1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 45 * 46 * Permission to use, copy, modify and distribute this software and 47 * its documentation is hereby granted, provided that both the copyright 48 * notice and this permission notice appear in all copies of the 49 * software, derivative works or modified versions, and any portions 50 * thereof, and that both notices appear in supporting documentation. 51 * 52 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 53 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 54 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 55 * 56 * Carnegie Mellon requests users of this software to return to 57 * 58 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 59 * School of Computer Science 60 * Carnegie Mellon University 61 * Pittsburgh PA 15213-3890 62 * 63 * any improvements or extensions that they make and grant Carnegie the 64 * rights to redistribute these changes. 65 * 66 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ 67 * $DragonFly: src/sys/vm/vm_object.c,v 1.33 2008/05/09 07:24:48 dillon Exp $ 68 */ 69 70 /* 71 * Virtual memory object module. 72 */ 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/proc.h> /* for curproc, pageproc */ 77 #include <sys/vnode.h> 78 #include <sys/vmmeter.h> 79 #include <sys/mman.h> 80 #include <sys/mount.h> 81 #include <sys/kernel.h> 82 #include <sys/sysctl.h> 83 84 #include <vm/vm.h> 85 #include <vm/vm_param.h> 86 #include <vm/pmap.h> 87 #include <vm/vm_map.h> 88 #include <vm/vm_object.h> 89 #include <vm/vm_page.h> 90 #include <vm/vm_pageout.h> 91 #include <vm/vm_pager.h> 92 #include <vm/swap_pager.h> 93 #include <vm/vm_kern.h> 94 #include <vm/vm_extern.h> 95 #include <vm/vm_zone.h> 96 97 #define EASY_SCAN_FACTOR 8 98 99 static void vm_object_qcollapse(vm_object_t object); 100 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, 101 int pagerflags); 102 103 /* 104 * Virtual memory objects maintain the actual data 105 * associated with allocated virtual memory. A given 106 * page of memory exists within exactly one object. 107 * 108 * An object is only deallocated when all "references" 109 * are given up. Only one "reference" to a given 110 * region of an object should be writeable. 111 * 112 * Associated with each object is a list of all resident 113 * memory pages belonging to that object; this list is 114 * maintained by the "vm_page" module, and locked by the object's 115 * lock. 116 * 117 * Each object also records a "pager" routine which is 118 * used to retrieve (and store) pages to the proper backing 119 * storage. In addition, objects may be backed by other 120 * objects from which they were virtual-copied. 121 * 122 * The only items within the object structure which are 123 * modified after time of creation are: 124 * reference count locked by object's lock 125 * pager routine locked by object's lock 126 * 127 */ 128 129 struct object_q vm_object_list; /* locked by vmobj_token */ 130 struct vm_object kernel_object; 131 132 static long vm_object_count; /* locked by vmobj_token */ 133 extern int vm_pageout_page_count; 134 135 static long object_collapses; 136 static long object_bypasses; 137 static int next_index; 138 static vm_zone_t obj_zone; 139 static struct vm_zone obj_zone_store; 140 static int object_hash_rand; 141 #define VM_OBJECTS_INIT 256 142 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 143 144 /* 145 * Initialize a freshly allocated object 146 * 147 * Used only by vm_object_allocate() and zinitna(). 148 * 149 * No requirements. 150 */ 151 void 152 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object) 153 { 154 int incr; 155 156 RB_INIT(&object->rb_memq); 157 LIST_INIT(&object->shadow_head); 158 159 object->type = type; 160 object->size = size; 161 object->ref_count = 1; 162 object->flags = 0; 163 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 164 vm_object_set_flag(object, OBJ_ONEMAPPING); 165 object->paging_in_progress = 0; 166 object->resident_page_count = 0; 167 object->agg_pv_list_count = 0; 168 object->shadow_count = 0; 169 object->pg_color = next_index; 170 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 171 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 172 else 173 incr = size; 174 next_index = (next_index + incr) & PQ_L2_MASK; 175 object->handle = NULL; 176 object->backing_object = NULL; 177 object->backing_object_offset = (vm_ooffset_t) 0; 178 /* 179 * Try to generate a number that will spread objects out in the 180 * hash table. We 'wipe' new objects across the hash in 128 page 181 * increments plus 1 more to offset it a little more by the time 182 * it wraps around. 183 */ 184 object->hash_rand = object_hash_rand - 129; 185 186 object->generation++; 187 object->swblock_count = 0; 188 RB_INIT(&object->swblock_root); 189 190 lwkt_gettoken(&vmobj_token); 191 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 192 vm_object_count++; 193 object_hash_rand = object->hash_rand; 194 lwkt_reltoken(&vmobj_token); 195 } 196 197 /* 198 * Initialize the VM objects module. 199 * 200 * Called from the low level boot code only. 201 */ 202 void 203 vm_object_init(void) 204 { 205 TAILQ_INIT(&vm_object_list); 206 207 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd), 208 &kernel_object); 209 210 obj_zone = &obj_zone_store; 211 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 212 vm_objects_init, VM_OBJECTS_INIT); 213 } 214 215 void 216 vm_object_init2(void) 217 { 218 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 219 } 220 221 /* 222 * Allocate and return a new object of the specified type and size. 223 * 224 * No requirements. 225 */ 226 vm_object_t 227 vm_object_allocate(objtype_t type, vm_pindex_t size) 228 { 229 vm_object_t result; 230 231 result = (vm_object_t) zalloc(obj_zone); 232 233 _vm_object_allocate(type, size, result); 234 235 return (result); 236 } 237 238 /* 239 * Add an additional reference to a vm_object. 240 * 241 * Object passed by caller must be stable or caller must already 242 * hold vmobj_token to avoid races. 243 */ 244 void 245 vm_object_reference(vm_object_t object) 246 { 247 if (object) { 248 lwkt_gettoken(&vmobj_token); 249 object->ref_count++; 250 if (object->type == OBJT_VNODE) { 251 vref(object->handle); 252 /* XXX what if the vnode is being destroyed? */ 253 } 254 lwkt_reltoken(&vmobj_token); 255 } 256 } 257 258 void 259 vm_object_reference_locked(vm_object_t object) 260 { 261 if (object) { 262 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 263 object->ref_count++; 264 if (object->type == OBJT_VNODE) { 265 vref(object->handle); 266 /* XXX what if the vnode is being destroyed? */ 267 } 268 } 269 } 270 271 /* 272 * Dereference an object and its underlying vnode. 273 * 274 * The caller must hold vmobj_token. 