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 1.32 2005/07/27 07:55:15 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 static void vm_page_queue_init(void); 93 static void vm_page_free_wakeup(void); 94 static vm_page_t vm_page_select_cache(vm_object_t, vm_pindex_t); 95 static vm_page_t _vm_page_list_find2(int basequeue, int index); 96 97 static int vm_page_bucket_count; /* How big is array? */ 98 static int vm_page_hash_mask; /* Mask for hash function */ 99 static struct vm_page **vm_page_buckets; /* Array of buckets */ 100 static volatile int vm_page_bucket_generation; 101 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 102 103 #define ASSERT_IN_CRIT_SECTION() KKASSERT(crit_test(curthread)); 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 in a critical section. 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 KKASSERT(m->dirty == 0); 171 172 vpq = &vm_page_queues[m->queue]; 173 if (vpq->flipflop) 174 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 175 else 176 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 177 vpq->flipflop = 1 - vpq->flipflop; 178 179 vm_page_queues[m->queue].lcnt++; 180 return (m); 181 } 182 183 /* 184 * (low level boot) 185 * 186 * Initializes the resident memory module. 187 * 188 * Allocates memory for the page cells, and for the object/offset-to-page 189 * hash table headers. Each page cell is initialized and placed on the 190 * free list. 191 * 192 * starta/enda represents the range of physical memory addresses available 193 * for use (skipping memory already used by the kernel), subject to 194 * phys_avail[]. Note that phys_avail[] has already mapped out memory 195 * already in use by the kernel. 196 */ 197 vm_offset_t 198 vm_page_startup(vm_offset_t vaddr) 199 { 200 vm_offset_t mapped; 201 struct vm_page **bucket; 202 vm_size_t npages; 203 vm_paddr_t page_range; 204 vm_paddr_t new_end; 205 int i; 206 vm_paddr_t pa; 207 int nblocks; 208 vm_paddr_t last_pa; 209 vm_paddr_t end; 210 vm_paddr_t biggestone, biggestsize; 211 212 vm_paddr_t total; 213 214 total = 0; 215 biggestsize = 0; 216 biggestone = 0; 217 nblocks = 0; 218 vaddr = round_page(vaddr); 219 220 for (i = 0; phys_avail[i + 1]; i += 2) { 221 phys_avail[i] = round_page(phys_avail[i]); 222 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 223 } 224 225 for (i = 0; phys_avail[i + 1]; i += 2) { 226 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 227 228 if (size > biggestsize) { 229 biggestone = i; 230 biggestsize = size; 231 } 232 ++nblocks; 233 total += size; 234 } 235 236 end = phys_avail[biggestone+1]; 237 238 /* 239 * Initialize the queue headers for the free queue, the active queue 240 * and the inactive queue. 241 */ 242 243 vm_page_queue_init(); 244 245 /* 246 * Allocate (and initialize) the hash table buckets. 247 * 248 * The number of buckets MUST BE a power of 2, and the actual value is 249 * the next power of 2 greater than the number of physical pages in 250 * the system. 251 * 252 * We make the hash table approximately 2x the number of pages to 253 * reduce the chain length. This is about the same size using the 254 * singly-linked list as the 1x hash table we were using before 255 * using TAILQ but the chain length will be smaller. 256 * 257 * Note: This computation can be tweaked if desired. 258 */ 259 vm_page_buckets = (struct vm_page **)vaddr; 260 bucket = vm_page_buckets; 261 if (vm_page_bucket_count == 0) { 262 vm_page_bucket_count = 1; 263 while (vm_page_bucket_count < atop(total)) 264 vm_page_bucket_count <<= 1; 265 } 266 vm_page_bucket_count <<= 1; 267 vm_page_hash_mask = vm_page_bucket_count - 1; 268 269 /* 270 * Cut a chunk out of the largest block of physical memory, 271 * moving its end point down to accomodate the hash table and 272 * vm_page_array. 273 */ 274 new_end = end - vm_page_bucket_count * sizeof(struct vm_page *); 275 new_end = trunc_page(new_end); 276 mapped = round_page(vaddr); 277 vaddr = pmap_map(mapped, new_end, end, 278 VM_PROT_READ | VM_PROT_WRITE); 279 vaddr = round_page(vaddr); 280 bzero((caddr_t) mapped, vaddr - mapped); 281 282 for (i = 0; i < vm_page_bucket_count; i++) { 283 *bucket = NULL; 284 bucket++; 285 } 286 287 /* 288 * Compute the number of pages of memory that will be available for 289 * use (taking into account the overhead of a page structure per 290 * page). 291 */ 292 first_page = phys_avail[0] / PAGE_SIZE; 293 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 294 npages = (total - (page_range * sizeof(struct vm_page)) - 295 (end - new_end)) / PAGE_SIZE; 296 297 end = new_end; 298 299 /* 300 * Initialize the mem entry structures now, and put them in the free 301 * queue. 302 */ 303 vm_page_array = (vm_page_t) vaddr; 304 mapped = vaddr; 305 306 /* 307 * Validate these addresses. 308 */ 309 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 310 mapped = pmap_map(mapped, new_end, end, 311 VM_PROT_READ | VM_PROT_WRITE); 312 313 /* 314 * Clear all of the page structures 315 */ 316 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 317 vm_page_array_size = page_range; 318 319 /* 320 * Construct the free queue(s) in ascending order (by physical 321 * address) so that the first 16MB of physical memory is allocated 322 * last rather than first. On large-memory machines, this avoids 323 * the exhaustion of low physical memory before isa_dmainit has run. 324 */ 325 vmstats.v_page_count = 0; 326 vmstats.v_free_count = 0; 327 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 328 pa = phys_avail[i]; 329 if (i == biggestone) 330 last_pa = new_end; 331 else 332 last_pa = phys_avail[i + 1]; 333 while (pa < last_pa && npages-- > 0) { 334 vm_add_new_page(pa); 335 pa += PAGE_SIZE; 336 } 337 } 338 return (mapped); 339 } 340 341 /* 342 * Distributes the object/offset key pair among hash buckets. 