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 #define VMACTION_HSIZE 256 100 #define VMACTION_HMASK (VMACTION_HSIZE - 1) 101 102 static void vm_page_queue_init(void); 103 static void vm_page_free_wakeup(void); 104 static vm_page_t vm_page_select_cache(vm_object_t, vm_pindex_t); 105 static vm_page_t _vm_page_list_find2(int basequeue, int index); 106 107 struct vpgqueues vm_page_queues[PQ_COUNT]; /* Array of tailq lists */ 108 109 LIST_HEAD(vm_page_action_list, vm_page_action); 110 struct vm_page_action_list action_list[VMACTION_HSIZE]; 111 112 113 #define ASSERT_IN_CRIT_SECTION() KKASSERT(crit_test(curthread)); 114 115 RB_GENERATE2(vm_page_rb_tree, vm_page, rb_entry, rb_vm_page_compare, 116 vm_pindex_t, pindex); 117 118 static void 119 vm_page_queue_init(void) 120 { 121 int i; 122 123 for (i = 0; i < PQ_L2_SIZE; i++) 124 vm_page_queues[PQ_FREE+i].cnt = &vmstats.v_free_count; 125 for (i = 0; i < PQ_L2_SIZE; i++) 126 vm_page_queues[PQ_CACHE+i].cnt = &vmstats.v_cache_count; 127 128 vm_page_queues[PQ_INACTIVE].cnt = &vmstats.v_inactive_count; 129 vm_page_queues[PQ_ACTIVE].cnt = &vmstats.v_active_count; 130 vm_page_queues[PQ_HOLD].cnt = &vmstats.v_active_count; 131 /* PQ_NONE has no queue */ 132 133 for (i = 0; i < PQ_COUNT; i++) 134 TAILQ_INIT(&vm_page_queues[i].pl); 135 136 for (i = 0; i < VMACTION_HSIZE; i++) 137 LIST_INIT(&action_list[i]); 138 } 139 140 /* 141 * note: place in initialized data section? Is this necessary? 142 */ 143 long first_page = 0; 144 int vm_page_array_size = 0; 145 int vm_page_zero_count = 0; 146 vm_page_t vm_page_array = 0; 147 148 /* 149 * (low level boot) 150 * 151 * Sets the page size, perhaps based upon the memory size. 152 * Must be called before any use of page-size dependent functions. 153 */ 154 void 155 vm_set_page_size(void) 156 { 157 if (vmstats.v_page_size == 0) 158 vmstats.v_page_size = PAGE_SIZE; 159 if (((vmstats.v_page_size - 1) & vmstats.v_page_size) != 0) 160 panic("vm_set_page_size: page size not a power of two"); 161 } 162 163 /* 164 * (low level boot) 165 * 166 * Add a new page to the freelist for use by the system. New pages 167 * are added to both the head and tail of the associated free page 168 * queue in a bottom-up fashion, so both zero'd and non-zero'd page 169 * requests pull 'recent' adds (higher physical addresses) first. 170 * 171 * Must be called in a critical section. 172 */ 173 vm_page_t 174 vm_add_new_page(vm_paddr_t pa) 175 { 176 struct vpgqueues *vpq; 177 vm_page_t m; 178 179 ++vmstats.v_page_count; 180 ++vmstats.v_free_count; 181 m = PHYS_TO_VM_PAGE(pa); 182 m->phys_addr = pa; 183 m->flags = 0; 184 m->pc = (pa >> PAGE_SHIFT) & PQ_L2_MASK; 185 m->queue = m->pc + PQ_FREE; 186 KKASSERT(m->dirty == 0); 187 188 vpq = &vm_page_queues[m->queue]; 189 if (vpq->flipflop) 190 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); 191 else 192 TAILQ_INSERT_HEAD(&vpq->pl, m, pageq); 193 vpq->flipflop = 1 - vpq->flipflop; 194 195 vm_page_queues[m->queue].lcnt++; 196 return (m); 197 } 198 199 /* 200 * (low level boot) 201 * 202 * Initializes the resident memory module. 203 * 204 * Allocates memory for the page cells, and for the object/offset-to-page 205 * hash table headers. Each page cell is initialized and placed on the 206 * free list. 207 * 208 * starta/enda represents the range of physical memory addresses available 209 * for use (skipping memory already used by the kernel), subject to 210 * phys_avail[]. Note that phys_avail[] has already mapped out memory 211 * already in use by the kernel. 212 */ 213 vm_offset_t 214 vm_page_startup(vm_offset_t vaddr) 215 { 216 vm_offset_t mapped; 217 vm_size_t npages; 218 vm_paddr_t page_range; 219 vm_paddr_t new_end; 220 int i; 221 vm_paddr_t pa; 222 int nblocks; 223 vm_paddr_t last_pa; 224 vm_paddr_t end; 225 vm_paddr_t biggestone, biggestsize; 226 vm_paddr_t total; 227 228 total = 0; 229 biggestsize = 0; 230 biggestone = 0; 231 nblocks = 0; 232 vaddr = round_page(vaddr); 233 234 for (i = 0; phys_avail[i + 1]; i += 2) { 235 phys_avail[i] = round_page64(phys_avail[i]); 236 phys_avail[i + 1] = trunc_page64(phys_avail[i + 1]); 237 } 238 239 for (i = 0; phys_avail[i + 1]; i += 2) { 240 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; 241 242 if (size > biggestsize) { 243 biggestone = i; 244 biggestsize = size; 245 } 246 ++nblocks; 247 total += size; 248 } 249 250 end = phys_avail[biggestone+1]; 251 end = trunc_page(end); 252 253 /* 254 * Initialize the queue headers for the free queue, the active queue 255 * and the inactive queue. 256 */ 257 258 vm_page_queue_init(); 259 260 /* VKERNELs don't support minidumps and as such don't need vm_page_dump */ 261 #if !defined(_KERNEL_VIRTUAL) 262 /* 263 * Allocate a bitmap to indicate that a random physical page 264 * needs to be included in a minidump. 265 * 266 * The amd64 port needs this to indicate which direct map pages 267 * need to be dumped, via calls to dump_add_page()/dump_drop_page(). 268 * 269 * However, i386 still needs this workspace internally within the 270 * minidump code. In theory, they are not needed on i386, but are 271 * included should the sf_buf code decide to use them. 272 */ 273 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE; 274 vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY); 275 end -= vm_page_dump_size; 276 vm_page_dump = (void *)pmap_map(&vaddr, end, end + vm_page_dump_size, 277 VM_PROT_READ | VM_PROT_WRITE); 278 bzero((void *)vm_page_dump, vm_page_dump_size); 279 #endif 280 281 /* 282 * Compute the number of pages of memory that will be available for 283 * use (taking into account the overhead of a page structure per 284 * page). 285 */ 286 first_page = phys_avail[0] / PAGE_SIZE; 287 page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page; 288 npages = (total - (page_range * sizeof(struct vm_page))) / PAGE_SIZE; 289 290 /* 291 * Initialize the mem entry structures now, and put them in the free 292 * queue. 293 */ 294 new_end = trunc_page(end - page_range * sizeof(struct vm_page)); 295 mapped = pmap_map(&vaddr, new_end, end, 296 VM_PROT_READ | VM_PROT_WRITE); 297 vm_page_array = (vm_page_t)mapped; 298 299 #if defined(__x86_64__) && !defined(_KERNEL_VIRTUAL) 300 /* 301 * since pmap_map on amd64 returns stuff out of a direct-map region, 302 * we have to manually add these pages to the minidump tracking so 303 * that they can be dumped, including the vm_page_array. 