1 /* 2 * Copyright (c) 1991, 1993, 2013 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94 33 * 34 * 35 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 36 * All rights reserved. 37 * 38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 39 * 40 * Permission to use, copy, modify and distribute this software and 41 * its documentation is hereby granted, provided that both the copyright 42 * notice and this permission notice appear in all copies of the 43 * software, derivative works or modified versions, and any portions 44 * thereof, and that both notices appear in supporting documentation. 45 * 46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 49 * 50 * Carnegie Mellon requests users of this software to return to 51 * 52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 53 * School of Computer Science 54 * Carnegie Mellon University 55 * Pittsburgh PA 15213-3890 56 * 57 * any improvements or extensions that they make and grant Carnegie the 58 * rights to redistribute these changes. 59 * 60 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ 61 */ 62 63 /* 64 * Virtual memory object module. 65 */ 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/proc.h> /* for curproc, pageproc */ 70 #include <sys/thread.h> 71 #include <sys/vnode.h> 72 #include <sys/vmmeter.h> 73 #include <sys/mman.h> 74 #include <sys/mount.h> 75 #include <sys/kernel.h> 76 #include <sys/sysctl.h> 77 #include <sys/refcount.h> 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <vm/pmap.h> 82 #include <vm/vm_map.h> 83 #include <vm/vm_object.h> 84 #include <vm/vm_page.h> 85 #include <vm/vm_pageout.h> 86 #include <vm/vm_pager.h> 87 #include <vm/swap_pager.h> 88 #include <vm/vm_kern.h> 89 #include <vm/vm_extern.h> 90 #include <vm/vm_zone.h> 91 92 #include <vm/vm_page2.h> 93 94 #include <machine/specialreg.h> 95 96 #define EASY_SCAN_FACTOR 8 97 98 static void vm_object_qcollapse(vm_object_t object, 99 vm_object_t backing_object); 100 static void vm_object_page_collect_flush(vm_object_t object, vm_page_t p, 101 int pagerflags); 102 static void vm_object_lock_init(vm_object_t); 103 104 105 /* 106 * Virtual memory objects maintain the actual data 107 * associated with allocated virtual memory. A given 108 * page of memory exists within exactly one object. 109 * 110 * An object is only deallocated when all "references" 111 * are given up. Only one "reference" to a given 112 * region of an object should be writeable. 113 * 114 * Associated with each object is a list of all resident 115 * memory pages belonging to that object; this list is 116 * maintained by the "vm_page" module, and locked by the object's 117 * lock. 118 * 119 * Each object also records a "pager" routine which is 120 * used to retrieve (and store) pages to the proper backing 121 * storage. In addition, objects may be backed by other 122 * objects from which they were virtual-copied. 123 * 124 * The only items within the object structure which are 125 * modified after time of creation are: 126 * reference count locked by object's lock 127 * pager routine locked by object's lock 128 * 129 */ 130 131 struct vm_object kernel_object; 132 133 static long vm_object_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 #define VM_OBJECTS_INIT 256 141 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 142 143 struct object_q vm_object_lists[VMOBJ_HSIZE]; 144 struct lwkt_token vmobj_tokens[VMOBJ_HSIZE]; 145 146 #if defined(DEBUG_LOCKS) 147 148 #define vm_object_vndeallocate(obj, vpp) \ 149 debugvm_object_vndeallocate(obj, vpp, __FILE__, __LINE__) 150 151 /* 152 * Debug helper to track hold/drop/ref/deallocate calls. 153 */ 154 static void 155 debugvm_object_add(vm_object_t obj, char *file, int line, int addrem) 156 { 157 int i; 158 159 i = atomic_fetchadd_int(&obj->debug_index, 1); 160 i = i & (VMOBJ_DEBUG_ARRAY_SIZE - 1); 161 ksnprintf(obj->debug_hold_thrs[i], 162 sizeof(obj->debug_hold_thrs[i]), 163 "%c%d:(%d):%s", 164 (addrem == -1 ? '-' : (addrem == 1 ? '+' : '=')), 165 (curthread->td_proc ? curthread->td_proc->p_pid : -1), 166 obj->ref_count, 167 curthread->td_comm); 168 obj->debug_hold_file[i] = file; 169 obj->debug_hold_line[i] = line; 170 #if 0 171 /* Uncomment for debugging obj refs/derefs in reproducable cases */ 172 if (strcmp(curthread->td_comm, "sshd") == 0) { 173 kprintf("%d %p refs=%d ar=%d file: %s/%d\n", 174 (curthread->td_proc ? curthread->td_proc->p_pid : -1), 175 obj, obj->ref_count, addrem, file, line); 176 } 177 #endif 178 } 179 180 #endif 181 182 /* 183 * Misc low level routines 184 */ 185 static void 186 vm_object_lock_init(vm_object_t obj) 187 { 188 #if defined(DEBUG_LOCKS) 189 int i; 190 191 obj->debug_index = 0; 192 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 193 obj->debug_hold_thrs[i][0] = 0; 194 obj->debug_hold_file[i] = NULL; 195 obj->debug_hold_line[i] = 0; 196 } 197 #endif 198 } 199 200 void 201 vm_object_lock_swap(void) 202 { 203 lwkt_token_swap(); 204 } 205 206 void 207 vm_object_lock(vm_object_t obj) 208 { 209 lwkt_gettoken(&obj->token); 210 } 211 212 /* 213 * Returns TRUE on sucesss 214 */ 215 static int 216 vm_object_lock_try(vm_object_t obj) 217 { 218 return(lwkt_trytoken(&obj->token)); 219 } 220 221 void 222 vm_object_lock_shared(vm_object_t obj) 223 { 224 lwkt_gettoken_shared(&obj->token); 225 } 226 227 void 228 vm_object_unlock(vm_object_t obj) 229 { 230 lwkt_reltoken(&obj->token); 231 } 232 233 void 234 vm_object_upgrade(vm_object_t obj) 235 { 236 lwkt_reltoken(&obj->token); 237 lwkt_gettoken(&obj->token); 238 } 239 240 void 241 vm_object_downgrade(vm_object_t obj) 242 { 243 lwkt_reltoken(&obj->token); 244 lwkt_gettoken_shared(&obj->token); 245 } 246 247 static __inline void 248 vm_object_assert_held(vm_object_t obj) 249 { 250 ASSERT_LWKT_TOKEN_HELD(&obj->token); 251 } 252 253 void 254 VMOBJDEBUG(vm_object_hold)(vm_object_t obj VMOBJDBARGS) 255 { 256 KKASSERT(obj != NULL); 257 258 /* 259 * Object must be held (object allocation is stable due to callers 260 * context, typically already holding the token on a parent object) 261 * prior to potentially blocking on the lock, otherwise the object 262 * can get ripped away from us. 263 */ 264 refcount_acquire(&obj->hold_count); 265 vm_object_lock(obj); 266 267 #if defined(DEBUG_LOCKS) 268 debugvm_object_add(obj, file, line, 1); 269 #endif 270 } 271 272 int 273 VMOBJDEBUG(vm_object_hold_try)(vm_object_t obj VMOBJDBARGS) 274 { 275 KKASSERT(obj != NULL); 276 277 /* 278 * Object must be held (object allocation is stable due to callers 279 * context, typically already holding the token on a parent object) 280 * prior to potentially blocking on the lock, otherwise the object 281 * can get ripped away from us. 282 */ 283 refcount_acquire(&obj->hold_count); 284 if (vm_object_lock_try(obj) == 0) { 285 if (refcount_release(&obj->hold_count)) { 286 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) 287 zfree(obj_zone, obj); 288 } 289 return(0); 290 } 291 292 #if defined(DEBUG_LOCKS) 293 debugvm_object_add(obj, file, line, 1); 294 #endif 295 return(1); 296 } 297 298 void 299 VMOBJDEBUG(vm_object_hold_shared)(vm_object_t obj VMOBJDBARGS) 300 { 301 KKASSERT(obj != NULL); 302 303 /* 304 * Object must be held (object allocation is stable due to callers 305 * context, typically already holding the token on a parent object) 306 * prior to potentially blocking on the lock, otherwise the object 307 * can get ripped away from us. 308 */ 309 refcount_acquire(&obj->hold_count); 310 vm_object_lock_shared(obj); 311 312 #if defined(DEBUG_LOCKS) 313 debugvm_object_add(obj, file, line, 1); 314 #endif 315 } 316 317 /* 318 * Drop the token and hold_count on the object. 319 * 320 * WARNING! Token might be shared. 321 */ 322 void 323 VMOBJDEBUG(vm_object_drop)(vm_object_t obj VMOBJDBARGS) 324 { 325 if (obj == NULL) 326 return; 327 328 /* 329 * No new holders should be possible once we drop hold_count 1->0 as 330 * there is no longer any way to reference the object. 331 */ 332 KKASSERT(obj->hold_count > 0); 333 if (refcount_release(&obj->hold_count)) { 334 #if defined(DEBUG_LOCKS) 335 debugvm_object_add(obj, file, line, -1); 336 #endif 337 338 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) { 339 vm_object_unlock(obj); 340 zfree(obj_zone, obj); 341 } else { 342 vm_object_unlock(obj); 343 } 344 } else { 345 #if defined(DEBUG_LOCKS) 346 debugvm_object_add(obj, file, line, -1); 347 #endif 348 vm_object_unlock(obj); 349 } 350 } 351 352 /* 353 * Initialize a freshly allocated object, returning a held object. 354 * 355 * Used only by vm_object_allocate() and zinitna(). 356 * 357 * No requirements. 358 */ 359 void 360 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object) 361 { 362 int incr; 363 int n; 364 365 RB_INIT(&object->rb_memq); 366 LIST_INIT(&object->shadow_head); 367 lwkt_token_init(&object->token, "vmobj"); 368 369 object->type = type; 370 object->size = size; 371 object->ref_count = 1; 372 object->memattr = VM_MEMATTR_DEFAULT; 373 object->hold_count = 0; 374 object->flags = 0; 375 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 376 vm_object_set_flag(object, OBJ_ONEMAPPING); 377 object->paging_in_progress = 0; 378 object->resident_page_count = 0; 379 object->agg_pv_list_count = 0; 380 object->shadow_count = 0; 381 /* cpu localization twist */ 382 object->pg_color = (int)(intptr_t)curthread; 383 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 384 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 385 else 386 incr = size; 387 next_index = (next_index + incr) & PQ_L2_MASK; 388 object->handle = NULL; 389 object->backing_object = NULL; 390 object->backing_object_offset = (vm_ooffset_t)0; 391 392 object->generation++; 393 object->swblock_count = 0; 394 RB_INIT(&object->swblock_root); 395 vm_object_lock_init(object); 396 pmap_object_init(object); 397 398 vm_object_hold(object); 399 400 n = VMOBJ_HASH(object); 401 atomic_add_long(&vm_object_count, 1); 402 lwkt_gettoken(&vmobj_tokens[n]); 403 TAILQ_INSERT_TAIL(&vm_object_lists[n], object, object_list); 404 lwkt_reltoken(&vmobj_tokens[n]); 405 } 406 407 /* 408 * Initialize the VM objects module. 409 * 410 * Called from the low level boot code only. 411 */ 412 void 413 vm_object_init(void) 414 { 415 int i; 416 417 for (i = 0; i < VMOBJ_HSIZE; ++i) { 418 TAILQ_INIT(&vm_object_lists[i]); 419 lwkt_token_init(&vmobj_tokens[i], "vmobjlst"); 420 } 421 422 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd), 423 &kernel_object); 424 vm_object_drop(&kernel_object); 425 426 obj_zone = &obj_zone_store; 427 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 428 vm_objects_init, VM_OBJECTS_INIT); 429 } 430 431 void 432 vm_object_init2(void) 433 { 434 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 435 } 436 437 /* 438 * Allocate and return a new object of the specified type and size. 439 * 440 * No requirements. 441 */ 442 vm_object_t 443 vm_object_allocate(objtype_t type, vm_pindex_t size) 444 { 445 vm_object_t result; 446 447 result = (vm_object_t) zalloc(obj_zone); 448 449 _vm_object_allocate(type, size, result); 450 vm_object_drop(result); 451 452 return (result); 453 } 454 455 /* 456 * This version returns a held object, allowing further atomic initialization 457 * of the object. 