The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_object.c

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    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/user.h>
   83 #include <sys/vnode.h>
   84 #include <sys/vmmeter.h>
   85 #include <sys/sx.h>
   86 
   87 #include <vm/vm.h>
   88 #include <vm/vm_param.h>
   89 #include <vm/pmap.h>
   90 #include <vm/vm_map.h>
   91 #include <vm/vm_object.h>
   92 #include <vm/vm_page.h>
   93 #include <vm/vm_pageout.h>
   94 #include <vm/vm_pager.h>
   95 #include <vm/swap_pager.h>
   96 #include <vm/vm_kern.h>
   97 #include <vm/vm_extern.h>
   98 #include <vm/vm_radix.h>
   99 #include <vm/vm_reserv.h>
  100 #include <vm/uma.h>
  101 
  102 static int old_msync;
  103 SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
  104     "Use old (insecure) msync behavior");
  105 
  106 static int      vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
  107                     int pagerflags, int flags, boolean_t *clearobjflags,
  108                     boolean_t *eio);
  109 static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
  110                     boolean_t *clearobjflags);
  111 static void     vm_object_qcollapse(vm_object_t object);
  112 static void     vm_object_vndeallocate(vm_object_t object);
  113 
  114 /*
  115  *      Virtual memory objects maintain the actual data
  116  *      associated with allocated virtual memory.  A given
  117  *      page of memory exists within exactly one object.
  118  *
  119  *      An object is only deallocated when all "references"
  120  *      are given up.  Only one "reference" to a given
  121  *      region of an object should be writeable.
  122  *
  123  *      Associated with each object is a list of all resident
  124  *      memory pages belonging to that object; this list is
  125  *      maintained by the "vm_page" module, and locked by the object's
  126  *      lock.
  127  *
  128  *      Each object also records a "pager" routine which is
  129  *      used to retrieve (and store) pages to the proper backing
  130  *      storage.  In addition, objects may be backed by other
  131  *      objects from which they were virtual-copied.
  132  *
  133  *      The only items within the object structure which are
  134  *      modified after time of creation are:
  135  *              reference count         locked by object's lock
  136  *              pager routine           locked by object's lock
  137  *
  138  */
  139 
  140 struct object_q vm_object_list;
  141 struct mtx vm_object_list_mtx;  /* lock for object list and count */
  142 
  143 struct vm_object kernel_object_store;
  144 struct vm_object kmem_object_store;
  145 
  146 static SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD, 0,
  147     "VM object stats");
  148 
  149 static long object_collapses;
  150 SYSCTL_LONG(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
  151     &object_collapses, 0, "VM object collapses");
  152 
  153 static long object_bypasses;
  154 SYSCTL_LONG(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
  155     &object_bypasses, 0, "VM object bypasses");
  156 
  157 static uma_zone_t obj_zone;
  158 
  159 static int vm_object_zinit(void *mem, int size, int flags);
  160 
  161 #ifdef INVARIANTS
  162 static void vm_object_zdtor(void *mem, int size, void *arg);
  163 
  164 static void
  165 vm_object_zdtor(void *mem, int size, void *arg)
  166 {
  167         vm_object_t object;
  168 
  169         object = (vm_object_t)mem;
  170         KASSERT(object->ref_count == 0,
  171             ("object %p ref_count = %d", object, object->ref_count));
  172         KASSERT(TAILQ_EMPTY(&object->memq),
  173             ("object %p has resident pages in its memq", object));
  174         KASSERT(vm_radix_is_empty(&object->rtree),
  175             ("object %p has resident pages in its trie", object));
  176 #if VM_NRESERVLEVEL > 0
  177         KASSERT(LIST_EMPTY(&object->rvq),
  178             ("object %p has reservations",
  179             object));
  180 #endif
  181         KASSERT(vm_object_cache_is_empty(object),
  182             ("object %p has cached pages",
  183             object));
  184         KASSERT(object->paging_in_progress == 0,
  185             ("object %p paging_in_progress = %d",
  186             object, object->paging_in_progress));
  187         KASSERT(object->resident_page_count == 0,
  188             ("object %p resident_page_count = %d",
  189             object, object->resident_page_count));
  190         KASSERT(object->shadow_count == 0,
  191             ("object %p shadow_count = %d",
  192             object, object->shadow_count));
  193         KASSERT(object->type == OBJT_DEAD,
  194             ("object %p has non-dead type %d",
  195             object, object->type));
  196 }
  197 #endif
  198 
  199 static int
  200 vm_object_zinit(void *mem, int size, int flags)
  201 {
  202         vm_object_t object;
  203 
  204         object = (vm_object_t)mem;
  205         bzero(&object->lock, sizeof(object->lock));
  206         rw_init_flags(&object->lock, "vm object", RW_DUPOK);
  207 
  208         /* These are true for any object that has been freed */
  209         object->type = OBJT_DEAD;
  210         object->ref_count = 0;
  211         object->rtree.rt_root = 0;
  212         object->rtree.rt_flags = 0;
  213         object->paging_in_progress = 0;
  214         object->resident_page_count = 0;
  215         object->shadow_count = 0;
  216         object->cache.rt_root = 0;
  217         object->cache.rt_flags = 0;
  218 
  219         mtx_lock(&vm_object_list_mtx);
  220         TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
  221         mtx_unlock(&vm_object_list_mtx);
  222         return (0);
  223 }
  224 
  225 static void
  226 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
  227 {
  228 
  229         TAILQ_INIT(&object->memq);
  230         LIST_INIT(&object->shadow_head);
  231 
  232         object->type = type;
  233         switch (type) {
  234         case OBJT_DEAD:
  235                 panic("_vm_object_allocate: can't create OBJT_DEAD");
  236         case OBJT_DEFAULT:
  237         case OBJT_SWAP:
  238                 object->flags = OBJ_ONEMAPPING;
  239                 break;
  240         case OBJT_DEVICE:
  241         case OBJT_SG:
  242                 object->flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
  243                 break;
  244         case OBJT_MGTDEVICE:
  245                 object->flags = OBJ_FICTITIOUS;
  246                 break;
  247         case OBJT_PHYS:
  248                 object->flags = OBJ_UNMANAGED;
  249                 break;
  250         case OBJT_VNODE:
  251                 object->flags = 0;
  252                 break;
  253         default:
  254                 panic("_vm_object_allocate: type %d is undefined", type);
  255         }
  256         object->size = size;
  257         object->generation = 1;
  258         object->ref_count = 1;
  259         object->memattr = VM_MEMATTR_DEFAULT;
  260         object->cred = NULL;
  261         object->charge = 0;
  262         object->handle = NULL;
  263         object->backing_object = NULL;
  264         object->backing_object_offset = (vm_ooffset_t) 0;
  265 #if VM_NRESERVLEVEL > 0
  266         LIST_INIT(&object->rvq);
  267 #endif
  268 }
  269 
  270 /*
  271  *      vm_object_init:
  272  *
  273  *      Initialize the VM objects module.
  274  */
  275 void
  276 vm_object_init(void)
  277 {
  278         TAILQ_INIT(&vm_object_list);
  279         mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
  280         
  281         rw_init(&kernel_object->lock, "kernel vm object");
  282         _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
  283             kernel_object);
  284 #if VM_NRESERVLEVEL > 0
  285         kernel_object->flags |= OBJ_COLORED;
  286         kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
  287 #endif
  288 
  289         rw_init(&kmem_object->lock, "kmem vm object");
  290         _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
  291             kmem_object);
  292 #if VM_NRESERVLEVEL > 0
  293         kmem_object->flags |= OBJ_COLORED;
  294         kmem_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
  295 #endif
  296 
  297         /*
  298          * The lock portion of struct vm_object must be type stable due
  299          * to vm_pageout_fallback_object_lock locking a vm object
  300          * without holding any references to it.
  301          */
  302         obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
  303 #ifdef INVARIANTS
  304             vm_object_zdtor,
  305 #else
  306             NULL,
  307 #endif
  308             vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  309 
  310         vm_radix_init();
  311 }
  312 
  313 void
  314 vm_object_clear_flag(vm_object_t object, u_short bits)
  315 {
  316 
  317         VM_OBJECT_ASSERT_WLOCKED(object);
  318         object->flags &= ~bits;
  319 }
  320 
  321 /*
  322  *      Sets the default memory attribute for the specified object.  Pages
  323  *      that are allocated to this object are by default assigned this memory
  324  *      attribute.
  325  *
  326  *      Presently, this function must be called before any pages are allocated
  327  *      to the object.  In the future, this requirement may be relaxed for
  328  *      "default" and "swap" objects.
  329  */
  330 int
  331 vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
  332 {
  333 
  334         VM_OBJECT_ASSERT_WLOCKED(object);
  335         switch (object->type) {
  336         case OBJT_DEFAULT:
  337         case OBJT_DEVICE:
  338         case OBJT_MGTDEVICE:
  339         case OBJT_PHYS:
  340         case OBJT_SG:
  341         case OBJT_SWAP:
  342         case OBJT_VNODE:
  343                 if (!TAILQ_EMPTY(&object->memq))
  344                         return (KERN_FAILURE);
  345                 break;
  346         case OBJT_DEAD:
  347                 return (KERN_INVALID_ARGUMENT);
  348         default:
  349                 panic("vm_object_set_memattr: object %p is of undefined type",
  350                     object);
  351         }
  352         object->memattr = memattr;
  353         return (KERN_SUCCESS);
  354 }
  355 
  356 void
  357 vm_object_pip_add(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_subtract(vm_object_t object, short i)
  366 {
  367 
  368         VM_OBJECT_ASSERT_WLOCKED(object);
  369         object->paging_in_progress -= i;
  370 }
  371 
  372 void
  373 vm_object_pip_wakeup(vm_object_t object)
  374 {
  375 
  376         VM_OBJECT_ASSERT_WLOCKED(object);
  377         object->paging_in_progress--;
  378         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
  379                 vm_object_clear_flag(object, OBJ_PIPWNT);
  380                 wakeup(object);
  381         }
  382 }
  383 
  384 void
  385 vm_object_pip_wakeupn(vm_object_t object, short i)
  386 {
  387 
  388         VM_OBJECT_ASSERT_WLOCKED(object);
  389         if (i)
  390                 object->paging_in_progress -= i;
  391         if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
  392                 vm_object_clear_flag(object, OBJ_PIPWNT);
  393                 wakeup(object);
  394         }
  395 }
  396 
  397 void
  398 vm_object_pip_wait(vm_object_t object, char *waitid)
  399 {
  400 
  401         VM_OBJECT_ASSERT_WLOCKED(object);
  402         while (object->paging_in_progress) {
  403                 object->flags |= OBJ_PIPWNT;
  404                 VM_OBJECT_SLEEP(object, object, PVM, waitid, 0);
  405         }
  406 }
  407 
  408 /*
  409  *      vm_object_allocate:
  410  *
  411  *      Returns a new object with the given size.
  412  */
  413 vm_object_t
  414 vm_object_allocate(objtype_t type, vm_pindex_t size)
  415 {
  416         vm_object_t object;
  417 
  418         object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
  419         _vm_object_allocate(type, size, object);
  420         return (object);
  421 }
  422 
  423 
  424 /*
  425  *      vm_object_reference:
  426  *
  427  *      Gets another reference to the given object.  Note: OBJ_DEAD
  428  *      objects can be referenced during final cleaning.
  429  */
  430 void
  431 vm_object_reference(vm_object_t object)
  432 {
  433         if (object == NULL)
  434                 return;
  435         VM_OBJECT_WLOCK(object);
  436         vm_object_reference_locked(object);
  437         VM_OBJECT_WUNLOCK(object);
  438 }
  439 
  440 /*
  441  *      vm_object_reference_locked:
  442  *
  443  *      Gets another reference to the given object.
  444  *
  445  *      The object must be locked.
  446  */
  447 void
  448 vm_object_reference_locked(vm_object_t object)
  449 {
  450         struct vnode *vp;
  451 
  452         VM_OBJECT_ASSERT_WLOCKED(object);
  453         object->ref_count++;
  454         if (object->type == OBJT_VNODE) {
  455                 vp = object->handle;
  456                 vref(vp);
  457         }
  458 }
  459 
  460 /*
  461  * Handle deallocating an object of type OBJT_VNODE.
