If we cannot free it, we do nothing. 1272 * 1 is returned on success, 0 on failure. 1273 */ 1274 int 1275 vm_page_try_to_free(vm_page_t m) 1276 { 1277 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1278 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1279 return(0); 1280 } 1281 vm_page_test_dirty(m); 1282 if (m->dirty) 1283 return(0); 1284 vm_page_busy(m); 1285 vm_page_protect(m, VM_PROT_NONE); 1286 vm_page_free(m); 1287 return(1); 1288 } 1289 1290 /* 1291 * vm_page_cache 1292 * 1293 * Put the specified page onto the page cache queue (if appropriate). 1294 * 1295 * This routine may not block. 1296 */ 1297 void 1298 vm_page_cache(vm_page_t m) 1299 { 1300 int s; 1301 1302 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1303 m->wire_count || m->hold_count) { 1304 printf("vm_page_cache: attempting to cache busy/held page\n"); 1305 return; 1306 } 1307 if ((m->queue - m->pc) == PQ_CACHE) 1308 return; 1309 1310 /* 1311 * Remove all pmaps and indicate that the page is not 1312 * writeable or mapped. 1313 */ 1314 1315 vm_page_protect(m, VM_PROT_NONE); 1316 if (m->dirty != 0) { 1317 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1318 (long)m->pindex); 1319 } 1320 s = splvm(); 1321 vm_page_unqueue_nowakeup(m); 1322 m->queue = PQ_CACHE + m->pc; 1323 vm_page_queues[m->queue].lcnt++; 1324 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1325 vmstats.v_cache_count++; 1326 vm_page_free_wakeup(); 1327 splx(s); 1328 } 1329 1330 /* 1331 * vm_page_dontneed() 1332 * 1333 * Cache, deactivate, or do nothing as appropriate. This routine 1334 * is typically used by madvise() MADV_DONTNEED. 1335 * 1336 * Generally speaking we want to move the page into the cache so 1337 * it gets reused quickly. However, this can result in a silly syndrome 1338 * due to the page recycling too quickly. Small objects will not be 1339 * fully cached. On the otherhand, if we move the page to the inactive 1340 * queue we wind up with a problem whereby very large objects 1341 * unnecessarily blow away our inactive and cache queues. 1342 * 1343 * The solution is to move the pages based on a fixed weighting. We 1344 * either leave them alone, deactivate them, or move them to the cache, 1345 * where moving them to the cache has the highest weighting. 1346 * By forcing some pages into other queues we eventually force the 1347 * system to balance the queues, potentially recovering other unrelated 1348 * space from active. The idea is to not force this to happen too 1349 * often. 1350 */ 1351 void 1352 vm_page_dontneed(vm_page_t m) 1353 { 1354 static int dnweight; 1355 int dnw; 1356 int head; 1357 1358 dnw = ++dnweight; 1359 1360 /* 1361 * occassionally leave the page alone 1362 */ 1363 1364 if ((dnw & 0x01F0) == 0 || 1365 m->queue == PQ_INACTIVE || 1366 m->queue - m->pc == PQ_CACHE 1367 ) { 1368 if (m->act_count >= ACT_INIT) 1369 --m->act_count; 1370 return; 1371 } 1372 1373 if (m->dirty == 0) 1374 vm_page_test_dirty(m); 1375 1376 if (m->dirty || (dnw & 0x0070) == 0) { 1377 /* 1378 * Deactivate the page 3 times out of 32. 1379 */ 1380 head = 0; 1381 } else { 1382 /* 1383 * Cache the page 28 times out of every 32. Note that 1384 * the page is deactivated instead of cached, but placed 1385 * at the head of the queue instead of the tail. 1386 */ 1387 head = 1; 1388 } 1389 _vm_page_deactivate(m, head); 1390 } 1391 1392 /* 1393 * Grab a page, blocking if it is busy and allocating a page if necessary. 1394 * A busy page is returned or NULL. 1395 * 1396 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1397 * If VM_ALLOC_RETRY is not specified 1398 * 1399 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1400 * always returned if we had blocked. 1401 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1402 * This routine may not be called from an interrupt. 1403 * The returned page may not be entirely valid. 1404 * 1405 * This routine may be called from mainline code without spl protection and 1406 * be guarenteed a busied page associated with the object at the specified 1407 * index. 