458 */ 459 vm_object_t 460 vm_object_allocate_hold(objtype_t type, vm_pindex_t size) 461 { 462 vm_object_t result; 463 464 result = (vm_object_t) zalloc(obj_zone); 465 466 _vm_object_allocate(type, size, result); 467 468 return (result); 469 } 470 471 /* 472 * Add an additional reference to a vm_object. The object must already be 473 * held. The original non-lock version is no longer supported. The object 474 * must NOT be chain locked by anyone at the time the reference is added. 475 * 476 * Referencing a chain-locked object can blow up the fairly sensitive 477 * ref_count and shadow_count tests in the deallocator. Most callers 478 * will call vm_object_chain_wait() prior to calling 479 * vm_object_reference_locked() to avoid the case. 480 * 481 * The object must be held, but may be held shared if desired (hence why 482 * we use an atomic op). 483 */ 484 void 485 VMOBJDEBUG(vm_object_reference_locked)(vm_object_t object VMOBJDBARGS) 486 { 487 KKASSERT(object != NULL); 488 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 489 KKASSERT((object->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) == 0); 490 atomic_add_int(&object->ref_count, 1); 491 if (object->type == OBJT_VNODE) { 492 vref(object->handle); 493 /* XXX what if the vnode is being destroyed? */ 494 } 495 #if defined(DEBUG_LOCKS) 496 debugvm_object_add(object, file, line, 1); 497 #endif 498 } 499 500 /* 501 * This version is only allowed for vnode objects. 502 */ 503 void 504 VMOBJDEBUG(vm_object_reference_quick)(vm_object_t object VMOBJDBARGS) 505 { 506 KKASSERT(object->type == OBJT_VNODE); 507 atomic_add_int(&object->ref_count, 1); 508 vref(object->handle); 509 #if defined(DEBUG_LOCKS) 510 debugvm_object_add(object, file, line, 1); 511 #endif 512 } 513 514 /* 515 * Object OBJ_CHAINLOCK lock handling. 516 * 517 * The caller can chain-lock backing objects recursively and then 518 * use vm_object_chain_release_all() to undo the whole chain. 519 * 520 * Chain locks are used to prevent collapses and are only applicable 521 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations 522 * on other object types are ignored. This is also important because 523 * it allows e.g. the vnode underlying a memory mapping to take concurrent 524 * faults. 525 * 526 * The object must usually be held on entry, though intermediate 527 * objects need not be held on release. The object must be held exclusively, 528 * NOT shared. Note that the prefault path checks the shared state and 529 * avoids using the chain functions. 530 */ 531 void 532 vm_object_chain_wait(vm_object_t object, int shared) 533 { 534 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 535 for (;;) { 536 uint32_t chainlk = object->chainlk; 537 538 cpu_ccfence(); 539 if (shared) { 540 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) { 541 tsleep_interlock(object, 0); 542 if (atomic_cmpset_int(&object->chainlk, 543 chainlk, 544 chainlk | CHAINLK_WAIT)) { 545 tsleep(object, PINTERLOCKED, 546 "objchns", 0); 547 } 548 /* retry */ 549 } else { 550 break; 551 } 552 /* retry */ 553 } else { 554 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) { 555 tsleep_interlock(object, 0); 556 if (atomic_cmpset_int(&object->chainlk, 557 chainlk, 558 chainlk | CHAINLK_WAIT)) 559 { 560 tsleep(object, PINTERLOCKED, 561 "objchnx", 0); 562 } 563 /* retry */ 564 } else { 565 if (atomic_cmpset_int(&object->chainlk, 566 chainlk, 567 chainlk & ~CHAINLK_WAIT)) 568 { 569 if (chainlk & CHAINLK_WAIT) 570 wakeup(object); 571 break; 572 } 573 /* retry */ 574 } 575 } 576 /* retry */ 577 } 578 } 579 580 void 581 vm_object_chain_acquire(vm_object_t object, int shared) 582 { 583 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) 584 return; 585 if (vm_shared_fault == 0) 586 shared = 0; 587 588 for (;;) { 589 uint32_t chainlk = object->chainlk; 590 591 cpu_ccfence(); 592 if (shared) { 593 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) { 594 tsleep_interlock(object, 0); 595 if (atomic_cmpset_int(&object->chainlk, 596 chainlk, 597 chainlk | CHAINLK_WAIT)) { 598 tsleep(object, PINTERLOCKED, 599 "objchns", 0); 600 } 601 /* retry */ 602 } else if (atomic_cmpset_int(&object->chainlk, 603 chainlk, chainlk + 1)) { 604 break; 605 } 606 /* retry */ 607 } else { 608 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) { 609 tsleep_interlock(object, 0); 610 if (atomic_cmpset_int(&object->chainlk, 611 chainlk, 612 chainlk | 613 CHAINLK_WAIT | 614 CHAINLK_EXCLREQ)) { 615 tsleep(object, PINTERLOCKED, 616 "objchnx", 0); 617 } 618 /* retry */ 619 } else { 620 if (atomic_cmpset_int(&object->chainlk, 621 chainlk, 622 (chainlk | CHAINLK_EXCL) & 623 ~(CHAINLK_EXCLREQ | 624 CHAINLK_WAIT))) { 625 if (chainlk & CHAINLK_WAIT) 626 wakeup(object); 627 break; 628 } 629 /* retry */ 630 } 631 } 632 /* retry */ 633 } 634 } 635 636 void 637 vm_object_chain_release(vm_object_t object) 638 { 639 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/ 640 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) 641 return; 642 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL)); 643 for (;;) { 644 uint32_t chainlk = object->chainlk; 645 646 cpu_ccfence(); 647 if (chainlk & CHAINLK_MASK) { 648 if ((chainlk & CHAINLK_MASK) == 1 && 649 atomic_cmpset_int(&object->chainlk, 650 chainlk, 651 (chainlk - 1) & ~CHAINLK_WAIT)) { 652 if (chainlk & CHAINLK_WAIT) 653 wakeup(object); 654 break; 655 } 656 if ((chainlk & CHAINLK_MASK) > 1 && 657 atomic_cmpset_int(&object->chainlk, 658 chainlk, chainlk - 1)) { 659 break; 660 } 661 /* retry */ 662 } else { 663 KKASSERT(chainlk & CHAINLK_EXCL); 664 if (atomic_cmpset_int(&object->chainlk, 665 chainlk, 666 chainlk & ~(CHAINLK_EXCL | 667 CHAINLK_WAIT))) { 668 if (chainlk & CHAINLK_WAIT) 669 wakeup(object); 670 break; 671 } 672 } 673 } 674 } 675 676 /* 677 * Release the chain from first_object through and including stopobj. 678 * The caller is typically holding the first and last object locked 679 * (shared or exclusive) to prevent destruction races. 680 * 681 * We release stopobj first as an optimization as this object is most 682 * likely to be shared across multiple processes. 683 */ 684 void 685 vm_object_chain_release_all(vm_object_t first_object, vm_object_t stopobj) 686 { 687 vm_object_t backing_object; 688 vm_object_t object; 689 690 vm_object_chain_release(stopobj); 691 object = first_object; 692 693 while (object != stopobj) { 694 KKASSERT(object); 695 backing_object = object->backing_object; 696 vm_object_chain_release(object); 697 object = backing_object; 698 } 699 } 700 701 /* 702 * Dereference an object and its underlying vnode. The object may be 703 * held shared. On return the object will remain held. 704 * 705 * This function may return a vnode in *vpp which the caller must release 706 * after the caller drops its own lock. If vpp is NULL, we assume that 707 * the caller was holding an exclusive lock on the object and we vrele() 708 * the vp ourselves. 709 */ 710 static void 711 VMOBJDEBUG(vm_object_vndeallocate)(vm_object_t object, struct vnode **vpp 712 VMOBJDBARGS) 713 { 714 struct vnode *vp = (struct vnode *) object->handle; 715 716 KASSERT(object->type == OBJT_VNODE, 717 ("vm_object_vndeallocate: not a vnode object")); 718 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 719 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 720 #ifdef INVARIANTS 721 if (object->ref_count == 0) { 722 vprint("vm_object_vndeallocate", vp); 723 panic("vm_object_vndeallocate: bad object reference count"); 724 } 725 #endif 726 for (;;) { 727 int count = object->ref_count; 728 cpu_ccfence(); 729 if (count == 1) { 730 vm_object_upgrade(object); 731 if (atomic_cmpset_int(&object->ref_count, count, 0)) { 732 vclrflags(vp, VTEXT); 733 break; 734 } 735 } else { 736 if (atomic_cmpset_int(&object->ref_count, 737 count, count - 1)) { 738 break; 739 } 740 } 741 /* retry */ 742 } 743 #if defined(DEBUG_LOCKS) 744 debugvm_object_add(object, file, line, -1); 745 #endif 746 747 /* 748 * vrele or return the vp to vrele. We can only safely vrele(vp) 749 * if the object was locked exclusively. But there are two races 750 * here. 751 * 752 * We had to upgrade the object above to safely clear VTEXT 753 * but the alternative path where the shared lock is retained 754 * can STILL race to 0 in other paths and cause our own vrele() 755 * to terminate the vnode. We can't allow that if the VM object 756 * is still locked shared. 757 */ 758 if (vpp) 759 *vpp = vp; 760 else 761 vrele(vp); 762 } 763 764 /* 765 * Release a reference to the specified object, gained either through a 766 * vm_object_allocate or a vm_object_reference call. When all references 767 * are gone, storage associated with this object may be relinquished. 768 * 769 * The caller does not have to hold the object locked but must have control 770 * over the reference in question in order to guarantee that the object 771 * does not get ripped out from under us. 772 * 773 * XXX Currently all deallocations require an exclusive lock. 774 */ 775 void 776 VMOBJDEBUG(vm_object_deallocate)(vm_object_t object VMOBJDBARGS) 777 { 778 struct vnode *vp; 779 int count; 780 781 if (object == NULL) 782 return; 783 784 for (;;) { 785 count = object->ref_count; 786 cpu_ccfence(); 787 788 /* 789 * If decrementing the count enters into special handling 790 * territory (0, 1, or 2) we have to do it the hard way. 791 * Fortunate though, objects with only a few refs like this 792 * are not likely to be heavily contended anyway. 793 * 794 * For vnode objects we only care about 1->0 transitions. 795 */ 796 if (count <= 3 || (object->type == OBJT_VNODE && count <= 1)) { 797 #if defined(DEBUG_LOCKS) 798 debugvm_object_add(object, file, line, 0); 799 #endif 800 vm_object_hold(object); 801 vm_object_deallocate_locked(object); 802 vm_object_drop(object); 803 break; 804 } 805 806 /* 807 * Try to decrement ref_count without acquiring a hold on 808 * the object. This is particularly important for the exec*() 809 * and exit*() code paths because the program binary may 810 * have a great deal of sharing and an exclusive lock will 811 * crowbar performance in those circumstances. 812 */ 813 if (object->type == OBJT_VNODE) { 814 vp = (struct vnode *)object->handle; 815 if (atomic_cmpset_int(&object->ref_count, 816 count, count - 1)) { 817 #if defined(DEBUG_LOCKS) 818 debugvm_object_add(object, file, line, -1); 819 #endif 820 821 vrele(vp); 822 break; 823 } 824 /* retry */ 825 } else { 826 if (atomic_cmpset_int(&object->ref_count, 827 count, count - 1)) { 828 #if defined(DEBUG_LOCKS) 829 debugvm_object_add(object, file, line, -1); 830 #endif 831 break; 832 } 833 /* retry */ 834 } 835 /* retry */ 836 } 837 } 838 839 void 840 VMOBJDEBUG(vm_object_deallocate_locked)(vm_object_t object VMOBJDBARGS) 841 { 842 struct vm_object_dealloc_list *dlist = NULL; 843 struct vm_object_dealloc_list *dtmp; 844 vm_object_t temp; 845 int must_drop = 0; 846 847 /* 848 * We may chain deallocate object, but additional objects may 849 * collect on the dlist which also have to be deallocated. We 850 * must avoid a recursion, vm_object chains can get deep. 851 */ 852 853 again: 854 while (object != NULL) { 855 /* 856 * vnode case, caller either locked the object exclusively 857 * or this is a recursion with must_drop != 0 and the vnode 858 * object will be locked shared. 