sys/vm/vm_object.c

   1 /*
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * The Mach Operating System project at Carnegie-Mellon University.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      from: @(#)vm_object.c   8.5 (Berkeley) 3/22/94
  37  *
  38  *
  39  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
  40  * All rights reserved.
  41  *
  42  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
  43  *
  44  * Permission to use, copy, modify and distribute this software and
  45  * its documentation is hereby granted, provided that both the copyright
  46  * notice and this permission notice appear in all copies of the
  47  * software, derivative works or modified versions, and any portions
  48  * thereof, and that both notices appear in supporting documentation.
  49  *
  50  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  51  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
  52  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  53  *
  54  * Carnegie Mellon requests users of this software to return to
  55  *
  56  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  57  *  School of Computer Science
  58  *  Carnegie Mellon University
  59  *  Pittsburgh PA 15213-3890
  60  *
  61  * any improvements or extensions that they make and grant Carnegie the
  62  * rights to redistribute these changes.
  63  *
  64  * $FreeBSD$
  65  */
  66
  67 /*
  68  *      Virtual memory object module.
  69  */
  70
  71 #include <sys/param.h>
  72 #include <sys/systm.h>
  73 #include <sys/lock.h>
  74 #include <sys/mman.h>
  75 #include <sys/mount.h>
  76 #include <sys/kernel.h>
  77 #include <sys/sysctl.h>
  78 #include <sys/mutex.h>
  79 #include <sys/proc.h>           /* for curproc, pageproc */
  80 #include <sys/socket.h>
  81 #include <sys/vnode.h>
  82 #include <sys/vmmeter.h>
  83 #include <sys/sx.h>
  84
  85 #include <vm/vm.h>
  86 #include <vm/vm_param.h>
  87 #include <vm/pmap.h>
  88 #include <vm/vm_map.h>
  89 #include <vm/vm_object.h>
  90 #include <vm/vm_page.h>
  91 #include <vm/vm_pageout.h>
  92 #include <vm/vm_pager.h>
  93 #include <vm/swap_pager.h>
  94 #include <vm/vm_kern.h>
  95 #include <vm/vm_extern.h>
  96 #include <vm/uma.h>
  97
  98 #define EASY_SCAN_FACTOR       8
  99
 100 #define MSYNC_FLUSH_HARDSEQ     0x01
 101 #define MSYNC_FLUSH_SOFTSEQ     0x02
 102
 103 /*
 104  * msync / VM object flushing optimizations
 105  */
 106 static int msync_flush_flags = MSYNC_FLUSH_HARDSEQ | MSYNC_FLUSH_SOFTSEQ;
 107 SYSCTL_INT(_vm, OID_AUTO, msync_flush_flags,
 108         CTLFLAG_RW, &msync_flush_flags, 0, "");
 109
 110 static void     vm_object_qcollapse(vm_object_t object);
 111 static int      vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags);
 112
 113 /*
 114  *      Virtual memory objects maintain the actual data
 115  *      associated with allocated virtual memory.  A given
 116  *      page of memory exists within exactly one object.
 117  *
 118  *      An object is only deallocated when all "references"
 119  *      are given up.  Only one "reference" to a given
 120  *      region of an object should be writeable.
 121  *
 122  *      Associated with each object is a list of all resident
 123  *      memory pages belonging to that object; this list is
 124  *      maintained by the "vm_page" module, and locked by the object's
 125  *      lock.
 126  *
 127  *      Each object also records a "pager" routine which is
 128  *      used to retrieve (and store) pages to the proper backing
 129  *      storage.  In addition, objects may be backed by other
 130  *      objects from which they were virtual-copied.
 131  *
 132  *      The only items within the object structure which are
 133  *      modified after time of creation are:
 134  *              reference count         locked by object's lock
 135  *              pager routine           locked by object's lock
 136  *
 137  */
 138
 139 struct object_q vm_object_list;
 140 struct mtx vm_object_list_mtx;  /* lock for object list and count */
 141 vm_object_t kernel_object;
 142 vm_object_t kmem_object;
 143 static struct vm_object kernel_object_store;
 144 static struct vm_object kmem_object_store;
 145 extern int vm_pageout_page_count;
 146
 147 static long object_collapses;
 148 static long object_bypasses;
 149 static int next_index;
 150 static uma_zone_t obj_zone;
 151 #define VM_OBJECTS_INIT 256
 152
 153 static void vm_object_zinit(void *mem, int size);
 154
 155 #ifdef INVARIANTS
 156 static void vm_object_zdtor(void *mem, int size, void *arg);
 157
 158 static void
 159 vm_object_zdtor(void *mem, int size, void *arg)
 160 {
 161         vm_object_t object;
 162
 163         object = (vm_object_t)mem;
 164         KASSERT(object->paging_in_progress == 0,
 165             ("object %p paging_in_progress = %d",
 166             object, object->paging_in_progress));
 167         KASSERT(object->resident_page_count == 0,
 168             ("object %p resident_page_count = %d",
 169             object, object->resident_page_count));
 170         KASSERT(object->shadow_count == 0,
 171             ("object %p shadow_count = %d",
 172             object, object->shadow_count));
 173 }
 174 #endif
 175
 176 static void
 177 vm_object_zinit(void *mem, int size)
 178 {
 179         vm_object_t object;
 180
 181         object = (vm_object_t)mem;
 182
 183         /* These are true for any object that has been freed */
 184         object->paging_in_progress = 0;
 185         object->resident_page_count = 0;
 186         object->shadow_count = 0;
 187 }
 188
 189 void
 190 _vm_object_allocate(objtype_t type, vm_size_t size, vm_object_t object)
 191 {
 192         static int object_hash_rand;
 193         int exp, incr;
 194
 195         TAILQ_INIT(&object->memq);
 196         TAILQ_INIT(&object->shadow_head);
 197
 198         object->type = type;
 199         object->size = size;
 200         object->ref_count = 1;
 201         object->flags = 0;
 202         if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
 203                 vm_object_set_flag(object, OBJ_ONEMAPPING);
 204         if (size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
 205                 incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
 206         else
 207                 incr = size;
 208         do
 209                 object->pg_color = next_index;
 210         while (!atomic_cmpset_int(&next_index, object->pg_color,
 211                                   (object->pg_color + incr) & PQ_L2_MASK));
 212         object->handle = NULL;
 213         object->backing_object = NULL;
 214         object->backing_object_offset = (vm_ooffset_t) 0;
 215         /*
 216          * Try to generate a number that will spread objects out in the
 217          * hash table.  We 'wipe' new objects across the hash in 128 page
 218          * increments plus 1 more to offset it a little more by the time
 219          * it wraps around.
 220          */
 221         do {
 222                 exp = object_hash_rand;
 223                 object->hash_rand = exp - 129;
 224         } while (!atomic_cmpset_int(&object_hash_rand, exp, object->hash_rand));
 225
 226         object->generation++;           /* atomicity needed? XXX */
 227
 228         mtx_lock(&vm_object_list_mtx);
 229         TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
 230         mtx_unlock(&vm_object_list_mtx);
 231 }
 232
 233 /*
 234  *      vm_object_init:
 235  *
 236  *      Initialize the VM objects module.
