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  * 4. 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.
  19  *
  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.
  31  *
  32  *      from: @(#)vm_object.c   8.5 (Berkeley) 3/22/94
  33  *
  34  *
  35  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
  36  * All rights reserved.
  37  *
  38  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
  39  *
  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.
  45  *
  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.
  49  *
  50  * Carnegie Mellon requests users of this software to return to
  51  *
  52  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  53  *  School of Computer Science
  54  *  Carnegie Mellon University
  55  *  Pittsburgh PA 15213-3890
  56  *
  57  * any improvements or extensions that they make and grant Carnegie the
  58  * rights to redistribute these changes.
  59  */
  60
  61 /*
  62  *      Virtual memory object module.
  63  */
  64
  65 #include <sys/cdefs.h>
  66 __FBSDID("$FreeBSD$");
  67
  68 #include "opt_vm.h"
  69
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/lock.h>
  73 #include <sys/mman.h>
  74 #include <sys/mount.h>
  75 #include <sys/kernel.h>
  76 #include <sys/sysctl.h>
  77 #include <sys/mutex.h>
  78 #include <sys/proc.h>           /* for curproc, pageproc */
  79 #include <sys/socket.h>
  80 #include <sys/resourcevar.h>
  81 #include <sys/rwlock.h>
  82 #include <sys/vnode.h>
  83 #include <sys/vmmeter.h>
  84 #include <sys/sx.h>
  85
  86 #include <vm/vm.h>
  87 #include <vm/vm_param.h>
  88 #include <vm/pmap.h>
  89 #include <vm/vm_map.h>
  90 #include <vm/vm_object.h>
  91 #include <vm/vm_page.h>
  92 #include <vm/vm_pageout.h>
  93 #include <vm/vm_pager.h>
  94 #include <vm/swap_pager.h>
  95 #include <vm/vm_kern.h>
  96 #include <vm/vm_extern.h>
  97 #include <vm/vm_radix.h>
  98 #include <vm/vm_reserv.h>
  99 #include <vm/uma.h>
 100
 101 static int old_msync;
 102 SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
 103     "Use old (insecure) msync behavior");
 104
 105 static int      vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
 106                     int pagerflags, int flags, boolean_t *clearobjflags,
 107                     boolean_t *eio);
 108 static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
 109                     boolean_t *clearobjflags);
 110 static void     vm_object_qcollapse(vm_object_t object);
 111 static void     vm_object_vndeallocate(vm_object_t object);
 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
 142 struct vm_object kernel_object_store;
 143 struct vm_object kmem_object_store;
 144
 145 static SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD, 0,
 146     "VM object stats");
 147
 148 static long object_collapses;
 149 SYSCTL_LONG(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
 150     &object_collapses, 0, "VM object collapses");
 151
 152 static long object_bypasses;
 153 SYSCTL_LONG(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
 154     &object_bypasses, 0, "VM object bypasses");
 155
 156 static uma_zone_t obj_zone;
 157
 158 static int vm_object_zinit(void *mem, int size, int flags);
 159
 160 #ifdef INVARIANTS
 161 static void vm_object_zdtor(void *mem, int size, void *arg);
 162
 163 static void
 164 vm_object_zdtor(void *mem, int size, void *arg)
 165 {
 166         vm_object_t object;
 167
 168         object = (vm_object_t)mem;
 169         KASSERT(TAILQ_EMPTY(&object->memq),
 170             ("object %p has resident pages in its memq", object));
 171         KASSERT(vm_radix_is_empty(&object->rtree),
 172             ("object %p has resident pages in its trie", object));
 173 #if VM_NRESERVLEVEL > 0
 174         KASSERT(LIST_EMPTY(&object->rvq),
 175             ("object %p has reservations",
 176             object));
 177 #endif
 178         KASSERT(vm_object_cache_is_empty(object),
 179             ("object %p has cached pages",
 180             object));
 181         KASSERT(object->paging_in_progress == 0,
 182             ("object %p paging_in_progress = %d",
 183             object, object->paging_in_progress));
 184         KASSERT(object->resident_page_count == 0,
 185             ("object %p resident_page_count = %d",
 186             object, object->resident_page_count));
 187         KASSERT(object->shadow_count == 0,
 188             ("object %p shadow_count = %d",
 189             object, object->shadow_count));
 190 }
 191 #endif
 192
 193 static int
 194 vm_object_zinit(void *mem, int size, int flags)
 195 {
 196         vm_object_t object;
 197
 198         object = (vm_object_t)mem;
 199         bzero(&object->lock, sizeof(object->lock));
 200         rw_init_flags(&object->lock, "vm object", RW_DUPOK);
 201
 202         /* These are true for any object that has been freed */
 203         object->rtree.rt_root = 0;
 204         object->rtree.rt_flags = 0;
 205         object->paging_in_progress = 0;
 206         object->resident_page_count = 0;
 207         object->shadow_count = 0;
 208         object->cache.rt_root = 0;
 209         object->cache.rt_flags = 0;
 210         return (0);
 211 }
 212
 213 static void
 214 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
 215 {
 216
 217         TAILQ_INIT(&object->memq);
 218         LIST_INIT(&object->shadow_head);
 219
 220         object->type = type;
 221         switch (type) {
 222         case OBJT_DEAD:
 223                 panic("_vm_object_allocate: can't create OBJT_DEAD");
 224         case OBJT_DEFAULT:
 225         case OBJT_SWAP:
 226                 object->flags = OBJ_ONEMAPPING;
 227                 break;
 228         case OBJT_DEVICE:
 229         case OBJT_SG:
 230                 object->flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
 231                 break;
 232         case OBJT_MGTDEVICE:
 233                 object->flags = OBJ_FICTITIOUS;
 234                 break;
 235         case OBJT_PHYS:
 236                 object->flags = OBJ_UNMANAGED;
 237                 break;
 238         case OBJT_VNODE:
 239                 object->flags = 0;
 240                 break;
 241         default:
 242                 panic("_vm_object_allocate: type %d is undefined", type);
 243         }
 244         object->size = size;
 245         object->generation = 1;
 246         object->ref_count = 1;
 247         object->memattr = VM_MEMATTR_DEFAULT;
 248         object->cred = NULL;
 249         object->charge = 0;
 250         object->handle = NULL;
 251         object->backing_object = NULL;
 252         object->backing_object_offset = (vm_ooffset_t) 0;
 253 #if VM_NRESERVLEVEL > 0
 254         LIST_INIT(&object->rvq);
 255 #endif
 256
 257         mtx_lock(&vm_object_list_mtx);
 258         TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
 259         mtx_unlock(&vm_object_list_mtx);
 260 }
 261
 262 /*
 263  *      vm_object_init:
 264  *
 265  *      Initialize the VM objects module.
 266  */
 267 void
 268 vm_object_init(void)
 269 {
 270         TAILQ_INIT(&vm_object_list);
 271         mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
 272
 273         rw_init(&kernel_object->lock, "kernel vm object");
 274         _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 275             kernel_object);
 276 #if VM_NRESERVLEVEL > 0
 277         kernel_object->flags |= OBJ_COLORED;
 278         kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
 279 #endif
 280
 281         rw_init(&kmem_object->lock, "kmem vm object");
 282         _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 283             kmem_object);
 284 #if VM_NRESERVLEVEL > 0
 285         kmem_object->flags |= OBJ_COLORED;
 286         kmem_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
 287 #endif
 288
 289         /*
 290          * The lock portion of struct vm_object must be type stable due
 291          * to vm_pageout_fallback_object_lock locking a vm object
 292          * without holding any references to it.
 293          */
 294         obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
 295 #ifdef INVARIANTS
 296             vm_object_zdtor,
 297 #else
 298             NULL,
 299 #endif
 300             vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 301
 302         vm_radix_init();
 303 }
 304
 305 void
 306 vm_object_clear_flag(vm_object_t object, u_short bits)
 307 {
 308
 309         VM_OBJECT_ASSERT_WLOCKED(object);
 310         object->flags &= ~bits;
 311 }
 312
 313 /*
 314  *      Sets the default memory attribute for the specified object.  Pages
 315  *      that are allocated to this object are by default assigned this memory
 316  *      attribute.
 317  *
 318  *      Presently, this function must be called before any pages are allocated
 319  *      to the object.  In the future, this requirement may be relaxed for
 320  *      "default" and "swap" objects.
 321  */
 322 int
 323 vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
 324 {
 325
 326         VM_OBJECT_ASSERT_WLOCKED(object);
 327         switch (object->type) {
 328         case OBJT_DEFAULT:
 329         case OBJT_DEVICE:
 330         case OBJT_MGTDEVICE:
 331         case OBJT_PHYS:
 332         case OBJT_SG:
 333         case OBJT_SWAP:
 334         case OBJT_VNODE:
 335                 if (!TAILQ_EMPTY(&object->memq))
 336                         return (KERN_FAILURE);
 337                 break;
 338         case OBJT_DEAD:
 339                 return (KERN_INVALID_ARGUMENT);
 340         default:
 341                 panic("vm_object_set_memattr: object %p is of undefined type",
 342                     object);
 343         }
 344         object->memattr = memattr;
 345         return (KERN_SUCCESS);
 346 }
 347
 348 void
 349 vm_object_pip_add(vm_object_t object, short i)
 350 {
 351
 352         VM_OBJECT_ASSERT_WLOCKED(object);
 353         object->paging_in_progress += i;
 354 }
 355
 356 void
 357 vm_object_pip_subtract(vm_object_t object, short i)
 358 {
 359
 360         VM_OBJECT_ASSERT_WLOCKED(object);
 361         object->paging_in_progress -= i;
 362 }
 363
 364 void
 365 vm_object_pip_wakeup(vm_object_t object)
 366 {
 367
 368         VM_OBJECT_ASSERT_WLOCKED(object);
 369         object->paging_in_progress--;
 370         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
 371                 vm_object_clear_flag(object, OBJ_PIPWNT);
 372                 wakeup(object);
 373         }
 374 }
 375
 376 void
 377 vm_object_pip_wakeupn(vm_object_t object, short i)
 378 {
 379
 380         VM_OBJECT_ASSERT_WLOCKED(object);
 381         if (i)
 382                 object->paging_in_progress -= i;
 383         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
 384                 vm_object_clear_flag(object, OBJ_PIPWNT);
 385                 wakeup(object);
 386         }
 387 }
 388
 389 void
 390 vm_object_pip_wait(vm_object_t object, char *waitid)
 391 {
 392
 393         VM_OBJECT_ASSERT_WLOCKED(object);
 394         while (object->paging_in_progress) {
 395                 object->flags |= OBJ_PIPWNT;
 396                 VM_OBJECT_SLEEP(object, object, PVM, waitid, 0);
 397         }
 398 }
 399
 400 /*
 401  *      vm_object_allocate:
 402  *
 403  *      Returns a new object with the given size.
