1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. 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_object.c 8.5 (Berkeley) 3/22/94 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 45 * 46 * Permission to use, copy, modify and distribute this software and 47 * its documentation is hereby granted, provided that both the copyright 48 * notice and this permission notice appear in all copies of the 49 * software, derivative works or modified versions, and any portions 50 * thereof, and that both notices appear in supporting documentation. 51 * 52 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 53 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 54 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 55 * 56 * Carnegie Mellon requests users of this software to return to 57 * 58 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 59 * School of Computer Science 60 * Carnegie Mellon University 61 * Pittsburgh PA 15213-3890 62 * 63 * any improvements or extensions that they make and grant Carnegie the 64 * rights to redistribute these changes. 65 * 66 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ 67 * $DragonFly: src/sys/vm/vm_object.c,v 1.33 2008/05/09 07:24:48 dillon Exp $ 68 */ 69 70 /* 71 * Virtual memory object module. 72 */ 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/proc.h> /* for curproc, pageproc */ 77 #include <sys/vnode.h> 78 #include <sys/vmmeter.h> 79 #include <sys/mman.h> 80 #include <sys/mount.h> 81 #include <sys/kernel.h> 82 #include <sys/sysctl.h> 83 84 #include <vm/vm.h> 85 #include <vm/vm_param.h> 86 #include <vm/pmap.h> 87 #include <vm/vm_map.h> 88 #include <vm/vm_object.h> 89 #include <vm/vm_page.h> 90 #include <vm/vm_pageout.h> 91 #include <vm/vm_pager.h> 92 #include <vm/swap_pager.h> 93 #include <vm/vm_kern.h> 94 #include <vm/vm_extern.h> 95 #include <vm/vm_zone.h> 96 97 #define EASY_SCAN_FACTOR 8 98 99 static void vm_object_qcollapse(vm_object_t object); 100 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, 101 int pagerflags); 102 103 /* 104 * Virtual memory objects maintain the actual data 105 * associated with allocated virtual memory. A given 106 * page of memory exists within exactly one object. 107 * 108 * An object is only deallocated when all "references" 109 * are given up. Only one "reference" to a given 110 * region of an object should be writeable. 111 * 112 * Associated with each object is a list of all resident 113 * memory pages belonging to that object; this list is 114 * maintained by the "vm_page" module, and locked by the object's 115 * lock. 116 * 117 * Each object also records a "pager" routine which is 118 * used to retrieve (and store) pages to the proper backing 119 * storage. In addition, objects may be backed by other 120 * objects from which they were virtual-copied. 121 * 122 * The only items within the object structure which are 123 * modified after time of creation are: 124 * reference count locked by object's lock 125 * pager routine locked by object's lock 126 * 127 */ 128 129 struct object_q vm_object_list; /* locked by vmobj_token */ 130 struct vm_object kernel_object; 131 132 static long vm_object_count; /* locked by vmobj_token */ 133 extern int vm_pageout_page_count; 134 135 static long object_collapses; 136 static long object_bypasses; 137 static int next_index; 138 static vm_zone_t obj_zone; 139 static struct vm_zone obj_zone_store; 140 static int object_hash_rand; 141 #define VM_OBJECTS_INIT 256 142 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 143 144 /* 145 * Initialize a freshly allocated object 146 * 147 * Used only by vm_object_allocate() and zinitna(). 148 * 149 * No requirements. 150 */ 151 void 152 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object) 153 { 154 int incr; 155 156 RB_INIT(&object->rb_memq); 157 LIST_INIT(&object->shadow_head); 158 159 object->type = type; 160 object->size = size; 161 object->ref_count = 1; 162 object->flags = 0; 163 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 164 vm_object_set_flag(object, OBJ_ONEMAPPING); 165 object->paging_in_progress = 0; 166 object->resident_page_count = 0; 167 object->shadow_count = 0; 168 object->pg_color = next_index; 169 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 170 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 171 else 172 incr = size; 173 next_index = (next_index + incr) & PQ_L2_MASK; 174 object->handle = NULL; 175 object->backing_object = NULL; 176 object->backing_object_offset = (vm_ooffset_t) 0; 177 /* 178 * Try to generate a number that will spread objects out in the 179 * hash table. We 'wipe' new objects across the hash in 128 page 180 * increments plus 1 more to offset it a little more by the time 181 * it wraps around. 182 */ 183 object->hash_rand = object_hash_rand - 129; 184 185 object->generation++; 186 object->swblock_count = 0; 187 RB_INIT(&object->swblock_root); 188 189 lwkt_gettoken(&vmobj_token); 190 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 191 vm_object_count++; 192 object_hash_rand = object->hash_rand; 193 lwkt_reltoken(&vmobj_token); 194 } 195 196 /* 197 * Initialize the VM objects module. 198 * 199 * Called from the low level boot code only. 200 */ 201 void 202 vm_object_init(void) 203 { 204 TAILQ_INIT(&vm_object_list); 205 206 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd), 207 &kernel_object); 208 209 obj_zone = &obj_zone_store; 210 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 211 vm_objects_init, VM_OBJECTS_INIT); 212 } 213 214 void 215 vm_object_init2(void) 216 { 217 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 218 } 219 220 /* 221 * Allocate and return a new object of the specified type and size. 222 * 223 * No requirements. 224 */ 225 vm_object_t 226 vm_object_allocate(objtype_t type, vm_pindex_t size) 227 { 228 vm_object_t result; 229 230 result = (vm_object_t) zalloc(obj_zone); 231 232 _vm_object_allocate(type, size, result); 233 234 return (result); 235 } 236 237 /* 238 * Add an additional reference to a vm_object. 239 * 240 * Object passed by caller must be stable or caller must already 241 * hold vmobj_token to avoid races. 242 */ 243 void 244 vm_object_reference(vm_object_t object) 245 { 246 if (object) { 247 lwkt_gettoken(&vmobj_token); 248 object->ref_count++; 249 if (object->type == OBJT_VNODE) { 250 vref(object->handle); 251 /* XXX what if the vnode is being destroyed? */ 252 } 253 lwkt_reltoken(&vmobj_token); 254 } 255 } 256 257 void 258 vm_object_reference_locked(vm_object_t object) 259 { 260 if (object) { 261 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 262 object->ref_count++; 263 if (object->type == OBJT_VNODE) { 264 vref(object->handle); 265 /* XXX what if the vnode is being destroyed? */ 266 } 267 } 268 } 269 270 /* 271 * Dereference an object and its underlying vnode. 272 * 273 * The caller must hold vmobj_token. 