1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 45 * 46 * Permission to use, copy, modify and distribute this software and 47 * its documentation is hereby granted, provided that both the copyright 48 * notice and this permission notice appear in all copies of the 49 * software, derivative works or modified versions, and any portions 50 * thereof, and that both notices appear in supporting documentation. 51 * 52 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 53 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 54 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 55 * 56 * Carnegie Mellon requests users of this software to return to 57 * 58 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 59 * School of Computer Science 60 * Carnegie Mellon University 61 * Pittsburgh PA 15213-3890 62 * 63 * any improvements or extensions that they make and grant Carnegie the 64 * rights to redistribute these changes. 65 * 66 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ 67 */ 68 69 /* 70 * Virtual memory object module. 71 */ 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/proc.h> /* for curproc, pageproc */ 76 #include <sys/thread.h> 77 #include <sys/vnode.h> 78 #include <sys/vmmeter.h> 79 #include <sys/mman.h> 80 #include <sys/mount.h> 81 #include <sys/kernel.h> 82 #include <sys/sysctl.h> 83 #include <sys/refcount.h> 84 85 #include <vm/vm.h> 86 #include <vm/vm_param.h> 87 #include <vm/pmap.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_object.h> 90 #include <vm/vm_page.h> 91 #include <vm/vm_pageout.h> 92 #include <vm/vm_pager.h> 93 #include <vm/swap_pager.h> 94 #include <vm/vm_kern.h> 95 #include <vm/vm_extern.h> 96 #include <vm/vm_zone.h> 97 98 #define EASY_SCAN_FACTOR 8 99 100 static void vm_object_qcollapse(vm_object_t object); 101 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, 102 int pagerflags); 103 static void vm_object_lock_init(vm_object_t); 104 static void vm_object_hold_wake(vm_object_t); 105 static void vm_object_hold_wait(vm_object_t); 106 107 108 /* 109 * Virtual memory objects maintain the actual data 110 * associated with allocated virtual memory. A given 111 * page of memory exists within exactly one object. 112 * 113 * An object is only deallocated when all "references" 114 * are given up. Only one "reference" to a given 115 * region of an object should be writeable. 116 * 117 * Associated with each object is a list of all resident 118 * memory pages belonging to that object; this list is 119 * maintained by the "vm_page" module, and locked by the object's 120 * lock. 121 * 122 * Each object also records a "pager" routine which is 123 * used to retrieve (and store) pages to the proper backing 124 * storage. In addition, objects may be backed by other 125 * objects from which they were virtual-copied. 126 * 127 * The only items within the object structure which are 128 * modified after time of creation are: 129 * reference count locked by object's lock 130 * pager routine locked by object's lock 131 * 132 */ 133 134 struct object_q vm_object_list; /* locked by vmobj_token */ 135 struct vm_object kernel_object; 136 137 static long vm_object_count; /* locked by vmobj_token */ 138 extern int vm_pageout_page_count; 139 140 static long object_collapses; 141 static long object_bypasses; 142 static int next_index; 143 static vm_zone_t obj_zone; 144 static struct vm_zone obj_zone_store; 145 #define VM_OBJECTS_INIT 256 146 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 147 148 /* 149 * Initialize a freshly allocated object 150 * 151 * Used only by vm_object_allocate() and zinitna(). 152 * 153 * No requirements. 154 */ 155 void 156 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object) 157 { 158 int incr; 159 160 RB_INIT(&object->rb_memq); 161 LIST_INIT(&object->shadow_head); 162 163 object->type = type; 164 object->size = size; 165 object->ref_count = 1; 166 object->hold_count = 0; 167 object->flags = 0; 168 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 169 vm_object_set_flag(object, OBJ_ONEMAPPING); 170 object->paging_in_progress = 0; 171 object->resident_page_count = 0; 172 object->agg_pv_list_count = 0; 173 object->shadow_count = 0; 174 object->pg_color = next_index; 175 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 176 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 177 else 178 incr = size; 179 next_index = (next_index + incr) & PQ_L2_MASK; 180 object->handle = NULL; 181 object->backing_object = NULL; 182 object->backing_object_offset = (vm_ooffset_t) 0; 183 184 object->generation++; 185 object->swblock_count = 0; 186 RB_INIT(&object->swblock_root); 187 vm_object_lock_init(object); 188 189 lwkt_gettoken(&vmobj_token); 190 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 191 vm_object_count++; 192 lwkt_reltoken(&vmobj_token); 193 } 194 195 /* 196 * Initialize the VM objects module. 197 * 198 * Called from the low level boot code only. 199 */ 200 void 201 vm_object_init(void) 202 { 203 TAILQ_INIT(&vm_object_list); 204 205 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd), 206 &kernel_object); 207 208 obj_zone = &obj_zone_store; 209 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 210 vm_objects_init, VM_OBJECTS_INIT); 211 } 212 213 void 214 vm_object_init2(void) 215 { 216 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 217 } 218 219 /* 220 * Allocate and return a new object of the specified type and size. 221 * 222 * No requirements. 223 */ 224 vm_object_t 225 vm_object_allocate(objtype_t type, vm_pindex_t size) 226 { 227 vm_object_t result; 228 229 result = (vm_object_t) zalloc(obj_zone); 230 231 _vm_object_allocate(type, size, result); 232 233 return (result); 234 } 235 236 /* 237 * Add an additional reference to a vm_object. 238 * 239 * Object passed by caller must be stable or caller must already 240 * hold vmobj_token to avoid races. 241 */ 242 void 243 vm_object_reference(vm_object_t object) 244 { 245 lwkt_gettoken(&vmobj_token); 246 vm_object_reference_locked(object); 247 lwkt_reltoken(&vmobj_token); 248 } 249 250 void 251 vm_object_reference_locked(vm_object_t object) 252 { 253 if (object) { 254 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 255 object->ref_count++; 256 if (object->type == OBJT_VNODE) { 257 vref(object->handle); 258 /* XXX what if the vnode is being destroyed? */ 259 } 260 } 261 } 262 263 /* 264 * Dereference an object and its underlying vnode. 265 * 266 * The caller must hold vmobj_token. 267 */ 268 static void 269 vm_object_vndeallocate(vm_object_t object) 270 { 271 struct vnode *vp = (struct vnode *) object->handle; 272 273 KASSERT(object->type == OBJT_VNODE, 274 ("vm_object_vndeallocate: not a vnode object")); 275 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 276 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 277 #ifdef INVARIANTS 278 if (object->ref_count == 0) { 279 vprint("vm_object_vndeallocate", vp); 280 panic("vm_object_vndeallocate: bad object reference count"); 281 } 282 #endif 283 284 object->ref_count--; 285 if (object->ref_count == 0) 286 vclrflags(vp, VTEXT); 287 vrele(vp); 288 } 289 290 /* 291 * Release a reference to the specified object, gained either through a 292 * vm_object_allocate or a vm_object_reference call. When all references 293 * are gone, storage associated with this object may be relinquished. 