 404  */
 405 vm_object_t
 406 vm_object_allocate(objtype_t type, vm_pindex_t size)
 407 {
 408         vm_object_t object;
 409
 410         object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
 411         _vm_object_allocate(type, size, object);
 412         return (object);
 413 }
 414
 415
 416 /*
 417  *      vm_object_reference:
 418  *
 419  *      Gets another reference to the given object.  Note: OBJ_DEAD
 420  *      objects can be referenced during final cleaning.
 421  */
 422 void
 423 vm_object_reference(vm_object_t object)
 424 {
 425         if (object == NULL)
 426                 return;
 427         VM_OBJECT_WLOCK(object);
 428         vm_object_reference_locked(object);
 429         VM_OBJECT_WUNLOCK(object);
 430 }
 431
 432 /*
 433  *      vm_object_reference_locked:
 434  *
 435  *      Gets another reference to the given object.
 436  *
 437  *      The object must be locked.
 438  */
 439 void
 440 vm_object_reference_locked(vm_object_t object)
 441 {
 442         struct vnode *vp;
 443
 444         VM_OBJECT_ASSERT_WLOCKED(object);
 445         object->ref_count++;
 446         if (object->type == OBJT_VNODE) {
 447                 vp = object->handle;
 448                 vref(vp);
 449         }
 450 }
 451
 452 /*
 453  * Handle deallocating an object of type OBJT_VNODE.
 454  */
 455 static void
 456 vm_object_vndeallocate(vm_object_t object)
 457 {
 458         struct vnode *vp = (struct vnode *) object->handle;
 459
 460         VM_OBJECT_ASSERT_WLOCKED(object);
 461         KASSERT(object->type == OBJT_VNODE,
 462             ("vm_object_vndeallocate: not a vnode object"));
 463         KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
 464 #ifdef INVARIANTS
 465         if (object->ref_count == 0) {
 466                 vprint("vm_object_vndeallocate", vp);
 467                 panic("vm_object_vndeallocate: bad object reference count");
 468         }
 469 #endif
 470
 471         if (object->ref_count > 1) {
 472                 object->ref_count--;
 473                 VM_OBJECT_WUNLOCK(object);
 474                 /* vrele may need the vnode lock. */
 475                 vrele(vp);
 476         } else {
 477                 vhold(vp);
 478                 VM_OBJECT_WUNLOCK(object);
 479                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 480                 vdrop(vp);
 481                 VM_OBJECT_WLOCK(object);
 482                 object->ref_count--;
 483                 if (object->type == OBJT_DEAD) {
 484                         VM_OBJECT_WUNLOCK(object);
 485                         VOP_UNLOCK(vp, 0);
 486                 } else {
 487                         if (object->ref_count == 0)
 488                                 VOP_UNSET_TEXT(vp);
 489                         VM_OBJECT_WUNLOCK(object);
 490                         vput(vp);
 491                 }
 492         }
 493 }
 494
 495 /*
 496  *      vm_object_deallocate:
 497  *
 498  *      Release a reference to the specified object,
 499  *      gained either through a vm_object_allocate
 500  *      or a vm_object_reference call.  When all references
 501  *      are gone, storage associated with this object
 502  *      may be relinquished.
 503  *
 504  *      No object may be locked.
 505  */
 506 void
 507 vm_object_deallocate(vm_object_t object)
 508 {
 509         vm_object_t temp;
 510         struct vnode *vp;
 511
 512         while (object != NULL) {
 513                 VM_OBJECT_WLOCK(object);
 514                 if (object->type == OBJT_VNODE) {
 515                         vm_object_vndeallocate(object);
 516                         return;
 517                 }
 518
 519                 KASSERT(object->ref_count != 0,
 520                         ("vm_object_deallocate: object deallocated too many times: %d", object->type));
 521
 522                 /*
 523                  * If the reference count goes to 0 we start calling
 524                  * vm_object_terminate() on the object chain.
 525                  * A ref count of 1 may be a special case depending on the
 526                  * shadow count being 0 or 1.
 527                  */
 528                 object->ref_count--;
 529                 if (object->ref_count > 1) {
 530                         VM_OBJECT_WUNLOCK(object);
 531                         return;
 532                 } else if (object->ref_count == 1) {
 533                         if (object->type == OBJT_SWAP &&
 534                             (object->flags & OBJ_TMPFS) != 0) {
 535                                 vp = object->un_pager.swp.swp_tmpfs;
 536                                 vhold(vp);
 537                                 VM_OBJECT_WUNLOCK(object);
 538                                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 539                                 vdrop(vp);
 540                                 VM_OBJECT_WLOCK(object);
 541                                 if (object->type == OBJT_DEAD ||
 542                                     object->ref_count != 1) {
 543                                         VM_OBJECT_WUNLOCK(object);
 544                                         VOP_UNLOCK(vp, 0);
 545                                         return;
 546                                 }
 547                                 if ((object->flags & OBJ_TMPFS) != 0)
 548                                         VOP_UNSET_TEXT(vp);
 549                                 VOP_UNLOCK(vp, 0);
 550                         }
 551                         if (object->shadow_count == 0 &&
 552                             object->handle == NULL &&
 553                             (object->type == OBJT_DEFAULT ||
 554                             (object->type == OBJT_SWAP &&
 555                             (object->flags & OBJ_TMPFS) == 0))) {
 556                                 vm_object_set_flag(object, OBJ_ONEMAPPING);
 557                         } else if ((object->shadow_count == 1) &&
 558                             (object->handle == NULL) &&
 559                             (object->type == OBJT_DEFAULT ||
 560                              object->type == OBJT_SWAP)) {
 561                                 KASSERT((object->flags & OBJ_TMPFS) == 0,
 562                                     ("shadowed tmpfs v_object %p", object));
 563                                 vm_object_t robject;
 564
 565                                 robject = LIST_FIRST(&object->shadow_head);
 566                                 KASSERT(robject != NULL,
 567                                     ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
 568                                          object->ref_count,
 569                                          object->shadow_count));
 570                                 if (!VM_OBJECT_TRYWLOCK(robject)) {
 571                                         /*
 572                                          * Avoid a potential deadlock.
 573                                          */
 574                                         object->ref_count++;
 575                                         VM_OBJECT_WUNLOCK(object);
 576                                         /*
 577                                          * More likely than not the thread
 578                                          * holding robject's lock has lower
 579                                          * priority than the current thread.
 580                                          * Let the lower priority thread run.
 581                                          */
 582                                         pause("vmo_de", 1);
 583                                         continue;
 584                                 }
 585                                 /*
 586                                  * Collapse object into its shadow unless its
 587                                  * shadow is dead.  In that case, object will
 588                                  * be deallocated by the thread that is
 589                                  * deallocating its shadow.
 590                                  */
 591                                 if ((robject->flags & OBJ_DEAD) == 0 &&
 592                                     (robject->handle == NULL) &&
 593                                     (robject->type == OBJT_DEFAULT ||
 594                                      robject->type == OBJT_SWAP)) {
 595
 596                                         robject->ref_count++;
 597 retry:
 598                                         if (robject->paging_in_progress) {
 599                                                 VM_OBJECT_WUNLOCK(object);
 600                                                 vm_object_pip_wait(robject,
 601                                                     "objde1");
 602                                                 temp = robject->backing_object;
 603                                                 if (object == temp) {
 604                                                         VM_OBJECT_WLOCK(object);
 605                                                         goto retry;
 606                                                 }
 607                                         } else if (object->paging_in_progress) {
 608                                                 VM_OBJECT_WUNLOCK(robject);
 609                                                 object->flags |= OBJ_PIPWNT;
 610                                                 VM_OBJECT_SLEEP(object, object,
 611                                                     PDROP | PVM, "objde2", 0);
 612                                                 VM_OBJECT_WLOCK(robject);
 613                                                 temp = robject->backing_object;
 614                                                 if (object == temp) {
 615                                                         VM_OBJECT_WLOCK(object);
 616                                                         goto retry;
 617                                                 }
 618                                         } else
 619                                                 VM_OBJECT_WUNLOCK(object);
 620
 621                                         if (robject->ref_count == 1) {
 622                                                 robject->ref_count--;
 623                                                 object = robject;
 624                                                 goto doterm;
 625                                         }
 626                                         object = robject;
 627                                         vm_object_collapse(object);
 628                                         VM_OBJECT_WUNLOCK(object);
 629                                         continue;
 630                                 }
 631                                 VM_OBJECT_WUNLOCK(robject);
 632                         }
 633                         VM_OBJECT_WUNLOCK(object);
 634                         return;
 635                 }
 636 doterm:
 637                 temp = object->backing_object;
 638                 if (temp != NULL) {
 639                         VM_OBJECT_WLOCK(temp);
 640                         LIST_REMOVE(object, shadow_list);
 641                         temp->shadow_count--;
 642                         VM_OBJECT_WUNLOCK(temp);
 643                         object->backing_object = NULL;
 644                 }
 645                 /*
 646                  * Don't double-terminate, we could be in a termination
 647                  * recursion due to the terminate having to sync data
 648                  * to disk.
 649                  */
 650                 if ((object->flags & OBJ_DEAD) == 0)
 651                         vm_object_terminate(object);
 652                 else
 653                         VM_OBJECT_WUNLOCK(object);
 654                 object = temp;
 655         }
 656 }
 657
 658 /*
 659  *      vm_object_destroy removes the object from the global object list
 660  *      and frees the space for the object.
 661  */
 662 void
 663 vm_object_destroy(vm_object_t object)
 664 {
 665
 666         /*
 667          * Remove the object from the global object list.
 668          */
 669         mtx_lock(&vm_object_list_mtx);
 670         TAILQ_REMOVE(&vm_object_list, object, object_list);
 671         mtx_unlock(&vm_object_list_mtx);
 672
 673         /*
 674          * Release the allocation charge.
 675          */
 676         if (object->cred != NULL) {
 677                 KASSERT(object->type == OBJT_DEFAULT ||
 678                     object->type == OBJT_SWAP,
 679                     ("%s: non-swap obj %p has cred", __func__, object));
 680                 swap_release_by_cred(object->charge, object->cred);
 681                 object->charge = 0;
 682                 crfree(object->cred);
 683                 object->cred = NULL;
 684         }
 685
 686         /*
 687          * Free the space for the object.
