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 */ 68 69 /* 70 * Virtual memory object module. 71 */ 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/proc.h> /* for curproc, pageproc */ 76 #include <sys/thread.h> 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 #include <sys/refcount.h> 84 85 #include <vm/vm.h> 86 #include <vm/vm_param.h> 87 #include <vm/pmap.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_object.h> 90 #include <vm/vm_page.h> 91 #include <vm/vm_pageout.h> 92 #include <vm/vm_pager.h> 93 #include <vm/swap_pager.h> 94 #include <vm/vm_kern.h> 95 #include <vm/vm_extern.h> 96 #include <vm/vm_zone.h> 97 98 #define EASY_SCAN_FACTOR 8 99 100 static void vm_object_qcollapse(vm_object_t object, 101 vm_object_t backing_object); 102 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, 103 int pagerflags); 104 static void vm_object_lock_init(vm_object_t); 105 106 107 /* 108 * Virtual memory objects maintain the actual data 109 * associated with allocated virtual memory. A given 110 * page of memory exists within exactly one object. 111 * 112 * An object is only deallocated when all "references" 113 * are given up. Only one "reference" to a given 114 * region of an object should be writeable. 115 * 116 * Associated with each object is a list of all resident 117 * memory pages belonging to that object; this list is 118 * maintained by the "vm_page" module, and locked by the object's 119 * lock. 120 * 121 * Each object also records a "pager" routine which is 122 * used to retrieve (and store) pages to the proper backing 123 * storage. In addition, objects may be backed by other 124 * objects from which they were virtual-copied. 125 * 126 * The only items within the object structure which are 127 * modified after time of creation are: 128 * reference count locked by object's lock 129 * pager routine locked by object's lock 130 * 131 */ 132 133 struct object_q vm_object_list; /* locked by vmobj_token */ 134 struct vm_object kernel_object; 135 136 static long vm_object_count; /* locked by vmobj_token */ 137 extern int vm_pageout_page_count; 138 139 static long object_collapses; 140 static long object_bypasses; 141 static int next_index; 142 static vm_zone_t obj_zone; 143 static struct vm_zone obj_zone_store; 144 #define VM_OBJECTS_INIT 256 145 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 146 147 /* 148 * Misc low level routines 149 */ 150 static void 151 vm_object_lock_init(vm_object_t obj) 152 { 153 #if defined(DEBUG_LOCKS) 154 int i; 155 156 obj->debug_hold_bitmap = 0; 157 obj->debug_hold_ovfl = 0; 158 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 159 obj->debug_hold_thrs[i] = NULL; 160 obj->debug_hold_file[i] = NULL; 161 obj->debug_hold_line[i] = 0; 162 } 163 #endif 164 } 165 166 void 167 vm_object_lock_swap(void) 168 { 169 lwkt_token_swap(); 170 } 171 172 void 173 vm_object_lock(vm_object_t obj) 174 { 175 lwkt_gettoken(&obj->token); 176 } 177 178 /* 179 * Returns TRUE on sucesss 180 */ 181 static int 182 vm_object_lock_try(vm_object_t obj) 183 { 184 return(lwkt_trytoken(&obj->token)); 185 } 186 187 void 188 vm_object_lock_shared(vm_object_t obj) 189 { 190 lwkt_gettoken_shared(&obj->token); 191 } 192 193 void 194 vm_object_unlock(vm_object_t obj) 195 { 196 lwkt_reltoken(&obj->token); 197 } 198 199 static __inline void 200 vm_object_assert_held(vm_object_t obj) 201 { 202 ASSERT_LWKT_TOKEN_HELD(&obj->token); 203 } 204 205 void 206 #ifndef DEBUG_LOCKS 207 vm_object_hold(vm_object_t obj) 208 #else 209 debugvm_object_hold(vm_object_t obj, char *file, int line) 210 #endif 211 { 212 KKASSERT(obj != NULL); 213 214 /* 215 * Object must be held (object allocation is stable due to callers 216 * context, typically already holding the token on a parent object) 217 * prior to potentially blocking on the lock, otherwise the object 218 * can get ripped away from us. 219 */ 220 refcount_acquire(&obj->hold_count); 221 vm_object_lock(obj); 222 223 #if defined(DEBUG_LOCKS) 224 int i; 225 u_int mask; 226 227 for (;;) { 228 mask = ~obj->debug_hold_bitmap; 229 cpu_ccfence(); 230 if (mask == 0xFFFFFFFFU) { 231 if (obj->debug_hold_ovfl == 0) 232 obj->debug_hold_ovfl = 1; 233 break; 234 } 235 i = ffs(mask) - 1; 236 if (atomic_cmpset_int(&obj->debug_hold_bitmap, ~mask, 237 ~mask | (1 << i))) { 238 obj->debug_hold_bitmap |= (1 << i); 239 obj->debug_hold_thrs[i] = curthread; 240 obj->debug_hold_file[i] = file; 241 obj->debug_hold_line[i] = line; 242 break; 243 } 244 } 245 #endif 246 } 247 248 int 249 #ifndef DEBUG_LOCKS 250 vm_object_hold_try(vm_object_t obj) 251 #else 252 debugvm_object_hold_try(vm_object_t obj, char *file, int line) 253 #endif 254 { 255 KKASSERT(obj != NULL); 256 257 /* 258 * Object must be held (object allocation is stable due to callers 259 * context, typically already holding the token on a parent object) 260 * prior to potentially blocking on the lock, otherwise the object 261 * can get ripped away from us. 262 */ 263 refcount_acquire(&obj->hold_count); 264 if (vm_object_lock_try(obj) == 0) { 265 if (refcount_release(&obj->hold_count)) { 266 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) 267 zfree(obj_zone, obj); 268 } 269 return(0); 270 } 271 272 #if defined(DEBUG_LOCKS) 273 int i; 274 u_int mask; 275 276 for (;;) { 277 mask = ~obj->debug_hold_bitmap; 278 cpu_ccfence(); 279 if (mask == 0xFFFFFFFFU) { 280 if (obj->debug_hold_ovfl == 0) 281 obj->debug_hold_ovfl = 1; 282 break; 283 } 284 i = ffs(mask) - 1; 285 if (atomic_cmpset_int(&obj->debug_hold_bitmap, ~mask, 286 ~mask | (1 << i))) { 287 obj->debug_hold_bitmap |= (1 << i); 288 obj->debug_hold_thrs[i] = curthread; 289 obj->debug_hold_file[i] = file; 290 obj->debug_hold_line[i] = line; 291 break; 292 } 293 } 294 #endif 295 return(1); 296 } 297 298 void 299 #ifndef DEBUG_LOCKS 300 vm_object_hold_shared(vm_object_t obj) 301 #else 302 debugvm_object_hold_shared(vm_object_t obj, char *file, int line) 303 #endif 304 { 305 KKASSERT(obj != NULL); 306 307 /* 308 * Object must be held (object allocation is stable due to callers 309 * context, typically already holding the token on a parent object) 310 * prior to potentially blocking on the lock, otherwise the object 311 * can get ripped away from us. 312 */ 313 refcount_acquire(&obj->hold_count); 314 vm_object_lock_shared(obj); 315 316 #if defined(DEBUG_LOCKS) 317 int i; 318 u_int mask; 319 320 for (;;) { 321 mask = ~obj->debug_hold_bitmap; 322 cpu_ccfence(); 323 if (mask == 0xFFFFFFFFU) { 324 if (obj->debug_hold_ovfl == 0) 325 obj->debug_hold_ovfl = 1; 326 break; 327 } 328 i = ffs(mask) - 1; 329 if (atomic_cmpset_int(&obj->debug_hold_bitmap, ~mask, 330 ~mask | (1 << i))) { 331 obj->debug_hold_bitmap |= (1 << i); 332 obj->debug_hold_thrs[i] = curthread; 333 obj->debug_hold_file[i] = file; 334 obj->debug_hold_line[i] = line; 335 break; 336 } 337 } 338 #endif 339 } 340 341 /* 342 * Drop the token and hold_count on the object. 343 */ 344 void 345 vm_object_drop(vm_object_t obj) 346 { 347 if (obj == NULL) 348 return; 349 350 #if defined(DEBUG_LOCKS) 351 int found = 0; 352 int i; 353 354 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 355 if ((obj->debug_hold_bitmap & (1 << i)) && 356 (obj->debug_hold_thrs[i] == curthread)) { 357 obj->debug_hold_bitmap &= ~(1 << i); 358 obj->debug_hold_thrs[i] = NULL; 359 obj->debug_hold_file[i] = NULL; 360 obj->debug_hold_line[i] = 0; 361 found = 1; 362 break; 363 } 364 } 365 366 if (found == 0 && obj->debug_hold_ovfl == 0) 367 panic("vm_object: attempt to drop hold on non-self-held obj"); 368 #endif 369 370 /* 371 * No new holders should be possible once we drop hold_count 1->0 as 372 * there is no longer any way to reference the object. 373 */ 374 KKASSERT(obj->hold_count > 0); 375 if (refcount_release(&obj->hold_count)) { 376 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) { 377 vm_object_unlock(obj); 378 zfree(obj_zone, obj); 379 } else { 380 vm_object_unlock(obj); 381 } 382 } else { 383 vm_object_unlock(obj); 384 } 385 } 386 387 /* 388 * Initialize a freshly allocated object, returning a held object. 389 * 390 * Used only by vm_object_allocate() and zinitna(). 391 * 392 * No requirements. 393 */ 394 void 395 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object) 396 { 397 int incr; 398 399 RB_INIT(&object->rb_memq); 400 LIST_INIT(&object->shadow_head); 401 lwkt_token_init(&object->token, "vmobj"); 402 403 object->type = type; 404 object->size = size; 405 object->ref_count = 1; 406 object->hold_count = 0; 407 object->flags = 0; 408 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 409 vm_object_set_flag(object, OBJ_ONEMAPPING); 410 object->paging_in_progress = 0; 411 object->resident_page_count = 0; 412 object->agg_pv_list_count = 0; 413 object->shadow_count = 0; 414 #ifdef SMP 415 /* cpu localization twist */ 416 object->pg_color = (int)(intptr_t)curthread; 417 #else 418 object->pg_color = next_index; 419 #endif 420 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 421 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 422 else 423 incr = size; 424 next_index = (next_index + incr) & PQ_L2_MASK; 425 object->handle = NULL; 426 object->backing_object = NULL; 427 object->backing_object_offset = (vm_ooffset_t)0; 428 429 object->generation++; 430 object->swblock_count = 0; 431 RB_INIT(&object->swblock_root); 432 vm_object_lock_init(object); 433 434 vm_object_hold(object); 435 lwkt_gettoken(&vmobj_token); 436 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 437 vm_object_count++; 438 lwkt_reltoken(&vmobj_token); 439 } 440 441 /* 442 * Initialize the VM objects module. 