294 */ 295 void 296 vm_object_deallocate(vm_object_t object) 297 { 298 lwkt_gettoken(&vmobj_token); 299 vm_object_deallocate_locked(object); 300 lwkt_reltoken(&vmobj_token); 301 } 302 303 void 304 vm_object_deallocate_locked(vm_object_t object) 305 { 306 vm_object_t temp; 307 308 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 309 310 while (object != NULL) { 311 if (object->type == OBJT_VNODE) { 312 vm_object_vndeallocate(object); 313 break; 314 } 315 316 if (object->ref_count == 0) { 317 panic("vm_object_deallocate: object deallocated " 318 "too many times: %d", object->type); 319 } 320 if (object->ref_count > 2) { 321 object->ref_count--; 322 break; 323 } 324 325 /* 326 * We currently need the vm_token from this point on, and 327 * we must recheck ref_count after acquiring it. 328 */ 329 lwkt_gettoken(&vm_token); 330 331 if (object->ref_count > 2) { 332 object->ref_count--; 333 lwkt_reltoken(&vm_token); 334 break; 335 } 336 337 /* 338 * Here on ref_count of one or two, which are special cases for 339 * objects. 340 */ 341 if ((object->ref_count == 2) && (object->shadow_count == 0)) { 342 vm_object_set_flag(object, OBJ_ONEMAPPING); 343 object->ref_count--; 344 lwkt_reltoken(&vm_token); 345 break; 346 } 347 if ((object->ref_count == 2) && (object->shadow_count == 1)) { 348 object->ref_count--; 349 if ((object->handle == NULL) && 350 (object->type == OBJT_DEFAULT || 351 object->type == OBJT_SWAP)) { 352 vm_object_t robject; 353 354 robject = LIST_FIRST(&object->shadow_head); 355 KASSERT(robject != NULL, 356 ("vm_object_deallocate: ref_count: " 357 "%d, shadow_count: %d", 358 object->ref_count, 359 object->shadow_count)); 360 361 if ((robject->handle == NULL) && 362 (robject->type == OBJT_DEFAULT || 363 robject->type == OBJT_SWAP)) { 364 365 robject->ref_count++; 366 367 while ( 368 robject->paging_in_progress || 369 object->paging_in_progress 370 ) { 371 vm_object_pip_sleep(robject, "objde1"); 372 vm_object_pip_sleep(object, "objde2"); 373 } 374 375 if (robject->ref_count == 1) { 376 robject->ref_count--; 377 object = robject; 378 goto doterm; 379 } 380 381 object = robject; 382 vm_object_collapse(object); 383 lwkt_reltoken(&vm_token); 384 continue; 385 } 386 } 387 lwkt_reltoken(&vm_token); 388 break; 389 } 390 391 /* 392 * Normal dereferencing path 393 */ 394 object->ref_count--; 395 if (object->ref_count != 0) { 396 lwkt_reltoken(&vm_token); 397 break; 398 } 399 400 /* 401 * Termination path 402 */ 403 doterm: 404 temp = object->backing_object; 405 if (temp) { 406 LIST_REMOVE(object, shadow_list); 407 temp->shadow_count--; 408 temp->generation++; 409 object->backing_object = NULL; 410 } 411 lwkt_reltoken(&vm_token); 412 413 /* 414 * Don't double-terminate, we could be in a termination 415 * recursion due to the terminate having to sync data 416 * to disk. 417 */ 418 if ((object->flags & OBJ_DEAD) == 0) 419 vm_object_terminate(object); 420 object = temp; 421 } 422 } 423 424 /* 425 * Destroy the specified object, freeing up related resources. 426 * 427 * The object must have zero references. 428 * 429 * The caller must be holding vmobj_token and properly interlock with 430 * OBJ_DEAD. 431 */ 432 static int vm_object_terminate_callback(vm_page_t p, void *data); 433 434 void 435 vm_object_terminate(vm_object_t object) 436 { 437 /* 438 * Make sure no one uses us. Once we set OBJ_DEAD we should be 439 * able to safely block. 440 */ 441 KKASSERT((object->flags & OBJ_DEAD) == 0); 442 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 443 vm_object_set_flag(object, OBJ_DEAD); 444 445 /* 446 * Wait for the pageout daemon to be done with the object 447 */ 448 vm_object_pip_wait(object, "objtrm1"); 449 450 KASSERT(!object->paging_in_progress, 451 ("vm_object_terminate: pageout in progress")); 452 453 /* 454 * Clean and free the pages, as appropriate. All references to the 455 * object are gone, so we don't need to lock it. 456 */ 457 if (object->type == OBJT_VNODE) { 458 struct vnode *vp; 459 460 /* 461 * Clean pages and flush buffers. 462 */ 463 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 464 465 vp = (struct vnode *) object->handle; 466 vinvalbuf(vp, V_SAVE, 0, 0); 467 } 468 469 /* 470 * Wait for any I/O to complete, after which there had better not 471 * be any references left on the object. 472 */ 473 vm_object_pip_wait(object, "objtrm2"); 474 475 if (object->ref_count != 0) { 476 panic("vm_object_terminate: object with references, " 477 "ref_count=%d", object->ref_count); 478 } 479 480 /* 481 * Now free any remaining pages. For internal objects, this also 482 * removes them from paging queues. Don't free wired pages, just 483 * remove them from the object. 484 */ 485 lwkt_gettoken(&vm_token); 486 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 487 vm_object_terminate_callback, NULL); 488 lwkt_reltoken(&vm_token); 489 490 /* 491 * Let the pager know object is dead. 492 */ 493 vm_pager_deallocate(object); 494 495 /* 496 * Wait for the object hold count to hit zero 497 */ 498 vm_object_hold_wait(object); 499 500 /* 501 * Remove the object from the global object list. 502 * 503 * (we are holding vmobj_token) 504 */ 505 TAILQ_REMOVE(&vm_object_list, object, object_list); 506 vm_object_count--; 507 vm_object_dead_wakeup(object); 508 509 if (object->ref_count != 0) { 510 panic("vm_object_terminate2: object with references, " 511 "ref_count=%d", object->ref_count); 512 } 513 514 /* 515 * Free the space for the object. 516 */ 517 zfree(obj_zone, object); 518 } 519 520 /* 521 * The caller must hold vm_token. 522 */ 523 static int 524 vm_object_terminate_callback(vm_page_t p, void *data __unused) 525 { 526 if (p->busy || (p->flags & PG_BUSY)) 527 panic("vm_object_terminate: freeing busy page %p", p); 528 if (p->wire_count == 0) { 529 vm_page_busy(p); 530 vm_page_free(p); 531 mycpu->gd_cnt.v_pfree++; 532 } else { 533 if (p->queue != PQ_NONE) 534 kprintf("vm_object_terminate: Warning: Encountered wired page %p on queue %d\n", p, p->queue); 535 vm_page_busy(p); 536 vm_page_remove(p); 537 vm_page_wakeup(p); 538 } 539 return(0); 540 } 541 542 /* 543 * The object is dead but still has an object<->pager association. Sleep 544 * and return. The caller typically retests the association in a loop. 545 * 546 * Must be called with the vmobj_token held. 547 */ 548 void 549 vm_object_dead_sleep(vm_object_t object, const char *wmesg) 550 { 551 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 552 if (object->handle) { 553 vm_object_set_flag(object, OBJ_DEADWNT); 554 tsleep(object, 0, wmesg, 0); 555 /* object may be invalid after this point */ 556 } 557 } 558 559 /* 560 * Wakeup anyone waiting for the object<->pager disassociation on 561 * a dead object. 562 * 563 * Must be called with the vmobj_token held. 564 */ 565 void 566 vm_object_dead_wakeup(vm_object_t object) 567 { 568 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 569 if (object->flags & OBJ_DEADWNT) { 570 vm_object_clear_flag(object, OBJ_DEADWNT); 571 wakeup(object); 572 } 573 } 574 575 /* 576 * Clean all dirty pages in the specified range of object. Leaves page 577 * on whatever queue it is currently on. If NOSYNC is set then do not 578 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 579 * leaving the object dirty. 