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 1.21 2004/11/12 00:09:56 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 #include <sys/thread2.h> 96 97 #define EASY_SCAN_FACTOR 8 98 99 #define MSYNC_FLUSH_HARDSEQ 0x01 100 #define MSYNC_FLUSH_SOFTSEQ 0x02 101 102 static int msync_flush_flags = MSYNC_FLUSH_HARDSEQ | MSYNC_FLUSH_SOFTSEQ; 103 SYSCTL_INT(_vm, OID_AUTO, msync_flush_flags, 104 CTLFLAG_RW, &msync_flush_flags, 0, ""); 105 106 static void vm_object_qcollapse (vm_object_t object); 107 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags); 108 109 /* 110 * Virtual memory objects maintain the actual data 111 * associated with allocated virtual memory. A given 112 * page of memory exists within exactly one object. 113 * 114 * An object is only deallocated when all "references" 115 * are given up. Only one "reference" to a given 116 * region of an object should be writeable. 117 * 118 * Associated with each object is a list of all resident 119 * memory pages belonging to that object; this list is 120 * maintained by the "vm_page" module, and locked by the object's 121 * lock. 122 * 123 * Each object also records a "pager" routine which is 124 * used to retrieve (and store) pages to the proper backing 125 * storage. In addition, objects may be backed by other 126 * objects from which they were virtual-copied. 127 * 128 * The only items within the object structure which are 129 * modified after time of creation are: 130 * reference count locked by object's lock 131 * pager routine locked by object's lock 132 * 133 */ 134 135 struct object_q vm_object_list; 136 static long vm_object_count; /* count of all objects */ 137 vm_object_t kernel_object; 138 vm_object_t kmem_object; 139 static struct vm_object kernel_object_store; 140 static struct vm_object kmem_object_store; 141 extern int vm_pageout_page_count; 142 143 static long object_collapses; 144 static long object_bypasses; 145 static int next_index; 146 static vm_zone_t obj_zone; 147 static struct vm_zone obj_zone_store; 148 static int object_hash_rand; 149 #define VM_OBJECTS_INIT 256 150 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; 151 152 void 153 _vm_object_allocate(objtype_t type, vm_size_t size, vm_object_t object) 154 { 155 int incr; 156 TAILQ_INIT(&object->memq); 157 LIST_INIT(&object->shadow_head); 158 159 object->type = type; 160 object->size = size; 161 object->ref_count = 1; 162 object->flags = 0; 163 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) 164 vm_object_set_flag(object, OBJ_ONEMAPPING); 165 object->paging_in_progress = 0; 166 object->resident_page_count = 0; 167 object->shadow_count = 0; 168 object->pg_color = next_index; 169 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) 170 incr = PQ_L2_SIZE / 3 + PQ_PRIME1; 171 else 172 incr = size; 173 next_index = (next_index + incr) & PQ_L2_MASK; 174 object->handle = NULL; 175 object->backing_object = NULL; 176 object->backing_object_offset = (vm_ooffset_t) 0; 177 /* 178 * Try to generate a number that will spread objects out in the 179 * hash table. We 'wipe' new objects across the hash in 128 page 180 * increments plus 1 more to offset it a little more by the time 181 * it wraps around. 182 */ 183 object->hash_rand = object_hash_rand - 129; 184 185 object->generation++; 186 187 crit_enter(); 188 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); 189 vm_object_count++; 190 object_hash_rand = object->hash_rand; 191 crit_exit(); 192 } 193 194 /* 195 * vm_object_init: 196 * 197 * Initialize the VM objects module. 198 */ 199 void 200 vm_object_init(void) 201 { 202 TAILQ_INIT(&vm_object_list); 203 204 kernel_object = &kernel_object_store; 205 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), 206 kernel_object); 207 208 kmem_object = &kmem_object_store; 209 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), 210 kmem_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 * vm_object_allocate: 225 * 226 * Returns a new object with the given size. 227 */ 228 229 vm_object_t 230 vm_object_allocate(objtype_t type, vm_size_t size) 231 { 232 vm_object_t result; 233 234 result = (vm_object_t) zalloc(obj_zone); 235 236 _vm_object_allocate(type, size, result); 237 238 return (result); 239 } 240 241 242 /* 243 * vm_object_reference: 244 * 245 * Gets another reference to the given object. 246 */ 247 void 248 vm_object_reference(vm_object_t object) 249 { 250 if (object == NULL) 251 return; 252 253 #if 0 254 /* object can be re-referenced during final cleaning */ 255 KASSERT(!(object->flags & OBJ_DEAD), 256 ("vm_object_reference: attempting to reference dead obj")); 257 #endif 258 259 object->ref_count++; 260 if (object->type == OBJT_VNODE) { 261 vref(object->handle); 262 /* XXX what if the vnode is being destroyed? */ 263 #if 0 264 while (vget((struct vnode *) object->handle, 265 LK_RETRY|LK_NOOBJ, curthread)) { 266 printf("vm_object_reference: delay in getting object\n"); 267 } 268 #endif 269 } 270 } 271 272 void 273 vm_object_vndeallocate(vm_object_t object) 274 { 275 struct vnode *vp = (struct vnode *) object->handle; 276 277 KASSERT(object->type == OBJT_VNODE, 278 ("vm_object_vndeallocate: not a vnode object")); 279 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); 280 #ifdef INVARIANTS 281 if (object->ref_count == 0) { 282 vprint("vm_object_vndeallocate", vp); 283 panic("vm_object_vndeallocate: bad object reference count"); 284 } 285 #endif 286 287 object->ref_count--; 288 if (object->ref_count == 0) { 289 vp->v_flag &= ~VTEXT; 290 vm_object_clear_flag(object, OBJ_OPT); 291 } 292 vrele(vp); 293 } 294 295 /* 296 * vm_object_deallocate: 297 * 298 * Release a reference to the specified object, 299 * gained either through a vm_object_allocate 300 * or a vm_object_reference call. When all references 301 * are gone, storage associated with this object 302 * may be relinquished. 