343 * 344 * NOTE: This macro depends on vm_page_bucket_count being a power of 2. 345 * This routine may not block. 346 * 347 * We try to randomize the hash based on the object to spread the pages 348 * out in the hash table without it costing us too much. 349 */ 350 static __inline int 351 vm_page_hash(vm_object_t object, vm_pindex_t pindex) 352 { 353 int i = ((uintptr_t)object + pindex) ^ object->hash_rand; 354 355 return(i & vm_page_hash_mask); 356 } 357 358 /* 359 * The opposite of vm_page_hold(). A page can be freed while being held, 360 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 361 * in this case to actually free it once the hold count drops to 0. 362 * 363 * This routine must be called at splvm(). 364 */ 365 void 366 vm_page_unhold(vm_page_t mem) 367 { 368 --mem->hold_count; 369 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 370 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) { 371 vm_page_busy(mem); 372 vm_page_free_toq(mem); 373 } 374 } 375 376 /* 377 * Inserts the given mem entry into the object and object list. 378 * 379 * The pagetables are not updated but will presumably fault the page 380 * in if necessary, or if a kernel page the caller will at some point 381 * enter the page into the kernel's pmap. We are not allowed to block 382 * here so we *can't* do this anyway. 383 * 384 * This routine may not block. 385 * This routine must be called with a critical section held. 386 */ 387 void 388 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 389 { 390 struct vm_page **bucket; 391 392 ASSERT_IN_CRIT_SECTION(); 393 if (m->object != NULL) 394 panic("vm_page_insert: already inserted"); 395 396 /* 397 * Record the object/offset pair in this page 398 */ 399 m->object = object; 400 m->pindex = pindex; 401 402 /* 403 * Insert it into the object_object/offset hash table 404 */ 405 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 406 m->hnext = *bucket; 407 *bucket = m; 408 vm_page_bucket_generation++; 409 410 /* 411 * Now link into the object's list of backed pages. 412 */ 413 TAILQ_INSERT_TAIL(&object->memq, m, listq); 414 object->generation++; 415 416 /* 417 * show that the object has one more resident page. 418 */ 419 object->resident_page_count++; 420 421 /* 422 * Since we are inserting a new and possibly dirty page, 423 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 424 */ 425 if (m->flags & PG_WRITEABLE) 426 vm_object_set_writeable_dirty(object); 427 } 428 429 /* 430 * Removes the given vm_page_t from the global (object,index) hash table 431 * and from the object's memq. 432 * 433 * The underlying pmap entry (if any) is NOT removed here. 434 * This routine may not block. 435 * 436 * The page must be BUSY and will remain BUSY on return. No spl needs to be 437 * held on call to this routine. 438 * 439 * note: FreeBSD side effect was to unbusy the page on return. We leave 440 * it busy. 441 */ 442 void 443 vm_page_remove(vm_page_t m) 444 { 445 vm_object_t object; 446 struct vm_page **bucket; 447 448 crit_enter(); 449 if (m->object == NULL) { 450 crit_exit(); 451 return; 452 } 453 454 if ((m->flags & PG_BUSY) == 0) 455 panic("vm_page_remove: page not busy"); 456 457 object = m->object; 458 459 /* 460 * Remove from the object_object/offset hash table. The object 461 * must be on the hash queue, we will panic if it isn't 462 * 463 * Note: we must NULL-out m->hnext to prevent loops in detached 464 * buffers with vm_page_lookup(). 465 */ 466 bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)]; 467 while (*bucket != m) { 468 if (*bucket == NULL) 469 panic("vm_page_remove(): page not found in hash"); 470 bucket = &(*bucket)->hnext; 471 } 472 *bucket = m->hnext; 473 m->hnext = NULL; 474 vm_page_bucket_generation++; 475 476 /* 477 * Now remove from the object's list of backed pages. 478 */ 479 TAILQ_REMOVE(&object->memq, m, listq); 480 481 /* 482 * And show that the object has one fewer resident page. 483 */ 484 object->resident_page_count--; 485 object->generation++; 486 487 m->object = NULL; 488 crit_exit(); 489 } 490 491 /* 492 * Locate and return the page at (object, pindex), or NULL if the 493 * page could not be found. 494 * 495 * This routine will operate properly without spl protection, but 496 * the returned page could be in flux if it is busy. Because an 497 * interrupt can race a caller's busy check (unbusying and freeing the 498 * page we return before the caller is able to check the busy bit), 499 * the caller should generally call this routine with a critical 500 * section held. 501 * 502 * Callers may call this routine without spl protection if they know 503 * 'for sure' that the page will not be ripped out from under them 504 * by an interrupt. 505 */ 506 vm_page_t 507 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 508 { 509 vm_page_t m; 510 struct vm_page **bucket; 511 int generation; 512 513 /* 514 * Search the hash table for this object/offset pair 515 */ 516 retry: 517 generation = vm_page_bucket_generation; 518 bucket = &vm_page_buckets[vm_page_hash(object, pindex)]; 519 for (m = *bucket; m != NULL; m = m->hnext) { 520 if ((m->object == object) && (m->pindex == pindex)) { 521 if (vm_page_bucket_generation != generation) 522 goto retry; 523 return (m); 524 } 525 } 526 if (vm_page_bucket_generation != generation) 527 goto retry; 528 return (NULL); 529 } 530 531 /* 532 * vm_page_rename() 533 * 534 * Move the given memory entry from its current object to the specified 535 * target object/offset. 