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