kernel - Break up scheduler and loadavg callout
[dragonfly.git] / sys / vm / vm_object.c
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1 /*
2 * Copyright (c) 1991, 1993, 2013
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
32 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
50 * Carnegie Mellon requests users of this software to return to
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
60 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $
64 * Virtual memory object module.
67 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <sys/proc.h> /* for curproc, pageproc */
70 #include <sys/thread.h>
71 #include <sys/vnode.h>
72 #include <sys/vmmeter.h>
73 #include <sys/mman.h>
74 #include <sys/mount.h>
75 #include <sys/kernel.h>
76 #include <sys/sysctl.h>
77 #include <sys/refcount.h>
79 #include <vm/vm.h>
80 #include <vm/vm_param.h>
81 #include <vm/pmap.h>
82 #include <vm/vm_map.h>
83 #include <vm/vm_object.h>
84 #include <vm/vm_page.h>
85 #include <vm/vm_pageout.h>
86 #include <vm/vm_pager.h>
87 #include <vm/swap_pager.h>
88 #include <vm/vm_kern.h>
89 #include <vm/vm_extern.h>
90 #include <vm/vm_zone.h>
92 #include <vm/vm_page2.h>
94 #include <machine/specialreg.h>
96 #define EASY_SCAN_FACTOR 8
98 static void vm_object_qcollapse(vm_object_t object,
99 vm_object_t backing_object);
100 static void vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
101 int pagerflags);
102 static void vm_object_lock_init(vm_object_t);
106 * Virtual memory objects maintain the actual data
107 * associated with allocated virtual memory. A given
108 * page of memory exists within exactly one object.
110 * An object is only deallocated when all "references"
111 * are given up. Only one "reference" to a given
112 * region of an object should be writeable.
114 * Associated with each object is a list of all resident
115 * memory pages belonging to that object; this list is
116 * maintained by the "vm_page" module, and locked by the object's
117 * lock.
119 * Each object also records a "pager" routine which is
120 * used to retrieve (and store) pages to the proper backing
121 * storage. In addition, objects may be backed by other
122 * objects from which they were virtual-copied.
124 * The only items within the object structure which are
125 * modified after time of creation are:
126 * reference count locked by object's lock
127 * pager routine locked by object's lock
131 struct vm_object kernel_object;
133 static long object_collapses;
134 static long object_bypasses;
136 struct vm_object_hash vm_object_hash[VMOBJ_HSIZE];
138 MALLOC_DEFINE(M_VM_OBJECT, "vm_object", "vm_object structures");
140 #if defined(DEBUG_LOCKS)
142 #define vm_object_vndeallocate(obj, vpp) \
143 debugvm_object_vndeallocate(obj, vpp, __FILE__, __LINE__)
146 * Debug helper to track hold/drop/ref/deallocate calls.
148 static void
149 debugvm_object_add(vm_object_t obj, char *file, int line, int addrem)
151 int i;
153 i = atomic_fetchadd_int(&obj->debug_index, 1);
154 i = i & (VMOBJ_DEBUG_ARRAY_SIZE - 1);
155 ksnprintf(obj->debug_hold_thrs[i],
156 sizeof(obj->debug_hold_thrs[i]),
157 "%c%d:(%d):%s",
158 (addrem == -1 ? '-' : (addrem == 1 ? '+' : '=')),
159 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
160 obj->ref_count,
161 curthread->td_comm);
162 obj->debug_hold_file[i] = file;
163 obj->debug_hold_line[i] = line;
164 #if 0
165 /* Uncomment for debugging obj refs/derefs in reproducable cases */
166 if (strcmp(curthread->td_comm, "sshd") == 0) {
167 kprintf("%d %p refs=%d ar=%d file: %s/%d\n",
168 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
169 obj, obj->ref_count, addrem, file, line);
171 #endif
174 #endif
177 * Misc low level routines
179 static void
180 vm_object_lock_init(vm_object_t obj)
182 #if defined(DEBUG_LOCKS)
183 int i;
185 obj->debug_index = 0;
186 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) {
187 obj->debug_hold_thrs[i][0] = 0;
188 obj->debug_hold_file[i] = NULL;
189 obj->debug_hold_line[i] = 0;
191 #endif
194 void
195 vm_object_lock_swap(void)
197 lwkt_token_swap();
200 void
201 vm_object_lock(vm_object_t obj)
203 lwkt_gettoken(&obj->token);
207 * Returns TRUE on sucesss
209 static int
210 vm_object_lock_try(vm_object_t obj)
212 return(lwkt_trytoken(&obj->token));
215 void
216 vm_object_lock_shared(vm_object_t obj)
218 lwkt_gettoken_shared(&obj->token);
221 void
222 vm_object_unlock(vm_object_t obj)
224 lwkt_reltoken(&obj->token);
227 void
228 vm_object_upgrade(vm_object_t obj)
230 lwkt_reltoken(&obj->token);
231 lwkt_gettoken(&obj->token);
234 void
235 vm_object_downgrade(vm_object_t obj)
237 lwkt_reltoken(&obj->token);
238 lwkt_gettoken_shared(&obj->token);
241 static __inline void
242 vm_object_assert_held(vm_object_t obj)
244 ASSERT_LWKT_TOKEN_HELD(&obj->token);
247 static __inline int
248 vm_quickcolor(void)
250 globaldata_t gd = mycpu;
251 int pg_color;
253 pg_color = (int)(intptr_t)gd->gd_curthread >> 10;
254 pg_color += gd->gd_quick_color;
255 gd->gd_quick_color += PQ_PRIME2;
257 return pg_color;
260 void
261 VMOBJDEBUG(vm_object_hold)(vm_object_t obj VMOBJDBARGS)
263 KKASSERT(obj != NULL);
266 * Object must be held (object allocation is stable due to callers
267 * context, typically already holding the token on a parent object)
268 * prior to potentially blocking on the lock, otherwise the object
269 * can get ripped away from us.
271 refcount_acquire(&obj->hold_count);
272 vm_object_lock(obj);
274 #if defined(DEBUG_LOCKS)
275 debugvm_object_add(obj, file, line, 1);
276 #endif
280 VMOBJDEBUG(vm_object_hold_try)(vm_object_t obj VMOBJDBARGS)
282 KKASSERT(obj != NULL);
285 * Object must be held (object allocation is stable due to callers
286 * context, typically already holding the token on a parent object)
287 * prior to potentially blocking on the lock, otherwise the object
288 * can get ripped away from us.
290 refcount_acquire(&obj->hold_count);
291 if (vm_object_lock_try(obj) == 0) {
292 if (refcount_release(&obj->hold_count)) {
293 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD))
294 kfree(obj, M_VM_OBJECT);
296 return(0);
299 #if defined(DEBUG_LOCKS)
300 debugvm_object_add(obj, file, line, 1);
301 #endif
302 return(1);
305 void
306 VMOBJDEBUG(vm_object_hold_shared)(vm_object_t obj VMOBJDBARGS)
308 KKASSERT(obj != NULL);
311 * Object must be held (object allocation is stable due to callers
312 * context, typically already holding the token on a parent object)
313 * prior to potentially blocking on the lock, otherwise the object
314 * can get ripped away from us.
316 refcount_acquire(&obj->hold_count);
317 vm_object_lock_shared(obj);
319 #if defined(DEBUG_LOCKS)
320 debugvm_object_add(obj, file, line, 1);
321 #endif
325 * Drop the token and hold_count on the object.
327 * WARNING! Token might be shared.
329 void
330 VMOBJDEBUG(vm_object_drop)(vm_object_t obj VMOBJDBARGS)
332 if (obj == NULL)
333 return;
336 * No new holders should be possible once we drop hold_count 1->0 as
337 * there is no longer any way to reference the object.
339 KKASSERT(obj->hold_count > 0);
340 if (refcount_release(&obj->hold_count)) {
341 #if defined(DEBUG_LOCKS)
342 debugvm_object_add(obj, file, line, -1);
343 #endif
345 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) {
346 vm_object_unlock(obj);
347 kfree(obj, M_VM_OBJECT);
348 } else {
349 vm_object_unlock(obj);
351 } else {
352 #if defined(DEBUG_LOCKS)
353 debugvm_object_add(obj, file, line, -1);
354 #endif
355 vm_object_unlock(obj);
360 * Initialize a freshly allocated object, returning a held object.
362 * Used only by vm_object_allocate(), zinitna() and vm_object_init().
364 * No requirements.
366 void
367 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
369 struct vm_object_hash *hash;
371 RB_INIT(&object->rb_memq);
372 LIST_INIT(&object->shadow_head);
373 lwkt_token_init(&object->token, "vmobj");
375 object->type = type;
376 object->size = size;
377 object->ref_count = 1;
378 object->memattr = VM_MEMATTR_DEFAULT;
379 object->hold_count = 0;
380 object->flags = 0;
381 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
382 vm_object_set_flag(object, OBJ_ONEMAPPING);
383 object->paging_in_progress = 0;
384 object->resident_page_count = 0;
385 object->shadow_count = 0;
386 /* cpu localization twist */
387 object->pg_color = vm_quickcolor();
388 object->handle = NULL;
389 object->backing_object = NULL;
390 object->backing_object_offset = (vm_ooffset_t)0;
392 atomic_add_int(&object->generation, 1);
393 object->swblock_count = 0;
394 RB_INIT(&object->swblock_root);
395 vm_object_lock_init(object);
396 pmap_object_init(object);
398 vm_object_hold(object);
400 hash = VMOBJ_HASH(object);
401 lwkt_gettoken(&hash->token);
402 TAILQ_INSERT_TAIL(&hash->list, object, object_list);
403 lwkt_reltoken(&hash->token);
407 * Initialize a VM object.
409 void
410 vm_object_init(vm_object_t object, vm_pindex_t size)
412 _vm_object_allocate(OBJT_DEFAULT, size, object);
413 vm_object_drop(object);
417 * Initialize the VM objects module.
419 * Called from the low level boot code only. Note that this occurs before
420 * kmalloc is initialized so we cannot allocate any VM objects.
422 void
423 vm_object_init1(void)
425 int i;
427 for (i = 0; i < VMOBJ_HSIZE; ++i) {
428 TAILQ_INIT(&vm_object_hash[i].list);
429 lwkt_token_init(&vm_object_hash[i].token, "vmobjlst");
432 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd),
433 &kernel_object);
434 vm_object_drop(&kernel_object);
437 void
438 vm_object_init2(void)
440 kmalloc_set_unlimited(M_VM_OBJECT);
444 * Allocate and return a new object of the specified type and size.
446 * No requirements.
448 vm_object_t
449 vm_object_allocate(objtype_t type, vm_pindex_t size)
451 vm_object_t obj;
453 obj = kmalloc(sizeof(*obj), M_VM_OBJECT, M_INTWAIT|M_ZERO);
454 _vm_object_allocate(type, size, obj);
455 vm_object_drop(obj);
457 return (obj);
461 * This version returns a held object, allowing further atomic initialization
462 * of the object.
464 vm_object_t
465 vm_object_allocate_hold(objtype_t type, vm_pindex_t size)
467 vm_object_t obj;
469 obj = kmalloc(sizeof(*obj), M_VM_OBJECT, M_INTWAIT|M_ZERO);
470 _vm_object_allocate(type, size, obj);
472 return (obj);
476 * Add an additional reference to a vm_object. The object must already be
477 * held. The original non-lock version is no longer supported. The object
478 * must NOT be chain locked by anyone at the time the reference is added.