1408 */ 1409 vm_page_t 1410 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1411 { 1412 vm_page_t m; 1413 int s, generation; 1414 1415 KKASSERT(allocflags & 1416 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1417 s = splvm(); 1418 retrylookup: 1419 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1420 if (m->busy || (m->flags & PG_BUSY)) { 1421 generation = object->generation; 1422 1423 while ((object->generation == generation) && 1424 (m->busy || (m->flags & PG_BUSY))) { 1425 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1426 tsleep(m, 0, "pgrbwt", 0); 1427 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1428 m = NULL; 1429 goto done; 1430 } 1431 } 1432 goto retrylookup; 1433 } else { 1434 vm_page_busy(m); 1435 goto done; 1436 } 1437 } 1438 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1439 if (m == NULL) { 1440 vm_wait(); 1441 if ((allocflags & VM_ALLOC_RETRY) == 0) 1442 goto done; 1443 goto retrylookup; 1444 } 1445 done: 1446 splx(s); 1447 return(m); 1448 } 1449 1450 /* 1451 * Mapping function for valid bits or for dirty bits in 1452 * a page. May not block. 1453 * 1454 * Inputs are required to range within a page. 1455 */ 1456 __inline int 1457 vm_page_bits(int base, int size) 1458 { 1459 int first_bit; 1460 int last_bit; 1461 1462 KASSERT( 1463 base + size <= PAGE_SIZE, 1464 ("vm_page_bits: illegal base/size %d/%d", base, size) 1465 ); 1466 1467 if (size == 0) /* handle degenerate case */ 1468 return(0); 1469 1470 first_bit = base >> DEV_BSHIFT; 1471 last_bit = (base + size - 1) >> DEV_BSHIFT; 1472 1473 return ((2 << last_bit) - (1 << first_bit)); 1474 } 1475 1476 /* 1477 * Sets portions of a page valid and clean. The arguments are expected 1478 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1479 * of any partial chunks touched by the range. The invalid portion of 1480 * such chunks will be zero'd. 1481 * 1482 * This routine may not block. 1483 * 1484 * (base + size) must be less then or equal to PAGE_SIZE. 1485 */ 1486 void 1487 vm_page_set_validclean(vm_page_t m, int base, int size) 1488 { 1489 int pagebits; 1490 int frag; 1491 int endoff; 1492 1493 if (size == 0) /* handle degenerate case */ 1494 return; 1495 1496 /* 1497 * If the base is not DEV_BSIZE aligned and the valid 1498 * bit is clear, we have to zero out a portion of the 1499 * first block. 1500 */ 1501 1502 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1503 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1504 ) { 1505 pmap_zero_page_area( 1506 VM_PAGE_TO_PHYS(m), 1507 frag, 1508 base - frag 1509 ); 1510 } 1511 1512 /* 1513 * If the ending offset is not DEV_BSIZE aligned and the 1514 * valid bit is clear, we have to zero out a portion of 1515 * the last block. 1516 */ 1517 1518 endoff = base + size; 1519 1520 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1521 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1522 ) { 1523 pmap_zero_page_area( 1524 VM_PAGE_TO_PHYS(m), 1525 endoff, 1526 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1527 ); 1528 } 1529 1530 /* 1531 * Set valid, clear dirty bits. If validating the entire 1532 * page we can safely clear the pmap modify bit. We also 1533 * use this opportunity to clear the PG_NOSYNC flag. If a process 1534 * takes a write fault on a MAP_NOSYNC memory area the flag will 1535 * be set again. 1536 * 1537 * We set valid bits inclusive of any overlap, but we can only 1538 * clear dirty bits for DEV_BSIZE chunks that are fully within 1539 * the range. 