Sync usage with man page.

[netbsd-mini2440.git] / sys / uvm / uvm_page.c

/*      $NetBSD: uvm_page.c,v 1.151 2009/08/18 19:08:39 thorpej Exp $   */

/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * Copyright (c) 1991, 1993, The Regents of the University of California.
 *
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * The Mach Operating System project at Carnegie-Mellon University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Charles D. Cranor,
 *      Washington University, the University of California, Berkeley and
 *      its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vm_page.c   8.3 (Berkeley) 3/21/94
 * from: Id: uvm_page.c,v 1.1.2.18 1998/02/06 05:24:42 chs Exp
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/*
 * uvm_page.c: page ops.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_page.c,v 1.151 2009/08/18 19:08:39 thorpej Exp $");

#include "opt_ddb.h"
#include "opt_uvmhist.h"
#include "opt_readahead.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/sched.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/atomic.h>
#include <sys/cpu.h>

#include <uvm/uvm.h>
#include <uvm/uvm_ddb.h>
#include <uvm/uvm_pdpolicy.h>

/*
 * global vars... XXXCDC: move to uvm. structure.
 */

/*
 * physical memory config is stored in vm_physmem.
 */

struct vm_physseg vm_physmem[VM_PHYSSEG_MAX];   /* XXXCDC: uvm.physmem */
int vm_nphysseg = 0;                            /* XXXCDC: uvm.nphysseg */

/*
 * Some supported CPUs in a given architecture don't support all
 * of the things necessary to do idle page zero'ing efficiently.
 * We therefore provide a way to disable it from machdep code here.
 */
/*
 * XXX disabled until we can find a way to do this without causing
 * problems for either CPU caches or DMA latency.
 */
bool vm_page_zero_enable = false;

/*
 * number of pages per-CPU to reserve for the kernel.
 */
int vm_page_reserve_kernel = 5;

/*
 * physical memory size;
 */
int physmem;

/*
 * local variables
 */

/*
 * these variables record the values returned by vm_page_bootstrap,
 * for debugging purposes.  The implementation of uvm_pageboot_alloc
 * and pmap_startup here also uses them internally.
 */

static vaddr_t      virtual_space_start;
static vaddr_t      virtual_space_end;

/*
 * we allocate an initial number of page colors in uvm_page_init(),
 * and remember them.  We may re-color pages as cache sizes are
 * discovered during the autoconfiguration phase.  But we can never
 * free the initial set of buckets, since they are allocated using
 * uvm_pageboot_alloc().
 */

static bool have_recolored_pages /* = false */;

MALLOC_DEFINE(M_VMPAGE, "VM page", "VM page");

#ifdef DEBUG
vaddr_t uvm_zerocheckkva;
#endif /* DEBUG */

/*
 * local prototypes
 */

static void uvm_pageinsert(struct vm_page *);
static void uvm_pageremove(struct vm_page *);

/*
 * per-object tree of pages
 */

static signed int
uvm_page_compare_nodes(const struct rb_node *n1, const struct rb_node *n2)
{
        const struct vm_page *pg1 = (const void *)n1;
        const struct vm_page *pg2 = (const void *)n2;
        const voff_t a = pg1->offset;
        const voff_t b = pg2->offset;

        if (a < b)
                return 1;
        if (a > b)
                return -1;
        return 0;
}

static signed int
uvm_page_compare_key(const struct rb_node *n, const void *key)
{
        const struct vm_page *pg = (const void *)n;
        const voff_t a = pg->offset;
        const voff_t b = *(const voff_t *)key;

        if (a < b)
                return 1;
        if (a > b)
                return -1;
        return 0;
}

const struct rb_tree_ops uvm_page_tree_ops = {
        .rbto_compare_nodes = uvm_page_compare_nodes,
        .rbto_compare_key = uvm_page_compare_key,
};

/*
 * inline functions
 */

/*
 * uvm_pageinsert: insert a page in the object.
 *
 * => caller must lock object
 * => caller must lock page queues
 * => call should have already set pg's object and offset pointers
 *    and bumped the version counter
 */

static inline void
uvm_pageinsert_list(struct uvm_object *uobj, struct vm_page *pg,
    struct vm_page *where)
{

        KASSERT(uobj == pg->uobject);
        KASSERT(mutex_owned(&uobj->vmobjlock));
        KASSERT((pg->flags & PG_TABLED) == 0);
        KASSERT(where == NULL || (where->flags & PG_TABLED));
        KASSERT(where == NULL || (where->uobject == uobj));

        if (UVM_OBJ_IS_VNODE(uobj)) {
                if (uobj->uo_npages == 0) {
                        struct vnode *vp = (struct vnode *)uobj;

                        vholdl(vp);
                }
                if (UVM_OBJ_IS_VTEXT(uobj)) {
                        atomic_inc_uint(&uvmexp.execpages);
                } else {
                        atomic_inc_uint(&uvmexp.filepages);
                }
        } else if (UVM_OBJ_IS_AOBJ(uobj)) {
                atomic_inc_uint(&uvmexp.anonpages);
        }

        if (where)
                TAILQ_INSERT_AFTER(&uobj->memq, where, pg, listq.queue);
        else
                TAILQ_INSERT_TAIL(&uobj->memq, pg, listq.queue);
        pg->flags |= PG_TABLED;
        uobj->uo_npages++;
}


static inline void
uvm_pageinsert_tree(struct uvm_object *uobj, struct vm_page *pg)
{
        bool success;

        KASSERT(uobj == pg->uobject);
        success = rb_tree_insert_node(&uobj->rb_tree, &pg->rb_node);
        KASSERT(success);
}

static inline void
uvm_pageinsert(struct vm_page *pg)
{
        struct uvm_object *uobj = pg->uobject;

        uvm_pageinsert_tree(uobj, pg);
        uvm_pageinsert_list(uobj, pg, NULL);
}

/*
 * uvm_page_remove: remove page from object.
 *
 * => caller must lock object
 * => caller must lock page queues
 */

static inline void
uvm_pageremove_list(struct uvm_object *uobj, struct vm_page *pg)
{

        KASSERT(uobj == pg->uobject);
        KASSERT(mutex_owned(&uobj->vmobjlock));
        KASSERT(pg->flags & PG_TABLED);

        if (UVM_OBJ_IS_VNODE(uobj)) {
                if (uobj->uo_npages == 1) {
                        struct vnode *vp = (struct vnode *)uobj;

                        holdrelel(vp);
                }
                if (UVM_OBJ_IS_VTEXT(uobj)) {
                        atomic_dec_uint(&uvmexp.execpages);
                } else {
                        atomic_dec_uint(&uvmexp.filepages);
                }
        } else if (UVM_OBJ_IS_AOBJ(uobj)) {
                atomic_dec_uint(&uvmexp.anonpages);
        }

        /* object should be locked */
        uobj->uo_npages--;
        TAILQ_REMOVE(&uobj->memq, pg, listq.queue);
        pg->flags &= ~PG_TABLED;
        pg->uobject = NULL;
}

static inline void
uvm_pageremove_tree(struct uvm_object *uobj, struct vm_page *pg)
{

        KASSERT(uobj == pg->uobject);
        rb_tree_remove_node(&uobj->rb_tree, &pg->rb_node);
}

static inline void
uvm_pageremove(struct vm_page *pg)
{
        struct uvm_object *uobj = pg->uobject;

        uvm_pageremove_tree(uobj, pg);
        uvm_pageremove_list(uobj, pg);
}

static void
uvm_page_init_buckets(struct pgfreelist *pgfl)
{
        int color, i;

        for (color = 0; color < uvmexp.ncolors; color++) {
                for (i = 0; i < PGFL_NQUEUES; i++) {
                        LIST_INIT(&pgfl->pgfl_buckets[color].pgfl_queues[i]);
                }
        }
}