480 * Referencing a chain-locked object can blow up the fairly sensitive
481 * ref_count and shadow_count tests in the deallocator. Most callers
482 * will call vm_object_chain_wait() prior to calling
483 * vm_object_reference_locked() to avoid the case.
485 * The object must be held, but may be held shared if desired (hence why
486 * we use an atomic op).
488 void
489 VMOBJDEBUG(vm_object_reference_locked)(vm_object_t object VMOBJDBARGS)
491 KKASSERT(object != NULL);
492 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
493 KKASSERT((object->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) == 0);
494 atomic_add_int(&object->ref_count, 1);
495 if (object->type == OBJT_VNODE) {
496 vref(object->handle);
497 /* XXX what if the vnode is being destroyed? */
499 #if defined(DEBUG_LOCKS)
500 debugvm_object_add(object, file, line, 1);
501 #endif
505 * This version is only allowed for vnode objects.
507 void
508 VMOBJDEBUG(vm_object_reference_quick)(vm_object_t object VMOBJDBARGS)
510 KKASSERT(object->type == OBJT_VNODE);
511 atomic_add_int(&object->ref_count, 1);
512 vref(object->handle);
513 #if defined(DEBUG_LOCKS)
514 debugvm_object_add(object, file, line, 1);
515 #endif
519 * Object OBJ_CHAINLOCK lock handling.
521 * The caller can chain-lock backing objects recursively and then
522 * use vm_object_chain_release_all() to undo the whole chain.
524 * Chain locks are used to prevent collapses and are only applicable
525 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
526 * on other object types are ignored. This is also important because
527 * it allows e.g. the vnode underlying a memory mapping to take concurrent
528 * faults.
530 * The object must usually be held on entry, though intermediate
531 * objects need not be held on release. The object must be held exclusively,
532 * NOT shared. Note that the prefault path checks the shared state and
533 * avoids using the chain functions.
535 void
536 vm_object_chain_wait(vm_object_t object, int shared)
538 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
539 for (;;) {
540 uint32_t chainlk = object->chainlk;
542 cpu_ccfence();
543 if (shared) {
544 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
545 tsleep_interlock(object, 0);
546 if (atomic_cmpset_int(&object->chainlk,
547 chainlk,
548 chainlk | CHAINLK_WAIT)) {
549 tsleep(object, PINTERLOCKED,
550 "objchns", 0);
552 /* retry */
553 } else {
554 break;
556 /* retry */
557 } else {
558 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
559 tsleep_interlock(object, 0);
560 if (atomic_cmpset_int(&object->chainlk,
561 chainlk,
562 chainlk | CHAINLK_WAIT))
564 tsleep(object, PINTERLOCKED,
565 "objchnx", 0);
567 /* retry */
568 } else {
569 if (atomic_cmpset_int(&object->chainlk,
570 chainlk,
571 chainlk & ~CHAINLK_WAIT))
573 if (chainlk & CHAINLK_WAIT)
574 wakeup(object);
575 break;
577 /* retry */
580 /* retry */
584 void
585 vm_object_chain_acquire(vm_object_t object, int shared)
587 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
588 return;
589 if (vm_shared_fault == 0)
590 shared = 0;
592 for (;;) {
593 uint32_t chainlk = object->chainlk;
595 cpu_ccfence();
596 if (shared) {
597 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
598 tsleep_interlock(object, 0);
599 if (atomic_cmpset_int(&object->chainlk,
600 chainlk,
601 chainlk | CHAINLK_WAIT)) {
602 tsleep(object, PINTERLOCKED,
603 "objchns", 0);
605 /* retry */
606 } else if (atomic_cmpset_int(&object->chainlk,
607 chainlk, chainlk + 1)) {
608 break;
610 /* retry */
611 } else {
612 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
613 tsleep_interlock(object, 0);
614 if (atomic_cmpset_int(&object->chainlk,
615 chainlk,
616 chainlk |
617 CHAINLK_WAIT |
618 CHAINLK_EXCLREQ)) {
619 tsleep(object, PINTERLOCKED,
620 "objchnx", 0);
622 /* retry */
623 } else {
624 if (atomic_cmpset_int(&object->chainlk,
625 chainlk,
626 (chainlk | CHAINLK_EXCL) &
627 ~(CHAINLK_EXCLREQ |
628 CHAINLK_WAIT))) {
629 if (chainlk & CHAINLK_WAIT)
630 wakeup(object);
631 break;
633 /* retry */
636 /* retry */
640 void
641 vm_object_chain_release(vm_object_t object)
643 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
644 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
645 return;
646 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
647 for (;;) {
648 uint32_t chainlk = object->chainlk;
650 cpu_ccfence();
651 if (chainlk & CHAINLK_MASK) {
652 if ((chainlk & CHAINLK_MASK) == 1 &&
653 atomic_cmpset_int(&object->chainlk,
654 chainlk,
655 (chainlk - 1) & ~CHAINLK_WAIT)) {
656 if (chainlk & CHAINLK_WAIT)
657 wakeup(object);
658 break;
660 if ((chainlk & CHAINLK_MASK) > 1 &&
661 atomic_cmpset_int(&object->chainlk,
662 chainlk, chainlk - 1)) {
663 break;
665 /* retry */
666 } else {
667 KKASSERT(chainlk & CHAINLK_EXCL);
668 if (atomic_cmpset_int(&object->chainlk,
669 chainlk,
670 chainlk & ~(CHAINLK_EXCL |
671 CHAINLK_WAIT))) {
672 if (chainlk & CHAINLK_WAIT)
673 wakeup(object);
674 break;
681 * Release the chain from first_object through and including stopobj.
682 * The caller is typically holding the first and last object locked
683 * (shared or exclusive) to prevent destruction races.
685 * We release stopobj first as an optimization as this object is most
686 * likely to be shared across multiple processes.
688 void
689 vm_object_chain_release_all(vm_object_t first_object, vm_object_t stopobj)
691 vm_object_t backing_object;
692 vm_object_t object;
694 vm_object_chain_release(stopobj);
695 object = first_object;
697 while (object != stopobj) {
698 KKASSERT(object);
699 backing_object = object->backing_object;
700 vm_object_chain_release(object);
701 object = backing_object;
706 * Dereference an object and its underlying vnode. The object may be
707 * held shared. On return the object will remain held.
709 * This function may return a vnode in *vpp which the caller must release
710 * after the caller drops its own lock. If vpp is NULL, we assume that
711 * the caller was holding an exclusive lock on the object and we vrele()
712 * the vp ourselves.
714 static void
715 VMOBJDEBUG(vm_object_vndeallocate)(vm_object_t object, struct vnode **vpp
716 VMOBJDBARGS)
718 struct vnode *vp = (struct vnode *) object->handle;
720 KASSERT(object->type == OBJT_VNODE,
721 ("vm_object_vndeallocate: not a vnode object"));
722 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
723 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
724 #ifdef INVARIANTS
725 if (object->ref_count == 0) {
726 vprint("vm_object_vndeallocate", vp);
727 panic("vm_object_vndeallocate: bad object reference count");
729 #endif
730 for (;;) {
731 int count = object->ref_count;
732 cpu_ccfence();
733 if (count == 1) {
734 vm_object_upgrade(object);
735 if (atomic_cmpset_int(&object->ref_count, count, 0)) {
736 vclrflags(vp, VTEXT);
737 break;
739 } else {
740 if (atomic_cmpset_int(&object->ref_count,
741 count, count - 1)) {
742 break;
745 /* retry */
747 #if defined(DEBUG_LOCKS)
748 debugvm_object_add(object, file, line, -1);
749 #endif
752 * vrele or return the vp to vrele. We can only safely vrele(vp)
753 * if the object was locked exclusively. But there are two races
754 * here.
756 * We had to upgrade the object above to safely clear VTEXT
757 * but the alternative path where the shared lock is retained
758 * can STILL race to 0 in other paths and cause our own vrele()
759 * to terminate the vnode. We can't allow that if the VM object
760 * is still locked shared.
762 if (vpp)
763 *vpp = vp;
764 else
765 vrele(vp);
769 * Release a reference to the specified object, gained either through a
770 * vm_object_allocate or a vm_object_reference call. When all references
771 * are gone, storage associated with this object may be relinquished.
773 * The caller does not have to hold the object locked but must have control
774 * over the reference in question in order to guarantee that the object
775 * does not get ripped out from under us.
777 * XXX Currently all deallocations require an exclusive lock.
779 void
780 VMOBJDEBUG(vm_object_deallocate)(vm_object_t object VMOBJDBARGS)
782 struct vnode *vp;
783 int count;
785 if (object == NULL)
786 return;
788 for (;;) {
789 count = object->ref_count;
790 cpu_ccfence();
793 * If decrementing the count enters into special handling
794 * territory (0, 1, or 2) we have to do it the hard way.
795 * Fortunate though, objects with only a few refs like this
796 * are not likely to be heavily contended anyway.
798 * For vnode objects we only care about 1->0 transitions.
800 if (count <= 3 || (object->type == OBJT_VNODE && count <= 1)) {
801 #if defined(DEBUG_LOCKS)
802 debugvm_object_add(object, file, line, 0);
803 #endif
804 vm_object_hold(object);
805 vm_object_deallocate_locked(object);
806 vm_object_drop(object);
807 break;
811 * Try to decrement ref_count without acquiring a hold on
812 * the object. This is particularly important for the exec*()
813 * and exit*() code paths because the program binary may
814 * have a great deal of sharing and an exclusive lock will
815 * crowbar performance in those circumstances.
817 if (object->type == OBJT_VNODE) {
818 vp = (struct vnode *)object->handle;
819 if (atomic_cmpset_int(&object->ref_count,
820 count, count - 1)) {
821 #if defined(DEBUG_LOCKS)
822 debugvm_object_add(object, file, line, -1);
823 #endif
825 vrele(vp);
826 break;
828 /* retry */
829 } else {
830 if (atomic_cmpset_int(&object->ref_count,
831 count, count - 1)) {
832 #if defined(DEBUG_LOCKS)
833 debugvm_object_add(object, file, line, -1);
834 #endif
835 break;
837 /* retry */
839 /* retry */
843 void
844 VMOBJDEBUG(vm_object_deallocate_locked)(vm_object_t object VMOBJDBARGS)
846 struct vm_object_dealloc_list *dlist = NULL;
847 struct vm_object_dealloc_list *dtmp;
848 vm_object_t temp;
849 int must_drop = 0;
852 * We may chain deallocate object, but additional objects may
853 * collect on the dlist which also have to be deallocated. We
854 * must avoid a recursion, vm_object chains can get deep.
857 again:
858 while (object != NULL) {
860 * vnode case, caller either locked the object exclusively
861 * or this is a recursion with must_drop != 0 and the vnode
862 * object will be locked shared.
864 * If locked shared we have to drop the object before we can
865 * call vrele() or risk a shared/exclusive livelock.
