1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991 Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91 39 * $FreeBSD: src/sys/vm/vm_page.c,v 1.147.2.18 2002/03/10 05:03:19 alc Exp $ 40 * $DragonFly: src/sys/vm/vm_page.c,v 1.40 2008/08/25 17:01:42 dillon Exp $ 41 */ 42 43 /* 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 /* 70 * Resident memory management module. The module manipulates 'VM pages'. 71 * A VM page is the core building block for memory management. 72 */ 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/malloc.h> 77 #include <sys/proc.h> 78 #include <sys/vmmeter.h> 79 #include <sys/vnode.h> 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <sys/lock.h> 84 #include <vm/vm_kern.h> 85 #include <vm/pmap.h> 86 #include <vm/vm_map.h> 87 #include <vm/vm_object.h> 88 #include <vm/vm_page.h> 89 #include <vm/vm_pageout.h> 90 #include <vm/vm_pager.h> 91 #include <vm/vm_extern.h> 92 #include <vm/swap_pager.h> 93 94 #include <machine/md_var.h> 95 96 #include <vm/vm_page2.h> 97 #include <sys/mplock2.h> 98 99 static void vm_page_queue_init(void); 100 static void vm_page_free_wakeup(void); 101 static vm_page_t vm_page_select_cache(vm_object_t, vm_pindex_t); 102 static vm_page_t _vm_page_list_find2(int basequeue, int index); 103 104 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 105 106 #define ASSERT_IN_CRIT_SECTION() KKASSERT(crit_test(curthread)); 107 108 RB_GENERATE2(vm_page_rb_tree, vm_page, rb_entry, rb_vm_page_compare, 109 vm_pindex_t, pindex); 110 111 static void 112 vm_page_queue_init(void) 113 { 114 int i; 115 116 for (i = 0; i < PQ_L2_SIZE; i++) 117 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 118 for (i = 0; i < PQ_L2_SIZE; i++) 119 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 120 121 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 122 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 123 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 124 /* PQ_NONE has no queue */ 125 126 for (i = 0; i < PQ_COUNT; i++) 127 TAILQ_INIT(&vm_page_queues[i].pl); 128 } 129 130 /* 131 * note: place in initialized data section? Is this necessary? 132 */ 133 long first_page = 0; 134 int vm_page_array_size = 0; 135 int vm_page_zero_count = 0; 136 vm_page_t vm_page_array = 0; 137 138 /* 139 * (low level boot) 140 * 141 * Sets the page size, perhaps based upon the memory size. 142 * Must be called before any use of page-size dependent functions. 143 */ 144 void 145 vm_set_page_size(void) 146 { 147 if (vmstats.v_page_size == 0) 148 vmstats.v_page_size = PAGE_SIZE; 149 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 150 panic("vm_set_page_size: page size not a power of two"); 151 } 152 153 /* 154 * (low level boot) 155 * 156 * Add a new page to the freelist for use by the system. New pages 157 * are added to both the head and tail of the associated free page 158 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 159 * requests pull 'recent' adds (higher physical addresses) first. 160 * 161 * Must be called in a critical section. 162 */ 163 vm_page_t 164 vm_add_new_page(vm_paddr_t pa) 165 { 166 struct vpgqueues *vpq; 167 vm_page_t m; 168 169 ++vmstats.v_page_count; 170 ++vmstats.v_free_count; 171 m = PHYS_TO_VM_PAGE(pa); 172 m->phys_addr = pa; 173 m->flags = 0; 174 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 175 m->queue = m->pc + PQ_FREE; 176 KKASSERT(m->dirty == 0); 177 178 vpq = &vm_page_queues[m->queue]; 179 if (vpq->flipflop) 180 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 181 else 182 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 183 vpq->flipflop = 1 - vpq->flipflop; 184 185 vm_page_queues[m->queue].lcnt++; 186 return (m); 187 } 188 189 /* 190 * (low level boot) 191 * 192 * Initializes the resident memory module. 193 * 194 * Allocates memory for the page cells, and for the object/offset-to-page 195 * hash table headers. Each page cell is initialized and placed on the 196 * free list. 197 * 198 * starta/enda represents the range of physical memory addresses available 199 * for use (skipping memory already used by the kernel), subject to 200 * phys_avail[]. Note that phys_avail[] has already mapped out memory 201 * already in use by the kernel. 202 */ 203 vm_offset_t 204 vm_page_startup(vm_offset_t vaddr) 205 { 206 vm_offset_t mapped; 207 vm_size_t npages; 208 vm_paddr_t page_range; 209 vm_paddr_t new_end; 210 int i; 211 vm_paddr_t pa; 212 int nblocks; 213 vm_paddr_t last_pa; 214 vm_paddr_t end; 215 vm_paddr_t biggestone, biggestsize; 216 vm_paddr_t total; 217 218 total = 0; 219 biggestsize = 0; 220 biggestone = 0; 221 nblocks = 0; 222 vaddr = round_page(vaddr); 223 224 for (i = 0; phys_avail[i + 1]; i += 2) { 225 phys_avail[i] = round_page64(phys_avail[i]); 226 phys_avail[i + 1] = trunc_page64(phys_avail[i + 1]); 227 } 228 229 for (i = 0; phys_avail[i + 1]; i += 2) { 230 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 231 232 if (size > biggestsize) { 233 biggestone = i; 234 biggestsize = size; 235 } 236 ++nblocks; 237 total += size; 238 } 239 240 end = phys_avail[biggestone+1]; 241 end = trunc_page(end); 242 243 /* 244 * Initialize the queue headers for the free queue, the active queue 245 * and the inactive queue. 246 */ 247 248 vm_page_queue_init(); 249 250 /* VKERNELs don't support minidumps and as such don't need vm_page_dump */ 251 #if !defined(_KERNEL_VIRTUAL) 252 /* 253 * Allocate a bitmap to indicate that a random physical page 254 * needs to be included in a minidump. 255 * 256 * The amd64 port needs this to indicate which direct map pages 257 * need to be dumped, via calls to dump_add_page()/dump_drop_page(). 258 * 259 * However, i386 still needs this workspace internally within the 260 * minidump code. In theory, they are not needed on i386, but are 261 * included should the sf_buf code decide to use them. 262 */ 263 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE; 264 vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY); 265 end -= vm_page_dump_size; 266 vm_page_dump = (void *)pmap_map(&vaddr, end, end + vm_page_dump_size, 267 VM_PROT_READ | VM_PROT_WRITE); 268 bzero((void *)vm_page_dump, vm_page_dump_size); 269 #endif 270 271 /* 272 * Compute the number of pages of memory that will be available for 273 * use (taking into account the overhead of a page structure per 274 * page). 