 237  */
 238 void
 239 vm_object_init(void)
 240 {
 241         TAILQ_INIT(&vm_object_list);
 242         mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
 243
 244         kernel_object = &kernel_object_store;
 245         _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 246             kernel_object);
 247
 248         kmem_object = &kmem_object_store;
 249         _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 250             kmem_object);
 251         obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
 252 #ifdef INVARIANTS
 253             vm_object_zdtor,
 254 #else
 255             NULL,
 256 #endif
 257             vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 258         uma_prealloc(obj_zone, VM_OBJECTS_INIT);
 259 }
 260
 261 void
 262 vm_object_init2(void)
 263 {
 264 }
 265
 266 void
 267 vm_object_set_flag(vm_object_t object, u_short bits)
 268 {
 269         object->flags |= bits;
 270 }
 271
 272 void
 273 vm_object_clear_flag(vm_object_t object, u_short bits)
 274 {
 275         GIANT_REQUIRED;
 276         object->flags &= ~bits;
 277 }
 278
 279 void
 280 vm_object_pip_add(vm_object_t object, short i)
 281 {
 282         GIANT_REQUIRED;
 283         object->paging_in_progress += i;
 284 }
 285
 286 void
 287 vm_object_pip_subtract(vm_object_t object, short i)
 288 {
 289         GIANT_REQUIRED;
 290         object->paging_in_progress -= i;
 291 }
 292
 293 void
 294 vm_object_pip_wakeup(vm_object_t object)
 295 {
 296         GIANT_REQUIRED;
 297         object->paging_in_progress--;
 298         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
 299                 vm_object_clear_flag(object, OBJ_PIPWNT);
 300                 wakeup(object);
 301         }
 302 }
 303
 304 void
 305 vm_object_pip_wakeupn(vm_object_t object, short i)
 306 {
 307         GIANT_REQUIRED;
 308         if (i)
 309                 object->paging_in_progress -= i;
 310         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
 311                 vm_object_clear_flag(object, OBJ_PIPWNT);
 312                 wakeup(object);
 313         }
 314 }
 315
 316 void
 317 vm_object_pip_sleep(vm_object_t object, char *waitid)
 318 {
 319         GIANT_REQUIRED;
 320         if (object->paging_in_progress) {
 321                 int s = splvm();
 322                 if (object->paging_in_progress) {
 323                         vm_object_set_flag(object, OBJ_PIPWNT);
 324                         tsleep(object, PVM, waitid, 0);
 325                 }
 326                 splx(s);
 327         }
 328 }
 329
 330 void
 331 vm_object_pip_wait(vm_object_t object, char *waitid)
 332 {
 333         GIANT_REQUIRED;
 334         while (object->paging_in_progress)
 335                 vm_object_pip_sleep(object, waitid);
 336 }
 337
 338 /*
 339  *      vm_object_allocate:
 340  *
 341  *      Returns a new object with the given size.
 342  */
 343 vm_object_t
 344 vm_object_allocate(objtype_t type, vm_size_t size)
 345 {
 346         vm_object_t result;
 347
 348         result = (vm_object_t) uma_zalloc(obj_zone, M_WAITOK);
 349         _vm_object_allocate(type, size, result);
 350
 351         return (result);
 352 }
 353
 354
 355 /*
 356  *      vm_object_reference:
 357  *
 358  *      Gets another reference to the given object.
 359  */
 360 void
 361 vm_object_reference(vm_object_t object)
 362 {
 363         if (object == NULL)
 364                 return;
 365
 366         mtx_lock(&Giant);
 367 #if 0
 368         /* object can be re-referenced during final cleaning */
 369         KASSERT(!(object->flags & OBJ_DEAD),
 370             ("vm_object_reference: attempting to reference dead obj"));
 371 #endif
 372
 373         object->ref_count++;
 374         if (object->type == OBJT_VNODE) {
 375                 while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curthread)) {
 376                         printf("vm_object_reference: delay in getting object\n");
 377                 }
 378         }
 379         mtx_unlock(&Giant);
 380 }
 381
 382 /*
 383  * handle deallocating a object of type OBJT_VNODE
 384  */
 385 void
 386 vm_object_vndeallocate(vm_object_t object)
 387 {
 388         struct vnode *vp = (struct vnode *) object->handle;
 389
 390         GIANT_REQUIRED;
 391         KASSERT(object->type == OBJT_VNODE,
 392             ("vm_object_vndeallocate: not a vnode object"));
 393         KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
 394 #ifdef INVARIANTS
 395         if (object->ref_count == 0) {
 396                 vprint("vm_object_vndeallocate", vp);
 397                 panic("vm_object_vndeallocate: bad object reference count");
 398         }
 399 #endif
 400
 401         object->ref_count--;
 402         if (object->ref_count == 0) {
 403                 vp->v_flag &= ~VTEXT;
 404 #ifdef ENABLE_VFS_IOOPT
 405                 vm_object_clear_flag(object, OBJ_OPT);
 406 #endif
 407         }
 408         /*
 409          * vrele may need a vop lock
 410          */
 411         vrele(vp);
 412 }
 413
 414 /*
 415  *      vm_object_deallocate:
 416  *
 417  *      Release a reference to the specified object,
 418  *      gained either through a vm_object_allocate
 419  *      or a vm_object_reference call.  When all references
 420  *      are gone, storage associated with this object
 421  *      may be relinquished.
 422  *
 423  *      No object may be locked.
 424  */
 425 void
 426 vm_object_deallocate(vm_object_t object)
 427 {
 428         vm_object_t temp;
 429
 430         mtx_lock(&Giant);
 431         while (object != NULL) {
 432
 433                 if (object->type == OBJT_VNODE) {
 434                         vm_object_vndeallocate(object);
 435                         mtx_unlock(&Giant);
 436                         return;
 437                 }
 438
 439                 KASSERT(object->ref_count != 0,
 440                         ("vm_object_deallocate: object deallocated too many times: %d", object->type));
 441
 442                 /*
 443                  * If the reference count goes to 0 we start calling
 444                  * vm_object_terminate() on the object chain.
 445                  * A ref count of 1 may be a special case depending on the
 446                  * shadow count being 0 or 1.
 447                  */
 448                 object->ref_count--;
 449                 if (object->ref_count > 1) {
 450                         mtx_unlock(&Giant);
 451                         return;
 452                 } else if (object->ref_count == 1) {
 453                         if (object->shadow_count == 0) {
 454                                 vm_object_set_flag(object, OBJ_ONEMAPPING);
 455                         } else if ((object->shadow_count == 1) &&
 456                             (object->handle == NULL) &&
 457                             (object->type == OBJT_DEFAULT ||
 458                              object->type == OBJT_SWAP)) {
 459                                 vm_object_t robject;
 460
 461                                 robject = TAILQ_FIRST(&object->shadow_head);
 462                                 KASSERT(robject != NULL,
 463                                     ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
 464                                          object->ref_count,
 465                                          object->shadow_count));
 466                                 if ((robject->handle == NULL) &&
 467                                     (robject->type == OBJT_DEFAULT ||
 468                                      robject->type == OBJT_SWAP)) {
 469
 470                                         robject->ref_count++;
 471
 472                                         while (
 473                                                 robject->paging_in_progress ||
 474                                                 object->paging_in_progress
 475                                         ) {
 476                                                 vm_object_pip_sleep(robject, "objde1");
 477                                                 vm_object_pip_sleep(object, "objde2");
 478                                         }
 479
 480                                         if (robject->ref_count == 1) {
 481                                                 robject->ref_count--;
 482                                                 object = robject;
 483                                                 goto doterm;
 484                                         }
 485
 486                                         object = robject;
 487                                         vm_object_collapse(object);
 488                                         continue;
 489                                 }
 490                         }
 491                         mtx_unlock(&Giant);
 492                         return;
 493                 }
 494 doterm:
 495                 temp = object->backing_object;
 496                 if (temp) {
 497                         TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
 498                         temp->shadow_count--;
 499 #ifdef ENABLE_VFS_IOOPT
 500                         if (temp->ref_count == 0)
 501                                 vm_object_clear_flag(temp, OBJ_OPT);
 502 #endif
 503                         temp->generation++;
 504                         object->backing_object = NULL;
 505                 }
 506                 /*
 507                  * Don't double-terminate, we could be in a termination
 508                  * recursion due to the terminate having to sync data
 509                  * to disk.
 510                  */
 511                 if ((object->flags & OBJ_DEAD) == 0)
 512                         vm_object_terminate(object);
 513                 object = temp;
 514         }
 515         mtx_unlock(&Giant);
 516 }
 517
 518 /*
 519  *      vm_object_terminate actually destroys the specified object, freeing
 520  *      up all previously used resources.
 521  *
 522  *      The object must be locked.
 523  *      This routine may block.
 524  */
 525 void
 526 vm_object_terminate(vm_object_t object)
 527 {
 528         vm_page_t p;
 529         int s;
 530
 531         GIANT_REQUIRED;
 532
 533         /*
 534          * Make sure no one uses us.
 535          */
 536         vm_object_set_flag(object, OBJ_DEAD);
 537
 538         /*
 539          * wait for the pageout daemon to be done with the object
 540          */
 541         vm_object_pip_wait(object, "objtrm");
 542
 543         KASSERT(!object->paging_in_progress,
 544                 ("vm_object_terminate: pageout in progress"));
 545
 546         /*
 547          * Clean and free the pages, as appropriate. All references to the
 548          * object are gone, so we don't need to lock it.
 549          */
 550         if (object->type == OBJT_VNODE) {
 551                 struct vnode *vp;
 552
 553 #ifdef ENABLE_VFS_IOOPT
 554                 /*
 555                  * Freeze optimized copies.
 556                  */
 557                 vm_freeze_copyopts(object, 0, object->size);
 558 #endif
 559                 /*
 560                  * Clean pages and flush buffers.