303 * 304 * No object may be locked. 305 */ 306 void 307 vm_object_deallocate(vm_object_t object) 308 { 309 vm_object_t temp; 310 311 while (object != NULL) { 312 313 if (object->type == OBJT_VNODE) { 314 vm_object_vndeallocate(object); 315 return; 316 } 317 318 if (object->ref_count == 0) { 319 panic("vm_object_deallocate: object deallocated too many times: %d", object->type); 320 } else if (object->ref_count > 2) { 321 object->ref_count--; 322 return; 323 } 324 325 /* 326 * Here on ref_count of one or two, which are special cases for 327 * objects. 328 */ 329 if ((object->ref_count == 2) && (object->shadow_count == 0)) { 330 vm_object_set_flag(object, OBJ_ONEMAPPING); 331 object->ref_count--; 332 return; 333 } else if ((object->ref_count == 2) && (object->shadow_count == 1)) { 334 object->ref_count--; 335 if ((object->handle == NULL) && 336 (object->type == OBJT_DEFAULT || 337 object->type == OBJT_SWAP)) { 338 vm_object_t robject; 339 340 robject = LIST_FIRST(&object->shadow_head); 341 KASSERT(robject != NULL, 342 ("vm_object_deallocate: ref_count: %d, shadow_count: %d", 343 object->ref_count, 344 object->shadow_count)); 345 if ((robject->handle == NULL) && 346 (robject->type == OBJT_DEFAULT || 347 robject->type == OBJT_SWAP)) { 348 349 robject->ref_count++; 350 351 while ( 352 robject->paging_in_progress || 353 object->paging_in_progress 354 ) { 355 vm_object_pip_sleep(robject, "objde1"); 356 vm_object_pip_sleep(object, "objde2"); 357 } 358 359 if (robject->ref_count == 1) { 360 robject->ref_count--; 361 object = robject; 362 goto doterm; 363 } 364 365 object = robject; 366 vm_object_collapse(object); 367 continue; 368 } 369 } 370 371 return; 372 373 } else { 374 object->ref_count--; 375 if (object->ref_count != 0) 376 return; 377 } 378 379 doterm: 380 381 temp = object->backing_object; 382 if (temp) { 383 LIST_REMOVE(object, shadow_list); 384 temp->shadow_count--; 385 if (temp->ref_count == 0) 386 vm_object_clear_flag(temp, OBJ_OPT); 387 temp->generation++; 388 object->backing_object = NULL; 389 } 390 391 /* 392 * Don't double-terminate, we could be in a termination 393 * recursion due to the terminate having to sync data 394 * to disk. 395 */ 396 if ((object->flags & OBJ_DEAD) == 0) 397 vm_object_terminate(object); 398 object = temp; 399 } 400 } 401 402 /* 403 * vm_object_terminate actually destroys the specified object, freeing 404 * up all previously used resources. 405 * 406 * The object must be locked. 407 * This routine may block. 408 */ 409 void 410 vm_object_terminate(vm_object_t object) 411 { 412 vm_page_t p; 413 414 /* 415 * Make sure no one uses us. 416 */ 417 vm_object_set_flag(object, OBJ_DEAD); 418 419 /* 420 * wait for the pageout daemon to be done with the object 421 */ 422 vm_object_pip_wait(object, "objtrm"); 423 424 KASSERT(!object->paging_in_progress, 425 ("vm_object_terminate: pageout in progress")); 426 427 /* 428 * Clean and free the pages, as appropriate. All references to the 429 * object are gone, so we don't need to lock it. 430 */ 431 if (object->type == OBJT_VNODE) { 432 struct vnode *vp; 433 434 /* 435 * Freeze optimized copies. 436 */ 437 vm_freeze_copyopts(object, 0, object->size); 438 439 /* 440 * Clean pages and flush buffers. 441 */ 442 vm_object_page_clean(object, 0, 0, OBJPC_SYNC); 443 444 vp = (struct vnode *) object->handle; 445 vinvalbuf(vp, V_SAVE, NULL, 0, 0); 446 } 447 448 /* 449 * Wait for any I/O to complete, after which there had better not 450 * be any references left on the object. 451 */ 452 vm_object_pip_wait(object, "objtrm"); 453 454 if (object->ref_count != 0) 455 panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count); 456 457 /* 458 * Now free any remaining pages. For internal objects, this also 459 * removes them from paging queues. Don't free wired pages, just 460 * remove them from the object. 461 */ 462 crit_enter(); 463 while ((p = TAILQ_FIRST(&object->memq)) != NULL) { 464 if (p->busy || (p->flags & PG_BUSY)) 465 panic("vm_object_terminate: freeing busy page %p", p); 466 if (p->wire_count == 0) { 467 vm_page_busy(p); 468 vm_page_free(p); 469 mycpu->gd_cnt.v_pfree++; 470 } else { 471 vm_page_busy(p); 472 vm_page_remove(p); 473 vm_page_wakeup(p); 474 } 475 } 476 crit_exit(); 477 478 /* 479 * Let the pager know object is dead. 480 */ 481 vm_pager_deallocate(object); 482 483 /* 484 * Remove the object from the global object list. 485 */ 486 crit_enter(); 487 TAILQ_REMOVE(&vm_object_list, object, object_list); 488 vm_object_count--; 489 crit_exit(); 490 491 wakeup(object); 492 if (object->ref_count != 0) 493 panic("vm_object_terminate2: object with references, ref_count=%d", object->ref_count); 494 495 /* 496 * Free the space for the object. 497 */ 498 zfree(obj_zone, object); 499 } 500 501 /* 502 * vm_object_page_clean 503 * 504 * Clean all dirty pages in the specified range of object. Leaves page 505 * on whatever queue it is currently on. If NOSYNC is set then do not 506 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), 507 * leaving the object dirty. 508 * 509 * When stuffing pages asynchronously, allow clustering. XXX we need a 510 * synchronous clustering mode implementation. 511 * 512 * Odd semantics: if start == end, we clean everything. 