580 * 581 * When stuffing pages asynchronously, allow clustering. XXX we need a 582 * synchronous clustering mode implementation. 583 * 584 * Odd semantics: if start == end, we clean everything. 585 * 586 * The object must be locked? XXX 587 */ 588 static int vm_object_page_clean_pass1(struct vm_page *p, void *data); 589 static int vm_object_page_clean_pass2(struct vm_page *p, void *data); 590 591 void 592 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 593 int flags) 594 { 595 struct rb_vm_page_scan_info info; 596 struct vnode *vp; 597 int wholescan; 598 int pagerflags; 599 int curgeneration; 600 601 lwkt_gettoken(&vm_token); 602 if (object->type != OBJT_VNODE || 603 (object->flags & OBJ_MIGHTBEDIRTY) == 0) { 604 lwkt_reltoken(&vm_token); 605 return; 606 } 607 608 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? 609 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 610 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 611 612 vp = object->handle; 613 614 /* 615 * Interlock other major object operations. This allows us to 616 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY. 617 */ 618 crit_enter(); 619 vm_object_set_flag(object, OBJ_CLEANING); 620 621 /* 622 * Handle 'entire object' case 623 */ 624 info.start_pindex = start; 625 if (end == 0) { 626 info.end_pindex = object->size - 1; 627 } else { 628 info.end_pindex = end - 1; 629 } 630 wholescan = (start == 0 && info.end_pindex == object->size - 1); 631 info.limit = flags; 632 info.pagerflags = pagerflags; 633 info.object = object; 634 635 /* 636 * If cleaning the entire object do a pass to mark the pages read-only. 637 * If everything worked out ok, clear OBJ_WRITEABLE and 638 * OBJ_MIGHTBEDIRTY. 639 */ 640 if (wholescan) { 641 info.error = 0; 642 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 643 vm_object_page_clean_pass1, &info); 644 if (info.error == 0) { 645 vm_object_clear_flag(object, 646 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 647 if (object->type == OBJT_VNODE && 648 (vp = (struct vnode *)object->handle) != NULL) { 649 if (vp->v_flag & VOBJDIRTY) 650 vclrflags(vp, VOBJDIRTY); 651 } 652 } 653 } 654 655 /* 656 * Do a pass to clean all the dirty pages we find. 657 */ 658 do { 659 info.error = 0; 660 curgeneration = object->generation; 661 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 662 vm_object_page_clean_pass2, &info); 663 } while (info.error || curgeneration != object->generation); 664 665 vm_object_clear_flag(object, OBJ_CLEANING); 666 crit_exit(); 667 lwkt_reltoken(&vm_token); 668 } 669 670 /* 671 * The caller must hold vm_token. 672 */ 673 static 674 int 675 vm_object_page_clean_pass1(struct vm_page *p, void *data) 676 { 677 struct rb_vm_page_scan_info *info = data; 678 679 vm_page_flag_set(p, PG_CLEANCHK); 680 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) 681 info->error = 1; 682 else 683 vm_page_protect(p, VM_PROT_READ); /* must not block */ 684 return(0); 685 } 686 687 /* 688 * The caller must hold vm_token. 689 */ 690 static 691 int 692 vm_object_page_clean_pass2(struct vm_page *p, void *data) 693 { 694 struct rb_vm_page_scan_info *info = data; 695 int n; 696 697 /* 698 * Do not mess with pages that were inserted after we started 699 * the cleaning pass. 700 */ 701 if ((p->flags & PG_CLEANCHK) == 0) 702 return(0); 703 704 /* 705 * Before wasting time traversing the pmaps, check for trivial 706 * cases where the page cannot be dirty. 707 */ 708 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { 709 KKASSERT((p->dirty & p->valid) == 0); 710 return(0); 711 } 712 713 /* 714 * Check whether the page is dirty or not. The page has been set 715 * to be read-only so the check will not race a user dirtying the 716 * page. 717 */ 718 vm_page_test_dirty(p); 719 if ((p->dirty & p->valid) == 0) { 720 vm_page_flag_clear(p, PG_CLEANCHK); 721 return(0); 722 } 723 724 /* 725 * If we have been asked to skip nosync pages and this is a 726 * nosync page, skip it. Note that the object flags were 727 * not cleared in this case (because pass1 will have returned an 728 * error), so we do not have to set them. 729 */ 730 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 731 vm_page_flag_clear(p, PG_CLEANCHK); 732 return(0); 733 } 734 735 /* 736 * Flush as many pages as we can. PG_CLEANCHK will be cleared on 737 * the pages that get successfully flushed. Set info->error if 738 * we raced an object modification. 739 */ 740 n = vm_object_page_collect_flush(info->object, p, info->pagerflags); 741 if (n == 0) 742 info->error = 1; 743 return(0); 744 } 745 746 /* 747 * Collect the specified page and nearby pages and flush them out. 748 * The number of pages flushed is returned. 749 * 750 * The caller must hold vm_token. 751 */ 752 static int 753 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags) 754 { 755 int runlen; 756 int maxf; 757 int chkb; 758 int maxb; 759 int i; 760 int curgeneration; 761 vm_pindex_t pi; 762 vm_page_t maf[vm_pageout_page_count]; 763 vm_page_t mab[vm_pageout_page_count]; 764 vm_page_t ma[vm_pageout_page_count]; 765 766 curgeneration = object->generation; 767 768 pi = p->pindex; 769 while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { 770 if (object->generation != curgeneration) { 771 return(0); 772 } 773 } 774 KKASSERT(p->object == object && p->pindex == pi); 775 776 maxf = 0; 777 for(i = 1; i < vm_pageout_page_count; i++) { 778 vm_page_t tp; 779 780 if ((tp = vm_page_lookup(object, pi + i)) != NULL) { 781 if ((tp->flags & PG_BUSY) || 782 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 783 (tp->flags & PG_CLEANCHK) == 0) || 784 (tp->busy != 0)) 785 break; 786 if((tp->queue - tp->pc) == PQ_CACHE) { 787 vm_page_flag_clear(tp, PG_CLEANCHK); 788 break; 789 } 790 vm_page_test_dirty(tp); 791 if ((tp->dirty & tp->valid) == 0) { 792 vm_page_flag_clear(tp, PG_CLEANCHK); 793 break; 794 } 795 maf[ i - 1 ] = tp; 796 maxf++; 797 continue; 798 } 799 break; 800 } 801 802 maxb = 0; 803 chkb = vm_pageout_page_count - maxf; 804 if (chkb) { 805 for(i = 1; i < chkb;i++) { 806 vm_page_t tp; 807 808 if ((tp = vm_page_lookup(object, pi - i)) != NULL) { 809 if ((tp->flags & PG_BUSY) || 810 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 811 (tp->flags & PG_CLEANCHK) == 0) || 812 (tp->busy != 0)) 813 break; 814 if((tp->queue - tp->pc) == PQ_CACHE) { 815 vm_page_flag_clear(tp, PG_CLEANCHK); 816 break; 817 } 818 vm_page_test_dirty(tp); 819 if ((tp->dirty & tp->valid) == 0) { 820 vm_page_flag_clear(tp, PG_CLEANCHK); 821 break; 822 } 823 mab[ i - 1 ] = tp; 824 maxb++; 825 continue; 826 } 827 break; 828 } 829 } 830 831 for(i = 0; i < maxb; i++) { 832 int index = (maxb - i) - 1; 833 ma[index] = mab[i]; 834 vm_page_flag_clear(ma[index], PG_CLEANCHK); 835 } 836 vm_page_flag_clear(p, PG_CLEANCHK); 837 ma[maxb] = p; 838 for(i = 0; i < maxf; i++) { 839 int index = (maxb + i) + 1; 840 ma[index] = maf[i]; 841 vm_page_flag_clear(ma[index], PG_CLEANCHK); 842 } 843 runlen = maxb + maxf + 1; 844 845 vm_pageout_flush(ma, runlen, pagerflags); 846 for (i = 0; i < runlen; i++) { 847 if (ma[i]->valid & ma[i]->dirty) { 848 vm_page_protect(ma[i], VM_PROT_READ); 849 vm_page_flag_set(ma[i], PG_CLEANCHK); 850 851 /* 852 * maxf will end up being the actual number of pages 853 * we wrote out contiguously, non-inclusive of the 854 * first page. We do not count look-behind pages. 