867 if (object->type == OBJT_VNODE) {
868 ASSERT_LWKT_TOKEN_HELD(&object->token);
869 if (must_drop) {
870 struct vnode *tmp_vp;
872 vm_object_vndeallocate(object, &tmp_vp);
873 vm_object_drop(object);
874 must_drop = 0;
875 object = NULL;
876 vrele(tmp_vp);
877 } else {
878 vm_object_vndeallocate(object, NULL);
880 break;
882 ASSERT_LWKT_TOKEN_HELD_EXCL(&object->token);
885 * Normal case (object is locked exclusively)
887 if (object->ref_count == 0) {
888 panic("vm_object_deallocate: object deallocated "
889 "too many times: %d", object->type);
891 if (object->ref_count > 2) {
892 atomic_add_int(&object->ref_count, -1);
893 #if defined(DEBUG_LOCKS)
894 debugvm_object_add(object, file, line, -1);
895 #endif
896 break;
900 * Here on ref_count of one or two, which are special cases for
901 * objects.
903 * Nominal ref_count > 1 case if the second ref is not from
904 * a shadow.
906 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
908 if (object->ref_count == 2 && object->shadow_count == 0) {
909 if (object->type == OBJT_DEFAULT ||
910 object->type == OBJT_SWAP) {
911 vm_object_set_flag(object, OBJ_ONEMAPPING);
913 atomic_add_int(&object->ref_count, -1);
914 #if defined(DEBUG_LOCKS)
915 debugvm_object_add(object, file, line, -1);
916 #endif
917 break;
921 * If the second ref is from a shadow we chain along it
922 * upwards if object's handle is exhausted.
924 * We have to decrement object->ref_count before potentially
925 * collapsing the first shadow object or the collapse code
926 * will not be able to handle the degenerate case to remove
927 * object. However, if we do it too early the object can
928 * get ripped out from under us.
930 if (object->ref_count == 2 && object->shadow_count == 1 &&
931 object->handle == NULL && (object->type == OBJT_DEFAULT ||
932 object->type == OBJT_SWAP)) {
933 temp = LIST_FIRST(&object->shadow_head);
934 KKASSERT(temp != NULL);
935 vm_object_hold(temp);
938 * Wait for any paging to complete so the collapse
939 * doesn't (or isn't likely to) qcollapse. pip
940 * waiting must occur before we acquire the
941 * chainlock.
943 while (
944 temp->paging_in_progress ||
945 object->paging_in_progress
947 vm_object_pip_wait(temp, "objde1");
948 vm_object_pip_wait(object, "objde2");
952 * If the parent is locked we have to give up, as
953 * otherwise we would be acquiring locks in the
954 * wrong order and potentially deadlock.
956 if (temp->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) {
957 vm_object_drop(temp);
958 goto skip;
960 vm_object_chain_acquire(temp, 0);
963 * Recheck/retry after the hold and the paging
964 * wait, both of which can block us.
966 if (object->ref_count != 2 ||
967 object->shadow_count != 1 ||
968 object->handle ||
969 LIST_FIRST(&object->shadow_head) != temp ||
970 (object->type != OBJT_DEFAULT &&
971 object->type != OBJT_SWAP)) {
972 vm_object_chain_release(temp);
973 vm_object_drop(temp);
974 continue;
978 * We can safely drop object's ref_count now.
980 KKASSERT(object->ref_count == 2);
981 atomic_add_int(&object->ref_count, -1);
982 #if defined(DEBUG_LOCKS)
983 debugvm_object_add(object, file, line, -1);
984 #endif
987 * If our single parent is not collapseable just
988 * decrement ref_count (2->1) and stop.
990 if (temp->handle || (temp->type != OBJT_DEFAULT &&
991 temp->type != OBJT_SWAP)) {
992 vm_object_chain_release(temp);
993 vm_object_drop(temp);
994 break;
998 * At this point we have already dropped object's
999 * ref_count so it is possible for a race to
1000 * deallocate obj out from under us. Any collapse
1001 * will re-check the situation. We must not block
1002 * until we are able to collapse.
1004 * Bump temp's ref_count to avoid an unwanted
1005 * degenerate recursion (can't call
1006 * vm_object_reference_locked() because it asserts
1007 * that CHAINLOCK is not set).
1009 atomic_add_int(&temp->ref_count, 1);
1010 KKASSERT(temp->ref_count > 1);
1013 * Collapse temp, then deallocate the extra ref
1014 * formally.
1016 vm_object_collapse(temp, &dlist);
1017 vm_object_chain_release(temp);
1018 if (must_drop) {
1019 vm_object_lock_swap();
1020 vm_object_drop(object);
1022 object = temp;
1023 must_drop = 1;
1024 continue;
1028 * Drop the ref and handle termination on the 1->0 transition.
1029 * We may have blocked above so we have to recheck.
1031 skip:
1032 KKASSERT(object->ref_count != 0);
1033 if (object->ref_count >= 2) {
1034 atomic_add_int(&object->ref_count, -1);
1035 #if defined(DEBUG_LOCKS)
1036 debugvm_object_add(object, file, line, -1);
1037 #endif
1038 break;
1040 KKASSERT(object->ref_count == 1);
1043 * 1->0 transition. Chain through the backing_object.
1044 * Maintain the ref until we've located the backing object,
1045 * then re-check.
1047 while ((temp = object->backing_object) != NULL) {
1048 if (temp->type == OBJT_VNODE)
1049 vm_object_hold_shared(temp);
1050 else
1051 vm_object_hold(temp);
1052 if (temp == object->backing_object)
1053 break;
1054 vm_object_drop(temp);
1058 * 1->0 transition verified, retry if ref_count is no longer
1059 * 1. Otherwise disconnect the backing_object (temp) and
1060 * clean up.
1062 if (object->ref_count != 1) {
1063 vm_object_drop(temp);
1064 continue;
1068 * It shouldn't be possible for the object to be chain locked
1069 * if we're removing the last ref on it.
1071 * Removing object from temp's shadow list requires dropping
1072 * temp, which we will do on loop.
1074 * NOTE! vnodes do not use the shadow list, but still have
1075 * the backing_object reference.
1077 KKASSERT((object->chainlk & (CHAINLK_EXCL|CHAINLK_MASK)) == 0);
1079 if (temp) {
1080 if (object->flags & OBJ_ONSHADOW) {
1081 LIST_REMOVE(object, shadow_list);
1082 temp->shadow_count--;
1083 atomic_add_int(&temp->generation, 1);
1084 vm_object_clear_flag(object, OBJ_ONSHADOW);
1086 object->backing_object = NULL;
1089 atomic_add_int(&object->ref_count, -1);
1090 if ((object->flags & OBJ_DEAD) == 0)
1091 vm_object_terminate(object);
1092 if (must_drop && temp)
1093 vm_object_lock_swap();
1094 if (must_drop)
1095 vm_object_drop(object);
1096 object = temp;
1097 must_drop = 1;
1100 if (must_drop && object)
1101 vm_object_drop(object);
1104 * Additional tail recursion on dlist. Avoid a recursion. Objects
1105 * on the dlist have a hold count but are not locked.
1107 if ((dtmp = dlist) != NULL) {
1108 dlist = dtmp->next;
1109 object = dtmp->object;
1110 kfree(dtmp, M_TEMP);
1112 vm_object_lock(object); /* already held, add lock */
1113 must_drop = 1; /* and we're responsible for it */
1114 goto again;
1119 * Destroy the specified object, freeing up related resources.
1121 * The object must have zero references.
1123 * The object must held. The caller is responsible for dropping the object
1124 * after terminate returns. Terminate does NOT drop the object.
1126 static int vm_object_terminate_callback(vm_page_t p, void *data);
1128 void
1129 vm_object_terminate(vm_object_t object)
1131 struct rb_vm_page_scan_info info;
1132 struct vm_object_hash *hash;
1135 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1136 * able to safely block.
1138 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1139 KKASSERT((object->flags & OBJ_DEAD) == 0);
1140 vm_object_set_flag(object, OBJ_DEAD);
1143 * Wait for the pageout daemon to be done with the object
1145 vm_object_pip_wait(object, "objtrm1");
1147 KASSERT(!object->paging_in_progress,
1148 ("vm_object_terminate: pageout in progress"));
1151 * Clean and free the pages, as appropriate. All references to the
1152 * object are gone, so we don't need to lock it.
1154 if (object->type == OBJT_VNODE) {
1155 struct vnode *vp;
1158 * Clean pages and flush buffers.
1160 * NOTE! TMPFS buffer flushes do not typically flush the
1161 * actual page to swap as this would be highly
1162 * inefficient, and normal filesystems usually wrap
1163 * page flushes with buffer cache buffers.
1165 * To deal with this we have to call vinvalbuf() both
1166 * before and after the vm_object_page_clean().
1168 vp = (struct vnode *) object->handle;
1169 vinvalbuf(vp, V_SAVE, 0, 0);
1170 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
1171 vinvalbuf(vp, V_SAVE, 0, 0);
1175 * Wait for any I/O to complete, after which there had better not
1176 * be any references left on the object.
1178 vm_object_pip_wait(object, "objtrm2");
1180 if (object->ref_count != 0) {
1181 panic("vm_object_terminate: object with references, "
1182 "ref_count=%d", object->ref_count);
1186 * Cleanup any shared pmaps associated with this object.
1188 pmap_object_free(object);
1191 * Now free any remaining pages. For internal objects, this also
1192 * removes them from paging queues. Don't free wired pages, just
1193 * remove them from the object.
1195 info.count = 0;
1196 info.object = object;
1197 do {
1198 info.error = 0;
1199 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1200 vm_object_terminate_callback, &info);
1201 } while (info.error);
1204 * Let the pager know object is dead.
1206 vm_pager_deallocate(object);
1209 * Wait for the object hold count to hit 1, clean out pages as
1210 * we go. vmobj_token interlocks any race conditions that might
1211 * pick the object up from the vm_object_list after we have cleared
1212 * rb_memq.
1214 for (;;) {
1215 if (RB_ROOT(&object->rb_memq) == NULL)
1216 break;
1217 kprintf("vm_object_terminate: Warning, object %p "
1218 "still has %ld pages\n",
1219 object, object->resident_page_count);
1220 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1221 vm_object_terminate_callback, &info);
1225 * There had better not be any pages left
1227 KKASSERT(object->resident_page_count == 0);
1230 * Remove the object from the global object list.
1232 hash = VMOBJ_HASH(object);
1233 lwkt_gettoken(&hash->token);
1234 TAILQ_REMOVE(&hash->list, object, object_list);
1235 lwkt_reltoken(&hash->token);
1237 if (object->ref_count != 0) {
1238 panic("vm_object_terminate2: object with references, "
1239 "ref_count=%d", object->ref_count);
1243 * NOTE: The object hold_count is at least 1, so we cannot kfree()
1244 * the object here. See vm_object_drop().
1249 * The caller must hold the object.