536 * 537 * The object must be locked. 538 * This routine may not block. 539 * 540 * Note: This routine will raise itself to splvm(), the caller need not. 541 * 542 * Note: Swap associated with the page must be invalidated by the move. We 543 * have to do this for several reasons: (1) we aren't freeing the 544 * page, (2) we are dirtying the page, (3) the VM system is probably 545 * moving the page from object A to B, and will then later move 546 * the backing store from A to B and we can't have a conflict. 547 * 548 * Note: We *always* dirty the page. It is necessary both for the 549 * fact that we moved it, and because we may be invalidating 550 * swap. If the page is on the cache, we have to deactivate it 551 * or vm_page_dirty() will panic. Dirty pages are not allowed 552 * on the cache. 553 */ 554 void 555 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 556 { 557 crit_enter(); 558 vm_page_remove(m); 559 vm_page_insert(m, new_object, new_pindex); 560 if (m->queue - m->pc == PQ_CACHE) 561 vm_page_deactivate(m); 562 vm_page_dirty(m); 563 vm_page_wakeup(m); 564 crit_exit(); 565 } 566 567 /* 568 * vm_page_unqueue() without any wakeup. This routine is used when a page 569 * is being moved between queues or otherwise is to remain BUSYied by the 570 * caller. 571 * 572 * This routine must be called at splhigh(). 573 * This routine may not block. 574 */ 575 void 576 vm_page_unqueue_nowakeup(vm_page_t m) 577 { 578 int queue = m->queue; 579 struct vpgqueues *pq; 580 581 if (queue != PQ_NONE) { 582 pq = &vm_page_queues[queue]; 583 m->queue = PQ_NONE; 584 TAILQ_REMOVE(&pq->pl, m, pageq); 585 (*pq->cnt)--; 586 pq->lcnt--; 587 } 588 } 589 590 /* 591 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 592 * if necessary. 593 * 594 * This routine must be called at splhigh(). 595 * This routine may not block. 596 */ 597 void 598 vm_page_unqueue(vm_page_t m) 599 { 600 int queue = m->queue; 601 struct vpgqueues *pq; 602 603 if (queue != PQ_NONE) { 604 m->queue = PQ_NONE; 605 pq = &vm_page_queues[queue]; 606 TAILQ_REMOVE(&pq->pl, m, pageq); 607 (*pq->cnt)--; 608 pq->lcnt--; 609 if ((queue - m->pc) == PQ_CACHE) { 610 if (vm_paging_needed()) 611 pagedaemon_wakeup(); 612 } 613 } 614 } 615 616 /* 617 * vm_page_list_find() 618 * 619 * Find a page on the specified queue with color optimization. 620 * 621 * The page coloring optimization attempts to locate a page that does 622 * not overload other nearby pages in the object in the cpu's L1 or L2 623 * caches. We need this optimization because cpu caches tend to be 624 * physical caches, while object spaces tend to be virtual. 625 * 626 * This routine must be called at splvm(). 627 * This routine may not block. 628 * 629 * Note that this routine is carefully inlined. A non-inlined version 630 * is available for outside callers but the only critical path is 631 * from within this source file. 632 */ 633 static __inline 634 vm_page_t 635 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 636 { 637 vm_page_t m; 638 639 if (prefer_zero) 640 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 641 else 642 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 643 if (m == NULL) 644 m = _vm_page_list_find2(basequeue, index); 645 return(m); 646 } 647 648 static vm_page_t 649 _vm_page_list_find2(int basequeue, int index) 650 { 651 int i; 652 vm_page_t m = NULL; 653 struct vpgqueues *pq; 654 655 pq = &vm_page_queues[basequeue]; 656 657 /* 658 * Note that for the first loop, index+i and index-i wind up at the 659 * same place. Even though this is not totally optimal, we've already 660 * blown it by missing the cache case so we do not care. 661 */ 662 663 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 664 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 665 break; 666 667 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 668 break; 669 } 670 return(m); 671 } 672 673 vm_page_t 674 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 675 { 676 return(_vm_page_list_find(basequeue, index, prefer_zero)); 677 } 678 679 /* 680 * Find a page on the cache queue with color optimization. As pages 681 * might be found, but not applicable, they are deactivated. This 682 * keeps us from using potentially busy cached pages. 683 * 684 * This routine must be called with a critical section held. 685 * This routine may not block. 686 */ 687 vm_page_t 688 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 689 { 690 vm_page_t m; 691 692 while (TRUE) { 693 m = _vm_page_list_find( 694 PQ_CACHE, 695 (pindex + object->pg_color) & PQ_L2_MASK, 696 FALSE 697 ); 698 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 699 m->hold_count || m->wire_count)) { 700 vm_page_deactivate(m); 701 continue; 702 } 703 return m; 704 } 705 /* not reached */ 706 } 707 708 /* 709 * Find a free or zero page, with specified preference. We attempt to 710 * inline the nominal case and fall back to _vm_page_select_free() 711 * otherwise. 712 * 713 * This routine must be called with a critical section held. 714 * This routine may not block. 