275 */ 276 first_page = phys_avail[0] / PAGE_SIZE; 277 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 278 npages = (total - (page_range * sizeof(struct vm_page))) / PAGE_SIZE; 279 280 /* 281 * Initialize the mem entry structures now, and put them in the free 282 * queue. 283 */ 284 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 285 mapped = pmap_map(&vaddr, new_end, end, 286 VM_PROT_READ | VM_PROT_WRITE); 287 vm_page_array = (vm_page_t)mapped; 288 289 #if defined(__x86_64__) && !defined(_KERNEL_VIRTUAL) 290 /* 291 * since pmap_map on amd64 returns stuff out of a direct-map region, 292 * we have to manually add these pages to the minidump tracking so 293 * that they can be dumped, including the vm_page_array. 294 */ 295 for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE) 296 dump_add_page(pa); 297 #endif 298 299 /* 300 * Clear all of the page structures 301 */ 302 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 303 vm_page_array_size = page_range; 304 305 /* 306 * Construct the free queue(s) in ascending order (by physical 307 * address) so that the first 16MB of physical memory is allocated 308 * last rather than first. On large-memory machines, this avoids 309 * the exhaustion of low physical memory before isa_dmainit has run. 310 */ 311 vmstats.v_page_count = 0; 312 vmstats.v_free_count = 0; 313 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 314 pa = phys_avail[i]; 315 if (i == biggestone) 316 last_pa = new_end; 317 else 318 last_pa = phys_avail[i + 1]; 319 while (pa < last_pa && npages-- > 0) { 320 vm_add_new_page(pa); 321 pa += PAGE_SIZE; 322 } 323 } 324 return (vaddr); 325 } 326 327 /* 328 * Scan comparison function for Red-Black tree scans. An inclusive 329 * (start,end) is expected. Other fields are not used. 330 */ 331 int 332 rb_vm_page_scancmp(struct vm_page *p, void *data) 333 { 334 struct rb_vm_page_scan_info *info = data; 335 336 if (p->pindex < info->start_pindex) 337 return(-1); 338 if (p->pindex > info->end_pindex) 339 return(1); 340 return(0); 341 } 342 343 int 344 rb_vm_page_compare(struct vm_page *p1, struct vm_page *p2) 345 { 346 if (p1->pindex < p2->pindex) 347 return(-1); 348 if (p1->pindex > p2->pindex) 349 return(1); 350 return(0); 351 } 352 353 /* 354 * The opposite of vm_page_hold(). A page can be freed while being held, 355 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 356 * in this case to actually free it once the hold count drops to 0. 357 * 358 * This routine must be called at splvm(). 359 */ 360 void 361 vm_page_unhold(vm_page_t mem) 362 { 363 --mem->hold_count; 364 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 365 if (mem->hold_count == 0 && mem->queue == PQ_HOLD) { 366 vm_page_busy(mem); 367 vm_page_free_toq(mem); 368 } 369 } 370 371 /* 372 * Inserts the given mem entry into the object and object list. 373 * 374 * The pagetables are not updated but will presumably fault the page 375 * in if necessary, or if a kernel page the caller will at some point 376 * enter the page into the kernel's pmap. We are not allowed to block 377 * here so we *can't* do this anyway. 378 * 379 * This routine may not block. 380 * This routine must be called with a critical section held. 381 */ 382 void 383 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 384 { 385 ASSERT_IN_CRIT_SECTION(); 386 if (m->object != NULL) 387 panic("vm_page_insert: already inserted"); 388 389 /* 390 * Record the object/offset pair in this page 391 */ 392 m->object = object; 393 m->pindex = pindex; 394 395 /* 396 * Insert it into the object. 397 */ 398 ASSERT_MP_LOCK_HELD(curthread); 399 vm_page_rb_tree_RB_INSERT(&object->rb_memq, m); 400 object->generation++; 401 402 /* 403 * show that the object has one more resident page. 404 */ 405 object->resident_page_count++; 406 407 /* 408 * Since we are inserting a new and possibly dirty page, 409 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 410 */ 411 if ((m->valid & m->dirty) || (m->flags & PG_WRITEABLE)) 412 vm_object_set_writeable_dirty(object); 413 414 /* 415 * Checks for a swap assignment and sets PG_SWAPPED if appropriate. 416 */ 417 swap_pager_page_inserted(m); 418 } 419 420 /* 421 * Removes the given vm_page_t from the global (object,index) hash table 422 * and from the object's memq. 423 * 424 * The underlying pmap entry (if any) is NOT removed here. 425 * This routine may not block. 426 * 427 * The page must be BUSY and will remain BUSY on return. 428 * No other requirements. 429 * 430 * NOTE: FreeBSD side effect was to unbusy the page on return. We leave 431 * it busy. 432 */ 433 void 434 vm_page_remove(vm_page_t m) 435 { 436 vm_object_t object; 437 438 crit_enter(); 439 lwkt_gettoken(&vm_token); 440 if (m->object == NULL) { 441 lwkt_reltoken(&vm_token); 442 crit_exit(); 443 return; 444 } 445 446 if ((m->flags & PG_BUSY) == 0) 447 panic("vm_page_remove: page not busy"); 448 449 object = m->object; 450 451 /* 452 * Remove the page from the object and update the object. 453 */ 454 ASSERT_MP_LOCK_HELD(curthread); 455 vm_page_rb_tree_RB_REMOVE(&object->rb_memq, m); 456 object->resident_page_count--; 457 object->generation++; 458 m->object = NULL; 459 460 lwkt_reltoken(&vm_token); 461 crit_exit(); 462 } 463 464 /* 465 * Locate and return the page at (object, pindex), or NULL if the 466 * page could not be found. 467 * 468 * This routine will operate properly without spl protection, but 469 * the returned page could be in flux if it is busy. Because an 470 * interrupt can race a caller's busy check (unbusying and freeing the 471 * page we return before the caller is able to check the busy bit), 472 * the caller should generally call this routine with a critical 473 * section held. 474 * 475 * Callers may call this routine without spl protection if they know 476 * 'for sure' that the page will not be ripped out from under them 477 * by an interrupt. 478 */ 479 vm_page_t 480 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 481 { 482 vm_page_t m; 483 484 /* 485 * Search the hash table for this object/offset pair 486 */ 487 ASSERT_MP_LOCK_HELD(curthread); 488 crit_enter(); 489 lwkt_gettoken(&vm_token); 490 m = vm_page_rb_tree_RB_LOOKUP(&object->rb_memq, pindex); 491 lwkt_reltoken(&vm_token); 492 crit_exit(); 493 KKASSERT(m == NULL || (m->object == object && m->pindex == pindex)); 494 return(m); 495 } 496 497 /* 498 * vm_page_rename() 499 * 500 * Move the given memory entry from its current object to the specified 501 * target object/offset. 