 688          */
 689         uma_zfree(obj_zone, object);
 690 }
 691
 692 /*
 693  *      vm_object_terminate actually destroys the specified object, freeing
 694  *      up all previously used resources.
 695  *
 696  *      The object must be locked.
 697  *      This routine may block.
 698  */
 699 void
 700 vm_object_terminate(vm_object_t object)
 701 {
 702         vm_page_t p, p_next;
 703
 704         VM_OBJECT_ASSERT_WLOCKED(object);
 705
 706         /*
 707          * Make sure no one uses us.
 708          */
 709         vm_object_set_flag(object, OBJ_DEAD);
 710
 711         /*
 712          * wait for the pageout daemon to be done with the object
 713          */
 714         vm_object_pip_wait(object, "objtrm");
 715
 716         KASSERT(!object->paging_in_progress,
 717                 ("vm_object_terminate: pageout in progress"));
 718
 719         /*
 720          * Clean and free the pages, as appropriate. All references to the
 721          * object are gone, so we don't need to lock it.
 722          */
 723         if (object->type == OBJT_VNODE) {
 724                 struct vnode *vp = (struct vnode *)object->handle;
 725
 726                 /*
 727                  * Clean pages and flush buffers.
 728                  */
 729                 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
 730                 VM_OBJECT_WUNLOCK(object);
 731
 732                 vinvalbuf(vp, V_SAVE, 0, 0);
 733
 734                 VM_OBJECT_WLOCK(object);
 735         }
 736
 737         KASSERT(object->ref_count == 0,
 738                 ("vm_object_terminate: object with references, ref_count=%d",
 739                 object->ref_count));
 740
 741         /*
 742          * Free any remaining pageable pages.  This also removes them from the
 743          * paging queues.  However, don't free wired pages, just remove them
 744          * from the object.  Rather than incrementally removing each page from
 745          * the object, the page and object are reset to any empty state.
 746          */
 747         TAILQ_FOREACH_SAFE(p, &object->memq, listq, p_next) {
 748                 vm_page_assert_unbusied(p);
 749                 vm_page_lock(p);
 750                 /*
 751                  * Optimize the page's removal from the object by resetting
 752                  * its "object" field.  Specifically, if the page is not
 753                  * wired, then the effect of this assignment is that
 754                  * vm_page_free()'s call to vm_page_remove() will return
 755                  * immediately without modifying the page or the object.
 756                  */
 757                 p->object = NULL;
 758                 if (p->wire_count == 0) {
 759                         vm_page_free(p);
 760                         PCPU_INC(cnt.v_pfree);
 761                 }
 762                 vm_page_unlock(p);
 763         }
 764         /*
 765          * If the object contained any pages, then reset it to an empty state.
 766          * None of the object's fields, including "resident_page_count", were
 767          * modified by the preceding loop.
 768          */
 769         if (object->resident_page_count != 0) {
 770                 vm_radix_reclaim_allnodes(&object->rtree);
 771                 TAILQ_INIT(&object->memq);
 772                 object->resident_page_count = 0;
 773                 if (object->type == OBJT_VNODE)
 774                         vdrop(object->handle);
 775         }
 776
 777 #if VM_NRESERVLEVEL > 0
 778         if (__predict_false(!LIST_EMPTY(&object->rvq)))
 779                 vm_reserv_break_all(object);
 780 #endif
 781         if (__predict_false(!vm_object_cache_is_empty(object)))
 782                 vm_page_cache_free(object, 0, 0);
 783
 784         /*
 785          * Let the pager know object is dead.
 786          */
 787         vm_pager_deallocate(object);
 788         VM_OBJECT_WUNLOCK(object);
 789
 790         vm_object_destroy(object);
 791 }
 792
 793 /*
 794  * Make the page read-only so that we can clear the object flags.  However, if
 795  * this is a nosync mmap then the object is likely to stay dirty so do not
 796  * mess with the page and do not clear the object flags.  Returns TRUE if the
 797  * page should be flushed, and FALSE otherwise.
 798  */
 799 static boolean_t
 800 vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *clearobjflags)
 801 {
 802
 803         /*
 804          * If we have been asked to skip nosync pages and this is a
 805          * nosync page, skip it.  Note that the object flags were not
 806          * cleared in this case so we do not have to set them.
 807          */
 808         if ((flags & OBJPC_NOSYNC) != 0 && (p->oflags & VPO_NOSYNC) != 0) {
 809                 *clearobjflags = FALSE;
 810                 return (FALSE);
 811         } else {
 812                 pmap_remove_write(p);
 813                 return (p->dirty != 0);
 814         }
 815 }
 816
 817 /*
 818  *      vm_object_page_clean
 819  *
 820  *      Clean all dirty pages in the specified range of object.  Leaves page
 821  *      on whatever queue it is currently on.   If NOSYNC is set then do not
 822  *      write out pages with VPO_NOSYNC set (originally comes from MAP_NOSYNC),
 823  *      leaving the object dirty.
 824  *
 825  *      When stuffing pages asynchronously, allow clustering.  XXX we need a
 826  *      synchronous clustering mode implementation.
 827  *
 828  *      Odd semantics: if start == end, we clean everything.
 829  *
 830  *      The object must be locked.
 831  *
 832  *      Returns FALSE if some page from the range was not written, as
 833  *      reported by the pager, and TRUE otherwise.
 834  */
 835 boolean_t
 836 vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
 837     int flags)
 838 {
 839         vm_page_t np, p;
 840         vm_pindex_t pi, tend, tstart;
 841         int curgeneration, n, pagerflags;
 842         boolean_t clearobjflags, eio, res;
 843
 844         VM_OBJECT_ASSERT_WLOCKED(object);
 845
 846         /*
 847          * The OBJ_MIGHTBEDIRTY flag is only set for OBJT_VNODE
 848          * objects.  The check below prevents the function from
 849          * operating on non-vnode objects.
 850          */
 851         if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
 852             object->resident_page_count == 0)
 853                 return (TRUE);
 854
 855         pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
 856             VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
 857         pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
 858
 859         tstart = OFF_TO_IDX(start);
 860         tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
 861         clearobjflags = tstart == 0 && tend >= object->size;
 862         res = TRUE;
 863
 864 rescan:
 865         curgeneration = object->generation;
 866
 867         for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
 868                 pi = p->pindex;
 869                 if (pi >= tend)
 870                         break;
 871                 np = TAILQ_NEXT(p, listq);
 872                 if (p->valid == 0)
 873                         continue;
 874                 if (vm_page_sleep_if_busy(p, "vpcwai")) {
 875                         if (object->generation != curgeneration) {
 876                                 if ((flags & OBJPC_SYNC) != 0)
 877                                         goto rescan;
 878                                 else
 879                                         clearobjflags = FALSE;
 880                         }
 881                         np = vm_page_find_least(object, pi);
 882                         continue;
 883                 }
 884                 if (!vm_object_page_remove_write(p, flags, &clearobjflags))
 885                         continue;
 886
 887                 n = vm_object_page_collect_flush(object, p, pagerflags,
 888                     flags, &clearobjflags, &eio);
 889                 if (eio) {
 890                         res = FALSE;
 891                         clearobjflags = FALSE;
 892                 }
 893                 if (object->generation != curgeneration) {
 894                         if ((flags & OBJPC_SYNC) != 0)
 895                                 goto rescan;
 896                         else
 897                                 clearobjflags = FALSE;
 898                 }
 899
 900                 /*
 901                  * If the VOP_PUTPAGES() did a truncated write, so
 902                  * that even the first page of the run is not fully
 903                  * written, vm_pageout_flush() returns 0 as the run
 904                  * length.  Since the condition that caused truncated
 905                  * write may be permanent, e.g. exhausted free space,
 906                  * accepting n == 0 would cause an infinite loop.
 907                  *
 908                  * Forwarding the iterator leaves the unwritten page
 909                  * behind, but there is not much we can do there if
 910                  * filesystem refuses to write it.
 911                  */
 912                 if (n == 0) {
 913                         n = 1;
 914                         clearobjflags = FALSE;
 915                 }
 916                 np = vm_page_find_least(object, pi + n);
 917         }
 918 #if 0
 919         VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
 920 #endif
 921
 922         if (clearobjflags)
 923                 vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
 924         return (res);
 925 }
 926
 927 static int
 928 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
 929     int flags, boolean_t *clearobjflags, boolean_t *eio)
 930 {
 931         vm_page_t ma[vm_pageout_page_count], p_first, tp;
 932         int count, i, mreq, runlen;
 933
 934         vm_page_lock_assert(p, MA_NOTOWNED);
 935         VM_OBJECT_ASSERT_WLOCKED(object);
 936
 937         count = 1;
 938         mreq = 0;
 939
 940         for (tp = p; count < vm_pageout_page_count; count++) {
 941                 tp = vm_page_next(tp);
 942                 if (tp == NULL || vm_page_busied(tp))
 943                         break;
 944                 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
 945                         break;
 946         }
 947
 948         for (p_first = p; count < vm_pageout_page_count; count++) {
 949                 tp = vm_page_prev(p_first);
 950                 if (tp == NULL || vm_page_busied(tp))
 951                         break;
 952                 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
 953                         break;
 954                 p_first = tp;
 955                 mreq++;
 956         }
 957
 958         for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
 959                 ma[i] = tp;
 960
 961         vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
 962         return (runlen);
 963 }
 964
 965 /*
 966  * Note that there is absolutely no sense in writing out
 967  * anonymous objects, so we track down the vnode object
 968  * to write out.
 969  * We invalidate (remove) all pages from the address space
 970  * for semantic correctness.
 971  *
 972  * If the backing object is a device object with unmanaged pages, then any
 973  * mappings to the specified range of pages must be removed before this
 974  * function is called.
 975  *
 976  * Note: certain anonymous maps, such as MAP_NOSYNC maps,
 977  * may start out with a NULL object.