275 */ 276 static void 277 vm_object_vndeallocate(vm_object_t object) 278 { 279 struct vnode *vp = (struct vnode *) object->handle; 280 281 KASSERT(object->type == OBJT_VNODE, 282 ("vm_object_vndeallocate: not a vnode object")); 283 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 284 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 285 #ifdef INVARIANTS 286 if (object->ref_count == 0) { 287 vprint("vm_object_vndeallocate", vp); 288 panic("vm_object_vndeallocate: bad object reference count"); 289 } 290 #endif 291 292 object->ref_count--; 293 if (object->ref_count == 0) 294 vclrflags(vp, VTEXT); 295 vrele(vp); 296 } 297 298 /* 299 * Release a reference to the specified object, gained either through a 300 * vm_object_allocate or a vm_object_reference call. When all references 301 * are gone, storage associated with this object may be relinquished. 302 */ 303 void 304 vm_object_deallocate(vm_object_t object) 305 { 306 lwkt_gettoken(&vmobj_token); 307 vm_object_deallocate_locked(object); 308 lwkt_reltoken(&vmobj_token); 309 } 310 311 void 312 vm_object_deallocate_locked(vm_object_t object) 313 { 314 vm_object_t temp; 315 316 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 317 318 while (object != NULL) { 319 if (object->type == OBJT_VNODE) { 320 vm_object_vndeallocate(object); 321 break; 322 } 323 324 if (object->ref_count == 0) { 325 panic("vm_object_deallocate: object deallocated " 326 "too many times: %d", object->type); 327 } 328 if (object->ref_count > 2) { 329 object->ref_count--; 330 break; 331 } 332 333 /* 334 * We currently need the vm_token from this point on, and 335 * we must recheck ref_count after acquiring it. 336 */ 337 lwkt_gettoken(&vm_token); 338 339 if (object->ref_count > 2) { 340 object->ref_count--; 341 lwkt_reltoken(&vm_token); 342 break; 343 } 344 345 /* 346 * Here on ref_count of one or two, which are special cases for 347 * objects. 348 */ 349 if ((object->ref_count == 2) && (object->shadow_count == 0)) { 350 vm_object_set_flag(object, OBJ_ONEMAPPING); 351 object->ref_count--; 352 lwkt_reltoken(&vm_token); 353 break; 354 } 355 if ((object->ref_count == 2) && (object->shadow_count == 1)) { 356 object->ref_count--; 357 if ((object->handle == NULL) && 358 (object->type == OBJT_DEFAULT || 359 object->type == OBJT_SWAP)) { 360 vm_object_t robject; 361 362 robject = LIST_FIRST(&object->shadow_head); 363 KASSERT(robject != NULL, 364 ("vm_object_deallocate: ref_count: " 365 "%d, shadow_count: %d", 366 object->ref_count, 367 object->shadow_count)); 368 369 if ((robject->handle == NULL) && 370 (robject->type == OBJT_DEFAULT || 371 robject->type == OBJT_SWAP)) { 372 373 robject->ref_count++; 374 375 while ( 376 robject->paging_in_progress || 377 object->paging_in_progress 378 ) { 379 vm_object_pip_sleep(robject, "objde1"); 380 vm_object_pip_sleep(object, "objde2"); 381 } 382 383 if (robject->ref_count == 1) { 384 robject->ref_count--; 385 object = robject; 386 goto doterm; 387 } 388 389 object = robject; 390 vm_object_collapse(object); 391 lwkt_reltoken(&vm_token); 392 continue; 393 } 394 } 395 lwkt_reltoken(&vm_token); 396 break; 397 } 398 399 /* 400 * Normal dereferencing path 401 */ 402 object->ref_count--; 403 if (object->ref_count != 0) { 404 lwkt_reltoken(&vm_token); 405 break; 406 } 407 408 /* 409 * Termination path 410 */ 411 doterm: 412 temp = object->backing_object; 413 if (temp) { 414 LIST_REMOVE(object, shadow_list); 415 temp->shadow_count--; 416 temp->generation++; 417 object->backing_object = NULL; 418 } 419 lwkt_reltoken(&vm_token); 420 421 /* 422 * Don't double-terminate, we could be in a termination 423 * recursion due to the terminate having to sync data 424 * to disk. 425 */ 426 if ((object->flags & OBJ_DEAD) == 0) 427 vm_object_terminate(object); 428 object = temp; 429 } 430 } 431 432 /* 433 * Destroy the specified object, freeing up related resources. 434 * 435 * The object must have zero references. 436 * 437 * The caller must be holding vmobj_token and properly interlock with 438 * OBJ_DEAD. 439 */ 440 static int vm_object_terminate_callback(vm_page_t p, void *data); 441 442 void 443 vm_object_terminate(vm_object_t object) 444 { 445 /* 446 * Make sure no one uses us. Once we set OBJ_DEAD we should be 447 * able to safely block. 448 */ 449 KKASSERT((object->flags & OBJ_DEAD) == 0); 450 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 451 vm_object_set_flag(object, OBJ_DEAD); 452 453 /* 454 * Wait for the pageout daemon to be done with the object 455 */ 456 vm_object_pip_wait(object, "objtrm"); 457 458 KASSERT(!object->paging_in_progress, 459 ("vm_object_terminate: pageout in progress")); 460 461 /* 462 * Clean and free the pages, as appropriate. All references to the 463 * object are gone, so we don't need to lock it. 464 */ 465 if (object->type == OBJT_VNODE) { 466 struct vnode *vp; 467 468 /* 469 * Clean pages and flush buffers. 470 */ 471 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 472 473 vp = (struct vnode *) object->handle; 474 vinvalbuf(vp, V_SAVE, 0, 0); 475 } 476 477 /* 478 * Wait for any I/O to complete, after which there had better not 479 * be any references left on the object. 480 */ 481 vm_object_pip_wait(object, "objtrm"); 482 483 if (object->ref_count != 0) { 484 panic("vm_object_terminate: object with references, " 485 "ref_count=%d", object->ref_count); 486 } 487 488 /* 489 * Now free any remaining pages. For internal objects, this also 490 * removes them from paging queues. Don't free wired pages, just 491 * remove them from the object. 492 */ 493 lwkt_gettoken(&vm_token); 494 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 495 vm_object_terminate_callback, NULL); 496 lwkt_reltoken(&vm_token); 497 498 /* 499 * Let the pager know object is dead. 500 */ 501 vm_pager_deallocate(object); 502 503 /* 504 * Remove the object from the global object list. 505 * 506 * (we are holding vmobj_token) 507 */ 508 TAILQ_REMOVE(&vm_object_list, object, object_list); 509 vm_object_count--; 510 vm_object_dead_wakeup(object); 511 512 if (object->ref_count != 0) { 513 panic("vm_object_terminate2: object with references, " 514 "ref_count=%d", object->ref_count); 515 } 516 517 /* 518 * Free the space for the object. 519 */ 520 zfree(obj_zone, object); 521 } 522 523 /* 524 * The caller must hold vm_token. 525 */ 526 static int 527 vm_object_terminate_callback(vm_page_t p, void *data __unused) 528 { 529 if (p->busy || (p->flags & PG_BUSY)) 530 panic("vm_object_terminate: freeing busy page %p", p); 531 if (p->wire_count == 0) { 532 vm_page_busy(p); 533 vm_page_free(p); 534 mycpu->gd_cnt.v_pfree++; 535 } else { 536 if (p->queue != PQ_NONE) 537 kprintf("vm_object_terminate: Warning: Encountered wired page %p on queue %d\n", p, p->queue); 538 vm_page_busy(p); 539 vm_page_remove(p); 540 vm_page_wakeup(p); 541 } 542 return(0); 543 } 544 545 /* 546 * The object is dead but still has an object<->pager association. Sleep 547 * and return. The caller typically retests the association in a loop. 548 * 549 * Must be called with the vmobj_token held. 550 */ 551 void 552 vm_object_dead_sleep(vm_object_t object, const char *wmesg) 553 { 554 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 555 if (object->handle) { 556 vm_object_set_flag(object, OBJ_DEADWNT); 557 tsleep(object, 0, wmesg, 0); 558 /* object may be invalid after this point */ 559 } 560 } 561 562 /* 563 * Wakeup anyone waiting for the object<->pager disassociation on 564 * a dead object. 