502 * 503 * The object must be locked. 504 * This routine may not block. 505 * 506 * Note: This routine will raise itself to splvm(), the caller need not. 507 * 508 * Note: Swap associated with the page must be invalidated by the move. We 509 * have to do this for several reasons: (1) we aren't freeing the 510 * page, (2) we are dirtying the page, (3) the VM system is probably 511 * moving the page from object A to B, and will then later move 512 * the backing store from A to B and we can't have a conflict. 513 * 514 * Note: We *always* dirty the page. It is necessary both for the 515 * fact that we moved it, and because we may be invalidating 516 * swap. If the page is on the cache, we have to deactivate it 517 * or vm_page_dirty() will panic. Dirty pages are not allowed 518 * on the cache. 519 */ 520 void 521 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 522 { 523 crit_enter(); 524 lwkt_gettoken(&vm_token); 525 vm_page_remove(m); 526 vm_page_insert(m, new_object, new_pindex); 527 if (m->queue - m->pc == PQ_CACHE) 528 vm_page_deactivate(m); 529 vm_page_dirty(m); 530 vm_page_wakeup(m); 531 lwkt_reltoken(&vm_token); 532 crit_exit(); 533 } 534 535 /* 536 * vm_page_unqueue() without any wakeup. This routine is used when a page 537 * is being moved between queues or otherwise is to remain BUSYied by the 538 * caller. 539 * 540 * This routine must be called at splhigh(). 541 * This routine may not block. 542 */ 543 void 544 vm_page_unqueue_nowakeup(vm_page_t m) 545 { 546 int queue = m->queue; 547 struct vpgqueues *pq; 548 549 if (queue != PQ_NONE) { 550 pq = &vm_page_queues[queue]; 551 m->queue = PQ_NONE; 552 TAILQ_REMOVE(&pq->pl, m, pageq); 553 (*pq->cnt)--; 554 pq->lcnt--; 555 } 556 } 557 558 /* 559 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 560 * if necessary. 561 * 562 * This routine must be called at splhigh(). 563 * This routine may not block. 564 */ 565 void 566 vm_page_unqueue(vm_page_t m) 567 { 568 int queue = m->queue; 569 struct vpgqueues *pq; 570 571 if (queue != PQ_NONE) { 572 m->queue = PQ_NONE; 573 pq = &vm_page_queues[queue]; 574 TAILQ_REMOVE(&pq->pl, m, pageq); 575 (*pq->cnt)--; 576 pq->lcnt--; 577 if ((queue - m->pc) == PQ_CACHE || (queue - m->pc) == PQ_FREE) 578 pagedaemon_wakeup(); 579 } 580 } 581 582 /* 583 * vm_page_list_find() 584 * 585 * Find a page on the specified queue with color optimization. 586 * 587 * The page coloring optimization attempts to locate a page that does 588 * not overload other nearby pages in the object in the cpu's L1 or L2 589 * caches. We need this optimization because cpu caches tend to be 590 * physical caches, while object spaces tend to be virtual. 591 * 592 * This routine must be called at splvm(). 593 * This routine may not block. 594 * 595 * Note that this routine is carefully inlined. A non-inlined version 596 * is available for outside callers but the only critical path is 597 * from within this source file. 598 */ 599 static __inline 600 vm_page_t 601 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 602 { 603 vm_page_t m; 604 605 if (prefer_zero) 606 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 607 else 608 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 609 if (m == NULL) 610 m = _vm_page_list_find2(basequeue, index); 611 return(m); 612 } 613 614 static vm_page_t 615 _vm_page_list_find2(int basequeue, int index) 616 { 617 int i; 618 vm_page_t m = NULL; 619 struct vpgqueues *pq; 620 621 pq = &vm_page_queues[basequeue]; 622 623 /* 624 * Note that for the first loop, index+i and index-i wind up at the 625 * same place. Even though this is not totally optimal, we've already 626 * blown it by missing the cache case so we do not care. 627 */ 628 629 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 630 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 631 break; 632 633 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 634 break; 635 } 636 return(m); 637 } 638 639 vm_page_t 640 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 641 { 642 return(_vm_page_list_find(basequeue, index, prefer_zero)); 643 } 644 645 /* 646 * Find a page on the cache queue with color optimization. As pages 647 * might be found, but not applicable, they are deactivated. This 648 * keeps us from using potentially busy cached pages. 649 * 650 * This routine must be called with a critical section held. 651 * This routine may not block. 652 */ 653 vm_page_t 654 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 655 { 656 vm_page_t m; 657 658 while (TRUE) { 659 m = _vm_page_list_find( 660 PQ_CACHE, 661 (pindex + object->pg_color) & PQ_L2_MASK, 662 FALSE 663 ); 664 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 665 m->hold_count || m->wire_count)) { 666 vm_page_deactivate(m); 667 continue; 668 } 669 return m; 670 } 671 /* not reached */ 672 } 673 674 /* 675 * Find a free or zero page, with specified preference. We attempt to 676 * inline the nominal case and fall back to _vm_page_select_free() 677 * otherwise. 678 * 679 * This routine must be called with a critical section held. 680 * This routine may not block. 681 */ 682 static __inline vm_page_t 683 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 684 { 685 vm_page_t m; 686 687 m = _vm_page_list_find( 688 PQ_FREE, 689 (pindex + object->pg_color) & PQ_L2_MASK, 690 prefer_zero 691 ); 692 return(m); 693 } 694 695 /* 696 * vm_page_alloc() 697 * 698 * Allocate and return a memory cell associated with this VM object/offset 699 * pair. 700 * 701 * page_req classes: 702 * 703 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 704 * VM_ALLOC_QUICK like normal but cannot use cache 705 * VM_ALLOC_SYSTEM greater free drain 706 * VM_ALLOC_INTERRUPT allow free list to be completely drained 707 * VM_ALLOC_ZERO advisory request for pre-zero'd page 708 * 709 * The object must be locked. 710 * This routine may not block. 