715 */ 716 static __inline vm_page_t 717 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 718 { 719 vm_page_t m; 720 721 m = _vm_page_list_find( 722 PQ_FREE, 723 (pindex + object->pg_color) & PQ_L2_MASK, 724 prefer_zero 725 ); 726 return(m); 727 } 728 729 /* 730 * vm_page_alloc() 731 * 732 * Allocate and return a memory cell associated with this VM object/offset 733 * pair. 734 * 735 * page_req classes: 736 * 737 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 738 * VM_ALLOC_SYSTEM greater free drain 739 * VM_ALLOC_INTERRUPT allow free list to be completely drained 740 * VM_ALLOC_ZERO advisory request for pre-zero'd page 741 * 742 * The object must be locked. 743 * This routine may not block. 744 * The returned page will be marked PG_BUSY 745 * 746 * Additional special handling is required when called from an interrupt 747 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 748 * in this case. 749 */ 750 vm_page_t 751 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 752 { 753 vm_page_t m = NULL; 754 755 KASSERT(!vm_page_lookup(object, pindex), 756 ("vm_page_alloc: page already allocated")); 757 KKASSERT(page_req & 758 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 759 760 /* 761 * The pager is allowed to eat deeper into the free page list. 762 */ 763 if (curthread == pagethread) 764 page_req |= VM_ALLOC_SYSTEM; 765 766 crit_enter(); 767 loop: 768 if (vmstats.v_free_count > vmstats.v_free_reserved || 769 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 770 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 771 vmstats.v_free_count > vmstats.v_interrupt_free_min) 772 ) { 773 /* 774 * The free queue has sufficient free pages to take one out. 775 */ 776 if (page_req & VM_ALLOC_ZERO) 777 m = vm_page_select_free(object, pindex, TRUE); 778 else 779 m = vm_page_select_free(object, pindex, FALSE); 780 } else if (page_req & VM_ALLOC_NORMAL) { 781 /* 782 * Allocatable from the cache (non-interrupt only). On 783 * success, we must free the page and try again, thus 784 * ensuring that vmstats.v_*_free_min counters are replenished. 785 */ 786 #ifdef INVARIANTS 787 if (curthread->td_preempted) { 788 printf("vm_page_alloc(): warning, attempt to allocate" 789 " cache page from preempting interrupt\n"); 790 m = NULL; 791 } else { 792 m = vm_page_select_cache(object, pindex); 793 } 794 #else 795 m = vm_page_select_cache(object, pindex); 796 #endif 797 /* 798 * On success move the page into the free queue and loop. 799 */ 800 if (m != NULL) { 801 KASSERT(m->dirty == 0, 802 ("Found dirty cache page %p", m)); 803 vm_page_busy(m); 804 vm_page_protect(m, VM_PROT_NONE); 805 vm_page_free(m); 806 goto loop; 807 } 808 809 /* 810 * On failure return NULL 811 */ 812 crit_exit(); 813 #if defined(DIAGNOSTIC) 814 if (vmstats.v_cache_count > 0) 815 printf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 816 #endif 817 vm_pageout_deficit++; 818 pagedaemon_wakeup(); 819 return (NULL); 820 } else { 821 /* 822 * No pages available, wakeup the pageout daemon and give up. 823 */ 824 crit_exit(); 825 vm_pageout_deficit++; 826 pagedaemon_wakeup(); 827 return (NULL); 828 } 829 830 /* 831 * Good page found. The page has not yet been busied. We are in 832 * a critical section. 833 */ 834 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 835 KASSERT(m->dirty == 0, 836 ("vm_page_alloc: free/cache page %p was dirty", m)); 837 838 /* 839 * Remove from free queue 840 */ 841 vm_page_unqueue_nowakeup(m); 842 843 /* 844 * Initialize structure. Only the PG_ZERO flag is inherited. Set 845 * the page PG_BUSY 846 */ 847 if (m->flags & PG_ZERO) { 848 vm_page_zero_count--; 849 m->flags = PG_ZERO | PG_BUSY; 850 } else { 851 m->flags = PG_BUSY; 852 } 853 m->wire_count = 0; 854 m->hold_count = 0; 855 m->act_count = 0; 856 m->busy = 0; 857 m->valid = 0; 858 859 /* 860 * vm_page_insert() is safe prior to the crit_exit(). Note also that 861 * inserting a page here does not insert it into the pmap (which 862 * could cause us to block allocating memory). We cannot block 863 * anywhere. 864 */ 865 vm_page_insert(m, object, pindex); 866 867 /* 868 * Don't wakeup too often - wakeup the pageout daemon when 869 * we would be nearly out of memory. 870 */ 871 if (vm_paging_needed()) 872 pagedaemon_wakeup(); 873 874 crit_exit(); 875 876 /* 877 * A PG_BUSY page is returned. 878 */ 879 return (m); 880 } 881 882 /* 883 * Block until free pages are available for allocation, called in various 884 * places before memory allocations. 885 */ 886 void 887 vm_wait(void) 888 { 889 crit_enter(); 890 if (curthread == pagethread) { 891 vm_pageout_pages_needed = 1; 892 tsleep(&vm_pageout_pages_needed, 0, "VMWait", 0); 893 } else { 894 if (!vm_pages_needed) { 895 vm_pages_needed = 1; 896 wakeup(&vm_pages_needed); 897 } 898 tsleep(&vmstats.v_free_count, 0, "vmwait", 0); 899 } 900 crit_exit(); 901 } 902 903 /* 904 * Block until free pages are available for allocation 905 * 906 * Called only in vm_fault so that processes page faulting can be 907 * easily tracked. 908 * 909 * Sleeps at a lower priority than vm_wait() so that vm_wait()ing 910 * processes will be able to grab memory first. Do not change 911 * this balance without careful testing first. 912 */ 913 void 914 vm_waitpfault(void) 915 { 916 crit_enter(); 917 if (!vm_pages_needed) { 918 vm_pages_needed = 1; 919 wakeup(&vm_pages_needed); 920 } 921 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 922 crit_exit(); 923 } 924 925 /* 926 * Put the specified page on the active list (if appropriate). Ensure 927 * that act_count is at least ACT_INIT but do not otherwise mess with it. 928 * 929 * The page queues must be locked. 