274 */ 275 static void 276 vm_object_vndeallocate(vm_object_t object) 277 { 278 struct vnode *vp = (struct vnode *) object->handle; 279 280 KASSERT(object->type == OBJT_VNODE, 281 ("vm_object_vndeallocate: not a vnode object")); 282 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 283 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 284 #ifdef INVARIANTS 285 if (object->ref_count == 0) { 286 vprint("vm_object_vndeallocate", vp); 287 panic("vm_object_vndeallocate: bad object reference count"); 288 } 289 #endif 290 291 object->ref_count--; 292 if (object->ref_count == 0) 293 vclrflags(vp, VTEXT); 294 vrele(vp); 295 } 296 297 /* 298 * Release a reference to the specified object, gained either through a 299 * vm_object_allocate or a vm_object_reference call. When all references 300 * are gone, storage associated with this object may be relinquished. 301 */ 302 void 303 vm_object_deallocate(vm_object_t object) 304 { 305 lwkt_gettoken(&vmobj_token); 306 vm_object_deallocate_locked(object); 307 lwkt_reltoken(&vmobj_token); 308 } 309 310 void 311 vm_object_deallocate_locked(vm_object_t object) 312 { 313 vm_object_t temp; 314 315 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 316 317 while (object != NULL) { 318 if (object->type == OBJT_VNODE) { 319 vm_object_vndeallocate(object); 320 break; 321 } 322 323 if (object->ref_count == 0) { 324 panic("vm_object_deallocate: object deallocated " 325 "too many times: %d", object->type); 326 } 327 if (object->ref_count > 2) { 328 object->ref_count--; 329 break; 330 } 331 332 /* 333 * We currently need the vm_token from this point on, and 334 * we must recheck ref_count after acquiring it. 335 */ 336 lwkt_gettoken(&vm_token); 337 338 if (object->ref_count > 2) { 339 object->ref_count--; 340 lwkt_reltoken(&vm_token); 341 break; 342 } 343 344 /* 345 * Here on ref_count of one or two, which are special cases for 346 * objects. 347 */ 348 if ((object->ref_count == 2) && (object->shadow_count == 0)) { 349 vm_object_set_flag(object, OBJ_ONEMAPPING); 350 object->ref_count--; 351 lwkt_reltoken(&vm_token); 352 break; 353 } 354 if ((object->ref_count == 2) && (object->shadow_count == 1)) { 355 object->ref_count--; 356 if ((object->handle == NULL) && 357 (object->type == OBJT_DEFAULT || 358 object->type == OBJT_SWAP)) { 359 vm_object_t robject; 360 361 robject = LIST_FIRST(&object->shadow_head); 362 KASSERT(robject != NULL, 363 ("vm_object_deallocate: ref_count: " 364 "%d, shadow_count: %d", 365 object->ref_count, 366 object->shadow_count)); 367 368 if ((robject->handle == NULL) && 369 (robject->type == OBJT_DEFAULT || 370 robject->type == OBJT_SWAP)) { 371 372 robject->ref_count++; 373 374 while ( 375 robject->paging_in_progress || 376 object->paging_in_progress 377 ) { 378 vm_object_pip_sleep(robject, "objde1"); 379 vm_object_pip_sleep(object, "objde2"); 380 } 381 382 if (robject->ref_count == 1) { 383 robject->ref_count--; 384 object = robject; 385 goto doterm; 386 } 387 388 object = robject; 389 vm_object_collapse(object); 390 lwkt_reltoken(&vm_token); 391 continue; 392 } 393 } 394 lwkt_reltoken(&vm_token); 395 break; 396 } 397 398 /* 399 * Normal dereferencing path 400 */ 401 object->ref_count--; 402 if (object->ref_count != 0) { 403 lwkt_reltoken(&vm_token); 404 break; 405 } 406 407 /* 408 * Termination path 409 */ 410 doterm: 411 temp = object->backing_object; 412 if (temp) { 413 LIST_REMOVE(object, shadow_list); 414 temp->shadow_count--; 415 temp->generation++; 416 object->backing_object = NULL; 417 } 418 lwkt_reltoken(&vm_token); 419 420 /* 421 * Don't double-terminate, we could be in a termination 422 * recursion due to the terminate having to sync data 423 * to disk. 424 */ 425 if ((object->flags & OBJ_DEAD) == 0) 426 vm_object_terminate(object); 427 object = temp; 428 } 429 } 430 431 /* 432 * Destroy the specified object, freeing up related resources. 433 * 434 * The object must have zero references. 435 * 436 * The caller must be holding vmobj_token and properly interlock with 437 * OBJ_DEAD. 438 */ 439 static int vm_object_terminate_callback(vm_page_t p, void *data); 440 441 void 442 vm_object_terminate(vm_object_t object) 443 { 444 /* 445 * Make sure no one uses us. Once we set OBJ_DEAD we should be 446 * able to safely block. 447 */ 448 KKASSERT((object->flags & OBJ_DEAD) == 0); 449 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 450 vm_object_set_flag(object, OBJ_DEAD); 451 452 /* 453 * Wait for the pageout daemon to be done with the object 454 */ 455 vm_object_pip_wait(object, "objtrm"); 456 457 KASSERT(!object->paging_in_progress, 458 ("vm_object_terminate: pageout in progress")); 459 460 /* 461 * Clean and free the pages, as appropriate. All references to the 462 * object are gone, so we don't need to lock it. 463 */ 464 if (object->type == OBJT_VNODE) { 465 struct vnode *vp; 466 467 /* 468 * Clean pages and flush buffers. 469 */ 470 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 471 472 vp = (struct vnode *) object->handle; 473 vinvalbuf(vp, V_SAVE, 0, 0); 474 } 475 476 /* 477 * Wait for any I/O to complete, after which there had better not 478 * be any references left on the object. 479 */ 480 vm_object_pip_wait(object, "objtrm"); 481 482 if (object->ref_count != 0) { 483 panic("vm_object_terminate: object with references, " 484 "ref_count=%d", object->ref_count); 485 } 486 487 /* 488 * Now free any remaining pages. For internal objects, this also 489 * removes them from paging queues. Don't free wired pages, just 490 * remove them from the object. 491 */ 492 lwkt_gettoken(&vm_token); 493 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 494 vm_object_terminate_callback, NULL); 495 lwkt_reltoken(&vm_token); 496 497 /* 498 * Let the pager know object is dead. 499 */ 500 vm_pager_deallocate(object); 501 502 /* 503 * Remove the object from the global object list. 504 * 505 * (we are holding vmobj_token) 506 */ 507 TAILQ_REMOVE(&vm_object_list, object, object_list); 508 vm_object_count--; 509 vm_object_dead_wakeup(object); 510 511 if (object->ref_count != 0) { 512 panic("vm_object_terminate2: object with references, " 513 "ref_count=%d", object->ref_count); 514 } 515 516 /* 517 * Free the space for the object. 518 */ 519 zfree(obj_zone, object); 520 } 521 522 /* 523 * The caller must hold vm_token. 524 */ 525 static int 526 vm_object_terminate_callback(vm_page_t p, void *data __unused) 527 { 528 if (p->busy || (p->flags & PG_BUSY)) 529 panic("vm_object_terminate: freeing busy page %p", p); 530 if (p->wire_count == 0) { 531 vm_page_busy(p); 532 vm_page_free(p); 533 mycpu->gd_cnt.v_pfree++; 534 } else { 535 if (p->queue != PQ_NONE) 536 kprintf("vm_object_terminate: Warning: Encountered wired page %p on queue %d\n", p, p->queue); 537 vm_page_busy(p); 538 vm_page_remove(p); 539 vm_page_wakeup(p); 540 } 541 return(0); 542 } 543 544 /* 545 * The object is dead but still has an object<->pager association. Sleep 546 * and return. The caller typically retests the association in a loop. 547 * 548 * Must be called with the vmobj_token held. 549 */ 550 void 551 vm_object_dead_sleep(vm_object_t object, const char *wmesg) 552 { 553 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 554 if (object->handle) { 555 vm_object_set_flag(object, OBJ_DEADWNT); 556 tsleep(object, 0, wmesg, 0); 557 /* object may be invalid after this point */ 558 } 559 } 560 561 /* 562 * Wakeup anyone waiting for the object<->pager disassociation on 563 * a dead object. 