xref: /freebsd/sys/vm/vm_object.c (revision 0640d357f29fb1c0daaaffadd0416c5981413afd)
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 1.133 1998/10/25 17:44:58 phk 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 static struct simplelock vm_object_list_lock;
123 static long vm_object_count;		/* count of all objects */
124 vm_object_t kernel_object;
125 vm_object_t kmem_object;
126 static struct vm_object kernel_object_store;
127 static struct vm_object kmem_object_store;
128 extern int vm_pageout_page_count;
129 
130 static long object_collapses;
131 static long object_bypasses;
132 static int next_index;
133 static vm_zone_t obj_zone;
134 static struct vm_zone obj_zone_store;
135 #define VM_OBJECTS_INIT 256
136 static struct vm_object vm_objects_init[VM_OBJECTS_INIT];
137 static int objidnumber;
138 
139 void
140 _vm_object_allocate(type, size, object)
141 	objtype_t type;
142 	vm_size_t size;
143 	register vm_object_t object;
144 {
145 	int incr;
146 	TAILQ_INIT(&object->memq);
147 	TAILQ_INIT(&object->shadow_head);
148 
149 	object->type = type;
150 	object->size = size;
151 	object->ref_count = 1;
152 	object->flags = 0;
153 	object->id = ++objidnumber;
154 	if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
155 		vm_object_set_flag(object, OBJ_ONEMAPPING);
156 	object->behavior = OBJ_NORMAL;
157 	object->paging_in_progress = 0;
158 	object->resident_page_count = 0;
159 	object->cache_count = 0;
160 	object->wire_count = 0;
161 	object->shadow_count = 0;
162 	object->pg_color = next_index;
163 	if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
164 		incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
165 	else
166 		incr = size;
167 	next_index = (next_index + incr) & PQ_L2_MASK;
168 	object->handle = NULL;
169 	object->paging_offset = (vm_ooffset_t) 0;
170 	object->backing_object = NULL;
171 	object->backing_object_offset = (vm_ooffset_t) 0;
172 	object->page_hint = NULL;
173 
174 	object->last_read = 0;
175 	object->generation++;
176 
177 	TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
178 	vm_object_count++;
179 }
180 
181 /*
182  *	vm_object_init:
183  *
184  *	Initialize the VM objects module.
185  */
186 void
187 vm_object_init()
188 {
189 	TAILQ_INIT(&vm_object_list);
190 	simple_lock_init(&vm_object_list_lock);
191 	vm_object_count = 0;
192 
193 	kernel_object = &kernel_object_store;
194 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
195 	    kernel_object);
196 
197 	kmem_object = &kmem_object_store;
198 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
199 	    kmem_object);
200 
201 	obj_zone = &obj_zone_store;
202 	zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object),
203 		vm_objects_init, VM_OBJECTS_INIT);
204 }
205 
206 void
207 vm_object_init2() {
208 	zinitna(obj_zone, NULL, NULL, 0, 0, 0, 1);
209 }
210 
211 /*
212  *	vm_object_allocate:
213  *
214  *	Returns a new object with the given size.
215  */
216 
217 vm_object_t
218 vm_object_allocate(type, size)
219 	objtype_t type;
220 	vm_size_t size;
221 {
222 	register vm_object_t result;
223 	result = (vm_object_t) zalloc(obj_zone);
224 
225 	_vm_object_allocate(type, size, result);
226 
227 	return (result);
228 }
229 
230 
231 /*
232  *	vm_object_reference:
233  *
234  *	Gets another reference to the given object.
235  */
236 void
237 vm_object_reference(object)
238 	register vm_object_t object;
239 {
240 	if (object == NULL)
241 		return;
242 
243 #if defined(DIAGNOSTIC)
244 	if (object->flags & OBJ_DEAD)
245 		panic("vm_object_reference: attempting to reference dead obj");
246 #endif
247 
248 	object->ref_count++;
249 	if (object->type == OBJT_VNODE) {
250 		while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curproc)) {
251 #if !defined(MAX_PERF)
252 			printf("vm_object_reference: delay in getting object\n");
253 #endif
254 		}
255 	}
256 }
257 
258 void
259 vm_object_vndeallocate(object)
260 	vm_object_t object;
261 {
262 	struct vnode *vp = (struct vnode *) object->handle;
263 #if defined(DIAGNOSTIC)
264 	if (object->type != OBJT_VNODE)
265 		panic("vm_object_vndeallocate: not a vnode object");
266 	if (vp == NULL)
267 		panic("vm_object_vndeallocate: missing vp");
268 	if (object->ref_count == 0) {
269 		vprint("vm_object_vndeallocate", vp);
270 		panic("vm_object_vndeallocate: bad object reference count");
271 	}
272 #endif
273 
274 	object->ref_count--;
275 	if (object->ref_count == 0) {
276 		vp->v_flag &= ~VTEXT;
277 		vm_object_clear_flag(object, OBJ_OPT);
278 	}
279 	vrele(vp);
280 }
281 
282 /*
283  *	vm_object_deallocate:
284  *
285  *	Release a reference to the specified object,
286  *	gained either through a vm_object_allocate
287  *	or a vm_object_reference call.  When all references
288  *	are gone, storage associated with this object
289  *	may be relinquished.
290  *
291  *	No object may be locked.
292  */
293 void
294 vm_object_deallocate(object)
295 	vm_object_t object;
296 {
297 	vm_object_t temp;
298 
299 	while (object != NULL) {
300 
301 		if (object->type == OBJT_VNODE) {
302 			vm_object_vndeallocate(object);
303 			return;
304 		}
305 
306 		if (object->ref_count == 0) {
307 			panic("vm_object_deallocate: object deallocated too many times: %d", object->type);
308 		} else if (object->ref_count > 2) {
309 			object->ref_count--;
310 			return;
311 		}
312 
313 		/*
314 		 * Here on ref_count of one or two, which are special cases for
315 		 * objects.
