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

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    1 /*-
    2  * Copyright (c) 1991 Regents of the University of California.
    3  * All rights reserved.
    4  * Copyright (c) 1998 Matthew Dillon.  All Rights Reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * The Mach Operating System project at Carnegie-Mellon University.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      from: @(#)vm_page.c     7.4 (Berkeley) 5/7/91
   34  */
   35 
   36 /*-
   37  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   38  * All rights reserved.
   39  *
   40  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
   41  *
   42  * Permission to use, copy, modify and distribute this software and
   43  * its documentation is hereby granted, provided that both the copyright
   44  * notice and this permission notice appear in all copies of the
   45  * software, derivative works or modified versions, and any portions
   46  * thereof, and that both notices appear in supporting documentation.
   47  *
   48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   50  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   51  *
   52  * Carnegie Mellon requests users of this software to return to
   53  *
   54  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   55  *  School of Computer Science
   56  *  Carnegie Mellon University
   57  *  Pittsburgh PA 15213-3890
   58  *
   59  * any improvements or extensions that they make and grant Carnegie the
   60  * rights to redistribute these changes.
   61  */
   62 
   63 /*
   64  *                      GENERAL RULES ON VM_PAGE MANIPULATION
   65  *
   66  *      - A page queue lock is required when adding or removing a page from a
   67  *        page queue regardless of other locks or the busy state of a page.
   68  *
   69  *              * In general, no thread besides the page daemon can acquire or
   70  *                hold more than one page queue lock at a time.
   71  *
   72  *              * The page daemon can acquire and hold any pair of page queue
   73  *                locks in any order.
   74  *
   75  *      - The object lock is required when inserting or removing
   76  *        pages from an object (vm_page_insert() or vm_page_remove()).
   77  *
   78  */
   79 
   80 /*
   81  *      Resident memory management module.
   82  */
   83 
   84 #include <sys/cdefs.h>
   85 __FBSDID("$FreeBSD: releng/10.3/sys/vm/vm_page.c 290741 2015-11-13 02:16:08Z markj $");
   86 
   87 #include "opt_vm.h"
   88 
   89 #include <sys/param.h>
   90 #include <sys/systm.h>
   91 #include <sys/lock.h>
   92 #include <sys/kernel.h>
   93 #include <sys/limits.h>
   94 #include <sys/malloc.h>
   95 #include <sys/mman.h>
   96 #include <sys/msgbuf.h>
   97 #include <sys/mutex.h>
   98 #include <sys/proc.h>
   99 #include <sys/rwlock.h>
  100 #include <sys/sysctl.h>
  101 #include <sys/vmmeter.h>
  102 #include <sys/vnode.h>
  103 
  104 #include <vm/vm.h>
  105 #include <vm/pmap.h>
  106 #include <vm/vm_param.h>
  107 #include <vm/vm_kern.h>
  108 #include <vm/vm_object.h>
  109 #include <vm/vm_page.h>
  110 #include <vm/vm_pageout.h>
  111 #include <vm/vm_pager.h>
  112 #include <vm/vm_phys.h>
  113 #include <vm/vm_radix.h>
  114 #include <vm/vm_reserv.h>
  115 #include <vm/vm_extern.h>
  116 #include <vm/uma.h>
  117 #include <vm/uma_int.h>
  118 
  119 #include <machine/md_var.h>
  120 
  121 /*
  122  *      Associated with page of user-allocatable memory is a
  123  *      page structure.
  124  */
  125 
  126 struct vm_domain vm_dom[MAXMEMDOM];
  127 struct mtx_padalign vm_page_queue_free_mtx;
  128 
  129 struct mtx_padalign pa_lock[PA_LOCK_COUNT];
  130 
  131 vm_page_t vm_page_array;
  132 long vm_page_array_size;
  133 long first_page;
  134 int vm_page_zero_count;
  135 
  136 static int boot_pages = UMA_BOOT_PAGES;
  137 TUNABLE_INT("vm.boot_pages", &boot_pages);
  138 SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0,
  139         "number of pages allocated for bootstrapping the VM system");
  140 
  141 static int pa_tryrelock_restart;
  142 SYSCTL_INT(_vm, OID_AUTO, tryrelock_restart, CTLFLAG_RD,
  143     &pa_tryrelock_restart, 0, "Number of tryrelock restarts");
  144 
  145 static uma_zone_t fakepg_zone;
  146 
  147 static struct vnode *vm_page_alloc_init(vm_page_t m);
  148 static void vm_page_cache_turn_free(vm_page_t m);
  149 static void vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits);
  150 static void vm_page_enqueue(int queue, vm_page_t m);
  151 static void vm_page_init_fakepg(void *dummy);
  152 static int vm_page_insert_after(vm_page_t m, vm_object_t object,
  153     vm_pindex_t pindex, vm_page_t mpred);
  154 static void vm_page_insert_radixdone(vm_page_t m, vm_object_t object,
  155     vm_page_t mpred);
  156 
  157 SYSINIT(vm_page, SI_SUB_VM, SI_ORDER_SECOND, vm_page_init_fakepg, NULL);
  158 
  159 static void
  160 vm_page_init_fakepg(void *dummy)
  161 {
  162 
  163         fakepg_zone = uma_zcreate("fakepg", sizeof(struct vm_page), NULL, NULL,
  164             NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 
  165 }
  166 
  167 /* Make sure that u_long is at least 64 bits when PAGE_SIZE is 32K. */
  168 #if PAGE_SIZE == 32768
  169 #ifdef CTASSERT
  170 CTASSERT(sizeof(u_long) >= 8);
  171 #endif
  172 #endif
  173 
  174 /*
  175  * Try to acquire a physical address lock while a pmap is locked.  If we
  176  * fail to trylock we unlock and lock the pmap directly and cache the
  177  * locked pa in *locked.  The caller should then restart their loop in case
  178  * the virtual to physical mapping has changed.
  179  */
  180 int
  181 vm_page_pa_tryrelock(pmap_t pmap, vm_paddr_t pa, vm_paddr_t *locked)
  182 {
  183         vm_paddr_t lockpa;
  184 
  185         lockpa = *locked;
  186         *locked = pa;
  187         if (lockpa) {
  188                 PA_LOCK_ASSERT(lockpa, MA_OWNED);
  189                 if (PA_LOCKPTR(pa) == PA_LOCKPTR(lockpa))
  190                         return (0);
  191                 PA_UNLOCK(lockpa);
  192         }
  193         if (PA_TRYLOCK(pa))
  194                 return (0);
  195         PMAP_UNLOCK(pmap);
  196         atomic_add_int(&pa_tryrelock_restart, 1);
  197         PA_LOCK(pa);
  198         PMAP_LOCK(pmap);
  199         return (EAGAIN);
  200 }
  201 
  202 /*
  203  *      vm_set_page_size:
  204  *
  205  *      Sets the page size, perhaps based upon the memory
  206  *      size.  Must be called before any use of page-size
  207  *      dependent functions.
  208  */
  209 void
  210 vm_set_page_size(void)
  211 {
  212         if (cnt.v_page_size == 0)
  213                 cnt.v_page_size = PAGE_SIZE;
  214         if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0)
  215                 panic("vm_set_page_size: page size not a power of two");
  216 }
  217 
  218 /*
  219  *      vm_page_blacklist_lookup:
  220  *
  221  *      See if a physical address in this page has been listed
  222  *      in the blacklist tunable.  Entries in the tunable are
  223  *      separated by spaces or commas.  If an invalid integer is
  224  *      encountered then the rest of the string is skipped.
  225  */
  226 static int
  227 vm_page_blacklist_lookup(char *list, vm_paddr_t pa)
  228 {
  229         vm_paddr_t bad;
  230         char *cp, *pos;
  231 
  232         for (pos = list; *pos != '\0'; pos = cp) {
  233                 bad = strtoq(pos, &cp, 0);
  234                 if (*cp != '\0') {
  235                         if (*cp == ' ' || *cp == ',') {
  236                                 cp++;
  237                                 if (cp == pos)
  238                                         continue;
  239                         } else
  240                                 break;
  241                 }
  242                 if (pa == trunc_page(bad))
  243                         return (1);
  244         }
  245         return (0);
  246 }
  247 
  248 static void
  249 vm_page_domain_init(struct vm_domain *vmd)
  250 {
  251         struct vm_pagequeue *pq;
  252         int i;
  253 
  254         *__DECONST(char **, &vmd->vmd_pagequeues[PQ_INACTIVE].pq_name) =
  255             "vm inactive pagequeue";
  256         *__DECONST(int **, &vmd->vmd_pagequeues[PQ_INACTIVE].pq_vcnt) =
  257             &cnt.v_inactive_count;
  258         *__DECONST(char **, &vmd->vmd_pagequeues[PQ_ACTIVE].pq_name) =
  259             "vm active pagequeue";
  260         *__DECONST(int **, &vmd->vmd_pagequeues[PQ_ACTIVE].pq_vcnt) =
  261             &cnt.v_active_count;
  262         vmd->vmd_page_count = 0;
  263         vmd->vmd_free_count = 0;
  264         vmd->vmd_segs = 0;
  265         vmd->vmd_oom = FALSE;
  266         vmd->vmd_pass = 0;
  267         for (i = 0; i < PQ_COUNT; i++) {
  268                 pq = &vmd->vmd_pagequeues[i];
  269                 TAILQ_INIT(&pq->pq_pl);
  270                 mtx_init(&pq->pq_mutex, pq->pq_name, "vm pagequeue",
  271                     MTX_DEF | MTX_DUPOK);
  272         }
  273 }
  274 
  275 /*
  276  *      vm_page_startup:
  277  *
  278  *      Initializes the resident memory module.
  279  *
  280  *      Allocates memory for the page cells, and
  281  *      for the object/offset-to-page hash table headers.
  282  *      Each page cell is initialized and placed on the free list.
  283  */
  284 vm_offset_t
  285 vm_page_startup(vm_offset_t vaddr)
  286 {
  287         vm_offset_t mapped;
  288         vm_paddr_t page_range;
  289         vm_paddr_t new_end;
  290         int i;
  291         vm_paddr_t pa;
  292         vm_paddr_t last_pa;
  293         char *list;
  294 
  295         /* the biggest memory array is the second group of pages */
  296         vm_paddr_t end;
  297         vm_paddr_t biggestsize;
  298         vm_paddr_t low_water, high_water;
  299         int biggestone;
  300 
  301         biggestsize = 0;
  302         biggestone = 0;
  303         vaddr = round_page(vaddr);
  304 
  305         for (i = 0; phys_avail[i + 1]; i += 2) {
  306                 phys_avail[i] = round_page(phys_avail[i]);
  307                 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]);
  308         }
  309 
  310 #ifdef XEN
  311         /*
  312          * There is no obvious reason why i386 PV Xen needs vm_page structs
  313          * created for these pseudo-physical addresses.  XXX
  314          */
  315         vm_phys_add_seg(0, phys_avail[0]);
  316 #endif
  317 
  318         low_water = phys_avail[0];
  319         high_water = phys_avail[1];
  320 
  321         for (i = 0; i < vm_phys_nsegs; i++) {
  322                 if (vm_phys_segs[i].start < low_water)
  323                         low_water = vm_phys_segs[i].start;
  324                 if (vm_phys_segs[i].end > high_water)
  325                         high_water = vm_phys_segs[i].end;
  326         }
  327         for (i = 0; phys_avail[i + 1]; i += 2) {
  328                 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i];
  329 
  330                 if (size > biggestsize) {
  331                         biggestone = i;
  332                         biggestsize = size;
  333                 }
  334                 if (phys_avail[i] < low_water)
  335                         low_water = phys_avail[i];
  336                 if (phys_avail[i + 1] > high_water)
  337                         high_water = phys_avail[i + 1];
  338         }
  339 
  340         end = phys_avail[biggestone+1];
  341 
  342         /*
  343          * Initialize the page and queue locks.
  344          */
  345         mtx_init(&vm_page_queue_free_mtx, "vm page free queue", NULL, MTX_DEF);
  346         for (i = 0; i < PA_LOCK_COUNT; i++)
  347                 mtx_init(&pa_lock[i], "vm page", NULL, MTX_DEF);
  348         for (i = 0; i < vm_ndomains; i++)
  349                 vm_page_domain_init(&vm_dom[i]);
  350 
  351         /*
  352          * Allocate memory for use when boot strapping the kernel memory
  353          * allocator.
  354          */
  355         new_end = end - (boot_pages * UMA_SLAB_SIZE);
  356         new_end = trunc_page(new_end);
  357         mapped = pmap_map(&vaddr, new_end, end,
  358             VM_PROT_READ | VM_PROT_WRITE);
  359         bzero((void *)mapped, end - new_end);
  360         uma_startup((void *)mapped, boot_pages);
  361 
  362 #if defined(__amd64__) || defined(__i386__) || defined(__arm__) || \
  363     defined(__mips__)
  364         /*
  365          * Allocate a bitmap to indicate that a random physical page
  366          * needs to be included in a minidump.
  367          *
  368          * The amd64 port needs this to indicate which direct map pages
  369          * need to be dumped, via calls to dump_add_page()/dump_drop_page().
  370          *
  371          * However, i386 still needs this workspace internally within the
  372          * minidump code.  In theory, they are not needed on i386, but are
  373          * included should the sf_buf code decide to use them.
  374          */
  375         last_pa = 0;
  376         for (i = 0; dump_avail[i + 1] != 0; i += 2)
  377                 if (dump_avail[i + 1] > last_pa)
  378                         last_pa = dump_avail[i + 1];
  379         page_range = last_pa / PAGE_SIZE;
  380         vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY);
  381         new_end -= vm_page_dump_size;
  382         vm_page_dump = (void *)(uintptr_t)pmap_map(&vaddr, new_end,
  383             new_end + vm_page_dump_size, VM_PROT_READ | VM_PROT_WRITE);
  384         bzero((void *)vm_page_dump, vm_page_dump_size);
  385 #endif
  386 #ifdef __amd64__
  387         /*
  388          * Request that the physical pages underlying the message buffer be
  389          * included in a crash dump.  Since the message buffer is accessed
  390          * through the direct map, they are not automatically included.
  391          */
  392         pa = DMAP_TO_PHYS((vm_offset_t)msgbufp->msg_ptr);
  393         last_pa = pa + round_page(msgbufsize);
  394         while (pa < last_pa) {
  395                 dump_add_page(pa);
  396                 pa += PAGE_SIZE;
  397         }
  398 #endif
  399         /*
  400          * Compute the number of pages of memory that will be available for
  401          * use (taking into account the overhead of a page structure per
  402          * page).
  403          */
  404         first_page = low_water / PAGE_SIZE;
  405 #ifdef VM_PHYSSEG_SPARSE
  406         page_range = 0;
  407         for (i = 0; i < vm_phys_nsegs; i++) {
  408                 page_range += atop(vm_phys_segs[i].end -
  409                     vm_phys_segs[i].start);
  410         }
  411         for (i = 0; phys_avail[i + 1] != 0; i += 2)
  412                 page_range += atop(phys_avail[i + 1] - phys_avail[i]);
  413 #elif defined(VM_PHYSSEG_DENSE)
  414         page_range = high_water / PAGE_SIZE - first_page;
  415 #else
  416 #error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
  417 #endif
  418         end = new_end;
  419 
  420         /*
  421          * Reserve an unmapped guard page to trap access to vm_page_array[-1].
  422          */
  423         vaddr += PAGE_SIZE;
  424 
  425         /*
  426          * Initialize the mem entry structures now, and put them in the free
  427          * queue.
