1 /* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 * 64 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ 65 * $DragonFly: src/sys/vm/vm_object.c,v 1.16 2004/05/13 17:40:19 dillon Exp $ 66 */ 67 68 /* 69 * Virtual memory object module. 70 */ 71 72 #include <sys/param.h> 73 #include <sys/systm.h> 74 #include <sys/proc.h> /* for curproc, pageproc */ 75 #include <sys/vnode.h> 76 #include <sys/vmmeter.h> 77 #include <sys/mman.h> 78 #include <sys/mount.h> 79 #include <sys/kernel.h> 80 #include <sys/sysctl.h> 81 82 #include <vm/vm.h> 83 #include <vm/vm_param.h> 84 #include <vm/pmap.h> 85 #include <vm/vm_map.h> 86 #include <vm/vm_object.h> 87 #include <vm/vm_page.h> 88 #include <vm/vm_pageout.h> 89 #include <vm/vm_pager.h> 90 #include <vm/swap_pager.h> 91 #include <vm/vm_kern.h> 92 #include <vm/vm_extern.h> 93 #include <vm/vm_zone.h> 94 95 #define EASY_SCAN_FACTOR 8 96 97 #define MSYNC_FLUSH_HARDSEQ 0x01 98 #define MSYNC_FLUSH_SOFTSEQ 0x02 99 100 static int msync_flush_flags = MSYNC_FLUSH_HARDSEQ | MSYNC_FLUSH_SOFTSEQ; 101 SYSCTL_INT(_vm, OID_AUTO, msync_flush_flags, 102 CTLFLAG_RW, &msync_flush_flags, 0, ""); 103 104 static void vm_object_qcollapse (vm_object_t object); 105 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags); 106 107 /* 108 * Virtual memory objects maintain the actual data 109 * associated with allocated virtual memory. A given 110 * page of memory exists within exactly one object. 111 * 112 * An object is only deallocated when all "references" 113 * are given up. Only one "reference" to a given 114 * region of an object should be writeable. 115 * 116 * Associated with each object is a list of all resident 117 * memory pages belonging to that object; this list is 118 * maintained by the "vm_page" module, and locked by the object's 119 * lock. 120 * 121 * Each object also records a "pager" routine which is 122 * used to retrieve (and store) pages to the proper backing 123 * storage. In addition, objects may be backed by other 124 * objects from which they were virtual-copied. 125 * 126 * The only items within the object structure which are 127 * modified after time of creation are: 128 * reference count locked by object's lock 129 * pager routine locked by object's lock 130 * 131 */ 132 133 struct object_q vm_object_list; 134 static struct lwkt_token vm_object_list_token; 135 static long vm_object_count; /* count of all objects */ 136 vm_object_t kernel_object; 137 vm_object_t kmem_object; 138 static struct vm_object kernel_object_store; 139 static struct vm_object kmem_object_store; 140 extern int vm_pageout_page_count; 141 142 static long object_collapses; 143 static long object_bypasses; 144 static int next_index; 145 static vm_zone_t obj_zone; 146 static struct vm_zone obj_zone_store; 147 static int object_hash_rand; 148 #define VM_OBJECTS_INIT 256 149 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 150 151 void 152 _vm_object_allocate(objtype_t type, vm_size_t size, vm_object_t object) 153 { 154 int incr; 155 TAILQ_INIT(&object->memq); 156 LIST_INIT(&object->shadow_head); 157 158 object->type = type; 159 object->size = size; 160 object->ref_count = 1; 161 object->flags = 0; 162 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 163 vm_object_set_flag(object, OBJ_ONEMAPPING); 164 object->paging_in_progress = 0; 165 object->resident_page_count = 0; 166 object->shadow_count = 0; 167 object->pg_color = next_index; 168 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 169 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 170 else 171 incr = size; 172 next_index = (next_index + incr) & PQ_L2_MASK; 173 object->handle = NULL; 174 object->backing_object = NULL; 175 object->backing_object_offset = (vm_ooffset_t) 0; 176 /* 177 * Try to generate a number that will spread objects out in the 178 * hash table. We 'wipe' new objects across the hash in 128 page 179 * increments plus 1 more to offset it a little more by the time 180 * it wraps around. 181 */ 182 object->hash_rand = object_hash_rand - 129; 183 184 object->generation++; 185 186 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 187 vm_object_count++; 188 object_hash_rand = object->hash_rand; 189 } 190 191 /* 192 * vm_object_init: 193 * 194 * Initialize the VM objects module. 195 */ 196 void 197 vm_object_init(void) 198 { 199 TAILQ_INIT(&vm_object_list); 200 lwkt_token_init(&vm_object_list_token); 201 vm_object_count = 0; 202 203 kernel_object = &kernel_object_store; 204 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), 205 kernel_object); 206 207 kmem_object = &kmem_object_store; 208 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), 209 kmem_object); 210 211 obj_zone = &obj_zone_store; 212 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), 213 vm_objects_init, VM_OBJECTS_INIT); 214 } 215 216 void 217 vm_object_init2(void) 218 { 219 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1); 220 } 221 222 /* 223 * vm_object_allocate: 224 * 225 * Returns a new object with the given size. 226 */ 227 228 vm_object_t 229 vm_object_allocate(objtype_t type, vm_size_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 /* 242 * vm_object_reference: 243 * 244 * Gets another reference to the given object. 245 */ 246 void 247 vm_object_reference(vm_object_t object) 248 { 249 if (object == NULL) 250 return; 251 252 #if 0 253 /* object can be re-referenced during final cleaning */ 254 KASSERT(!(object->flags & OBJ_DEAD), 255 ("vm_object_reference: attempting to reference dead obj")); 256 #endif 257 258 object->ref_count++; 259 if (object->type == OBJT_VNODE) { 260 while (vget((struct vnode *) object->handle, NULL, 261 LK_RETRY|LK_NOOBJ, curthread)) { 262 printf("vm_object_reference: delay in getting object\n"); 263 } 264 } 265 } 266 267 void 268 vm_object_vndeallocate(vm_object_t object) 269 { 270 struct vnode *vp = (struct vnode *) object->handle; 271 272 KASSERT(object->type == OBJT_VNODE, 273 ("vm_object_vndeallocate: not a vnode object")); 274 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 275 #ifdef INVARIANTS 276 if (object->ref_count == 0) { 277 vprint("vm_object_vndeallocate", vp); 278 panic("vm_object_vndeallocate: bad object reference count"); 279 } 280 #endif 281 282 object->ref_count--; 283 if (object->ref_count == 0) { 284 vp->v_flag &= ~VTEXT; 285 vm_object_clear_flag(object, OBJ_OPT); 286 } 287 vrele(vp); 288 } 289 290 /* 291 * vm_object_deallocate: 292 * 293 * Release a reference to the specified object, 294 * gained either through a vm_object_allocate 295 * or a vm_object_reference call. When all references 296 * are gone, storage associated with this object 297 * may be relinquished. 