565 * 566 * Must be called with the vmobj_token held. 567 */ 568 void 569 vm_object_dead_wakeup(vm_object_t object) 570 { 571 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 572 if (object->flags & OBJ_DEADWNT) { 573 vm_object_clear_flag(object, OBJ_DEADWNT); 574 wakeup(object); 575 } 576 } 577 578 /* 579 * Clean all dirty pages in the specified range of object. Leaves page 580 * on whatever queue it is currently on. If NOSYNC is set then do not 581 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 582 * leaving the object dirty. 583 * 584 * When stuffing pages asynchronously, allow clustering. XXX we need a 585 * synchronous clustering mode implementation. 586 * 587 * Odd semantics: if start == end, we clean everything. 588 * 589 * The object must be locked? XXX 590 */ 591 static int vm_object_page_clean_pass1(struct vm_page *p, void *data); 592 static int vm_object_page_clean_pass2(struct vm_page *p, void *data); 593 594 void 595 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 596 int flags) 597 { 598 struct rb_vm_page_scan_info info; 599 struct vnode *vp; 600 int wholescan; 601 int pagerflags; 602 int curgeneration; 603 604 lwkt_gettoken(&vm_token); 605 if (object->type != OBJT_VNODE || 606 (object->flags & OBJ_MIGHTBEDIRTY) == 0) { 607 lwkt_reltoken(&vm_token); 608 return; 609 } 610 611 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? 612 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 613 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 614 615 vp = object->handle; 616 617 /* 618 * Interlock other major object operations. This allows us to 619 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY. 620 */ 621 crit_enter(); 622 vm_object_set_flag(object, OBJ_CLEANING); 623 624 /* 625 * Handle 'entire object' case 626 */ 627 info.start_pindex = start; 628 if (end == 0) { 629 info.end_pindex = object->size - 1; 630 } else { 631 info.end_pindex = end - 1; 632 } 633 wholescan = (start == 0 && info.end_pindex == object->size - 1); 634 info.limit = flags; 635 info.pagerflags = pagerflags; 636 info.object = object; 637 638 /* 639 * If cleaning the entire object do a pass to mark the pages read-only. 640 * If everything worked out ok, clear OBJ_WRITEABLE and 641 * OBJ_MIGHTBEDIRTY. 642 */ 643 if (wholescan) { 644 info.error = 0; 645 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 646 vm_object_page_clean_pass1, &info); 647 if (info.error == 0) { 648 vm_object_clear_flag(object, 649 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 650 if (object->type == OBJT_VNODE && 651 (vp = (struct vnode *)object->handle) != NULL) { 652 if (vp->v_flag & VOBJDIRTY) 653 vclrflags(vp, VOBJDIRTY); 654 } 655 } 656 } 657 658 /* 659 * Do a pass to clean all the dirty pages we find. 660 */ 661 do { 662 info.error = 0; 663 curgeneration = object->generation; 664 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 665 vm_object_page_clean_pass2, &info); 666 } while (info.error || curgeneration != object->generation); 667 668 vm_object_clear_flag(object, OBJ_CLEANING); 669 crit_exit(); 670 lwkt_reltoken(&vm_token); 671 } 672 673 /* 674 * The caller must hold vm_token. 675 */ 676 static 677 int 678 vm_object_page_clean_pass1(struct vm_page *p, void *data) 679 { 680 struct rb_vm_page_scan_info *info = data; 681 682 vm_page_flag_set(p, PG_CLEANCHK); 683 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) 684 info->error = 1; 685 else 686 vm_page_protect(p, VM_PROT_READ); /* must not block */ 687 return(0); 688 } 689 690 /* 691 * The caller must hold vm_token. 692 */ 693 static 694 int 695 vm_object_page_clean_pass2(struct vm_page *p, void *data) 696 { 697 struct rb_vm_page_scan_info *info = data; 698 int n; 699 700 /* 701 * Do not mess with pages that were inserted after we started 702 * the cleaning pass. 703 */ 704 if ((p->flags & PG_CLEANCHK) == 0) 705 return(0); 706 707 /* 708 * Before wasting time traversing the pmaps, check for trivial 709 * cases where the page cannot be dirty. 710 */ 711 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { 712 KKASSERT((p->dirty & p->valid) == 0); 713 return(0); 714 } 715 716 /* 717 * Check whether the page is dirty or not. The page has been set 718 * to be read-only so the check will not race a user dirtying the 719 * page. 720 */ 721 vm_page_test_dirty(p); 722 if ((p->dirty & p->valid) == 0) { 723 vm_page_flag_clear(p, PG_CLEANCHK); 724 return(0); 725 } 726 727 /* 728 * If we have been asked to skip nosync pages and this is a 729 * nosync page, skip it. Note that the object flags were 730 * not cleared in this case (because pass1 will have returned an 731 * error), so we do not have to set them. 732 */ 733 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 734 vm_page_flag_clear(p, PG_CLEANCHK); 735 return(0); 736 } 737 738 /* 739 * Flush as many pages as we can. PG_CLEANCHK will be cleared on 740 * the pages that get successfully flushed. Set info->error if 741 * we raced an object modification. 742 */ 743 n = vm_object_page_collect_flush(info->object, p, info->pagerflags); 744 if (n == 0) 745 info->error = 1; 746 return(0); 747 } 748 749 /* 750 * Collect the specified page and nearby pages and flush them out. 751 * The number of pages flushed is returned. 752 * 753 * The caller must hold vm_token. 754 */ 755 static int 756 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags) 757 { 758 int runlen; 759 int maxf; 760 int chkb; 761 int maxb; 762 int i; 763 int curgeneration; 764 vm_pindex_t pi; 765 vm_page_t maf[vm_pageout_page_count]; 766 vm_page_t mab[vm_pageout_page_count]; 767 vm_page_t ma[vm_pageout_page_count]; 768 769 curgeneration = object->generation; 770 771 pi = p->pindex; 772 while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { 773 if (object->generation != curgeneration) { 774 return(0); 775 } 776 } 777 KKASSERT(p->object == object && p->pindex == pi); 778 779 maxf = 0; 780 for(i = 1; i < vm_pageout_page_count; i++) { 781 vm_page_t tp; 782 783 if ((tp = vm_page_lookup(object, pi + i)) != NULL) { 784 if ((tp->flags & PG_BUSY) || 785 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 786 (tp->flags & PG_CLEANCHK) == 0) || 787 (tp->busy != 0)) 788 break; 789 if((tp->queue - tp->pc) == PQ_CACHE) { 790 vm_page_flag_clear(tp, PG_CLEANCHK); 791 break; 792 } 793 vm_page_test_dirty(tp); 794 if ((tp->dirty & tp->valid) == 0) { 795 vm_page_flag_clear(tp, PG_CLEANCHK); 796 break; 797 } 798 maf[ i - 1 ] = tp; 799 maxf++; 800 continue; 801 } 802 break; 803 } 804 