304 */ 305 for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE) 306 dump_add_page(pa); 307 #endif 308 309 /* 310 * Clear all of the page structures 311 */ 312 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); 313 vm_page_array_size = page_range; 314 315 /* 316 * Construct the free queue(s) in ascending order (by physical 317 * address) so that the first 16MB of physical memory is allocated 318 * last rather than first. On large-memory machines, this avoids 319 * the exhaustion of low physical memory before isa_dmainit has run. 320 */ 321 vmstats.v_page_count = 0; 322 vmstats.v_free_count = 0; 323 for (i = 0; phys_avail[i + 1] && npages > 0; i += 2) { 324 pa = phys_avail[i]; 325 if (i == biggestone) 326 last_pa = new_end; 327 else 328 last_pa = phys_avail[i + 1]; 329 while (pa < last_pa && npages-- > 0) { 330 vm_add_new_page(pa); 331 pa += PAGE_SIZE; 332 } 333 } 334 return (vaddr); 335 } 336 337 /* 338 * Scan comparison function for Red-Black tree scans. An inclusive 339 * (start,end) is expected. Other fields are not used. 340 */ 341 int 342 rb_vm_page_scancmp(struct vm_page *p, void *data) 343 { 344 struct rb_vm_page_scan_info *info = data; 345 346 if (p->pindex < info->start_pindex) 347 return(-1); 348 if (p->pindex > info->end_pindex) 349 return(1); 350 return(0); 351 } 352 353 int 354 rb_vm_page_compare(struct vm_page *p1, struct vm_page *p2) 355 { 356 if (p1->pindex < p2->pindex) 357 return(-1); 358 if (p1->pindex > p2->pindex) 359 return(1); 360 return(0); 361 } 362 363 /* 364 * Holding a page keeps it from being reused. Other parts of the system 365 * can still disassociate the page from its current object and free it, or 366 * perform read or write I/O on it and/or otherwise manipulate the page, 367 * but if the page is held the VM system will leave the page and its data 368 * intact and not reuse the page for other purposes until the last hold 369 * reference is released. (see vm_page_wire() if you want to prevent the 370 * page from being disassociated from its object too). 371 * 372 * The caller must hold vm_token. 373 * 374 * The caller must still validate the contents of the page and, if necessary, 375 * wait for any pending I/O (e.g. vm_page_sleep_busy() loop) to complete 376 * before manipulating the page. 377 */ 378 void 379 vm_page_hold(vm_page_t m) 380 { 381 ASSERT_LWKT_TOKEN_HELD(&vm_token); 382 ++m->hold_count; 383 } 384 385 /* 386 * The opposite of vm_page_hold(). A page can be freed while being held, 387 * which places it on the PQ_HOLD queue. We must call vm_page_free_toq() 388 * in this case to actually free it once the hold count drops to 0. 389 * 390 * The caller must hold vm_token if non-blocking operation is desired, 391 * but otherwise does not need to. 392 */ 393 void 394 vm_page_unhold(vm_page_t m) 395 { 396 lwkt_gettoken(&vm_token); 397 --m->hold_count; 398 KASSERT(m->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); 399 if (m->hold_count == 0 && m->queue == PQ_HOLD) { 400 vm_page_busy(m); 401 vm_page_free_toq(m); 402 } 403 lwkt_reltoken(&vm_token); 404 } 405 406 /* 407 * Inserts the given vm_page into the object and object list. 408 * 409 * The pagetables are not updated but will presumably fault the page 410 * in if necessary, or if a kernel page the caller will at some point 411 * enter the page into the kernel's pmap. We are not allowed to block 412 * here so we *can't* do this anyway. 413 * 414 * This routine may not block. 415 * This routine must be called with the vm_token held. 416 * This routine must be called with a critical section held. 417 */ 418 void 419 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) 420 { 421 ASSERT_IN_CRIT_SECTION(); 422 ASSERT_LWKT_TOKEN_HELD(&vm_token); 423 if (m->object != NULL) 424 panic("vm_page_insert: already inserted"); 425 426 /* 427 * Record the object/offset pair in this page 428 */ 429 m->object = object; 430 m->pindex = pindex; 431 432 /* 433 * Insert it into the object. 434 */ 435 vm_page_rb_tree_RB_INSERT(&object->rb_memq, m); 436 object->generation++; 437 438 /* 439 * show that the object has one more resident page. 440 */ 441 object->resident_page_count++; 442 443 /* 444 * Add the pv_list_cout of the page when its inserted in 445 * the object 446 */ 447 object->agg_pv_list_count = object->agg_pv_list_count + m->md.pv_list_count; 448 449 /* 450 * Since we are inserting a new and possibly dirty page, 451 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags. 452 */ 453 if ((m->valid & m->dirty) || (m->flags & PG_WRITEABLE)) 454 vm_object_set_writeable_dirty(object); 455 456 /* 457 * Checks for a swap assignment and sets PG_SWAPPED if appropriate. 458 */ 459 swap_pager_page_inserted(m); 460 } 461 462 /* 463 * Removes the given vm_page_t from the global (object,index) hash table 464 * and from the object's memq. 465 * 466 * The underlying pmap entry (if any) is NOT removed here. 467 * This routine may not block. 468 * 469 * The page must be BUSY and will remain BUSY on return. 470 * No other requirements. 471 * 472 * NOTE: FreeBSD side effect was to unbusy the page on return. We leave 473 * it busy. 474 */ 475 void 476 vm_page_remove(vm_page_t m) 477 { 478 vm_object_t object; 479 480 crit_enter(); 481 lwkt_gettoken(&vm_token); 482 if (m->object == NULL) { 483 lwkt_reltoken(&vm_token); 484 crit_exit(); 485 return; 486 } 487 488 if ((m->flags & PG_BUSY) == 0) 489 panic("vm_page_remove: page not busy"); 490 491 object = m->object; 492 493 /* 494 * Remove the page from the object and update the object. 495 */ 496 vm_page_rb_tree_RB_REMOVE(&object->rb_memq, m); 497 object->resident_page_count--; 498 object->agg_pv_list_count = object->agg_pv_list_count - m->md.pv_list_count; 499 object->generation++; 500 m->object = NULL; 501 502 lwkt_reltoken(&vm_token); 503 crit_exit(); 504 } 505 506 /* 507 * Locate and return the page at (object, pindex), or NULL if the 508 * page could not be found. 509 * 510 * The caller must hold vm_token. 511 */ 512 vm_page_t 513 vm_page_lookup(vm_object_t object, vm_pindex_t pindex) 514 { 515 vm_page_t m; 516 517 /* 518 * Search the hash table for this object/offset pair 519 */ 520 ASSERT_LWKT_TOKEN_HELD(&vm_token); 521 crit_enter(); 522 m = vm_page_rb_tree_RB_LOOKUP(&object->rb_memq, pindex); 523 crit_exit(); 524 KKASSERT(m == NULL || (m->object == object && m->pindex == pindex)); 525 return(m); 526 } 527 528 /* 529 * vm_page_rename() 530 * 531 * Move the given memory entry from its current object to the specified 532 * target object/offset. 533 * 534 * The object must be locked. 535 * This routine may not block. 536 * 537 * Note: This routine will raise itself to splvm(), the caller need not. 538 * 539 * Note: Swap associated with the page must be invalidated by the move. We 540 * have to do this for several reasons: (1) we aren't freeing the 541 * page, (2) we are dirtying the page, (3) the VM system is probably 542 * moving the page from object A to B, and will then later move 543 * the backing store from A to B and we can't have a conflict. 