298 * 299 * No object may be locked. 300 */ 301 void 302 vm_object_deallocate(vm_object_t object) 303 { 304 vm_object_t temp; 305 306 while (object != NULL) { 307 308 if (object->type == OBJT_VNODE) { 309 vm_object_vndeallocate(object); 310 return; 311 } 312 313 if (object->ref_count == 0) { 314 panic("vm_object_deallocate: object deallocated too many times: %d", object->type); 315 } else if (object->ref_count > 2) { 316 object->ref_count--; 317 return; 318 } 319 320 /* 321 * Here on ref_count of one or two, which are special cases for 322 * objects. 323 */ 324 if ((object->ref_count == 2) && (object->shadow_count == 0)) { 325 vm_object_set_flag(object, OBJ_ONEMAPPING); 326 object->ref_count--; 327 return; 328 } else if ((object->ref_count == 2) && (object->shadow_count == 1)) { 329 object->ref_count--; 330 if ((object->handle == NULL) && 331 (object->type == OBJT_DEFAULT || 332 object->type == OBJT_SWAP)) { 333 vm_object_t robject; 334 335 robject = LIST_FIRST(&object->shadow_head); 336 KASSERT(robject != NULL, 337 ("vm_object_deallocate: ref_count: %d, shadow_count: %d", 338 object->ref_count, 339 object->shadow_count)); 340 if ((robject->handle == NULL) && 341 (robject->type == OBJT_DEFAULT || 342 robject->type == OBJT_SWAP)) { 343 344 robject->ref_count++; 345 346 while ( 347 robject->paging_in_progress || 348 object->paging_in_progress 349 ) { 350 vm_object_pip_sleep(robject, "objde1"); 351 vm_object_pip_sleep(object, "objde2"); 352 } 353 354 if (robject->ref_count == 1) { 355 robject->ref_count--; 356 object = robject; 357 goto doterm; 358 } 359 360 object = robject; 361 vm_object_collapse(object); 362 continue; 363 } 364 } 365 366 return; 367 368 } else { 369 object->ref_count--; 370 if (object->ref_count != 0) 371 return; 372 } 373 374 doterm: 375 376 temp = object->backing_object; 377 if (temp) { 378 LIST_REMOVE(object, shadow_list); 379 temp->shadow_count--; 380 if (temp->ref_count == 0) 381 vm_object_clear_flag(temp, OBJ_OPT); 382 temp->generation++; 383 object->backing_object = NULL; 384 } 385 386 /* 387 * Don't double-terminate, we could be in a termination 388 * recursion due to the terminate having to sync data 389 * to disk. 390 */ 391 if ((object->flags & OBJ_DEAD) == 0) 392 vm_object_terminate(object); 393 object = temp; 394 } 395 } 396 397 /* 398 * vm_object_terminate actually destroys the specified object, freeing 399 * up all previously used resources. 400 * 401 * The object must be locked. 402 * This routine may block. 403 */ 404 void 405 vm_object_terminate(vm_object_t object) 406 { 407 lwkt_tokref ilock; 408 vm_page_t p; 409 int s; 410 411 /* 412 * Make sure no one uses us. 413 */ 414 vm_object_set_flag(object, OBJ_DEAD); 415 416 /* 417 * wait for the pageout daemon to be done with the object 418 */ 419 vm_object_pip_wait(object, "objtrm"); 420 421 KASSERT(!object->paging_in_progress, 422 ("vm_object_terminate: pageout in progress")); 423 424 /* 425 * Clean and free the pages, as appropriate. All references to the 426 * object are gone, so we don't need to lock it. 427 */ 428 if (object->type == OBJT_VNODE) { 429 struct vnode *vp; 430 431 /* 432 * Freeze optimized copies. 433 */ 434 vm_freeze_copyopts(object, 0, object->size); 435 436 /* 437 * Clean pages and flush buffers. 438 */ 439 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 440 441 vp = (struct vnode *) object->handle; 442 vinvalbuf(vp, V_SAVE, NULL, 0, 0); 443 } 444 445 /* 446 * Wait for any I/O to complete, after which there had better not 447 * be any references left on the object. 448 */ 449 vm_object_pip_wait(object, "objtrm"); 450 451 if (object->ref_count != 0) 452 panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count); 453 454 /* 455 * Now free any remaining pages. For internal objects, this also 456 * removes them from paging queues. Don't free wired pages, just 457 * remove them from the object. 458 */ 459 s = splvm(); 460 while ((p = TAILQ_FIRST(&object->memq)) != NULL) { 461 if (p->busy || (p->flags & PG_BUSY)) 462 panic("vm_object_terminate: freeing busy page %p", p); 463 if (p->wire_count == 0) { 464 vm_page_busy(p); 465 vm_page_free(p); 466 mycpu->gd_cnt.v_pfree++; 467 } else { 468 vm_page_busy(p); 469 vm_page_remove(p); 470 } 471 } 472 splx(s); 473 474 /* 475 * Let the pager know object is dead. 476 */ 477 vm_pager_deallocate(object); 478 479 /* 480 * Remove the object from the global object list. 481 */ 482 lwkt_gettoken(&ilock, &vm_object_list_token); 483 TAILQ_REMOVE(&vm_object_list, object, object_list); 484 lwkt_reltoken(&ilock); 485 486 wakeup(object); 487 488 /* 489 * Free the space for the object. 490 */ 491 zfree(obj_zone, object); 492 } 493 494 /* 495 * vm_object_page_clean 496 * 497 * Clean all dirty pages in the specified range of object. Leaves page 498 * on whatever queue it is currently on. If NOSYNC is set then do not 499 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 500 * leaving the object dirty. 501 * 502 * When stuffing pages asynchronously, allow clustering. XXX we need a 503 * synchronous clustering mode implementation. 504 * 505 * Odd semantics: if start == end, we clean everything. 