1540 */ 1541 1542 pagebits = vm_page_bits(base, size); 1543 m->valid |= pagebits; 1544 #if 0 /* NOT YET */ 1545 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1546 frag = DEV_BSIZE - frag; 1547 base += frag; 1548 size -= frag; 1549 if (size < 0) 1550 size = 0; 1551 } 1552 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1553 #endif 1554 m->dirty &= ~pagebits; 1555 if (base == 0 && size == PAGE_SIZE) { 1556 pmap_clear_modify(m); 1557 vm_page_flag_clear(m, PG_NOSYNC); 1558 } 1559 } 1560 1561 void 1562 vm_page_clear_dirty(vm_page_t m, int base, int size) 1563 { 1564 m->dirty &= ~vm_page_bits(base, size); 1565 } 1566 1567 /* 1568 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1569 * valid and dirty bits for the effected areas are cleared. 1570 * 1571 * May not block. 1572 */ 1573 void 1574 vm_page_set_invalid(vm_page_t m, int base, int size) 1575 { 1576 int bits; 1577 1578 bits = vm_page_bits(base, size); 1579 m->valid &= ~bits; 1580 m->dirty &= ~bits; 1581 m->object->generation++; 1582 } 1583 1584 /* 1585 * The kernel assumes that the invalid portions of a page contain 1586 * garbage, but such pages can be mapped into memory by user code. 1587 * When this occurs, we must zero out the non-valid portions of the 1588 * page so user code sees what it expects. 1589 * 1590 * Pages are most often semi-valid when the end of a file is mapped 1591 * into memory and the file's size is not page aligned. 1592 */ 1593 void 1594 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1595 { 1596 int b; 1597 int i; 1598 1599 /* 1600 * Scan the valid bits looking for invalid sections that 1601 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1602 * valid bit may be set ) have already been zerod by 1603 * vm_page_set_validclean(). 1604 */ 1605 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1606 if (i == (PAGE_SIZE / DEV_BSIZE) || 1607 (m->valid & (1 << i)) 1608 ) { 1609 if (i > b) { 1610 pmap_zero_page_area( 1611 VM_PAGE_TO_PHYS(m), 1612 b << DEV_BSHIFT, 1613 (i - b) << DEV_BSHIFT 1614 ); 1615 } 1616 b = i + 1; 1617 } 1618 } 1619 1620 /* 1621 * setvalid is TRUE when we can safely set the zero'd areas 1622 * as being valid. We can do this if there are no cache consistency 1623 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1624 */ 1625 if (setvalid) 1626 m->valid = VM_PAGE_BITS_ALL; 1627 } 1628 1629 /* 1630 * Is a (partial) page valid? Note that the case where size == 0 1631 * will return FALSE in the degenerate case where the page is entirely 1632 * invalid, and TRUE otherwise. 1633 * 1634 * May not block. 1635 */ 1636 int 1637 vm_page_is_valid(vm_page_t m, int base, int size) 1638 { 1639 int bits = vm_page_bits(base, size); 1640 1641 if (m->valid && ((m->valid & bits) == bits)) 1642 return 1; 1643 else 1644 return 0; 1645 } 1646 1647 /* 1648 * update dirty bits from pmap/mmu. May not block. 1649 */ 1650 void 1651 vm_page_test_dirty(vm_page_t m) 1652 { 1653 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1654 vm_page_dirty(m); 1655 } 1656 } 1657 1658 #include "opt_ddb.h" 1659 #ifdef DDB 1660 #include <sys/kernel.h> 1661 1662 #include <ddb/ddb.h> 1663 1664 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1665 { 1666 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1667 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1668 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1669 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1670 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1671 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1672 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1673 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1674 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1675 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1676 } 1677 1678 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1679 { 1680 int i; 1681 db_printf("PQ_FREE:"); 1682 for(i=0;i<PQ_L2_SIZE;i++) { 1683 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1684 } 1685 db_printf("\n"); 1686 1687 db_printf("PQ_CACHE:"); 1688 for(i=0;i<PQ_L2_SIZE;i++) { 1689 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1690 } 1691 db_printf("\n"); 1692 1693 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1694 vm_page_queues[PQ_ACTIVE].lcnt, 1695 vm_page_queues[PQ_INACTIVE].lcnt); 1696 } 1697 #endif /* DDB */ 1698