  428          */
  429         new_end = trunc_page(end - page_range * sizeof(struct vm_page));
  430         mapped = pmap_map(&vaddr, new_end, end,
  431             VM_PROT_READ | VM_PROT_WRITE);
  432         vm_page_array = (vm_page_t) mapped;
  433 #if VM_NRESERVLEVEL > 0
  434         /*
  435          * Allocate memory for the reservation management system's data
  436          * structures.
  437          */
  438         new_end = vm_reserv_startup(&vaddr, new_end, high_water);
  439 #endif
  440 #if defined(__amd64__) || defined(__mips__)
  441         /*
  442          * pmap_map on amd64 and mips can come out of the direct-map, not kvm
  443          * like i386, so the pages must be tracked for a crashdump to include
  444          * this data.  This includes the vm_page_array and the early UMA
  445          * bootstrap pages.
  446          */
  447         for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE)
  448                 dump_add_page(pa);
  449 #endif  
  450         phys_avail[biggestone + 1] = new_end;
  451 
  452         /*
  453          * Add physical memory segments corresponding to the available
  454          * physical pages.
  455          */
  456         for (i = 0; phys_avail[i + 1] != 0; i += 2)
  457                 vm_phys_add_seg(phys_avail[i], phys_avail[i + 1]);
  458 
  459         /*
  460          * Clear all of the page structures
  461          */
  462         bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page));
  463         for (i = 0; i < page_range; i++)
  464                 vm_page_array[i].order = VM_NFREEORDER;
  465         vm_page_array_size = page_range;
  466 
  467         /*
  468          * Initialize the physical memory allocator.
  469          */
  470         vm_phys_init();
  471 
  472         /*
  473          * Add every available physical page that is not blacklisted to
  474          * the free lists.
  475          */
  476         cnt.v_page_count = 0;
  477         cnt.v_free_count = 0;
  478         list = getenv("vm.blacklist");
  479         for (i = 0; phys_avail[i + 1] != 0; i += 2) {
  480                 pa = phys_avail[i];
  481                 last_pa = phys_avail[i + 1];
  482                 while (pa < last_pa) {
  483                         if (list != NULL &&
  484                             vm_page_blacklist_lookup(list, pa))
  485                                 printf("Skipping page with pa 0x%jx\n",
  486                                     (uintmax_t)pa);
  487                         else
  488                                 vm_phys_add_page(pa);
  489                         pa += PAGE_SIZE;
  490                 }
  491         }
  492         freeenv(list);
  493 #if VM_NRESERVLEVEL > 0
  494         /*
  495          * Initialize the reservation management system.
  496          */
  497         vm_reserv_init();
  498 #endif
  499         return (vaddr);
  500 }
  501 
  502 void
  503 vm_page_reference(vm_page_t m)
  504 {
  505 
  506         vm_page_aflag_set(m, PGA_REFERENCED);
  507 }
  508 
  509 /*
  510  *      vm_page_busy_downgrade:
  511  *
  512  *      Downgrade an exclusive busy page into a single shared busy page.
  513  */
  514 void
  515 vm_page_busy_downgrade(vm_page_t m)
  516 {
  517         u_int x;
  518 
  519         vm_page_assert_xbusied(m);
  520 
  521         for (;;) {
  522                 x = m->busy_lock;
  523                 x &= VPB_BIT_WAITERS;
  524                 if (atomic_cmpset_rel_int(&m->busy_lock,
  525                     VPB_SINGLE_EXCLUSIVER | x, VPB_SHARERS_WORD(1) | x))
  526                         break;
  527         }
  528 }
  529 
  530 /*
  531  *      vm_page_sbusied:
  532  *
  533  *      Return a positive value if the page is shared busied, 0 otherwise.
  534  */
  535 int
  536 vm_page_sbusied(vm_page_t m)
  537 {
  538         u_int x;
  539 
  540         x = m->busy_lock;
  541         return ((x & VPB_BIT_SHARED) != 0 && x != VPB_UNBUSIED);
  542 }
  543 
  544 /*
  545  *      vm_page_sunbusy:
  546  *
  547  *      Shared unbusy a page.
  548  */
  549 void
  550 vm_page_sunbusy(vm_page_t m)
  551 {
  552         u_int x;
  553 
  554         vm_page_assert_sbusied(m);
  555 
  556         for (;;) {
  557                 x = m->busy_lock;
  558                 if (VPB_SHARERS(x) > 1) {
  559                         if (atomic_cmpset_int(&m->busy_lock, x,
  560                             x - VPB_ONE_SHARER))
  561                                 break;
  562                         continue;
  563                 }
  564                 if ((x & VPB_BIT_WAITERS) == 0) {
  565                         KASSERT(x == VPB_SHARERS_WORD(1),
  566                             ("vm_page_sunbusy: invalid lock state"));
  567                         if (atomic_cmpset_int(&m->busy_lock,
  568                             VPB_SHARERS_WORD(1), VPB_UNBUSIED))
  569                                 break;
  570                         continue;
  571                 }
  572                 KASSERT(x == (VPB_SHARERS_WORD(1) | VPB_BIT_WAITERS),
  573                     ("vm_page_sunbusy: invalid lock state for waiters"));
  574 
  575                 vm_page_lock(m);
  576                 if (!atomic_cmpset_int(&m->busy_lock, x, VPB_UNBUSIED)) {
  577                         vm_page_unlock(m);
  578                         continue;
  579                 }
  580                 wakeup(m);
  581                 vm_page_unlock(m);
  582                 break;
  583         }
  584 }
  585 
  586 /*
  587  *      vm_page_busy_sleep:
  588  *
  589  *      Sleep and release the page lock, using the page pointer as wchan.
  590  *      This is used to implement the hard-path of busying mechanism.
  591  *
  592  *      The given page must be locked.
  593  */
  594 void
  595 vm_page_busy_sleep(vm_page_t m, const char *wmesg)
  596 {
  597         u_int x;
  598 
  599         vm_page_lock_assert(m, MA_OWNED);
  600 
  601         x = m->busy_lock;
  602         if (x == VPB_UNBUSIED) {
  603                 vm_page_unlock(m);
  604                 return;
  605         }
  606         if ((x & VPB_BIT_WAITERS) == 0 &&
  607             !atomic_cmpset_int(&m->busy_lock, x, x | VPB_BIT_WAITERS)) {
  608                 vm_page_unlock(m);
  609                 return;
  610         }
  611         msleep(m, vm_page_lockptr(m), PVM | PDROP, wmesg, 0);
  612 }
  613 
  614 /*
  615  *      vm_page_trysbusy:
  616  *
  617  *      Try to shared busy a page.
  618  *      If the operation succeeds 1 is returned otherwise 0.
  619  *      The operation never sleeps.
  620  */
  621 int
  622 vm_page_trysbusy(vm_page_t m)
  623 {
  624         u_int x;
  625 
  626         for (;;) {
  627                 x = m->busy_lock;
  628                 if ((x & VPB_BIT_SHARED) == 0)
  629                         return (0);
  630                 if (atomic_cmpset_acq_int(&m->busy_lock, x, x + VPB_ONE_SHARER))
  631                         return (1);
  632         }
  633 }
  634 
  635 /*
  636  *      vm_page_xunbusy_hard:
  637  *
  638  *      Called after the first try the exclusive unbusy of a page failed.
  639  *      It is assumed that the waiters bit is on.
  640  */
  641 void
  642 vm_page_xunbusy_hard(vm_page_t m)
  643 {
  644 
  645         vm_page_assert_xbusied(m);
  646 
  647         vm_page_lock(m);
  648         atomic_store_rel_int(&m->busy_lock, VPB_UNBUSIED);
  649         wakeup(m);
  650         vm_page_unlock(m);
  651 }
  652 
  653 /*
  654  *      vm_page_flash:
  655  *
  656  *      Wakeup anyone waiting for the page.
  657  *      The ownership bits do not change.
  658  *
  659  *      The given page must be locked.
  660  */
  661 void
  662 vm_page_flash(vm_page_t m)
  663 {
  664         u_int x;
  665 
  666         vm_page_lock_assert(m, MA_OWNED);
  667 
  668         for (;;) {
  669                 x = m->busy_lock;
  670                 if ((x & VPB_BIT_WAITERS) == 0)
  671                         return;
  672                 if (atomic_cmpset_int(&m->busy_lock, x,
  673                     x & (~VPB_BIT_WAITERS)))
  674                         break;
  675         }
  676         wakeup(m);
  677 }
  678 
  679 /*
  680  * Keep page from being freed by the page daemon
  681  * much of the same effect as wiring, except much lower
  682  * overhead and should be used only for *very* temporary
  683  * holding ("wiring").
  684  */
  685 void
  686 vm_page_hold(vm_page_t mem)
  687 {
  688 
  689         vm_page_lock_assert(mem, MA_OWNED);
  690         mem->hold_count++;
  691 }
  692 
  693 void
  694 vm_page_unhold(vm_page_t mem)
  695 {
  696 
  697         vm_page_lock_assert(mem, MA_OWNED);
  698         KASSERT(mem->hold_count >= 1, ("vm_page_unhold: hold count < 0!!!"));
  699         --mem->hold_count;
  700         if (mem->hold_count == 0 && (mem->flags & PG_UNHOLDFREE) != 0)
  701                 vm_page_free_toq(mem);
  702 }
  703 
  704 /*
  705  *      vm_page_unhold_pages:
  706  *
  707  *      Unhold each of the pages that is referenced by the given array.
  708  */ 
  709 void
  710 vm_page_unhold_pages(vm_page_t *ma, int count)
  711 {
  712         struct mtx *mtx, *new_mtx;
  713 
  714         mtx = NULL;
  715         for (; count != 0; count--) {
  716                 /*
  717                  * Avoid releasing and reacquiring the same page lock.
  718                  */
  719                 new_mtx = vm_page_lockptr(*ma);
  720                 if (mtx != new_mtx) {
  721                         if (mtx != NULL)
  722                                 mtx_unlock(mtx);
  723                         mtx = new_mtx;
  724                         mtx_lock(mtx);
  725                 }
  726                 vm_page_unhold(*ma);
  727                 ma++;
  728         }
  729         if (mtx != NULL)
  730                 mtx_unlock(mtx);
  731 }
  732 
  733 vm_page_t
  734 PHYS_TO_VM_PAGE(vm_paddr_t pa)
  735 {
  736         vm_page_t m;
  737 
  738 #ifdef VM_PHYSSEG_SPARSE
  739         m = vm_phys_paddr_to_vm_page(pa);
  740         if (m == NULL)
  741                 m = vm_phys_fictitious_to_vm_page(pa);
  742         return (m);
  743 #elif defined(VM_PHYSSEG_DENSE)
  744         long pi;
  745 
  746         pi = atop(pa);
  747         if (pi >= first_page && (pi - first_page) < vm_page_array_size) {
  748                 m = &vm_page_array[pi - first_page];
  749                 return (m);
  750         }
  751         return (vm_phys_fictitious_to_vm_page(pa));
  752 #else
  753 #error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
  754 #endif
  755 }
  756 
  757 /*
  758  *      vm_page_getfake:
  759  *
  760  *      Create a fictitious page with the specified physical address and
  761  *      memory attribute.  The memory attribute is the only the machine-
  762  *      dependent aspect of a fictitious page that must be initialized.
  763  */
  764 vm_page_t
  765 vm_page_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
  766 {
  767         vm_page_t m;
  768 
  769         m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO);
  770         vm_page_initfake(m, paddr, memattr);
  771         return (m);
  772 }
  773 
  774 void
  775 vm_page_initfake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
  776 {
  777 
  778         if ((m->flags & PG_FICTITIOUS) != 0) {
  779                 /*
  780                  * The page's memattr might have changed since the
  781                  * previous initialization.  Update the pmap to the
  782                  * new memattr.
  783                  */
  784                 goto memattr;
  785         }
  786         m->phys_addr = paddr;
  787         m->queue = PQ_NONE;
  788         /* Fictitious pages don't use "segind". */
  789         m->flags = PG_FICTITIOUS;
  790         /* Fictitious pages don't use "order" or "pool". */
  791         m->oflags = VPO_UNMANAGED;
  792         m->busy_lock = VPB_SINGLE_EXCLUSIVER;
  793         m->wire_count = 1;
  794         pmap_page_init(m);
  795 memattr:
  796         pmap_page_set_memattr(m, memattr);
  797 }
  798 
  799 /*
  800  *      vm_page_putfake:
  801  *
  802  *      Release a fictitious page.
  803  */
  804 void
  805 vm_page_putfake(vm_page_t m)
  806 {
  807 
  808         KASSERT((m->oflags & VPO_UNMANAGED) != 0, ("managed %p", m));
  809         KASSERT((m->flags & PG_FICTITIOUS) != 0,
  810             ("vm_page_putfake: bad page %p", m));
  811         uma_zfree(fakepg_zone, m);
  812 }
  813 
  814 /*
  815  *      vm_page_updatefake:
  816  *
  817  *      Update the given fictitious page to the specified physical address and
  818  *      memory attribute.
  819  */
  820 void
  821 vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
  822 {
  823 
  824         KASSERT((m->flags & PG_FICTITIOUS) != 0,
  825             ("vm_page_updatefake: bad page %p", m));
  826         m->phys_addr = paddr;
  827         pmap_page_set_memattr(m, memattr);
  828 }
  829 
  830 /*
  831  *      vm_page_free:
  832  *
  833  *      Free a page.
  834  */
  835 void
  836 vm_page_free(vm_page_t m)
  837 {
  838 
  839         m->flags &= ~PG_ZERO;
  840         vm_page_free_toq(m);
  841 }
  842 
  843 /*
  844  *      vm_page_free_zero:
  845  *
  846  *      Free a page to the zerod-pages queue
  847  */
  848 void
  849 vm_page_free_zero(vm_page_t m)
  850 {
  851 
  852         m->flags |= PG_ZERO;
  853         vm_page_free_toq(m);
  854 }
  855 
  856 /*
  857  * Unbusy and handle the page queueing for a page from the VOP_GETPAGES()
  858  * array which is not the request page.
  859  */
  860 void
  861 vm_page_readahead_finish(vm_page_t m)
  862 {
  863 
  864         if (m->valid != 0) {
  865                 /*
  866                  * Since the page is not the requested page, whether
  867                  * it should be activated or deactivated is not
  868                  * obvious.  Empirical results have shown that
  869                  * deactivating the page is usually the best choice,
  870                  * unless the page is wanted by another thread.
  871                  */
  872                 vm_page_lock(m);
  873                 if ((m->busy_lock & VPB_BIT_WAITERS) != 0)
  874                         vm_page_activate(m);
  875                 else
  876                         vm_page_deactivate(m);
  877                 vm_page_unlock(m);
  878                 vm_page_xunbusy(m);
  879         } else {
  880                 /*
  881                  * Free the completely invalid page.  Such page state
  882                  * occurs due to the short read operation which did
  883                  * not covered our page at all, or in case when a read
  884                  * error happens.
  885                  */
  886                 vm_page_lock(m);
  887                 vm_page_free(m);
  888                 vm_page_unlock(m);
  889         }
  890 }
  891 
  892 /*
  893  *      vm_page_sleep_if_busy:
  894  *
  895  *      Sleep and release the page queues lock if the page is busied.
  896  *      Returns TRUE if the thread slept.
  897  *
  898  *      The given page must be unlocked and object containing it must
  899  *      be locked.
  900  */
  901 int
  902 vm_page_sleep_if_busy(vm_page_t m, const char *msg)
  903 {
  904         vm_object_t obj;
  905 
  906         vm_page_lock_assert(m, MA_NOTOWNED);
  907         VM_OBJECT_ASSERT_WLOCKED(m->object);
  908 
  909         if (vm_page_busied(m)) {
  910                 /*
  911                  * The page-specific object must be cached because page
  912                  * identity can change during the sleep, causing the
  913                  * re-lock of a different object.