544 * 545 * Note: We *always* dirty the page. It is necessary both for the 546 * fact that we moved it, and because we may be invalidating 547 * swap. If the page is on the cache, we have to deactivate it 548 * or vm_page_dirty() will panic. Dirty pages are not allowed 549 * on the cache. 550 */ 551 void 552 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) 553 { 554 crit_enter(); 555 lwkt_gettoken(&vm_token); 556 vm_page_remove(m); 557 vm_page_insert(m, new_object, new_pindex); 558 if (m->queue - m->pc == PQ_CACHE) 559 vm_page_deactivate(m); 560 vm_page_dirty(m); 561 vm_page_wakeup(m); 562 lwkt_reltoken(&vm_token); 563 crit_exit(); 564 } 565 566 /* 567 * vm_page_unqueue() without any wakeup. This routine is used when a page 568 * is being moved between queues or otherwise is to remain BUSYied by the 569 * caller. 570 * 571 * The caller must hold vm_token 572 * This routine may not block. 573 */ 574 void 575 vm_page_unqueue_nowakeup(vm_page_t m) 576 { 577 int queue = m->queue; 578 struct vpgqueues *pq; 579 580 ASSERT_LWKT_TOKEN_HELD(&vm_token); 581 if (queue != PQ_NONE) { 582 pq = &vm_page_queues[queue]; 583 m->queue = PQ_NONE; 584 TAILQ_REMOVE(&pq->pl, m, pageq); 585 (*pq->cnt)--; 586 pq->lcnt--; 587 } 588 } 589 590 /* 591 * vm_page_unqueue() - Remove a page from its queue, wakeup the pagedemon 592 * if necessary. 593 * 594 * The caller must hold vm_token 595 * This routine may not block. 596 */ 597 void 598 vm_page_unqueue(vm_page_t m) 599 { 600 int queue = m->queue; 601 struct vpgqueues *pq; 602 603 ASSERT_LWKT_TOKEN_HELD(&vm_token); 604 if (queue != PQ_NONE) { 605 m->queue = PQ_NONE; 606 pq = &vm_page_queues[queue]; 607 TAILQ_REMOVE(&pq->pl, m, pageq); 608 (*pq->cnt)--; 609 pq->lcnt--; 610 if ((queue - m->pc) == PQ_CACHE || (queue - m->pc) == PQ_FREE) 611 pagedaemon_wakeup(); 612 } 613 } 614 615 /* 616 * vm_page_list_find() 617 * 618 * Find a page on the specified queue with color optimization. 619 * 620 * The page coloring optimization attempts to locate a page that does 621 * not overload other nearby pages in the object in the cpu's L1 or L2 622 * caches. We need this optimization because cpu caches tend to be 623 * physical caches, while object spaces tend to be virtual. 624 * 625 * Must be called with vm_token held. 626 * This routine may not block. 627 * 628 * Note that this routine is carefully inlined. A non-inlined version 629 * is available for outside callers but the only critical path is 630 * from within this source file. 631 */ 632 static __inline 633 vm_page_t 634 _vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 635 { 636 vm_page_t m; 637 638 if (prefer_zero) 639 m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist); 640 else 641 m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl); 642 if (m == NULL) 643 m = _vm_page_list_find2(basequeue, index); 644 return(m); 645 } 646 647 static vm_page_t 648 _vm_page_list_find2(int basequeue, int index) 649 { 650 int i; 651 vm_page_t m = NULL; 652 struct vpgqueues *pq; 653 654 pq = &vm_page_queues[basequeue]; 655 656 /* 657 * Note that for the first loop, index+i and index-i wind up at the 658 * same place. Even though this is not totally optimal, we've already 659 * blown it by missing the cache case so we do not care. 660 */ 661 662 for(i = PQ_L2_SIZE / 2; i > 0; --i) { 663 if ((m = TAILQ_FIRST(&pq[(index + i) & PQ_L2_MASK].pl)) != NULL) 664 break; 665 666 if ((m = TAILQ_FIRST(&pq[(index - i) & PQ_L2_MASK].pl)) != NULL) 667 break; 668 } 669 return(m); 670 } 671 672 /* 673 * Must be called with vm_token held if the caller desired non-blocking 674 * operation and a stable result. 675 */ 676 vm_page_t 677 vm_page_list_find(int basequeue, int index, boolean_t prefer_zero) 678 { 679 return(_vm_page_list_find(basequeue, index, prefer_zero)); 680 } 681 682 /* 683 * Find a page on the cache queue with color optimization. As pages 684 * might be found, but not applicable, they are deactivated. This 685 * keeps us from using potentially busy cached pages. 686 * 687 * This routine may not block. 688 * Must be called with vm_token held. 689 */ 690 vm_page_t 691 vm_page_select_cache(vm_object_t object, vm_pindex_t pindex) 692 { 693 vm_page_t m; 694 695 ASSERT_LWKT_TOKEN_HELD(&vm_token); 696 while (TRUE) { 697 m = _vm_page_list_find( 698 PQ_CACHE, 699 (pindex + object->pg_color) & PQ_L2_MASK, 700 FALSE 701 ); 702 if (m && ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 703 m->hold_count || m->wire_count)) { 704 vm_page_deactivate(m); 705 continue; 706 } 707 return m; 708 } 709 /* not reached */ 710 } 711 712 /* 713 * Find a free or zero page, with specified preference. We attempt to 714 * inline the nominal case and fall back to _vm_page_select_free() 715 * otherwise. 716 * 717 * This routine must be called with a critical section held. 718 * This routine may not block. 719 */ 720 static __inline vm_page_t 721 vm_page_select_free(vm_object_t object, vm_pindex_t pindex, boolean_t prefer_zero) 722 { 723 vm_page_t m; 724 725 m = _vm_page_list_find( 726 PQ_FREE, 727 (pindex + object->pg_color) & PQ_L2_MASK, 728 prefer_zero 729 ); 730 return(m); 731 } 732 733 /* 734 * vm_page_alloc() 735 * 736 * Allocate and return a memory cell associated with this VM object/offset 737 * pair. 738 * 739 * page_req classes: 740 * 741 * VM_ALLOC_NORMAL allow use of cache pages, nominal free drain 742 * VM_ALLOC_QUICK like normal but cannot use cache 743 * VM_ALLOC_SYSTEM greater free drain 744 * VM_ALLOC_INTERRUPT allow free list to be completely drained 745 * VM_ALLOC_ZERO advisory request for pre-zero'd page 746 * 747 * The object must be locked. 748 * This routine may not block. 749 * The returned page will be marked PG_BUSY 750 * 751 * Additional special handling is required when called from an interrupt 752 * (VM_ALLOC_INTERRUPT). We are not allowed to mess with the page cache 753 * in this case. 754 */ 755 vm_page_t 756 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int page_req) 757 { 758 vm_page_t m = NULL; 759 760 crit_enter(); 761 lwkt_gettoken(&vm_token); 762 763 KKASSERT(object != NULL); 764 KASSERT(!vm_page_lookup(object, pindex), 765 ("vm_page_alloc: page already allocated")); 766 KKASSERT(page_req & 767 (VM_ALLOC_NORMAL|VM_ALLOC_QUICK| 768 VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 769 770 /* 771 * Certain system threads (pageout daemon, buf_daemon's) are 772 * allowed to eat deeper into the free page list. 773 */ 774 if (curthread->td_flags & TDF_SYSTHREAD) 775 page_req |= VM_ALLOC_SYSTEM; 776 777 loop: 778 if (vmstats.v_free_count > vmstats.v_free_reserved || 779 ((page_req & VM_ALLOC_INTERRUPT) && vmstats.v_free_count > 0) || 780 ((page_req & VM_ALLOC_SYSTEM) && vmstats.v_cache_count == 0 && 781 vmstats.v_free_count > vmstats.v_interrupt_free_min) 782 ) { 783 /* 784 * The free queue has sufficient free pages to take one out. 785 */ 786 if (page_req & VM_ALLOC_ZERO) 787 m = vm_page_select_free(object, pindex, TRUE); 788 else 789 m = vm_page_select_free(object, pindex, FALSE); 790 } else if (page_req & VM_ALLOC_NORMAL) { 791 /* 792 * Allocatable from the cache (non-interrupt only). On 793 * success, we must free the page and try again, thus 794 * ensuring that vmstats.v_*_free_min counters are replenished. 