564 * 565 * Must be called with the vmobj_token held. 566 */ 567 void 568 vm_object_dead_wakeup(vm_object_t object) 569 { 570 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 571 if (object->flags & OBJ_DEADWNT) { 572 vm_object_clear_flag(object, OBJ_DEADWNT); 573 wakeup(object); 574 } 575 } 576 577 /* 578 * Clean all dirty pages in the specified range of object. Leaves page 579 * on whatever queue it is currently on. If NOSYNC is set then do not 580 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 581 * leaving the object dirty. 582 * 583 * When stuffing pages asynchronously, allow clustering. XXX we need a 584 * synchronous clustering mode implementation. 585 * 586 * Odd semantics: if start == end, we clean everything. 587 * 588 * The object must be locked? XXX 589 */ 590 static int vm_object_page_clean_pass1(struct vm_page *p, void *data); 591 static int vm_object_page_clean_pass2(struct vm_page *p, void *data); 592 593 void 594 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 595 int flags) 596 { 597 struct rb_vm_page_scan_info info; 598 struct vnode *vp; 599 int wholescan; 600 int pagerflags; 601 int curgeneration; 602 603 lwkt_gettoken(&vm_token); 604 if (object->type != OBJT_VNODE || 605 (object->flags & OBJ_MIGHTBEDIRTY) == 0) { 606 lwkt_reltoken(&vm_token); 607 return; 608 } 609 610 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? 611 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 612 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 613 614 vp = object->handle; 615 616 /* 617 * Interlock other major object operations. This allows us to 618 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY. 619 */ 620 crit_enter(); 621 vm_object_set_flag(object, OBJ_CLEANING); 622 623 /* 624 * Handle 'entire object' case 625 */ 626 info.start_pindex = start; 627 if (end == 0) { 628 info.end_pindex = object->size - 1; 629 } else { 630 info.end_pindex = end - 1; 631 } 632 wholescan = (start == 0 && info.end_pindex == object->size - 1); 633 info.limit = flags; 634 info.pagerflags = pagerflags; 635 info.object = object; 636 637 /* 638 * If cleaning the entire object do a pass to mark the pages read-only. 639 * If everything worked out ok, clear OBJ_WRITEABLE and 640 * OBJ_MIGHTBEDIRTY. 641 */ 642 if (wholescan) { 643 info.error = 0; 644 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 645 vm_object_page_clean_pass1, &info); 646 if (info.error == 0) { 647 vm_object_clear_flag(object, 648 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 649 if (object->type == OBJT_VNODE && 650 (vp = (struct vnode *)object->handle) != NULL) { 651 if (vp->v_flag & VOBJDIRTY) 652 vclrflags(vp, VOBJDIRTY); 653 } 654 } 655 } 656 657 /* 658 * Do a pass to clean all the dirty pages we find. 659 */ 660 do { 661 info.error = 0; 662 curgeneration = object->generation; 663 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 664 vm_object_page_clean_pass2, &info); 665 } while (info.error || curgeneration != object->generation); 666 667 vm_object_clear_flag(object, OBJ_CLEANING); 668 crit_exit(); 669 lwkt_reltoken(&vm_token); 670 } 671 672 /* 673 * The caller must hold vm_token. 674 */ 675 static 676 int 677 vm_object_page_clean_pass1(struct vm_page *p, void *data) 678 { 679 struct rb_vm_page_scan_info *info = data; 680 681 vm_page_flag_set(p, PG_CLEANCHK); 682 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) 683 info->error = 1; 684 else 685 vm_page_protect(p, VM_PROT_READ); /* must not block */ 686 return(0); 687 } 688 689 /* 690 * The caller must hold vm_token. 691 */ 692 static 693 int 694 vm_object_page_clean_pass2(struct vm_page *p, void *data) 695 { 696 struct rb_vm_page_scan_info *info = data; 697 int n; 698 699 /* 700 * Do not mess with pages that were inserted after we started 701 * the cleaning pass. 702 */ 703 if ((p->flags & PG_CLEANCHK) == 0) 704 return(0); 705 706 /* 707 * Before wasting time traversing the pmaps, check for trivial 708 * cases where the page cannot be dirty. 709 */ 710 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { 711 KKASSERT((p->dirty & p->valid) == 0); 712 return(0); 713 } 714 715 /* 716 * Check whether the page is dirty or not. The page has been set 717 * to be read-only so the check will not race a user dirtying the 718 * page. 719 */ 720 vm_page_test_dirty(p); 721 if ((p->dirty & p->valid) == 0) { 722 vm_page_flag_clear(p, PG_CLEANCHK); 723 return(0); 724 } 725 726 /* 727 * If we have been asked to skip nosync pages and this is a 728 * nosync page, skip it. Note that the object flags were 729 * not cleared in this case (because pass1 will have returned an 730 * error), so we do not have to set them. 731 */ 732 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 733 vm_page_flag_clear(p, PG_CLEANCHK); 734 return(0); 735 } 736 737 /* 738 * Flush as many pages as we can. PG_CLEANCHK will be cleared on 739 * the pages that get successfully flushed. Set info->error if 740 * we raced an object modification. 741 */ 742 n = vm_object_page_collect_flush(info->object, p, info->pagerflags); 743 if (n == 0) 744 info->error = 1; 745 return(0); 746 } 747 748 /* 749 * Collect the specified page and nearby pages and flush them out. 750 * The number of pages flushed is returned. 751 * 752 * The caller must hold vm_token. 753 */ 754 static int 755 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags) 756 { 757 int runlen; 758 int maxf; 759 int chkb; 760 int maxb; 761 int i; 762 int curgeneration; 763 vm_pindex_t pi; 764 vm_page_t maf[vm_pageout_page_count]; 765 vm_page_t mab[vm_pageout_page_count]; 766 vm_page_t ma[vm_pageout_page_count]; 767 768 curgeneration = object->generation; 769 770 pi = p->pindex; 771 while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { 772 if (object->generation != curgeneration) { 773 return(0); 774 } 775 } 776 KKASSERT(p->object == object && p->pindex == pi); 777 778 maxf = 0; 779 for(i = 1; i < vm_pageout_page_count; i++) { 780 vm_page_t tp; 781 782 if ((tp = vm_page_lookup(object, pi + i)) != NULL) { 783 if ((tp->flags & PG_BUSY) || 784 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 785 (tp->flags & PG_CLEANCHK) == 0) || 786 (tp->busy != 0)) 787 break; 788 if((tp->queue - tp->pc) == PQ_CACHE) { 789 vm_page_flag_clear(tp, PG_CLEANCHK); 790 break; 791 } 792 vm_page_test_dirty(tp); 793 if ((tp->dirty & tp->valid) == 0) { 794 vm_page_flag_clear(tp, PG_CLEANCHK); 795 break; 796 } 797 