/*
 * uvm_page_init: init the page system.   called from uvm_init().
 *
 * => we return the range of kernel virtual memory in kvm_startp/kvm_endp
 */

void
uvm_page_init(vaddr_t *kvm_startp, vaddr_t *kvm_endp)
{
        vsize_t freepages, pagecount, bucketcount, n;
        struct pgflbucket *bucketarray, *cpuarray;
        struct vm_page *pagearray;
        int lcv;
        u_int i;
        paddr_t paddr;

        KASSERT(ncpu <= 1);
        CTASSERT(sizeof(pagearray->offset) >= sizeof(struct uvm_cpu *));

        /*
         * init the page queues and page queue locks, except the free
         * list; we allocate that later (with the initial vm_page
         * structures).
         */

        curcpu()->ci_data.cpu_uvm = &uvm.cpus[0];
        uvm_reclaim_init();
        uvmpdpol_init();
        mutex_init(&uvm_pageqlock, MUTEX_DRIVER, IPL_NONE);
        mutex_init(&uvm_fpageqlock, MUTEX_DRIVER, IPL_VM);

        /*
         * allocate vm_page structures.
         */

        /*
         * sanity check:
         * before calling this function the MD code is expected to register
         * some free RAM with the uvm_page_physload() function.   our job
         * now is to allocate vm_page structures for this memory.
         */

        if (vm_nphysseg == 0)
                panic("uvm_page_bootstrap: no memory pre-allocated");

        /*
         * first calculate the number of free pages...
         *
         * note that we use start/end rather than avail_start/avail_end.
         * this allows us to allocate extra vm_page structures in case we
         * want to return some memory to the pool after booting.
         */

        freepages = 0;
        for (lcv = 0 ; lcv < vm_nphysseg ; lcv++)
                freepages += (vm_physmem[lcv].end - vm_physmem[lcv].start);

        /*
         * Let MD code initialize the number of colors, or default
         * to 1 color if MD code doesn't care.
         */
        if (uvmexp.ncolors == 0)
                uvmexp.ncolors = 1;
        uvmexp.colormask = uvmexp.ncolors - 1;

        /*
         * we now know we have (PAGE_SIZE * freepages) bytes of memory we can
         * use.   for each page of memory we use we need a vm_page structure.
         * thus, the total number of pages we can use is the total size of
         * the memory divided by the PAGE_SIZE plus the size of the vm_page
         * structure.   we add one to freepages as a fudge factor to avoid
         * truncation errors (since we can only allocate in terms of whole
         * pages).
         */

        bucketcount = uvmexp.ncolors * VM_NFREELIST;
        pagecount = ((freepages + 1) << PAGE_SHIFT) /
            (PAGE_SIZE + sizeof(struct vm_page));

        bucketarray = (void *)uvm_pageboot_alloc((bucketcount *
            sizeof(struct pgflbucket) * 2) + (pagecount *
            sizeof(struct vm_page)));
        cpuarray = bucketarray + bucketcount;
        pagearray = (struct vm_page *)(bucketarray + bucketcount * 2);

        for (lcv = 0; lcv < VM_NFREELIST; lcv++) {
                uvm.page_free[lcv].pgfl_buckets =
                    (bucketarray + (lcv * uvmexp.ncolors));
                uvm_page_init_buckets(&uvm.page_free[lcv]);
                uvm.cpus[0].page_free[lcv].pgfl_buckets =
                    (cpuarray + (lcv * uvmexp.ncolors));
                uvm_page_init_buckets(&uvm.cpus[0].page_free[lcv]);
        }
        memset(pagearray, 0, pagecount * sizeof(struct vm_page));

        /*
         * init the vm_page structures and put them in the correct place.
         */

        for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) {
                n = vm_physmem[lcv].end - vm_physmem[lcv].start;

                /* set up page array pointers */
                vm_physmem[lcv].pgs = pagearray;
                pagearray += n;
                pagecount -= n;
                vm_physmem[lcv].lastpg = vm_physmem[lcv].pgs + (n - 1);

                /* init and free vm_pages (we've already zeroed them) */
                paddr = ptoa(vm_physmem[lcv].start);
                for (i = 0 ; i < n ; i++, paddr += PAGE_SIZE) {
                        vm_physmem[lcv].pgs[i].phys_addr = paddr;
#ifdef __HAVE_VM_PAGE_MD
                        VM_MDPAGE_INIT(&vm_physmem[lcv].pgs[i]);
#endif
                        if (atop(paddr) >= vm_physmem[lcv].avail_start &&
                            atop(paddr) <= vm_physmem[lcv].avail_end) {
                                uvmexp.npages++;
                                /* add page to free pool */
                                uvm_pagefree(&vm_physmem[lcv].pgs[i]);
                        }
                }
        }

        /*
         * pass up the values of virtual_space_start and
         * virtual_space_end (obtained by uvm_pageboot_alloc) to the upper
         * layers of the VM.
         */

        *kvm_startp = round_page(virtual_space_start);
        *kvm_endp = trunc_page(virtual_space_end);
#ifdef DEBUG
        /*
         * steal kva for uvm_pagezerocheck().
         */
        uvm_zerocheckkva = *kvm_startp;
        *kvm_startp += PAGE_SIZE;
#endif /* DEBUG */

        /*
         * init various thresholds.
         */

        uvmexp.reserve_pagedaemon = 1;
        uvmexp.reserve_kernel = vm_page_reserve_kernel;

        /*
         * determine if we should zero pages in the idle loop.
         */

        uvm.cpus[0].page_idle_zero = vm_page_zero_enable;

        /*
         * done!
         */

        uvm.page_init_done = true;
}

/*
 * uvm_setpagesize: set the page size
 *
 * => sets page_shift and page_mask from uvmexp.pagesize.
 */

void
uvm_setpagesize(void)
{

        /*
         * If uvmexp.pagesize is 0 at this point, we expect PAGE_SIZE
         * to be a constant (indicated by being a non-zero value).
         */
        if (uvmexp.pagesize == 0) {
                if (PAGE_SIZE == 0)
                        panic("uvm_setpagesize: uvmexp.pagesize not set");
                uvmexp.pagesize = PAGE_SIZE;
        }
        uvmexp.pagemask = uvmexp.pagesize - 1;
        if ((uvmexp.pagemask & uvmexp.pagesize) != 0)
                panic("uvm_setpagesize: page size not a power of two");
        for (uvmexp.pageshift = 0; ; uvmexp.pageshift++)
                if ((1 << uvmexp.pageshift) == uvmexp.pagesize)
                        break;
}

/*
 * uvm_pageboot_alloc: steal memory from physmem for bootstrapping
 */

vaddr_t
uvm_pageboot_alloc(vsize_t size)
{
        static bool initialized = false;
        vaddr_t addr;
#if !defined(PMAP_STEAL_MEMORY)
        vaddr_t vaddr;
        paddr_t paddr;
#endif

        /*
         * on first call to this function, initialize ourselves.
         */
        if (initialized == false) {
                pmap_virtual_space(&virtual_space_start, &virtual_space_end);

                /* round it the way we like it */
                virtual_space_start = round_page(virtual_space_start);
                virtual_space_end = trunc_page(virtual_space_end);

                initialized = true;
        }

        /* round to page size */
        size = round_page(size);

#if defined(PMAP_STEAL_MEMORY)

        /*
         * defer bootstrap allocation to MD code (it may want to allocate
         * from a direct-mapped segment).  pmap_steal_memory should adjust
         * virtual_space_start/virtual_space_end if necessary.
         */

        addr = pmap_steal_memory(size, &virtual_space_start,
            &virtual_space_end);

        return(addr);

#else /* !PMAP_STEAL_MEMORY */

        /*
         * allocate virtual memory for this request
         */
        if (virtual_space_start == virtual_space_end ||
            (virtual_space_end - virtual_space_start) < size)
                panic("uvm_pageboot_alloc: out of virtual space");

        addr = virtual_space_start;