506 */ 507 508 void 509 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 510 int flags) 511 { 512 vm_page_t p, np; 513 vm_offset_t tstart, tend; 514 vm_pindex_t pi; 515 struct vnode *vp; 516 int clearobjflags; 517 int pagerflags; 518 int curgeneration; 519 lwkt_tokref vlock; 520 int s; 521 522 if (object->type != OBJT_VNODE || 523 (object->flags & OBJ_MIGHTBEDIRTY) == 0) 524 return; 525 526 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 527 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 528 529 vp = object->handle; 530 531 vm_object_set_flag(object, OBJ_CLEANING); 532 533 /* 534 * Handle 'entire object' case 535 */ 536 tstart = start; 537 if (end == 0) { 538 tend = object->size; 539 } else { 540 tend = end; 541 } 542 543 /* 544 * If the caller is smart and only msync()s a range he knows is 545 * dirty, we may be able to avoid an object scan. This results in 546 * a phenominal improvement in performance. We cannot do this 547 * as a matter of course because the object may be huge - e.g. 548 * the size might be in the gigabytes or terrabytes. 549 */ 550 if (msync_flush_flags & MSYNC_FLUSH_HARDSEQ) { 551 vm_offset_t tscan; 552 int scanlimit; 553 int scanreset; 554 555 scanreset = object->resident_page_count / EASY_SCAN_FACTOR; 556 if (scanreset < 16) 557 scanreset = 16; 558 pagerflags |= VM_PAGER_IGNORE_CLEANCHK; 559 560 scanlimit = scanreset; 561 tscan = tstart; 562 563 /* 564 * spl protection is required despite the obj generation 565 * tracking because we cannot safely call vm_page_test_dirty() 566 * or avoid page field tests against an interrupt unbusy/free 567 * race that might occur prior to the busy check in 568 * vm_object_page_collect_flush(). 569 */ 570 s = splvm(); 571 while (tscan < tend) { 572 curgeneration = object->generation; 573 p = vm_page_lookup(object, tscan); 574 if (p == NULL || p->valid == 0 || 575 (p->queue - p->pc) == PQ_CACHE) { 576 if (--scanlimit == 0) 577 break; 578 ++tscan; 579 continue; 580 } 581 vm_page_test_dirty(p); 582 if ((p->dirty & p->valid) == 0) { 583 if (--scanlimit == 0) 584 break; 585 ++tscan; 586 continue; 587 } 588 /* 589 * If we have been asked to skip nosync pages and 590 * this is a nosync page, we can't continue. 591 */ 592 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 593 if (--scanlimit == 0) 594 break; 595 ++tscan; 596 continue; 597 } 598 scanlimit = scanreset; 599 600 /* 601 * This returns 0 if it was unable to busy the first 602 * page (i.e. had to sleep). 603 */ 604 tscan += vm_object_page_collect_flush(object, p, 605 curgeneration, pagerflags); 606 } 607 splx(s); 608 609 /* 610 * If everything was dirty and we flushed it successfully, 611 * and the requested range is not the entire object, we 612 * don't have to mess with CLEANCHK or MIGHTBEDIRTY and can 613 * return immediately. 614 */ 615 if (tscan >= tend && (tstart || tend < object->size)) { 616 vm_object_clear_flag(object, OBJ_CLEANING); 617 return; 618 } 619 pagerflags &= ~VM_PAGER_IGNORE_CLEANCHK; 620 } 621 622 /* 623 * Generally set CLEANCHK interlock and make the page read-only so 624 * we can then clear the object flags. 625 * 626 * However, if this is a nosync mmap then the object is likely to 627 * stay dirty so do not mess with the page and do not clear the 628 * object flags. 629 * 630 * spl protection is required because an interrupt can remove page 631 * from the object. 632 */ 633 clearobjflags = 1; 634 635 s = splvm(); 636 for (p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) { 637 vm_page_flag_set(p, PG_CLEANCHK); 638 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) 639 clearobjflags = 0; 640 else 641 vm_page_protect(p, VM_PROT_READ); 642 } 643 splx(s); 644 645 if (clearobjflags && (tstart == 0) && (tend == object->size)) { 646 struct vnode *vp; 647 648 vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 649 if (object->type == OBJT_VNODE && 650 (vp = (struct vnode *)object->handle) != NULL) { 651 if (vp->v_flag & VOBJDIRTY) { 652 lwkt_gettoken(&vlock, vp->v_interlock); 653 vp->v_flag &= ~VOBJDIRTY; 654 lwkt_reltoken(&vlock); 655 } 656 } 657 } 658 659 /* 660 * spl protection is required both to avoid an interrupt unbusy/free 661 * race against a vm_page_lookup(), and also to ensure that the 662 * memq is consistent. We do not want a busy page to be ripped out 663 * from under us. 664 */ 665 s = splvm(); 666 rescan: 667 splx(s); /* give interrupts a chance */ 668 s = splvm(); 669 curgeneration = object->generation; 670 671 for (p = TAILQ_FIRST(&object->memq); p; p = np) { 672 int n; 673 674 np = TAILQ_NEXT(p, listq); 675 676 again: 677 pi = p->pindex; 678 if (((p->flags & PG_CLEANCHK) == 0) || 679 (pi < tstart) || (pi >= tend) || 680 (p->valid == 0) || 681 ((p->queue - p->pc) == PQ_CACHE)) { 682 vm_page_flag_clear(p, PG_CLEANCHK); 683 continue; 684 } 685 686 vm_page_test_dirty(p); 687 if ((p->dirty & p->valid) == 0) { 688 vm_page_flag_clear(p, PG_CLEANCHK); 689 continue; 690 } 691 692 /* 693 * If we have been asked to skip nosync pages and this is a 694 * nosync page, skip it. Note that the object flags were 695 * not cleared in this case so we do not have to set them. 696 */ 697 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 698 vm_page_flag_clear(p, PG_CLEANCHK); 699 continue; 700 } 701 702 n = vm_object_page_collect_flush(object, p, 703 curgeneration, pagerflags); 704 if (n == 0) 705 goto rescan; 706 if (object->generation != curgeneration) 707 goto rescan; 708 709 /* 710 * Try to optimize the next page. If we can't we pick up 711 * our (random) scan where we left off. 712 */ 713 if (msync_flush_flags & MSYNC_FLUSH_SOFTSEQ) { 714 if ((p = vm_page_lookup(object, pi + n)) != NULL) 715 goto again; 716 } 717 } 718 splx(s); 719 720 #if 0 721 VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc); 722 #endif 723 724 vm_object_clear_flag(object, OBJ_CLEANING); 725 return; 726 } 727 728 /* 729 * This routine must be called at splvm() to properly avoid an interrupt 730 * unbusy/free race that can occur prior to the busy check. 731 * 732 * Using the object generation number here to detect page ripout is not 733 * the best idea in the world. XXX 734 * 735 * NOTE: we operate under the assumption that a page found to not be busy 736 * will not be ripped out from under us by an interrupt. XXX we should 737 * recode this to explicitly busy the pages. 