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 1.40 2008/08/25 17:01:42 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 #include <vm/swap_pager.h> 92 93 #include <machine/md_var.h> 94 95 static void vm_page_queue_init(void); 96 static void vm_page_free_wakeup(void); 97 static vm_page_t vm_page_select_cache(vm_object_t, vm_pindex_t); 98 static vm_page_t _vm_page_list_find2(int basequeue, int index); 99 100 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 101 102 #define ASSERT_IN_CRIT_SECTION() KKASSERT(crit_test(curthread)); 103 104 RB_GENERATE2(vm_page_rb_tree, vm_page, rb_entry, rb_vm_page_compare, 105 vm_pindex_t, pindex); 106 107 static void 108 vm_page_queue_init(void) 109 { 110 int i; 111 112 for (i = 0; i < PQ_L2_SIZE; i++) 113 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 114 for (i = 0; i < PQ_L2_SIZE; i++) 115 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 116 117 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 118 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 119 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 120 /* PQ_NONE has no queue */ 121 122 for (i = 0; i < PQ_COUNT; i++) 123 TAILQ_INIT(&vm_page_queues[i].pl); 124 } 125 126 /* 127 * note: place in initialized data section? Is this necessary? 128 */ 129 long first_page = 0; 130 int vm_page_array_size = 0; 131 int vm_page_zero_count = 0; 132 vm_page_t vm_page_array = 0; 133 134 /* 135 * (low level boot) 136 * 137 * Sets the page size, perhaps based upon the memory size. 138 * Must be called before any use of page-size dependent functions. 139 */ 140 void 141 vm_set_page_size(void) 142 { 143 if (vmstats.v_page_size == 0) 144 vmstats.v_page_size = PAGE_SIZE; 145 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 146 panic("vm_set_page_size: page size not a power of two"); 147 } 148 149 /* 150 * (low level boot) 151 * 152 * Add a new page to the freelist for use by the system. New pages 153 * are added to both the head and tail of the associated free page 154 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 155 * requests pull 'recent' adds (higher physical addresses) first. 156 * 157 * Must be called in a critical section. 158 */ 159 vm_page_t 160 vm_add_new_page(vm_paddr_t pa) 161 { 162 struct vpgqueues *vpq; 163 vm_page_t m; 164 165 ++vmstats.v_page_count; 166 ++vmstats.v_free_count; 167 m = PHYS_TO_VM_PAGE(pa); 168 m->phys_addr = pa; 169 m->flags = 0; 170 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 171 m->queue = m->pc + PQ_FREE; 172 KKASSERT(m->dirty == 0); 173 174 vpq = &vm_page_queues[m->queue]; 175 if (vpq->flipflop) 176 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 177 else 178 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 179 vpq->flipflop = 1 - vpq->flipflop; 180 181 vm_page_queues[m->queue].lcnt++; 182 return (m); 183 } 184 185 /* 186 * (low level boot) 187 * 188 * Initializes the resident memory module. 189 * 190 * Allocates memory for the page cells, and for the object/offset-to-page 191 * hash table headers. Each page cell is initialized and placed on the 192 * free list. 193 * 194 * starta/enda represents the range of physical memory addresses available 195 * for use (skipping memory already used by the kernel), subject to 196 * phys_avail[]. Note that phys_avail[] has already mapped out memory 197 * already in use by the kernel. 198 */ 199 vm_offset_t 200 vm_page_startup(vm_offset_t vaddr) 201 { 202 vm_offset_t mapped; 203 vm_size_t npages; 204 vm_paddr_t page_range; 205 vm_paddr_t new_end; 206 int i; 207 vm_paddr_t pa; 208 int nblocks; 209 vm_paddr_t last_pa; 210 vm_paddr_t end; 211 vm_paddr_t biggestone, biggestsize; 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_page64(phys_avail[i]); 222 phys_avail[i + 1] = trunc_page64(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 end = trunc_page(end); 238 239 /* 240 * Initialize the queue headers for the free queue, the active queue 241 * and the inactive queue. 242 */ 243 244 vm_page_queue_init(); 245 246 /* VKERNELs don't support minidumps and as such don't need vm_page_dump */ 247 #if !defined(_KERNEL_VIRTUAL) 248 /* 249 * Allocate a bitmap to indicate that a random physical page 250 * needs to be included in a minidump. 251 * 252 * The amd64 port needs this to indicate which direct map pages 253 * need to be dumped, via calls to dump_add_page()/dump_drop_page(). 254 * 255 * However, i386 still needs this workspace internally within the 256 * minidump code. In theory, they are not needed on i386, but are 257 * included should the sf_buf code decide to use them. 258 */ 259 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE; 260 vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY); 261 end -= vm_page_dump_size; 262 vm_page_dump = (void *)pmap_map(&vaddr, end, end + vm_page_dump_size, 263 VM_PROT_READ | VM_PROT_WRITE); 264 bzero((void *)vm_page_dump, vm_page_dump_size); 265 #endif 266 267 /* 268 * Compute the number of pages of memory that will be available for 269 * use (taking into account the overhead of a page structure per 270 * page). 271 */ 272 first_page = phys_avail[0] / PAGE_SIZE; 273 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 274 npages = (total - (page_range * sizeof(struct vm_page))) / PAGE_SIZE; 275 276 /* 277 * Initialize the mem entry structures now, and put them in the free 278 * queue. 279 */ 280 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 281 mapped = pmap_map(&vaddr, new_end, end, 282 VM_PROT_READ | VM_PROT_WRITE); 283 vm_page_array = (vm_page_t)mapped; 284 285 #ifdef __x86_64__ 286 /* 287 * since pmap_map on amd64 returns stuff out of a direct-map region, 288 * we have to manually add these pages to the minidump tracking so 289 * that they can be dumped, including the vm_page_array. 