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 1.36 2007/12/06 22:25:49 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 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 98 99 #define ASSERT_IN_CRIT_SECTION() KKASSERT(crit_test(curthread)); 100 101 RB_GENERATE2(vm_page_rb_tree, vm_page, rb_entry, rb_vm_page_compare, 102 vm_pindex_t, pindex); 103 104 static void 105 vm_page_queue_init(void) 106 { 107 int i; 108 109 for (i = 0; i < PQ_L2_SIZE; i++) 110 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 111 for (i = 0; i < PQ_L2_SIZE; i++) 112 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 113 114 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 115 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 116 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 117 /* PQ_NONE has no queue */ 118 119 for (i = 0; i < PQ_COUNT; i++) 120 TAILQ_INIT(&vm_page_queues[i].pl); 121 } 122 123 /* 124 * note: place in initialized data section? Is this necessary? 125 */ 126 long first_page = 0; 127 int vm_page_array_size = 0; 128 int vm_page_zero_count = 0; 129 vm_page_t vm_page_array = 0; 130 131 /* 132 * (low level boot) 133 * 134 * Sets the page size, perhaps based upon the memory size. 135 * Must be called before any use of page-size dependent functions. 136 */ 137 void 138 vm_set_page_size(void) 139 { 140 if (vmstats.v_page_size == 0) 141 vmstats.v_page_size = PAGE_SIZE; 142 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 143 panic("vm_set_page_size: page size not a power of two"); 144 } 145 146 /* 147 * (low level boot) 148 * 149 * Add a new page to the freelist for use by the system. New pages 150 * are added to both the head and tail of the associated free page 151 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 152 * requests pull 'recent' adds (higher physical addresses) first. 153 * 154 * Must be called in a critical section. 155 */ 156 vm_page_t 157 vm_add_new_page(vm_paddr_t pa) 158 { 159 struct vpgqueues *vpq; 160 vm_page_t m; 161 162 ++vmstats.v_page_count; 163 ++vmstats.v_free_count; 164 m = PHYS_TO_VM_PAGE(pa); 165 m->phys_addr = pa; 166 m->flags = 0; 167 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 168 m->queue = m->pc + PQ_FREE; 169 KKASSERT(m->dirty == 0); 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 * starta/enda represents the range of physical memory addresses available 192 * for use (skipping memory already used by the kernel), subject to 193 * phys_avail[]. Note that phys_avail[] has already mapped out memory 194 * already in use by the kernel. 195 */ 196 vm_offset_t 197 vm_page_startup(vm_offset_t vaddr) 198 { 199 vm_offset_t mapped; 200 vm_size_t npages; 201 vm_paddr_t page_range; 202 vm_paddr_t new_end; 203 int i; 204 vm_paddr_t pa; 205 int nblocks; 206 vm_paddr_t last_pa; 207 vm_paddr_t end; 208 vm_paddr_t biggestone, biggestsize; 209 vm_paddr_t total; 210 211 total = 0; 212 biggestsize = 0; 213 biggestone = 0; 214 nblocks = 0; 215 vaddr = round_page(vaddr); 216 217 for (i = 0; phys_avail[i + 1]; i += 2) { 218 phys_avail[i] = round_page(phys_avail[i]); 219 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); 220 } 221 222 for (i = 0; phys_avail[i + 1]; i += 2) { 223 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 224 225 if (size > biggestsize) { 226 biggestone = i; 227 biggestsize = size; 228 } 229 ++nblocks; 230 total += size; 231 } 232 233 end = phys_avail[biggestone+1]; 234 end = trunc_page(end); 235 236 /* 237 * Initialize the queue headers for the free queue, the active queue 238 * and the inactive queue. 239 */ 240 241 vm_page_queue_init(); 242 243 /* 244 * Compute the number of pages of memory that will be available for 245 * use (taking into account the overhead of a page structure per 246 * page). 247 */ 248 first_page = phys_avail[0] / PAGE_SIZE; 249 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 250 npages = (total - (page_range * sizeof(struct vm_page))) / PAGE_SIZE; 251 252 /* 253 * Initialize the mem entry structures now, and put them in the free 254 * queue. 255 */ 256 vm_page_array = (vm_page_t) vaddr; 257 mapped = vaddr; 258 259 /* 260 * Validate these addresses. 261 */ 262 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 263 mapped = pmap_map(mapped, new_end, end, 264 VM_PROT_READ | VM_PROT_WRITE); 265 266 /* 267 * Clear all of the page structures 268 */ 269 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 270 vm_page_array_size = page_range; 271 272 /* 273 * Construct the free queue(s) in ascending order (by physical 274 * address) so that the first 16MB of physical memory is allocated 275 * last rather than first. On large-memory machines, this avoids 276 * the exhaustion of low physical memory before isa_dmainit has run. 277 */ 278 vmstats.v_page_count = 0; 279 vmstats.v_free_count = 0; 280 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 281 pa = phys_avail[i]; 282 if (i == biggestone) 283 last_pa = new_end; 284 else 285 last_pa = phys_avail[i + 1]; 286 while (pa < last_pa && npages-- > 0) { 287 vm_add_new_page(pa); 288 pa += PAGE_SIZE; 289 } 290 } 291 return (mapped); 292 } 293 294 /* 295 * Scan comparison function for Red-Black tree scans. An inclusive 296 * (start,end) is expected. Other fields are not used. 297 */ 298 int 299 rb_vm_page_scancmp(struct vm_page *p, void *data) 300 { 301 struct rb_vm_page_scan_info *info = data; 302 303 if (p->pindex < info->start_pindex) 304 return(-1); 305 if (p->pindex > info->end_pindex) 306 return(1); 307 return(0); 308 } 309 310 int 311 rb_vm_page_compare(struct vm_page *p1, struct vm_page *p2) 312 { 313 if (p1->pindex < p2->pindex) 314 return(-1); 315 if (p1->pindex > p2->pindex) 316 return(1); 317 return(0); 318 } 319 320 /* 321 * The opposite of vm_page_hold(). A page can be freed while being held, 322 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 323 * in this case to actually free it once the hold count drops to 0. 