1251 static int
1252 vm_object_terminate_callback(vm_page_t p, void *data)
1254 struct rb_vm_page_scan_info *info = data;
1255 vm_object_t object;
1257 object = p->object;
1258 KKASSERT(object == info->object);
1259 if (vm_page_busy_try(p, TRUE)) {
1260 vm_page_sleep_busy(p, TRUE, "vmotrm");
1261 info->error = 1;
1262 return 0;
1264 if (object != p->object) {
1265 /* XXX remove once we determine it can't happen */
1266 kprintf("vm_object_terminate: Warning: Encountered "
1267 "busied page %p on queue %d\n", p, p->queue);
1268 vm_page_wakeup(p);
1269 info->error = 1;
1270 } else if (p->wire_count == 0) {
1272 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1274 vm_page_free(p);
1275 mycpu->gd_cnt.v_pfree++;
1276 } else {
1277 if (p->queue != PQ_NONE)
1278 kprintf("vm_object_terminate: Warning: Encountered "
1279 "wired page %p on queue %d\n", p, p->queue);
1280 vm_page_remove(p);
1281 vm_page_wakeup(p);
1285 * Must be at end to avoid SMP races, caller holds object token
1287 if ((++info->count & 63) == 0)
1288 lwkt_user_yield();
1289 return(0);
1293 * Clean all dirty pages in the specified range of object. Leaves page
1294 * on whatever queue it is currently on. If NOSYNC is set then do not
1295 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1296 * leaving the object dirty.
1298 * When stuffing pages asynchronously, allow clustering. XXX we need a
1299 * synchronous clustering mode implementation.
1301 * Odd semantics: if start == end, we clean everything.
1303 * The object must be locked? XXX
1305 static int vm_object_page_clean_pass1(struct vm_page *p, void *data);
1306 static int vm_object_page_clean_pass2(struct vm_page *p, void *data);
1308 void
1309 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1310 int flags)
1312 struct rb_vm_page_scan_info info;
1313 struct vnode *vp;
1314 int wholescan;
1315 int pagerflags;
1316 int generation;
1318 vm_object_hold(object);
1319 if (object->type != OBJT_VNODE ||
1320 (object->flags & OBJ_MIGHTBEDIRTY) == 0) {
1321 vm_object_drop(object);
1322 return;
1325 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ?
1326 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
1327 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
1329 vp = object->handle;
1332 * Interlock other major object operations. This allows us to
1333 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1335 vm_object_set_flag(object, OBJ_CLEANING);
1338 * Handle 'entire object' case
1340 info.start_pindex = start;
1341 if (end == 0) {
1342 info.end_pindex = object->size - 1;
1343 } else {
1344 info.end_pindex = end - 1;
1346 wholescan = (start == 0 && info.end_pindex == object->size - 1);
1347 info.limit = flags;
1348 info.pagerflags = pagerflags;
1349 info.object = object;
1352 * If cleaning the entire object do a pass to mark the pages read-only.
1353 * If everything worked out ok, clear OBJ_WRITEABLE and
1354 * OBJ_MIGHTBEDIRTY.
1356 if (wholescan) {
1357 info.error = 0;
1358 info.count = 0;
1359 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1360 vm_object_page_clean_pass1, &info);
1361 if (info.error == 0) {
1362 vm_object_clear_flag(object,
1363 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
1364 if (object->type == OBJT_VNODE &&
1365 (vp = (struct vnode *)object->handle) != NULL) {
1367 * Use new-style interface to clear VISDIRTY
1368 * because the vnode is not necessarily removed
1369 * from the syncer list(s) as often as it was
1370 * under the old interface, which can leave
1371 * the vnode on the syncer list after reclaim.
1373 vclrobjdirty(vp);
1379 * Do a pass to clean all the dirty pages we find.
1381 do {
1382 info.error = 0;
1383 info.count = 0;
1384 generation = object->generation;
1385 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1386 vm_object_page_clean_pass2, &info);
1387 } while (info.error || generation != object->generation);
1389 vm_object_clear_flag(object, OBJ_CLEANING);
1390 vm_object_drop(object);
1394 * The caller must hold the object.
1396 static
1398 vm_object_page_clean_pass1(struct vm_page *p, void *data)
1400 struct rb_vm_page_scan_info *info = data;
1402 KKASSERT(p->object == info->object);
1404 vm_page_flag_set(p, PG_CLEANCHK);
1405 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1406 info->error = 1;
1407 } else if (vm_page_busy_try(p, FALSE)) {
1408 info->error = 1;
1409 } else {
1410 KKASSERT(p->object == info->object);
1411 vm_page_protect(p, VM_PROT_READ);
1412 vm_page_wakeup(p);
1416 * Must be at end to avoid SMP races, caller holds object token
1418 if ((++info->count & 63) == 0)
1419 lwkt_user_yield();
1420 return(0);
1424 * The caller must hold the object
1426 static
1428 vm_object_page_clean_pass2(struct vm_page *p, void *data)
1430 struct rb_vm_page_scan_info *info = data;
1431 int generation;
1433 KKASSERT(p->object == info->object);
1436 * Do not mess with pages that were inserted after we started
1437 * the cleaning pass.
1439 if ((p->flags & PG_CLEANCHK) == 0)
1440 goto done;
1442 generation = info->object->generation;
1444 if (vm_page_busy_try(p, TRUE)) {
1445 vm_page_sleep_busy(p, TRUE, "vpcwai");
1446 info->error = 1;
1447 goto done;
1450 KKASSERT(p->object == info->object &&
1451 info->object->generation == generation);
1454 * Before wasting time traversing the pmaps, check for trivial
1455 * cases where the page cannot be dirty.
1457 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) {
1458 KKASSERT((p->dirty & p->valid) == 0 &&
1459 (p->flags & PG_NEED_COMMIT) == 0);
1460 vm_page_wakeup(p);
1461 goto done;
1465 * Check whether the page is dirty or not. The page has been set
1466 * to be read-only so the check will not race a user dirtying the
1467 * page.
1469 vm_page_test_dirty(p);
1470 if ((p->dirty & p->valid) == 0 && (p->flags & PG_NEED_COMMIT) == 0) {
1471 vm_page_flag_clear(p, PG_CLEANCHK);
1472 vm_page_wakeup(p);
1473 goto done;
1477 * If we have been asked to skip nosync pages and this is a
1478 * nosync page, skip it. Note that the object flags were
1479 * not cleared in this case (because pass1 will have returned an
1480 * error), so we do not have to set them.
1482 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1483 vm_page_flag_clear(p, PG_CLEANCHK);
1484 vm_page_wakeup(p);
1485 goto done;
1489 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1490 * the pages that get successfully flushed. Set info->error if
1491 * we raced an object modification.
1493 vm_object_page_collect_flush(info->object, p, info->pagerflags);
1494 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1497 * Must be at end to avoid SMP races, caller holds object token
1499 done:
1500 if ((++info->count & 63) == 0)
1501 lwkt_user_yield();
1502 return(0);
1506 * Collect the specified page and nearby pages and flush them out.
1507 * The number of pages flushed is returned. The passed page is busied
1508 * by the caller and we are responsible for its disposition.
1510 * The caller must hold the object.
1512 static void
1513 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags)
1515 int error;
1516 int is;
1517 int ib;
1518 int i;
1519 int page_base;
1520 vm_pindex_t pi;
1521 vm_page_t ma[BLIST_MAX_ALLOC];
1523 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1525 pi = p->pindex;
1526 page_base = pi % BLIST_MAX_ALLOC;
1527 ma[page_base] = p;
1528 ib = page_base - 1;
1529 is = page_base + 1;
1531 while (ib >= 0) {
1532 vm_page_t tp;
1534 tp = vm_page_lookup_busy_try(object, pi - page_base + ib,
1535 TRUE, &error);
1536 if (error)
1537 break;
1538 if (tp == NULL)
1539 break;
1540 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1541 (tp->flags & PG_CLEANCHK) == 0) {
1542 vm_page_wakeup(tp);
1543 break;
1545 if ((tp->queue - tp->pc) == PQ_CACHE) {
1546 vm_page_flag_clear(tp, PG_CLEANCHK);
1547 vm_page_wakeup(tp);
1548 break;
1550 vm_page_test_dirty(tp);
1551 if ((tp->dirty & tp->valid) == 0 &&
1552 (tp->flags & PG_NEED_COMMIT) == 0) {
1553 vm_page_flag_clear(tp, PG_CLEANCHK);
1554 vm_page_wakeup(tp);
1555 break;
1557 ma[ib] = tp;
1558 --ib;
1560 ++ib; /* fixup */
1562 while (is < BLIST_MAX_ALLOC &&
1563 pi - page_base + is < object->size) {
1564 vm_page_t tp;
1566 tp = vm_page_lookup_busy_try(object, pi - page_base + is,
1567 TRUE, &error);
1568 if (error)
1569 break;
1570 if (tp == NULL)
1571 break;
1572 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1573 (tp->flags & PG_CLEANCHK) == 0) {
1574 vm_page_wakeup(tp);
1575 break;
1577 if ((tp->queue - tp->pc) == PQ_CACHE) {
1578 vm_page_flag_clear(tp, PG_CLEANCHK);
1579 vm_page_wakeup(tp);
1580 break;
1582 vm_page_test_dirty(tp);
1583 if ((tp->dirty & tp->valid) == 0 &&
1584 (tp->flags & PG_NEED_COMMIT) == 0) {
1585 vm_page_flag_clear(tp, PG_CLEANCHK);
1586 vm_page_wakeup(tp);
1587 break;
1589 ma[is] = tp;
1590 ++is;
1594 * All pages in the ma[] array are busied now
1596 for (i = ib; i < is; ++i) {
1597 vm_page_flag_clear(ma[i], PG_CLEANCHK);
1598 vm_page_hold(ma[i]); /* XXX need this any more? */
1600 vm_pageout_flush(&ma[ib], is - ib, pagerflags);
1601 for (i = ib; i < is; ++i) /* XXX need this any more? */
1602 vm_page_unhold(ma[i]);
1606 * Same as vm_object_pmap_copy, except range checking really
1607 * works, and is meant for small sections of an object.
1609 * This code protects resident pages by making them read-only
1610 * and is typically called on a fork or split when a page
1611 * is converted to copy-on-write.
1613 * NOTE: If the page is already at VM_PROT_NONE, calling
1614 * vm_page_protect will have no effect.
1616 void
1617 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1619 vm_pindex_t idx;
1620 vm_page_t p;
1622 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
1623 return;
1625 vm_object_hold(object);
1626 for (idx = start; idx < end; idx++) {
1627 p = vm_page_lookup(object, idx);
1628 if (p == NULL)
1629 continue;
1630 vm_page_protect(p, VM_PROT_READ);
1632 vm_object_drop(object);
1636 * Removes all physical pages in the specified object range from all
1637 * physical maps.
1639 * The object must *not* be locked.
1642 static int vm_object_pmap_remove_callback(vm_page_t p, void *data);
1644 void
1645 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1647 struct rb_vm_page_scan_info info;
1649 if (object == NULL)
1650 return;
1651 if (start == end)
1652 return;
1653 info.start_pindex = start;
1654 info.end_pindex = end - 1;
1655 info.count = 0;
1656 info.object = object;
1658 vm_object_hold(object);
1659 do {
1660 info.error = 0;
1661 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1662 vm_object_pmap_remove_callback, &info);
1663 } while (info.error);
1664 if (start == 0 && end == object->size)
1665 vm_object_clear_flag(object, OBJ_WRITEABLE);
1666 vm_object_drop(object);
1670 * The caller must hold the object
1672 static int
1673 vm_object_pmap_remove_callback(vm_page_t p, void *data)
1675 struct rb_vm_page_scan_info *info = data;
1677 if (info->object != p->object ||
1678 p->pindex < info->start_pindex ||
1679 p->pindex > info->end_pindex) {
1680 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1681 info->object, p);
1682 info->error = 1;
1683 return(0);
1686 vm_page_protect(p, VM_PROT_NONE);
1689 * Must be at end to avoid SMP races, caller holds object token
1691 if ((++info->count & 63) == 0)
1692 lwkt_user_yield();
1693 return(0);
1697 * Implements the madvise function at the object/page level.