290 */ 291 for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE) 292 dump_add_page(pa); 293 #endif 294 295 /* 296 * Clear all of the page structures 297 */ 298 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 299 vm_page_array_size = page_range; 300 301 /* 302 * Construct the free queue(s) in ascending order (by physical 303 * address) so that the first 16MB of physical memory is allocated 304 * last rather than first. On large-memory machines, this avoids 305 * the exhaustion of low physical memory before isa_dmainit has run. 306 */ 307 vmstats.v_page_count = 0; 308 vmstats.v_free_count = 0; 309 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 310 pa = phys_avail[i]; 311 if (i == biggestone) 312 last_pa = new_end; 313 else 314 last_pa = phys_avail[i + 1]; 315 while (pa < last_pa && npages-- > 0) { 316 vm_add_new_page(pa); 317 pa += PAGE_SIZE; 318 } 319 } 320 return (vaddr); 321 } 322 323 /* 324 * Scan comparison function for Red-Black tree scans. An inclusive 325 * (start,end) is expected. Other fields are not used. 326 */ 327 int 328 rb_vm_page_scancmp(struct vm_page *p, void *data) 329 { 330 struct rb_vm_page_scan_info *info = data; 331 332 if (p->pindex < info->start_pindex) 333 return(-1); 334 if (p->pindex > info->end_pindex) 335 return(1); 336 return(0); 337 } 338 339 int 340 rb_vm_page_compare(struct vm_page *p1, struct vm_page *p2) 341 { 342 if (p1->pindex < p2->pindex) 343 return(-1); 344 if (p1->pindex > p2->pindex) 345 return(1); 346 return(0); 347 } 348 349 /* 350 * The opposite of vm_page_hold(). A page can be freed while being held, 351 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 352 * in this case to actually free it once the hold count drops to 0. 353 * 354 * This routine must be called at splvm(). 355 */ 356 void 357 vm_page_unhold(vm_page_t mem) 358 { 359 --mem->hold_count; 360 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 361 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) { 362 vm_page_busy(mem); 363 vm_page_free_toq(mem); 364 } 365 } 366 367 /* 368 * Inserts the given mem entry into the object and object list. 369 * 370 * The pagetables are not updated but will presumably fault the page 371 * in if necessary, or if a kernel page the caller will at some point 372 * enter the page into the kernel's pmap. We are not allowed to block 373 * here so we *can't* do this anyway. 374 * 375 * This routine may not block. 376 * This routine must be called with a critical section held. 377 */ 378 void 379 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 380 { 381 ASSERT_IN_CRIT_SECTION(); 382 if (m->object != NULL) 383 panic("vm_page_insert: already inserted"); 384 385 /* 386 * Record the object/offset pair in this page 387 */ 388 m->object = object; 389 m->pindex = pindex; 390 391 /* 392 * Insert it into the object. 393 */ 394 vm_page_rb_tree_RB_INSERT(&object->rb_memq, m); 395 object->generation++; 396 397 /* 398 * show that the object has one more resident page. 399 */ 400 object->resident_page_count++; 401 402 /* 403 * Since we are inserting a new and possibly dirty page, 404 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 405 */ 406 if ((m->valid & m->dirty) || (m->flags & PG_WRITEABLE)) 407 vm_object_set_writeable_dirty(object); 408 409 /* 410 * Checks for a swap assignment and sets PG_SWAPPED if appropriate. 411 */ 412 swap_pager_page_inserted(m); 413 } 414 415 /* 416 * Removes the given vm_page_t from the global (object,index) hash table 417 * and from the object's memq. 418 * 419 * The underlying pmap entry (if any) is NOT removed here. 420 * This routine may not block. 421 * 422 * The page must be BUSY and will remain BUSY on return. No spl needs to be 423 * held on call to this routine. 424 * 425 * note: FreeBSD side effect was to unbusy the page on return. We leave 426 * it busy. 427 */ 428 void 429 vm_page_remove(vm_page_t m) 430 { 431 vm_object_t object; 432 433 crit_enter(); 434 if (m->object == NULL) { 435 crit_exit(); 436 return; 437 } 438 439 if ((m->flags & PG_BUSY) == 0) 440 panic("vm_page_remove: page not busy"); 441 442 object = m->object; 443 444 /* 445 * Remove the page from the object and update the object. 446 */ 447 vm_page_rb_tree_RB_REMOVE(&object->rb_memq, m); 448 object->resident_page_count--; 449 object->generation++; 450 m->object = NULL; 451 452 crit_exit(); 453 } 454 455 /* 456 * Locate and return the page at (object, pindex), or NULL if the 457 * page could not be found. 458 * 459 * This routine will operate properly without spl protection, but 460 * the returned page could be in flux if it is busy. Because an 461 * interrupt can race a caller's busy check (unbusying and freeing the 462 * page we return before the caller is able to check the busy bit), 463 * the caller should generally call this routine with a critical 464 * section held. 465 * 466 * Callers may call this routine without spl protection if they know 467 * 'for sure' that the page will not be ripped out from under them 468 * by an interrupt. 469 */ 470 vm_page_t 471 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 472 { 473 vm_page_t m; 474 475 /* 476 * Search the hash table for this object/offset pair 477 */ 478 crit_enter(); 479 m = vm_page_rb_tree_RB_LOOKUP(&object->rb_memq, pindex); 480 crit_exit(); 481 KKASSERT(m == NULL || (m->object == object && m->pindex == pindex)); 482 return(m); 483 } 484 485 /* 486 * vm_page_rename() 487 * 488 * Move the given memory entry from its current object to the specified 489 * target object/offset. 490 * 491 * The object must be locked. 492 * This routine may not block. 493 * 494 * Note: This routine will raise itself to splvm(), the caller need not. 495 * 496 * Note: Swap associated with the page must be invalidated by the move. We 497 * have to do this for several reasons: (1) we aren't freeing the 498 * page, (2) we are dirtying the page, (3) the VM system is probably 499 * moving the page from object A to B, and will then later move 500 * the backing store from A to B and we can't have a conflict. 