855 */ 856 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 857 maxf = i - maxb - 1; 858 } 859 } 860 return(maxf + 1); 861 } 862 863 /* 864 * Same as vm_object_pmap_copy, except range checking really 865 * works, and is meant for small sections of an object. 866 * 867 * This code protects resident pages by making them read-only 868 * and is typically called on a fork or split when a page 869 * is converted to copy-on-write. 870 * 871 * NOTE: If the page is already at VM_PROT_NONE, calling 872 * vm_page_protect will have no effect. 873 */ 874 void 875 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 876 { 877 vm_pindex_t idx; 878 vm_page_t p; 879 880 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 881 return; 882 883 /* 884 * spl protection needed to prevent races between the lookup, 885 * an interrupt unbusy/free, and our protect call. 886 */ 887 crit_enter(); 888 lwkt_gettoken(&vm_token); 889 for (idx = start; idx < end; idx++) { 890 p = vm_page_lookup(object, idx); 891 if (p == NULL) 892 continue; 893 vm_page_protect(p, VM_PROT_READ); 894 } 895 lwkt_reltoken(&vm_token); 896 crit_exit(); 897 } 898 899 /* 900 * Removes all physical pages in the specified object range from all 901 * physical maps. 902 * 903 * The object must *not* be locked. 904 */ 905 906 static int vm_object_pmap_remove_callback(vm_page_t p, void *data); 907 908 void 909 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 910 { 911 struct rb_vm_page_scan_info info; 912 913 if (object == NULL) 914 return; 915 info.start_pindex = start; 916 info.end_pindex = end - 1; 917 918 crit_enter(); 919 lwkt_gettoken(&vm_token); 920 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 921 vm_object_pmap_remove_callback, &info); 922 if (start == 0 && end == object->size) 923 vm_object_clear_flag(object, OBJ_WRITEABLE); 924 lwkt_reltoken(&vm_token); 925 crit_exit(); 926 } 927 928 /* 929 * The caller must hold vm_token. 930 */ 931 static int 932 vm_object_pmap_remove_callback(vm_page_t p, void *data __unused) 933 { 934 vm_page_protect(p, VM_PROT_NONE); 935 return(0); 936 } 937 938 /* 939 * Implements the madvise function at the object/page level. 940 * 941 * MADV_WILLNEED (any object) 942 * 943 * Activate the specified pages if they are resident. 944 * 945 * MADV_DONTNEED (any object) 946 * 947 * Deactivate the specified pages if they are resident. 948 * 949 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only) 950 * 951 * Deactivate and clean the specified pages if they are 952 * resident. This permits the process to reuse the pages 953 * without faulting or the kernel to reclaim the pages 954 * without I/O. 955 * 956 * No requirements. 957 */ 958 void 959 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise) 960 { 961 vm_pindex_t end, tpindex; 962 vm_object_t tobject; 963 vm_page_t m; 964 965 if (object == NULL) 966 return; 967 968 end = pindex + count; 969 970 lwkt_gettoken(&vm_token); 971 972 /* 973 * Locate and adjust resident pages 974 */ 975 for (; pindex < end; pindex += 1) { 976 relookup: 977 tobject = object; 978 tpindex = pindex; 979 shadowlookup: 980 /* 981 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 982 * and those pages must be OBJ_ONEMAPPING. 983 */ 984 if (advise == MADV_FREE) { 985 if ((tobject->type != OBJT_DEFAULT && 986 tobject->type != OBJT_SWAP) || 987 (tobject->flags & OBJ_ONEMAPPING) == 0) { 988 continue; 989 } 990 } 991 992 /* 993 * spl protection is required to avoid a race between the 994 * lookup, an interrupt unbusy/free, and our busy check. 995 */ 996 997 crit_enter(); 998 m = vm_page_lookup(tobject, tpindex); 999 1000 if (m == NULL) { 1001 /* 1002 * There may be swap even if there is no backing page 1003 */ 1004 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1005 swap_pager_freespace(tobject, tpindex, 1); 1006 1007 /* 1008 * next object 1009 */ 1010 crit_exit(); 1011 if (tobject->backing_object == NULL) 1012 continue; 1013 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1014 tobject = tobject->backing_object; 1015 goto shadowlookup; 1016 } 1017 1018 /* 1019 * If the page is busy or not in a normal active state, 1020 * we skip it. If the page is not managed there are no 1021 * page queues to mess with. Things can break if we mess 1022 * with pages in any of the below states. 1023 */ 1024 if ( 1025 m->hold_count || 1026 m->wire_count || 1027 (m->flags & PG_UNMANAGED) || 1028 m->valid != VM_PAGE_BITS_ALL 1029 ) { 1030 crit_exit(); 1031 continue; 1032 } 1033 1034 if (vm_page_sleep_busy(m, TRUE, "madvpo")) { 1035 crit_exit(); 1036 goto relookup; 1037 } 1038 vm_page_busy(m); 1039 crit_exit(); 1040 1041 /* 1042 * Theoretically once a page is known not to be busy, an 1043 * interrupt cannot come along and rip it out from under us. 1044 */ 1045 1046 if (advise == MADV_WILLNEED) { 1047 vm_page_activate(m); 1048 } else if (advise == MADV_DONTNEED) { 1049 vm_page_dontneed(m); 1050 } else if (advise == MADV_FREE) { 1051 /* 1052 * Mark the page clean. This will allow the page 1053 * to be freed up by the system. However, such pages 1054 * are often reused quickly by malloc()/free() 1055 * so we do not do anything that would cause 1056 * a page fault if we can help it. 1057 * 1058 * Specifically, we do not try to actually free 1059 * the page now nor do we try to put it in the 1060 * cache (which would cause a page fault on reuse). 1061 * 1062 * But we do make the page is freeable as we 1063 * can without actually taking the step of unmapping 1064 * it. 1065 */ 1066 pmap_clear_modify(m); 1067 m->dirty = 0; 1068 m->act_count = 0; 1069 vm_page_dontneed(m); 1070 if (tobject->type == OBJT_SWAP) 1071 swap_pager_freespace(tobject, tpindex, 1); 1072 } 1073 vm_page_wakeup(m); 1074 } 1075 lwkt_reltoken(&vm_token); 1076 } 1077 1078 /* 1079 * Create a new object which is backed by the specified existing object 1080 * range. The source object reference is deallocated. 1081 * 1082 * The new object and offset into that object are returned in the source 1083 * parameters. 1084 * 1085 * No other requirements. 1086 */ 1087 void 1088 vm_object_shadow(vm_object_t *object, vm_ooffset_t *offset, vm_size_t length) 1089 { 1090 vm_object_t source; 1091 vm_object_t result; 1092 1093 source = *object; 1094 1095 /* 1096 * Don't create the new object if the old object isn't shared. 1097 */ 1098 lwkt_gettoken(&vm_token); 1099 1100 if (source != NULL && 1101 source->ref_count == 1 && 1102 source->handle == NULL && 1103 (source->type == OBJT_DEFAULT || 1104 source->type == OBJT_SWAP)) { 1105 lwkt_reltoken(&vm_token); 1106 return; 1107 } 1108 1109 /* 1110 * Allocate a new object with the given length 1111 */ 1112 1113 if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) 1114 panic("vm_object_shadow: no object for shadowing"); 1115 1116 /* 1117 * The new object shadows the source object, adding a reference to it. 1118 * Our caller changes his reference to point to the new object, 1119 * removing a reference to the source object. Net result: no change 1120 * of reference count. 