  462  */
  463 static void
  464 vm_object_vndeallocate(vm_object_t object)
  465 {
  466         struct vnode *vp = (struct vnode *) object->handle;
  467 
  468         VM_OBJECT_ASSERT_WLOCKED(object);
  469         KASSERT(object->type == OBJT_VNODE,
  470             ("vm_object_vndeallocate: not a vnode object"));
  471         KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
  472 #ifdef INVARIANTS
  473         if (object->ref_count == 0) {
  474                 vprint("vm_object_vndeallocate", vp);
  475                 panic("vm_object_vndeallocate: bad object reference count");
  476         }
  477 #endif
  478 
  479         /*
  480          * The test for text of vp vnode does not need a bypass to
  481          * reach right VV_TEXT there, since it is obtained from
  482          * object->handle.
  483          */
  484         if (object->ref_count > 1 || (vp->v_vflag & VV_TEXT) == 0) {
  485                 object->ref_count--;
  486                 VM_OBJECT_WUNLOCK(object);
  487                 /* vrele may need the vnode lock. */
  488                 vrele(vp);
  489         } else {
  490                 vhold(vp);
  491                 VM_OBJECT_WUNLOCK(object);
  492                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  493                 vdrop(vp);
  494                 VM_OBJECT_WLOCK(object);
  495                 object->ref_count--;
  496                 if (object->type == OBJT_DEAD) {
  497                         VM_OBJECT_WUNLOCK(object);
  498                         VOP_UNLOCK(vp, 0);
  499                 } else {
  500                         if (object->ref_count == 0)
  501                                 VOP_UNSET_TEXT(vp);
  502                         VM_OBJECT_WUNLOCK(object);
  503                         vput(vp);
  504                 }
  505         }
  506 }
  507 
  508 /*
  509  *      vm_object_deallocate:
  510  *
  511  *      Release a reference to the specified object,
  512  *      gained either through a vm_object_allocate
  513  *      or a vm_object_reference call.  When all references
  514  *      are gone, storage associated with this object
  515  *      may be relinquished.
  516  *
  517  *      No object may be locked.
  518  */
  519 void
  520 vm_object_deallocate(vm_object_t object)
  521 {
  522         vm_object_t temp;
  523         struct vnode *vp;
  524 
  525         while (object != NULL) {
  526                 VM_OBJECT_WLOCK(object);
  527                 if (object->type == OBJT_VNODE) {
  528                         vm_object_vndeallocate(object);
  529                         return;
  530                 }
  531 
  532                 KASSERT(object->ref_count != 0,
  533                         ("vm_object_deallocate: object deallocated too many times: %d", object->type));
  534 
  535                 /*
  536                  * If the reference count goes to 0 we start calling
  537                  * vm_object_terminate() on the object chain.
  538                  * A ref count of 1 may be a special case depending on the
  539                  * shadow count being 0 or 1.
  540                  */
  541                 object->ref_count--;
  542                 if (object->ref_count > 1) {
  543                         VM_OBJECT_WUNLOCK(object);
  544                         return;
  545                 } else if (object->ref_count == 1) {
  546                         if (object->type == OBJT_SWAP &&
  547                             (object->flags & OBJ_TMPFS) != 0) {
  548                                 vp = object->un_pager.swp.swp_tmpfs;
  549                                 vhold(vp);
  550                                 VM_OBJECT_WUNLOCK(object);
  551                                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  552                                 VM_OBJECT_WLOCK(object);
  553                                 if (object->type == OBJT_DEAD ||
  554                                     object->ref_count != 1) {
  555                                         VM_OBJECT_WUNLOCK(object);
  556                                         VOP_UNLOCK(vp, 0);
  557                                         vdrop(vp);
  558                                         return;
  559                                 }
  560                                 if ((object->flags & OBJ_TMPFS) != 0)
  561                                         VOP_UNSET_TEXT(vp);
  562                                 VOP_UNLOCK(vp, 0);
  563                                 vdrop(vp);
  564                         }
  565                         if (object->shadow_count == 0 &&
  566                             object->handle == NULL &&
  567                             (object->type == OBJT_DEFAULT ||
  568                             (object->type == OBJT_SWAP &&
  569                             (object->flags & OBJ_TMPFS_NODE) == 0))) {
  570                                 vm_object_set_flag(object, OBJ_ONEMAPPING);
  571                         } else if ((object->shadow_count == 1) &&
  572                             (object->handle == NULL) &&
  573                             (object->type == OBJT_DEFAULT ||
  574                              object->type == OBJT_SWAP)) {
  575                                 vm_object_t robject;
  576 
  577                                 robject = LIST_FIRST(&object->shadow_head);
  578                                 KASSERT(robject != NULL,
  579                                     ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
  580                                          object->ref_count,
  581                                          object->shadow_count));
  582                                 KASSERT((robject->flags & OBJ_TMPFS_NODE) == 0,
  583                                     ("shadowed tmpfs v_object %p", object));
  584                                 if (!VM_OBJECT_TRYWLOCK(robject)) {
  585                                         /*
  586                                          * Avoid a potential deadlock.
  587                                          */
  588                                         object->ref_count++;
  589                                         VM_OBJECT_WUNLOCK(object);
  590                                         /*
  591                                          * More likely than not the thread
  592                                          * holding robject's lock has lower
  593                                          * priority than the current thread.
  594                                          * Let the lower priority thread run.
  595                                          */
  596                                         pause("vmo_de", 1);
  597                                         continue;
  598                                 }
  599                                 /*
  600                                  * Collapse object into its shadow unless its
  601                                  * shadow is dead.  In that case, object will
  602                                  * be deallocated by the thread that is
  603                                  * deallocating its shadow.
  604                                  */
  605                                 if ((robject->flags & OBJ_DEAD) == 0 &&
  606                                     (robject->handle == NULL) &&
  607                                     (robject->type == OBJT_DEFAULT ||
  608                                      robject->type == OBJT_SWAP)) {
  609 
  610                                         robject->ref_count++;
  611 retry:
  612                                         if (robject->paging_in_progress) {
  613                                                 VM_OBJECT_WUNLOCK(object);
  614                                                 vm_object_pip_wait(robject,
  615                                                     "objde1");
  616                                                 temp = robject->backing_object;
  617                                                 if (object == temp) {
  618                                                         VM_OBJECT_WLOCK(object);
  619                                                         goto retry;
  620                                                 }
  621                                         } else if (object->paging_in_progress) {
  622                                                 VM_OBJECT_WUNLOCK(robject);
  623                                                 object->flags |= OBJ_PIPWNT;
  624                                                 VM_OBJECT_SLEEP(object, object,
  625                                                     PDROP | PVM, "objde2", 0);
  626                                                 VM_OBJECT_WLOCK(robject);
  627                                                 temp = robject->backing_object;
  628                                                 if (object == temp) {
  629                                                         VM_OBJECT_WLOCK(object);
  630                                                         goto retry;
  631                                                 }
  632                                         } else
  633                                                 VM_OBJECT_WUNLOCK(object);
  634 
  635                                         if (robject->ref_count == 1) {
  636                                                 robject->ref_count--;
  637                                                 object = robject;
  638                                                 goto doterm;
  639                                         }
  640                                         object = robject;
  641                                         vm_object_collapse(object);
  642                                         VM_OBJECT_WUNLOCK(object);
  643                                         continue;
  644                                 }
  645                                 VM_OBJECT_WUNLOCK(robject);
  646                         }
  647                         VM_OBJECT_WUNLOCK(object);
  648                         return;
  649                 }
  650 doterm:
  651                 temp = object->backing_object;
  652                 if (temp != NULL) {
  653                         KASSERT((object->flags & OBJ_TMPFS_NODE) == 0,
  654                             ("shadowed tmpfs v_object 2 %p", object));
  655                         VM_OBJECT_WLOCK(temp);
  656                         LIST_REMOVE(object, shadow_list);
  657                         temp->shadow_count--;
  658                         VM_OBJECT_WUNLOCK(temp);
  659                         object->backing_object = NULL;
  660                 }
  661                 /*
  662                  * Don't double-terminate, we could be in a termination
  663                  * recursion due to the terminate having to sync data
  664                  * to disk.
  665                  */
  666                 if ((object->flags & OBJ_DEAD) == 0)
  667                         vm_object_terminate(object);
  668                 else
  669                         VM_OBJECT_WUNLOCK(object);
  670                 object = temp;
  671         }
  672 }
  673 
  674 /*
  675  *      vm_object_destroy removes the object from the global object list
  676  *      and frees the space for the object.
  677  */
  678 void
  679 vm_object_destroy(vm_object_t object)
  680 {
  681 
  682         /*
  683          * Release the allocation charge.
  684          */
  685         if (object->cred != NULL) {
  686                 swap_release_by_cred(object->charge, object->cred);
  687                 object->charge = 0;
  688                 crfree(object->cred);
  689                 object->cred = NULL;
  690         }
  691 
  692         /*
  693          * Free the space for the object.
  694          */
  695         uma_zfree(obj_zone, object);
  696 }
  697 
  698 /*
  699  *      vm_object_terminate actually destroys the specified object, freeing
  700  *      up all previously used resources.
  701  *
  702  *      The object must be locked.
  703  *      This routine may block.
  704  */
  705 void
  706 vm_object_terminate(vm_object_t object)
  707 {
  708         vm_page_t p, p_next;
  709 
  710         VM_OBJECT_ASSERT_WLOCKED(object);
  711 
  712         /*
  713          * Make sure no one uses us.
  714          */
  715         vm_object_set_flag(object, OBJ_DEAD);
  716 
  717         /*
  718          * wait for the pageout daemon to be done with the object
  719          */
  720         vm_object_pip_wait(object, "objtrm");
  721 
  722         KASSERT(!object->paging_in_progress,
  723                 ("vm_object_terminate: pageout in progress"));
  724 
  725         /*
  726          * Clean and free the pages, as appropriate. All references to the
  727          * object are gone, so we don't need to lock it.
  728          */
  729         if (object->type == OBJT_VNODE) {
  730                 struct vnode *vp = (struct vnode *)object->handle;
  731 
  732                 /*
  733                  * Clean pages and flush buffers.
  734                  */
  735                 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
  736                 VM_OBJECT_WUNLOCK(object);
  737 
  738                 vinvalbuf(vp, V_SAVE, 0, 0);
  739 
  740                 BO_LOCK(&vp->v_bufobj);
  741                 vp->v_bufobj.bo_flag |= BO_DEAD;
  742                 BO_UNLOCK(&vp->v_bufobj);
  743 
  744                 VM_OBJECT_WLOCK(object);
  745         }
  746 
  747         KASSERT(object->ref_count == 0, 
  748                 ("vm_object_terminate: object with references, ref_count=%d",
  749                 object->ref_count));
  750 
  751         /*
  752          * Free any remaining pageable pages.  This also removes them from the
  753          * paging queues.  However, don't free wired pages, just remove them
  754          * from the object.  Rather than incrementally removing each page from
  755          * the object, the page and object are reset to any empty state. 
  756          */
  757         TAILQ_FOREACH_SAFE(p, &object->memq, listq, p_next) {
  758                 vm_page_assert_unbusied(p);
  759                 vm_page_lock(p);
  760                 /*
  761                  * Optimize the page's removal from the object by resetting
  762                  * its "object" field.  Specifically, if the page is not
  763                  * wired, then the effect of this assignment is that
  764                  * vm_page_free()'s call to vm_page_remove() will return
  765                  * immediately without modifying the page or the object.
  766                  */ 
  767                 p->object = NULL;
  768                 if (p->wire_count == 0) {
  769                         vm_page_free(p);
  770                         PCPU_INC(cnt.v_pfree);
  771                 }
  772                 vm_page_unlock(p);
  773         }
  774         /*
  775          * If the object contained any pages, then reset it to an empty state.
  776          * None of the object's fields, including "resident_page_count", were
  777          * modified by the preceding loop.