443 * 444 * Called from the low level boot code only. 445 */ 446 void 447 vm_object_init(void) 448 { 449 TAILQ_INIT(&vm_object_list); 450 451 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd), 452 &kernel_object); 453 vm_object_drop(&kernel_object); 454 455 obj_zone = &obj_zone_store; 456 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 457 vm_objects_init, VM_OBJECTS_INIT); 458 } 459 460 void 461 vm_object_init2(void) 462 { 463 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 464 } 465 466 /* 467 * Allocate and return a new object of the specified type and size. 468 * 469 * No requirements. 470 */ 471 vm_object_t 472 vm_object_allocate(objtype_t type, vm_pindex_t size) 473 { 474 vm_object_t result; 475 476 result = (vm_object_t) zalloc(obj_zone); 477 478 _vm_object_allocate(type, size, result); 479 vm_object_drop(result); 480 481 return (result); 482 } 483 484 /* 485 * This version returns a held object, allowing further atomic initialization 486 * of the object. 487 */ 488 vm_object_t 489 vm_object_allocate_hold(objtype_t type, vm_pindex_t size) 490 { 491 vm_object_t result; 492 493 result = (vm_object_t) zalloc(obj_zone); 494 495 _vm_object_allocate(type, size, result); 496 497 return (result); 498 } 499 500 /* 501 * Add an additional reference to a vm_object. The object must already be 502 * held. The original non-lock version is no longer supported. The object 503 * must NOT be chain locked by anyone at the time the reference is added. 504 * 505 * Referencing a chain-locked object can blow up the fairly sensitive 506 * ref_count and shadow_count tests in the deallocator. Most callers 507 * will call vm_object_chain_wait() prior to calling 508 * vm_object_reference_locked() to avoid the case. 509 * 510 * The object must be held. 511 */ 512 void 513 vm_object_reference_locked(vm_object_t object) 514 { 515 KKASSERT(object != NULL); 516 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 517 KKASSERT((object->flags & OBJ_CHAINLOCK) == 0); 518 object->ref_count++; 519 if (object->type == OBJT_VNODE) { 520 vref(object->handle); 521 /* XXX what if the vnode is being destroyed? */ 522 } 523 } 524 525 /* 526 * Object OBJ_CHAINLOCK lock handling. 527 * 528 * The caller can chain-lock backing objects recursively and then 529 * use vm_object_chain_release_all() to undo the whole chain. 530 * 531 * Chain locks are used to prevent collapses and are only applicable 532 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations 533 * on other object types are ignored. This is also important because 534 * it allows e.g. the vnode underlying a memory mapping to take concurrent 535 * faults. 536 * 537 * The object must usually be held on entry, though intermediate 538 * objects need not be held on release. 539 */ 540 void 541 vm_object_chain_wait(vm_object_t object) 542 { 543 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 544 while (object->flags & OBJ_CHAINLOCK) { 545 vm_object_set_flag(object, OBJ_CHAINWANT); 546 tsleep(object, 0, "objchain", 0); 547 } 548 } 549 550 void 551 vm_object_chain_acquire(vm_object_t object) 552 { 553 if (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP) { 554 vm_object_chain_wait(object); 555 vm_object_set_flag(object, OBJ_CHAINLOCK); 556 } 557 } 558 559 void 560 vm_object_chain_release(vm_object_t object) 561 { 562 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 563 if (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP) { 564 KKASSERT(object->flags & OBJ_CHAINLOCK); 565 if (object->flags & OBJ_CHAINWANT) { 566 vm_object_clear_flag(object, 567 OBJ_CHAINLOCK | OBJ_CHAINWANT); 568 wakeup(object); 569 } else { 570 vm_object_clear_flag(object, OBJ_CHAINLOCK); 571 } 572 } 573 } 574 575 /* 576 * This releases the entire chain of objects from first_object to and 577 * including stopobj, flowing through object->backing_object. 578 * 579 * We release stopobj first as an optimization as this object is most 580 * likely to be shared across multiple processes. 581 */ 582 void 583 vm_object_chain_release_all(vm_object_t first_object, vm_object_t stopobj) 584 { 585 vm_object_t backing_object; 586 vm_object_t object; 587 588 vm_object_chain_release(stopobj); 589 object = first_object; 590 591 while (object != stopobj) { 592 KKASSERT(object); 593 if (object != first_object) 594 vm_object_hold(object); 595 backing_object = object->backing_object; 596 vm_object_chain_release(object); 597 if (object != first_object) 598 vm_object_drop(object); 599 object = backing_object; 600 } 601 } 602 603 /* 604 * Dereference an object and its underlying vnode. 605 * 606 * The object must be held and will be held on return. 607 */ 608 static void 609 vm_object_vndeallocate(vm_object_t object) 610 { 611 struct vnode *vp = (struct vnode *) object->handle; 612 613 KASSERT(object->type == OBJT_VNODE, 614 ("vm_object_vndeallocate: not a vnode object")); 615 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 616 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 617 #ifdef INVARIANTS 618 if (object->ref_count == 0) { 619 vprint("vm_object_vndeallocate", vp); 620 panic("vm_object_vndeallocate: bad object reference count"); 621 } 622 #endif 623 object->ref_count--; 624 if (object->ref_count == 0) 625 vclrflags(vp, VTEXT); 626 vrele(vp); 627 } 628 629 /* 630 * Release a reference to the specified object, gained either through a 631 * vm_object_allocate or a vm_object_reference call. When all references 632 * are gone, storage associated with this object may be relinquished. 633 * 634 * The caller does not have to hold the object locked but must have control 635 * over the reference in question in order to guarantee that the object 636 * does not get ripped out from under us. 637 */ 638 void 639 vm_object_deallocate(vm_object_t object) 640 { 641 if (object) { 642 vm_object_hold(object); 643 vm_object_deallocate_locked(object); 644 vm_object_drop(object); 645 } 646 } 647 648 void 649 vm_object_deallocate_locked(vm_object_t object) 650 { 651 struct vm_object_dealloc_list *dlist = NULL; 652 struct vm_object_dealloc_list *dtmp; 653 vm_object_t temp; 654 int must_drop = 0; 655 656 /* 657 * We may chain deallocate object, but additional objects may 658 * collect on the dlist which also have to be deallocated. We 659 * must avoid a recursion, vm_object chains can get deep. 660 */ 661 again: 662 while (object != NULL) { 663 #if 0 664 /* 665 * Don't rip a ref_count out from under an object undergoing 666 * collapse, it will confuse the collapse code. 667 */ 668 vm_object_chain_wait(object); 669 #endif 670 if (object->type == OBJT_VNODE) { 671 vm_object_vndeallocate(object); 672 break; 673 } 674 675 if (object->ref_count == 0) { 676 panic("vm_object_deallocate: object deallocated " 677 "too many times: %d", object->type); 678 } 679 if (object->ref_count > 2) { 680 object->ref_count--; 681 break; 682 } 683 684 /* 685 * Here on ref_count of one or two, which are special cases for 686 * objects. 687 * 688 * Nominal ref_count > 1 case if the second ref is not from 689 * a shadow. 690 */ 691 if (object->ref_count == 2 && object->shadow_count == 0) { 692 vm_object_set_flag(object, OBJ_ONEMAPPING); 693 object->ref_count--; 694 break; 695 } 696 697 /* 698 * If the second ref is from a shadow we chain along it 699 * upwards if object's handle is exhausted. 700 * 701 * We have to decrement object->ref_count before potentially 702 * collapsing the first shadow object or the collapse code 703 * will not be able to handle the degenerate case to remove 704 * object. However, if we do it too early the object can 705 * get ripped out from under us. 706 */ 707 if (object->ref_count == 2 && object->shadow_count == 1 && 708 object->handle == NULL && (object->type == OBJT_DEFAULT || 709 object->type == OBJT_SWAP)) { 710 temp = LIST_FIRST(&object->shadow_head); 711 KKASSERT(temp != NULL); 712 vm_object_hold(temp); 713 714 /* 715 * Wait for any paging to complete so the collapse 716 * doesn't (or isn't likely to) qcollapse. pip 717 * waiting must occur before we acquire the 718 * chainlock. 719 */ 720 while ( 721 temp->paging_in_progress || 722 object->paging_in_progress 723 ) { 724 vm_object_pip_wait(temp, "objde1"); 725 vm_object_pip_wait(object, "objde2"); 726 } 727 728 /* 729 * If the parent is locked we have to give up, as 730 * otherwise we would be acquiring locks in the 731 * wrong order and potentially deadlock. 732 */ 733 if (temp->flags & OBJ_CHAINLOCK) { 734 vm_object_drop(temp); 735 goto skip; 736 } 737 vm_object_chain_acquire(temp); 738 739 /* 740 * Recheck/retry after the hold and the paging 741 * wait, both of which can block us. 742 */ 743 if (object->ref_count != 2 || 744 object->shadow_count != 1 || 745 object->handle || 746 LIST_FIRST(&object->shadow_head) != temp || 747 (object->type != OBJT_DEFAULT && 748 object->type != OBJT_SWAP)) { 749 vm_object_chain_release(temp); 750 vm_object_drop(temp); 751 continue; 752 } 753 754 /* 755 * We can safely drop object's ref_count now. 756 */ 757 KKASSERT(object->ref_count == 2); 758 object->ref_count--; 759 760 /* 761 * If our single parent is not collapseable just 762 * decrement ref_count (2->1) and stop. 763 */ 764 if (temp->handle || (temp->type != OBJT_DEFAULT && 765 temp->type != OBJT_SWAP)) { 766 vm_object_chain_release(temp); 767 vm_object_drop(temp); 768 break; 769 } 770 771 /* 772 * At this point we have already dropped object's 773 * ref_count so it is possible for a race to 774 * deallocate obj out from under us. Any collapse 775 * will re-check the situation. We must not block 776 * until we are able to collapse. 