  914                  * It is assumed that a reference to the object is already
  915                  * held by the callers.
  916                  */
  917                 obj = m->object;
  918                 vm_page_lock(m);
  919                 VM_OBJECT_WUNLOCK(obj);
  920                 vm_page_busy_sleep(m, msg);
  921                 VM_OBJECT_WLOCK(obj);
  922                 return (TRUE);
  923         }
  924         return (FALSE);
  925 }
  926 
  927 /*
  928  *      vm_page_dirty_KBI:              [ internal use only ]
  929  *
  930  *      Set all bits in the page's dirty field.
  931  *
  932  *      The object containing the specified page must be locked if the
  933  *      call is made from the machine-independent layer.
  934  *
  935  *      See vm_page_clear_dirty_mask().
  936  *
  937  *      This function should only be called by vm_page_dirty().
  938  */
  939 void
  940 vm_page_dirty_KBI(vm_page_t m)
  941 {
  942 
  943         /* These assertions refer to this operation by its public name. */
  944         KASSERT((m->flags & PG_CACHED) == 0,
  945             ("vm_page_dirty: page in cache!"));
  946         KASSERT(!VM_PAGE_IS_FREE(m),
  947             ("vm_page_dirty: page is free!"));
  948         KASSERT(m->valid == VM_PAGE_BITS_ALL,
  949             ("vm_page_dirty: page is invalid!"));
  950         m->dirty = VM_PAGE_BITS_ALL;
  951 }
  952 
  953 /*
  954  *      vm_page_insert:         [ internal use only ]
  955  *
  956  *      Inserts the given mem entry into the object and object list.
  957  *
  958  *      The object must be locked.
  959  */
  960 int
  961 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
  962 {
  963         vm_page_t mpred;
  964 
  965         VM_OBJECT_ASSERT_WLOCKED(object);
  966         mpred = vm_radix_lookup_le(&object->rtree, pindex);
  967         return (vm_page_insert_after(m, object, pindex, mpred));
  968 }
  969 
  970 /*
  971  *      vm_page_insert_after:
  972  *
  973  *      Inserts the page "m" into the specified object at offset "pindex".
  974  *
  975  *      The page "mpred" must immediately precede the offset "pindex" within
  976  *      the specified object.
  977  *
  978  *      The object must be locked.
  979  */
  980 static int
  981 vm_page_insert_after(vm_page_t m, vm_object_t object, vm_pindex_t pindex,
  982     vm_page_t mpred)
  983 {
  984         vm_pindex_t sidx;
  985         vm_object_t sobj;
  986         vm_page_t msucc;
  987 
  988         VM_OBJECT_ASSERT_WLOCKED(object);
  989         KASSERT(m->object == NULL,
  990             ("vm_page_insert_after: page already inserted"));
  991         if (mpred != NULL) {
  992                 KASSERT(mpred->object == object,
  993                     ("vm_page_insert_after: object doesn't contain mpred"));
  994                 KASSERT(mpred->pindex < pindex,
  995                     ("vm_page_insert_after: mpred doesn't precede pindex"));
  996                 msucc = TAILQ_NEXT(mpred, listq);
  997         } else
  998                 msucc = TAILQ_FIRST(&object->memq);
  999         if (msucc != NULL)
 1000                 KASSERT(msucc->pindex > pindex,
 1001                     ("vm_page_insert_after: msucc doesn't succeed pindex"));
 1002 
 1003         /*
 1004          * Record the object/offset pair in this page
 1005          */
 1006         sobj = m->object;
 1007         sidx = m->pindex;
 1008         m->object = object;
 1009         m->pindex = pindex;
 1010 
 1011         /*
 1012          * Now link into the object's ordered list of backed pages.
 1013          */
 1014         if (vm_radix_insert(&object->rtree, m)) {
 1015                 m->object = sobj;
 1016                 m->pindex = sidx;
 1017                 return (1);
 1018         }
 1019         vm_page_insert_radixdone(m, object, mpred);
 1020         return (0);
 1021 }
 1022 
 1023 /*
 1024  *      vm_page_insert_radixdone:
 1025  *
 1026  *      Complete page "m" insertion into the specified object after the
 1027  *      radix trie hooking.
 1028  *
 1029  *      The page "mpred" must precede the offset "m->pindex" within the
 1030  *      specified object.
 1031  *
 1032  *      The object must be locked.
 1033  */
 1034 static void
 1035 vm_page_insert_radixdone(vm_page_t m, vm_object_t object, vm_page_t mpred)
 1036 {
 1037 
 1038         VM_OBJECT_ASSERT_WLOCKED(object);
 1039         KASSERT(object != NULL && m->object == object,
 1040             ("vm_page_insert_radixdone: page %p has inconsistent object", m));
 1041         if (mpred != NULL) {
 1042                 KASSERT(mpred->object == object,
 1043                     ("vm_page_insert_after: object doesn't contain mpred"));
 1044                 KASSERT(mpred->pindex < m->pindex,
 1045                     ("vm_page_insert_after: mpred doesn't precede pindex"));
 1046         }
 1047 
 1048         if (mpred != NULL)
 1049                 TAILQ_INSERT_AFTER(&object->memq, mpred, m, listq);
 1050         else
 1051                 TAILQ_INSERT_HEAD(&object->memq, m, listq);
 1052 
 1053         /*
 1054          * Show that the object has one more resident page.
 1055          */
 1056         object->resident_page_count++;
 1057 
 1058         /*
 1059          * Hold the vnode until the last page is released.
 1060          */
 1061         if (object->resident_page_count == 1 && object->type == OBJT_VNODE)
 1062                 vhold(object->handle);
 1063 
 1064         /*
 1065          * Since we are inserting a new and possibly dirty page,
 1066          * update the object's OBJ_MIGHTBEDIRTY flag.
 1067          */
 1068         if (pmap_page_is_write_mapped(m))
 1069                 vm_object_set_writeable_dirty(object);
 1070 }
 1071 
 1072 /*
 1073  *      vm_page_remove:
 1074  *
 1075  *      Removes the given mem entry from the object/offset-page
 1076  *      table and the object page list, but do not invalidate/terminate
 1077  *      the backing store.
 1078  *
 1079  *      The object must be locked.  The page must be locked if it is managed.
 1080  */
 1081 void
 1082 vm_page_remove(vm_page_t m)
 1083 {
 1084         vm_object_t object;
 1085         boolean_t lockacq;
 1086 
 1087         if ((m->oflags & VPO_UNMANAGED) == 0)
 1088                 vm_page_lock_assert(m, MA_OWNED);
 1089         if ((object = m->object) == NULL)
 1090                 return;
 1091         VM_OBJECT_ASSERT_WLOCKED(object);
 1092         if (vm_page_xbusied(m)) {
 1093                 lockacq = FALSE;
 1094                 if ((m->oflags & VPO_UNMANAGED) != 0 &&
 1095                     !mtx_owned(vm_page_lockptr(m))) {
 1096                         lockacq = TRUE;
 1097                         vm_page_lock(m);
 1098                 }
 1099                 vm_page_flash(m);
 1100                 atomic_store_rel_int(&m->busy_lock, VPB_UNBUSIED);
 1101                 if (lockacq)
 1102                         vm_page_unlock(m);
 1103         }
 1104 
 1105         /*
 1106          * Now remove from the object's list of backed pages.
 1107          */
 1108         vm_radix_remove(&object->rtree, m->pindex);
 1109         TAILQ_REMOVE(&object->memq, m, listq);
 1110 
 1111         /*
 1112          * And show that the object has one fewer resident page.
 1113          */
 1114         object->resident_page_count--;
 1115 
 1116         /*
 1117          * The vnode may now be recycled.
 1118          */
 1119         if (object->resident_page_count == 0 && object->type == OBJT_VNODE)
 1120                 vdrop(object->handle);
 1121 
 1122         m->object = NULL;
 1123 }
 1124 
 1125 /*
 1126  *      vm_page_lookup:
 1127  *
 1128  *      Returns the page associated with the object/offset
 1129  *      pair specified; if none is found, NULL is returned.
 1130  *
 1131  *      The object must be locked.
 1132  */
 1133 vm_page_t
 1134 vm_page_lookup(vm_object_t object, vm_pindex_t pindex)
 1135 {
 1136 
 1137         VM_OBJECT_ASSERT_LOCKED(object);
 1138         return (vm_radix_lookup(&object->rtree, pindex));
 1139 }
 1140 
 1141 /*
 1142  *      vm_page_find_least:
 1143  *
 1144  *      Returns the page associated with the object with least pindex
 1145  *      greater than or equal to the parameter pindex, or NULL.
 1146  *
 1147  *      The object must be locked.
 1148  */
 1149 vm_page_t
 1150 vm_page_find_least(vm_object_t object, vm_pindex_t pindex)
 1151 {
 1152         vm_page_t m;
 1153 
 1154         VM_OBJECT_ASSERT_LOCKED(object);
 1155         if ((m = TAILQ_FIRST(&object->memq)) != NULL && m->pindex < pindex)
 1156                 m = vm_radix_lookup_ge(&object->rtree, pindex);
 1157         return (m);
 1158 }
 1159 
 1160 /*
 1161  * Returns the given page's successor (by pindex) within the object if it is
 1162  * resident; if none is found, NULL is returned.
 1163  *
 1164  * The object must be locked.
 1165  */
 1166 vm_page_t
 1167 vm_page_next(vm_page_t m)
 1168 {
 1169         vm_page_t next;
 1170 
 1171         VM_OBJECT_ASSERT_WLOCKED(m->object);
 1172         if ((next = TAILQ_NEXT(m, listq)) != NULL &&
 1173             next->pindex != m->pindex + 1)
 1174                 next = NULL;
 1175         return (next);
 1176 }
 1177 
 1178 /*
 1179  * Returns the given page's predecessor (by pindex) within the object if it is
 1180  * resident; if none is found, NULL is returned.
 1181  *
 1182  * The object must be locked.
 1183  */
 1184 vm_page_t
 1185 vm_page_prev(vm_page_t m)
 1186 {
 1187         vm_page_t prev;
 1188 
 1189         VM_OBJECT_ASSERT_WLOCKED(m->object);
 1190         if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
 1191             prev->pindex != m->pindex - 1)
 1192                 prev = NULL;
 1193         return (prev);
 1194 }
 1195 
 1196 /*
 1197  * Uses the page mnew as a replacement for an existing page at index
 1198  * pindex which must be already present in the object.
 1199  *
 1200  * The existing page must not be on a paging queue.
 1201  */
 1202 vm_page_t
 1203 vm_page_replace(vm_page_t mnew, vm_object_t object, vm_pindex_t pindex)
 1204 {
 1205         vm_page_t mold, mpred;
 1206 
 1207         VM_OBJECT_ASSERT_WLOCKED(object);
 1208 
 1209         /*
 1210          * This function mostly follows vm_page_insert() and
 1211          * vm_page_remove() without the radix, object count and vnode
 1212          * dance.  Double check such functions for more comments.
 1213          */
 1214         mpred = vm_radix_lookup(&object->rtree, pindex);
 1215         KASSERT(mpred != NULL,
 1216             ("vm_page_replace: replacing page not present with pindex"));
 1217         mpred = TAILQ_PREV(mpred, respgs, listq);
 1218         if (mpred != NULL)
 1219                 KASSERT(mpred->pindex < pindex,
 1220                     ("vm_page_insert_after: mpred doesn't precede pindex"));
 1221 
 1222         mnew->object = object;
 1223         mnew->pindex = pindex;
 1224         mold = vm_radix_replace(&object->rtree, mnew);
 1225         KASSERT(mold->queue == PQ_NONE,
 1226             ("vm_page_replace: mold is on a paging queue"));
 1227 
 1228         /* Detach the old page from the resident tailq. */
 1229         TAILQ_REMOVE(&object->memq, mold, listq);
 1230 
 1231         mold->object = NULL;
 1232         vm_page_xunbusy(mold);
 1233 
 1234         /* Insert the new page in the resident tailq. */
 1235         if (mpred != NULL)
 1236                 TAILQ_INSERT_AFTER(&object->memq, mpred, mnew, listq);
 1237         else
 1238                 TAILQ_INSERT_HEAD(&object->memq, mnew, listq);
 1239         if (pmap_page_is_write_mapped(mnew))
 1240                 vm_object_set_writeable_dirty(object);
 1241         return (mold);
 1242 }
 1243 
 1244 /*
 1245  *      vm_page_rename:
 1246  *
 1247  *      Move the given memory entry from its
 1248  *      current object to the specified target object/offset.
 1249  *
 1250  *      Note: swap associated with the page must be invalidated by the move.  We
 1251  *            have to do this for several reasons:  (1) we aren't freeing the
 1252  *            page, (2) we are dirtying the page, (3) the VM system is probably
 1253  *            moving the page from object A to B, and will then later move
 1254  *            the backing store from A to B and we can't have a conflict.
 1255  *
 1256  *      Note: we *always* dirty the page.  It is necessary both for the
 1257  *            fact that we moved it, and because we may be invalidating
 1258  *            swap.  If the page is on the cache, we have to deactivate it
 1259  *            or vm_page_dirty() will panic.  Dirty pages are not allowed
 1260  *            on the cache.
 1261  *
 1262  *      The objects must be locked.
 1263  */
 1264 int
 1265 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex)
 1266 {
 1267         vm_page_t mpred;
 1268         vm_pindex_t opidx;
 1269 
 1270         VM_OBJECT_ASSERT_WLOCKED(new_object);
 1271 
 1272         mpred = vm_radix_lookup_le(&new_object->rtree, new_pindex);
 1273         KASSERT(mpred == NULL || mpred->pindex != new_pindex,
 1274             ("vm_page_rename: pindex already renamed"));
 1275 
 1276         /*
 1277          * Create a custom version of vm_page_insert() which does not depend
 1278          * by m_prev and can cheat on the implementation aspects of the
 1279          * function.
 1280          */
 1281         opidx = m->pindex;
 1282         m->pindex = new_pindex;
 1283         if (vm_radix_insert(&new_object->rtree, m)) {
 1284                 m->pindex = opidx;
 1285                 return (1);
 1286         }
 1287 
 1288         /*
 1289          * The operation cannot fail anymore.  The removal must happen before
 1290          * the listq iterator is tainted.
 1291          */
 1292         m->pindex = opidx;
 1293         vm_page_lock(m);
 1294         vm_page_remove(m);
 1295 
 1296         /* Return back to the new pindex to complete vm_page_insert(). */
 1297         m->pindex = new_pindex;
 1298         m->object = new_object;
 1299         vm_page_unlock(m);
 1300         vm_page_insert_radixdone(m, new_object, mpred);
 1301         vm_page_dirty(m);
 1302         return (0);
 1303 }
 1304 
 1305 /*
 1306  *      Convert all of the given object's cached pages that have a
 1307  *      pindex within the given range into free pages.  If the value
 1308  *      zero is given for "end", then the range's upper bound is
 1309  *      infinity.  If the given object is backed by a vnode and it
 1310  *      transitions from having one or more cached pages to none, the
 1311  *      vnode's hold count is reduced. 