  778          */
  779         if (object->resident_page_count != 0) {
  780                 vm_radix_reclaim_allnodes(&object->rtree);
  781                 TAILQ_INIT(&object->memq);
  782                 object->resident_page_count = 0;
  783                 if (object->type == OBJT_VNODE)
  784                         vdrop(object->handle);
  785         }
  786 
  787 #if VM_NRESERVLEVEL > 0
  788         if (__predict_false(!LIST_EMPTY(&object->rvq)))
  789                 vm_reserv_break_all(object);
  790 #endif
  791         if (__predict_false(!vm_object_cache_is_empty(object)))
  792                 vm_page_cache_free(object, 0, 0);
  793 
  794         KASSERT(object->cred == NULL || object->type == OBJT_DEFAULT ||
  795             object->type == OBJT_SWAP,
  796             ("%s: non-swap obj %p has cred", __func__, object));
  797 
  798         /*
  799          * Let the pager know object is dead.
  800          */
  801         vm_pager_deallocate(object);
  802         VM_OBJECT_WUNLOCK(object);
  803 
  804         vm_object_destroy(object);
  805 }
  806 
  807 /*
  808  * Make the page read-only so that we can clear the object flags.  However, if
  809  * this is a nosync mmap then the object is likely to stay dirty so do not
  810  * mess with the page and do not clear the object flags.  Returns TRUE if the
  811  * page should be flushed, and FALSE otherwise.
  812  */
  813 static boolean_t
  814 vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *clearobjflags)
  815 {
  816 
  817         /*
  818          * If we have been asked to skip nosync pages and this is a
  819          * nosync page, skip it.  Note that the object flags were not
  820          * cleared in this case so we do not have to set them.
  821          */
  822         if ((flags & OBJPC_NOSYNC) != 0 && (p->oflags & VPO_NOSYNC) != 0) {
  823                 *clearobjflags = FALSE;
  824                 return (FALSE);
  825         } else {
  826                 pmap_remove_write(p);
  827                 return (p->dirty != 0);
  828         }
  829 }
  830 
  831 /*
  832  *      vm_object_page_clean
  833  *
  834  *      Clean all dirty pages in the specified range of object.  Leaves page 
  835  *      on whatever queue it is currently on.   If NOSYNC is set then do not
  836  *      write out pages with VPO_NOSYNC set (originally comes from MAP_NOSYNC),
  837  *      leaving the object dirty.
  838  *
  839  *      When stuffing pages asynchronously, allow clustering.  XXX we need a
  840  *      synchronous clustering mode implementation.
  841  *
  842  *      Odd semantics: if start == end, we clean everything.
  843  *
  844  *      The object must be locked.
  845  *
  846  *      Returns FALSE if some page from the range was not written, as
  847  *      reported by the pager, and TRUE otherwise.
  848  */
  849 boolean_t
  850 vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
  851     int flags)
  852 {
  853         vm_page_t np, p;
  854         vm_pindex_t pi, tend, tstart;
  855         int curgeneration, n, pagerflags;
  856         boolean_t clearobjflags, eio, res;
  857 
  858         VM_OBJECT_ASSERT_WLOCKED(object);
  859 
  860         /*
  861          * The OBJ_MIGHTBEDIRTY flag is only set for OBJT_VNODE
  862          * objects.  The check below prevents the function from
  863          * operating on non-vnode objects.
  864          */
  865         if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
  866             object->resident_page_count == 0)
  867                 return (TRUE);
  868 
  869         pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
  870             VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
  871         pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
  872 
  873         tstart = OFF_TO_IDX(start);
  874         tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
  875         clearobjflags = tstart == 0 && tend >= object->size;
  876         res = TRUE;
  877 
  878 rescan:
  879         curgeneration = object->generation;
  880 
  881         for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
  882                 pi = p->pindex;
  883                 if (pi >= tend)
  884                         break;
  885                 np = TAILQ_NEXT(p, listq);
  886                 if (p->valid == 0)
  887                         continue;
  888                 if (vm_page_sleep_if_busy(p, "vpcwai")) {
  889                         if (object->generation != curgeneration) {
  890                                 if ((flags & OBJPC_SYNC) != 0)
  891                                         goto rescan;
  892                                 else
  893                                         clearobjflags = FALSE;
  894                         }
  895                         np = vm_page_find_least(object, pi);
  896                         continue;
  897                 }
  898                 if (!vm_object_page_remove_write(p, flags, &clearobjflags))
  899                         continue;
  900 
  901                 n = vm_object_page_collect_flush(object, p, pagerflags,
  902                     flags, &clearobjflags, &eio);
  903                 if (eio) {
  904                         res = FALSE;
  905                         clearobjflags = FALSE;
  906                 }
  907                 if (object->generation != curgeneration) {
  908                         if ((flags & OBJPC_SYNC) != 0)
  909                                 goto rescan;
  910                         else
  911                                 clearobjflags = FALSE;
  912                 }
  913 
  914                 /*
  915                  * If the VOP_PUTPAGES() did a truncated write, so
  916                  * that even the first page of the run is not fully
  917                  * written, vm_pageout_flush() returns 0 as the run
  918                  * length.  Since the condition that caused truncated
  919                  * write may be permanent, e.g. exhausted free space,
  920                  * accepting n == 0 would cause an infinite loop.
  921                  *
  922                  * Forwarding the iterator leaves the unwritten page
  923                  * behind, but there is not much we can do there if
  924                  * filesystem refuses to write it.
  925                  */
  926                 if (n == 0) {
  927                         n = 1;
  928                         clearobjflags = FALSE;
  929                 }
  930                 np = vm_page_find_least(object, pi + n);
  931         }
  932 #if 0
  933         VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
  934 #endif
  935 
  936         if (clearobjflags)
  937                 vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
  938         return (res);
  939 }
  940 
  941 static int
  942 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
  943     int flags, boolean_t *clearobjflags, boolean_t *eio)
  944 {
  945         vm_page_t ma[vm_pageout_page_count], p_first, tp;
  946         int count, i, mreq, runlen;
  947 
  948         vm_page_lock_assert(p, MA_NOTOWNED);
  949         VM_OBJECT_ASSERT_WLOCKED(object);
  950 
  951         count = 1;
  952         mreq = 0;
  953 
  954         for (tp = p; count < vm_pageout_page_count; count++) {
  955                 tp = vm_page_next(tp);
  956                 if (tp == NULL || vm_page_busied(tp))
  957                         break;
  958                 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
  959                         break;
  960         }
  961 
  962         for (p_first = p; count < vm_pageout_page_count; count++) {
  963                 tp = vm_page_prev(p_first);
  964                 if (tp == NULL || vm_page_busied(tp))
  965                         break;
  966                 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
  967                         break;
  968                 p_first = tp;
  969                 mreq++;
  970         }
  971 
  972         for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
  973                 ma[i] = tp;
  974 
  975         vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
  976         return (runlen);
  977 }
  978 
  979 /*
  980  * Note that there is absolutely no sense in writing out
  981  * anonymous objects, so we track down the vnode object
  982  * to write out.
  983  * We invalidate (remove) all pages from the address space
  984  * for semantic correctness.
  985  *
  986  * If the backing object is a device object with unmanaged pages, then any
  987  * mappings to the specified range of pages must be removed before this
  988  * function is called.
  989  *
  990  * Note: certain anonymous maps, such as MAP_NOSYNC maps,
  991  * may start out with a NULL object.
  992  */
  993 boolean_t
  994 vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
  995     boolean_t syncio, boolean_t invalidate)
  996 {
  997         vm_object_t backing_object;
  998         struct vnode *vp;
  999         struct mount *mp;
 1000         int error, flags, fsync_after;
 1001         boolean_t res;
 1002 
 1003         if (object == NULL)
 1004                 return (TRUE);
 1005         res = TRUE;
 1006         error = 0;
 1007         VM_OBJECT_WLOCK(object);
 1008         while ((backing_object = object->backing_object) != NULL) {
 1009                 VM_OBJECT_WLOCK(backing_object);
 1010                 offset += object->backing_object_offset;
 1011                 VM_OBJECT_WUNLOCK(object);
 1012                 object = backing_object;
 1013                 if (object->size < OFF_TO_IDX(offset + size))
 1014                         size = IDX_TO_OFF(object->size) - offset;
 1015         }
 1016         /*
 1017          * Flush pages if writing is allowed, invalidate them
 1018          * if invalidation requested.  Pages undergoing I/O
 1019          * will be ignored by vm_object_page_remove().
 1020          *
 1021          * We cannot lock the vnode and then wait for paging
 1022          * to complete without deadlocking against vm_fault.
 1023          * Instead we simply call vm_object_page_remove() and
 1024          * allow it to block internally on a page-by-page
 1025          * basis when it encounters pages undergoing async
 1026          * I/O.
 1027          */
 1028         if (object->type == OBJT_VNODE &&
 1029             (object->flags & OBJ_MIGHTBEDIRTY) != 0) {
 1030                 vp = object->handle;
 1031                 VM_OBJECT_WUNLOCK(object);
 1032                 (void) vn_start_write(vp, &mp, V_WAIT);
 1033                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1034                 if (syncio && !invalidate && offset == 0 &&
 1035                     OFF_TO_IDX(size) == object->size) {
 1036                         /*
 1037                          * If syncing the whole mapping of the file,
 1038                          * it is faster to schedule all the writes in
 1039                          * async mode, also allowing the clustering,
 1040                          * and then wait for i/o to complete.
 1041                          */
 1042                         flags = 0;
 1043                         fsync_after = TRUE;
 1044                 } else {
 1045                         flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
 1046                         flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
 1047                         fsync_after = FALSE;
 1048                 }
 1049                 VM_OBJECT_WLOCK(object);
 1050                 res = vm_object_page_clean(object, offset, offset + size,
 1051                     flags);
 1052                 VM_OBJECT_WUNLOCK(object);
 1053                 if (fsync_after)
 1054                         error = VOP_FSYNC(vp, MNT_WAIT, curthread);
 1055                 VOP_UNLOCK(vp, 0);
 1056                 vn_finished_write(mp);
 1057                 if (error != 0)
 1058                         res = FALSE;
 1059                 VM_OBJECT_WLOCK(object);
 1060         }
 1061         if ((object->type == OBJT_VNODE ||
 1062              object->type == OBJT_DEVICE) && invalidate) {
 1063                 if (object->type == OBJT_DEVICE)
 1064                         /*
 1065                          * The option OBJPR_NOTMAPPED must be passed here
 1066                          * because vm_object_page_remove() cannot remove
 1067                          * unmanaged mappings.
 1068                          */
 1069                         flags = OBJPR_NOTMAPPED;
 1070                 else if (old_msync)
 1071                         flags = 0;
 1072                 else
 1073                         flags = OBJPR_CLEANONLY;
 1074                 vm_object_page_remove(object, OFF_TO_IDX(offset),
 1075                     OFF_TO_IDX(offset + size + PAGE_MASK), flags);
 1076         }
 1077         VM_OBJECT_WUNLOCK(object);
 1078         return (res);
 1079 }
 1080 
 1081 /*
 1082  *      vm_object_madvise:
 1083  *
 1084  *      Implements the madvise function at the object/page level.
 1085  *
 1086  *      MADV_WILLNEED   (any object)
 1087  *
 1088  *          Activate the specified pages if they are resident.
 1089  *
 1090  *      MADV_DONTNEED   (any object)
 1091  *
 1092  *          Deactivate the specified pages if they are resident.
 1093  *
 1094  *      MADV_FREE       (OBJT_DEFAULT/OBJT_SWAP objects,
 1095  *                       OBJ_ONEMAPPING only)
 1096  *
 1097  *          Deactivate and clean the specified pages if they are
 1098  *          resident.  This permits the process to reuse the pages
 1099  *          without faulting or the kernel to reclaim the pages
 1100  *          without I/O.
 1101  */
 1102 void
 1103 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
 1104     int advise)
 1105 {
 1106         vm_pindex_t tpindex;
 1107         vm_object_t backing_object, tobject;
 1108         vm_page_t m;
 1109 
 1110         if (object == NULL)
 1111                 return;
 1112         VM_OBJECT_WLOCK(object);
 1113         /*
 1114          * Locate and adjust resident pages
 1115          */
 1116         for (; pindex < end; pindex += 1) {
 1117 relookup:
 1118                 tobject = object;
 1119                 tpindex = pindex;
 1120 shadowlookup:
 1121                 /*
 1122                  * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
 1123                  * and those pages must be OBJ_ONEMAPPING.