1699 * MADV_WILLNEED (any object)
1701 * Activate the specified pages if they are resident.
1703 * MADV_DONTNEED (any object)
1705 * Deactivate the specified pages if they are resident.
1707 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1709 * Deactivate and clean the specified pages if they are
1710 * resident. This permits the process to reuse the pages
1711 * without faulting or the kernel to reclaim the pages
1712 * without I/O.
1714 * No requirements.
1716 void
1717 vm_object_madvise(vm_object_t object, vm_pindex_t pindex,
1718 vm_pindex_t count, int advise)
1720 vm_pindex_t end, tpindex;
1721 vm_object_t tobject;
1722 vm_object_t xobj;
1723 vm_page_t m;
1724 int error;
1726 if (object == NULL)
1727 return;
1729 end = pindex + count;
1731 vm_object_hold(object);
1732 tobject = object;
1735 * Locate and adjust resident pages
1737 for (; pindex < end; pindex += 1) {
1738 relookup:
1739 if (tobject != object)
1740 vm_object_drop(tobject);
1741 tobject = object;
1742 tpindex = pindex;
1743 shadowlookup:
1745 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1746 * and those pages must be OBJ_ONEMAPPING.
1748 if (advise == MADV_FREE) {
1749 if ((tobject->type != OBJT_DEFAULT &&
1750 tobject->type != OBJT_SWAP) ||
1751 (tobject->flags & OBJ_ONEMAPPING) == 0) {
1752 continue;
1756 m = vm_page_lookup_busy_try(tobject, tpindex, TRUE, &error);
1758 if (error) {
1759 vm_page_sleep_busy(m, TRUE, "madvpo");
1760 goto relookup;
1762 if (m == NULL) {
1764 * There may be swap even if there is no backing page
1766 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1767 swap_pager_freespace(tobject, tpindex, 1);
1770 * next object
1772 while ((xobj = tobject->backing_object) != NULL) {
1773 KKASSERT(xobj != object);
1774 vm_object_hold(xobj);
1775 if (xobj == tobject->backing_object)
1776 break;
1777 vm_object_drop(xobj);
1779 if (xobj == NULL)
1780 continue;
1781 tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1782 if (tobject != object) {
1783 vm_object_lock_swap();
1784 vm_object_drop(tobject);
1786 tobject = xobj;
1787 goto shadowlookup;
1791 * If the page is not in a normal active state, we skip it.
1792 * If the page is not managed there are no page queues to
1793 * mess with. Things can break if we mess with pages in
1794 * any of the below states.
1796 if (m->wire_count ||
1797 (m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) ||
1798 m->valid != VM_PAGE_BITS_ALL
1800 vm_page_wakeup(m);
1801 continue;
1805 * Theoretically once a page is known not to be busy, an
1806 * interrupt cannot come along and rip it out from under us.
1809 if (advise == MADV_WILLNEED) {
1810 vm_page_activate(m);
1811 } else if (advise == MADV_DONTNEED) {
1812 vm_page_dontneed(m);
1813 } else if (advise == MADV_FREE) {
1815 * Mark the page clean. This will allow the page
1816 * to be freed up by the system. However, such pages
1817 * are often reused quickly by malloc()/free()
1818 * so we do not do anything that would cause
1819 * a page fault if we can help it.
1821 * Specifically, we do not try to actually free
1822 * the page now nor do we try to put it in the
1823 * cache (which would cause a page fault on reuse).
1825 * But we do make the page is freeable as we
1826 * can without actually taking the step of unmapping
1827 * it.
1829 pmap_clear_modify(m);
1830 m->dirty = 0;
1831 m->act_count = 0;
1832 vm_page_dontneed(m);
1833 if (tobject->type == OBJT_SWAP)
1834 swap_pager_freespace(tobject, tpindex, 1);
1836 vm_page_wakeup(m);
1838 if (tobject != object)
1839 vm_object_drop(tobject);
1840 vm_object_drop(object);
1844 * Create a new object which is backed by the specified existing object
1845 * range. Replace the pointer and offset that was pointing at the existing
1846 * object with the pointer/offset for the new object.
1848 * If addref is non-zero the returned object is given an additional reference.
1849 * This mechanic exists to avoid the situation where refs might be 1 and
1850 * race against a collapse when the caller intends to bump it. So the
1851 * caller cannot add the ref after the fact. Used when the caller is
1852 * duplicating a vm_map_entry.
1854 * No other requirements.
1856 void
1857 vm_object_shadow(vm_object_t *objectp, vm_ooffset_t *offset, vm_size_t length,
1858 int addref)
1860 vm_object_t source;
1861 vm_object_t result;
1862 int useshadowlist;
1864 source = *objectp;
1867 * Don't create the new object if the old object isn't shared.
1868 * We have to chain wait before adding the reference to avoid
1869 * racing a collapse or deallocation.
1871 * Clear OBJ_ONEMAPPING flag when shadowing.
1873 * The caller owns a ref on source via *objectp which we are going
1874 * to replace. This ref is inherited by the backing_object assignment.
1875 * from nobject and does not need to be incremented here.
1877 * However, we add a temporary extra reference to the original source
1878 * prior to holding nobject in case we block, to avoid races where
1879 * someone else might believe that the source can be collapsed.
1881 useshadowlist = 0;
1882 if (source) {
1883 if (source->type != OBJT_VNODE) {
1884 useshadowlist = 1;
1885 vm_object_hold(source);
1886 vm_object_chain_wait(source, 0);
1887 if (source->ref_count == 1 &&
1888 source->handle == NULL &&
1889 (source->type == OBJT_DEFAULT ||
1890 source->type == OBJT_SWAP)) {
1891 if (addref) {
1892 vm_object_reference_locked(source);
1893 vm_object_clear_flag(source,
1894 OBJ_ONEMAPPING);
1896 vm_object_drop(source);
1897 return;
1899 vm_object_reference_locked(source);
1900 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1901 } else {
1902 vm_object_reference_quick(source);
1903 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1908 * Allocate a new object with the given length. The new object
1909 * is returned referenced but we may have to add another one.
1910 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1911 * (typically because the caller is about to clone a vm_map_entry).
1913 * The source object currently has an extra reference to prevent
1914 * collapses into it while we mess with its shadow list, which
1915 * we will remove later in this routine.
1917 * The target object may require a second reference if asked for one
1918 * by the caller.
1920 result = vm_object_allocate(OBJT_DEFAULT, length);
1921 if (result == NULL)
1922 panic("vm_object_shadow: no object for shadowing");
1923 vm_object_hold(result);
1924 if (addref) {
1925 vm_object_reference_locked(result);
1926 vm_object_clear_flag(result, OBJ_ONEMAPPING);
1930 * The new object shadows the source object. Chain wait before
1931 * adjusting shadow_count or the shadow list to avoid races.
1933 * Try to optimize the result object's page color when shadowing
1934 * in order to maintain page coloring consistency in the combined
1935 * shadowed object.
1937 * The backing_object reference to source requires adding a ref to
1938 * source. We simply inherit the ref from the original *objectp
1939 * (which we are replacing) so no additional refs need to be added.
1940 * (we must still clean up the extra ref we had to prevent collapse
1941 * races).
1943 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1945 KKASSERT(result->backing_object == NULL);
1946 result->backing_object = source;
1947 if (source) {
1948 if (useshadowlist) {
1949 vm_object_chain_wait(source, 0);
1950 LIST_INSERT_HEAD(&source->shadow_head,
1951 result, shadow_list);
1952 source->shadow_count++;
1953 atomic_add_int(&source->generation, 1);
1954 vm_object_set_flag(result, OBJ_ONSHADOW);
1956 /* cpu localization twist */
1957 result->pg_color = vm_quickcolor();
1961 * Adjust the return storage. Drop the ref on source before
1962 * returning.
1964 result->backing_object_offset = *offset;
1965 vm_object_drop(result);
1966 *offset = 0;
1967 if (source) {
1968 if (useshadowlist) {
1969 vm_object_deallocate_locked(source);
1970 vm_object_drop(source);
1971 } else {
1972 vm_object_deallocate(source);
1977 * Return the new things
1979 *objectp = result;
1982 #define OBSC_TEST_ALL_SHADOWED 0x0001
1983 #define OBSC_COLLAPSE_NOWAIT 0x0002
1984 #define OBSC_COLLAPSE_WAIT 0x0004
1986 static int vm_object_backing_scan_callback(vm_page_t p, void *data);
1989 * The caller must hold the object.
1991 static __inline int
1992 vm_object_backing_scan(vm_object_t object, vm_object_t backing_object, int op)
1994 struct rb_vm_page_scan_info info;
1995 struct vm_object_hash *hash;
1997 vm_object_assert_held(object);
1998 vm_object_assert_held(backing_object);
2000 KKASSERT(backing_object == object->backing_object);
2001 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
2004 * Initial conditions
2006 if (op & OBSC_TEST_ALL_SHADOWED) {
2008 * We do not want to have to test for the existence of
2009 * swap pages in the backing object. XXX but with the
2010 * new swapper this would be pretty easy to do.
2012 * XXX what about anonymous MAP_SHARED memory that hasn't
2013 * been ZFOD faulted yet? If we do not test for this, the
2014 * shadow test may succeed! XXX
2016 if (backing_object->type != OBJT_DEFAULT)
2017 return(0);
2019 if (op & OBSC_COLLAPSE_WAIT) {
2020 KKASSERT((backing_object->flags & OBJ_DEAD) == 0);
2021 vm_object_set_flag(backing_object, OBJ_DEAD);
2023 hash = VMOBJ_HASH(backing_object);
2024 lwkt_gettoken(&hash->token);
2025 TAILQ_REMOVE(&hash->list, backing_object, object_list);
2026 lwkt_reltoken(&hash->token);
2030 * Our scan. We have to retry if a negative error code is returned,
2031 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2032 * the scan had to be stopped because the parent does not completely
2033 * shadow the child.
2035 info.object = object;
2036 info.backing_object = backing_object;
2037 info.limit = op;
2038 info.count = 0;
2039 do {
2040 info.error = 1;
2041 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL,
2042 vm_object_backing_scan_callback,
2043 &info);
2044 } while (info.error < 0);
2046 return(info.error);
2050 * The caller must hold the object.
2052 static int
2053 vm_object_backing_scan_callback(vm_page_t p, void *data)
2055 struct rb_vm_page_scan_info *info = data;
2056 vm_object_t backing_object;
2057 vm_object_t object;
2058 vm_pindex_t pindex;
2059 vm_pindex_t new_pindex;
2060 vm_pindex_t backing_offset_index;
2061 int op;
2063 pindex = p->pindex;
2064 new_pindex = pindex - info->backing_offset_index;
2065 op = info->limit;
2066 object = info->object;
2067 backing_object = info->backing_object;
2068 backing_offset_index = info->backing_offset_index;
2070 if (op & OBSC_TEST_ALL_SHADOWED) {
2071 vm_page_t pp;
2074 * Ignore pages outside the parent object's range
2075 * and outside the parent object's mapping of the
2076 * backing object.