930 * This routine may not block. 931 */ 932 void 933 vm_page_activate(vm_page_t m) 934 { 935 crit_enter(); 936 if (m->queue != PQ_ACTIVE) { 937 if ((m->queue - m->pc) == PQ_CACHE) 938 mycpu->gd_cnt.v_reactivated++; 939 940 vm_page_unqueue(m); 941 942 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 943 m->queue = PQ_ACTIVE; 944 vm_page_queues[PQ_ACTIVE].lcnt++; 945 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 946 m, pageq); 947 if (m->act_count < ACT_INIT) 948 m->act_count = ACT_INIT; 949 vmstats.v_active_count++; 950 } 951 } else { 952 if (m->act_count < ACT_INIT) 953 m->act_count = ACT_INIT; 954 } 955 crit_exit(); 956 } 957 958 /* 959 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 960 * routine is called when a page has been added to the cache or free 961 * queues. 962 * 963 * This routine may not block. 964 * This routine must be called at splvm() 965 */ 966 static __inline void 967 vm_page_free_wakeup(void) 968 { 969 /* 970 * if pageout daemon needs pages, then tell it that there are 971 * some free. 972 */ 973 if (vm_pageout_pages_needed && 974 vmstats.v_cache_count + vmstats.v_free_count >= 975 vmstats.v_pageout_free_min 976 ) { 977 wakeup(&vm_pageout_pages_needed); 978 vm_pageout_pages_needed = 0; 979 } 980 981 /* 982 * wakeup processes that are waiting on memory if we hit a 983 * high water mark. And wakeup scheduler process if we have 984 * lots of memory. this process will swapin processes. 985 */ 986 if (vm_pages_needed && !vm_page_count_min()) { 987 vm_pages_needed = 0; 988 wakeup(&vmstats.v_free_count); 989 } 990 } 991 992 /* 993 * vm_page_free_toq: 994 * 995 * Returns the given page to the PQ_FREE list, disassociating it with 996 * any VM object. 997 * 998 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 999 * return (the page will have been freed). No particular spl is required 1000 * on entry. 1001 * 1002 * This routine may not block. 1003 */ 1004 void 1005 vm_page_free_toq(vm_page_t m) 1006 { 1007 struct vpgqueues *pq; 1008 1009 crit_enter(); 1010 mycpu->gd_cnt.v_tfree++; 1011 1012 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1013 printf( 1014 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1015 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1016 m->hold_count); 1017 if ((m->queue - m->pc) == PQ_FREE) 1018 panic("vm_page_free: freeing free page"); 1019 else 1020 panic("vm_page_free: freeing busy page"); 1021 } 1022 1023 /* 1024 * unqueue, then remove page. Note that we cannot destroy 1025 * the page here because we do not want to call the pager's 1026 * callback routine until after we've put the page on the 1027 * appropriate free queue. 1028 */ 1029 vm_page_unqueue_nowakeup(m); 1030 vm_page_remove(m); 1031 1032 /* 1033 * No further management of fictitious pages occurs beyond object 1034 * and queue removal. 1035 */ 1036 if ((m->flags & PG_FICTITIOUS) != 0) { 1037 vm_page_wakeup(m); 1038 crit_exit(); 1039 return; 1040 } 1041 1042 m->valid = 0; 1043 vm_page_undirty(m); 1044 1045 if (m->wire_count != 0) { 1046 if (m->wire_count > 1) { 1047 panic( 1048 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1049 m->wire_count, (long)m->pindex); 1050 } 1051 panic("vm_page_free: freeing wired page"); 1052 } 1053 1054 /* 1055 * Clear the UNMANAGED flag when freeing an unmanaged page. 1056 */ 1057 if (m->flags & PG_UNMANAGED) { 1058 m->flags &= ~PG_UNMANAGED; 1059 } 1060 1061 if (m->hold_count != 0) { 1062 m->flags &= ~PG_ZERO; 1063 m->queue = PQ_HOLD; 1064 } else { 1065 m->queue = PQ_FREE + m->pc; 1066 } 1067 pq = &vm_page_queues[m->queue]; 1068 pq->lcnt++; 1069 ++(*pq->cnt); 1070 1071 /* 1072 * Put zero'd pages on the end ( where we look for zero'd pages 1073 * first ) and non-zerod pages at the head. 1074 */ 1075 if (m->flags & PG_ZERO) { 1076 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1077 ++vm_page_zero_count; 1078 } else { 1079 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1080 } 1081 vm_page_wakeup(m); 1082 vm_page_free_wakeup(); 1083 crit_exit(); 1084 } 1085 1086 /* 1087 * vm_page_unmanage() 1088 * 1089 * Prevent PV management from being done on the page. The page is 1090 * removed from the paging queues as if it were wired, and as a 1091 * consequence of no longer being managed the pageout daemon will not 1092 * touch it (since there is no way to locate the pte mappings for the 1093 * page). madvise() calls that mess with the pmap will also no longer 1094 * operate on the page. 1095 * 1096 * Beyond that the page is still reasonably 'normal'. Freeing the page 1097 * will clear the flag. 1098 * 1099 * This routine is used by OBJT_PHYS objects - objects using unswappable 1100 * physical memory as backing store rather then swap-backed memory and 1101 * will eventually be extended to support 4MB unmanaged physical 1102 * mappings. 1103 * 1104 * Must be called with a critical section held. 1105 */ 1106 void 1107 vm_page_unmanage(vm_page_t m) 1108 { 1109 ASSERT_IN_CRIT_SECTION(); 1110 if ((m->flags & PG_UNMANAGED) == 0) { 1111 if (m->wire_count == 0) 1112 vm_page_unqueue(m); 1113 } 1114 vm_page_flag_set(m, PG_UNMANAGED); 1115 } 1116 1117 /* 1118 * Mark this page as wired down by yet another map, removing it from 1119 * paging queues as necessary. 1120 * 1121 * The page queues must be locked. 1122 * This routine may not block. 