maf[ i - 1 ] = tp; 798 maxf++; 799 continue; 800 } 801 break; 802 } 803 804 maxb = 0; 805 chkb = vm_pageout_page_count - maxf; 806 if (chkb) { 807 for(i = 1; i < chkb;i++) { 808 vm_page_t tp; 809 810 if ((tp = vm_page_lookup(object, pi - i)) != NULL) { 811 if ((tp->flags & PG_BUSY) || 812 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 813 (tp->flags & PG_CLEANCHK) == 0) || 814 (tp->busy != 0)) 815 break; 816 if((tp->queue - tp->pc) == PQ_CACHE) { 817 vm_page_flag_clear(tp, PG_CLEANCHK); 818 break; 819 } 820 vm_page_test_dirty(tp); 821 if ((tp->dirty & tp->valid) == 0) { 822 vm_page_flag_clear(tp, PG_CLEANCHK); 823 break; 824 } 825 mab[ i - 1 ] = tp; 826 maxb++; 827 continue; 828 } 829 break; 830 } 831 } 832 833 for(i = 0; i < maxb; i++) { 834 int index = (maxb - i) - 1; 835 ma[index] = mab[i]; 836 vm_page_flag_clear(ma[index], PG_CLEANCHK); 837 } 838 vm_page_flag_clear(p, PG_CLEANCHK); 839 ma[maxb] = p; 840 for(i = 0; i < maxf; i++) { 841 int index = (maxb + i) + 1; 842 ma[index] = maf[i]; 843 vm_page_flag_clear(ma[index], PG_CLEANCHK); 844 } 845 runlen = maxb + maxf + 1; 846 847 vm_pageout_flush(ma, runlen, pagerflags); 848 for (i = 0; i < runlen; i++) { 849 if (ma[i]->valid & ma[i]->dirty) { 850 vm_page_protect(ma[i], VM_PROT_READ); 851 vm_page_flag_set(ma[i], PG_CLEANCHK); 852 853 /* 854 * maxf will end up being the actual number of pages 855 * we wrote out contiguously, non-inclusive of the 856 * first page. We do not count look-behind pages. 857 */ 858 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 859 maxf = i - maxb - 1; 860 } 861 } 862 return(maxf + 1); 863 } 864 865 /* 866 * Same as vm_object_pmap_copy, except range checking really 867 * works, and is meant for small sections of an object. 868 * 869 * This code protects resident pages by making them read-only 870 * and is typically called on a fork or split when a page 871 * is converted to copy-on-write. 872 * 873 * NOTE: If the page is already at VM_PROT_NONE, calling 874 * vm_page_protect will have no effect. 875 */ 876 void 877 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 878 { 879 vm_pindex_t idx; 880 vm_page_t p; 881 882 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 883 return; 884 885 /* 886 * spl protection needed to prevent races between the lookup, 887 * an interrupt unbusy/free, and our protect call. 888 */ 889 crit_enter(); 890 lwkt_gettoken(&vm_token); 891 for (idx = start; idx < end; idx++) { 892 p = vm_page_lookup(object, idx); 893 if (p == NULL) 894 continue; 895 vm_page_protect(p, VM_PROT_READ); 896 } 897 lwkt_reltoken(&vm_token); 898 crit_exit(); 899 } 900 901 /* 902 * Removes all physical pages in the specified object range from all 903 * physical maps. 904 * 905 * The object must *not* be locked. 906 */ 907 908 static int vm_object_pmap_remove_callback(vm_page_t p, void *data); 909 910 void 911 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 912 { 913 struct rb_vm_page_scan_info info; 914 915 if (object == NULL) 916 return; 917 info.start_pindex = start; 918 info.end_pindex = end - 1; 919 920 crit_enter(); 921 lwkt_gettoken(&vm_token); 922 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 923 vm_object_pmap_remove_callback, &info); 924 if (start == 0 && end == object->size) 925 vm_object_clear_flag(object, OBJ_WRITEABLE); 926 lwkt_reltoken(&vm_token); 927 crit_exit(); 928 } 929 930 /* 931 * The caller must hold vm_token. 932 */ 933 static int 934 vm_object_pmap_remove_callback(vm_page_t p, void *data __unused) 935 { 936 vm_page_protect(p, VM_PROT_NONE); 937 return(0); 938 } 939 940 /* 941 * Implements the madvise function at the object/page level. 942 * 943 * MADV_WILLNEED (any object) 944 * 945 * Activate the specified pages if they are resident. 946 * 947 * MADV_DONTNEED (any object) 948 * 949 * Deactivate the specified pages if they are resident. 950 * 951 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only) 952 * 953 * Deactivate and clean the specified pages if they are 954 * resident. This permits the process to reuse the pages 955 * without faulting or the kernel to reclaim the pages 956 * without I/O. 957 * 958 * No requirements. 959 */ 960 void 961 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise) 962 { 963 vm_pindex_t end, tpindex; 964 vm_object_t tobject; 965 vm_page_t m; 966 967 if (object == NULL) 968 return; 969 970 end = pindex + count; 971 972 lwkt_gettoken(&vm_token); 973 974 /* 975 * Locate and adjust resident pages 976 */ 977 for (; pindex < end; pindex += 1) { 978 relookup: 979 tobject = object; 980 tpindex = pindex; 981 shadowlookup: 982 /* 983 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 984 * and those pages must be OBJ_ONEMAPPING. 985 */ 986 if (advise == MADV_FREE) { 987 if ((tobject->type != OBJT_DEFAULT && 988 tobject->type != OBJT_SWAP) || 989 (tobject->flags & OBJ_ONEMAPPING) == 0) { 990 continue; 991 } 992 } 993 994 /* 995 * spl protection is required to avoid a race between the 996 * lookup, an interrupt unbusy/free, and our busy check. 997 */ 998 999 crit_enter(); 1000 m = vm_page_lookup(tobject, tpindex); 1001 1002 if (m == NULL) { 1003 /* 1004 * There may be swap even if there is no backing page 1005 */ 1006 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1007 swap_pager_freespace(tobject, tpindex, 1); 1008 1009 /* 1010 * next object 1011 */ 1012 crit_exit(); 1013 if (tobject->backing_object == NULL) 1014 continue; 1015 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1016 tobject = tobject->backing_object; 1017 goto shadowlookup; 1018 } 1019 1020 /* 1021 * If the page is busy or not in a normal active state, 1022 * we skip it. If the page is not managed there are no 1023 * page queues to mess with. Things can break if we mess 1024 * with pages in any of the below states. 1025 */ 1026 if ( 1027 m->hold_count || 1028 m->wire_count || 1029 (m->flags & PG_UNMANAGED) || 1030 m->valid != VM_PAGE_BITS_ALL 1031 ) { 1032 crit_exit(); 1033 continue; 1034 } 1035 1036 if (vm_page_sleep_busy(m, TRUE, "madvpo")) { 1037 crit_exit(); 1038 goto relookup; 1039 } 1040 crit_exit(); 1041 1042 /* 1043 * Theoretically once a page is known not to be busy, an 1044 * interrupt cannot come along and rip it out from under us. 1045 */ 1046 1047 if (advise == MADV_WILLNEED) { 1048 vm_page_activate(m); 1049 } else if (advise == MADV_DONTNEED) { 1050 vm_page_dontneed(m); 1051 } else if (advise == MADV_FREE) { 1052 /* 1053 * Mark the page clean. This will allow the page 1054 * to be freed up by the system. However, such pages 1055 * are often reused quickly by malloc()/free() 1056 * so we do not do anything that would cause 1057 * a page fault if we can help it. 1058 * 1059 * Specifically, we do not try to actually free 1060 * the page now nor do we try to put it in the 1061 * cache (which would cause a page fault on reuse). 