xref: /freebsd/sys/vm/vm_object.c (revision 7f3dea244c40159a41ab22da77a434d7c5b5e85a)
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  * $Id: vm_object.c,v 1.165 1999/08/15 21:55:20 alc Exp $
65  */
66 
67 /*
68  *	Virtual memory object module.
69  */
70 
71 #include <sys/param.h>
72 #include <sys/systm.h>
73 #include <sys/proc.h>		/* for curproc, pageproc */
74 #include <sys/vnode.h>
75 #include <sys/vmmeter.h>
76 #include <sys/mman.h>
77 #include <sys/mount.h>
78 
79 #include <vm/vm.h>
80 #include <vm/vm_param.h>
81 #include <vm/vm_prot.h>
82 #include <vm/pmap.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_object.h>
85 #include <vm/vm_page.h>
86 #include <vm/vm_pageout.h>
87 #include <vm/vm_pager.h>
88 #include <vm/swap_pager.h>
89 #include <vm/vm_kern.h>
90 #include <vm/vm_extern.h>
91 #include <vm/vm_zone.h>
92 
93 static void	vm_object_qcollapse __P((vm_object_t object));
94 
95 /*
96  *	Virtual memory objects maintain the actual data
97  *	associated with allocated virtual memory.  A given
98  *	page of memory exists within exactly one object.
99  *
100  *	An object is only deallocated when all "references"
101  *	are given up.  Only one "reference" to a given
102  *	region of an object should be writeable.
103  *
104  *	Associated with each object is a list of all resident
105  *	memory pages belonging to that object; this list is
106  *	maintained by the "vm_page" module, and locked by the object's
107  *	lock.
108  *
109  *	Each object also records a "pager" routine which is
110  *	used to retrieve (and store) pages to the proper backing
111  *	storage.  In addition, objects may be backed by other
112  *	objects from which they were virtual-copied.
113  *
114  *	The only items within the object structure which are
115  *	modified after time of creation are:
116  *		reference count		locked by object's lock
117  *		pager routine		locked by object's lock
118  *
119  */
120 
121 struct object_q vm_object_list;
122 #ifndef NULL_SIMPLELOCKS
123 static struct simplelock vm_object_list_lock;
124 #endif
125 static long vm_object_count;		/* count of all objects */
126 vm_object_t kernel_object;
127 vm_object_t kmem_object;
128 static struct vm_object kernel_object_store;
129 static struct vm_object kmem_object_store;
130 extern int vm_pageout_page_count;
131 
132 static long object_collapses;
133 static long object_bypasses;
134 static int next_index;
135 static vm_zone_t obj_zone;
136 static struct vm_zone obj_zone_store;
137 static int object_hash_rand;
138 #define VM_OBJECTS_INIT 256
139 static struct vm_object vm_objects_init[VM_OBJECTS_INIT];
140 
141 void
142 _vm_object_allocate(type, size, object)
143 	objtype_t type;
144 	vm_size_t size;
145 	vm_object_t object;
146 {
147 	int incr;
148 	TAILQ_INIT(&object->memq);
149 	TAILQ_INIT(&object->shadow_head);
150 
151 	object->type = type;
152 	object->size = size;
153 	object->ref_count = 1;
154 	object->flags = 0;
155 	if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
156 		vm_object_set_flag(object, OBJ_ONEMAPPING);
157 	object->paging_in_progress = 0;
158 	object->resident_page_count = 0;
159 	object->shadow_count = 0;
160 	object->pg_color = next_index;
161 	if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
162 		incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
163 	else
164 		incr = size;
165 	next_index = (next_index + incr) & PQ_L2_MASK;
166 	object->handle = NULL;
167 	object->backing_object = NULL;
168 	object->backing_object_offset = (vm_ooffset_t) 0;
169 	/*
170 	 * Try to generate a number that will spread objects out in the
171 	 * hash table.  We 'wipe' new objects across the hash in 128 page
172 	 * increments plus 1 more to offset it a little more by the time
173 	 * it wraps around.
174 	 */
175 	object->hash_rand = object_hash_rand - 129;
176 
177 	object->generation++;
178 
179 	TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
180 	vm_object_count++;
181 	object_hash_rand = object->hash_rand;
182 }
183 
184 /*
185  *	vm_object_init:
186  *
187  *	Initialize the VM objects module.
188  */
189 void
190 vm_object_init()
191 {
192 	TAILQ_INIT(&vm_object_list);
193 	simple_lock_init(&vm_object_list_lock);
194 	vm_object_count = 0;
195 
196 	kernel_object = &kernel_object_store;
197 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
198 	    kernel_object);
199 
200 	kmem_object = &kmem_object_store;
201 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
202 	    kmem_object);
203 
204 	obj_zone = &obj_zone_store;
205 	zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object),
206 		vm_objects_init, VM_OBJECTS_INIT);
207 }
208 
209 void
210 vm_object_init2() {
211 	zinitna(obj_zone, NULL, NULL, 0, 0, 0, 1);
212 }
213 
214 /*
215  *	vm_object_allocate:
216  *
217  *	Returns a new object with the given size.
218  */
219 
220 vm_object_t
221 vm_object_allocate(type, size)
222 	objtype_t type;
223 	vm_size_t size;
224 {
225 	vm_object_t result;
226 
227 	result = (vm_object_t) zalloc(obj_zone);
228 
229 	_vm_object_allocate(type, size, result);
230 
231 	return (result);
232 }
233 
234 
235 /*
236  *	vm_object_reference:
237  *
238  *	Gets another reference to the given object.
239  */
240 void
241 vm_object_reference(object)
242 	vm_object_t object;
243 {
244 	if (object == NULL)
245 		return;
246 
247 	KASSERT(!(object->flags & OBJ_DEAD),
248 	    ("vm_object_reference: attempting to reference dead obj"));
249 
250 	object->ref_count++;
251 	if (object->type == OBJT_VNODE) {
252 		while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curproc)) {
253 #if !defined(MAX_PERF)
254 			printf("vm_object_reference: delay in getting object\n");
255 #endif
256 		}
257 	}
258 }
259 
260 void
261 vm_object_vndeallocate(object)
262 	vm_object_t object;
263 {
264 	struct vnode *vp = (struct vnode *) object->handle;
265 
266 	KASSERT(object->type == OBJT_VNODE,
267 	    ("vm_object_vndeallocate: not a vnode object"));
268 	KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
269 #ifdef INVARIANTS
270 	if (object->ref_count == 0) {
271 		vprint("vm_object_vndeallocate", vp);
272 		panic("vm_object_vndeallocate: bad object reference count");
273 	}
274 #endif
275 
276 	object->ref_count--;
277 	if (object->ref_count == 0) {
278 		vp->v_flag &= ~VTEXT;
279 		vm_object_clear_flag(object, OBJ_OPT);
280 	}
281 	vrele(vp);
282 }
283 
284 /*
285  *	vm_object_deallocate:
286  *
287  *	Release a reference to the specified object,
288  *	gained either through a vm_object_allocate
289  *	or a vm_object_reference call.  When all references
290  *	are gone, storage associated with this object
291  *	may be relinquished.