738 */ 739 static int 740 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags) 741 { 742 int runlen; 743 int maxf; 744 int chkb; 745 int maxb; 746 int i; 747 vm_pindex_t pi; 748 vm_page_t maf[vm_pageout_page_count]; 749 vm_page_t mab[vm_pageout_page_count]; 750 vm_page_t ma[vm_pageout_page_count]; 751 752 pi = p->pindex; 753 while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { 754 if (object->generation != curgeneration) { 755 return(0); 756 } 757 } 758 759 maxf = 0; 760 for(i = 1; i < vm_pageout_page_count; i++) { 761 vm_page_t tp; 762 763 if ((tp = vm_page_lookup(object, pi + i)) != NULL) { 764 if ((tp->flags & PG_BUSY) || 765 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 766 (tp->flags & PG_CLEANCHK) == 0) || 767 (tp->busy != 0)) 768 break; 769 if((tp->queue - tp->pc) == PQ_CACHE) { 770 vm_page_flag_clear(tp, PG_CLEANCHK); 771 break; 772 } 773 vm_page_test_dirty(tp); 774 if ((tp->dirty & tp->valid) == 0) { 775 vm_page_flag_clear(tp, PG_CLEANCHK); 776 break; 777 } 778 maf[ i - 1 ] = tp; 779 maxf++; 780 continue; 781 } 782 break; 783 } 784 785 maxb = 0; 786 chkb = vm_pageout_page_count - maxf; 787 if (chkb) { 788 for(i = 1; i < chkb;i++) { 789 vm_page_t tp; 790 791 if ((tp = vm_page_lookup(object, pi - i)) != NULL) { 792 if ((tp->flags & PG_BUSY) || 793 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 794 (tp->flags & PG_CLEANCHK) == 0) || 795 (tp->busy != 0)) 796 break; 797 if((tp->queue - tp->pc) == PQ_CACHE) { 798 vm_page_flag_clear(tp, PG_CLEANCHK); 799 break; 800 } 801 vm_page_test_dirty(tp); 802 if ((tp->dirty & tp->valid) == 0) { 803 vm_page_flag_clear(tp, PG_CLEANCHK); 804 break; 805 } 806 mab[ i - 1 ] = tp; 807 maxb++; 808 continue; 809 } 810 break; 811 } 812 } 813 814 for(i = 0; i < maxb; i++) { 815 int index = (maxb - i) - 1; 816 ma[index] = mab[i]; 817 vm_page_flag_clear(ma[index], PG_CLEANCHK); 818 } 819 vm_page_flag_clear(p, PG_CLEANCHK); 820 ma[maxb] = p; 821 for(i = 0; i < maxf; i++) { 822 int index = (maxb + i) + 1; 823 ma[index] = maf[i]; 824 vm_page_flag_clear(ma[index], PG_CLEANCHK); 825 } 826 runlen = maxb + maxf + 1; 827 828 vm_pageout_flush(ma, runlen, pagerflags); 829 for (i = 0; i < runlen; i++) { 830 if (ma[i]->valid & ma[i]->dirty) { 831 vm_page_protect(ma[i], VM_PROT_READ); 832 vm_page_flag_set(ma[i], PG_CLEANCHK); 833 834 /* 835 * maxf will end up being the actual number of pages 836 * we wrote out contiguously, non-inclusive of the 837 * first page. We do not count look-behind pages. 838 */ 839 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 840 maxf = i - maxb - 1; 841 } 842 } 843 return(maxf + 1); 844 } 845 846 #ifdef not_used 847 /* XXX I cannot tell if this should be an exported symbol */ 848 /* 849 * vm_object_deactivate_pages 850 * 851 * Deactivate all pages in the specified object. (Keep its pages 852 * in memory even though it is no longer referenced.) 853 * 854 * The object must be locked. 855 */ 856 static void 857 vm_object_deactivate_pages(vm_object_t object) 858 { 859 vm_page_t p, next; 860 int s; 861 862 s = splvm(); 863 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { 864 next = TAILQ_NEXT(p, listq); 865 vm_page_deactivate(p); 866 } 867 splx(s); 868 } 869 #endif 870 871 /* 872 * Same as vm_object_pmap_copy, except range checking really 873 * works, and is meant for small sections of an object. 874 * 875 * This code protects resident pages by making them read-only 876 * and is typically called on a fork or split when a page 877 * is converted to copy-on-write. 878 * 879 * NOTE: If the page is already at VM_PROT_NONE, calling 880 * vm_page_protect will have no effect. 881 */ 882 void 883 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 884 { 885 vm_pindex_t idx; 886 vm_page_t p; 887 int s; 888 889 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 890 return; 891 892 /* 893 * spl protection needed to prevent races between the lookup, 894 * an interrupt unbusy/free, and our protect call. 895 */ 896 s = splvm(); 897 for (idx = start; idx < end; idx++) { 898 p = vm_page_lookup(object, idx); 899 if (p == NULL) 900 continue; 901 vm_page_protect(p, VM_PROT_READ); 902 } 903 splx(s); 904 } 905 906 /* 907 * vm_object_pmap_remove: 908 * 909 * Removes all physical pages in the specified 910 * object range from all physical maps. 911 * 912 * The object must *not* be locked. 913 */ 914 void 915 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 916 { 917 vm_page_t p; 918 int s; 919 920 if (object == NULL) 921 return; 922 923 /* 924 * spl protection is required because an interrupt can unbusy/free 925 * a page. 926 */ 927 s = splvm(); 928 for (p = TAILQ_FIRST(&object->memq); 929 p != NULL; 930 p = TAILQ_NEXT(p, listq) 931 ) { 932 if (p->pindex >= start && p->pindex < end) 933 vm_page_protect(p, VM_PROT_NONE); 934 } 935 splx(s); 936 if ((start == 0) && (object->size == end)) 937 vm_object_clear_flag(object, OBJ_WRITEABLE); 938 } 939 940 /* 941 * vm_object_madvise: 942 * 943 * Implements the madvise function at the object/page level. 944 * 945 * MADV_WILLNEED (any object) 946 * 947 * Activate the specified pages if they are resident. 948 * 949 * MADV_DONTNEED (any object) 950 * 951 * Deactivate the specified pages if they are resident. 952 * 953 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, 954 * OBJ_ONEMAPPING only) 955 * 956 * Deactivate and clean the specified pages if they are 957 * resident. This permits the process to reuse the pages 958 * without faulting or the kernel to reclaim the pages 959 * without I/O. 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 int s; 968 969 if (object == NULL) 970 return; 971 972 end = pindex + count; 973 974 /* 975 * Locate and adjust resident pages 976 */ 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 s = splvm(); 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 splx(s); 1014 tobject = tobject->backing_object; 1015 if (tobject == NULL) 1016 continue; 1017 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 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 splx(s); 1034 continue; 1035 } 1036 1037 if (vm_page_sleep_busy(m, TRUE, "madvpo")) { 1038 splx(s); 1039 goto relookup; 1040 } 1041 splx(s); 1042 1043 /* 1044 * Theoretically once a page is known not to be busy, an 1045 * interrupt cannot come along and rip it out from under us. 1046 */ 1047 1048 if (advise == MADV_WILLNEED) { 1049 vm_page_activate(m); 1050 } else if (advise == MADV_DONTNEED) { 1051 vm_page_dontneed(m); 1052 } else if (advise == MADV_FREE) { 1053 /* 1054 * Mark the page clean. This will allow the page 1055 * to be freed up by the system. However, such pages 1056 * are often reused quickly by malloc()/free() 1057 * so we do not do anything that would cause 1058 * a page fault if we can help it. 1059 * 1060 * Specifically, we do not try to actually free 1061 * the page now nor do we try to put it in the 1062 * cache (which would cause a page fault on reuse). 