 1124                  */
 1125                 if (advise == MADV_FREE) {
 1126                         if ((tobject->type != OBJT_DEFAULT &&
 1127                              tobject->type != OBJT_SWAP) ||
 1128                             (tobject->flags & OBJ_ONEMAPPING) == 0) {
 1129                                 goto unlock_tobject;
 1130                         }
 1131                 } else if ((tobject->flags & OBJ_UNMANAGED) != 0)
 1132                         goto unlock_tobject;
 1133                 m = vm_page_lookup(tobject, tpindex);
 1134                 if (m == NULL && advise == MADV_WILLNEED) {
 1135                         /*
 1136                          * If the page is cached, reactivate it.
 1137                          */
 1138                         m = vm_page_alloc(tobject, tpindex, VM_ALLOC_IFCACHED |
 1139                             VM_ALLOC_NOBUSY);
 1140                 }
 1141                 if (m == NULL) {
 1142                         /*
 1143                          * There may be swap even if there is no backing page
 1144                          */
 1145                         if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
 1146                                 swap_pager_freespace(tobject, tpindex, 1);
 1147                         /*
 1148                          * next object
 1149                          */
 1150                         backing_object = tobject->backing_object;
 1151                         if (backing_object == NULL)
 1152                                 goto unlock_tobject;
 1153                         VM_OBJECT_WLOCK(backing_object);
 1154                         tpindex += OFF_TO_IDX(tobject->backing_object_offset);
 1155                         if (tobject != object)
 1156                                 VM_OBJECT_WUNLOCK(tobject);
 1157                         tobject = backing_object;
 1158                         goto shadowlookup;
 1159                 } else if (m->valid != VM_PAGE_BITS_ALL)
 1160                         goto unlock_tobject;
 1161                 /*
 1162                  * If the page is not in a normal state, skip it.
 1163                  */
 1164                 vm_page_lock(m);
 1165                 if (m->hold_count != 0 || m->wire_count != 0) {
 1166                         vm_page_unlock(m);
 1167                         goto unlock_tobject;
 1168                 }
 1169                 KASSERT((m->flags & PG_FICTITIOUS) == 0,
 1170                     ("vm_object_madvise: page %p is fictitious", m));
 1171                 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
 1172                     ("vm_object_madvise: page %p is not managed", m));
 1173                 if (vm_page_busied(m)) {
 1174                         if (advise == MADV_WILLNEED) {
 1175                                 /*
 1176                                  * Reference the page before unlocking and
 1177                                  * sleeping so that the page daemon is less
 1178                                  * likely to reclaim it. 
 1179                                  */
 1180                                 vm_page_aflag_set(m, PGA_REFERENCED);
 1181                         }
 1182                         if (object != tobject)
 1183                                 VM_OBJECT_WUNLOCK(object);
 1184                         VM_OBJECT_WUNLOCK(tobject);
 1185                         vm_page_busy_sleep(m, "madvpo", false);
 1186                         VM_OBJECT_WLOCK(object);
 1187                         goto relookup;
 1188                 }
 1189                 if (advise == MADV_WILLNEED) {
 1190                         vm_page_activate(m);
 1191                 } else {
 1192                         vm_page_advise(m, advise);
 1193                 }
 1194                 vm_page_unlock(m);
 1195                 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
 1196                         swap_pager_freespace(tobject, tpindex, 1);
 1197 unlock_tobject:
 1198                 if (tobject != object)
 1199                         VM_OBJECT_WUNLOCK(tobject);
 1200         }       
 1201         VM_OBJECT_WUNLOCK(object);
 1202 }
 1203 
 1204 /*
 1205  *      vm_object_shadow:
 1206  *
 1207  *      Create a new object which is backed by the
 1208  *      specified existing object range.  The source
 1209  *      object reference is deallocated.
 1210  *
 1211  *      The new object and offset into that object
 1212  *      are returned in the source parameters.
 1213  */
 1214 void
 1215 vm_object_shadow(
 1216         vm_object_t *object,    /* IN/OUT */
 1217         vm_ooffset_t *offset,   /* IN/OUT */
 1218         vm_size_t length)
 1219 {
 1220         vm_object_t source;
 1221         vm_object_t result;
 1222 
 1223         source = *object;
 1224 
 1225         /*
 1226          * Don't create the new object if the old object isn't shared.
 1227          */
 1228         if (source != NULL) {
 1229                 VM_OBJECT_WLOCK(source);
 1230                 if (source->ref_count == 1 &&
 1231                     source->handle == NULL &&
 1232                     (source->type == OBJT_DEFAULT ||
 1233                      source->type == OBJT_SWAP)) {
 1234                         VM_OBJECT_WUNLOCK(source);
 1235                         return;
 1236                 }
 1237                 VM_OBJECT_WUNLOCK(source);
 1238         }
 1239 
 1240         /*
 1241          * Allocate a new object with the given length.
 1242          */
 1243         result = vm_object_allocate(OBJT_DEFAULT, atop(length));
 1244 
 1245         /*
 1246          * The new object shadows the source object, adding a reference to it.
 1247          * Our caller changes his reference to point to the new object,
 1248          * removing a reference to the source object.  Net result: no change
 1249          * of reference count.
 1250          *
 1251          * Try to optimize the result object's page color when shadowing
 1252          * in order to maintain page coloring consistency in the combined 
 1253          * shadowed object.
 1254          */
 1255         result->backing_object = source;
 1256         /*
 1257          * Store the offset into the source object, and fix up the offset into
 1258          * the new object.
 1259          */
 1260         result->backing_object_offset = *offset;
 1261         if (source != NULL) {
 1262                 VM_OBJECT_WLOCK(source);
 1263                 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
 1264                 source->shadow_count++;
 1265 #if VM_NRESERVLEVEL > 0
 1266                 result->flags |= source->flags & OBJ_COLORED;
 1267                 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
 1268                     ((1 << (VM_NFREEORDER - 1)) - 1);
 1269 #endif
 1270                 VM_OBJECT_WUNLOCK(source);
 1271         }
 1272 
 1273 
 1274         /*
 1275          * Return the new things
 1276          */
 1277         *offset = 0;
 1278         *object = result;
 1279 }
 1280 
 1281 /*
 1282  *      vm_object_split:
 1283  *
 1284  * Split the pages in a map entry into a new object.  This affords
 1285  * easier removal of unused pages, and keeps object inheritance from
 1286  * being a negative impact on memory usage.
 1287  */
 1288 void
 1289 vm_object_split(vm_map_entry_t entry)
 1290 {
 1291         vm_page_t m, m_next;
 1292         vm_object_t orig_object, new_object, source;
 1293         vm_pindex_t idx, offidxstart;
 1294         vm_size_t size;
 1295 
 1296         orig_object = entry->object.vm_object;
 1297         if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
 1298                 return;
 1299         if (orig_object->ref_count <= 1)
 1300                 return;
 1301         VM_OBJECT_WUNLOCK(orig_object);
 1302 
 1303         offidxstart = OFF_TO_IDX(entry->offset);
 1304         size = atop(entry->end - entry->start);
 1305 
 1306         /*
 1307          * If swap_pager_copy() is later called, it will convert new_object
 1308          * into a swap object.
 1309          */
 1310         new_object = vm_object_allocate(OBJT_DEFAULT, size);
 1311 
 1312         /*
 1313          * At this point, the new object is still private, so the order in
 1314          * which the original and new objects are locked does not matter.
 1315          */
 1316         VM_OBJECT_WLOCK(new_object);
 1317         VM_OBJECT_WLOCK(orig_object);
 1318         source = orig_object->backing_object;
 1319         if (source != NULL) {
 1320                 VM_OBJECT_WLOCK(source);
 1321                 if ((source->flags & OBJ_DEAD) != 0) {
 1322                         VM_OBJECT_WUNLOCK(source);
 1323                         VM_OBJECT_WUNLOCK(orig_object);
 1324                         VM_OBJECT_WUNLOCK(new_object);
 1325                         vm_object_deallocate(new_object);
 1326                         VM_OBJECT_WLOCK(orig_object);
 1327                         return;
 1328                 }
 1329                 LIST_INSERT_HEAD(&source->shadow_head,
 1330                                   new_object, shadow_list);
 1331                 source->shadow_count++;
 1332                 vm_object_reference_locked(source);     /* for new_object */
 1333                 vm_object_clear_flag(source, OBJ_ONEMAPPING);
 1334                 VM_OBJECT_WUNLOCK(source);
 1335                 new_object->backing_object_offset = 
 1336                         orig_object->backing_object_offset + entry->offset;
 1337                 new_object->backing_object = source;
 1338         }
 1339         if (orig_object->cred != NULL) {
 1340                 new_object->cred = orig_object->cred;
 1341                 crhold(orig_object->cred);
 1342                 new_object->charge = ptoa(size);
 1343                 KASSERT(orig_object->charge >= ptoa(size),
 1344                     ("orig_object->charge < 0"));
 1345                 orig_object->charge -= ptoa(size);
 1346         }
 1347 retry:
 1348         m = vm_page_find_least(orig_object, offidxstart);
 1349         for (; m != NULL && (idx = m->pindex - offidxstart) < size;
 1350             m = m_next) {
 1351                 m_next = TAILQ_NEXT(m, listq);
 1352 
 1353                 /*
 1354                  * We must wait for pending I/O to complete before we can
 1355                  * rename the page.
 1356                  *
 1357                  * We do not have to VM_PROT_NONE the page as mappings should
 1358                  * not be changed by this operation.
 1359                  */
 1360                 if (vm_page_busied(m)) {
 1361                         VM_OBJECT_WUNLOCK(new_object);
 1362                         vm_page_lock(m);
 1363                         VM_OBJECT_WUNLOCK(orig_object);
 1364                         vm_page_busy_sleep(m, "spltwt", false);
 1365                         VM_OBJECT_WLOCK(orig_object);
 1366                         VM_OBJECT_WLOCK(new_object);
 1367                         goto retry;
 1368                 }
 1369 
 1370                 /* vm_page_rename() will handle dirty and cache. */
 1371                 if (vm_page_rename(m, new_object, idx)) {
 1372                         VM_OBJECT_WUNLOCK(new_object);
 1373                         VM_OBJECT_WUNLOCK(orig_object);
 1374                         VM_WAIT;
 1375                         VM_OBJECT_WLOCK(orig_object);
 1376                         VM_OBJECT_WLOCK(new_object);
 1377                         goto retry;
 1378                 }
 1379 #if VM_NRESERVLEVEL > 0
 1380                 /*
 1381                  * If some of the reservation's allocated pages remain with
 1382                  * the original object, then transferring the reservation to
 1383                  * the new object is neither particularly beneficial nor
 1384                  * particularly harmful as compared to leaving the reservation
 1385                  * with the original object.  If, however, all of the
 1386                  * reservation's allocated pages are transferred to the new
 1387                  * object, then transferring the reservation is typically
 1388                  * beneficial.  Determining which of these two cases applies
 1389                  * would be more costly than unconditionally renaming the
 1390                  * reservation.
 1391                  */
 1392                 vm_reserv_rename(m, new_object, orig_object, offidxstart);
 1393 #endif
 1394                 if (orig_object->type == OBJT_SWAP)
 1395                         vm_page_xbusy(m);
 1396         }
 1397         if (orig_object->type == OBJT_SWAP) {
 1398                 /*
 1399                  * swap_pager_copy() can sleep, in which case the orig_object's
 1400                  * and new_object's locks are released and reacquired. 
 1401                  */
 1402                 swap_pager_copy(orig_object, new_object, offidxstart, 0);
 1403                 TAILQ_FOREACH(m, &new_object->memq, listq)
 1404                         vm_page_xunbusy(m);
 1405 
 1406                 /*
 1407                  * Transfer any cached pages from orig_object to new_object.
