xref: /freebsd/sys/vm/vm_object.c (revision 601752d5a7bef087e755da5a2b158fa35cb51ccb)
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 1.152 1999/02/24 21:26:26 dillon 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->behavior = OBJ_NORMAL;
158 	object->paging_in_progress = 0;
159 	object->resident_page_count = 0;
160 	object->cache_count = 0;
161 	object->wire_count = 0;
162 	object->shadow_count = 0;
163 	object->pg_color = next_index;
164 	if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
165 		incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
166 	else
167 		incr = size;
168 	next_index = (next_index + incr) & PQ_L2_MASK;
169 	object->handle = NULL;
170 	object->backing_object = NULL;
171 	object->backing_object_offset = (vm_ooffset_t) 0;
172 	/*
173 	 * Try to generate a number that will spread objects out in the
174 	 * hash table.  We 'wipe' new objects across the hash in 128 page
175 	 * increments plus 1 more to offset it a little more by the time
176 	 * it wraps around.
177 	 */
178 	object->hash_rand = object_hash_rand - 129;
179 
180 	object->last_read = 0;
181 	object->generation++;
182 
183 	TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
184 	vm_object_count++;
185 	object_hash_rand = object->hash_rand;
186 }
187 
188 /*
189  *	vm_object_init:
190  *
191  *	Initialize the VM objects module.
192  */
193 void
194 vm_object_init()
195 {
196 	TAILQ_INIT(&vm_object_list);
197 	simple_lock_init(&vm_object_list_lock);
198 	vm_object_count = 0;
199 
200 	kernel_object = &kernel_object_store;
201 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
202 	    kernel_object);
203 
204 	kmem_object = &kmem_object_store;
205 	_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
206 	    kmem_object);
207 
208 	obj_zone = &obj_zone_store;
209 	zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object),
210 		vm_objects_init, VM_OBJECTS_INIT);
211 }
212 
213 void
214 vm_object_init2() {
215 	zinitna(obj_zone, NULL, NULL, 0, 0, 0, 1);
216 }
217 
218 /*
219  *	vm_object_allocate:
220  *
221  *	Returns a new object with the given size.
222  */
223 
224 vm_object_t
225 vm_object_allocate(type, size)
226 	objtype_t type;
227 	vm_size_t size;
228 {
229 	vm_object_t result;
230 
231 	result = (vm_object_t) zalloc(obj_zone);
232 
233 	_vm_object_allocate(type, size, result);
234 
235 	return (result);
236 }
237 
238 
239 /*
240  *	vm_object_reference:
241  *
242  *	Gets another reference to the given object.
243  */
244 void
245 vm_object_reference(object)
246 	vm_object_t object;
247 {
248 	if (object == NULL)
249 		return;
250 
251 	KASSERT(!(object->flags & OBJ_DEAD),
252 	    ("vm_object_reference: attempting to reference dead obj"));
253 
254 	object->ref_count++;
255 	if (object->type == OBJT_VNODE) {
256 		while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curproc)) {
257 #if !defined(MAX_PERF)
258 			printf("vm_object_reference: delay in getting object\n");
259 #endif
260 		}
261 	}
262 }
263 
264 void
265 vm_object_vndeallocate(object)
266 	vm_object_t object;
267 {
268 	struct vnode *vp = (struct vnode *) object->handle;
269 
270 	KASSERT(object->type == OBJT_VNODE,
271 	    ("vm_object_vndeallocate: not a vnode object"));
272 	KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
273 #ifdef INVARIANTS
274 	if (object->ref_count == 0) {
275 		vprint("vm_object_vndeallocate", vp);
276 		panic("vm_object_vndeallocate: bad object reference count");
277 	}
278 #endif
279 
280 	object->ref_count--;
281 	if (object->ref_count == 0) {
282 		vp->v_flag &= ~VTEXT;
283 		vm_object_clear_flag(object, OBJ_OPT);
284 	}
285 	vrele(vp);
286 }
287 
288 /*
289  *	vm_object_deallocate:
290  *
291  *	Release a reference to the specified object,
292  *	gained either through a vm_object_allocate
293  *	or a vm_object_reference call.  When all references
294  *	are gone, storage associated with this object
295  *	may be relinquished.
296  *
297  *	No object may be locked.
298  */
299 void
300 vm_object_deallocate(object)
301 	vm_object_t object;
302 {
303 	vm_object_t temp;
304 
305 	while (object != NULL) {
306 
307 		if (object->type == OBJT_VNODE) {
308 			vm_object_vndeallocate(object);
309 			return;
310 		}
311 
312 		if (object->ref_count == 0) {
313 			panic("vm_object_deallocate: object deallocated too many times: %d", object->type);
314 		} else if (object->ref_count > 2) {
315 			object->ref_count--;
316 			return;
317 		}
318 
319 		/*
320 		 * Here on ref_count of one or two, which are special cases for
321 		 * objects.
322 		 */
323 		if ((object->ref_count == 2) && (object->shadow_count == 0)) {
324 			vm_object_set_flag(object, OBJ_ONEMAPPING);
325 			object->ref_count--;
326 			return;
327 		} else if ((object->ref_count == 2) && (object->shadow_count == 1)) {
328 			object->ref_count--;
329 			if ((object->handle == NULL) &&
330 			    (object->type == OBJT_DEFAULT ||
331 			     object->type == OBJT_SWAP)) {
332 				vm_object_t robject;
333 
334 				robject = TAILQ_FIRST(&object->shadow_head);
335 				KASSERT(robject != NULL,
336 				    ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
337 					 object->ref_count,
338 					 object->shadow_count));
339 				if ((robject->handle == NULL) &&
340 				    (robject->type == OBJT_DEFAULT ||
341 				     robject->type == OBJT_SWAP)) {
342 
343 					robject->ref_count++;
344 
345 					while (
346 						robject->paging_in_progress ||
347 						object->paging_in_progress
348 					) {
349 						vm_object_pip_sleep(robject, "objde1");
350 						vm_object_pip_sleep(object, "objde2");
351 					}
352 
353 					if (robject->ref_count == 1) {
354 						robject->ref_count--;
355 						object = robject;
356 						goto doterm;
357 					}
358 
359 					object = robject;
360 					vm_object_collapse(object);
361 					continue;
362 				}
363 			}
364 
365 			return;
366 
367 		} else {
368 			object->ref_count--;
369 			if (object->ref_count != 0)
370 				return;
371 		}
372 
373 doterm:
374 
375 		temp = object->backing_object;
376 		if (temp) {
377 			TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
378 			temp->shadow_count--;
379 			if (temp->ref_count == 0)
380 				vm_object_clear_flag(temp, OBJ_OPT);
381 			temp->generation++;
382 			object->backing_object = NULL;
383 		}
384 		vm_object_terminate(object);
385 		/* unlocks and deallocates object */
386 		object = temp;
387 	}
388 }
389 
390 /*
391  *	vm_object_terminate actually destroys the specified object, freeing
392  *	up all previously used resources.