777 * 778 * Bump temp's ref_count to avoid an unwanted 779 * degenerate recursion (can't call 780 * vm_object_reference_locked() because it asserts 781 * that CHAINLOCK is not set). 782 */ 783 temp->ref_count++; 784 KKASSERT(temp->ref_count > 1); 785 786 /* 787 * Collapse temp, then deallocate the extra ref 788 * formally. 789 */ 790 vm_object_collapse(temp, &dlist); 791 vm_object_chain_release(temp); 792 if (must_drop) { 793 vm_object_lock_swap(); 794 vm_object_drop(object); 795 } 796 object = temp; 797 must_drop = 1; 798 continue; 799 } 800 801 /* 802 * Drop the ref and handle termination on the 1->0 transition. 803 * We may have blocked above so we have to recheck. 804 */ 805 skip: 806 KKASSERT(object->ref_count != 0); 807 if (object->ref_count >= 2) { 808 object->ref_count--; 809 break; 810 } 811 KKASSERT(object->ref_count == 1); 812 813 /* 814 * 1->0 transition. Chain through the backing_object. 815 * Maintain the ref until we've located the backing object, 816 * then re-check. 817 */ 818 while ((temp = object->backing_object) != NULL) { 819 vm_object_hold(temp); 820 if (temp == object->backing_object) 821 break; 822 vm_object_drop(temp); 823 } 824 825 /* 826 * 1->0 transition verified, retry if ref_count is no longer 827 * 1. Otherwise disconnect the backing_object (temp) and 828 * clean up. 829 */ 830 if (object->ref_count != 1) { 831 vm_object_drop(temp); 832 continue; 833 } 834 835 /* 836 * It shouldn't be possible for the object to be chain locked 837 * if we're removing the last ref on it. 838 */ 839 KKASSERT((object->flags & OBJ_CHAINLOCK) == 0); 840 841 if (temp) { 842 LIST_REMOVE(object, shadow_list); 843 temp->shadow_count--; 844 temp->generation++; 845 object->backing_object = NULL; 846 } 847 848 --object->ref_count; 849 if ((object->flags & OBJ_DEAD) == 0) 850 vm_object_terminate(object); 851 if (must_drop && temp) 852 vm_object_lock_swap(); 853 if (must_drop) 854 vm_object_drop(object); 855 object = temp; 856 must_drop = 1; 857 } 858 if (must_drop && object) 859 vm_object_drop(object); 860 861 /* 862 * Additional tail recursion on dlist. Avoid a recursion. Objects 863 * on the dlist have a hold count but are not locked. 864 */ 865 if ((dtmp = dlist) != NULL) { 866 dlist = dtmp->next; 867 object = dtmp->object; 868 kfree(dtmp, M_TEMP); 869 870 vm_object_lock(object); /* already held, add lock */ 871 must_drop = 1; /* and we're responsible for it */ 872 goto again; 873 } 874 } 875 876 /* 877 * Destroy the specified object, freeing up related resources. 878 * 879 * The object must have zero references. 880 * 881 * The object must held. The caller is responsible for dropping the object 882 * after terminate returns. Terminate does NOT drop the object. 883 */ 884 static int vm_object_terminate_callback(vm_page_t p, void *data); 885 886 void 887 vm_object_terminate(vm_object_t object) 888 { 889 /* 890 * Make sure no one uses us. Once we set OBJ_DEAD we should be 891 * able to safely block. 892 */ 893 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 894 KKASSERT((object->flags & OBJ_DEAD) == 0); 895 vm_object_set_flag(object, OBJ_DEAD); 896 897 /* 898 * Wait for the pageout daemon to be done with the object 899 */ 900 vm_object_pip_wait(object, "objtrm1"); 901 902 KASSERT(!object->paging_in_progress, 903 ("vm_object_terminate: pageout in progress")); 904 905 /* 906 * Clean and free the pages, as appropriate. All references to the 907 * object are gone, so we don't need to lock it. 908 */ 909 if (object->type == OBJT_VNODE) { 910 struct vnode *vp; 911 912 /* 913 * Clean pages and flush buffers. 914 */ 915 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 916 917 vp = (struct vnode *) object->handle; 918 vinvalbuf(vp, V_SAVE, 0, 0); 919 } 920 921 /* 922 * Wait for any I/O to complete, after which there had better not 923 * be any references left on the object. 924 */ 925 vm_object_pip_wait(object, "objtrm2"); 926 927 if (object->ref_count != 0) { 928 panic("vm_object_terminate: object with references, " 929 "ref_count=%d", object->ref_count); 930 } 931 932 /* 933 * Now free any remaining pages. For internal objects, this also 934 * removes them from paging queues. Don't free wired pages, just 935 * remove them from the object. 936 */ 937 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 938 vm_object_terminate_callback, NULL); 939 940 /* 941 * Let the pager know object is dead. 942 */ 943 vm_pager_deallocate(object); 944 945 /* 946 * Wait for the object hold count to hit 1, clean out pages as 947 * we go. vmobj_token interlocks any race conditions that might 948 * pick the object up from the vm_object_list after we have cleared 949 * rb_memq. 950 */ 951 for (;;) { 952 if (RB_ROOT(&object->rb_memq) == NULL) 953 break; 954 kprintf("vm_object_terminate: Warning, object %p " 955 "still has %d pages\n", 956 object, object->resident_page_count); 957 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 958 vm_object_terminate_callback, NULL); 959 } 960 961 /* 962 * There had better not be any pages left 963 */ 964 KKASSERT(object->resident_page_count == 0); 965 966 /* 967 * Remove the object from the global object list. 968 */ 969 lwkt_gettoken(&vmobj_token); 970 TAILQ_REMOVE(&vm_object_list, object, object_list); 971 vm_object_count--; 972 lwkt_reltoken(&vmobj_token); 973 vm_object_dead_wakeup(object); 974 975 if (object->ref_count != 0) { 976 panic("vm_object_terminate2: object with references, " 977 "ref_count=%d", object->ref_count); 978 } 979 980 /* 981 * NOTE: The object hold_count is at least 1, so we cannot zfree() 982 * the object here. See vm_object_drop(). 983 */ 984 } 985 986 /* 987 * The caller must hold the object. 988 */ 989 static int 990 vm_object_terminate_callback(vm_page_t p, void *data __unused) 991 { 992 vm_object_t object; 993 994 object = p->object; 995 vm_page_busy_wait(p, TRUE, "vmpgtrm"); 996 if (object != p->object) { 997 kprintf("vm_object_terminate: Warning: Encountered " 998 "busied page %p on queue %d\n", p, p->queue); 999 vm_page_wakeup(p); 1000 } else if (p->wire_count == 0) { 1001 /* 1002 * NOTE: PG_NEED_COMMIT is ignored. 1003 */ 1004 vm_page_free(p); 1005 mycpu->gd_cnt.v_pfree++; 1006 } else { 1007 if (p->queue != PQ_NONE) 1008 kprintf("vm_object_terminate: Warning: Encountered " 1009 "wired page %p on queue %d\n", p, p->queue); 1010 vm_page_remove(p); 1011 vm_page_wakeup(p); 1012 } 1013 lwkt_yield(); 1014 return(0); 1015 } 1016 1017 /* 1018 * The object is dead but still has an object<->pager association. Sleep 1019 * and return. The caller typically retests the association in a loop. 1020 * 1021 * The caller must hold the object. 1022 */ 1023 void 1024 vm_object_dead_sleep(vm_object_t object, const char *wmesg) 1025 { 1026 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1027 if (object->handle) { 1028 vm_object_set_flag(object, OBJ_DEADWNT); 1029 tsleep(object, 0, wmesg, 0); 1030 /* object may be invalid after this point */ 1031 } 1032 } 1033 1034 /* 1035 * Wakeup anyone waiting for the object<->pager disassociation on 1036 * a dead object. 1037 * 1038 * The caller must hold the object. 1039 */ 1040 void 1041 vm_object_dead_wakeup(vm_object_t object) 1042 { 1043 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1044 if (object->flags & OBJ_DEADWNT) { 1045 vm_object_clear_flag(object, OBJ_DEADWNT); 1046 wakeup(object); 1047 } 1048 } 1049 1050 /* 1051 * Clean all dirty pages in the specified range of object. Leaves page 1052 * on whatever queue it is currently on. If NOSYNC is set then do not 1053 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 1054 * leaving the object dirty. 1055 * 1056 * When stuffing pages asynchronously, allow clustering. XXX we need a 1057 * synchronous clustering mode implementation. 1058 * 1059 * Odd semantics: if start == end, we clean everything. 1060 * 1061 * The object must be locked? XXX 1062 */ 1063 static int vm_object_page_clean_pass1(struct vm_page *p, void *data); 1064 static int vm_object_page_clean_pass2(struct vm_page *p, void *data); 1065 1066 void 1067 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1068 int flags) 1069 { 1070 struct rb_vm_page_scan_info info; 1071 struct vnode *vp; 1072 int wholescan; 1073 int pagerflags; 1074 int generation; 1075 1076 vm_object_hold(object); 1077 if (object->type != OBJT_VNODE || 1078 (object->flags & OBJ_MIGHTBEDIRTY) == 0) { 1079 vm_object_drop(object); 1080 return; 1081 } 1082 1083 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? 1084 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 1085 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 1086 1087 vp = object->handle; 1088 1089 /* 1090 * Interlock other major object operations. This allows us to 1091 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY. 1092 */ 1093 vm_object_set_flag(object, OBJ_CLEANING); 1094 1095 /* 1096 * Handle 'entire object' case 1097 */ 1098 info.start_pindex = start; 1099 if (end == 0) { 1100 info.end_pindex = object->size - 1; 1101 } else { 1102 info.end_pindex = end - 1; 1103 } 1104 wholescan = (start == 0 && info.end_pindex == object->size - 1); 1105 info.limit = flags; 1106 info.pagerflags = pagerflags; 1107 info.object = object; 1108 1109 /* 1110 * If cleaning the entire object do a pass to mark the pages read-only. 1111 * If everything worked out ok, clear OBJ_WRITEABLE and 1112 * OBJ_MIGHTBEDIRTY. 