 561                  */
 562                 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
 563
 564                 vp = (struct vnode *) object->handle;
 565                 vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
 566         }
 567
 568         KASSERT(object->ref_count == 0,
 569                 ("vm_object_terminate: object with references, ref_count=%d",
 570                 object->ref_count));
 571
 572         /*
 573          * Now free any remaining pages. For internal objects, this also
 574          * removes them from paging queues. Don't free wired pages, just
 575          * remove them from the object.
 576          */
 577         s = splvm();
 578         while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
 579                 KASSERT(!p->busy && (p->flags & PG_BUSY) == 0,
 580                         ("vm_object_terminate: freeing busy page %p "
 581                         "p->busy = %d, p->flags %x\n", p, p->busy, p->flags));
 582                 if (p->wire_count == 0) {
 583                         vm_page_busy(p);
 584                         vm_page_free(p);
 585                         cnt.v_pfree++;
 586                 } else {
 587                         vm_page_busy(p);
 588                         vm_page_remove(p);
 589                 }
 590         }
 591         splx(s);
 592
 593         /*
 594          * Let the pager know object is dead.
 595          */
 596         vm_pager_deallocate(object);
 597
 598         /*
 599          * Remove the object from the global object list.
 600          */
 601         mtx_lock(&vm_object_list_mtx);
 602         TAILQ_REMOVE(&vm_object_list, object, object_list);
 603         mtx_unlock(&vm_object_list_mtx);
 604
 605         wakeup(object);
 606
 607         /*
 608          * Free the space for the object.
 609          */
 610         uma_zfree(obj_zone, object);
 611 }
 612
 613 /*
 614  *      vm_object_page_clean
 615  *
 616  *      Clean all dirty pages in the specified range of object.  Leaves page
 617  *      on whatever queue it is currently on.   If NOSYNC is set then do not
 618  *      write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
 619  *      leaving the object dirty.
 620  *
 621  *      Odd semantics: if start == end, we clean everything.
 622  *
 623  *      The object must be locked.
 624  */
 625 void
 626 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end, int flags)
 627 {
 628         vm_page_t p, np;
 629         vm_offset_t tstart, tend;
 630         vm_pindex_t pi;
 631         struct vnode *vp;
 632         int clearobjflags;
 633         int pagerflags;
 634         int curgeneration;
 635
 636         GIANT_REQUIRED;
 637
 638         if (object->type != OBJT_VNODE ||
 639                 (object->flags & OBJ_MIGHTBEDIRTY) == 0)
 640                 return;
 641
 642         pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : 0;
 643         pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
 644
 645         vp = object->handle;
 646
 647         vm_object_set_flag(object, OBJ_CLEANING);
 648
 649         tstart = start;
 650         if (end == 0) {
 651                 tend = object->size;
 652         } else {
 653                 tend = end;
 654         }
 655
 656         /*
 657          * If the caller is smart and only msync()s a range he knows is
 658          * dirty, we may be able to avoid an object scan.  This results in
 659          * a phenominal improvement in performance.  We cannot do this
 660          * as a matter of course because the object may be huge - e.g.
 661          * the size might be in the gigabytes or terrabytes.
 662          */
 663         if (msync_flush_flags & MSYNC_FLUSH_HARDSEQ) {
 664                 vm_offset_t tscan;
 665                 int scanlimit;
 666                 int scanreset;
 667
 668                 scanreset = object->resident_page_count / EASY_SCAN_FACTOR;
 669                 if (scanreset < 16)
 670                         scanreset = 16;
 671
 672                 scanlimit = scanreset;
 673                 tscan = tstart;
 674                 while (tscan < tend) {
 675                         curgeneration = object->generation;
 676                         p = vm_page_lookup(object, tscan);
 677                         if (p == NULL || p->valid == 0 ||
 678                             (p->queue - p->pc) == PQ_CACHE) {
 679                                 if (--scanlimit == 0)
 680                                         break;
 681                                 ++tscan;
 682                                 continue;
 683                         }
 684                         vm_page_test_dirty(p);
 685                         if ((p->dirty & p->valid) == 0) {
 686                                 if (--scanlimit == 0)
 687                                         break;
 688                                 ++tscan;
 689                                 continue;
 690                         }
 691                         /*
 692                          * If we have been asked to skip nosync pages and
 693                          * this is a nosync page, we can't continue.
 694                          */
 695                         if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
 696                                 if (--scanlimit == 0)
 697                                         break;
 698                                 ++tscan;
 699                                 continue;
 700                         }
 701                         scanlimit = scanreset;
 702
 703                         /*
 704                          * This returns 0 if it was unable to busy the first
 705                          * page (i.e. had to sleep).
 706                          */
 707                         tscan += vm_object_page_collect_flush(object, p, curgeneration, pagerflags);
 708                 }
 709
 710                 /*
 711                  * If everything was dirty and we flushed it successfully,
 712                  * and the requested range is not the entire object, we
 713                  * don't have to mess with CLEANCHK or MIGHTBEDIRTY and can
 714                  * return immediately.
 715                  */
 716                 if (tscan >= tend && (tstart || tend < object->size)) {
 717                         vm_object_clear_flag(object, OBJ_CLEANING);
 718                         return;
 719                 }
 720         }
 721
 722         /*
 723          * Generally set CLEANCHK interlock and make the page read-only so
 724          * we can then clear the object flags.
 725          *
 726          * However, if this is a nosync mmap then the object is likely to
 727          * stay dirty so do not mess with the page and do not clear the
 728          * object flags.
 729          */
 730         clearobjflags = 1;
 731
 732         TAILQ_FOREACH(p, &object->memq, listq) {
 733                 vm_page_flag_set(p, PG_CLEANCHK);
 734                 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC))
 735                         clearobjflags = 0;
 736                 else
 737                         vm_page_protect(p, VM_PROT_READ);
 738         }
 739
 740         if (clearobjflags && (tstart == 0) && (tend == object->size)) {
 741                 struct vnode *vp;
 742
 743                 vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
 744                 if (object->type == OBJT_VNODE &&
 745                     (vp = (struct vnode *)object->handle) != NULL) {
 746                         if (vp->v_flag & VOBJDIRTY) {
 747                                 mtx_lock(&vp->v_interlock);
 748                                 vp->v_flag &= ~VOBJDIRTY;
 749                                 mtx_unlock(&vp->v_interlock);
 750                         }
 751                 }
 752         }
 753
 754 rescan:
 755         curgeneration = object->generation;
 756
 757         for (p = TAILQ_FIRST(&object->memq); p; p = np) {
 758                 int n;
 759
 760                 np = TAILQ_NEXT(p, listq);
 761
 762 again:
 763                 pi = p->pindex;
 764                 if (((p->flags & PG_CLEANCHK) == 0) ||
 765                         (pi < tstart) || (pi >= tend) ||
 766                         (p->valid == 0) ||
 767                         ((p->queue - p->pc) == PQ_CACHE)) {
 768                         vm_page_flag_clear(p, PG_CLEANCHK);
 769                         continue;
 770                 }
 771
 772                 vm_page_test_dirty(p);
 773                 if ((p->dirty & p->valid) == 0) {
 774                         vm_page_flag_clear(p, PG_CLEANCHK);
 775                         continue;
 776                 }
 777
 778                 /*
 779                  * If we have been asked to skip nosync pages and this is a
 780                  * nosync page, skip it.  Note that the object flags were
 781                  * not cleared in this case so we do not have to set them.
 782                  */
 783                 if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
 784                         vm_page_flag_clear(p, PG_CLEANCHK);
 785                         continue;
 786                 }
 787
 788                 n = vm_object_page_collect_flush(object, p,
 789                         curgeneration, pagerflags);
 790                 if (n == 0)
 791                         goto rescan;
 792
 793                 if (object->generation != curgeneration)
 794                         goto rescan;
 795
 796                 /*
 797                  * Try to optimize the next page.  If we can't we pick up
 798                  * our (random) scan where we left off.