711 * The returned page will be marked PG_BUSY 712 * 713 * Additional special handling is required when called from an interrupt 714 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 715 * in this case. 716 */ 717 vm_page_t 718 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 719 { 720 vm_page_t m = NULL; 721 722 KKASSERT(object != NULL); 723 KASSERT(!vm_page_lookup(object, pindex), 724 ("vm_page_alloc: page already allocated")); 725 KKASSERT(page_req & 726 (VM_ALLOC_NORMAL|VM_ALLOC_QUICK| 727 VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 728 729 /* 730 * Certain system threads (pageout daemon, buf_daemon's) are 731 * allowed to eat deeper into the free page list. 732 */ 733 if (curthread->td_flags & TDF_SYSTHREAD) 734 page_req |= VM_ALLOC_SYSTEM; 735 736 crit_enter(); 737 lwkt_gettoken(&vm_token); 738 loop: 739 if (vmstats.v_free_count > vmstats.v_free_reserved || 740 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 741 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 742 vmstats.v_free_count > vmstats.v_interrupt_free_min) 743 ) { 744 /* 745 * The free queue has sufficient free pages to take one out. 746 */ 747 if (page_req & VM_ALLOC_ZERO) 748 m = vm_page_select_free(object, pindex, TRUE); 749 else 750 m = vm_page_select_free(object, pindex, FALSE); 751 } else if (page_req & VM_ALLOC_NORMAL) { 752 /* 753 * Allocatable from the cache (non-interrupt only). On 754 * success, we must free the page and try again, thus 755 * ensuring that vmstats.v_*_free_min counters are replenished. 756 */ 757 #ifdef INVARIANTS 758 if (curthread->td_preempted) { 759 kprintf("vm_page_alloc(): warning, attempt to allocate" 760 " cache page from preempting interrupt\n"); 761 m = NULL; 762 } else { 763 m = vm_page_select_cache(object, pindex); 764 } 765 #else 766 m = vm_page_select_cache(object, pindex); 767 #endif 768 /* 769 * On success move the page into the free queue and loop. 770 */ 771 if (m != NULL) { 772 KASSERT(m->dirty == 0, 773 ("Found dirty cache page %p", m)); 774 vm_page_busy(m); 775 vm_page_protect(m, VM_PROT_NONE); 776 vm_page_free(m); 777 goto loop; 778 } 779 780 /* 781 * On failure return NULL 782 */ 783 lwkt_reltoken(&vm_token); 784 crit_exit(); 785 #if defined(DIAGNOSTIC) 786 if (vmstats.v_cache_count > 0) 787 kprintf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 788 #endif 789 vm_pageout_deficit++; 790 pagedaemon_wakeup(); 791 return (NULL); 792 } else { 793 /* 794 * No pages available, wakeup the pageout daemon and give up. 795 */ 796 lwkt_reltoken(&vm_token); 797 crit_exit(); 798 vm_pageout_deficit++; 799 pagedaemon_wakeup(); 800 return (NULL); 801 } 802 803 /* 804 * Good page found. The page has not yet been busied. We are in 805 * a critical section. 806 */ 807 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 808 KASSERT(m->dirty == 0, 809 ("vm_page_alloc: free/cache page %p was dirty", m)); 810 811 /* 812 * Remove from free queue 813 */ 814 vm_page_unqueue_nowakeup(m); 815 816 /* 817 * Initialize structure. Only the PG_ZERO flag is inherited. Set 818 * the page PG_BUSY 819 */ 820 if (m->flags & PG_ZERO) { 821 vm_page_zero_count--; 822 m->flags = PG_ZERO | PG_BUSY; 823 } else { 824 m->flags = PG_BUSY; 825 } 826 m->wire_count = 0; 827 m->hold_count = 0; 828 m->act_count = 0; 829 m->busy = 0; 830 m->valid = 0; 831 832 /* 833 * vm_page_insert() is safe prior to the crit_exit(). Note also that 834 * inserting a page here does not insert it into the pmap (which 835 * could cause us to block allocating memory). We cannot block 836 * anywhere. 837 */ 838 vm_page_insert(m, object, pindex); 839 840 /* 841 * Don't wakeup too often - wakeup the pageout daemon when 842 * we would be nearly out of memory. 843 */ 844 pagedaemon_wakeup(); 845 846 lwkt_reltoken(&vm_token); 847 crit_exit(); 848 849 /* 850 * A PG_BUSY page is returned. 851 */ 852 return (m); 853 } 854 855 /* 856 * Wait for sufficient free memory for nominal heavy memory use kernel 857 * operations. 858 */ 859 void 860 vm_wait_nominal(void) 861 { 862 while (vm_page_count_min(0)) 863 vm_wait(0); 864 } 865 866 /* 867 * Test if vm_wait_nominal() would block. 868 */ 869 int 870 vm_test_nominal(void) 871 { 872 if (vm_page_count_min(0)) 873 return(1); 874 return(0); 875 } 876 877 /* 878 * Block until free pages are available for allocation, called in various 879 * places before memory allocations. 880 */ 881 void 882 vm_wait(int timo) 883 { 884 crit_enter(); 885 lwkt_gettoken(&vm_token); 886 if (curthread == pagethread) { 887 vm_pageout_pages_needed = 1; 888 tsleep(&vm_pageout_pages_needed, 0, "VMWait", timo); 889 } else { 890 if (vm_pages_needed == 0) { 891 vm_pages_needed = 1; 892 wakeup(&vm_pages_needed); 893 } 894 tsleep(&vmstats.v_free_count, 0, "vmwait", timo); 895 } 896 lwkt_reltoken(&vm_token); 897 crit_exit(); 898 } 899 900 /* 901 * Block until free pages are available for allocation 902 * 903 * Called only in vm_fault so that processes page faulting can be 904 * easily tracked. 905 */ 906 void 907 vm_waitpfault(void) 908 { 909 crit_enter(); 910 lwkt_gettoken(&vm_token); 911 if (vm_pages_needed == 0) { 912 vm_pages_needed = 1; 913 wakeup(&vm_pages_needed); 914 } 915 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 916 lwkt_reltoken(&vm_token); 917 crit_exit(); 918 } 919 920 /* 921 * Put the specified page on the active list (if appropriate). Ensure 922 * that act_count is at least ACT_INIT but do not otherwise mess with it. 923 * 924 * The page queues must be locked. 925 * This routine may not block. 926 */ 927 void 928 vm_page_activate(vm_page_t m) 929 { 930 crit_enter(); 931 lwkt_gettoken(&vm_token); 932 if (m->queue != PQ_ACTIVE) { 933 if ((m->queue - m->pc) == PQ_CACHE) 934 mycpu->gd_cnt.v_reactivated++; 935 936 vm_page_unqueue(m); 937 938 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 939 m->queue = PQ_ACTIVE; 940 vm_page_queues[PQ_ACTIVE].lcnt++; 941 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 942 m, pageq); 943 if (m->act_count < ACT_INIT) 944 m->act_count = ACT_INIT; 945 vmstats.v_active_count++; 946 } 947 } else { 948 if (m->act_count < ACT_INIT) 949 m->act_count = ACT_INIT; 950 } 951 lwkt_reltoken(&vm_token); 952 crit_exit(); 953 } 954 955 /* 956 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 957 * routine is called when a page has been added to the cache or free 958 * queues. 959 * 960 * This routine may not block. 