292  *
293  *	No object may be locked.
294  */
295 void
296 vm_object_deallocate(object)
297 	vm_object_t object;
298 {
299 	vm_object_t temp;
300 
301 	while (object != NULL) {
302 
303 		if (object->type == OBJT_VNODE) {
304 			vm_object_vndeallocate(object);
305 			return;
306 		}
307 
308 		if (object->ref_count == 0) {
309 			panic("vm_object_deallocate: object deallocated too many times: %d", object->type);
310 		} else if (object->ref_count > 2) {
311 			object->ref_count--;
312 			return;
313 		}
314 
315 		/*
316 		 * Here on ref_count of one or two, which are special cases for
317 		 * objects.
318 		 */
319 		if ((object->ref_count == 2) && (object->shadow_count == 0)) {
320 			vm_object_set_flag(object, OBJ_ONEMAPPING);
321 			object->ref_count--;
322 			return;
323 		} else if ((object->ref_count == 2) && (object->shadow_count == 1)) {
324 			object->ref_count--;
325 			if ((object->handle == NULL) &&
326 			    (object->type == OBJT_DEFAULT ||
327 			     object->type == OBJT_SWAP)) {
328 				vm_object_t robject;
329 
330 				robject = TAILQ_FIRST(&object->shadow_head);
331 				KASSERT(robject != NULL,
332 				    ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
333 					 object->ref_count,
334 					 object->shadow_count));
335 				if ((robject->handle == NULL) &&
336 				    (robject->type == OBJT_DEFAULT ||
337 				     robject->type == OBJT_SWAP)) {
338 
339 					robject->ref_count++;
340 
341 					while (
342 						robject->paging_in_progress ||
343 						object->paging_in_progress
344 					) {
345 						vm_object_pip_sleep(robject, "objde1");
346 						vm_object_pip_sleep(object, "objde2");
347 					}
348 
349 					if (robject->ref_count == 1) {
350 						robject->ref_count--;
351 						object = robject;
352 						goto doterm;
353 					}
354 
355 					object = robject;
356 					vm_object_collapse(object);
357 					continue;
358 				}
359 			}
360 
361 			return;
362 
363 		} else {
364 			object->ref_count--;
365 			if (object->ref_count != 0)
366 				return;
367 		}
368 
369 doterm:
370 
371 		temp = object->backing_object;
372 		if (temp) {
373 			TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
374 			temp->shadow_count--;
375 			if (temp->ref_count == 0)
376 				vm_object_clear_flag(temp, OBJ_OPT);
377 			temp->generation++;
378 			object->backing_object = NULL;
379 		}
380 		vm_object_terminate(object);
381 		/* unlocks and deallocates object */
382 		object = temp;
383 	}
384 }
385 
386 /*
387  *	vm_object_terminate actually destroys the specified object, freeing
388  *	up all previously used resources.
389  *
390  *	The object must be locked.
391  *	This routine may block.
392  */
393 void
394 vm_object_terminate(object)
395 	vm_object_t object;
396 {
397 	vm_page_t p;
398 	int s;
399 
400 	/*
401 	 * Make sure no one uses us.
402 	 */
403 	vm_object_set_flag(object, OBJ_DEAD);
404 
405 	/*
406 	 * wait for the pageout daemon to be done with the object
407 	 */
408 	vm_object_pip_wait(object, "objtrm");
409 
410 	KASSERT(!object->paging_in_progress,
411 		("vm_object_terminate: pageout in progress"));
412 
413 	/*
414 	 * Clean and free the pages, as appropriate. All references to the
415 	 * object are gone, so we don't need to lock it.
416 	 */
417 	if (object->type == OBJT_VNODE) {
418 		struct vnode *vp;
419 
420 		/*
421 		 * Freeze optimized copies.
422 		 */
423 		vm_freeze_copyopts(object, 0, object->size);
424 
425 		/*
426 		 * Clean pages and flush buffers.
427 		 */
428 		vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
429 
430 		vp = (struct vnode *) object->handle;
431 		vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
432 	}
433 
434 	if (object->ref_count != 0)
435 		panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count);
436 
437 	/*
438 	 * Now free any remaining pages. For internal objects, this also
439 	 * removes them from paging queues. Don't free wired pages, just
440 	 * remove them from the object.
441 	 */
442 	s = splvm();
443 	while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
444 #if !defined(MAX_PERF)
445 		if (p->busy || (p->flags & PG_BUSY))
446 			panic("vm_object_terminate: freeing busy page %p\n", p);
447 #endif
448 		if (p->wire_count == 0) {
449 			vm_page_busy(p);
450 			vm_page_free(p);
451 			cnt.v_pfree++;
452 		} else {
453 			vm_page_busy(p);
454 			vm_page_remove(p);
455 		}
456 	}
457 	splx(s);
458 
459 	/*
460 	 * Let the pager know object is dead.
461 	 */
462 	vm_pager_deallocate(object);
463 
464 	/*
465 	 * Remove the object from the global object list.
466 	 */
467 	simple_lock(&vm_object_list_lock);
468 	TAILQ_REMOVE(&vm_object_list, object, object_list);
469 	simple_unlock(&vm_object_list_lock);
470 
471 	wakeup(object);
472 
473 	/*
474 	 * Free the space for the object.
475 	 */
476 	zfree(obj_zone, object);
477 }
478 
479 /*
480  *	vm_object_page_clean
481  *
482  *	Clean all dirty pages in the specified range of object.
483  *	Leaves page on whatever queue it is currently on.
484  *
485  *	Odd semantics: if start == end, we clean everything.
486  *
487  *	The object must be locked.