316 		 */
317 		if ((object->ref_count == 2) && (object->shadow_count == 0)) {
318 			vm_object_set_flag(object, OBJ_ONEMAPPING);
319 			object->ref_count--;
320 			return;
321 		} else if ((object->ref_count == 2) && (object->shadow_count == 1)) {
322 			object->ref_count--;
323 			if ((object->handle == NULL) &&
324 			    (object->type == OBJT_DEFAULT ||
325 			     object->type == OBJT_SWAP)) {
326 				vm_object_t robject;
327 
328 				robject = TAILQ_FIRST(&object->shadow_head);
329 #if defined(DIAGNOSTIC)
330 				if (robject == NULL)
331 					panic("vm_object_deallocate: ref_count: %d,"
332 						  " shadow_count: %d",
333 						  object->ref_count, object->shadow_count);
334 #endif
335 				if ((robject->handle == NULL) &&
336 				    (robject->type == OBJT_DEFAULT ||
337 				     robject->type == OBJT_SWAP)) {
338 
339 					robject->ref_count++;
340 
341 			retry:
342 					if (robject->paging_in_progress ||
343 							object->paging_in_progress) {
344 						vm_object_pip_sleep(robject, "objde1");
345 						if (robject->paging_in_progress &&
346 							robject->type == OBJT_SWAP) {
347 							swap_pager_sync();
348 							goto retry;
349 						}
350 
351 						vm_object_pip_sleep(object, "objde2");
352 						if (object->paging_in_progress &&
353 							object->type == OBJT_SWAP) {
354 							swap_pager_sync();
355 						}
356 						goto retry;
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 			TAILQ_REMOVE(&temp->shadow_head, 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 		vm_object_terminate(object);
391 		/* unlocks and deallocates object */
392 		object = temp;
393 	}
394 }
395 
396 /*
397  *	vm_object_terminate actually destroys the specified object, freeing
398  *	up all previously used resources.
399  *
400  *	The object must be locked.
401  */
402 void
403 vm_object_terminate(object)
404 	register vm_object_t object;
405 {
406 	register vm_page_t p;
407 	int s;
408 
409 	/*
410 	 * Make sure no one uses us.
411 	 */
412 	vm_object_set_flag(object, OBJ_DEAD);
413 
414 	/*
415 	 * wait for the pageout daemon to be done with the object
416 	 */
417 	vm_object_pip_wait(object, "objtrm");
418 
419 #if defined(DIAGNOSTIC)
420 	if (object->paging_in_progress != 0)
421 		panic("vm_object_terminate: pageout in progress");
422 #endif
423 
424 	/*
425 	 * Clean and free the pages, as appropriate. All references to the
426 	 * object are gone, so we don't need to lock it.
427 	 */
428 	if (object->type == OBJT_VNODE) {
429 		struct vnode *vp;
430 
431 		/*
432 		 * Freeze optimized copies.
433 		 */
434 		vm_freeze_copyopts(object, 0, object->size);
435 
436 		/*
437 		 * Clean pages and flush buffers.
438 		 */
439 		vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
440 
441 		vp = (struct vnode *) object->handle;
442 		vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
443 	}
444 
445 	if (object->ref_count != 0)
446 		panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count);
447 
448 	/*
449 	 * Now free any remaining pages. For internal objects, this also
450 	 * removes them from paging queues. Don't free wired pages, just
451 	 * remove them from the object.
452 	 */
453 	s = splvm();
454 	while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
455 #if !defined(MAX_PERF)
456 		if (p->busy || (p->flags & PG_BUSY))
457 			printf("vm_object_terminate: freeing busy page\n");
458 #endif
459 		if (p->wire_count == 0) {
460 			vm_page_busy(p);
461 			vm_page_free(p);
462 			cnt.v_pfree++;
463 		} else {
464 			if (!(p->flags & PG_FICTITIOUS))
465 				printf("vm_object_terminate: not freeing wired page; wire_count=%d\n", p->wire_count);
466 			vm_page_busy(p);
467 			vm_page_remove(p);
468 		}
469 	}
470 	splx(s);
471 
472 	/*
473 	 * Let the pager know object is dead.
474 	 */
475 	vm_pager_deallocate(object);
476 
477 	/*
478 	 * Remove the object from the global object list.
479 	 */
480 	simple_lock(&vm_object_list_lock);
481 	TAILQ_REMOVE(&vm_object_list, object, object_list);
482 	simple_unlock(&vm_object_list_lock);
483 
484 	wakeup(object);
485 
486 	/*
487 	 * Free the space for the object.
488 	 */
489 	zfree(obj_zone, object);
490 }
491 
492 /*
493  *	vm_object_page_clean
494  *
495  *	Clean all dirty pages in the specified range of object.
496  *	Leaves page on whatever queue it is currently on.
497  *
498  *	Odd semantics: if start == end, we clean everything.
499  *
500  *	The object must be locked.
501  */
502 
503 void
504 vm_object_page_clean(object, start, end, flags)
505 	vm_object_t object;
506 	vm_pindex_t start;
507 	vm_pindex_t end;
508 	int flags;
509 {
510 	register vm_page_t p, np, tp;
511 	register vm_offset_t tstart, tend;
512 	vm_pindex_t pi;
513 	int s;
514 	struct vnode *vp;
515 	int runlen;
516 	int maxf;
517 	int chkb;
518 	int maxb;
519 	int i;
520 	int pagerflags;
521 	vm_page_t maf[vm_pageout_page_count];
522 	vm_page_t mab[vm_pageout_page_count];
523 	vm_page_t ma[vm_pageout_page_count];
524 	int curgeneration;
525 
526 	if (object->type != OBJT_VNODE ||
527 		(object->flags & OBJ_MIGHTBEDIRTY) == 0)
528 		return;
529 
530 	pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : 0;
531 	pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
532 
533 	vp = object->handle;
534 
535 	vm_object_set_flag(object, OBJ_CLEANING);
536 
537 	tstart = start;
538 	if (end == 0) {
539 		tend = object->size;
540 	} else {
541 		tend = end;
542 	}
543 
544 	for(p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) {
545 		vm_page_flag_set(p, PG_CLEANCHK);
546 		vm_page_protect(p, VM_PROT_READ);
547 	}
548 
549 	if ((tstart == 0) && (tend == object->size)) {
550 		vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
551 	}
552 
553 rescan:
554 	curgeneration = object->generation;
555 
556 	for(p = TAILQ_FIRST(&object->memq); p; p = np) {
557 		np = TAILQ_NEXT(p, listq);
558 
559 		pi = p->pindex;
560 		if (((p->flags & PG_CLEANCHK) == 0) ||
561 			(pi < tstart) || (pi >= tend) ||
562 			(p->valid == 0) ||
563 			((p->queue - p->pc) == PQ_CACHE)) {
564 			vm_page_flag_clear(p, PG_CLEANCHK);
565 			continue;
566 		}
567 
568 		vm_page_test_dirty(p);
569 		if ((p->dirty & p->valid) == 0) {
570 			vm_page_flag_clear(p, PG_CLEANCHK);
571 			continue;
572 		}
573 
574 		s = splvm();
575 		while ((p->flags & PG_BUSY) || p->busy) {
576 			vm_page_flag_set(p, PG_WANTED | PG_REFERENCED);
577 			tsleep(p, PVM, "vpcwai", 0);
578 			if (object->generation != curgeneration) {
579 				splx(s);
580 				goto rescan;
581 			}
582 		}
583 
584 		maxf = 0;
585 		for(i=1;i<vm_pageout_page_count;i++) {
586 			if (tp = vm_page_lookup(object, pi + i)) {
587 				if ((tp->flags & PG_BUSY) ||
588 					(tp->flags & PG_CLEANCHK) == 0 ||
589 					(tp->busy != 0))
590 					break;
591 				if((tp->queue - tp->pc) == PQ_CACHE) {
592 					vm_page_flag_clear(tp, PG_CLEANCHK);
593 					break;
594 				}
595 				vm_page_test_dirty(tp);
596 				if ((tp->dirty & tp->valid) == 0) {
597 					vm_page_flag_clear(tp, PG_CLEANCHK);
598 					break;
599 				}
600 				maf[ i - 1 ] = tp;
601 				maxf++;
602 				continue;
603 			}
604 			break;
605 		}
606 
607 		maxb = 0;
608 		chkb = vm_pageout_page_count -  maxf;
609 		if (chkb) {
610 			for(i = 1; i < chkb;i++) {
611 				if (tp = vm_page_lookup(object, pi - i)) {
612 					if ((tp->flags & PG_BUSY) ||
613 						(tp->flags & PG_CLEANCHK) == 0 ||
614 						(tp->busy != 0))
615 						break;
616 					if((tp->queue - tp->pc) == PQ_CACHE) {
617 						vm_page_flag_clear(tp, PG_CLEANCHK);
618 						break;
619 					}
620 					vm_page_test_dirty(tp);
621 					if ((tp->dirty & tp->valid) == 0) {
622 						vm_page_flag_clear(tp, PG_CLEANCHK);
623 						break;
624 					}
625 					mab[ i - 1 ] = tp;
626 					maxb++;
627 					continue;
628 				}
629 				break;
630 			}
631 		}
632 
633 		for(i=0;i<maxb;i++) {
634 			int index = (maxb - i) - 1;
635 			ma[index] = mab[i];
636 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
637 		}
638 		vm_page_flag_clear(p, PG_CLEANCHK);
639 		ma[maxb] = p;
640 		for(i=0;i<maxf;i++) {
641 			int index = (maxb + i) + 1;
642 			ma[index] = maf[i];
643 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
644 		}
645 		runlen = maxb + maxf + 1;
646 
647 		splx(s);
648 		vm_pageout_flush(ma, runlen, pagerflags);
649 		for (i = 0; i<runlen; i++) {
650 			if (ma[i]->valid & ma[i]->dirty) {
651 				vm_page_protect(ma[i], VM_PROT_READ);
652 				vm_page_flag_set(ma[i], PG_CLEANCHK);
653 			}
654 		}
655 		if (object->generation != curgeneration)
656 			goto rescan;
657 	}
658 
659 	VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);
660 
661 	vm_object_clear_flag(object, OBJ_CLEANING);
662 	return;
663 }
664 
665 #ifdef not_used
666 /* XXX I cannot tell if this should be an exported symbol */
667 /*
668  *	vm_object_deactivate_pages
669  *
670  *	Deactivate all pages in the specified object.  (Keep its pages
671  *	in memory even though it is no longer referenced.)
672  *
673  *	The object must be locked.
674  */
675 static void
676 vm_object_deactivate_pages(object)
677 	register vm_object_t object;
678 {
679 	register vm_page_t p, next;
680 
681 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
682 		next = TAILQ_NEXT(p, listq);
683 		vm_page_deactivate(p);
684 	}
685 }
686 #endif
687 
688 /*
689  *	vm_object_pmap_copy:
690  *
691  *	Makes all physical pages in the specified
692  *	object range copy-on-write.  No writeable
693  *	references to these pages should remain.
694  *
695  *	The object must *not* be locked.
696  */
697 void
698 vm_object_pmap_copy(object, start, end)
699 	register vm_object_t object;
700 	register vm_pindex_t start;
701 	register vm_pindex_t end;
702 {
703 	register vm_page_t p;
704 
705 	if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
706 		return;
707 
708 	for (p = TAILQ_FIRST(&object->memq);
709 		p != NULL;
710 		p = TAILQ_NEXT(p, listq)) {
711 		vm_page_protect(p, VM_PROT_READ);
712 	}
713 
714 	vm_object_clear_flag(object, OBJ_WRITEABLE);
715 }
716 
717 /*
718  * Same as vm_object_pmap_copy_1, except range checking really
719  * works, and is meant for small sections of an object.
720  */
721 void
722 vm_object_pmap_copy_1(object, start, end)
723 	register vm_object_t object;
724 	register vm_pindex_t start;
725 	register vm_pindex_t end;
726 {
727 	vm_pindex_t idx;
728 	register vm_page_t p;
729 
730 	if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
731 		return;
732 
733 	for (idx = start; idx < end; idx++) {
734 		p = vm_page_lookup(object, idx);
735 		if (p == NULL)
736 			continue;
737 		vm_page_protect(p, VM_PROT_READ);
738 	}
739 }
740 
741 /*
742  *	vm_object_pmap_remove:
743  *
744  *	Removes all physical pages in the specified
745  *	object range from all physical maps.
746  *
747  *	The object must *not* be locked.
748  */
749 void
750 vm_object_pmap_remove(object, start, end)
751 	register vm_object_t object;
752 	register vm_pindex_t start;
753 	register vm_pindex_t end;
754 {
755 	register vm_page_t p;
756 	if (object == NULL)
757 		return;
758 	for (p = TAILQ_FIRST(&object->memq);
759 		p != NULL;
760 		p = TAILQ_NEXT(p, listq)) {
761 		if (p->pindex >= start && p->pindex < end)
762 			vm_page_protect(p, VM_PROT_NONE);
763 	}
764 	if ((start == 0) && (object->size == end))
765 		vm_object_clear_flag(object, OBJ_WRITEABLE);
766 }
767 
768 /*
769  *	vm_object_madvise:
770  *
771  *	Implements the madvise function at the object/page level.