805 maxb = 0; 806 chkb = vm_pageout_page_count - maxf; 807 if (chkb) { 808 for(i = 1; i < chkb;i++) { 809 vm_page_t tp; 810 811 if ((tp = vm_page_lookup(object, pi - i)) != NULL) { 812 if ((tp->flags & PG_BUSY) || 813 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 814 (tp->flags & PG_CLEANCHK) == 0) || 815 (tp->busy != 0)) 816 break; 817 if((tp->queue - tp->pc) == PQ_CACHE) { 818 vm_page_flag_clear(tp, PG_CLEANCHK); 819 break; 820 } 821 vm_page_test_dirty(tp); 822 if ((tp->dirty & tp->valid) == 0) { 823 vm_page_flag_clear(tp, PG_CLEANCHK); 824 break; 825 } 826 mab[ i - 1 ] = tp; 827 maxb++; 828 continue; 829 } 830 break; 831 } 832 } 833 834 for(i = 0; i < maxb; i++) { 835 int index = (maxb - i) - 1; 836 ma[index] = mab[i]; 837 vm_page_flag_clear(ma[index], PG_CLEANCHK); 838 } 839 vm_page_flag_clear(p, PG_CLEANCHK); 840 ma[maxb] = p; 841 for(i = 0; i < maxf; i++) { 842 int index = (maxb + i) + 1; 843 ma[index] = maf[i]; 844 vm_page_flag_clear(ma[index], PG_CLEANCHK); 845 } 846 runlen = maxb + maxf + 1; 847 848 vm_pageout_flush(ma, runlen, pagerflags); 849 for (i = 0; i < runlen; i++) { 850 if (ma[i]->valid & ma[i]->dirty) { 851 vm_page_protect(ma[i], VM_PROT_READ); 852 vm_page_flag_set(ma[i], PG_CLEANCHK); 853 854 /* 855 * maxf will end up being the actual number of pages 856 * we wrote out contiguously, non-inclusive of the 857 * first page. We do not count look-behind pages. 858 */ 859 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 860 maxf = i - maxb - 1; 861 } 862 } 863 return(maxf + 1); 864 } 865 866 /* 867 * Same as vm_object_pmap_copy, except range checking really 868 * works, and is meant for small sections of an object. 869 * 870 * This code protects resident pages by making them read-only 871 * and is typically called on a fork or split when a page 872 * is converted to copy-on-write. 873 * 874 * NOTE: If the page is already at VM_PROT_NONE, calling 875 * vm_page_protect will have no effect. 876 */ 877 void 878 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 879 { 880 vm_pindex_t idx; 881 vm_page_t p; 882 883 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 884 return; 885 886 /* 887 * spl protection needed to prevent races between the lookup, 888 * an interrupt unbusy/free, and our protect call. 889 */ 890 crit_enter(); 891 lwkt_gettoken(&vm_token); 892 for (idx = start; idx < end; idx++) { 893 p = vm_page_lookup(object, idx); 894 if (p == NULL) 895 continue; 896 vm_page_protect(p, VM_PROT_READ); 897 } 898 lwkt_reltoken(&vm_token); 899 crit_exit(); 900 } 901 902 /* 903 * Removes all physical pages in the specified object range from all 904 * physical maps. 905 * 906 * The object must *not* be locked. 907 */ 908 909 static int vm_object_pmap_remove_callback(vm_page_t p, void *data); 910 911 void 912 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 913 { 914 struct rb_vm_page_scan_info info; 915 916 if (object == NULL) 917 return; 918 info.start_pindex = start; 919 info.end_pindex = end - 1; 920 921 crit_enter(); 922 lwkt_gettoken(&vm_token); 923 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 924 vm_object_pmap_remove_callback, &info); 925 if (start == 0 && end == object->size) 926 vm_object_clear_flag(object, OBJ_WRITEABLE); 927 lwkt_reltoken(&vm_token); 928 crit_exit(); 929 } 930 931 /* 932 * The caller must hold vm_token. 933 */ 934 static int 935 vm_object_pmap_remove_callback(vm_page_t p, void *data __unused) 936 { 937 vm_page_protect(p, VM_PROT_NONE); 938 return(0); 939 } 940 941 /* 942 * Implements the madvise function at the object/page level. 943 * 944 * MADV_WILLNEED (any object) 945 * 946 * Activate the specified pages if they are resident. 947 * 948 * MADV_DONTNEED (any object) 949 * 950 * Deactivate the specified pages if they are resident. 951 * 952 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only) 953 * 954 * Deactivate and clean the specified pages if they are 955 * resident. This permits the process to reuse the pages 956 * without faulting or the kernel to reclaim the pages 957 * without I/O. 958 * 959 * No requirements. 960 */ 961 void 962 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise) 963 { 964 vm_pindex_t end, tpindex; 965 vm_object_t tobject; 966 vm_page_t m; 967 968 if (object == NULL) 969 return; 970 971 end = pindex + count; 972 973 lwkt_gettoken(&vm_token); 974 975 /* 976 * Locate and adjust resident pages 977 */ 978 for (; pindex < end; pindex += 1) { 979 relookup: 980 tobject = object; 981 tpindex = pindex; 982 shadowlookup: 983 /* 984 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 985 * and those pages must be OBJ_ONEMAPPING. 986 */ 987 if (advise == MADV_FREE) { 988 if ((tobject->type != OBJT_DEFAULT && 989 tobject->type != OBJT_SWAP) || 990 (tobject->flags & OBJ_ONEMAPPING) == 0) { 991 continue; 992 } 993 } 994 995 /* 996 * spl protection is required to avoid a race between the 997 * lookup, an interrupt unbusy/free, and our busy check. 998 */ 999 1000 crit_enter(); 1001 m = vm_page_lookup(tobject, tpindex); 1002 1003 if (m == NULL) { 1004 /* 1005 * There may be swap even if there is no backing page 1006 */ 1007 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1008 swap_pager_freespace(tobject, tpindex, 1); 1009 1010 /* 1011 * next object 1012 */ 1013 crit_exit(); 1014 if (tobject->backing_object == NULL) 1015 continue; 1016 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1017 tobject = tobject->backing_object; 1018 goto shadowlookup; 1019 } 1020 1021 /* 1022 * If the page is busy or not in a normal active state, 1023 * we skip it. If the page is not managed there are no 1024 * page queues to mess with. Things can break if we mess 1025 * with pages in any of the below states. 1026 */ 1027 if ( 1028 m->hold_count || 1029 m->wire_count || 1030 (m->flags & PG_UNMANAGED) || 1031 m->valid != VM_PAGE_BITS_ALL 1032 ) { 1033 crit_exit(); 1034 continue; 1035 } 1036 1037 if (vm_page_sleep_busy(m, TRUE, "madvpo")) { 1038 crit_exit(); 1039 goto relookup; 1040 } 1041 vm_page_busy(m); 1042 crit_exit(); 1043 1044 /* 1045 * Theoretically once a page is known not to be busy, an 1046 * interrupt cannot come along and rip it out from under us. 1047 */ 1048 1049 if (advise == MADV_WILLNEED) { 1050 vm_page_activate(m); 1051 } else if (advise == MADV_DONTNEED) { 1052 vm_page_dontneed(m); 1053 } else if (advise == MADV_FREE) { 1054 /* 1055 * Mark the page clean. This will allow the page 1056 * to be freed up by the system. However, such pages 1057 * are often reused quickly by malloc()/free() 1058 * so we do not do anything that would cause 1059 * a page fault if we can help it. 1060 * 1061 * Specifically, we do not try to actually free 1062 * the page now nor do we try to put it in the 1063 * cache (which would cause a page fault on reuse). 