2078 * note that we do not busy the backing object's
2079 * page.
2081 if (pindex < backing_offset_index ||
2082 new_pindex >= object->size
2084 return(0);
2088 * See if the parent has the page or if the parent's
2089 * object pager has the page. If the parent has the
2090 * page but the page is not valid, the parent's
2091 * object pager must have the page.
2093 * If this fails, the parent does not completely shadow
2094 * the object and we might as well give up now.
2096 pp = vm_page_lookup(object, new_pindex);
2097 if ((pp == NULL || pp->valid == 0) &&
2098 !vm_pager_has_page(object, new_pindex)
2100 info->error = 0; /* problemo */
2101 return(-1); /* stop the scan */
2106 * Check for busy page. Note that we may have lost (p) when we
2107 * possibly blocked above.
2109 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
2110 vm_page_t pp;
2112 if (vm_page_busy_try(p, TRUE)) {
2113 if (op & OBSC_COLLAPSE_NOWAIT) {
2114 return(0);
2115 } else {
2117 * If we slept, anything could have
2118 * happened. Ask that the scan be restarted.
2120 * Since the object is marked dead, the
2121 * backing offset should not have changed.
2123 vm_page_sleep_busy(p, TRUE, "vmocol");
2124 info->error = -1;
2125 return(-1);
2130 * If (p) is no longer valid restart the scan.
2132 if (p->object != backing_object || p->pindex != pindex) {
2133 kprintf("vm_object_backing_scan: Warning: page "
2134 "%p ripped out from under us\n", p);
2135 vm_page_wakeup(p);
2136 info->error = -1;
2137 return(-1);
2140 if (op & OBSC_COLLAPSE_NOWAIT) {
2141 if (p->valid == 0 ||
2142 p->wire_count ||
2143 (p->flags & PG_NEED_COMMIT)) {
2144 vm_page_wakeup(p);
2145 return(0);
2147 } else {
2148 /* XXX what if p->valid == 0 , hold_count, etc? */
2151 KASSERT(
2152 p->object == backing_object,
2153 ("vm_object_qcollapse(): object mismatch")
2157 * Destroy any associated swap
2159 if (backing_object->type == OBJT_SWAP)
2160 swap_pager_freespace(backing_object, p->pindex, 1);
2162 if (
2163 p->pindex < backing_offset_index ||
2164 new_pindex >= object->size
2167 * Page is out of the parent object's range, we
2168 * can simply destroy it.
2170 vm_page_protect(p, VM_PROT_NONE);
2171 vm_page_free(p);
2172 return(0);
2175 pp = vm_page_lookup(object, new_pindex);
2176 if (pp != NULL || vm_pager_has_page(object, new_pindex)) {
2178 * page already exists in parent OR swap exists
2179 * for this location in the parent. Destroy
2180 * the original page from the backing object.
2182 * Leave the parent's page alone
2184 vm_page_protect(p, VM_PROT_NONE);
2185 vm_page_free(p);
2186 return(0);
2190 * Page does not exist in parent, rename the
2191 * page from the backing object to the main object.
2193 * If the page was mapped to a process, it can remain
2194 * mapped through the rename.
2196 if ((p->queue - p->pc) == PQ_CACHE)
2197 vm_page_deactivate(p);
2199 vm_page_rename(p, object, new_pindex);
2200 vm_page_wakeup(p);
2201 /* page automatically made dirty by rename */
2203 return(0);
2207 * This version of collapse allows the operation to occur earlier and
2208 * when paging_in_progress is true for an object... This is not a complete
2209 * operation, but should plug 99.9% of the rest of the leaks.
2211 * The caller must hold the object and backing_object and both must be
2212 * chainlocked.
2214 * (only called from vm_object_collapse)
2216 static void
2217 vm_object_qcollapse(vm_object_t object, vm_object_t backing_object)
2219 if (backing_object->ref_count == 1) {
2220 atomic_add_int(&backing_object->ref_count, 2);
2221 #if defined(DEBUG_LOCKS)
2222 debugvm_object_add(backing_object, "qcollapse", 1, 2);
2223 #endif
2224 vm_object_backing_scan(object, backing_object,
2225 OBSC_COLLAPSE_NOWAIT);
2226 atomic_add_int(&backing_object->ref_count, -2);
2227 #if defined(DEBUG_LOCKS)
2228 debugvm_object_add(backing_object, "qcollapse", 2, -2);
2229 #endif
2234 * Collapse an object with the object backing it. Pages in the backing
2235 * object are moved into the parent, and the backing object is deallocated.
2236 * Any conflict is resolved in favor of the parent's existing pages.
2238 * object must be held and chain-locked on call.
2240 * The caller must have an extra ref on object to prevent a race from
2241 * destroying it during the collapse.
2243 void
2244 vm_object_collapse(vm_object_t object, struct vm_object_dealloc_list **dlistp)
2246 struct vm_object_dealloc_list *dlist = NULL;
2247 vm_object_t backing_object;
2250 * Only one thread is attempting a collapse at any given moment.
2251 * There are few restrictions for (object) that callers of this
2252 * function check so reentrancy is likely.
2254 KKASSERT(object != NULL);
2255 vm_object_assert_held(object);
2256 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
2258 for (;;) {
2259 vm_object_t bbobj;
2260 int dodealloc;
2263 * We can only collapse a DEFAULT/SWAP object with a
2264 * DEFAULT/SWAP object.
2266 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) {
2267 backing_object = NULL;
2268 break;
2271 backing_object = object->backing_object;
2272 if (backing_object == NULL)
2273 break;
2274 if (backing_object->type != OBJT_DEFAULT &&
2275 backing_object->type != OBJT_SWAP) {
2276 backing_object = NULL;
2277 break;
2281 * Hold the backing_object and check for races
2283 vm_object_hold(backing_object);
2284 if (backing_object != object->backing_object ||
2285 (backing_object->type != OBJT_DEFAULT &&
2286 backing_object->type != OBJT_SWAP)) {
2287 vm_object_drop(backing_object);
2288 continue;
2292 * Chain-lock the backing object too because if we
2293 * successfully merge its pages into the top object we
2294 * will collapse backing_object->backing_object as the
2295 * new backing_object. Re-check that it is still our
2296 * backing object.
2298 vm_object_chain_acquire(backing_object, 0);
2299 if (backing_object != object->backing_object) {
2300 vm_object_chain_release(backing_object);
2301 vm_object_drop(backing_object);
2302 continue;
2306 * we check the backing object first, because it is most likely
2307 * not collapsable.
2309 if (backing_object->handle != NULL ||
2310 (backing_object->type != OBJT_DEFAULT &&
2311 backing_object->type != OBJT_SWAP) ||
2312 (backing_object->flags & OBJ_DEAD) ||
2313 object->handle != NULL ||
2314 (object->type != OBJT_DEFAULT &&
2315 object->type != OBJT_SWAP) ||
2316 (object->flags & OBJ_DEAD)) {
2317 break;
2321 * If paging is in progress we can't do a normal collapse.
2323 if (
2324 object->paging_in_progress != 0 ||
2325 backing_object->paging_in_progress != 0
2327 vm_object_qcollapse(object, backing_object);
2328 break;
2332 * We know that we can either collapse the backing object (if
2333 * the parent is the only reference to it) or (perhaps) have
2334 * the parent bypass the object if the parent happens to shadow
2335 * all the resident pages in the entire backing object.
2337 * This is ignoring pager-backed pages such as swap pages.
2338 * vm_object_backing_scan fails the shadowing test in this
2339 * case.
2341 if (backing_object->ref_count == 1) {
2343 * If there is exactly one reference to the backing
2344 * object, we can collapse it into the parent.
2346 KKASSERT(object->backing_object == backing_object);
2347 vm_object_backing_scan(object, backing_object,
2348 OBSC_COLLAPSE_WAIT);
2351 * Move the pager from backing_object to object.
2353 if (backing_object->type == OBJT_SWAP) {
2354 vm_object_pip_add(backing_object, 1);
2357 * scrap the paging_offset junk and do a
2358 * discrete copy. This also removes major
2359 * assumptions about how the swap-pager
2360 * works from where it doesn't belong. The
2361 * new swapper is able to optimize the
2362 * destroy-source case.
2364 vm_object_pip_add(object, 1);
2365 swap_pager_copy(backing_object, object,
2366 OFF_TO_IDX(object->backing_object_offset),
2367 TRUE);
2368 vm_object_pip_wakeup(object);
2369 vm_object_pip_wakeup(backing_object);
2373 * Object now shadows whatever backing_object did.
2374 * Remove object from backing_object's shadow_list.
2376 * Removing object from backing_objects shadow list
2377 * requires releasing object, which we will do below.
2379 KKASSERT(object->backing_object == backing_object);
2380 if (object->flags & OBJ_ONSHADOW) {
2381 LIST_REMOVE(object, shadow_list);
2382 backing_object->shadow_count--;
2383 atomic_add_int(&backing_object->generation, 1);
2384 vm_object_clear_flag(object, OBJ_ONSHADOW);
2388 * backing_object->backing_object moves from within
2389 * backing_object to within object.
2391 * OBJT_VNODE bbobj's should have empty shadow lists.
2393 while ((bbobj = backing_object->backing_object) != NULL) {
2394 if (bbobj->type == OBJT_VNODE)
2395 vm_object_hold_shared(bbobj);
2396 else
2397 vm_object_hold(bbobj);
2398 if (bbobj == backing_object->backing_object)
2399 break;
2400 vm_object_drop(bbobj);
2404 * We are removing backing_object from bbobj's
2405 * shadow list and adding object to bbobj's shadow
2406 * list, so the ref_count on bbobj is unchanged.
2408 if (bbobj) {
2409 if (backing_object->flags & OBJ_ONSHADOW) {
2410 /* not locked exclusively if vnode */
2411 KKASSERT(bbobj->type != OBJT_VNODE);
2412 LIST_REMOVE(backing_object,
2413 shadow_list);
2414 bbobj->shadow_count--;
2415 atomic_add_int(&bbobj->generation, 1);
2416 vm_object_clear_flag(backing_object,
2417 OBJ_ONSHADOW);
2419 backing_object->backing_object = NULL;
2421 object->backing_object = bbobj;
2422 if (bbobj) {
2423 if (bbobj->type != OBJT_VNODE) {
2424 LIST_INSERT_HEAD(&bbobj->shadow_head,
2425 object, shadow_list);
2426 bbobj->shadow_count++;
2427 atomic_add_int(&bbobj->generation, 1);
2428 vm_object_set_flag(object,
2429 OBJ_ONSHADOW);
2433 object->backing_object_offset +=
2434 backing_object->backing_object_offset;
2436 vm_object_drop(bbobj);
2439 * Discard the old backing_object. Nothing should be
2440 * able to ref it, other than a vm_map_split(),
2441 * and vm_map_split() will stall on our chain lock.
2442 * And we control the parent so it shouldn't be
2443 * possible for it to go away either.
2445 * Since the backing object has no pages, no pager
2446 * left, and no object references within it, all
2447 * that is necessary is to dispose of it.
2449 KASSERT(backing_object->ref_count == 1,
2450 ("backing_object %p was somehow "
2451 "re-referenced during collapse!",
2452 backing_object));
2453 KASSERT(RB_EMPTY(&backing_object->rb_memq),
2454 ("backing_object %p somehow has left "
2455 "over pages during collapse!",
2456 backing_object));
2459 * The object can be destroyed.