393  *
394  *	The object must be locked.
395  *	This routine may block.
396  */
397 void
398 vm_object_terminate(object)
399 	vm_object_t object;
400 {
401 	vm_page_t p;
402 	int s;
403 
404 	/*
405 	 * Make sure no one uses us.
406 	 */
407 	vm_object_set_flag(object, OBJ_DEAD);
408 
409 	/*
410 	 * wait for the pageout daemon to be done with the object
411 	 */
412 	vm_object_pip_wait(object, "objtrm");
413 
414 	KASSERT(!object->paging_in_progress,
415 		("vm_object_terminate: pageout in progress"));
416 
417 	/*
418 	 * Clean and free the pages, as appropriate. All references to the
419 	 * object are gone, so we don't need to lock it.
420 	 */
421 	if (object->type == OBJT_VNODE) {
422 		struct vnode *vp;
423 
424 		/*
425 		 * Freeze optimized copies.
426 		 */
427 		vm_freeze_copyopts(object, 0, object->size);
428 
429 		/*
430 		 * Clean pages and flush buffers.
431 		 */
432 		vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
433 
434 		vp = (struct vnode *) object->handle;
435 		vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
436 	}
437 
438 	if (object->ref_count != 0)
439 		panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count);
440 
441 	/*
442 	 * Now free any remaining pages. For internal objects, this also
443 	 * removes them from paging queues. Don't free wired pages, just
444 	 * remove them from the object.
445 	 */
446 	s = splvm();
447 	while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
448 #if !defined(MAX_PERF)
449 		if (p->busy || (p->flags & PG_BUSY))
450 			panic("vm_object_terminate: freeing busy page %p\n", p);
451 #endif
452 		if (p->wire_count == 0) {
453 			vm_page_busy(p);
454 			vm_page_free(p);
455 			cnt.v_pfree++;
456 		} else {
457 			vm_page_busy(p);
458 			vm_page_remove(p);
459 		}
460 	}
461 	splx(s);
462 
463 	/*
464 	 * Let the pager know object is dead.
465 	 */
466 	vm_pager_deallocate(object);
467 
468 	/*
469 	 * Remove the object from the global object list.
470 	 */
471 	simple_lock(&vm_object_list_lock);
472 	TAILQ_REMOVE(&vm_object_list, object, object_list);
473 	simple_unlock(&vm_object_list_lock);
474 
475 	wakeup(object);
476 
477 	/*
478 	 * Free the space for the object.
479 	 */
480 	zfree(obj_zone, object);
481 }
482 
483 /*
484  *	vm_object_page_clean
485  *
486  *	Clean all dirty pages in the specified range of object.
487  *	Leaves page on whatever queue it is currently on.
488  *
489  *	Odd semantics: if start == end, we clean everything.
490  *
491  *	The object must be locked.
492  */
493 
494 void
495 vm_object_page_clean(object, start, end, flags)
496 	vm_object_t object;
497 	vm_pindex_t start;
498 	vm_pindex_t end;
499 	int flags;
500 {
501 	vm_page_t p, np, tp;
502 	vm_offset_t tstart, tend;
503 	vm_pindex_t pi;
504 	int s;
505 	struct vnode *vp;
506 	int runlen;
507 	int maxf;
508 	int chkb;
509 	int maxb;
510 	int i;
511 	int pagerflags;
512 	vm_page_t maf[vm_pageout_page_count];
513 	vm_page_t mab[vm_pageout_page_count];
514 	vm_page_t ma[vm_pageout_page_count];
515 	int curgeneration;
516 
517 	if (object->type != OBJT_VNODE ||
518 		(object->flags & OBJ_MIGHTBEDIRTY) == 0)
519 		return;
520 
521 	pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : 0;
522 	pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
523 
524 	vp = object->handle;
525 
526 	vm_object_set_flag(object, OBJ_CLEANING);
527 
528 	tstart = start;
529 	if (end == 0) {
530 		tend = object->size;
531 	} else {
532 		tend = end;
533 	}
534 
535 	for(p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) {
536 		vm_page_flag_set(p, PG_CLEANCHK);
537 		vm_page_protect(p, VM_PROT_READ);
538 	}
539 
540 	if ((tstart == 0) && (tend == object->size)) {
541 		vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
542 	}
543 
544 rescan:
545 	curgeneration = object->generation;
546 
547 	for(p = TAILQ_FIRST(&object->memq); p; p = np) {
548 		np = TAILQ_NEXT(p, listq);
549 
550 		pi = p->pindex;
551 		if (((p->flags & PG_CLEANCHK) == 0) ||
552 			(pi < tstart) || (pi >= tend) ||
553 			(p->valid == 0) ||
554 			((p->queue - p->pc) == PQ_CACHE)) {
555 			vm_page_flag_clear(p, PG_CLEANCHK);
556 			continue;
557 		}
558 
559 		vm_page_test_dirty(p);
560 		if ((p->dirty & p->valid) == 0) {
561 			vm_page_flag_clear(p, PG_CLEANCHK);
562 			continue;
563 		}
564 
565 		s = splvm();
566 		while (vm_page_sleep_busy(p, TRUE, "vpcwai")) {
567 			if (object->generation != curgeneration) {
568 				splx(s);
569 				goto rescan;
570 			}
571 		}
572 
573 		maxf = 0;
574 		for(i=1;i<vm_pageout_page_count;i++) {
575 			if ((tp = vm_page_lookup(object, pi + i)) != NULL) {
576 				if ((tp->flags & PG_BUSY) ||
577 					(tp->flags & PG_CLEANCHK) == 0 ||
578 					(tp->busy != 0))
579 					break;
580 				if((tp->queue - tp->pc) == PQ_CACHE) {
581 					vm_page_flag_clear(tp, PG_CLEANCHK);
582 					break;
583 				}
584 				vm_page_test_dirty(tp);
585 				if ((tp->dirty & tp->valid) == 0) {
586 					vm_page_flag_clear(tp, PG_CLEANCHK);
587 					break;
588 				}
589 				maf[ i - 1 ] = tp;
590 				maxf++;
591 				continue;
592 			}
593 			break;
594 		}
595 
596 		maxb = 0;
597 		chkb = vm_pageout_page_count -  maxf;
598 		if (chkb) {
599 			for(i = 1; i < chkb;i++) {
600 				if ((tp = vm_page_lookup(object, pi - i)) != NULL) {
601 					if ((tp->flags & PG_BUSY) ||