1063 * 1064 * But we do make the page is freeable as we 1065 * can without actually taking the step of unmapping 1066 * it. 1067 */ 1068 pmap_clear_modify(m); 1069 m->dirty = 0; 1070 m->act_count = 0; 1071 vm_page_dontneed(m); 1072 if (tobject->type == OBJT_SWAP) 1073 swap_pager_freespace(tobject, tpindex, 1); 1074 } 1075 } 1076 } 1077 1078 /* 1079 * vm_object_shadow: 1080 * 1081 * Create a new object which is backed by the 1082 * specified existing object range. The source 1083 * object reference is deallocated. 1084 * 1085 * The new object and offset into that object 1086 * are returned in the source parameters. 1087 */ 1088 1089 void 1090 vm_object_shadow(vm_object_t *object, /* IN/OUT */ 1091 vm_ooffset_t *offset, /* IN/OUT */ 1092 vm_size_t length) 1093 { 1094 vm_object_t source; 1095 vm_object_t result; 1096 1097 source = *object; 1098 1099 /* 1100 * Don't create the new object if the old object isn't shared. 1101 */ 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 return; 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 1140 result->backing_object_offset = *offset; 1141 1142 /* 1143 * Return the new things 1144 */ 1145 1146 *offset = 0; 1147 *object = result; 1148 } 1149 1150 #define OBSC_TEST_ALL_SHADOWED 0x0001 1151 #define OBSC_COLLAPSE_NOWAIT 0x0002 1152 #define OBSC_COLLAPSE_WAIT 0x0004 1153 1154 static __inline int 1155 vm_object_backing_scan(vm_object_t object, int op) 1156 { 1157 int s; 1158 int r = 1; 1159 vm_page_t p; 1160 vm_object_t backing_object; 1161 vm_pindex_t backing_offset_index; 1162 1163 /* 1164 * spl protection is required to avoid races between the memq/lookup, 1165 * an interrupt doing an unbusy/free, and our busy check. Amoung 1166 * other things. 1167 */ 1168 s = splvm(); 1169 1170 backing_object = object->backing_object; 1171 backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1172 1173 /* 1174 * Initial conditions 1175 */ 1176 1177 if (op & OBSC_TEST_ALL_SHADOWED) { 1178 /* 1179 * We do not want to have to test for the existence of 1180 * swap pages in the backing object. XXX but with the 1181 * new swapper this would be pretty easy to do. 1182 * 1183 * XXX what about anonymous MAP_SHARED memory that hasn't 1184 * been ZFOD faulted yet? If we do not test for this, the 1185 * shadow test may succeed! XXX 1186 */ 1187 if (backing_object->type != OBJT_DEFAULT) { 1188 splx(s); 1189 return(0); 1190 } 1191 } 1192 if (op & OBSC_COLLAPSE_WAIT) { 1193 vm_object_set_flag(backing_object, OBJ_DEAD); 1194 } 1195 1196 /* 1197 * Our scan 1198 */ 1199 1200 p = TAILQ_FIRST(&backing_object->memq); 1201 while (p) { 1202 vm_page_t next = TAILQ_NEXT(p, listq); 1203 vm_pindex_t new_pindex = p->pindex - backing_offset_index; 1204 1205 if (op & OBSC_TEST_ALL_SHADOWED) { 1206 vm_page_t pp; 1207 1208 /* 1209 * Ignore pages outside the parent object's range 1210 * and outside the parent object's mapping of the 1211 * backing object. 1212 * 1213 * note that we do not busy the backing object's 1214 * page. 1215 */ 1216 1217 if ( 1218 p->pindex < backing_offset_index || 1219 new_pindex >= object->size 1220 ) { 1221 p = next; 1222 continue; 1223 } 1224 1225 /* 1226 * See if the parent has the page or if the parent's 1227 * object pager has the page. If the parent has the 1228 * page but the page is not valid, the parent's 1229 * object pager must have the page. 1230 * 1231 * If this fails, the parent does not completely shadow 1232 * the object and we might as well give up now. 1233 */ 1234 1235 pp = vm_page_lookup(object, new_pindex); 1236 if ( 1237 (pp == NULL || pp->valid == 0) && 1238 !vm_pager_has_page(object, new_pindex, NULL, NULL) 1239 ) { 1240 r = 0; 1241 break; 1242 } 1243 } 1244 1245 /* 1246 * Check for busy page 1247 */ 1248 1249 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1250 vm_page_t pp; 1251 1252 if (op & OBSC_COLLAPSE_NOWAIT) { 1253 if ( 1254 (p->flags & PG_BUSY) || 1255 !p->valid || 1256 p->hold_count || 1257 p->wire_count || 1258 p->busy 1259 ) { 1260 p = next; 1261 continue; 1262 } 1263 } else if (op & OBSC_COLLAPSE_WAIT) { 1264 if (vm_page_sleep_busy(p, TRUE, "vmocol")) { 1265 /* 1266 * If we slept, anything could have 1267 * happened. Since the object is 1268 * marked dead, the backing offset 1269 * should not have changed so we 1270 * just restart our scan. 1271 */ 1272 p = TAILQ_FIRST(&backing_object->memq); 1273 continue; 1274 } 1275 } 1276 1277 /* 1278 * Busy the page 1279 */ 1280 vm_page_busy(p); 1281 1282 KASSERT( 1283 p->object == backing_object, 1284 ("vm_object_qcollapse(): object mismatch") 1285 ); 1286 1287 /* 1288 * Destroy any associated swap 1289 */ 1290 if (backing_object->type == OBJT_SWAP) { 1291 swap_pager_freespace( 1292 backing_object, 1293 p->pindex, 1294 1 1295 ); 1296 } 1297 1298 if ( 1299 p->pindex < backing_offset_index || 1300 new_pindex >= object->size 1301 ) { 1302 /* 1303 * Page is out of the parent object's range, we 1304 * can simply destroy it. 1305 */ 1306 vm_page_protect(p, VM_PROT_NONE); 1307 vm_page_free(p); 1308 p = next; 1309 continue; 1310 } 1311 1312 pp = vm_page_lookup(object, new_pindex); 1313 if ( 1314 pp != NULL || 1315 vm_pager_has_page(object, new_pindex, NULL, NULL) 1316 ) { 1317 /* 1318 * page already exists in parent OR swap exists 1319 * for this location in the parent. Destroy 1320 * the original page from the backing object. 1321 * 1322 * Leave the parent's page alone 1323 */ 1324 vm_page_protect(p, VM_PROT_NONE); 1325 vm_page_free(p); 1326 p = next; 1327 continue; 1328 } 1329 1330 /* 1331 * Page does not exist in parent, rename the 1332 * page from the backing object to the main object. 