772  */
773 void
774 vm_object_madvise(object, pindex, count, advise)
775 	vm_object_t object;
776 	vm_pindex_t pindex;
777 	int count;
778 	int advise;
779 {
780 	vm_pindex_t end, tpindex;
781 	vm_object_t tobject;
782 	vm_page_t m;
783 
784 	if (object == NULL)
785 		return;
786 
787 	end = pindex + count;
788 
789 	for (; pindex < end; pindex += 1) {
790 
791 relookup:
792 		tobject = object;
793 		tpindex = pindex;
794 shadowlookup:
795 		m = vm_page_lookup(tobject, tpindex);
796 		if (m == NULL) {
797 			if (tobject->type != OBJT_DEFAULT) {
798 				continue;
799 			}
800 
801 			tobject = tobject->backing_object;
802 			if ((tobject == NULL) || (tobject->ref_count != 1)) {
803 				continue;
804 			}
805 			tpindex += OFF_TO_IDX(tobject->backing_object_offset);
806 			goto shadowlookup;
807 		}
808 
809 		/*
810 		 * If the page is busy or not in a normal active state,
811 		 * we skip it.  Things can break if we mess with pages
812 		 * in any of the below states.
813 		 */
814 		if (m->hold_count || m->wire_count ||
815 			m->valid != VM_PAGE_BITS_ALL) {
816 			continue;
817 		}
818 
819  		if (vm_page_sleep(m, "madvpo", &m->busy))
820   			goto relookup;
821 
822 		if (advise == MADV_WILLNEED) {
823 			vm_page_activate(m);
824 		} else if (advise == MADV_DONTNEED) {
825 			vm_page_deactivate(m);
826 		} else if (advise == MADV_FREE) {
827 			pmap_clear_modify(VM_PAGE_TO_PHYS(m));
828 			m->dirty = 0;
829 			/*
830 			 * Force a demand zero if attempt to read from swap.
831 			 * We currently don't handle vnode files correctly,
832 			 * and will reread stale contents unnecessarily.
833 			 */
834 			if (object->type == OBJT_SWAP)
835 				swap_pager_dmzspace(tobject, m->pindex, 1);
836 		}
837 	}
838 }
839 
840 /*
841  *	vm_object_shadow:
842  *
843  *	Create a new object which is backed by the
844  *	specified existing object range.  The source
845  *	object reference is deallocated.
846  *
847  *	The new object and offset into that object
848  *	are returned in the source parameters.
849  */
850 
851 void
852 vm_object_shadow(object, offset, length)
853 	vm_object_t *object;	/* IN/OUT */
854 	vm_ooffset_t *offset;	/* IN/OUT */
855 	vm_size_t length;
856 {
857 	register vm_object_t source;
858 	register vm_object_t result;
859 
860 	source = *object;
861 
862 	/*
863 	 * Allocate a new object with the given length
864 	 */
865 
866 	if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL)
867 		panic("vm_object_shadow: no object for shadowing");
868 
869 	/*
870 	 * The new object shadows the source object, adding a reference to it.
871 	 * Our caller changes his reference to point to the new object,
872 	 * removing a reference to the source object.  Net result: no change
873 	 * of reference count.
874 	 */
875 	result->backing_object = source;
876 	if (source) {
877 		TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
878 		vm_object_clear_flag(source, OBJ_ONEMAPPING);
879 		source->shadow_count++;
880 		source->generation++;
881 	}
882 
883 	/*
884 	 * Store the offset into the source object, and fix up the offset into
885 	 * the new object.
886 	 */
887 
888 	result->backing_object_offset = *offset;
889 
890 	/*
891 	 * Return the new things
892 	 */
893 
894 	*offset = 0;
895 	*object = result;
896 }
897 
898 
899 /*
900  * this version of collapse allows the operation to occur earlier and
901  * when paging_in_progress is true for an object...  This is not a complete
902  * operation, but should plug 99.9% of the rest of the leaks.
903  */
904 static void
905 vm_object_qcollapse(object)
906 	register vm_object_t object;
907 {
908 	register vm_object_t backing_object;
909 	register vm_pindex_t backing_offset_index, paging_offset_index;
910 	vm_pindex_t backing_object_paging_offset_index;
911 	vm_pindex_t new_pindex;
912 	register vm_page_t p, pp;
913 	register vm_size_t size;
914 
915 	backing_object = object->backing_object;
916 	if (backing_object->ref_count != 1)
917 		return;
918 
919 	backing_object->ref_count += 2;
920 
921 	backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
922 	backing_object_paging_offset_index = OFF_TO_IDX(backing_object->paging_offset);
923 	paging_offset_index = OFF_TO_IDX(object->paging_offset);
924 	size = object->size;
925 	p = TAILQ_FIRST(&backing_object->memq);
926 	while (p) {
927 		vm_page_t next;
928 
929 		next = TAILQ_NEXT(p, listq);
930 		if ((p->flags & (PG_BUSY | PG_FICTITIOUS)) ||
931 		    !p->valid || p->hold_count || p->wire_count || p->busy) {
932 			p = next;
933 			continue;
934 		}
935 		vm_page_busy(p);
936 
937 		new_pindex = p->pindex - backing_offset_index;
938 		if (p->pindex < backing_offset_index ||
939 		    new_pindex >= size) {
940 			if (backing_object->type == OBJT_SWAP)
941 				swap_pager_freespace(backing_object,
942 				    backing_object_paging_offset_index+p->pindex,
943 				    1);
944 			vm_page_protect(p, VM_PROT_NONE);
945 			vm_page_free(p);
946 		} else {
947 			pp = vm_page_lookup(object, new_pindex);
948 			if (pp != NULL ||
949 				(object->type == OBJT_SWAP && vm_pager_has_page(object,
950 				    paging_offset_index + new_pindex, NULL, NULL))) {
951 				if (backing_object->type == OBJT_SWAP)
952 					swap_pager_freespace(backing_object,
953 					    backing_object_paging_offset_index + p->pindex, 1);
954 				vm_page_protect(p, VM_PROT_NONE);
955 				vm_page_free(p);
956 			} else {
957 				if (backing_object->type == OBJT_SWAP)
958 					swap_pager_freespace(backing_object,
959 					    backing_object_paging_offset_index + p->pindex, 1);
960 
961 				if ((p->queue - p->pc) == PQ_CACHE)
962 					vm_page_deactivate(p);
963 				else
964 					vm_page_protect(p, VM_PROT_NONE);
965 
966 				vm_page_rename(p, object, new_pindex);
967 				p->dirty = VM_PAGE_BITS_ALL;
968 			}
969 		}
970 		p = next;
971 	}
972 	backing_object->ref_count -= 2;
973 }
974 
975 /*
976  *	vm_object_collapse:
977  *
978  *	Collapse an object with the object backing it.