602 						(tp->flags & PG_CLEANCHK) == 0 ||
603 						(tp->busy != 0))
604 						break;
605 					if((tp->queue - tp->pc) == PQ_CACHE) {
606 						vm_page_flag_clear(tp, PG_CLEANCHK);
607 						break;
608 					}
609 					vm_page_test_dirty(tp);
610 					if ((tp->dirty & tp->valid) == 0) {
611 						vm_page_flag_clear(tp, PG_CLEANCHK);
612 						break;
613 					}
614 					mab[ i - 1 ] = tp;
615 					maxb++;
616 					continue;
617 				}
618 				break;
619 			}
620 		}
621 
622 		for(i=0;i<maxb;i++) {
623 			int index = (maxb - i) - 1;
624 			ma[index] = mab[i];
625 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
626 		}
627 		vm_page_flag_clear(p, PG_CLEANCHK);
628 		ma[maxb] = p;
629 		for(i=0;i<maxf;i++) {
630 			int index = (maxb + i) + 1;
631 			ma[index] = maf[i];
632 			vm_page_flag_clear(ma[index], PG_CLEANCHK);
633 		}
634 		runlen = maxb + maxf + 1;
635 
636 		splx(s);
637 		vm_pageout_flush(ma, runlen, pagerflags);
638 		for (i = 0; i<runlen; i++) {
639 			if (ma[i]->valid & ma[i]->dirty) {
640 				vm_page_protect(ma[i], VM_PROT_READ);
641 				vm_page_flag_set(ma[i], PG_CLEANCHK);
642 			}
643 		}
644 		if (object->generation != curgeneration)
645 			goto rescan;
646 	}
647 
648 	VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);
649 
650 	vm_object_clear_flag(object, OBJ_CLEANING);
651 	return;
652 }
653 
654 #ifdef not_used
655 /* XXX I cannot tell if this should be an exported symbol */
656 /*
657  *	vm_object_deactivate_pages
658  *
659  *	Deactivate all pages in the specified object.  (Keep its pages
660  *	in memory even though it is no longer referenced.)
661  *
662  *	The object must be locked.
663  */
664 static void
665 vm_object_deactivate_pages(object)
666 	vm_object_t object;
667 {
668 	vm_page_t p, next;
669 
670 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
671 		next = TAILQ_NEXT(p, listq);
672 		vm_page_deactivate(p);
673 	}
674 }
675 #endif
676 
677 /*
678  * Same as vm_object_pmap_copy, except range checking really
679  * works, and is meant for small sections of an object.
680  *
681  * This code protects resident pages by making them read-only
682  * and is typically called on a fork or split when a page
683  * is converted to copy-on-write.
684  *
685  * NOTE: If the page is already at VM_PROT_NONE, calling
686  * vm_page_protect will have no effect.
687  */
688 
689 void
690 vm_object_pmap_copy_1(object, start, end)
691 	vm_object_t object;
692 	vm_pindex_t start;
693 	vm_pindex_t end;
694 {
695 	vm_pindex_t idx;
696 	vm_page_t p;
697 
698 	if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
699 		return;
700 
701 	for (idx = start; idx < end; idx++) {
702 		p = vm_page_lookup(object, idx);
703 		if (p == NULL)
704 			continue;
705 		vm_page_protect(p, VM_PROT_READ);
706 	}
707 }
708 
709 /*
710  *	vm_object_pmap_remove:
711  *
712  *	Removes all physical pages in the specified
713  *	object range from all physical maps.
714  *
715  *	The object must *not* be locked.
716  */
717 void
718 vm_object_pmap_remove(object, start, end)
719 	vm_object_t object;
720 	vm_pindex_t start;
721 	vm_pindex_t end;
722 {
723 	vm_page_t p;
724 
725 	if (object == NULL)
726 		return;
727 	for (p = TAILQ_FIRST(&object->memq);
728 		p != NULL;
729 		p = TAILQ_NEXT(p, listq)) {
730 		if (p->pindex >= start && p->pindex < end)
731 			vm_page_protect(p, VM_PROT_NONE);
732 	}
733 	if ((start == 0) && (object->size == end))
734 		vm_object_clear_flag(object, OBJ_WRITEABLE);
735 }
736 
737 /*
738  *	vm_object_madvise:
739  *
740  *	Implements the madvise function at the object/page level.
741  *
742  *	Currently, madvise() functions are limited to the default and
743  *	swap object types only, and also limited to only the unshared portions
744  *	of a process's address space.  MADV_FREE, certainly, could never be
745  *	run on anything else.  The others are more flexible and the code could
746  *	be adjusted in the future to handle expanded cases for them.
747  */
748 void
749 vm_object_madvise(object, pindex, count, advise)
750 	vm_object_t object;
751 	vm_pindex_t pindex;
752 	int count;
753 	int advise;
754 {
755 	vm_pindex_t end, tpindex;
756 	vm_object_t tobject;
757 	vm_page_t m;
758 
759 	if (object == NULL)
760 		return;
761 
762 	end = pindex + count;
763 
764 	/*
765 	 * Locate and adjust resident pages
766 	 */
767 
768 	for (; pindex < end; pindex += 1) {
769 relookup:
770 		tobject = object;
771 		tpindex = pindex;
772 shadowlookup:
773 
774 		if (tobject->type != OBJT_DEFAULT &&
775 		    tobject->type != OBJT_SWAP
776 		) {
777 			continue;
778 		}
779 
780 		if ((tobject->flags & OBJ_ONEMAPPING) == 0)
781 			continue;
782 
783 		m = vm_page_lookup(tobject, tpindex);
784 
785 		if (m == NULL) {
786 			/*
787 			 * There may be swap even if there is no backing page
788 			 */
789 			if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
790 				swap_pager_freespace(tobject, tpindex, 1);
791 
792 			/*
793 			 * next object
794 			 */
795 			tobject = tobject->backing_object;
796 			if (tobject == NULL)
797 				continue;
798 			tpindex += OFF_TO_IDX(tobject->backing_object_offset);
799 			goto shadowlookup;
800 		}
801 
802 		/*
803 		 * If the page is busy or not in a normal active state,
804 		 * we skip it.  Things can break if we mess with pages
805 		 * in any of the below states.