 978  */
 979 boolean_t
 980 vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
 981     boolean_t syncio, boolean_t invalidate)
 982 {
 983         vm_object_t backing_object;
 984         struct vnode *vp;
 985         struct mount *mp;
 986         int error, flags, fsync_after;
 987         boolean_t res;
 988
 989         if (object == NULL)
 990                 return (TRUE);
 991         res = TRUE;
 992         error = 0;
 993         VM_OBJECT_WLOCK(object);
 994         while ((backing_object = object->backing_object) != NULL) {
 995                 VM_OBJECT_WLOCK(backing_object);
 996                 offset += object->backing_object_offset;
 997                 VM_OBJECT_WUNLOCK(object);
 998                 object = backing_object;
 999                 if (object->size < OFF_TO_IDX(offset + size))
1000                         size = IDX_TO_OFF(object->size) - offset;
1001         }
1002         /*
1003          * Flush pages if writing is allowed, invalidate them
1004          * if invalidation requested.  Pages undergoing I/O
1005          * will be ignored by vm_object_page_remove().
1006          *
1007          * We cannot lock the vnode and then wait for paging
1008          * to complete without deadlocking against vm_fault.
1009          * Instead we simply call vm_object_page_remove() and
1010          * allow it to block internally on a page-by-page
1011          * basis when it encounters pages undergoing async
1012          * I/O.
1013          */
1014         if (object->type == OBJT_VNODE &&
1015             (object->flags & OBJ_MIGHTBEDIRTY) != 0) {
1016                 vp = object->handle;
1017                 VM_OBJECT_WUNLOCK(object);
1018                 (void) vn_start_write(vp, &mp, V_WAIT);
1019                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1020                 if (syncio && !invalidate && offset == 0 &&
1021                     OFF_TO_IDX(size) == object->size) {
1022                         /*
1023                          * If syncing the whole mapping of the file,
1024                          * it is faster to schedule all the writes in
1025                          * async mode, also allowing the clustering,
1026                          * and then wait for i/o to complete.
1027                          */
1028                         flags = 0;
1029                         fsync_after = TRUE;
1030                 } else {
1031                         flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
1032                         flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
1033                         fsync_after = FALSE;
1034                 }
1035                 VM_OBJECT_WLOCK(object);
1036                 res = vm_object_page_clean(object, offset, offset + size,
1037                     flags);
1038                 VM_OBJECT_WUNLOCK(object);
1039                 if (fsync_after)
1040                         error = VOP_FSYNC(vp, MNT_WAIT, curthread);
1041                 VOP_UNLOCK(vp, 0);
1042                 vn_finished_write(mp);
1043                 if (error != 0)
1044                         res = FALSE;
1045                 VM_OBJECT_WLOCK(object);
1046         }
1047         if ((object->type == OBJT_VNODE ||
1048              object->type == OBJT_DEVICE) && invalidate) {
1049                 if (object->type == OBJT_DEVICE)
1050                         /*
1051                          * The option OBJPR_NOTMAPPED must be passed here
1052                          * because vm_object_page_remove() cannot remove
1053                          * unmanaged mappings.
1054                          */
1055                         flags = OBJPR_NOTMAPPED;
1056                 else if (old_msync)
1057                         flags = OBJPR_NOTWIRED;
1058                 else
1059                         flags = OBJPR_CLEANONLY | OBJPR_NOTWIRED;
1060                 vm_object_page_remove(object, OFF_TO_IDX(offset),
1061                     OFF_TO_IDX(offset + size + PAGE_MASK), flags);
1062         }
1063         VM_OBJECT_WUNLOCK(object);
1064         return (res);
1065 }
1066
1067 /*
1068  *      vm_object_madvise:
1069  *
1070  *      Implements the madvise function at the object/page level.
1071  *
1072  *      MADV_WILLNEED   (any object)
1073  *
1074  *          Activate the specified pages if they are resident.
1075  *
1076  *      MADV_DONTNEED   (any object)
1077  *
1078  *          Deactivate the specified pages if they are resident.
1079  *
1080  *      MADV_FREE       (OBJT_DEFAULT/OBJT_SWAP objects,
1081  *                       OBJ_ONEMAPPING only)
1082  *
1083  *          Deactivate and clean the specified pages if they are
1084  *          resident.  This permits the process to reuse the pages
1085  *          without faulting or the kernel to reclaim the pages
1086  *          without I/O.
1087  */
1088 void
1089 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
1090     int advise)
1091 {
1092         vm_pindex_t tpindex;
1093         vm_object_t backing_object, tobject;
1094         vm_page_t m;
1095
1096         if (object == NULL)
1097                 return;
1098         VM_OBJECT_WLOCK(object);
1099         /*
1100          * Locate and adjust resident pages
1101          */
1102         for (; pindex < end; pindex += 1) {
1103 relookup:
1104                 tobject = object;
1105                 tpindex = pindex;
1106 shadowlookup:
1107                 /*
1108                  * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1109                  * and those pages must be OBJ_ONEMAPPING.
1110                  */
1111                 if (advise == MADV_FREE) {
1112                         if ((tobject->type != OBJT_DEFAULT &&
1113                              tobject->type != OBJT_SWAP) ||
1114                             (tobject->flags & OBJ_ONEMAPPING) == 0) {
1115                                 goto unlock_tobject;
1116                         }
1117                 } else if ((tobject->flags & OBJ_UNMANAGED) != 0)
1118                         goto unlock_tobject;
1119                 m = vm_page_lookup(tobject, tpindex);
1120                 if (m == NULL && advise == MADV_WILLNEED) {
1121                         /*
1122                          * If the page is cached, reactivate it.
1123                          */
1124                         m = vm_page_alloc(tobject, tpindex, VM_ALLOC_IFCACHED |
1125                             VM_ALLOC_NOBUSY);
1126                 }
1127                 if (m == NULL) {
1128                         /*
1129                          * There may be swap even if there is no backing page
1130                          */
1131                         if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1132                                 swap_pager_freespace(tobject, tpindex, 1);
1133                         /*
1134                          * next object
1135                          */
1136                         backing_object = tobject->backing_object;
1137                         if (backing_object == NULL)
1138                                 goto unlock_tobject;
1139                         VM_OBJECT_WLOCK(backing_object);
1140                         tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1141                         if (tobject != object)
1142                                 VM_OBJECT_WUNLOCK(tobject);
1143                         tobject = backing_object;
1144                         goto shadowlookup;
1145                 } else if (m->valid != VM_PAGE_BITS_ALL)
1146                         goto unlock_tobject;
1147                 /*
1148                  * If the page is not in a normal state, skip it.
1149                  */
1150                 vm_page_lock(m);
1151                 if (m->hold_count != 0 || m->wire_count != 0) {
1152                         vm_page_unlock(m);
1153                         goto unlock_tobject;
1154                 }
1155                 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1156                     ("vm_object_madvise: page %p is fictitious", m));
1157                 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1158                     ("vm_object_madvise: page %p is not managed", m));
1159                 if (vm_page_busied(m)) {
1160                         if (advise == MADV_WILLNEED) {
1161                                 /*
1162                                  * Reference the page before unlocking and
1163                                  * sleeping so that the page daemon is less
1164                                  * likely to reclaim it.
1165                                  */
1166                                 vm_page_aflag_set(m, PGA_REFERENCED);
1167                         }
1168                         if (object != tobject)
1169                                 VM_OBJECT_WUNLOCK(object);
1170                         VM_OBJECT_WUNLOCK(tobject);
1171                         vm_page_busy_sleep(m, "madvpo");
1172                         VM_OBJECT_WLOCK(object);
1173                         goto relookup;
1174                 }
1175                 if (advise == MADV_WILLNEED) {
1176                         vm_page_activate(m);
1177                 } else {
1178                         vm_page_advise(m, advise);
1179                 }
1180                 vm_page_unlock(m);
1181                 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1182                         swap_pager_freespace(tobject, tpindex, 1);
1183 unlock_tobject:
1184                 if (tobject != object)
1185                         VM_OBJECT_WUNLOCK(tobject);
1186         }
1187         VM_OBJECT_WUNLOCK(object);
1188 }
1189
1190 /*
1191  *      vm_object_shadow:
1192  *
1193  *      Create a new object which is backed by the
1194  *      specified existing object range.  The source
1195  *      object reference is deallocated.
1196  *
1197  *      The new object and offset into that object
1198  *      are returned in the source parameters.
1199  */
1200 void
1201 vm_object_shadow(
1202         vm_object_t *object,    /* IN/OUT */
1203         vm_ooffset_t *offset,   /* IN/OUT */
1204         vm_size_t length)
1205 {
1206         vm_object_t source;
1207         vm_object_t result;
1208
1209         source = *object;
1210
1211         /*
1212          * Don't create the new object if the old object isn't shared.
1213          */
1214         if (source != NULL) {
1215                 VM_OBJECT_WLOCK(source);
1216                 if (source->ref_count == 1 &&
1217                     source->handle == NULL &&
1218                     (source->type == OBJT_DEFAULT ||
1219                      source->type == OBJT_SWAP)) {
1220                         VM_OBJECT_WUNLOCK(source);
1221                         return;
1222                 }
1223                 VM_OBJECT_WUNLOCK(source);
1224         }
1225
1226         /*
1227          * Allocate a new object with the given length.
1228          */
1229         result = vm_object_allocate(OBJT_DEFAULT, atop(length));
1230
1231         /*
1232          * The new object shadows the source object, adding a reference to it.
1233          * Our caller changes his reference to point to the new object,
1234          * removing a reference to the source object.  Net result: no change
1235          * of reference count.
1236          *
1237          * Try to optimize the result object's page color when shadowing
1238          * in order to maintain page coloring consistency in the combined
1239          * shadowed object.
1240          */
1241         result->backing_object = source;
1242         /*
1243          * Store the offset into the source object, and fix up the offset into
1244          * the new object.
1245          */
1246         result->backing_object_offset = *offset;
1247         if (source != NULL) {
1248                 VM_OBJECT_WLOCK(source);
1249                 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
1250                 source->shadow_count++;
1251 #if VM_NRESERVLEVEL > 0
1252                 result->flags |= source->flags & OBJ_COLORED;
1253                 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
1254                     ((1 << (VM_NFREEORDER - 1)) - 1);
1255 #endif
1256                 VM_OBJECT_WUNLOCK(source);
1257         }
1258
1259
1260         /*
1261          * Return the new things
1262          */
1263         *offset = 0;
1264         *object = result;
1265 }
1266
1267 /*
1268  *      vm_object_split:
1269  *
1270  * Split the pages in a map entry into a new object.  This affords
1271  * easier removal of unused pages, and keeps object inheritance from
1272  * being a negative impact on memory usage.