 799                  */
 800                 if (msync_flush_flags & MSYNC_FLUSH_SOFTSEQ) {
 801                         if ((p = vm_page_lookup(object, pi + n)) != NULL)
 802                                 goto again;
 803                 }
 804         }
 805
 806 #if 0
 807         VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);
 808 #endif
 809
 810         vm_object_clear_flag(object, OBJ_CLEANING);
 811         return;
 812 }
 813
 814 static int
 815 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags)
 816 {
 817         int runlen;
 818         int s;
 819         int maxf;
 820         int chkb;
 821         int maxb;
 822         int i;
 823         vm_pindex_t pi;
 824         vm_page_t maf[vm_pageout_page_count];
 825         vm_page_t mab[vm_pageout_page_count];
 826         vm_page_t ma[vm_pageout_page_count];
 827
 828         s = splvm();
 829         pi = p->pindex;
 830         while (vm_page_sleep_busy(p, TRUE, "vpcwai")) {
 831                 if (object->generation != curgeneration) {
 832                         splx(s);
 833                         return(0);
 834                 }
 835         }
 836
 837         maxf = 0;
 838         for(i = 1; i < vm_pageout_page_count; i++) {
 839                 vm_page_t tp;
 840
 841                 if ((tp = vm_page_lookup(object, pi + i)) != NULL) {
 842                         if ((tp->flags & PG_BUSY) ||
 843                                 (tp->flags & PG_CLEANCHK) == 0 ||
 844                                 (tp->busy != 0))
 845                                 break;
 846                         if((tp->queue - tp->pc) == PQ_CACHE) {
 847                                 vm_page_flag_clear(tp, PG_CLEANCHK);
 848                                 break;
 849                         }
 850                         vm_page_test_dirty(tp);
 851                         if ((tp->dirty & tp->valid) == 0) {
 852                                 vm_page_flag_clear(tp, PG_CLEANCHK);
 853                                 break;
 854                         }
 855                         maf[ i - 1 ] = tp;
 856                         maxf++;
 857                         continue;
 858                 }
 859                 break;
 860         }
 861
 862         maxb = 0;
 863         chkb = vm_pageout_page_count -  maxf;
 864         if (chkb) {
 865                 for(i = 1; i < chkb;i++) {
 866                         vm_page_t tp;
 867
 868                         if ((tp = vm_page_lookup(object, pi - i)) != NULL) {
 869                                 if ((tp->flags & PG_BUSY) ||
 870                                         (tp->flags & PG_CLEANCHK) == 0 ||
 871                                         (tp->busy != 0))
 872                                         break;
 873                                 if ((tp->queue - tp->pc) == PQ_CACHE) {
 874                                         vm_page_flag_clear(tp, PG_CLEANCHK);
 875                                         break;
 876                                 }
 877                                 vm_page_test_dirty(tp);
 878                                 if ((tp->dirty & tp->valid) == 0) {
 879                                         vm_page_flag_clear(tp, PG_CLEANCHK);
 880                                         break;
 881                                 }
 882                                 mab[ i - 1 ] = tp;
 883                                 maxb++;
 884                                 continue;
 885                         }
 886                         break;
 887                 }
 888         }
 889
 890         for(i = 0; i < maxb; i++) {
 891                 int index = (maxb - i) - 1;
 892                 ma[index] = mab[i];
 893                 vm_page_flag_clear(ma[index], PG_CLEANCHK);
 894         }
 895         vm_page_flag_clear(p, PG_CLEANCHK);
 896         ma[maxb] = p;
 897         for(i = 0; i < maxf; i++) {
 898                 int index = (maxb + i) + 1;
 899                 ma[index] = maf[i];
 900                 vm_page_flag_clear(ma[index], PG_CLEANCHK);
 901         }
 902         runlen = maxb + maxf + 1;
 903
 904         splx(s);
 905         vm_pageout_flush(ma, runlen, pagerflags);
 906         for (i = 0; i < runlen; i++) {
 907                 if (ma[i]->valid & ma[i]->dirty) {
 908                         vm_page_protect(ma[i], VM_PROT_READ);
 909                         vm_page_flag_set(ma[i], PG_CLEANCHK);
 910
 911                         /*
 912                          * maxf will end up being the actual number of pages
 913                          * we wrote out contiguously, non-inclusive of the
 914                          * first page.  We do not count look-behind pages.
 915                          */
 916                         if (i >= maxb + 1 && (maxf > i - maxb - 1))
 917                                 maxf = i - maxb - 1;
 918                 }
 919         }
 920         return(maxf + 1);
 921 }
 922
 923 /*
 924  * Same as vm_object_pmap_copy, except range checking really
 925  * works, and is meant for small sections of an object.
 926  *
 927  * This code protects resident pages by making them read-only
 928  * and is typically called on a fork or split when a page
 929  * is converted to copy-on-write.
 930  *
 931  * NOTE: If the page is already at VM_PROT_NONE, calling
 932  * vm_page_protect will have no effect.
 933  */
 934 void
 935 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 936 {
 937         vm_pindex_t idx;
 938         vm_page_t p;
 939
 940         GIANT_REQUIRED;
 941
 942         if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
 943                 return;
 944
 945         for (idx = start; idx < end; idx++) {
 946                 p = vm_page_lookup(object, idx);
 947                 if (p == NULL)
 948                         continue;
 949                 vm_page_protect(p, VM_PROT_READ);
 950         }
 951 }
 952
 953 /*
 954  *      vm_object_pmap_remove:
 955  *
 956  *      Removes all physical pages in the specified
 957  *      object range from all physical maps.
 958  *
 959  *      The object must *not* be locked.
 960  */
 961 void
 962 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 963 {
 964         vm_page_t p;
 965
 966         GIANT_REQUIRED;
 967         if (object == NULL)
 968                 return;
 969         TAILQ_FOREACH(p, &object->memq, listq) {
 970                 if (p->pindex >= start && p->pindex < end)
 971                         vm_page_protect(p, VM_PROT_NONE);
 972         }
 973         if ((start == 0) && (object->size == end))
 974                 vm_object_clear_flag(object, OBJ_WRITEABLE);
 975 }
 976
 977 /*
 978  *      vm_object_madvise:
 979  *
 980  *      Implements the madvise function at the object/page level.
 981  *
 982  *      MADV_WILLNEED   (any object)
 983  *
 984  *          Activate the specified pages if they are resident.
 985  *
 986  *      MADV_DONTNEED   (any object)
 987  *
 988  *          Deactivate the specified pages if they are resident.
 989  *
 990  *      MADV_FREE       (OBJT_DEFAULT/OBJT_SWAP objects,
 991  *                       OBJ_ONEMAPPING only)
 992  *
 993  *          Deactivate and clean the specified pages if they are
 994  *          resident.  This permits the process to reuse the pages
 995  *          without faulting or the kernel to reclaim the pages
 996  *          without I/O.
 997  */
 998 void
 999 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise)
1000 {
1001         vm_pindex_t end, tpindex;
1002         vm_object_t tobject;
1003         vm_page_t m;
1004
1005         if (object == NULL)
1006                 return;
1007
1008         mtx_lock(&Giant);
1009
1010         end = pindex + count;
1011
1012         /*
1013          * Locate and adjust resident pages
1014          */
1015         for (; pindex < end; pindex += 1) {
1016 relookup:
1017                 tobject = object;
1018                 tpindex = pindex;
1019 shadowlookup:
1020                 /*
1021                  * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1022                  * and those pages must be OBJ_ONEMAPPING.
1023                  */
1024                 if (advise == MADV_FREE) {
1025                         if ((tobject->type != OBJT_DEFAULT &&
1026                              tobject->type != OBJT_SWAP) ||
1027                             (tobject->flags & OBJ_ONEMAPPING) == 0) {
1028                                 continue;
1029                         }
1030                 }
1031
1032                 m = vm_page_lookup(tobject, tpindex);
1033
1034                 if (m == NULL) {
1035                         /*
1036                          * There may be swap even if there is no backing page
1037                          */
1038                         if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1039                                 swap_pager_freespace(tobject, tpindex, 1);
1040
1041                         /*
1042                          * next object
1043                          */
1044                         tobject = tobject->backing_object;
1045                         if (tobject == NULL)
1046                                 continue;
1047                         tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1048                         goto shadowlookup;
1049                 }
1050
1051                 /*
1052                  * If the page is busy or not in a normal active state,
1053                  * we skip it.  If the page is not managed there are no
1054                  * page queues to mess with.  Things can break if we mess
1055                  * with pages in any of the below states.
1056                  */
1057                 if (
1058                     m->hold_count ||
1059                     m->wire_count ||
1060                     (m->flags & PG_UNMANAGED) ||
1061                     m->valid != VM_PAGE_BITS_ALL
1062                 ) {
1063                         continue;
1064                 }
1065
1066                 if (vm_page_sleep_busy(m, TRUE, "madvpo"))
1067                         goto relookup;
1068
1069                 if (advise == MADV_WILLNEED) {
1070                         vm_page_activate(m);
1071                 } else if (advise == MADV_DONTNEED) {
1072                         vm_page_dontneed(m);
1073                 } else if (advise == MADV_FREE) {
1074                         /*
1075                          * Mark the page clean.  This will allow the page
1076                          * to be freed up by the system.  However, such pages
1077                          * are often reused quickly by malloc()/free()
1078                          * so we do not do anything that would cause
1079                          * a page fault if we can help it.