1113 */ 1114 if (wholescan) { 1115 info.error = 0; 1116 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1117 vm_object_page_clean_pass1, &info); 1118 if (info.error == 0) { 1119 vm_object_clear_flag(object, 1120 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1121 if (object->type == OBJT_VNODE && 1122 (vp = (struct vnode *)object->handle) != NULL) { 1123 if (vp->v_flag & VOBJDIRTY) 1124 vclrflags(vp, VOBJDIRTY); 1125 } 1126 } 1127 } 1128 1129 /* 1130 * Do a pass to clean all the dirty pages we find. 1131 */ 1132 do { 1133 info.error = 0; 1134 generation = object->generation; 1135 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1136 vm_object_page_clean_pass2, &info); 1137 } while (info.error || generation != object->generation); 1138 1139 vm_object_clear_flag(object, OBJ_CLEANING); 1140 vm_object_drop(object); 1141 } 1142 1143 /* 1144 * The caller must hold the object. 1145 */ 1146 static 1147 int 1148 vm_object_page_clean_pass1(struct vm_page *p, void *data) 1149 { 1150 struct rb_vm_page_scan_info *info = data; 1151 1152 vm_page_flag_set(p, PG_CLEANCHK); 1153 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 1154 info->error = 1; 1155 } else if (vm_page_busy_try(p, FALSE) == 0) { 1156 vm_page_protect(p, VM_PROT_READ); /* must not block */ 1157 vm_page_wakeup(p); 1158 } else { 1159 info->error = 1; 1160 } 1161 lwkt_yield(); 1162 return(0); 1163 } 1164 1165 /* 1166 * The caller must hold the object 1167 */ 1168 static 1169 int 1170 vm_object_page_clean_pass2(struct vm_page *p, void *data) 1171 { 1172 struct rb_vm_page_scan_info *info = data; 1173 int generation; 1174 1175 /* 1176 * Do not mess with pages that were inserted after we started 1177 * the cleaning pass. 1178 */ 1179 if ((p->flags & PG_CLEANCHK) == 0) 1180 goto done; 1181 1182 generation = info->object->generation; 1183 vm_page_busy_wait(p, TRUE, "vpcwai"); 1184 if (p->object != info->object || 1185 info->object->generation != generation) { 1186 info->error = 1; 1187 vm_page_wakeup(p); 1188 goto done; 1189 } 1190 1191 /* 1192 * Before wasting time traversing the pmaps, check for trivial 1193 * cases where the page cannot be dirty. 1194 */ 1195 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { 1196 KKASSERT((p->dirty & p->valid) == 0); 1197 vm_page_wakeup(p); 1198 goto done; 1199 } 1200 1201 /* 1202 * Check whether the page is dirty or not. The page has been set 1203 * to be read-only so the check will not race a user dirtying the 1204 * page. 1205 */ 1206 vm_page_test_dirty(p); 1207 if ((p->dirty & p->valid) == 0) { 1208 vm_page_flag_clear(p, PG_CLEANCHK); 1209 vm_page_wakeup(p); 1210 goto done; 1211 } 1212 1213 /* 1214 * If we have been asked to skip nosync pages and this is a 1215 * nosync page, skip it. Note that the object flags were 1216 * not cleared in this case (because pass1 will have returned an 1217 * error), so we do not have to set them. 1218 */ 1219 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 1220 vm_page_flag_clear(p, PG_CLEANCHK); 1221 vm_page_wakeup(p); 1222 goto done; 1223 } 1224 1225 /* 1226 * Flush as many pages as we can. PG_CLEANCHK will be cleared on 1227 * the pages that get successfully flushed. Set info->error if 1228 * we raced an object modification. 1229 */ 1230 vm_object_page_collect_flush(info->object, p, info->pagerflags); 1231 vm_wait_nominal(); 1232 done: 1233 lwkt_yield(); 1234 return(0); 1235 } 1236 1237 /* 1238 * Collect the specified page and nearby pages and flush them out. 1239 * The number of pages flushed is returned. The passed page is busied 1240 * by the caller and we are responsible for its disposition. 1241 * 1242 * The caller must hold the object. 1243 */ 1244 static int 1245 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags) 1246 { 1247 int runlen; 1248 int error; 1249 int maxf; 1250 int chkb; 1251 int maxb; 1252 int i; 1253 vm_pindex_t pi; 1254 vm_page_t maf[vm_pageout_page_count]; 1255 vm_page_t mab[vm_pageout_page_count]; 1256 vm_page_t ma[vm_pageout_page_count]; 1257 1258 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1259 1260 pi = p->pindex; 1261 1262 maxf = 0; 1263 for(i = 1; i < vm_pageout_page_count; i++) { 1264 vm_page_t tp; 1265 1266 tp = vm_page_lookup_busy_try(object, pi + i, TRUE, &error); 1267 if (error) 1268 break; 1269 if (tp == NULL) 1270 break; 1271 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 1272 (tp->flags & PG_CLEANCHK) == 0) { 1273 vm_page_wakeup(tp); 1274 break; 1275 } 1276 if ((tp->queue - tp->pc) == PQ_CACHE) { 1277 vm_page_flag_clear(tp, PG_CLEANCHK); 1278 vm_page_wakeup(tp); 1279 break; 1280 } 1281 vm_page_test_dirty(tp); 1282 if ((tp->dirty & tp->valid) == 0) { 1283 vm_page_flag_clear(tp, PG_CLEANCHK); 1284 vm_page_wakeup(tp); 1285 break; 1286 } 1287 maf[i - 1] = tp; 1288 maxf++; 1289 } 1290 1291 maxb = 0; 1292 chkb = vm_pageout_page_count - maxf; 1293 /* 1294 * NOTE: chkb can be 0 1295 */ 1296 for(i = 1; chkb && i < chkb; i++) { 1297 vm_page_t tp; 1298 1299 tp = vm_page_lookup_busy_try(object, pi - i, TRUE, &error); 1300 if (error) 1301 break; 1302 if (tp == NULL) 1303 break; 1304 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 1305 (tp->flags & PG_CLEANCHK) == 0) { 1306 vm_page_wakeup(tp); 1307 break; 1308 } 1309 if ((tp->queue - tp->pc) == PQ_CACHE) { 1310 vm_page_flag_clear(tp, PG_CLEANCHK); 1311 vm_page_wakeup(tp); 1312 break; 1313 } 1314 vm_page_test_dirty(tp); 1315 if ((tp->dirty & tp->valid) == 0) { 1316 vm_page_flag_clear(tp, PG_CLEANCHK); 1317 vm_page_wakeup(tp); 1318 break; 1319 } 1320 mab[i - 1] = tp; 1321 maxb++; 1322 } 1323 1324 /* 1325 * All pages in the maf[] and mab[] array are busied. 1326 */ 1327 for (i = 0; i < maxb; i++) { 1328 int index = (maxb - i) - 1; 1329 ma[index] = mab[i]; 1330 vm_page_flag_clear(ma[index], PG_CLEANCHK); 1331 } 1332 vm_page_flag_clear(p, PG_CLEANCHK); 1333 ma[maxb] = p; 1334 for(i = 0; i < maxf; i++) { 1335 int index = (maxb + i) + 1; 1336 ma[index] = maf[i]; 1337 vm_page_flag_clear(ma[index], PG_CLEANCHK); 1338 } 1339 runlen = maxb + maxf + 1; 1340 1341 for (i = 0; i < runlen; i++) 1342 vm_page_hold(ma[i]); 1343 1344 vm_pageout_flush(ma, runlen, pagerflags); 1345 1346 for (i = 0; i < runlen; i++) { 1347 if (ma[i]->valid & ma[i]->dirty) { 1348 vm_page_protect(ma[i], VM_PROT_READ); 1349 vm_page_flag_set(ma[i], PG_CLEANCHK); 1350 1351 /* 1352 * maxf will end up being the actual number of pages 1353 * we wrote out contiguously, non-inclusive of the 1354 * first page. We do not count look-behind pages. 1355 */ 1356 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 1357 maxf = i - maxb - 1; 1358 } 1359 vm_page_unhold(ma[i]); 1360 } 1361 return(maxf + 1); 1362 } 1363 1364 /* 1365 * Same as vm_object_pmap_copy, except range checking really 1366 * works, and is meant for small sections of an object. 1367 * 1368 * This code protects resident pages by making them read-only 1369 * and is typically called on a fork or split when a page 1370 * is converted to copy-on-write. 1371 * 1372 * NOTE: If the page is already at VM_PROT_NONE, calling 1373 * vm_page_protect will have no effect. 1374 */ 1375 void 1376 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 1377 { 1378 vm_pindex_t idx; 1379 vm_page_t p; 1380 1381 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 1382 return; 1383 1384 vm_object_hold(object); 1385 for (idx = start; idx < end; idx++) { 1386 p = vm_page_lookup(object, idx); 1387 if (p == NULL) 1388 continue; 1389 vm_page_protect(p, VM_PROT_READ); 1390 } 1391 vm_object_drop(object); 1392 } 1393 1394 /* 1395 * Removes all physical pages in the specified object range from all 1396 * physical maps. 1397 * 1398 * The object must *not* be locked. 1399 */ 1400 1401 static int vm_object_pmap_remove_callback(vm_page_t p, void *data); 1402 1403 void 1404 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 1405 { 1406 struct rb_vm_page_scan_info info; 1407 1408 if (object == NULL) 1409 return; 1410 info.start_pindex = start; 1411 info.end_pindex = end - 1; 1412 1413 vm_object_hold(object); 1414 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1415 vm_object_pmap_remove_callback, &info); 1416 if (start == 0 && end == object->size) 1417 vm_object_clear_flag(object, OBJ_WRITEABLE); 1418 vm_object_drop(object); 1419 } 1420 1421 /* 1422 * The caller must hold the object 1423 */ 1424 static int 1425 vm_object_pmap_remove_callback(vm_page_t p, void *data __unused) 1426 { 1427 vm_page_protect(p, VM_PROT_NONE); 1428 return(0); 1429 } 1430 1431 /* 1432 * Implements the madvise function at the object/page level. 1433 * 1434 * MADV_WILLNEED (any object) 1435 * 1436 * Activate the specified pages if they are resident. 1437 * 1438 * MADV_DONTNEED (any object) 1439 * 1440 * Deactivate the specified pages if they are resident. 1441 * 1442 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only) 1443 * 1444 * Deactivate and clean the specified pages if they are 1445 * resident. This permits the process to reuse the pages 1446 * without faulting or the kernel to reclaim the pages 1447 * without I/O. 1448 * 1449 * No requirements. 1450 */ 1451 void 1452 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise) 1453 { 1454 vm_pindex_t end, tpindex; 1455 vm_object_t tobject; 1456 vm_object_t xobj; 1457 vm_page_t m; 1458 int error; 1459 1460 if (object == NULL) 1461 return; 1462 1463 end = pindex + count; 1464 1465 vm_object_hold(object); 1466 tobject = object; 1467 1468 /* 1469 * Locate and adjust resident pages 1470 */ 1471 for (; pindex < end; pindex += 1) { 1472 relookup: 1473 if (tobject != object) 1474 vm_object_drop(tobject); 1475 tobject = object; 1476 tpindex = pindex; 1477 shadowlookup: 1478 /* 1479 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 1480 * and those pages must be OBJ_ONEMAPPING. 