1123 */ 1124 void 1125 vm_page_wire(vm_page_t m) 1126 { 1127 /* 1128 * Only bump the wire statistics if the page is not already wired, 1129 * and only unqueue the page if it is on some queue (if it is unmanaged 1130 * it is already off the queues). Don't do anything with fictitious 1131 * pages because they are always wired. 1132 */ 1133 crit_enter(); 1134 if ((m->flags & PG_FICTITIOUS) == 0) { 1135 if (m->wire_count == 0) { 1136 if ((m->flags & PG_UNMANAGED) == 0) 1137 vm_page_unqueue(m); 1138 vmstats.v_wire_count++; 1139 } 1140 m->wire_count++; 1141 KASSERT(m->wire_count != 0, 1142 ("vm_page_wire: wire_count overflow m=%p", m)); 1143 } 1144 vm_page_flag_set(m, PG_MAPPED); 1145 crit_exit(); 1146 } 1147 1148 /* 1149 * Release one wiring of this page, potentially enabling it to be paged again. 1150 * 1151 * Many pages placed on the inactive queue should actually go 1152 * into the cache, but it is difficult to figure out which. What 1153 * we do instead, if the inactive target is well met, is to put 1154 * clean pages at the head of the inactive queue instead of the tail. 1155 * This will cause them to be moved to the cache more quickly and 1156 * if not actively re-referenced, freed more quickly. If we just 1157 * stick these pages at the end of the inactive queue, heavy filesystem 1158 * meta-data accesses can cause an unnecessary paging load on memory bound 1159 * processes. This optimization causes one-time-use metadata to be 1160 * reused more quickly. 1161 * 1162 * BUT, if we are in a low-memory situation we have no choice but to 1163 * put clean pages on the cache queue. 1164 * 1165 * A number of routines use vm_page_unwire() to guarantee that the page 1166 * will go into either the inactive or active queues, and will NEVER 1167 * be placed in the cache - for example, just after dirtying a page. 1168 * dirty pages in the cache are not allowed. 1169 * 1170 * The page queues must be locked. 1171 * This routine may not block. 1172 */ 1173 void 1174 vm_page_unwire(vm_page_t m, int activate) 1175 { 1176 crit_enter(); 1177 if (m->flags & PG_FICTITIOUS) { 1178 /* do nothing */ 1179 } else if (m->wire_count <= 0) { 1180 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1181 } else { 1182 if (--m->wire_count == 0) { 1183 --vmstats.v_wire_count; 1184 if (m->flags & PG_UNMANAGED) { 1185 ; 1186 } else if (activate) { 1187 TAILQ_INSERT_TAIL( 1188 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1189 m->queue = PQ_ACTIVE; 1190 vm_page_queues[PQ_ACTIVE].lcnt++; 1191 vmstats.v_active_count++; 1192 } else { 1193 vm_page_flag_clear(m, PG_WINATCFLS); 1194 TAILQ_INSERT_TAIL( 1195 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1196 m->queue = PQ_INACTIVE; 1197 vm_page_queues[PQ_INACTIVE].lcnt++; 1198 vmstats.v_inactive_count++; 1199 } 1200 } 1201 } 1202 crit_exit(); 1203 } 1204 1205 1206 /* 1207 * Move the specified page to the inactive queue. If the page has 1208 * any associated swap, the swap is deallocated. 1209 * 1210 * Normally athead is 0 resulting in LRU operation. athead is set 1211 * to 1 if we want this page to be 'as if it were placed in the cache', 1212 * except without unmapping it from the process address space. 1213 * 1214 * This routine may not block. 1215 */ 1216 static __inline void 1217 _vm_page_deactivate(vm_page_t m, int athead) 1218 { 1219 /* 1220 * Ignore if already inactive. 1221 */ 1222 if (m->queue == PQ_INACTIVE) 1223 return; 1224 1225 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1226 if ((m->queue - m->pc) == PQ_CACHE) 1227 mycpu->gd_cnt.v_reactivated++; 1228 vm_page_flag_clear(m, PG_WINATCFLS); 1229 vm_page_unqueue(m); 1230 if (athead) 1231 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1232 else 1233 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1234 m->queue = PQ_INACTIVE; 1235 vm_page_queues[PQ_INACTIVE].lcnt++; 1236 vmstats.v_inactive_count++; 1237 } 1238 } 1239 1240 void 1241 vm_page_deactivate(vm_page_t m) 1242 { 1243 crit_enter(); 1244 _vm_page_deactivate(m, 0); 1245 crit_exit(); 1246 } 1247 1248 /* 1249 * vm_page_try_to_cache: 1250 * 1251 * Returns 0 on failure, 1 on success 1252 */ 1253 int 1254 vm_page_try_to_cache(vm_page_t m) 1255 { 1256 crit_enter(); 1257 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1258 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1259 crit_exit(); 1260 return(0); 1261 } 1262 vm_page_test_dirty(m); 1263 if (m->dirty) { 1264 crit_exit(); 1265 return(0); 1266 } 1267 vm_page_cache(m); 1268 crit_exit(); 1269 return(1); 1270 } 1271 1272 /* 1273 * Attempt to free the page. If we cannot free it, we do nothing. 1274 * 1 is returned on success, 0 on failure. 1275 */ 1276 int 1277 vm_page_try_to_free(vm_page_t m) 1278 { 1279 crit_enter(); 1280 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1281 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1282 crit_exit(); 1283 return(0); 1284 } 1285 vm_page_test_dirty(m); 1286 if (m->dirty) { 1287 crit_exit(); 1288 return(0); 1289 } 1290 vm_page_busy(m); 1291 vm_page_protect(m, VM_PROT_NONE); 1292 vm_page_free(m); 1293 crit_exit(); 1294 return(1); 1295 } 1296 1297 /* 1298 * vm_page_cache 1299 * 1300 * Put the specified page onto the page cache queue (if appropriate). 1301 * 1302 * This routine may not block. 1303 */ 1304 void 1305 vm_page_cache(vm_page_t m) 1306 { 1307 ASSERT_IN_CRIT_SECTION(); 1308 1309 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1310 m->wire_count || m->hold_count) { 1311 printf("vm_page_cache: attempting to cache busy/held page\n"); 1312 return; 1313 } 1314 if ((m->queue - m->pc) == PQ_CACHE) 1315 return; 1316 1317 /* 1318 * Remove all pmaps and indicate that the page is not 1319 * writeable or mapped. 