#ifdef PMAP_GROWKERNEL
        /*
         * If the kernel pmap can't map the requested space,
         * then allocate more resources for it.
         */
        if (uvm_maxkaddr < (addr + size)) {
                uvm_maxkaddr = pmap_growkernel(addr + size);
                if (uvm_maxkaddr < (addr + size))
                        panic("uvm_pageboot_alloc: pmap_growkernel() failed");
        }
#endif

        virtual_space_start += size;

        /*
         * allocate and mapin physical pages to back new virtual pages
         */

        for (vaddr = round_page(addr) ; vaddr < addr + size ;
            vaddr += PAGE_SIZE) {

                if (!uvm_page_physget(&paddr))
                        panic("uvm_pageboot_alloc: out of memory");

                /*
                 * Note this memory is no longer managed, so using
                 * pmap_kenter is safe.
                 */
                pmap_kenter_pa(vaddr, paddr, VM_PROT_READ|VM_PROT_WRITE, 0);
        }
        pmap_update(pmap_kernel());
        return(addr);
#endif  /* PMAP_STEAL_MEMORY */
}

#if !defined(PMAP_STEAL_MEMORY)
/*
 * uvm_page_physget: "steal" one page from the vm_physmem structure.
 *
 * => attempt to allocate it off the end of a segment in which the "avail"
 *    values match the start/end values.   if we can't do that, then we
 *    will advance both values (making them equal, and removing some
 *    vm_page structures from the non-avail area).
 * => return false if out of memory.
 */

/* subroutine: try to allocate from memory chunks on the specified freelist */
static bool uvm_page_physget_freelist(paddr_t *, int);

static bool
uvm_page_physget_freelist(paddr_t *paddrp, int freelist)
{
        int lcv, x;

        /* pass 1: try allocating from a matching end */
#if (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST)
        for (lcv = vm_nphysseg - 1 ; lcv >= 0 ; lcv--)
#else
        for (lcv = 0 ; lcv < vm_nphysseg ; lcv++)
#endif
        {

                if (uvm.page_init_done == true)
                        panic("uvm_page_physget: called _after_ bootstrap");

                if (vm_physmem[lcv].free_list != freelist)
                        continue;

                /* try from front */
                if (vm_physmem[lcv].avail_start == vm_physmem[lcv].start &&
                    vm_physmem[lcv].avail_start < vm_physmem[lcv].avail_end) {
                        *paddrp = ptoa(vm_physmem[lcv].avail_start);
                        vm_physmem[lcv].avail_start++;
                        vm_physmem[lcv].start++;
                        /* nothing left?   nuke it */
                        if (vm_physmem[lcv].avail_start ==
                            vm_physmem[lcv].end) {
                                if (vm_nphysseg == 1)
                                    panic("uvm_page_physget: out of memory!");
                                vm_nphysseg--;
                                for (x = lcv ; x < vm_nphysseg ; x++)
                                        /* structure copy */
                                        vm_physmem[x] = vm_physmem[x+1];
                        }
                        return (true);
                }

                /* try from rear */
                if (vm_physmem[lcv].avail_end == vm_physmem[lcv].end &&
                    vm_physmem[lcv].avail_start < vm_physmem[lcv].avail_end) {
                        *paddrp = ptoa(vm_physmem[lcv].avail_end - 1);
                        vm_physmem[lcv].avail_end--;
                        vm_physmem[lcv].end--;
                        /* nothing left?   nuke it */
                        if (vm_physmem[lcv].avail_end ==
                            vm_physmem[lcv].start) {
                                if (vm_nphysseg == 1)
                                    panic("uvm_page_physget: out of memory!");
                                vm_nphysseg--;
                                for (x = lcv ; x < vm_nphysseg ; x++)
                                        /* structure copy */
                                        vm_physmem[x] = vm_physmem[x+1];
                        }
                        return (true);
                }
        }

        /* pass2: forget about matching ends, just allocate something */
#if (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST)
        for (lcv = vm_nphysseg - 1 ; lcv >= 0 ; lcv--)
#else
        for (lcv = 0 ; lcv < vm_nphysseg ; lcv++)
#endif
        {

                /* any room in this bank? */
                if (vm_physmem[lcv].avail_start >= vm_physmem[lcv].avail_end)
                        continue;  /* nope */

                *paddrp = ptoa(vm_physmem[lcv].avail_start);
                vm_physmem[lcv].avail_start++;
                /* truncate! */
                vm_physmem[lcv].start = vm_physmem[lcv].avail_start;

                /* nothing left?   nuke it */
                if (vm_physmem[lcv].avail_start == vm_physmem[lcv].end) {
                        if (vm_nphysseg == 1)
                                panic("uvm_page_physget: out of memory!");
                        vm_nphysseg--;
                        for (x = lcv ; x < vm_nphysseg ; x++)
                                /* structure copy */
                                vm_physmem[x] = vm_physmem[x+1];
                }
                return (true);
        }

        return (false);        /* whoops! */
}

bool
uvm_page_physget(paddr_t *paddrp)
{
        int i;

        /* try in the order of freelist preference */
        for (i = 0; i < VM_NFREELIST; i++)
                if (uvm_page_physget_freelist(paddrp, i) == true)
                        return (true);
        return (false);
}
#endif /* PMAP_STEAL_MEMORY */

/*
 * uvm_page_physload: load physical memory into VM system
 *
 * => all args are PFs
 * => all pages in start/end get vm_page structures
 * => areas marked by avail_start/avail_end get added to the free page pool
 * => we are limited to VM_PHYSSEG_MAX physical memory segments
 */

void
uvm_page_physload(paddr_t start, paddr_t end, paddr_t avail_start,
    paddr_t avail_end, int free_list)
{
        int preload, lcv;
        psize_t npages;
        struct vm_page *pgs;
        struct vm_physseg *ps;

        if (uvmexp.pagesize == 0)
                panic("uvm_page_physload: page size not set!");
        if (free_list >= VM_NFREELIST || free_list < VM_FREELIST_DEFAULT)
                panic("uvm_page_physload: bad free list %d", free_list);
        if (start >= end)
                panic("uvm_page_physload: start >= end");

        /*
         * do we have room?
         */

        if (vm_nphysseg == VM_PHYSSEG_MAX) {
                printf("uvm_page_physload: unable to load physical memory "
                    "segment\n");
                printf("\t%d segments allocated, ignoring 0x%llx -> 0x%llx\n",
                    VM_PHYSSEG_MAX, (long long)start, (long long)end);
                printf("\tincrease VM_PHYSSEG_MAX\n");
                return;
        }

        /*
         * check to see if this is a "preload" (i.e. uvm_mem_init hasn't been
         * called yet, so malloc is not available).
         */

        for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) {
                if (vm_physmem[lcv].pgs)
                        break;
        }
        preload = (lcv == vm_nphysseg);

        /*
         * if VM is already running, attempt to malloc() vm_page structures
         */

        if (!preload) {
#if defined(VM_PHYSSEG_NOADD)
                panic("uvm_page_physload: tried to add RAM after vm_mem_init");
#else
                /* XXXCDC: need some sort of lockout for this case */
                paddr_t paddr;
                npages = end - start;  /* # of pages */
                pgs = malloc(sizeof(struct vm_page) * npages,
                    M_VMPAGE, M_NOWAIT);
                if (pgs == NULL) {
                        printf("uvm_page_physload: can not malloc vm_page "
                            "structs for segment\n");
                        printf("\tignoring 0x%lx -> 0x%lx\n", start, end);
                        return;
                }
                /* zero data, init phys_addr and free_list, and free pages */
                memset(pgs, 0, sizeof(struct vm_page) * npages);
                for (lcv = 0, paddr = ptoa(start) ;
                                 lcv < npages ; lcv++, paddr += PAGE_SIZE) {
                        pgs[lcv].phys_addr = paddr;
                        pgs[lcv].free_list = free_list;
                        if (atop(paddr) >= avail_start &&
                            atop(paddr) <= avail_end)
                                uvm_pagefree(&pgs[lcv]);
                }
                /* XXXCDC: incomplete: need to update uvmexp.free, what else? */
                /* XXXCDC: need hook to tell pmap to rebuild pv_list, etc... */
#endif
        } else {
                pgs = NULL;
                npages = 0;
        }