1481 */ 1482 if (advise == MADV_FREE) { 1483 if ((tobject->type != OBJT_DEFAULT && 1484 tobject->type != OBJT_SWAP) || 1485 (tobject->flags & OBJ_ONEMAPPING) == 0) { 1486 continue; 1487 } 1488 } 1489 1490 m = vm_page_lookup_busy_try(tobject, tpindex, TRUE, &error); 1491 1492 if (error) { 1493 vm_page_sleep_busy(m, TRUE, "madvpo"); 1494 goto relookup; 1495 } 1496 if (m == NULL) { 1497 /* 1498 * There may be swap even if there is no backing page 1499 */ 1500 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1501 swap_pager_freespace(tobject, tpindex, 1); 1502 1503 /* 1504 * next object 1505 */ 1506 while ((xobj = tobject->backing_object) != NULL) { 1507 KKASSERT(xobj != object); 1508 vm_object_hold(xobj); 1509 if (xobj == tobject->backing_object) 1510 break; 1511 vm_object_drop(xobj); 1512 } 1513 if (xobj == NULL) 1514 continue; 1515 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1516 if (tobject != object) { 1517 vm_object_lock_swap(); 1518 vm_object_drop(tobject); 1519 } 1520 tobject = xobj; 1521 goto shadowlookup; 1522 } 1523 1524 /* 1525 * If the page is not in a normal active state, we skip it. 1526 * If the page is not managed there are no page queues to 1527 * mess with. Things can break if we mess with pages in 1528 * any of the below states. 1529 */ 1530 if (m->wire_count || 1531 (m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1532 m->valid != VM_PAGE_BITS_ALL 1533 ) { 1534 vm_page_wakeup(m); 1535 continue; 1536 } 1537 1538 /* 1539 * Theoretically once a page is known not to be busy, an 1540 * interrupt cannot come along and rip it out from under us. 1541 */ 1542 1543 if (advise == MADV_WILLNEED) { 1544 vm_page_activate(m); 1545 } else if (advise == MADV_DONTNEED) { 1546 vm_page_dontneed(m); 1547 } else if (advise == MADV_FREE) { 1548 /* 1549 * Mark the page clean. This will allow the page 1550 * to be freed up by the system. However, such pages 1551 * are often reused quickly by malloc()/free() 1552 * so we do not do anything that would cause 1553 * a page fault if we can help it. 1554 * 1555 * Specifically, we do not try to actually free 1556 * the page now nor do we try to put it in the 1557 * cache (which would cause a page fault on reuse). 1558 * 1559 * But we do make the page is freeable as we 1560 * can without actually taking the step of unmapping 1561 * it. 1562 */ 1563 pmap_clear_modify(m); 1564 m->dirty = 0; 1565 m->act_count = 0; 1566 vm_page_dontneed(m); 1567 if (tobject->type == OBJT_SWAP) 1568 swap_pager_freespace(tobject, tpindex, 1); 1569 } 1570 vm_page_wakeup(m); 1571 } 1572 if (tobject != object) 1573 vm_object_drop(tobject); 1574 vm_object_drop(object); 1575 } 1576 1577 /* 1578 * Create a new object which is backed by the specified existing object 1579 * range. Replace the pointer and offset that was pointing at the existing 1580 * object with the pointer/offset for the new object. 1581 * 1582 * No other requirements. 1583 */ 1584 void 1585 vm_object_shadow(vm_object_t *objectp, vm_ooffset_t *offset, vm_size_t length, 1586 int addref) 1587 { 1588 vm_object_t source; 1589 vm_object_t result; 1590 1591 source = *objectp; 1592 1593 /* 1594 * Don't create the new object if the old object isn't shared. 1595 * We have to chain wait before adding the reference to avoid 1596 * racing a collapse or deallocation. 1597 * 1598 * Add the additional ref to source here to avoid racing a later 1599 * collapse or deallocation. Clear the ONEMAPPING flag whether 1600 * addref is TRUE or not in this case because the original object 1601 * will be shadowed. 1602 */ 1603 if (source) { 1604 vm_object_hold(source); 1605 vm_object_chain_wait(source); 1606 if (source->ref_count == 1 && 1607 source->handle == NULL && 1608 (source->type == OBJT_DEFAULT || 1609 source->type == OBJT_SWAP)) { 1610 vm_object_drop(source); 1611 if (addref) { 1612 vm_object_reference_locked(source); 1613 vm_object_clear_flag(source, OBJ_ONEMAPPING); 1614 } 1615 return; 1616 } 1617 vm_object_reference_locked(source); 1618 vm_object_clear_flag(source, OBJ_ONEMAPPING); 1619 } 1620 1621 /* 1622 * Allocate a new object with the given length. The new object 1623 * is returned referenced but we may have to add another one. 1624 * If we are adding a second reference we must clear OBJ_ONEMAPPING. 1625 * (typically because the caller is about to clone a vm_map_entry). 1626 * 1627 * The source object currently has an extra reference to prevent 1628 * collapses into it while we mess with its shadow list, which 1629 * we will remove later in this routine. 1630 */ 1631 if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) 1632 panic("vm_object_shadow: no object for shadowing"); 1633 vm_object_hold(result); 1634 if (addref) { 1635 vm_object_reference_locked(result); 1636 vm_object_clear_flag(result, OBJ_ONEMAPPING); 1637 } 1638 1639 /* 1640 * The new object shadows the source object. Chain wait before 1641 * adjusting shadow_count or the shadow list to avoid races. 1642 * 1643 * Try to optimize the result object's page color when shadowing 1644 * in order to maintain page coloring consistency in the combined 1645 * shadowed object. 1646 */ 1647 KKASSERT(result->backing_object == NULL); 1648 result->backing_object = source; 1649 if (source) { 1650 vm_object_chain_wait(source); 1651 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); 1652 source->shadow_count++; 1653 source->generation++; 1654 #ifdef SMP 1655 /* cpu localization twist */ 1656 result->pg_color = (int)(intptr_t)curthread; 1657 #else 1658 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & 1659 PQ_L2_MASK; 1660 #endif 1661 } 1662 1663 /* 1664 * Adjust the return storage. Drop the ref on source before 1665 * returning. 1666 */ 1667 result->backing_object_offset = *offset; 1668 vm_object_drop(result); 1669 *offset = 0; 1670 if (source) { 1671 vm_object_deallocate_locked(source); 1672 vm_object_drop(source); 1673 } 1674 1675 /* 1676 * Return the new things 1677 */ 1678 *objectp = result; 1679 } 1680 1681 #define OBSC_TEST_ALL_SHADOWED 0x0001 1682 #define OBSC_COLLAPSE_NOWAIT 0x0002 1683 #define OBSC_COLLAPSE_WAIT 0x0004 1684 1685 static int vm_object_backing_scan_callback(vm_page_t p, void *data); 1686 1687 /* 1688 * The caller must hold the object. 1689 */ 1690 static __inline int 1691 vm_object_backing_scan(vm_object_t object, vm_object_t backing_object, int op) 1692 { 1693 struct rb_vm_page_scan_info info; 1694 1695 vm_object_assert_held(object); 1696 vm_object_assert_held(backing_object); 1697 1698 KKASSERT(backing_object == object->backing_object); 1699 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1700 1701 /* 1702 * Initial conditions 1703 */ 1704 if (op & OBSC_TEST_ALL_SHADOWED) { 1705 /* 1706 * We do not want to have to test for the existence of 1707 * swap pages in the backing object. XXX but with the 1708 * new swapper this would be pretty easy to do. 1709 * 1710 * XXX what about anonymous MAP_SHARED memory that hasn't 1711 * been ZFOD faulted yet? If we do not test for this, the 1712 * shadow test may succeed! XXX 1713 */ 1714 if (backing_object->type != OBJT_DEFAULT) 1715 return(0); 1716 } 1717 if (op & OBSC_COLLAPSE_WAIT) { 1718 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 1719 vm_object_set_flag(backing_object, OBJ_DEAD); 1720 lwkt_gettoken(&vmobj_token); 1721 TAILQ_REMOVE(&vm_object_list, backing_object, object_list); 1722 vm_object_count--; 1723 lwkt_reltoken(&vmobj_token); 1724 vm_object_dead_wakeup(backing_object); 1725 } 1726 1727 /* 1728 * Our scan. We have to retry if a negative error code is returned, 1729 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that 1730 * the scan had to be stopped because the parent does not completely 1731 * shadow the child. 1732 */ 1733 info.object = object; 1734 info.backing_object = backing_object; 1735 info.limit = op; 1736 do { 1737 info.error = 1; 1738 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL, 1739 vm_object_backing_scan_callback, 1740 &info); 1741 } while (info.error < 0); 1742 1743 return(info.error); 1744 } 1745 1746 /* 1747 * The caller must hold the object. 1748 */ 1749 static int 1750 vm_object_backing_scan_callback(vm_page_t p, void *data) 1751 { 1752 struct rb_vm_page_scan_info *info = data; 1753 vm_object_t backing_object; 1754 vm_object_t object; 1755 vm_pindex_t pindex; 1756 vm_pindex_t new_pindex; 1757 vm_pindex_t backing_offset_index; 1758 int op; 1759 1760 pindex = p->pindex; 1761 new_pindex = pindex - info->backing_offset_index; 1762 op = info->limit; 1763 object = info->object; 1764 backing_object = info->backing_object; 1765 backing_offset_index = info->backing_offset_index; 1766 1767 if (op & OBSC_TEST_ALL_SHADOWED) { 1768 vm_page_t pp; 1769 1770 /* 1771 * Ignore pages outside the parent object's range 1772 * and outside the parent object's mapping of the 1773 * backing object. 1774 * 1775 * note that we do not busy the backing object's 1776 * page. 1777 */ 1778 if (pindex < backing_offset_index || 1779 new_pindex >= object->size 1780 ) { 1781 return(0); 1782 } 1783 1784 /* 1785 * See if the parent has the page or if the parent's 1786 * object pager has the page. If the parent has the 1787 * page but the page is not valid, the parent's 1788 * object pager must have the page. 1789 * 1790 * If this fails, the parent does not completely shadow 1791 * the object and we might as well give up now. 1792 */ 1793 pp = vm_page_lookup(object, new_pindex); 1794 if ((pp == NULL || pp->valid == 0) && 1795 !vm_pager_has_page(object, new_pindex) 1796 ) { 1797 info->error = 0; /* problemo */ 1798 return(-1); /* stop the scan */ 1799 } 1800 } 1801 1802 /* 1803 * Check for busy page. Note that we may have lost (p) when we 1804 * possibly blocked above. 