 1312  */
 1313 void
 1314 vm_page_cache_free(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 1315 {
 1316         vm_page_t m;
 1317         boolean_t empty;
 1318 
 1319         mtx_lock(&vm_page_queue_free_mtx);
 1320         if (__predict_false(vm_radix_is_empty(&object->cache))) {
 1321                 mtx_unlock(&vm_page_queue_free_mtx);
 1322                 return;
 1323         }
 1324         while ((m = vm_radix_lookup_ge(&object->cache, start)) != NULL) {
 1325                 if (end != 0 && m->pindex >= end)
 1326                         break;
 1327                 vm_radix_remove(&object->cache, m->pindex);
 1328                 vm_page_cache_turn_free(m);
 1329         }
 1330         empty = vm_radix_is_empty(&object->cache);
 1331         mtx_unlock(&vm_page_queue_free_mtx);
 1332         if (object->type == OBJT_VNODE && empty)
 1333                 vdrop(object->handle);
 1334 }
 1335 
 1336 /*
 1337  *      Returns the cached page that is associated with the given
 1338  *      object and offset.  If, however, none exists, returns NULL.
 1339  *
 1340  *      The free page queue must be locked.
 1341  */
 1342 static inline vm_page_t
 1343 vm_page_cache_lookup(vm_object_t object, vm_pindex_t pindex)
 1344 {
 1345 
 1346         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 1347         return (vm_radix_lookup(&object->cache, pindex));
 1348 }
 1349 
 1350 /*
 1351  *      Remove the given cached page from its containing object's
 1352  *      collection of cached pages.
 1353  *
 1354  *      The free page queue must be locked.
 1355  */
 1356 static void
 1357 vm_page_cache_remove(vm_page_t m)
 1358 {
 1359 
 1360         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 1361         KASSERT((m->flags & PG_CACHED) != 0,
 1362             ("vm_page_cache_remove: page %p is not cached", m));
 1363         vm_radix_remove(&m->object->cache, m->pindex);
 1364         m->object = NULL;
 1365         cnt.v_cache_count--;
 1366 }
 1367 
 1368 /*
 1369  *      Transfer all of the cached pages with offset greater than or
 1370  *      equal to 'offidxstart' from the original object's cache to the
 1371  *      new object's cache.  However, any cached pages with offset
 1372  *      greater than or equal to the new object's size are kept in the
 1373  *      original object.  Initially, the new object's cache must be
 1374  *      empty.  Offset 'offidxstart' in the original object must
 1375  *      correspond to offset zero in the new object.
 1376  *
 1377  *      The new object must be locked.
 1378  */
 1379 void
 1380 vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
 1381     vm_object_t new_object)
 1382 {
 1383         vm_page_t m;
 1384 
 1385         /*
 1386          * Insertion into an object's collection of cached pages
 1387          * requires the object to be locked.  In contrast, removal does
 1388          * not.
 1389          */
 1390         VM_OBJECT_ASSERT_WLOCKED(new_object);
 1391         KASSERT(vm_radix_is_empty(&new_object->cache),
 1392             ("vm_page_cache_transfer: object %p has cached pages",
 1393             new_object));
 1394         mtx_lock(&vm_page_queue_free_mtx);
 1395         while ((m = vm_radix_lookup_ge(&orig_object->cache,
 1396             offidxstart)) != NULL) {
 1397                 /*
 1398                  * Transfer all of the pages with offset greater than or
 1399                  * equal to 'offidxstart' from the original object's
 1400                  * cache to the new object's cache.
 1401                  */
 1402                 if ((m->pindex - offidxstart) >= new_object->size)
 1403                         break;
 1404                 vm_radix_remove(&orig_object->cache, m->pindex);
 1405                 /* Update the page's object and offset. */
 1406                 m->object = new_object;
 1407                 m->pindex -= offidxstart;
 1408                 if (vm_radix_insert(&new_object->cache, m))
 1409                         vm_page_cache_turn_free(m);
 1410         }
 1411         mtx_unlock(&vm_page_queue_free_mtx);
 1412 }
 1413 
 1414 /*
 1415  *      Returns TRUE if a cached page is associated with the given object and
 1416  *      offset, and FALSE otherwise.
 1417  *
 1418  *      The object must be locked.
 1419  */
 1420 boolean_t
 1421 vm_page_is_cached(vm_object_t object, vm_pindex_t pindex)
 1422 {
 1423         vm_page_t m;
 1424 
 1425         /*
 1426          * Insertion into an object's collection of cached pages requires the
 1427          * object to be locked.  Therefore, if the object is locked and the
 1428          * object's collection is empty, there is no need to acquire the free
 1429          * page queues lock in order to prove that the specified page doesn't
 1430          * exist.
 1431          */
 1432         VM_OBJECT_ASSERT_WLOCKED(object);
 1433         if (__predict_true(vm_object_cache_is_empty(object)))
 1434                 return (FALSE);
 1435         mtx_lock(&vm_page_queue_free_mtx);
 1436         m = vm_page_cache_lookup(object, pindex);
 1437         mtx_unlock(&vm_page_queue_free_mtx);
 1438         return (m != NULL);
 1439 }
 1440 
 1441 /*
 1442  *      vm_page_alloc:
 1443  *
 1444  *      Allocate and return a page that is associated with the specified
 1445  *      object and offset pair.  By default, this page is exclusive busied.
 1446  *
 1447  *      The caller must always specify an allocation class.
 1448  *
 1449  *      allocation classes:
 1450  *      VM_ALLOC_NORMAL         normal process request
 1451  *      VM_ALLOC_SYSTEM         system *really* needs a page
 1452  *      VM_ALLOC_INTERRUPT      interrupt time request
 1453  *
 1454  *      optional allocation flags:
 1455  *      VM_ALLOC_COUNT(number)  the number of additional pages that the caller
 1456  *                              intends to allocate
 1457  *      VM_ALLOC_IFCACHED       return page only if it is cached
 1458  *      VM_ALLOC_IFNOTCACHED    return NULL, do not reactivate if the page
 1459  *                              is cached
 1460  *      VM_ALLOC_NOBUSY         do not exclusive busy the page
 1461  *      VM_ALLOC_NODUMP         do not include the page in a kernel core dump
 1462  *      VM_ALLOC_NOOBJ          page is not associated with an object and
 1463  *                              should not be exclusive busy 
 1464  *      VM_ALLOC_SBUSY          shared busy the allocated page
 1465  *      VM_ALLOC_WIRED          wire the allocated page
 1466  *      VM_ALLOC_ZERO           prefer a zeroed page
 1467  *
 1468  *      This routine may not sleep.
 1469  */
 1470 vm_page_t
 1471 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
 1472 {
 1473         struct vnode *vp = NULL;
 1474         vm_object_t m_object;
 1475         vm_page_t m, mpred;
 1476         int flags, req_class;
 1477 
 1478         mpred = 0;      /* XXX: pacify gcc */
 1479         KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0) &&
 1480             (object != NULL || (req & VM_ALLOC_SBUSY) == 0) &&
 1481             ((req & (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)) !=
 1482             (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)),
 1483             ("vm_page_alloc: inconsistent object(%p)/req(%x)", (void *)object,
 1484             req));
 1485         if (object != NULL)
 1486                 VM_OBJECT_ASSERT_WLOCKED(object);
 1487 
 1488         req_class = req & VM_ALLOC_CLASS_MASK;
 1489 
 1490         /*
 1491          * The page daemon is allowed to dig deeper into the free page list.
 1492          */
 1493         if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
 1494                 req_class = VM_ALLOC_SYSTEM;
 1495 
 1496         if (object != NULL) {
 1497                 mpred = vm_radix_lookup_le(&object->rtree, pindex);
 1498                 KASSERT(mpred == NULL || mpred->pindex != pindex,
 1499                    ("vm_page_alloc: pindex already allocated"));
 1500         }
 1501 
 1502         /*
 1503          * The page allocation request can came from consumers which already
 1504          * hold the free page queue mutex, like vm_page_insert() in
 1505          * vm_page_cache().
 1506          */
 1507         mtx_lock_flags(&vm_page_queue_free_mtx, MTX_RECURSE);
 1508         if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
 1509             (req_class == VM_ALLOC_SYSTEM &&
 1510             cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
 1511             (req_class == VM_ALLOC_INTERRUPT &&
 1512             cnt.v_free_count + cnt.v_cache_count > 0)) {
 1513                 /*
 1514                  * Allocate from the free queue if the number of free pages
 1515                  * exceeds the minimum for the request class.
 1516                  */
 1517                 if (object != NULL &&
 1518                     (m = vm_page_cache_lookup(object, pindex)) != NULL) {
 1519                         if ((req & VM_ALLOC_IFNOTCACHED) != 0) {
 1520                                 mtx_unlock(&vm_page_queue_free_mtx);
 1521                                 return (NULL);
 1522                         }
 1523                         if (vm_phys_unfree_page(m))
 1524                                 vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0);
 1525 #if VM_NRESERVLEVEL > 0
 1526                         else if (!vm_reserv_reactivate_page(m))
 1527 #else
 1528                         else
 1529 #endif
 1530                                 panic("vm_page_alloc: cache page %p is missing"
 1531                                     " from the free queue", m);
 1532                 } else if ((req & VM_ALLOC_IFCACHED) != 0) {
 1533                         mtx_unlock(&vm_page_queue_free_mtx);
 1534                         return (NULL);
 1535 #if VM_NRESERVLEVEL > 0
 1536                 } else if (object == NULL || (object->flags & (OBJ_COLORED |
 1537                     OBJ_FICTITIOUS)) != OBJ_COLORED || (m =
 1538                     vm_reserv_alloc_page(object, pindex, mpred)) == NULL) {
 1539 #else
 1540                 } else {
 1541 #endif
 1542                         m = vm_phys_alloc_pages(object != NULL ?
 1543                             VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0);
 1544 #if VM_NRESERVLEVEL > 0
 1545                         if (m == NULL && vm_reserv_reclaim_inactive()) {
 1546                                 m = vm_phys_alloc_pages(object != NULL ?
 1547                                     VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT,
 1548                                     0);
 1549                         }
 1550 #endif
 1551                 }
 1552         } else {
 1553                 /*
 1554                  * Not allocatable, give up.
 1555                  */
 1556                 mtx_unlock(&vm_page_queue_free_mtx);
 1557                 atomic_add_int(&vm_pageout_deficit,
 1558                     max((u_int)req >> VM_ALLOC_COUNT_SHIFT, 1));
 1559                 pagedaemon_wakeup();
 1560                 return (NULL);
 1561         }
 1562 
 1563         /*
 1564          *  At this point we had better have found a good page.
 1565          */
 1566         KASSERT(m != NULL, ("vm_page_alloc: missing page"));
 1567         KASSERT(m->queue == PQ_NONE,
 1568             ("vm_page_alloc: page %p has unexpected queue %d", m, m->queue));
 1569         KASSERT(m->wire_count == 0, ("vm_page_alloc: page %p is wired", m));
 1570         KASSERT(m->hold_count == 0, ("vm_page_alloc: page %p is held", m));
 1571         KASSERT(!vm_page_sbusied(m), 
 1572             ("vm_page_alloc: page %p is busy", m));
 1573         KASSERT(m->dirty == 0, ("vm_page_alloc: page %p is dirty", m));
 1574         KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
 1575             ("vm_page_alloc: page %p has unexpected memattr %d", m,
 1576             pmap_page_get_memattr(m)));
 1577         if ((m->flags & PG_CACHED) != 0) {
 1578                 KASSERT((m->flags & PG_ZERO) == 0,
 1579                     ("vm_page_alloc: cached page %p is PG_ZERO", m));
 1580                 KASSERT(m->valid != 0,
 1581                     ("vm_page_alloc: cached page %p is invalid", m));
 1582                 if (m->object == object && m->pindex == pindex)
 1583                         cnt.v_reactivated++;
 1584                 else
 1585                         m->valid = 0;
 1586                 m_object = m->object;
 1587                 vm_page_cache_remove(m);
 1588                 if (m_object->type == OBJT_VNODE &&
 1589                     vm_object_cache_is_empty(m_object))
 1590                         vp = m_object->handle;
 1591         } else {
 1592                 KASSERT(VM_PAGE_IS_FREE(m),
 1593                     ("vm_page_alloc: page %p is not free", m));
 1594                 KASSERT(m->valid == 0,
 1595                     ("vm_page_alloc: free page %p is valid", m));
 1596                 vm_phys_freecnt_adj(m, -1);
 1597         }
 1598 
 1599         /*
 1600          * Only the PG_ZERO flag is inherited.  The PG_CACHED or PG_FREE flag
 1601          * must be cleared before the free page queues lock is released.
 1602          */
 1603         flags = 0;
 1604         if (m->flags & PG_ZERO) {
 1605                 vm_page_zero_count--;
 1606                 if (req & VM_ALLOC_ZERO)
 1607                         flags = PG_ZERO;
 1608         }
 1609         if (req & VM_ALLOC_NODUMP)
 1610                 flags |= PG_NODUMP;
 1611         m->flags = flags;
 1612         mtx_unlock(&vm_page_queue_free_mtx);
 1613         m->aflags = 0;
 1614         m->oflags = object == NULL || (object->flags & OBJ_UNMANAGED) != 0 ?
 1615             VPO_UNMANAGED : 0;
 1616         m->busy_lock = VPB_UNBUSIED;
 1617         if ((req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ | VM_ALLOC_SBUSY)) == 0)
 1618                 m->busy_lock = VPB_SINGLE_EXCLUSIVER;
 1619         if ((req & VM_ALLOC_SBUSY) != 0)
 1620                 m->busy_lock = VPB_SHARERS_WORD(1);
 1621         if (req & VM_ALLOC_WIRED) {
 1622                 /*
 1623                  * The page lock is not required for wiring a page until that
 1624                  * page is inserted into the object.
 1625                  */
 1626                 atomic_add_int(&cnt.v_wire_count, 1);
 1627                 m->wire_count = 1;
 1628         }
 1629         m->act_count = 0;
 1630 
 1631         if (object != NULL) {
 1632                 if (vm_page_insert_after(m, object, pindex, mpred)) {
 1633                         /* See the comment below about hold count. */
 1634                         if (vp != NULL)
 1635                                 vdrop(vp);
 1636                         pagedaemon_wakeup();
 1637                         if (req & VM_ALLOC_WIRED) {
 1638                                 atomic_subtract_int(&cnt.v_wire_count, 1);
 1639                                 m->wire_count = 0;
 1640                         }
 1641                         m->object = NULL;
 1642                         m->oflags = VPO_UNMANAGED;
 1643                         vm_page_free(m);
 1644                         return (NULL);
 1645                 }
 1646 
 1647                 /* Ignore device objects; the pager sets "memattr" for them. */
 1648                 if (object->memattr != VM_MEMATTR_DEFAULT &&
 1649                     (object->flags & OBJ_FICTITIOUS) == 0)
 1650                         pmap_page_set_memattr(m, object->memattr);
 1651         } else
 1652                 m->pindex = pindex;
 1653 
 1654         /*
 1655          * The following call to vdrop() must come after the above call
 1656          * to vm_page_insert() in case both affect the same object and
 1657          * vnode.  Otherwise, the affected vnode's hold count could
 1658          * temporarily become zero.
 1659          */
 1660         if (vp != NULL)
 1661                 vdrop(vp);
 1662 
 1663         /*
 1664          * Don't wakeup too often - wakeup the pageout daemon when
 1665          * we would be nearly out of memory.
 1666          */
 1667         if (vm_paging_needed())
 1668                 pagedaemon_wakeup();
 1669 
 1670         return (m);
 1671 }
 1672 
 1673 static void
 1674 vm_page_alloc_contig_vdrop(struct spglist *lst)
 1675 {
 1676 
 1677         while (!SLIST_EMPTY(lst)) {
 1678                 vdrop((struct vnode *)SLIST_FIRST(lst)-> plinks.s.pv);
 1679                 SLIST_REMOVE_HEAD(lst, plinks.s.ss);
 1680         }
 1681 }
 1682 
 1683 /*
 1684  *      vm_page_alloc_contig:
 1685  *
 1686  *      Allocate a contiguous set of physical pages of the given size "npages"
 1687  *      from the free lists.  All of the physical pages must be at or above
 1688  *      the given physical address "low" and below the given physical address
 1689  *      "high".  The given value "alignment" determines the alignment of the
 1690  *      first physical page in the set.  If the given value "boundary" is
 1691  *      non-zero, then the set of physical pages cannot cross any physical
 1692  *      address boundary that is a multiple of that value.  Both "alignment"
 1693  *      and "boundary" must be a power of two.