1080                          *
1081                          * Specifically, we do not try to actually free
1082                          * the page now nor do we try to put it in the
1083                          * cache (which would cause a page fault on reuse).
1084                          *
1085                          * But we do make the page is freeable as we
1086                          * can without actually taking the step of unmapping
1087                          * it.
1088                          */
1089                         pmap_clear_modify(m);
1090                         m->dirty = 0;
1091                         m->act_count = 0;
1092                         vm_page_dontneed(m);
1093                         if (tobject->type == OBJT_SWAP)
1094                                 swap_pager_freespace(tobject, tpindex, 1);
1095                 }
1096         }
1097         mtx_unlock(&Giant);
1098 }
1099
1100 /*
1101  *      vm_object_shadow:
1102  *
1103  *      Create a new object which is backed by the
1104  *      specified existing object range.  The source
1105  *      object reference is deallocated.
1106  *
1107  *      The new object and offset into that object
1108  *      are returned in the source parameters.
1109  */
1110 void
1111 vm_object_shadow(
1112         vm_object_t *object,    /* IN/OUT */
1113         vm_ooffset_t *offset,   /* IN/OUT */
1114         vm_size_t length)
1115 {
1116         vm_object_t source;
1117         vm_object_t result;
1118
1119         GIANT_REQUIRED;
1120         source = *object;
1121
1122         /*
1123          * Don't create the new object if the old object isn't shared.
1124          */
1125         if (source != NULL &&
1126             source->ref_count == 1 &&
1127             source->handle == NULL &&
1128             (source->type == OBJT_DEFAULT ||
1129              source->type == OBJT_SWAP))
1130                 return;
1131
1132         /*
1133          * Allocate a new object with the given length
1134          */
1135         result = vm_object_allocate(OBJT_DEFAULT, length);
1136         KASSERT(result != NULL, ("vm_object_shadow: no object for shadowing"));
1137
1138         /*
1139          * The new object shadows the source object, adding a reference to it.
1140          * Our caller changes his reference to point to the new object,
1141          * removing a reference to the source object.  Net result: no change
1142          * of reference count.
1143          *
1144          * Try to optimize the result object's page color when shadowing
1145          * in order to maintain page coloring consistency in the combined
1146          * shadowed object.
1147          */
1148         result->backing_object = source;
1149         if (source) {
1150                 TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
1151                 source->shadow_count++;
1152                 source->generation++;
1153                 if (length < source->size)
1154                         length = source->size;
1155                 if (length > PQ_L2_SIZE / 3 + PQ_PRIME1 ||
1156                     source->generation > 1)
1157                         length = PQ_L2_SIZE / 3 + PQ_PRIME1;
1158                 result->pg_color = (source->pg_color +
1159                     length * source->generation) & PQ_L2_MASK;
1160                 next_index = (result->pg_color + PQ_L2_SIZE / 3 + PQ_PRIME1) &
1161                     PQ_L2_MASK;
1162         }
1163
1164         /*
1165          * Store the offset into the source object, and fix up the offset into
1166          * the new object.
1167          */
1168         result->backing_object_offset = *offset;
1169
1170         /*
1171          * Return the new things
1172          */
1173         *offset = 0;
1174         *object = result;
1175 }
1176
1177 #define OBSC_TEST_ALL_SHADOWED  0x0001
1178 #define OBSC_COLLAPSE_NOWAIT    0x0002
1179 #define OBSC_COLLAPSE_WAIT      0x0004
1180
1181 static __inline int
1182 vm_object_backing_scan(vm_object_t object, int op)
1183 {
1184         int s;
1185         int r = 1;
1186         vm_page_t p;
1187         vm_object_t backing_object;
1188         vm_pindex_t backing_offset_index;
1189
1190         s = splvm();
1191         GIANT_REQUIRED;
1192
1193         backing_object = object->backing_object;
1194         backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1195
1196         /*
1197          * Initial conditions
1198          */
1199         if (op & OBSC_TEST_ALL_SHADOWED) {
1200                 /*
1201                  * We do not want to have to test for the existence of
1202                  * swap pages in the backing object.  XXX but with the
1203                  * new swapper this would be pretty easy to do.
1204                  *
1205                  * XXX what about anonymous MAP_SHARED memory that hasn't
1206                  * been ZFOD faulted yet?  If we do not test for this, the
1207                  * shadow test may succeed! XXX
1208                  */
1209                 if (backing_object->type != OBJT_DEFAULT) {
1210                         splx(s);
1211                         return (0);
1212                 }
1213         }
1214         if (op & OBSC_COLLAPSE_WAIT) {
1215                 vm_object_set_flag(backing_object, OBJ_DEAD);
1216         }
1217
1218         /*
1219          * Our scan
1220          */
1221         p = TAILQ_FIRST(&backing_object->memq);
1222         while (p) {
1223                 vm_page_t next = TAILQ_NEXT(p, listq);
1224                 vm_pindex_t new_pindex = p->pindex - backing_offset_index;
1225
1226                 if (op & OBSC_TEST_ALL_SHADOWED) {
1227                         vm_page_t pp;
1228
1229                         /*
1230                          * Ignore pages outside the parent object's range
1231                          * and outside the parent object's mapping of the
1232                          * backing object.
1233                          *
1234                          * note that we do not busy the backing object's
1235                          * page.
1236                          */
1237                         if (
1238                             p->pindex < backing_offset_index ||
1239                             new_pindex >= object->size
1240                         ) {
1241                                 p = next;
1242                                 continue;
1243                         }
1244
1245                         /*
1246                          * See if the parent has the page or if the parent's
1247                          * object pager has the page.  If the parent has the
1248                          * page but the page is not valid, the parent's
1249                          * object pager must have the page.
1250                          *
1251                          * If this fails, the parent does not completely shadow
1252                          * the object and we might as well give up now.
1253                          */
1254
1255                         pp = vm_page_lookup(object, new_pindex);
1256                         if (
1257                             (pp == NULL || pp->valid == 0) &&
1258                             !vm_pager_has_page(object, new_pindex, NULL, NULL)
1259                         ) {
1260                                 r = 0;
1261                                 break;
1262                         }
1263                 }
1264
1265                 /*
1266                  * Check for busy page
1267                  */
1268                 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1269                         vm_page_t pp;
1270
1271                         if (op & OBSC_COLLAPSE_NOWAIT) {
1272                                 if (
1273                                     (p->flags & PG_BUSY) ||
1274                                     !p->valid ||
1275                                     p->hold_count ||
1276                                     p->wire_count ||
1277                                     p->busy
1278                                 ) {
1279                                         p = next;
1280                                         continue;
1281                                 }
1282                         } else if (op & OBSC_COLLAPSE_WAIT) {
1283                                 if (vm_page_sleep_busy(p, TRUE, "vmocol")) {
1284                                         /*
1285                                          * If we slept, anything could have
1286                                          * happened.  Since the object is
1287                                          * marked dead, the backing offset
1288                                          * should not have changed so we
1289                                          * just restart our scan.
1290                                          */
1291                                         p = TAILQ_FIRST(&backing_object->memq);
1292                                         continue;
1293                                 }
1294                         }
1295
1296                         /*
1297                          * Busy the page
1298                          */
1299                         vm_page_busy(p);
1300
1301                         KASSERT(
1302                             p->object == backing_object,
1303                             ("vm_object_qcollapse(): object mismatch")
1304                         );
1305
1306                         /*
1307                          * Destroy any associated swap
1308                          */
1309                         if (backing_object->type == OBJT_SWAP) {
1310                                 swap_pager_freespace(
1311                                     backing_object,
1312                                     p->pindex,
1313                                     1
1314                                 );
1315                         }
1316
1317                         if (
1318                             p->pindex < backing_offset_index ||
1319                             new_pindex >= object->size
1320                         ) {
1321                                 /*
1322                                  * Page is out of the parent object's range, we
1323                                  * can simply destroy it.
1324                                  */
1325                                 vm_page_protect(p, VM_PROT_NONE);
1326                                 vm_page_free(p);
1327                                 p = next;
1328                                 continue;
1329                         }
1330
1331                         pp = vm_page_lookup(object, new_pindex);
1332                         if (
1333                             pp != NULL ||
1334                             vm_pager_has_page(object, new_pindex, NULL, NULL)
1335                         ) {
1336                                 /*
1337                                  * page already exists in parent OR swap exists
1338                                  * for this location in the parent.  Destroy
1339                                  * the original page from the backing object.