1805 */ 1806 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1807 vm_page_t pp; 1808 1809 if (vm_page_busy_try(p, TRUE)) { 1810 if (op & OBSC_COLLAPSE_NOWAIT) { 1811 return(0); 1812 } else { 1813 /* 1814 * If we slept, anything could have 1815 * happened. Ask that the scan be restarted. 1816 * 1817 * Since the object is marked dead, the 1818 * backing offset should not have changed. 1819 */ 1820 vm_page_sleep_busy(p, TRUE, "vmocol"); 1821 info->error = -1; 1822 return(-1); 1823 } 1824 } 1825 1826 /* 1827 * If (p) is no longer valid restart the scan. 1828 */ 1829 if (p->object != backing_object || p->pindex != pindex) { 1830 kprintf("vm_object_backing_scan: Warning: page " 1831 "%p ripped out from under us\n", p); 1832 vm_page_wakeup(p); 1833 info->error = -1; 1834 return(-1); 1835 } 1836 1837 if (op & OBSC_COLLAPSE_NOWAIT) { 1838 if (p->valid == 0 || 1839 p->wire_count || 1840 (p->flags & PG_NEED_COMMIT)) { 1841 vm_page_wakeup(p); 1842 return(0); 1843 } 1844 } else { 1845 /* XXX what if p->valid == 0 , hold_count, etc? */ 1846 } 1847 1848 KASSERT( 1849 p->object == backing_object, 1850 ("vm_object_qcollapse(): object mismatch") 1851 ); 1852 1853 /* 1854 * Destroy any associated swap 1855 */ 1856 if (backing_object->type == OBJT_SWAP) 1857 swap_pager_freespace(backing_object, p->pindex, 1); 1858 1859 if ( 1860 p->pindex < backing_offset_index || 1861 new_pindex >= object->size 1862 ) { 1863 /* 1864 * Page is out of the parent object's range, we 1865 * can simply destroy it. 1866 */ 1867 vm_page_protect(p, VM_PROT_NONE); 1868 vm_page_free(p); 1869 return(0); 1870 } 1871 1872 pp = vm_page_lookup(object, new_pindex); 1873 if (pp != NULL || vm_pager_has_page(object, new_pindex)) { 1874 /* 1875 * page already exists in parent OR swap exists 1876 * for this location in the parent. Destroy 1877 * the original page from the backing object. 1878 * 1879 * Leave the parent's page alone 1880 */ 1881 vm_page_protect(p, VM_PROT_NONE); 1882 vm_page_free(p); 1883 return(0); 1884 } 1885 1886 /* 1887 * Page does not exist in parent, rename the 1888 * page from the backing object to the main object. 1889 * 1890 * If the page was mapped to a process, it can remain 1891 * mapped through the rename. 1892 */ 1893 if ((p->queue - p->pc) == PQ_CACHE) 1894 vm_page_deactivate(p); 1895 1896 vm_page_rename(p, object, new_pindex); 1897 vm_page_wakeup(p); 1898 /* page automatically made dirty by rename */ 1899 } 1900 return(0); 1901 } 1902 1903 /* 1904 * This version of collapse allows the operation to occur earlier and 1905 * when paging_in_progress is true for an object... This is not a complete 1906 * operation, but should plug 99.9% of the rest of the leaks. 1907 * 1908 * The caller must hold the object and backing_object and both must be 1909 * chainlocked. 1910 * 1911 * (only called from vm_object_collapse) 1912 */ 1913 static void 1914 vm_object_qcollapse(vm_object_t object, vm_object_t backing_object) 1915 { 1916 if (backing_object->ref_count == 1) { 1917 backing_object->ref_count += 2; 1918 vm_object_backing_scan(object, backing_object, 1919 OBSC_COLLAPSE_NOWAIT); 1920 backing_object->ref_count -= 2; 1921 } 1922 } 1923 1924 /* 1925 * Collapse an object with the object backing it. Pages in the backing 1926 * object are moved into the parent, and the backing object is deallocated. 1927 * Any conflict is resolved in favor of the parent's existing pages. 1928 * 1929 * object must be held and chain-locked on call. 1930 * 1931 * The caller must have an extra ref on object to prevent a race from 1932 * destroying it during the collapse. 1933 */ 1934 void 1935 vm_object_collapse(vm_object_t object, struct vm_object_dealloc_list **dlistp) 1936 { 1937 struct vm_object_dealloc_list *dlist = NULL; 1938 vm_object_t backing_object; 1939 1940 /* 1941 * Only one thread is attempting a collapse at any given moment. 1942 * There are few restrictions for (object) that callers of this 1943 * function check so reentrancy is likely. 1944 */ 1945 KKASSERT(object != NULL); 1946 vm_object_assert_held(object); 1947 KKASSERT(object->flags & OBJ_CHAINLOCK); 1948 1949 for (;;) { 1950 vm_object_t bbobj; 1951 int dodealloc; 1952 1953 /* 1954 * We have to hold the backing object, check races. 1955 */ 1956 while ((backing_object = object->backing_object) != NULL) { 1957 vm_object_hold(backing_object); 1958 if (backing_object == object->backing_object) 1959 break; 1960 vm_object_drop(backing_object); 1961 } 1962 1963 /* 1964 * No backing object? Nothing to collapse then. 1965 */ 1966 if (backing_object == NULL) 1967 break; 1968 1969 /* 1970 * You can't collapse with a non-default/non-swap object. 1971 */ 1972 if (backing_object->type != OBJT_DEFAULT && 1973 backing_object->type != OBJT_SWAP) { 1974 vm_object_drop(backing_object); 1975 backing_object = NULL; 1976 break; 1977 } 1978 1979 /* 1980 * Chain-lock the backing object too because if we 1981 * successfully merge its pages into the top object we 1982 * will collapse backing_object->backing_object as the 1983 * new backing_object. Re-check that it is still our 1984 * backing object. 1985 */ 1986 vm_object_chain_acquire(backing_object); 1987 if (backing_object != object->backing_object) { 1988 vm_object_chain_release(backing_object); 1989 vm_object_drop(backing_object); 1990 continue; 1991 } 1992 1993 /* 1994 * we check the backing object first, because it is most likely 1995 * not collapsable. 1996 */ 1997 if (backing_object->handle != NULL || 1998 (backing_object->type != OBJT_DEFAULT && 1999 backing_object->type != OBJT_SWAP) || 2000 (backing_object->flags & OBJ_DEAD) || 2001 object->handle != NULL || 2002 (object->type != OBJT_DEFAULT && 2003 object->type != OBJT_SWAP) || 2004 (object->flags & OBJ_DEAD)) { 2005 break; 2006 } 2007 2008 /* 2009 * If paging is in progress we can't do a normal collapse. 2010 */ 2011 if ( 2012 object->paging_in_progress != 0 || 2013 backing_object->paging_in_progress != 0 2014 ) { 2015 vm_object_qcollapse(object, backing_object); 2016 break; 2017 } 2018 2019 /* 2020 * We know that we can either collapse the backing object (if 2021 * the parent is the only reference to it) or (perhaps) have 2022 * the parent bypass the object if the parent happens to shadow 2023 * all the resident pages in the entire backing object. 2024 * 2025 * This is ignoring pager-backed pages such as swap pages. 2026 * vm_object_backing_scan fails the shadowing test in this 2027 * case. 2028 */ 2029 if (backing_object->ref_count == 1) { 2030 /* 2031 * If there is exactly one reference to the backing 2032 * object, we can collapse it into the parent. 2033 */ 2034 KKASSERT(object->backing_object == backing_object); 2035 vm_object_backing_scan(object, backing_object, 2036 OBSC_COLLAPSE_WAIT); 2037 2038 /* 2039 * Move the pager from backing_object to object. 2040 */ 2041 if (backing_object->type == OBJT_SWAP) { 2042 vm_object_pip_add(backing_object, 1); 2043 2044 /* 2045 * scrap the paging_offset junk and do a 2046 * discrete copy. This also removes major 2047 * assumptions about how the swap-pager 2048 * works from where it doesn't belong. The 2049 * new swapper is able to optimize the 2050 * destroy-source case. 2051 */ 2052 vm_object_pip_add(object, 1); 2053 swap_pager_copy(backing_object, object, 2054 OFF_TO_IDX(object->backing_object_offset), 2055 TRUE); 2056 vm_object_pip_wakeup(object); 2057 vm_object_pip_wakeup(backing_object); 2058 } 2059 2060 /* 2061 * Object now shadows whatever backing_object did. 2062 * Remove object from backing_object's shadow_list. 2063 */ 2064 LIST_REMOVE(object, shadow_list); 2065 KKASSERT(object->backing_object == backing_object); 2066 backing_object->shadow_count--; 2067 backing_object->generation++; 2068 2069 /* 2070 * backing_object->backing_object moves from within 2071 * backing_object to within object. 2072 */ 2073 while ((bbobj = backing_object->backing_object) != NULL) { 2074 vm_object_hold(bbobj); 2075 if (bbobj == backing_object->backing_object) 2076 break; 2077 vm_object_drop(bbobj); 2078 } 2079 if (bbobj) { 2080 LIST_REMOVE(backing_object, shadow_list); 2081 bbobj->shadow_count--; 2082 bbobj->generation++; 2083 backing_object->backing_object = NULL; 2084 } 2085 object->backing_object = bbobj; 2086 if (bbobj) { 2087 LIST_INSERT_HEAD(&bbobj->shadow_head, 2088 object, shadow_list); 2089 bbobj->shadow_count++; 2090 bbobj->generation++; 2091 } 2092 2093 object->backing_object_offset += 2094 backing_object->backing_object_offset; 2095 2096 vm_object_drop(bbobj); 2097 2098 /* 2099 * Discard the old backing_object. Nothing should be 2100 * able to ref it, other than a vm_map_split(), 2101 * and vm_map_split() will stall on our chain lock. 2102 * And we control the parent so it shouldn't be 2103 * possible for it to go away either. 2104 * 2105 * Since the backing object has no pages, no pager 2106 * left, and no object references within it, all 2107 * that is necessary is to dispose of it. 2108 */ 2109 KASSERT(backing_object->ref_count == 1, 2110 ("backing_object %p was somehow " 2111 "re-referenced during collapse!", 2112 backing_object)); 2113 KASSERT(RB_EMPTY(&backing_object->rb_memq), 2114 ("backing_object %p somehow has left " 2115 "over pages during collapse!", 2116 backing_object)); 2117 2118 /* 2119 * The object can be destroyed. 2120 * 2121 * XXX just fall through and dodealloc instead 2122 * of forcing destruction? 