961 * This routine must be called at splvm() 962 */ 963 static __inline void 964 vm_page_free_wakeup(void) 965 { 966 /* 967 * if pageout daemon needs pages, then tell it that there are 968 * some free. 969 */ 970 if (vm_pageout_pages_needed && 971 vmstats.v_cache_count + vmstats.v_free_count >= 972 vmstats.v_pageout_free_min 973 ) { 974 wakeup(&vm_pageout_pages_needed); 975 vm_pageout_pages_needed = 0; 976 } 977 978 /* 979 * wakeup processes that are waiting on memory if we hit a 980 * high water mark. And wakeup scheduler process if we have 981 * lots of memory. this process will swapin processes. 982 */ 983 if (vm_pages_needed && !vm_page_count_min(0)) { 984 vm_pages_needed = 0; 985 wakeup(&vmstats.v_free_count); 986 } 987 } 988 989 /* 990 * vm_page_free_toq: 991 * 992 * Returns the given page to the PQ_FREE list, disassociating it with 993 * any VM object. 994 * 995 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 996 * return (the page will have been freed). No particular spl is required 997 * on entry. 998 * 999 * This routine may not block. 1000 */ 1001 void 1002 vm_page_free_toq(vm_page_t m) 1003 { 1004 struct vpgqueues *pq; 1005 1006 crit_enter(); 1007 lwkt_gettoken(&vm_token); 1008 mycpu->gd_cnt.v_tfree++; 1009 1010 KKASSERT((m->flags & PG_MAPPED) == 0); 1011 1012 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1013 kprintf( 1014 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1015 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1016 m->hold_count); 1017 if ((m->queue - m->pc) == PQ_FREE) 1018 panic("vm_page_free: freeing free page"); 1019 else 1020 panic("vm_page_free: freeing busy page"); 1021 } 1022 1023 /* 1024 * unqueue, then remove page. Note that we cannot destroy 1025 * the page here because we do not want to call the pager's 1026 * callback routine until after we've put the page on the 1027 * appropriate free queue. 1028 */ 1029 vm_page_unqueue_nowakeup(m); 1030 vm_page_remove(m); 1031 1032 /* 1033 * No further management of fictitious pages occurs beyond object 1034 * and queue removal. 1035 */ 1036 if ((m->flags & PG_FICTITIOUS) != 0) { 1037 vm_page_wakeup(m); 1038 lwkt_reltoken(&vm_token); 1039 crit_exit(); 1040 return; 1041 } 1042 1043 m->valid = 0; 1044 vm_page_undirty(m); 1045 1046 if (m->wire_count != 0) { 1047 if (m->wire_count > 1) { 1048 panic( 1049 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1050 m->wire_count, (long)m->pindex); 1051 } 1052 panic("vm_page_free: freeing wired page"); 1053 } 1054 1055 /* 1056 * Clear the UNMANAGED flag when freeing an unmanaged page. 1057 */ 1058 if (m->flags & PG_UNMANAGED) { 1059 m->flags &= ~PG_UNMANAGED; 1060 } 1061 1062 if (m->hold_count != 0) { 1063 m->flags &= ~PG_ZERO; 1064 m->queue = PQ_HOLD; 1065 } else { 1066 m->queue = PQ_FREE + m->pc; 1067 } 1068 pq = &vm_page_queues[m->queue]; 1069 pq->lcnt++; 1070 ++(*pq->cnt); 1071 1072 /* 1073 * Put zero'd pages on the end ( where we look for zero'd pages 1074 * first ) and non-zerod pages at the head. 1075 */ 1076 if (m->flags & PG_ZERO) { 1077 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1078 ++vm_page_zero_count; 1079 } else { 1080 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1081 } 1082 vm_page_wakeup(m); 1083 vm_page_free_wakeup(); 1084 lwkt_reltoken(&vm_token); 1085 crit_exit(); 1086 } 1087 1088 /* 1089 * vm_page_free_fromq_fast() 1090 * 1091 * Remove a non-zero page from one of the free queues; the page is removed for 1092 * zeroing, so do not issue a wakeup. 1093 * 1094 * MPUNSAFE 1095 */ 1096 vm_page_t 1097 vm_page_free_fromq_fast(void) 1098 { 1099 static int qi; 1100 vm_page_t m; 1101 int i; 1102 1103 crit_enter(); 1104 lwkt_gettoken(&vm_token); 1105 for (i = 0; i < PQ_L2_SIZE; ++i) { 1106 m = vm_page_list_find(PQ_FREE, qi, FALSE); 1107 qi = (qi + PQ_PRIME2) & PQ_L2_MASK; 1108 if (m && (m->flags & PG_ZERO) == 0) { 1109 vm_page_unqueue_nowakeup(m); 1110 vm_page_busy(m); 1111 break; 1112 } 1113 m = NULL; 1114 } 1115 lwkt_reltoken(&vm_token); 1116 crit_exit(); 1117 return (m); 1118 } 1119 1120 /* 1121 * vm_page_unmanage() 1122 * 1123 * Prevent PV management from being done on the page. The page is 1124 * removed from the paging queues as if it were wired, and as a 1125 * consequence of no longer being managed the pageout daemon will not 1126 * touch it (since there is no way to locate the pte mappings for the 1127 * page). madvise() calls that mess with the pmap will also no longer 1128 * operate on the page. 1129 * 1130 * Beyond that the page is still reasonably 'normal'. Freeing the page 1131 * will clear the flag. 1132 * 1133 * This routine is used by OBJT_PHYS objects - objects using unswappable 1134 * physical memory as backing store rather then swap-backed memory and 1135 * will eventually be extended to support 4MB unmanaged physical 1136 * mappings. 1137 * 1138 * Must be called with a critical section held. 1139 */ 1140 void 1141 vm_page_unmanage(vm_page_t m) 1142 { 1143 ASSERT_IN_CRIT_SECTION(); 1144 if ((m->flags & PG_UNMANAGED) == 0) { 1145 if (m->wire_count == 0) 1146 vm_page_unqueue(m); 1147 } 1148 vm_page_flag_set(m, PG_UNMANAGED); 1149 } 1150 1151 /* 1152 * Mark this page as wired down by yet another map, removing it from 1153 * paging queues as necessary. 1154 * 1155 * The page queues must be locked. 1156 * This routine may not block. 1157 */ 1158 void 1159 vm_page_wire(vm_page_t m) 1160 { 1161 /* 1162 * Only bump the wire statistics if the page is not already wired, 1163 * and only unqueue the page if it is on some queue (if it is unmanaged 1164 * it is already off the queues). Don't do anything with fictitious 1165 * pages because they are always wired. 1166 */ 1167 crit_enter(); 1168 lwkt_gettoken(&vm_token); 1169 if ((m->flags & PG_FICTITIOUS) == 0) { 1170 if (m->wire_count == 0) { 1171 if ((m->flags & PG_UNMANAGED) == 0) 1172 vm_page_unqueue(m); 1173 vmstats.v_wire_count++; 1174 } 1175 m->wire_count++; 1176 KASSERT(m->wire_count != 0, 1177 ("vm_page_wire: wire_count overflow m=%p", m)); 1178 } 1179 lwkt_reltoken(&vm_token); 1180 crit_exit(); 1181 } 1182 1183 /* 1184 * Release one wiring of this page, potentially enabling it to be paged again. 1185 * 1186 * Many pages placed on the inactive queue should actually go 1187 * into the cache, but it is difficult to figure out which. What 1188 * we do instead, if the inactive target is well met, is to put 1189 * clean pages at the head of the inactive queue instead of the tail. 1190 * This will cause them to be moved to the cache more quickly and 1191 * if not actively re-referenced, freed more quickly. If we just 1192 * stick these pages at the end of the inactive queue, heavy filesystem 1193 * meta-data accesses can cause an unnecessary paging load on memory bound 1194 * processes. This optimization causes one-time-use metadata to be 1195 * reused more quickly. 