324 * 325 * This routine must be called at splvm(). 326 */ 327 void 328 vm_page_unhold(vm_page_t mem) 329 { 330 --mem->hold_count; 331 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 332 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) { 333 vm_page_busy(mem); 334 vm_page_free_toq(mem); 335 } 336 } 337 338 /* 339 * Inserts the given mem entry into the object and object list. 340 * 341 * The pagetables are not updated but will presumably fault the page 342 * in if necessary, or if a kernel page the caller will at some point 343 * enter the page into the kernel's pmap. We are not allowed to block 344 * here so we *can't* do this anyway. 345 * 346 * This routine may not block. 347 * This routine must be called with a critical section held. 348 */ 349 void 350 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 351 { 352 ASSERT_IN_CRIT_SECTION(); 353 if (m->object != NULL) 354 panic("vm_page_insert: already inserted"); 355 356 /* 357 * Record the object/offset pair in this page 358 */ 359 m->object = object; 360 m->pindex = pindex; 361 362 /* 363 * Insert it into the object. 364 */ 365 vm_page_rb_tree_RB_INSERT(&object->rb_memq, m); 366 object->generation++; 367 368 /* 369 * show that the object has one more resident page. 370 */ 371 object->resident_page_count++; 372 373 /* 374 * Since we are inserting a new and possibly dirty page, 375 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 376 */ 377 if (m->flags & PG_WRITEABLE) 378 vm_object_set_writeable_dirty(object); 379 } 380 381 /* 382 * Removes the given vm_page_t from the global (object,index) hash table 383 * and from the object's memq. 384 * 385 * The underlying pmap entry (if any) is NOT removed here. 386 * This routine may not block. 387 * 388 * The page must be BUSY and will remain BUSY on return. No spl needs to be 389 * held on call to this routine. 390 * 391 * note: FreeBSD side effect was to unbusy the page on return. We leave 392 * it busy. 393 */ 394 void 395 vm_page_remove(vm_page_t m) 396 { 397 vm_object_t object; 398 399 crit_enter(); 400 if (m->object == NULL) { 401 crit_exit(); 402 return; 403 } 404 405 if ((m->flags & PG_BUSY) == 0) 406 panic("vm_page_remove: page not busy"); 407 408 object = m->object; 409 410 /* 411 * Remove the page from the object and update the object. 412 */ 413 vm_page_rb_tree_RB_REMOVE(&object->rb_memq, m); 414 object->resident_page_count--; 415 object->generation++; 416 m->object = NULL; 417 418 crit_exit(); 419 } 420 421 /* 422 * Locate and return the page at (object, pindex), or NULL if the 423 * page could not be found. 424 * 425 * This routine will operate properly without spl protection, but 426 * the returned page could be in flux if it is busy. Because an 427 * interrupt can race a caller's busy check (unbusying and freeing the 428 * page we return before the caller is able to check the busy bit), 429 * the caller should generally call this routine with a critical 430 * section held. 431 * 432 * Callers may call this routine without spl protection if they know 433 * 'for sure' that the page will not be ripped out from under them 434 * by an interrupt. 435 */ 436 vm_page_t 437 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 438 { 439 vm_page_t m; 440 441 /* 442 * Search the hash table for this object/offset pair 443 */ 444 crit_enter(); 445 m = vm_page_rb_tree_RB_LOOKUP(&object->rb_memq, pindex); 446 crit_exit(); 447 KKASSERT(m == NULL || (m->object == object && m->pindex == pindex)); 448 return(m); 449 } 450 451 /* 452 * vm_page_rename() 453 * 454 * Move the given memory entry from its current object to the specified 455 * target object/offset. 456 * 457 * The object must be locked. 458 * This routine may not block. 459 * 460 * Note: This routine will raise itself to splvm(), the caller need not. 461 * 462 * Note: Swap associated with the page must be invalidated by the move. We 463 * have to do this for several reasons: (1) we aren't freeing the 464 * page, (2) we are dirtying the page, (3) the VM system is probably 465 * moving the page from object A to B, and will then later move 466 * the backing store from A to B and we can't have a conflict. 467 * 468 * Note: We *always* dirty the page. It is necessary both for the 469 * fact that we moved it, and because we may be invalidating 470 * swap. If the page is on the cache, we have to deactivate it 471 * or vm_page_dirty() will panic. Dirty pages are not allowed 472 * on the cache. 473 */ 474 void 475 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 476 { 477 crit_enter(); 478 vm_page_remove(m); 479 vm_page_insert(m, new_object, new_pindex); 480 if (m->queue - m->pc == PQ_CACHE) 481 vm_page_deactivate(m); 482 vm_page_dirty(m); 483 vm_page_wakeup(m); 484 crit_exit(); 485 } 486 487 /* 488 * vm_page_unqueue() without any wakeup. This routine is used when a page 489 * is being moved between queues or otherwise is to remain BUSYied by the 490 * caller. 