        /*
         * now insert us in the proper place in vm_physmem[]
         */

#if (VM_PHYSSEG_STRAT == VM_PSTRAT_RANDOM)
        /* random: put it at the end (easy!) */
        ps = &vm_physmem[vm_nphysseg];
#elif (VM_PHYSSEG_STRAT == VM_PSTRAT_BSEARCH)
        {
                int x;
                /* sort by address for binary search */
                for (lcv = 0 ; lcv < vm_nphysseg ; lcv++)
                        if (start < vm_physmem[lcv].start)
                                break;
                ps = &vm_physmem[lcv];
                /* move back other entries, if necessary ... */
                for (x = vm_nphysseg ; x > lcv ; x--)
                        /* structure copy */
                        vm_physmem[x] = vm_physmem[x - 1];
        }
#elif (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST)
        {
                int x;
                /* sort by largest segment first */
                for (lcv = 0 ; lcv < vm_nphysseg ; lcv++)
                        if ((end - start) >
                            (vm_physmem[lcv].end - vm_physmem[lcv].start))
                                break;
                ps = &vm_physmem[lcv];
                /* move back other entries, if necessary ... */
                for (x = vm_nphysseg ; x > lcv ; x--)
                        /* structure copy */
                        vm_physmem[x] = vm_physmem[x - 1];
        }
#else
        panic("uvm_page_physload: unknown physseg strategy selected!");
#endif

        ps->start = start;
        ps->end = end;
        ps->avail_start = avail_start;
        ps->avail_end = avail_end;
        if (preload) {
                ps->pgs = NULL;
        } else {
                ps->pgs = pgs;
                ps->lastpg = pgs + npages - 1;
        }
        ps->free_list = free_list;
        vm_nphysseg++;

        if (!preload) {
                uvmpdpol_reinit();
        }
}

/*
 * uvm_page_recolor: Recolor the pages if the new bucket count is
 * larger than the old one.
 */

void
uvm_page_recolor(int newncolors)
{
        struct pgflbucket *bucketarray, *cpuarray, *oldbucketarray;
        struct pgfreelist gpgfl, pgfl;
        struct vm_page *pg;
        vsize_t bucketcount;
        int lcv, color, i, ocolors;
        struct uvm_cpu *ucpu;

        if (newncolors <= uvmexp.ncolors)
                return;

        if (uvm.page_init_done == false) {
                uvmexp.ncolors = newncolors;
                return;
        }

        bucketcount = newncolors * VM_NFREELIST;
        bucketarray = malloc(bucketcount * sizeof(struct pgflbucket) * 2,
            M_VMPAGE, M_NOWAIT);
        cpuarray = bucketarray + bucketcount;
        if (bucketarray == NULL) {
                printf("WARNING: unable to allocate %ld page color buckets\n",
                    (long) bucketcount);
                return;
        }

        mutex_spin_enter(&uvm_fpageqlock);

        /* Make sure we should still do this. */
        if (newncolors <= uvmexp.ncolors) {
                mutex_spin_exit(&uvm_fpageqlock);
                free(bucketarray, M_VMPAGE);
                return;
        }

        oldbucketarray = uvm.page_free[0].pgfl_buckets;
        ocolors = uvmexp.ncolors;

        uvmexp.ncolors = newncolors;
        uvmexp.colormask = uvmexp.ncolors - 1;

        ucpu = curcpu()->ci_data.cpu_uvm;
        for (lcv = 0; lcv < VM_NFREELIST; lcv++) {
                gpgfl.pgfl_buckets = (bucketarray + (lcv * newncolors));
                pgfl.pgfl_buckets = (cpuarray + (lcv * uvmexp.ncolors));
                uvm_page_init_buckets(&gpgfl);
                uvm_page_init_buckets(&pgfl);
                for (color = 0; color < ocolors; color++) {
                        for (i = 0; i < PGFL_NQUEUES; i++) {
                                while ((pg = LIST_FIRST(&uvm.page_free[
                                    lcv].pgfl_buckets[color].pgfl_queues[i]))
                                    != NULL) {
                                        LIST_REMOVE(pg, pageq.list); /* global */
                                        LIST_REMOVE(pg, listq.list); /* cpu */
                                        LIST_INSERT_HEAD(&gpgfl.pgfl_buckets[
                                            VM_PGCOLOR_BUCKET(pg)].pgfl_queues[
                                            i], pg, pageq.list);
                                        LIST_INSERT_HEAD(&pgfl.pgfl_buckets[
                                            VM_PGCOLOR_BUCKET(pg)].pgfl_queues[
                                            i], pg, listq.list);
                                }
                        }
                }
                uvm.page_free[lcv].pgfl_buckets = gpgfl.pgfl_buckets;
                ucpu->page_free[lcv].pgfl_buckets = pgfl.pgfl_buckets;
        }

        if (have_recolored_pages) {
                mutex_spin_exit(&uvm_fpageqlock);
                free(oldbucketarray, M_VMPAGE);
                return;
        }

        have_recolored_pages = true;
        mutex_spin_exit(&uvm_fpageqlock);
}

/*
 * uvm_cpu_attach: initialize per-CPU data structures.
 */

void
uvm_cpu_attach(struct cpu_info *ci)
{
        struct pgflbucket *bucketarray;
        struct pgfreelist pgfl;
        struct uvm_cpu *ucpu;
        vsize_t bucketcount;
        int lcv;

        if (CPU_IS_PRIMARY(ci)) {
                /* Already done in uvm_page_init(). */
                return;
        }

        /* Add more reserve pages for this CPU. */
        uvmexp.reserve_kernel += vm_page_reserve_kernel;

        /* Configure this CPU's free lists. */
        bucketcount = uvmexp.ncolors * VM_NFREELIST;
        bucketarray = malloc(bucketcount * sizeof(struct pgflbucket),
            M_VMPAGE, M_WAITOK);
        ucpu = &uvm.cpus[cpu_index(ci)];
        ci->ci_data.cpu_uvm = ucpu;
        for (lcv = 0; lcv < VM_NFREELIST; lcv++) {
                pgfl.pgfl_buckets = (bucketarray + (lcv * uvmexp.ncolors));
                uvm_page_init_buckets(&pgfl);
                ucpu->page_free[lcv].pgfl_buckets = pgfl.pgfl_buckets;
        }
}

/*
 * uvm_pagealloc_pgfl: helper routine for uvm_pagealloc_strat
 */

static struct vm_page *
uvm_pagealloc_pgfl(struct uvm_cpu *ucpu, int flist, int try1, int try2,
    int *trycolorp)
{
        struct pgflist *freeq;
        struct vm_page *pg;
        int color, trycolor = *trycolorp;
        struct pgfreelist *gpgfl, *pgfl;

        KASSERT(mutex_owned(&uvm_fpageqlock));

        color = trycolor;
        pgfl = &ucpu->page_free[flist];
        gpgfl = &uvm.page_free[flist];
        do {
                /* cpu, try1 */
                if ((pg = LIST_FIRST((freeq =
                    &pgfl->pgfl_buckets[color].pgfl_queues[try1]))) != NULL) {
                        VM_FREE_PAGE_TO_CPU(pg)->pages[try1]--;
                        uvmexp.cpuhit++;
                        goto gotit;
                }
                /* global, try1 */
                if ((pg = LIST_FIRST((freeq =
                    &gpgfl->pgfl_buckets[color].pgfl_queues[try1]))) != NULL) {
                        VM_FREE_PAGE_TO_CPU(pg)->pages[try1]--;
                        uvmexp.cpumiss++;
                        goto gotit;
                }
                /* cpu, try2 */
                if ((pg = LIST_FIRST((freeq =
                    &pgfl->pgfl_buckets[color].pgfl_queues[try2]))) != NULL) {
                        VM_FREE_PAGE_TO_CPU(pg)->pages[try2]--;
                        uvmexp.cpuhit++;
                        goto gotit;
                }
                /* global, try2 */
                if ((pg = LIST_FIRST((freeq =
                    &gpgfl->pgfl_buckets[color].pgfl_queues[try2]))) != NULL) {
                        VM_FREE_PAGE_TO_CPU(pg)->pages[try2]--;
                        uvmexp.cpumiss++;
                        goto gotit;
                }
                color = (color + 1) & uvmexp.colormask;
        } while (color != trycolor);

        return (NULL);

 gotit:
        LIST_REMOVE(pg, pageq.list);    /* global list */
        LIST_REMOVE(pg, listq.list);    /* per-cpu list */
        uvmexp.free--;