513 */ 514 515 void 516 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, 517 int flags) 518 { 519 vm_page_t p, np; 520 vm_offset_t tstart, tend; 521 vm_pindex_t pi; 522 struct vnode *vp; 523 int clearobjflags; 524 int pagerflags; 525 int curgeneration; 526 527 if (object->type != OBJT_VNODE || 528 (object->flags & OBJ_MIGHTBEDIRTY) == 0) 529 return; 530 531 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; 532 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; 533 534 vp = object->handle; 535 536 vm_object_set_flag(object, OBJ_CLEANING); 537 538 /* 539 * Handle 'entire object' case 540 */ 541 tstart = start; 542 if (end == 0) { 543 tend = object->size; 544 } else { 545 tend = end; 546 } 547 548 /* 549 * If the caller is smart and only msync()s a range he knows is 550 * dirty, we may be able to avoid an object scan. This results in 551 * a phenominal improvement in performance. We cannot do this 552 * as a matter of course because the object may be huge - e.g. 553 * the size might be in the gigabytes or terrabytes. 554 */ 555 if (msync_flush_flags & MSYNC_FLUSH_HARDSEQ) { 556 vm_offset_t tscan; 557 int scanlimit; 558 int scanreset; 559 560 scanreset = object->resident_page_count / EASY_SCAN_FACTOR; 561 if (scanreset < 16) 562 scanreset = 16; 563 pagerflags |= VM_PAGER_IGNORE_CLEANCHK; 564 565 scanlimit = scanreset; 566 tscan = tstart; 567 568 /* 569 * spl protection is required despite the obj generation 570 * tracking because we cannot safely call vm_page_test_dirty() 571 * or avoid page field tests against an interrupt unbusy/free 572 * race that might occur prior to the busy check in 573 * vm_object_page_collect_flush(). 574 */ 575 crit_enter(); 576 while (tscan < tend) { 577 curgeneration = object->generation; 578 p = vm_page_lookup(object, tscan); 579 if (p == NULL || p->valid == 0 || 580 (p->queue - p->pc) == PQ_CACHE) { 581 if (--scanlimit == 0) 582 break; 583 ++tscan; 584 continue; 585 } 586 vm_page_test_dirty(p); 587 if ((p->dirty & p->valid) == 0) { 588 if (--scanlimit == 0) 589 break; 590 ++tscan; 591 continue; 592 } 593 /* 594 * If we have been asked to skip nosync pages and 595 * this is a nosync page, we can't continue. 596 */ 597 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 598 if (--scanlimit == 0) 599 break; 600 ++tscan; 601 continue; 602 } 603 scanlimit = scanreset; 604 605 /* 606 * This returns 0 if it was unable to busy the first 607 * page (i.e. had to sleep). 608 */ 609 tscan += vm_object_page_collect_flush(object, p, 610 curgeneration, pagerflags); 611 } 612 crit_exit(); 613 614 /* 615 * If everything was dirty and we flushed it successfully, 616 * and the requested range is not the entire object, we 617 * don't have to mess with CLEANCHK or MIGHTBEDIRTY and can 618 * return immediately. 619 */ 620 if (tscan >= tend && (tstart || tend < object->size)) { 621 vm_object_clear_flag(object, OBJ_CLEANING); 622 return; 623 } 624 pagerflags &= ~VM_PAGER_IGNORE_CLEANCHK; 625 } 626 627 /* 628 * Generally set CLEANCHK interlock and make the page read-only so 629 * we can then clear the object flags. 630 * 631 * However, if this is a nosync mmap then the object is likely to 632 * stay dirty so do not mess with the page and do not clear the 633 * object flags. 634 * 635 * spl protection is required because an interrupt can remove page 636 * from the object. 637 */ 638 clearobjflags = 1; 639 640 crit_enter(); 641 for (p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) { 642 vm_page_flag_set(p, PG_CLEANCHK); 643 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) 644 clearobjflags = 0; 645 else 646 vm_page_protect(p, VM_PROT_READ); 647 } 648 crit_exit(); 649 650 if (clearobjflags && (tstart == 0) && (tend == object->size)) { 651 struct vnode *vp; 652 653 vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 654 if (object->type == OBJT_VNODE && 655 (vp = (struct vnode *)object->handle) != NULL) { 656 if (vp->v_flag & VOBJDIRTY) 657 vclrflags(vp, VOBJDIRTY); 658 } 659 } 660 661 /* 662 * spl protection is required both to avoid an interrupt unbusy/free 663 * race against a vm_page_lookup(), and also to ensure that the 664 * memq is consistent. We do not want a busy page to be ripped out 665 * from under us. 666 */ 667 crit_enter(); 668 rescan: 669 crit_exit(); 670 crit_enter(); 671 curgeneration = object->generation; 672 673 for (p = TAILQ_FIRST(&object->memq); p; p = np) { 674 int n; 675 676 np = TAILQ_NEXT(p, listq); 677 678 again: 679 pi = p->pindex; 680 if (((p->flags & PG_CLEANCHK) == 0) || 681 (pi < tstart) || (pi >= tend) || 682 (p->valid == 0) || 683 ((p->queue - p->pc) == PQ_CACHE)) { 684 vm_page_flag_clear(p, PG_CLEANCHK); 685 continue; 686 } 687 688 vm_page_test_dirty(p); 689 if ((p->dirty & p->valid) == 0) { 690 vm_page_flag_clear(p, PG_CLEANCHK); 691 continue; 692 } 693 694 /* 695 * If we have been asked to skip nosync pages and this is a 696 * nosync page, skip it. Note that the object flags were 697 * not cleared in this case so we do not have to set them. 698 */ 699 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { 700 vm_page_flag_clear(p, PG_CLEANCHK); 701 continue; 702 } 703 704 n = vm_object_page_collect_flush(object, p, 705 curgeneration, pagerflags); 706 if (n == 0) 707 goto rescan; 708 if (object->generation != curgeneration) 709 goto rescan; 710 711 /* 712 * Try to optimize the next page. If we can't we pick up 713 * our (random) scan where we left off. 714 */ 715 if (msync_flush_flags & MSYNC_FLUSH_SOFTSEQ) { 716 if ((p = vm_page_lookup(object, pi + n)) != NULL) 717 goto again; 718 } 719 } 720 crit_exit(); 721 722 #if 0 723 VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc); 724 #endif 725 726 vm_object_clear_flag(object, OBJ_CLEANING); 727 return; 728 } 729 730 /* 731 * This routine must be called within a critical section to properly avoid 732 * an interrupt unbusy/free race that can occur prior to the busy check. 733 * 734 * Using the object generation number here to detect page ripout is not 735 * the best idea in the world. XXX 736 * 737 * NOTE: we operate under the assumption that a page found to not be busy 738 * will not be ripped out from under us by an interrupt. XXX we should 739 * recode this to explicitly busy the pages. 