2123 */ 2124 --backing_object->ref_count; 2125 if ((backing_object->flags & OBJ_DEAD) == 0) 2126 vm_object_terminate(backing_object); 2127 object_collapses++; 2128 dodealloc = 0; 2129 } else { 2130 /* 2131 * If we do not entirely shadow the backing object, 2132 * there is nothing we can do so we give up. 2133 */ 2134 if (vm_object_backing_scan(object, backing_object, 2135 OBSC_TEST_ALL_SHADOWED) == 0) { 2136 break; 2137 } 2138 2139 /* 2140 * bbobj is backing_object->backing_object. Since 2141 * object completely shadows backing_object we can 2142 * bypass it and become backed by bbobj instead. 2143 */ 2144 while ((bbobj = backing_object->backing_object) != NULL) { 2145 vm_object_hold(bbobj); 2146 if (bbobj == backing_object->backing_object) 2147 break; 2148 vm_object_drop(bbobj); 2149 } 2150 2151 /* 2152 * Make object shadow bbobj instead of backing_object. 2153 * Remove object from backing_object's shadow list. 2154 * 2155 * Deallocating backing_object will not remove 2156 * it, since its reference count is at least 2. 2157 */ 2158 KKASSERT(object->backing_object == backing_object); 2159 LIST_REMOVE(object, shadow_list); 2160 backing_object->shadow_count--; 2161 backing_object->generation++; 2162 2163 /* 2164 * Add a ref to bbobj, bbobj now shadows object. 2165 * 2166 * NOTE: backing_object->backing_object still points 2167 * to bbobj. That relationship remains intact 2168 * because backing_object has > 1 ref, so 2169 * someone else is pointing to it (hence why 2170 * we can't collapse it into object and can 2171 * only handle the all-shadowed bypass case). 2172 */ 2173 if (bbobj) { 2174 vm_object_chain_wait(bbobj); 2175 vm_object_reference_locked(bbobj); 2176 LIST_INSERT_HEAD(&bbobj->shadow_head, 2177 object, shadow_list); 2178 bbobj->shadow_count++; 2179 bbobj->generation++; 2180 object->backing_object_offset += 2181 backing_object->backing_object_offset; 2182 object->backing_object = bbobj; 2183 vm_object_drop(bbobj); 2184 } else { 2185 object->backing_object = NULL; 2186 } 2187 2188 /* 2189 * Drop the reference count on backing_object. To 2190 * handle ref_count races properly we can't assume 2191 * that the ref_count is still at least 2 so we 2192 * have to actually call vm_object_deallocate() 2193 * (after clearing the chainlock). 2194 */ 2195 object_bypasses++; 2196 dodealloc = 1; 2197 } 2198 2199 /* 2200 * Ok, we want to loop on the new object->bbobj association, 2201 * possibly collapsing it further. However if dodealloc is 2202 * non-zero we have to deallocate the backing_object which 2203 * itself can potentially undergo a collapse, creating a 2204 * recursion depth issue with the LWKT token subsystem. 2205 * 2206 * In the case where we must deallocate the backing_object 2207 * it is possible now that the backing_object has a single 2208 * shadow count on some other object (not represented here 2209 * as yet), since it no longer shadows us. Thus when we 2210 * call vm_object_deallocate() it may attempt to collapse 2211 * itself into its remaining parent. 2212 */ 2213 if (dodealloc) { 2214 struct vm_object_dealloc_list *dtmp; 2215 2216 vm_object_chain_release(backing_object); 2217 vm_object_unlock(backing_object); 2218 /* backing_object remains held */ 2219 2220 /* 2221 * Auto-deallocation list for caller convenience. 2222 */ 2223 if (dlistp == NULL) 2224 dlistp = &dlist; 2225 2226 dtmp = kmalloc(sizeof(*dtmp), M_TEMP, M_WAITOK); 2227 dtmp->object = backing_object; 2228 dtmp->next = *dlistp; 2229 *dlistp = dtmp; 2230 } else { 2231 vm_object_chain_release(backing_object); 2232 vm_object_drop(backing_object); 2233 } 2234 /* backing_object = NULL; not needed */ 2235 /* loop */ 2236 } 2237 2238 /* 2239 * Clean up any left over backing_object 2240 */ 2241 if (backing_object) { 2242 vm_object_chain_release(backing_object); 2243 vm_object_drop(backing_object); 2244 } 2245 2246 /* 2247 * Clean up any auto-deallocation list. This is a convenience 2248 * for top-level callers so they don't have to pass &dlist. 2249 * Do not clean up any caller-passed dlistp, the caller will 2250 * do that. 2251 */ 2252 if (dlist) 2253 vm_object_deallocate_list(&dlist); 2254 2255 } 2256 2257 /* 2258 * vm_object_collapse() may collect additional objects in need of 2259 * deallocation. This routine deallocates these objects. The 2260 * deallocation itself can trigger additional collapses (which the 2261 * deallocate function takes care of). This procedure is used to 2262 * reduce procedural recursion since these vm_object shadow chains 2263 * can become quite long. 2264 */ 2265 void 2266 vm_object_deallocate_list(struct vm_object_dealloc_list **dlistp) 2267 { 2268 struct vm_object_dealloc_list *dlist; 2269 2270 while ((dlist = *dlistp) != NULL) { 2271 *dlistp = dlist->next; 2272 vm_object_lock(dlist->object); 2273 vm_object_deallocate_locked(dlist->object); 2274 vm_object_drop(dlist->object); 2275 kfree(dlist, M_TEMP); 2276 } 2277 } 2278 2279 /* 2280 * Removes all physical pages in the specified object range from the 2281 * object's list of pages. 2282 * 2283 * No requirements. 2284 */ 2285 static int vm_object_page_remove_callback(vm_page_t p, void *data); 2286 2287 void 2288 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 2289 boolean_t clean_only) 2290 { 2291 struct rb_vm_page_scan_info info; 2292 int all; 2293 2294 /* 2295 * Degenerate cases and assertions 2296 */ 2297 vm_object_hold(object); 2298 if (object == NULL || 2299 (object->resident_page_count == 0 && object->swblock_count == 0)) { 2300 vm_object_drop(object); 2301 return; 2302 } 2303 KASSERT(object->type != OBJT_PHYS, 2304 ("attempt to remove pages from a physical object")); 2305 2306 /* 2307 * Indicate that paging is occuring on the object 2308 */ 2309 vm_object_pip_add(object, 1); 2310 2311 /* 2312 * Figure out the actual removal range and whether we are removing 2313 * the entire contents of the object or not. If removing the entire 2314 * contents, be sure to get all pages, even those that might be 2315 * beyond the end of the object. 2316 */ 2317 info.start_pindex = start; 2318 if (end == 0) 2319 info.end_pindex = (vm_pindex_t)-1; 2320 else 2321 info.end_pindex = end - 1; 2322 info.limit = clean_only; 2323 all = (start == 0 && info.end_pindex >= object->size - 1); 2324 2325 /* 2326 * Loop until we are sure we have gotten them all. 2327 */ 2328 do { 2329 info.error = 0; 2330 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 2331 vm_object_page_remove_callback, &info); 2332 } while (info.error); 2333 2334 /* 2335 * Remove any related swap if throwing away pages, or for 2336 * non-swap objects (the swap is a clean copy in that case). 2337 */ 2338 if (object->type != OBJT_SWAP || clean_only == FALSE) { 2339 if (all) 2340 swap_pager_freespace_all(object); 2341 else 2342 swap_pager_freespace(object, info.start_pindex, 2343 info.end_pindex - info.start_pindex + 1); 2344 } 2345 2346 /* 2347 * Cleanup 2348 */ 2349 vm_object_pip_wakeup(object); 2350 vm_object_drop(object); 2351 } 2352 2353 /* 2354 * The caller must hold the object 2355 */ 2356 static int 2357 vm_object_page_remove_callback(vm_page_t p, void *data) 2358 { 2359 struct rb_vm_page_scan_info *info = data; 2360 2361 if (vm_page_busy_try(p, TRUE)) { 2362 vm_page_sleep_busy(p, TRUE, "vmopar"); 2363 info->error = 1; 2364 return(0); 2365 } 2366 2367 /* 2368 * Wired pages cannot be destroyed, but they can be invalidated 2369 * and we do so if clean_only (limit) is not set. 2370 * 2371 * WARNING! The page may be wired due to being part of a buffer 2372 * cache buffer, and the buffer might be marked B_CACHE. 2373 * This is fine as part of a truncation but VFSs must be 2374 * sure to fix the buffer up when re-extending the file. 2375 * 2376 * NOTE! PG_NEED_COMMIT is ignored. 2377 */ 2378 if (p->wire_count != 0) { 2379 vm_page_protect(p, VM_PROT_NONE); 2380 if (info->limit == 0) 2381 p->valid = 0; 2382 vm_page_wakeup(p); 2383 return(0); 2384 } 2385 2386 /* 2387 * limit is our clean_only flag. If set and the page is dirty, do 2388 * not free it. If set and the page is being held by someone, do 2389 * not free it. 2390 */ 2391 if (info->limit && p->valid) { 2392 vm_page_test_dirty(p); 2393 if (p->valid & p->dirty) { 2394 vm_page_wakeup(p); 2395 return(0); 2396 } 2397 #if 0 2398 if (p->hold_count) { 2399 vm_page_wakeup(p); 2400 return(0); 2401 } 2402 #endif 2403 } 2404 2405 /* 2406 * Destroy the page 2407 */ 2408 vm_page_protect(p, VM_PROT_NONE); 2409 vm_page_free(p); 2410 return(0); 2411 } 2412 2413 /* 2414 * Coalesces two objects backing up adjoining regions of memory into a 2415 * single object. 2416 * 2417 * returns TRUE if objects were combined. 2418 * 2419 * NOTE: Only works at the moment if the second object is NULL - 2420 * if it's not, which object do we lock first? 2421 * 2422 * Parameters: 2423 * prev_object First object to coalesce 2424 * prev_offset Offset into prev_object 2425 * next_object Second object into coalesce 2426 * next_offset Offset into next_object 2427 * 2428 * prev_size Size of reference to prev_object 2429 * next_size Size of reference to next_object 2430 * 2431 * The caller does not need to hold (prev_object) but must have a stable 2432 * pointer to it (typically by holding the vm_map locked). 