1064 * 1065 * But we do make the page is freeable as we 1066 * can without actually taking the step of unmapping 1067 * it. 1068 */ 1069 pmap_clear_modify(m); 1070 m->dirty = 0; 1071 m->act_count = 0; 1072 vm_page_dontneed(m); 1073 if (tobject->type == OBJT_SWAP) 1074 swap_pager_freespace(tobject, tpindex, 1); 1075 } 1076 vm_page_wakeup(m); 1077 } 1078 lwkt_reltoken(&vm_token); 1079 } 1080 1081 /* 1082 * Create a new object which is backed by the specified existing object 1083 * range. The source object reference is deallocated. 1084 * 1085 * The new object and offset into that object are returned in the source 1086 * parameters. 1087 * 1088 * No other requirements. 1089 */ 1090 void 1091 vm_object_shadow(vm_object_t *object, vm_ooffset_t *offset, vm_size_t length) 1092 { 1093 vm_object_t source; 1094 vm_object_t result; 1095 1096 source = *object; 1097 1098 /* 1099 * Don't create the new object if the old object isn't shared. 1100 */ 1101 lwkt_gettoken(&vm_token); 1102 1103 if (source != NULL && 1104 source->ref_count == 1 && 1105 source->handle == NULL && 1106 (source->type == OBJT_DEFAULT || 1107 source->type == OBJT_SWAP)) { 1108 lwkt_reltoken(&vm_token); 1109 return; 1110 } 1111 1112 /* 1113 * Allocate a new object with the given length 1114 */ 1115 1116 if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) 1117 panic("vm_object_shadow: no object for shadowing"); 1118 1119 /* 1120 * The new object shadows the source object, adding a reference to it. 1121 * Our caller changes his reference to point to the new object, 1122 * removing a reference to the source object. Net result: no change 1123 * of reference count. 1124 * 1125 * Try to optimize the result object's page color when shadowing 1126 * in order to maintain page coloring consistency in the combined 1127 * shadowed object. 1128 */ 1129 result->backing_object = source; 1130 if (source) { 1131 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); 1132 source->shadow_count++; 1133 source->generation++; 1134 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK; 1135 } 1136 1137 /* 1138 * Store the offset into the source object, and fix up the offset into 1139 * the new object. 1140 */ 1141 result->backing_object_offset = *offset; 1142 lwkt_reltoken(&vm_token); 1143 1144 /* 1145 * Return the new things 1146 */ 1147 *offset = 0; 1148 *object = result; 1149 } 1150 1151 #define OBSC_TEST_ALL_SHADOWED 0x0001 1152 #define OBSC_COLLAPSE_NOWAIT 0x0002 1153 #define OBSC_COLLAPSE_WAIT 0x0004 1154 1155 static int vm_object_backing_scan_callback(vm_page_t p, void *data); 1156 1157 /* 1158 * The caller must hold vm_token. 1159 */ 1160 static __inline int 1161 vm_object_backing_scan(vm_object_t object, int op) 1162 { 1163 struct rb_vm_page_scan_info info; 1164 vm_object_t backing_object; 1165 1166 crit_enter(); 1167 1168 backing_object = object->backing_object; 1169 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1170 1171 /* 1172 * Initial conditions 1173 */ 1174 1175 if (op & OBSC_TEST_ALL_SHADOWED) { 1176 /* 1177 * We do not want to have to test for the existence of 1178 * swap pages in the backing object. XXX but with the 1179 * new swapper this would be pretty easy to do. 1180 * 1181 * XXX what about anonymous MAP_SHARED memory that hasn't 1182 * been ZFOD faulted yet? If we do not test for this, the 1183 * shadow test may succeed! XXX 1184 */ 1185 if (backing_object->type != OBJT_DEFAULT) { 1186 crit_exit(); 1187 return(0); 1188 } 1189 } 1190 if (op & OBSC_COLLAPSE_WAIT) { 1191 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 1192 vm_object_set_flag(backing_object, OBJ_DEAD); 1193 } 1194 1195 /* 1196 * Our scan. We have to retry if a negative error code is returned, 1197 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that 1198 * the scan had to be stopped because the parent does not completely 1199 * shadow the child. 1200 */ 1201 info.object = object; 1202 info.backing_object = backing_object; 1203 info.limit = op; 1204 do { 1205 info.error = 1; 1206 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL, 1207 vm_object_backing_scan_callback, 1208 &info); 1209 } while (info.error < 0); 1210 crit_exit(); 1211 return(info.error); 1212 } 1213 1214 /* 1215 * The caller must hold vm_token. 1216 */ 1217 static int 1218 vm_object_backing_scan_callback(vm_page_t p, void *data) 1219 { 1220 struct rb_vm_page_scan_info *info = data; 1221 vm_object_t backing_object; 1222 vm_object_t object; 1223 vm_pindex_t new_pindex; 1224 vm_pindex_t backing_offset_index; 1225 int op; 1226 1227 new_pindex = p->pindex - info->backing_offset_index; 1228 op = info->limit; 1229 object = info->object; 1230 backing_object = info->backing_object; 1231 backing_offset_index = info->backing_offset_index; 1232 1233 if (op & OBSC_TEST_ALL_SHADOWED) { 1234 vm_page_t pp; 1235 1236 /* 1237 * Ignore pages outside the parent object's range 1238 * and outside the parent object's mapping of the 1239 * backing object. 1240 * 1241 * note that we do not busy the backing object's 1242 * page. 1243 */ 1244 if ( 1245 p->pindex < backing_offset_index || 1246 new_pindex >= object->size 1247 ) { 1248 return(0); 1249 } 1250 1251 /* 1252 * See if the parent has the page or if the parent's 1253 * object pager has the page. If the parent has the 1254 * page but the page is not valid, the parent's 1255 * object pager must have the page. 1256 * 1257 * If this fails, the parent does not completely shadow 1258 * the object and we might as well give up now. 1259 */ 1260 1261 pp = vm_page_lookup(object, new_pindex); 1262 if ((pp == NULL || pp->valid == 0) && 1263 !vm_pager_has_page(object, new_pindex) 1264 ) { 1265 info->error = 0; /* problemo */ 1266 return(-1); /* stop the scan */ 1267 } 1268 } 1269 1270 /* 1271 * Check for busy page 1272 */ 1273 1274 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1275 vm_page_t pp; 1276 1277 if (op & OBSC_COLLAPSE_NOWAIT) { 1278 if ( 1279 (p->flags & PG_BUSY) || 1280 !p->valid || 1281 p->hold_count || 1282 p->wire_count || 1283 p->busy 1284 ) { 1285 return(0); 1286 } 1287 } else if (op & OBSC_COLLAPSE_WAIT) { 1288 if (vm_page_sleep_busy(p, TRUE, "vmocol")) { 1289 /* 1290 * If we slept, anything could have 1291 * happened. Ask that the scan be restarted. 1292 * 1293 * Since the object is marked dead, the 1294 * backing offset should not have changed. 1295 */ 1296 info->error = -1; 1297 return(-1); 1298 } 1299 } 1300 1301 /* 1302 * Busy the page 1303 */ 1304 vm_page_busy(p); 1305 1306 KASSERT( 1307 p->object == backing_object, 1308 ("vm_object_qcollapse(): object mismatch") 1309 ); 1310 1311 /* 1312 * Destroy any associated swap 1313 */ 1314 if (backing_object->type == OBJT_SWAP) 1315 swap_pager_freespace(backing_object, p->pindex, 1); 1316 1317 if ( 1318 p->pindex < backing_offset_index || 1319 new_pindex >= object->size 1320 ) { 1321 /* 1322 * Page is out of the parent object's range, we 1323 * can simply destroy it. 1324 */ 1325 vm_page_protect(p, VM_PROT_NONE); 1326 vm_page_free(p); 1327 return(0); 1328 } 1329 1330 pp = vm_page_lookup(object, new_pindex); 1331 if (pp != NULL || vm_pager_has_page(object, new_pindex)) { 1332 /* 1333 * page already exists in parent OR swap exists 1334 * for this location in the parent. Destroy 1335 * the original page from the backing object. 