501 * 502 * Note: We *always* dirty the page. It is necessary both for the 503 * fact that we moved it, and because we may be invalidating 504 * swap. If the page is on the cache, we have to deactivate it 505 * or vm_page_dirty() will panic. Dirty pages are not allowed 506 * on the cache. 507 */ 508 void 509 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 510 { 511 crit_enter(); 512 vm_page_remove(m); 513 vm_page_insert(m, new_object, new_pindex); 514 if (m->queue - m->pc == PQ_CACHE) 515 vm_page_deactivate(m); 516 vm_page_dirty(m); 517 vm_page_wakeup(m); 518 crit_exit(); 519 } 520 521 /* 522 * vm_page_unqueue() without any wakeup. This routine is used when a page 523 * is being moved between queues or otherwise is to remain BUSYied by the 524 * caller. 525 * 526 * This routine must be called at splhigh(). 527 * This routine may not block. 528 */ 529 void 530 vm_page_unqueue_nowakeup(vm_page_t m) 531 { 532 int queue = m->queue; 533 struct vpgqueues *pq; 534 535 if (queue != PQ_NONE) { 536 pq = &vm_page_queues[queue]; 537 m->queue = PQ_NONE; 538 TAILQ_REMOVE(&pq->pl, m, pageq); 539 (*pq->cnt)--; 540 pq->lcnt--; 541 } 542 } 543 544 /* 545 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 546 * if necessary. 547 * 548 * This routine must be called at splhigh(). 549 * This routine may not block. 550 */ 551 void 552 vm_page_unqueue(vm_page_t m) 553 { 554 int queue = m->queue; 555 struct vpgqueues *pq; 556 557 if (queue != PQ_NONE) { 558 m->queue = PQ_NONE; 559 pq = &vm_page_queues[queue]; 560 TAILQ_REMOVE(&pq->pl, m, pageq); 561 (*pq->cnt)--; 562 pq->lcnt--; 563 if ((queue - m->pc) == PQ_CACHE || (queue - m->pc) == PQ_FREE) 564 pagedaemon_wakeup(); 565 } 566 } 567 568 /* 569 * vm_page_list_find() 570 * 571 * Find a page on the specified queue with color optimization. 572 * 573 * The page coloring optimization attempts to locate a page that does 574 * not overload other nearby pages in the object in the cpu's L1 or L2 575 * caches. We need this optimization because cpu caches tend to be 576 * physical caches, while object spaces tend to be virtual. 577 * 578 * This routine must be called at splvm(). 579 * This routine may not block. 580 * 581 * Note that this routine is carefully inlined. A non-inlined version 582 * is available for outside callers but the only critical path is 583 * from within this source file. 584 */ 585 static __inline 586 vm_page_t 587 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 588 { 589 vm_page_t m; 590 591 if (prefer_zero) 592 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 593 else 594 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 595 if (m == NULL) 596 m = _vm_page_list_find2(basequeue, index); 597 return(m); 598 } 599 600 static vm_page_t 601 _vm_page_list_find2(int basequeue, int index) 602 { 603 int i; 604 vm_page_t m = NULL; 605 struct vpgqueues *pq; 606 607 pq = &vm_page_queues[basequeue]; 608 609 /* 610 * Note that for the first loop, index+i and index-i wind up at the 611 * same place. Even though this is not totally optimal, we've already 612 * blown it by missing the cache case so we do not care. 613 */ 614 615 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 616 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 617 break; 618 619 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 620 break; 621 } 622 return(m); 623 } 624 625 vm_page_t 626 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 627 { 628 return(_vm_page_list_find(basequeue, index, prefer_zero)); 629 } 630 631 /* 632 * Find a page on the cache queue with color optimization. As pages 633 * might be found, but not applicable, they are deactivated. This 634 * keeps us from using potentially busy cached pages. 635 * 636 * This routine must be called with a critical section held. 637 * This routine may not block. 638 */ 639 vm_page_t 640 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 641 { 642 vm_page_t m; 643 644 while (TRUE) { 645 m = _vm_page_list_find( 646 PQ_CACHE, 647 (pindex + object->pg_color) & PQ_L2_MASK, 648 FALSE 649 ); 650 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 651 m->hold_count || m->wire_count)) { 652 vm_page_deactivate(m); 653 continue; 654 } 655 return m; 656 } 657 /* not reached */ 658 } 659 660 /* 661 * Find a free or zero page, with specified preference. We attempt to 662 * inline the nominal case and fall back to _vm_page_select_free() 663 * otherwise. 664 * 665 * This routine must be called with a critical section held. 666 * This routine may not block. 667 */ 668 static __inline vm_page_t 669 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 670 { 671 vm_page_t m; 672 673 m = _vm_page_list_find( 674 PQ_FREE, 675 (pindex + object->pg_color) & PQ_L2_MASK, 676 prefer_zero 677 ); 678 return(m); 679 } 680 681 /* 682 * vm_page_alloc() 683 * 684 * Allocate and return a memory cell associated with this VM object/offset 685 * pair. 686 * 687 * page_req classes: 688 * 689 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 690 * VM_ALLOC_QUICK like normal but cannot use cache 691 * VM_ALLOC_SYSTEM greater free drain 692 * VM_ALLOC_INTERRUPT allow free list to be completely drained 693 * VM_ALLOC_ZERO advisory request for pre-zero'd page 694 * 695 * The object must be locked. 696 * This routine may not block. 