859 * 860 * If locked shared we have to drop the object before we can 861 * call vrele() or risk a shared/exclusive livelock. 862 */ 863 if (object->type == OBJT_VNODE) { 864 ASSERT_LWKT_TOKEN_HELD(&object->token); 865 if (must_drop) { 866 struct vnode *tmp_vp; 867 868 vm_object_vndeallocate(object, &tmp_vp); 869 vm_object_drop(object); 870 must_drop = 0; 871 object = NULL; 872 vrele(tmp_vp); 873 } else { 874 vm_object_vndeallocate(object, NULL); 875 } 876 break; 877 } 878 ASSERT_LWKT_TOKEN_HELD_EXCL(&object->token); 879 880 /* 881 * Normal case (object is locked exclusively) 882 */ 883 if (object->ref_count == 0) { 884 panic("vm_object_deallocate: object deallocated " 885 "too many times: %d", object->type); 886 } 887 if (object->ref_count > 2) { 888 atomic_add_int(&object->ref_count, -1); 889 #if defined(DEBUG_LOCKS) 890 debugvm_object_add(object, file, line, -1); 891 #endif 892 break; 893 } 894 895 /* 896 * Here on ref_count of one or two, which are special cases for 897 * objects. 898 * 899 * Nominal ref_count > 1 case if the second ref is not from 900 * a shadow. 901 * 902 * (ONEMAPPING only applies to DEFAULT AND SWAP objects) 903 */ 904 if (object->ref_count == 2 && object->shadow_count == 0) { 905 if (object->type == OBJT_DEFAULT || 906 object->type == OBJT_SWAP) { 907 vm_object_set_flag(object, OBJ_ONEMAPPING); 908 } 909 atomic_add_int(&object->ref_count, -1); 910 #if defined(DEBUG_LOCKS) 911 debugvm_object_add(object, file, line, -1); 912 #endif 913 break; 914 } 915 916 /* 917 * If the second ref is from a shadow we chain along it 918 * upwards if object's handle is exhausted. 919 * 920 * We have to decrement object->ref_count before potentially 921 * collapsing the first shadow object or the collapse code 922 * will not be able to handle the degenerate case to remove 923 * object. However, if we do it too early the object can 924 * get ripped out from under us. 925 */ 926 if (object->ref_count == 2 && object->shadow_count == 1 && 927 object->handle == NULL && (object->type == OBJT_DEFAULT || 928 object->type == OBJT_SWAP)) { 929 temp = LIST_FIRST(&object->shadow_head); 930 KKASSERT(temp != NULL); 931 vm_object_hold(temp); 932 933 /* 934 * Wait for any paging to complete so the collapse 935 * doesn't (or isn't likely to) qcollapse. pip 936 * waiting must occur before we acquire the 937 * chainlock. 938 */ 939 while ( 940 temp->paging_in_progress || 941 object->paging_in_progress 942 ) { 943 vm_object_pip_wait(temp, "objde1"); 944 vm_object_pip_wait(object, "objde2"); 945 } 946 947 /* 948 * If the parent is locked we have to give up, as 949 * otherwise we would be acquiring locks in the 950 * wrong order and potentially deadlock. 951 */ 952 if (temp->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) { 953 vm_object_drop(temp); 954 goto skip; 955 } 956 vm_object_chain_acquire(temp, 0); 957 958 /* 959 * Recheck/retry after the hold and the paging 960 * wait, both of which can block us. 961 */ 962 if (object->ref_count != 2 || 963 object->shadow_count != 1 || 964 object->handle || 965 LIST_FIRST(&object->shadow_head) != temp || 966 (object->type != OBJT_DEFAULT && 967 object->type != OBJT_SWAP)) { 968 vm_object_chain_release(temp); 969 vm_object_drop(temp); 970 continue; 971 } 972 973 /* 974 * We can safely drop object's ref_count now. 975 */ 976 KKASSERT(object->ref_count == 2); 977 atomic_add_int(&object->ref_count, -1); 978 #if defined(DEBUG_LOCKS) 979 debugvm_object_add(object, file, line, -1); 980 #endif 981 982 /* 983 * If our single parent is not collapseable just 984 * decrement ref_count (2->1) and stop. 985 */ 986 if (temp->handle || (temp->type != OBJT_DEFAULT && 987 temp->type != OBJT_SWAP)) { 988 vm_object_chain_release(temp); 989 vm_object_drop(temp); 990 break; 991 } 992 993 /* 994 * At this point we have already dropped object's 995 * ref_count so it is possible for a race to 996 * deallocate obj out from under us. Any collapse 997 * will re-check the situation. We must not block 998 * until we are able to collapse. 999 * 1000 * Bump temp's ref_count to avoid an unwanted 1001 * degenerate recursion (can't call 1002 * vm_object_reference_locked() because it asserts 1003 * that CHAINLOCK is not set). 1004 */ 1005 atomic_add_int(&temp->ref_count, 1); 1006 KKASSERT(temp->ref_count > 1); 1007 1008 /* 1009 * Collapse temp, then deallocate the extra ref 1010 * formally. 1011 */ 1012 vm_object_collapse(temp, &dlist); 1013 vm_object_chain_release(temp); 1014 if (must_drop) { 1015 vm_object_lock_swap(); 1016 vm_object_drop(object); 1017 } 1018 object = temp; 1019 must_drop = 1; 1020 continue; 1021 } 1022 1023 /* 1024 * Drop the ref and handle termination on the 1->0 transition. 1025 * We may have blocked above so we have to recheck. 1026 */ 1027 skip: 1028 KKASSERT(object->ref_count != 0); 1029 if (object->ref_count >= 2) { 1030 atomic_add_int(&object->ref_count, -1); 1031 #if defined(DEBUG_LOCKS) 1032 debugvm_object_add(object, file, line, -1); 1033 #endif 1034 break; 1035 } 1036 KKASSERT(object->ref_count == 1); 1037 1038 /* 1039 * 1->0 transition. Chain through the backing_object. 1040 * Maintain the ref until we've located the backing object, 1041 * then re-check. 1042 */ 1043 while ((temp = object->backing_object) != NULL) { 1044 if (temp->type == OBJT_VNODE) 1045 vm_object_hold_shared(temp); 1046 else 1047 vm_object_hold(temp); 1048 if (temp == object->backing_object) 1049 break; 1050 vm_object_drop(temp); 1051 } 1052 1053 /* 1054 * 1->0 transition verified, retry if ref_count is no longer 1055 * 1. Otherwise disconnect the backing_object (temp) and 1056 * clean up. 1057 */ 1058 if (object->ref_count != 1) { 1059 vm_object_drop(temp); 1060 continue; 1061 } 1062 1063 /* 1064 * It shouldn't be possible for the object to be chain locked 1065 * if we're removing the last ref on it. 1066 * 1067 * Removing object from temp's shadow list requires dropping 1068 * temp, which we will do on loop. 1069 * 1070 * NOTE! vnodes do not use the shadow list, but still have 1071 * the backing_object reference. 1072 */ 1073 KKASSERT((object->chainlk & (CHAINLK_EXCL|CHAINLK_MASK)) == 0); 1074 1075 if (temp) { 1076 if (object->flags & OBJ_ONSHADOW) { 1077 LIST_REMOVE(object, shadow_list); 1078 temp->shadow_count--; 1079 temp->generation++; 1080 vm_object_clear_flag(object, OBJ_ONSHADOW); 1081 } 1082 object->backing_object = NULL; 1083 } 1084 1085 atomic_add_int(&object->ref_count, -1); 1086 if ((object->flags & OBJ_DEAD) == 0) 1087 vm_object_terminate(object); 1088 if (must_drop && temp) 1089 vm_object_lock_swap(); 1090 if (must_drop) 1091 vm_object_drop(object); 1092 object = temp; 1093 must_drop = 1; 1094 } 1095 1096 if (must_drop && object) 1097 vm_object_drop(object); 1098 1099 /* 1100 * Additional tail recursion on dlist. Avoid a recursion. Objects 1101 * on the dlist have a hold count but are not locked. 1102 */ 1103 if ((dtmp = dlist) != NULL) { 1104 dlist = dtmp->next; 1105 object = dtmp->object; 1106 kfree(dtmp, M_TEMP); 1107 1108 vm_object_lock(object); /* already held, add lock */ 1109 must_drop = 1; /* and we're responsible for it */ 1110 goto again; 1111 } 1112 } 1113 1114 /* 1115 * Destroy the specified object, freeing up related resources. 1116 * 1117 * The object must have zero references. 1118 * 1119 * The object must held. The caller is responsible for dropping the object 1120 * after terminate returns. Terminate does NOT drop the object. 1121 */ 1122 static int vm_object_terminate_callback(vm_page_t p, void *data); 1123 1124 void 1125 vm_object_terminate(vm_object_t object) 1126 { 1127 struct rb_vm_page_scan_info info; 1128 int n; 1129 1130 /* 1131 * Make sure no one uses us. Once we set OBJ_DEAD we should be 1132 * able to safely block. 1133 */ 1134 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1135 KKASSERT((object->flags & OBJ_DEAD) == 0); 1136 vm_object_set_flag(object, OBJ_DEAD); 1137 1138 /* 1139 * Wait for the pageout daemon to be done with the object 1140 */ 1141 vm_object_pip_wait(object, "objtrm1"); 1142 1143 KASSERT(!object->paging_in_progress, 1144 ("vm_object_terminate: pageout in progress")); 1145 1146 /* 1147 * Clean and free the pages, as appropriate. All references to the 1148 * object are gone, so we don't need to lock it. 1149 */ 1150 if (object->type == OBJT_VNODE) { 1151 struct vnode *vp; 1152 1153 /* 1154 * Clean pages and flush buffers. 1155 * 1156 * NOTE! TMPFS buffer flushes do not typically flush the 1157 * actual page to swap as this would be highly 1158 * inefficient, and normal filesystems usually wrap 1159 * page flushes with buffer cache buffers. 1160 * 1161 * To deal with this we have to call vinvalbuf() both 1162 * before and after the vm_object_page_clean(). 1163 */ 1164 vp = (struct vnode *) object->handle; 1165 vinvalbuf(vp, V_SAVE, 0, 0); 1166 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 1167 vinvalbuf(vp, V_SAVE, 0, 0); 1168 } 1169 1170 /* 1171 * Wait for any I/O to complete, after which there had better not 1172 * be any references left on the object. 1173 */ 1174 vm_object_pip_wait(object, "objtrm2"); 1175 1176 if (object->ref_count != 0) { 1177 panic("vm_object_terminate: object with references, " 1178 "ref_count=%d", object->ref_count); 1179 } 1180 1181 /* 1182 * Cleanup any shared pmaps associated with this object. 1183 */ 1184 pmap_object_free(object); 1185 1186 /* 1187 * Now free any remaining pages. For internal objects, this also 1188 * removes them from paging queues. Don't free wired pages, just 1189 * remove them from the object. 1190 */ 1191 info.count = 0; 1192 info.object = object; 1193 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 1194 vm_object_terminate_callback, &info); 1195 1196 /* 1197 * Let the pager know object is dead. 1198 */ 1199 vm_pager_deallocate(object); 1200 1201 /* 1202 * Wait for the object hold count to hit 1, clean out pages as 1203 * we go. vmobj_token interlocks any race conditions that might 1204 * pick the object up from the vm_object_list after we have cleared 1205 * rb_memq. 1206 */ 1207 for (;;) { 1208 if (RB_ROOT(&object->rb_memq) == NULL) 1209 break; 1210 kprintf("vm_object_terminate: Warning, object %p " 1211 "still has %d pages\n", 1212 object, object->resident_page_count); 1213 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 1214 vm_object_terminate_callback, &info); 1215 } 1216 1217 /* 1218 * There had better not be any pages left 1219 */ 1220 KKASSERT(object->resident_page_count == 0); 1221 1222 /* 1223 * Remove the object from the global object list. 1224 */ 1225 n = VMOBJ_HASH(object); 1226 lwkt_gettoken(&vmobj_tokens[n]); 1227 TAILQ_REMOVE(&vm_object_lists[n], object, object_list); 1228 lwkt_reltoken(&vmobj_tokens[n]); 1229 atomic_add_long(&vm_object_count, -1); 1230 1231 if (object->ref_count != 0) { 1232 panic("vm_object_terminate2: object with references, " 1233 "ref_count=%d", object->ref_count); 1234 } 1235 1236 /* 1237 * NOTE: The object hold_count is at least 1, so we cannot zfree() 1238 * the object here. See vm_object_drop(). 1239 */ 1240 } 1241 1242 /* 1243 * The caller must hold the object. 