 1694  *
 1695  *      If the specified memory attribute, "memattr", is VM_MEMATTR_DEFAULT,
 1696  *      then the memory attribute setting for the physical pages is configured
 1697  *      to the object's memory attribute setting.  Otherwise, the memory
 1698  *      attribute setting for the physical pages is configured to "memattr",
 1699  *      overriding the object's memory attribute setting.  However, if the
 1700  *      object's memory attribute setting is not VM_MEMATTR_DEFAULT, then the
 1701  *      memory attribute setting for the physical pages cannot be configured
 1702  *      to VM_MEMATTR_DEFAULT.
 1703  *
 1704  *      The caller must always specify an allocation class.
 1705  *
 1706  *      allocation classes:
 1707  *      VM_ALLOC_NORMAL         normal process request
 1708  *      VM_ALLOC_SYSTEM         system *really* needs a page
 1709  *      VM_ALLOC_INTERRUPT      interrupt time request
 1710  *
 1711  *      optional allocation flags:
 1712  *      VM_ALLOC_NOBUSY         do not exclusive busy the page
 1713  *      VM_ALLOC_NODUMP         do not include the page in a kernel core dump
 1714  *      VM_ALLOC_NOOBJ          page is not associated with an object and
 1715  *                              should not be exclusive busy 
 1716  *      VM_ALLOC_SBUSY          shared busy the allocated page
 1717  *      VM_ALLOC_WIRED          wire the allocated page
 1718  *      VM_ALLOC_ZERO           prefer a zeroed page
 1719  *
 1720  *      This routine may not sleep.
 1721  */
 1722 vm_page_t
 1723 vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
 1724     u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
 1725     vm_paddr_t boundary, vm_memattr_t memattr)
 1726 {
 1727         struct vnode *drop;
 1728         struct spglist deferred_vdrop_list;
 1729         vm_page_t m, m_tmp, m_ret;
 1730         u_int flags, oflags;
 1731         int req_class;
 1732 
 1733         KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0) &&
 1734             (object != NULL || (req & VM_ALLOC_SBUSY) == 0) &&
 1735             ((req & (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)) !=
 1736             (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)),
 1737             ("vm_page_alloc: inconsistent object(%p)/req(%x)", (void *)object,
 1738             req));
 1739         if (object != NULL) {
 1740                 VM_OBJECT_ASSERT_WLOCKED(object);
 1741                 KASSERT(object->type == OBJT_PHYS,
 1742                     ("vm_page_alloc_contig: object %p isn't OBJT_PHYS",
 1743                     object));
 1744         }
 1745         KASSERT(npages > 0, ("vm_page_alloc_contig: npages is zero"));
 1746         req_class = req & VM_ALLOC_CLASS_MASK;
 1747 
 1748         /*
 1749          * The page daemon is allowed to dig deeper into the free page list.
 1750          */
 1751         if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
 1752                 req_class = VM_ALLOC_SYSTEM;
 1753 
 1754         SLIST_INIT(&deferred_vdrop_list);
 1755         mtx_lock(&vm_page_queue_free_mtx);
 1756         if (cnt.v_free_count + cnt.v_cache_count >= npages +
 1757             cnt.v_free_reserved || (req_class == VM_ALLOC_SYSTEM &&
 1758             cnt.v_free_count + cnt.v_cache_count >= npages +
 1759             cnt.v_interrupt_free_min) || (req_class == VM_ALLOC_INTERRUPT &&
 1760             cnt.v_free_count + cnt.v_cache_count >= npages)) {
 1761 #if VM_NRESERVLEVEL > 0
 1762 retry:
 1763                 if (object == NULL || (object->flags & OBJ_COLORED) == 0 ||
 1764                     (m_ret = vm_reserv_alloc_contig(object, pindex, npages,
 1765                     low, high, alignment, boundary)) == NULL)
 1766 #endif
 1767                         m_ret = vm_phys_alloc_contig(npages, low, high,
 1768                             alignment, boundary);
 1769         } else {
 1770                 mtx_unlock(&vm_page_queue_free_mtx);
 1771                 atomic_add_int(&vm_pageout_deficit, npages);
 1772                 pagedaemon_wakeup();
 1773                 return (NULL);
 1774         }
 1775         if (m_ret != NULL)
 1776                 for (m = m_ret; m < &m_ret[npages]; m++) {
 1777                         drop = vm_page_alloc_init(m);
 1778                         if (drop != NULL) {
 1779                                 /*
 1780                                  * Enqueue the vnode for deferred vdrop().
 1781                                  */
 1782                                 m->plinks.s.pv = drop;
 1783                                 SLIST_INSERT_HEAD(&deferred_vdrop_list, m,
 1784                                     plinks.s.ss);
 1785                         }
 1786                 }
 1787         else {
 1788 #if VM_NRESERVLEVEL > 0
 1789                 if (vm_reserv_reclaim_contig(npages, low, high, alignment,
 1790                     boundary))
 1791                         goto retry;
 1792 #endif
 1793         }
 1794         mtx_unlock(&vm_page_queue_free_mtx);
 1795         if (m_ret == NULL)
 1796                 return (NULL);
 1797 
 1798         /*
 1799          * Initialize the pages.  Only the PG_ZERO flag is inherited.
 1800          */
 1801         flags = 0;
 1802         if ((req & VM_ALLOC_ZERO) != 0)
 1803                 flags = PG_ZERO;
 1804         if ((req & VM_ALLOC_NODUMP) != 0)
 1805                 flags |= PG_NODUMP;
 1806         if ((req & VM_ALLOC_WIRED) != 0)
 1807                 atomic_add_int(&cnt.v_wire_count, npages);
 1808         oflags = VPO_UNMANAGED;
 1809         if (object != NULL) {
 1810                 if (object->memattr != VM_MEMATTR_DEFAULT &&
 1811                     memattr == VM_MEMATTR_DEFAULT)
 1812                         memattr = object->memattr;
 1813         }
 1814         for (m = m_ret; m < &m_ret[npages]; m++) {
 1815                 m->aflags = 0;
 1816                 m->flags = (m->flags | PG_NODUMP) & flags;
 1817                 m->busy_lock = VPB_UNBUSIED;
 1818                 if (object != NULL) {
 1819                         if ((req & (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)) == 0)
 1820                                 m->busy_lock = VPB_SINGLE_EXCLUSIVER;
 1821                         if ((req & VM_ALLOC_SBUSY) != 0)
 1822                                 m->busy_lock = VPB_SHARERS_WORD(1);
 1823                 }
 1824                 if ((req & VM_ALLOC_WIRED) != 0)
 1825                         m->wire_count = 1;
 1826                 /* Unmanaged pages don't use "act_count". */
 1827                 m->oflags = oflags;
 1828                 if (object != NULL) {
 1829                         if (vm_page_insert(m, object, pindex)) {
 1830                                 vm_page_alloc_contig_vdrop(
 1831                                     &deferred_vdrop_list);
 1832                                 if (vm_paging_needed())
 1833                                         pagedaemon_wakeup();
 1834                                 if ((req & VM_ALLOC_WIRED) != 0)
 1835                                         atomic_subtract_int(&cnt.v_wire_count,
 1836                                             npages);
 1837                                 for (m_tmp = m, m = m_ret;
 1838                                     m < &m_ret[npages]; m++) {
 1839                                         if ((req & VM_ALLOC_WIRED) != 0)
 1840                                                 m->wire_count = 0;
 1841                                         if (m >= m_tmp)
 1842                                                 m->object = NULL;
 1843                                         vm_page_free(m);
 1844                                 }
 1845                                 return (NULL);
 1846                         }
 1847                 } else
 1848                         m->pindex = pindex;
 1849                 if (memattr != VM_MEMATTR_DEFAULT)
 1850                         pmap_page_set_memattr(m, memattr);
 1851                 pindex++;
 1852         }
 1853         vm_page_alloc_contig_vdrop(&deferred_vdrop_list);
 1854         if (vm_paging_needed())
 1855                 pagedaemon_wakeup();
 1856         return (m_ret);
 1857 }
 1858 
 1859 /*
 1860  * Initialize a page that has been freshly dequeued from a freelist.
 1861  * The caller has to drop the vnode returned, if it is not NULL.
 1862  *
 1863  * This function may only be used to initialize unmanaged pages.
 1864  *
 1865  * To be called with vm_page_queue_free_mtx held.
 1866  */
 1867 static struct vnode *
 1868 vm_page_alloc_init(vm_page_t m)
 1869 {
 1870         struct vnode *drop;
 1871         vm_object_t m_object;
 1872 
 1873         KASSERT(m->queue == PQ_NONE,
 1874             ("vm_page_alloc_init: page %p has unexpected queue %d",
 1875             m, m->queue));
 1876         KASSERT(m->wire_count == 0,
 1877             ("vm_page_alloc_init: page %p is wired", m));
 1878         KASSERT(m->hold_count == 0,
 1879             ("vm_page_alloc_init: page %p is held", m));
 1880         KASSERT(!vm_page_sbusied(m),
 1881             ("vm_page_alloc_init: page %p is busy", m));
 1882         KASSERT(m->dirty == 0,
 1883             ("vm_page_alloc_init: page %p is dirty", m));
 1884         KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
 1885             ("vm_page_alloc_init: page %p has unexpected memattr %d",
 1886             m, pmap_page_get_memattr(m)));
 1887         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 1888         drop = NULL;
 1889         if ((m->flags & PG_CACHED) != 0) {
 1890                 KASSERT((m->flags & PG_ZERO) == 0,
 1891                     ("vm_page_alloc_init: cached page %p is PG_ZERO", m));
 1892                 m->valid = 0;
 1893                 m_object = m->object;
 1894                 vm_page_cache_remove(m);
 1895                 if (m_object->type == OBJT_VNODE &&
 1896                     vm_object_cache_is_empty(m_object))
 1897                         drop = m_object->handle;
 1898         } else {
 1899                 KASSERT(VM_PAGE_IS_FREE(m),
 1900                     ("vm_page_alloc_init: page %p is not free", m));
 1901                 KASSERT(m->valid == 0,
 1902                     ("vm_page_alloc_init: free page %p is valid", m));
 1903                 vm_phys_freecnt_adj(m, -1);
 1904                 if ((m->flags & PG_ZERO) != 0)
 1905                         vm_page_zero_count--;
 1906         }
 1907         /* Don't clear the PG_ZERO flag; we'll need it later. */
 1908         m->flags &= PG_ZERO;
 1909         return (drop);
 1910 }
 1911 
 1912 /*
 1913  *      vm_page_alloc_freelist:
 1914  *
 1915  *      Allocate a physical page from the specified free page list.
 1916  *
 1917  *      The caller must always specify an allocation class.
 1918  *
 1919  *      allocation classes:
 1920  *      VM_ALLOC_NORMAL         normal process request
 1921  *      VM_ALLOC_SYSTEM         system *really* needs a page
 1922  *      VM_ALLOC_INTERRUPT      interrupt time request
 1923  *
 1924  *      optional allocation flags:
 1925  *      VM_ALLOC_COUNT(number)  the number of additional pages that the caller
 1926  *                              intends to allocate
 1927  *      VM_ALLOC_WIRED          wire the allocated page
 1928  *      VM_ALLOC_ZERO           prefer a zeroed page
 1929  *
 1930  *      This routine may not sleep.
 1931  */
 1932 vm_page_t
 1933 vm_page_alloc_freelist(int flind, int req)
 1934 {
 1935         struct vnode *drop;
 1936         vm_page_t m;
 1937         u_int flags;
 1938         int req_class;
 1939 
 1940         req_class = req & VM_ALLOC_CLASS_MASK;
 1941 
 1942         /*
 1943          * The page daemon is allowed to dig deeper into the free page list.
 1944          */
 1945         if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
 1946                 req_class = VM_ALLOC_SYSTEM;
 1947 
 1948         /*
 1949          * Do not allocate reserved pages unless the req has asked for it.
 1950          */
 1951         mtx_lock_flags(&vm_page_queue_free_mtx, MTX_RECURSE);
 1952         if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
 1953             (req_class == VM_ALLOC_SYSTEM &&
 1954             cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
 1955             (req_class == VM_ALLOC_INTERRUPT &&
 1956             cnt.v_free_count + cnt.v_cache_count > 0))
 1957                 m = vm_phys_alloc_freelist_pages(flind, VM_FREEPOOL_DIRECT, 0);
 1958         else {
 1959                 mtx_unlock(&vm_page_queue_free_mtx);
 1960                 atomic_add_int(&vm_pageout_deficit,
 1961                     max((u_int)req >> VM_ALLOC_COUNT_SHIFT, 1));
 1962                 pagedaemon_wakeup();
 1963                 return (NULL);
 1964         }
 1965         if (m == NULL) {
 1966                 mtx_unlock(&vm_page_queue_free_mtx);
 1967                 return (NULL);
 1968         }
 1969         drop = vm_page_alloc_init(m);
 1970         mtx_unlock(&vm_page_queue_free_mtx);
 1971 
 1972         /*
 1973          * Initialize the page.  Only the PG_ZERO flag is inherited.
 1974          */
 1975         m->aflags = 0;
 1976         flags = 0;
 1977         if ((req & VM_ALLOC_ZERO) != 0)
 1978                 flags = PG_ZERO;
 1979         m->flags &= flags;
 1980         if ((req & VM_ALLOC_WIRED) != 0) {
 1981                 /*
 1982                  * The page lock is not required for wiring a page that does
 1983                  * not belong to an object.
 1984                  */
 1985                 atomic_add_int(&cnt.v_wire_count, 1);
 1986                 m->wire_count = 1;
 1987         }
 1988         /* Unmanaged pages don't use "act_count". */
 1989         m->oflags = VPO_UNMANAGED;
 1990         if (drop != NULL)
 1991                 vdrop(drop);
 1992         if (vm_paging_needed())
 1993                 pagedaemon_wakeup();
 1994         return (m);
 1995 }
 1996 
 1997 /*
 1998  *      vm_wait:        (also see VM_WAIT macro)
 1999  *
 2000  *      Sleep until free pages are available for allocation.
 2001  *      - Called in various places before memory allocations.
 2002  */
 2003 void
 2004 vm_wait(void)
 2005 {
 2006 
 2007         mtx_lock(&vm_page_queue_free_mtx);
 2008         if (curproc == pageproc) {
 2009                 vm_pageout_pages_needed = 1;
 2010                 msleep(&vm_pageout_pages_needed, &vm_page_queue_free_mtx,
 2011                     PDROP | PSWP, "VMWait", 0);
 2012         } else {
 2013                 if (!vm_pages_needed) {
 2014                         vm_pages_needed = 1;
 2015                         wakeup(&vm_pages_needed);
 2016                 }
 2017                 msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PVM,
 2018                     "vmwait", 0);
 2019         }
 2020 }
 2021 
 2022 /*
 2023  *      vm_waitpfault:  (also see VM_WAITPFAULT macro)
 2024  *
 2025  *      Sleep until free pages are available for allocation.
 2026  *      - Called only in vm_fault so that processes page faulting
 2027  *        can be easily tracked.
 2028  *      - Sleeps at a lower priority than vm_wait() so that vm_wait()ing
 2029  *        processes will be able to grab memory first.  Do not change
 2030  *        this balance without careful testing first.