        /* update zero'd page count */
        if (pg->flags & PG_ZERO)
                uvmexp.zeropages--;

        if (color == trycolor)
                uvmexp.colorhit++;
        else {
                uvmexp.colormiss++;
                *trycolorp = color;
        }

        return (pg);
}

/*
 * uvm_pagealloc_strat: allocate vm_page from a particular free list.
 *
 * => return null if no pages free
 * => wake up pagedaemon if number of free pages drops below low water mark
 * => if obj != NULL, obj must be locked (to put in obj's tree)
 * => if anon != NULL, anon must be locked (to put in anon)
 * => only one of obj or anon can be non-null
 * => caller must activate/deactivate page if it is not wired.
 * => free_list is ignored if strat == UVM_PGA_STRAT_NORMAL.
 * => policy decision: it is more important to pull a page off of the
 *      appropriate priority free list than it is to get a zero'd or
 *      unknown contents page.  This is because we live with the
 *      consequences of a bad free list decision for the entire
 *      lifetime of the page, e.g. if the page comes from memory that
 *      is slower to access.
 */

struct vm_page *
uvm_pagealloc_strat(struct uvm_object *obj, voff_t off, struct vm_anon *anon,
    int flags, int strat, int free_list)
{
        int lcv, try1, try2, zeroit = 0, color;
        struct uvm_cpu *ucpu;
        struct vm_page *pg;
        lwp_t *l;

        KASSERT(obj == NULL || anon == NULL);
        KASSERT(anon == NULL || off == 0);
        KASSERT(off == trunc_page(off));
        KASSERT(obj == NULL || mutex_owned(&obj->vmobjlock));
        KASSERT(anon == NULL || mutex_owned(&anon->an_lock));

        mutex_spin_enter(&uvm_fpageqlock);

        /*
         * This implements a global round-robin page coloring
         * algorithm.
         *
         * XXXJRT: What about virtually-indexed caches?
         */

        ucpu = curcpu()->ci_data.cpu_uvm;
        color = ucpu->page_free_nextcolor;

        /*
         * check to see if we need to generate some free pages waking
         * the pagedaemon.
         */

        uvm_kick_pdaemon();

        /*
         * fail if any of these conditions is true:
         * [1]  there really are no free pages, or
         * [2]  only kernel "reserved" pages remain and
         *        reserved pages have not been requested.
         * [3]  only pagedaemon "reserved" pages remain and
         *        the requestor isn't the pagedaemon.
         * we make kernel reserve pages available if called by a
         * kernel thread or a realtime thread.
         */
        l = curlwp;
        if (__predict_true(l != NULL) && lwp_eprio(l) >= PRI_KTHREAD) {
                flags |= UVM_PGA_USERESERVE;
        }
        if ((uvmexp.free <= uvmexp.reserve_kernel &&
            (flags & UVM_PGA_USERESERVE) == 0) ||
            (uvmexp.free <= uvmexp.reserve_pagedaemon &&
             curlwp != uvm.pagedaemon_lwp))
                goto fail;

#if PGFL_NQUEUES != 2
#error uvm_pagealloc_strat needs to be updated
#endif

        /*
         * If we want a zero'd page, try the ZEROS queue first, otherwise
         * we try the UNKNOWN queue first.
         */
        if (flags & UVM_PGA_ZERO) {
                try1 = PGFL_ZEROS;
                try2 = PGFL_UNKNOWN;
        } else {
                try1 = PGFL_UNKNOWN;
                try2 = PGFL_ZEROS;
        }

 again:
        switch (strat) {
        case UVM_PGA_STRAT_NORMAL:
                /* Check freelists: descending priority (ascending id) order */
                for (lcv = 0; lcv < VM_NFREELIST; lcv++) {
                        pg = uvm_pagealloc_pgfl(ucpu, lcv,
                            try1, try2, &color);
                        if (pg != NULL)
                                goto gotit;
                }

                /* No pages free! */
                goto fail;

        case UVM_PGA_STRAT_ONLY:
        case UVM_PGA_STRAT_FALLBACK:
                /* Attempt to allocate from the specified free list. */
                KASSERT(free_list >= 0 && free_list < VM_NFREELIST);
                pg = uvm_pagealloc_pgfl(ucpu, free_list,
                    try1, try2, &color);
                if (pg != NULL)
                        goto gotit;

                /* Fall back, if possible. */
                if (strat == UVM_PGA_STRAT_FALLBACK) {
                        strat = UVM_PGA_STRAT_NORMAL;
                        goto again;
                }

                /* No pages free! */
                goto fail;

        default:
                panic("uvm_pagealloc_strat: bad strat %d", strat);
                /* NOTREACHED */
        }

 gotit:
        /*
         * We now know which color we actually allocated from; set
         * the next color accordingly.
         */

        ucpu->page_free_nextcolor = (color + 1) & uvmexp.colormask;

        /*
         * update allocation statistics and remember if we have to
         * zero the page
         */

        if (flags & UVM_PGA_ZERO) {
                if (pg->flags & PG_ZERO) {
                        uvmexp.pga_zerohit++;
                        zeroit = 0;
                } else {
                        uvmexp.pga_zeromiss++;
                        zeroit = 1;
                }
                if (ucpu->pages[PGFL_ZEROS] < ucpu->pages[PGFL_UNKNOWN]) {
                        ucpu->page_idle_zero = vm_page_zero_enable;
                }
        }
        KASSERT(pg->pqflags == PQ_FREE);

        pg->offset = off;
        pg->uobject = obj;
        pg->uanon = anon;
        pg->flags = PG_BUSY|PG_CLEAN|PG_FAKE;
        if (anon) {
                anon->an_page = pg;
                pg->pqflags = PQ_ANON;
                atomic_inc_uint(&uvmexp.anonpages);
        } else {
                if (obj) {
                        uvm_pageinsert(pg);
                }
                pg->pqflags = 0;
        }
        mutex_spin_exit(&uvm_fpageqlock);

#if defined(UVM_PAGE_TRKOWN)
        pg->owner_tag = NULL;
#endif
        UVM_PAGE_OWN(pg, "new alloc");

        if (flags & UVM_PGA_ZERO) {
                /*
                 * A zero'd page is not clean.  If we got a page not already
                 * zero'd, then we have to zero it ourselves.
                 */
                pg->flags &= ~PG_CLEAN;
                if (zeroit)
                        pmap_zero_page(VM_PAGE_TO_PHYS(pg));
        }

        return(pg);

 fail:
        mutex_spin_exit(&uvm_fpageqlock);
        return (NULL);
}

/*
 * uvm_pagereplace: replace a page with another
 *
 * => object must be locked
 */

void
uvm_pagereplace(struct vm_page *oldpg, struct vm_page *newpg)
{
        struct uvm_object *uobj = oldpg->uobject;

        KASSERT((oldpg->flags & PG_TABLED) != 0);
        KASSERT(uobj != NULL);
        KASSERT((newpg->flags & PG_TABLED) == 0);
        KASSERT(newpg->uobject == NULL);
        KASSERT(mutex_owned(&uobj->vmobjlock));

        newpg->uobject = uobj;
        newpg->offset = oldpg->offset;

        uvm_pageremove_tree(uobj, oldpg);
        uvm_pageinsert_tree(uobj, newpg);
        uvm_pageinsert_list(uobj, newpg, oldpg);
        uvm_pageremove_list(uobj, oldpg);
}