491 * 492 * This routine must be called at splhigh(). 493 * This routine may not block. 494 */ 495 void 496 vm_page_unqueue_nowakeup(vm_page_t m) 497 { 498 int queue = m->queue; 499 struct vpgqueues *pq; 500 501 if (queue != PQ_NONE) { 502 pq = &vm_page_queues[queue]; 503 m->queue = PQ_NONE; 504 TAILQ_REMOVE(&pq->pl, m, pageq); 505 (*pq->cnt)--; 506 pq->lcnt--; 507 } 508 } 509 510 /* 511 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 512 * if necessary. 513 * 514 * This routine must be called at splhigh(). 515 * This routine may not block. 516 */ 517 void 518 vm_page_unqueue(vm_page_t m) 519 { 520 int queue = m->queue; 521 struct vpgqueues *pq; 522 523 if (queue != PQ_NONE) { 524 m->queue = PQ_NONE; 525 pq = &vm_page_queues[queue]; 526 TAILQ_REMOVE(&pq->pl, m, pageq); 527 (*pq->cnt)--; 528 pq->lcnt--; 529 if ((queue - m->pc) == PQ_CACHE) { 530 if (vm_paging_needed()) 531 pagedaemon_wakeup(); 532 } 533 } 534 } 535 536 /* 537 * vm_page_list_find() 538 * 539 * Find a page on the specified queue with color optimization. 540 * 541 * The page coloring optimization attempts to locate a page that does 542 * not overload other nearby pages in the object in the cpu's L1 or L2 543 * caches. We need this optimization because cpu caches tend to be 544 * physical caches, while object spaces tend to be virtual. 545 * 546 * This routine must be called at splvm(). 547 * This routine may not block. 548 * 549 * Note that this routine is carefully inlined. A non-inlined version 550 * is available for outside callers but the only critical path is 551 * from within this source file. 552 */ 553 static __inline 554 vm_page_t 555 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 556 { 557 vm_page_t m; 558 559 if (prefer_zero) 560 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 561 else 562 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 563 if (m == NULL) 564 m = _vm_page_list_find2(basequeue, index); 565 return(m); 566 } 567 568 static vm_page_t 569 _vm_page_list_find2(int basequeue, int index) 570 { 571 int i; 572 vm_page_t m = NULL; 573 struct vpgqueues *pq; 574 575 pq = &vm_page_queues[basequeue]; 576 577 /* 578 * Note that for the first loop, index+i and index-i wind up at the 579 * same place. Even though this is not totally optimal, we've already 580 * blown it by missing the cache case so we do not care. 581 */ 582 583 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 584 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 585 break; 586 587 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 588 break; 589 } 590 return(m); 591 } 592 593 vm_page_t 594 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 595 { 596 return(_vm_page_list_find(basequeue, index, prefer_zero)); 597 } 598 599 /* 600 * Find a page on the cache queue with color optimization. As pages 601 * might be found, but not applicable, they are deactivated. This 602 * keeps us from using potentially busy cached pages. 603 * 604 * This routine must be called with a critical section held. 605 * This routine may not block. 606 */ 607 vm_page_t 608 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 609 { 610 vm_page_t m; 611 612 while (TRUE) { 613 m = _vm_page_list_find( 614 PQ_CACHE, 615 (pindex + object->pg_color) & PQ_L2_MASK, 616 FALSE 617 ); 618 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 619 m->hold_count || m->wire_count)) { 620 vm_page_deactivate(m); 621 continue; 622 } 623 return m; 624 } 625 /* not reached */ 626 } 627 628 /* 629 * Find a free or zero page, with specified preference. We attempt to 630 * inline the nominal case and fall back to _vm_page_select_free() 631 * otherwise. 632 * 633 * This routine must be called with a critical section held. 634 * This routine may not block. 635 */ 636 static __inline vm_page_t 637 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 638 { 639 vm_page_t m; 640 641 m = _vm_page_list_find( 642 PQ_FREE, 643 (pindex + object->pg_color) & PQ_L2_MASK, 644 prefer_zero 645 ); 646 return(m); 647 } 648 649 /* 650 * vm_page_alloc() 651 * 652 * Allocate and return a memory cell associated with this VM object/offset 653 * pair. 654 * 655 * page_req classes: 656 * 657 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 658 * VM_ALLOC_SYSTEM greater free drain 659 * VM_ALLOC_INTERRUPT allow free list to be completely drained 660 * VM_ALLOC_ZERO advisory request for pre-zero'd page 661 * 662 * The object must be locked. 663 * This routine may not block. 