697 * The returned page will be marked PG_BUSY 698 * 699 * Additional special handling is required when called from an interrupt 700 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 701 * in this case. 702 */ 703 vm_page_t 704 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 705 { 706 vm_page_t m = NULL; 707 708 KKASSERT(object != NULL); 709 KASSERT(!vm_page_lookup(object, pindex), 710 ("vm_page_alloc: page already allocated")); 711 KKASSERT(page_req & 712 (VM_ALLOC_NORMAL|VM_ALLOC_QUICK| 713 VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 714 715 /* 716 * Certain system threads (pageout daemon, buf_daemon's) are 717 * allowed to eat deeper into the free page list. 718 */ 719 if (curthread->td_flags & TDF_SYSTHREAD) 720 page_req |= VM_ALLOC_SYSTEM; 721 722 crit_enter(); 723 loop: 724 if (vmstats.v_free_count > vmstats.v_free_reserved || 725 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 726 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 727 vmstats.v_free_count > vmstats.v_interrupt_free_min) 728 ) { 729 /* 730 * The free queue has sufficient free pages to take one out. 731 */ 732 if (page_req & VM_ALLOC_ZERO) 733 m = vm_page_select_free(object, pindex, TRUE); 734 else 735 m = vm_page_select_free(object, pindex, FALSE); 736 } else if (page_req & VM_ALLOC_NORMAL) { 737 /* 738 * Allocatable from the cache (non-interrupt only). On 739 * success, we must free the page and try again, thus 740 * ensuring that vmstats.v_*_free_min counters are replenished. 741 */ 742 #ifdef INVARIANTS 743 if (curthread->td_preempted) { 744 kprintf("vm_page_alloc(): warning, attempt to allocate" 745 " cache page from preempting interrupt\n"); 746 m = NULL; 747 } else { 748 m = vm_page_select_cache(object, pindex); 749 } 750 #else 751 m = vm_page_select_cache(object, pindex); 752 #endif 753 /* 754 * On success move the page into the free queue and loop. 755 */ 756 if (m != NULL) { 757 KASSERT(m->dirty == 0, 758 ("Found dirty cache page %p", m)); 759 vm_page_busy(m); 760 vm_page_protect(m, VM_PROT_NONE); 761 vm_page_free(m); 762 goto loop; 763 } 764 765 /* 766 * On failure return NULL 767 */ 768 crit_exit(); 769 #if defined(DIAGNOSTIC) 770 if (vmstats.v_cache_count > 0) 771 kprintf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 772 #endif 773 vm_pageout_deficit++; 774 pagedaemon_wakeup(); 775 return (NULL); 776 } else { 777 /* 778 * No pages available, wakeup the pageout daemon and give up. 779 */ 780 crit_exit(); 781 vm_pageout_deficit++; 782 pagedaemon_wakeup(); 783 return (NULL); 784 } 785 786 /* 787 * Good page found. The page has not yet been busied. We are in 788 * a critical section. 789 */ 790 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 791 KASSERT(m->dirty == 0, 792 ("vm_page_alloc: free/cache page %p was dirty", m)); 793 794 /* 795 * Remove from free queue 796 */ 797 vm_page_unqueue_nowakeup(m); 798 799 /* 800 * Initialize structure. Only the PG_ZERO flag is inherited. Set 801 * the page PG_BUSY 802 */ 803 if (m->flags & PG_ZERO) { 804 vm_page_zero_count--; 805 m->flags = PG_ZERO | PG_BUSY; 806 } else { 807 m->flags = PG_BUSY; 808 } 809 m->wire_count = 0; 810 m->hold_count = 0; 811 m->act_count = 0; 812 m->busy = 0; 813 m->valid = 0; 814 815 /* 816 * vm_page_insert() is safe prior to the crit_exit(). Note also that 817 * inserting a page here does not insert it into the pmap (which 818 * could cause us to block allocating memory). We cannot block 819 * anywhere. 820 */ 821 vm_page_insert(m, object, pindex); 822 823 /* 824 * Don't wakeup too often - wakeup the pageout daemon when 825 * we would be nearly out of memory. 826 */ 827 pagedaemon_wakeup(); 828 829 crit_exit(); 830 831 /* 832 * A PG_BUSY page is returned. 833 */ 834 return (m); 835 } 836 837 /* 838 * Block until free pages are available for allocation, called in various 839 * places before memory allocations. 840 */ 841 void 842 vm_wait(int timo) 843 { 844 crit_enter(); 845 if (curthread == pagethread) { 846 vm_pageout_pages_needed = 1; 847 tsleep(&vm_pageout_pages_needed, 0, "VMWait", timo); 848 } else { 849 if (vm_pages_needed == 0) { 850 vm_pages_needed = 1; 851 wakeup(&vm_pages_needed); 852 } 853 tsleep(&vmstats.v_free_count, 0, "vmwait", timo); 854 } 855 crit_exit(); 856 } 857 858 /* 859 * Block until free pages are available for allocation 860 * 861 * Called only in vm_fault so that processes page faulting can be 862 * easily tracked. 863 */ 864 void 865 vm_waitpfault(void) 866 { 867 crit_enter(); 868 if (vm_pages_needed == 0) { 869 vm_pages_needed = 1; 870 wakeup(&vm_pages_needed); 871 } 872 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 873 crit_exit(); 874 } 875 876 /* 877 * Put the specified page on the active list (if appropriate). Ensure 878 * that act_count is at least ACT_INIT but do not otherwise mess with it. 879 * 880 * The page queues must be locked. 881 * This routine may not block. 882 */ 883 void 884 vm_page_activate(vm_page_t m) 885 { 886 crit_enter(); 887 if (m->queue != PQ_ACTIVE) { 888 if ((m->queue - m->pc) == PQ_CACHE) 889 mycpu->gd_cnt.v_reactivated++; 890 891 vm_page_unqueue(m); 892 893 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 894 m->queue = PQ_ACTIVE; 895 vm_page_queues[PQ_ACTIVE].lcnt++; 896 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 897 m, pageq); 898 if (m->act_count < ACT_INIT) 899 m->act_count = ACT_INIT; 900 vmstats.v_active_count++; 901 } 902 } else { 903 if (m->act_count < ACT_INIT) 904 m->act_count = ACT_INIT; 905 } 906 crit_exit(); 907 } 908 909 /* 910 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 911 * routine is called when a page has been added to the cache or free 912 * queues. 913 * 914 * This routine may not block. 915 * This routine must be called at splvm() 916 */ 917 static __inline void 918 vm_page_free_wakeup(void) 919 { 920 /* 921 * if pageout daemon needs pages, then tell it that there are 922 * some free. 923 */ 924 if (vm_pageout_pages_needed && 925 vmstats.v_cache_count + vmstats.v_free_count >= 926 vmstats.v_pageout_free_min 927 ) { 928 wakeup(&vm_pageout_pages_needed); 929 vm_pageout_pages_needed = 0; 930 } 931 932 /* 933 * wakeup processes that are waiting on memory if we hit a 934 * high water mark. And wakeup scheduler process if we have 935 * lots of memory. this process will swapin processes. 