488  */
489 
490 void
491 vm_object_page_clean(object, start, end, flags)
492 	vm_object_t object;
493 	vm_pindex_t start;
494 	vm_pindex_t end;
495 	int flags;
496 {
497 	vm_page_t p, np, tp;
498 	vm_offset_t tstart, tend;
499 	vm_pindex_t pi;
500 	int s;
501 	struct vnode *vp;
502 	int runlen;
503 	int maxf;
504 	int chkb;
505 	int maxb;
506 	int i;
507 	int pagerflags;
508 	vm_page_t maf[vm_pageout_page_count];
509 	vm_page_t mab[vm_pageout_page_count];
510 	vm_page_t ma[vm_pageout_page_count];
511 	int curgeneration;
512 
513 	if (object->type != OBJT_VNODE ||
514 		(object->flags & OBJ_MIGHTBEDIRTY) == 0)
515 		return;
516 
517 	pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : 0;
518 	pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
519 
520 	vp = object->handle;
521 
522 	vm_object_set_flag(object, OBJ_CLEANING);
523 
524 	tstart = start;
525 	if (end == 0) {
526 		tend = object->size;
527 	} else {
528 		tend = end;
529 	}
530 
531 	for(p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) {
532 		vm_page_flag_set(p, PG_CLEANCHK);
533 		vm_page_protect(p, VM_PROT_READ);
534 	}
535 
536 	if ((tstart == 0) && (tend == object->size)) {
537 		vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
538 	}
539 
540 rescan:
541 	curgeneration = object->generation;
542 
543 	for(p = TAILQ_FIRST(&object->memq); p; p = np) {
544 		np = TAILQ_NEXT(p, listq);
545 
546 		pi = p->pindex;
547 		if (((p->flags & PG_CLEANCHK) == 0) ||
548 			(pi < tstart) || (pi >= tend) ||
549 			(p->valid == 0) ||
550 			((p->queue - p->pc) == PQ_CACHE)) {
551 			vm_page_flag_clear(p, PG_CLEANCHK);
552 			continue;
553 		}
554 
555 		vm_page_test_dirty(p);
556 		if ((p->dirty & p->valid) == 0) {
557 			vm_page_flag_clear(p, PG_CLEANCHK);
558 			continue;
559 		}
560 
561 		s = splvm();
562 		while (vm_page_sleep_busy(p, TRUE, "vpcwai")) {
563 			if (object->generation != curgeneration) {
564 				splx(s);
565 				goto rescan;
566 			}
567 		}
568 
569 		maxf = 0;
570 		for(i=1;i<vm_pageout_page_count;i++) {
571 			if ((tp = vm_page_lookup(object, pi + i)) != NULL) {
572 				if ((tp->flags & PG_BUSY) ||
573 					(tp->flags & PG_CLEANCHK) == 0 ||
574 					(tp->busy != 0))
575 					break;
576 				if((tp->queue - tp->pc) == PQ_CACHE) {
577 					vm_page_flag_clear(tp, PG_CLEANCHK);
578 					break;
579 				}
580 				vm_page_test_dirty(tp);
581 				if ((tp->dirty & tp->valid) == 0) {
582 					vm_page_flag_clear(tp, PG_CLEANCHK);
583 					break;
584 				}
585 				maf[ i - 1 ] = tp;
586 				maxf++;
587 				continue;
588 			}
589 			break;
590 		}
591 
592 		maxb = 0;
593 		chkb = vm_pageout_page_count -  maxf;
594 		if (chkb) {
595 			for(i = 1; i < chkb;i++) {
596 				if ((tp = vm_page_lookup(object, pi - i)) != NULL) {
597 					if ((tp->flags & PG_BUSY) ||
598 						(tp->flags & PG_CLEANCHK) == 0 ||
599 						(tp->busy != 0))
600 						break;
601 					if((tp->queue - tp->pc) == PQ_CACHE) {
602 						vm_page_flag_clear(tp, PG_CLEANCHK);
603 						break;
604 					}
605 					vm_page_test_dirty(tp);
606 					if ((tp->dirty & tp->valid) == 0) {
607 						vm_page_flag_clear(tp, PG_CLEANCHK);
608 						break;
609 					}
610 					mab[ i - 1 ] = tp;
611 					maxb++;
612 					continue;
613 				}
614 				break;
615 			}
616 		}
617 
618 		for(i=0;i<maxb;i++) {
619 			int index = (maxb - i) - 1;
620 			ma[index] = mab[i];
621 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
622 		}
623 		vm_page_flag_clear(p, PG_CLEANCHK);
624 		ma[maxb] = p;
625 		for(i=0;i<maxf;i++) {
626 			int index = (maxb + i) + 1;
627 			ma[index] = maf[i];
628 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
629 		}
630 		runlen = maxb + maxf + 1;
631 
632 		splx(s);
633 		vm_pageout_flush(ma, runlen, pagerflags);
634 		for (i = 0; i<runlen; i++) {
635 			if (ma[i]->valid & ma[i]->dirty) {
636 				vm_page_protect(ma[i], VM_PROT_READ);
637 				vm_page_flag_set(ma[i], PG_CLEANCHK);
638 			}
639 		}
640 		if (object->generation != curgeneration)
641 			goto rescan;
642 	}
643 
644 	VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);
645 
646 	vm_object_clear_flag(object, OBJ_CLEANING);
647 	return;
648 }
649 
650 #ifdef not_used
651 /* XXX I cannot tell if this should be an exported symbol */
652 /*
653  *	vm_object_deactivate_pages
654  *
655  *	Deactivate all pages in the specified object.  (Keep its pages
656  *	in memory even though it is no longer referenced.)
657  *
658  *	The object must be locked.
659  */
660 static void
661 vm_object_deactivate_pages(object)
662 	vm_object_t object;
663 {
664 	vm_page_t p, next;
665 
666 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
667 		next = TAILQ_NEXT(p, listq);
668 		vm_page_deactivate(p);
669 	}
670 }
671 #endif
672 
673 /*
674  * Same as vm_object_pmap_copy, except range checking really
675  * works, and is meant for small sections of an object.
676  *
677  * This code protects resident pages by making them read-only
678  * and is typically called on a fork or split when a page
679  * is converted to copy-on-write.
680  *
681  * NOTE: If the page is already at VM_PROT_NONE, calling
682  * vm_page_protect will have no effect.
683  */
684 
685 void
686 vm_object_pmap_copy_1(object, start, end)
687 	vm_object_t object;
688 	vm_pindex_t start;
689 	vm_pindex_t end;
690 {
691 	vm_pindex_t idx;
692 	vm_page_t p;
693 
694 	if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
695 		return;
696 
697 	for (idx = start; idx < end; idx++) {
698 		p = vm_page_lookup(object, idx);
699 		if (p == NULL)
700 			continue;
701 		vm_page_protect(p, VM_PROT_READ);
702 	}
703 }
704 
705 /*
706  *	vm_object_pmap_remove:
707  *
708  *	Removes all physical pages in the specified
709  *	object range from all physical maps.
710  *
711  *	The object must *not* be locked.
712  */
713 void
714 vm_object_pmap_remove(object, start, end)
715 	vm_object_t object;
716 	vm_pindex_t start;
717 	vm_pindex_t end;
718 {
719 	vm_page_t p;
720 
721 	if (object == NULL)
722 		return;
723 	for (p = TAILQ_FIRST(&object->memq);
724 		p != NULL;
725 		p = TAILQ_NEXT(p, listq)) {
726 		if (p->pindex >= start && p->pindex < end)
727 			vm_page_protect(p, VM_PROT_NONE);
728 	}
729 	if ((start == 0) && (object->size == end))
730 		vm_object_clear_flag(object, OBJ_WRITEABLE);
731 }
732 
733 /*
734  *	vm_object_madvise:
735  *
736  *	Implements the madvise function at the object/page level.