806 		 */
807 		if (
808 		    m->hold_count ||
809 		    m->wire_count ||
810 		    m->valid != VM_PAGE_BITS_ALL
811 		) {
812 			continue;
813 		}
814 
815  		if (vm_page_sleep_busy(m, TRUE, "madvpo"))
816   			goto relookup;
817 
818 		if (advise == MADV_WILLNEED) {
819 			vm_page_activate(m);
820 		} else if (advise == MADV_DONTNEED) {
821 			vm_page_deactivate(m);
822 		} else if (advise == MADV_FREE) {
823 			/*
824 			 * Mark the page clean.  This will allow the page
825 			 * to be freed up by the system.  However, such pages
826 			 * are often reused quickly by malloc()/free()
827 			 * so we do not do anything that would cause
828 			 * a page fault if we can help it.
829 			 *
830 			 * Specifically, we do not try to actually free
831 			 * the page now nor do we try to put it in the
832 			 * cache (which would cause a page fault on reuse).
833 			 *
834 			 * But we do make the page is freeable as we
835 			 * can without actually taking the step of unmapping
836 			 * it.
837 			 */
838 			pmap_clear_modify(VM_PAGE_TO_PHYS(m));
839 			m->dirty = 0;
840 			m->act_count = 0;
841 			vm_page_deactivate(m);
842 			if (tobject->type == OBJT_SWAP)
843 				swap_pager_freespace(tobject, tpindex, 1);
844 		}
845 	}
846 }
847 
848 /*
849  *	vm_object_shadow:
850  *
851  *	Create a new object which is backed by the
852  *	specified existing object range.  The source
853  *	object reference is deallocated.
854  *
855  *	The new object and offset into that object
856  *	are returned in the source parameters.
857  */
858 
859 void
860 vm_object_shadow(object, offset, length)
861 	vm_object_t *object;	/* IN/OUT */
862 	vm_ooffset_t *offset;	/* IN/OUT */
863 	vm_size_t length;
864 {
865 	vm_object_t source;
866 	vm_object_t result;
867 
868 	source = *object;
869 
870 	/*
871 	 * Allocate a new object with the given length
872 	 */
873 
874 	if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL)
875 		panic("vm_object_shadow: no object for shadowing");
876 
877 	/*
878 	 * The new object shadows the source object, adding a reference to it.
879 	 * Our caller changes his reference to point to the new object,
880 	 * removing a reference to the source object.  Net result: no change
881 	 * of reference count.
882 	 *
883 	 * Try to optimize the result object's page color when shadowing
884 	 * in order to maintain page coloring consistancy in the combined
885 	 * shadowed object.
886 	 */
887 	result->backing_object = source;
888 	if (source) {
889 		TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
890 		vm_object_clear_flag(source, OBJ_ONEMAPPING);
891 		source->shadow_count++;
892 		source->generation++;
893 		result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK;
894 	}
895 
896 	/*
897 	 * Store the offset into the source object, and fix up the offset into
898 	 * the new object.
899 	 */
900 
901 	result->backing_object_offset = *offset;
902 
903 	/*
904 	 * Return the new things
905 	 */
906 
907 	*offset = 0;
908 	*object = result;
909 }
910 
911 #define	OBSC_TEST_ALL_SHADOWED	0x0001
912 #define	OBSC_COLLAPSE_NOWAIT	0x0002
913 #define	OBSC_COLLAPSE_WAIT	0x0004
914 
915 static __inline int
916 vm_object_backing_scan(vm_object_t object, int op)
917 {
918 	int s;
919 	int r = 1;
920 	vm_page_t p;
921 	vm_object_t backing_object;
922 	vm_pindex_t backing_offset_index;
923 
924 	s = splvm();
925 
926 	backing_object = object->backing_object;
927 	backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
928 
929 	/*
930 	 * Initial conditions
931 	 */
932 
933 	if (op & OBSC_TEST_ALL_SHADOWED) {
934 		/*
935 		 * We do not want to have to test for the existance of
936 		 * swap pages in the backing object.  XXX but with the
937 		 * new swapper this would be pretty easy to do.
938 		 *
939 		 * XXX what about anonymous MAP_SHARED memory that hasn't
940 		 * been ZFOD faulted yet?  If we do not test for this, the
941 		 * shadow test may succeed! XXX
942 		 */
943 		if (backing_object->type != OBJT_DEFAULT) {
944 			splx(s);
945 			return(0);
946 		}
947 	}
948 	if (op & OBSC_COLLAPSE_WAIT) {
949 		vm_object_set_flag(backing_object, OBJ_DEAD);
950 	}
951 
952 	/*
953 	 * Our scan
954 	 */
955 
956 	p = TAILQ_FIRST(&backing_object->memq);
957 	while (p) {
958 		vm_page_t next = TAILQ_NEXT(p, listq);
959 		vm_pindex_t new_pindex = p->pindex - backing_offset_index;
960 
961 		if (op & OBSC_TEST_ALL_SHADOWED) {
962 			vm_page_t pp;
963 
964 			/*
965 			 * Ignore pages outside the parent object's range
966 			 * and outside the parent object's mapping of the
967 			 * backing object.
968 			 *
969 			 * note that we do not busy the backing object's
970 			 * page.
971 			 */
972 
973 			if (
974 			    p->pindex < backing_offset_index ||
975 			    new_pindex >= object->size
976 			) {
977 				p = next;
978 				continue;
979 			}
980 
981 			/*
982 			 * See if the parent has the page or if the parent's
983 			 * object pager has the page.  If the parent has the
984 			 * page but the page is not valid, the parent's
985 			 * object pager must have the page.