1244 */ 1245 static int 1246 vm_object_terminate_callback(vm_page_t p, void *data) 1247 { 1248 struct rb_vm_page_scan_info *info = data; 1249 vm_object_t object; 1250 1251 if ((++info->count & 63) == 0) 1252 lwkt_user_yield(); 1253 object = p->object; 1254 if (object != info->object) { 1255 kprintf("vm_object_terminate_callback: obj/pg race %p/%p\n", 1256 info->object, p); 1257 return(0); 1258 } 1259 vm_page_busy_wait(p, TRUE, "vmpgtrm"); 1260 if (object != p->object) { 1261 kprintf("vm_object_terminate: Warning: Encountered " 1262 "busied page %p on queue %d\n", p, p->queue); 1263 vm_page_wakeup(p); 1264 } else if (p->wire_count == 0) { 1265 /* 1266 * NOTE: p->dirty and PG_NEED_COMMIT are ignored. 1267 */ 1268 vm_page_free(p); 1269 mycpu->gd_cnt.v_pfree++; 1270 } else { 1271 if (p->queue != PQ_NONE) 1272 kprintf("vm_object_terminate: Warning: Encountered " 1273 "wired page %p on queue %d\n", p, p->queue); 1274 vm_page_remove(p); 1275 vm_page_wakeup(p); 1276 } 1277 return(0); 1278 } 1279 1280 /* 1281 * Clean all dirty pages in the specified range of object. Leaves page 1282 * on whatever queue it is currently on. If NOSYNC is set then do not 1283 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 1284 * leaving the object dirty. 1285 * 1286 * When stuffing pages asynchronously, allow clustering. XXX we need a 1287 * synchronous clustering mode implementation. 1288 * 1289 * Odd semantics: if start == end, we clean everything. 1290 * 1291 * The object must be locked? XXX 1292 */ 1293 static int vm_object_page_clean_pass1(struct vm_page *p, void *data); 1294 static int vm_object_page_clean_pass2(struct vm_page *p, void *data); 1295 1296 void 1297 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1298 int flags) 1299 { 1300 struct rb_vm_page_scan_info info; 1301 struct vnode *vp; 1302 int wholescan; 1303 int pagerflags; 1304 int generation; 1305 1306 vm_object_hold(object); 1307 if (object->type != OBJT_VNODE || 1308 (object->flags & OBJ_MIGHTBEDIRTY) == 0) { 1309 vm_object_drop(object); 1310 return; 1311 } 1312 1313 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? 1314 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 1315 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 1316 1317 vp = object->handle; 1318 1319 /* 1320 * Interlock other major object operations. This allows us to 1321 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY. 1322 */ 1323 vm_object_set_flag(object, OBJ_CLEANING); 1324 1325 /* 1326 * Handle 'entire object' case 1327 */ 1328 info.start_pindex = start; 1329 if (end == 0) { 1330 info.end_pindex = object->size - 1; 1331 } else { 1332 info.end_pindex = end - 1; 1333 } 1334 wholescan = (start == 0 && info.end_pindex == object->size - 1); 1335 info.limit = flags; 1336 info.pagerflags = pagerflags; 1337 info.object = object; 1338 info.count = 0; 1339 1340 /* 1341 * If cleaning the entire object do a pass to mark the pages read-only. 1342 * If everything worked out ok, clear OBJ_WRITEABLE and 1343 * OBJ_MIGHTBEDIRTY. 1344 */ 1345 if (wholescan) { 1346 info.error = 0; 1347 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1348 vm_object_page_clean_pass1, &info); 1349 if (info.error == 0) { 1350 vm_object_clear_flag(object, 1351 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1352 if (object->type == OBJT_VNODE && 1353 (vp = (struct vnode *)object->handle) != NULL) { 1354 /* 1355 * Use new-style interface to clear VISDIRTY 1356 * because the vnode is not necessarily removed 1357 * from the syncer list(s) as often as it was 1358 * under the old interface, which can leave 1359 * the vnode on the syncer list after reclaim. 1360 */ 1361 vclrobjdirty(vp); 1362 } 1363 } 1364 } 1365 1366 /* 1367 * Do a pass to clean all the dirty pages we find. 1368 */ 1369 do { 1370 info.error = 0; 1371 generation = object->generation; 1372 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1373 vm_object_page_clean_pass2, &info); 1374 } while (info.error || generation != object->generation); 1375 1376 vm_object_clear_flag(object, OBJ_CLEANING); 1377 vm_object_drop(object); 1378 } 1379 1380 /* 1381 * The caller must hold the object. 1382 */ 1383 static 1384 int 1385 vm_object_page_clean_pass1(struct vm_page *p, void *data) 1386 { 1387 struct rb_vm_page_scan_info *info = data; 1388 1389 if ((++info->count & 63) == 0) 1390 lwkt_user_yield(); 1391 if (p->object != info->object || 1392 p->pindex < info->start_pindex || 1393 p->pindex > info->end_pindex) { 1394 kprintf("vm_object_page_clean_pass1: obj/pg race %p/%p\n", 1395 info->object, p); 1396 return(0); 1397 } 1398 vm_page_flag_set(p, PG_CLEANCHK); 1399 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 1400 info->error = 1; 1401 } else if (vm_page_busy_try(p, FALSE) == 0) { 1402 if (p->object == info->object) 1403 vm_page_protect(p, VM_PROT_READ); 1404 vm_page_wakeup(p); 1405 } else { 1406 info->error = 1; 1407 } 1408 return(0); 1409 } 1410 1411 /* 1412 * The caller must hold the object 1413 */ 1414 static 1415 int 1416 vm_object_page_clean_pass2(struct vm_page *p, void *data) 1417 { 1418 struct rb_vm_page_scan_info *info = data; 1419 int generation; 1420 1421 if (p->object != info->object || 1422 p->pindex < info->start_pindex || 1423 p->pindex > info->end_pindex) { 1424 kprintf("vm_object_page_clean_pass2: obj/pg race %p/%p\n", 1425 info->object, p); 1426 return(0); 1427 } 1428 1429 /* 1430 * Do not mess with pages that were inserted after we started 1431 * the cleaning pass. 1432 */ 1433 if ((p->flags & PG_CLEANCHK) == 0) 1434 goto done; 1435 1436 generation = info->object->generation; 1437 vm_page_busy_wait(p, TRUE, "vpcwai"); 1438 1439 if (p->object != info->object || 1440 p->pindex < info->start_pindex || 1441 p->pindex > info->end_pindex || 1442 info->object->generation != generation) { 1443 info->error = 1; 1444 vm_page_wakeup(p); 1445 goto done; 1446 } 1447 1448 /* 1449 * Before wasting time traversing the pmaps, check for trivial 1450 * cases where the page cannot be dirty. 1451 */ 1452 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { 1453 KKASSERT((p->dirty & p->valid) == 0 && 1454 (p->flags & PG_NEED_COMMIT) == 0); 1455 vm_page_wakeup(p); 1456 goto done; 1457 } 1458 1459 /* 1460 * Check whether the page is dirty or not. The page has been set 1461 * to be read-only so the check will not race a user dirtying the 1462 * page. 1463 */ 1464 vm_page_test_dirty(p); 1465 if ((p->dirty & p->valid) == 0 && (p->flags & PG_NEED_COMMIT) == 0) { 1466 vm_page_flag_clear(p, PG_CLEANCHK); 1467 vm_page_wakeup(p); 1468 goto done; 1469 } 1470 1471 /* 1472 * If we have been asked to skip nosync pages and this is a 1473 * nosync page, skip it. Note that the object flags were 1474 * not cleared in this case (because pass1 will have returned an 1475 * error), so we do not have to set them. 1476 */ 1477 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 1478 vm_page_flag_clear(p, PG_CLEANCHK); 1479 vm_page_wakeup(p); 1480 goto done; 1481 } 1482 1483 /* 1484 * Flush as many pages as we can. PG_CLEANCHK will be cleared on 1485 * the pages that get successfully flushed. Set info->error if 1486 * we raced an object modification. 1487 */ 1488 vm_object_page_collect_flush(info->object, p, info->pagerflags); 1489 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */ 1490 done: 1491 if ((++info->count & 63) == 0) 1492 lwkt_user_yield(); 1493 1494 return(0); 1495 } 1496 1497 /* 1498 * Collect the specified page and nearby pages and flush them out. 1499 * The number of pages flushed is returned. The passed page is busied 1500 * by the caller and we are responsible for its disposition. 1501 * 1502 * The caller must hold the object. 1503 */ 1504 static void 1505 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags) 1506 { 1507 int error; 1508 int is; 1509 int ib; 1510 int i; 1511 int page_base; 1512 vm_pindex_t pi; 1513 vm_page_t ma[BLIST_MAX_ALLOC]; 1514 1515 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1516 1517 pi = p->pindex; 1518 page_base = pi % BLIST_MAX_ALLOC; 1519 ma[page_base] = p; 1520 ib = page_base - 1; 1521 is = page_base + 1; 1522 1523 while (ib >= 0) { 1524 vm_page_t tp; 1525 1526 tp = vm_page_lookup_busy_try(object, pi - page_base + ib, 1527 TRUE, &error); 1528 if (error) 1529 break; 1530 if (tp == NULL) 1531 break; 1532 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 1533 (tp->flags & PG_CLEANCHK) == 0) { 1534 vm_page_wakeup(tp); 1535 break; 1536 } 1537 if ((tp->queue - tp->pc) == PQ_CACHE) { 1538 vm_page_flag_clear(tp, PG_CLEANCHK); 1539 vm_page_wakeup(tp); 1540 break; 1541 } 1542 vm_page_test_dirty(tp); 1543 if ((tp->dirty & tp->valid) == 0 && 1544 (tp->flags & PG_NEED_COMMIT) == 0) { 1545 vm_page_flag_clear(tp, PG_CLEANCHK); 1546 vm_page_wakeup(tp); 1547 break; 1548 } 1549 ma[ib] = tp; 1550 --ib; 1551 } 1552 ++ib; /* fixup */ 1553 1554 while (is < BLIST_MAX_ALLOC && 1555 pi - page_base + is < object->size) { 1556 vm_page_t tp; 1557 1558 tp = vm_page_lookup_busy_try(object, pi - page_base + is, 1559 TRUE, &error); 1560 if (error) 1561 break; 1562 if (tp == NULL) 1563 break; 1564 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 1565 (tp->flags & PG_CLEANCHK) == 0) { 1566 vm_page_wakeup(tp); 1567 break; 1568 } 1569 if ((tp->queue - tp->pc) == PQ_CACHE) { 1570 vm_page_flag_clear(tp, PG_CLEANCHK); 1571 vm_page_wakeup(tp); 1572 break; 1573 } 1574 vm_page_test_dirty(tp); 1575 if ((tp->dirty & tp->valid) == 0 && 1576 (tp->flags & PG_NEED_COMMIT) == 0) { 1577 vm_page_flag_clear(tp, PG_CLEANCHK); 1578 vm_page_wakeup(tp); 1579 break; 1580 } 1581 ma[is] = tp; 1582 ++is; 1583 } 1584 1585 /* 1586 * All pages in the ma[] array are busied now 1587 */ 1588 for (i = ib; i < is; ++i) { 1589 vm_page_flag_clear(ma[i], PG_CLEANCHK); 1590 vm_page_hold(ma[i]); /* XXX need this any more? */ 1591 } 1592 vm_pageout_flush(&ma[ib], is - ib, pagerflags); 1593 for (i = ib; i < is; ++i) /* XXX need this any more? */ 1594 vm_page_unhold(ma[i]); 1595 } 1596 1597 /* 1598 * Same as vm_object_pmap_copy, except range checking really 1599 * works, and is meant for small sections of an object. 1600 * 1601 * This code protects resident pages by making them read-only 1602 * and is typically called on a fork or split when a page 1603 * is converted to copy-on-write. 1604 * 1605 * NOTE: If the page is already at VM_PROT_NONE, calling 1606 * vm_page_protect will have no effect. 1607 */ 1608 void 1609 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 1610 { 1611 vm_pindex_t idx; 1612 vm_page_t p; 1613 1614 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 1615 return; 1616 1617 vm_object_hold(object); 1618 for (idx = start; idx < end; idx++) { 1619 p = vm_page_lookup(object, idx); 1620 if (p == NULL) 1621 continue; 1622 vm_page_protect(p, VM_PROT_READ); 1623 } 1624 vm_object_drop(object); 1625 } 1626 1627 /* 1628 * Removes all physical pages in the specified object range from all 1629 * physical maps. 1630 * 1631 * The object must *not* be locked. 