 1408                  * If swap_pager_copy() found swapped out pages within the
 1409                  * specified range of orig_object, then it changed
 1410                  * new_object's type to OBJT_SWAP when it transferred those
 1411                  * pages to new_object.  Otherwise, new_object's type
 1412                  * should still be OBJT_DEFAULT and orig_object should not
 1413                  * contain any cached pages within the specified range.
 1414                  */
 1415                 if (__predict_false(!vm_object_cache_is_empty(orig_object)))
 1416                         vm_page_cache_transfer(orig_object, offidxstart,
 1417                             new_object);
 1418         }
 1419         VM_OBJECT_WUNLOCK(orig_object);
 1420         VM_OBJECT_WUNLOCK(new_object);
 1421         entry->object.vm_object = new_object;
 1422         entry->offset = 0LL;
 1423         vm_object_deallocate(orig_object);
 1424         VM_OBJECT_WLOCK(new_object);
 1425 }
 1426 
 1427 #define OBSC_TEST_ALL_SHADOWED  0x0001
 1428 #define OBSC_COLLAPSE_NOWAIT    0x0002
 1429 #define OBSC_COLLAPSE_WAIT      0x0004
 1430 
 1431 static vm_page_t
 1432 vm_object_backing_scan_wait(vm_object_t object, vm_page_t p, vm_page_t next,
 1433     int op)
 1434 {
 1435         vm_object_t backing_object;
 1436 
 1437         VM_OBJECT_ASSERT_WLOCKED(object);
 1438         backing_object = object->backing_object;
 1439         VM_OBJECT_ASSERT_WLOCKED(backing_object);
 1440 
 1441         KASSERT(p == NULL || vm_page_busied(p), ("unbusy page %p", p));
 1442         KASSERT(p == NULL || p->object == object || p->object == backing_object,
 1443             ("invalid ownership %p %p %p", p, object, backing_object));
 1444         if ((op & OBSC_COLLAPSE_NOWAIT) != 0)
 1445                 return (next);
 1446         if (p != NULL)
 1447                 vm_page_lock(p);
 1448         VM_OBJECT_WUNLOCK(object);
 1449         VM_OBJECT_WUNLOCK(backing_object);
 1450         if (p == NULL)
 1451                 VM_WAIT;
 1452         else
 1453                 vm_page_busy_sleep(p, "vmocol", false);
 1454         VM_OBJECT_WLOCK(object);
 1455         VM_OBJECT_WLOCK(backing_object);
 1456         return (TAILQ_FIRST(&backing_object->memq));
 1457 }
 1458 
 1459 static bool
 1460 vm_object_backing_scan(vm_object_t object, int op)
 1461 {
 1462         vm_object_t backing_object;
 1463         vm_page_t next, p, pp;
 1464         vm_pindex_t backing_offset_index, new_pindex;
 1465 
 1466         VM_OBJECT_ASSERT_WLOCKED(object);
 1467         VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
 1468 
 1469         backing_object = object->backing_object;
 1470         backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
 1471 
 1472         /*
 1473          * Initial conditions
 1474          */
 1475         if (op & OBSC_TEST_ALL_SHADOWED) {
 1476                 /*
 1477                  * We do not want to have to test for the existence of cache
 1478                  * or swap pages in the backing object.  XXX but with the
 1479                  * new swapper this would be pretty easy to do.
 1480                  *
 1481                  * XXX what about anonymous MAP_SHARED memory that hasn't
 1482                  * been ZFOD faulted yet?  If we do not test for this, the
 1483                  * shadow test may succeed! XXX
 1484                  */
 1485                 if (backing_object->type != OBJT_DEFAULT) {
 1486                         return (false);
 1487                 }
 1488         }
 1489         if (op & OBSC_COLLAPSE_WAIT) {
 1490                 vm_object_set_flag(backing_object, OBJ_DEAD);
 1491         }
 1492 
 1493         /*
 1494          * Our scan
 1495          */
 1496         p = TAILQ_FIRST(&backing_object->memq);
 1497         while (p) {
 1498                 next = TAILQ_NEXT(p, listq);
 1499                 new_pindex = p->pindex - backing_offset_index;
 1500                 if (op & OBSC_TEST_ALL_SHADOWED) {
 1501                         /*
 1502                          * Ignore pages outside the parent object's range
 1503                          * and outside the parent object's mapping of the 
 1504                          * backing object.
 1505                          *
 1506                          * Note that we do not busy the backing object's
 1507                          * page.
 1508                          */
 1509                         if (p->pindex < backing_offset_index ||
 1510                             new_pindex >= object->size) {
 1511                                 p = next;
 1512                                 continue;
 1513                         }
 1514 
 1515                         /*
 1516                          * See if the parent has the page or if the parent's
 1517                          * object pager has the page.  If the parent has the
 1518                          * page but the page is not valid, the parent's
 1519                          * object pager must have the page.
 1520                          *
 1521                          * If this fails, the parent does not completely shadow
 1522                          * the object and we might as well give up now.
 1523                          */
 1524 
 1525                         pp = vm_page_lookup(object, new_pindex);
 1526                         if ((pp == NULL || pp->valid == 0) &&
 1527                             !vm_pager_has_page(object, new_pindex, NULL, NULL))
 1528                                 return (false);
 1529                 }
 1530 
 1531                 /*
 1532                  * Check for busy page
 1533                  */
 1534                 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
 1535                         if (vm_page_busied(p)) {
 1536                                 p = vm_object_backing_scan_wait(object, p,
 1537                                     next, op);
 1538                                 continue;
 1539                         }
 1540 
 1541                         KASSERT(p->object == backing_object,
 1542                             ("vm_object_backing_scan: object mismatch"));
 1543 
 1544                         if (p->pindex < backing_offset_index ||
 1545                             new_pindex >= object->size) {
 1546                                 if (backing_object->type == OBJT_SWAP)
 1547                                         swap_pager_freespace(backing_object, 
 1548                                             p->pindex, 1);
 1549 
 1550                                 /*
 1551                                  * Page is out of the parent object's range, we 
 1552                                  * can simply destroy it. 
 1553                                  */
 1554                                 vm_page_lock(p);
 1555                                 KASSERT(!pmap_page_is_mapped(p),
 1556                                     ("freeing mapped page %p", p));
 1557                                 if (p->wire_count == 0)
 1558                                         vm_page_free(p);
 1559                                 else
 1560                                         vm_page_remove(p);
 1561                                 vm_page_unlock(p);
 1562                                 p = next;
 1563                                 continue;
 1564                         }
 1565 
 1566                         pp = vm_page_lookup(object, new_pindex);
 1567                         if (pp != NULL && vm_page_busied(pp)) {
 1568                                 /*
 1569                                  * The page in the parent is busy and
 1570                                  * possibly not (yet) valid.  Until
 1571                                  * its state is finalized by the busy
 1572                                  * bit owner, we can't tell whether it
 1573                                  * shadows the original page.
 1574                                  * Therefore, we must either skip it
 1575                                  * and the original (backing_object)
 1576                                  * page or wait for its state to be
 1577                                  * finalized.
 1578                                  *
 1579                                  * This is due to a race with vm_fault()
 1580                                  * where we must unbusy the original
 1581                                  * (backing_obj) page before we can
 1582                                  * (re)lock the parent.  Hence we can
 1583                                  * get here.
 1584                                  */
 1585                                 p = vm_object_backing_scan_wait(object, pp,
 1586                                     next, op);
 1587                                 continue;
 1588                         }
 1589 
 1590                         KASSERT(pp == NULL || pp->valid != 0,
 1591                             ("unbusy invalid page %p", pp));
 1592 
 1593                         if (pp != NULL || vm_pager_has_page(object,
 1594                             new_pindex, NULL, NULL)) {
 1595                                 /*
 1596                                  * The page already exists in the
 1597                                  * parent OR swap exists for this
 1598                                  * location in the parent.  Leave the
 1599                                  * parent's page alone.  Destroy the
 1600                                  * original page from the backing
 1601                                  * object.
 1602                                  */
 1603                                 if (backing_object->type == OBJT_SWAP)
 1604                                         swap_pager_freespace(backing_object,
 1605                                             p->pindex, 1);
 1606                                 vm_page_lock(p);
 1607                                 KASSERT(!pmap_page_is_mapped(p),
 1608                                     ("freeing mapped page %p", p));
 1609                                 if (p->wire_count == 0)
 1610                                         vm_page_free(p);
 1611                                 else
 1612                                         vm_page_remove(p);
 1613                                 vm_page_unlock(p);
 1614                                 p = next;
 1615                                 continue;
 1616                         }
 1617 
 1618                         /*
 1619                          * Page does not exist in parent, rename the
 1620                          * page from the backing object to the main object. 
 1621                          *
 1622                          * If the page was mapped to a process, it can remain 
 1623                          * mapped through the rename.
 1624                          * vm_page_rename() will handle dirty and cache.
 1625                          */
 1626                         if (vm_page_rename(p, object, new_pindex)) {
 1627                                 p = vm_object_backing_scan_wait(object, NULL,
 1628                                     next, op);
 1629                                 continue;
 1630                         }
 1631 
 1632                         /* Use the old pindex to free the right page. */
 1633                         if (backing_object->type == OBJT_SWAP)
 1634                                 swap_pager_freespace(backing_object,
 1635                                     new_pindex + backing_offset_index, 1);
 1636 
 1637 #if VM_NRESERVLEVEL > 0
 1638                         /*
 1639                          * Rename the reservation.
 1640                          */
 1641                         vm_reserv_rename(p, object, backing_object,
 1642                             backing_offset_index);
 1643 #endif
 1644                 }
 1645                 p = next;
 1646         }
 1647         return (true);
 1648 }
 1649 
 1650 
 1651 /*
 1652  * this version of collapse allows the operation to occur earlier and
 1653  * when paging_in_progress is true for an object...  This is not a complete
 1654  * operation, but should plug 99.9% of the rest of the leaks.
 1655  */
 1656 static void
 1657 vm_object_qcollapse(vm_object_t object)
 1658 {
 1659         vm_object_t backing_object = object->backing_object;
 1660 
 1661         VM_OBJECT_ASSERT_WLOCKED(object);
 1662         VM_OBJECT_ASSERT_WLOCKED(backing_object);
 1663 
 1664         if (backing_object->ref_count != 1)
 1665                 return;
 1666 
 1667         vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
 1668 }
 1669 
 1670 /*
 1671  *      vm_object_collapse:
 1672  *
 1673  *      Collapse an object with the object backing it.
 1674  *      Pages in the backing object are moved into the
 1675  *      parent, and the backing object is deallocated.
 1676  */
 1677 void
 1678 vm_object_collapse(vm_object_t object)
 1679 {
 1680         vm_object_t backing_object, new_backing_object;
 1681 
 1682         VM_OBJECT_ASSERT_WLOCKED(object);
 1683 
 1684         while (TRUE) {
 1685                 /*
 1686                  * Verify that the conditions are right for collapse:
 1687                  *
 1688                  * The object exists and the backing object exists.
 1689                  */
 1690                 if ((backing_object = object->backing_object) == NULL)
 1691                         break;
 1692 
 1693                 /*
 1694                  * we check the backing object first, because it is most likely
 1695                  * not collapsable.
 1696                  */
 1697                 VM_OBJECT_WLOCK(backing_object);
 1698                 if (backing_object->handle != NULL ||
 1699                     (backing_object->type != OBJT_DEFAULT &&
 1700                      backing_object->type != OBJT_SWAP) ||
 1701                     (backing_object->flags & OBJ_DEAD) ||
 1702                     object->handle != NULL ||
 1703                     (object->type != OBJT_DEFAULT &&
 1704                      object->type != OBJT_SWAP) ||
 1705                     (object->flags & OBJ_DEAD)) {
 1706                         VM_OBJECT_WUNLOCK(backing_object);
 1707                         break;
 1708                 }
 1709 
 1710                 if (object->paging_in_progress != 0 ||
 1711                     backing_object->paging_in_progress != 0) {
 1712                         vm_object_qcollapse(object);
 1713                         VM_OBJECT_WUNLOCK(backing_object);
 1714                         break;
 1715                 }
 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                         vm_object_pip_add(object, 1);
 1729                         vm_object_pip_add(backing_object, 1);
 1730 
 1731                         /*
 1732                          * If there is exactly one reference to the backing
 1733                          * object, we can collapse it into the parent.  