979  *	Pages in the backing object are moved into the
980  *	parent, and the backing object is deallocated.
981  */
982 void
983 vm_object_collapse(object)
984 	vm_object_t object;
985 
986 {
987 	vm_object_t backing_object;
988 	vm_ooffset_t backing_offset;
989 	vm_size_t size;
990 	vm_pindex_t new_pindex, backing_offset_index;
991 	vm_page_t p, pp;
992 
993 	while (TRUE) {
994 		/*
995 		 * Verify that the conditions are right for collapse:
996 		 *
997 		 * The object exists and no pages in it are currently being paged
998 		 * out.
999 		 */
1000 		if (object == NULL)
1001 			return;
1002 
1003 		/*
1004 		 * Make sure there is a backing object.
1005 		 */
1006 		if ((backing_object = object->backing_object) == NULL)
1007 			return;
1008 
1009 		/*
1010 		 * we check the backing object first, because it is most likely
1011 		 * not collapsable.
1012 		 */
1013 		if (backing_object->handle != NULL ||
1014 		    (backing_object->type != OBJT_DEFAULT &&
1015 		     backing_object->type != OBJT_SWAP) ||
1016 		    (backing_object->flags & OBJ_DEAD) ||
1017 		    object->handle != NULL ||
1018 		    (object->type != OBJT_DEFAULT &&
1019 		     object->type != OBJT_SWAP) ||
1020 		    (object->flags & OBJ_DEAD)) {
1021 			return;
1022 		}
1023 
1024 		if (object->paging_in_progress != 0 ||
1025 		    backing_object->paging_in_progress != 0) {
1026 			vm_object_qcollapse(object);
1027 			return;
1028 		}
1029 
1030 		/*
1031 		 * We know that we can either collapse the backing object (if
1032 		 * the parent is the only reference to it) or (perhaps) remove
1033 		 * the parent's reference to it.
1034 		 */
1035 
1036 		backing_offset = object->backing_object_offset;
1037 		backing_offset_index = OFF_TO_IDX(backing_offset);
1038 		size = object->size;
1039 
1040 		/*
1041 		 * If there is exactly one reference to the backing object, we
1042 		 * can collapse it into the parent.
1043 		 */
1044 
1045 		if (backing_object->ref_count == 1) {
1046 
1047 			vm_object_set_flag(backing_object, OBJ_DEAD);
1048 			/*
1049 			 * We can collapse the backing object.
1050 			 *
1051 			 * Move all in-memory pages from backing_object to the
1052 			 * parent.  Pages that have been paged out will be
1053 			 * overwritten by any of the parent's pages that
1054 			 * shadow them.
1055 			 */
1056 
1057 			while ((p = TAILQ_FIRST(&backing_object->memq)) != 0) {
1058 
1059 				new_pindex = p->pindex - backing_offset_index;
1060 				vm_page_busy(p);
1061 
1062 				/*
1063 				 * If the parent has a page here, or if this
1064 				 * page falls outside the parent, dispose of
1065 				 * it.
1066 				 *
1067 				 * Otherwise, move it as planned.
1068 				 */
1069 
1070 				if (p->pindex < backing_offset_index ||
1071 				    new_pindex >= size) {
1072 					vm_page_protect(p, VM_PROT_NONE);
1073 					vm_page_free(p);
1074 				} else {
1075 					pp = vm_page_lookup(object, new_pindex);
1076 					if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object,
1077 					    OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL))) {
1078 						vm_page_protect(p, VM_PROT_NONE);
1079 						vm_page_free(p);
1080 					} else {
1081 						if ((p->queue - p->pc) == PQ_CACHE)
1082 							vm_page_deactivate(p);
1083 						else
1084 							vm_page_protect(p, VM_PROT_NONE);
1085 						vm_page_rename(p, object, new_pindex);
1086 						p->dirty = VM_PAGE_BITS_ALL;
1087 					}
1088 				}
1089 			}
1090 
1091 			/*
1092 			 * Move the pager from backing_object to object.
1093 			 */
1094 
1095 			if (backing_object->type == OBJT_SWAP) {
1096 				vm_object_pip_add(backing_object, 1);
1097 				if (object->type == OBJT_SWAP) {
1098 					vm_object_pip_add(object, 1);
1099 					/*
1100 					 * copy shadow object pages into ours
1101 					 * and destroy unneeded pages in
1102 					 * shadow object.
1103 					 */
1104 					swap_pager_copy(
1105 					    backing_object,
1106 					    OFF_TO_IDX(backing_object->paging_offset),
1107 					    object,
1108 					    OFF_TO_IDX(object->paging_offset),
1109 					    OFF_TO_IDX(object->backing_object_offset), TRUE);
1110 					vm_object_pip_wakeup(object);
1111 				} else {
1112 					vm_object_pip_add(object, 1);
1113 					/*
1114 					 * move the shadow backing_object's pager data to
1115 					 * "object" and convert "object" type to OBJT_SWAP.
1116 					 */
1117 					object->type = OBJT_SWAP;
1118 					object->un_pager.swp.swp_nblocks =
1119 					    backing_object->un_pager.swp.swp_nblocks;
1120 					object->un_pager.swp.swp_allocsize =
1121 					    backing_object->un_pager.swp.swp_allocsize;
1122 					object->un_pager.swp.swp_blocks =
1123 					    backing_object->un_pager.swp.swp_blocks;
1124 					object->un_pager.swp.swp_poip =		/* XXX */
1125 					    backing_object->un_pager.swp.swp_poip;
1126 					object->paging_offset = backing_object->paging_offset + backing_offset;
1127 					TAILQ_INSERT_TAIL(&swap_pager_un_object_list, object, pager_object_list);
1128 
1129 					/*
1130 					 * Convert backing object from OBJT_SWAP to
1131 					 * OBJT_DEFAULT. XXX - only the TAILQ_REMOVE is
1132 					 * actually necessary.
1133 					 */
1134 					backing_object->type = OBJT_DEFAULT;
1135 					TAILQ_REMOVE(&swap_pager_un_object_list, backing_object, pager_object_list);
1136 					/*
1137 					 * free unnecessary blocks
1138 					 */
1139 					swap_pager_freespace(object, 0,
1140 						OFF_TO_IDX(object->paging_offset));
1141 					vm_object_pip_wakeup(object);
1142 				}
1143 
1144 				vm_object_pip_wakeup(backing_object);
1145 			}
1146 			/*
1147 			 * Object now shadows whatever backing_object did.