986 			 *
987 			 * If this fails, the parent does not completely shadow
988 			 * the object and we might as well give up now.
989 			 */
990 
991 			pp = vm_page_lookup(object, new_pindex);
992 			if (
993 			    (pp == NULL || pp->valid == 0) &&
994 			    !vm_pager_has_page(object, new_pindex, NULL, NULL)
995 			) {
996 				r = 0;
997 				break;
998 			}
999 		}
1000 
1001 		/*
1002 		 * Check for busy page
1003 		 */
1004 
1005 		if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1006 			vm_page_t pp;
1007 
1008 			if (op & OBSC_COLLAPSE_NOWAIT) {
1009 				if (
1010 				    (p->flags & PG_BUSY) ||
1011 				    !p->valid ||
1012 				    p->hold_count ||
1013 				    p->wire_count ||
1014 				    p->busy
1015 				) {
1016 					p = next;
1017 					continue;
1018 				}
1019 			} else if (op & OBSC_COLLAPSE_WAIT) {
1020 				if (vm_page_sleep_busy(p, TRUE, "vmocol")) {
1021 					/*
1022 					 * If we slept, anything could have
1023 					 * happened.  Since the object is
1024 					 * marked dead, the backing offset
1025 					 * should not have changed so we
1026 					 * just restart our scan.
1027 					 */
1028 					p = TAILQ_FIRST(&backing_object->memq);
1029 					continue;
1030 				}
1031 			}
1032 
1033 			/*
1034 			 * Busy the page
1035 			 */
1036 			vm_page_busy(p);
1037 
1038 			KASSERT(
1039 			    p->object == backing_object,
1040 			    ("vm_object_qcollapse(): object mismatch")
1041 			);
1042 
1043 			/*
1044 			 * Destroy any associated swap
1045 			 */
1046 			if (backing_object->type == OBJT_SWAP) {
1047 				swap_pager_freespace(
1048 				    backing_object,
1049 				    p->pindex,
1050 				    1
1051 				);
1052 			}
1053 
1054 			if (
1055 			    p->pindex < backing_offset_index ||
1056 			    new_pindex >= object->size
1057 			) {
1058 				/*
1059 				 * Page is out of the parent object's range, we
1060 				 * can simply destroy it.
1061 				 */
1062 				vm_page_protect(p, VM_PROT_NONE);
1063 				vm_page_free(p);
1064 				p = next;
1065 				continue;
1066 			}
1067 
1068 			pp = vm_page_lookup(object, new_pindex);
1069 			if (
1070 			    pp != NULL ||
1071 			    vm_pager_has_page(object, new_pindex, NULL, NULL)
1072 			) {
1073 				/*
1074 				 * page already exists in parent OR swap exists
1075 				 * for this location in the parent.  Destroy
1076 				 * the original page from the backing object.
1077 				 *
1078 				 * Leave the parent's page alone
1079 				 */
1080 				vm_page_protect(p, VM_PROT_NONE);
1081 				vm_page_free(p);
1082 				p = next;
1083 				continue;
1084 			}
1085 
1086 			/*
1087 			 * Page does not exist in parent, rename the
1088 			 * page from the backing object to the main object.
1089 			 *
1090 			 * If the page was mapped to a process, it can remain
1091 			 * mapped through the rename.
1092 			 */
1093 			if ((p->queue - p->pc) == PQ_CACHE)
1094 				vm_page_deactivate(p);
1095 
1096 			vm_page_rename(p, object, new_pindex);
1097 			/* page automatically made dirty by rename */
1098 		}
1099 		p = next;
1100 	}
1101 	splx(s);
1102 	return(r);
1103 }
1104 
1105 
1106 /*
1107  * this version of collapse allows the operation to occur earlier and
1108  * when paging_in_progress is true for an object...  This is not a complete
1109  * operation, but should plug 99.9% of the rest of the leaks.
1110  */
1111 static void
1112 vm_object_qcollapse(object)
1113 	vm_object_t object;
1114 {
1115 	vm_object_t backing_object = object->backing_object;
1116 
1117 	if (backing_object->ref_count != 1)
1118 		return;
1119 
1120 	backing_object->ref_count += 2;
1121 
1122 	vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1123 
1124 	backing_object->ref_count -= 2;
1125 }
1126 
1127 /*
1128  *	vm_object_collapse:
1129  *
1130  *	Collapse an object with the object backing it.
1131  *	Pages in the backing object are moved into the
1132  *	parent, and the backing object is deallocated.
1133  */
1134 void
1135 vm_object_collapse(object)
1136 	vm_object_t object;
1137 {
1138 	while (TRUE) {
1139 		vm_object_t backing_object;
1140 
1141 		/*
1142 		 * Verify that the conditions are right for collapse:
1143 		 *
1144 		 * The object exists and the backing object exists.
1145 		 */
1146 		if (object == NULL)
1147 			break;
1148 
1149 		if ((backing_object = object->backing_object) == NULL)
1150 			break;
1151 
1152 		/*
1153 		 * we check the backing object first, because it is most likely
1154 		 * not collapsable.
1155 		 */
1156 		if (backing_object->handle != NULL ||
1157 		    (backing_object->type != OBJT_DEFAULT &&
1158 		     backing_object->type != OBJT_SWAP) ||
1159 		    (backing_object->flags & OBJ_DEAD) ||
1160 		    object->handle != NULL ||
1161 		    (object->type != OBJT_DEFAULT &&
1162 		     object->type != OBJT_SWAP) ||
1163 		    (object->flags & OBJ_DEAD)) {
1164 			break;
1165 		}
1166 
1167 		if (
1168 		    object->paging_in_progress != 0 ||
1169 		    backing_object->paging_in_progress != 0
1170 		) {
1171 			vm_object_qcollapse(object);
1172 			break;
1173 		}
1174 
1175 		/*
1176 		 * We know that we can either collapse the backing object (if
1177 		 * the parent is the only reference to it) or (perhaps) have
1178 		 * the parent bypass the object if the parent happens to shadow
1179 		 * all the resident pages in the entire backing object.
1180 		 *
1181 		 * This is ignoring pager-backed pages such as swap pages.
1182 		 * vm_object_backing_scan fails the shadowing test in this
1183 		 * case.