664 * The returned page will be marked PG_BUSY 665 * 666 * Additional special handling is required when called from an interrupt 667 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 668 * in this case. 669 */ 670 vm_page_t 671 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 672 { 673 vm_page_t m = NULL; 674 675 KASSERT(!vm_page_lookup(object, pindex), 676 ("vm_page_alloc: page already allocated")); 677 KKASSERT(page_req & 678 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 679 680 /* 681 * The pager is allowed to eat deeper into the free page list. 682 */ 683 if (curthread == pagethread) 684 page_req |= VM_ALLOC_SYSTEM; 685 686 crit_enter(); 687 loop: 688 if (vmstats.v_free_count > vmstats.v_free_reserved || 689 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 690 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 691 vmstats.v_free_count > vmstats.v_interrupt_free_min) 692 ) { 693 /* 694 * The free queue has sufficient free pages to take one out. 695 */ 696 if (page_req & VM_ALLOC_ZERO) 697 m = vm_page_select_free(object, pindex, TRUE); 698 else 699 m = vm_page_select_free(object, pindex, FALSE); 700 } else if (page_req & VM_ALLOC_NORMAL) { 701 /* 702 * Allocatable from the cache (non-interrupt only). On 703 * success, we must free the page and try again, thus 704 * ensuring that vmstats.v_*_free_min counters are replenished. 705 */ 706 #ifdef INVARIANTS 707 if (curthread->td_preempted) { 708 kprintf("vm_page_alloc(): warning, attempt to allocate" 709 " cache page from preempting interrupt\n"); 710 m = NULL; 711 } else { 712 m = vm_page_select_cache(object, pindex); 713 } 714 #else 715 m = vm_page_select_cache(object, pindex); 716 #endif 717 /* 718 * On success move the page into the free queue and loop. 719 */ 720 if (m != NULL) { 721 KASSERT(m->dirty == 0, 722 ("Found dirty cache page %p", m)); 723 vm_page_busy(m); 724 vm_page_protect(m, VM_PROT_NONE); 725 vm_page_free(m); 726 goto loop; 727 } 728 729 /* 730 * On failure return NULL 731 */ 732 crit_exit(); 733 #if defined(DIAGNOSTIC) 734 if (vmstats.v_cache_count > 0) 735 kprintf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 736 #endif 737 vm_pageout_deficit++; 738 pagedaemon_wakeup(); 739 return (NULL); 740 } else { 741 /* 742 * No pages available, wakeup the pageout daemon and give up. 743 */ 744 crit_exit(); 745 vm_pageout_deficit++; 746 pagedaemon_wakeup(); 747 return (NULL); 748 } 749 750 /* 751 * Good page found. The page has not yet been busied. We are in 752 * a critical section. 753 */ 754 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 755 KASSERT(m->dirty == 0, 756 ("vm_page_alloc: free/cache page %p was dirty", m)); 757 758 /* 759 * Remove from free queue 760 */ 761 vm_page_unqueue_nowakeup(m); 762 763 /* 764 * Initialize structure. Only the PG_ZERO flag is inherited. Set 765 * the page PG_BUSY 766 */ 767 if (m->flags & PG_ZERO) { 768 vm_page_zero_count--; 769 m->flags = PG_ZERO | PG_BUSY; 770 } else { 771 m->flags = PG_BUSY; 772 } 773 m->wire_count = 0; 774 m->hold_count = 0; 775 m->act_count = 0; 776 m->busy = 0; 777 m->valid = 0; 778 779 /* 780 * vm_page_insert() is safe prior to the crit_exit(). Note also that 781 * inserting a page here does not insert it into the pmap (which 782 * could cause us to block allocating memory). We cannot block 783 * anywhere. 784 */ 785 vm_page_insert(m, object, pindex); 786 787 /* 788 * Don't wakeup too often - wakeup the pageout daemon when 789 * we would be nearly out of memory. 790 */ 791 if (vm_paging_needed()) 792 pagedaemon_wakeup(); 793 794 crit_exit(); 795 796 /* 797 * A PG_BUSY page is returned. 798 */ 799 return (m); 800 } 801 802 /* 803 * Block until free pages are available for allocation, called in various 804 * places before memory allocations. 805 */ 806 void 807 vm_wait(void) 808 { 809 crit_enter(); 810 if (curthread == pagethread) { 811 vm_pageout_pages_needed = 1; 812 tsleep(&vm_pageout_pages_needed, 0, "VMWait", 0); 813 } else { 814 if (!vm_pages_needed) { 815 vm_pages_needed = 1; 816 wakeup(&vm_pages_needed); 817 } 818 tsleep(&vmstats.v_free_count, 0, "vmwait", 0); 819 } 820 crit_exit(); 821 } 822 823 /* 824 * Block until free pages are available for allocation 825 * 826 * Called only in vm_fault so that processes page faulting can be 827 * easily tracked. 828 * 829 * Sleeps at a lower priority than vm_wait() so that vm_wait()ing 830 * processes will be able to grab memory first. Do not change 831 * this balance without careful testing first. 832 */ 833 void 834 vm_waitpfault(void) 835 { 836 crit_enter(); 837 if (!vm_pages_needed) { 838 vm_pages_needed = 1; 839 wakeup(&vm_pages_needed); 840 } 841 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 842 crit_exit(); 843 } 844 845 /* 846 * Put the specified page on the active list (if appropriate). Ensure 847 * that act_count is at least ACT_INIT but do not otherwise mess with it. 848 * 849 * The page queues must be locked. 850 * This routine may not block. 851 */ 852 void 853 vm_page_activate(vm_page_t m) 854 { 855 crit_enter(); 856 if (m->queue != PQ_ACTIVE) { 857 if ((m->queue - m->pc) == PQ_CACHE) 858 mycpu->gd_cnt.v_reactivated++; 859 860 vm_page_unqueue(m); 861 862 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 863 m->queue = PQ_ACTIVE; 864 vm_page_queues[PQ_ACTIVE].lcnt++; 865 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 866 m, pageq); 867 if (m->act_count < ACT_INIT) 868 m->act_count = ACT_INIT; 869 vmstats.v_active_count++; 870 } 871 } else { 872 if (m->act_count < ACT_INIT) 873 m->act_count = ACT_INIT; 874 } 875 crit_exit(); 876 } 877 878 /* 879 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 880 * routine is called when a page has been added to the cache or free 881 * queues. 882 * 883 * This routine may not block. 