1148 			 * Note that the reference to backing_object->backing_object
1149 			 * moves from within backing_object to within object.
1150 			 */
1151 
1152 			TAILQ_REMOVE(&object->backing_object->shadow_head, object,
1153 			    shadow_list);
1154 			object->backing_object->shadow_count--;
1155 			object->backing_object->generation++;
1156 			if (backing_object->backing_object) {
1157 				TAILQ_REMOVE(&backing_object->backing_object->shadow_head,
1158 				    backing_object, shadow_list);
1159 				backing_object->backing_object->shadow_count--;
1160 				backing_object->backing_object->generation++;
1161 			}
1162 			object->backing_object = backing_object->backing_object;
1163 			if (object->backing_object) {
1164 				TAILQ_INSERT_TAIL(&object->backing_object->shadow_head,
1165 				    object, shadow_list);
1166 				object->backing_object->shadow_count++;
1167 				object->backing_object->generation++;
1168 			}
1169 
1170 			object->backing_object_offset += backing_object->backing_object_offset;
1171 			/*
1172 			 * Discard backing_object.
1173 			 *
1174 			 * Since the backing object has no pages, no pager left,
1175 			 * and no object references within it, all that is
1176 			 * necessary is to dispose of it.
1177 			 */
1178 
1179 			TAILQ_REMOVE(&vm_object_list, backing_object,
1180 			    object_list);
1181 			vm_object_count--;
1182 
1183 			zfree(obj_zone, backing_object);
1184 
1185 			object_collapses++;
1186 		} else {
1187 			vm_object_t new_backing_object;
1188 			/*
1189 			 * If all of the pages in the backing object are
1190 			 * shadowed by the parent object, the parent object no
1191 			 * longer has to shadow the backing object; it can
1192 			 * shadow the next one in the chain.
1193 			 *
1194 			 * The backing object must not be paged out - we'd have
1195 			 * to check all of the paged-out pages, as well.
1196 			 */
1197 
1198 			if (backing_object->type != OBJT_DEFAULT) {
1199 				return;
1200 			}
1201 			/*
1202 			 * Should have a check for a 'small' number of pages
1203 			 * here.
1204 			 */
1205 
1206 			for (p = TAILQ_FIRST(&backing_object->memq); p;
1207 					p = TAILQ_NEXT(p, listq)) {
1208 
1209 				new_pindex = p->pindex - backing_offset_index;
1210 				vm_page_busy(p);
1211 
1212 				/*
1213 				 * If the parent has a page here, or if this
1214 				 * page falls outside the parent, keep going.
1215 				 *
1216 				 * Otherwise, the backing_object must be left in
1217 				 * the chain.
1218 				 */
1219 
1220 				if (p->pindex >= backing_offset_index &&
1221 					new_pindex <= size) {
1222 
1223 					pp = vm_page_lookup(object, new_pindex);
1224 
1225 					if ((pp == NULL) || (pp->flags & PG_BUSY) || pp->busy) {
1226 						vm_page_wakeup(p);
1227 						return;
1228 					}
1229 
1230 					vm_page_busy(pp);
1231 					if ((pp->valid == 0) &&
1232 				   	    !vm_pager_has_page(object, OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL)) {
1233 						/*
1234 						 * Page still needed. Can't go any
1235 						 * further.
1236 						 */
1237 						vm_page_wakeup(pp);
1238 						vm_page_wakeup(p);
1239 						return;
1240 					}
1241 					vm_page_wakeup(pp);
1242 				}
1243 				vm_page_wakeup(p);
1244 			}
1245 
1246 			/*
1247 			 * Make the parent shadow the next object in the
1248 			 * chain.  Deallocating backing_object will not remove
1249 			 * it, since its reference count is at least 2.
1250 			 */
1251 
1252 			TAILQ_REMOVE(&backing_object->shadow_head,
1253 			    object, shadow_list);
1254 			backing_object->shadow_count--;
1255 			backing_object->generation++;
1256 
1257 			new_backing_object = backing_object->backing_object;
1258 			if (object->backing_object = new_backing_object) {
1259 				vm_object_reference(new_backing_object);
1260 				TAILQ_INSERT_TAIL(&new_backing_object->shadow_head,
1261 				    object, shadow_list);
1262 				new_backing_object->shadow_count++;
1263 				new_backing_object->generation++;
1264 				object->backing_object_offset +=
1265 					backing_object->backing_object_offset;
1266 			}
1267 
1268 			/*
1269 			 * Drop the reference count on backing_object. Since
1270 			 * its ref_count was at least 2, it will not vanish;
1271 			 * so we don't need to call vm_object_deallocate, but
1272 			 * we do anyway.
1273 			 */
1274 			vm_object_deallocate(backing_object);
1275 			object_bypasses++;
1276 		}
1277 
1278 		/*
1279 		 * Try again with this object's new backing object.
1280 		 */
1281 	}
1282 }
1283 
1284 /*
1285  *	vm_object_page_remove: [internal]
1286  *
1287  *	Removes all physical pages in the specified
1288  *	object range from the object's list of pages.
1289  *
1290  *	The object must be locked.