1273  */
1274 void
1275 vm_object_split(vm_map_entry_t entry)
1276 {
1277         vm_page_t m, m_next;
1278         vm_object_t orig_object, new_object, source;
1279         vm_pindex_t idx, offidxstart;
1280         vm_size_t size;
1281
1282         orig_object = entry->object.vm_object;
1283         if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
1284                 return;
1285         if (orig_object->ref_count <= 1)
1286                 return;
1287         VM_OBJECT_WUNLOCK(orig_object);
1288
1289         offidxstart = OFF_TO_IDX(entry->offset);
1290         size = atop(entry->end - entry->start);
1291
1292         /*
1293          * If swap_pager_copy() is later called, it will convert new_object
1294          * into a swap object.
1295          */
1296         new_object = vm_object_allocate(OBJT_DEFAULT, size);
1297
1298         /*
1299          * At this point, the new object is still private, so the order in
1300          * which the original and new objects are locked does not matter.
1301          */
1302         VM_OBJECT_WLOCK(new_object);
1303         VM_OBJECT_WLOCK(orig_object);
1304         source = orig_object->backing_object;
1305         if (source != NULL) {
1306                 VM_OBJECT_WLOCK(source);
1307                 if ((source->flags & OBJ_DEAD) != 0) {
1308                         VM_OBJECT_WUNLOCK(source);
1309                         VM_OBJECT_WUNLOCK(orig_object);
1310                         VM_OBJECT_WUNLOCK(new_object);
1311                         vm_object_deallocate(new_object);
1312                         VM_OBJECT_WLOCK(orig_object);
1313                         return;
1314                 }
1315                 LIST_INSERT_HEAD(&source->shadow_head,
1316                                   new_object, shadow_list);
1317                 source->shadow_count++;
1318                 vm_object_reference_locked(source);     /* for new_object */
1319                 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1320                 VM_OBJECT_WUNLOCK(source);
1321                 new_object->backing_object_offset =
1322                         orig_object->backing_object_offset + entry->offset;
1323                 new_object->backing_object = source;
1324         }
1325         if (orig_object->cred != NULL) {
1326                 new_object->cred = orig_object->cred;
1327                 crhold(orig_object->cred);
1328                 new_object->charge = ptoa(size);
1329                 KASSERT(orig_object->charge >= ptoa(size),
1330                     ("orig_object->charge < 0"));
1331                 orig_object->charge -= ptoa(size);
1332         }
1333 retry:
1334         m = vm_page_find_least(orig_object, offidxstart);
1335         for (; m != NULL && (idx = m->pindex - offidxstart) < size;
1336             m = m_next) {
1337                 m_next = TAILQ_NEXT(m, listq);
1338
1339                 /*
1340                  * We must wait for pending I/O to complete before we can
1341                  * rename the page.
1342                  *
1343                  * We do not have to VM_PROT_NONE the page as mappings should
1344                  * not be changed by this operation.
1345                  */
1346                 if (vm_page_busied(m)) {
1347                         VM_OBJECT_WUNLOCK(new_object);
1348                         vm_page_lock(m);
1349                         VM_OBJECT_WUNLOCK(orig_object);
1350                         vm_page_busy_sleep(m, "spltwt");
1351                         VM_OBJECT_WLOCK(orig_object);
1352                         VM_OBJECT_WLOCK(new_object);
1353                         goto retry;
1354                 }
1355
1356                 /* vm_page_rename() will handle dirty and cache. */
1357                 if (vm_page_rename(m, new_object, idx)) {
1358                         VM_OBJECT_WUNLOCK(new_object);
1359                         VM_OBJECT_WUNLOCK(orig_object);
1360                         VM_WAIT;
1361                         VM_OBJECT_WLOCK(orig_object);
1362                         VM_OBJECT_WLOCK(new_object);
1363                         goto retry;
1364                 }
1365 #if VM_NRESERVLEVEL > 0
1366                 /*
1367                  * If some of the reservation's allocated pages remain with
1368                  * the original object, then transferring the reservation to
1369                  * the new object is neither particularly beneficial nor
1370                  * particularly harmful as compared to leaving the reservation
1371                  * with the original object.  If, however, all of the
1372                  * reservation's allocated pages are transferred to the new
1373                  * object, then transferring the reservation is typically
1374                  * beneficial.  Determining which of these two cases applies
1375                  * would be more costly than unconditionally renaming the
1376                  * reservation.
1377                  */
1378                 vm_reserv_rename(m, new_object, orig_object, offidxstart);
1379 #endif
1380                 if (orig_object->type == OBJT_SWAP)
1381                         vm_page_xbusy(m);
1382         }
1383         if (orig_object->type == OBJT_SWAP) {
1384                 /*
1385                  * swap_pager_copy() can sleep, in which case the orig_object's
1386                  * and new_object's locks are released and reacquired.
1387                  */
1388                 swap_pager_copy(orig_object, new_object, offidxstart, 0);
1389                 TAILQ_FOREACH(m, &new_object->memq, listq)
1390                         vm_page_xunbusy(m);
1391
1392                 /*
1393                  * Transfer any cached pages from orig_object to new_object.
1394                  * If swap_pager_copy() found swapped out pages within the
1395                  * specified range of orig_object, then it changed
1396                  * new_object's type to OBJT_SWAP when it transferred those
1397                  * pages to new_object.  Otherwise, new_object's type
1398                  * should still be OBJT_DEFAULT and orig_object should not
1399                  * contain any cached pages within the specified range.
1400                  */
1401                 if (__predict_false(!vm_object_cache_is_empty(orig_object)))
1402                         vm_page_cache_transfer(orig_object, offidxstart,
1403                             new_object);
1404         }
1405         VM_OBJECT_WUNLOCK(orig_object);
1406         VM_OBJECT_WUNLOCK(new_object);
1407         entry->object.vm_object = new_object;
1408         entry->offset = 0LL;
1409         vm_object_deallocate(orig_object);
1410         VM_OBJECT_WLOCK(new_object);
1411 }
1412
1413 #define OBSC_TEST_ALL_SHADOWED  0x0001
1414 #define OBSC_COLLAPSE_NOWAIT    0x0002
1415 #define OBSC_COLLAPSE_WAIT      0x0004
1416
1417 static int
1418 vm_object_backing_scan(vm_object_t object, int op)
1419 {
1420         int r = 1;
1421         vm_page_t p;
1422         vm_object_t backing_object;
1423         vm_pindex_t backing_offset_index;
1424
1425         VM_OBJECT_ASSERT_WLOCKED(object);
1426         VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
1427
1428         backing_object = object->backing_object;
1429         backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1430
1431         /*
1432          * Initial conditions
1433          */
1434         if (op & OBSC_TEST_ALL_SHADOWED) {
1435                 /*
1436                  * We do not want to have to test for the existence of cache
1437                  * or swap pages in the backing object.  XXX but with the
1438                  * new swapper this would be pretty easy to do.
1439                  *
1440                  * XXX what about anonymous MAP_SHARED memory that hasn't
1441                  * been ZFOD faulted yet?  If we do not test for this, the
1442                  * shadow test may succeed! XXX
1443                  */
1444                 if (backing_object->type != OBJT_DEFAULT) {
1445                         return (0);
1446                 }
1447         }
1448         if (op & OBSC_COLLAPSE_WAIT) {
1449                 vm_object_set_flag(backing_object, OBJ_DEAD);
1450         }
1451
1452         /*
1453          * Our scan
1454          */
1455         p = TAILQ_FIRST(&backing_object->memq);
1456         while (p) {
1457                 vm_page_t next = TAILQ_NEXT(p, listq);
1458                 vm_pindex_t new_pindex = p->pindex - backing_offset_index;
1459
1460                 if (op & OBSC_TEST_ALL_SHADOWED) {
1461                         vm_page_t pp;
1462
1463                         /*
1464                          * Ignore pages outside the parent object's range
1465                          * and outside the parent object's mapping of the
1466                          * backing object.
1467                          *
1468                          * note that we do not busy the backing object's
1469                          * page.
1470                          */
1471                         if (
1472                             p->pindex < backing_offset_index ||
1473                             new_pindex >= object->size
1474                         ) {
1475                                 p = next;
1476                                 continue;
1477                         }
1478
1479                         /*
1480                          * See if the parent has the page or if the parent's
1481                          * object pager has the page.  If the parent has the
1482                          * page but the page is not valid, the parent's
1483                          * object pager must have the page.
1484                          *
1485                          * If this fails, the parent does not completely shadow
1486                          * the object and we might as well give up now.
1487                          */
1488
1489                         pp = vm_page_lookup(object, new_pindex);
1490                         if (
1491                             (pp == NULL || pp->valid == 0) &&
1492                             !vm_pager_has_page(object, new_pindex, NULL, NULL)
1493                         ) {
1494                                 r = 0;
1495                                 break;
1496                         }
1497                 }
1498
1499                 /*
1500                  * Check for busy page
1501                  */
1502                 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1503                         vm_page_t pp;
1504
1505                         if (op & OBSC_COLLAPSE_NOWAIT) {
1506                                 if (!p->valid || vm_page_busied(p)) {
1507                                         p = next;
1508                                         continue;
1509                                 }
1510                         } else if (op & OBSC_COLLAPSE_WAIT) {
1511                                 if (vm_page_busied(p)) {
1512                                         VM_OBJECT_WUNLOCK(object);
1513                                         vm_page_lock(p);
1514                                         VM_OBJECT_WUNLOCK(backing_object);
1515                                         vm_page_busy_sleep(p, "vmocol");
1516                                         VM_OBJECT_WLOCK(object);
1517                                         VM_OBJECT_WLOCK(backing_object);
1518                                         /*
1519                                          * If we slept, anything could have
1520                                          * happened.  Since the object is
1521                                          * marked dead, the backing offset
1522                                          * should not have changed so we
1523                                          * just restart our scan.
1524                                          */
1525                                         p = TAILQ_FIRST(&backing_object->memq);
1526                                         continue;
1527                                 }
1528                         }
1529
1530                         KASSERT(
1531                             p->object == backing_object,
1532                             ("vm_object_backing_scan: object mismatch")
1533                         );
1534
1535                         if (
1536                             p->pindex < backing_offset_index ||
1537                             new_pindex >= object->size
1538                         ) {
1539                                 if (backing_object->type == OBJT_SWAP)
1540                                         swap_pager_freespace(backing_object,
1541                                             p->pindex, 1);
1542
1543                                 /*
1544                                  * Page is out of the parent object's range, we
1545                                  * can simply destroy it.