737  *
738  *	MADV_WILLNEED	(any object)
739  *
740  *	    Activate the specified pages if they are resident.
741  *
742  *	MADV_DONTNEED	(any object)
743  *
744  *	    Deactivate the specified pages if they are resident.
745  *
746  *	MADV_FREE	(OBJT_DEFAULT/OBJT_SWAP objects,
747  *			 OBJ_ONEMAPPING only)
748  *
749  *	    Deactivate and clean the specified pages if they are
750  *	    resident.  This permits the process to reuse the pages
751  *	    without faulting or the kernel to reclaim the pages
752  *	    without I/O.
753  */
754 void
755 vm_object_madvise(object, pindex, count, advise)
756 	vm_object_t object;
757 	vm_pindex_t pindex;
758 	int count;
759 	int advise;
760 {
761 	vm_pindex_t end, tpindex;
762 	vm_object_t tobject;
763 	vm_page_t m;
764 
765 	if (object == NULL)
766 		return;
767 
768 	end = pindex + count;
769 
770 	/*
771 	 * Locate and adjust resident pages
772 	 */
773 
774 	for (; pindex < end; pindex += 1) {
775 relookup:
776 		tobject = object;
777 		tpindex = pindex;
778 shadowlookup:
779 		/*
780 		 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
781 		 * and those pages must be OBJ_ONEMAPPING.
782 		 */
783 		if (advise == MADV_FREE) {
784 			if ((tobject->type != OBJT_DEFAULT &&
785 			     tobject->type != OBJT_SWAP) ||
786 			    (tobject->flags & OBJ_ONEMAPPING) == 0) {
787 				continue;
788 			}
789 		}
790 
791 		m = vm_page_lookup(tobject, tpindex);
792 
793 		if (m == NULL) {
794 			/*
795 			 * There may be swap even if there is no backing page
796 			 */
797 			if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
798 				swap_pager_freespace(tobject, tpindex, 1);
799 
800 			/*
801 			 * next object
802 			 */
803 			tobject = tobject->backing_object;
804 			if (tobject == NULL)
805 				continue;
806 			tpindex += OFF_TO_IDX(tobject->backing_object_offset);
807 			goto shadowlookup;
808 		}
809 
810 		/*
811 		 * If the page is busy or not in a normal active state,
812 		 * we skip it.  Things can break if we mess with pages
813 		 * in any of the below states.
814 		 */
815 		if (
816 		    m->hold_count ||
817 		    m->wire_count ||
818 		    m->valid != VM_PAGE_BITS_ALL
819 		) {
820 			continue;
821 		}
822 
823  		if (vm_page_sleep_busy(m, TRUE, "madvpo"))
824   			goto relookup;
825 
826 		if (advise == MADV_WILLNEED) {
827 			vm_page_activate(m);
828 		} else if (advise == MADV_DONTNEED) {
829 			vm_page_deactivate(m);
830 		} else if (advise == MADV_FREE) {
831 			/*
832 			 * Mark the page clean.  This will allow the page
833 			 * to be freed up by the system.  However, such pages
834 			 * are often reused quickly by malloc()/free()
835 			 * so we do not do anything that would cause
836 			 * a page fault if we can help it.
837 			 *
838 			 * Specifically, we do not try to actually free
839 			 * the page now nor do we try to put it in the
840 			 * cache (which would cause a page fault on reuse).
841 			 *
842 			 * But we do make the page is freeable as we
843 			 * can without actually taking the step of unmapping
844 			 * it.
845 			 */
846 			pmap_clear_modify(VM_PAGE_TO_PHYS(m));
847 			m->dirty = 0;
848 			m->act_count = 0;
849 			vm_page_deactivate(m);
850 			if (tobject->type == OBJT_SWAP)
851 				swap_pager_freespace(tobject, tpindex, 1);
852 		}
853 	}
854 }
855 
856 /*
857  *	vm_object_shadow:
858  *
859  *	Create a new object which is backed by the
860  *	specified existing object range.  The source
861  *	object reference is deallocated.
862  *
863  *	The new object and offset into that object
864  *	are returned in the source parameters.
865  */
866 
867 void
868 vm_object_shadow(object, offset, length)
869 	vm_object_t *object;	/* IN/OUT */
870 	vm_ooffset_t *offset;	/* IN/OUT */
871 	vm_size_t length;
872 {
873 	vm_object_t source;
874 	vm_object_t result;
875 
876 	source = *object;
877 
878 	/*
879 	 * Don't create the new object if the old object isn't shared.
880 	 */
881 
882 	if (source != NULL &&
883 	    source->ref_count == 1 &&
884 	    source->handle == NULL &&
885 	    (source->type == OBJT_DEFAULT ||
886 	     source->type == OBJT_SWAP))
887 		return;
888 
889 	KASSERT((source->flags & OBJ_ONEMAPPING) == 0,
890 		("vm_object_shadow: source object has OBJ_ONEMAPPING set.\n"));
891 
892 	/*
893 	 * Allocate a new object with the given length
894 	 */
895 
896 	if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL)
897 		panic("vm_object_shadow: no object for shadowing");
898 
899 	/*
900 	 * The new object shadows the source object, adding a reference to it.
901 	 * Our caller changes his reference to point to the new object,
902 	 * removing a reference to the source object.  Net result: no change
903 	 * of reference count.
904 	 *
905 	 * Try to optimize the result object's page color when shadowing
906 	 * in order to maintain page coloring consistancy in the combined
907 	 * shadowed object.
908 	 */
909 	result->backing_object = source;
910 	if (source) {
911 		TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
912 		source->shadow_count++;
913 		source->generation++;
914 		result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK;
915 	}
916 
917 	/*
918 	 * Store the offset into the source object, and fix up the offset into
919 	 * the new object.
920 	 */
921 
922 	result->backing_object_offset = *offset;
923 
924 	/*
925 	 * Return the new things
926 	 */
927 
928 	*offset = 0;
929 	*object = result;
930 }
931 
932 #define	OBSC_TEST_ALL_SHADOWED	0x0001
933 #define	OBSC_COLLAPSE_NOWAIT	0x0002
934 #define	OBSC_COLLAPSE_WAIT	0x0004
935 
936 static __inline int
937 vm_object_backing_scan(vm_object_t object, int op)
938 {
939 	int s;
940 	int r = 1;
941 	vm_page_t p;
942 	vm_object_t backing_object;
943 	vm_pindex_t backing_offset_index;
944 
945 	s = splvm();
946 
947 	backing_object = object->backing_object;
948 	backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
949 
950 	/*
951 	 * Initial conditions
952 	 */
953 
954 	if (op & OBSC_TEST_ALL_SHADOWED) {
955 		/*
956 		 * We do not want to have to test for the existance of
957 		 * swap pages in the backing object.  XXX but with the
958 		 * new swapper this would be pretty easy to do.