2461 * XXX just fall through and dodealloc instead
2462 * of forcing destruction?
2464 atomic_add_int(&backing_object->ref_count, -1);
2465 #if defined(DEBUG_LOCKS)
2466 debugvm_object_add(backing_object, "collapse", 1, -1);
2467 #endif
2468 if ((backing_object->flags & OBJ_DEAD) == 0)
2469 vm_object_terminate(backing_object);
2470 object_collapses++;
2471 dodealloc = 0;
2472 } else {
2474 * If we do not entirely shadow the backing object,
2475 * there is nothing we can do so we give up.
2477 if (vm_object_backing_scan(object, backing_object,
2478 OBSC_TEST_ALL_SHADOWED) == 0) {
2479 break;
2483 * bbobj is backing_object->backing_object. Since
2484 * object completely shadows backing_object we can
2485 * bypass it and become backed by bbobj instead.
2487 * The shadow list for vnode backing objects is not
2488 * used and a shared hold is allowed.
2490 while ((bbobj = backing_object->backing_object) != NULL) {
2491 if (bbobj->type == OBJT_VNODE)
2492 vm_object_hold_shared(bbobj);
2493 else
2494 vm_object_hold(bbobj);
2495 if (bbobj == backing_object->backing_object)
2496 break;
2497 vm_object_drop(bbobj);
2501 * Make object shadow bbobj instead of backing_object.
2502 * Remove object from backing_object's shadow list.
2504 * Deallocating backing_object will not remove
2505 * it, since its reference count is at least 2.
2507 * Removing object from backing_object's shadow
2508 * list requires releasing a ref, which we do
2509 * below by setting dodealloc to 1.
2511 KKASSERT(object->backing_object == backing_object);
2512 if (object->flags & OBJ_ONSHADOW) {
2513 LIST_REMOVE(object, shadow_list);
2514 backing_object->shadow_count--;
2515 atomic_add_int(&backing_object->generation, 1);
2516 vm_object_clear_flag(object, OBJ_ONSHADOW);
2520 * Add a ref to bbobj, bbobj now shadows object.
2522 * NOTE: backing_object->backing_object still points
2523 * to bbobj. That relationship remains intact
2524 * because backing_object has > 1 ref, so
2525 * someone else is pointing to it (hence why
2526 * we can't collapse it into object and can
2527 * only handle the all-shadowed bypass case).
2529 if (bbobj) {
2530 if (bbobj->type != OBJT_VNODE) {
2531 vm_object_chain_wait(bbobj, 0);
2532 vm_object_reference_locked(bbobj);
2533 LIST_INSERT_HEAD(&bbobj->shadow_head,
2534 object, shadow_list);
2535 bbobj->shadow_count++;
2536 atomic_add_int(&bbobj->generation, 1);
2537 vm_object_set_flag(object,
2538 OBJ_ONSHADOW);
2539 } else {
2540 vm_object_reference_quick(bbobj);
2542 object->backing_object_offset +=
2543 backing_object->backing_object_offset;
2544 object->backing_object = bbobj;
2545 vm_object_drop(bbobj);
2546 } else {
2547 object->backing_object = NULL;
2551 * Drop the reference count on backing_object. To
2552 * handle ref_count races properly we can't assume
2553 * that the ref_count is still at least 2 so we
2554 * have to actually call vm_object_deallocate()
2555 * (after clearing the chainlock).
2557 object_bypasses++;
2558 dodealloc = 1;
2562 * Ok, we want to loop on the new object->bbobj association,
2563 * possibly collapsing it further. However if dodealloc is
2564 * non-zero we have to deallocate the backing_object which
2565 * itself can potentially undergo a collapse, creating a
2566 * recursion depth issue with the LWKT token subsystem.
2568 * In the case where we must deallocate the backing_object
2569 * it is possible now that the backing_object has a single
2570 * shadow count on some other object (not represented here
2571 * as yet), since it no longer shadows us. Thus when we
2572 * call vm_object_deallocate() it may attempt to collapse
2573 * itself into its remaining parent.
2575 if (dodealloc) {
2576 struct vm_object_dealloc_list *dtmp;
2578 vm_object_chain_release(backing_object);
2579 vm_object_unlock(backing_object);
2580 /* backing_object remains held */
2583 * Auto-deallocation list for caller convenience.
2585 if (dlistp == NULL)
2586 dlistp = &dlist;
2588 dtmp = kmalloc(sizeof(*dtmp), M_TEMP, M_WAITOK);
2589 dtmp->object = backing_object;
2590 dtmp->next = *dlistp;
2591 *dlistp = dtmp;
2592 } else {
2593 vm_object_chain_release(backing_object);
2594 vm_object_drop(backing_object);
2596 /* backing_object = NULL; not needed */
2597 /* loop */
2601 * Clean up any left over backing_object
2603 if (backing_object) {
2604 vm_object_chain_release(backing_object);
2605 vm_object_drop(backing_object);
2609 * Clean up any auto-deallocation list. This is a convenience
2610 * for top-level callers so they don't have to pass &dlist.
2611 * Do not clean up any caller-passed dlistp, the caller will
2612 * do that.
2614 if (dlist)
2615 vm_object_deallocate_list(&dlist);
2620 * vm_object_collapse() may collect additional objects in need of
2621 * deallocation. This routine deallocates these objects. The
2622 * deallocation itself can trigger additional collapses (which the
2623 * deallocate function takes care of). This procedure is used to
2624 * reduce procedural recursion since these vm_object shadow chains
2625 * can become quite long.
2627 void
2628 vm_object_deallocate_list(struct vm_object_dealloc_list **dlistp)
2630 struct vm_object_dealloc_list *dlist;
2632 while ((dlist = *dlistp) != NULL) {
2633 *dlistp = dlist->next;
2634 vm_object_lock(dlist->object);
2635 vm_object_deallocate_locked(dlist->object);
2636 vm_object_drop(dlist->object);
2637 kfree(dlist, M_TEMP);
2642 * Removes all physical pages in the specified object range from the
2643 * object's list of pages.
2645 * No requirements.
2647 static int vm_object_page_remove_callback(vm_page_t p, void *data);
2649 void
2650 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
2651 boolean_t clean_only)
2653 struct rb_vm_page_scan_info info;
2654 int all;
2657 * Degenerate cases and assertions
2659 vm_object_hold(object);
2660 if (object == NULL ||
2661 (object->resident_page_count == 0 && object->swblock_count == 0)) {
2662 vm_object_drop(object);
2663 return;
2665 KASSERT(object->type != OBJT_PHYS,
2666 ("attempt to remove pages from a physical object"));
2669 * Indicate that paging is occuring on the object
2671 vm_object_pip_add(object, 1);
2674 * Figure out the actual removal range and whether we are removing
2675 * the entire contents of the object or not. If removing the entire
2676 * contents, be sure to get all pages, even those that might be
2677 * beyond the end of the object.
2679 info.object = object;
2680 info.start_pindex = start;
2681 if (end == 0)
2682 info.end_pindex = (vm_pindex_t)-1;
2683 else
2684 info.end_pindex = end - 1;
2685 info.limit = clean_only;
2686 info.count = 0;
2687 all = (start == 0 && info.end_pindex >= object->size - 1);
2690 * Loop until we are sure we have gotten them all.
2692 do {
2693 info.error = 0;
2694 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
2695 vm_object_page_remove_callback, &info);
2696 } while (info.error);
2699 * Remove any related swap if throwing away pages, or for
2700 * non-swap objects (the swap is a clean copy in that case).
2702 if (object->type != OBJT_SWAP || clean_only == FALSE) {
2703 if (all)
2704 swap_pager_freespace_all(object);
2705 else
2706 swap_pager_freespace(object, info.start_pindex,
2707 info.end_pindex - info.start_pindex + 1);
2711 * Cleanup
2713 vm_object_pip_wakeup(object);
2714 vm_object_drop(object);
2718 * The caller must hold the object.
2720 * NOTE: User yields are allowed when removing more than one page, but not
2721 * allowed if only removing one page (the path for single page removals
2722 * might hold a spinlock).
2724 static int
2725 vm_object_page_remove_callback(vm_page_t p, void *data)
2727 struct rb_vm_page_scan_info *info = data;
2729 if (info->object != p->object ||
2730 p->pindex < info->start_pindex ||
2731 p->pindex > info->end_pindex) {
2732 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n",
2733 info->object, p);
2734 return(0);
2736 if (vm_page_busy_try(p, TRUE)) {
2737 vm_page_sleep_busy(p, TRUE, "vmopar");
2738 info->error = 1;
2739 return(0);
2741 if (info->object != p->object) {
2742 /* this should never happen */
2743 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n",
2744 info->object, p);
2745 vm_page_wakeup(p);
2746 return(0);
2750 * Wired pages cannot be destroyed, but they can be invalidated
2751 * and we do so if clean_only (limit) is not set.
2753 * WARNING! The page may be wired due to being part of a buffer
2754 * cache buffer, and the buffer might be marked B_CACHE.
2755 * This is fine as part of a truncation but VFSs must be
2756 * sure to fix the buffer up when re-extending the file.
2758 * NOTE! PG_NEED_COMMIT is ignored.
2760 if (p->wire_count != 0) {
2761 vm_page_protect(p, VM_PROT_NONE);
2762 if (info->limit == 0)
2763 p->valid = 0;
2764 vm_page_wakeup(p);
2765 goto done;
2769 * limit is our clean_only flag. If set and the page is dirty or
2770 * requires a commit, do not free it. If set and the page is being
2771 * held by someone, do not free it.
2773 if (info->limit && p->valid) {
2774 vm_page_test_dirty(p);
2775 if ((p->valid & p->dirty) || (p->flags & PG_NEED_COMMIT)) {
2776 vm_page_wakeup(p);
2777 goto done;
2782 * Destroy the page
2784 vm_page_protect(p, VM_PROT_NONE);
2785 vm_page_free(p);
2788 * Must be at end to avoid SMP races, caller holds object token
2790 done:
2791 if ((++info->count & 63) == 0)
2792 lwkt_user_yield();
2794 return(0);
2798 * Coalesces two objects backing up adjoining regions of memory into a
2799 * single object.
2801 * returns TRUE if objects were combined.
2803 * NOTE: Only works at the moment if the second object is NULL -
2804 * if it's not, which object do we lock first?
2806 * Parameters:
2807 * prev_object First object to coalesce
2808 * prev_offset Offset into prev_object
2809 * next_object Second object into coalesce
2810 * next_offset Offset into next_object
2812 * prev_size Size of reference to prev_object
2813 * next_size Size of reference to next_object
2815 * The caller does not need to hold (prev_object) but must have a stable
2816 * pointer to it (typically by holding the vm_map locked).