1121 * 1122 * Try to optimize the result object's page color when shadowing 1123 * in order to maintain page coloring consistency in the combined 1124 * shadowed object. 1125 */ 1126 result->backing_object = source; 1127 if (source) { 1128 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); 1129 source->shadow_count++; 1130 source->generation++; 1131 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK; 1132 } 1133 1134 /* 1135 * Store the offset into the source object, and fix up the offset into 1136 * the new object. 1137 */ 1138 result->backing_object_offset = *offset; 1139 lwkt_reltoken(&vm_token); 1140 1141 /* 1142 * Return the new things 1143 */ 1144 *offset = 0; 1145 *object = result; 1146 } 1147 1148 #define OBSC_TEST_ALL_SHADOWED 0x0001 1149 #define OBSC_COLLAPSE_NOWAIT 0x0002 1150 #define OBSC_COLLAPSE_WAIT 0x0004 1151 1152 static int vm_object_backing_scan_callback(vm_page_t p, void *data); 1153 1154 /* 1155 * The caller must hold vm_token. 1156 */ 1157 static __inline int 1158 vm_object_backing_scan(vm_object_t object, int op) 1159 { 1160 struct rb_vm_page_scan_info info; 1161 vm_object_t backing_object; 1162 1163 crit_enter(); 1164 1165 backing_object = object->backing_object; 1166 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1167 1168 /* 1169 * Initial conditions 1170 */ 1171 1172 if (op & OBSC_TEST_ALL_SHADOWED) { 1173 /* 1174 * We do not want to have to test for the existence of 1175 * swap pages in the backing object. XXX but with the 1176 * new swapper this would be pretty easy to do. 1177 * 1178 * XXX what about anonymous MAP_SHARED memory that hasn't 1179 * been ZFOD faulted yet? If we do not test for this, the 1180 * shadow test may succeed! XXX 1181 */ 1182 if (backing_object->type != OBJT_DEFAULT) { 1183 crit_exit(); 1184 return(0); 1185 } 1186 } 1187 if (op & OBSC_COLLAPSE_WAIT) { 1188 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 1189 vm_object_set_flag(backing_object, OBJ_DEAD); 1190 } 1191 1192 /* 1193 * Our scan. We have to retry if a negative error code is returned, 1194 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that 1195 * the scan had to be stopped because the parent does not completely 1196 * shadow the child. 1197 */ 1198 info.object = object; 1199 info.backing_object = backing_object; 1200 info.limit = op; 1201 do { 1202 info.error = 1; 1203 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL, 1204 vm_object_backing_scan_callback, 1205 &info); 1206 } while (info.error < 0); 1207 crit_exit(); 1208 return(info.error); 1209 } 1210 1211 /* 1212 * The caller must hold vm_token. 1213 */ 1214 static int 1215 vm_object_backing_scan_callback(vm_page_t p, void *data) 1216 { 1217 struct rb_vm_page_scan_info *info = data; 1218 vm_object_t backing_object; 1219 vm_object_t object; 1220 vm_pindex_t new_pindex; 1221 vm_pindex_t backing_offset_index; 1222 int op; 1223 1224 new_pindex = p->pindex - info->backing_offset_index; 1225 op = info->limit; 1226 object = info->object; 1227 backing_object = info->backing_object; 1228 backing_offset_index = info->backing_offset_index; 1229 1230 if (op & OBSC_TEST_ALL_SHADOWED) { 1231 vm_page_t pp; 1232 1233 /* 1234 * Ignore pages outside the parent object's range 1235 * and outside the parent object's mapping of the 1236 * backing object. 1237 * 1238 * note that we do not busy the backing object's 1239 * page. 1240 */ 1241 if ( 1242 p->pindex < backing_offset_index || 1243 new_pindex >= object->size 1244 ) { 1245 return(0); 1246 } 1247 1248 /* 1249 * See if the parent has the page or if the parent's 1250 * object pager has the page. If the parent has the 1251 * page but the page is not valid, the parent's 1252 * object pager must have the page. 1253 * 1254 * If this fails, the parent does not completely shadow 1255 * the object and we might as well give up now. 1256 */ 1257 1258 pp = vm_page_lookup(object, new_pindex); 1259 if ((pp == NULL || pp->valid == 0) && 1260 !vm_pager_has_page(object, new_pindex) 1261 ) { 1262 info->error = 0; /* problemo */ 1263 return(-1); /* stop the scan */ 1264 } 1265 } 1266 1267 /* 1268 * Check for busy page 1269 */ 1270 1271 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1272 vm_page_t pp; 1273 1274 if (op & OBSC_COLLAPSE_NOWAIT) { 1275 if ( 1276 (p->flags & PG_BUSY) || 1277 !p->valid || 1278 p->hold_count || 1279 p->wire_count || 1280 p->busy 1281 ) { 1282 return(0); 1283 } 1284 } else if (op & OBSC_COLLAPSE_WAIT) { 1285 if (vm_page_sleep_busy(p, TRUE, "vmocol")) { 1286 /* 1287 * If we slept, anything could have 1288 * happened. Ask that the scan be restarted. 1289 * 1290 * Since the object is marked dead, the 1291 * backing offset should not have changed. 1292 */ 1293 info->error = -1; 1294 return(-1); 1295 } 1296 } 1297 1298 /* 1299 * Busy the page 1300 */ 1301 vm_page_busy(p); 1302 1303 KASSERT( 1304 p->object == backing_object, 1305 ("vm_object_qcollapse(): object mismatch") 1306 ); 1307 1308 /* 1309 * Destroy any associated swap 1310 */ 1311 if (backing_object->type == OBJT_SWAP) 1312 swap_pager_freespace(backing_object, p->pindex, 1); 1313 1314 if ( 1315 p->pindex < backing_offset_index || 1316 new_pindex >= object->size 1317 ) { 1318 /* 1319 * Page is out of the parent object's range, we 1320 * can simply destroy it. 1321 */ 1322 vm_page_protect(p, VM_PROT_NONE); 1323 vm_page_free(p); 1324 return(0); 1325 } 1326 1327 pp = vm_page_lookup(object, new_pindex); 1328 if (pp != NULL || vm_pager_has_page(object, new_pindex)) { 1329 /* 1330 * page already exists in parent OR swap exists 1331 * for this location in the parent. Destroy 1332 * the original page from the backing object. 1333 * 1334 * Leave the parent's page alone 1335 */ 1336 vm_page_protect(p, VM_PROT_NONE); 1337 vm_page_free(p); 1338 return(0); 1339 } 1340 1341 /* 1342 * Page does not exist in parent, rename the 1343 * page from the backing object to the main object. 1344 * 1345 * If the page was mapped to a process, it can remain 1346 * mapped through the rename. 1347 */ 1348 if ((p->queue - p->pc) == PQ_CACHE) 1349 vm_page_deactivate(p); 1350 1351 vm_page_rename(p, object, new_pindex); 1352 /* page automatically made dirty by rename */ 1353 } 1354 return(0); 1355 } 1356 1357 /* 1358 * This version of collapse allows the operation to occur earlier and 1359 * when paging_in_progress is true for an object... This is not a complete 1360 * operation, but should plug 99.9% of the rest of the leaks. 1361 * 1362 * The caller must hold vm_token and vmobj_token. 1363 * (only called from vm_object_collapse) 1364 */ 1365 static void 1366 vm_object_qcollapse(vm_object_t object) 1367 { 1368 vm_object_t backing_object = object->backing_object; 1369 1370 if (backing_object->ref_count != 1) 1371 return; 1372 1373 backing_object->ref_count += 2; 1374 1375 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 1376 1377 backing_object->ref_count -= 2; 1378 } 1379 1380 /* 1381 * Collapse an object with the object backing it. Pages in the backing 1382 * object are moved into the parent, and the backing object is deallocated. 