1320 */ 1321 1322 vm_page_protect(m, VM_PROT_NONE); 1323 if (m->dirty != 0) { 1324 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1325 (long)m->pindex); 1326 } 1327 vm_page_unqueue_nowakeup(m); 1328 m->queue = PQ_CACHE + m->pc; 1329 vm_page_queues[m->queue].lcnt++; 1330 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1331 vmstats.v_cache_count++; 1332 vm_page_free_wakeup(); 1333 } 1334 1335 /* 1336 * vm_page_dontneed() 1337 * 1338 * Cache, deactivate, or do nothing as appropriate. This routine 1339 * is typically used by madvise() MADV_DONTNEED. 1340 * 1341 * Generally speaking we want to move the page into the cache so 1342 * it gets reused quickly. However, this can result in a silly syndrome 1343 * due to the page recycling too quickly. Small objects will not be 1344 * fully cached. On the otherhand, if we move the page to the inactive 1345 * queue we wind up with a problem whereby very large objects 1346 * unnecessarily blow away our inactive and cache queues. 1347 * 1348 * The solution is to move the pages based on a fixed weighting. We 1349 * either leave them alone, deactivate them, or move them to the cache, 1350 * where moving them to the cache has the highest weighting. 1351 * By forcing some pages into other queues we eventually force the 1352 * system to balance the queues, potentially recovering other unrelated 1353 * space from active. The idea is to not force this to happen too 1354 * often. 1355 */ 1356 void 1357 vm_page_dontneed(vm_page_t m) 1358 { 1359 static int dnweight; 1360 int dnw; 1361 int head; 1362 1363 dnw = ++dnweight; 1364 1365 /* 1366 * occassionally leave the page alone 1367 */ 1368 crit_enter(); 1369 if ((dnw & 0x01F0) == 0 || 1370 m->queue == PQ_INACTIVE || 1371 m->queue - m->pc == PQ_CACHE 1372 ) { 1373 if (m->act_count >= ACT_INIT) 1374 --m->act_count; 1375 crit_exit(); 1376 return; 1377 } 1378 1379 if (m->dirty == 0) 1380 vm_page_test_dirty(m); 1381 1382 if (m->dirty || (dnw & 0x0070) == 0) { 1383 /* 1384 * Deactivate the page 3 times out of 32. 1385 */ 1386 head = 0; 1387 } else { 1388 /* 1389 * Cache the page 28 times out of every 32. Note that 1390 * the page is deactivated instead of cached, but placed 1391 * at the head of the queue instead of the tail. 1392 */ 1393 head = 1; 1394 } 1395 _vm_page_deactivate(m, head); 1396 crit_exit(); 1397 } 1398 1399 /* 1400 * Grab a page, blocking if it is busy and allocating a page if necessary. 1401 * A busy page is returned or NULL. 1402 * 1403 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1404 * If VM_ALLOC_RETRY is not specified 1405 * 1406 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1407 * always returned if we had blocked. 1408 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1409 * This routine may not be called from an interrupt. 1410 * The returned page may not be entirely valid. 1411 * 1412 * This routine may be called from mainline code without spl protection and 1413 * be guarenteed a busied page associated with the object at the specified 1414 * index. 1415 */ 1416 vm_page_t 1417 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1418 { 1419 vm_page_t m; 1420 int generation; 1421 1422 KKASSERT(allocflags & 1423 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1424 crit_enter(); 1425 retrylookup: 1426 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1427 if (m->busy || (m->flags & PG_BUSY)) { 1428 generation = object->generation; 1429 1430 while ((object->generation == generation) && 1431 (m->busy || (m->flags & PG_BUSY))) { 1432 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1433 tsleep(m, 0, "pgrbwt", 0); 1434 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1435 m = NULL; 1436 goto done; 1437 } 1438 } 1439 goto retrylookup; 1440 } else { 1441 vm_page_busy(m); 1442 goto done; 1443 } 1444 } 1445 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1446 if (m == NULL) { 1447 vm_wait(); 1448 if ((allocflags & VM_ALLOC_RETRY) == 0) 1449 goto done; 1450 goto retrylookup; 1451 } 1452 done: 1453 crit_exit(); 1454 return(m); 1455 } 1456 1457 /* 1458 * Mapping function for valid bits or for dirty bits in 1459 * a page. May not block. 1460 * 1461 * Inputs are required to range within a page. 1462 */ 1463 __inline int 1464 vm_page_bits(int base, int size) 1465 { 1466 int first_bit; 1467 int last_bit; 1468 1469 KASSERT( 1470 base + size <= PAGE_SIZE, 1471 ("vm_page_bits: illegal base/size %d/%d", base, size) 1472 ); 1473 1474 if (size == 0) /* handle degenerate case */ 1475 return(0); 1476 1477 first_bit = base >> DEV_BSHIFT; 1478 last_bit = (base + size - 1) >> DEV_BSHIFT; 1479 1480 return ((2 << last_bit) - (1 << first_bit)); 1481 } 1482 1483 /* 1484 * Sets portions of a page valid and clean. The arguments are expected 1485 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1486 * of any partial chunks touched by the range. The invalid portion of 1487 * such chunks will be zero'd. 1488 * 1489 * This routine may not block. 1490 * 1491 * (base + size) must be less then or equal to PAGE_SIZE. 1492 */ 1493 void 1494 vm_page_set_validclean(vm_page_t m, int base, int size) 1495 { 1496 int pagebits; 1497 int frag; 1498 int endoff; 1499 1500 if (size == 0) /* handle degenerate case */ 1501 return; 1502 1503 /* 1504 * If the base is not DEV_BSIZE aligned and the valid 1505 * bit is clear, we have to zero out a portion of the 1506 * first block. 