884 * This routine must be called at splvm() 885 */ 886 static __inline void 887 vm_page_free_wakeup(void) 888 { 889 /* 890 * if pageout daemon needs pages, then tell it that there are 891 * some free. 892 */ 893 if (vm_pageout_pages_needed && 894 vmstats.v_cache_count + vmstats.v_free_count >= 895 vmstats.v_pageout_free_min 896 ) { 897 wakeup(&vm_pageout_pages_needed); 898 vm_pageout_pages_needed = 0; 899 } 900 901 /* 902 * wakeup processes that are waiting on memory if we hit a 903 * high water mark. And wakeup scheduler process if we have 904 * lots of memory. this process will swapin processes. 905 */ 906 if (vm_pages_needed && !vm_page_count_min()) { 907 vm_pages_needed = 0; 908 wakeup(&vmstats.v_free_count); 909 } 910 } 911 912 /* 913 * vm_page_free_toq: 914 * 915 * Returns the given page to the PQ_FREE list, disassociating it with 916 * any VM object. 917 * 918 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 919 * return (the page will have been freed). No particular spl is required 920 * on entry. 921 * 922 * This routine may not block. 923 */ 924 void 925 vm_page_free_toq(vm_page_t m) 926 { 927 struct vpgqueues *pq; 928 929 crit_enter(); 930 mycpu->gd_cnt.v_tfree++; 931 932 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 933 kprintf( 934 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 935 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 936 m->hold_count); 937 if ((m->queue - m->pc) == PQ_FREE) 938 panic("vm_page_free: freeing free page"); 939 else 940 panic("vm_page_free: freeing busy page"); 941 } 942 943 /* 944 * unqueue, then remove page. Note that we cannot destroy 945 * the page here because we do not want to call the pager's 946 * callback routine until after we've put the page on the 947 * appropriate free queue. 948 */ 949 vm_page_unqueue_nowakeup(m); 950 vm_page_remove(m); 951 952 /* 953 * No further management of fictitious pages occurs beyond object 954 * and queue removal. 955 */ 956 if ((m->flags & PG_FICTITIOUS) != 0) { 957 vm_page_wakeup(m); 958 crit_exit(); 959 return; 960 } 961 962 m->valid = 0; 963 vm_page_undirty(m); 964 965 if (m->wire_count != 0) { 966 if (m->wire_count > 1) { 967 panic( 968 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 969 m->wire_count, (long)m->pindex); 970 } 971 panic("vm_page_free: freeing wired page"); 972 } 973 974 /* 975 * Clear the UNMANAGED flag when freeing an unmanaged page. 976 */ 977 if (m->flags & PG_UNMANAGED) { 978 m->flags &= ~PG_UNMANAGED; 979 } 980 981 if (m->hold_count != 0) { 982 m->flags &= ~PG_ZERO; 983 m->queue = PQ_HOLD; 984 } else { 985 m->queue = PQ_FREE + m->pc; 986 } 987 pq = &vm_page_queues[m->queue]; 988 pq->lcnt++; 989 ++(*pq->cnt); 990 991 /* 992 * Put zero'd pages on the end ( where we look for zero'd pages 993 * first ) and non-zerod pages at the head. 994 */ 995 if (m->flags & PG_ZERO) { 996 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 997 ++vm_page_zero_count; 998 } else { 999 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1000 } 1001 vm_page_wakeup(m); 1002 vm_page_free_wakeup(); 1003 crit_exit(); 1004 } 1005 1006 /* 1007 * vm_page_unmanage() 1008 * 1009 * Prevent PV management from being done on the page. The page is 1010 * removed from the paging queues as if it were wired, and as a 1011 * consequence of no longer being managed the pageout daemon will not 1012 * touch it (since there is no way to locate the pte mappings for the 1013 * page). madvise() calls that mess with the pmap will also no longer 1014 * operate on the page. 1015 * 1016 * Beyond that the page is still reasonably 'normal'. Freeing the page 1017 * will clear the flag. 1018 * 1019 * This routine is used by OBJT_PHYS objects - objects using unswappable 1020 * physical memory as backing store rather then swap-backed memory and 1021 * will eventually be extended to support 4MB unmanaged physical 1022 * mappings. 1023 * 1024 * Must be called with a critical section held. 1025 */ 1026 void 1027 vm_page_unmanage(vm_page_t m) 1028 { 1029 ASSERT_IN_CRIT_SECTION(); 1030 if ((m->flags & PG_UNMANAGED) == 0) { 1031 if (m->wire_count == 0) 1032 vm_page_unqueue(m); 1033 } 1034 vm_page_flag_set(m, PG_UNMANAGED); 1035 } 1036 1037 /* 1038 * Mark this page as wired down by yet another map, removing it from 1039 * paging queues as necessary. 1040 * 1041 * The page queues must be locked. 1042 * This routine may not block. 1043 */ 1044 void 1045 vm_page_wire(vm_page_t m) 1046 { 1047 /* 1048 * Only bump the wire statistics if the page is not already wired, 1049 * and only unqueue the page if it is on some queue (if it is unmanaged 1050 * it is already off the queues). Don't do anything with fictitious 1051 * pages because they are always wired. 1052 */ 1053 crit_enter(); 1054 if ((m->flags & PG_FICTITIOUS) == 0) { 1055 if (m->wire_count == 0) { 1056 if ((m->flags & PG_UNMANAGED) == 0) 1057 vm_page_unqueue(m); 1058 vmstats.v_wire_count++; 1059 } 1060 m->wire_count++; 1061 KASSERT(m->wire_count != 0, 1062 ("vm_page_wire: wire_count overflow m=%p", m)); 1063 } 1064 vm_page_flag_set(m, PG_MAPPED); 1065 crit_exit(); 1066 } 1067 1068 /* 1069 * Release one wiring of this page, potentially enabling it to be paged again. 