1336 * 1337 * Leave the parent's page alone 1338 */ 1339 vm_page_protect(p, VM_PROT_NONE); 1340 vm_page_free(p); 1341 return(0); 1342 } 1343 1344 /* 1345 * Page does not exist in parent, rename the 1346 * page from the backing object to the main object. 1347 * 1348 * If the page was mapped to a process, it can remain 1349 * mapped through the rename. 1350 */ 1351 if ((p->queue - p->pc) == PQ_CACHE) 1352 vm_page_deactivate(p); 1353 1354 vm_page_rename(p, object, new_pindex); 1355 /* page automatically made dirty by rename */ 1356 } 1357 return(0); 1358 } 1359 1360 /* 1361 * This version of collapse allows the operation to occur earlier and 1362 * when paging_in_progress is true for an object... This is not a complete 1363 * operation, but should plug 99.9% of the rest of the leaks. 1364 * 1365 * The caller must hold vm_token and vmobj_token. 1366 * (only called from vm_object_collapse) 1367 */ 1368 static void 1369 vm_object_qcollapse(vm_object_t object) 1370 { 1371 vm_object_t backing_object = object->backing_object; 1372 1373 if (backing_object->ref_count != 1) 1374 return; 1375 1376 backing_object->ref_count += 2; 1377 1378 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 1379 1380 backing_object->ref_count -= 2; 1381 } 1382 1383 /* 1384 * Collapse an object with the object backing it. Pages in the backing 1385 * object are moved into the parent, and the backing object is deallocated. 1386 */ 1387 void 1388 vm_object_collapse(vm_object_t object) 1389 { 1390 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1391 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1392 1393 while (TRUE) { 1394 vm_object_t backing_object; 1395 1396 /* 1397 * Verify that the conditions are right for collapse: 1398 * 1399 * The object exists and the backing object exists. 1400 */ 1401 if (object == NULL) 1402 break; 1403 1404 if ((backing_object = object->backing_object) == NULL) 1405 break; 1406 1407 /* 1408 * we check the backing object first, because it is most likely 1409 * not collapsable. 1410 */ 1411 if (backing_object->handle != NULL || 1412 (backing_object->type != OBJT_DEFAULT && 1413 backing_object->type != OBJT_SWAP) || 1414 (backing_object->flags & OBJ_DEAD) || 1415 object->handle != NULL || 1416 (object->type != OBJT_DEFAULT && 1417 object->type != OBJT_SWAP) || 1418 (object->flags & OBJ_DEAD)) { 1419 break; 1420 } 1421 1422 if ( 1423 object->paging_in_progress != 0 || 1424 backing_object->paging_in_progress != 0 1425 ) { 1426 vm_object_qcollapse(object); 1427 break; 1428 } 1429 1430 /* 1431 * We know that we can either collapse the backing object (if 1432 * the parent is the only reference to it) or (perhaps) have 1433 * the parent bypass the object if the parent happens to shadow 1434 * all the resident pages in the entire backing object. 1435 * 1436 * This is ignoring pager-backed pages such as swap pages. 1437 * vm_object_backing_scan fails the shadowing test in this 1438 * case. 1439 */ 1440 1441 if (backing_object->ref_count == 1) { 1442 /* 1443 * If there is exactly one reference to the backing 1444 * object, we can collapse it into the parent. 1445 */ 1446 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); 1447 1448 /* 1449 * Move the pager from backing_object to object. 1450 */ 1451 1452 if (backing_object->type == OBJT_SWAP) { 1453 vm_object_pip_add(backing_object, 1); 1454 1455 /* 1456 * scrap the paging_offset junk and do a 1457 * discrete copy. This also removes major 1458 * assumptions about how the swap-pager 1459 * works from where it doesn't belong. The 1460 * new swapper is able to optimize the 1461 * destroy-source case. 1462 */ 1463 1464 vm_object_pip_add(object, 1); 1465 swap_pager_copy( 1466 backing_object, 1467 object, 1468 OFF_TO_IDX(object->backing_object_offset), TRUE); 1469 vm_object_pip_wakeup(object); 1470 1471 vm_object_pip_wakeup(backing_object); 1472 } 1473 /* 1474 * Object now shadows whatever backing_object did. 1475 * Note that the reference to 1476 * backing_object->backing_object moves from within 1477 * backing_object to within object. 1478 */ 1479 1480 LIST_REMOVE(object, shadow_list); 1481 object->backing_object->shadow_count--; 1482 object->backing_object->generation++; 1483 if (backing_object->backing_object) { 1484 LIST_REMOVE(backing_object, shadow_list); 1485 backing_object->backing_object->shadow_count--; 1486 backing_object->backing_object->generation++; 1487 } 1488 object->backing_object = backing_object->backing_object; 1489 if (object->backing_object) { 1490 LIST_INSERT_HEAD( 1491 &object->backing_object->shadow_head, 1492 object, 1493 shadow_list 1494 ); 1495 object->backing_object->shadow_count++; 1496 object->backing_object->generation++; 1497 } 1498 1499 object->backing_object_offset += 1500 backing_object->backing_object_offset; 1501 1502 /* 1503 * Discard backing_object. 1504 * 1505 * Since the backing object has no pages, no pager left, 1506 * and no object references within it, all that is 1507 * necessary is to dispose of it. 1508 */ 1509 1510 KASSERT(backing_object->ref_count == 1, 1511 ("backing_object %p was somehow " 1512 "re-referenced during collapse!", 1513 backing_object)); 1514 KASSERT(RB_EMPTY(&backing_object->rb_memq), 1515 ("backing_object %p somehow has left " 1516 "over pages during collapse!", 1517 backing_object)); 1518 1519 /* (we are holding vmobj_token) */ 1520 TAILQ_REMOVE(&vm_object_list, backing_object, 1521 object_list); 1522 vm_object_count--; 1523 1524 zfree(obj_zone, backing_object); 1525 1526 object_collapses++; 1527 } else { 1528 vm_object_t new_backing_object; 1529 1530 /* 1531 * If we do not entirely shadow the backing object, 1532 * there is nothing we can do so we give up. 1533 */ 1534 1535 if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) { 1536 break; 1537 } 1538 1539 /* 1540 * Make the parent shadow the next object in the 1541 * chain. Deallocating backing_object will not remove 1542 * it, since its reference count is at least 2. 1543 */ 1544 1545 LIST_REMOVE(object, shadow_list); 1546 backing_object->shadow_count--; 1547 backing_object->generation++; 1548 1549 new_backing_object = backing_object->backing_object; 1550 if ((object->backing_object = new_backing_object) != NULL) { 1551 vm_object_reference(new_backing_object); 1552 LIST_INSERT_HEAD( 1553 &new_backing_object->shadow_head, 1554 object, 1555 shadow_list 1556 ); 1557 new_backing_object->shadow_count++; 1558 new_backing_object->generation++; 1559 object->backing_object_offset += 1560 backing_object->backing_object_offset; 1561 } 1562 1563 /* 1564 * Drop the reference count on backing_object. Since 1565 * its ref_count was at least 2, it will not vanish; 1566 * so we don't need to call vm_object_deallocate, but 1567 * we do anyway. 