1333 * 1334 * If the page was mapped to a process, it can remain 1335 * mapped through the rename. 1336 */ 1337 if ((p->queue - p->pc) == PQ_CACHE) 1338 vm_page_deactivate(p); 1339 1340 vm_page_rename(p, object, new_pindex); 1341 /* page automatically made dirty by rename */ 1342 } 1343 p = next; 1344 } 1345 splx(s); 1346 return(r); 1347 } 1348 1349 1350 /* 1351 * this version of collapse allows the operation to occur earlier and 1352 * when paging_in_progress is true for an object... This is not a complete 1353 * operation, but should plug 99.9% of the rest of the leaks. 1354 */ 1355 static void 1356 vm_object_qcollapse(vm_object_t object) 1357 { 1358 vm_object_t backing_object = object->backing_object; 1359 1360 if (backing_object->ref_count != 1) 1361 return; 1362 1363 backing_object->ref_count += 2; 1364 1365 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 1366 1367 backing_object->ref_count -= 2; 1368 } 1369 1370 /* 1371 * vm_object_collapse: 1372 * 1373 * Collapse an object with the object backing it. 1374 * Pages in the backing object are moved into the 1375 * parent, and the backing object is deallocated. 1376 */ 1377 void 1378 vm_object_collapse(vm_object_t object) 1379 { 1380 while (TRUE) { 1381 vm_object_t backing_object; 1382 1383 /* 1384 * Verify that the conditions are right for collapse: 1385 * 1386 * The object exists and the backing object exists. 1387 */ 1388 if (object == NULL) 1389 break; 1390 1391 if ((backing_object = object->backing_object) == NULL) 1392 break; 1393 1394 /* 1395 * we check the backing object first, because it is most likely 1396 * not collapsable. 1397 */ 1398 if (backing_object->handle != NULL || 1399 (backing_object->type != OBJT_DEFAULT && 1400 backing_object->type != OBJT_SWAP) || 1401 (backing_object->flags & OBJ_DEAD) || 1402 object->handle != NULL || 1403 (object->type != OBJT_DEFAULT && 1404 object->type != OBJT_SWAP) || 1405 (object->flags & OBJ_DEAD)) { 1406 break; 1407 } 1408 1409 if ( 1410 object->paging_in_progress != 0 || 1411 backing_object->paging_in_progress != 0 1412 ) { 1413 vm_object_qcollapse(object); 1414 break; 1415 } 1416 1417 /* 1418 * We know that we can either collapse the backing object (if 1419 * the parent is the only reference to it) or (perhaps) have 1420 * the parent bypass the object if the parent happens to shadow 1421 * all the resident pages in the entire backing object. 1422 * 1423 * This is ignoring pager-backed pages such as swap pages. 1424 * vm_object_backing_scan fails the shadowing test in this 1425 * case. 1426 */ 1427 1428 if (backing_object->ref_count == 1) { 1429 /* 1430 * If there is exactly one reference to the backing 1431 * object, we can collapse it into the parent. 1432 */ 1433 1434 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); 1435 1436 /* 1437 * Move the pager from backing_object to object. 1438 */ 1439 1440 if (backing_object->type == OBJT_SWAP) { 1441 vm_object_pip_add(backing_object, 1); 1442 1443 /* 1444 * scrap the paging_offset junk and do a 1445 * discrete copy. This also removes major 1446 * assumptions about how the swap-pager 1447 * works from where it doesn't belong. The 1448 * new swapper is able to optimize the 1449 * destroy-source case. 1450 */ 1451 1452 vm_object_pip_add(object, 1); 1453 swap_pager_copy( 1454 backing_object, 1455 object, 1456 OFF_TO_IDX(object->backing_object_offset), TRUE); 1457 vm_object_pip_wakeup(object); 1458 1459 vm_object_pip_wakeup(backing_object); 1460 } 1461 /* 1462 * Object now shadows whatever backing_object did. 1463 * Note that the reference to 1464 * backing_object->backing_object moves from within 1465 * backing_object to within object. 1466 */ 1467 1468 LIST_REMOVE(object, shadow_list); 1469 object->backing_object->shadow_count--; 1470 object->backing_object->generation++; 1471 if (backing_object->backing_object) { 1472 LIST_REMOVE(backing_object, shadow_list); 1473 backing_object->backing_object->shadow_count--; 1474 backing_object->backing_object->generation++; 1475 } 1476 object->backing_object = backing_object->backing_object; 1477 if (object->backing_object) { 1478 LIST_INSERT_HEAD( 1479 &object->backing_object->shadow_head, 1480 object, 1481 shadow_list 1482 ); 1483 object->backing_object->shadow_count++; 1484 object->backing_object->generation++; 1485 } 1486 1487 object->backing_object_offset += 1488 backing_object->backing_object_offset; 1489 1490 /* 1491 * Discard backing_object. 1492 * 1493 * Since the backing object has no pages, no pager left, 1494 * and no object references within it, all that is 1495 * necessary is to dispose of it. 1496 */ 1497 1498 KASSERT(backing_object->ref_count == 1, ("backing_object %p was somehow re-referenced during collapse!", backing_object)); 1499 KASSERT(TAILQ_FIRST(&backing_object->memq) == NULL, ("backing_object %p somehow has left over pages during collapse!", backing_object)); 1500 TAILQ_REMOVE( 1501 &vm_object_list, 1502 backing_object, 1503 object_list 1504 ); 1505 vm_object_count--; 1506 1507 zfree(obj_zone, backing_object); 1508 1509 object_collapses++; 1510 } else { 1511 vm_object_t new_backing_object; 1512 1513 /* 1514 * If we do not entirely shadow the backing object, 1515 * there is nothing we can do so we give up. 1516 */ 1517 1518 if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) { 1519 break; 1520 } 1521 1522 /* 1523 * Make the parent shadow the next object in the 1524 * chain. Deallocating backing_object will not remove 1525 * it, since its reference count is at least 2. 1526 */ 1527 1528 LIST_REMOVE(object, shadow_list); 1529 backing_object->shadow_count--; 1530 backing_object->generation++; 1531 1532 new_backing_object = backing_object->backing_object; 1533 if ((object->backing_object = new_backing_object) != NULL) { 1534 vm_object_reference(new_backing_object); 1535 LIST_INSERT_HEAD( 1536 &new_backing_object->shadow_head, 1537 object, 1538 shadow_list 1539 ); 1540 new_backing_object->shadow_count++; 1541 new_backing_object->generation++; 1542 object->backing_object_offset += 1543 backing_object->backing_object_offset; 1544 } 1545 1546 /* 1547 * Drop the reference count on backing_object. Since 1548 * its ref_count was at least 2, it will not vanish; 1549 * so we don't need to call vm_object_deallocate, but 1550 * we do anyway. 