959 		 *
960 		 * XXX what about anonymous MAP_SHARED memory that hasn't
961 		 * been ZFOD faulted yet?  If we do not test for this, the
962 		 * shadow test may succeed! XXX
963 		 */
964 		if (backing_object->type != OBJT_DEFAULT) {
965 			splx(s);
966 			return(0);
967 		}
968 	}
969 	if (op & OBSC_COLLAPSE_WAIT) {
970 		vm_object_set_flag(backing_object, OBJ_DEAD);
971 	}
972 
973 	/*
974 	 * Our scan
975 	 */
976 
977 	p = TAILQ_FIRST(&backing_object->memq);
978 	while (p) {
979 		vm_page_t next = TAILQ_NEXT(p, listq);
980 		vm_pindex_t new_pindex = p->pindex - backing_offset_index;
981 
982 		if (op & OBSC_TEST_ALL_SHADOWED) {
983 			vm_page_t pp;
984 
985 			/*
986 			 * Ignore pages outside the parent object's range
987 			 * and outside the parent object's mapping of the
988 			 * backing object.
989 			 *
990 			 * note that we do not busy the backing object's
991 			 * page.
992 			 */
993 
994 			if (
995 			    p->pindex < backing_offset_index ||
996 			    new_pindex >= object->size
997 			) {
998 				p = next;
999 				continue;
1000 			}
1001 
1002 			/*
1003 			 * See if the parent has the page or if the parent's
1004 			 * object pager has the page.  If the parent has the
1005 			 * page but the page is not valid, the parent's
1006 			 * object pager must have the page.
1007 			 *
1008 			 * If this fails, the parent does not completely shadow
1009 			 * the object and we might as well give up now.
1010 			 */
1011 
1012 			pp = vm_page_lookup(object, new_pindex);
1013 			if (
1014 			    (pp == NULL || pp->valid == 0) &&
1015 			    !vm_pager_has_page(object, new_pindex, NULL, NULL)
1016 			) {
1017 				r = 0;
1018 				break;
1019 			}
1020 		}
1021 
1022 		/*
1023 		 * Check for busy page
1024 		 */
1025 
1026 		if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1027 			vm_page_t pp;
1028 
1029 			if (op & OBSC_COLLAPSE_NOWAIT) {
1030 				if (
1031 				    (p->flags & PG_BUSY) ||
1032 				    !p->valid ||
1033 				    p->hold_count ||
1034 				    p->wire_count ||
1035 				    p->busy
1036 				) {
1037 					p = next;
1038 					continue;
1039 				}
1040 			} else if (op & OBSC_COLLAPSE_WAIT) {
1041 				if (vm_page_sleep_busy(p, TRUE, "vmocol")) {
1042 					/*
1043 					 * If we slept, anything could have
1044 					 * happened.  Since the object is
1045 					 * marked dead, the backing offset
1046 					 * should not have changed so we
1047 					 * just restart our scan.
1048 					 */
1049 					p = TAILQ_FIRST(&backing_object->memq);
1050 					continue;
1051 				}
1052 			}
1053 
1054 			/*
1055 			 * Busy the page
1056 			 */
1057 			vm_page_busy(p);
1058 
1059 			KASSERT(
1060 			    p->object == backing_object,
1061 			    ("vm_object_qcollapse(): object mismatch")
1062 			);
1063 
1064 			/*
1065 			 * Destroy any associated swap
1066 			 */
1067 			if (backing_object->type == OBJT_SWAP) {
1068 				swap_pager_freespace(
1069 				    backing_object,
1070 				    p->pindex,
1071 				    1
1072 				);
1073 			}
1074 
1075 			if (
1076 			    p->pindex < backing_offset_index ||
1077 			    new_pindex >= object->size
1078 			) {
1079 				/*
1080 				 * Page is out of the parent object's range, we
1081 				 * can simply destroy it.
1082 				 */
1083 				vm_page_protect(p, VM_PROT_NONE);
1084 				vm_page_free(p);
1085 				p = next;
1086 				continue;
1087 			}
1088 
1089 			pp = vm_page_lookup(object, new_pindex);
1090 			if (
1091 			    pp != NULL ||
1092 			    vm_pager_has_page(object, new_pindex, NULL, NULL)
1093 			) {
1094 				/*
1095 				 * page already exists in parent OR swap exists
1096 				 * for this location in the parent.  Destroy
1097 				 * the original page from the backing object.
1098 				 *
1099 				 * Leave the parent's page alone
1100 				 */
1101 				vm_page_protect(p, VM_PROT_NONE);
1102 				vm_page_free(p);
1103 				p = next;
1104 				continue;
1105 			}
1106 
1107 			/*
1108 			 * Page does not exist in parent, rename the
1109 			 * page from the backing object to the main object.
1110 			 *
1111 			 * If the page was mapped to a process, it can remain
1112 			 * mapped through the rename.
1113 			 */
1114 			if ((p->queue - p->pc) == PQ_CACHE)
1115 				vm_page_deactivate(p);
1116 
1117 			vm_page_rename(p, object, new_pindex);
1118 			/* page automatically made dirty by rename */
1119 		}
1120 		p = next;
1121 	}
1122 	splx(s);
1123 	return(r);
1124 }
1125 
1126 
1127 /*
1128  * this version of collapse allows the operation to occur earlier and
1129  * when paging_in_progress is true for an object...  This is not a complete
1130  * operation, but should plug 99.9% of the rest of the leaks.
1131  */
1132 static void
1133 vm_object_qcollapse(object)
1134 	vm_object_t object;
1135 {
1136 	vm_object_t backing_object = object->backing_object;
1137 
1138 	if (backing_object->ref_count != 1)
1139 		return;
1140 
1141 	backing_object->ref_count += 2;
1142 
1143 	vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1144 
1145 	backing_object->ref_count -= 2;
1146 }
1147 
1148 /*
1149  *	vm_object_collapse:
1150  *
1151  *	Collapse an object with the object backing it.
1152  *	Pages in the backing object are moved into the
1153  *	parent, and the backing object is deallocated.
1154  */
1155 void
1156 vm_object_collapse(object)
1157 	vm_object_t object;
1158 {
1159 	while (TRUE) {
1160 		vm_object_t backing_object;
1161 
1162 		/*
1163 		 * Verify that the conditions are right for collapse:
1164 		 *
1165 		 * The object exists and the backing object exists.