740 */ 741 static int 742 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags) 743 { 744 int runlen; 745 int maxf; 746 int chkb; 747 int maxb; 748 int i; 749 vm_pindex_t pi; 750 vm_page_t maf[vm_pageout_page_count]; 751 vm_page_t mab[vm_pageout_page_count]; 752 vm_page_t ma[vm_pageout_page_count]; 753 754 pi = p->pindex; 755 while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { 756 if (object->generation != curgeneration) { 757 return(0); 758 } 759 } 760 761 maxf = 0; 762 for(i = 1; i < vm_pageout_page_count; i++) { 763 vm_page_t tp; 764 765 if ((tp = vm_page_lookup(object, pi + i)) != NULL) { 766 if ((tp->flags & PG_BUSY) || 767 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 768 (tp->flags & PG_CLEANCHK) == 0) || 769 (tp->busy != 0)) 770 break; 771 if((tp->queue - tp->pc) == PQ_CACHE) { 772 vm_page_flag_clear(tp, PG_CLEANCHK); 773 break; 774 } 775 vm_page_test_dirty(tp); 776 if ((tp->dirty & tp->valid) == 0) { 777 vm_page_flag_clear(tp, PG_CLEANCHK); 778 break; 779 } 780 maf[ i - 1 ] = tp; 781 maxf++; 782 continue; 783 } 784 break; 785 } 786 787 maxb = 0; 788 chkb = vm_pageout_page_count - maxf; 789 if (chkb) { 790 for(i = 1; i < chkb;i++) { 791 vm_page_t tp; 792 793 if ((tp = vm_page_lookup(object, pi - i)) != NULL) { 794 if ((tp->flags & PG_BUSY) || 795 ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && 796 (tp->flags & PG_CLEANCHK) == 0) || 797 (tp->busy != 0)) 798 break; 799 if((tp->queue - tp->pc) == PQ_CACHE) { 800 vm_page_flag_clear(tp, PG_CLEANCHK); 801 break; 802 } 803 vm_page_test_dirty(tp); 804 if ((tp->dirty & tp->valid) == 0) { 805 vm_page_flag_clear(tp, PG_CLEANCHK); 806 break; 807 } 808 mab[ i - 1 ] = tp; 809 maxb++; 810 continue; 811 } 812 break; 813 } 814 } 815 816 for(i = 0; i < maxb; i++) { 817 int index = (maxb - i) - 1; 818 ma[index] = mab[i]; 819 vm_page_flag_clear(ma[index], PG_CLEANCHK); 820 } 821 vm_page_flag_clear(p, PG_CLEANCHK); 822 ma[maxb] = p; 823 for(i = 0; i < maxf; i++) { 824 int index = (maxb + i) + 1; 825 ma[index] = maf[i]; 826 vm_page_flag_clear(ma[index], PG_CLEANCHK); 827 } 828 runlen = maxb + maxf + 1; 829 830 vm_pageout_flush(ma, runlen, pagerflags); 831 for (i = 0; i < runlen; i++) { 832 if (ma[i]->valid & ma[i]->dirty) { 833 vm_page_protect(ma[i], VM_PROT_READ); 834 vm_page_flag_set(ma[i], PG_CLEANCHK); 835 836 /* 837 * maxf will end up being the actual number of pages 838 * we wrote out contiguously, non-inclusive of the 839 * first page. We do not count look-behind pages. 840 */ 841 if (i >= maxb + 1 && (maxf > i - maxb - 1)) 842 maxf = i - maxb - 1; 843 } 844 } 845 return(maxf + 1); 846 } 847 848 #ifdef not_used 849 /* XXX I cannot tell if this should be an exported symbol */ 850 /* 851 * vm_object_deactivate_pages 852 * 853 * Deactivate all pages in the specified object. (Keep its pages 854 * in memory even though it is no longer referenced.) 855 * 856 * The object must be locked. 857 */ 858 static void 859 vm_object_deactivate_pages(vm_object_t object) 860 { 861 vm_page_t p, next; 862 int s; 863 864 crit_enter(); 865 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { 866 next = TAILQ_NEXT(p, listq); 867 vm_page_deactivate(p); 868 } 869 crit_exit(); 870 } 871 #endif 872 873 /* 874 * Same as vm_object_pmap_copy, except range checking really 875 * works, and is meant for small sections of an object. 876 * 877 * This code protects resident pages by making them read-only 878 * and is typically called on a fork or split when a page 879 * is converted to copy-on-write. 880 * 881 * NOTE: If the page is already at VM_PROT_NONE, calling 882 * vm_page_protect will have no effect. 883 */ 884 void 885 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 886 { 887 vm_pindex_t idx; 888 vm_page_t p; 889 890 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) 891 return; 892 893 /* 894 * spl protection needed to prevent races between the lookup, 895 * an interrupt unbusy/free, and our protect call. 896 */ 897 crit_enter(); 898 for (idx = start; idx < end; idx++) { 899 p = vm_page_lookup(object, idx); 900 if (p == NULL) 901 continue; 902 vm_page_protect(p, VM_PROT_READ); 903 } 904 crit_exit(); 905 } 906 907 /* 908 * vm_object_pmap_remove: 909 * 910 * Removes all physical pages in the specified 911 * object range from all physical maps. 912 * 913 * The object must *not* be locked. 914 */ 915 void 916 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end) 917 { 918 vm_page_t p; 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 crit_enter(); 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 crit_exit(); 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; 967 968 if (object == NULL) 969 return; 970 971 end = pindex + count; 972 973 /* 974 * Locate and adjust resident pages 975 */ 976 977 for (; pindex < end; pindex += 1) { 978 relookup: 979 tobject = object; 980 tpindex = pindex; 981 shadowlookup: 982 /* 983 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages 984 * and those pages must be OBJ_ONEMAPPING. 985 */ 986 if (advise == MADV_FREE) { 987 if ((tobject->type != OBJT_DEFAULT && 988 tobject->type != OBJT_SWAP) || 989 (tobject->flags & OBJ_ONEMAPPING) == 0) { 990 continue; 991 } 992 } 993 994 /* 995 * spl protection is required to avoid a race between the 996 * lookup, an interrupt unbusy/free, and our busy check. 997 */ 998 999 crit_enter(); 1000 m = vm_page_lookup(tobject, tpindex); 1001 1002 if (m == NULL) { 1003 /* 1004 * There may be swap even if there is no backing page 1005 */ 1006 if (advise == MADV_FREE && tobject->type == OBJT_SWAP) 1007 swap_pager_freespace(tobject, tpindex, 1); 1008 1009 /* 1010 * next object 1011 */ 1012 crit_exit(); 1013 if (tobject->backing_object == NULL) 1014 continue; 1015 tpindex += OFF_TO_IDX(tobject->backing_object_offset); 1016 tobject = tobject->backing_object; 1017 goto shadowlookup; 1018 } 1019 1020 /* 1021 * If the page is busy or not in a normal active state, 1022 * we skip it. If the page is not managed there are no 1023 * page queues to mess with. Things can break if we mess 1024 * with pages in any of the below states. 