1546                                  */
1547                                 vm_page_lock(p);
1548                                 KASSERT(!pmap_page_is_mapped(p),
1549                                     ("freeing mapped page %p", p));
1550                                 if (p->wire_count == 0)
1551                                         vm_page_free(p);
1552                                 else
1553                                         vm_page_remove(p);
1554                                 vm_page_unlock(p);
1555                                 p = next;
1556                                 continue;
1557                         }
1558
1559                         pp = vm_page_lookup(object, new_pindex);
1560                         if (
1561                             (op & OBSC_COLLAPSE_NOWAIT) != 0 &&
1562                             (pp != NULL && pp->valid == 0)
1563                         ) {
1564                                 if (backing_object->type == OBJT_SWAP)
1565                                         swap_pager_freespace(backing_object,
1566                                             p->pindex, 1);
1567
1568                                 /*
1569                                  * The page in the parent is not (yet) valid.
1570                                  * We don't know anything about the state of
1571                                  * the original page.  It might be mapped,
1572                                  * so we must avoid the next if here.
1573                                  *
1574                                  * This is due to a race in vm_fault() where
1575                                  * we must unbusy the original (backing_obj)
1576                                  * page before we can (re)lock the parent.
1577                                  * Hence we can get here.
1578                                  */
1579                                 p = next;
1580                                 continue;
1581                         }
1582                         if (
1583                             pp != NULL ||
1584                             vm_pager_has_page(object, new_pindex, NULL, NULL)
1585                         ) {
1586                                 if (backing_object->type == OBJT_SWAP)
1587                                         swap_pager_freespace(backing_object,
1588                                             p->pindex, 1);
1589
1590                                 /*
1591                                  * page already exists in parent OR swap exists
1592                                  * for this location in the parent.  Destroy
1593                                  * the original page from the backing object.
1594                                  *
1595                                  * Leave the parent's page alone
1596                                  */
1597                                 vm_page_lock(p);
1598                                 KASSERT(!pmap_page_is_mapped(p),
1599                                     ("freeing mapped page %p", p));
1600                                 if (p->wire_count == 0)
1601                                         vm_page_free(p);
1602                                 else
1603                                         vm_page_remove(p);
1604                                 vm_page_unlock(p);
1605                                 p = next;
1606                                 continue;
1607                         }
1608
1609                         /*
1610                          * Page does not exist in parent, rename the
1611                          * page from the backing object to the main object.
1612                          *
1613                          * If the page was mapped to a process, it can remain
1614                          * mapped through the rename.
1615                          * vm_page_rename() will handle dirty and cache.
1616                          */
1617                         if (vm_page_rename(p, object, new_pindex)) {
1618                                 if (op & OBSC_COLLAPSE_NOWAIT) {
1619                                         p = next;
1620                                         continue;
1621                                 }
1622                                 VM_OBJECT_WLOCK(backing_object);
1623                                 VM_OBJECT_WUNLOCK(object);
1624                                 VM_WAIT;
1625                                 VM_OBJECT_WLOCK(object);
1626                                 VM_OBJECT_WLOCK(backing_object);
1627                                 p = TAILQ_FIRST(&backing_object->memq);
1628                                 continue;
1629                         }
1630
1631                         /* Use the old pindex to free the right page. */
1632                         if (backing_object->type == OBJT_SWAP)
1633                                 swap_pager_freespace(backing_object,
1634                                     new_pindex + backing_offset_index, 1);
1635
1636 #if VM_NRESERVLEVEL > 0
1637                         /*
1638                          * Rename the reservation.
1639                          */
1640                         vm_reserv_rename(p, object, backing_object,
1641                             backing_offset_index);
1642 #endif
1643                 }
1644                 p = next;
1645         }
1646         return (r);
1647 }
1648
1649
1650 /*
1651  * this version of collapse allows the operation to occur earlier and
1652  * when paging_in_progress is true for an object...  This is not a complete
1653  * operation, but should plug 99.9% of the rest of the leaks.
1654  */
1655 static void
1656 vm_object_qcollapse(vm_object_t object)
1657 {
1658         vm_object_t backing_object = object->backing_object;
1659
1660         VM_OBJECT_ASSERT_WLOCKED(object);
1661         VM_OBJECT_ASSERT_WLOCKED(backing_object);
1662
1663         if (backing_object->ref_count != 1)
1664                 return;
1665
1666         vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1667 }
1668
1669 /*
1670  *      vm_object_collapse:
1671  *
1672  *      Collapse an object with the object backing it.
1673  *      Pages in the backing object are moved into the
1674  *      parent, and the backing object is deallocated.
1675  */
1676 void
1677 vm_object_collapse(vm_object_t object)
1678 {
1679         VM_OBJECT_ASSERT_WLOCKED(object);
1680
1681         while (TRUE) {
1682                 vm_object_t backing_object;
1683
1684                 /*
1685                  * Verify that the conditions are right for collapse:
1686                  *
1687                  * The object exists and the backing object exists.
1688                  */
1689                 if ((backing_object = object->backing_object) == NULL)
1690                         break;
1691
1692                 /*
1693                  * we check the backing object first, because it is most likely
1694                  * not collapsable.
1695                  */
1696                 VM_OBJECT_WLOCK(backing_object);
1697                 if (backing_object->handle != NULL ||
1698                     (backing_object->type != OBJT_DEFAULT &&
1699                      backing_object->type != OBJT_SWAP) ||
1700                     (backing_object->flags & OBJ_DEAD) ||
1701                     object->handle != NULL ||
1702                     (object->type != OBJT_DEFAULT &&
1703                      object->type != OBJT_SWAP) ||
1704                     (object->flags & OBJ_DEAD)) {
1705                         VM_OBJECT_WUNLOCK(backing_object);
1706                         break;
1707                 }
1708
1709                 if (
1710                     object->paging_in_progress != 0 ||
1711                     backing_object->paging_in_progress != 0
1712                 ) {
1713                         vm_object_qcollapse(object);
1714                         VM_OBJECT_WUNLOCK(backing_object);
1715                         break;
1716                 }
1717                 /*
1718                  * We know that we can either collapse the backing object (if
1719                  * the parent is the only reference to it) or (perhaps) have
1720                  * the parent bypass the object if the parent happens to shadow
1721                  * all the resident pages in the entire backing object.
1722                  *
1723                  * This is ignoring pager-backed pages such as swap pages.
1724                  * vm_object_backing_scan fails the shadowing test in this
1725                  * case.
1726                  */
1727                 if (backing_object->ref_count == 1) {
1728                         /*
1729                          * If there is exactly one reference to the backing
1730                          * object, we can collapse it into the parent.
1731                          */
1732                         vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1733
1734 #if VM_NRESERVLEVEL > 0
1735                         /*
1736                          * Break any reservations from backing_object.
1737                          */
1738                         if (__predict_false(!LIST_EMPTY(&backing_object->rvq)))
1739                                 vm_reserv_break_all(backing_object);
1740 #endif
1741
1742                         /*
1743                          * Move the pager from backing_object to object.
1744                          */
1745                         if (backing_object->type == OBJT_SWAP) {
1746                                 /*
1747                                  * swap_pager_copy() can sleep, in which case
1748                                  * the backing_object's and object's locks are
1749                                  * released and reacquired.
1750                                  * Since swap_pager_copy() is being asked to
1751                                  * destroy the source, it will change the
1752                                  * backing_object's type to OBJT_DEFAULT.
1753                                  */
1754                                 swap_pager_copy(
1755                                     backing_object,
1756                                     object,
1757                                     OFF_TO_IDX(object->backing_object_offset), TRUE);
1758
1759                                 /*
1760                                  * Free any cached pages from backing_object.
1761                                  */
1762                                 if (__predict_false(
1763                                     !vm_object_cache_is_empty(backing_object)))
1764                                         vm_page_cache_free(backing_object, 0, 0);
1765                         }
1766                         /*
1767                          * Object now shadows whatever backing_object did.
1768                          * Note that the reference to
1769                          * backing_object->backing_object moves from within
1770                          * backing_object to within object.
1771                          */
1772                         LIST_REMOVE(object, shadow_list);
1773                         backing_object->shadow_count--;
1774                         if (backing_object->backing_object) {
1775                                 VM_OBJECT_WLOCK(backing_object->backing_object);
1776                                 LIST_REMOVE(backing_object, shadow_list);
1777                                 LIST_INSERT_HEAD(
1778                                     &backing_object->backing_object->shadow_head,
1779                                     object, shadow_list);
1780                                 /*
1781                                  * The shadow_count has not changed.
1782                                  */
1783                                 VM_OBJECT_WUNLOCK(backing_object->backing_object);
1784                         }
1785                         object->backing_object = backing_object->backing_object;
1786                         object->backing_object_offset +=
1787                             backing_object->backing_object_offset;
1788
1789                         /*
1790                          * Discard backing_object.
1791                          *
1792                          * Since the backing object has no pages, no pager left,
1793                          * and no object references within it, all that is
1794                          * necessary is to dispose of it.
1795                          */
1796                         KASSERT(backing_object->ref_count == 1, (
1797 "backing_object %p was somehow re-referenced during collapse!",
1798                             backing_object));
1799                         VM_OBJECT_WUNLOCK(backing_object);
1800                         vm_object_destroy(backing_object);
1801
1802                         object_collapses++;
1803                 } else {
1804                         vm_object_t new_backing_object;
1805
1806                         /*
1807                          * If we do not entirely shadow the backing object,
1808                          * there is nothing we can do so we give up.
1809                          */
1810                         if (object->resident_page_count != object->size &&
1811                             vm_object_backing_scan(object,
1812                             OBSC_TEST_ALL_SHADOWED) == 0) {
1813                                 VM_OBJECT_WUNLOCK(backing_object);
1814                                 break;
1815                         }
1816
1817                         /*
1818                          * Make the parent shadow the next object in the
1819                          * chain.  Deallocating backing_object will not remove
1820                          * it, since its reference count is at least 2.
1821                          */
1822                         LIST_REMOVE(object, shadow_list);
1823                         backing_object->shadow_count--;
1824
1825                         new_backing_object = backing_object->backing_object;
1826                         if ((object->backing_object = new_backing_object) != NULL) {
1827                                 VM_OBJECT_WLOCK(new_backing_object);
1828                                 LIST_INSERT_HEAD(
1829                                     &new_backing_object->shadow_head,
1830                                     object,
1831                                     shadow_list
1832                                 );
1833                                 new_backing_object->shadow_count++;
1834                                 vm_object_reference_locked(new_backing_object);
1835                                 VM_OBJECT_WUNLOCK(new_backing_object);
1836                                 object->backing_object_offset +=
1837                                         backing_object->backing_object_offset;
1838                         }
1839
1840                         /*
1841                          * Drop the reference count on backing_object. Since
1842                          * its ref_count was at least 2, it will not vanish.