1291  */
1292 void
1293 vm_object_page_remove(object, start, end, clean_only)
1294 	register vm_object_t object;
1295 	register vm_pindex_t start;
1296 	register vm_pindex_t end;
1297 	boolean_t clean_only;
1298 {
1299 	register vm_page_t p, next;
1300 	unsigned int size;
1301 	int all;
1302 
1303 	if (object == NULL)
1304 		return;
1305 
1306 	all = ((end == 0) && (start == 0));
1307 
1308 	vm_object_pip_add(object, 1);
1309 again:
1310 	size = end - start;
1311 	if (all || size > 4 || size >= object->size / 4) {
1312 		for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
1313 			next = TAILQ_NEXT(p, listq);
1314 			if (all || ((start <= p->pindex) && (p->pindex < end))) {
1315 				if (p->wire_count != 0) {
1316 					vm_page_protect(p, VM_PROT_NONE);
1317 					if (!clean_only)
1318 						p->valid = 0;
1319 					continue;
1320 				}
1321 
1322 				/*
1323 				 * The busy flags are only cleared at
1324 				 * interrupt -- minimize the spl transitions
1325 				 */
1326 
1327  				if (vm_page_sleep(p, "vmopar", &p->busy))
1328  					goto again;
1329 
1330 				if (clean_only && p->valid) {
1331 					vm_page_test_dirty(p);
1332 					if (p->valid & p->dirty)
1333 						continue;
1334 				}
1335 
1336 				vm_page_busy(p);
1337 				vm_page_protect(p, VM_PROT_NONE);
1338 				vm_page_free(p);
1339 			}
1340 		}
1341 	} else {
1342 		while (size > 0) {
1343 			if ((p = vm_page_lookup(object, start)) != 0) {
1344 
1345 				if (p->wire_count != 0) {
1346 					vm_page_protect(p, VM_PROT_NONE);
1347 					if (!clean_only)
1348 						p->valid = 0;
1349 					start += 1;
1350 					size -= 1;
1351 					continue;
1352 				}
1353 
1354 				/*
1355 				 * The busy flags are only cleared at
1356 				 * interrupt -- minimize the spl transitions
1357 				 */
1358  				if (vm_page_sleep(p, "vmopar", &p->busy))
1359 					goto again;
1360 
1361 				if (clean_only && p->valid) {
1362 					vm_page_test_dirty(p);
1363 					if (p->valid & p->dirty) {
1364 						start += 1;
1365 						size -= 1;
1366 						continue;
1367 					}
1368 				}
1369 
1370 				vm_page_busy(p);
1371 				vm_page_protect(p, VM_PROT_NONE);
1372 				vm_page_free(p);
1373 			}
1374 			start += 1;
1375 			size -= 1;
1376 		}
1377 	}
1378 	vm_object_pip_wakeup(object);
1379 }
1380 
1381 /*
1382  *	Routine:	vm_object_coalesce
1383  *	Function:	Coalesces two objects backing up adjoining
1384  *			regions of memory into a single object.
1385  *
1386  *	returns TRUE if objects were combined.
1387  *
1388  *	NOTE:	Only works at the moment if the second object is NULL -
1389  *		if it's not, which object do we lock first?
1390  *
1391  *	Parameters:
1392  *		prev_object	First object to coalesce
1393  *		prev_offset	Offset into prev_object
1394  *		next_object	Second object into coalesce
1395  *		next_offset	Offset into next_object
1396  *
1397  *		prev_size	Size of reference to prev_object
1398  *		next_size	Size of reference to next_object
1399  *
1400  *	Conditions:
1401  *	The object must *not* be locked.
1402  */
1403 boolean_t
1404 vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size)
1405 	register vm_object_t prev_object;
1406 	vm_pindex_t prev_pindex;
1407 	vm_size_t prev_size, next_size;
1408 {
1409 	vm_size_t newsize;
1410 
1411 	if (prev_object == NULL) {
1412 		return (TRUE);
1413 	}
1414 
1415 	if (prev_object->type != OBJT_DEFAULT) {
1416 		return (FALSE);
1417 	}
1418 
1419 	/*
1420 	 * Try to collapse the object first
1421 	 */
1422 	vm_object_collapse(prev_object);
1423 
1424 	/*
1425 	 * Can't coalesce if: . more than one reference . paged out . shadows
1426 	 * another object . has a copy elsewhere (any of which mean that the
1427 	 * pages not mapped to prev_entry may be in use anyway)
1428 	 */
1429 
1430 	if (prev_object->backing_object != NULL) {
1431 		return (FALSE);
1432 	}
1433 
1434 	prev_size >>= PAGE_SHIFT;
1435 	next_size >>= PAGE_SHIFT;
1436 
1437 	if ((prev_object->ref_count > 1) &&
1438 	    (prev_object->size != prev_pindex + prev_size)) {
1439 		return (FALSE);
1440 	}
1441 
1442 	/*
1443 	 * Remove any pages that may still be in the object from a previous
1444 	 * deallocation.
1445 	 */
1446 
1447 	vm_object_page_remove(prev_object,
1448 	    prev_pindex + prev_size,
1449 	    prev_pindex + prev_size + next_size, FALSE);
1450 
1451 	/*
1452 	 * Extend the object if necessary.
1453 	 */
1454 	newsize = prev_pindex + prev_size + next_size;
1455 	if (newsize > prev_object->size)
1456 		prev_object->size = newsize;
1457 
1458 	return (TRUE);
1459 }
1460 
1461 #include "opt_ddb.h"
1462 #ifdef DDB
1463 #include <sys/kernel.h>
1464 
1465 #include <machine/cons.h>
1466 
1467 #include <ddb/ddb.h>
1468 
1469 static int	_vm_object_in_map __P((vm_map_t map, vm_object_t object,
1470 				       vm_map_entry_t entry));
1471 static int	vm_object_in_map __P((vm_object_t object));
1472 
1473 static int
1474 _vm_object_in_map(map, object, entry)
1475 	vm_map_t map;
1476 	vm_object_t object;
1477 	vm_map_entry_t entry;
1478 {
1479 	vm_map_t tmpm;
1480 	vm_map_entry_t tmpe;
1481 	vm_object_t obj;
1482 	int entcount;
1483 
1484 	if (map == 0)
1485 		return 0;
1486 
1487 	if (entry == 0) {
1488 		tmpe = map->header.next;
1489 		entcount = map->nentries;
1490 		while (entcount-- && (tmpe != &map->header)) {
1491 			if( _vm_object_in_map(map, object, tmpe)) {
1492 				return 1;
1493 			}
1494 			tmpe = tmpe->next;
1495 		}
1496 	} else if (entry->eflags & (MAP_ENTRY_IS_A_MAP|MAP_ENTRY_IS_SUB_MAP)) {
1497 		tmpm = entry->object.share_map;
1498 		tmpe = tmpm->header.next;
1499 		entcount = tmpm->nentries;
1500 		while (entcount-- && tmpe != &tmpm->header) {
1501 			if( _vm_object_in_map(tmpm, object, tmpe)) {
1502 				return 1;
1503 			}
1504 			tmpe = tmpe->next;
1505 		}
1506 	} else if (obj = entry->object.vm_object) {
1507 		for(; obj; obj=obj->backing_object)
1508 			if( obj == object) {
1509 				return 1;
1510 			}
1511 	}
1512 	return 0;
1513 }
1514 
1515 static int
1516 vm_object_in_map( object)
1517 	vm_object_t object;
1518 {
1519 	struct proc *p;
1520 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
1521 		if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
1522 			continue;
1523 		if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0))
1524 			return 1;
1525 	}
1526 	if( _vm_object_in_map( kernel_map, object, 0))
1527 		return 1;
1528 	if( _vm_object_in_map( kmem_map, object, 0))
1529 		return 1;
1530 	if( _vm_object_in_map( pager_map, object, 0))
1531 		return 1;
1532 	if( _vm_object_in_map( buffer_map, object, 0))
1533 		return 1;
1534 	if( _vm_object_in_map( io_map, object, 0))
1535 		return 1;
1536 	if( _vm_object_in_map( phys_map, object, 0))
1537 		return 1;
1538 	if( _vm_object_in_map( mb_map, object, 0))
1539 		return 1;
1540 	if( _vm_object_in_map( u_map, object, 0))
1541 		return 1;
1542 	return 0;
1543 }
1544 
1545 DB_SHOW_COMMAND(vmochk, vm_object_check)
1546 {
1547 	vm_object_t object;
1548 
1549 	/*
1550 	 * make sure that internal objs are in a map somewhere
1551 	 * and none have zero ref counts.