 1734                          */
 1735                         vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
 1736 
 1737 #if VM_NRESERVLEVEL > 0
 1738                         /*
 1739                          * Break any reservations from backing_object.
 1740                          */
 1741                         if (__predict_false(!LIST_EMPTY(&backing_object->rvq)))
 1742                                 vm_reserv_break_all(backing_object);
 1743 #endif
 1744 
 1745                         /*
 1746                          * Move the pager from backing_object to object.
 1747                          */
 1748                         if (backing_object->type == OBJT_SWAP) {
 1749                                 /*
 1750                                  * swap_pager_copy() can sleep, in which case
 1751                                  * the backing_object's and object's locks are
 1752                                  * released and reacquired.
 1753                                  * Since swap_pager_copy() is being asked to
 1754                                  * destroy the source, it will change the
 1755                                  * backing_object's type to OBJT_DEFAULT.
 1756                                  */
 1757                                 swap_pager_copy(
 1758                                     backing_object,
 1759                                     object,
 1760                                     OFF_TO_IDX(object->backing_object_offset), TRUE);
 1761 
 1762                                 /*
 1763                                  * Free any cached pages from backing_object.
 1764                                  */
 1765                                 if (__predict_false(
 1766                                     !vm_object_cache_is_empty(backing_object)))
 1767                                         vm_page_cache_free(backing_object, 0, 0);
 1768                         }
 1769                         /*
 1770                          * Object now shadows whatever backing_object did.
 1771                          * Note that the reference to 
 1772                          * backing_object->backing_object moves from within 
 1773                          * backing_object to within object.
 1774                          */
 1775                         LIST_REMOVE(object, shadow_list);
 1776                         backing_object->shadow_count--;
 1777                         if (backing_object->backing_object) {
 1778                                 VM_OBJECT_WLOCK(backing_object->backing_object);
 1779                                 LIST_REMOVE(backing_object, shadow_list);
 1780                                 LIST_INSERT_HEAD(
 1781                                     &backing_object->backing_object->shadow_head,
 1782                                     object, shadow_list);
 1783                                 /*
 1784                                  * The shadow_count has not changed.
 1785                                  */
 1786                                 VM_OBJECT_WUNLOCK(backing_object->backing_object);
 1787                         }
 1788                         object->backing_object = backing_object->backing_object;
 1789                         object->backing_object_offset +=
 1790                             backing_object->backing_object_offset;
 1791 
 1792                         /*
 1793                          * Discard backing_object.
 1794                          *
 1795                          * Since the backing object has no pages, no pager left,
 1796                          * and no object references within it, all that is
 1797                          * necessary is to dispose of it.
 1798                          */
 1799                         KASSERT(backing_object->ref_count == 1, (
 1800 "backing_object %p was somehow re-referenced during collapse!",
 1801                             backing_object));
 1802                         vm_object_pip_wakeup(backing_object);
 1803                         backing_object->type = OBJT_DEAD;
 1804                         backing_object->ref_count = 0;
 1805                         VM_OBJECT_WUNLOCK(backing_object);
 1806                         vm_object_destroy(backing_object);
 1807 
 1808                         vm_object_pip_wakeup(object);
 1809                         object_collapses++;
 1810                 } else {
 1811                         /*
 1812                          * If we do not entirely shadow the backing object,
 1813                          * there is nothing we can do so we give up.
 1814                          */
 1815                         if (object->resident_page_count != object->size &&
 1816                             !vm_object_backing_scan(object,
 1817                             OBSC_TEST_ALL_SHADOWED)) {
 1818                                 VM_OBJECT_WUNLOCK(backing_object);
 1819                                 break;
 1820                         }
 1821 
 1822                         /*
 1823                          * Make the parent shadow the next object in the
 1824                          * chain.  Deallocating backing_object will not remove
 1825                          * it, since its reference count is at least 2.
 1826                          */
 1827                         LIST_REMOVE(object, shadow_list);
 1828                         backing_object->shadow_count--;
 1829 
 1830                         new_backing_object = backing_object->backing_object;
 1831                         if ((object->backing_object = new_backing_object) != NULL) {
 1832                                 VM_OBJECT_WLOCK(new_backing_object);
 1833                                 LIST_INSERT_HEAD(
 1834                                     &new_backing_object->shadow_head,
 1835                                     object,
 1836                                     shadow_list
 1837                                 );
 1838                                 new_backing_object->shadow_count++;
 1839                                 vm_object_reference_locked(new_backing_object);
 1840                                 VM_OBJECT_WUNLOCK(new_backing_object);
 1841                                 object->backing_object_offset +=
 1842                                         backing_object->backing_object_offset;
 1843                         }
 1844 
 1845                         /*
 1846                          * Drop the reference count on backing_object. Since
 1847                          * its ref_count was at least 2, it will not vanish.
 1848                          */
 1849                         backing_object->ref_count--;
 1850                         VM_OBJECT_WUNLOCK(backing_object);
 1851                         object_bypasses++;
 1852                 }
 1853 
 1854                 /*
 1855                  * Try again with this object's new backing object.
 1856                  */
 1857         }
 1858 }
 1859 
 1860 /*
 1861  *      vm_object_page_remove:
 1862  *
 1863  *      For the given object, either frees or invalidates each of the
 1864  *      specified pages.  In general, a page is freed.  However, if a page is
 1865  *      wired for any reason other than the existence of a managed, wired
 1866  *      mapping, then it may be invalidated but not removed from the object.
 1867  *      Pages are specified by the given range ["start", "end") and the option
 1868  *      OBJPR_CLEANONLY.  As a special case, if "end" is zero, then the range
 1869  *      extends from "start" to the end of the object.  If the option
 1870  *      OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
 1871  *      specified range are affected.  If the option OBJPR_NOTMAPPED is
 1872  *      specified, then the pages within the specified range must have no
 1873  *      mappings.  Otherwise, if this option is not specified, any mappings to
 1874  *      the specified pages are removed before the pages are freed or
 1875  *      invalidated.
 1876  *
 1877  *      In general, this operation should only be performed on objects that
 1878  *      contain managed pages.  There are, however, two exceptions.  First, it
 1879  *      is performed on the kernel and kmem objects by vm_map_entry_delete().
 1880  *      Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
 1881  *      backed pages.  In both of these cases, the option OBJPR_CLEANONLY must
 1882  *      not be specified and the option OBJPR_NOTMAPPED must be specified.
 1883  *
 1884  *      The object must be locked.
 1885  */
 1886 void
 1887 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
 1888     int options)
 1889 {
 1890         vm_page_t p, next;
 1891 
 1892         VM_OBJECT_ASSERT_WLOCKED(object);
 1893         KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
 1894             (options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
 1895             ("vm_object_page_remove: illegal options for object %p", object));
 1896         if (object->resident_page_count == 0)
 1897                 goto skipmemq;
 1898         vm_object_pip_add(object, 1);
 1899 again:
 1900         p = vm_page_find_least(object, start);
 1901 
 1902         /*
 1903          * Here, the variable "p" is either (1) the page with the least pindex
 1904          * greater than or equal to the parameter "start" or (2) NULL. 
 1905          */
 1906         for (; p != NULL && (p->pindex < end || end == 0); p = next) {
 1907                 next = TAILQ_NEXT(p, listq);
 1908 
 1909                 /*
 1910                  * If the page is wired for any reason besides the existence
 1911                  * of managed, wired mappings, then it cannot be freed.  For
 1912                  * example, fictitious pages, which represent device memory,
 1913                  * are inherently wired and cannot be freed.  They can,
 1914                  * however, be invalidated if the option OBJPR_CLEANONLY is
 1915                  * not specified.
 1916                  */
 1917                 vm_page_lock(p);
 1918                 if (vm_page_xbusied(p)) {
 1919                         VM_OBJECT_WUNLOCK(object);
 1920                         vm_page_busy_sleep(p, "vmopax", true);
 1921                         VM_OBJECT_WLOCK(object);
 1922                         goto again;
 1923                 }
 1924                 if (p->wire_count != 0) {
 1925                         if ((options & OBJPR_NOTMAPPED) == 0)
 1926                                 pmap_remove_all(p);
 1927                         if ((options & OBJPR_CLEANONLY) == 0) {
 1928                                 p->valid = 0;
 1929                                 vm_page_undirty(p);
 1930                         }
 1931                         goto next;
 1932                 }
 1933                 if (vm_page_busied(p)) {
 1934                         VM_OBJECT_WUNLOCK(object);
 1935                         vm_page_busy_sleep(p, "vmopar", false);
 1936                         VM_OBJECT_WLOCK(object);
 1937                         goto again;
 1938                 }
 1939                 KASSERT((p->flags & PG_FICTITIOUS) == 0,
 1940                     ("vm_object_page_remove: page %p is fictitious", p));
 1941                 if ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {
 1942                         if ((options & OBJPR_NOTMAPPED) == 0)
 1943                                 pmap_remove_write(p);
 1944                         if (p->dirty)
 1945                                 goto next;
 1946                 }
 1947                 if ((options & OBJPR_NOTMAPPED) == 0)
 1948                         pmap_remove_all(p);
 1949                 vm_page_free(p);
 1950 next:
 1951                 vm_page_unlock(p);
 1952         }
 1953         vm_object_pip_wakeup(object);
 1954 skipmemq:
 1955         if (__predict_false(!vm_object_cache_is_empty(object)))
 1956                 vm_page_cache_free(object, start, end);
 1957 }
 1958 
 1959 /*
 1960  *      vm_object_page_cache:
 1961  *
 1962  *      For the given object, attempt to move the specified clean
 1963  *      pages to the cache queue.  If a page is wired for any reason,
 1964  *      then it will not be changed.  Pages are specified by the given
 1965  *      range ["start", "end").  As a special case, if "end" is zero,
 1966  *      then the range extends from "start" to the end of the object.
 1967  *      Any mappings to the specified pages are removed before the
 1968  *      pages are moved to the cache queue.
 1969  *
 1970  *      This operation should only be performed on objects that
 1971  *      contain non-fictitious, managed pages.
 1972  *
 1973  *      The object must be locked.
 1974  */
 1975 void
 1976 vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 1977 {
 1978         struct mtx *mtx, *new_mtx;
 1979         vm_page_t p, next;
 1980 
 1981         VM_OBJECT_ASSERT_WLOCKED(object);
 1982         KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
 1983             ("vm_object_page_cache: illegal object %p", object));
 1984         if (object->resident_page_count == 0)
 1985                 return;
 1986         p = vm_page_find_least(object, start);
 1987 
 1988         /*
 1989          * Here, the variable "p" is either (1) the page with the least pindex
 1990          * greater than or equal to the parameter "start" or (2) NULL. 
 1991          */
 1992         mtx = NULL;
 1993         for (; p != NULL && (p->pindex < end || end == 0); p = next) {
 1994                 next = TAILQ_NEXT(p, listq);
 1995 
 1996                 /*
 1997                  * Avoid releasing and reacquiring the same page lock.
 1998                  */
 1999                 new_mtx = vm_page_lockptr(p);
 2000                 if (mtx != new_mtx) {
 2001                         if (mtx != NULL)
 2002                                 mtx_unlock(mtx);
 2003                         mtx = new_mtx;
 2004                         mtx_lock(mtx);
 2005                 }
 2006                 vm_page_try_to_cache(p);
 2007         }
 2008         if (mtx != NULL)
 2009                 mtx_unlock(mtx);
 2010 }
 2011 
 2012 /*
 2013  *      Populate the specified range of the object with valid pages.  Returns
 2014  *      TRUE if the range is successfully populated and FALSE otherwise.
 2015  *
 2016  *      Note: This function should be optimized to pass a larger array of
 2017  *      pages to vm_pager_get_pages() before it is applied to a non-
 2018  *      OBJT_DEVICE object.
 2019  *
 2020  *      The object must be locked.