1196 * 1197 * BUT, if we are in a low-memory situation we have no choice but to 1198 * put clean pages on the cache queue. 1199 * 1200 * A number of routines use vm_page_unwire() to guarantee that the page 1201 * will go into either the inactive or active queues, and will NEVER 1202 * be placed in the cache - for example, just after dirtying a page. 1203 * dirty pages in the cache are not allowed. 1204 * 1205 * The page queues must be locked. 1206 * This routine may not block. 1207 */ 1208 void 1209 vm_page_unwire(vm_page_t m, int activate) 1210 { 1211 crit_enter(); 1212 lwkt_gettoken(&vm_token); 1213 if (m->flags & PG_FICTITIOUS) { 1214 /* do nothing */ 1215 } else if (m->wire_count <= 0) { 1216 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1217 } else { 1218 if (--m->wire_count == 0) { 1219 --vmstats.v_wire_count; 1220 if (m->flags & PG_UNMANAGED) { 1221 ; 1222 } else if (activate) { 1223 TAILQ_INSERT_TAIL( 1224 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1225 m->queue = PQ_ACTIVE; 1226 vm_page_queues[PQ_ACTIVE].lcnt++; 1227 vmstats.v_active_count++; 1228 } else { 1229 vm_page_flag_clear(m, PG_WINATCFLS); 1230 TAILQ_INSERT_TAIL( 1231 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1232 m->queue = PQ_INACTIVE; 1233 vm_page_queues[PQ_INACTIVE].lcnt++; 1234 vmstats.v_inactive_count++; 1235 ++vm_swapcache_inactive_heuristic; 1236 } 1237 } 1238 } 1239 lwkt_reltoken(&vm_token); 1240 crit_exit(); 1241 } 1242 1243 1244 /* 1245 * Move the specified page to the inactive queue. If the page has 1246 * any associated swap, the swap is deallocated. 1247 * 1248 * Normally athead is 0 resulting in LRU operation. athead is set 1249 * to 1 if we want this page to be 'as if it were placed in the cache', 1250 * except without unmapping it from the process address space. 1251 * 1252 * This routine may not block. 1253 */ 1254 static __inline void 1255 _vm_page_deactivate(vm_page_t m, int athead) 1256 { 1257 /* 1258 * Ignore if already inactive. 1259 */ 1260 if (m->queue == PQ_INACTIVE) 1261 return; 1262 1263 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1264 if ((m->queue - m->pc) == PQ_CACHE) 1265 mycpu->gd_cnt.v_reactivated++; 1266 vm_page_flag_clear(m, PG_WINATCFLS); 1267 vm_page_unqueue(m); 1268 if (athead) { 1269 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, 1270 m, pageq); 1271 } else { 1272 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, 1273 m, pageq); 1274 ++vm_swapcache_inactive_heuristic; 1275 } 1276 m->queue = PQ_INACTIVE; 1277 vm_page_queues[PQ_INACTIVE].lcnt++; 1278 vmstats.v_inactive_count++; 1279 } 1280 } 1281 1282 void 1283 vm_page_deactivate(vm_page_t m) 1284 { 1285 crit_enter(); 1286 lwkt_gettoken(&vm_token); 1287 _vm_page_deactivate(m, 0); 1288 lwkt_reltoken(&vm_token); 1289 crit_exit(); 1290 } 1291 1292 /* 1293 * vm_page_try_to_cache: 1294 * 1295 * Returns 0 on failure, 1 on success 1296 */ 1297 int 1298 vm_page_try_to_cache(vm_page_t m) 1299 { 1300 crit_enter(); 1301 lwkt_gettoken(&vm_token); 1302 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1303 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1304 lwkt_reltoken(&vm_token); 1305 crit_exit(); 1306 return(0); 1307 } 1308 vm_page_test_dirty(m); 1309 if (m->dirty) { 1310 lwkt_reltoken(&vm_token); 1311 crit_exit(); 1312 return(0); 1313 } 1314 vm_page_cache(m); 1315 lwkt_reltoken(&vm_token); 1316 crit_exit(); 1317 return(1); 1318 } 1319 1320 /* 1321 * Attempt to free the page. If we cannot free it, we do nothing. 1322 * 1 is returned on success, 0 on failure. 1323 */ 1324 int 1325 vm_page_try_to_free(vm_page_t m) 1326 { 1327 crit_enter(); 1328 lwkt_gettoken(&vm_token); 1329 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1330 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1331 lwkt_reltoken(&vm_token); 1332 crit_exit(); 1333 return(0); 1334 } 1335 vm_page_test_dirty(m); 1336 if (m->dirty) { 1337 lwkt_reltoken(&vm_token); 1338 crit_exit(); 1339 return(0); 1340 } 1341 vm_page_busy(m); 1342 vm_page_protect(m, VM_PROT_NONE); 1343 vm_page_free(m); 1344 lwkt_reltoken(&vm_token); 1345 crit_exit(); 1346 return(1); 1347 } 1348 1349 /* 1350 * vm_page_cache 1351 * 1352 * Put the specified page onto the page cache queue (if appropriate). 1353 * 1354 * This routine may not block. 1355 */ 1356 void 1357 vm_page_cache(vm_page_t m) 1358 { 1359 ASSERT_IN_CRIT_SECTION(); 1360 1361 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1362 m->wire_count || m->hold_count) { 1363 kprintf("vm_page_cache: attempting to cache busy/held page\n"); 1364 return; 1365 } 1366 1367 /* 1368 * Already in the cache (and thus not mapped) 1369 */ 1370 if ((m->queue - m->pc) == PQ_CACHE) { 1371 KKASSERT((m->flags & PG_MAPPED) == 0); 1372 return; 1373 } 1374 1375 /* 1376 * Caller is required to test m->dirty, but note that the act of 1377 * removing the page from its maps can cause it to become dirty 1378 * on an SMP system due to another cpu running in usermode. 1379 */ 1380 if (m->dirty) { 1381 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1382 (long)m->pindex); 1383 } 1384 1385 /* 1386 * Remove all pmaps and indicate that the page is not 1387 * writeable or mapped. Our vm_page_protect() call may 1388 * have blocked (especially w/ VM_PROT_NONE), so recheck 1389 * everything. 1390 */ 1391 vm_page_busy(m); 1392 vm_page_protect(m, VM_PROT_NONE); 1393 vm_page_wakeup(m); 1394 if ((m->flags & (PG_BUSY|PG_UNMANAGED|PG_MAPPED)) || m->busy || 1395 m->wire_count || m->hold_count) { 1396 /* do nothing */ 1397 } else if (m->dirty) { 1398 vm_page_deactivate(m); 1399 } else { 1400 vm_page_unqueue_nowakeup(m); 1401 m->queue = PQ_CACHE + m->pc; 1402 vm_page_queues[m->queue].lcnt++; 1403 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1404 vmstats.v_cache_count++; 1405 vm_page_free_wakeup(); 1406 } 1407 } 1408 1409 /* 1410 * vm_page_dontneed() 1411 * 1412 * Cache, deactivate, or do nothing as appropriate. This routine 1413 * is typically used by madvise() MADV_DONTNEED. 