1166 		 */
1167 		if (object == NULL)
1168 			break;
1169 
1170 		if ((backing_object = object->backing_object) == NULL)
1171 			break;
1172 
1173 		/*
1174 		 * we check the backing object first, because it is most likely
1175 		 * not collapsable.
1176 		 */
1177 		if (backing_object->handle != NULL ||
1178 		    (backing_object->type != OBJT_DEFAULT &&
1179 		     backing_object->type != OBJT_SWAP) ||
1180 		    (backing_object->flags & OBJ_DEAD) ||
1181 		    object->handle != NULL ||
1182 		    (object->type != OBJT_DEFAULT &&
1183 		     object->type != OBJT_SWAP) ||
1184 		    (object->flags & OBJ_DEAD)) {
1185 			break;
1186 		}
1187 
1188 		if (
1189 		    object->paging_in_progress != 0 ||
1190 		    backing_object->paging_in_progress != 0
1191 		) {
1192 			vm_object_qcollapse(object);
1193 			break;
1194 		}
1195 
1196 		/*
1197 		 * We know that we can either collapse the backing object (if
1198 		 * the parent is the only reference to it) or (perhaps) have
1199 		 * the parent bypass the object if the parent happens to shadow
1200 		 * all the resident pages in the entire backing object.
1201 		 *
1202 		 * This is ignoring pager-backed pages such as swap pages.
1203 		 * vm_object_backing_scan fails the shadowing test in this
1204 		 * case.
1205 		 */
1206 
1207 		if (backing_object->ref_count == 1) {
1208 			/*
1209 			 * If there is exactly one reference to the backing
1210 			 * object, we can collapse it into the parent.
1211 			 */
1212 
1213 			vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1214 
1215 			/*
1216 			 * Move the pager from backing_object to object.
1217 			 */
1218 
1219 			if (backing_object->type == OBJT_SWAP) {
1220 				vm_object_pip_add(backing_object, 1);
1221 
1222 				/*
1223 				 * scrap the paging_offset junk and do a
1224 				 * discrete copy.  This also removes major
1225 				 * assumptions about how the swap-pager
1226 				 * works from where it doesn't belong.  The
1227 				 * new swapper is able to optimize the
1228 				 * destroy-source case.
1229 				 */
1230 
1231 				vm_object_pip_add(object, 1);
1232 				swap_pager_copy(
1233 				    backing_object,
1234 				    object,
1235 				    OFF_TO_IDX(object->backing_object_offset), TRUE);
1236 				vm_object_pip_wakeup(object);
1237 
1238 				vm_object_pip_wakeup(backing_object);
1239 			}
1240 			/*
1241 			 * Object now shadows whatever backing_object did.
1242 			 * Note that the reference to
1243 			 * backing_object->backing_object moves from within
1244 			 * backing_object to within object.
1245 			 */
1246 
1247 			TAILQ_REMOVE(
1248 			    &object->backing_object->shadow_head,
1249 			    object,
1250 			    shadow_list
1251 			);
1252 			object->backing_object->shadow_count--;
1253 			object->backing_object->generation++;
1254 			if (backing_object->backing_object) {
1255 				TAILQ_REMOVE(
1256 				    &backing_object->backing_object->shadow_head,
1257 				    backing_object,
1258 				    shadow_list
1259 				);
1260 				backing_object->backing_object->shadow_count--;
1261 				backing_object->backing_object->generation++;
1262 			}
1263 			object->backing_object = backing_object->backing_object;
1264 			if (object->backing_object) {
1265 				TAILQ_INSERT_TAIL(
1266 				    &object->backing_object->shadow_head,
1267 				    object,
1268 				    shadow_list
1269 				);
1270 				object->backing_object->shadow_count++;
1271 				object->backing_object->generation++;
1272 			}
1273 
1274 			object->backing_object_offset +=
1275 			    backing_object->backing_object_offset;
1276 
1277 			/*
1278 			 * Discard backing_object.
1279 			 *
1280 			 * Since the backing object has no pages, no pager left,
1281 			 * and no object references within it, all that is
1282 			 * necessary is to dispose of it.
1283 			 */
1284 
1285 			TAILQ_REMOVE(
1286 			    &vm_object_list,
1287 			    backing_object,
1288 			    object_list
1289 			);
1290 			vm_object_count--;
1291 
1292 			zfree(obj_zone, backing_object);
1293 
1294 			object_collapses++;
1295 		} else {
1296 			vm_object_t new_backing_object;
1297 
1298 			/*
1299 			 * If we do not entirely shadow the backing object,
1300 			 * there is nothing we can do so we give up.
1301 			 */
1302 
1303 			if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) {
1304 				break;
1305 			}
1306 
1307 			/*
1308 			 * Make the parent shadow the next object in the
1309 			 * chain.  Deallocating backing_object will not remove
1310 			 * it, since its reference count is at least 2.
1311 			 */
1312 
1313 			TAILQ_REMOVE(
1314 			    &backing_object->shadow_head,
1315 			    object,
1316 			    shadow_list
1317 			);
1318 			backing_object->shadow_count--;
1319 			backing_object->generation++;
1320 
1321 			new_backing_object = backing_object->backing_object;
1322 			if ((object->backing_object = new_backing_object) != NULL) {
1323 				vm_object_reference(new_backing_object);
1324 				TAILQ_INSERT_TAIL(
1325 				    &new_backing_object->shadow_head,
1326 				    object,
1327 				    shadow_list
1328 				);
1329 				new_backing_object->shadow_count++;
1330 				new_backing_object->generation++;
1331 				object->backing_object_offset +=
1332 					backing_object->backing_object_offset;
1333 			}
1334 
1335 			/*
1336 			 * Drop the reference count on backing_object. Since
1337 			 * its ref_count was at least 2, it will not vanish;
1338 			 * so we don't need to call vm_object_deallocate, but
1339 			 * we do anyway.
1340 			 */
1341 			vm_object_deallocate(backing_object);
1342 			object_bypasses++;
1343 		}
1344 
1345 		/*
1346 		 * Try again with this object's new backing object.
1347 		 */
1348 	}
1349 }
1350 
1351 /*
1352  *	vm_object_page_remove: [internal]
1353  *
1354  *	Removes all physical pages in the specified
1355  *	object range from the object's list of pages.
1356  *
1357  *	The object must be locked.