1025 */ 1026 if ( 1027 m->hold_count || 1028 m->wire_count || 1029 (m->flags & PG_UNMANAGED) || 1030 m->valid != VM_PAGE_BITS_ALL 1031 ) { 1032 crit_exit(); 1033 continue; 1034 } 1035 1036 if (vm_page_sleep_busy(m, TRUE, "madvpo")) { 1037 crit_exit(); 1038 goto relookup; 1039 } 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 } 1075 } 1076 1077 /* 1078 * vm_object_shadow: 1079 * 1080 * Create a new object which is backed by the 1081 * specified existing object range. The source 1082 * object reference is deallocated. 1083 * 1084 * The new object and offset into that object 1085 * are returned in the source parameters. 1086 */ 1087 1088 void 1089 vm_object_shadow(vm_object_t *object, /* IN/OUT */ 1090 vm_ooffset_t *offset, /* IN/OUT */ 1091 vm_size_t length) 1092 { 1093 vm_object_t source; 1094 vm_object_t result; 1095 1096 source = *object; 1097 1098 /* 1099 * Don't create the new object if the old object isn't shared. 1100 */ 1101 1102 if (source != NULL && 1103 source->ref_count == 1 && 1104 source->handle == NULL && 1105 (source->type == OBJT_DEFAULT || 1106 source->type == OBJT_SWAP)) 1107 return; 1108 1109 /* 1110 * Allocate a new object with the given length 1111 */ 1112 1113 if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) 1114 panic("vm_object_shadow: no object for shadowing"); 1115 1116 /* 1117 * The new object shadows the source object, adding a reference to it. 1118 * Our caller changes his reference to point to the new object, 1119 * removing a reference to the source object. Net result: no change 1120 * of reference count. 1121 * 1122 * Try to optimize the result object's page color when shadowing 1123 * in order to maintain page coloring consistency in the combined 1124 * shadowed object. 1125 */ 1126 result->backing_object = source; 1127 if (source) { 1128 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); 1129 source->shadow_count++; 1130 source->generation++; 1131 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK; 1132 } 1133 1134 /* 1135 * Store the offset into the source object, and fix up the offset into 1136 * the new object. 1137 */ 1138 1139 result->backing_object_offset = *offset; 1140 1141 /* 1142 * Return the new things 1143 */ 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 __inline int 1154 vm_object_backing_scan(vm_object_t object, int op) 1155 { 1156 int r = 1; 1157 vm_page_t p; 1158 vm_object_t backing_object; 1159 vm_pindex_t backing_offset_index; 1160 1161 /* 1162 * spl protection is required to avoid races between the memq/lookup, 1163 * an interrupt doing an unbusy/free, and our busy check. Amoung 1164 * other things. 1165 */ 1166 crit_enter(); 1167 1168 backing_object = object->backing_object; 1169 backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 1170 1171 /* 1172 * Initial conditions 1173 */ 1174 1175 if (op & OBSC_TEST_ALL_SHADOWED) { 1176 /* 1177 * We do not want to have to test for the existence of 1178 * swap pages in the backing object. XXX but with the 1179 * new swapper this would be pretty easy to do. 1180 * 1181 * XXX what about anonymous MAP_SHARED memory that hasn't 1182 * been ZFOD faulted yet? If we do not test for this, the 1183 * shadow test may succeed! XXX 1184 */ 1185 if (backing_object->type != OBJT_DEFAULT) { 1186 crit_exit(); 1187 return(0); 1188 } 1189 } 1190 if (op & OBSC_COLLAPSE_WAIT) { 1191 KKASSERT((backing_object->flags & OBJ_DEAD) == 0); 1192 vm_object_set_flag(backing_object, OBJ_DEAD); 1193 } 1194 1195 /* 1196 * Our scan 1197 */ 1198 1199 p = TAILQ_FIRST(&backing_object->memq); 1200 while (p) { 1201 vm_page_t next = TAILQ_NEXT(p, listq); 1202 vm_pindex_t new_pindex = p->pindex - backing_offset_index; 1203 1204 if (op & OBSC_TEST_ALL_SHADOWED) { 1205 vm_page_t pp; 1206 1207 /* 1208 * Ignore pages outside the parent object's range 1209 * and outside the parent object's mapping of the 1210 * backing object. 1211 * 1212 * note that we do not busy the backing object's 1213 * page. 1214 */ 1215 1216 if ( 1217 p->pindex < backing_offset_index || 1218 new_pindex >= object->size 1219 ) { 1220 p = next; 1221 continue; 1222 } 1223 1224 /* 1225 * See if the parent has the page or if the parent's 1226 * object pager has the page. If the parent has the 1227 * page but the page is not valid, the parent's 1228 * object pager must have the page. 1229 * 1230 * If this fails, the parent does not completely shadow 1231 * the object and we might as well give up now. 1232 */ 1233 1234 pp = vm_page_lookup(object, new_pindex); 1235 if ( 1236 (pp == NULL || pp->valid == 0) && 1237 !vm_pager_has_page(object, new_pindex, NULL, NULL) 1238 ) { 1239 r = 0; 1240 break; 1241 } 1242 } 1243 1244 /* 1245 * Check for busy page 1246 */ 1247 1248 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { 1249 vm_page_t pp; 1250 1251 if (op & OBSC_COLLAPSE_NOWAIT) { 1252 if ( 1253 (p->flags & PG_BUSY) || 1254 !p->valid || 1255 p->hold_count || 1256 p->wire_count || 1257 p->busy 1258 ) { 1259 p = next; 1260 continue; 1261 } 1262 } else if (op & OBSC_COLLAPSE_WAIT) { 1263 if (vm_page_sleep_busy(p, TRUE, "vmocol")) { 1264 /* 1265 * If we slept, anything could have 1266 * happened. Since the object is 1267 * marked dead, the backing offset 1268 * should not have changed so we 1269 * just restart our scan. 1270 */ 1271 p = TAILQ_FIRST(&backing_object->memq); 1272 continue; 1273 } 1274 } 1275 1276 /* 1277 * Busy the page 1278 */ 1279 vm_page_busy(p); 1280 1281 KASSERT( 1282 p->object == backing_object, 1283 ("vm_object_qcollapse(): object mismatch") 1284 ); 1285 1286 /* 1287 * Destroy any associated swap 1288 */ 1289 if (backing_object->type == OBJT_SWAP) { 1290 swap_pager_freespace( 1291 backing_object, 1292 p->pindex, 1293 1 1294 ); 1295 } 1296 1297 if ( 1298 p->pindex < backing_offset_index || 1299 new_pindex >= object->size 1300 ) { 1301 /* 1302 * Page is out of the parent object's range, we 1303 * can simply destroy it. 1304 */ 1305 vm_page_protect(p, VM_PROT_NONE); 1306 vm_page_free(p); 1307 p = next; 1308 continue; 1309 } 1310 1311 pp = vm_page_lookup(object, new_pindex); 1312 if ( 1313 pp != NULL || 1314 vm_pager_has_page(object, new_pindex, NULL, NULL) 1315 ) { 1316 /* 1317 * page already exists in parent OR swap exists 1318 * for this location in the parent. Destroy 1319 * the original page from the backing object. 