/*
 * uvm_pagerealloc: reallocate a page from one object to another
 *
 * => both objects must be locked
 */

void
uvm_pagerealloc(struct vm_page *pg, struct uvm_object *newobj, voff_t newoff)
{
        /*
         * remove it from the old object
         */

        if (pg->uobject) {
                uvm_pageremove(pg);
        }

        /*
         * put it in the new object
         */

        if (newobj) {
                pg->uobject = newobj;
                pg->offset = newoff;
                uvm_pageinsert(pg);
        }
}

#ifdef DEBUG
/*
 * check if page is zero-filled
 *
 *  - called with free page queue lock held.
 */
void
uvm_pagezerocheck(struct vm_page *pg)
{
        int *p, *ep;

        KASSERT(uvm_zerocheckkva != 0);
        KASSERT(mutex_owned(&uvm_fpageqlock));

        /*
         * XXX assuming pmap_kenter_pa and pmap_kremove never call
         * uvm page allocator.
         *
         * it might be better to have "CPU-local temporary map" pmap interface.
         */
        pmap_kenter_pa(uvm_zerocheckkva, VM_PAGE_TO_PHYS(pg), VM_PROT_READ, 0);
        p = (int *)uvm_zerocheckkva;
        ep = (int *)((char *)p + PAGE_SIZE);
        pmap_update(pmap_kernel());
        while (p < ep) {
                if (*p != 0)
                        panic("PG_ZERO page isn't zero-filled");
                p++;
        }
        pmap_kremove(uvm_zerocheckkva, PAGE_SIZE);
        /*
         * pmap_update() is not necessary here because no one except us
         * uses this VA.
         */
}
#endif /* DEBUG */

/*
 * uvm_pagefree: free page
 *
 * => erase page's identity (i.e. remove from object)
 * => put page on free list
 * => caller must lock owning object (either anon or uvm_object)
 * => caller must lock page queues
 * => assumes all valid mappings of pg are gone
 */

void
uvm_pagefree(struct vm_page *pg)
{
        struct pgflist *pgfl;
        struct uvm_cpu *ucpu;
        int index, color, queue;
        bool iszero;

#ifdef DEBUG
        if (pg->uobject == (void *)0xdeadbeef &&
            pg->uanon == (void *)0xdeadbeef) {
                panic("uvm_pagefree: freeing free page %p", pg);
        }
#endif /* DEBUG */

        KASSERT((pg->flags & PG_PAGEOUT) == 0);
        KASSERT(!(pg->pqflags & PQ_FREE));
        KASSERT(mutex_owned(&uvm_pageqlock) || !uvmpdpol_pageisqueued_p(pg));
        KASSERT(pg->uobject == NULL || mutex_owned(&pg->uobject->vmobjlock));
        KASSERT(pg->uobject != NULL || pg->uanon == NULL ||
                mutex_owned(&pg->uanon->an_lock));

        /*
         * if the page is loaned, resolve the loan instead of freeing.
         */

        if (pg->loan_count) {
                KASSERT(pg->wire_count == 0);

                /*
                 * if the page is owned by an anon then we just want to
                 * drop anon ownership.  the kernel will free the page when
                 * it is done with it.  if the page is owned by an object,
                 * remove it from the object and mark it dirty for the benefit
                 * of possible anon owners.
                 *
                 * regardless of previous ownership, wakeup any waiters,
                 * unbusy the page, and we're done.
                 */

                if (pg->uobject != NULL) {
                        uvm_pageremove(pg);
                        pg->flags &= ~PG_CLEAN;
                } else if (pg->uanon != NULL) {
                        if ((pg->pqflags & PQ_ANON) == 0) {
                                pg->loan_count--;
                        } else {
                                pg->pqflags &= ~PQ_ANON;
                                atomic_dec_uint(&uvmexp.anonpages);
                        }
                        pg->uanon->an_page = NULL;
                        pg->uanon = NULL;
                }
                if (pg->flags & PG_WANTED) {
                        wakeup(pg);
                }
                pg->flags &= ~(PG_WANTED|PG_BUSY|PG_RELEASED|PG_PAGER1);
#ifdef UVM_PAGE_TRKOWN
                pg->owner_tag = NULL;
#endif
                if (pg->loan_count) {
                        KASSERT(pg->uobject == NULL);
                        if (pg->uanon == NULL) {
                                uvm_pagedequeue(pg);
                        }
                        return;
                }
        }

        /*
         * remove page from its object or anon.
         */

        if (pg->uobject != NULL) {
                uvm_pageremove(pg);
        } else if (pg->uanon != NULL) {
                pg->uanon->an_page = NULL;
                atomic_dec_uint(&uvmexp.anonpages);
        }

        /*
         * now remove the page from the queues.
         */

        uvm_pagedequeue(pg);

        /*
         * if the page was wired, unwire it now.
         */

        if (pg->wire_count) {
                pg->wire_count = 0;
                uvmexp.wired--;
        }

        /*
         * and put on free queue
         */

        iszero = (pg->flags & PG_ZERO);
        index = uvm_page_lookup_freelist(pg);
        color = VM_PGCOLOR_BUCKET(pg);
        queue = (iszero ? PGFL_ZEROS : PGFL_UNKNOWN);

#ifdef DEBUG
        pg->uobject = (void *)0xdeadbeef;
        pg->uanon = (void *)0xdeadbeef;
#endif

        mutex_spin_enter(&uvm_fpageqlock);
        pg->pqflags = PQ_FREE;

#ifdef DEBUG
        if (iszero)
                uvm_pagezerocheck(pg);
#endif /* DEBUG */


        /* global list */
        pgfl = &uvm.page_free[index].pgfl_buckets[color].pgfl_queues[queue];
        LIST_INSERT_HEAD(pgfl, pg, pageq.list);
        uvmexp.free++;
        if (iszero) {
                uvmexp.zeropages++;
        }

        /* per-cpu list */
        ucpu = curcpu()->ci_data.cpu_uvm;
        pg->offset = (uintptr_t)ucpu;
        pgfl = &ucpu->page_free[index].pgfl_buckets[color].pgfl_queues[queue];
        LIST_INSERT_HEAD(pgfl, pg, listq.list);
        ucpu->pages[queue]++;
        if (ucpu->pages[PGFL_ZEROS] < ucpu->pages[PGFL_UNKNOWN]) {
                ucpu->page_idle_zero = vm_page_zero_enable;
        }

        mutex_spin_exit(&uvm_fpageqlock);
}

/*
 * uvm_page_unbusy: unbusy an array of pages.
 *
 * => pages must either all belong to the same object, or all belong to anons.
 * => if pages are object-owned, object must be locked.
 * => if pages are anon-owned, anons must be locked.
 * => caller must lock page queues if pages may be released.
 * => caller must make sure that anon-owned pages are not PG_RELEASED.
 */

void
uvm_page_unbusy(struct vm_page **pgs, int npgs)
{
        struct vm_page *pg;
        int i;
        UVMHIST_FUNC("uvm_page_unbusy"); UVMHIST_CALLED(ubchist);

        for (i = 0; i < npgs; i++) {
                pg = pgs[i];
                if (pg == NULL || pg == PGO_DONTCARE) {
                        continue;
                }

                KASSERT(pg->uobject == NULL ||
                    mutex_owned(&pg->uobject->vmobjlock));
                KASSERT(pg->uobject != NULL ||
                    (pg->uanon != NULL && mutex_owned(&pg->uanon->an_lock)));