1632 */ 1633 1634 static int vm_object_pmap_remove_callback(vm_page_t p, void *data); 1635 1636 void 1637 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 1638 { 1639 struct rb_vm_page_scan_info info; 1640 1641 if (object == NULL) 1642 return; 1643 info.start_pindex = start; 1644 info.end_pindex = end - 1; 1645 info.count = 0; 1646 info.object = object; 1647 1648 vm_object_hold(object); 1649 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1650 vm_object_pmap_remove_callback, &info); 1651 if (start == 0 && end == object->size) 1652 vm_object_clear_flag(object, OBJ_WRITEABLE); 1653 vm_object_drop(object); 1654 } 1655 1656 /* 1657 * The caller must hold the object 1658 */ 1659 static int 1660 vm_object_pmap_remove_callback(vm_page_t p, void *data) 1661 { 1662 struct rb_vm_page_scan_info *info = data; 1663 1664 if ((++info->count & 63) == 0) 1665 lwkt_user_yield(); 1666 1667 if (info->object != p->object || 1668 p->pindex < info->start_pindex || 1669 p->pindex > info->end_pindex) { 1670 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n", 1671 info->object, p); 1672 return(0); 1673 } 1674 1675 vm_page_protect(p, VM_PROT_NONE); 1676 1677 return(0); 1678 } 1679 1680 /* 1681 * Implements the madvise function at the object/page level. 1682 * 1683 * MADV_WILLNEED (any object) 1684 * 1685 * Activate the specified pages if they are resident. 1686 * 1687 * MADV_DONTNEED (any object) 1688 * 1689 * Deactivate the specified pages if they are resident. 1690 * 1691 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only) 1692 * 1693 * Deactivate and clean the specified pages if they are 1694 * resident. This permits the process to reuse the pages 1695 * without faulting or the kernel to reclaim the pages 1696 * without I/O. 1697 * 1698 * No requirements. 1699 */ 1700 void 1701 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise) 1702 { 1703 vm_pindex_t end, tpindex; 1704 vm_object_t tobject; 1705 vm_object_t xobj; 1706 vm_page_t m; 1707 int error; 1708 1709 if (object == NULL) 1710 return; 1711 1712 end = pindex + count; 1713 1714 vm_object_hold(object); 1715 tobject = object; 1716 1717 /* 1718 * Locate and adjust resident pages 1719 */ 1720 for (; pindex < end; pindex += 1) { 1721 relookup: 1722 if (tobject != object) 1723 vm_object_drop(tobject); 1724 tobject = object; 1725 tpindex = pindex; 1726 shadowlookup: 1727 /* 1728 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 1729 * and those pages must be OBJ_ONEMAPPING. 1730 */ 1731 if (advise == MADV_FREE) { 1732 if ((tobject->type != OBJT_DEFAULT && 1733 tobject->type != OBJT_SWAP) || 1734 (tobject->flags & OBJ_ONEMAPPING) == 0) { 1735 continue; 1736 } 1737 } 1738 1739 m = vm_page_lookup_busy_try(tobject, tpindex, TRUE, &error); 1740 1741 if (error) { 1742 vm_page_sleep_busy(m, TRUE, "madvpo"); 1743 goto relookup; 1744 } 1745 if (m == NULL) { 1746 /* 1747 * There may be swap even if there is no backing page 1748 */ 1749 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1750 swap_pager_freespace(tobject, tpindex, 1); 1751 1752 /* 1753 * next object 1754 */ 1755 while ((xobj = tobject->backing_object) != NULL) { 1756 KKASSERT(xobj != object); 1757 vm_object_hold(xobj); 1758 if (xobj == tobject->backing_object) 1759 break; 1760 vm_object_drop(xobj); 1761 } 1762 if (xobj == NULL) 1763 continue; 1764 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1765 if (tobject != object) { 1766 vm_object_lock_swap(); 1767 vm_object_drop(tobject); 1768 } 1769 tobject = xobj; 1770 goto shadowlookup; 1771 } 1772 1773 /* 1774 * If the page is not in a normal active state, we skip it. 1775 * If the page is not managed there are no page queues to 1776 * mess with. Things can break if we mess with pages in 1777 * any of the below states. 1778 */ 1779 if (m->wire_count || 1780 (m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) || 1781 m->valid != VM_PAGE_BITS_ALL 1782 ) { 1783 vm_page_wakeup(m); 1784 continue; 1785 } 1786 1787 /* 1788 * Theoretically once a page is known not to be busy, an 1789 * interrupt cannot come along and rip it out from under us. 1790 */ 1791 1792 if (advise == MADV_WILLNEED) { 1793 vm_page_activate(m); 1794 } else if (advise == MADV_DONTNEED) { 1795 vm_page_dontneed(m); 1796 } else if (advise == MADV_FREE) { 1797 /* 1798 * Mark the page clean. This will allow the page 1799 * to be freed up by the system. However, such pages 1800 * are often reused quickly by malloc()/free() 1801 * so we do not do anything that would cause 1802 * a page fault if we can help it. 1803 * 1804 * Specifically, we do not try to actually free 1805 * the page now nor do we try to put it in the 1806 * cache (which would cause a page fault on reuse). 1807 * 1808 * But we do make the page is freeable as we 1809 * can without actually taking the step of unmapping 1810 * it. 1811 */ 1812 pmap_clear_modify(m); 1813 m->dirty = 0; 1814 m->act_count = 0; 1815 vm_page_dontneed(m); 1816 if (tobject->type == OBJT_SWAP) 1817 swap_pager_freespace(tobject, tpindex, 1); 1818 } 1819 vm_page_wakeup(m); 1820 } 1821 if (tobject != object) 1822 vm_object_drop(tobject); 1823 vm_object_drop(object); 1824 } 1825 1826 /* 1827 * Create a new object which is backed by the specified existing object 1828 * range. Replace the pointer and offset that was pointing at the existing 1829 * object with the pointer/offset for the new object. 1830 * 1831 * If addref is non-zero the returned object is given an additional reference. 1832 * This mechanic exists to avoid the situation where refs might be 1 and 1833 * race against a collapse when the caller intends to bump it. So the 1834 * caller cannot add the ref after the fact. Used when the caller is 1835 * duplicating a vm_map_entry. 1836 * 1837 * No other requirements. 1838 */ 1839 void 1840 vm_object_shadow(vm_object_t *objectp, vm_ooffset_t *offset, vm_size_t length, 1841 int addref) 1842 { 1843 vm_object_t source; 1844 vm_object_t result; 1845 int useshadowlist; 1846 1847 source = *objectp; 1848 1849 /* 1850 * Don't create the new object if the old object isn't shared. 1851 * We have to chain wait before adding the reference to avoid 1852 * racing a collapse or deallocation. 1853 * 1854 * Clear OBJ_ONEMAPPING flag when shadowing. 1855 * 1856 * The caller owns a ref on source via *objectp which we are going 1857 * to replace. This ref is inherited by the backing_object assignment. 1858 * from nobject and does not need to be incremented here. 1859 * 1860 * However, we add a temporary extra reference to the original source 1861 * prior to holding nobject in case we block, to avoid races where 1862 * someone else might believe that the source can be collapsed. 1863 */ 1864 useshadowlist = 0; 1865 if (source) { 1866 if (source->type != OBJT_VNODE) { 1867 useshadowlist = 1; 1868 vm_object_hold(source); 1869 vm_object_chain_wait(source, 0); 1870 if (source->ref_count == 1 && 1871 source->handle == NULL && 1872 (source->type == OBJT_DEFAULT || 1873 source->type == OBJT_SWAP)) { 1874 if (addref) { 1875 vm_object_reference_locked(source); 1876 vm_object_clear_flag(source, 1877 OBJ_ONEMAPPING); 1878 } 1879 vm_object_drop(source); 1880 return; 1881 } 1882 vm_object_reference_locked(source); 1883 vm_object_clear_flag(source, OBJ_ONEMAPPING); 1884 } else { 1885 vm_object_reference_quick(source); 1886 vm_object_clear_flag(source, OBJ_ONEMAPPING); 1887 } 1888 } 1889 1890 /* 1891 * Allocate a new object with the given length. The new object 1892 * is returned referenced but we may have to add another one. 1893 * If we are adding a second reference we must clear OBJ_ONEMAPPING. 1894 * (typically because the caller is about to clone a vm_map_entry). 1895 * 1896 * The source object currently has an extra reference to prevent 1897 * collapses into it while we mess with its shadow list, which 1898 * we will remove later in this routine. 1899 * 1900 * The target object may require a second reference if asked for one 1901 * by the caller. 1902 */ 1903 result = vm_object_allocate(OBJT_DEFAULT, length); 1904 if (result == NULL) 1905 panic("vm_object_shadow: no object for shadowing"); 1906 vm_object_hold(result); 1907 if (addref) { 1908 vm_object_reference_locked(result); 1909 vm_object_clear_flag(result, OBJ_ONEMAPPING); 1910 } 1911 1912 /* 1913 * The new object shadows the source object. Chain wait before 1914 * adjusting shadow_count or the shadow list to avoid races. 1915 * 1916 * Try to optimize the result object's page color when shadowing 1917 * in order to maintain page coloring consistency in the combined 1918 * shadowed object. 1919 * 1920 * The backing_object reference to source requires adding a ref to 1921 * source. We simply inherit the ref from the original *objectp 1922 * (which we are replacing) so no additional refs need to be added. 1923 * (we must still clean up the extra ref we had to prevent collapse 1924 * races). 1925 * 1926 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS 1927 */ 1928 KKASSERT(result->backing_object == NULL); 1929 result->backing_object = source; 1930 if (source) { 1931 if (useshadowlist) { 1932 vm_object_chain_wait(source, 0); 1933 LIST_INSERT_HEAD(&source->shadow_head, 1934 result, shadow_list); 1935 source->shadow_count++; 1936 source->generation++; 1937 vm_object_set_flag(result, OBJ_ONSHADOW); 1938 } 1939 /* cpu localization twist */ 1940 result->pg_color = (int)(intptr_t)curthread; 1941 } 1942 1943 /* 1944 * Adjust the return storage. Drop the ref on source before 1945 * returning. 1946 */ 1947 result->backing_object_offset = *offset; 1948 vm_object_drop(result); 1949 *offset = 0; 1950 if (source) { 1951 if (useshadowlist) { 1952 vm_object_deallocate_locked(source); 1953 vm_object_drop(source); 1954 } else { 1955 vm_object_deallocate(source); 1956 } 1957 } 1958 1959 /* 1960 * Return the new things 1961 */ 1962 *objectp = result; 1963 } 1964 1965 #define OBSC_TEST_ALL_SHADOWED 0x0001 1966 #define OBSC_COLLAPSE_NOWAIT 0x0002 1967 #define OBSC_COLLAPSE_WAIT 0x0004 1968 1969 static int vm_object_backing_scan_callback(vm_page_t p, void *data); 1970 1971 /* 1972 * The caller must hold the object. 1973 */ 1974 static __inline int 1975 vm_object_backing_scan(vm_object_t object, vm_object_t backing_object, int op) 1976 { 1977 struct rb_vm_page_scan_info info; 1978 int n; 1979 1980 vm_object_assert_held(object); 1981 vm_object_assert_held(backing_object); 1982 1983 KKASSERT(backing_object == object->backing_object); 1984 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1985 1986 /* 1987 * Initial conditions 1988 */ 1989 if (op & OBSC_TEST_ALL_SHADOWED) { 1990 /* 1991 * We do not want to have to test for the existence of 1992 * swap pages in the backing object. XXX but with the 1993 * new swapper this would be pretty easy to do. 1994 * 1995 * XXX what about anonymous MAP_SHARED memory that hasn't 1996 * been ZFOD faulted yet? If we do not test for this, the 1997 * shadow test may succeed! XXX 1998 */ 1999 if (backing_object->type != OBJT_DEFAULT) 2000 return(0); 2001 } 2002 if (op & OBSC_COLLAPSE_WAIT) { 2003 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 2004 vm_object_set_flag(backing_object, OBJ_DEAD); 2005 2006 n = VMOBJ_HASH(backing_object); 2007 lwkt_gettoken(&vmobj_tokens[n]); 2008 TAILQ_REMOVE(&vm_object_lists[n], backing_object, object_list); 2009 lwkt_reltoken(&vmobj_tokens[n]); 2010 atomic_add_long(&vm_object_count, -1); 2011 } 2012 2013 /* 2014 * Our scan. We have to retry if a negative error code is returned, 2015 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that 2016 * the scan had to be stopped because the parent does not completely 2017 * shadow the child. 2018 */ 2019 info.object = object; 2020 info.backing_object = backing_object; 2021 info.limit = op; 2022 do { 2023 info.error = 1; 2024 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL, 2025 vm_object_backing_scan_callback, 2026 &info); 2027 } while (info.error < 0); 2028 2029 return(info.error); 2030 } 2031 2032 /* 2033 * The caller must hold the object. 