1507 */ 1508 1509 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1510 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1511 ) { 1512 pmap_zero_page_area( 1513 VM_PAGE_TO_PHYS(m), 1514 frag, 1515 base - frag 1516 ); 1517 } 1518 1519 /* 1520 * If the ending offset is not DEV_BSIZE aligned and the 1521 * valid bit is clear, we have to zero out a portion of 1522 * the last block. 1523 */ 1524 1525 endoff = base + size; 1526 1527 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1528 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1529 ) { 1530 pmap_zero_page_area( 1531 VM_PAGE_TO_PHYS(m), 1532 endoff, 1533 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1534 ); 1535 } 1536 1537 /* 1538 * Set valid, clear dirty bits. If validating the entire 1539 * page we can safely clear the pmap modify bit. We also 1540 * use this opportunity to clear the PG_NOSYNC flag. If a process 1541 * takes a write fault on a MAP_NOSYNC memory area the flag will 1542 * be set again. 1543 * 1544 * We set valid bits inclusive of any overlap, but we can only 1545 * clear dirty bits for DEV_BSIZE chunks that are fully within 1546 * the range. 1547 */ 1548 1549 pagebits = vm_page_bits(base, size); 1550 m->valid |= pagebits; 1551 #if 0 /* NOT YET */ 1552 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1553 frag = DEV_BSIZE - frag; 1554 base += frag; 1555 size -= frag; 1556 if (size < 0) 1557 size = 0; 1558 } 1559 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1560 #endif 1561 m->dirty &= ~pagebits; 1562 if (base == 0 && size == PAGE_SIZE) { 1563 pmap_clear_modify(m); 1564 vm_page_flag_clear(m, PG_NOSYNC); 1565 } 1566 } 1567 1568 void 1569 vm_page_clear_dirty(vm_page_t m, int base, int size) 1570 { 1571 m->dirty &= ~vm_page_bits(base, size); 1572 } 1573 1574 /* 1575 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1576 * valid and dirty bits for the effected areas are cleared. 1577 * 1578 * May not block. 1579 */ 1580 void 1581 vm_page_set_invalid(vm_page_t m, int base, int size) 1582 { 1583 int bits; 1584 1585 bits = vm_page_bits(base, size); 1586 m->valid &= ~bits; 1587 m->dirty &= ~bits; 1588 m->object->generation++; 1589 } 1590 1591 /* 1592 * The kernel assumes that the invalid portions of a page contain 1593 * garbage, but such pages can be mapped into memory by user code. 1594 * When this occurs, we must zero out the non-valid portions of the 1595 * page so user code sees what it expects. 1596 * 1597 * Pages are most often semi-valid when the end of a file is mapped 1598 * into memory and the file's size is not page aligned. 1599 */ 1600 void 1601 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1602 { 1603 int b; 1604 int i; 1605 1606 /* 1607 * Scan the valid bits looking for invalid sections that 1608 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1609 * valid bit may be set ) have already been zerod by 1610 * vm_page_set_validclean(). 1611 */ 1612 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1613 if (i == (PAGE_SIZE / DEV_BSIZE) || 1614 (m->valid & (1 << i)) 1615 ) { 1616 if (i > b) { 1617 pmap_zero_page_area( 1618 VM_PAGE_TO_PHYS(m), 1619 b << DEV_BSHIFT, 1620 (i - b) << DEV_BSHIFT 1621 ); 1622 } 1623 b = i + 1; 1624 } 1625 } 1626 1627 /* 1628 * setvalid is TRUE when we can safely set the zero'd areas 1629 * as being valid. We can do this if there are no cache consistency 1630 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1631 */ 1632 if (setvalid) 1633 m->valid = VM_PAGE_BITS_ALL; 1634 } 1635 1636 /* 1637 * Is a (partial) page valid? Note that the case where size == 0 1638 * will return FALSE in the degenerate case where the page is entirely 1639 * invalid, and TRUE otherwise. 1640 * 1641 * May not block. 1642 */ 1643 int 1644 vm_page_is_valid(vm_page_t m, int base, int size) 1645 { 1646 int bits = vm_page_bits(base, size); 1647 1648 if (m->valid && ((m->valid & bits) == bits)) 1649 return 1; 1650 else 1651 return 0; 1652 } 1653 1654 /* 1655 * update dirty bits from pmap/mmu. May not block. 1656 */ 1657 void 1658 vm_page_test_dirty(vm_page_t m) 1659 { 1660 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1661 vm_page_dirty(m); 1662 } 1663 } 1664 1665 #include "opt_ddb.h" 1666 #ifdef DDB 1667 #include <sys/kernel.h> 1668 1669 #include <ddb/ddb.h> 1670 1671 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1672 { 1673 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1674 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1675 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1676 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1677 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1678 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1679 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1680 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1681 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1682 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1683 } 1684 1685 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1686 { 1687 int i; 1688 db_printf("PQ_FREE:"); 1689 for(i=0;i<PQ_L2_SIZE;i++) { 1690 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1691 } 1692 db_printf("\n"); 1693 1694 db_printf("PQ_CACHE:"); 1695 for(i=0;i<PQ_L2_SIZE;i++) { 1696 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1697 } 1698 db_printf("\n"); 1699 1700 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1701 vm_page_queues[PQ_ACTIVE].lcnt, 1702 vm_page_queues[PQ_INACTIVE].lcnt); 1703 } 1704 #endif /* DDB */ 1705