795 */ 796 #ifdef INVARIANTS 797 if (curthread->td_preempted) { 798 kprintf("vm_page_alloc(): warning, attempt to allocate" 799 " cache page from preempting interrupt\n"); 800 m = NULL; 801 } else { 802 m = vm_page_select_cache(object, pindex); 803 } 804 #else 805 m = vm_page_select_cache(object, pindex); 806 #endif 807 /* 808 * On success move the page into the free queue and loop. 809 */ 810 if (m != NULL) { 811 KASSERT(m->dirty == 0, 812 ("Found dirty cache page %p", m)); 813 vm_page_busy(m); 814 vm_page_protect(m, VM_PROT_NONE); 815 vm_page_free(m); 816 goto loop; 817 } 818 819 /* 820 * On failure return NULL 821 */ 822 lwkt_reltoken(&vm_token); 823 crit_exit(); 824 #if defined(DIAGNOSTIC) 825 if (vmstats.v_cache_count > 0) 826 kprintf("vm_page_alloc(NORMAL): missing pages on cache queue: %d\n", vmstats.v_cache_count); 827 #endif 828 vm_pageout_deficit++; 829 pagedaemon_wakeup(); 830 return (NULL); 831 } else { 832 /* 833 * No pages available, wakeup the pageout daemon and give up. 834 */ 835 lwkt_reltoken(&vm_token); 836 crit_exit(); 837 vm_pageout_deficit++; 838 pagedaemon_wakeup(); 839 return (NULL); 840 } 841 842 /* 843 * Good page found. The page has not yet been busied. We are in 844 * a critical section. 845 */ 846 KASSERT(m != NULL, ("vm_page_alloc(): missing page on free queue\n")); 847 KASSERT(m->dirty == 0, 848 ("vm_page_alloc: free/cache page %p was dirty", m)); 849 850 /* 851 * Remove from free queue 852 */ 853 vm_page_unqueue_nowakeup(m); 854 855 /* 856 * Initialize structure. Only the PG_ZERO flag is inherited. Set 857 * the page PG_BUSY 858 */ 859 if (m->flags & PG_ZERO) { 860 vm_page_zero_count--; 861 m->flags = PG_ZERO | PG_BUSY; 862 } else { 863 m->flags = PG_BUSY; 864 } 865 m->wire_count = 0; 866 m->hold_count = 0; 867 m->act_count = 0; 868 m->busy = 0; 869 m->valid = 0; 870 871 /* 872 * vm_page_insert() is safe prior to the crit_exit(). Note also that 873 * inserting a page here does not insert it into the pmap (which 874 * could cause us to block allocating memory). We cannot block 875 * anywhere. 876 */ 877 vm_page_insert(m, object, pindex); 878 879 /* 880 * Don't wakeup too often - wakeup the pageout daemon when 881 * we would be nearly out of memory. 882 */ 883 pagedaemon_wakeup(); 884 885 lwkt_reltoken(&vm_token); 886 crit_exit(); 887 888 /* 889 * A PG_BUSY page is returned. 890 */ 891 return (m); 892 } 893 894 /* 895 * Wait for sufficient free memory for nominal heavy memory use kernel 896 * operations. 897 */ 898 void 899 vm_wait_nominal(void) 900 { 901 while (vm_page_count_min(0)) 902 vm_wait(0); 903 } 904 905 /* 906 * Test if vm_wait_nominal() would block. 907 */ 908 int 909 vm_test_nominal(void) 910 { 911 if (vm_page_count_min(0)) 912 return(1); 913 return(0); 914 } 915 916 /* 917 * Block until free pages are available for allocation, called in various 918 * places before memory allocations. 919 */ 920 void 921 vm_wait(int timo) 922 { 923 crit_enter(); 924 lwkt_gettoken(&vm_token); 925 if (curthread == pagethread) { 926 vm_pageout_pages_needed = 1; 927 tsleep(&vm_pageout_pages_needed, 0, "VMWait", timo); 928 } else { 929 if (vm_pages_needed == 0) { 930 vm_pages_needed = 1; 931 wakeup(&vm_pages_needed); 932 } 933 tsleep(&vmstats.v_free_count, 0, "vmwait", timo); 934 } 935 lwkt_reltoken(&vm_token); 936 crit_exit(); 937 } 938 939 /* 940 * Block until free pages are available for allocation 941 * 942 * Called only in vm_fault so that processes page faulting can be 943 * easily tracked. 944 */ 945 void 946 vm_waitpfault(void) 947 { 948 crit_enter(); 949 lwkt_gettoken(&vm_token); 950 if (vm_pages_needed == 0) { 951 vm_pages_needed = 1; 952 wakeup(&vm_pages_needed); 953 } 954 tsleep(&vmstats.v_free_count, 0, "pfault", 0); 955 lwkt_reltoken(&vm_token); 956 crit_exit(); 957 } 958 959 /* 960 * Put the specified page on the active list (if appropriate). Ensure 961 * that act_count is at least ACT_INIT but do not otherwise mess with it. 962 * 963 * The page queues must be locked. 964 * This routine may not block. 965 */ 966 void 967 vm_page_activate(vm_page_t m) 968 { 969 crit_enter(); 970 lwkt_gettoken(&vm_token); 971 if (m->queue != PQ_ACTIVE) { 972 if ((m->queue - m->pc) == PQ_CACHE) 973 mycpu->gd_cnt.v_reactivated++; 974 975 vm_page_unqueue(m); 976 977 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 978 m->queue = PQ_ACTIVE; 979 vm_page_queues[PQ_ACTIVE].lcnt++; 980 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, 981 m, pageq); 982 if (m->act_count < ACT_INIT) 983 m->act_count = ACT_INIT; 984 vmstats.v_active_count++; 985 } 986 } else { 987 if (m->act_count < ACT_INIT) 988 m->act_count = ACT_INIT; 989 } 990 lwkt_reltoken(&vm_token); 991 crit_exit(); 992 } 993 994 /* 995 * Helper routine for vm_page_free_toq() and vm_page_cache(). This 996 * routine is called when a page has been added to the cache or free 997 * queues. 998 * 999 * This routine may not block. 1000 * This routine must be called at splvm() 1001 */ 1002 static __inline void 1003 vm_page_free_wakeup(void) 1004 { 1005 /* 1006 * if pageout daemon needs pages, then tell it that there are 1007 * some free. 1008 */ 1009 if (vm_pageout_pages_needed && 1010 vmstats.v_cache_count + vmstats.v_free_count >= 1011 vmstats.v_pageout_free_min 1012 ) { 1013 wakeup(&vm_pageout_pages_needed); 1014 vm_pageout_pages_needed = 0; 1015 } 1016 1017 /* 1018 * wakeup processes that are waiting on memory if we hit a 1019 * high water mark. And wakeup scheduler process if we have 1020 * lots of memory. this process will swapin processes. 1021 */ 1022 if (vm_pages_needed && !vm_page_count_min(0)) { 1023 vm_pages_needed = 0; 1024 wakeup(&vmstats.v_free_count); 1025 } 1026 } 1027 1028 /* 1029 * vm_page_free_toq: 1030 * 1031 * Returns the given page to the PQ_FREE list, disassociating it with 1032 * any VM object. 1033 * 1034 * The vm_page must be PG_BUSY on entry. PG_BUSY will be released on 1035 * return (the page will have been freed). No particular spl is required 1036 * on entry. 1037 * 1038 * This routine may not block. 1039 */ 1040 void 1041 vm_page_free_toq(vm_page_t m) 1042 { 1043 struct vpgqueues *pq; 1044 1045 crit_enter(); 1046 lwkt_gettoken(&vm_token); 1047 mycpu->gd_cnt.v_tfree++; 1048 1049 KKASSERT((m->flags & PG_MAPPED) == 0); 1050 1051 if (m->busy || ((m->queue - m->pc) == PQ_FREE)) { 1052 kprintf( 1053 "vm_page_free: pindex(%lu), busy(%d), PG_BUSY(%d), hold(%d)\n", 1054 (u_long)m->pindex, m->busy, (m->flags & PG_BUSY) ? 