1320 * 1321 * Leave the parent's page alone 1322 */ 1323 vm_page_protect(p, VM_PROT_NONE); 1324 vm_page_free(p); 1325 p = next; 1326 continue; 1327 } 1328 1329 /* 1330 * Page does not exist in parent, rename the 1331 * page from the backing object to the main object. 1332 * 1333 * If the page was mapped to a process, it can remain 1334 * mapped through the rename. 1335 */ 1336 if ((p->queue - p->pc) == PQ_CACHE) 1337 vm_page_deactivate(p); 1338 1339 vm_page_rename(p, object, new_pindex); 1340 /* page automatically made dirty by rename */ 1341 } 1342 p = next; 1343 } 1344 crit_exit(); 1345 return(r); 1346 } 1347 1348 1349 /* 1350 * this version of collapse allows the operation to occur earlier and 1351 * when paging_in_progress is true for an object... This is not a complete 1352 * operation, but should plug 99.9% of the rest of the leaks. 1353 */ 1354 static void 1355 vm_object_qcollapse(vm_object_t object) 1356 { 1357 vm_object_t backing_object = object->backing_object; 1358 1359 if (backing_object->ref_count != 1) 1360 return; 1361 1362 backing_object->ref_count += 2; 1363 1364 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 1365 1366 backing_object->ref_count -= 2; 1367 } 1368 1369 /* 1370 * vm_object_collapse: 1371 * 1372 * Collapse an object with the object backing it. 1373 * Pages in the backing object are moved into the 1374 * parent, and the backing object is deallocated. 1375 */ 1376 void 1377 vm_object_collapse(vm_object_t object) 1378 { 1379 while (TRUE) { 1380 vm_object_t backing_object; 1381 1382 /* 1383 * Verify that the conditions are right for collapse: 1384 * 1385 * The object exists and the backing object exists. 1386 */ 1387 if (object == NULL) 1388 break; 1389 1390 if ((backing_object = object->backing_object) == NULL) 1391 break; 1392 1393 /* 1394 * we check the backing object first, because it is most likely 1395 * not collapsable. 1396 */ 1397 if (backing_object->handle != NULL || 1398 (backing_object->type != OBJT_DEFAULT && 1399 backing_object->type != OBJT_SWAP) || 1400 (backing_object->flags & OBJ_DEAD) || 1401 object->handle != NULL || 1402 (object->type != OBJT_DEFAULT && 1403 object->type != OBJT_SWAP) || 1404 (object->flags & OBJ_DEAD)) { 1405 break; 1406 } 1407 1408 if ( 1409 object->paging_in_progress != 0 || 1410 backing_object->paging_in_progress != 0 1411 ) { 1412 vm_object_qcollapse(object); 1413 break; 1414 } 1415 1416 /* 1417 * We know that we can either collapse the backing object (if 1418 * the parent is the only reference to it) or (perhaps) have 1419 * the parent bypass the object if the parent happens to shadow 1420 * all the resident pages in the entire backing object. 1421 * 1422 * This is ignoring pager-backed pages such as swap pages. 1423 * vm_object_backing_scan fails the shadowing test in this 1424 * case. 1425 */ 1426 1427 if (backing_object->ref_count == 1) { 1428 /* 1429 * If there is exactly one reference to the backing 1430 * object, we can collapse it into the parent. 1431 */ 1432 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); 1433 1434 /* 1435 * Move the pager from backing_object to object. 1436 */ 1437 1438 if (backing_object->type == OBJT_SWAP) { 1439 vm_object_pip_add(backing_object, 1); 1440 1441 /* 1442 * scrap the paging_offset junk and do a 1443 * discrete copy. This also removes major 1444 * assumptions about how the swap-pager 1445 * works from where it doesn't belong. The 1446 * new swapper is able to optimize the 1447 * destroy-source case. 1448 */ 1449 1450 vm_object_pip_add(object, 1); 1451 swap_pager_copy( 1452 backing_object, 1453 object, 1454 OFF_TO_IDX(object->backing_object_offset), TRUE); 1455 vm_object_pip_wakeup(object); 1456 1457 vm_object_pip_wakeup(backing_object); 1458 } 1459 /* 1460 * Object now shadows whatever backing_object did. 1461 * Note that the reference to 1462 * backing_object->backing_object moves from within 1463 * backing_object to within object. 1464 */ 1465 1466 LIST_REMOVE(object, shadow_list); 1467 object->backing_object->shadow_count--; 1468 object->backing_object->generation++; 1469 if (backing_object->backing_object) { 1470 LIST_REMOVE(backing_object, shadow_list); 1471 backing_object->backing_object->shadow_count--; 1472 backing_object->backing_object->generation++; 1473 } 1474 object->backing_object = backing_object->backing_object; 1475 if (object->backing_object) { 1476 LIST_INSERT_HEAD( 1477 &object->backing_object->shadow_head, 1478 object, 1479 shadow_list 1480 ); 1481 object->backing_object->shadow_count++; 1482 object->backing_object->generation++; 1483 } 1484 1485 object->backing_object_offset += 1486 backing_object->backing_object_offset; 1487 1488 /* 1489 * Discard backing_object. 