1062 * 1063 * But we do make the page is freeable as we 1064 * can without actually taking the step of unmapping 1065 * it. 1066 */ 1067 pmap_clear_modify(m); 1068 m->dirty = 0; 1069 m->act_count = 0; 1070 vm_page_dontneed(m); 1071 if (tobject->type == OBJT_SWAP) 1072 swap_pager_freespace(tobject, tpindex, 1); 1073 } 1074 } 1075 lwkt_reltoken(&vm_token); 1076 } 1077 1078 /* 1079 * Create a new object which is backed by the specified existing object 1080 * range. The source object reference is deallocated. 1081 * 1082 * The new object and offset into that object are returned in the source 1083 * parameters. 1084 * 1085 * No other requirements. 1086 */ 1087 void 1088 vm_object_shadow(vm_object_t *object, vm_ooffset_t *offset, vm_size_t length) 1089 { 1090 vm_object_t source; 1091 vm_object_t result; 1092 1093 source = *object; 1094 1095 /* 1096 * Don't create the new object if the old object isn't shared. 1097 */ 1098 lwkt_gettoken(&vm_token); 1099 1100 if (source != NULL && 1101 source->ref_count == 1 && 1102 source->handle == NULL && 1103 (source->type == OBJT_DEFAULT || 1104 source->type == OBJT_SWAP)) { 1105 lwkt_reltoken(&vm_token); 1106 return; 1107 } 1108 1109 /* 1110 * Allocate a new object with the given length 1111 */ 1112 1113 if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) 1114 panic("vm_object_shadow: no object for shadowing"); 1115 1116 /* 1117 * The new object shadows the source object, adding a reference to it. 1118 * Our caller changes his reference to point to the new object, 1119 * removing a reference to the source object. Net result: no change 1120 * of reference count. 1121 * 1122 * Try to optimize the result object's page color when shadowing 1123 * in order to maintain page coloring consistency in the combined 1124 * shadowed object. 1125 */ 1126 result->backing_object = source; 1127 if (source) { 1128 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); 1129 source->shadow_count++; 1130 source->generation++; 1131 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK; 1132 } 1133 1134 /* 1135 * Store the offset into the source object, and fix up the offset into 1136 * the new object. 1137 */ 1138 result->backing_object_offset = *offset; 1139 lwkt_reltoken(&vm_token); 1140 1141 /* 1142 * Return the new things 1143 */ 1144 *offset = 0; 1145 *object = result; 1146 } 1147 1148 #define OBSC_TEST_ALL_SHADOWED 0x0001 1149 #define OBSC_COLLAPSE_NOWAIT 0x0002 1150 #define OBSC_COLLAPSE_WAIT 0x0004 1151 1152 static int vm_object_backing_scan_callback(vm_page_t p, void *data); 1153 1154 /* 1155 * The caller must hold vm_token. 1156 */ 1157 static __inline int 1158 vm_object_backing_scan(vm_object_t object, int op) 1159 { 1160 struct rb_vm_page_scan_info info; 1161 vm_object_t backing_object; 1162 1163 crit_enter(); 1164 1165 backing_object = object->backing_object; 1166 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1167 1168 /* 1169 * Initial conditions 1170 */ 1171 1172 if (op & OBSC_TEST_ALL_SHADOWED) { 1173 /* 1174 * We do not want to have to test for the existence of 1175 * swap pages in the backing object. XXX but with the 1176 * new swapper this would be pretty easy to do. 1177 * 1178 * XXX what about anonymous MAP_SHARED memory that hasn't 1179 * been ZFOD faulted yet? If we do not test for this, the 1180 * shadow test may succeed! XXX 1181 */ 1182 if (backing_object->type != OBJT_DEFAULT) { 1183 crit_exit(); 1184 return(0); 1185 } 1186 } 1187 if (op & OBSC_COLLAPSE_WAIT) { 1188 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 1189 vm_object_set_flag(backing_object, OBJ_DEAD); 1190 } 1191 1192 /* 1193 * Our scan. We have to retry if a negative error code is returned, 1194 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that 1195 * the scan had to be stopped because the parent does not completely 1196 * shadow the child. 1197 */ 1198 info.object = object; 1199 info.backing_object = backing_object; 1200 info.limit = op; 1201 do { 1202 info.error = 1; 1203 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL, 1204 vm_object_backing_scan_callback, 1205 &info); 1206 } while (info.error < 0); 1207 crit_exit(); 1208 return(info.error); 1209 } 1210 1211 /* 1212 * The caller must hold vm_token. 1213 */ 1214 static int 1215 vm_object_backing_scan_callback(vm_page_t p, void *data) 1216 { 1217 struct rb_vm_page_scan_info *info = data; 1218 vm_object_t backing_object; 1219 vm_object_t object; 1220 vm_pindex_t new_pindex; 1221 vm_pindex_t backing_offset_index; 1222 int op; 1223 1224 new_pindex = p->pindex - info->backing_offset_index; 1225 op = info->limit; 1226 object = info->object; 1227 backing_object = info->backing_object; 1228 backing_offset_index = info->backing_offset_index; 1229 1230 if (op & OBSC_TEST_ALL_SHADOWED) { 1231 vm_page_t pp; 1232 1233 /* 1234 * Ignore pages outside the parent object's range 1235 * and outside the parent object's mapping of the 1236 * backing object. 1237 * 1238 * note that we do not busy the backing object's 1239 * page. 1240 */ 1241 if ( 1242 p->pindex < backing_offset_index || 1243 new_pindex >= object->size 1244 ) { 1245 return(0); 1246 } 1247 1248 /* 1249 * See if the parent has the page or if the parent's 1250 * object pager has the page. If the parent has the 1251 * page but the page is not valid, the parent's 1252 * object pager must have the page. 1253 * 1254 * If this fails, the parent does not completely shadow 1255 * the object and we might as well give up now. 1256 */ 1257 1258 pp = vm_page_lookup(object, new_pindex); 1259 if ((pp == NULL || pp->valid == 0) && 1260 !vm_pager_has_page(object, new_pindex) 1261 ) { 1262 info->error = 0; /* problemo */ 1263 return(-1); /* stop the scan */ 1264 } 1265 } 1266 1267 /* 1268 * Check for busy page 1269 */ 1270 1271 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1272 vm_page_t pp; 1273 1274 if (op & OBSC_COLLAPSE_NOWAIT) { 1275 if ( 1276 (p->flags & PG_BUSY) || 1277 !p->valid || 1278 p->hold_count || 1279 p->wire_count || 1280 p->busy 1281 ) { 1282 return(0); 1283 } 1284 } else if (op & OBSC_COLLAPSE_WAIT) { 1285 if (vm_page_sleep_busy(p, TRUE, "vmocol")) { 1286 /* 1287 * If we slept, anything could have 1288 * happened. Ask that the scan be restarted. 1289 * 1290 * Since the object is marked dead, the 1291 * backing offset should not have changed. 1292 */ 1293 info->error = -1; 1294 return(-1); 1295 } 1296 } 1297 1298 /* 1299 * Busy the page 1300 */ 1301 vm_page_busy(p); 1302 1303 KASSERT( 1304 p->object == backing_object, 1305 ("vm_object_qcollapse(): object mismatch") 1306 ); 1307 1308 /* 1309 * Destroy any associated swap 1310 */ 1311 if (backing_object->type == OBJT_SWAP) 1312 swap_pager_freespace(backing_object, p->pindex, 1); 1313 1314 if ( 1315 p->pindex < backing_offset_index || 1316 new_pindex >= object->size 1317 ) { 1318 /* 1319 * Page is out of the parent object's range, we 1320 * can simply destroy it. 1321 */ 1322 vm_page_protect(p, VM_PROT_NONE); 1323 vm_page_free(p); 1324 return(0); 1325 } 1326 1327 pp = vm_page_lookup(object, new_pindex); 1328 if (pp != NULL || vm_pager_has_page(object, new_pindex)) { 1329 /* 1330 * page already exists in parent OR swap exists 1331 * for this location in the parent. Destroy 1332 * the original page from the backing object. 