1184 		 */
1185 
1186 		if (backing_object->ref_count == 1) {
1187 			/*
1188 			 * If there is exactly one reference to the backing
1189 			 * object, we can collapse it into the parent.
1190 			 */
1191 
1192 			vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1193 
1194 			/*
1195 			 * Move the pager from backing_object to object.
1196 			 */
1197 
1198 			if (backing_object->type == OBJT_SWAP) {
1199 				vm_object_pip_add(backing_object, 1);
1200 
1201 				/*
1202 				 * scrap the paging_offset junk and do a
1203 				 * discrete copy.  This also removes major
1204 				 * assumptions about how the swap-pager
1205 				 * works from where it doesn't belong.  The
1206 				 * new swapper is able to optimize the
1207 				 * destroy-source case.
1208 				 */
1209 
1210 				vm_object_pip_add(object, 1);
1211 				swap_pager_copy(
1212 				    backing_object,
1213 				    object,
1214 				    OFF_TO_IDX(object->backing_object_offset), TRUE);
1215 				vm_object_pip_wakeup(object);
1216 
1217 				vm_object_pip_wakeup(backing_object);
1218 			}
1219 			/*
1220 			 * Object now shadows whatever backing_object did.
1221 			 * Note that the reference to
1222 			 * backing_object->backing_object moves from within
1223 			 * backing_object to within object.
1224 			 */
1225 
1226 			TAILQ_REMOVE(
1227 			    &object->backing_object->shadow_head,
1228 			    object,
1229 			    shadow_list
1230 			);
1231 			object->backing_object->shadow_count--;
1232 			object->backing_object->generation++;
1233 			if (backing_object->backing_object) {
1234 				TAILQ_REMOVE(
1235 				    &backing_object->backing_object->shadow_head,
1236 				    backing_object,
1237 				    shadow_list
1238 				);
1239 				backing_object->backing_object->shadow_count--;
1240 				backing_object->backing_object->generation++;
1241 			}
1242 			object->backing_object = backing_object->backing_object;
1243 			if (object->backing_object) {
1244 				TAILQ_INSERT_TAIL(
1245 				    &object->backing_object->shadow_head,
1246 				    object,
1247 				    shadow_list
1248 				);
1249 				object->backing_object->shadow_count++;
1250 				object->backing_object->generation++;
1251 			}
1252 
1253 			object->backing_object_offset +=
1254 			    backing_object->backing_object_offset;
1255 
1256 			/*
1257 			 * Discard backing_object.
1258 			 *
1259 			 * Since the backing object has no pages, no pager left,
1260 			 * and no object references within it, all that is
1261 			 * necessary is to dispose of it.
1262 			 */
1263 
1264 			TAILQ_REMOVE(
1265 			    &vm_object_list,
1266 			    backing_object,
1267 			    object_list
1268 			);
1269 			vm_object_count--;
1270 
1271 			zfree(obj_zone, backing_object);
1272 
1273 			object_collapses++;
1274 		} else {
1275 			vm_object_t new_backing_object;
1276 
1277 			/*
1278 			 * If we do not entirely shadow the backing object,
1279 			 * there is nothing we can do so we give up.
1280 			 */
1281 
1282 			if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) {
1283 				break;
1284 			}
1285 
1286 			/*
1287 			 * Make the parent shadow the next object in the
1288 			 * chain.  Deallocating backing_object will not remove
1289 			 * it, since its reference count is at least 2.
1290 			 */
1291 
1292 			TAILQ_REMOVE(
1293 			    &backing_object->shadow_head,
1294 			    object,
1295 			    shadow_list
1296 			);
1297 			backing_object->shadow_count--;
1298 			backing_object->generation++;
1299 
1300 			new_backing_object = backing_object->backing_object;
1301 			if ((object->backing_object = new_backing_object) != NULL) {
1302 				vm_object_reference(new_backing_object);
1303 				TAILQ_INSERT_TAIL(
1304 				    &new_backing_object->shadow_head,
1305 				    object,
1306 				    shadow_list
1307 				);
1308 				new_backing_object->shadow_count++;
1309 				new_backing_object->generation++;
1310 				object->backing_object_offset +=
1311 					backing_object->backing_object_offset;
1312 			}
1313 
1314 			/*
1315 			 * Drop the reference count on backing_object. Since
1316 			 * its ref_count was at least 2, it will not vanish;
1317 			 * so we don't need to call vm_object_deallocate, but
1318 			 * we do anyway.
1319 			 */
1320 			vm_object_deallocate(backing_object);
1321 			object_bypasses++;
1322 		}
1323 
1324 		/*
1325 		 * Try again with this object's new backing object.
1326 		 */
1327 	}
1328 }
1329 
1330 /*
1331  *	vm_object_page_remove: [internal]
1332  *
1333  *	Removes all physical pages in the specified
1334  *	object range from the object's list of pages.
1335  *
1336  *	The object must be locked.
1337  */
1338 void
1339 vm_object_page_remove(object, start, end, clean_only)
1340 	vm_object_t object;
1341 	vm_pindex_t start;
1342 	vm_pindex_t end;
1343 	boolean_t clean_only;
1344 {
1345 	vm_page_t p, next;
1346 	unsigned int size;
1347 	int all;
1348 
1349 	if (object == NULL ||
1350 	    object->resident_page_count == 0)
1351 		return;
1352 
1353 	all = ((end == 0) && (start == 0));
1354 
1355 	vm_object_pip_add(object, 1);
1356 again:
1357 	size = end - start;
1358 	if (all || size > object->resident_page_count / 4) {
1359 		for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
1360 			next = TAILQ_NEXT(p, listq);
1361 			if (all || ((start <= p->pindex) && (p->pindex < end))) {
1362 				if (p->wire_count != 0) {
1363 					vm_page_protect(p, VM_PROT_NONE);
1364 					if (!clean_only)
1365 						p->valid = 0;
1366 					continue;
1367 				}
1368 
1369 				/*
1370 				 * The busy flags are only cleared at
1371 				 * interrupt -- minimize the spl transitions
1372 				 */
1373 
1374  				if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1375  					goto again;
1376 
1377 				if (clean_only && p->valid) {
1378 					vm_page_test_dirty(p);
1379 					if (p->valid & p->dirty)
1380 						continue;
1381 				}
1382 
1383 				vm_page_busy(p);
1384 				vm_page_protect(p, VM_PROT_NONE);
1385 				vm_page_free(p);
1386 			}
1387 		}
1388 	} else {
1389 		while (size > 0) {
1390 			if ((p = vm_page_lookup(object, start)) != 0) {
1391 
1392 				if (p->wire_count != 0) {
1393 					vm_page_protect(p, VM_PROT_NONE);
1394 					if (!clean_only)
1395 						p->valid = 0;
1396 					start += 1;
1397 					size -= 1;
1398 					continue;
1399 				}
1400 
1401 				/*
1402 				 * The busy flags are only cleared at
1403 				 * interrupt -- minimize the spl transitions
1404 				 */
1405  				if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1406 					goto again;
1407 
1408 				if (clean_only && p->valid) {
1409 					vm_page_test_dirty(p);
1410 					if (p->valid & p->dirty) {
1411 						start += 1;
1412 						size -= 1;
1413 						continue;
1414 					}
1415 				}
1416 
1417 				vm_page_busy(p);
1418 				vm_page_protect(p, VM_PROT_NONE);
1419 				vm_page_free(p);
1420 			}
1421 			start += 1;
1422 			size -= 1;
1423 		}
1424 	}
1425 	vm_object_pip_wakeup(object);
1426 }
1427 
1428 /*
1429  *	Routine:	vm_object_coalesce
1430  *	Function:	Coalesces two objects backing up adjoining
1431  *			regions of memory into a single object.