 2021  */
 2022 boolean_t
 2023 vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 2024 {
 2025         vm_page_t m, ma[1];
 2026         vm_pindex_t pindex;
 2027         int rv;
 2028 
 2029         VM_OBJECT_ASSERT_WLOCKED(object);
 2030         for (pindex = start; pindex < end; pindex++) {
 2031                 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
 2032                 if (m->valid != VM_PAGE_BITS_ALL) {
 2033                         ma[0] = m;
 2034                         rv = vm_pager_get_pages(object, ma, 1, 0);
 2035                         m = vm_page_lookup(object, pindex);
 2036                         if (m == NULL)
 2037                                 break;
 2038                         if (rv != VM_PAGER_OK) {
 2039                                 vm_page_lock(m);
 2040                                 vm_page_free(m);
 2041                                 vm_page_unlock(m);
 2042                                 break;
 2043                         }
 2044                 }
 2045                 /*
 2046                  * Keep "m" busy because a subsequent iteration may unlock
 2047                  * the object.
 2048                  */
 2049         }
 2050         if (pindex > start) {
 2051                 m = vm_page_lookup(object, start);
 2052                 while (m != NULL && m->pindex < pindex) {
 2053                         vm_page_xunbusy(m);
 2054                         m = TAILQ_NEXT(m, listq);
 2055                 }
 2056         }
 2057         return (pindex == end);
 2058 }
 2059 
 2060 /*
 2061  *      Routine:        vm_object_coalesce
 2062  *      Function:       Coalesces two objects backing up adjoining
 2063  *                      regions of memory into a single object.
 2064  *
 2065  *      returns TRUE if objects were combined.
 2066  *
 2067  *      NOTE:   Only works at the moment if the second object is NULL -
 2068  *              if it's not, which object do we lock first?
 2069  *
 2070  *      Parameters:
 2071  *              prev_object     First object to coalesce
 2072  *              prev_offset     Offset into prev_object
 2073  *              prev_size       Size of reference to prev_object
 2074  *              next_size       Size of reference to the second object
 2075  *              reserved        Indicator that extension region has
 2076  *                              swap accounted for
 2077  *
 2078  *      Conditions:
 2079  *      The object must *not* be locked.
 2080  */
 2081 boolean_t
 2082 vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
 2083     vm_size_t prev_size, vm_size_t next_size, boolean_t reserved)
 2084 {
 2085         vm_pindex_t next_pindex;
 2086 
 2087         if (prev_object == NULL)
 2088                 return (TRUE);
 2089         VM_OBJECT_WLOCK(prev_object);
 2090         if ((prev_object->type != OBJT_DEFAULT &&
 2091             prev_object->type != OBJT_SWAP) ||
 2092             (prev_object->flags & OBJ_TMPFS_NODE) != 0) {
 2093                 VM_OBJECT_WUNLOCK(prev_object);
 2094                 return (FALSE);
 2095         }
 2096 
 2097         /*
 2098          * Try to collapse the object first
 2099          */
 2100         vm_object_collapse(prev_object);
 2101 
 2102         /*
 2103          * Can't coalesce if: . more than one reference . paged out . shadows
 2104          * another object . has a copy elsewhere (any of which mean that the
 2105          * pages not mapped to prev_entry may be in use anyway)
 2106          */
 2107         if (prev_object->backing_object != NULL) {
 2108                 VM_OBJECT_WUNLOCK(prev_object);
 2109                 return (FALSE);
 2110         }
 2111 
 2112         prev_size >>= PAGE_SHIFT;
 2113         next_size >>= PAGE_SHIFT;
 2114         next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
 2115 
 2116         if ((prev_object->ref_count > 1) &&
 2117             (prev_object->size != next_pindex)) {
 2118                 VM_OBJECT_WUNLOCK(prev_object);
 2119                 return (FALSE);
 2120         }
 2121 
 2122         /*
 2123          * Account for the charge.
 2124          */
 2125         if (prev_object->cred != NULL) {
 2126 
 2127                 /*
 2128                  * If prev_object was charged, then this mapping,
 2129                  * althought not charged now, may become writable
 2130                  * later. Non-NULL cred in the object would prevent
 2131                  * swap reservation during enabling of the write
 2132                  * access, so reserve swap now. Failed reservation
 2133                  * cause allocation of the separate object for the map
 2134                  * entry, and swap reservation for this entry is
 2135                  * managed in appropriate time.
 2136                  */
 2137                 if (!reserved && !swap_reserve_by_cred(ptoa(next_size),
 2138                     prev_object->cred)) {
 2139                         VM_OBJECT_WUNLOCK(prev_object);
 2140                         return (FALSE);
 2141                 }
 2142                 prev_object->charge += ptoa(next_size);
 2143         }
 2144 
 2145         /*
 2146          * Remove any pages that may still be in the object from a previous
 2147          * deallocation.
 2148          */
 2149         if (next_pindex < prev_object->size) {
 2150                 vm_object_page_remove(prev_object, next_pindex, next_pindex +
 2151                     next_size, 0);
 2152                 if (prev_object->type == OBJT_SWAP)
 2153                         swap_pager_freespace(prev_object,
 2154                                              next_pindex, next_size);
 2155 #if 0
 2156                 if (prev_object->cred != NULL) {
 2157                         KASSERT(prev_object->charge >=
 2158                             ptoa(prev_object->size - next_pindex),
 2159                             ("object %p overcharged 1 %jx %jx", prev_object,
 2160                                 (uintmax_t)next_pindex, (uintmax_t)next_size));
 2161                         prev_object->charge -= ptoa(prev_object->size -
 2162                             next_pindex);
 2163                 }
 2164 #endif
 2165         }
 2166 
 2167         /*
 2168          * Extend the object if necessary.
 2169          */
 2170         if (next_pindex + next_size > prev_object->size)
 2171                 prev_object->size = next_pindex + next_size;
 2172 
 2173         VM_OBJECT_WUNLOCK(prev_object);
 2174         return (TRUE);
 2175 }
 2176 
 2177 void
 2178 vm_object_set_writeable_dirty(vm_object_t object)
 2179 {
 2180 
 2181         VM_OBJECT_ASSERT_WLOCKED(object);
 2182         if (object->type != OBJT_VNODE) {
 2183                 if ((object->flags & OBJ_TMPFS_NODE) != 0) {
 2184                         KASSERT(object->type == OBJT_SWAP, ("non-swap tmpfs"));
 2185                         vm_object_set_flag(object, OBJ_TMPFS_DIRTY);
 2186                 }
 2187                 return;
 2188         }
 2189         object->generation++;
 2190         if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
 2191                 return;
 2192         vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
 2193 }
 2194 
 2195 /*
 2196  *      vm_object_unwire:
 2197  *
 2198  *      For each page offset within the specified range of the given object,
 2199  *      find the highest-level page in the shadow chain and unwire it.  A page
 2200  *      must exist at every page offset, and the highest-level page must be
 2201  *      wired.
 2202  */
 2203 void
 2204 vm_object_unwire(vm_object_t object, vm_ooffset_t offset, vm_size_t length,
 2205     uint8_t queue)
 2206 {
 2207         vm_object_t tobject;
 2208         vm_page_t m, tm;
 2209         vm_pindex_t end_pindex, pindex, tpindex;
 2210         int depth, locked_depth;
 2211 
 2212         KASSERT((offset & PAGE_MASK) == 0,
 2213             ("vm_object_unwire: offset is not page aligned"));
 2214         KASSERT((length & PAGE_MASK) == 0,
 2215             ("vm_object_unwire: length is not a multiple of PAGE_SIZE"));
 2216         /* The wired count of a fictitious page never changes. */
 2217         if ((object->flags & OBJ_FICTITIOUS) != 0)
 2218                 return;
 2219         pindex = OFF_TO_IDX(offset);
 2220         end_pindex = pindex + atop(length);
 2221         locked_depth = 1;
 2222         VM_OBJECT_RLOCK(object);
 2223         m = vm_page_find_least(object, pindex);
 2224         while (pindex < end_pindex) {
 2225                 if (m == NULL || pindex < m->pindex) {
 2226                         /*
 2227                          * The first object in the shadow chain doesn't
 2228                          * contain a page at the current index.  Therefore,
 2229                          * the page must exist in a backing object.
 2230                          */
 2231                         tobject = object;
 2232                         tpindex = pindex;
 2233                         depth = 0;
 2234                         do {
 2235                                 tpindex +=
 2236                                     OFF_TO_IDX(tobject->backing_object_offset);
 2237                                 tobject = tobject->backing_object;
 2238                                 KASSERT(tobject != NULL,
 2239                                     ("vm_object_unwire: missing page"));
 2240                                 if ((tobject->flags & OBJ_FICTITIOUS) != 0)
 2241                                         goto next_page;
 2242                                 depth++;
 2243                                 if (depth == locked_depth) {
 2244                                         locked_depth++;
 2245                                         VM_OBJECT_RLOCK(tobject);
 2246                                 }
 2247                         } while ((tm = vm_page_lookup(tobject, tpindex)) ==
 2248                             NULL);
 2249                 } else {
 2250                         tm = m;
 2251                         m = TAILQ_NEXT(m, listq);
 2252                 }
 2253                 vm_page_lock(tm);
 2254                 vm_page_unwire(tm, queue);
 2255                 vm_page_unlock(tm);
 2256 next_page:
 2257                 pindex++;
 2258         }
 2259         /* Release the accumulated object locks. */
 2260         for (depth = 0; depth < locked_depth; depth++) {
 2261                 tobject = object->backing_object;
 2262                 VM_OBJECT_RUNLOCK(object);
 2263                 object = tobject;
 2264         }
 2265 }
 2266 
 2267 struct vnode *
 2268 vm_object_vnode(vm_object_t object)
 2269 {
 2270 
 2271         VM_OBJECT_ASSERT_LOCKED(object);
 2272         if (object->type == OBJT_VNODE)
 2273                 return (object->handle);
 2274         if (object->type == OBJT_SWAP && (object->flags & OBJ_TMPFS) != 0)
 2275                 return (object->un_pager.swp.swp_tmpfs);
 2276         return (NULL);
 2277 }
 2278 
 2279 static int
 2280 sysctl_vm_object_list(SYSCTL_HANDLER_ARGS)
 2281 {
 2282         struct kinfo_vmobject *kvo;
 2283         char *fullpath, *freepath;
 2284         struct vnode *vp;
 2285         struct vattr va;
 2286         vm_object_t obj;
 2287         vm_page_t m;
 2288         int count, error;
 2289 
 2290         if (req->oldptr == NULL) {
 2291                 /*
 2292                  * If an old buffer has not been provided, generate an
 2293                  * estimate of the space needed for a subsequent call.
 2294                  */
 2295                 mtx_lock(&vm_object_list_mtx);
 2296                 count = 0;
 2297                 TAILQ_FOREACH(obj, &vm_object_list, object_list) {
 2298                         if (obj->type == OBJT_DEAD)
 2299                                 continue;
 2300                         count++;
 2301                 }
 2302                 mtx_unlock(&vm_object_list_mtx);
 2303                 return (SYSCTL_OUT(req, NULL, sizeof(struct kinfo_vmobject) *
 2304                     count * 11 / 10));
 2305         }
 2306 
 2307         kvo = malloc(sizeof(*kvo), M_TEMP, M_WAITOK);
 2308         error = 0;
 2309 
 2310         /*
 2311          * VM objects are type stable and are never removed from the
 2312          * list once added.  This allows us to safely read obj->object_list
 2313          * after reacquiring the VM object lock.
 2314          */
 2315         mtx_lock(&vm_object_list_mtx);
 2316         TAILQ_FOREACH(obj, &vm_object_list, object_list) {
 2317                 if (obj->type == OBJT_DEAD)
 2318                         continue;
 2319                 VM_OBJECT_RLOCK(obj);
 2320                 if (obj->type == OBJT_DEAD) {
 2321                         VM_OBJECT_RUNLOCK(obj);
 2322                         continue;
 2323                 }
 2324                 mtx_unlock(&vm_object_list_mtx);
 2325                 kvo->kvo_size = ptoa(obj->size);
 2326                 kvo->kvo_resident = obj->resident_page_count;
 2327                 kvo->kvo_ref_count = obj->ref_count;
 2328                 kvo->kvo_shadow_count = obj->shadow_count;
 2329                 kvo->kvo_memattr = obj->memattr;
 2330                 kvo->kvo_active = 0;
 2331                 kvo->kvo_inactive = 0;
 2332                 TAILQ_FOREACH(m, &obj->memq, listq) {
 2333                         /*
 2334                          * A page may belong to the object but be
 2335                          * dequeued and set to PQ_NONE while the
 2336                          * object lock is not held.  This makes the
 2337                          * reads of m->queue below racy, and we do not
 2338                          * count pages set to PQ_NONE.  However, this
 2339                          * sysctl is only meant to give an
 2340                          * approximation of the system anyway.