1333 * 1334 * Leave the parent's page alone 1335 */ 1336 vm_page_protect(p, VM_PROT_NONE); 1337 vm_page_free(p); 1338 return(0); 1339 } 1340 1341 /* 1342 * Page does not exist in parent, rename the 1343 * page from the backing object to the main object. 1344 * 1345 * If the page was mapped to a process, it can remain 1346 * mapped through the rename. 1347 */ 1348 if ((p->queue - p->pc) == PQ_CACHE) 1349 vm_page_deactivate(p); 1350 1351 vm_page_rename(p, object, new_pindex); 1352 /* page automatically made dirty by rename */ 1353 } 1354 return(0); 1355 } 1356 1357 /* 1358 * This version of collapse allows the operation to occur earlier and 1359 * when paging_in_progress is true for an object... This is not a complete 1360 * operation, but should plug 99.9% of the rest of the leaks. 1361 * 1362 * The caller must hold vm_token and vmobj_token. 1363 * (only called from vm_object_collapse) 1364 */ 1365 static void 1366 vm_object_qcollapse(vm_object_t object) 1367 { 1368 vm_object_t backing_object = object->backing_object; 1369 1370 if (backing_object->ref_count != 1) 1371 return; 1372 1373 backing_object->ref_count += 2; 1374 1375 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 1376 1377 backing_object->ref_count -= 2; 1378 } 1379 1380 /* 1381 * Collapse an object with the object backing it. Pages in the backing 1382 * object are moved into the parent, and the backing object is deallocated. 1383 */ 1384 void 1385 vm_object_collapse(vm_object_t object) 1386 { 1387 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1388 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1389 1390 while (TRUE) { 1391 vm_object_t backing_object; 1392 1393 /* 1394 * Verify that the conditions are right for collapse: 1395 * 1396 * The object exists and the backing object exists. 1397 */ 1398 if (object == NULL) 1399 break; 1400 1401 if ((backing_object = object->backing_object) == NULL) 1402 break; 1403 1404 /* 1405 * we check the backing object first, because it is most likely 1406 * not collapsable. 1407 */ 1408 if (backing_object->handle != NULL || 1409 (backing_object->type != OBJT_DEFAULT && 1410 backing_object->type != OBJT_SWAP) || 1411 (backing_object->flags & OBJ_DEAD) || 1412 object->handle != NULL || 1413 (object->type != OBJT_DEFAULT && 1414 object->type != OBJT_SWAP) || 1415 (object->flags & OBJ_DEAD)) { 1416 break; 1417 } 1418 1419 if ( 1420 object->paging_in_progress != 0 || 1421 backing_object->paging_in_progress != 0 1422 ) { 1423 vm_object_qcollapse(object); 1424 break; 1425 } 1426 1427 /* 1428 * We know that we can either collapse the backing object (if 1429 * the parent is the only reference to it) or (perhaps) have 1430 * the parent bypass the object if the parent happens to shadow 1431 * all the resident pages in the entire backing object. 1432 * 1433 * This is ignoring pager-backed pages such as swap pages. 1434 * vm_object_backing_scan fails the shadowing test in this 1435 * case. 1436 */ 1437 1438 if (backing_object->ref_count == 1) { 1439 /* 1440 * If there is exactly one reference to the backing 1441 * object, we can collapse it into the parent. 1442 */ 1443 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); 1444 1445 /* 1446 * Move the pager from backing_object to object. 1447 */ 1448 1449 if (backing_object->type == OBJT_SWAP) { 1450 vm_object_pip_add(backing_object, 1); 1451 1452 /* 1453 * scrap the paging_offset junk and do a 1454 * discrete copy. This also removes major 1455 * assumptions about how the swap-pager 1456 * works from where it doesn't belong. The 1457 * new swapper is able to optimize the 1458 * destroy-source case. 1459 */ 1460 1461 vm_object_pip_add(object, 1); 1462 swap_pager_copy( 1463 backing_object, 1464 object, 1465 OFF_TO_IDX(object->backing_object_offset), TRUE); 1466 vm_object_pip_wakeup(object); 1467 1468 vm_object_pip_wakeup(backing_object); 1469 } 1470 /* 1471 * Object now shadows whatever backing_object did. 1472 * Note that the reference to 1473 * backing_object->backing_object moves from within 1474 * backing_object to within object. 1475 */ 1476 1477 LIST_REMOVE(object, shadow_list); 1478 object->backing_object->shadow_count--; 1479 object->backing_object->generation++; 1480 if (backing_object->backing_object) { 1481 LIST_REMOVE(backing_object, shadow_list); 1482 backing_object->backing_object->shadow_count--; 1483 backing_object->backing_object->generation++; 1484 } 1485 object->backing_object = backing_object->backing_object; 1486 if (object->backing_object) { 1487 LIST_INSERT_HEAD( 1488 &object->backing_object->shadow_head, 1489 object, 1490 shadow_list 1491 ); 1492 object->backing_object->shadow_count++; 1493 object->backing_object->generation++; 1494 } 1495 1496 object->backing_object_offset += 1497 backing_object->backing_object_offset; 1498 1499 /* 1500 * Discard backing_object. 1501 * 1502 * Since the backing object has no pages, no pager left, 1503 * and no object references within it, all that is 1504 * necessary is to dispose of it. 1505 */ 1506 1507 KASSERT(backing_object->ref_count == 1, 1508 ("backing_object %p was somehow " 1509 "re-referenced during collapse!", 1510 backing_object)); 1511 KASSERT(RB_EMPTY(&backing_object->rb_memq), 1512 ("backing_object %p somehow has left " 1513 "over pages during collapse!", 1514 backing_object)); 1515 1516 /* (we are holding vmobj_token) */ 1517 TAILQ_REMOVE(&vm_object_list, backing_object, 1518 object_list); 1519 vm_object_count--; 1520 1521 zfree(obj_zone, backing_object); 1522 1523 object_collapses++; 1524 } else { 1525 vm_object_t new_backing_object; 1526 1527 /* 1528 * If we do not entirely shadow the backing object, 1529 * there is nothing we can do so we give up. 1530 */ 1531 1532 if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) { 1533 break; 1534 } 1535 1536 /* 1537 * Make the parent shadow the next object in the 1538 * chain. Deallocating backing_object will not remove 1539 * it, since its reference count is at least 2. 1540 */ 1541 1542 LIST_REMOVE(object, shadow_list); 1543 backing_object->shadow_count--; 1544 backing_object->generation++; 1545 1546 new_backing_object = backing_object->backing_object; 1547 if ((object->backing_object = new_backing_object) != NULL) { 1548 vm_object_reference(new_backing_object); 1549 LIST_INSERT_HEAD( 1550 &new_backing_object->shadow_head, 1551 object, 1552 shadow_list 1553 ); 1554 new_backing_object->shadow_count++; 1555 new_backing_object->generation++; 1556 object->backing_object_offset += 1557 backing_object->backing_object_offset; 1558 } 1559 1560 /* 1561 * Drop the reference count on backing_object. Since 1562 * its ref_count was at least 2, it will not vanish; 1563 * so we don't need to call vm_object_deallocate, but 1564 * we do anyway. 