2034 */ 2035 static int 2036 vm_object_backing_scan_callback(vm_page_t p, void *data) 2037 { 2038 struct rb_vm_page_scan_info *info = data; 2039 vm_object_t backing_object; 2040 vm_object_t object; 2041 vm_pindex_t pindex; 2042 vm_pindex_t new_pindex; 2043 vm_pindex_t backing_offset_index; 2044 int op; 2045 2046 pindex = p->pindex; 2047 new_pindex = pindex - info->backing_offset_index; 2048 op = info->limit; 2049 object = info->object; 2050 backing_object = info->backing_object; 2051 backing_offset_index = info->backing_offset_index; 2052 2053 if (op & OBSC_TEST_ALL_SHADOWED) { 2054 vm_page_t pp; 2055 2056 /* 2057 * Ignore pages outside the parent object's range 2058 * and outside the parent object's mapping of the 2059 * backing object. 2060 * 2061 * note that we do not busy the backing object's 2062 * page. 2063 */ 2064 if (pindex < backing_offset_index || 2065 new_pindex >= object->size 2066 ) { 2067 return(0); 2068 } 2069 2070 /* 2071 * See if the parent has the page or if the parent's 2072 * object pager has the page. If the parent has the 2073 * page but the page is not valid, the parent's 2074 * object pager must have the page. 2075 * 2076 * If this fails, the parent does not completely shadow 2077 * the object and we might as well give up now. 2078 */ 2079 pp = vm_page_lookup(object, new_pindex); 2080 if ((pp == NULL || pp->valid == 0) && 2081 !vm_pager_has_page(object, new_pindex) 2082 ) { 2083 info->error = 0; /* problemo */ 2084 return(-1); /* stop the scan */ 2085 } 2086 } 2087 2088 /* 2089 * Check for busy page. Note that we may have lost (p) when we 2090 * possibly blocked above. 2091 */ 2092 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 2093 vm_page_t pp; 2094 2095 if (vm_page_busy_try(p, TRUE)) { 2096 if (op & OBSC_COLLAPSE_NOWAIT) { 2097 return(0); 2098 } else { 2099 /* 2100 * If we slept, anything could have 2101 * happened. Ask that the scan be restarted. 2102 * 2103 * Since the object is marked dead, the 2104 * backing offset should not have changed. 2105 */ 2106 vm_page_sleep_busy(p, TRUE, "vmocol"); 2107 info->error = -1; 2108 return(-1); 2109 } 2110 } 2111 2112 /* 2113 * If (p) is no longer valid restart the scan. 2114 */ 2115 if (p->object != backing_object || p->pindex != pindex) { 2116 kprintf("vm_object_backing_scan: Warning: page " 2117 "%p ripped out from under us\n", p); 2118 vm_page_wakeup(p); 2119 info->error = -1; 2120 return(-1); 2121 } 2122 2123 if (op & OBSC_COLLAPSE_NOWAIT) { 2124 if (p->valid == 0 || 2125 p->wire_count || 2126 (p->flags & PG_NEED_COMMIT)) { 2127 vm_page_wakeup(p); 2128 return(0); 2129 } 2130 } else { 2131 /* XXX what if p->valid == 0 , hold_count, etc? */ 2132 } 2133 2134 KASSERT( 2135 p->object == backing_object, 2136 ("vm_object_qcollapse(): object mismatch") 2137 ); 2138 2139 /* 2140 * Destroy any associated swap 2141 */ 2142 if (backing_object->type == OBJT_SWAP) 2143 swap_pager_freespace(backing_object, p->pindex, 1); 2144 2145 if ( 2146 p->pindex < backing_offset_index || 2147 new_pindex >= object->size 2148 ) { 2149 /* 2150 * Page is out of the parent object's range, we 2151 * can simply destroy it. 2152 */ 2153 vm_page_protect(p, VM_PROT_NONE); 2154 vm_page_free(p); 2155 return(0); 2156 } 2157 2158 pp = vm_page_lookup(object, new_pindex); 2159 if (pp != NULL || vm_pager_has_page(object, new_pindex)) { 2160 /* 2161 * page already exists in parent OR swap exists 2162 * for this location in the parent. Destroy 2163 * the original page from the backing object. 2164 * 2165 * Leave the parent's page alone 2166 */ 2167 vm_page_protect(p, VM_PROT_NONE); 2168 vm_page_free(p); 2169 return(0); 2170 } 2171 2172 /* 2173 * Page does not exist in parent, rename the 2174 * page from the backing object to the main object. 2175 * 2176 * If the page was mapped to a process, it can remain 2177 * mapped through the rename. 2178 */ 2179 if ((p->queue - p->pc) == PQ_CACHE) 2180 vm_page_deactivate(p); 2181 2182 vm_page_rename(p, object, new_pindex); 2183 vm_page_wakeup(p); 2184 /* page automatically made dirty by rename */ 2185 } 2186 return(0); 2187 } 2188 2189 /* 2190 * This version of collapse allows the operation to occur earlier and 2191 * when paging_in_progress is true for an object... This is not a complete 2192 * operation, but should plug 99.9% of the rest of the leaks. 2193 * 2194 * The caller must hold the object and backing_object and both must be 2195 * chainlocked. 2196 * 2197 * (only called from vm_object_collapse) 2198 */ 2199 static void 2200 vm_object_qcollapse(vm_object_t object, vm_object_t backing_object) 2201 { 2202 if (backing_object->ref_count == 1) { 2203 atomic_add_int(&backing_object->ref_count, 2); 2204 #if defined(DEBUG_LOCKS) 2205 debugvm_object_add(backing_object, "qcollapse", 1, 2); 2206 #endif 2207 vm_object_backing_scan(object, backing_object, 2208 OBSC_COLLAPSE_NOWAIT); 2209 atomic_add_int(&backing_object->ref_count, -2); 2210 #if defined(DEBUG_LOCKS) 2211 debugvm_object_add(backing_object, "qcollapse", 2, -2); 2212 #endif 2213 } 2214 } 2215 2216 /* 2217 * Collapse an object with the object backing it. Pages in the backing 2218 * object are moved into the parent, and the backing object is deallocated. 2219 * Any conflict is resolved in favor of the parent's existing pages. 2220 * 2221 * object must be held and chain-locked on call. 2222 * 2223 * The caller must have an extra ref on object to prevent a race from 2224 * destroying it during the collapse. 2225 */ 2226 void 2227 vm_object_collapse(vm_object_t object, struct vm_object_dealloc_list **dlistp) 2228 { 2229 struct vm_object_dealloc_list *dlist = NULL; 2230 vm_object_t backing_object; 2231 2232 /* 2233 * Only one thread is attempting a collapse at any given moment. 2234 * There are few restrictions for (object) that callers of this 2235 * function check so reentrancy is likely. 2236 */ 2237 KKASSERT(object != NULL); 2238 vm_object_assert_held(object); 2239 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL)); 2240 2241 for (;;) { 2242 vm_object_t bbobj; 2243 int dodealloc; 2244 2245 /* 2246 * We can only collapse a DEFAULT/SWAP object with a 2247 * DEFAULT/SWAP object. 2248 */ 2249 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) { 2250 backing_object = NULL; 2251 break; 2252 } 2253 2254 backing_object = object->backing_object; 2255 if (backing_object == NULL) 2256 break; 2257 if (backing_object->type != OBJT_DEFAULT && 2258 backing_object->type != OBJT_SWAP) { 2259 backing_object = NULL; 2260 break; 2261 } 2262 2263 /* 2264 * Hold the backing_object and check for races 2265 */ 2266 vm_object_hold(backing_object); 2267 if (backing_object != object->backing_object || 2268 (backing_object->type != OBJT_DEFAULT && 2269 backing_object->type != OBJT_SWAP)) { 2270 vm_object_drop(backing_object); 2271 continue; 2272 } 2273 2274 /* 2275 * Chain-lock the backing object too because if we 2276 * successfully merge its pages into the top object we 2277 * will collapse backing_object->backing_object as the 2278 * new backing_object. Re-check that it is still our 2279 * backing object. 2280 */ 2281 vm_object_chain_acquire(backing_object, 0); 2282 if (backing_object != object->backing_object) { 2283 vm_object_chain_release(backing_object); 2284 vm_object_drop(backing_object); 2285 continue; 2286 } 2287 2288 /* 2289 * we check the backing object first, because it is most likely 2290 * not collapsable. 2291 */ 2292 if (backing_object->handle != NULL || 2293 (backing_object->type != OBJT_DEFAULT && 2294 backing_object->type != OBJT_SWAP) || 2295 (backing_object->flags & OBJ_DEAD) || 2296 object->handle != NULL || 2297 (object->type != OBJT_DEFAULT && 2298 object->type != OBJT_SWAP) || 2299 (object->flags & OBJ_DEAD)) { 2300 break; 2301 } 2302 2303 /* 2304 * If paging is in progress we can't do a normal collapse. 2305 */ 2306 if ( 2307 object->paging_in_progress != 0 || 2308 backing_object->paging_in_progress != 0 2309 ) { 2310 vm_object_qcollapse(object, backing_object); 2311 break; 2312 } 2313 2314 /* 2315 * We know that we can either collapse the backing object (if 2316 * the parent is the only reference to it) or (perhaps) have 2317 * the parent bypass the object if the parent happens to shadow 2318 * all the resident pages in the entire backing object. 2319 * 2320 * This is ignoring pager-backed pages such as swap pages. 2321 * vm_object_backing_scan fails the shadowing test in this 2322 * case. 2323 */ 2324 if (backing_object->ref_count == 1) { 2325 /* 2326 * If there is exactly one reference to the backing 2327 * object, we can collapse it into the parent. 2328 */ 2329 KKASSERT(object->backing_object == backing_object); 2330 vm_object_backing_scan(object, backing_object, 2331 OBSC_COLLAPSE_WAIT); 2332 2333 /* 2334 * Move the pager from backing_object to object. 2335 */ 2336 if (backing_object->type == OBJT_SWAP) { 2337 vm_object_pip_add(backing_object, 1); 2338 2339 /* 2340 * scrap the paging_offset junk and do a 2341 * discrete copy. This also removes major 2342 * assumptions about how the swap-pager 2343 * works from where it doesn't belong. The 2344 * new swapper is able to optimize the 2345 * destroy-source case. 2346 */ 2347 vm_object_pip_add(object, 1); 2348 swap_pager_copy(backing_object, object, 2349 OFF_TO_IDX(object->backing_object_offset), 2350 TRUE); 2351 vm_object_pip_wakeup(object); 2352 vm_object_pip_wakeup(backing_object); 2353 } 2354 2355 /* 2356 * Object now shadows whatever backing_object did. 2357 * Remove object from backing_object's shadow_list. 2358 * 2359 * Removing object from backing_objects shadow list 2360 * requires releasing object, which we will do below. 2361 */ 2362 KKASSERT(object->backing_object == backing_object); 2363 if (object->flags & OBJ_ONSHADOW) { 2364 LIST_REMOVE(object, shadow_list); 2365 backing_object->shadow_count--; 2366 backing_object->generation++; 2367 vm_object_clear_flag(object, OBJ_ONSHADOW); 2368 } 2369 2370 /* 2371 * backing_object->backing_object moves from within 2372 * backing_object to within object. 2373 * 2374 * OBJT_VNODE bbobj's should have empty shadow lists. 2375 */ 2376 while ((bbobj = backing_object->backing_object) != NULL) { 2377 if (bbobj->type == OBJT_VNODE) 2378 vm_object_hold_shared(bbobj); 2379 else 2380 vm_object_hold(bbobj); 2381 if (bbobj == backing_object->backing_object) 2382 break; 2383 vm_object_drop(bbobj); 2384 } 2385 2386 /* 2387 * We are removing backing_object from bbobj's 2388 * shadow list and adding object to bbobj's shadow 2389 * list, so the ref_count on bbobj is unchanged. 2390 */ 2391 if (bbobj) { 2392 if (backing_object->flags & OBJ_ONSHADOW) { 2393 /* not locked exclusively if vnode */ 2394 KKASSERT(bbobj->type != OBJT_VNODE); 2395 LIST_REMOVE(backing_object, 2396 shadow_list); 2397 bbobj->shadow_count--; 2398 bbobj->generation++; 2399 vm_object_clear_flag(backing_object, 2400 OBJ_ONSHADOW); 2401 } 2402 backing_object->backing_object = NULL; 2403 } 2404 object->backing_object = bbobj; 2405 if (bbobj) { 2406 if (bbobj->type != OBJT_VNODE) { 2407 LIST_INSERT_HEAD(&bbobj->shadow_head, 2408 object, shadow_list); 2409 bbobj->shadow_count++; 2410 bbobj->generation++; 2411 vm_object_set_flag(object, 2412 OBJ_ONSHADOW); 2413 } 2414 } 2415 2416 object->backing_object_offset += 2417 backing_object->backing_object_offset; 2418 2419 vm_object_drop(bbobj); 2420 2421 /* 2422 * Discard the old backing_object. Nothing should be 2423 * able to ref it, other than a vm_map_split(), 2424 * and vm_map_split() will stall on our chain lock. 2425 * And we control the parent so it shouldn't be 2426 * possible for it to go away either. 