2818 boolean_t
2819 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex,
2820 vm_size_t prev_size, vm_size_t next_size)
2822 vm_pindex_t next_pindex;
2824 if (prev_object == NULL)
2825 return (TRUE);
2827 vm_object_hold(prev_object);
2829 if (prev_object->type != OBJT_DEFAULT &&
2830 prev_object->type != OBJT_SWAP) {
2831 vm_object_drop(prev_object);
2832 return (FALSE);
2836 * Try to collapse the object first
2838 vm_object_chain_acquire(prev_object, 0);
2839 vm_object_collapse(prev_object, NULL);
2842 * Can't coalesce if: . more than one reference . paged out . shadows
2843 * another object . has a copy elsewhere (any of which mean that the
2844 * pages not mapped to prev_entry may be in use anyway)
2847 if (prev_object->backing_object != NULL) {
2848 vm_object_chain_release(prev_object);
2849 vm_object_drop(prev_object);
2850 return (FALSE);
2853 prev_size >>= PAGE_SHIFT;
2854 next_size >>= PAGE_SHIFT;
2855 next_pindex = prev_pindex + prev_size;
2857 if ((prev_object->ref_count > 1) &&
2858 (prev_object->size != next_pindex)) {
2859 vm_object_chain_release(prev_object);
2860 vm_object_drop(prev_object);
2861 return (FALSE);
2865 * Remove any pages that may still be in the object from a previous
2866 * deallocation.
2868 if (next_pindex < prev_object->size) {
2869 vm_object_page_remove(prev_object,
2870 next_pindex,
2871 next_pindex + next_size, FALSE);
2872 if (prev_object->type == OBJT_SWAP)
2873 swap_pager_freespace(prev_object,
2874 next_pindex, next_size);
2878 * Extend the object if necessary.
2880 if (next_pindex + next_size > prev_object->size)
2881 prev_object->size = next_pindex + next_size;
2883 vm_object_chain_release(prev_object);
2884 vm_object_drop(prev_object);
2885 return (TRUE);
2889 * Make the object writable and flag is being possibly dirty.
2891 * The object might not be held (or might be held but held shared),
2892 * the related vnode is probably not held either. Object and vnode are
2893 * stable by virtue of the vm_page busied by the caller preventing
2894 * destruction.
2896 * If the related mount is flagged MNTK_THR_SYNC we need to call
2897 * vsetobjdirty(). Filesystems using this option usually shortcut
2898 * synchronization by only scanning the syncer list.
2900 void
2901 vm_object_set_writeable_dirty(vm_object_t object)
2903 struct vnode *vp;
2905 /*vm_object_assert_held(object);*/
2907 * Avoid contention in vm fault path by checking the state before
2908 * issuing an atomic op on it.
2910 if ((object->flags & (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) !=
2911 (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) {
2912 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
2914 if (object->type == OBJT_VNODE &&
2915 (vp = (struct vnode *)object->handle) != NULL) {
2916 if ((vp->v_flag & VOBJDIRTY) == 0) {
2917 if (vp->v_mount &&
2918 (vp->v_mount->mnt_kern_flag & MNTK_THR_SYNC)) {
2920 * New style THR_SYNC places vnodes on the
2921 * syncer list more deterministically.
2923 vsetobjdirty(vp);
2924 } else {
2926 * Old style scan would not necessarily place
2927 * a vnode on the syncer list when possibly
2928 * modified via mmap.
2930 vsetflags(vp, VOBJDIRTY);
2936 #include "opt_ddb.h"
2937 #ifdef DDB
2938 #include <sys/cons.h>
2940 #include <ddb/ddb.h>
2942 static int _vm_object_in_map (vm_map_t map, vm_object_t object,
2943 vm_map_entry_t entry);
2944 static int vm_object_in_map (vm_object_t object);
2947 * The caller must hold the object.
2949 static int
2950 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
2952 vm_map_t tmpm;
2953 vm_map_entry_t tmpe;
2954 vm_object_t obj, nobj;
2955 int entcount;
2957 if (map == 0)
2958 return 0;
2959 if (entry == 0) {
2960 tmpe = map->header.next;
2961 entcount = map->nentries;
2962 while (entcount-- && (tmpe != &map->header)) {
2963 if( _vm_object_in_map(map, object, tmpe)) {
2964 return 1;
2966 tmpe = tmpe->next;
2968 return (0);
2970 switch(entry->maptype) {
2971 case VM_MAPTYPE_SUBMAP:
2972 tmpm = entry->object.sub_map;
2973 tmpe = tmpm->header.next;
2974 entcount = tmpm->nentries;
2975 while (entcount-- && tmpe != &tmpm->header) {
2976 if( _vm_object_in_map(tmpm, object, tmpe)) {
2977 return 1;
2979 tmpe = tmpe->next;
2981 break;
2982 case VM_MAPTYPE_NORMAL:
2983 case VM_MAPTYPE_VPAGETABLE:
2984 obj = entry->object.vm_object;
2985 while (obj) {
2986 if (obj == object) {
2987 if (obj != entry->object.vm_object)
2988 vm_object_drop(obj);
2989 return 1;
2991 while ((nobj = obj->backing_object) != NULL) {
2992 vm_object_hold(nobj);
2993 if (nobj == obj->backing_object)
2994 break;
2995 vm_object_drop(nobj);
2997 if (obj != entry->object.vm_object) {
2998 if (nobj)
2999 vm_object_lock_swap();
3000 vm_object_drop(obj);
3002 obj = nobj;
3004 break;
3005 default:
3006 break;
3008 return 0;
3011 static int vm_object_in_map_callback(struct proc *p, void *data);
3013 struct vm_object_in_map_info {
3014 vm_object_t object;
3015 int rv;
3019 * Debugging only
3021 static int
3022 vm_object_in_map(vm_object_t object)
3024 struct vm_object_in_map_info info;
3026 info.rv = 0;
3027 info.object = object;
3029 allproc_scan(vm_object_in_map_callback, &info, 0);
3030 if (info.rv)
3031 return 1;
3032 if( _vm_object_in_map(&kernel_map, object, 0))
3033 return 1;
3034 if( _vm_object_in_map(&pager_map, object, 0))
3035 return 1;
3036 if( _vm_object_in_map(&buffer_map, object, 0))
3037 return 1;
3038 return 0;
3042 * Debugging only
3044 static int
3045 vm_object_in_map_callback(struct proc *p, void *data)
3047 struct vm_object_in_map_info *info = data;
3049 if (p->p_vmspace) {
3050 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) {
3051 info->rv = 1;
3052 return -1;
3055 return (0);
3058 DB_SHOW_COMMAND(vmochk, vm_object_check)
3060 struct vm_object_hash *hash;
3061 vm_object_t object;
3062 int n;
3065 * make sure that internal objs are in a map somewhere
3066 * and none have zero ref counts.
3068 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3069 hash = &vm_object_hash[n];
3070 for (object = TAILQ_FIRST(&hash->list);
3071 object != NULL;
3072 object = TAILQ_NEXT(object, object_list)) {
3073 if (object->type == OBJT_MARKER)
3074 continue;
3075 if (object->handle != NULL ||
3076 (object->type != OBJT_DEFAULT &&
3077 object->type != OBJT_SWAP)) {
3078 continue;
3080 if (object->ref_count == 0) {
3081 db_printf("vmochk: internal obj has "
3082 "zero ref count: %ld\n",
3083 (long)object->size);
3085 if (vm_object_in_map(object))
3086 continue;
3087 db_printf("vmochk: internal obj is not in a map: "
3088 "ref: %d, size: %lu: 0x%lx, "
3089 "backing_object: %p\n",
3090 object->ref_count, (u_long)object->size,
3091 (u_long)object->size,
3092 (void *)object->backing_object);
3098 * Debugging only
3100 DB_SHOW_COMMAND(object, vm_object_print_static)
3102 /* XXX convert args. */
3103 vm_object_t object = (vm_object_t)addr;
3104 boolean_t full = have_addr;
3106 vm_page_t p;
3108 /* XXX count is an (unused) arg. Avoid shadowing it. */
3109 #define count was_count
3111 int count;
3113 if (object == NULL)
3114 return;
3116 db_iprintf(
3117 "Object %p: type=%d, size=0x%lx, res=%ld, ref=%d, flags=0x%x\n",
3118 object, (int)object->type, (u_long)object->size,
3119 object->resident_page_count, object->ref_count, object->flags);
3121 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3123 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3124 object->shadow_count,
3125 object->backing_object ? object->backing_object->ref_count : 0,
3126 object->backing_object, (long)object->backing_object_offset);
3128 if (!full)
3129 return;
3131 db_indent += 2;
3132 count = 0;
3133 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) {
3134 if (count == 0)
3135 db_iprintf("memory:=");
3136 else if (count == 6) {
3137 db_printf("\n");
3138 db_iprintf(" ...");
3139 count = 0;
3140 } else
3141 db_printf(",");
3142 count++;
3144 db_printf("(off=0x%lx,page=0x%lx)",
3145 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
3147 if (count != 0)
3148 db_printf("\n");
3149 db_indent -= 2;
3152 /* XXX. */
3153 #undef count
3156 * XXX need this non-static entry for calling from vm_map_print.
3158 * Debugging only
3160 void
3161 vm_object_print(/* db_expr_t */ long addr,
3162 boolean_t have_addr,
3163 /* db_expr_t */ long count,
3164 char *modif)
3166 vm_object_print_static(addr, have_addr, count, modif);
3170 * Debugging only
3172 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
3174 struct vm_object_hash *hash;
3175 vm_object_t object;
3176 int nl = 0;
3177 int c;
3178 int n;
3180 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3181 hash = &vm_object_hash[n];
3182 for (object = TAILQ_FIRST(&hash->list);
3183 object != NULL;
3184 object = TAILQ_NEXT(object, object_list)) {
3185 vm_pindex_t idx, fidx;
3186 vm_pindex_t osize;
3187 vm_paddr_t pa = -1, padiff;
3188 int rcount;
3189 vm_page_t m;
3191 if (object->type == OBJT_MARKER)
3192 continue;
3193 db_printf("new object: %p\n", (void *)object);
3194 if ( nl > 18) {
3195 c = cngetc();
3196 if (c != ' ')
3197 return;
3198 nl = 0;
3200 nl++;
3201 rcount = 0;
3202 fidx = 0;
3203 osize = object->size;
3204 if (osize > 128)
3205 osize = 128;
3206 for (idx = 0; idx < osize; idx++) {
3207 m = vm_page_lookup(object, idx);
3208 if (m == NULL) {
3209 if (rcount) {
3210 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3211 (long)fidx, rcount, (long)pa);
3212 if ( nl > 18) {
3213 c = cngetc();
3214 if (c != ' ')
3215 return;
3216 nl = 0;
3218 nl++;
3219 rcount = 0;
3221 continue;
3224 if (rcount &&
3225 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
3226 ++rcount;
3227 continue;
3229 if (rcount) {
3230 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
3231 padiff >>= PAGE_SHIFT;
3232 padiff &= PQ_L2_MASK;
3233 if (padiff == 0) {
3234 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
3235 ++rcount;
3236 continue;
3238 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3239 (long)fidx, rcount, (long)pa);
3240 db_printf("pd(%ld)\n", (long)padiff);
3241 if ( nl > 18) {
3242 c = cngetc();
3243 if (c != ' ')
3244 return;
3245 nl = 0;
3247 nl++;
3249 fidx = idx;
3250 pa = VM_PAGE_TO_PHYS(m);
3251 rcount = 1;
3253 if (rcount) {
3254 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3255 (long)fidx, rcount, (long)pa);
3256 if ( nl > 18) {
3257 c = cngetc();
3258 if (c != ' ')
3259 return;
3260 nl = 0;
3262 nl++;
3267 #endif /* DDB */