1 : 0, 1055 m->hold_count); 1056 if ((m->queue - m->pc) == PQ_FREE) 1057 panic("vm_page_free: freeing free page"); 1058 else 1059 panic("vm_page_free: freeing busy page"); 1060 } 1061 1062 /* 1063 * unqueue, then remove page. Note that we cannot destroy 1064 * the page here because we do not want to call the pager's 1065 * callback routine until after we've put the page on the 1066 * appropriate free queue. 1067 */ 1068 vm_page_unqueue_nowakeup(m); 1069 vm_page_remove(m); 1070 1071 /* 1072 * No further management of fictitious pages occurs beyond object 1073 * and queue removal. 1074 */ 1075 if ((m->flags & PG_FICTITIOUS) != 0) { 1076 vm_page_wakeup(m); 1077 lwkt_reltoken(&vm_token); 1078 crit_exit(); 1079 return; 1080 } 1081 1082 m->valid = 0; 1083 vm_page_undirty(m); 1084 1085 if (m->wire_count != 0) { 1086 if (m->wire_count > 1) { 1087 panic( 1088 "vm_page_free: invalid wire count (%d), pindex: 0x%lx", 1089 m->wire_count, (long)m->pindex); 1090 } 1091 panic("vm_page_free: freeing wired page"); 1092 } 1093 1094 /* 1095 * Clear the UNMANAGED flag when freeing an unmanaged page. 1096 */ 1097 if (m->flags & PG_UNMANAGED) { 1098 m->flags &= ~PG_UNMANAGED; 1099 } 1100 1101 if (m->hold_count != 0) { 1102 m->flags &= ~PG_ZERO; 1103 m->queue = PQ_HOLD; 1104 } else { 1105 m->queue = PQ_FREE + m->pc; 1106 } 1107 pq = &vm_page_queues[m->queue]; 1108 pq->lcnt++; 1109 ++(*pq->cnt); 1110 1111 /* 1112 * Put zero'd pages on the end ( where we look for zero'd pages 1113 * first ) and non-zerod pages at the head. 1114 */ 1115 if (m->flags & PG_ZERO) { 1116 TAILQ_INSERT_TAIL(&pq->pl, m, pageq); 1117 ++vm_page_zero_count; 1118 } else { 1119 TAILQ_INSERT_HEAD(&pq->pl, m, pageq); 1120 } 1121 vm_page_wakeup(m); 1122 vm_page_free_wakeup(); 1123 lwkt_reltoken(&vm_token); 1124 crit_exit(); 1125 } 1126 1127 /* 1128 * vm_page_free_fromq_fast() 1129 * 1130 * Remove a non-zero page from one of the free queues; the page is removed for 1131 * zeroing, so do not issue a wakeup. 1132 * 1133 * MPUNSAFE 1134 */ 1135 vm_page_t 1136 vm_page_free_fromq_fast(void) 1137 { 1138 static int qi; 1139 vm_page_t m; 1140 int i; 1141 1142 crit_enter(); 1143 lwkt_gettoken(&vm_token); 1144 for (i = 0; i < PQ_L2_SIZE; ++i) { 1145 m = vm_page_list_find(PQ_FREE, qi, FALSE); 1146 qi = (qi + PQ_PRIME2) & PQ_L2_MASK; 1147 if (m && (m->flags & PG_ZERO) == 0) { 1148 vm_page_unqueue_nowakeup(m); 1149 vm_page_busy(m); 1150 break; 1151 } 1152 m = NULL; 1153 } 1154 lwkt_reltoken(&vm_token); 1155 crit_exit(); 1156 return (m); 1157 } 1158 1159 /* 1160 * vm_page_unmanage() 1161 * 1162 * Prevent PV management from being done on the page. The page is 1163 * removed from the paging queues as if it were wired, and as a 1164 * consequence of no longer being managed the pageout daemon will not 1165 * touch it (since there is no way to locate the pte mappings for the 1166 * page). madvise() calls that mess with the pmap will also no longer 1167 * operate on the page. 1168 * 1169 * Beyond that the page is still reasonably 'normal'. Freeing the page 1170 * will clear the flag. 1171 * 1172 * This routine is used by OBJT_PHYS objects - objects using unswappable 1173 * physical memory as backing store rather then swap-backed memory and 1174 * will eventually be extended to support 4MB unmanaged physical 1175 * mappings. 1176 * 1177 * Must be called with a critical section held. 1178 * Must be called with vm_token held. 1179 */ 1180 void 1181 vm_page_unmanage(vm_page_t m) 1182 { 1183 ASSERT_IN_CRIT_SECTION(); 1184 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1185 if ((m->flags & PG_UNMANAGED) == 0) { 1186 if (m->wire_count == 0) 1187 vm_page_unqueue(m); 1188 } 1189 vm_page_flag_set(m, PG_UNMANAGED); 1190 } 1191 1192 /* 1193 * Mark this page as wired down by yet another map, removing it from 1194 * paging queues as necessary. 1195 * 1196 * The page queues must be locked. 1197 * This routine may not block. 1198 */ 1199 void 1200 vm_page_wire(vm_page_t m) 1201 { 1202 /* 1203 * Only bump the wire statistics if the page is not already wired, 1204 * and only unqueue the page if it is on some queue (if it is unmanaged 1205 * it is already off the queues). Don't do anything with fictitious 1206 * pages because they are always wired. 1207 */ 1208 crit_enter(); 1209 lwkt_gettoken(&vm_token); 1210 if ((m->flags & PG_FICTITIOUS) == 0) { 1211 if (m->wire_count == 0) { 1212 if ((m->flags & PG_UNMANAGED) == 0) 1213 vm_page_unqueue(m); 1214 vmstats.v_wire_count++; 1215 } 1216 m->wire_count++; 1217 KASSERT(m->wire_count != 0, 1218 ("vm_page_wire: wire_count overflow m=%p", m)); 1219 } 1220 lwkt_reltoken(&vm_token); 1221 crit_exit(); 1222 } 1223 1224 /* 1225 * Release one wiring of this page, potentially enabling it to be paged again. 1226 * 1227 * Many pages placed on the inactive queue should actually go 1228 * into the cache, but it is difficult to figure out which. What 1229 * we do instead, if the inactive target is well met, is to put 1230 * clean pages at the head of the inactive queue instead of the tail. 1231 * This will cause them to be moved to the cache more quickly and 1232 * if not actively re-referenced, freed more quickly. If we just 1233 * stick these pages at the end of the inactive queue, heavy filesystem 1234 * meta-data accesses can cause an unnecessary paging load on memory bound 1235 * processes. This optimization causes one-time-use metadata to be 1236 * reused more quickly. 1237 * 1238 * BUT, if we are in a low-memory situation we have no choice but to 1239 * put clean pages on the cache queue. 1240 * 1241 * A number of routines use vm_page_unwire() to guarantee that the page 1242 * will go into either the inactive or active queues, and will NEVER 1243 * be placed in the cache - for example, just after dirtying a page. 1244 * dirty pages in the cache are not allowed. 1245 * 1246 * The page queues must be locked. 1247 * This routine may not block. 1248 */ 1249 void 1250 vm_page_unwire(vm_page_t m, int activate) 1251 { 1252 crit_enter(); 1253 lwkt_gettoken(&vm_token); 1254 if (m->flags & PG_FICTITIOUS) { 1255 /* do nothing */ 1256 } else if (m->wire_count <= 0) { 1257 panic("vm_page_unwire: invalid wire count: %d", m->wire_count); 1258 } else { 1259 if (--m->wire_count == 0) { 1260 --vmstats.v_wire_count; 1261 if (m->flags & PG_UNMANAGED) { 1262 ; 1263 } else if (activate) { 1264 TAILQ_INSERT_TAIL( 1265 &vm_page_queues[PQ_ACTIVE].pl, m, pageq); 1266 m->queue = PQ_ACTIVE; 1267 vm_page_queues[PQ_ACTIVE].lcnt++; 1268 vmstats.v_active_count++; 1269 } else { 1270 vm_page_flag_clear(m, PG_WINATCFLS); 1271 TAILQ_INSERT_TAIL( 1272 &vm_page_queues[PQ_INACTIVE].pl, m, pageq); 1273 m->queue = PQ_INACTIVE; 1274 vm_page_queues[PQ_INACTIVE].lcnt++; 1275 vmstats.v_inactive_count++; 1276 ++vm_swapcache_inactive_heuristic; 1277 } 1278 } 1279 } 1280 lwkt_reltoken(&vm_token); 1281 crit_exit(); 1282 } 1283 1284 1285 /* 1286 * Move the specified page to the inactive queue. If the page has 1287 * any associated swap, the swap is deallocated. 