1432  *
1433  *	returns TRUE if objects were combined.
1434  *
1435  *	NOTE:	Only works at the moment if the second object is NULL -
1436  *		if it's not, which object do we lock first?
1437  *
1438  *	Parameters:
1439  *		prev_object	First object to coalesce
1440  *		prev_offset	Offset into prev_object
1441  *		next_object	Second object into coalesce
1442  *		next_offset	Offset into next_object
1443  *
1444  *		prev_size	Size of reference to prev_object
1445  *		next_size	Size of reference to next_object
1446  *
1447  *	Conditions:
1448  *	The object must *not* be locked.
1449  */
1450 boolean_t
1451 vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size)
1452 	vm_object_t prev_object;
1453 	vm_pindex_t prev_pindex;
1454 	vm_size_t prev_size, next_size;
1455 {
1456 	vm_size_t newsize;
1457 
1458 	if (prev_object == NULL) {
1459 		return (TRUE);
1460 	}
1461 
1462 	if (prev_object->type != OBJT_DEFAULT &&
1463 	    prev_object->type != OBJT_SWAP) {
1464 		return (FALSE);
1465 	}
1466 
1467 	/*
1468 	 * Try to collapse the object first
1469 	 */
1470 	vm_object_collapse(prev_object);
1471 
1472 	/*
1473 	 * Can't coalesce if: . more than one reference . paged out . shadows
1474 	 * another object . has a copy elsewhere (any of which mean that the
1475 	 * pages not mapped to prev_entry may be in use anyway)
1476 	 */
1477 
1478 	if (prev_object->backing_object != NULL) {
1479 		return (FALSE);
1480 	}
1481 
1482 	prev_size >>= PAGE_SHIFT;
1483 	next_size >>= PAGE_SHIFT;
1484 
1485 	if ((prev_object->ref_count > 1) &&
1486 	    (prev_object->size != prev_pindex + prev_size)) {
1487 		return (FALSE);
1488 	}
1489 
1490 	/*
1491 	 * Remove any pages that may still be in the object from a previous
1492 	 * deallocation.
1493 	 */
1494 
1495 	vm_object_page_remove(prev_object,
1496 	    prev_pindex + prev_size,
1497 	    prev_pindex + prev_size + next_size, FALSE);
1498 
1499 	/*
1500 	 * Extend the object if necessary.
1501 	 */
1502 	newsize = prev_pindex + prev_size + next_size;
1503 	if (newsize > prev_object->size)
1504 		prev_object->size = newsize;
1505 
1506 	return (TRUE);
1507 }
1508 
1509 #include "opt_ddb.h"
1510 #ifdef DDB
1511 #include <sys/kernel.h>
1512 
1513 #include <machine/cons.h>
1514 
1515 #include <ddb/ddb.h>
1516 
1517 static int	_vm_object_in_map __P((vm_map_t map, vm_object_t object,
1518 				       vm_map_entry_t entry));
1519 static int	vm_object_in_map __P((vm_object_t object));
1520 
1521 static int
1522 _vm_object_in_map(map, object, entry)
1523 	vm_map_t map;
1524 	vm_object_t object;
1525 	vm_map_entry_t entry;
1526 {
1527 	vm_map_t tmpm;
1528 	vm_map_entry_t tmpe;
1529 	vm_object_t obj;
1530 	int entcount;
1531 
1532 	if (map == 0)
1533 		return 0;
1534 
1535 	if (entry == 0) {
1536 		tmpe = map->header.next;
1537 		entcount = map->nentries;
1538 		while (entcount-- && (tmpe != &map->header)) {
1539 			if( _vm_object_in_map(map, object, tmpe)) {
1540 				return 1;
1541 			}
1542 			tmpe = tmpe->next;
1543 		}
1544 	} else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
1545 		tmpm = entry->object.sub_map;
1546 		tmpe = tmpm->header.next;
1547 		entcount = tmpm->nentries;
1548 		while (entcount-- && tmpe != &tmpm->header) {
1549 			if( _vm_object_in_map(tmpm, object, tmpe)) {
1550 				return 1;
1551 			}
1552 			tmpe = tmpe->next;
1553 		}
1554 	} else if ((obj = entry->object.vm_object) != NULL) {
1555 		for(; obj; obj=obj->backing_object)
1556 			if( obj == object) {
1557 				return 1;
1558 			}
1559 	}
1560 	return 0;
1561 }
1562 
1563 static int
1564 vm_object_in_map( object)
1565 	vm_object_t object;
1566 {
1567 	struct proc *p;
1568 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
1569 		if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
1570 			continue;
1571 		if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0))
1572 			return 1;
1573 	}
1574 	if( _vm_object_in_map( kernel_map, object, 0))
1575 		return 1;
1576 	if( _vm_object_in_map( kmem_map, object, 0))
1577 		return 1;
1578 	if( _vm_object_in_map( pager_map, object, 0))
1579 		return 1;
1580 	if( _vm_object_in_map( buffer_map, object, 0))
1581 		return 1;
1582 	if( _vm_object_in_map( io_map, object, 0))
1583 		return 1;
1584 	if( _vm_object_in_map( phys_map, object, 0))
1585 		return 1;
1586 	if( _vm_object_in_map( mb_map, object, 0))
1587 		return 1;
1588 	if( _vm_object_in_map( u_map, object, 0))
1589 		return 1;
1590 	return 0;
1591 }
1592 
1593 DB_SHOW_COMMAND(vmochk, vm_object_check)
1594 {
1595 	vm_object_t object;
1596 
1597 	/*
1598 	 * make sure that internal objs are in a map somewhere
1599 	 * and none have zero ref counts.