936 */ 937 if (vm_pages_needed && !vm_page_count_min(0)) { 938 vm_pages_needed = 0; 939 wakeup(&vmstats.v_free_count); 940 } 941 } 942 943 /* 944 * vm_page_free_toq: 945 * 946 * Returns the given page to the PQ_FREE list, disassociating it with 947 * any VM object. 948 * 949 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 950 * return (the page will have been freed). No particular spl is required 951 * on entry. 952 * 953 * This routine may not block. 954 */ 955 void 956 vm_page_free_toq(vm_page_t m) 957 { 958 struct vpgqueues *pq; 959 960 crit_enter(); 961 mycpu->gd_cnt.v_tfree++; 962 963 KKASSERT((m->flags & PG_MAPPED) == 0); 964 965 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 966 kprintf( 967 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 968 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 969 m->hold_count); 970 if ((m->queue - m->pc) == PQ_FREE) 971 panic("vm_page_free: freeing free page"); 972 else 973 panic("vm_page_free: freeing busy page"); 974 } 975 976 /* 977 * unqueue, then remove page. Note that we cannot destroy 978 * the page here because we do not want to call the pager's 979 * callback routine until after we've put the page on the 980 * appropriate free queue. 981 */ 982 vm_page_unqueue_nowakeup(m); 983 vm_page_remove(m); 984 985 /* 986 * No further management of fictitious pages occurs beyond object 987 * and queue removal. 988 */ 989 if ((m->flags & PG_FICTITIOUS) != 0) { 990 vm_page_wakeup(m); 991 crit_exit(); 992 return; 993 } 994 995 m->valid = 0; 996 vm_page_undirty(m); 997 998 if (m->wire_count != 0) { 999 if (m->wire_count > 1) { 1000 panic( 1001 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1002 m->wire_count, (long)m->pindex); 1003 } 1004 panic("vm_page_free: freeing wired page"); 1005 } 1006 1007 /* 1008 * Clear the UNMANAGED flag when freeing an unmanaged page. 1009 */ 1010 if (m->flags & PG_UNMANAGED) { 1011 m->flags &= ~PG_UNMANAGED; 1012 } 1013 1014 if (m->hold_count != 0) { 1015 m->flags &= ~PG_ZERO; 1016 m->queue = PQ_HOLD; 1017 } else { 1018 m->queue = PQ_FREE + m->pc; 1019 } 1020 pq = &vm_page_queues[m->queue]; 1021 pq->lcnt++; 1022 ++(*pq->cnt); 1023 1024 /* 1025 * Put zero'd pages on the end ( where we look for zero'd pages 1026 * first ) and non-zerod pages at the head. 1027 */ 1028 if (m->flags & PG_ZERO) { 1029 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1030 ++vm_page_zero_count; 1031 } else { 1032 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1033 } 1034 vm_page_wakeup(m); 1035 vm_page_free_wakeup(); 1036 crit_exit(); 1037 } 1038 1039 /* 1040 * vm_page_unmanage() 1041 * 1042 * Prevent PV management from being done on the page. The page is 1043 * removed from the paging queues as if it were wired, and as a 1044 * consequence of no longer being managed the pageout daemon will not 1045 * touch it (since there is no way to locate the pte mappings for the 1046 * page). madvise() calls that mess with the pmap will also no longer 1047 * operate on the page. 1048 * 1049 * Beyond that the page is still reasonably 'normal'. Freeing the page 1050 * will clear the flag. 1051 * 1052 * This routine is used by OBJT_PHYS objects - objects using unswappable 1053 * physical memory as backing store rather then swap-backed memory and 1054 * will eventually be extended to support 4MB unmanaged physical 1055 * mappings. 1056 * 1057 * Must be called with a critical section held. 1058 */ 1059 void 1060 vm_page_unmanage(vm_page_t m) 1061 { 1062 ASSERT_IN_CRIT_SECTION(); 1063 if ((m->flags & PG_UNMANAGED) == 0) { 1064 if (m->wire_count == 0) 1065 vm_page_unqueue(m); 1066 } 1067 vm_page_flag_set(m, PG_UNMANAGED); 1068 } 1069 1070 /* 1071 * Mark this page as wired down by yet another map, removing it from 1072 * paging queues as necessary. 1073 * 1074 * The page queues must be locked. 1075 * This routine may not block. 1076 */ 1077 void 1078 vm_page_wire(vm_page_t m) 1079 { 1080 /* 1081 * Only bump the wire statistics if the page is not already wired, 1082 * and only unqueue the page if it is on some queue (if it is unmanaged 1083 * it is already off the queues). Don't do anything with fictitious 1084 * pages because they are always wired. 1085 */ 1086 crit_enter(); 1087 if ((m->flags & PG_FICTITIOUS) == 0) { 1088 if (m->wire_count == 0) { 1089 if ((m->flags & PG_UNMANAGED) == 0) 1090 vm_page_unqueue(m); 1091 vmstats.v_wire_count++; 1092 } 1093 m->wire_count++; 1094 KASSERT(m->wire_count != 0, 1095 ("vm_page_wire: wire_count overflow m=%p", m)); 1096 } 1097 crit_exit(); 1098 } 1099 1100 /* 1101 * Release one wiring of this page, potentially enabling it to be paged again. 1102 * 1103 * Many pages placed on the inactive queue should actually go 1104 * into the cache, but it is difficult to figure out which. What 1105 * we do instead, if the inactive target is well met, is to put 1106 * clean pages at the head of the inactive queue instead of the tail. 1107 * This will cause them to be moved to the cache more quickly and 1108 * if not actively re-referenced, freed more quickly. If we just 1109 * stick these pages at the end of the inactive queue, heavy filesystem 1110 * meta-data accesses can cause an unnecessary paging load on memory bound 1111 * processes. This optimization causes one-time-use metadata to be 1112 * reused more quickly. 1113 * 1114 * BUT, if we are in a low-memory situation we have no choice but to 1115 * put clean pages on the cache queue. 1116 * 1117 * A number of routines use vm_page_unwire() to guarantee that the page 1118 * will go into either the inactive or active queues, and will NEVER 1119 * be placed in the cache - for example, just after dirtying a page. 1120 * dirty pages in the cache are not allowed. 1121 * 1122 * The page queues must be locked. 1123 * This routine may not block. 