1565 */ 1566 vm_object_deallocate_locked(backing_object); 1567 object_bypasses++; 1568 } 1569 1570 /* 1571 * Try again with this object's new backing object. 1572 */ 1573 } 1574 } 1575 1576 /* 1577 * Removes all physical pages in the specified object range from the 1578 * object's list of pages. 1579 * 1580 * No requirements. 1581 */ 1582 static int vm_object_page_remove_callback(vm_page_t p, void *data); 1583 1584 void 1585 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1586 boolean_t clean_only) 1587 { 1588 struct rb_vm_page_scan_info info; 1589 int all; 1590 1591 /* 1592 * Degenerate cases and assertions 1593 */ 1594 lwkt_gettoken(&vm_token); 1595 if (object == NULL || 1596 (object->resident_page_count == 0 && object->swblock_count == 0)) { 1597 lwkt_reltoken(&vm_token); 1598 return; 1599 } 1600 KASSERT(object->type != OBJT_PHYS, 1601 ("attempt to remove pages from a physical object")); 1602 1603 /* 1604 * Indicate that paging is occuring on the object 1605 */ 1606 crit_enter(); 1607 vm_object_pip_add(object, 1); 1608 1609 /* 1610 * Figure out the actual removal range and whether we are removing 1611 * the entire contents of the object or not. If removing the entire 1612 * contents, be sure to get all pages, even those that might be 1613 * beyond the end of the object. 1614 */ 1615 info.start_pindex = start; 1616 if (end == 0) 1617 info.end_pindex = (vm_pindex_t)-1; 1618 else 1619 info.end_pindex = end - 1; 1620 info.limit = clean_only; 1621 all = (start == 0 && info.end_pindex >= object->size - 1); 1622 1623 /* 1624 * Loop until we are sure we have gotten them all. 1625 */ 1626 do { 1627 info.error = 0; 1628 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1629 vm_object_page_remove_callback, &info); 1630 } while (info.error); 1631 1632 /* 1633 * Remove any related swap if throwing away pages, or for 1634 * non-swap objects (the swap is a clean copy in that case). 1635 */ 1636 if (object->type != OBJT_SWAP || clean_only == FALSE) { 1637 if (all) 1638 swap_pager_freespace_all(object); 1639 else 1640 swap_pager_freespace(object, info.start_pindex, 1641 info.end_pindex - info.start_pindex + 1); 1642 } 1643 1644 /* 1645 * Cleanup 1646 */ 1647 vm_object_pip_wakeup(object); 1648 crit_exit(); 1649 lwkt_reltoken(&vm_token); 1650 } 1651 1652 /* 1653 * The caller must hold vm_token. 1654 */ 1655 static int 1656 vm_object_page_remove_callback(vm_page_t p, void *data) 1657 { 1658 struct rb_vm_page_scan_info *info = data; 1659 1660 /* 1661 * Wired pages cannot be destroyed, but they can be invalidated 1662 * and we do so if clean_only (limit) is not set. 1663 * 1664 * WARNING! The page may be wired due to being part of a buffer 1665 * cache buffer, and the buffer might be marked B_CACHE. 1666 * This is fine as part of a truncation but VFSs must be 1667 * sure to fix the buffer up when re-extending the file. 1668 */ 1669 if (p->wire_count != 0) { 1670 vm_page_protect(p, VM_PROT_NONE); 1671 if (info->limit == 0) 1672 p->valid = 0; 1673 return(0); 1674 } 1675 1676 /* 1677 * The busy flags are only cleared at 1678 * interrupt -- minimize the spl transitions 1679 */ 1680 1681 if (vm_page_sleep_busy(p, TRUE, "vmopar")) { 1682 info->error = 1; 1683 return(0); 1684 } 1685 1686 /* 1687 * limit is our clean_only flag. If set and the page is dirty, do 1688 * not free it. If set and the page is being held by someone, do 1689 * not free it. 1690 */ 1691 if (info->limit && p->valid) { 1692 vm_page_test_dirty(p); 1693 if (p->valid & p->dirty) 1694 return(0); 1695 if (p->hold_count) 1696 return(0); 1697 } 1698 1699 /* 1700 * Destroy the page 1701 */ 1702 vm_page_busy(p); 1703 vm_page_protect(p, VM_PROT_NONE); 1704 vm_page_free(p); 1705 return(0); 1706 } 1707 1708 /* 1709 * Coalesces two objects backing up adjoining regions of memory into a 1710 * single object. 1711 * 1712 * returns TRUE if objects were combined. 1713 * 1714 * NOTE: Only works at the moment if the second object is NULL - 1715 * if it's not, which object do we lock first? 1716 * 1717 * Parameters: 1718 * prev_object First object to coalesce 1719 * prev_offset Offset into prev_object 1720 * next_object Second object into coalesce 1721 * next_offset Offset into next_object 1722 * 1723 * prev_size Size of reference to prev_object 1724 * next_size Size of reference to next_object 1725 * 1726 * The object must not be locked. 1727 * The caller must hold vm_token and vmobj_token. 1728 */ 1729 boolean_t 1730 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 1731 vm_size_t prev_size, vm_size_t next_size) 1732 { 1733 vm_pindex_t next_pindex; 1734 1735 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1736 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1737 1738 if (prev_object == NULL) { 1739 return (TRUE); 1740 } 1741 1742 if (prev_object->type != OBJT_DEFAULT && 1743 prev_object->type != OBJT_SWAP) { 1744 return (FALSE); 1745 } 1746 1747 /* 1748 * Try to collapse the object first 1749 */ 1750 vm_object_collapse(prev_object); 1751 1752 /* 1753 * Can't coalesce if: . more than one reference . paged out . shadows 1754 * another object . has a copy elsewhere (any of which mean that the 1755 * pages not mapped to prev_entry may be in use anyway) 1756 */ 1757 1758 if (prev_object->backing_object != NULL) 1759 return (FALSE); 1760 1761 prev_size >>= PAGE_SHIFT; 1762 next_size >>= PAGE_SHIFT; 1763 next_pindex = prev_pindex + prev_size; 1764 1765 if ((prev_object->ref_count > 1) && 1766 (prev_object->size != next_pindex)) { 1767 return (FALSE); 1768 } 1769 1770 /* 1771 * Remove any pages that may still be in the object from a previous 1772 * deallocation. 1773 */ 1774 if (next_pindex < prev_object->size) { 1775 vm_object_page_remove(prev_object, 1776 next_pindex, 1777 next_pindex + next_size, FALSE); 1778 if (prev_object->type == OBJT_SWAP) 1779 swap_pager_freespace(prev_object, 1780 next_pindex, next_size); 1781 } 1782 1783 /* 1784 * Extend the object if necessary. 1785 */ 1786 if (next_pindex + next_size > prev_object->size) 1787 prev_object->size = next_pindex + next_size; 1788 return (TRUE); 1789 } 1790 1791 /* 1792 * Make the object writable and flag is being possibly dirty. 1793 * 1794 * No requirements. 1795 */ 1796 void 1797 vm_object_set_writeable_dirty(vm_object_t object) 1798 { 1799 struct vnode *vp; 1800 1801 lwkt_gettoken(&vm_token); 1802 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1803 if (object->type == OBJT_VNODE && 1804 (vp = (struct vnode *)object->handle) != NULL) { 1805 if ((vp->v_flag & VOBJDIRTY) == 0) { 1806 vsetflags(vp, VOBJDIRTY); 1807 } 1808 } 1809 lwkt_reltoken(&vm_token); 1810 } 1811 1812 #include "opt_ddb.h" 1813 #ifdef DDB 1814 #include <sys/kernel.h> 1815 1816 #include <sys/cons.h> 1817 1818 #include <ddb/ddb.h> 1819 1820 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 1821 vm_map_entry_t entry); 1822 static int vm_object_in_map (vm_object_t object); 1823 1824 /* 1825 * The caller must hold vm_token. 