1568 */ 1569 vm_object_deallocate_locked(backing_object); 1570 object_bypasses++; 1571 } 1572 1573 /* 1574 * Try again with this object's new backing object. 1575 */ 1576 } 1577 } 1578 1579 /* 1580 * Removes all physical pages in the specified object range from the 1581 * object's list of pages. 1582 * 1583 * No requirements. 1584 */ 1585 static int vm_object_page_remove_callback(vm_page_t p, void *data); 1586 1587 void 1588 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1589 boolean_t clean_only) 1590 { 1591 struct rb_vm_page_scan_info info; 1592 int all; 1593 1594 /* 1595 * Degenerate cases and assertions 1596 */ 1597 lwkt_gettoken(&vm_token); 1598 if (object == NULL || 1599 (object->resident_page_count == 0 && object->swblock_count == 0)) { 1600 lwkt_reltoken(&vm_token); 1601 return; 1602 } 1603 KASSERT(object->type != OBJT_PHYS, 1604 ("attempt to remove pages from a physical object")); 1605 1606 /* 1607 * Indicate that paging is occuring on the object 1608 */ 1609 crit_enter(); 1610 vm_object_pip_add(object, 1); 1611 1612 /* 1613 * Figure out the actual removal range and whether we are removing 1614 * the entire contents of the object or not. If removing the entire 1615 * contents, be sure to get all pages, even those that might be 1616 * beyond the end of the object. 1617 */ 1618 info.start_pindex = start; 1619 if (end == 0) 1620 info.end_pindex = (vm_pindex_t)-1; 1621 else 1622 info.end_pindex = end - 1; 1623 info.limit = clean_only; 1624 all = (start == 0 && info.end_pindex >= object->size - 1); 1625 1626 /* 1627 * Loop until we are sure we have gotten them all. 1628 */ 1629 do { 1630 info.error = 0; 1631 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp, 1632 vm_object_page_remove_callback, &info); 1633 } while (info.error); 1634 1635 /* 1636 * Remove any related swap if throwing away pages, or for 1637 * non-swap objects (the swap is a clean copy in that case). 1638 */ 1639 if (object->type != OBJT_SWAP || clean_only == FALSE) { 1640 if (all) 1641 swap_pager_freespace_all(object); 1642 else 1643 swap_pager_freespace(object, info.start_pindex, 1644 info.end_pindex - info.start_pindex + 1); 1645 } 1646 1647 /* 1648 * Cleanup 1649 */ 1650 vm_object_pip_wakeup(object); 1651 crit_exit(); 1652 lwkt_reltoken(&vm_token); 1653 } 1654 1655 /* 1656 * The caller must hold vm_token. 1657 */ 1658 static int 1659 vm_object_page_remove_callback(vm_page_t p, void *data) 1660 { 1661 struct rb_vm_page_scan_info *info = data; 1662 1663 /* 1664 * Wired pages cannot be destroyed, but they can be invalidated 1665 * and we do so if clean_only (limit) is not set. 1666 * 1667 * WARNING! The page may be wired due to being part of a buffer 1668 * cache buffer, and the buffer might be marked B_CACHE. 1669 * This is fine as part of a truncation but VFSs must be 1670 * sure to fix the buffer up when re-extending the file. 1671 */ 1672 if (p->wire_count != 0) { 1673 vm_page_protect(p, VM_PROT_NONE); 1674 if (info->limit == 0) 1675 p->valid = 0; 1676 return(0); 1677 } 1678 1679 /* 1680 * The busy flags are only cleared at 1681 * interrupt -- minimize the spl transitions 1682 */ 1683 1684 if (vm_page_sleep_busy(p, TRUE, "vmopar")) { 1685 info->error = 1; 1686 return(0); 1687 } 1688 1689 /* 1690 * limit is our clean_only flag. If set and the page is dirty, do 1691 * not free it. If set and the page is being held by someone, do 1692 * not free it. 1693 */ 1694 if (info->limit && p->valid) { 1695 vm_page_test_dirty(p); 1696 if (p->valid & p->dirty) 1697 return(0); 1698 if (p->hold_count) 1699 return(0); 1700 } 1701 1702 /* 1703 * Destroy the page 1704 */ 1705 vm_page_busy(p); 1706 vm_page_protect(p, VM_PROT_NONE); 1707 vm_page_free(p); 1708 return(0); 1709 } 1710 1711 /* 1712 * Coalesces two objects backing up adjoining regions of memory into a 1713 * single object. 1714 * 1715 * returns TRUE if objects were combined. 1716 * 1717 * NOTE: Only works at the moment if the second object is NULL - 1718 * if it's not, which object do we lock first? 1719 * 1720 * Parameters: 1721 * prev_object First object to coalesce 1722 * prev_offset Offset into prev_object 1723 * next_object Second object into coalesce 1724 * next_offset Offset into next_object 1725 * 1726 * prev_size Size of reference to prev_object 1727 * next_size Size of reference to next_object 1728 * 1729 * The object must not be locked. 1730 * The caller must hold vm_token and vmobj_token. 1731 */ 1732 boolean_t 1733 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 1734 vm_size_t prev_size, vm_size_t next_size) 1735 { 1736 vm_pindex_t next_pindex; 1737 1738 ASSERT_LWKT_TOKEN_HELD(&vm_token); 1739 ASSERT_LWKT_TOKEN_HELD(&vmobj_token); 1740 1741 if (prev_object == NULL) { 1742 return (TRUE); 1743 } 1744 1745 if (prev_object->type != OBJT_DEFAULT && 1746 prev_object->type != OBJT_SWAP) { 1747 return (FALSE); 1748 } 1749 1750 /* 1751 * Try to collapse the object first 1752 */ 1753 vm_object_collapse(prev_object); 1754 1755 /* 1756 * Can't coalesce if: . more than one reference . paged out . shadows 1757 * another object . has a copy elsewhere (any of which mean that the 1758 * pages not mapped to prev_entry may be in use anyway) 1759 */ 1760 1761 if (prev_object->backing_object != NULL) 1762 return (FALSE); 1763 1764 prev_size >>= PAGE_SHIFT; 1765 next_size >>= PAGE_SHIFT; 1766 next_pindex = prev_pindex + prev_size; 1767 1768 if ((prev_object->ref_count > 1) && 1769 (prev_object->size != next_pindex)) { 1770 return (FALSE); 1771 } 1772 1773 /* 1774 * Remove any pages that may still be in the object from a previous 1775 * deallocation. 1776 */ 1777 if (next_pindex < prev_object->size) { 1778 vm_object_page_remove(prev_object, 1779 next_pindex, 1780 next_pindex + next_size, FALSE); 1781 if (prev_object->type == OBJT_SWAP) 1782 swap_pager_freespace(prev_object, 1783 next_pindex, next_size); 1784 } 1785 1786 /* 1787 * Extend the object if necessary. 1788 */ 1789 if (next_pindex + next_size > prev_object->size) 1790 prev_object->size = next_pindex + next_size; 1791 return (TRUE); 1792 } 1793 1794 /* 1795 * Make the object writable and flag is being possibly dirty. 1796 * 1797 * No requirements. 1798 */ 1799 void 1800 vm_object_set_writeable_dirty(vm_object_t object) 1801 { 1802 struct vnode *vp; 1803 1804 lwkt_gettoken(&vm_token); 1805 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1806 if (object->type == OBJT_VNODE && 1807 (vp = (struct vnode *)object->handle) != NULL) { 1808 if ((vp->v_flag & VOBJDIRTY) == 0) { 1809 vsetflags(vp, VOBJDIRTY); 1810 } 1811 } 1812 lwkt_reltoken(&vm_token); 1813 } 1814 1815 #include "opt_ddb.h" 1816 #ifdef DDB 1817 #include <sys/kernel.h> 1818 1819 #include <sys/cons.h> 1820 1821 #include <ddb/ddb.h> 1822 1823 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 1824 vm_map_entry_t entry); 1825 static int vm_object_in_map (vm_object_t object); 1826 1827 /* 1828 * The caller must hold vm_token. 