 2031  */
 2032 void
 2033 vm_waitpfault(void)
 2034 {
 2035 
 2036         mtx_lock(&vm_page_queue_free_mtx);
 2037         if (!vm_pages_needed) {
 2038                 vm_pages_needed = 1;
 2039                 wakeup(&vm_pages_needed);
 2040         }
 2041         msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PUSER,
 2042             "pfault", 0);
 2043 }
 2044 
 2045 struct vm_pagequeue *
 2046 vm_page_pagequeue(vm_page_t m)
 2047 {
 2048 
 2049         return (&vm_phys_domain(m)->vmd_pagequeues[m->queue]);
 2050 }
 2051 
 2052 /*
 2053  *      vm_page_dequeue:
 2054  *
 2055  *      Remove the given page from its current page queue.
 2056  *
 2057  *      The page must be locked.
 2058  */
 2059 void
 2060 vm_page_dequeue(vm_page_t m)
 2061 {
 2062         struct vm_pagequeue *pq;
 2063 
 2064         vm_page_lock_assert(m, MA_OWNED);
 2065         KASSERT(m->queue != PQ_NONE,
 2066             ("vm_page_dequeue: page %p is not queued", m));
 2067         pq = vm_page_pagequeue(m);
 2068         vm_pagequeue_lock(pq);
 2069         m->queue = PQ_NONE;
 2070         TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
 2071         vm_pagequeue_cnt_dec(pq);
 2072         vm_pagequeue_unlock(pq);
 2073 }
 2074 
 2075 /*
 2076  *      vm_page_dequeue_locked:
 2077  *
 2078  *      Remove the given page from its current page queue.
 2079  *
 2080  *      The page and page queue must be locked.
 2081  */
 2082 void
 2083 vm_page_dequeue_locked(vm_page_t m)
 2084 {
 2085         struct vm_pagequeue *pq;
 2086 
 2087         vm_page_lock_assert(m, MA_OWNED);
 2088         pq = vm_page_pagequeue(m);
 2089         vm_pagequeue_assert_locked(pq);
 2090         m->queue = PQ_NONE;
 2091         TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
 2092         vm_pagequeue_cnt_dec(pq);
 2093 }
 2094 
 2095 /*
 2096  *      vm_page_enqueue:
 2097  *
 2098  *      Add the given page to the specified page queue.
 2099  *
 2100  *      The page must be locked.
 2101  */
 2102 static void
 2103 vm_page_enqueue(int queue, vm_page_t m)
 2104 {
 2105         struct vm_pagequeue *pq;
 2106 
 2107         vm_page_lock_assert(m, MA_OWNED);
 2108         pq = &vm_phys_domain(m)->vmd_pagequeues[queue];
 2109         vm_pagequeue_lock(pq);
 2110         m->queue = queue;
 2111         TAILQ_INSERT_TAIL(&pq->pq_pl, m, plinks.q);
 2112         vm_pagequeue_cnt_inc(pq);
 2113         vm_pagequeue_unlock(pq);
 2114 }
 2115 
 2116 /*
 2117  *      vm_page_requeue:
 2118  *
 2119  *      Move the given page to the tail of its current page queue.
 2120  *
 2121  *      The page must be locked.
 2122  */
 2123 void
 2124 vm_page_requeue(vm_page_t m)
 2125 {
 2126         struct vm_pagequeue *pq;
 2127 
 2128         vm_page_lock_assert(m, MA_OWNED);
 2129         KASSERT(m->queue != PQ_NONE,
 2130             ("vm_page_requeue: page %p is not queued", m));
 2131         pq = vm_page_pagequeue(m);
 2132         vm_pagequeue_lock(pq);
 2133         TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
 2134         TAILQ_INSERT_TAIL(&pq->pq_pl, m, plinks.q);
 2135         vm_pagequeue_unlock(pq);
 2136 }
 2137 
 2138 /*
 2139  *      vm_page_requeue_locked:
 2140  *
 2141  *      Move the given page to the tail of its current page queue.
 2142  *
 2143  *      The page queue must be locked.
 2144  */
 2145 void
 2146 vm_page_requeue_locked(vm_page_t m)
 2147 {
 2148         struct vm_pagequeue *pq;
 2149 
 2150         KASSERT(m->queue != PQ_NONE,
 2151             ("vm_page_requeue_locked: page %p is not queued", m));
 2152         pq = vm_page_pagequeue(m);
 2153         vm_pagequeue_assert_locked(pq);
 2154         TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
 2155         TAILQ_INSERT_TAIL(&pq->pq_pl, m, plinks.q);
 2156 }
 2157 
 2158 /*
 2159  *      vm_page_activate:
 2160  *
 2161  *      Put the specified page on the active list (if appropriate).
 2162  *      Ensure that act_count is at least ACT_INIT but do not otherwise
 2163  *      mess with it.
 2164  *
 2165  *      The page must be locked.
 2166  */
 2167 void
 2168 vm_page_activate(vm_page_t m)
 2169 {
 2170         int queue;
 2171 
 2172         vm_page_lock_assert(m, MA_OWNED);
 2173         if ((queue = m->queue) != PQ_ACTIVE) {
 2174                 if (m->wire_count == 0 && (m->oflags & VPO_UNMANAGED) == 0) {
 2175                         if (m->act_count < ACT_INIT)
 2176                                 m->act_count = ACT_INIT;
 2177                         if (queue != PQ_NONE)
 2178                                 vm_page_dequeue(m);
 2179                         vm_page_enqueue(PQ_ACTIVE, m);
 2180                 } else
 2181                         KASSERT(queue == PQ_NONE,
 2182                             ("vm_page_activate: wired page %p is queued", m));
 2183         } else {
 2184                 if (m->act_count < ACT_INIT)
 2185                         m->act_count = ACT_INIT;
 2186         }
 2187 }
 2188 
 2189 /*
 2190  *      vm_page_free_wakeup:
 2191  *
 2192  *      Helper routine for vm_page_free_toq() and vm_page_cache().  This
 2193  *      routine is called when a page has been added to the cache or free
 2194  *      queues.
 2195  *
 2196  *      The page queues must be locked.
 2197  */
 2198 static inline void
 2199 vm_page_free_wakeup(void)
 2200 {
 2201 
 2202         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 2203         /*
 2204          * if pageout daemon needs pages, then tell it that there are
 2205          * some free.
 2206          */
 2207         if (vm_pageout_pages_needed &&
 2208             cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) {
 2209                 wakeup(&vm_pageout_pages_needed);
 2210                 vm_pageout_pages_needed = 0;
 2211         }
 2212         /*
 2213          * wakeup processes that are waiting on memory if we hit a
 2214          * high water mark. And wakeup scheduler process if we have
 2215          * lots of memory. this process will swapin processes.
 2216          */
 2217         if (vm_pages_needed && !vm_page_count_min()) {
 2218                 vm_pages_needed = 0;
 2219                 wakeup(&cnt.v_free_count);
 2220         }
 2221 }
 2222 
 2223 /*
 2224  *      Turn a cached page into a free page, by changing its attributes.
 2225  *      Keep the statistics up-to-date.
 2226  *
 2227  *      The free page queue must be locked.
 2228  */
 2229 static void
 2230 vm_page_cache_turn_free(vm_page_t m)
 2231 {
 2232 
 2233         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 2234 
 2235         m->object = NULL;
 2236         m->valid = 0;
 2237         /* Clear PG_CACHED and set PG_FREE. */
 2238         m->flags ^= PG_CACHED | PG_FREE;
 2239         KASSERT((m->flags & (PG_CACHED | PG_FREE)) == PG_FREE,
 2240             ("vm_page_cache_free: page %p has inconsistent flags", m));
 2241         cnt.v_cache_count--;
 2242         vm_phys_freecnt_adj(m, 1);
 2243 }
 2244 
 2245 /*
 2246  *      vm_page_free_toq:
 2247  *
 2248  *      Returns the given page to the free list,
 2249  *      disassociating it with any VM object.
 2250  *
 2251  *      The object must be locked.  The page must be locked if it is managed.
 2252  */
 2253 void
 2254 vm_page_free_toq(vm_page_t m)
 2255 {
 2256 
 2257         if ((m->oflags & VPO_UNMANAGED) == 0) {
 2258                 vm_page_lock_assert(m, MA_OWNED);
 2259                 KASSERT(!pmap_page_is_mapped(m),
 2260                     ("vm_page_free_toq: freeing mapped page %p", m));
 2261         } else
 2262                 KASSERT(m->queue == PQ_NONE,
 2263                     ("vm_page_free_toq: unmanaged page %p is queued", m));
 2264         PCPU_INC(cnt.v_tfree);
 2265 
 2266         if (VM_PAGE_IS_FREE(m))
 2267                 panic("vm_page_free: freeing free page %p", m);
 2268         else if (vm_page_sbusied(m))
 2269                 panic("vm_page_free: freeing busy page %p", m);
 2270 
 2271         /*
 2272          * Unqueue, then remove page.  Note that we cannot destroy
 2273          * the page here because we do not want to call the pager's
 2274          * callback routine until after we've put the page on the
 2275          * appropriate free queue.
 2276          */
 2277         vm_page_remque(m);
 2278         vm_page_remove(m);
 2279 
 2280         /*
 2281          * If fictitious remove object association and
 2282          * return, otherwise delay object association removal.
 2283          */
 2284         if ((m->flags & PG_FICTITIOUS) != 0) {
 2285                 return;
 2286         }
 2287 
 2288         m->valid = 0;
 2289         vm_page_undirty(m);
 2290 
 2291         if (m->wire_count != 0)
 2292                 panic("vm_page_free: freeing wired page %p", m);
 2293         if (m->hold_count != 0) {
 2294                 m->flags &= ~PG_ZERO;
 2295                 KASSERT((m->flags & PG_UNHOLDFREE) == 0,
 2296                     ("vm_page_free: freeing PG_UNHOLDFREE page %p", m));
 2297                 m->flags |= PG_UNHOLDFREE;
 2298         } else {
 2299                 /*
 2300                  * Restore the default memory attribute to the page.
 2301                  */
 2302                 if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
 2303                         pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
 2304 
 2305                 /*
 2306                  * Insert the page into the physical memory allocator's
 2307                  * cache/free page queues.
 2308                  */
 2309                 mtx_lock(&vm_page_queue_free_mtx);
 2310                 m->flags |= PG_FREE;
 2311                 vm_phys_freecnt_adj(m, 1);
 2312 #if VM_NRESERVLEVEL > 0
 2313                 if (!vm_reserv_free_page(m))
 2314 #else
 2315                 if (TRUE)
 2316 #endif
 2317                         vm_phys_free_pages(m, 0);
 2318                 if ((m->flags & PG_ZERO) != 0)
 2319                         ++vm_page_zero_count;
 2320                 else
 2321                         vm_page_zero_idle_wakeup();
 2322                 vm_page_free_wakeup();
 2323                 mtx_unlock(&vm_page_queue_free_mtx);
 2324         }
 2325 }
 2326 
 2327 /*
 2328  *      vm_page_wire:
 2329  *
 2330  *      Mark this page as wired down by yet
 2331  *      another map, removing it from paging queues
 2332  *      as necessary.
 2333  *
 2334  *      If the page is fictitious, then its wire count must remain one.
 2335  *
 2336  *      The page must be locked.
 2337  */
 2338 void
 2339 vm_page_wire(vm_page_t m)
 2340 {
 2341 
 2342         /*
 2343          * Only bump the wire statistics if the page is not already wired,
 2344          * and only unqueue the page if it is on some queue (if it is unmanaged
 2345          * it is already off the queues).
 2346          */
 2347         vm_page_lock_assert(m, MA_OWNED);
 2348         if ((m->flags & PG_FICTITIOUS) != 0) {
 2349                 KASSERT(m->wire_count == 1,
 2350                     ("vm_page_wire: fictitious page %p's wire count isn't one",
 2351                     m));
 2352                 return;
 2353         }
 2354         if (m->wire_count == 0) {
 2355                 KASSERT((m->oflags & VPO_UNMANAGED) == 0 ||
 2356                     m->queue == PQ_NONE,
 2357                     ("vm_page_wire: unmanaged page %p is queued", m));
 2358                 vm_page_remque(m);
 2359                 atomic_add_int(&cnt.v_wire_count, 1);
 2360         }
 2361         m->wire_count++;
 2362         KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m));
 2363 }
 2364 
 2365 /*
 2366  * vm_page_unwire:
 2367  *
 2368  * Release one wiring of the specified page, potentially enabling it to be
 2369  * paged again.  If paging is enabled, then the value of the parameter
 2370  * "activate" determines to which queue the page is added.  If "activate" is
 2371  * non-zero, then the page is added to the active queue.  Otherwise, it is
 2372  * added to the inactive queue.
 2373  *
 2374  * However, unless the page belongs to an object, it is not enqueued because
 2375  * it cannot be paged out.
 2376  *
 2377  * If a page is fictitious, then its wire count must always be one.
 2378  *
 2379  * A managed page must be locked.
 2380  */
 2381 void
 2382 vm_page_unwire(vm_page_t m, int activate)
 2383 {
 2384 
 2385         if ((m->oflags & VPO_UNMANAGED) == 0)
 2386                 vm_page_lock_assert(m, MA_OWNED);
 2387         if ((m->flags & PG_FICTITIOUS) != 0) {
 2388                 KASSERT(m->wire_count == 1,
 2389             ("vm_page_unwire: fictitious page %p's wire count isn't one", m));
 2390                 return;
 2391         }
 2392         if (m->wire_count > 0) {
 2393                 m->wire_count--;
 2394                 if (m->wire_count == 0) {
 2395                         atomic_subtract_int(&cnt.v_wire_count, 1);
 2396                         if ((m->oflags & VPO_UNMANAGED) != 0 ||
 2397                             m->object == NULL)
 2398                                 return;
 2399                         if (!activate)
 2400                                 m->flags &= ~PG_WINATCFLS;
 2401                         vm_page_enqueue(activate ? PQ_ACTIVE : PQ_INACTIVE, m);
 2402                 }
 2403         } else
 2404                 panic("vm_page_unwire: page %p's wire count is zero", m);
 2405 }
 2406 
 2407 /*
 2408  * Move the specified page to the inactive queue.
 2409  *
 2410  * Many pages placed on the inactive queue should actually go
 2411  * into the cache, but it is difficult to figure out which.  What
 2412  * we do instead, if the inactive target is well met, is to put
 2413  * clean pages at the head of the inactive queue instead of the tail.
 2414  * This will cause them to be moved to the cache more quickly and
 2415  * if not actively re-referenced, reclaimed more quickly.  If we just
 2416  * stick these pages at the end of the inactive queue, heavy filesystem
 2417  * meta-data accesses can cause an unnecessary paging load on memory bound 
 2418  * processes.  This optimization causes one-time-use metadata to be
 2419  * reused more quickly.
 2420  *
 2421  * Normally athead is 0 resulting in LRU operation.  athead is set
 2422  * to 1 if we want this page to be 'as if it were placed in the cache',
 2423  * except without unmapping it from the process address space.
 2424  *
 2425  * The page must be locked.
 2426  */
 2427 static inline void
 2428 _vm_page_deactivate(vm_page_t m, int athead)
 2429 {
 2430         struct vm_pagequeue *pq;
 2431         int queue;
 2432 
 2433         vm_page_assert_locked(m);
 2434 
 2435         /*
 2436          * Ignore if the page is already inactive, unless it is unlikely to be
 2437          * reactivated.