1383 */ 1384 void 1385 vm_object_collapse(vm_object_t object) 1386 { 1387 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1388 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1389 1390 while (TRUE) { 1391 vm_object_t backing_object; 1392 1393 /* 1394 * Verify that the conditions are right for collapse: 1395 * 1396 * The object exists and the backing object exists. 1397 */ 1398 if (object == NULL) 1399 break; 1400 1401 if ((backing_object = object->backing_object) == NULL) 1402 break; 1403 1404 /* 1405 * we check the backing object first, because it is most likely 1406 * not collapsable. 1407 */ 1408 if (backing_object->handle != NULL || 1409 (backing_object->type != OBJT_DEFAULT && 1410 backing_object->type != OBJT_SWAP) || 1411 (backing_object->flags & OBJ_DEAD) || 1412 object->handle != NULL || 1413 (object->type != OBJT_DEFAULT && 1414 object->type != OBJT_SWAP) || 1415 (object->flags & OBJ_DEAD)) { 1416 break; 1417 } 1418 1419 if ( 1420 object->paging_in_progress != 0 || 1421 backing_object->paging_in_progress != 0 1422 ) { 1423 vm_object_qcollapse(object); 1424 break; 1425 } 1426 1427 /* 1428 * We know that we can either collapse the backing object (if 1429 * the parent is the only reference to it) or (perhaps) have 1430 * the parent bypass the object if the parent happens to shadow 1431 * all the resident pages in the entire backing object. 1432 * 1433 * This is ignoring pager-backed pages such as swap pages. 1434 * vm_object_backing_scan fails the shadowing test in this 1435 * case. 1436 */ 1437 1438 if (backing_object->ref_count == 1) { 1439 /* 1440 * If there is exactly one reference to the backing 1441 * object, we can collapse it into the parent. 1442 */ 1443 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); 1444 1445 /* 1446 * Move the pager from backing_object to object. 1447 */ 1448 1449 if (backing_object->type == OBJT_SWAP) { 1450 vm_object_pip_add(backing_object, 1); 1451 1452 /* 1453 * scrap the paging_offset junk and do a 1454 * discrete copy. This also removes major 1455 * assumptions about how the swap-pager 1456 * works from where it doesn't belong. The 1457 * new swapper is able to optimize the 1458 * destroy-source case. 1459 */ 1460 1461 vm_object_pip_add(object, 1); 1462 swap_pager_copy( 1463 backing_object, 1464 object, 1465 OFF_TO_IDX(object->backing_object_offset), TRUE); 1466 vm_object_pip_wakeup(object); 1467 1468 vm_object_pip_wakeup(backing_object); 1469 } 1470 /* 1471 * Object now shadows whatever backing_object did. 1472 * Note that the reference to 1473 * backing_object->backing_object moves from within 1474 * backing_object to within object. 1475 */ 1476 1477 LIST_REMOVE(object, shadow_list); 1478 object->backing_object->shadow_count--; 1479 object->backing_object->generation++; 1480 if (backing_object->backing_object) { 1481 LIST_REMOVE(backing_object, shadow_list); 1482 backing_object->backing_object->shadow_count--; 1483 backing_object->backing_object->generation++; 1484 } 1485 object->backing_object = backing_object->backing_object; 1486 if (object->backing_object) { 1487 LIST_INSERT_HEAD( 1488 &object->backing_object->shadow_head, 1489 object, 1490 shadow_list 1491 ); 1492 object->backing_object->shadow_count++; 1493 object->backing_object->generation++; 1494 } 1495 1496 object->backing_object_offset += 1497 backing_object->backing_object_offset; 1498 1499 /* 1500 * Discard backing_object. 1501 * 1502 * Since the backing object has no pages, no pager left, 1503 * and no object references within it, all that is 1504 * necessary is to dispose of it. 1505 */ 1506 1507 KASSERT(backing_object->ref_count == 1, 1508 ("backing_object %p was somehow " 1509 "re-referenced during collapse!", 1510 backing_object)); 1511 KASSERT(RB_EMPTY(&backing_object->rb_memq), 1512 ("backing_object %p somehow has left " 1513 "over pages during collapse!", 1514 backing_object)); 1515 1516 /* 1517 * Wait for hold count to hit zero 1518 */ 1519 vm_object_hold_wait(backing_object); 1520 1521 /* (we are holding vmobj_token) */ 1522 TAILQ_REMOVE(&vm_object_list, backing_object, 1523 object_list); 1524 vm_object_count--; 1525 1526 zfree(obj_zone, backing_object); 1527 1528 object_collapses++; 1529 } else { 1530 vm_object_t new_backing_object; 1531 1532 /* 1533 * If we do not entirely shadow the backing object, 1534 * there is nothing we can do so we give up. 1535 */ 1536 1537 if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) { 1538 break; 1539 } 1540 1541 /* 1542 * Make the parent shadow the next object in the 1543 * chain. Deallocating backing_object will not remove 1544 * it, since its reference count is at least 2. 1545 */ 1546 1547 LIST_REMOVE(object, shadow_list); 1548 backing_object->shadow_count--; 1549 backing_object->generation++; 1550 1551 new_backing_object = backing_object->backing_object; 1552 if ((object->backing_object = new_backing_object) != NULL) { 1553 vm_object_reference(new_backing_object); 1554 LIST_INSERT_HEAD( 1555 &new_backing_object->shadow_head, 1556 object, 1557 shadow_list 1558 ); 1559 new_backing_object->shadow_count++; 1560 new_backing_object->generation++; 1561 object->backing_object_offset += 1562 backing_object->backing_object_offset; 1563 } 1564 1565 /* 1566 * Drop the reference count on backing_object. Since 1567 * its ref_count was at least 2, it will not vanish; 1568 * so we don't need to call vm_object_deallocate, but 1569 * we do anyway. 1570 */ 1571 vm_object_deallocate_locked(backing_object); 1572 object_bypasses++; 1573 } 1574 1575 /* 1576 * Try again with this object's new backing object. 1577 */ 1578 } 1579 } 1580 1581 /* 1582 * Removes all physical pages in the specified object range from the 1583 * object's list of pages. 1584 * 1585 * No requirements. 1586 */ 1587 static int vm_object_page_remove_callback(vm_page_t p, void *data); 1588 1589 void 1590 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1591 boolean_t clean_only) 1592 { 1593 struct rb_vm_page_scan_info info; 1594 int all; 1595 1596 /* 1597 * Degenerate cases and assertions 1598 */ 1599 lwkt_gettoken(&vm_token); 1600 if (object == NULL || 1601 (object->resident_page_count == 0 && object->swblock_count == 0)) { 1602 lwkt_reltoken(&vm_token); 1603 return; 1604 } 1605 KASSERT(object->type != OBJT_PHYS, 1606 ("attempt to remove pages from a physical object")); 1607 1608 /* 1609 * Indicate that paging is occuring on the object 1610 */ 1611 crit_enter(); 1612 vm_object_pip_add(object, 1); 1613 1614 /* 1615 * Figure out the actual removal range and whether we are removing 1616 * the entire contents of the object or not. If removing the entire 1617 * contents, be sure to get all pages, even those that might be 1618 * beyond the end of the object. 1619 */ 1620 info.start_pindex = start; 1621 if (end == 0) 1622 info.end_pindex = (vm_pindex_t)-1; 1623 else 1624 info.end_pindex = end - 1; 1625 info.limit = clean_only; 1626 all = (start == 0 && info.end_pindex >= object->size - 1); 1627 1628 /* 1629 * Loop until we are sure we have gotten them all. 1630 */ 1631 do { 1632 info.error = 0; 1633 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1634 vm_object_page_remove_callback, &info); 1635 } while (info.error); 1636 1637 /* 1638 * Remove any related swap if throwing away pages, or for 1639 * non-swap objects (the swap is a clean copy in that case). 