1490 * 1491 * Since the backing object has no pages, no pager left, 1492 * and no object references within it, all that is 1493 * necessary is to dispose of it. 1494 */ 1495 1496 KASSERT(backing_object->ref_count == 1, ("backing_object %p was somehow re-referenced during collapse!", backing_object)); 1497 KASSERT(TAILQ_FIRST(&backing_object->memq) == NULL, ("backing_object %p somehow has left over pages during collapse!", backing_object)); 1498 crit_enter(); 1499 TAILQ_REMOVE( 1500 &vm_object_list, 1501 backing_object, 1502 object_list 1503 ); 1504 vm_object_count--; 1505 crit_exit(); 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 1576 if (object == NULL || object->resident_page_count == 0) 1577 return; 1578 1579 all = ((end == 0) && (start == 0)); 1580 1581 /* 1582 * Since physically-backed objects do not use managed pages, we can't 1583 * remove pages from the object (we must instead remove the page 1584 * references, and then destroy the object). 1585 */ 1586 KASSERT(object->type != OBJT_PHYS, 1587 ("attempt to remove pages from a physical object")); 1588 1589 /* 1590 * Indicating that the object is undergoing paging. 1591 * 1592 * spl protection is required to avoid a race between the memq scan, 1593 * an interrupt unbusy/free, and the busy check. 1594 */ 1595 vm_object_pip_add(object, 1); 1596 crit_enter(); 1597 again: 1598 size = end - start; 1599 if (all || size > object->resident_page_count / 4) { 1600 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { 1601 next = TAILQ_NEXT(p, listq); 1602 if (all || ((start <= p->pindex) && (p->pindex < end))) { 1603 if (p->wire_count != 0) { 1604 vm_page_protect(p, VM_PROT_NONE); 1605 if (!clean_only) 1606 p->valid = 0; 1607 continue; 1608 } 1609 1610 /* 1611 * The busy flags are only cleared at 1612 * interrupt -- minimize the spl transitions 1613 */ 1614 1615 if (vm_page_sleep_busy(p, TRUE, "vmopar")) 1616 goto again; 1617 1618 if (clean_only && p->valid) { 1619 vm_page_test_dirty(p); 1620 if (p->valid & p->dirty) 1621 continue; 1622 } 1623 1624 vm_page_busy(p); 1625 vm_page_protect(p, VM_PROT_NONE); 1626 vm_page_free(p); 1627 } 1628 } 1629 } else { 1630 while (size > 0) { 1631 if ((p = vm_page_lookup(object, start)) != 0) { 1632 if (p->wire_count != 0) { 1633 vm_page_protect(p, VM_PROT_NONE); 1634 if (!clean_only) 1635 p->valid = 0; 1636 start += 1; 1637 size -= 1; 1638 continue; 1639 } 1640 1641 /* 1642 * The busy flags are only cleared at 1643 * interrupt -- minimize the spl transitions 1644 */ 1645 if (vm_page_sleep_busy(p, TRUE, "vmopar")) 1646 goto again; 1647 1648 if (clean_only && p->valid) { 1649 vm_page_test_dirty(p); 1650 if (p->valid & p->dirty) { 1651 start += 1; 1652 size -= 1; 1653 continue; 1654 } 1655 } 1656 1657 vm_page_busy(p); 1658 vm_page_protect(p, VM_PROT_NONE); 1659 vm_page_free(p); 1660 } 1661 start += 1; 1662 size -= 1; 1663 } 1664 } 1665 crit_exit(); 1666 vm_object_pip_wakeup(object); 1667 } 1668 1669 /* 1670 * Routine: vm_object_coalesce 1671 * Function: Coalesces two objects backing up adjoining 1672 * regions of memory into a single object. 1673 * 1674 * returns TRUE if objects were combined. 1675 * 1676 * NOTE: Only works at the moment if the second object is NULL - 1677 * if it's not, which object do we lock first? 1678 * 1679 * Parameters: 1680 * prev_object First object to coalesce 1681 * prev_offset Offset into prev_object 1682 * next_object Second object into coalesce 1683 * next_offset Offset into next_object 1684 * 1685 * prev_size Size of reference to prev_object 1686 * next_size Size of reference to next_object 1687 * 1688 * Conditions: 1689 * The object must *not* be locked. 1690 */ 1691 boolean_t 1692 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, 1693 vm_size_t prev_size, vm_size_t next_size) 1694 { 1695 vm_pindex_t next_pindex; 1696 1697 if (prev_object == NULL) { 1698 return (TRUE); 1699 } 1700 1701 if (prev_object->type != OBJT_DEFAULT && 1702 prev_object->type != OBJT_SWAP) { 1703 return (FALSE); 1704 } 1705 1706 /* 1707 * Try to collapse the object first 1708 */ 1709 vm_object_collapse(prev_object); 1710 1711 /* 1712 * Can't coalesce if: . more than one reference . paged out . shadows 1713 * another object . has a copy elsewhere (any of which mean that the 1714 * pages not mapped to prev_entry may be in use anyway) 1715 */ 1716 1717 if (prev_object->backing_object != NULL) { 1718 return (FALSE); 1719 } 1720 1721 prev_size >>= PAGE_SHIFT; 1722 next_size >>= PAGE_SHIFT; 1723 next_pindex = prev_pindex + prev_size; 1724 1725 if ((prev_object->ref_count > 1) && 1726 (prev_object->size != next_pindex)) { 1727 return (FALSE); 1728 } 1729 1730 /* 1731 * Remove any pages that may still be in the object from a previous 1732 * deallocation. 1733 */ 1734 if (next_pindex < prev_object->size) { 1735 vm_object_page_remove(prev_object, 1736 next_pindex, 1737 next_pindex + next_size, FALSE); 1738 if (prev_object->type == OBJT_SWAP) 1739 swap_pager_freespace(prev_object, 1740 next_pindex, next_size); 1741 } 1742 1743 /* 1744 * Extend the object if necessary. 1745 */ 1746 if (next_pindex + next_size > prev_object->size) 1747 prev_object->size = next_pindex + next_size; 1748 1749 return (TRUE); 1750 } 1751 1752 void 1753 vm_object_set_writeable_dirty(vm_object_t object) 1754 { 1755 struct vnode *vp; 1756 1757 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 1758 if (object->type == OBJT_VNODE && 1759 (vp = (struct vnode *)object->handle) != NULL) { 1760 if ((vp->v_flag & VOBJDIRTY) == 0) { 1761 vsetflags(vp, VOBJDIRTY); 1762 } 1763 } 1764 } 1765 1766 1767 1768 #include "opt_ddb.h" 1769 #ifdef DDB 1770 #include <sys/kernel.h> 1771 1772 #include <sys/cons.h> 1773 1774 #include <ddb/ddb.h> 1775 1776 static int _vm_object_in_map (vm_map_t map, vm_object_t object, 1777 vm_map_entry_t entry); 1778 static int vm_object_in_map (vm_object_t object); 1779 1780 static int 1781 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry) 1782 { 1783 vm_map_t tmpm; 1784 vm_map_entry_t tmpe; 1785 vm_object_t obj; 1786 int entcount; 1787 1788 if (map == 0) 1789 return 0; 1790 1791 if (entry == 