1070 * 1071 * Many pages placed on the inactive queue should actually go 1072 * into the cache, but it is difficult to figure out which. What 1073 * we do instead, if the inactive target is well met, is to put 1074 * clean pages at the head of the inactive queue instead of the tail. 1075 * This will cause them to be moved to the cache more quickly and 1076 * if not actively re-referenced, freed more quickly. If we just 1077 * stick these pages at the end of the inactive queue, heavy filesystem 1078 * meta-data accesses can cause an unnecessary paging load on memory bound 1079 * processes. This optimization causes one-time-use metadata to be 1080 * reused more quickly. 1081 * 1082 * BUT, if we are in a low-memory situation we have no choice but to 1083 * put clean pages on the cache queue. 1084 * 1085 * A number of routines use vm_page_unwire() to guarantee that the page 1086 * will go into either the inactive or active queues, and will NEVER 1087 * be placed in the cache - for example, just after dirtying a page. 1088 * dirty pages in the cache are not allowed. 1089 * 1090 * The page queues must be locked. 1091 * This routine may not block. 1092 */ 1093 void 1094 vm_page_unwire(vm_page_t m, int activate) 1095 { 1096 crit_enter(); 1097 if (m->flags & PG_FICTITIOUS) { 1098 /* do nothing */ 1099 } else if (m->wire_count <= 0) { 1100 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1101 } else { 1102 if (--m->wire_count == 0) { 1103 --vmstats.v_wire_count; 1104 if (m->flags & PG_UNMANAGED) { 1105 ; 1106 } else if (activate) { 1107 TAILQ_INSERT_TAIL( 1108 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1109 m->queue = PQ_ACTIVE; 1110 vm_page_queues[PQ_ACTIVE].lcnt++; 1111 vmstats.v_active_count++; 1112 } else { 1113 vm_page_flag_clear(m, PG_WINATCFLS); 1114 TAILQ_INSERT_TAIL( 1115 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1116 m->queue = PQ_INACTIVE; 1117 vm_page_queues[PQ_INACTIVE].lcnt++; 1118 vmstats.v_inactive_count++; 1119 } 1120 } 1121 } 1122 crit_exit(); 1123 } 1124 1125 1126 /* 1127 * Move the specified page to the inactive queue. If the page has 1128 * any associated swap, the swap is deallocated. 1129 * 1130 * Normally athead is 0 resulting in LRU operation. athead is set 1131 * to 1 if we want this page to be 'as if it were placed in the cache', 1132 * except without unmapping it from the process address space. 1133 * 1134 * This routine may not block. 1135 */ 1136 static __inline void 1137 _vm_page_deactivate(vm_page_t m, int athead) 1138 { 1139 /* 1140 * Ignore if already inactive. 1141 */ 1142 if (m->queue == PQ_INACTIVE) 1143 return; 1144 1145 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1146 if ((m->queue - m->pc) == PQ_CACHE) 1147 mycpu->gd_cnt.v_reactivated++; 1148 vm_page_flag_clear(m, PG_WINATCFLS); 1149 vm_page_unqueue(m); 1150 if (athead) 1151 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1152 else 1153 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1154 m->queue = PQ_INACTIVE; 1155 vm_page_queues[PQ_INACTIVE].lcnt++; 1156 vmstats.v_inactive_count++; 1157 } 1158 } 1159 1160 void 1161 vm_page_deactivate(vm_page_t m) 1162 { 1163 crit_enter(); 1164 _vm_page_deactivate(m, 0); 1165 crit_exit(); 1166 } 1167 1168 /* 1169 * vm_page_try_to_cache: 1170 * 1171 * Returns 0 on failure, 1 on success 1172 */ 1173 int 1174 vm_page_try_to_cache(vm_page_t m) 1175 { 1176 crit_enter(); 1177 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1178 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1179 crit_exit(); 1180 return(0); 1181 } 1182 vm_page_test_dirty(m); 1183 if (m->dirty) { 1184 crit_exit(); 1185 return(0); 1186 } 1187 vm_page_cache(m); 1188 crit_exit(); 1189 return(1); 1190 } 1191 1192 /* 1193 * Attempt to free the page. If we cannot free it, we do nothing. 1194 * 1 is returned on success, 0 on failure. 1195 */ 1196 int 1197 vm_page_try_to_free(vm_page_t m) 1198 { 1199 crit_enter(); 1200 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1201 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1202 crit_exit(); 1203 return(0); 1204 } 1205 vm_page_test_dirty(m); 1206 if (m->dirty) { 1207 crit_exit(); 1208 return(0); 1209 } 1210 vm_page_busy(m); 1211 vm_page_protect(m, VM_PROT_NONE); 1212 vm_page_free(m); 1213 crit_exit(); 1214 return(1); 1215 } 1216 1217 /* 1218 * vm_page_cache 1219 * 1220 * Put the specified page onto the page cache queue (if appropriate). 1221 * 1222 * This routine may not block. 1223 */ 1224 void 1225 vm_page_cache(vm_page_t m) 1226 { 1227 ASSERT_IN_CRIT_SECTION(); 1228 1229 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1230 m->wire_count || m->hold_count) { 1231 kprintf("vm_page_cache: attempting to cache busy/held page\n"); 1232 return; 1233 } 1234 1235 /* 1236 * Already in the cache (and thus not mapped) 1237 */ 1238 if ((m->queue - m->pc) == PQ_CACHE) 1239 return; 1240 1241 /* 1242 * Caller is required to test m->dirty, but note that the act of 1243 * removing the page from its maps can cause it to become dirty 1244 * on an SMP system due to another cpu running in usermode. 1245 */ 1246 if (m->dirty) { 1247 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1248 (long)m->pindex); 1249 } 1250 1251 /* 1252 * Remove all pmaps and indicate that the page is not 1253 * writeable or mapped. Deal with the case where the page 1254 * may have become dirty via a race. 1255 */ 1256 vm_page_protect(m, VM_PROT_NONE); 1257 if (m->dirty) { 1258 vm_page_deactivate(m); 1259 } else { 1260 vm_page_unqueue_nowakeup(m); 1261 m->queue = PQ_CACHE + m->pc; 1262 vm_page_queues[m->queue].lcnt++; 1263 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1264 vmstats.v_cache_count++; 1265 vm_page_free_wakeup(); 1266 } 1267 } 1268 1269 /* 1270 * vm_page_dontneed() 1271 * 1272 * Cache, deactivate, or do nothing as appropriate. This routine 1273 * is typically used by madvise() MADV_DONTNEED. 