1829 */ 1830 static int 1831 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 1832 { 1833 vm_map_t tmpm; 1834 vm_map_entry_t tmpe; 1835 vm_object_t obj; 1836 int entcount; 1837 1838 if (map == 0) 1839 return 0; 1840 if (entry == 0) { 1841 tmpe = map->header.next; 1842 entcount = map->nentries; 1843 while (entcount-- && (tmpe != &map->header)) { 1844 if( _vm_object_in_map(map, object, tmpe)) { 1845 return 1; 1846 } 1847 tmpe = tmpe->next; 1848 } 1849 return (0); 1850 } 1851 switch(entry->maptype) { 1852 case VM_MAPTYPE_SUBMAP: 1853 tmpm = entry->object.sub_map; 1854 tmpe = tmpm->header.next; 1855 entcount = tmpm->nentries; 1856 while (entcount-- && tmpe != &tmpm->header) { 1857 if( _vm_object_in_map(tmpm, object, tmpe)) { 1858 return 1; 1859 } 1860 tmpe = tmpe->next; 1861 } 1862 break; 1863 case VM_MAPTYPE_NORMAL: 1864 case VM_MAPTYPE_VPAGETABLE: 1865 obj = entry->object.vm_object; 1866 while (obj) { 1867 if (obj == object) 1868 return 1; 1869 obj = obj->backing_object; 1870 } 1871 break; 1872 default: 1873 break; 1874 } 1875 return 0; 1876 } 1877 1878 static int vm_object_in_map_callback(struct proc *p, void *data); 1879 1880 struct vm_object_in_map_info { 1881 vm_object_t object; 1882 int rv; 1883 }; 1884 1885 /* 1886 * Debugging only 1887 */ 1888 static int 1889 vm_object_in_map(vm_object_t object) 1890 { 1891 struct vm_object_in_map_info info; 1892 1893 info.rv = 0; 1894 info.object = object; 1895 1896 allproc_scan(vm_object_in_map_callback, &info); 1897 if (info.rv) 1898 return 1; 1899 if( _vm_object_in_map(&kernel_map, object, 0)) 1900 return 1; 1901 if( _vm_object_in_map(&pager_map, object, 0)) 1902 return 1; 1903 if( _vm_object_in_map(&buffer_map, object, 0)) 1904 return 1; 1905 return 0; 1906 } 1907 1908 /* 1909 * Debugging only 1910 */ 1911 static int 1912 vm_object_in_map_callback(struct proc *p, void *data) 1913 { 1914 struct vm_object_in_map_info *info = data; 1915 1916 if (p->p_vmspace) { 1917 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) { 1918 info->rv = 1; 1919 return -1; 1920 } 1921 } 1922 return (0); 1923 } 1924 1925 DB_SHOW_COMMAND(vmochk, vm_object_check) 1926 { 1927 vm_object_t object; 1928 1929 /* 1930 * make sure that internal objs are in a map somewhere 1931 * and none have zero ref counts. 1932 */ 1933 for (object = TAILQ_FIRST(&vm_object_list); 1934 object != NULL; 1935 object = TAILQ_NEXT(object, object_list)) { 1936 if (object->type == OBJT_MARKER) 1937 continue; 1938 if (object->handle == NULL && 1939 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 1940 if (object->ref_count == 0) { 1941 db_printf("vmochk: internal obj has zero ref count: %ld\n", 1942 (long)object->size); 1943 } 1944 if (!vm_object_in_map(object)) { 1945 db_printf( 1946 "vmochk: internal obj is not in a map: " 1947 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 1948 object->ref_count, (u_long)object->size, 1949 (u_long)object->size, 1950 (void *)object->backing_object); 1951 } 1952 } 1953 } 1954 } 1955 1956 /* 1957 * Debugging only 1958 */ 1959 DB_SHOW_COMMAND(object, vm_object_print_static) 1960 { 1961 /* XXX convert args. */ 1962 vm_object_t object = (vm_object_t)addr; 1963 boolean_t full = have_addr; 1964 1965 vm_page_t p; 1966 1967 /* XXX count is an (unused) arg. Avoid shadowing it. */ 1968 #define count was_count 1969 1970 int count; 1971 1972 if (object == NULL) 1973 return; 1974 1975 db_iprintf( 1976 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 1977 object, (int)object->type, (u_long)object->size, 1978 object->resident_page_count, object->ref_count, object->flags); 1979 /* 1980 * XXX no %qd in kernel. Truncate object->backing_object_offset. 1981 */ 1982 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 1983 object->shadow_count, 1984 object->backing_object ? object->backing_object->ref_count : 0, 1985 object->backing_object, (long)object->backing_object_offset); 1986 1987 if (!full) 1988 return; 1989 1990 db_indent += 2; 1991 count = 0; 1992 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) { 1993 if (count == 0) 1994 db_iprintf("memory:="); 1995 else if (count == 6) { 1996 db_printf("\n"); 1997 db_iprintf(" ..."); 1998 count = 0; 1999 } else 2000 db_printf(","); 2001 count++; 2002 2003 db_printf("(off=0x%lx,page=0x%lx)", 2004 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 2005 } 2006 if (count != 0) 2007 db_printf("\n"); 2008 db_indent -= 2; 2009 } 2010 2011 /* XXX. */ 2012 #undef count 2013 2014 /* 2015 * XXX need this non-static entry for calling from vm_map_print. 2016 * 2017 * Debugging only 2018 */ 2019 void 2020 vm_object_print(/* db_expr_t */ long addr, 2021 boolean_t have_addr, 2022 /* db_expr_t */ long count, 2023 char *modif) 2024 { 2025 vm_object_print_static(addr, have_addr, count, modif); 2026 } 2027 2028 /* 2029 * Debugging only 2030 */ 2031 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 2032 { 2033 vm_object_t object; 2034 int nl = 0; 2035 int c; 2036 for (object = TAILQ_FIRST(&vm_object_list); 2037 object != NULL; 2038 object = TAILQ_NEXT(object, object_list)) { 2039 vm_pindex_t idx, fidx; 2040 vm_pindex_t osize; 2041 vm_paddr_t pa = -1, padiff; 2042 int rcount; 2043 vm_page_t m; 2044 2045 if (object->type == OBJT_MARKER) 2046 continue; 2047 db_printf("new object: %p\n", (void *)object); 2048 if ( nl > 18) { 2049 c = cngetc(); 2050 if (c != ' ') 2051 return; 2052 nl = 0; 2053 } 2054 nl++; 2055 rcount = 0; 2056 fidx = 0; 2057 osize = object->size; 2058 if (osize > 128) 2059 osize = 128; 2060 for (idx = 0; idx < osize; idx++) { 2061 m = vm_page_lookup(object, idx); 2062 if (m == NULL) { 2063 if (rcount) { 2064 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2065 (long)fidx, rcount, (long)pa); 2066 if ( nl > 18) { 2067 c = cngetc(); 2068 if (c != ' ') 2069 return; 2070 nl = 0; 2071 } 2072 nl++; 2073 rcount = 0; 2074 } 2075 continue; 2076 } 2077 2078 2079 if (rcount && 2080 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 2081 ++rcount; 2082 continue; 2083 } 2084 if (rcount) { 2085 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 2086 padiff >>= PAGE_SHIFT; 2087 padiff &= PQ_L2_MASK; 2088 if (padiff == 0) { 2089 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 2090 ++rcount; 2091 continue; 2092 } 2093 db_printf(" index(%ld)run(%d)pa(0x%lx)", 2094 (long)fidx, rcount, (long)pa); 2095 db_printf("pd(%ld)\n", (long)padiff); 2096 if ( nl > 18) { 2097 c = cngetc(); 2098 if (c != ' ') 2099 return; 2100 nl = 0; 2101 } 2102 nl++; 2103 } 2104 fidx = idx; 2105 pa = VM_PAGE_TO_PHYS(m); 2106 rcount = 1; 2107 } 2108 if (rcount) { 2109 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2110 (long)fidx, rcount, (long)pa); 2111 if ( nl > 18) { 2112 c = cngetc(); 2113 if (c != ' ') 2114 return; 2115 nl = 0; 2116 } 2117 nl++; 2118 } 2119 } 2120 } 2121 #endif /* DDB */ 2122