1358  */
1359 void
1360 vm_object_page_remove(object, start, end, clean_only)
1361 	vm_object_t object;
1362 	vm_pindex_t start;
1363 	vm_pindex_t end;
1364 	boolean_t clean_only;
1365 {
1366 	vm_page_t p, next;
1367 	unsigned int size;
1368 	int all;
1369 
1370 	if (object == NULL ||
1371 	    object->resident_page_count == 0)
1372 		return;
1373 
1374 	all = ((end == 0) && (start == 0));
1375 
1376 	vm_object_pip_add(object, 1);
1377 again:
1378 	size = end - start;
1379 	if (all || size > object->resident_page_count / 4) {
1380 		for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
1381 			next = TAILQ_NEXT(p, listq);
1382 			if (all || ((start <= p->pindex) && (p->pindex < end))) {
1383 				if (p->wire_count != 0) {
1384 					vm_page_protect(p, VM_PROT_NONE);
1385 					if (!clean_only)
1386 						p->valid = 0;
1387 					continue;
1388 				}
1389 
1390 				/*
1391 				 * The busy flags are only cleared at
1392 				 * interrupt -- minimize the spl transitions
1393 				 */
1394 
1395  				if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1396  					goto again;
1397 
1398 				if (clean_only && p->valid) {
1399 					vm_page_test_dirty(p);
1400 					if (p->valid & p->dirty)
1401 						continue;
1402 				}
1403 
1404 				vm_page_busy(p);
1405 				vm_page_protect(p, VM_PROT_NONE);
1406 				vm_page_free(p);
1407 			}
1408 		}
1409 	} else {
1410 		while (size > 0) {
1411 			if ((p = vm_page_lookup(object, start)) != 0) {
1412 
1413 				if (p->wire_count != 0) {
1414 					vm_page_protect(p, VM_PROT_NONE);
1415 					if (!clean_only)
1416 						p->valid = 0;
1417 					start += 1;
1418 					size -= 1;
1419 					continue;
1420 				}
1421 
1422 				/*
1423 				 * The busy flags are only cleared at
1424 				 * interrupt -- minimize the spl transitions
1425 				 */
1426  				if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1427 					goto again;
1428 
1429 				if (clean_only && p->valid) {
1430 					vm_page_test_dirty(p);
1431 					if (p->valid & p->dirty) {
1432 						start += 1;
1433 						size -= 1;
1434 						continue;
1435 					}
1436 				}
1437 
1438 				vm_page_busy(p);
1439 				vm_page_protect(p, VM_PROT_NONE);
1440 				vm_page_free(p);
1441 			}
1442 			start += 1;
1443 			size -= 1;
1444 		}
1445 	}
1446 	vm_object_pip_wakeup(object);
1447 }
1448 
1449 /*
1450  *	Routine:	vm_object_coalesce
1451  *	Function:	Coalesces two objects backing up adjoining
1452  *			regions of memory into a single object.
1453  *
1454  *	returns TRUE if objects were combined.
1455  *
1456  *	NOTE:	Only works at the moment if the second object is NULL -
1457  *		if it's not, which object do we lock first?
1458  *
1459  *	Parameters:
1460  *		prev_object	First object to coalesce
1461  *		prev_offset	Offset into prev_object
1462  *		next_object	Second object into coalesce
1463  *		next_offset	Offset into next_object
1464  *
1465  *		prev_size	Size of reference to prev_object
1466  *		next_size	Size of reference to next_object
1467  *
1468  *	Conditions:
1469  *	The object must *not* be locked.
1470  */
1471 boolean_t
1472 vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size)
1473 	vm_object_t prev_object;
1474 	vm_pindex_t prev_pindex;
1475 	vm_size_t prev_size, next_size;
1476 {
1477 	vm_pindex_t next_pindex;
1478 
1479 	if (prev_object == NULL) {
1480 		return (TRUE);
1481 	}
1482 
1483 	if (prev_object->type != OBJT_DEFAULT &&
1484 	    prev_object->type != OBJT_SWAP) {
1485 		return (FALSE);
1486 	}
1487 
1488 	/*
1489 	 * Try to collapse the object first
1490 	 */
1491 	vm_object_collapse(prev_object);
1492 
1493 	/*
1494 	 * Can't coalesce if: . more than one reference . paged out . shadows
1495 	 * another object . has a copy elsewhere (any of which mean that the
1496 	 * pages not mapped to prev_entry may be in use anyway)
1497 	 */
1498 
1499 	if (prev_object->backing_object != NULL) {
1500 		return (FALSE);
1501 	}
1502 
1503 	prev_size >>= PAGE_SHIFT;
1504 	next_size >>= PAGE_SHIFT;
1505 	next_pindex = prev_pindex + prev_size;
1506 
1507 	if ((prev_object->ref_count > 1) &&
1508 	    (prev_object->size != next_pindex)) {
1509 		return (FALSE);
1510 	}
1511 
1512 	/*
1513 	 * Remove any pages that may still be in the object from a previous
1514 	 * deallocation.
1515 	 */
1516 	if (next_pindex < prev_object->size) {
1517 		vm_object_page_remove(prev_object,
1518 				      next_pindex,
1519 				      next_pindex + next_size, FALSE);
1520 		if (prev_object->type == OBJT_SWAP)
1521 			swap_pager_freespace(prev_object,
1522 					     next_pindex, next_size);
1523 	}
1524 
1525 	/*
1526 	 * Extend the object if necessary.
1527 	 */
1528 	if (next_pindex + next_size > prev_object->size)
1529 		prev_object->size = next_pindex + next_size;
1530 
1531 	return (TRUE);
1532 }
1533 
1534 #include "opt_ddb.h"
1535 #ifdef DDB
1536 #include <sys/kernel.h>
1537 
1538 #include <sys/cons.h>
1539 
1540 #include <ddb/ddb.h>
1541 
1542 static int	_vm_object_in_map __P((vm_map_t map, vm_object_t object,
1543 				       vm_map_entry_t entry));
1544 static int	vm_object_in_map __P((vm_object_t object));
1545 
1546 static int
1547 _vm_object_in_map(map, object, entry)
1548 	vm_map_t map;
1549 	vm_object_t object;
1550 	vm_map_entry_t entry;
1551 {
1552 	vm_map_t tmpm;
1553 	vm_map_entry_t tmpe;
1554 	vm_object_t obj;
1555 	int entcount;
1556 
1557 	if (map == 0)
1558 		return 0;
1559 
1560 	if (entry == 0) {
1561 		tmpe = map->header.next;
1562 		entcount = map->nentries;
1563 		while (entcount-- && (tmpe != &map->header)) {
1564 			if( _vm_object_in_map(map, object, tmpe)) {
1565 				return 1;
1566 			}
1567 			tmpe = tmpe->next;
1568 		}
1569 	} else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
1570 		tmpm = entry->object.sub_map;
1571 		tmpe = tmpm->header.next;
1572 		entcount = tmpm->nentries;
1573 		while (entcount-- && tmpe != &tmpm->header) {
1574 			if( _vm_object_in_map(tmpm, object, tmpe)) {
1575 				return 1;
1576 			}
1577 			tmpe = tmpe->next;
1578 		}
1579 	} else if ((obj = entry->object.vm_object) != NULL) {
1580 		for(; obj; obj=obj->backing_object)
1581 			if( obj == object) {
1582 				return 1;
1583 			}
1584 	}
1585 	return 0;
1586 }
1587 
1588 static int
1589 vm_object_in_map( object)
1590 	vm_object_t object;
1591 {
1592 	struct proc *p;
1593 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
1594 		if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
1595 			continue;
1596 		if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0))
1597 			return 1;
1598 	}
1599 	if( _vm_object_in_map( kernel_map, object, 0))
1600 		return 1;
1601 	if( _vm_object_in_map( kmem_map, object, 0))
1602 		return 1;
1603 	if( _vm_object_in_map( pager_map, object, 0))
1604 		return 1;
1605 	if( _vm_object_in_map( buffer_map, object, 0))
1606 		return 1;
1607 	if( _vm_object_in_map( phys_map, object, 0))
1608 		return 1;
1609 	if( _vm_object_in_map( mb_map, object, 0))
1610 		return 1;
1611 	return 0;
1612 }
1613 
1614 DB_SHOW_COMMAND(vmochk, vm_object_check)
1615 {
1616 	vm_object_t object;
1617 
1618 	/*
1619 	 * make sure that internal objs are in a map somewhere
1620 	 * and none have zero ref counts.