1288 * 1289 * Normally athead is 0 resulting in LRU operation. athead is set 1290 * to 1 if we want this page to be 'as if it were placed in the cache', 1291 * except without unmapping it from the process address space. 1292 * 1293 * This routine may not block. 1294 * The caller must hold vm_token. 1295 */ 1296 static __inline void 1297 _vm_page_deactivate(vm_page_t m, int athead) 1298 { 1299 /* 1300 * Ignore if already inactive. 1301 */ 1302 if (m->queue == PQ_INACTIVE) 1303 return; 1304 1305 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { 1306 if ((m->queue - m->pc) == PQ_CACHE) 1307 mycpu->gd_cnt.v_reactivated++; 1308 vm_page_flag_clear(m, PG_WINATCFLS); 1309 vm_page_unqueue(m); 1310 if (athead) { 1311 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, 1312 m, pageq); 1313 } else { 1314 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, 1315 m, pageq); 1316 ++vm_swapcache_inactive_heuristic; 1317 } 1318 m->queue = PQ_INACTIVE; 1319 vm_page_queues[PQ_INACTIVE].lcnt++; 1320 vmstats.v_inactive_count++; 1321 } 1322 } 1323 1324 /* 1325 * Attempt to deactivate a page. 1326 * 1327 * No requirements. 1328 */ 1329 void 1330 vm_page_deactivate(vm_page_t m) 1331 { 1332 crit_enter(); 1333 lwkt_gettoken(&vm_token); 1334 _vm_page_deactivate(m, 0); 1335 lwkt_reltoken(&vm_token); 1336 crit_exit(); 1337 } 1338 1339 /* 1340 * Attempt to move a page to PQ_CACHE. 1341 * Returns 0 on failure, 1 on success 1342 * 1343 * No requirements. 1344 */ 1345 int 1346 vm_page_try_to_cache(vm_page_t m) 1347 { 1348 crit_enter(); 1349 lwkt_gettoken(&vm_token); 1350 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1351 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1352 lwkt_reltoken(&vm_token); 1353 crit_exit(); 1354 return(0); 1355 } 1356 vm_page_test_dirty(m); 1357 if (m->dirty) { 1358 lwkt_reltoken(&vm_token); 1359 crit_exit(); 1360 return(0); 1361 } 1362 vm_page_cache(m); 1363 lwkt_reltoken(&vm_token); 1364 crit_exit(); 1365 return(1); 1366 } 1367 1368 /* 1369 * Attempt to free the page. If we cannot free it, we do nothing. 1370 * 1 is returned on success, 0 on failure. 1371 * 1372 * No requirements. 1373 */ 1374 int 1375 vm_page_try_to_free(vm_page_t m) 1376 { 1377 crit_enter(); 1378 lwkt_gettoken(&vm_token); 1379 if (m->dirty || m->hold_count || m->busy || m->wire_count || 1380 (m->flags & (PG_BUSY|PG_UNMANAGED))) { 1381 lwkt_reltoken(&vm_token); 1382 crit_exit(); 1383 return(0); 1384 } 1385 vm_page_test_dirty(m); 1386 if (m->dirty) { 1387 lwkt_reltoken(&vm_token); 1388 crit_exit(); 1389 return(0); 1390 } 1391 vm_page_busy(m); 1392 vm_page_protect(m, VM_PROT_NONE); 1393 vm_page_free(m); 1394 lwkt_reltoken(&vm_token); 1395 crit_exit(); 1396 return(1); 1397 } 1398 1399 /* 1400 * vm_page_cache 1401 * 1402 * Put the specified page onto the page cache queue (if appropriate). 1403 * 1404 * The caller must hold vm_token. 1405 * This routine may not block. 1406 */ 1407 void 1408 vm_page_cache(vm_page_t m) 1409 { 1410 ASSERT_IN_CRIT_SECTION(); 1411 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1412 1413 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || m->busy || 1414 m->wire_count || m->hold_count) { 1415 kprintf("vm_page_cache: attempting to cache busy/held page\n"); 1416 return; 1417 } 1418 1419 /* 1420 * Already in the cache (and thus not mapped) 1421 */ 1422 if ((m->queue - m->pc) == PQ_CACHE) { 1423 KKASSERT((m->flags & PG_MAPPED) == 0); 1424 return; 1425 } 1426 1427 /* 1428 * Caller is required to test m->dirty, but note that the act of 1429 * removing the page from its maps can cause it to become dirty 1430 * on an SMP system due to another cpu running in usermode. 1431 */ 1432 if (m->dirty) { 1433 panic("vm_page_cache: caching a dirty page, pindex: %ld", 1434 (long)m->pindex); 1435 } 1436 1437 /* 1438 * Remove all pmaps and indicate that the page is not 1439 * writeable or mapped. Our vm_page_protect() call may 1440 * have blocked (especially w/ VM_PROT_NONE), so recheck 1441 * everything. 1442 */ 1443 vm_page_busy(m); 1444 vm_page_protect(m, VM_PROT_NONE); 1445 vm_page_wakeup(m); 1446 if ((m->flags & (PG_BUSY|PG_UNMANAGED|PG_MAPPED)) || m->busy || 1447 m->wire_count || m->hold_count) { 1448 /* do nothing */ 1449 } else if (m->dirty) { 1450 vm_page_deactivate(m); 1451 } else { 1452 vm_page_unqueue_nowakeup(m); 1453 m->queue = PQ_CACHE + m->pc; 1454 vm_page_queues[m->queue].lcnt++; 1455 TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, pageq); 1456 vmstats.v_cache_count++; 1457 vm_page_free_wakeup(); 1458 } 1459 } 1460 1461 /* 1462 * vm_page_dontneed() 1463 * 1464 * Cache, deactivate, or do nothing as appropriate. This routine 1465 * is typically used by madvise() MADV_DONTNEED. 1466 * 1467 * Generally speaking we want to move the page into the cache so 1468 * it gets reused quickly. However, this can result in a silly syndrome 1469 * due to the page recycling too quickly. Small objects will not be 1470 * fully cached. On the otherhand, if we move the page to the inactive 1471 * queue we wind up with a problem whereby very large objects 1472 * unnecessarily blow away our inactive and cache queues. 1473 * 1474 * The solution is to move the pages based on a fixed weighting. We 1475 * either leave them alone, deactivate them, or move them to the cache, 1476 * where moving them to the cache has the highest weighting. 1477 * By forcing some pages into other queues we eventually force the 1478 * system to balance the queues, potentially recovering other unrelated 1479 * space from active. The idea is to not force this to happen too 1480 * often. 1481 * 1482 * No requirements. 1483 */ 1484 void 1485 vm_page_dontneed(vm_page_t m) 1486 { 1487 static int dnweight; 1488 int dnw; 1489 int head; 1490 1491 dnw = ++dnweight; 1492 1493 /* 1494 * occassionally leave the page alone 1495 */ 1496 crit_enter(); 1497 lwkt_gettoken(&vm_token); 1498 if ((dnw & 0x01F0) == 0 || 1499 m->queue == PQ_INACTIVE || 1500 m->queue - m->pc == PQ_CACHE 1501 ) { 1502 if (m->act_count >= ACT_INIT) 1503 --m->act_count; 1504 lwkt_reltoken(&vm_token); 1505 crit_exit(); 1506 return; 1507 } 1508 1509 if (m->dirty == 0) 1510 vm_page_test_dirty(m); 1511 1512 if (m->dirty || (dnw & 0x0070) == 0) { 1513 /* 1514 * Deactivate the page 3 times out of 32. 