0) { 1792 tmpe = map->header.next; 1793 entcount = map->nentries; 1794 while (entcount-- && (tmpe != &map->header)) { 1795 if( _vm_object_in_map(map, object, tmpe)) { 1796 return 1; 1797 } 1798 tmpe = tmpe->next; 1799 } 1800 } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) { 1801 tmpm = entry->object.sub_map; 1802 tmpe = tmpm->header.next; 1803 entcount = tmpm->nentries; 1804 while (entcount-- && tmpe != &tmpm->header) { 1805 if( _vm_object_in_map(tmpm, object, tmpe)) { 1806 return 1; 1807 } 1808 tmpe = tmpe->next; 1809 } 1810 } else if ((obj = entry->object.vm_object) != NULL) { 1811 for(; obj; obj=obj->backing_object) 1812 if( obj == object) { 1813 return 1; 1814 } 1815 } 1816 return 0; 1817 } 1818 1819 static int 1820 vm_object_in_map(vm_object_t object) 1821 { 1822 struct proc *p; 1823 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) { 1824 if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */) 1825 continue; 1826 if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) 1827 return 1; 1828 } 1829 if( _vm_object_in_map( kernel_map, object, 0)) 1830 return 1; 1831 if( _vm_object_in_map( pager_map, object, 0)) 1832 return 1; 1833 if( _vm_object_in_map( buffer_map, object, 0)) 1834 return 1; 1835 return 0; 1836 } 1837 1838 DB_SHOW_COMMAND(vmochk, vm_object_check) 1839 { 1840 vm_object_t object; 1841 1842 /* 1843 * make sure that internal objs are in a map somewhere 1844 * and none have zero ref counts. 1845 */ 1846 for (object = TAILQ_FIRST(&vm_object_list); 1847 object != NULL; 1848 object = TAILQ_NEXT(object, object_list)) { 1849 if (object->handle == NULL && 1850 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { 1851 if (object->ref_count == 0) { 1852 db_printf("vmochk: internal obj has zero ref count: %ld\n", 1853 (long)object->size); 1854 } 1855 if (!vm_object_in_map(object)) { 1856 db_printf( 1857 "vmochk: internal obj is not in a map: " 1858 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", 1859 object->ref_count, (u_long)object->size, 1860 (u_long)object->size, 1861 (void *)object->backing_object); 1862 } 1863 } 1864 } 1865 } 1866 1867 /* 1868 * vm_object_print: [ debug ] 1869 */ 1870 DB_SHOW_COMMAND(object, vm_object_print_static) 1871 { 1872 /* XXX convert args. */ 1873 vm_object_t object = (vm_object_t)addr; 1874 boolean_t full = have_addr; 1875 1876 vm_page_t p; 1877 1878 /* XXX count is an (unused) arg. Avoid shadowing it. */ 1879 #define count was_count 1880 1881 int count; 1882 1883 if (object == NULL) 1884 return; 1885 1886 db_iprintf( 1887 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", 1888 object, (int)object->type, (u_long)object->size, 1889 object->resident_page_count, object->ref_count, object->flags); 1890 /* 1891 * XXX no %qd in kernel. Truncate object->backing_object_offset. 1892 */ 1893 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", 1894 object->shadow_count, 1895 object->backing_object ? object->backing_object->ref_count : 0, 1896 object->backing_object, (long)object->backing_object_offset); 1897 1898 if (!full) 1899 return; 1900 1901 db_indent += 2; 1902 count = 0; 1903 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) { 1904 if (count == 0) 1905 db_iprintf("memory:="); 1906 else if (count == 6) { 1907 db_printf("\n"); 1908 db_iprintf(" ..."); 1909 count = 0; 1910 } else 1911 db_printf(","); 1912 count++; 1913 1914 db_printf("(off=0x%lx,page=0x%lx)", 1915 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); 1916 } 1917 if (count != 0) 1918 db_printf("\n"); 1919 db_indent -= 2; 1920 } 1921 1922 /* XXX. */ 1923 #undef count 1924 1925 /* XXX need this non-static entry for calling from vm_map_print. */ 1926 void 1927 vm_object_print(/* db_expr_t */ long addr, 1928 boolean_t have_addr, 1929 /* db_expr_t */ long count, 1930 char *modif) 1931 { 1932 vm_object_print_static(addr, have_addr, count, modif); 1933 } 1934 1935 DB_SHOW_COMMAND(vmopag, vm_object_print_pages) 1936 { 1937 vm_object_t object; 1938 int nl = 0; 1939 int c; 1940 for (object = TAILQ_FIRST(&vm_object_list); 1941 object != NULL; 1942 object = TAILQ_NEXT(object, object_list)) { 1943 vm_pindex_t idx, fidx; 1944 vm_pindex_t osize; 1945 vm_paddr_t pa = -1, padiff; 1946 int rcount; 1947 vm_page_t m; 1948 1949 db_printf("new object: %p\n", (void *)object); 1950 if ( nl > 18) { 1951 c = cngetc(); 1952 if (c != ' ') 1953 return; 1954 nl = 0; 1955 } 1956 nl++; 1957 rcount = 0; 1958 fidx = 0; 1959 osize = object->size; 1960 if (osize > 128) 1961 osize = 128; 1962 for (idx = 0; idx < osize; idx++) { 1963 m = vm_page_lookup(object, idx); 1964 if (m == NULL) { 1965 if (rcount) { 1966 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 1967 (long)fidx, rcount, (long)pa); 1968 if ( nl > 18) { 1969 c = cngetc(); 1970 if (c != ' ') 1971 return; 1972 nl = 0; 1973 } 1974 nl++; 1975 rcount = 0; 1976 } 1977 continue; 1978 } 1979 1980 1981 if (rcount && 1982 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { 1983 ++rcount; 1984 continue; 1985 } 1986 if (rcount) { 1987 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); 1988 padiff >>= PAGE_SHIFT; 1989 padiff &= PQ_L2_MASK; 1990 if (padiff == 0) { 1991 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; 1992 ++rcount; 1993 continue; 1994 } 1995 db_printf(" index(%ld)run(%d)pa(0x%lx)", 1996 (long)fidx, rcount, (long)pa); 1997 db_printf("pd(%ld)\n", (long)padiff); 1998 if ( nl > 18) { 1999 c = cngetc(); 2000 if (c != ' ') 2001 return; 2002 nl = 0; 2003 } 2004 nl++; 2005 } 2006 fidx = idx; 2007 pa = VM_PAGE_TO_PHYS(m); 2008 rcount = 1; 2009 } 2010 if (rcount) { 2011 db_printf(" index(%ld)run(%d)pa(0x%lx)\n", 2012 (long)fidx, rcount, (long)pa); 2013 if ( nl > 18) { 2014 c = cngetc(); 2015 if (c != ' ') 2016 return; 2017 nl = 0; 2018 } 2019 nl++; 2020 } 2021 } 2022 } 2023 #endif /* DDB */ 2024