1621 	 */
1622 	for (object = TAILQ_FIRST(&vm_object_list);
1623 			object != NULL;
1624 			object = TAILQ_NEXT(object, object_list)) {
1625 		if (object->handle == NULL &&
1626 		    (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
1627 			if (object->ref_count == 0) {
1628 				db_printf("vmochk: internal obj has zero ref count: %ld\n",
1629 					(long)object->size);
1630 			}
1631 			if (!vm_object_in_map(object)) {
1632 				db_printf(
1633 			"vmochk: internal obj is not in a map: "
1634 			"ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
1635 				    object->ref_count, (u_long)object->size,
1636 				    (u_long)object->size,
1637 				    (void *)object->backing_object);
1638 			}
1639 		}
1640 	}
1641 }
1642 
1643 /*
1644  *	vm_object_print:	[ debug ]
1645  */
1646 DB_SHOW_COMMAND(object, vm_object_print_static)
1647 {
1648 	/* XXX convert args. */
1649 	vm_object_t object = (vm_object_t)addr;
1650 	boolean_t full = have_addr;
1651 
1652 	vm_page_t p;
1653 
1654 	/* XXX count is an (unused) arg.  Avoid shadowing it. */
1655 #define	count	was_count
1656 
1657 	int count;
1658 
1659 	if (object == NULL)
1660 		return;
1661 
1662 	db_iprintf(
1663 	    "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
1664 	    object, (int)object->type, (u_long)object->size,
1665 	    object->resident_page_count, object->ref_count, object->flags);
1666 	/*
1667 	 * XXX no %qd in kernel.  Truncate object->backing_object_offset.
1668 	 */
1669 	db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
1670 	    object->shadow_count,
1671 	    object->backing_object ? object->backing_object->ref_count : 0,
1672 	    object->backing_object, (long)object->backing_object_offset);
1673 
1674 	if (!full)
1675 		return;
1676 
1677 	db_indent += 2;
1678 	count = 0;
1679 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) {
1680 		if (count == 0)
1681 			db_iprintf("memory:=");
1682 		else if (count == 6) {
1683 			db_printf("\n");
1684 			db_iprintf(" ...");
1685 			count = 0;
1686 		} else
1687 			db_printf(",");
1688 		count++;
1689 
1690 		db_printf("(off=0x%lx,page=0x%lx)",
1691 		    (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
1692 	}
1693 	if (count != 0)
1694 		db_printf("\n");
1695 	db_indent -= 2;
1696 }
1697 
1698 /* XXX. */
1699 #undef count
1700 
1701 /* XXX need this non-static entry for calling from vm_map_print. */
1702 void
1703 vm_object_print(addr, have_addr, count, modif)
1704         /* db_expr_t */ long addr;
1705 	boolean_t have_addr;
1706 	/* db_expr_t */ long count;
1707 	char *modif;
1708 {
1709 	vm_object_print_static(addr, have_addr, count, modif);
1710 }
1711 
1712 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
1713 {
1714 	vm_object_t object;
1715 	int nl = 0;
1716 	int c;
1717 	for (object = TAILQ_FIRST(&vm_object_list);
1718 			object != NULL;
1719 			object = TAILQ_NEXT(object, object_list)) {
1720 		vm_pindex_t idx, fidx;
1721 		vm_pindex_t osize;
1722 		vm_offset_t pa = -1, padiff;
1723 		int rcount;
1724 		vm_page_t m;
1725 
1726 		db_printf("new object: %p\n", (void *)object);
1727 		if ( nl > 18) {
1728 			c = cngetc();
1729 			if (c != ' ')
1730 				return;
1731 			nl = 0;
1732 		}
1733 		nl++;
1734 		rcount = 0;
1735 		fidx = 0;
1736 		osize = object->size;
1737 		if (osize > 128)
1738 			osize = 128;
1739 		for(idx=0;idx<osize;idx++) {
1740 			m = vm_page_lookup(object, idx);
1741 			if (m == NULL) {
1742 				if (rcount) {
1743 					db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
1744 						(long)fidx, rcount, (long)pa);
1745 					if ( nl > 18) {
1746 						c = cngetc();
1747 						if (c != ' ')
1748 							return;
1749 						nl = 0;
1750 					}
1751 					nl++;
1752 					rcount = 0;
1753 				}
1754 				continue;
1755 			}
1756 
1757 
1758 			if (rcount &&
1759 				(VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
1760 				++rcount;
1761 				continue;
1762 			}
1763 			if (rcount) {
1764 				padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
1765 				padiff >>= PAGE_SHIFT;
1766 				padiff &= PQ_L2_MASK;
1767 				if (padiff == 0) {
1768 					pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
1769 					++rcount;
1770 					continue;
1771 				}
1772 				db_printf(" index(%ld)run(%d)pa(0x%lx)",
1773 					(long)fidx, rcount, (long)pa);
1774 				db_printf("pd(%ld)\n", (long)padiff);
1775 				if ( nl > 18) {
1776 					c = cngetc();
1777 					if (c != ' ')
1778 						return;
1779 					nl = 0;
1780 				}
1781 				nl++;
1782 			}
1783 			fidx = idx;
1784 			pa = VM_PAGE_TO_PHYS(m);
1785 			rcount = 1;
1786 		}
1787 		if (rcount) {
1788 			db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
1789 				(long)fidx, rcount, (long)pa);
1790 			if ( nl > 18) {
1791 				c = cngetc();
1792 				if (c != ' ')
1793 					return;
1794 				nl = 0;
1795 			}
1796 			nl++;
1797 		}
1798 	}
1799 }
1800 #endif /* DDB */
1801