2427 * 2428 * Since the backing object has no pages, no pager 2429 * left, and no object references within it, all 2430 * that is necessary is to dispose of it. 2431 */ 2432 KASSERT(backing_object->ref_count == 1, 2433 ("backing_object %p was somehow " 2434 "re-referenced during collapse!", 2435 backing_object)); 2436 KASSERT(RB_EMPTY(&backing_object->rb_memq), 2437 ("backing_object %p somehow has left " 2438 "over pages during collapse!", 2439 backing_object)); 2440 2441 /* 2442 * The object can be destroyed. 2443 * 2444 * XXX just fall through and dodealloc instead 2445 * of forcing destruction? 2446 */ 2447 atomic_add_int(&backing_object->ref_count, -1); 2448 #if defined(DEBUG_LOCKS) 2449 debugvm_object_add(backing_object, "collapse", 1, -1); 2450 #endif 2451 if ((backing_object->flags & OBJ_DEAD) == 0) 2452 vm_object_terminate(backing_object); 2453 object_collapses++; 2454 dodealloc = 0; 2455 } else { 2456 /* 2457 * If we do not entirely shadow the backing object, 2458 * there is nothing we can do so we give up. 2459 */ 2460 if (vm_object_backing_scan(object, backing_object, 2461 OBSC_TEST_ALL_SHADOWED) == 0) { 2462 break; 2463 } 2464 2465 /* 2466 * bbobj is backing_object->backing_object. Since 2467 * object completely shadows backing_object we can 2468 * bypass it and become backed by bbobj instead. 2469 * 2470 * The shadow list for vnode backing objects is not 2471 * used and a shared hold is allowed. 2472 */ 2473 while ((bbobj = backing_object->backing_object) != NULL) { 2474 if (bbobj->type == OBJT_VNODE) 2475 vm_object_hold_shared(bbobj); 2476 else 2477 vm_object_hold(bbobj); 2478 if (bbobj == backing_object->backing_object) 2479 break; 2480 vm_object_drop(bbobj); 2481 } 2482 2483 /* 2484 * Make object shadow bbobj instead of backing_object. 2485 * Remove object from backing_object's shadow list. 2486 * 2487 * Deallocating backing_object will not remove 2488 * it, since its reference count is at least 2. 2489 * 2490 * Removing object from backing_object's shadow 2491 * list requires releasing a ref, which we do 2492 * below by setting dodealloc to 1. 2493 */ 2494 KKASSERT(object->backing_object == backing_object); 2495 if (object->flags & OBJ_ONSHADOW) { 2496 LIST_REMOVE(object, shadow_list); 2497 backing_object->shadow_count--; 2498 backing_object->generation++; 2499 vm_object_clear_flag(object, OBJ_ONSHADOW); 2500 } 2501 2502 /* 2503 * Add a ref to bbobj, bbobj now shadows object. 2504 * 2505 * NOTE: backing_object->backing_object still points 2506 * to bbobj. That relationship remains intact 2507 * because backing_object has > 1 ref, so 2508 * someone else is pointing to it (hence why 2509 * we can't collapse it into object and can 2510 * only handle the all-shadowed bypass case). 2511 */ 2512 if (bbobj) { 2513 if (bbobj->type != OBJT_VNODE) { 2514 vm_object_chain_wait(bbobj, 0); 2515 vm_object_reference_locked(bbobj); 2516 LIST_INSERT_HEAD(&bbobj->shadow_head, 2517 object, shadow_list); 2518 bbobj->shadow_count++; 2519 bbobj->generation++; 2520 vm_object_set_flag(object, 2521 OBJ_ONSHADOW); 2522 } else { 2523 vm_object_reference_quick(bbobj); 2524 } 2525 object->backing_object_offset += 2526 backing_object->backing_object_offset; 2527 object->backing_object = bbobj; 2528 vm_object_drop(bbobj); 2529 } else { 2530 object->backing_object = NULL; 2531 } 2532 2533 /* 2534 * Drop the reference count on backing_object. To 2535 * handle ref_count races properly we can't assume 2536 * that the ref_count is still at least 2 so we 2537 * have to actually call vm_object_deallocate() 2538 * (after clearing the chainlock). 2539 */ 2540 object_bypasses++; 2541 dodealloc = 1; 2542 } 2543 2544 /* 2545 * Ok, we want to loop on the new object->bbobj association, 2546 * possibly collapsing it further. However if dodealloc is 2547 * non-zero we have to deallocate the backing_object which 2548 * itself can potentially undergo a collapse, creating a 2549 * recursion depth issue with the LWKT token subsystem. 2550 * 2551 * In the case where we must deallocate the backing_object 2552 * it is possible now that the backing_object has a single 2553 * shadow count on some other object (not represented here 2554 * as yet), since it no longer shadows us. Thus when we 2555 * call vm_object_deallocate() it may attempt to collapse 2556 * itself into its remaining parent. 2557 */ 2558 if (dodealloc) { 2559 struct vm_object_dealloc_list *dtmp; 2560 2561 vm_object_chain_release(backing_object); 2562 vm_object_unlock(backing_object); 2563 /* backing_object remains held */ 2564 2565 /* 2566 * Auto-deallocation list for caller convenience. 2567 */ 2568 if (dlistp == NULL) 2569 dlistp = &dlist; 2570 2571 dtmp = kmalloc(sizeof(*dtmp), M_TEMP, M_WAITOK); 2572 dtmp->object = backing_object; 2573 dtmp->next = *dlistp; 2574 *dlistp = dtmp; 2575 } else { 2576 vm_object_chain_release(backing_object); 2577 vm_object_drop(backing_object); 2578 } 2579 /* backing_object = NULL; not needed */ 2580 /* loop */ 2581 } 2582 2583 /* 2584 * Clean up any left over backing_object 2585 */ 2586 if (backing_object) { 2587 vm_object_chain_release(backing_object); 2588 vm_object_drop(backing_object); 2589 } 2590 2591 /* 2592 * Clean up any auto-deallocation list. This is a convenience 2593 * for top-level callers so they don't have to pass &dlist. 2594 * Do not clean up any caller-passed dlistp, the caller will 2595 * do that. 2596 */ 2597 if (dlist) 2598 vm_object_deallocate_list(&dlist); 2599 2600 } 2601 2602 /* 2603 * vm_object_collapse() may collect additional objects in need of 2604 * deallocation. This routine deallocates these objects. The 2605 * deallocation itself can trigger additional collapses (which the 2606 * deallocate function takes care of). This procedure is used to 2607 * reduce procedural recursion since these vm_object shadow chains 2608 * can become quite long. 2609 */ 2610 void 2611 vm_object_deallocate_list(struct vm_object_dealloc_list **dlistp) 2612 { 2613 struct vm_object_dealloc_list *dlist; 2614 2615 while ((dlist = *dlistp) != NULL) { 2616 *dlistp = dlist->next; 2617 vm_object_lock(dlist->object); 2618 vm_object_deallocate_locked(dlist->object); 2619 vm_object_drop(dlist->object); 2620 kfree(dlist, M_TEMP); 2621 } 2622 } 2623 2624 /* 2625 * Removes all physical pages in the specified object range from the 2626 * object's list of pages. 2627 * 2628 * No requirements. 2629 */ 2630 static int vm_object_page_remove_callback(vm_page_t p, void *data); 2631 2632 void 2633 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 2634 boolean_t clean_only) 2635 { 2636 struct rb_vm_page_scan_info info; 2637 int all; 2638 2639 /* 2640 * Degenerate cases and assertions 2641 */ 2642 vm_object_hold(object); 2643 if (object == NULL || 2644 (object->resident_page_count == 0 && object->swblock_count == 0)) { 2645 vm_object_drop(object); 2646 return; 2647 } 2648 KASSERT(object->type != OBJT_PHYS, 2649 ("attempt to remove pages from a physical object")); 2650 2651 /* 2652 * Indicate that paging is occuring on the object 2653 */ 2654 vm_object_pip_add(object, 1); 2655 2656 /* 2657 * Figure out the actual removal range and whether we are removing 2658 * the entire contents of the object or not. If removing the entire 2659 * contents, be sure to get all pages, even those that might be 2660 * beyond the end of the object. 2661 */ 2662 info.object = object; 2663 info.start_pindex = start; 2664 if (end == 0) 2665 info.end_pindex = (vm_pindex_t)-1; 2666 else 2667 info.end_pindex = end - 1; 2668 info.limit = clean_only; 2669 all = (start == 0 && info.end_pindex >= object->size - 1); 2670 2671 /* 2672 * Loop until we are sure we have gotten them all. 2673 */ 2674 do { 2675 info.error = 0; 2676 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 2677 vm_object_page_remove_callback, &info); 2678 } while (info.error); 2679 2680 /* 2681 * Remove any related swap if throwing away pages, or for 2682 * non-swap objects (the swap is a clean copy in that case). 2683 */ 2684 if (object->type != OBJT_SWAP || clean_only == FALSE) { 2685 if (all) 2686 swap_pager_freespace_all(object); 2687 else 2688 swap_pager_freespace(object, info.start_pindex, 2689 info.end_pindex - info.start_pindex + 1); 2690 } 2691 2692 /* 2693 * Cleanup 2694 */ 2695 vm_object_pip_wakeup(object); 2696 vm_object_drop(object); 2697 } 2698 2699 /* 2700 * The caller must hold the object 2701 */ 2702 static int 2703 vm_object_page_remove_callback(vm_page_t p, void *data) 2704 { 2705 struct rb_vm_page_scan_info *info = data; 2706 2707 if ((++info->count & 63) == 0) 2708 lwkt_user_yield(); 2709 2710 if (info->object != p->object || 2711 p->pindex < info->start_pindex || 2712 p->pindex > info->end_pindex) { 2713 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n", 2714 info->object, p); 2715 return(0); 2716 } 2717 if (vm_page_busy_try(p, TRUE)) { 2718 vm_page_sleep_busy(p, TRUE, "vmopar"); 2719 info->error = 1; 2720 return(0); 2721 } 2722 if (info->object != p->object) { 2723 /* this should never happen */ 2724 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n", 2725 info->object, p); 2726 vm_page_wakeup(p); 2727 return(0); 2728 } 2729 2730 /* 2731 * Wired pages cannot be destroyed, but they can be invalidated 2732 * and we do so if clean_only (limit) is not set. 2733 * 2734 * WARNING! The page may be wired due to being part of a buffer 2735 * cache buffer, and the buffer might be marked B_CACHE. 2736 * This is fine as part of a truncation but VFSs must be 2737 * sure to fix the buffer up when re-extending the file. 2738 * 2739 * NOTE! PG_NEED_COMMIT is ignored. 2740 */ 2741 if (p->wire_count != 0) { 2742 vm_page_protect(p, VM_PROT_NONE); 2743 if (info->limit == 0) 2744 p->valid = 0; 2745 vm_page_wakeup(p); 2746 return(0); 2747 } 2748 2749 /* 2750 * limit is our clean_only flag. If set and the page is dirty or 2751 * requires a commit, do not free it. If set and the page is being 2752 * held by someone, do not free it. 2753 */ 2754 if (info->limit && p->valid) { 2755 vm_page_test_dirty(p); 2756 if ((p->valid & p->dirty) || (p->flags & PG_NEED_COMMIT)) { 2757 vm_page_wakeup(p); 2758 return(0); 2759 } 2760 } 2761 2762 /* 2763 * Destroy the page 2764 */ 2765 vm_page_protect(p, VM_PROT_NONE); 2766 vm_page_free(p); 2767 2768 return(0); 2769 } 2770 2771 /* 2772 * Coalesces two objects backing up adjoining regions of memory into a 2773 * single object. 2774 * 2775 * returns TRUE if objects were combined. 2776 * 2777 * NOTE: Only works at the moment if the second object is NULL - 2778 * if it's not, which object do we lock first? 2779 * 2780 * Parameters: 2781 * prev_object First object to coalesce 2782 * prev_offset Offset into prev_object 2783 * next_object Second object into coalesce 2784 * next_offset Offset into next_object 2785 * 2786 * prev_size Size of reference to prev_object 2787 * next_size Size of reference to next_object 2788 * 2789 * The caller does not need to hold (prev_object) but must have a stable 2790 * pointer to it (typically by holding the vm_map locked). 