1640 */ 1641 if (object->type != OBJT_SWAP || clean_only == FALSE) { 1642 if (all) 1643 swap_pager_freespace_all(object); 1644 else 1645 swap_pager_freespace(object, info.start_pindex, 1646 info.end_pindex - info.start_pindex + 1); 1647 } 1648 1649 /* 1650 * Cleanup 1651 */ 1652 vm_object_pip_wakeup(object); 1653 crit_exit(); 1654 lwkt_reltoken(&vm_token); 1655 } 1656 1657 /* 1658 * The caller must hold vm_token. 1659 */ 1660 static int 1661 vm_object_page_remove_callback(vm_page_t p, void *data) 1662 { 1663 struct rb_vm_page_scan_info *info = data; 1664 1665 /* 1666 * Wired pages cannot be destroyed, but they can be invalidated 1667 * and we do so if clean_only (limit) is not set. 1668 * 1669 * WARNING! The page may be wired due to being part of a buffer 1670 * cache buffer, and the buffer might be marked B_CACHE. 1671 * This is fine as part of a truncation but VFSs must be 1672 * sure to fix the buffer up when re-extending the file. 1673 */ 1674 if (p->wire_count != 0) { 1675 vm_page_protect(p, VM_PROT_NONE); 1676 if (info->limit == 0) 1677 p->valid = 0; 1678 return(0); 1679 } 1680 1681 /* 1682 * The busy flags are only cleared at 1683 * interrupt -- minimize the spl transitions 1684 */ 1685 1686 if (vm_page_sleep_busy(p, TRUE, "vmopar")) { 1687 info->error = 1; 1688 return(0); 1689 } 1690 1691 /* 1692 * limit is our clean_only flag. If set and the page is dirty, do 1693 * not free it. If set and the page is being held by someone, do 1694 * not free it. 1695 */ 1696 if (info->limit && p->valid) { 1697 vm_page_test_dirty(p); 1698 if (p->valid & p->dirty) 1699 return(0); 1700 if (p->hold_count) 1701 return(0); 1702 } 1703 1704 /* 1705 * Destroy the page 1706 */ 1707 vm_page_busy(p); 1708 vm_page_protect(p, VM_PROT_NONE); 1709 vm_page_free(p); 1710 return(0); 1711 } 1712 1713 /* 1714 * Coalesces two objects backing up adjoining regions of memory into a 1715 * single object. 1716 * 1717 * returns TRUE if objects were combined. 1718 * 1719 * NOTE: Only works at the moment if the second object is NULL - 1720 * if it's not, which object do we lock first? 1721 * 1722 * Parameters: 1723 * prev_object First object to coalesce 1724 * prev_offset Offset into prev_object 1725 * next_object Second object into coalesce 1726 * next_offset Offset into next_object 1727 * 1728 * prev_size Size of reference to prev_object 1729 * next_size Size of reference to next_object 1730 * 1731 * The object must not be locked. 1732 * The caller must hold vm_token and vmobj_token. 1733 */ 1734 boolean_t 1735 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 1736 vm_size_t prev_size, vm_size_t next_size) 1737 { 1738 vm_pindex_t next_pindex; 1739 1740 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1741 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1742 1743 if (prev_object == NULL) { 1744 return (TRUE); 1745 } 1746 1747 if (prev_object->type != OBJT_DEFAULT && 1748 prev_object->type != OBJT_SWAP) { 1749 return (FALSE); 1750 } 1751 1752 /* 1753 * Try to collapse the object first 1754 */ 1755 vm_object_collapse(prev_object); 1756 1757 /* 1758 * Can't coalesce if: . more than one reference . paged out . shadows 1759 * another object . has a copy elsewhere (any of which mean that the 1760 * pages not mapped to prev_entry may be in use anyway) 1761 */ 1762 1763 if (prev_object->backing_object != NULL) { 1764 return (FALSE); 1765 } 1766 1767 prev_size >>= PAGE_SHIFT; 1768 next_size >>= PAGE_SHIFT; 1769 next_pindex = prev_pindex + prev_size; 1770 1771 if ((prev_object->ref_count > 1) && 1772 (prev_object->size != next_pindex)) { 1773 return (FALSE); 1774 } 1775 1776 /* 1777 * Remove any pages that may still be in the object from a previous 1778 * deallocation. 1779 */ 1780 if (next_pindex < prev_object->size) { 1781 vm_object_page_remove(prev_object, 1782 next_pindex, 1783 next_pindex + next_size, FALSE); 1784 if (prev_object->type == OBJT_SWAP) 1785 swap_pager_freespace(prev_object, 1786 next_pindex, next_size); 1787 } 1788 1789 /* 1790 * Extend the object if necessary. 1791 */ 1792 if (next_pindex + next_size > prev_object->size) 1793 prev_object->size = next_pindex + next_size; 1794 1795 return (TRUE); 1796 } 1797 1798 /* 1799 * Make the object writable and flag is being possibly dirty. 1800 * 1801 * No requirements. 1802 */ 1803 void 1804 vm_object_set_writeable_dirty(vm_object_t object) 1805 { 1806 struct vnode *vp; 1807 1808 lwkt_gettoken(&vm_token); 1809 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1810 if (object->type == OBJT_VNODE && 1811 (vp = (struct vnode *)object->handle) != NULL) { 1812 if ((vp->v_flag & VOBJDIRTY) == 0) { 1813 vsetflags(vp, VOBJDIRTY); 1814 } 1815 } 1816 lwkt_reltoken(&vm_token); 1817 } 1818 1819 static void 1820 vm_object_lock_init(vm_object_t obj) 1821 { 1822 #if defined(DEBUG_LOCKS) 1823 int i; 1824 1825 obj->debug_hold_bitmap = 0; 1826 obj->debug_hold_ovfl = 0; 1827 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 1828 obj->debug_hold_thrs[i] = NULL; 1829 } 1830 #endif 1831 } 1832 1833 void 1834 vm_object_lock(vm_object_t obj) 1835 { 1836 lwkt_getpooltoken(obj); 1837 } 1838 1839 void 1840 vm_object_unlock(vm_object_t obj) 1841 { 1842 lwkt_relpooltoken(obj); 1843 } 1844 1845 void 1846 vm_object_hold(vm_object_t obj) 1847 { 1848 vm_object_lock(obj); 1849 1850 refcount_acquire(&obj->hold_count); 1851 1852 #if defined(DEBUG_LOCKS) 1853 int i; 1854 1855 i = ffs(~obj->debug_hold_bitmap) - 1; 1856 if (i == -1) { 1857 kprintf("vm_object hold count > VMOBJ_DEBUG_ARRAY_SIZE"); 1858 obj->debug_hold_ovfl = 1; 1859 } 1860 1861 obj->debug_hold_bitmap |= (1 << i); 1862 obj->debug_hold_thrs[i] = curthread; 1863 #endif 1864 } 1865 1866 void 1867 vm_object_drop(vm_object_t obj) 1868 { 1869 int rc; 1870 1871 #if defined(DEBUG_LOCKS) 1872 int found = 0; 1873 int i; 1874 1875 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 1876 if ((obj->debug_hold_bitmap & (1 << i)) && 1877 (obj->debug_hold_thrs[i] == curthread)) { 1878 obj->debug_hold_bitmap &= ~(1 << i); 1879 obj->debug_hold_thrs[i] = NULL; 1880 found = 1; 1881 break; 1882 } 1883 } 1884 1885 if (found == 0 && obj->debug_hold_ovfl == 0) 1886 panic("vm_object: attempt to drop hold on non-self-held obj"); 1887 #endif 1888 1889 rc = refcount_release(&obj->hold_count); 1890 vm_object_unlock(obj); 1891 1892 if (rc) 1893 vm_object_hold_wake(obj); 1894 } 1895 1896 static void 1897 vm_object_hold_wake(vm_object_t obj) 1898 { 1899 wakeup(obj); 1900 } 1901 1902 static void 1903 vm_object_hold_wait(vm_object_t obj) 1904 { 1905 vm_object_lock(obj); 1906 1907 #if defined(DEBUG_LOCKS) 1908 int i; 1909 1910 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) { 1911 if ((obj->debug_hold_bitmap & (1 << i)) && 1912 (obj->debug_hold_thrs[i] == curthread)) 1913 panic("vm_object: self-hold in terminate or collapse"); 1914 } 1915 #endif 1916 1917 while (obj->hold_count) 1918 tsleep(obj, 0, "vmobjhld", 0); 1919 1920 vm_object_unlock(obj); 1921 } 1922 1923 #include "opt_ddb.h" 1924 #ifdef DDB 1925 #include <sys/kernel.h> 1926 1927 #include <sys/cons.h> 1928 1929 #include <ddb/ddb.h> 1930 1931 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 1932 vm_map_entry_t entry); 1933 static int vm_object_in_map (vm_object_t object); 1934 1935 /* 1936 * The caller must hold vm_token. 