 2438          */
 2439         if ((queue = m->queue) == PQ_INACTIVE && !athead)
 2440                 return;
 2441         if (m->wire_count == 0 && (m->oflags & VPO_UNMANAGED) == 0) {
 2442                 pq = &vm_phys_domain(m)->vmd_pagequeues[PQ_INACTIVE];
 2443                 /* Avoid multiple acquisitions of the inactive queue lock. */
 2444                 if (queue == PQ_INACTIVE) {
 2445                         vm_pagequeue_lock(pq);
 2446                         vm_page_dequeue_locked(m);
 2447                 } else {
 2448                         if (queue != PQ_NONE)
 2449                                 vm_page_dequeue(m);
 2450                         m->flags &= ~PG_WINATCFLS;
 2451                         vm_pagequeue_lock(pq);
 2452                 }
 2453                 m->queue = PQ_INACTIVE;
 2454                 if (athead)
 2455                         TAILQ_INSERT_HEAD(&pq->pq_pl, m, plinks.q);
 2456                 else
 2457                         TAILQ_INSERT_TAIL(&pq->pq_pl, m, plinks.q);
 2458                 vm_pagequeue_cnt_inc(pq);
 2459                 vm_pagequeue_unlock(pq);
 2460         }
 2461 }
 2462 
 2463 /*
 2464  * Move the specified page to the inactive queue.
 2465  *
 2466  * The page must be locked.
 2467  */
 2468 void
 2469 vm_page_deactivate(vm_page_t m)
 2470 {
 2471 
 2472         _vm_page_deactivate(m, 0);
 2473 }
 2474 
 2475 /*
 2476  * vm_page_try_to_cache:
 2477  *
 2478  * Returns 0 on failure, 1 on success
 2479  */
 2480 int
 2481 vm_page_try_to_cache(vm_page_t m)
 2482 {
 2483 
 2484         vm_page_lock_assert(m, MA_OWNED);
 2485         VM_OBJECT_ASSERT_WLOCKED(m->object);
 2486         if (m->dirty || m->hold_count || m->wire_count ||
 2487             (m->oflags & VPO_UNMANAGED) != 0 || vm_page_busied(m))
 2488                 return (0);
 2489         pmap_remove_all(m);
 2490         if (m->dirty)
 2491                 return (0);
 2492         vm_page_cache(m);
 2493         return (1);
 2494 }
 2495 
 2496 /*
 2497  * vm_page_try_to_free()
 2498  *
 2499  *      Attempt to free the page.  If we cannot free it, we do nothing.
 2500  *      1 is returned on success, 0 on failure.
 2501  */
 2502 int
 2503 vm_page_try_to_free(vm_page_t m)
 2504 {
 2505 
 2506         vm_page_lock_assert(m, MA_OWNED);
 2507         if (m->object != NULL)
 2508                 VM_OBJECT_ASSERT_WLOCKED(m->object);
 2509         if (m->dirty || m->hold_count || m->wire_count ||
 2510             (m->oflags & VPO_UNMANAGED) != 0 || vm_page_busied(m))
 2511                 return (0);
 2512         pmap_remove_all(m);
 2513         if (m->dirty)
 2514                 return (0);
 2515         vm_page_free(m);
 2516         return (1);
 2517 }
 2518 
 2519 /*
 2520  * vm_page_cache
 2521  *
 2522  * Put the specified page onto the page cache queue (if appropriate).
 2523  *
 2524  * The object and page must be locked.
 2525  */
 2526 void
 2527 vm_page_cache(vm_page_t m)
 2528 {
 2529         vm_object_t object;
 2530         boolean_t cache_was_empty;
 2531 
 2532         vm_page_lock_assert(m, MA_OWNED);
 2533         object = m->object;
 2534         VM_OBJECT_ASSERT_WLOCKED(object);
 2535         if (vm_page_busied(m) || (m->oflags & VPO_UNMANAGED) ||
 2536             m->hold_count || m->wire_count)
 2537                 panic("vm_page_cache: attempting to cache busy page");
 2538         KASSERT(!pmap_page_is_mapped(m),
 2539             ("vm_page_cache: page %p is mapped", m));
 2540         KASSERT(m->dirty == 0, ("vm_page_cache: page %p is dirty", m));
 2541         if (m->valid == 0 || object->type == OBJT_DEFAULT ||
 2542             (object->type == OBJT_SWAP &&
 2543             !vm_pager_has_page(object, m->pindex, NULL, NULL))) {
 2544                 /*
 2545                  * Hypothesis: A cache-elgible page belonging to a
 2546                  * default object or swap object but without a backing
 2547                  * store must be zero filled.
 2548                  */
 2549                 vm_page_free(m);
 2550                 return;
 2551         }
 2552         KASSERT((m->flags & PG_CACHED) == 0,
 2553             ("vm_page_cache: page %p is already cached", m));
 2554 
 2555         /*
 2556          * Remove the page from the paging queues.
 2557          */
 2558         vm_page_remque(m);
 2559 
 2560         /*
 2561          * Remove the page from the object's collection of resident
 2562          * pages. 
 2563          */
 2564         vm_radix_remove(&object->rtree, m->pindex);
 2565         TAILQ_REMOVE(&object->memq, m, listq);
 2566         object->resident_page_count--;
 2567 
 2568         /*
 2569          * Restore the default memory attribute to the page.
 2570          */
 2571         if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
 2572                 pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
 2573 
 2574         /*
 2575          * Insert the page into the object's collection of cached pages
 2576          * and the physical memory allocator's cache/free page queues.
 2577          */
 2578         m->flags &= ~PG_ZERO;
 2579         mtx_lock(&vm_page_queue_free_mtx);
 2580         cache_was_empty = vm_radix_is_empty(&object->cache);
 2581         if (vm_radix_insert(&object->cache, m)) {
 2582                 mtx_unlock(&vm_page_queue_free_mtx);
 2583                 if (object->resident_page_count == 0)
 2584                         vdrop(object->handle);
 2585                 m->object = NULL;
 2586                 vm_page_free(m);
 2587                 return;
 2588         }
 2589 
 2590         /*
 2591          * The above call to vm_radix_insert() could reclaim the one pre-
 2592          * existing cached page from this object, resulting in a call to
 2593          * vdrop().
 2594          */
 2595         if (!cache_was_empty)
 2596                 cache_was_empty = vm_radix_is_singleton(&object->cache);
 2597 
 2598         m->flags |= PG_CACHED;
 2599         cnt.v_cache_count++;
 2600         PCPU_INC(cnt.v_tcached);
 2601 #if VM_NRESERVLEVEL > 0
 2602         if (!vm_reserv_free_page(m)) {
 2603 #else
 2604         if (TRUE) {
 2605 #endif
 2606                 vm_phys_set_pool(VM_FREEPOOL_CACHE, m, 0);
 2607                 vm_phys_free_pages(m, 0);
 2608         }
 2609         vm_page_free_wakeup();
 2610         mtx_unlock(&vm_page_queue_free_mtx);
 2611 
 2612         /*
 2613          * Increment the vnode's hold count if this is the object's only
 2614          * cached page.  Decrement the vnode's hold count if this was
 2615          * the object's only resident page.
 2616          */
 2617         if (object->type == OBJT_VNODE) {
 2618                 if (cache_was_empty && object->resident_page_count != 0)
 2619                         vhold(object->handle);
 2620                 else if (!cache_was_empty && object->resident_page_count == 0)
 2621                         vdrop(object->handle);
 2622         }
 2623 }
 2624 
 2625 /*
 2626  * vm_page_advise
 2627  *
 2628  *      Deactivate or do nothing, as appropriate.  This routine is used
 2629  *      by madvise() and vop_stdadvise().
 2630  *
 2631  *      The object and page must be locked.
 2632  */
 2633 void
 2634 vm_page_advise(vm_page_t m, int advice)
 2635 {
 2636 
 2637         vm_page_assert_locked(m);
 2638         VM_OBJECT_ASSERT_WLOCKED(m->object);
 2639         if (advice == MADV_FREE)
 2640                 /*
 2641                  * Mark the page clean.  This will allow the page to be freed
 2642                  * up by the system.  However, such pages are often reused
 2643                  * quickly by malloc() so we do not do anything that would
 2644                  * cause a page fault if we can help it.
 2645                  *
 2646                  * Specifically, we do not try to actually free the page now
 2647                  * nor do we try to put it in the cache (which would cause a
 2648                  * page fault on reuse).
 2649                  *
 2650                  * But we do make the page as freeable as we can without
 2651                  * actually taking the step of unmapping it.
 2652                  */
 2653                 m->dirty = 0;
 2654         else if (advice != MADV_DONTNEED)
 2655                 return;
 2656 
 2657         /*
 2658          * Clear any references to the page.  Otherwise, the page daemon will
 2659          * immediately reactivate the page.
 2660          */
 2661         vm_page_aflag_clear(m, PGA_REFERENCED);
 2662 
 2663         if (advice != MADV_FREE && m->dirty == 0 && pmap_is_modified(m))
 2664                 vm_page_dirty(m);
 2665 
 2666         /*
 2667          * Place clean pages at the head of the inactive queue rather than the
 2668          * tail, thus defeating the queue's LRU operation and ensuring that the
 2669          * page will be reused quickly.
 2670          */
 2671         _vm_page_deactivate(m, m->dirty == 0);
 2672 }
 2673 
 2674 /*
 2675  * Grab a page, waiting until we are waken up due to the page
 2676  * changing state.  We keep on waiting, if the page continues
 2677  * to be in the object.  If the page doesn't exist, first allocate it
 2678  * and then conditionally zero it.
 2679  *
 2680  * This routine may sleep.
 2681  *
 2682  * The object must be locked on entry.  The lock will, however, be released
 2683  * and reacquired if the routine sleeps.
 2684  */
 2685 vm_page_t
 2686 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
 2687 {
 2688         vm_page_t m;
 2689         int sleep;
 2690 
 2691         VM_OBJECT_ASSERT_WLOCKED(object);
 2692         KASSERT((allocflags & VM_ALLOC_SBUSY) == 0 ||
 2693             (allocflags & VM_ALLOC_IGN_SBUSY) != 0,
 2694             ("vm_page_grab: VM_ALLOC_SBUSY/VM_ALLOC_IGN_SBUSY mismatch"));
 2695 retrylookup:
 2696         if ((m = vm_page_lookup(object, pindex)) != NULL) {
 2697                 sleep = (allocflags & VM_ALLOC_IGN_SBUSY) != 0 ?
 2698                     vm_page_xbusied(m) : vm_page_busied(m);
 2699                 if (sleep) {
 2700                         /*
 2701                          * Reference the page before unlocking and
 2702                          * sleeping so that the page daemon is less
 2703                          * likely to reclaim it.
 2704                          */
 2705                         vm_page_aflag_set(m, PGA_REFERENCED);
 2706                         vm_page_lock(m);
 2707                         VM_OBJECT_WUNLOCK(object);
 2708                         vm_page_busy_sleep(m, "pgrbwt");
 2709                         VM_OBJECT_WLOCK(object);
 2710                         goto retrylookup;
 2711                 } else {
 2712                         if ((allocflags & VM_ALLOC_WIRED) != 0) {
 2713                                 vm_page_lock(m);
 2714                                 vm_page_wire(m);
 2715                                 vm_page_unlock(m);
 2716                         }
 2717                         if ((allocflags &
 2718                             (VM_ALLOC_NOBUSY | VM_ALLOC_SBUSY)) == 0)
 2719                                 vm_page_xbusy(m);
 2720                         if ((allocflags & VM_ALLOC_SBUSY) != 0)
 2721                                 vm_page_sbusy(m);
 2722                         return (m);
 2723                 }
 2724         }
 2725         m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_IGN_SBUSY);
 2726         if (m == NULL) {
 2727                 VM_OBJECT_WUNLOCK(object);
 2728                 VM_WAIT;
 2729                 VM_OBJECT_WLOCK(object);
 2730                 goto retrylookup;
 2731         } else if (m->valid != 0)
 2732                 return (m);
 2733         if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0)
 2734                 pmap_zero_page(m);
 2735         return (m);
 2736 }
 2737 
 2738 /*
 2739  * Mapping function for valid or dirty bits in a page.
 2740  *
 2741  * Inputs are required to range within a page.
 2742  */
 2743 vm_page_bits_t
 2744 vm_page_bits(int base, int size)
 2745 {
 2746         int first_bit;
 2747         int last_bit;
 2748 
 2749         KASSERT(
 2750             base + size <= PAGE_SIZE,
 2751             ("vm_page_bits: illegal base/size %d/%d", base, size)
 2752         );
 2753 
 2754         if (size == 0)          /* handle degenerate case */
 2755                 return (0);
 2756 
 2757         first_bit = base >> DEV_BSHIFT;
 2758         last_bit = (base + size - 1) >> DEV_BSHIFT;
 2759 
 2760         return (((vm_page_bits_t)2 << last_bit) -
 2761             ((vm_page_bits_t)1 << first_bit));
 2762 }
 2763 
 2764 /*
 2765  *      vm_page_set_valid_range:
 2766  *
 2767  *      Sets portions of a page valid.  The arguments are expected
 2768  *      to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
 2769  *      of any partial chunks touched by the range.  The invalid portion of
 2770  *      such chunks will be zeroed.
 2771  *
 2772  *      (base + size) must be less then or equal to PAGE_SIZE.
 2773  */
 2774 void
 2775 vm_page_set_valid_range(vm_page_t m, int base, int size)
 2776 {
 2777         int endoff, frag;
 2778 
 2779         VM_OBJECT_ASSERT_WLOCKED(m->object);
 2780         if (size == 0)  /* handle degenerate case */
 2781                 return;
 2782 
 2783         /*
 2784          * If the base is not DEV_BSIZE aligned and the valid
 2785          * bit is clear, we have to zero out a portion of the
 2786          * first block.
 2787          */
 2788         if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
 2789             (m->valid & (1 << (base >> DEV_BSHIFT))) == 0)
 2790                 pmap_zero_page_area(m, frag, base - frag);
 2791 
 2792         /*
 2793          * If the ending offset is not DEV_BSIZE aligned and the 
 2794          * valid bit is clear, we have to zero out a portion of
 2795          * the last block.
 2796          */
 2797         endoff = base + size;
 2798         if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
 2799             (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0)
 2800                 pmap_zero_page_area(m, endoff,
 2801                     DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
 2802 
 2803         /*
 2804          * Assert that no previously invalid block that is now being validated
 2805          * is already dirty. 
 2806          */
 2807         KASSERT((~m->valid & vm_page_bits(base, size) & m->dirty) == 0,
 2808             ("vm_page_set_valid_range: page %p is dirty", m));
 2809 
 2810         /*
 2811          * Set valid bits inclusive of any overlap.
 2812          */
 2813         m->valid |= vm_page_bits(base, size);
 2814 }
 2815 
 2816 /*
 2817  * Clear the given bits from the specified page's dirty field.
 2818  */
 2819 static __inline void
 2820 vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits)
 2821 {
 2822         uintptr_t addr;
 2823 #if PAGE_SIZE < 16384
 2824         int shift;
 2825 #endif
 2826 
 2827         /*
 2828          * If the object is locked and the page is neither exclusive busy nor
 2829          * write mapped, then the page's dirty field cannot possibly be
 2830          * set by a concurrent pmap operation.
 2831          */
 2832         VM_OBJECT_ASSERT_WLOCKED(m->object);
 2833         if (!vm_page_xbusied(m) && !pmap_page_is_write_mapped(m))
 2834                 m->dirty &= ~pagebits;
 2835         else {
 2836                 /*
 2837                  * The pmap layer can call vm_page_dirty() without
 2838                  * holding a distinguished lock.  The combination of
 2839                  * the object's lock and an atomic operation suffice
 2840                  * to guarantee consistency of the page dirty field.