1274 * 1275 * Generally speaking we want to move the page into the cache so 1276 * it gets reused quickly. However, this can result in a silly syndrome 1277 * due to the page recycling too quickly. Small objects will not be 1278 * fully cached. On the otherhand, if we move the page to the inactive 1279 * queue we wind up with a problem whereby very large objects 1280 * unnecessarily blow away our inactive and cache queues. 1281 * 1282 * The solution is to move the pages based on a fixed weighting. We 1283 * either leave them alone, deactivate them, or move them to the cache, 1284 * where moving them to the cache has the highest weighting. 1285 * By forcing some pages into other queues we eventually force the 1286 * system to balance the queues, potentially recovering other unrelated 1287 * space from active. The idea is to not force this to happen too 1288 * often. 1289 */ 1290 void 1291 vm_page_dontneed(vm_page_t m) 1292 { 1293 static int dnweight; 1294 int dnw; 1295 int head; 1296 1297 dnw = ++dnweight; 1298 1299 /* 1300 * occassionally leave the page alone 1301 */ 1302 crit_enter(); 1303 if ((dnw & 0x01F0) == 0 || 1304 m->queue == PQ_INACTIVE || 1305 m->queue - m->pc == PQ_CACHE 1306 ) { 1307 if (m->act_count >= ACT_INIT) 1308 --m->act_count; 1309 crit_exit(); 1310 return; 1311 } 1312 1313 if (m->dirty == 0) 1314 vm_page_test_dirty(m); 1315 1316 if (m->dirty || (dnw & 0x0070) == 0) { 1317 /* 1318 * Deactivate the page 3 times out of 32. 1319 */ 1320 head = 0; 1321 } else { 1322 /* 1323 * Cache the page 28 times out of every 32. Note that 1324 * the page is deactivated instead of cached, but placed 1325 * at the head of the queue instead of the tail. 1326 */ 1327 head = 1; 1328 } 1329 _vm_page_deactivate(m, head); 1330 crit_exit(); 1331 } 1332 1333 /* 1334 * Grab a page, blocking if it is busy and allocating a page if necessary. 1335 * A busy page is returned or NULL. 1336 * 1337 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1338 * If VM_ALLOC_RETRY is not specified 1339 * 1340 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1341 * always returned if we had blocked. 1342 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1343 * This routine may not be called from an interrupt. 1344 * The returned page may not be entirely valid. 1345 * 1346 * This routine may be called from mainline code without spl protection and 1347 * be guarenteed a busied page associated with the object at the specified 1348 * index. 1349 */ 1350 vm_page_t 1351 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1352 { 1353 vm_page_t m; 1354 int generation; 1355 1356 KKASSERT(allocflags & 1357 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1358 crit_enter(); 1359 retrylookup: 1360 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1361 if (m->busy || (m->flags & PG_BUSY)) { 1362 generation = object->generation; 1363 1364 while ((object->generation == generation) && 1365 (m->busy || (m->flags & PG_BUSY))) { 1366 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1367 tsleep(m, 0, "pgrbwt", 0); 1368 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1369 m = NULL; 1370 goto done; 1371 } 1372 } 1373 goto retrylookup; 1374 } else { 1375 vm_page_busy(m); 1376 goto done; 1377 } 1378 } 1379 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1380 if (m == NULL) { 1381 vm_wait(); 1382 if ((allocflags & VM_ALLOC_RETRY) == 0) 1383 goto done; 1384 goto retrylookup; 1385 } 1386 done: 1387 crit_exit(); 1388 return(m); 1389 } 1390 1391 /* 1392 * Mapping function for valid bits or for dirty bits in 1393 * a page. May not block. 1394 * 1395 * Inputs are required to range within a page. 1396 */ 1397 __inline int 1398 vm_page_bits(int base, int size) 1399 { 1400 int first_bit; 1401 int last_bit; 1402 1403 KASSERT( 1404 base + size <= PAGE_SIZE, 1405 ("vm_page_bits: illegal base/size %d/%d", base, size) 1406 ); 1407 1408 if (size == 0) /* handle degenerate case */ 1409 return(0); 1410 1411 first_bit = base >> DEV_BSHIFT; 1412 last_bit = (base + size - 1) >> DEV_BSHIFT; 1413 1414 return ((2 << last_bit) - (1 << first_bit)); 1415 } 1416 1417 /* 1418 * Sets portions of a page valid and clean. The arguments are expected 1419 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1420 * of any partial chunks touched by the range. The invalid portion of 1421 * such chunks will be zero'd. 1422 * 1423 * This routine may not block. 1424 * 1425 * (base + size) must be less then or equal to PAGE_SIZE. 1426 */ 1427 void 1428 vm_page_set_validclean(vm_page_t m, int base, int size) 1429 { 1430 int pagebits; 1431 int frag; 1432 int endoff; 1433 1434 if (size == 0) /* handle degenerate case */ 1435 return; 1436 1437 /* 1438 * If the base is not DEV_BSIZE aligned and the valid 1439 * bit is clear, we have to zero out a portion of the 1440 * first block. 