1551 */ 1552 vm_object_deallocate(backing_object); 1553 object_bypasses++; 1554 } 1555 1556 /* 1557 * Try again with this object's new backing object. 1558 */ 1559 } 1560 } 1561 1562 /* 1563 * vm_object_page_remove: [internal] 1564 * 1565 * Removes all physical pages in the specified 1566 * object range from the object's list of pages. 1567 */ 1568 void 1569 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 1570 boolean_t clean_only) 1571 { 1572 vm_page_t p, next; 1573 unsigned int size; 1574 int all; 1575 int s; 1576 1577 if (object == NULL || object->resident_page_count == 0) 1578 return; 1579 1580 all = ((end == 0) && (start == 0)); 1581 1582 /* 1583 * Since physically-backed objects do not use managed pages, we can't 1584 * remove pages from the object (we must instead remove the page 1585 * references, and then destroy the object). 1586 */ 1587 KASSERT(object->type != OBJT_PHYS, 1588 ("attempt to remove pages from a physical object")); 1589 1590 /* 1591 * Indicating that the object is undergoing paging. 1592 * 1593 * spl protection is required to avoid a race between the memq scan, 1594 * an interrupt unbusy/free, and the busy check. 1595 */ 1596 vm_object_pip_add(object, 1); 1597 s = splvm(); 1598 again: 1599 size = end - start; 1600 if (all || size > object->resident_page_count / 4) { 1601 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { 1602 next = TAILQ_NEXT(p, listq); 1603 if (all || ((start <= p->pindex) && (p->pindex < end))) { 1604 if (p->wire_count != 0) { 1605 vm_page_protect(p, VM_PROT_NONE); 1606 if (!clean_only) 1607 p->valid = 0; 1608 continue; 1609 } 1610 1611 /* 1612 * The busy flags are only cleared at 1613 * interrupt -- minimize the spl transitions 1614 */ 1615 1616 if (vm_page_sleep_busy(p, TRUE, "vmopar")) 1617 goto again; 1618 1619 if (clean_only && p->valid) { 1620 vm_page_test_dirty(p); 1621 if (p->valid & p->dirty) 1622 continue; 1623 } 1624 1625 vm_page_busy(p); 1626 vm_page_protect(p, VM_PROT_NONE); 1627 vm_page_free(p); 1628 } 1629 } 1630 } else { 1631 while (size > 0) { 1632 if ((p = vm_page_lookup(object, start)) != 0) { 1633 if (p->wire_count != 0) { 1634 vm_page_protect(p, VM_PROT_NONE); 1635 if (!clean_only) 1636 p->valid = 0; 1637 start += 1; 1638 size -= 1; 1639 continue; 1640 } 1641 1642 /* 1643 * The busy flags are only cleared at 1644 * interrupt -- minimize the spl transitions 1645 */ 1646 if (vm_page_sleep_busy(p, TRUE, "vmopar")) 1647 goto again; 1648 1649 if (clean_only && p->valid) { 1650 vm_page_test_dirty(p); 1651 if (p->valid & p->dirty) { 1652 start += 1; 1653 size -= 1; 1654 continue; 1655 } 1656 } 1657 1658 vm_page_busy(p); 1659 vm_page_protect(p, VM_PROT_NONE); 1660 vm_page_free(p); 1661 } 1662 start += 1; 1663 size -= 1; 1664 } 1665 } 1666 splx(s); 1667 vm_object_pip_wakeup(object); 1668 } 1669 1670 /* 1671 * Routine: vm_object_coalesce 1672 * Function: Coalesces two objects backing up adjoining 1673 * regions of memory into a single object. 1674 * 1675 * returns TRUE if objects were combined. 1676 * 1677 * NOTE: Only works at the moment if the second object is NULL - 1678 * if it's not, which object do we lock first? 1679 * 1680 * Parameters: 1681 * prev_object First object to coalesce 1682 * prev_offset Offset into prev_object 1683 * next_object Second object into coalesce 1684 * next_offset Offset into next_object 1685 * 1686 * prev_size Size of reference to prev_object 1687 * next_size Size of reference to next_object 1688 * 1689 * Conditions: 1690 * The object must *not* be locked. 1691 */ 1692 boolean_t 1693 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 1694 vm_size_t prev_size, vm_size_t next_size) 1695 { 1696 vm_pindex_t next_pindex; 1697 1698 if (prev_object == NULL) { 1699 return (TRUE); 1700 } 1701 1702 if (prev_object->type != OBJT_DEFAULT && 1703 prev_object->type != OBJT_SWAP) { 1704 return (FALSE); 1705 } 1706 1707 /* 1708 * Try to collapse the object first 1709 */ 1710 vm_object_collapse(prev_object); 1711 1712 /* 1713 * Can't coalesce if: . more than one reference . paged out . shadows 1714 * another object . has a copy elsewhere (any of which mean that the 1715 * pages not mapped to prev_entry may be in use anyway) 1716 */ 1717 1718 if (prev_object->backing_object != NULL) { 1719 return (FALSE); 1720 } 1721 1722 prev_size >>= PAGE_SHIFT; 1723 next_size >>= PAGE_SHIFT; 1724 next_pindex = prev_pindex + prev_size; 1725 1726 if ((prev_object->ref_count > 1) && 1727 (prev_object->size != next_pindex)) { 1728 return (FALSE); 1729 } 1730 1731 /* 1732 * Remove any pages that may still be in the object from a previous 1733 * deallocation. 1734 */ 1735 if (next_pindex < prev_object->size) { 1736 vm_object_page_remove(prev_object, 1737 next_pindex, 1738 next_pindex + next_size, FALSE); 1739 if (prev_object->type == OBJT_SWAP) 1740 swap_pager_freespace(prev_object, 1741 next_pindex, next_size); 1742 } 1743 1744 /* 1745 * Extend the object if necessary. 