1843                          */
1844                         backing_object->ref_count--;
1845                         VM_OBJECT_WUNLOCK(backing_object);
1846                         object_bypasses++;
1847                 }
1848
1849                 /*
1850                  * Try again with this object's new backing object.
1851                  */
1852         }
1853 }
1854
1855 /*
1856  *      vm_object_page_remove:
1857  *
1858  *      For the given object, either frees or invalidates each of the
1859  *      specified pages.  In general, a page is freed.  However, if a page is
1860  *      wired for any reason other than the existence of a managed, wired
1861  *      mapping, then it may be invalidated but not removed from the object.
1862  *      Pages are specified by the given range ["start", "end") and the option
1863  *      OBJPR_CLEANONLY.  As a special case, if "end" is zero, then the range
1864  *      extends from "start" to the end of the object.  If the option
1865  *      OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
1866  *      specified range are affected.  If the option OBJPR_NOTMAPPED is
1867  *      specified, then the pages within the specified range must have no
1868  *      mappings.  Otherwise, if this option is not specified, any mappings to
1869  *      the specified pages are removed before the pages are freed or
1870  *      invalidated.
1871  *
1872  *      In general, this operation should only be performed on objects that
1873  *      contain managed pages.  There are, however, two exceptions.  First, it
1874  *      is performed on the kernel and kmem objects by vm_map_entry_delete().
1875  *      Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
1876  *      backed pages.  In both of these cases, the option OBJPR_CLEANONLY must
1877  *      not be specified and the option OBJPR_NOTMAPPED must be specified.
1878  *
1879  *      The object must be locked.
1880  */
1881 void
1882 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1883     int options)
1884 {
1885         vm_page_t p, next;
1886         int wirings;
1887
1888         VM_OBJECT_ASSERT_WLOCKED(object);
1889         KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
1890             (options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
1891             ("vm_object_page_remove: illegal options for object %p", object));
1892         if (object->resident_page_count == 0)
1893                 goto skipmemq;
1894         vm_object_pip_add(object, 1);
1895 again:
1896         p = vm_page_find_least(object, start);
1897
1898         /*
1899          * Here, the variable "p" is either (1) the page with the least pindex
1900          * greater than or equal to the parameter "start" or (2) NULL.
1901          */
1902         for (; p != NULL && (p->pindex < end || end == 0); p = next) {
1903                 next = TAILQ_NEXT(p, listq);
1904
1905                 /*
1906                  * If the page is wired for any reason besides the existence
1907                  * of managed, wired mappings, then it cannot be freed.  For
1908                  * example, fictitious pages, which represent device memory,
1909                  * are inherently wired and cannot be freed.  They can,
1910                  * however, be invalidated if the option OBJPR_CLEANONLY is
1911                  * not specified.
1912                  */
1913                 vm_page_lock(p);
1914                 if (vm_page_xbusied(p)) {
1915                         VM_OBJECT_WUNLOCK(object);
1916                         vm_page_busy_sleep(p, "vmopax");
1917                         VM_OBJECT_WLOCK(object);
1918                         goto again;
1919                 }
1920                 if ((wirings = p->wire_count) != 0 &&
1921                     (wirings = pmap_page_wired_mappings(p)) != p->wire_count) {
1922                         if ((options & (OBJPR_NOTWIRED | OBJPR_NOTMAPPED)) ==
1923                             0) {
1924                                 pmap_remove_all(p);
1925                                 /* Account for removal of wired mappings. */
1926                                 if (wirings != 0)
1927                                         p->wire_count -= wirings;
1928                         }
1929                         if ((options & OBJPR_CLEANONLY) == 0) {
1930                                 p->valid = 0;
1931                                 vm_page_undirty(p);
1932                         }
1933                         goto next;
1934                 }
1935                 if (vm_page_busied(p)) {
1936                         VM_OBJECT_WUNLOCK(object);
1937                         vm_page_busy_sleep(p, "vmopar");
1938                         VM_OBJECT_WLOCK(object);
1939                         goto again;
1940                 }
1941                 KASSERT((p->flags & PG_FICTITIOUS) == 0,
1942                     ("vm_object_page_remove: page %p is fictitious", p));
1943                 if ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {
1944                         if ((options & OBJPR_NOTMAPPED) == 0)
1945                                 pmap_remove_write(p);
1946                         if (p->dirty)
1947                                 goto next;
1948                 }
1949                 if ((options & OBJPR_NOTMAPPED) == 0) {
1950                         if ((options & OBJPR_NOTWIRED) != 0 && wirings != 0)
1951                                 goto next;
1952                         pmap_remove_all(p);
1953                         /* Account for removal of wired mappings. */
1954                         if (wirings != 0) {
1955                                 KASSERT(p->wire_count == wirings,
1956                                     ("inconsistent wire count %d %d %p",
1957                                     p->wire_count, wirings, p));
1958                                 p->wire_count = 0;
1959                                 atomic_subtract_int(&cnt.v_wire_count, 1);
1960                         }
1961                 }
1962                 vm_page_free(p);
1963 next:
1964                 vm_page_unlock(p);
1965         }
1966         vm_object_pip_wakeup(object);
1967 skipmemq:
1968         if (__predict_false(!vm_object_cache_is_empty(object)))
1969                 vm_page_cache_free(object, start, end);
1970 }
1971
1972 /*
1973  *      vm_object_page_cache:
1974  *
1975  *      For the given object, attempt to move the specified clean
1976  *      pages to the cache queue.  If a page is wired for any reason,
1977  *      then it will not be changed.  Pages are specified by the given
1978  *      range ["start", "end").  As a special case, if "end" is zero,
1979  *      then the range extends from "start" to the end of the object.
1980  *      Any mappings to the specified pages are removed before the
1981  *      pages are moved to the cache queue.
1982  *
1983  *      This operation should only be performed on objects that
1984  *      contain non-fictitious, managed pages.
1985  *
1986  *      The object must be locked.
1987  */
1988 void
1989 vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1990 {
1991         struct mtx *mtx, *new_mtx;
1992         vm_page_t p, next;
1993
1994         VM_OBJECT_ASSERT_WLOCKED(object);
1995         KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
1996             ("vm_object_page_cache: illegal object %p", object));
1997         if (object->resident_page_count == 0)
1998                 return;
1999         p = vm_page_find_least(object, start);
2000
2001         /*
2002          * Here, the variable "p" is either (1) the page with the least pindex
2003          * greater than or equal to the parameter "start" or (2) NULL.
2004          */
2005         mtx = NULL;
2006         for (; p != NULL && (p->pindex < end || end == 0); p = next) {
2007                 next = TAILQ_NEXT(p, listq);
2008
2009                 /*
2010                  * Avoid releasing and reacquiring the same page lock.
2011                  */
2012                 new_mtx = vm_page_lockptr(p);
2013                 if (mtx != new_mtx) {
2014                         if (mtx != NULL)
2015                                 mtx_unlock(mtx);
2016                         mtx = new_mtx;
2017                         mtx_lock(mtx);
2018                 }
2019                 vm_page_try_to_cache(p);
2020         }
2021         if (mtx != NULL)
2022                 mtx_unlock(mtx);
2023 }
2024
2025 /*
2026  *      Populate the specified range of the object with valid pages.  Returns
2027  *      TRUE if the range is successfully populated and FALSE otherwise.
2028  *
2029  *      Note: This function should be optimized to pass a larger array of
2030  *      pages to vm_pager_get_pages() before it is applied to a non-
2031  *      OBJT_DEVICE object.
2032  *
2033  *      The object must be locked.
2034  */
2035 boolean_t
2036 vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
2037 {
2038         vm_page_t m, ma[1];
2039         vm_pindex_t pindex;
2040         int rv;
2041
2042         VM_OBJECT_ASSERT_WLOCKED(object);
2043         for (pindex = start; pindex < end; pindex++) {
2044                 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
2045                 if (m->valid != VM_PAGE_BITS_ALL) {
2046                         ma[0] = m;
2047                         rv = vm_pager_get_pages(object, ma, 1, 0);
2048                         m = vm_page_lookup(object, pindex);
2049                         if (m == NULL)
2050                                 break;
2051                         if (rv != VM_PAGER_OK) {
2052                                 vm_page_lock(m);
2053                                 vm_page_free(m);
2054                                 vm_page_unlock(m);
2055                                 break;
2056                         }
2057                 }
2058                 /*
2059                  * Keep "m" busy because a subsequent iteration may unlock
2060                  * the object.
2061                  */
2062         }
2063         if (pindex > start) {
2064                 m = vm_page_lookup(object, start);
2065                 while (m != NULL && m->pindex < pindex) {
2066                         vm_page_xunbusy(m);
2067                         m = TAILQ_NEXT(m, listq);
2068                 }
2069         }
2070         return (pindex == end);
2071 }
2072
2073 /*
2074  *      Routine:        vm_object_coalesce
2075  *      Function:       Coalesces two objects backing up adjoining
2076  *                      regions of memory into a single object.
2077  *
2078  *      returns TRUE if objects were combined.
2079  *
2080  *      NOTE:   Only works at the moment if the second object is NULL -
2081  *              if it's not, which object do we lock first?
2082  *
2083  *      Parameters:
2084  *              prev_object     First object to coalesce
2085  *              prev_offset     Offset into prev_object
2086  *              prev_size       Size of reference to prev_object
2087  *              next_size       Size of reference to the second object
2088  *              reserved        Indicator that extension region has
2089  *                              swap accounted for
2090  *
2091  *      Conditions:
2092  *      The object must *not* be locked.