1515 */ 1516 head = 0; 1517 } else { 1518 /* 1519 * Cache the page 28 times out of every 32. Note that 1520 * the page is deactivated instead of cached, but placed 1521 * at the head of the queue instead of the tail. 1522 */ 1523 head = 1; 1524 } 1525 _vm_page_deactivate(m, head); 1526 lwkt_reltoken(&vm_token); 1527 crit_exit(); 1528 } 1529 1530 /* 1531 * Grab a page, blocking if it is busy and allocating a page if necessary. 1532 * A busy page is returned or NULL. 1533 * 1534 * If VM_ALLOC_RETRY is specified VM_ALLOC_NORMAL must also be specified. 1535 * If VM_ALLOC_RETRY is not specified 1536 * 1537 * This routine may block, but if VM_ALLOC_RETRY is not set then NULL is 1538 * always returned if we had blocked. 1539 * This routine will never return NULL if VM_ALLOC_RETRY is set. 1540 * This routine may not be called from an interrupt. 1541 * The returned page may not be entirely valid. 1542 * 1543 * This routine may be called from mainline code without spl protection and 1544 * be guarenteed a busied page associated with the object at the specified 1545 * index. 1546 * 1547 * No requirements. 1548 */ 1549 vm_page_t 1550 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) 1551 { 1552 vm_page_t m; 1553 int generation; 1554 1555 KKASSERT(allocflags & 1556 (VM_ALLOC_NORMAL|VM_ALLOC_INTERRUPT|VM_ALLOC_SYSTEM)); 1557 crit_enter(); 1558 lwkt_gettoken(&vm_token); 1559 retrylookup: 1560 if ((m = vm_page_lookup(object, pindex)) != NULL) { 1561 if (m->busy || (m->flags & PG_BUSY)) { 1562 generation = object->generation; 1563 1564 while ((object->generation == generation) && 1565 (m->busy || (m->flags & PG_BUSY))) { 1566 vm_page_flag_set(m, PG_WANTED | PG_REFERENCED); 1567 tsleep(m, 0, "pgrbwt", 0); 1568 if ((allocflags & VM_ALLOC_RETRY) == 0) { 1569 m = NULL; 1570 goto done; 1571 } 1572 } 1573 goto retrylookup; 1574 } else { 1575 vm_page_busy(m); 1576 goto done; 1577 } 1578 } 1579 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); 1580 if (m == NULL) { 1581 vm_wait(0); 1582 if ((allocflags & VM_ALLOC_RETRY) == 0) 1583 goto done; 1584 goto retrylookup; 1585 } 1586 done: 1587 lwkt_reltoken(&vm_token); 1588 crit_exit(); 1589 return(m); 1590 } 1591 1592 /* 1593 * Mapping function for valid bits or for dirty bits in 1594 * a page. May not block. 1595 * 1596 * Inputs are required to range within a page. 1597 * 1598 * No requirements. 1599 * Non blocking. 1600 */ 1601 int 1602 vm_page_bits(int base, int size) 1603 { 1604 int first_bit; 1605 int last_bit; 1606 1607 KASSERT( 1608 base + size <= PAGE_SIZE, 1609 ("vm_page_bits: illegal base/size %d/%d", base, size) 1610 ); 1611 1612 if (size == 0) /* handle degenerate case */ 1613 return(0); 1614 1615 first_bit = base >> DEV_BSHIFT; 1616 last_bit = (base + size - 1) >> DEV_BSHIFT; 1617 1618 return ((2 << last_bit) - (1 << first_bit)); 1619 } 1620 1621 /* 1622 * Sets portions of a page valid and clean. The arguments are expected 1623 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive 1624 * of any partial chunks touched by the range. The invalid portion of 1625 * such chunks will be zero'd. 1626 * 1627 * NOTE: When truncating a buffer vnode_pager_setsize() will automatically 1628 * align base to DEV_BSIZE so as not to mark clean a partially 1629 * truncated device block. Otherwise the dirty page status might be 1630 * lost. 1631 * 1632 * This routine may not block. 1633 * 1634 * (base + size) must be less then or equal to PAGE_SIZE. 1635 */ 1636 static void 1637 _vm_page_zero_valid(vm_page_t m, int base, int size) 1638 { 1639 int frag; 1640 int endoff; 1641 1642 if (size == 0) /* handle degenerate case */ 1643 return; 1644 1645 /* 1646 * If the base is not DEV_BSIZE aligned and the valid 1647 * bit is clear, we have to zero out a portion of the 1648 * first block. 1649 */ 1650 1651 if ((frag = base & ~(DEV_BSIZE - 1)) != base && 1652 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0 1653 ) { 1654 pmap_zero_page_area( 1655 VM_PAGE_TO_PHYS(m), 1656 frag, 1657 base - frag 1658 ); 1659 } 1660 1661 /* 1662 * If the ending offset is not DEV_BSIZE aligned and the 1663 * valid bit is clear, we have to zero out a portion of 1664 * the last block. 1665 */ 1666 1667 endoff = base + size; 1668 1669 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && 1670 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0 1671 ) { 1672 pmap_zero_page_area( 1673 VM_PAGE_TO_PHYS(m), 1674 endoff, 1675 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)) 1676 ); 1677 } 1678 } 1679 1680 /* 1681 * Set valid, clear dirty bits. If validating the entire 1682 * page we can safely clear the pmap modify bit. We also 1683 * use this opportunity to clear the PG_NOSYNC flag. If a process 1684 * takes a write fault on a MAP_NOSYNC memory area the flag will 1685 * be set again. 1686 * 1687 * We set valid bits inclusive of any overlap, but we can only 1688 * clear dirty bits for DEV_BSIZE chunks that are fully within 1689 * the range. 1690 * 1691 * Page must be busied? 1692 * No other requirements. 1693 */ 1694 void 1695 vm_page_set_valid(vm_page_t m, int base, int size) 1696 { 1697 _vm_page_zero_valid(m, base, size); 1698 m->valid |= vm_page_bits(base, size); 1699 } 1700 1701 1702 /* 1703 * Set valid bits and clear dirty bits. 1704 * 1705 * NOTE: This function does not clear the pmap modified bit. 1706 * Also note that e.g. NFS may use a byte-granular base 1707 * and size. 1708 * 1709 * Page must be busied? 1710 * No other requirements. 1711 */ 1712 void 1713 vm_page_set_validclean(vm_page_t m, int base, int size) 1714 { 1715 int pagebits; 1716 1717 _vm_page_zero_valid(m, base, size); 1718 pagebits = vm_page_bits(base, size); 1719 m->valid |= pagebits; 1720 m->dirty &= ~pagebits; 1721 if (base == 0 && size == PAGE_SIZE) { 1722 /*pmap_clear_modify(m);*/ 1723 vm_page_flag_clear(m, PG_NOSYNC); 1724 } 1725 } 1726 1727 /* 1728 * Set valid & dirty. Used by buwrite() 1729 * 1730 * Page must be busied? 1731 * No other requirements. 1732 */ 1733 void 1734 vm_page_set_validdirty(vm_page_t m, int base, int size) 1735 { 1736 int pagebits; 1737 1738 pagebits = vm_page_bits(base, size); 1739 m->valid |= pagebits; 1740 m->dirty |= pagebits; 1741 if (m->object) 1742 vm_object_set_writeable_dirty(m->object); 1743 } 1744 1745 /* 1746 * Clear dirty bits. 1747 * 1748 * NOTE: This function does not clear the pmap modified bit. 1749 * Also note that e.g. NFS may use a byte-granular base 1750 * and size. 1751 * 1752 * Page must be busied? 1753 * No other requirements. 1754 */ 1755 void 1756 vm_page_clear_dirty(vm_page_t m, int base, int size) 1757 { 1758 m->dirty &= ~vm_page_bits(base, size); 1759 if (base == 0 && size == PAGE_SIZE) { 1760 /*pmap_clear_modify(m);*/ 1761 vm_page_flag_clear(m, PG_NOSYNC); 1762 } 1763 } 1764 1765 /* 1766 * Make the page all-dirty. 