                KASSERT(pg->flags & PG_BUSY);
                KASSERT((pg->flags & PG_PAGEOUT) == 0);
                if (pg->flags & PG_WANTED) {
                        wakeup(pg);
                }
                if (pg->flags & PG_RELEASED) {
                        UVMHIST_LOG(ubchist, "releasing pg %p", pg,0,0,0);
                        KASSERT(pg->uobject != NULL ||
                            (pg->uanon != NULL && pg->uanon->an_ref > 0));
                        pg->flags &= ~PG_RELEASED;
                        uvm_pagefree(pg);
                } else {
                        UVMHIST_LOG(ubchist, "unbusying pg %p", pg,0,0,0);
                        KASSERT((pg->flags & PG_FAKE) == 0);
                        pg->flags &= ~(PG_WANTED|PG_BUSY);
                        UVM_PAGE_OWN(pg, NULL);
                }
        }
}

#if defined(UVM_PAGE_TRKOWN)
/*
 * uvm_page_own: set or release page ownership
 *
 * => this is a debugging function that keeps track of who sets PG_BUSY
 *      and where they do it.   it can be used to track down problems
 *      such a process setting "PG_BUSY" and never releasing it.
 * => page's object [if any] must be locked
 * => if "tag" is NULL then we are releasing page ownership
 */
void
uvm_page_own(struct vm_page *pg, const char *tag)
{
        struct uvm_object *uobj;
        struct vm_anon *anon;

        KASSERT((pg->flags & (PG_PAGEOUT|PG_RELEASED)) == 0);

        uobj = pg->uobject;
        anon = pg->uanon;
        if (uobj != NULL) {
                KASSERT(mutex_owned(&uobj->vmobjlock));
        } else if (anon != NULL) {
                KASSERT(mutex_owned(&anon->an_lock));
        }

        KASSERT((pg->flags & PG_WANTED) == 0);

        /* gain ownership? */
        if (tag) {
                KASSERT((pg->flags & PG_BUSY) != 0);
                if (pg->owner_tag) {
                        printf("uvm_page_own: page %p already owned "
                            "by proc %d [%s]\n", pg,
                            pg->owner, pg->owner_tag);
                        panic("uvm_page_own");
                }
                pg->owner = (curproc) ? curproc->p_pid :  (pid_t) -1;
                pg->lowner = (curlwp) ? curlwp->l_lid :  (lwpid_t) -1;
                pg->owner_tag = tag;
                return;
        }

        /* drop ownership */
        KASSERT((pg->flags & PG_BUSY) == 0);
        if (pg->owner_tag == NULL) {
                printf("uvm_page_own: dropping ownership of an non-owned "
                    "page (%p)\n", pg);
                panic("uvm_page_own");
        }
        if (!uvmpdpol_pageisqueued_p(pg)) {
                KASSERT((pg->uanon == NULL && pg->uobject == NULL) ||
                    pg->wire_count > 0);
        } else {
                KASSERT(pg->wire_count == 0);
        }
        pg->owner_tag = NULL;
}
#endif

/*
 * uvm_pageidlezero: zero free pages while the system is idle.
 *
 * => try to complete one color bucket at a time, to reduce our impact
 *      on the CPU cache.
 * => we loop until we either reach the target or there is a lwp ready
 *      to run, or MD code detects a reason to break early.
 */
void
uvm_pageidlezero(void)
{
        struct vm_page *pg;
        struct pgfreelist *pgfl, *gpgfl;
        struct uvm_cpu *ucpu;
        int free_list, firstbucket, nextbucket;

        ucpu = curcpu()->ci_data.cpu_uvm;
        if (!ucpu->page_idle_zero ||
            ucpu->pages[PGFL_UNKNOWN] < uvmexp.ncolors) {
                ucpu->page_idle_zero = false;
                return;
        }
        mutex_enter(&uvm_fpageqlock);
        firstbucket = ucpu->page_free_nextcolor;
        nextbucket = firstbucket;
        do {
                for (free_list = 0; free_list < VM_NFREELIST; free_list++) {
                        if (sched_curcpu_runnable_p()) {
                                goto quit;
                        }
                        pgfl = &ucpu->page_free[free_list];
                        gpgfl = &uvm.page_free[free_list];
                        while ((pg = LIST_FIRST(&pgfl->pgfl_buckets[
                            nextbucket].pgfl_queues[PGFL_UNKNOWN])) != NULL) {
                                if (sched_curcpu_runnable_p()) {
                                        goto quit;
                                }
                                LIST_REMOVE(pg, pageq.list); /* global list */
                                LIST_REMOVE(pg, listq.list); /* per-cpu list */
                                ucpu->pages[PGFL_UNKNOWN]--;
                                uvmexp.free--;
                                KASSERT(pg->pqflags == PQ_FREE);
                                pg->pqflags = 0;
                                mutex_spin_exit(&uvm_fpageqlock);
#ifdef PMAP_PAGEIDLEZERO
                                if (!PMAP_PAGEIDLEZERO(VM_PAGE_TO_PHYS(pg))) {

                                        /*
                                         * The machine-dependent code detected
                                         * some reason for us to abort zeroing
                                         * pages, probably because there is a
                                         * process now ready to run.
                                         */

                                        mutex_spin_enter(&uvm_fpageqlock);
                                        pg->pqflags = PQ_FREE;
                                        LIST_INSERT_HEAD(&gpgfl->pgfl_buckets[
                                            nextbucket].pgfl_queues[
                                            PGFL_UNKNOWN], pg, pageq.list);
                                        LIST_INSERT_HEAD(&pgfl->pgfl_buckets[
                                            nextbucket].pgfl_queues[
                                            PGFL_UNKNOWN], pg, listq.list);
                                        ucpu->pages[PGFL_UNKNOWN]++;
                                        uvmexp.free++;
                                        uvmexp.zeroaborts++;
                                        goto quit;
                                }
#else
                                pmap_zero_page(VM_PAGE_TO_PHYS(pg));
#endif /* PMAP_PAGEIDLEZERO */
                                pg->flags |= PG_ZERO;

                                mutex_spin_enter(&uvm_fpageqlock);
                                pg->pqflags = PQ_FREE;
                                LIST_INSERT_HEAD(&gpgfl->pgfl_buckets[
                                    nextbucket].pgfl_queues[PGFL_ZEROS],
                                    pg, pageq.list);
                                LIST_INSERT_HEAD(&pgfl->pgfl_buckets[
                                    nextbucket].pgfl_queues[PGFL_ZEROS],
                                    pg, listq.list);
                                ucpu->pages[PGFL_ZEROS]++;
                                uvmexp.free++;
                                uvmexp.zeropages++;
                        }
                }
                if (ucpu->pages[PGFL_UNKNOWN] < uvmexp.ncolors) {
                        break;
                }
                nextbucket = (nextbucket + 1) & uvmexp.colormask;
        } while (nextbucket != firstbucket);
        ucpu->page_idle_zero = false;
 quit:
        mutex_spin_exit(&uvm_fpageqlock);
}

/*
 * uvm_pagelookup: look up a page
 *
 * => caller should lock object to keep someone from pulling the page
 *      out from under it
 */

struct vm_page *
uvm_pagelookup(struct uvm_object *obj, voff_t off)
{
        struct vm_page *pg;

        KASSERT(mutex_owned(&obj->vmobjlock));

        pg = (struct vm_page *)rb_tree_find_node(&obj->rb_tree, &off);

        KASSERT(pg == NULL || obj->uo_npages != 0);
        KASSERT(pg == NULL || (pg->flags & (PG_RELEASED|PG_PAGEOUT)) == 0 ||
                (pg->flags & PG_BUSY) != 0);
        return(pg);
}

/*
 * uvm_pagewire: wire the page, thus removing it from the daemon's grasp
 *
 * => caller must lock page queues
 */

void
uvm_pagewire(struct vm_page *pg)
{
        KASSERT(mutex_owned(&uvm_pageqlock));
#if defined(READAHEAD_STATS)
        if ((pg->pqflags & PQ_READAHEAD) != 0) {
                uvm_ra_hit.ev_count++;
                pg->pqflags &= ~PQ_READAHEAD;
        }
#endif /* defined(READAHEAD_STATS) */
        if (pg->wire_count == 0) {
                uvm_pagedequeue(pg);
                uvmexp.wired++;
        }
        pg->wire_count++;
}