1124 */ 1125 void 1126 vm_page_unwire(vm_page_t m, int activate) 1127 { 1128 crit_enter(); 1129 if (m->flags & PG_FICTITIOUS) { 1130 /* do nothing */ 1131 } else if (m->wire_count <= 0) { 1132 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1133 } else { 1134 if (--m->wire_count == 0) { 1135 --vmstats.v_wire_count; 1136 if (m->flags & PG_UNMANAGED) { 1137 ; 1138 } else if (activate) { 1139 TAILQ_INSERT_TAIL( 1140 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1141 m->queue = PQ_ACTIVE; 1142 vm_page_queues[PQ_ACTIVE].lcnt++; 1143 vmstats.v_active_count++; 1144 } else { 1145 vm_page_flag_clear(m, PG_WINATCFLS); 1146 TAILQ_INSERT_TAIL( 1147 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1148 m->queue = PQ_INACTIVE; 1149 vm_page_queues[PQ_INACTIVE].lcnt++; 1150 vmstats.v_inactive_count++; 1151 ++vm_swapcache_inactive_heuristic; 1152 } 1153 } 1154 } 1155 crit_exit(); 1156 } 1157 1158 1159 /* 1160 * Move the specified page to the inactive queue. If the page has 1161 * any associated swap, the swap is deallocated. 1162 * 1163 * Normally athead is 0 resulting in LRU operation. athead is set 1164 * to 1 if we want this page to be 'as if it were placed in the cache', 1165 * except without unmapping it from the process address space. 1166 * 1167 * This routine may not block. 1168 */ 1169 static __inline void 1170 _vm_page_deactivate(vm_page_t m, int athead) 1171 { 1172 /* 1173 * Ignore if already inactive. 1174 */ 1175 if (m->queue == PQ_INACTIVE) 1176 return; 1177 1178 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1179 if ((m->queue - m->pc) == PQ_CACHE) 1180 mycpu->gd_cnt.v_reactivated++; 1181 vm_page_flag_clear(m, PG_WINATCFLS); 1182 vm_page_unqueue(m); 1183 if (athead) { 1184 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, 1185 m, pageq); 1186 } else { 1187 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, 1188 m, pageq); 1189 ++vm_swapcache_inactive_heuristic; 1190 } 1191 m->queue = PQ_INACTIVE; 1192 vm_page_queues[PQ_INACTIVE].lcnt++; 1193 vmstats.v_inactive_count++; 1194 } 1195 } 1196 1197 void 1198 vm_page_deactivate(vm_page_t m) 1199 { 1200 crit_enter(); 1201 _vm_page_deactivate(m, 0); 1202 crit_exit(); 1203 } 1204 1205 /* 1206 * vm_page_try_to_cache: 1207 * 1208 * Returns 0 on failure, 1 on success 1209 */ 1210 int 1211 vm_page_try_to_cache(vm_page_t m) 1212 { 1213 crit_enter(); 1214 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1215 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1216 crit_exit(); 1217 return(0); 1218 } 1219 vm_page_test_dirty(m); 1220 if (m->dirty) { 1221 crit_exit(); 1222 return(0); 1223 } 1224 vm_page_cache(m); 1225 crit_exit(); 1226 return(1); 1227 } 1228 1229 /* 1230 * Attempt to free the page. If we cannot free it, we do nothing. 1231 * 1 is returned on success, 0 on failure. 1232 */ 1233 int 1234 vm_page_try_to_free(vm_page_t m) 1235 { 1236 crit_enter(); 1237 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1238 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1239 crit_exit(); 1240 return(0); 1241 } 1242 vm_page_test_dirty(m); 1243 if (m->dirty) { 1244 crit_exit(); 1245 return(0); 1246 } 1247 vm_page_busy(m); 1248 vm_page_protect(m, VM_PROT_NONE); 1249 vm_page_free(m); 1250 crit_exit(); 1251 return(1); 1252 } 1253 1254 /* 1255 * vm_page_cache 1256 * 1257 * Put the specified page onto the page cache queue (if appropriate). 1258 * 1259 * This routine may not block. 1260 */ 1261 void 1262 vm_page_cache(vm_page_t m) 1263 { 1264 ASSERT_IN_CRIT_SECTION(); 1265 1266 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1267 m->wire_count || m->hold_count) { 1268 kprintf("vm_page_cache: attempting to cache busy/held page\n"); 1269 return; 1270 } 1271 1272 /* 1273 * Already in the cache (and thus not mapped) 1274 */ 1275 if ((m->queue - m->pc) == PQ_CACHE) { 1276 KKASSERT((m->flags & PG_MAPPED) == 0); 1277 return; 1278 } 1279 1280 /* 1281 * Caller is required to test m->dirty, but note that the act of 1282 * removing the page from its maps can cause it to become dirty 1283 * on an SMP system due to another cpu running in usermode. 1284 */ 1285 if (m->dirty) { 1286 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1287 (long)m->pindex); 1288 } 1289 1290 /* 1291 * Remove all pmaps and indicate that the page is not 1292 * writeable or mapped. Our vm_page_protect() call may 1293 * have blocked (especially w/ VM_PROT_NONE), so recheck 1294 * everything. 1295 */ 1296 vm_page_busy(m); 1297 vm_page_protect(m, VM_PROT_NONE); 1298 vm_page_wakeup(m); 1299 if ((m->flags & (PG_BUSY|PG_UNMANAGED|PG_MAPPED)) || m->busy || 1300 m->wire_count || m->hold_count) { 1301 /* do nothing */ 1302 } else if (m->dirty) { 1303 vm_page_deactivate(m); 1304 } else { 1305 vm_page_unqueue_nowakeup(m); 1306 m->queue = PQ_CACHE + m->pc; 1307 vm_page_queues[m->queue].lcnt++; 1308 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1309 vmstats.v_cache_count++; 1310 vm_page_free_wakeup(); 1311 } 1312 } 1313 1314 /* 1315 * vm_page_dontneed() 1316 * 1317 * Cache, deactivate, or do nothing as appropriate. This routine 1318 * is typically used by madvise() MADV_DONTNEED. 1319 * 1320 * Generally speaking we want to move the page into the cache so 1321 * it gets reused quickly. However, this can result in a silly syndrome 1322 * due to the page recycling too quickly. Small objects will not be 1323 * fully cached. On the otherhand, if we move the page to the inactive 1324 * queue we wind up with a problem whereby very large objects 1325 * unnecessarily blow away our inactive and cache queues. 1326 * 1327 * The solution is to move the pages based on a fixed weighting. We 1328 * either leave them alone, deactivate them, or move them to the cache, 1329 * where moving them to the cache has the highest weighting. 1330 * By forcing some pages into other queues we eventually force the 1331 * system to balance the queues, potentially recovering other unrelated 1332 * space from active. The idea is to not force this to happen too 1333 * often. 