2433 */ 2434 boolean_t 2435 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 2436 vm_size_t prev_size, vm_size_t next_size) 2437 { 2438 vm_pindex_t next_pindex; 2439 2440 if (prev_object == NULL) 2441 return (TRUE); 2442 2443 vm_object_hold(prev_object); 2444 2445 if (prev_object->type != OBJT_DEFAULT && 2446 prev_object->type != OBJT_SWAP) { 2447 vm_object_drop(prev_object); 2448 return (FALSE); 2449 } 2450 2451 /* 2452 * Try to collapse the object first 2453 */ 2454 vm_object_chain_acquire(prev_object); 2455 vm_object_collapse(prev_object, NULL); 2456 2457 /* 2458 * Can't coalesce if: . more than one reference . paged out . shadows 2459 * another object . has a copy elsewhere (any of which mean that the 2460 * pages not mapped to prev_entry may be in use anyway) 2461 */ 2462 2463 if (prev_object->backing_object != NULL) { 2464 vm_object_chain_release(prev_object); 2465 vm_object_drop(prev_object); 2466 return (FALSE); 2467 } 2468 2469 prev_size >>= PAGE_SHIFT; 2470 next_size >>= PAGE_SHIFT; 2471 next_pindex = prev_pindex + prev_size; 2472 2473 if ((prev_object->ref_count > 1) && 2474 (prev_object->size != next_pindex)) { 2475 vm_object_chain_release(prev_object); 2476 vm_object_drop(prev_object); 2477 return (FALSE); 2478 } 2479 2480 /* 2481 * Remove any pages that may still be in the object from a previous 2482 * deallocation. 2483 */ 2484 if (next_pindex < prev_object->size) { 2485 vm_object_page_remove(prev_object, 2486 next_pindex, 2487 next_pindex + next_size, FALSE); 2488 if (prev_object->type == OBJT_SWAP) 2489 swap_pager_freespace(prev_object, 2490 next_pindex, next_size); 2491 } 2492 2493 /* 2494 * Extend the object if necessary. 2495 */ 2496 if (next_pindex + next_size > prev_object->size) 2497 prev_object->size = next_pindex + next_size; 2498 2499 vm_object_chain_release(prev_object); 2500 vm_object_drop(prev_object); 2501 return (TRUE); 2502 } 2503 2504 /* 2505 * Make the object writable and flag is being possibly dirty. 2506 * 2507 * The caller must hold the object. XXX called from vm_page_dirty(), 2508 * There is currently no requirement to hold the object. 2509 */ 2510 void 2511 vm_object_set_writeable_dirty(vm_object_t object) 2512 { 2513 struct vnode *vp; 2514 2515 /*vm_object_assert_held(object);*/ 2516 /* 2517 * Avoid contention in vm fault path by checking the state before 2518 * issuing an atomic op on it. 2519 */ 2520 if ((object->flags & (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) != 2521 (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) { 2522 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 2523 } 2524 if (object->type == OBJT_VNODE && 2525 (vp = (struct vnode *)object->handle) != NULL) { 2526 if ((vp->v_flag & VOBJDIRTY) == 0) { 2527 vsetflags(vp, VOBJDIRTY); 2528 } 2529 } 2530 } 2531 2532 #include "opt_ddb.h" 2533 #ifdef DDB 2534 #include <sys/kernel.h> 2535 2536 #include <sys/cons.h> 2537 2538 #include <ddb/ddb.h> 2539 2540 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 2541 vm_map_entry_t entry); 2542 static int vm_object_in_map (vm_object_t object); 2543 2544 /* 2545 * The caller must hold the object. 2546 */ 2547 static int 2548 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 2549 { 2550 vm_map_t tmpm; 2551 vm_map_entry_t tmpe; 2552 vm_object_t obj, nobj; 2553 int entcount; 2554 2555 if (map == 0) 2556 return 0; 2557 if (entry == 0) { 2558 tmpe = map->header.next; 2559 entcount = map->nentries; 2560 while (entcount-- && (tmpe != &map->header)) { 2561 if( _vm_object_in_map(map, object, tmpe)) { 2562 return 1; 2563 } 2564 tmpe = tmpe->next; 2565 } 2566 return (0); 2567 } 2568 switch(entry->maptype) { 2569 case VM_MAPTYPE_SUBMAP: 2570 tmpm = entry->object.sub_map; 2571 tmpe = tmpm->header.next; 2572 entcount = tmpm->nentries; 2573 while (entcount-- && tmpe != &tmpm->header) { 2574 if( _vm_object_in_map(tmpm, object, tmpe)) { 2575 return 1; 2576 } 2577 tmpe = tmpe->next; 2578 } 2579 break; 2580 case VM_MAPTYPE_NORMAL: 2581 case VM_MAPTYPE_VPAGETABLE: 2582 obj = entry->object.vm_object; 2583 while (obj) { 2584 if (obj == object) { 2585 if (obj != entry->object.vm_object) 2586 vm_object_drop(obj); 2587 return 1; 2588 } 2589 while ((nobj = obj->backing_object) != NULL) { 2590 vm_object_hold(nobj); 2591 if (nobj == obj->backing_object) 2592 break; 2593 vm_object_drop(nobj); 2594 } 2595 if (obj != entry->object.vm_object) { 2596 if (nobj) 2597 vm_object_lock_swap(); 2598 vm_object_drop(obj); 2599 } 2600 obj = nobj; 2601 } 2602 break; 2603 default: 2604 break; 2605 } 2606 return 0; 2607 } 2608 2609 static int vm_object_in_map_callback(struct proc *p, void *data); 2610 2611 struct vm_object_in_map_info { 2612 vm_object_t object; 2613 int rv; 2614 }; 2615 2616 /* 2617 * Debugging only 2618 */ 2619 static int 2620 vm_object_in_map(vm_object_t object) 2621 { 2622 struct vm_object_in_map_info info; 2623 2624 info.rv = 0; 2625 info.object = object; 2626 2627 allproc_scan(vm_object_in_map_callback, &info); 2628 if (info.rv) 2629 return 1; 2630 if( _vm_object_in_map(&kernel_map, object, 0)) 2631 return 1; 2632 if( _vm_object_in_map(&pager_map, object, 0)) 2633 return 1; 2634 if( _vm_object_in_map(&buffer_map, object, 0)) 2635 return 1; 2636 return 0; 2637 } 2638 2639 /* 2640 * Debugging only 2641 */ 2642 static int 2643 vm_object_in_map_callback(struct proc *p, void *data) 2644 { 2645 struct vm_object_in_map_info *info = data; 2646 2647 if (p->p_vmspace) { 2648 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) { 2649 info->rv = 1; 2650 return -1; 2651 } 2652 } 2653 return (0); 2654 } 2655 2656 DB_SHOW_COMMAND(vmochk, vm_object_check) 2657 { 2658 vm_object_t object; 2659 2660 /* 2661 * make sure that internal objs are in a map somewhere 2662 * and none have zero ref counts. 2663 */ 2664 for (object = TAILQ_FIRST(&vm_object_list); 2665 object != NULL; 2666 object = TAILQ_NEXT(object, object_list)) { 2667 if (object->type == OBJT_MARKER) 2668 continue; 2669 if (object->handle == NULL && 2670 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 2671 if (object->ref_count == 0) { 2672 db_printf("vmochk: internal obj has zero ref count: %ld\n", 2673 (long)object->size); 2674 } 2675 if (!vm_object_in_map(object)) { 2676 db_printf( 2677 "vmochk: internal obj is not in a map: " 2678 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 2679 object->ref_count, (u_long)object->size, 2680 (u_long)object->size, 2681 (void *)object->backing_object); 2682 } 2683 } 2684 } 2685 } 2686 2687 /* 2688 * Debugging only 2689 */ 2690 DB_SHOW_COMMAND(object, vm_object_print_static) 2691 { 2692 /* XXX convert args. */ 2693 vm_object_t object = (vm_object_t)addr; 2694 boolean_t full = have_addr; 2695 2696 vm_page_t p; 2697 2698 /* XXX count is an (unused) arg. Avoid shadowing it. */ 2699 #define count was_count 2700 2701 int count; 2702 2703 if (object == NULL) 2704 return; 2705 2706 db_iprintf( 2707 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 2708 object, (int)object->type, (u_long)object->size, 2709 object->resident_page_count, object->ref_count, object->flags); 2710 /* 2711 * XXX no %qd in kernel. Truncate object->backing_object_offset. 2712 */ 2713 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 2714 object->shadow_count, 2715 object->backing_object ? object->backing_object->ref_count : 0, 2716 object->backing_object, (long)object->backing_object_offset); 2717 2718 if (!full) 2719 return; 2720 2721 db_indent += 2; 2722 count = 0; 2723 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) { 2724 if (count == 0) 2725 db_iprintf("memory:="); 2726 else if (count == 6) { 2727 db_printf("\n"); 2728 db_iprintf(" ..."); 2729 count = 0; 2730 } else 2731 db_printf(","); 2732 count++; 2733 2734 db_printf("(off=0x%lx,page=0x%lx)", 2735 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 2736 } 2737 if (count != 0) 2738 db_printf("\n"); 2739 db_indent -= 2; 2740 } 2741 2742 /* XXX. */ 2743 #undef count 2744 2745 /* 2746 * XXX need this non-static entry for calling from vm_map_print. 2747 * 2748 * Debugging only 2749 */ 2750 void 2751 vm_object_print(/* db_expr_t */ long addr, 2752 boolean_t have_addr, 2753 /* db_expr_t */ long count, 2754 char *modif) 2755 { 2756 vm_object_print_static(addr, have_addr, count, modif); 2757 } 2758 2759 /* 2760 * Debugging only 2761 */ 2762 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 2763 { 2764 vm_object_t object; 2765 int nl = 0; 2766 int c; 2767 for (object = TAILQ_FIRST(&vm_object_list); 2768 object != NULL; 2769 object = TAILQ_NEXT(object, object_list)) { 2770 vm_pindex_t idx, fidx; 2771 vm_pindex_t osize; 2772 vm_paddr_t pa = -1, padiff; 2773 int rcount; 2774 vm_page_t m; 2775 2776 if (object->type == OBJT_MARKER) 2777 continue; 2778 db_printf("new object: %p\n", (void *)object); 2779 if ( nl > 18) { 2780 c = cngetc(); 2781 if (c != ' ') 2782 return; 2783 nl = 0; 2784 } 2785 nl++; 2786 rcount = 0; 2787 fidx = 0; 2788 osize = object->size; 2789 if (osize > 128) 2790 osize = 128; 2791 for (idx = 0; idx < osize; idx++) { 2792 m = vm_page_lookup(object, idx); 2793 if (m == NULL) { 2794 if (rcount) { 2795 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2796 (long)fidx, rcount, (long)pa); 2797 if ( nl > 18) { 2798 c = cngetc(); 2799 if (c != ' ') 2800 return; 2801 nl = 0; 2802 } 2803 nl++; 2804 rcount = 0; 2805 } 2806 continue; 2807 } 2808 2809 2810 if (rcount && 2811 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 2812 ++rcount; 2813 continue; 2814 } 2815 if (rcount) { 2816 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 2817 padiff >>= PAGE_SHIFT; 2818 padiff &= PQ_L2_MASK; 2819 if (padiff == 0) { 2820 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 2821 ++rcount; 2822 continue; 2823 } 2824 db_printf(" index(%ld)run(%d)pa(0x%lx)", 2825 (long)fidx, rcount, (long)pa); 2826 db_printf("pd(%ld)\n", (long)padiff); 2827 if ( nl > 18) { 2828 c = cngetc(); 2829 if (c != ' ') 2830 return; 2831 nl = 0; 2832 } 2833 nl++; 2834 } 2835 fidx = idx; 2836 pa = VM_PAGE_TO_PHYS(m); 2837 rcount = 1; 2838 } 2839 if (rcount) { 2840 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2841 (long)fidx, rcount, (long)pa); 2842 if ( nl > 18) { 2843 c = cngetc(); 2844 if (c != ' ') 2845 return; 2846 nl = 0; 2847 } 2848 nl++; 2849 } 2850 } 2851 } 2852 #endif /* DDB */ 2853