2791 */ 2792 boolean_t 2793 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 2794 vm_size_t prev_size, vm_size_t next_size) 2795 { 2796 vm_pindex_t next_pindex; 2797 2798 if (prev_object == NULL) 2799 return (TRUE); 2800 2801 vm_object_hold(prev_object); 2802 2803 if (prev_object->type != OBJT_DEFAULT && 2804 prev_object->type != OBJT_SWAP) { 2805 vm_object_drop(prev_object); 2806 return (FALSE); 2807 } 2808 2809 /* 2810 * Try to collapse the object first 2811 */ 2812 vm_object_chain_acquire(prev_object, 0); 2813 vm_object_collapse(prev_object, NULL); 2814 2815 /* 2816 * Can't coalesce if: . more than one reference . paged out . shadows 2817 * another object . has a copy elsewhere (any of which mean that the 2818 * pages not mapped to prev_entry may be in use anyway) 2819 */ 2820 2821 if (prev_object->backing_object != NULL) { 2822 vm_object_chain_release(prev_object); 2823 vm_object_drop(prev_object); 2824 return (FALSE); 2825 } 2826 2827 prev_size >>= PAGE_SHIFT; 2828 next_size >>= PAGE_SHIFT; 2829 next_pindex = prev_pindex + prev_size; 2830 2831 if ((prev_object->ref_count > 1) && 2832 (prev_object->size != next_pindex)) { 2833 vm_object_chain_release(prev_object); 2834 vm_object_drop(prev_object); 2835 return (FALSE); 2836 } 2837 2838 /* 2839 * Remove any pages that may still be in the object from a previous 2840 * deallocation. 2841 */ 2842 if (next_pindex < prev_object->size) { 2843 vm_object_page_remove(prev_object, 2844 next_pindex, 2845 next_pindex + next_size, FALSE); 2846 if (prev_object->type == OBJT_SWAP) 2847 swap_pager_freespace(prev_object, 2848 next_pindex, next_size); 2849 } 2850 2851 /* 2852 * Extend the object if necessary. 2853 */ 2854 if (next_pindex + next_size > prev_object->size) 2855 prev_object->size = next_pindex + next_size; 2856 2857 vm_object_chain_release(prev_object); 2858 vm_object_drop(prev_object); 2859 return (TRUE); 2860 } 2861 2862 /* 2863 * Make the object writable and flag is being possibly dirty. 2864 * 2865 * The object might not be held (or might be held but held shared), 2866 * the related vnode is probably not held either. Object and vnode are 2867 * stable by virtue of the vm_page busied by the caller preventing 2868 * destruction. 2869 * 2870 * If the related mount is flagged MNTK_THR_SYNC we need to call 2871 * vsetobjdirty(). Filesystems using this option usually shortcut 2872 * synchronization by only scanning the syncer list. 2873 */ 2874 void 2875 vm_object_set_writeable_dirty(vm_object_t object) 2876 { 2877 struct vnode *vp; 2878 2879 /*vm_object_assert_held(object);*/ 2880 /* 2881 * Avoid contention in vm fault path by checking the state before 2882 * issuing an atomic op on it. 2883 */ 2884 if ((object->flags & (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) != 2885 (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) { 2886 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 2887 } 2888 if (object->type == OBJT_VNODE && 2889 (vp = (struct vnode *)object->handle) != NULL) { 2890 if ((vp->v_flag & VOBJDIRTY) == 0) { 2891 if (vp->v_mount && 2892 (vp->v_mount->mnt_kern_flag & MNTK_THR_SYNC)) { 2893 /* 2894 * New style THR_SYNC places vnodes on the 2895 * syncer list more deterministically. 2896 */ 2897 vsetobjdirty(vp); 2898 } else { 2899 /* 2900 * Old style scan would not necessarily place 2901 * a vnode on the syncer list when possibly 2902 * modified via mmap. 2903 */ 2904 vsetflags(vp, VOBJDIRTY); 2905 } 2906 } 2907 } 2908 } 2909 2910 #include "opt_ddb.h" 2911 #ifdef DDB 2912 #include <sys/kernel.h> 2913 2914 #include <sys/cons.h> 2915 2916 #include <ddb/ddb.h> 2917 2918 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 2919 vm_map_entry_t entry); 2920 static int vm_object_in_map (vm_object_t object); 2921 2922 /* 2923 * The caller must hold the object. 2924 */ 2925 static int 2926 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 2927 { 2928 vm_map_t tmpm; 2929 vm_map_entry_t tmpe; 2930 vm_object_t obj, nobj; 2931 int entcount; 2932 2933 if (map == 0) 2934 return 0; 2935 if (entry == 0) { 2936 tmpe = map->header.next; 2937 entcount = map->nentries; 2938 while (entcount-- && (tmpe != &map->header)) { 2939 if( _vm_object_in_map(map, object, tmpe)) { 2940 return 1; 2941 } 2942 tmpe = tmpe->next; 2943 } 2944 return (0); 2945 } 2946 switch(entry->maptype) { 2947 case VM_MAPTYPE_SUBMAP: 2948 tmpm = entry->object.sub_map; 2949 tmpe = tmpm->header.next; 2950 entcount = tmpm->nentries; 2951 while (entcount-- && tmpe != &tmpm->header) { 2952 if( _vm_object_in_map(tmpm, object, tmpe)) { 2953 return 1; 2954 } 2955 tmpe = tmpe->next; 2956 } 2957 break; 2958 case VM_MAPTYPE_NORMAL: 2959 case VM_MAPTYPE_VPAGETABLE: 2960 obj = entry->object.vm_object; 2961 while (obj) { 2962 if (obj == object) { 2963 if (obj != entry->object.vm_object) 2964 vm_object_drop(obj); 2965 return 1; 2966 } 2967 while ((nobj = obj->backing_object) != NULL) { 2968 vm_object_hold(nobj); 2969 if (nobj == obj->backing_object) 2970 break; 2971 vm_object_drop(nobj); 2972 } 2973 if (obj != entry->object.vm_object) { 2974 if (nobj) 2975 vm_object_lock_swap(); 2976 vm_object_drop(obj); 2977 } 2978 obj = nobj; 2979 } 2980 break; 2981 default: 2982 break; 2983 } 2984 return 0; 2985 } 2986 2987 static int vm_object_in_map_callback(struct proc *p, void *data); 2988 2989 struct vm_object_in_map_info { 2990 vm_object_t object; 2991 int rv; 2992 }; 2993 2994 /* 2995 * Debugging only 2996 */ 2997 static int 2998 vm_object_in_map(vm_object_t object) 2999 { 3000 struct vm_object_in_map_info info; 3001 3002 info.rv = 0; 3003 info.object = object; 3004 3005 allproc_scan(vm_object_in_map_callback, &info); 3006 if (info.rv) 3007 return 1; 3008 if( _vm_object_in_map(&kernel_map, object, 0)) 3009 return 1; 3010 if( _vm_object_in_map(&pager_map, object, 0)) 3011 return 1; 3012 if( _vm_object_in_map(&buffer_map, object, 0)) 3013 return 1; 3014 return 0; 3015 } 3016 3017 /* 3018 * Debugging only 3019 */ 3020 static int 3021 vm_object_in_map_callback(struct proc *p, void *data) 3022 { 3023 struct vm_object_in_map_info *info = data; 3024 3025 if (p->p_vmspace) { 3026 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) { 3027 info->rv = 1; 3028 return -1; 3029 } 3030 } 3031 return (0); 3032 } 3033 3034 DB_SHOW_COMMAND(vmochk, vm_object_check) 3035 { 3036 vm_object_t object; 3037 int n; 3038 3039 /* 3040 * make sure that internal objs are in a map somewhere 3041 * and none have zero ref counts. 3042 */ 3043 for (n = 0; n < VMOBJ_HSIZE; ++n) { 3044 for (object = TAILQ_FIRST(&vm_object_lists[n]); 3045 object != NULL; 3046 object = TAILQ_NEXT(object, object_list)) { 3047 if (object->type == OBJT_MARKER) 3048 continue; 3049 if (object->handle != NULL || 3050 (object->type != OBJT_DEFAULT && 3051 object->type != OBJT_SWAP)) { 3052 continue; 3053 } 3054 if (object->ref_count == 0) { 3055 db_printf("vmochk: internal obj has " 3056 "zero ref count: %ld\n", 3057 (long)object->size); 3058 } 3059 if (vm_object_in_map(object)) 3060 continue; 3061 db_printf("vmochk: internal obj is not in a map: " 3062 "ref: %d, size: %lu: 0x%lx, " 3063 "backing_object: %p\n", 3064 object->ref_count, (u_long)object->size, 3065 (u_long)object->size, 3066 (void *)object->backing_object); 3067 } 3068 } 3069 } 3070 3071 /* 3072 * Debugging only 3073 */ 3074 DB_SHOW_COMMAND(object, vm_object_print_static) 3075 { 3076 /* XXX convert args. */ 3077 vm_object_t object = (vm_object_t)addr; 3078 boolean_t full = have_addr; 3079 3080 vm_page_t p; 3081 3082 /* XXX count is an (unused) arg. Avoid shadowing it. */ 3083 #define count was_count 3084 3085 int count; 3086 3087 if (object == NULL) 3088 return; 3089 3090 db_iprintf( 3091 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 3092 object, (int)object->type, (u_long)object->size, 3093 object->resident_page_count, object->ref_count, object->flags); 3094 /* 3095 * XXX no %qd in kernel. Truncate object->backing_object_offset. 3096 */ 3097 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 3098 object->shadow_count, 3099 object->backing_object ? object->backing_object->ref_count : 0, 3100 object->backing_object, (long)object->backing_object_offset); 3101 3102 if (!full) 3103 return; 3104 3105 db_indent += 2; 3106 count = 0; 3107 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) { 3108 if (count == 0) 3109 db_iprintf("memory:="); 3110 else if (count == 6) { 3111 db_printf("\n"); 3112 db_iprintf(" ..."); 3113 count = 0; 3114 } else 3115 db_printf(","); 3116 count++; 3117 3118 db_printf("(off=0x%lx,page=0x%lx)", 3119 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 3120 } 3121 if (count != 0) 3122 db_printf("\n"); 3123 db_indent -= 2; 3124 } 3125 3126 /* XXX. */ 3127 #undef count 3128 3129 /* 3130 * XXX need this non-static entry for calling from vm_map_print. 3131 * 3132 * Debugging only 3133 */ 3134 void 3135 vm_object_print(/* db_expr_t */ long addr, 3136 boolean_t have_addr, 3137 /* db_expr_t */ long count, 3138 char *modif) 3139 { 3140 vm_object_print_static(addr, have_addr, count, modif); 3141 } 3142 3143 /* 3144 * Debugging only 3145 */ 3146 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 3147 { 3148 vm_object_t object; 3149 int nl = 0; 3150 int c; 3151 int n; 3152 3153 for (n = 0; n < VMOBJ_HSIZE; ++n) { 3154 for (object = TAILQ_FIRST(&vm_object_lists[n]); 3155 object != NULL; 3156 object = TAILQ_NEXT(object, object_list)) { 3157 vm_pindex_t idx, fidx; 3158 vm_pindex_t osize; 3159 vm_paddr_t pa = -1, padiff; 3160 int rcount; 3161 vm_page_t m; 3162 3163 if (object->type == OBJT_MARKER) 3164 continue; 3165 db_printf("new object: %p\n", (void *)object); 3166 if ( nl > 18) { 3167 c = cngetc(); 3168 if (c != ' ') 3169 return; 3170 nl = 0; 3171 } 3172 nl++; 3173 rcount = 0; 3174 fidx = 0; 3175 osize = object->size; 3176 if (osize > 128) 3177 osize = 128; 3178 for (idx = 0; idx < osize; idx++) { 3179 m = vm_page_lookup(object, idx); 3180 if (m == NULL) { 3181 if (rcount) { 3182 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 3183 (long)fidx, rcount, (long)pa); 3184 if ( nl > 18) { 3185 c = cngetc(); 3186 if (c != ' ') 3187 return; 3188 nl = 0; 3189 } 3190 nl++; 3191 rcount = 0; 3192 } 3193 continue; 3194 } 3195 3196 if (rcount && 3197 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 3198 ++rcount; 3199 continue; 3200 } 3201 if (rcount) { 3202 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 3203 padiff >>= PAGE_SHIFT; 3204 padiff &= PQ_L2_MASK; 3205 if (padiff == 0) { 3206 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 3207 ++rcount; 3208 continue; 3209 } 3210 db_printf(" index(%ld)run(%d)pa(0x%lx)", 3211 (long)fidx, rcount, (long)pa); 3212 db_printf("pd(%ld)\n", (long)padiff); 3213 if ( nl > 18) { 3214 c = cngetc(); 3215 if (c != ' ') 3216 return; 3217 nl = 0; 3218 } 3219 nl++; 3220 } 3221 fidx = idx; 3222 pa = VM_PAGE_TO_PHYS(m); 3223 rcount = 1; 3224 } 3225 if (rcount) { 3226 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 3227 (long)fidx, rcount, (long)pa); 3228 if ( nl > 18) { 3229 c = cngetc(); 3230 if (c != ' ') 3231 return; 3232 nl = 0; 3233 } 3234 nl++; 3235 } 3236 } 3237 } 3238 } 3239 #endif /* DDB */ 3240