1767 * 1768 * Also make sure the related object and vnode reflect the fact that the 1769 * object may now contain a dirty page. 1770 * 1771 * Page must be busied? 1772 * No other requirements. 1773 */ 1774 void 1775 vm_page_dirty(vm_page_t m) 1776 { 1777 #ifdef INVARIANTS 1778 int pqtype = m->queue - m->pc; 1779 #endif 1780 KASSERT(pqtype != PQ_CACHE && pqtype != PQ_FREE, 1781 ("vm_page_dirty: page in free/cache queue!")); 1782 if (m->dirty != VM_PAGE_BITS_ALL) { 1783 m->dirty = VM_PAGE_BITS_ALL; 1784 if (m->object) 1785 vm_object_set_writeable_dirty(m->object); 1786 } 1787 } 1788 1789 /* 1790 * Invalidates DEV_BSIZE'd chunks within a page. Both the 1791 * valid and dirty bits for the effected areas are cleared. 1792 * 1793 * Page must be busied? 1794 * Does not block. 1795 * No other requirements. 1796 */ 1797 void 1798 vm_page_set_invalid(vm_page_t m, int base, int size) 1799 { 1800 int bits; 1801 1802 bits = vm_page_bits(base, size); 1803 m->valid &= ~bits; 1804 m->dirty &= ~bits; 1805 m->object->generation++; 1806 } 1807 1808 /* 1809 * The kernel assumes that the invalid portions of a page contain 1810 * garbage, but such pages can be mapped into memory by user code. 1811 * When this occurs, we must zero out the non-valid portions of the 1812 * page so user code sees what it expects. 1813 * 1814 * Pages are most often semi-valid when the end of a file is mapped 1815 * into memory and the file's size is not page aligned. 1816 * 1817 * Page must be busied? 1818 * No other requirements. 1819 */ 1820 void 1821 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) 1822 { 1823 int b; 1824 int i; 1825 1826 /* 1827 * Scan the valid bits looking for invalid sections that 1828 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the 1829 * valid bit may be set ) have already been zerod by 1830 * vm_page_set_validclean(). 1831 */ 1832 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { 1833 if (i == (PAGE_SIZE / DEV_BSIZE) || 1834 (m->valid & (1 << i)) 1835 ) { 1836 if (i > b) { 1837 pmap_zero_page_area( 1838 VM_PAGE_TO_PHYS(m), 1839 b << DEV_BSHIFT, 1840 (i - b) << DEV_BSHIFT 1841 ); 1842 } 1843 b = i + 1; 1844 } 1845 } 1846 1847 /* 1848 * setvalid is TRUE when we can safely set the zero'd areas 1849 * as being valid. We can do this if there are no cache consistency 1850 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. 1851 */ 1852 if (setvalid) 1853 m->valid = VM_PAGE_BITS_ALL; 1854 } 1855 1856 /* 1857 * Is a (partial) page valid? Note that the case where size == 0 1858 * will return FALSE in the degenerate case where the page is entirely 1859 * invalid, and TRUE otherwise. 1860 * 1861 * Does not block. 1862 * No other requirements. 1863 */ 1864 int 1865 vm_page_is_valid(vm_page_t m, int base, int size) 1866 { 1867 int bits = vm_page_bits(base, size); 1868 1869 if (m->valid && ((m->valid & bits) == bits)) 1870 return 1; 1871 else 1872 return 0; 1873 } 1874 1875 /* 1876 * update dirty bits from pmap/mmu. May not block. 1877 * 1878 * Caller must hold vm_token if non-blocking operation desired. 1879 * No other requirements. 1880 */ 1881 void 1882 vm_page_test_dirty(vm_page_t m) 1883 { 1884 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { 1885 vm_page_dirty(m); 1886 } 1887 } 1888 1889 /* 1890 * Register an action, associating it with its vm_page 1891 */ 1892 void 1893 vm_page_register_action(vm_page_action_t action, vm_page_event_t event) 1894 { 1895 struct vm_page_action_list *list; 1896 int hv; 1897 1898 hv = (int)((intptr_t)action->m >> 8) & VMACTION_HMASK; 1899 list = &action_list[hv]; 1900 1901 lwkt_gettoken(&vm_token); 1902 vm_page_flag_set(action->m, PG_ACTIONLIST); 1903 action->event = event; 1904 LIST_INSERT_HEAD(list, action, entry); 1905 lwkt_reltoken(&vm_token); 1906 } 1907 1908 /* 1909 * Unregister an action, disassociating it from its related vm_page 1910 */ 1911 void 1912 vm_page_unregister_action(vm_page_action_t action) 1913 { 1914 struct vm_page_action_list *list; 1915 int hv; 1916 1917 lwkt_gettoken(&vm_token); 1918 if (action->event != VMEVENT_NONE) { 1919 action->event = VMEVENT_NONE; 1920 LIST_REMOVE(action, entry); 1921 1922 hv = (int)((intptr_t)action->m >> 8) & VMACTION_HMASK; 1923 list = &action_list[hv]; 1924 if (LIST_EMPTY(list)) 1925 vm_page_flag_clear(action->m, PG_ACTIONLIST); 1926 } 1927 lwkt_reltoken(&vm_token); 1928 } 1929 1930 /* 1931 * Issue an event on a VM page. Corresponding action structures are 1932 * removed from the page's list and called. 1933 * 1934 * If the vm_page has no more pending action events we clear its 1935 * PG_ACTIONLIST flag. 1936 */ 1937 void 1938 vm_page_event_internal(vm_page_t m, vm_page_event_t event) 1939 { 1940 struct vm_page_action_list *list; 1941 struct vm_page_action *scan; 1942 struct vm_page_action *next; 1943 int hv; 1944 int all; 1945 1946 hv = (int)((intptr_t)m >> 8) & VMACTION_HMASK; 1947 list = &action_list[hv]; 1948 all = 1; 1949 1950 lwkt_gettoken(&vm_token); 1951 LIST_FOREACH_MUTABLE(scan, list, entry, next) { 1952 if (scan->m == m) { 1953 if (scan->event == event) { 1954 scan->event = VMEVENT_NONE; 1955 LIST_REMOVE(scan, entry); 1956 scan->func(m, scan); 1957 /* XXX */ 1958 } else { 1959 all = 0; 1960 } 1961 } 1962 } 1963 if (all) 1964 vm_page_flag_clear(m, PG_ACTIONLIST); 1965 lwkt_reltoken(&vm_token); 1966 } 1967 1968 1969 #include "opt_ddb.h" 1970 #ifdef DDB 1971 #include <sys/kernel.h> 1972 1973 #include <ddb/ddb.h> 1974 1975 DB_SHOW_COMMAND(page, vm_page_print_page_info) 1976 { 1977 db_printf("vmstats.v_free_count: %d\n", vmstats.v_free_count); 1978 db_printf("vmstats.v_cache_count: %d\n", vmstats.v_cache_count); 1979 db_printf("vmstats.v_inactive_count: %d\n", vmstats.v_inactive_count); 1980 db_printf("vmstats.v_active_count: %d\n", vmstats.v_active_count); 1981 db_printf("vmstats.v_wire_count: %d\n", vmstats.v_wire_count); 1982 db_printf("vmstats.v_free_reserved: %d\n", vmstats.v_free_reserved); 1983 db_printf("vmstats.v_free_min: %d\n", vmstats.v_free_min); 1984 db_printf("vmstats.v_free_target: %d\n", vmstats.v_free_target); 1985 db_printf("vmstats.v_cache_min: %d\n", vmstats.v_cache_min); 1986 db_printf("vmstats.v_inactive_target: %d\n", vmstats.v_inactive_target); 1987 } 1988 1989 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) 1990 { 1991 int i; 1992 db_printf("PQ_FREE:"); 1993 for(i=0;i<PQ_L2_SIZE;i++) { 1994 db_printf(" %d", vm_page_queues[PQ_FREE + i].lcnt); 1995 } 1996 db_printf("\n"); 1997 1998 db_printf("PQ_CACHE:"); 1999 for(i=0;i<PQ_L2_SIZE;i++) { 2000 db_printf(" %d", vm_page_queues[PQ_CACHE + i].lcnt); 2001 } 2002 db_printf("\n"); 2003 2004 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", 2005 vm_page_queues[PQ_ACTIVE].lcnt, 2006 vm_page_queues[PQ_INACTIVE].lcnt); 2007 } 2008 #endif /* DDB */ 2009