1334 */ 1335 void 1336 vm_page_dontneed(vm_page_t m) 1337 { 1338 static int dnweight; 1339 int dnw; 1340 int head; 1341 1342 dnw = ++dnweight; 1343 1344 /* 1345 * occassionally leave the page alone 1346 */ 1347 crit_enter(); 1348 if ((dnw & 0x01F0) == 0 || 1349 m->queue == PQ_INACTIVE || 1350 m->queue - m->pc == PQ_CACHE 1351 ) { 1352 if (m->act_count >= ACT_INIT) 1353 --m->act_count; 1354 crit_exit(); 1355 return; 1356 } 1357 1358 if (m->dirty == 0) 1359 vm_page_test_dirty(m); 1360 1361 if (m->dirty || (dnw & 0x0070) == 0) { 1362 /* 1363 * Deactivate the page 3 times out of 32. 1364 */ 1365 head = 0; 1366 } else { 1367 /* 1368 * Cache the page 28 times out of every 32. Note that 1369 * the page is deactivated instead of cached, but placed 1370 * at the head of the queue instead of the tail. 1371 */ 1372 head = 1; 1373 } 1374 _vm_page_deactivate(m, head); 1375 crit_exit(); 1376 } 1377 1378 /* 1379 * Grab a page, blocking if it is busy and allocating a page if necessary. 1380 * A busy page is returned or NULL. 1381 * 1382 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1383 * If VM_ALLOC_RETRY is not specified 1384 * 1385 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1386 * always returned if we had blocked. 1387 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1388 * This routine may not be called from an interrupt. 1389 * The returned page may not be entirely valid. 1390 * 1391 * This routine may be called from mainline code without spl protection and 1392 * be guarenteed a busied page associated with the object at the specified 1393 * index. 1394 */ 1395 vm_page_t 1396 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1397 { 1398 vm_page_t m; 1399 int generation; 1400 1401 KKASSERT(allocflags & 1402 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1403 crit_enter(); 1404 retrylookup: 1405 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1406 if (m->busy || (m->flags & PG_BUSY)) { 1407 generation = object->generation; 1408 1409 while ((object->generation == generation) && 1410 (m->busy || (m->flags & PG_BUSY))) { 1411 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1412 tsleep(m, 0, "pgrbwt", 0); 1413 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1414 m = NULL; 1415 goto done; 1416 } 1417 } 1418 goto retrylookup; 1419 } else { 1420 vm_page_busy(m); 1421 goto done; 1422 } 1423 } 1424 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1425 if (m == NULL) { 1426 vm_wait(0); 1427 if ((allocflags & VM_ALLOC_RETRY) == 0) 1428 goto done; 1429 goto retrylookup; 1430 } 1431 done: 1432 crit_exit(); 1433 return(m); 1434 } 1435 1436 /* 1437 * Mapping function for valid bits or for dirty bits in 1438 * a page. May not block. 1439 * 1440 * Inputs are required to range within a page. 1441 */ 1442 __inline int 1443 vm_page_bits(int base, int size) 1444 { 1445 int first_bit; 1446 int last_bit; 1447 1448 KASSERT( 1449 base + size <= PAGE_SIZE, 1450 ("vm_page_bits: illegal base/size %d/%d", base, size) 1451 ); 1452 1453 if (size == 0) /* handle degenerate case */ 1454 return(0); 1455 1456 first_bit = base >> DEV_BSHIFT; 1457 last_bit = (base + size - 1) >> DEV_BSHIFT; 1458 1459 return ((2 << last_bit) - (1 << first_bit)); 1460 } 1461 1462 /* 1463 * Sets portions of a page valid and clean. The arguments are expected 1464 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1465 * of any partial chunks touched by the range. The invalid portion of 1466 * such chunks will be zero'd. 1467 * 1468 * NOTE: When truncating a buffer vnode_pager_setsize() will automatically 1469 * align base to DEV_BSIZE so as not to mark clean a partially 1470 * truncated device block. Otherwise the dirty page status might be 1471 * lost. 1472 * 1473 * This routine may not block. 1474 * 1475 * (base + size) must be less then or equal to PAGE_SIZE. 1476 */ 1477 static void 1478 _vm_page_zero_valid(vm_page_t m, int base, int size) 1479 { 1480 int frag; 1481 int endoff; 1482 1483 if (size == 0) /* handle degenerate case */ 1484 return; 1485 1486 /* 1487 * If the base is not DEV_BSIZE aligned and the valid 1488 * bit is clear, we have to zero out a portion of the 1489 * first block. 1490 */ 1491 1492 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1493 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1494 ) { 1495 pmap_zero_page_area( 1496 VM_PAGE_TO_PHYS(m), 1497 frag, 1498 base - frag 1499 ); 1500 } 1501 1502 /* 1503 * If the ending offset is not DEV_BSIZE aligned and the 1504 * valid bit is clear, we have to zero out a portion of 1505 * the last block. 1506 */ 1507 1508 endoff = base + size; 1509 1510 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1511 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1512 ) { 1513 pmap_zero_page_area( 1514 VM_PAGE_TO_PHYS(m), 1515 endoff, 1516 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1517 ); 1518 } 1519 } 1520 1521 /* 1522 * Set valid, clear dirty bits. If validating the entire 1523 * page we can safely clear the pmap modify bit. We also 1524 * use this opportunity to clear the PG_NOSYNC flag. If a process 1525 * takes a write fault on a MAP_NOSYNC memory area the flag will 1526 * be set again. 1527 * 1528 * We set valid bits inclusive of any overlap, but we can only 1529 * clear dirty bits for DEV_BSIZE chunks that are fully within 1530 * the range. 