1826 */ 1827 static int 1828 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 1829 { 1830 vm_map_t tmpm; 1831 vm_map_entry_t tmpe; 1832 vm_object_t obj; 1833 int entcount; 1834 1835 if (map == 0) 1836 return 0; 1837 if (entry == 0) { 1838 tmpe = map->header.next; 1839 entcount = map->nentries; 1840 while (entcount-- && (tmpe != &map->header)) { 1841 if( _vm_object_in_map(map, object, tmpe)) { 1842 return 1; 1843 } 1844 tmpe = tmpe->next; 1845 } 1846 return (0); 1847 } 1848 switch(entry->maptype) { 1849 case VM_MAPTYPE_SUBMAP: 1850 tmpm = entry->object.sub_map; 1851 tmpe = tmpm->header.next; 1852 entcount = tmpm->nentries; 1853 while (entcount-- && tmpe != &tmpm->header) { 1854 if( _vm_object_in_map(tmpm, object, tmpe)) { 1855 return 1; 1856 } 1857 tmpe = tmpe->next; 1858 } 1859 break; 1860 case VM_MAPTYPE_NORMAL: 1861 case VM_MAPTYPE_VPAGETABLE: 1862 obj = entry->object.vm_object; 1863 while (obj) { 1864 if (obj == object) 1865 return 1; 1866 obj = obj->backing_object; 1867 } 1868 break; 1869 default: 1870 break; 1871 } 1872 return 0; 1873 } 1874 1875 static int vm_object_in_map_callback(struct proc *p, void *data); 1876 1877 struct vm_object_in_map_info { 1878 vm_object_t object; 1879 int rv; 1880 }; 1881 1882 /* 1883 * Debugging only 1884 */ 1885 static int 1886 vm_object_in_map(vm_object_t object) 1887 { 1888 struct vm_object_in_map_info info; 1889 1890 info.rv = 0; 1891 info.object = object; 1892 1893 allproc_scan(vm_object_in_map_callback, &info); 1894 if (info.rv) 1895 return 1; 1896 if( _vm_object_in_map(&kernel_map, object, 0)) 1897 return 1; 1898 if( _vm_object_in_map(&pager_map, object, 0)) 1899 return 1; 1900 if( _vm_object_in_map(&buffer_map, object, 0)) 1901 return 1; 1902 return 0; 1903 } 1904 1905 /* 1906 * Debugging only 1907 */ 1908 static int 1909 vm_object_in_map_callback(struct proc *p, void *data) 1910 { 1911 struct vm_object_in_map_info *info = data; 1912 1913 if (p->p_vmspace) { 1914 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) { 1915 info->rv = 1; 1916 return -1; 1917 } 1918 } 1919 return (0); 1920 } 1921 1922 DB_SHOW_COMMAND(vmochk, vm_object_check) 1923 { 1924 vm_object_t object; 1925 1926 /* 1927 * make sure that internal objs are in a map somewhere 1928 * and none have zero ref counts. 1929 */ 1930 for (object = TAILQ_FIRST(&vm_object_list); 1931 object != NULL; 1932 object = TAILQ_NEXT(object, object_list)) { 1933 if (object->type == OBJT_MARKER) 1934 continue; 1935 if (object->handle == NULL && 1936 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 1937 if (object->ref_count == 0) { 1938 db_printf("vmochk: internal obj has zero ref count: %ld\n", 1939 (long)object->size); 1940 } 1941 if (!vm_object_in_map(object)) { 1942 db_printf( 1943 "vmochk: internal obj is not in a map: " 1944 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 1945 object->ref_count, (u_long)object->size, 1946 (u_long)object->size, 1947 (void *)object->backing_object); 1948 } 1949 } 1950 } 1951 } 1952 1953 /* 1954 * Debugging only 1955 */ 1956 DB_SHOW_COMMAND(object, vm_object_print_static) 1957 { 1958 /* XXX convert args. */ 1959 vm_object_t object = (vm_object_t)addr; 1960 boolean_t full = have_addr; 1961 1962 vm_page_t p; 1963 1964 /* XXX count is an (unused) arg. Avoid shadowing it. */ 1965 #define count was_count 1966 1967 int count; 1968 1969 if (object == NULL) 1970 return; 1971 1972 db_iprintf( 1973 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 1974 object, (int)object->type, (u_long)object->size, 1975 object->resident_page_count, object->ref_count, object->flags); 1976 /* 1977 * XXX no %qd in kernel. Truncate object->backing_object_offset. 1978 */ 1979 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 1980 object->shadow_count, 1981 object->backing_object ? object->backing_object->ref_count : 0, 1982 object->backing_object, (long)object->backing_object_offset); 1983 1984 if (!full) 1985 return; 1986 1987 db_indent += 2; 1988 count = 0; 1989 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) { 1990 if (count == 0) 1991 db_iprintf("memory:="); 1992 else if (count == 6) { 1993 db_printf("\n"); 1994 db_iprintf(" ..."); 1995 count = 0; 1996 } else 1997 db_printf(","); 1998 count++; 1999 2000 db_printf("(off=0x%lx,page=0x%lx)", 2001 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 2002 } 2003 if (count != 0) 2004 db_printf("\n"); 2005 db_indent -= 2; 2006 } 2007 2008 /* XXX. */ 2009 #undef count 2010 2011 /* 2012 * XXX need this non-static entry for calling from vm_map_print. 2013 * 2014 * Debugging only 2015 */ 2016 void 2017 vm_object_print(/* db_expr_t */ long addr, 2018 boolean_t have_addr, 2019 /* db_expr_t */ long count, 2020 char *modif) 2021 { 2022 vm_object_print_static(addr, have_addr, count, modif); 2023 } 2024 2025 /* 2026 * Debugging only 2027 */ 2028 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 2029 { 2030 vm_object_t object; 2031 int nl = 0; 2032 int c; 2033 for (object = TAILQ_FIRST(&vm_object_list); 2034 object != NULL; 2035 object = TAILQ_NEXT(object, object_list)) { 2036 vm_pindex_t idx, fidx; 2037 vm_pindex_t osize; 2038 vm_paddr_t pa = -1, padiff; 2039 int rcount; 2040 vm_page_t m; 2041 2042 if (object->type == OBJT_MARKER) 2043 continue; 2044 db_printf("new object: %p\n", (void *)object); 2045 if ( nl > 18) { 2046 c = cngetc(); 2047 if (c != ' ') 2048 return; 2049 nl = 0; 2050 } 2051 nl++; 2052 rcount = 0; 2053 fidx = 0; 2054 osize = object->size; 2055 if (osize > 128) 2056 osize = 128; 2057 for (idx = 0; idx < osize; idx++) { 2058 m = vm_page_lookup(object, idx); 2059 if (m == NULL) { 2060 if (rcount) { 2061 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2062 (long)fidx, rcount, (long)pa); 2063 if ( nl > 18) { 2064 c = cngetc(); 2065 if (c != ' ') 2066 return; 2067 nl = 0; 2068 } 2069 nl++; 2070 rcount = 0; 2071 } 2072 continue; 2073 } 2074 2075 2076 if (rcount && 2077 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 2078 ++rcount; 2079 continue; 2080 } 2081 if (rcount) { 2082 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 2083 padiff >>= PAGE_SHIFT; 2084 padiff &= PQ_L2_MASK; 2085 if (padiff == 0) { 2086 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 2087 ++rcount; 2088 continue; 2089 } 2090 db_printf(" index(%ld)run(%d)pa(0x%lx)", 2091 (long)fidx, rcount, (long)pa); 2092 db_printf("pd(%ld)\n", (long)padiff); 2093 if ( nl > 18) { 2094 c = cngetc(); 2095 if (c != ' ') 2096 return; 2097 nl = 0; 2098 } 2099 nl++; 2100 } 2101 fidx = idx; 2102 pa = VM_PAGE_TO_PHYS(m); 2103 rcount = 1; 2104 } 2105 if (rcount) { 2106 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2107 (long)fidx, rcount, (long)pa); 2108 if ( nl > 18) { 2109 c = cngetc(); 2110 if (c != ' ') 2111 return; 2112 nl = 0; 2113 } 2114 nl++; 2115 } 2116 } 2117 } 2118 #endif /* DDB */ 2119