1414 * 1415 * Generally speaking we want to move the page into the cache so 1416 * it gets reused quickly. However, this can result in a silly syndrome 1417 * due to the page recycling too quickly. Small objects will not be 1418 * fully cached. On the otherhand, if we move the page to the inactive 1419 * queue we wind up with a problem whereby very large objects 1420 * unnecessarily blow away our inactive and cache queues. 1421 * 1422 * The solution is to move the pages based on a fixed weighting. We 1423 * either leave them alone, deactivate them, or move them to the cache, 1424 * where moving them to the cache has the highest weighting. 1425 * By forcing some pages into other queues we eventually force the 1426 * system to balance the queues, potentially recovering other unrelated 1427 * space from active. The idea is to not force this to happen too 1428 * often. 1429 */ 1430 void 1431 vm_page_dontneed(vm_page_t m) 1432 { 1433 static int dnweight; 1434 int dnw; 1435 int head; 1436 1437 dnw = ++dnweight; 1438 1439 /* 1440 * occassionally leave the page alone 1441 */ 1442 crit_enter(); 1443 lwkt_gettoken(&vm_token); 1444 if ((dnw & 0x01F0) == 0 || 1445 m->queue == PQ_INACTIVE || 1446 m->queue - m->pc == PQ_CACHE 1447 ) { 1448 if (m->act_count >= ACT_INIT) 1449 --m->act_count; 1450 lwkt_reltoken(&vm_token); 1451 crit_exit(); 1452 return; 1453 } 1454 1455 if (m->dirty == 0) 1456 vm_page_test_dirty(m); 1457 1458 if (m->dirty || (dnw & 0x0070) == 0) { 1459 /* 1460 * Deactivate the page 3 times out of 32. 1461 */ 1462 head = 0; 1463 } else { 1464 /* 1465 * Cache the page 28 times out of every 32. Note that 1466 * the page is deactivated instead of cached, but placed 1467 * at the head of the queue instead of the tail. 1468 */ 1469 head = 1; 1470 } 1471 _vm_page_deactivate(m, head); 1472 lwkt_reltoken(&vm_token); 1473 crit_exit(); 1474 } 1475 1476 /* 1477 * Grab a page, blocking if it is busy and allocating a page if necessary. 1478 * A busy page is returned or NULL. 1479 * 1480 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1481 * If VM_ALLOC_RETRY is not specified 1482 * 1483 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1484 * always returned if we had blocked. 1485 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1486 * This routine may not be called from an interrupt. 1487 * The returned page may not be entirely valid. 1488 * 1489 * This routine may be called from mainline code without spl protection and 1490 * be guarenteed a busied page associated with the object at the specified 1491 * index. 1492 */ 1493 vm_page_t 1494 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1495 { 1496 vm_page_t m; 1497 int generation; 1498 1499 KKASSERT(allocflags & 1500 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1501 crit_enter(); 1502 lwkt_gettoken(&vm_token); 1503 retrylookup: 1504 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1505 if (m->busy || (m->flags & PG_BUSY)) { 1506 generation = object->generation; 1507 1508 while ((object->generation == generation) && 1509 (m->busy || (m->flags & PG_BUSY))) { 1510 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1511 tsleep(m, 0, "pgrbwt", 0); 1512 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1513 m = NULL; 1514 goto done; 1515 } 1516 } 1517 goto retrylookup; 1518 } else { 1519 vm_page_busy(m); 1520 goto done; 1521 } 1522 } 1523 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1524 if (m == NULL) { 1525 vm_wait(0); 1526 if ((allocflags & VM_ALLOC_RETRY) == 0) 1527 goto done; 1528 goto retrylookup; 1529 } 1530 done: 1531 lwkt_reltoken(&vm_token); 1532 crit_exit(); 1533 return(m); 1534 } 1535 1536 /* 1537 * Mapping function for valid bits or for dirty bits in 1538 * a page. May not block. 1539 * 1540 * Inputs are required to range within a page. 1541 */ 1542 __inline int 1543 vm_page_bits(int base, int size) 1544 { 1545 int first_bit; 1546 int last_bit; 1547 1548 KASSERT( 1549 base + size <= PAGE_SIZE, 1550 ("vm_page_bits: illegal base/size %d/%d", base, size) 1551 ); 1552 1553 if (size == 0) /* handle degenerate case */ 1554 return(0); 1555 1556 first_bit = base >> DEV_BSHIFT; 1557 last_bit = (base + size - 1) >> DEV_BSHIFT; 1558 1559 return ((2 << last_bit) - (1 << first_bit)); 1560 } 1561 1562 /* 1563 * Sets portions of a page valid and clean. The arguments are expected 1564 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1565 * of any partial chunks touched by the range. The invalid portion of 1566 * such chunks will be zero'd. 1567 * 1568 * NOTE: When truncating a buffer vnode_pager_setsize() will automatically 1569 * align base to DEV_BSIZE so as not to mark clean a partially 1570 * truncated device block. Otherwise the dirty page status might be 1571 * lost. 1572 * 1573 * This routine may not block. 1574 * 1575 * (base + size) must be less then or equal to PAGE_SIZE. 1576 */ 1577 static void 1578 _vm_page_zero_valid(vm_page_t m, int base, int size) 1579 { 1580 int frag; 1581 int endoff; 1582 1583 if (size == 0) /* handle degenerate case */ 1584 return; 1585 1586 /* 1587 * If the base is not DEV_BSIZE aligned and the valid 1588 * bit is clear, we have to zero out a portion of the 1589 * first block. 1590 */ 1591 1592 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1593 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1594 ) { 1595 pmap_zero_page_area( 1596 VM_PAGE_TO_PHYS(m), 1597 frag, 1598 base - frag 1599 ); 1600 } 1601 1602 /* 1603 * If the ending offset is not DEV_BSIZE aligned and the 1604 * valid bit is clear, we have to zero out a portion of 1605 * the last block. 1606 */ 1607 1608 endoff = base + size; 1609 1610 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1611 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1612 ) { 1613 pmap_zero_page_area( 1614 VM_PAGE_TO_PHYS(m), 1615 endoff, 1616 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1617 ); 1618 } 1619 } 1620 1621 /* 1622 * Set valid, clear dirty bits. If validating the entire 1623 * page we can safely clear the pmap modify bit. We also 1624 * use this opportunity to clear the PG_NOSYNC flag. If a process 1625 * takes a write fault on a MAP_NOSYNC memory area the flag will 1626 * be set again. 1627 * 1628 * We set valid bits inclusive of any overlap, but we can only 1629 * clear dirty bits for DEV_BSIZE chunks that are fully within 1630 * the range. 