1552 	 */
1553 	for (object = TAILQ_FIRST(&vm_object_list);
1554 			object != NULL;
1555 			object = TAILQ_NEXT(object, object_list)) {
1556 		if (object->handle == NULL &&
1557 		    (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
1558 			if (object->ref_count == 0) {
1559 				db_printf("vmochk: internal obj has zero ref count: %d\n",
1560 					object->size);
1561 			}
1562 			if (!vm_object_in_map(object)) {
1563 				db_printf(
1564 			"vmochk: internal obj is not in a map: "
1565 			"ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
1566 				    object->ref_count, (u_long)object->size,
1567 				    (u_long)object->size,
1568 				    (void *)object->backing_object);
1569 			}
1570 		}
1571 	}
1572 }
1573 
1574 /*
1575  *	vm_object_print:	[ debug ]
1576  */
1577 DB_SHOW_COMMAND(object, vm_object_print_static)
1578 {
1579 	/* XXX convert args. */
1580 	vm_object_t object = (vm_object_t)addr;
1581 	boolean_t full = have_addr;
1582 
1583 	register vm_page_t p;
1584 
1585 	/* XXX count is an (unused) arg.  Avoid shadowing it. */
1586 #define	count	was_count
1587 
1588 	register int count;
1589 
1590 	if (object == NULL)
1591 		return;
1592 
1593 	db_iprintf(
1594 	    "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
1595 	    object, (int)object->type, (u_long)object->size,
1596 	    object->resident_page_count, object->ref_count, object->flags);
1597 	/*
1598 	 * XXX no %qd in kernel.  Truncate object->paging_offset and
1599 	 * object->backing_object_offset.
1600 	 */
1601 	db_iprintf(" sref=%d, offset=0x%lx, backing_object(%d)=(%p)+0x%lx\n",
1602 	    object->shadow_count, (long)object->paging_offset,
1603 	    object->backing_object ? object->backing_object->ref_count : 0,
1604 	    object->backing_object, (long)object->backing_object_offset);
1605 
1606 	if (!full)
1607 		return;
1608 
1609 	db_indent += 2;
1610 	count = 0;
1611 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) {
1612 		if (count == 0)
1613 			db_iprintf("memory:=");
1614 		else if (count == 6) {
1615 			db_printf("\n");
1616 			db_iprintf(" ...");
1617 			count = 0;
1618 		} else
1619 			db_printf(",");
1620 		count++;
1621 
1622 		db_printf("(off=0x%lx,page=0x%lx)",
1623 		    (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
1624 	}
1625 	if (count != 0)
1626 		db_printf("\n");
1627 	db_indent -= 2;
1628 }
1629 
1630 /* XXX. */
1631 #undef count
1632 
1633 /* XXX need this non-static entry for calling from vm_map_print. */
1634 void
1635 vm_object_print(addr, have_addr, count, modif)
1636         /* db_expr_t */ long addr;
1637 	boolean_t have_addr;
1638 	/* db_expr_t */ long count;
1639 	char *modif;
1640 {
1641 	vm_object_print_static(addr, have_addr, count, modif);
1642 }
1643 
1644 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
1645 {
1646 	vm_object_t object;
1647 	int nl = 0;
1648 	int c;
1649 	for (object = TAILQ_FIRST(&vm_object_list);
1650 			object != NULL;
1651 			object = TAILQ_NEXT(object, object_list)) {
1652 		vm_pindex_t idx, fidx;
1653 		vm_pindex_t osize;
1654 		vm_offset_t pa = -1, padiff;
1655 		int rcount;
1656 		vm_page_t m;
1657 
1658 		db_printf("new object: %p\n", (void *)object);
1659 		if ( nl > 18) {
1660 			c = cngetc();
1661 			if (c != ' ')
1662 				return;
1663 			nl = 0;
1664 		}
1665 		nl++;
1666 		rcount = 0;
1667 		fidx = 0;
1668 		osize = object->size;
1669 		if (osize > 128)
1670 			osize = 128;
1671 		for(idx=0;idx<osize;idx++) {
1672 			m = vm_page_lookup(object, idx);
1673 			if (m == NULL) {
1674 				if (rcount) {
1675 					db_printf(" index(%d)run(%d)pa(0x%x)\n",
1676 						fidx, rcount, pa);
1677 					if ( nl > 18) {
1678 						c = cngetc();
1679 						if (c != ' ')
1680 							return;
1681 						nl = 0;
1682 					}
1683 					nl++;
1684 					rcount = 0;
1685 				}
1686 				continue;
1687 			}
1688 
1689 
1690 			if (rcount &&
1691 				(VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
1692 				++rcount;
1693 				continue;
1694 			}
1695 			if (rcount) {
1696 				padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
1697 				padiff >>= PAGE_SHIFT;
1698 				padiff &= PQ_L2_MASK;
1699 				if (padiff == 0) {
1700 					pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
1701 					++rcount;
1702 					continue;
1703 				}
1704 				db_printf(" index(%d)run(%d)pa(0x%x)", fidx, rcount, pa);
1705 				db_printf("pd(%d)\n", padiff);
1706 				if ( nl > 18) {
1707 					c = cngetc();
1708 					if (c != ' ')
1709 						return;
1710 					nl = 0;
1711 				}
1712 				nl++;
1713 			}
1714 			fidx = idx;
1715 			pa = VM_PAGE_TO_PHYS(m);
1716 			rcount = 1;
1717 		}
1718 		if (rcount) {
1719 			db_printf(" index(%d)run(%d)pa(0x%x)\n", fidx, rcount, pa);
1720 			if ( nl > 18) {
1721 				c = cngetc();
1722 				if (c != ' ')
1723 					return;
1724 				nl = 0;
1725 			}
1726 			nl++;
1727 		}
1728 	}
1729 }
1730 #endif /* DDB */
1731