1441 */ 1442 1443 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1444 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1445 ) { 1446 pmap_zero_page_area( 1447 VM_PAGE_TO_PHYS(m), 1448 frag, 1449 base - frag 1450 ); 1451 } 1452 1453 /* 1454 * If the ending offset is not DEV_BSIZE aligned and the 1455 * valid bit is clear, we have to zero out a portion of 1456 * the last block. 1457 */ 1458 1459 endoff = base + size; 1460 1461 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1462 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1463 ) { 1464 pmap_zero_page_area( 1465 VM_PAGE_TO_PHYS(m), 1466 endoff, 1467 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1468 ); 1469 } 1470 1471 /* 1472 * Set valid, clear dirty bits. If validating the entire 1473 * page we can safely clear the pmap modify bit. We also 1474 * use this opportunity to clear the PG_NOSYNC flag. If a process 1475 * takes a write fault on a MAP_NOSYNC memory area the flag will 1476 * be set again. 1477 * 1478 * We set valid bits inclusive of any overlap, but we can only 1479 * clear dirty bits for DEV_BSIZE chunks that are fully within 1480 * the range. 1481 */ 1482 1483 pagebits = vm_page_bits(base, size); 1484 m->valid |= pagebits; 1485 #if 0 /* NOT YET */ 1486 if ((frag = base & (DEV_BSIZE - 1)) != 0) { 1487 frag = DEV_BSIZE - frag; 1488 base += frag; 1489 size -= frag; 1490 if (size < 0) 1491 size = 0; 1492 } 1493 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); 1494 #endif 1495 m->dirty &= ~pagebits; 1496 if (base == 0 && size == PAGE_SIZE) { 1497 pmap_clear_modify(m); 1498 vm_page_flag_clear(m, PG_NOSYNC); 1499 } 1500 } 1501 1502 void 1503 vm_page_clear_dirty(vm_page_t m, int base, int size) 1504 { 1505 m->dirty &= ~vm_page_bits(base, size); 1506 } 1507 1508 /* 1509 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1510 * valid and dirty bits for the effected areas are cleared. 1511 * 1512 * May not block. 1513 */ 1514 void 1515 vm_page_set_invalid(vm_page_t m, int base, int size) 1516 { 1517 int bits; 1518 1519 bits = vm_page_bits(base, size); 1520 m->valid &= ~bits; 1521 m->dirty &= ~bits; 1522 m->object->generation++; 1523 } 1524 1525 /* 1526 * The kernel assumes that the invalid portions of a page contain 1527 * garbage, but such pages can be mapped into memory by user code. 1528 * When this occurs, we must zero out the non-valid portions of the 1529 * page so user code sees what it expects. 1530 * 1531 * Pages are most often semi-valid when the end of a file is mapped 1532 * into memory and the file's size is not page aligned. 1533 */ 1534 void 1535 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1536 { 1537 int b; 1538 int i; 1539 1540 /* 1541 * Scan the valid bits looking for invalid sections that 1542 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1543 * valid bit may be set ) have already been zerod by 1544 * vm_page_set_validclean(). 1545 */ 1546 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1547 if (i == (PAGE_SIZE / DEV_BSIZE) || 1548 (m->valid & (1 << i)) 1549 ) { 1550 if (i > b) { 1551 pmap_zero_page_area( 1552 VM_PAGE_TO_PHYS(m), 1553 b << DEV_BSHIFT, 1554 (i - b) << DEV_BSHIFT 1555 ); 1556 } 1557 b = i + 1; 1558 } 1559 } 1560 1561 /* 1562 * setvalid is TRUE when we can safely set the zero'd areas 1563 * as being valid. We can do this if there are no cache consistency 1564 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1565 */ 1566 if (setvalid) 1567 m->valid = VM_PAGE_BITS_ALL; 1568 } 1569 1570 /* 1571 * Is a (partial) page valid? Note that the case where size == 0 1572 * will return FALSE in the degenerate case where the page is entirely 1573 * invalid, and TRUE otherwise. 1574 * 1575 * May not block. 1576 */ 1577 int 1578 vm_page_is_valid(vm_page_t m, int base, int size) 1579 { 1580 int bits = vm_page_bits(base, size); 1581 1582 if (m->valid && ((m->valid & bits) == bits)) 1583 return 1; 1584 else 1585 return 0; 1586 } 1587 1588 /* 1589 * update dirty bits from pmap/mmu. May not block. 1590 */ 1591 void 1592 vm_page_test_dirty(vm_page_t m) 1593 { 1594 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1595 vm_page_dirty(m); 1596 } 1597 } 1598 1599 #include "opt_ddb.h" 1600 #ifdef DDB 1601 #include <sys/kernel.h> 1602 1603 #include <ddb/ddb.h> 1604 1605 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1606 { 1607 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1608 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1609 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1610 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1611 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1612 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1613 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1614 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1615 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1616 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1617 } 1618 1619 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1620 { 1621 int i; 1622 db_printf("PQ_FREE:"); 1623 for(i=0;i<PQ_L2_SIZE;i++) { 1624 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1625 } 1626 db_printf("\n"); 1627 1628 db_printf("PQ_CACHE:"); 1629 for(i=0;i<PQ_L2_SIZE;i++) { 1630 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1631 } 1632 db_printf("\n"); 1633 1634 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1635 vm_page_queues[PQ_ACTIVE].lcnt, 1636 vm_page_queues[PQ_INACTIVE].lcnt); 1637 } 1638 #endif /* DDB */ 1639