1631 */ 1632 void 1633 vm_page_set_valid(vm_page_t m, int base, int size) 1634 { 1635 _vm_page_zero_valid(m, base, size); 1636 m->valid |= vm_page_bits(base, size); 1637 } 1638 1639 1640 /* 1641 * Set valid bits and clear dirty bits. 1642 * 1643 * NOTE: This function does not clear the pmap modified bit. 1644 * Also note that e.g. NFS may use a byte-granular base 1645 * and size. 1646 */ 1647 void 1648 vm_page_set_validclean(vm_page_t m, int base, int size) 1649 { 1650 int pagebits; 1651 1652 _vm_page_zero_valid(m, base, size); 1653 pagebits = vm_page_bits(base, size); 1654 m->valid |= pagebits; 1655 m->dirty &= ~pagebits; 1656 if (base == 0 && size == PAGE_SIZE) { 1657 /*pmap_clear_modify(m);*/ 1658 vm_page_flag_clear(m, PG_NOSYNC); 1659 } 1660 } 1661 1662 /* 1663 * Set valid & dirty. Used by buwrite() 1664 */ 1665 void 1666 vm_page_set_validdirty(vm_page_t m, int base, int size) 1667 { 1668 int pagebits; 1669 1670 pagebits = vm_page_bits(base, size); 1671 m->valid |= pagebits; 1672 m->dirty |= pagebits; 1673 if (m->object) 1674 vm_object_set_writeable_dirty(m->object); 1675 } 1676 1677 /* 1678 * Clear dirty bits. 1679 * 1680 * NOTE: This function does not clear the pmap modified bit. 1681 * Also note that e.g. NFS may use a byte-granular base 1682 * and size. 1683 */ 1684 void 1685 vm_page_clear_dirty(vm_page_t m, int base, int size) 1686 { 1687 m->dirty &= ~vm_page_bits(base, size); 1688 if (base == 0 && size == PAGE_SIZE) { 1689 /*pmap_clear_modify(m);*/ 1690 vm_page_flag_clear(m, PG_NOSYNC); 1691 } 1692 } 1693 1694 /* 1695 * Make the page all-dirty. 1696 * 1697 * Also make sure the related object and vnode reflect the fact that the 1698 * object may now contain a dirty page. 1699 */ 1700 void 1701 vm_page_dirty(vm_page_t m) 1702 { 1703 #ifdef INVARIANTS 1704 int pqtype = m->queue - m->pc; 1705 #endif 1706 KASSERT(pqtype != PQ_CACHE && pqtype != PQ_FREE, 1707 ("vm_page_dirty: page in free/cache queue!")); 1708 if (m->dirty != VM_PAGE_BITS_ALL) { 1709 m->dirty = VM_PAGE_BITS_ALL; 1710 if (m->object) 1711 vm_object_set_writeable_dirty(m->object); 1712 } 1713 } 1714 1715 /* 1716 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1717 * valid and dirty bits for the effected areas are cleared. 1718 * 1719 * May not block. 1720 */ 1721 void 1722 vm_page_set_invalid(vm_page_t m, int base, int size) 1723 { 1724 int bits; 1725 1726 bits = vm_page_bits(base, size); 1727 m->valid &= ~bits; 1728 m->dirty &= ~bits; 1729 m->object->generation++; 1730 } 1731 1732 /* 1733 * The kernel assumes that the invalid portions of a page contain 1734 * garbage, but such pages can be mapped into memory by user code. 1735 * When this occurs, we must zero out the non-valid portions of the 1736 * page so user code sees what it expects. 1737 * 1738 * Pages are most often semi-valid when the end of a file is mapped 1739 * into memory and the file's size is not page aligned. 1740 */ 1741 void 1742 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1743 { 1744 int b; 1745 int i; 1746 1747 /* 1748 * Scan the valid bits looking for invalid sections that 1749 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1750 * valid bit may be set ) have already been zerod by 1751 * vm_page_set_validclean(). 1752 */ 1753 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1754 if (i == (PAGE_SIZE / DEV_BSIZE) || 1755 (m->valid & (1 << i)) 1756 ) { 1757 if (i > b) { 1758 pmap_zero_page_area( 1759 VM_PAGE_TO_PHYS(m), 1760 b << DEV_BSHIFT, 1761 (i - b) << DEV_BSHIFT 1762 ); 1763 } 1764 b = i + 1; 1765 } 1766 } 1767 1768 /* 1769 * setvalid is TRUE when we can safely set the zero'd areas 1770 * as being valid. We can do this if there are no cache consistency 1771 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1772 */ 1773 if (setvalid) 1774 m->valid = VM_PAGE_BITS_ALL; 1775 } 1776 1777 /* 1778 * Is a (partial) page valid? Note that the case where size == 0 1779 * will return FALSE in the degenerate case where the page is entirely 1780 * invalid, and TRUE otherwise. 1781 * 1782 * May not block. 1783 */ 1784 int 1785 vm_page_is_valid(vm_page_t m, int base, int size) 1786 { 1787 int bits = vm_page_bits(base, size); 1788 1789 if (m->valid && ((m->valid & bits) == bits)) 1790 return 1; 1791 else 1792 return 0; 1793 } 1794 1795 /* 1796 * update dirty bits from pmap/mmu. May not block. 1797 */ 1798 void 1799 vm_page_test_dirty(vm_page_t m) 1800 { 1801 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1802 vm_page_dirty(m); 1803 } 1804 } 1805 1806 /* 1807 * Issue an event on a VM page. Corresponding action structures are 1808 * removed from the page's list and called. 1809 */ 1810 void 1811 vm_page_event_internal(vm_page_t m, vm_page_event_t event) 1812 { 1813 struct vm_page_action *scan, *next; 1814 1815 LIST_FOREACH_MUTABLE(scan, &m->action_list, entry, next) { 1816 if (scan->event == event) { 1817 scan->event = VMEVENT_NONE; 1818 LIST_REMOVE(scan, entry); 1819 scan->func(m, scan); 1820 } 1821 } 1822 } 1823 1824 1825 #include "opt_ddb.h" 1826 #ifdef DDB 1827 #include <sys/kernel.h> 1828 1829 #include <ddb/ddb.h> 1830 1831 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1832 { 1833 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1834 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1835 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1836 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1837 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1838 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1839 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1840 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1841 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1842 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1843 } 1844 1845 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1846 { 1847 int i; 1848 db_printf("PQ_FREE:"); 1849 for(i=0;i<PQ_L2_SIZE;i++) { 1850 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1851 } 1852 db_printf("\n"); 1853 1854 db_printf("PQ_CACHE:"); 1855 for(i=0;i<PQ_L2_SIZE;i++) { 1856 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 1857 } 1858 db_printf("\n"); 1859 1860 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 1861 vm_page_queues[PQ_ACTIVE].lcnt, 1862 vm_page_queues[PQ_INACTIVE].lcnt); 1863 } 1864 #endif /* DDB */ 1865