/*
 * uvm_pageunwire: unwire the page.
 *
 * => activate if wire count goes to zero.
 * => caller must lock page queues
 */

void
uvm_pageunwire(struct vm_page *pg)
{
        KASSERT(mutex_owned(&uvm_pageqlock));
        pg->wire_count--;
        if (pg->wire_count == 0) {
                uvm_pageactivate(pg);
                uvmexp.wired--;
        }
}

/*
 * uvm_pagedeactivate: deactivate page
 *
 * => caller must lock page queues
 * => caller must check to make sure page is not wired
 * => object that page belongs to must be locked (so we can adjust pg->flags)
 * => caller must clear the reference on the page before calling
 */

void
uvm_pagedeactivate(struct vm_page *pg)
{

        KASSERT(mutex_owned(&uvm_pageqlock));
        KASSERT(pg->wire_count != 0 || uvmpdpol_pageisqueued_p(pg));
        uvmpdpol_pagedeactivate(pg);
}

/*
 * uvm_pageactivate: activate page
 *
 * => caller must lock page queues
 */

void
uvm_pageactivate(struct vm_page *pg)
{

        KASSERT(mutex_owned(&uvm_pageqlock));
#if defined(READAHEAD_STATS)
        if ((pg->pqflags & PQ_READAHEAD) != 0) {
                uvm_ra_hit.ev_count++;
                pg->pqflags &= ~PQ_READAHEAD;
        }
#endif /* defined(READAHEAD_STATS) */
        if (pg->wire_count != 0) {
                return;
        }
        uvmpdpol_pageactivate(pg);
}

/*
 * uvm_pagedequeue: remove a page from any paging queue
 */

void
uvm_pagedequeue(struct vm_page *pg)
{

        if (uvmpdpol_pageisqueued_p(pg)) {
                KASSERT(mutex_owned(&uvm_pageqlock));
        }

        uvmpdpol_pagedequeue(pg);
}

/*
 * uvm_pageenqueue: add a page to a paging queue without activating.
 * used where a page is not really demanded (yet).  eg. read-ahead
 */

void
uvm_pageenqueue(struct vm_page *pg)
{

        KASSERT(mutex_owned(&uvm_pageqlock));
        if (pg->wire_count != 0) {
                return;
        }
        uvmpdpol_pageenqueue(pg);
}

/*
 * uvm_pagezero: zero fill a page
 *
 * => if page is part of an object then the object should be locked
 *      to protect pg->flags.
 */

void
uvm_pagezero(struct vm_page *pg)
{
        pg->flags &= ~PG_CLEAN;
        pmap_zero_page(VM_PAGE_TO_PHYS(pg));
}

/*
 * uvm_pagecopy: copy a page
 *
 * => if page is part of an object then the object should be locked
 *      to protect pg->flags.
 */

void
uvm_pagecopy(struct vm_page *src, struct vm_page *dst)
{

        dst->flags &= ~PG_CLEAN;
        pmap_copy_page(VM_PAGE_TO_PHYS(src), VM_PAGE_TO_PHYS(dst));
}

/*
 * uvm_pageismanaged: test it see that a page (specified by PA) is managed.
 */

bool
uvm_pageismanaged(paddr_t pa)
{

        return (vm_physseg_find(atop(pa), NULL) != -1);
}

/*
 * uvm_page_lookup_freelist: look up the free list for the specified page
 */

int
uvm_page_lookup_freelist(struct vm_page *pg)
{
        int lcv;

        lcv = vm_physseg_find(atop(VM_PAGE_TO_PHYS(pg)), NULL);
        KASSERT(lcv != -1);
        return (vm_physmem[lcv].free_list);
}

#if defined(DDB) || defined(DEBUGPRINT)

/*
 * uvm_page_printit: actually print the page
 */

static const char page_flagbits[] = UVM_PGFLAGBITS;
static const char page_pqflagbits[] = UVM_PQFLAGBITS;

void
uvm_page_printit(struct vm_page *pg, bool full,
    void (*pr)(const char *, ...))
{
        struct vm_page *tpg;
        struct uvm_object *uobj;
        struct pgflist *pgl;
        char pgbuf[128];
        char pqbuf[128];

        (*pr)("PAGE %p:\n", pg);
        snprintb(pgbuf, sizeof(pgbuf), page_flagbits, pg->flags);
        snprintb(pqbuf, sizeof(pqbuf), page_pqflagbits, pg->pqflags);
        (*pr)("  flags=%s, pqflags=%s, wire_count=%d, pa=0x%lx\n",
            pgbuf, pqbuf, pg->wire_count, (long)VM_PAGE_TO_PHYS(pg));
        (*pr)("  uobject=%p, uanon=%p, offset=0x%llx loan_count=%d\n",
            pg->uobject, pg->uanon, (long long)pg->offset, pg->loan_count);
#if defined(UVM_PAGE_TRKOWN)
        if (pg->flags & PG_BUSY)
                (*pr)("  owning process = %d, tag=%s\n",
                    pg->owner, pg->owner_tag);
        else
                (*pr)("  page not busy, no owner\n");
#else
        (*pr)("  [page ownership tracking disabled]\n");
#endif

        if (!full)
                return;

        /* cross-verify object/anon */
        if ((pg->pqflags & PQ_FREE) == 0) {
                if (pg->pqflags & PQ_ANON) {
                        if (pg->uanon == NULL || pg->uanon->an_page != pg)
                            (*pr)("  >>> ANON DOES NOT POINT HERE <<< (%p)\n",
                                (pg->uanon) ? pg->uanon->an_page : NULL);
                        else
                                (*pr)("  anon backpointer is OK\n");
                } else {
                        uobj = pg->uobject;
                        if (uobj) {
                                (*pr)("  checking object list\n");
                                TAILQ_FOREACH(tpg, &uobj->memq, listq.queue) {
                                        if (tpg == pg) {
                                                break;
                                        }
                                }
                                if (tpg)
                                        (*pr)("  page found on object list\n");
                                else
                        (*pr)("  >>> PAGE NOT FOUND ON OBJECT LIST! <<<\n");
                        }
                }
        }

        /* cross-verify page queue */
        if (pg->pqflags & PQ_FREE) {
                int fl = uvm_page_lookup_freelist(pg);
                int color = VM_PGCOLOR_BUCKET(pg);
                pgl = &uvm.page_free[fl].pgfl_buckets[color].pgfl_queues[
                    ((pg)->flags & PG_ZERO) ? PGFL_ZEROS : PGFL_UNKNOWN];
        } else {
                pgl = NULL;
        }

        if (pgl) {
                (*pr)("  checking pageq list\n");
                LIST_FOREACH(tpg, pgl, pageq.list) {
                        if (tpg == pg) {
                                break;
                        }
                }
                if (tpg)
                        (*pr)("  page found on pageq list\n");
                else
                        (*pr)("  >>> PAGE NOT FOUND ON PAGEQ LIST! <<<\n");
        }
}

/*
 * uvm_pages_printthem - print a summary of all managed pages
 */

void
uvm_page_printall(void (*pr)(const char *, ...))
{
        unsigned i;
        struct vm_page *pg;

        (*pr)("%18s %4s %4s %18s %18s"
#ifdef UVM_PAGE_TRKOWN
            " OWNER"
#endif
            "\n", "PAGE", "FLAG", "PQ", "UOBJECT", "UANON");
        for (i = 0; i < vm_nphysseg; i++) {
                for (pg = vm_physmem[i].pgs; pg <= vm_physmem[i].lastpg; pg++) {
                        (*pr)("%18p %04x %04x %18p %18p",
                            pg, pg->flags, pg->pqflags, pg->uobject,
                            pg->uanon);
#ifdef UVM_PAGE_TRKOWN
                        if (pg->flags & PG_BUSY)
                                (*pr)(" %d [%s]", pg->owner, pg->owner_tag);
#endif
                        (*pr)("\n");
                }
        }
}

#endif /* DDB || DEBUGPRINT */