1340                                  *
1341                                  * Leave the parent's page alone
1342                                  */
1343                                 vm_page_protect(p, VM_PROT_NONE);
1344                                 vm_page_free(p);
1345                                 p = next;
1346                                 continue;
1347                         }
1348
1349                         /*
1350                          * Page does not exist in parent, rename the
1351                          * page from the backing object to the main object.
1352                          *
1353                          * If the page was mapped to a process, it can remain
1354                          * mapped through the rename.
1355                          */
1356                         if ((p->queue - p->pc) == PQ_CACHE)
1357                                 vm_page_deactivate(p);
1358
1359                         vm_page_rename(p, object, new_pindex);
1360                         /* page automatically made dirty by rename */
1361                 }
1362                 p = next;
1363         }
1364         splx(s);
1365         return (r);
1366 }
1367
1368
1369 /*
1370  * this version of collapse allows the operation to occur earlier and
1371  * when paging_in_progress is true for an object...  This is not a complete
1372  * operation, but should plug 99.9% of the rest of the leaks.
1373  */
1374 static void
1375 vm_object_qcollapse(vm_object_t object)
1376 {
1377         vm_object_t backing_object = object->backing_object;
1378
1379         GIANT_REQUIRED;
1380
1381         if (backing_object->ref_count != 1)
1382                 return;
1383
1384         backing_object->ref_count += 2;
1385
1386         vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1387
1388         backing_object->ref_count -= 2;
1389 }
1390
1391 /*
1392  *      vm_object_collapse:
1393  *
1394  *      Collapse an object with the object backing it.
1395  *      Pages in the backing object are moved into the
1396  *      parent, and the backing object is deallocated.
1397  */
1398 void
1399 vm_object_collapse(vm_object_t object)
1400 {
1401         GIANT_REQUIRED;
1402
1403         while (TRUE) {
1404                 vm_object_t backing_object;
1405
1406                 /*
1407                  * Verify that the conditions are right for collapse:
1408                  *
1409                  * The object exists and the backing object exists.
1410                  */
1411                 if (object == NULL)
1412                         break;
1413
1414                 if ((backing_object = object->backing_object) == NULL)
1415                         break;
1416
1417                 /*
1418                  * we check the backing object first, because it is most likely
1419                  * not collapsable.
1420                  */
1421                 if (backing_object->handle != NULL ||
1422                     (backing_object->type != OBJT_DEFAULT &&
1423                      backing_object->type != OBJT_SWAP) ||
1424                     (backing_object->flags & OBJ_DEAD) ||
1425                     object->handle != NULL ||
1426                     (object->type != OBJT_DEFAULT &&
1427                      object->type != OBJT_SWAP) ||
1428                     (object->flags & OBJ_DEAD)) {
1429                         break;
1430                 }
1431
1432                 if (
1433                     object->paging_in_progress != 0 ||
1434                     backing_object->paging_in_progress != 0
1435                 ) {
1436                         vm_object_qcollapse(object);
1437                         break;
1438                 }
1439
1440                 /*
1441                  * We know that we can either collapse the backing object (if
1442                  * the parent is the only reference to it) or (perhaps) have
1443                  * the parent bypass the object if the parent happens to shadow
1444                  * all the resident pages in the entire backing object.
1445                  *
1446                  * This is ignoring pager-backed pages such as swap pages.
1447                  * vm_object_backing_scan fails the shadowing test in this
1448                  * case.
1449                  */
1450                 if (backing_object->ref_count == 1) {
1451                         /*
1452                          * If there is exactly one reference to the backing
1453                          * object, we can collapse it into the parent.
1454                          */
1455                         vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1456
1457                         /*
1458                          * Move the pager from backing_object to object.
1459                          */
1460                         if (backing_object->type == OBJT_SWAP) {
1461                                 vm_object_pip_add(backing_object, 1);
1462
1463                                 /*
1464                                  * scrap the paging_offset junk and do a
1465                                  * discrete copy.  This also removes major
1466                                  * assumptions about how the swap-pager
1467                                  * works from where it doesn't belong.  The
1468                                  * new swapper is able to optimize the
1469                                  * destroy-source case.
1470                                  */
1471                                 vm_object_pip_add(object, 1);
1472                                 swap_pager_copy(
1473                                     backing_object,
1474                                     object,
1475                                     OFF_TO_IDX(object->backing_object_offset), TRUE);
1476                                 vm_object_pip_wakeup(object);
1477
1478                                 vm_object_pip_wakeup(backing_object);
1479                         }
1480                         /*
1481                          * Object now shadows whatever backing_object did.
1482                          * Note that the reference to
1483                          * backing_object->backing_object moves from within
1484                          * backing_object to within object.
1485                          */
1486                         TAILQ_REMOVE(
1487                             &object->backing_object->shadow_head,
1488                             object,
1489                             shadow_list
1490                         );
1491                         object->backing_object->shadow_count--;
1492                         object->backing_object->generation++;
1493                         if (backing_object->backing_object) {
1494                                 TAILQ_REMOVE(
1495                                     &backing_object->backing_object->shadow_head,
1496                                     backing_object,
1497                                     shadow_list
1498                                 );
1499                                 backing_object->backing_object->shadow_count--;
1500                                 backing_object->backing_object->generation++;
1501                         }
1502                         object->backing_object = backing_object->backing_object;
1503                         if (object->backing_object) {
1504                                 TAILQ_INSERT_TAIL(
1505                                     &object->backing_object->shadow_head,
1506                                     object,
1507                                     shadow_list
1508                                 );
1509                                 object->backing_object->shadow_count++;
1510                                 object->backing_object->generation++;
1511                         }
1512
1513                         object->backing_object_offset +=
1514                             backing_object->backing_object_offset;
1515
1516                         /*
1517                          * Discard backing_object.
1518                          *
1519                          * Since the backing object has no pages, no pager left,
1520                          * and no object references within it, all that is
1521                          * necessary is to dispose of it.
1522                          */
1523                         KASSERT(backing_object->ref_count == 1, ("backing_object %p was somehow re-referenced during collapse!", backing_object));
1524                         KASSERT(TAILQ_FIRST(&backing_object->memq) == NULL, ("backing_object %p somehow has left over pages during collapse!", backing_object));
1525
1526                         mtx_lock(&vm_object_list_mtx);
1527                         TAILQ_REMOVE(
1528                             &vm_object_list,
1529                             backing_object,
1530                             object_list
1531                         );
1532                         mtx_unlock(&vm_object_list_mtx);
1533
1534                         uma_zfree(obj_zone, backing_object);
1535
1536                         object_collapses++;
1537                 } else {
1538                         vm_object_t new_backing_object;
1539
1540                         /*
1541                          * If we do not entirely shadow the backing object,
1542                          * there is nothing we can do so we give up.
1543                          */
1544                         if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) {
1545                                 break;
1546                         }
1547
1548                         /*
1549                          * Make the parent shadow the next object in the
1550                          * chain.  Deallocating backing_object will not remove
1551                          * it, since its reference count is at least 2.
1552                          */
1553                         TAILQ_REMOVE(
1554                             &backing_object->shadow_head,
1555                             object,
1556                             shadow_list
1557                         );
1558                         backing_object->shadow_count--;
1559                         backing_object->generation++;
1560
1561                         new_backing_object = backing_object->backing_object;
1562                         if ((object->backing_object = new_backing_object) != NULL) {
1563                                 vm_object_reference(new_backing_object);
1564                                 TAILQ_INSERT_TAIL(
1565                                     &new_backing_object->shadow_head,
1566                                     object,
1567                                     shadow_list
1568                                 );
1569                                 new_backing_object->shadow_count++;
1570                                 new_backing_object->generation++;
1571                                 object->backing_object_offset +=
1572                                         backing_object->backing_object_offset;
1573                         }
1574
1575                         /*
1576                          * Drop the reference count on backing_object. Since
1577                          * its ref_count was at least 2, it will not vanish;
1578                          * so we don't need to call vm_object_deallocate, but
1579                          * we do anyway.
1580                          */
1581                         vm_object_deallocate(backing_object);
1582                         object_bypasses++;
1583                 }
1584
1585                 /*
1586                  * Try again with this object's new backing object.
1587                  */
1588         }
1589 }
1590
1591 /*
1592  *      vm_object_page_remove: [internal]
1593  *
1594  *      Removes all physical pages in the specified
1595  *      object range from the object's list of pages.
1596  *
1597  *      The object must be locked.