1600 	 */
1601 	for (object = TAILQ_FIRST(&vm_object_list);
1602 			object != NULL;
1603 			object = TAILQ_NEXT(object, object_list)) {
1604 		if (object->handle == NULL &&
1605 		    (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
1606 			if (object->ref_count == 0) {
1607 				db_printf("vmochk: internal obj has zero ref count: %d\n",
1608 					object->size);
1609 			}
1610 			if (!vm_object_in_map(object)) {
1611 				db_printf(
1612 			"vmochk: internal obj is not in a map: "
1613 			"ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
1614 				    object->ref_count, (u_long)object->size,
1615 				    (u_long)object->size,
1616 				    (void *)object->backing_object);
1617 			}
1618 		}
1619 	}
1620 }
1621 
1622 /*
1623  *	vm_object_print:	[ debug ]
1624  */
1625 DB_SHOW_COMMAND(object, vm_object_print_static)
1626 {
1627 	/* XXX convert args. */
1628 	vm_object_t object = (vm_object_t)addr;
1629 	boolean_t full = have_addr;
1630 
1631 	vm_page_t p;
1632 
1633 	/* XXX count is an (unused) arg.  Avoid shadowing it. */
1634 #define	count	was_count
1635 
1636 	int count;
1637 
1638 	if (object == NULL)
1639 		return;
1640 
1641 	db_iprintf(
1642 	    "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
1643 	    object, (int)object->type, (u_long)object->size,
1644 	    object->resident_page_count, object->ref_count, object->flags);
1645 	/*
1646 	 * XXX no %qd in kernel.  Truncate object->backing_object_offset.
1647 	 */
1648 	db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
1649 	    object->shadow_count,
1650 	    object->backing_object ? object->backing_object->ref_count : 0,
1651 	    object->backing_object, (long)object->backing_object_offset);
1652 
1653 	if (!full)
1654 		return;
1655 
1656 	db_indent += 2;
1657 	count = 0;
1658 	for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) {
1659 		if (count == 0)
1660 			db_iprintf("memory:=");
1661 		else if (count == 6) {
1662 			db_printf("\n");
1663 			db_iprintf(" ...");
1664 			count = 0;
1665 		} else
1666 			db_printf(",");
1667 		count++;
1668 
1669 		db_printf("(off=0x%lx,page=0x%lx)",
1670 		    (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
1671 	}
1672 	if (count != 0)
1673 		db_printf("\n");
1674 	db_indent -= 2;
1675 }
1676 
1677 /* XXX. */
1678 #undef count
1679 
1680 /* XXX need this non-static entry for calling from vm_map_print. */
1681 void
1682 vm_object_print(addr, have_addr, count, modif)
1683         /* db_expr_t */ long addr;
1684 	boolean_t have_addr;
1685 	/* db_expr_t */ long count;
1686 	char *modif;
1687 {
1688 	vm_object_print_static(addr, have_addr, count, modif);
1689 }
1690 
1691 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
1692 {
1693 	vm_object_t object;
1694 	int nl = 0;
1695 	int c;
1696 	for (object = TAILQ_FIRST(&vm_object_list);
1697 			object != NULL;
1698 			object = TAILQ_NEXT(object, object_list)) {
1699 		vm_pindex_t idx, fidx;
1700 		vm_pindex_t osize;
1701 		vm_offset_t pa = -1, padiff;
1702 		int rcount;
1703 		vm_page_t m;
1704 
1705 		db_printf("new object: %p\n", (void *)object);
1706 		if ( nl > 18) {
1707 			c = cngetc();
1708 			if (c != ' ')
1709 				return;
1710 			nl = 0;
1711 		}
1712 		nl++;
1713 		rcount = 0;
1714 		fidx = 0;
1715 		osize = object->size;
1716 		if (osize > 128)
1717 			osize = 128;
1718 		for(idx=0;idx<osize;idx++) {
1719 			m = vm_page_lookup(object, idx);
1720 			if (m == NULL) {
1721 				if (rcount) {
1722 					db_printf(" index(%d)run(%d)pa(0x%x)\n",
1723 						fidx, rcount, pa);
1724 					if ( nl > 18) {
1725 						c = cngetc();
1726 						if (c != ' ')
1727 							return;
1728 						nl = 0;
1729 					}
1730 					nl++;
1731 					rcount = 0;
1732 				}
1733 				continue;
1734 			}
1735 
1736 
1737 			if (rcount &&
1738 				(VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
1739 				++rcount;
1740 				continue;
1741 			}
1742 			if (rcount) {
1743 				padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
1744 				padiff >>= PAGE_SHIFT;
1745 				padiff &= PQ_L2_MASK;
1746 				if (padiff == 0) {
1747 					pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
1748 					++rcount;
1749 					continue;
1750 				}
1751 				db_printf(" index(%d)run(%d)pa(0x%x)", fidx, rcount, pa);
1752 				db_printf("pd(%d)\n", padiff);
1753 				if ( nl > 18) {
1754 					c = cngetc();
1755 					if (c != ' ')
1756 						return;
1757 					nl = 0;
1758 				}
1759 				nl++;
1760 			}
1761 			fidx = idx;
1762 			pa = VM_PAGE_TO_PHYS(m);
1763 			rcount = 1;
1764 		}
1765 		if (rcount) {
1766 			db_printf(" index(%d)run(%d)pa(0x%x)\n", fidx, rcount, pa);
1767 			if ( nl > 18) {
1768 				c = cngetc();
1769 				if (c != ' ')
1770 					return;
1771 				nl = 0;
1772 			}
1773 			nl++;
1774 		}
1775 	}
1776 }
1777 #endif /* DDB */
1778