1746 */ 1747 if (next_pindex + next_size > prev_object->size) 1748 prev_object->size = next_pindex + next_size; 1749 1750 return (TRUE); 1751 } 1752 1753 void 1754 vm_object_set_writeable_dirty(vm_object_t object) 1755 { 1756 struct vnode *vp; 1757 lwkt_tokref vlock; 1758 1759 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1760 if (object->type == OBJT_VNODE && 1761 (vp = (struct vnode *)object->handle) != NULL) { 1762 if ((vp->v_flag & VOBJDIRTY) == 0) { 1763 lwkt_gettoken(&vlock, vp->v_interlock); 1764 vp->v_flag |= VOBJDIRTY; 1765 lwkt_reltoken(&vlock); 1766 } 1767 } 1768 } 1769 1770 1771 1772 #include "opt_ddb.h" 1773 #ifdef DDB 1774 #include <sys/kernel.h> 1775 1776 #include <sys/cons.h> 1777 1778 #include <ddb/ddb.h> 1779 1780 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 1781 vm_map_entry_t entry); 1782 static int vm_object_in_map (vm_object_t object); 1783 1784 static int 1785 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 1786 { 1787 vm_map_t tmpm; 1788 vm_map_entry_t tmpe; 1789 vm_object_t obj; 1790 int entcount; 1791 1792 if (map == 0) 1793 return 0; 1794 1795 if (entry == 0) { 1796 tmpe = map->header.next; 1797 entcount = map->nentries; 1798 while (entcount-- && (tmpe != &map->header)) { 1799 if( _vm_object_in_map(map, object, tmpe)) { 1800 return 1; 1801 } 1802 tmpe = tmpe->next; 1803 } 1804 } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) { 1805 tmpm = entry->object.sub_map; 1806 tmpe = tmpm->header.next; 1807 entcount = tmpm->nentries; 1808 while (entcount-- && tmpe != &tmpm->header) { 1809 if( _vm_object_in_map(tmpm, object, tmpe)) { 1810 return 1; 1811 } 1812 tmpe = tmpe->next; 1813 } 1814 } else if ((obj = entry->object.vm_object) != NULL) { 1815 for(; obj; obj=obj->backing_object) 1816 if( obj == object) { 1817 return 1; 1818 } 1819 } 1820 return 0; 1821 } 1822 1823 static int 1824 vm_object_in_map(vm_object_t object) 1825 { 1826 struct proc *p; 1827 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1828 if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */) 1829 continue; 1830 if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) 1831 return 1; 1832 } 1833 if( _vm_object_in_map( kernel_map, object, 0)) 1834 return 1; 1835 if( _vm_object_in_map( pager_map, object, 0)) 1836 return 1; 1837 if( _vm_object_in_map( buffer_map, object, 0)) 1838 return 1; 1839 if( _vm_object_in_map( mb_map, object, 0)) 1840 return 1; 1841 return 0; 1842 } 1843 1844 DB_SHOW_COMMAND(vmochk, vm_object_check) 1845 { 1846 vm_object_t object; 1847 1848 /* 1849 * make sure that internal objs are in a map somewhere 1850 * and none have zero ref counts. 1851 */ 1852 for (object = TAILQ_FIRST(&vm_object_list); 1853 object != NULL; 1854 object = TAILQ_NEXT(object, object_list)) { 1855 if (object->handle == NULL && 1856 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 1857 if (object->ref_count == 0) { 1858 db_printf("vmochk: internal obj has zero ref count: %ld\n", 1859 (long)object->size); 1860 } 1861 if (!vm_object_in_map(object)) { 1862 db_printf( 1863 "vmochk: internal obj is not in a map: " 1864 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 1865 object->ref_count, (u_long)object->size, 1866 (u_long)object->size, 1867 (void *)object->backing_object); 1868 } 1869 } 1870 } 1871 } 1872 1873 /* 1874 * vm_object_print: [ debug ] 1875 */ 1876 DB_SHOW_COMMAND(object, vm_object_print_static) 1877 { 1878 /* XXX convert args. */ 1879 vm_object_t object = (vm_object_t)addr; 1880 boolean_t full = have_addr; 1881 1882 vm_page_t p; 1883 1884 /* XXX count is an (unused) arg. Avoid shadowing it. */ 1885 #define count was_count 1886 1887 int count; 1888 1889 if (object == NULL) 1890 return; 1891 1892 db_iprintf( 1893 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 1894 object, (int)object->type, (u_long)object->size, 1895 object->resident_page_count, object->ref_count, object->flags); 1896 /* 1897 * XXX no %qd in kernel. Truncate object->backing_object_offset. 1898 */ 1899 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 1900 object->shadow_count, 1901 object->backing_object ? object->backing_object->ref_count : 0, 1902 object->backing_object, (long)object->backing_object_offset); 1903 1904 if (!full) 1905 return; 1906 1907 db_indent += 2; 1908 count = 0; 1909 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) { 1910 if (count == 0) 1911 db_iprintf("memory:="); 1912 else if (count == 6) { 1913 db_printf("\n"); 1914 db_iprintf(" ..."); 1915 count = 0; 1916 } else 1917 db_printf(","); 1918 count++; 1919 1920 db_printf("(off=0x%lx,page=0x%lx)", 1921 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 1922 } 1923 if (count != 0) 1924 db_printf("\n"); 1925 db_indent -= 2; 1926 } 1927 1928 /* XXX. */ 1929 #undef count 1930 1931 /* XXX need this non-static entry for calling from vm_map_print. */ 1932 void 1933 vm_object_print(/* db_expr_t */ long addr, 1934 boolean_t have_addr, 1935 /* db_expr_t */ long count, 1936 char *modif) 1937 { 1938 vm_object_print_static(addr, have_addr, count, modif); 1939 } 1940 1941 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 1942 { 1943 vm_object_t object; 1944 int nl = 0; 1945 int c; 1946 for (object = TAILQ_FIRST(&vm_object_list); 1947 object != NULL; 1948 object = TAILQ_NEXT(object, object_list)) { 1949 vm_pindex_t idx, fidx; 1950 vm_pindex_t osize; 1951 vm_paddr_t pa = -1, padiff; 1952 int rcount; 1953 vm_page_t m; 1954 1955 db_printf("new object: %p\n", (void *)object); 1956 if ( nl > 18) { 1957 c = cngetc(); 1958 if (c != ' ') 1959 return; 1960 nl = 0; 1961 } 1962 nl++; 1963 rcount = 0; 1964 fidx = 0; 1965 osize = object->size; 1966 if (osize > 128) 1967 osize = 128; 1968 for (idx = 0; idx < osize; idx++) { 1969 m = vm_page_lookup(object, idx); 1970 if (m == NULL) { 1971 if (rcount) { 1972 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 1973 (long)fidx, rcount, (long)pa); 1974 if ( nl > 18) { 1975 c = cngetc(); 1976 if (c != ' ') 1977 return; 1978 nl = 0; 1979 } 1980 nl++; 1981 rcount = 0; 1982 } 1983 continue; 1984 } 1985 1986 1987 if (rcount && 1988 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 1989 ++rcount; 1990 continue; 1991 } 1992 if (rcount) { 1993 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 1994 padiff >>= PAGE_SHIFT; 1995 padiff &= PQ_L2_MASK; 1996 if (padiff == 0) { 1997 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 1998 ++rcount; 1999 continue; 2000 } 2001 db_printf(" index(%ld)run(%d)pa(0x%lx)", 2002 (long)fidx, rcount, (long)pa); 2003 db_printf("pd(%ld)\n", (long)padiff); 2004 if ( nl > 18) { 2005 c = cngetc(); 2006 if (c != ' ') 2007 return; 2008 nl = 0; 2009 } 2010 nl++; 2011 } 2012 fidx = idx; 2013 pa = VM_PAGE_TO_PHYS(m); 2014 rcount = 1; 2015 } 2016 if (rcount) { 2017 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2018 (long)fidx, rcount, (long)pa); 2019 if ( nl > 18) { 2020 c = cngetc(); 2021 if (c != ' ') 2022 return; 2023 nl = 0; 2024 } 2025 nl++; 2026 } 2027 } 2028 } 2029 #endif /* DDB */ 2030