1531 */ 1532 void 1533 vm_page_set_valid(vm_page_t m, int base, int size) 1534 { 1535 _vm_page_zero_valid(m, base, size); 1536 m->valid |= vm_page_bits(base, size); 1537 } 1538 1539 1540 /* 1541 * Set valid bits and clear dirty bits. 1542 * 1543 * NOTE: This function does not clear the pmap modified bit. 1544 * Also note that e.g. NFS may use a byte-granular base 1545 * and size. 1546 */ 1547 void 1548 vm_page_set_validclean(vm_page_t m, int base, int size) 1549 { 1550 int pagebits; 1551 1552 _vm_page_zero_valid(m, base, size); 1553 pagebits = vm_page_bits(base, size); 1554 m->valid |= pagebits; 1555 m->dirty &= ~pagebits; 1556 if (base == 0 && size == PAGE_SIZE) { 1557 /*pmap_clear_modify(m);*/ 1558 vm_page_flag_clear(m, PG_NOSYNC); 1559 } 1560 } 1561 1562 /* 1563 * Set valid & dirty. Used by buwrite() 1564 */ 1565 void 1566 vm_page_set_validdirty(vm_page_t m, int base, int size) 1567 { 1568 int pagebits; 1569 1570 pagebits = vm_page_bits(base, size); 1571 m->valid |= pagebits; 1572 m->dirty |= pagebits; 1573 if (m->object) 1574 vm_object_set_writeable_dirty(m->object); 1575 } 1576 1577 /* 1578 * Clear dirty bits. 1579 * 1580 * NOTE: This function does not clear the pmap modified bit. 1581 * Also note that e.g. NFS may use a byte-granular base 1582 * and size. 1583 */ 1584 void 1585 vm_page_clear_dirty(vm_page_t m, int base, int size) 1586 { 1587 m->dirty &= ~vm_page_bits(base, size); 1588 if (base == 0 && size == PAGE_SIZE) { 1589 /*pmap_clear_modify(m);*/ 1590 vm_page_flag_clear(m, PG_NOSYNC); 1591 } 1592 } 1593 1594 /* 1595 * Make the page all-dirty. 1596 * 1597 * Also make sure the related object and vnode reflect the fact that the 1598 * object may now contain a dirty page. 1599 */ 1600 void 1601 vm_page_dirty(vm_page_t m) 1602 { 1603 #ifdef INVARIANTS 1604 int pqtype = m->queue - m->pc; 1605 #endif 1606 KASSERT(pqtype != PQ_CACHE && pqtype != PQ_FREE, 1607 ("vm_page_dirty: page in free/cache queue!")); 1608 if (m->dirty != VM_PAGE_BITS_ALL) { 1609 m->dirty = VM_PAGE_BITS_ALL; 1610 if (m->object) 1611 vm_object_set_writeable_dirty(m->object); 1612 } 1613 } 1614 1615 /* 1616 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1617 * valid and dirty bits for the effected areas are cleared. 1618 * 1619 * May not block. 1620 */ 1621 void 1622 vm_page_set_invalid(vm_page_t m, int base, int size) 1623 { 1624 int bits; 1625 1626 bits = vm_page_bits(base, size); 1627 m->valid &= ~bits; 1628 m->dirty &= ~bits; 1629 m->object->generation++; 1630 } 1631 1632 /* 1633 * The kernel assumes that the invalid portions of a page contain 1634 * garbage, but such pages can be mapped into memory by user code. 1635 * When this occurs, we must zero out the non-valid portions of the 1636 * page so user code sees what it expects. 1637 * 1638 * Pages are most often semi-valid when the end of a file is mapped 1639 * into memory and the file's size is not page aligned. 1640 */ 1641 void 1642 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1643 { 1644 int b; 1645 int i; 1646 1647 /* 1648 * Scan the valid bits looking for invalid sections that 1649 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1650 * valid bit may be set ) have already been zerod by 1651 * vm_page_set_validclean(). 1652 */ 1653 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1654 if (i == (PAGE_SIZE / DEV_BSIZE) || 1655 (m->valid & (1 << i)) 1656 ) { 1657 if (i > b) { 1658 pmap_zero_page_area( 1659 VM_PAGE_TO_PHYS(m), 1660 b << DEV_BSHIFT, 1661 (i - b) << DEV_BSHIFT 1662 ); 1663 } 1664 b = i + 1; 1665 } 1666 } 1667 1668 /* 1669 * setvalid is TRUE when we can safely set the zero'd areas 1670 * as being valid. We can do this if there are no cache consistency 1671 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1672 */ 1673 if (setvalid) 1674 m->valid = VM_PAGE_BITS_ALL; 1675 } 1676 1677 /* 1678 * Is a (partial) page valid? Note that the case where size == 0 1679 * will return FALSE in the degenerate case where the page is entirely 1680 * invalid, and TRUE otherwise. 1681 * 1682 * May not block. 1683 */ 1684 int 1685 vm_page_is_valid(vm_page_t m, int base, int size) 1686 { 1687 int bits = vm_page_bits(base, size); 1688 1689 if (m->valid && ((m->valid & bits) == bits)) 1690 return 1; 1691 else 1692 return 0; 1693 } 1694 1695 /* 1696 * update dirty bits from pmap/mmu. May not block. 1697 */ 1698 void 1699 vm_page_test_dirty(vm_page_t m) 1700 { 1701 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1702 vm_page_dirty(m); 1703 } 1704 } 1705 1706 /* 1707 * Issue an event on a VM page. Corresponding action structures are 1708 * removed from the page's list and called. 1709 */ 1710 void 1711 vm_page_event_internal(vm_page_t m, vm_page_event_t event) 1712 { 1713 struct vm_page_action *scan, *next; 1714 1715 LIST_FOREACH_MUTABLE(scan, &m->action_list, entry, next) { 1716 if (scan->event == event) { 1717 scan->event = VMEVENT_NONE; 1718 LIST_REMOVE(scan, entry); 1719 scan->func(m, scan); 1720 } 1721 } 1722 } 1723 1724 #include "opt_ddb.h" 1725 #ifdef DDB 1726 #include <sys/kernel.h> 1727 1728 #include <ddb/ddb.h> 1729 1730 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1731 { 1732 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1733 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1734 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1735 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1736 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1737 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1738 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1739 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1740 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1741 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1742 } 1743 1744 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1745 { 1746 int i; 1747 db_printf("PQ_FREE:"); 1748 for(i=0;i<PQ_L2_SIZE;i++) { 1749 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1750 } 1751 db_printf("\n"); 1752 1753 db_printf("PQ_CACHE:"); 1754 for(i=0;i<PQ_L2_SIZE;i++) { 1755 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1756 } 1757 db_printf("\n"); 1758 1759 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1760 vm_page_queues[PQ_ACTIVE].lcnt, 1761 vm_page_queues[PQ_INACTIVE].lcnt); 1762 } 1763 #endif /* DDB */ 1764