 2841                  *
 2842                  * For PAGE_SIZE == 32768 case, compiler already
 2843                  * properly aligns the dirty field, so no forcible
 2844                  * alignment is needed. Only require existence of
 2845                  * atomic_clear_64 when page size is 32768.
 2846                  */
 2847                 addr = (uintptr_t)&m->dirty;
 2848 #if PAGE_SIZE == 32768
 2849                 atomic_clear_64((uint64_t *)addr, pagebits);
 2850 #elif PAGE_SIZE == 16384
 2851                 atomic_clear_32((uint32_t *)addr, pagebits);
 2852 #else           /* PAGE_SIZE <= 8192 */
 2853                 /*
 2854                  * Use a trick to perform a 32-bit atomic on the
 2855                  * containing aligned word, to not depend on the existence
 2856                  * of atomic_clear_{8, 16}.
 2857                  */
 2858                 shift = addr & (sizeof(uint32_t) - 1);
 2859 #if BYTE_ORDER == BIG_ENDIAN
 2860                 shift = (sizeof(uint32_t) - sizeof(m->dirty) - shift) * NBBY;
 2861 #else
 2862                 shift *= NBBY;
 2863 #endif
 2864                 addr &= ~(sizeof(uint32_t) - 1);
 2865                 atomic_clear_32((uint32_t *)addr, pagebits << shift);
 2866 #endif          /* PAGE_SIZE */
 2867         }
 2868 }
 2869 
 2870 /*
 2871  *      vm_page_set_validclean:
 2872  *
 2873  *      Sets portions of a page valid and clean.  The arguments are expected
 2874  *      to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
 2875  *      of any partial chunks touched by the range.  The invalid portion of
 2876  *      such chunks will be zero'd.
 2877  *
 2878  *      (base + size) must be less then or equal to PAGE_SIZE.
 2879  */
 2880 void
 2881 vm_page_set_validclean(vm_page_t m, int base, int size)
 2882 {
 2883         vm_page_bits_t oldvalid, pagebits;
 2884         int endoff, frag;
 2885 
 2886         VM_OBJECT_ASSERT_WLOCKED(m->object);
 2887         if (size == 0)  /* handle degenerate case */
 2888                 return;
 2889 
 2890         /*
 2891          * If the base is not DEV_BSIZE aligned and the valid
 2892          * bit is clear, we have to zero out a portion of the
 2893          * first block.
 2894          */
 2895         if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
 2896             (m->valid & ((vm_page_bits_t)1 << (base >> DEV_BSHIFT))) == 0)
 2897                 pmap_zero_page_area(m, frag, base - frag);
 2898 
 2899         /*
 2900          * If the ending offset is not DEV_BSIZE aligned and the 
 2901          * valid bit is clear, we have to zero out a portion of
 2902          * the last block.
 2903          */
 2904         endoff = base + size;
 2905         if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
 2906             (m->valid & ((vm_page_bits_t)1 << (endoff >> DEV_BSHIFT))) == 0)
 2907                 pmap_zero_page_area(m, endoff,
 2908                     DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
 2909 
 2910         /*
 2911          * Set valid, clear dirty bits.  If validating the entire
 2912          * page we can safely clear the pmap modify bit.  We also
 2913          * use this opportunity to clear the VPO_NOSYNC flag.  If a process
 2914          * takes a write fault on a MAP_NOSYNC memory area the flag will
 2915          * be set again.
 2916          *
 2917          * We set valid bits inclusive of any overlap, but we can only
 2918          * clear dirty bits for DEV_BSIZE chunks that are fully within
 2919          * the range.
 2920          */
 2921         oldvalid = m->valid;
 2922         pagebits = vm_page_bits(base, size);
 2923         m->valid |= pagebits;
 2924 #if 0   /* NOT YET */
 2925         if ((frag = base & (DEV_BSIZE - 1)) != 0) {
 2926                 frag = DEV_BSIZE - frag;
 2927                 base += frag;
 2928                 size -= frag;
 2929                 if (size < 0)
 2930                         size = 0;
 2931         }
 2932         pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1));
 2933 #endif
 2934         if (base == 0 && size == PAGE_SIZE) {
 2935                 /*
 2936                  * The page can only be modified within the pmap if it is
 2937                  * mapped, and it can only be mapped if it was previously
 2938                  * fully valid.
 2939                  */
 2940                 if (oldvalid == VM_PAGE_BITS_ALL)
 2941                         /*
 2942                          * Perform the pmap_clear_modify() first.  Otherwise,
 2943                          * a concurrent pmap operation, such as
 2944                          * pmap_protect(), could clear a modification in the
 2945                          * pmap and set the dirty field on the page before
 2946                          * pmap_clear_modify() had begun and after the dirty
 2947                          * field was cleared here.
 2948                          */
 2949                         pmap_clear_modify(m);
 2950                 m->dirty = 0;
 2951                 m->oflags &= ~VPO_NOSYNC;
 2952         } else if (oldvalid != VM_PAGE_BITS_ALL)
 2953                 m->dirty &= ~pagebits;
 2954         else
 2955                 vm_page_clear_dirty_mask(m, pagebits);
 2956 }
 2957 
 2958 void
 2959 vm_page_clear_dirty(vm_page_t m, int base, int size)
 2960 {
 2961 
 2962         vm_page_clear_dirty_mask(m, vm_page_bits(base, size));
 2963 }
 2964 
 2965 /*
 2966  *      vm_page_set_invalid:
 2967  *
 2968  *      Invalidates DEV_BSIZE'd chunks within a page.  Both the
 2969  *      valid and dirty bits for the effected areas are cleared.
 2970  */
 2971 void
 2972 vm_page_set_invalid(vm_page_t m, int base, int size)
 2973 {
 2974         vm_page_bits_t bits;
 2975         vm_object_t object;
 2976 
 2977         object = m->object;
 2978         VM_OBJECT_ASSERT_WLOCKED(object);
 2979         if (object->type == OBJT_VNODE && base == 0 && IDX_TO_OFF(m->pindex) +
 2980             size >= object->un_pager.vnp.vnp_size)
 2981                 bits = VM_PAGE_BITS_ALL;
 2982         else
 2983                 bits = vm_page_bits(base, size);
 2984         if (object->ref_count != 0 && m->valid == VM_PAGE_BITS_ALL &&
 2985             bits != 0)
 2986                 pmap_remove_all(m);
 2987         KASSERT((bits == 0 && m->valid == VM_PAGE_BITS_ALL) ||
 2988             !pmap_page_is_mapped(m),
 2989             ("vm_page_set_invalid: page %p is mapped", m));
 2990         m->valid &= ~bits;
 2991         m->dirty &= ~bits;
 2992 }
 2993 
 2994 /*
 2995  * vm_page_zero_invalid()
 2996  *
 2997  *      The kernel assumes that the invalid portions of a page contain 
 2998  *      garbage, but such pages can be mapped into memory by user code.
 2999  *      When this occurs, we must zero out the non-valid portions of the
 3000  *      page so user code sees what it expects.
 3001  *
 3002  *      Pages are most often semi-valid when the end of a file is mapped 
 3003  *      into memory and the file's size is not page aligned.
 3004  */
 3005 void
 3006 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid)
 3007 {
 3008         int b;
 3009         int i;
 3010 
 3011         VM_OBJECT_ASSERT_WLOCKED(m->object);
 3012         /*
 3013          * Scan the valid bits looking for invalid sections that
 3014          * must be zeroed.  Invalid sub-DEV_BSIZE'd areas ( where the
 3015          * valid bit may be set ) have already been zeroed by
 3016          * vm_page_set_validclean().
 3017          */
 3018         for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) {
 3019                 if (i == (PAGE_SIZE / DEV_BSIZE) || 
 3020                     (m->valid & ((vm_page_bits_t)1 << i))) {
 3021                         if (i > b) {
 3022                                 pmap_zero_page_area(m, 
 3023                                     b << DEV_BSHIFT, (i - b) << DEV_BSHIFT);
 3024                         }
 3025                         b = i + 1;
 3026                 }
 3027         }
 3028 
 3029         /*
 3030          * setvalid is TRUE when we can safely set the zero'd areas
 3031          * as being valid.  We can do this if there are no cache consistancy
 3032          * issues.  e.g. it is ok to do with UFS, but not ok to do with NFS.
 3033          */
 3034         if (setvalid)
 3035                 m->valid = VM_PAGE_BITS_ALL;
 3036 }
 3037 
 3038 /*
 3039  *      vm_page_is_valid:
 3040  *
 3041  *      Is (partial) page valid?  Note that the case where size == 0
 3042  *      will return FALSE in the degenerate case where the page is
 3043  *      entirely invalid, and TRUE otherwise.
 3044  */
 3045 int
 3046 vm_page_is_valid(vm_page_t m, int base, int size)
 3047 {
 3048         vm_page_bits_t bits;
 3049 
 3050         VM_OBJECT_ASSERT_LOCKED(m->object);
 3051         bits = vm_page_bits(base, size);
 3052         return (m->valid != 0 && (m->valid & bits) == bits);
 3053 }
 3054 
 3055 /*
 3056  *      vm_page_ps_is_valid:
 3057  *
 3058  *      Returns TRUE if the entire (super)page is valid and FALSE otherwise.
 3059  */
 3060 boolean_t
 3061 vm_page_ps_is_valid(vm_page_t m)
 3062 {
 3063         int i, npages;
 3064 
 3065         VM_OBJECT_ASSERT_LOCKED(m->object);
 3066         npages = atop(pagesizes[m->psind]);
 3067 
 3068         /*
 3069          * The physically contiguous pages that make up a superpage, i.e., a
 3070          * page with a page size index ("psind") greater than zero, will
 3071          * occupy adjacent entries in vm_page_array[].
 3072          */
 3073         for (i = 0; i < npages; i++) {
 3074                 if (m[i].valid != VM_PAGE_BITS_ALL)
 3075                         return (FALSE);
 3076         }
 3077         return (TRUE);
 3078 }
 3079 
 3080 /*
 3081  * Set the page's dirty bits if the page is modified.
 3082  */
 3083 void
 3084 vm_page_test_dirty(vm_page_t m)
 3085 {
 3086 
 3087         VM_OBJECT_ASSERT_WLOCKED(m->object);
 3088         if (m->dirty != VM_PAGE_BITS_ALL && pmap_is_modified(m))
 3089                 vm_page_dirty(m);
 3090 }
 3091 
 3092 void
 3093 vm_page_lock_KBI(vm_page_t m, const char *file, int line)
 3094 {
 3095 
 3096         mtx_lock_flags_(vm_page_lockptr(m), 0, file, line);
 3097 }
 3098 
 3099 void
 3100 vm_page_unlock_KBI(vm_page_t m, const char *file, int line)
 3101 {
 3102 
 3103         mtx_unlock_flags_(vm_page_lockptr(m), 0, file, line);
 3104 }
 3105 
 3106 int
 3107 vm_page_trylock_KBI(vm_page_t m, const char *file, int line)
 3108 {
 3109 
 3110         return (mtx_trylock_flags_(vm_page_lockptr(m), 0, file, line));
 3111 }
 3112 
 3113 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 3114 void
 3115 vm_page_assert_locked_KBI(vm_page_t m, const char *file, int line)
 3116 {
 3117 
 3118         vm_page_lock_assert_KBI(m, MA_OWNED, file, line);
 3119 }
 3120 
 3121 void
 3122 vm_page_lock_assert_KBI(vm_page_t m, int a, const char *file, int line)
 3123 {
 3124 
 3125         mtx_assert_(vm_page_lockptr(m), a, file, line);
 3126 }
 3127 #endif
 3128 
 3129 #ifdef INVARIANTS
 3130 void
 3131 vm_page_object_lock_assert(vm_page_t m)
 3132 {
 3133 
 3134         /*
 3135          * Certain of the page's fields may only be modified by the
 3136          * holder of the containing object's lock or the exclusive busy.
 3137          * holder.  Unfortunately, the holder of the write busy is
 3138          * not recorded, and thus cannot be checked here.
 3139          */
 3140         if (m->object != NULL && !vm_page_xbusied(m))
 3141                 VM_OBJECT_ASSERT_WLOCKED(m->object);
 3142 }
 3143 
 3144 void
 3145 vm_page_assert_pga_writeable(vm_page_t m, uint8_t bits)
 3146 {
 3147 
 3148         if ((bits & PGA_WRITEABLE) == 0)
 3149                 return;
 3150 
 3151         /*
 3152          * The PGA_WRITEABLE flag can only be set if the page is
 3153          * managed, is exclusively busied or the object is locked.
 3154          * Currently, this flag is only set by pmap_enter().
 3155          */
 3156         KASSERT((m->oflags & VPO_UNMANAGED) == 0,
 3157             ("PGA_WRITEABLE on unmanaged page"));
 3158         if (!vm_page_xbusied(m))
 3159                 VM_OBJECT_ASSERT_LOCKED(m->object);
 3160 }
 3161 #endif
 3162 
 3163 #include "opt_ddb.h"
 3164 #ifdef DDB
 3165 #include <sys/kernel.h>
 3166 
 3167 #include <ddb/ddb.h>
 3168 
 3169 DB_SHOW_COMMAND(page, vm_page_print_page_info)
 3170 {
 3171         db_printf("cnt.v_free_count: %d\n", cnt.v_free_count);
 3172         db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count);
 3173         db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count);
 3174         db_printf("cnt.v_active_count: %d\n", cnt.v_active_count);
 3175         db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count);
 3176         db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved);
 3177         db_printf("cnt.v_free_min: %d\n", cnt.v_free_min);
 3178         db_printf("cnt.v_free_target: %d\n", cnt.v_free_target);
 3179         db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min);
 3180         db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target);
 3181 }
 3182 
 3183 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info)
 3184 {
 3185         int dom;
 3186 
 3187         db_printf("pq_free %d pq_cache %d\n",
 3188             cnt.v_free_count, cnt.v_cache_count);
 3189         for (dom = 0; dom < vm_ndomains; dom++) {
 3190                 db_printf(
 3191         "dom %d page_cnt %d free %d pq_act %d pq_inact %d pass %d\n",
 3192                     dom,
 3193                     vm_dom[dom].vmd_page_count,
 3194                     vm_dom[dom].vmd_free_count,
 3195                     vm_dom[dom].vmd_pagequeues[PQ_ACTIVE].pq_cnt,
 3196                     vm_dom[dom].vmd_pagequeues[PQ_INACTIVE].pq_cnt,
 3197                     vm_dom[dom].vmd_pass);
 3198         }
 3199 }
 3200 
 3201 DB_SHOW_COMMAND(pginfo, vm_page_print_pginfo)
 3202 {
 3203         vm_page_t m;
 3204         boolean_t phys;
 3205 
 3206         if (!have_addr) {
 3207                 db_printf("show pginfo addr\n");
 3208                 return;
 3209         }
 3210 
 3211         phys = strchr(modif, 'p') != NULL;
 3212         if (phys)
 3213                 m = PHYS_TO_VM_PAGE(addr);
 3214         else
 3215                 m = (vm_page_t)addr;
 3216         db_printf(
 3217     "page %p obj %p pidx 0x%jx phys 0x%jx q %d hold %d wire %d\n"
 3218     "  af 0x%x of 0x%x f 0x%x act %d busy %x valid 0x%x dirty 0x%x\n",
 3219             m, m->object, (uintmax_t)m->pindex, (uintmax_t)m->phys_addr,
 3220             m->queue, m->hold_count, m->wire_count, m->aflags, m->oflags,
 3221             m->flags, m->act_count, m->busy_lock, m->valid, m->dirty);
 3222 }
 3223 #endif /* DDB */

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