1937 */ 1938 static int 1939 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 1940 { 1941 vm_map_t tmpm; 1942 vm_map_entry_t tmpe; 1943 vm_object_t obj; 1944 int entcount; 1945 1946 if (map == 0) 1947 return 0; 1948 if (entry == 0) { 1949 tmpe = map->header.next; 1950 entcount = map->nentries; 1951 while (entcount-- && (tmpe != &map->header)) { 1952 if( _vm_object_in_map(map, object, tmpe)) { 1953 return 1; 1954 } 1955 tmpe = tmpe->next; 1956 } 1957 return (0); 1958 } 1959 switch(entry->maptype) { 1960 case VM_MAPTYPE_SUBMAP: 1961 tmpm = entry->object.sub_map; 1962 tmpe = tmpm->header.next; 1963 entcount = tmpm->nentries; 1964 while (entcount-- && tmpe != &tmpm->header) { 1965 if( _vm_object_in_map(tmpm, object, tmpe)) { 1966 return 1; 1967 } 1968 tmpe = tmpe->next; 1969 } 1970 break; 1971 case VM_MAPTYPE_NORMAL: 1972 case VM_MAPTYPE_VPAGETABLE: 1973 obj = entry->object.vm_object; 1974 while (obj) { 1975 if (obj == object) 1976 return 1; 1977 obj = obj->backing_object; 1978 } 1979 break; 1980 default: 1981 break; 1982 } 1983 return 0; 1984 } 1985 1986 static int vm_object_in_map_callback(struct proc *p, void *data); 1987 1988 struct vm_object_in_map_info { 1989 vm_object_t object; 1990 int rv; 1991 }; 1992 1993 /* 1994 * Debugging only 1995 */ 1996 static int 1997 vm_object_in_map(vm_object_t object) 1998 { 1999 struct vm_object_in_map_info info; 2000 2001 info.rv = 0; 2002 info.object = object; 2003 2004 allproc_scan(vm_object_in_map_callback, &info); 2005 if (info.rv) 2006 return 1; 2007 if( _vm_object_in_map(&kernel_map, object, 0)) 2008 return 1; 2009 if( _vm_object_in_map(&pager_map, object, 0)) 2010 return 1; 2011 if( _vm_object_in_map(&buffer_map, object, 0)) 2012 return 1; 2013 return 0; 2014 } 2015 2016 /* 2017 * Debugging only 2018 */ 2019 static int 2020 vm_object_in_map_callback(struct proc *p, void *data) 2021 { 2022 struct vm_object_in_map_info *info = data; 2023 2024 if (p->p_vmspace) { 2025 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) { 2026 info->rv = 1; 2027 return -1; 2028 } 2029 } 2030 return (0); 2031 } 2032 2033 DB_SHOW_COMMAND(vmochk, vm_object_check) 2034 { 2035 vm_object_t object; 2036 2037 /* 2038 * make sure that internal objs are in a map somewhere 2039 * and none have zero ref counts. 2040 */ 2041 for (object = TAILQ_FIRST(&vm_object_list); 2042 object != NULL; 2043 object = TAILQ_NEXT(object, object_list)) { 2044 if (object->type == OBJT_MARKER) 2045 continue; 2046 if (object->handle == NULL && 2047 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 2048 if (object->ref_count == 0) { 2049 db_printf("vmochk: internal obj has zero ref count: %ld\n", 2050 (long)object->size); 2051 } 2052 if (!vm_object_in_map(object)) { 2053 db_printf( 2054 "vmochk: internal obj is not in a map: " 2055 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 2056 object->ref_count, (u_long)object->size, 2057 (u_long)object->size, 2058 (void *)object->backing_object); 2059 } 2060 } 2061 } 2062 } 2063 2064 /* 2065 * Debugging only 2066 */ 2067 DB_SHOW_COMMAND(object, vm_object_print_static) 2068 { 2069 /* XXX convert args. */ 2070 vm_object_t object = (vm_object_t)addr; 2071 boolean_t full = have_addr; 2072 2073 vm_page_t p; 2074 2075 /* XXX count is an (unused) arg. Avoid shadowing it. */ 2076 #define count was_count 2077 2078 int count; 2079 2080 if (object == NULL) 2081 return; 2082 2083 db_iprintf( 2084 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 2085 object, (int)object->type, (u_long)object->size, 2086 object->resident_page_count, object->ref_count, object->flags); 2087 /* 2088 * XXX no %qd in kernel. Truncate object->backing_object_offset. 2089 */ 2090 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 2091 object->shadow_count, 2092 object->backing_object ? object->backing_object->ref_count : 0, 2093 object->backing_object, (long)object->backing_object_offset); 2094 2095 if (!full) 2096 return; 2097 2098 db_indent += 2; 2099 count = 0; 2100 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) { 2101 if (count == 0) 2102 db_iprintf("memory:="); 2103 else if (count == 6) { 2104 db_printf("\n"); 2105 db_iprintf(" ..."); 2106 count = 0; 2107 } else 2108 db_printf(","); 2109 count++; 2110 2111 db_printf("(off=0x%lx,page=0x%lx)", 2112 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 2113 } 2114 if (count != 0) 2115 db_printf("\n"); 2116 db_indent -= 2; 2117 } 2118 2119 /* XXX. */ 2120 #undef count 2121 2122 /* 2123 * XXX need this non-static entry for calling from vm_map_print. 2124 * 2125 * Debugging only 2126 */ 2127 void 2128 vm_object_print(/* db_expr_t */ long addr, 2129 boolean_t have_addr, 2130 /* db_expr_t */ long count, 2131 char *modif) 2132 { 2133 vm_object_print_static(addr, have_addr, count, modif); 2134 } 2135 2136 /* 2137 * Debugging only 2138 */ 2139 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 2140 { 2141 vm_object_t object; 2142 int nl = 0; 2143 int c; 2144 for (object = TAILQ_FIRST(&vm_object_list); 2145 object != NULL; 2146 object = TAILQ_NEXT(object, object_list)) { 2147 vm_pindex_t idx, fidx; 2148 vm_pindex_t osize; 2149 vm_paddr_t pa = -1, padiff; 2150 int rcount; 2151 vm_page_t m; 2152 2153 if (object->type == OBJT_MARKER) 2154 continue; 2155 db_printf("new object: %p\n", (void *)object); 2156 if ( nl > 18) { 2157 c = cngetc(); 2158 if (c != ' ') 2159 return; 2160 nl = 0; 2161 } 2162 nl++; 2163 rcount = 0; 2164 fidx = 0; 2165 osize = object->size; 2166 if (osize > 128) 2167 osize = 128; 2168 for (idx = 0; idx < osize; idx++) { 2169 m = vm_page_lookup(object, idx); 2170 if (m == NULL) { 2171 if (rcount) { 2172 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2173 (long)fidx, rcount, (long)pa); 2174 if ( nl > 18) { 2175 c = cngetc(); 2176 if (c != ' ') 2177 return; 2178 nl = 0; 2179 } 2180 nl++; 2181 rcount = 0; 2182 } 2183 continue; 2184 } 2185 2186 2187 if (rcount && 2188 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 2189 ++rcount; 2190 continue; 2191 } 2192 if (rcount) { 2193 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 2194 padiff >>= PAGE_SHIFT; 2195 padiff &= PQ_L2_MASK; 2196 if (padiff == 0) { 2197 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 2198 ++rcount; 2199 continue; 2200 } 2201 db_printf(" index(%ld)run(%d)pa(0x%lx)", 2202 (long)fidx, rcount, (long)pa); 2203 db_printf("pd(%ld)\n", (long)padiff); 2204 if ( nl > 18) { 2205 c = cngetc(); 2206 if (c != ' ') 2207 return; 2208 nl = 0; 2209 } 2210 nl++; 2211 } 2212 fidx = idx; 2213 pa = VM_PAGE_TO_PHYS(m); 2214 rcount = 1; 2215 } 2216 if (rcount) { 2217 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2218 (long)fidx, rcount, (long)pa); 2219 if ( nl > 18) { 2220 c = cngetc(); 2221 if (c != ' ') 2222 return; 2223 nl = 0; 2224 } 2225 nl++; 2226 } 2227 } 2228 } 2229 #endif /* DDB */ 2230