2093  */
2094 boolean_t
2095 vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
2096     vm_size_t prev_size, vm_size_t next_size, boolean_t reserved)
2097 {
2098         vm_pindex_t next_pindex;
2099
2100         if (prev_object == NULL)
2101                 return (TRUE);
2102         VM_OBJECT_WLOCK(prev_object);
2103         if ((prev_object->type != OBJT_DEFAULT &&
2104             prev_object->type != OBJT_SWAP) ||
2105             (prev_object->flags & OBJ_TMPFS) != 0) {
2106                 VM_OBJECT_WUNLOCK(prev_object);
2107                 return (FALSE);
2108         }
2109
2110         /*
2111          * Try to collapse the object first
2112          */
2113         vm_object_collapse(prev_object);
2114
2115         /*
2116          * Can't coalesce if: . more than one reference . paged out . shadows
2117          * another object . has a copy elsewhere (any of which mean that the
2118          * pages not mapped to prev_entry may be in use anyway)
2119          */
2120         if (prev_object->backing_object != NULL) {
2121                 VM_OBJECT_WUNLOCK(prev_object);
2122                 return (FALSE);
2123         }
2124
2125         prev_size >>= PAGE_SHIFT;
2126         next_size >>= PAGE_SHIFT;
2127         next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
2128
2129         if ((prev_object->ref_count > 1) &&
2130             (prev_object->size != next_pindex)) {
2131                 VM_OBJECT_WUNLOCK(prev_object);
2132                 return (FALSE);
2133         }
2134
2135         /*
2136          * Account for the charge.
2137          */
2138         if (prev_object->cred != NULL) {
2139
2140                 /*
2141                  * If prev_object was charged, then this mapping,
2142                  * althought not charged now, may become writable
2143                  * later. Non-NULL cred in the object would prevent
2144                  * swap reservation during enabling of the write
2145                  * access, so reserve swap now. Failed reservation
2146                  * cause allocation of the separate object for the map
2147                  * entry, and swap reservation for this entry is
2148                  * managed in appropriate time.
2149                  */
2150                 if (!reserved && !swap_reserve_by_cred(ptoa(next_size),
2151                     prev_object->cred)) {
2152                         return (FALSE);
2153                 }
2154                 prev_object->charge += ptoa(next_size);
2155         }
2156
2157         /*
2158          * Remove any pages that may still be in the object from a previous
2159          * deallocation.
2160          */
2161         if (next_pindex < prev_object->size) {
2162                 vm_object_page_remove(prev_object, next_pindex, next_pindex +
2163                     next_size, 0);
2164                 if (prev_object->type == OBJT_SWAP)
2165                         swap_pager_freespace(prev_object,
2166                                              next_pindex, next_size);
2167 #if 0
2168                 if (prev_object->cred != NULL) {
2169                         KASSERT(prev_object->charge >=
2170                             ptoa(prev_object->size - next_pindex),
2171                             ("object %p overcharged 1 %jx %jx", prev_object,
2172                                 (uintmax_t)next_pindex, (uintmax_t)next_size));
2173                         prev_object->charge -= ptoa(prev_object->size -
2174                             next_pindex);
2175                 }
2176 #endif
2177         }
2178
2179         /*
2180          * Extend the object if necessary.
2181          */
2182         if (next_pindex + next_size > prev_object->size)
2183                 prev_object->size = next_pindex + next_size;
2184
2185         VM_OBJECT_WUNLOCK(prev_object);
2186         return (TRUE);
2187 }
2188
2189 void
2190 vm_object_set_writeable_dirty(vm_object_t object)
2191 {
2192
2193         VM_OBJECT_ASSERT_WLOCKED(object);
2194         if (object->type != OBJT_VNODE)
2195                 return;
2196         object->generation++;
2197         if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
2198                 return;
2199         vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
2200 }
2201
2202 #include "opt_ddb.h"
2203 #ifdef DDB
2204 #include <sys/kernel.h>
2205
2206 #include <sys/cons.h>
2207
2208 #include <ddb/ddb.h>
2209
2210 static int
2211 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
2212 {
2213         vm_map_t tmpm;
2214         vm_map_entry_t tmpe;
2215         vm_object_t obj;
2216         int entcount;
2217
2218         if (map == 0)
2219                 return 0;
2220
2221         if (entry == 0) {
2222                 tmpe = map->header.next;
2223                 entcount = map->nentries;
2224                 while (entcount-- && (tmpe != &map->header)) {
2225                         if (_vm_object_in_map(map, object, tmpe)) {
2226                                 return 1;
2227                         }
2228                         tmpe = tmpe->next;
2229                 }
2230         } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
2231                 tmpm = entry->object.sub_map;
2232                 tmpe = tmpm->header.next;
2233                 entcount = tmpm->nentries;
2234                 while (entcount-- && tmpe != &tmpm->header) {
2235                         if (_vm_object_in_map(tmpm, object, tmpe)) {
2236                                 return 1;
2237                         }
2238                         tmpe = tmpe->next;
2239                 }
2240         } else if ((obj = entry->object.vm_object) != NULL) {
2241                 for (; obj; obj = obj->backing_object)
2242                         if (obj == object) {
2243                                 return 1;
2244                         }
2245         }
2246         return 0;
2247 }
2248
2249 static int
2250 vm_object_in_map(vm_object_t object)
2251 {
2252         struct proc *p;
2253
2254         /* sx_slock(&allproc_lock); */
2255         FOREACH_PROC_IN_SYSTEM(p) {
2256                 if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
2257                         continue;
2258                 if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
2259                         /* sx_sunlock(&allproc_lock); */
2260                         return 1;
2261                 }
2262         }
2263         /* sx_sunlock(&allproc_lock); */
2264         if (_vm_object_in_map(kernel_map, object, 0))
2265                 return 1;
2266         return 0;
2267 }
2268
2269 DB_SHOW_COMMAND(vmochk, vm_object_check)
2270 {
2271         vm_object_t object;
2272
2273         /*
2274          * make sure that internal objs are in a map somewhere
2275          * and none have zero ref counts.
2276          */
2277         TAILQ_FOREACH(object, &vm_object_list, object_list) {
2278                 if (object->handle == NULL &&
2279                     (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
2280                         if (object->ref_count == 0) {
2281                                 db_printf("vmochk: internal obj has zero ref count: %ld\n",
2282                                         (long)object->size);
2283                         }
2284                         if (!vm_object_in_map(object)) {
2285                                 db_printf(
2286                         "vmochk: internal obj is not in a map: "
2287                         "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
2288                                     object->ref_count, (u_long)object->size,
2289                                     (u_long)object->size,
2290                                     (void *)object->backing_object);
2291                         }
2292                 }
2293         }
2294 }
2295
2296 /*
2297  *      vm_object_print:        [ debug ]
2298  */
2299 DB_SHOW_COMMAND(object, vm_object_print_static)
2300 {
2301         /* XXX convert args. */
2302         vm_object_t object = (vm_object_t)addr;
2303         boolean_t full = have_addr;
2304
2305         vm_page_t p;
2306
2307         /* XXX count is an (unused) arg.  Avoid shadowing it. */
2308 #define count   was_count
2309
2310         int count;
2311
2312         if (object == NULL)
2313                 return;
2314
2315         db_iprintf(
2316             "Object %p: type=%d, size=0x%jx, res=%d, ref=%d, flags=0x%x ruid %d charge %jx\n",
2317             object, (int)object->type, (uintmax_t)object->size,
2318             object->resident_page_count, object->ref_count, object->flags,
2319             object->cred ? object->cred->cr_ruid : -1, (uintmax_t)object->charge);
2320         db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%jx\n",
2321             object->shadow_count,
2322             object->backing_object ? object->backing_object->ref_count : 0,
2323             object->backing_object, (uintmax_t)object->backing_object_offset);
2324
2325         if (!full)
2326                 return;
2327
2328         db_indent += 2;
2329         count = 0;
2330         TAILQ_FOREACH(p, &object->memq, listq) {
2331                 if (count == 0)
2332                         db_iprintf("memory:=");
2333                 else if (count == 6) {
2334                         db_printf("\n");
2335                         db_iprintf(" ...");
2336                         count = 0;
2337                 } else
2338                         db_printf(",");
2339                 count++;
2340
2341                 db_printf("(off=0x%jx,page=0x%jx)",
2342                     (uintmax_t)p->pindex, (uintmax_t)VM_PAGE_TO_PHYS(p));
2343         }
2344         if (count != 0)
2345                 db_printf("\n");
2346         db_indent -= 2;
2347 }
2348
2349 /* XXX. */
2350 #undef count
2351
2352 /* XXX need this non-static entry for calling from vm_map_print. */
2353 void
2354 vm_object_print(
2355         /* db_expr_t */ long addr,
2356         boolean_t have_addr,
2357         /* db_expr_t */ long count,
2358         char *modif)
2359 {
2360         vm_object_print_static(addr, have_addr, count, modif);
2361 }
2362
2363 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
2364 {
2365         vm_object_t object;
2366         vm_pindex_t fidx;
2367         vm_paddr_t pa;
2368         vm_page_t m, prev_m;
2369         int rcount, nl, c;
2370
2371         nl = 0;
2372         TAILQ_FOREACH(object, &vm_object_list, object_list) {
2373                 db_printf("new object: %p\n", (void *)object);
2374                 if (nl > 18) {
2375                         c = cngetc();
2376                         if (c != ' ')
2377                                 return;
2378                         nl = 0;
2379                 }
2380                 nl++;
2381                 rcount = 0;
2382                 fidx = 0;
2383                 pa = -1;
2384                 TAILQ_FOREACH(m, &object->memq, listq) {
2385                         if (m->pindex > 128)
2386                                 break;
2387                         if ((prev_m = TAILQ_PREV(m, pglist, listq)) != NULL &&
2388                             prev_m->pindex + 1 != m->pindex) {
2389                                 if (rcount) {
2390                                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2391                                                 (long)fidx, rcount, (long)pa);
2392                                         if (nl > 18) {
2393                                                 c = cngetc();
2394                                                 if (c != ' ')
2395                                                         return;
2396                                                 nl = 0;
2397                                         }
2398                                         nl++;
2399                                         rcount = 0;
2400                                 }
2401                         }
2402                         if (rcount &&
2403                                 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
2404                                 ++rcount;
2405                                 continue;
2406                         }
2407                         if (rcount) {
2408                                 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2409                                         (long)fidx, rcount, (long)pa);
2410                                 if (nl > 18) {
2411                                         c = cngetc();
2412                                         if (c != ' ')
2413                                                 return;
2414                                         nl = 0;
2415                                 }
2416                                 nl++;
2417                         }
2418                         fidx = m->pindex;
2419                         pa = VM_PAGE_TO_PHYS(m);
2420                         rcount = 1;
2421                 }
2422                 if (rcount) {
2423                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2424                                 (long)fidx, rcount, (long)pa);
2425                         if (nl > 18) {
2426                                 c = cngetc();
2427                                 if (c != ' ')
2428                                         return;
2429                                 nl = 0;
2430                         }
2431                         nl++;
2432                 }
2433         }
2434 }
2435 #endif /* DDB */