1598  */
1599 void
1600 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end, boolean_t clean_only)
1601 {
1602         vm_page_t p, next;
1603         unsigned int size;
1604         int all;
1605
1606         GIANT_REQUIRED;
1607
1608         if (object == NULL ||
1609             object->resident_page_count == 0)
1610                 return;
1611
1612         all = ((end == 0) && (start == 0));
1613
1614         /*
1615          * Since physically-backed objects do not use managed pages, we can't
1616          * remove pages from the object (we must instead remove the page
1617          * references, and then destroy the object).
1618          */
1619         KASSERT(object->type != OBJT_PHYS, ("attempt to remove pages from a physical object"));
1620
1621         vm_object_pip_add(object, 1);
1622 again:
1623         size = end - start;
1624         if (all || size > object->resident_page_count / 4) {
1625                 for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
1626                         next = TAILQ_NEXT(p, listq);
1627                         if (all || ((start <= p->pindex) && (p->pindex < end))) {
1628                                 if (p->wire_count != 0) {
1629                                         vm_page_protect(p, VM_PROT_NONE);
1630                                         if (!clean_only)
1631                                                 p->valid = 0;
1632                                         continue;
1633                                 }
1634
1635                                 /*
1636                                  * The busy flags are only cleared at
1637                                  * interrupt -- minimize the spl transitions
1638                                  */
1639                                 if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1640                                         goto again;
1641
1642                                 if (clean_only && p->valid) {
1643                                         vm_page_test_dirty(p);
1644                                         if (p->valid & p->dirty)
1645                                                 continue;
1646                                 }
1647
1648                                 vm_page_busy(p);
1649                                 vm_page_protect(p, VM_PROT_NONE);
1650                                 vm_page_free(p);
1651                         }
1652                 }
1653         } else {
1654                 while (size > 0) {
1655                         if ((p = vm_page_lookup(object, start)) != 0) {
1656
1657                                 if (p->wire_count != 0) {
1658                                         vm_page_protect(p, VM_PROT_NONE);
1659                                         if (!clean_only)
1660                                                 p->valid = 0;
1661                                         start += 1;
1662                                         size -= 1;
1663                                         continue;
1664                                 }
1665
1666                                 /*
1667                                  * The busy flags are only cleared at
1668                                  * interrupt -- minimize the spl transitions
1669                                  */
1670                                 if (vm_page_sleep_busy(p, TRUE, "vmopar"))
1671                                         goto again;
1672
1673                                 if (clean_only && p->valid) {
1674                                         vm_page_test_dirty(p);
1675                                         if (p->valid & p->dirty) {
1676                                                 start += 1;
1677                                                 size -= 1;
1678                                                 continue;
1679                                         }
1680                                 }
1681
1682                                 vm_page_busy(p);
1683                                 vm_page_protect(p, VM_PROT_NONE);
1684                                 vm_page_free(p);
1685                         }
1686                         start += 1;
1687                         size -= 1;
1688                 }
1689         }
1690         vm_object_pip_wakeup(object);
1691 }
1692
1693 /*
1694  *      Routine:        vm_object_coalesce
1695  *      Function:       Coalesces two objects backing up adjoining
1696  *                      regions of memory into a single object.
1697  *
1698  *      returns TRUE if objects were combined.
1699  *
1700  *      NOTE:   Only works at the moment if the second object is NULL -
1701  *              if it's not, which object do we lock first?
1702  *
1703  *      Parameters:
1704  *              prev_object     First object to coalesce
1705  *              prev_offset     Offset into prev_object
1706  *              next_object     Second object into coalesce
1707  *              next_offset     Offset into next_object
1708  *
1709  *              prev_size       Size of reference to prev_object
1710  *              next_size       Size of reference to next_object
1711  *
1712  *      Conditions:
1713  *      The object must *not* be locked.
1714  */
1715 boolean_t
1716 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex, vm_size_t prev_size, vm_size_t next_size)
1717 {
1718         vm_pindex_t next_pindex;
1719
1720         GIANT_REQUIRED;
1721
1722         if (prev_object == NULL) {
1723                 return (TRUE);
1724         }
1725
1726         if (prev_object->type != OBJT_DEFAULT &&
1727             prev_object->type != OBJT_SWAP) {
1728                 return (FALSE);
1729         }
1730
1731         /*
1732          * Try to collapse the object first
1733          */
1734         vm_object_collapse(prev_object);
1735
1736         /*
1737          * Can't coalesce if: . more than one reference . paged out . shadows
1738          * another object . has a copy elsewhere (any of which mean that the
1739          * pages not mapped to prev_entry may be in use anyway)
1740          */
1741         if (prev_object->backing_object != NULL) {
1742                 return (FALSE);
1743         }
1744
1745         prev_size >>= PAGE_SHIFT;
1746         next_size >>= PAGE_SHIFT;
1747         next_pindex = prev_pindex + prev_size;
1748
1749         if ((prev_object->ref_count > 1) &&
1750             (prev_object->size != next_pindex)) {
1751                 return (FALSE);
1752         }
1753
1754         /*
1755          * Remove any pages that may still be in the object from a previous
1756          * deallocation.
1757          */
1758         if (next_pindex < prev_object->size) {
1759                 vm_object_page_remove(prev_object,
1760                                       next_pindex,
1761                                       next_pindex + next_size, FALSE);
1762                 if (prev_object->type == OBJT_SWAP)
1763                         swap_pager_freespace(prev_object,
1764                                              next_pindex, next_size);
1765         }
1766
1767         /*
1768          * Extend the object if necessary.
1769          */
1770         if (next_pindex + next_size > prev_object->size)
1771                 prev_object->size = next_pindex + next_size;
1772
1773         return (TRUE);
1774 }
1775
1776 void
1777 vm_object_set_writeable_dirty(vm_object_t object)
1778 {
1779         struct vnode *vp;
1780
1781         vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
1782         if (object->type == OBJT_VNODE &&
1783             (vp = (struct vnode *)object->handle) != NULL) {
1784                 if ((vp->v_flag & VOBJDIRTY) == 0) {
1785                         mtx_lock(&vp->v_interlock);
1786                         vp->v_flag |= VOBJDIRTY;
1787                         mtx_unlock(&vp->v_interlock);
1788                 }
1789         }
1790 }
1791
1792 #ifdef ENABLE_VFS_IOOPT
1793 /*
1794  * Experimental support for zero-copy I/O
1795  *
1796  * Performs the copy_on_write operations necessary to allow the virtual copies
1797  * into user space to work.  This has to be called for write(2) system calls
1798  * from other processes, file unlinking, and file size shrinkage.