 2341                          */
 2342                         if (m->queue == PQ_ACTIVE)
 2343                                 kvo->kvo_active++;
 2344                         else if (m->queue == PQ_INACTIVE)
 2345                                 kvo->kvo_inactive++;
 2346                 }
 2347 
 2348                 kvo->kvo_vn_fileid = 0;
 2349                 kvo->kvo_vn_fsid = 0;
 2350                 freepath = NULL;
 2351                 fullpath = "";
 2352                 vp = NULL;
 2353                 switch (obj->type) {
 2354                 case OBJT_DEFAULT:
 2355                         kvo->kvo_type = KVME_TYPE_DEFAULT;
 2356                         break;
 2357                 case OBJT_VNODE:
 2358                         kvo->kvo_type = KVME_TYPE_VNODE;
 2359                         vp = obj->handle;
 2360                         vref(vp);
 2361                         break;
 2362                 case OBJT_SWAP:
 2363                         kvo->kvo_type = KVME_TYPE_SWAP;
 2364                         break;
 2365                 case OBJT_DEVICE:
 2366                         kvo->kvo_type = KVME_TYPE_DEVICE;
 2367                         break;
 2368                 case OBJT_PHYS:
 2369                         kvo->kvo_type = KVME_TYPE_PHYS;
 2370                         break;
 2371                 case OBJT_DEAD:
 2372                         kvo->kvo_type = KVME_TYPE_DEAD;
 2373                         break;
 2374                 case OBJT_SG:
 2375                         kvo->kvo_type = KVME_TYPE_SG;
 2376                         break;
 2377                 case OBJT_MGTDEVICE:
 2378                         kvo->kvo_type = KVME_TYPE_MGTDEVICE;
 2379                         break;
 2380                 default:
 2381                         kvo->kvo_type = KVME_TYPE_UNKNOWN;
 2382                         break;
 2383                 }
 2384                 VM_OBJECT_RUNLOCK(obj);
 2385                 if (vp != NULL) {
 2386                         vn_fullpath(curthread, vp, &fullpath, &freepath);
 2387                         vn_lock(vp, LK_SHARED | LK_RETRY);
 2388                         if (VOP_GETATTR(vp, &va, curthread->td_ucred) == 0) {
 2389                                 kvo->kvo_vn_fileid = va.va_fileid;
 2390                                 kvo->kvo_vn_fsid = va.va_fsid;
 2391                         }
 2392                         vput(vp);
 2393                 }
 2394 
 2395                 strlcpy(kvo->kvo_path, fullpath, sizeof(kvo->kvo_path));
 2396                 if (freepath != NULL)
 2397                         free(freepath, M_TEMP);
 2398 
 2399                 /* Pack record size down */
 2400                 kvo->kvo_structsize = offsetof(struct kinfo_vmobject, kvo_path)
 2401                     + strlen(kvo->kvo_path) + 1;
 2402                 kvo->kvo_structsize = roundup(kvo->kvo_structsize,
 2403                     sizeof(uint64_t));
 2404                 error = SYSCTL_OUT(req, kvo, kvo->kvo_structsize);
 2405                 mtx_lock(&vm_object_list_mtx);
 2406                 if (error)
 2407                         break;
 2408         }
 2409         mtx_unlock(&vm_object_list_mtx);
 2410         free(kvo, M_TEMP);
 2411         return (error);
 2412 }
 2413 SYSCTL_PROC(_vm, OID_AUTO, objects, CTLTYPE_STRUCT | CTLFLAG_RW | CTLFLAG_SKIP |
 2414     CTLFLAG_MPSAFE, NULL, 0, sysctl_vm_object_list, "S,kinfo_vmobject",
 2415     "List of VM objects");
 2416 
 2417 #include "opt_ddb.h"
 2418 #ifdef DDB
 2419 #include <sys/kernel.h>
 2420 
 2421 #include <sys/cons.h>
 2422 
 2423 #include <ddb/ddb.h>
 2424 
 2425 static int
 2426 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
 2427 {
 2428         vm_map_t tmpm;
 2429         vm_map_entry_t tmpe;
 2430         vm_object_t obj;
 2431         int entcount;
 2432 
 2433         if (map == 0)
 2434                 return 0;
 2435 
 2436         if (entry == 0) {
 2437                 tmpe = map->header.next;
 2438                 entcount = map->nentries;
 2439                 while (entcount-- && (tmpe != &map->header)) {
 2440                         if (_vm_object_in_map(map, object, tmpe)) {
 2441                                 return 1;
 2442                         }
 2443                         tmpe = tmpe->next;
 2444                 }
 2445         } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
 2446                 tmpm = entry->object.sub_map;
 2447                 tmpe = tmpm->header.next;
 2448                 entcount = tmpm->nentries;
 2449                 while (entcount-- && tmpe != &tmpm->header) {
 2450                         if (_vm_object_in_map(tmpm, object, tmpe)) {
 2451                                 return 1;
 2452                         }
 2453                         tmpe = tmpe->next;
 2454                 }
 2455         } else if ((obj = entry->object.vm_object) != NULL) {
 2456                 for (; obj; obj = obj->backing_object)
 2457                         if (obj == object) {
 2458                                 return 1;
 2459                         }
 2460         }
 2461         return 0;
 2462 }
 2463 
 2464 static int
 2465 vm_object_in_map(vm_object_t object)
 2466 {
 2467         struct proc *p;
 2468 
 2469         /* sx_slock(&allproc_lock); */
 2470         FOREACH_PROC_IN_SYSTEM(p) {
 2471                 if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
 2472                         continue;
 2473                 if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
 2474                         /* sx_sunlock(&allproc_lock); */
 2475                         return 1;
 2476                 }
 2477         }
 2478         /* sx_sunlock(&allproc_lock); */
 2479         if (_vm_object_in_map(kernel_map, object, 0))
 2480                 return 1;
 2481         return 0;
 2482 }
 2483 
 2484 DB_SHOW_COMMAND(vmochk, vm_object_check)
 2485 {
 2486         vm_object_t object;
 2487 
 2488         /*
 2489          * make sure that internal objs are in a map somewhere
 2490          * and none have zero ref counts.
 2491          */
 2492         TAILQ_FOREACH(object, &vm_object_list, object_list) {
 2493                 if (object->handle == NULL &&
 2494                     (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
 2495                         if (object->ref_count == 0) {
 2496                                 db_printf("vmochk: internal obj has zero ref count: %ld\n",
 2497                                         (long)object->size);
 2498                         }
 2499                         if (!vm_object_in_map(object)) {
 2500                                 db_printf(
 2501                         "vmochk: internal obj is not in a map: "
 2502                         "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
 2503                                     object->ref_count, (u_long)object->size, 
 2504                                     (u_long)object->size,
 2505                                     (void *)object->backing_object);
 2506                         }
 2507                 }
 2508         }
 2509 }
 2510 
 2511 /*
 2512  *      vm_object_print:        [ debug ]
 2513  */
 2514 DB_SHOW_COMMAND(object, vm_object_print_static)
 2515 {
 2516         /* XXX convert args. */
 2517         vm_object_t object = (vm_object_t)addr;
 2518         boolean_t full = have_addr;
 2519 
 2520         vm_page_t p;
 2521 
 2522         /* XXX count is an (unused) arg.  Avoid shadowing it. */
 2523 #define count   was_count
 2524 
 2525         int count;
 2526 
 2527         if (object == NULL)
 2528                 return;
 2529 
 2530         db_iprintf(
 2531             "Object %p: type=%d, size=0x%jx, res=%d, ref=%d, flags=0x%x ruid %d charge %jx\n",
 2532             object, (int)object->type, (uintmax_t)object->size,
 2533             object->resident_page_count, object->ref_count, object->flags,
 2534             object->cred ? object->cred->cr_ruid : -1, (uintmax_t)object->charge);
 2535         db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%jx\n",
 2536             object->shadow_count, 
 2537             object->backing_object ? object->backing_object->ref_count : 0,
 2538             object->backing_object, (uintmax_t)object->backing_object_offset);
 2539 
 2540         if (!full)
 2541                 return;
 2542 
 2543         db_indent += 2;
 2544         count = 0;
 2545         TAILQ_FOREACH(p, &object->memq, listq) {
 2546                 if (count == 0)
 2547                         db_iprintf("memory:=");
 2548                 else if (count == 6) {
 2549                         db_printf("\n");
 2550                         db_iprintf(" ...");
 2551                         count = 0;
 2552                 } else
 2553                         db_printf(",");
 2554                 count++;
 2555 
 2556                 db_printf("(off=0x%jx,page=0x%jx)",
 2557                     (uintmax_t)p->pindex, (uintmax_t)VM_PAGE_TO_PHYS(p));
 2558         }
 2559         if (count != 0)
 2560                 db_printf("\n");
 2561         db_indent -= 2;
 2562 }
 2563 
 2564 /* XXX. */
 2565 #undef count
 2566 
 2567 /* XXX need this non-static entry for calling from vm_map_print. */
 2568 void
 2569 vm_object_print(
 2570         /* db_expr_t */ long addr,
 2571         boolean_t have_addr,
 2572         /* db_expr_t */ long count,
 2573         char *modif)
 2574 {
 2575         vm_object_print_static(addr, have_addr, count, modif);
 2576 }
 2577 
 2578 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
 2579 {
 2580         vm_object_t object;
 2581         vm_pindex_t fidx;
 2582         vm_paddr_t pa;
 2583         vm_page_t m, prev_m;
 2584         int rcount, nl, c;
 2585 
 2586         nl = 0;
 2587         TAILQ_FOREACH(object, &vm_object_list, object_list) {
 2588                 db_printf("new object: %p\n", (void *)object);
 2589                 if (nl > 18) {
 2590                         c = cngetc();
 2591                         if (c != ' ')
 2592                                 return;
 2593                         nl = 0;
 2594                 }
 2595                 nl++;
 2596                 rcount = 0;
 2597                 fidx = 0;
 2598                 pa = -1;
 2599                 TAILQ_FOREACH(m, &object->memq, listq) {
 2600                         if (m->pindex > 128)
 2601                                 break;
 2602                         if ((prev_m = TAILQ_PREV(m, pglist, listq)) != NULL &&
 2603                             prev_m->pindex + 1 != m->pindex) {
 2604                                 if (rcount) {
 2605                                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
 2606                                                 (long)fidx, rcount, (long)pa);
 2607                                         if (nl > 18) {
 2608                                                 c = cngetc();
 2609                                                 if (c != ' ')
 2610                                                         return;
 2611                                                 nl = 0;
 2612                                         }
 2613                                         nl++;
 2614                                         rcount = 0;
 2615                                 }
 2616                         }                               
 2617                         if (rcount &&
 2618                                 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
 2619                                 ++rcount;
 2620                                 continue;
 2621                         }
 2622                         if (rcount) {
 2623                                 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
 2624                                         (long)fidx, rcount, (long)pa);
 2625                                 if (nl > 18) {
 2626                                         c = cngetc();
 2627                                         if (c != ' ')
 2628                                                 return;
 2629                                         nl = 0;
 2630                                 }
 2631                                 nl++;
 2632                         }
 2633                         fidx = m->pindex;
 2634                         pa = VM_PAGE_TO_PHYS(m);
 2635                         rcount = 1;
 2636                 }
 2637                 if (rcount) {
 2638                         db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
 2639                                 (long)fidx, rcount, (long)pa);
 2640                         if (nl > 18) {
 2641                                 c = cngetc();
 2642                                 if (c != ' ')
 2643                                         return;
 2644                                 nl = 0;
 2645                         }
 2646                         nl++;
 2647                 }
 2648         }
 2649 }
 2650 #endif /* DDB */

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