1799  */
1800 void
1801 vm_freeze_copyopts(vm_object_t object, vm_pindex_t froma, vm_pindex_t toa)
1802 {
1803         int rv;
1804         vm_object_t robject;
1805         vm_pindex_t idx;
1806
1807         GIANT_REQUIRED;
1808         if ((object == NULL) ||
1809                 ((object->flags & OBJ_OPT) == 0))
1810                 return;
1811
1812         if (object->shadow_count > object->ref_count)
1813                 panic("vm_freeze_copyopts: sc > rc");
1814
1815         while ((robject = TAILQ_FIRST(&object->shadow_head)) != NULL) {
1816                 vm_pindex_t bo_pindex;
1817                 vm_page_t m_in, m_out;
1818
1819                 bo_pindex = OFF_TO_IDX(robject->backing_object_offset);
1820
1821                 vm_object_reference(robject);
1822
1823                 vm_object_pip_wait(robject, "objfrz");
1824
1825                 if (robject->ref_count == 1) {
1826                         vm_object_deallocate(robject);
1827                         continue;
1828                 }
1829
1830                 vm_object_pip_add(robject, 1);
1831
1832                 for (idx = 0; idx < robject->size; idx++) {
1833
1834                         m_out = vm_page_grab(robject, idx,
1835                                                 VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
1836
1837                         if (m_out->valid == 0) {
1838                                 m_in = vm_page_grab(object, bo_pindex + idx,
1839                                                 VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
1840                                 if (m_in->valid == 0) {
1841                                         rv = vm_pager_get_pages(object, &m_in, 1, 0);
1842                                         if (rv != VM_PAGER_OK) {
1843                                                 printf("vm_freeze_copyopts: cannot read page from file: %lx\n", (long)m_in->pindex);
1844                                                 continue;
1845                                         }
1846                                         vm_page_deactivate(m_in);
1847                                 }
1848
1849                                 vm_page_protect(m_in, VM_PROT_NONE);
1850                                 pmap_copy_page(m_in, m_out);
1851                                 m_out->valid = m_in->valid;
1852                                 vm_page_dirty(m_out);
1853                                 vm_page_activate(m_out);
1854                                 vm_page_wakeup(m_in);
1855                         }
1856                         vm_page_wakeup(m_out);
1857                 }
1858
1859                 object->shadow_count--;
1860                 object->ref_count--;
1861                 TAILQ_REMOVE(&object->shadow_head, robject, shadow_list);
1862                 robject->backing_object = NULL;
1863                 robject->backing_object_offset = 0;
1864
1865                 vm_object_pip_wakeup(robject);
1866                 vm_object_deallocate(robject);
1867         }
1868
1869         vm_object_clear_flag(object, OBJ_OPT);
1870 }
1871 #endif
1872
1873 #include "opt_ddb.h"
1874 #ifdef DDB
1875 #include <sys/kernel.h>
1876
1877 #include <sys/cons.h>
1878
1879 #include <ddb/ddb.h>
1880
1881 static int
1882 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
1883 {
1884         vm_map_t tmpm;
1885         vm_map_entry_t tmpe;
1886         vm_object_t obj;
1887         int entcount;
1888
1889         if (map == 0)
1890                 return 0;
1891
1892         if (entry == 0) {
1893                 tmpe = map->header.next;
1894                 entcount = map->nentries;
1895                 while (entcount-- && (tmpe != &map->header)) {
1896                         if (_vm_object_in_map(map, object, tmpe)) {
1897                                 return 1;
1898                         }
1899                         tmpe = tmpe->next;
1900                 }
1901         } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
1902                 tmpm = entry->object.sub_map;
1903                 tmpe = tmpm->header.next;
1904                 entcount = tmpm->nentries;
1905                 while (entcount-- && tmpe != &tmpm->header) {
1906                         if (_vm_object_in_map(tmpm, object, tmpe)) {
1907                                 return 1;
1908                         }
1909                         tmpe = tmpe->next;
1910                 }
1911         } else if ((obj = entry->object.vm_object) != NULL) {
1912                 for (; obj; obj = obj->backing_object)
1913                         if (obj == object) {
1914                                 return 1;
1915                         }
1916         }
1917         return 0;
1918 }
1919
1920 static int
1921 vm_object_in_map(vm_object_t object)
1922 {
1923         struct proc *p;
1924
1925         /* sx_slock(&allproc_lock); */
1926         LIST_FOREACH(p, &allproc, p_list) {
1927                 if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
1928                         continue;
1929                 if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
1930                         /* sx_sunlock(&allproc_lock); */
1931                         return 1;
1932                 }
1933         }
1934         /* sx_sunlock(&allproc_lock); */
1935         if (_vm_object_in_map(kernel_map, object, 0))
1936                 return 1;
1937         if (_vm_object_in_map(kmem_map, object, 0))
1938                 return 1;
1939         if (_vm_object_in_map(pager_map, object, 0))
1940                 return 1;
1941         if (_vm_object_in_map(buffer_map, object, 0))
1942                 return 1;
1943         return 0;
1944 }
1945
1946 DB_SHOW_COMMAND(vmochk, vm_object_check)
1947 {
1948         vm_object_t object;
1949
1950         /*
1951          * make sure that internal objs are in a map somewhere
1952          * and none have zero ref counts.
1953          */
1954         TAILQ_FOREACH(object, &vm_object_list, object_list) {
1955                 if (object->handle == NULL &&
1956                     (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
1957                         if (object->ref_count == 0) {
1958                                 db_printf("vmochk: internal obj has zero ref count: %ld\n",
1959                                         (long)object->size);
1960                         }
1961                         if (!vm_object_in_map(object)) {
1962                                 db_printf(
1963                         "vmochk: internal obj is not in a map: "
1964                         "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
1965                                     object->ref_count, (u_long)object->size,
1966                                     (u_long)object->size,
1967                                     (void *)object->backing_object);
1968                         }
1969                 }
1970         }
1971 }
1972
1973 /*
1974  *      vm_object_print:        [ debug ]
1975  */
1976 DB_SHOW_COMMAND(object, vm_object_print_static)
1977 {
1978         /* XXX convert args. */
1979         vm_object_t object = (vm_object_t)addr;
1980         boolean_t full = have_addr;
1981
1982         vm_page_t p;
1983
1984         /* XXX count is an (unused) arg.  Avoid shadowing it. */
1985 #define count   was_count
1986
1987         int count;
1988
1989         if (object == NULL)
1990                 return;
1991
1992         db_iprintf(
1993             "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
1994             object, (int)object->type, (u_long)object->size,
1995             object->resident_page_count, object->ref_count, object->flags);
1996         /*
1997          * XXX no %qd in kernel.  Truncate object->backing_object_offset.
1998          */
1999         db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
2000             object->shadow_count,
2001             object->backing_object ? object->backing_object->ref_count : 0,
2002             object->backing_object, (long)object->backing_object_offset);
2003
2004         if (!full)
2005                 return;
2006
2007         db_indent += 2;
2008         count = 0;
2009         TAILQ_FOREACH(p, &object->memq, listq) {
2010                 if (count == 0)
2011                         db_iprintf("memory:=");
2012                 else if (count == 6) {
2013                         db_printf("\n");
2014                         db_iprintf(" ...");
2015                         count = 0;
2016                 } else
2017                         db_printf(",");
2018                 count++;
2019
2020                 db_printf("(off=0x%lx,page=0x%lx)",
2021                     (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
2022         }
2023         if (count != 0)
2024                 db_printf("\n");
2025         db_indent -= 2;
2026 }
2027
2028 /* XXX. */
2029 #undef count
2030
2031 /* XXX need this non-static entry for calling from vm_map_print. */
2032 void
2033 vm_object_print(
2034         /* db_expr_t */ long addr,
2035         boolean_t have_addr,
2036         /* db_expr_t */ long count,
2037         char *modif)
2038 {
2039         vm_object_print_static(addr, have_addr, count, modif);
2040 }
2041
2042 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
2043 {
2044         vm_object_t object;
2045         int nl = 0;
2046         int c;
2047
2048         TAILQ_FOREACH(object, &vm_object_list, object_list) {
2049                 vm_pindex_t idx, fidx;
2050                 vm_pindex_t osize;
2051                 vm_offset_t pa = -1, padiff;
2052                 int rcount;
2053                 vm_page_t m;
2054
2055                 db_printf("new object: %p\n", (void *)object);
2056                 if (nl > 18) {
2057                         c = cngetc();
2058                         if (c != ' ')
2059                                 return;
2060                         nl = 0;
2061                 }
2062                 nl++;
2063                 rcount = 0;
2064                 fidx = 0;
2065                 osize = object->size;
2066                 if (osize > 128)
2067                         osize = 128;
2068                 for (idx = 0; idx < osize; idx++) {
2069                         m = vm_page_lookup(object, idx);
2070                         if (m == NULL) {
2071                                 if (rcount) {
2072                                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2073                                                 (long)fidx, rcount, (long)pa);
2074                                         if (nl > 18) {
2075                                                 c = cngetc();
2076                                                 if (c != ' ')
2077                                                         return;
2078                                                 nl = 0;
2079                                         }
2080                                         nl++;
2081                                         rcount = 0;
2082                                 }
2083                                 continue;
2084                         }
2085
2086
2087                         if (rcount &&
2088                                 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
2089                                 ++rcount;
2090                                 continue;
2091                         }
2092                         if (rcount) {
2093                                 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
2094                                 padiff >>= PAGE_SHIFT;
2095                                 padiff &= PQ_L2_MASK;
2096                                 if (padiff == 0) {
2097                                         pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
2098                                         ++rcount;
2099                                         continue;
2100                                 }
2101                                 db_printf(" index(%ld)run(%d)pa(0x%lx)",
2102                                         (long)fidx, rcount, (long)pa);
2103                                 db_printf("pd(%ld)\n", (long)padiff);
2104                                 if (nl > 18) {
2105                                         c = cngetc();
2106                                         if (c != ' ')
2107                                                 return;
2108                                         nl = 0;
2109                                 }
2110                                 nl++;
2111                         }
2112                         fidx = idx;
2113                         pa = VM_PAGE_TO_PHYS(m);
2114                         rcount = 1;
2115                 }
2116                 if (rcount) {
2117                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2118                                 (long)fidx, rcount, (long)pa);
2119                         if (nl > 18) {
2120                                 c = cngetc();
2121                                 if (c != ' ')
2122                                         return;
2123                                 nl = 0;
2124                         }
2125                         nl++;
2126                 }
2127         }
2128 }
2129 #endif /* DDB */