Merge illumos-gate

[unleashed.git] / kernel / vm / vm_pagelist.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * Copyright 2012 Joyent, Inc.  All rights reserved.
 */

/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*      All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */


/*
 * This file contains common functions to access and manage the page lists.
 * Many of these routines originated from platform dependent modules
 * (sun4/vm/vm_dep.c, i86pc/vm/vm_machdep.c) and modified to function in
 * a platform independent manner.
 *
 * vm/vm_dep.h provides for platform specific support.
 */

#include <sys/types.h>
#include <sys/debug.h>
#include <sys/cmn_err.h>
#include <sys/systm.h>
#include <sys/atomic.h>
#include <sys/sysmacros.h>
#include <vm/as.h>
#include <vm/page.h>
#include <vm/seg_kmem.h>
#include <vm/seg_vn.h>
#include <sys/vmsystm.h>
#include <sys/memnode.h>
#include <vm/vm_dep.h>
#include <sys/lgrp.h>
#include <sys/mem_config.h>
#include <sys/callb.h>
#include <sys/sdt.h>
#include <sys/dumphdr.h>
#include <sys/swap.h>

extern uint_t   vac_colors;

#define MAX_PRAGMA_ALIGN        128

/* vm_cpu_data0 for the boot cpu before kmem is initialized */

#if L2CACHE_ALIGN_MAX <= MAX_PRAGMA_ALIGN
#pragma align   L2CACHE_ALIGN_MAX(vm_cpu_data0)
#else
#pragma align   MAX_PRAGMA_ALIGN(vm_cpu_data0)
#endif
char            vm_cpu_data0[VM_CPU_DATA_PADSIZE];

/*
 * number of page colors equivalent to reqested color in page_get routines.
 * If set, keeps large pages intact longer and keeps MPO allocation
 * from the local mnode in favor of acquiring the 'correct' page color from
 * a demoted large page or from a remote mnode.
 */
uint_t  colorequiv;

/*
 * color equivalency mask for each page size.
 * Mask is computed based on cpu L2$ way sizes and colorequiv global.
 * High 4 bits determine the number of high order bits of the color to ignore.
 * Low 4 bits determines number of low order bits of color to ignore (it's only
 * relevant for hashed index based page coloring).
 */
uchar_t colorequivszc[MMU_PAGE_SIZES];

/*
 * if set, specifies the percentage of large pages that are free from within
 * a large page region before attempting to lock those pages for
 * page_get_contig_pages processing.
 *
 * Should be turned on when kpr is available when page_trylock_contig_pages
 * can be more selective.
 */

int     ptcpthreshold;

/*
 * Limit page get contig page search based on failure cnts in pgcpfailcnt[].
 * Enabled by default via pgcplimitsearch.
 *
 * pgcpfailcnt[] is bounded by PGCPFAILMAX (>= 1/2 of installed
 * memory). When reached, pgcpfailcnt[] is reset to 1/2 of this upper
 * bound. This upper bound range guarantees:
 *    - all large page 'slots' will be searched over time
 *    - the minimum (1) large page candidates considered on each pgcp call
 *    - count doesn't wrap around to 0
 */
pgcnt_t pgcpfailcnt[MMU_PAGE_SIZES];
int     pgcplimitsearch = 1;

#define PGCPFAILMAX             (1 << (highbit(physinstalled) - 1))
#define SETPGCPFAILCNT(szc)                                             \
        if (++pgcpfailcnt[szc] >= PGCPFAILMAX)                          \
                pgcpfailcnt[szc] = PGCPFAILMAX / 2;

#ifdef VM_STATS
struct vmm_vmstats_str  vmm_vmstats;

#endif /* VM_STATS */

/* enable page_get_contig_pages */
#define LPGCREATE       1

int pg_contig_disable;
int pg_lpgcreate_nocage = LPGCREATE;

/*
 * page_freelist_split pfn flag to signify no lo or hi pfn requirement.
 */
#define PFNNULL         0

/* Flags involved in promotion and demotion routines */
#define PC_FREE         0x1     /* put page on freelist */
#define PC_ALLOC        0x2     /* return page for allocation */

/*
 * Flag for page_demote to be used with PC_FREE to denote that we don't care
 * what the color is as the color parameter to the function is ignored.
 */
#define PC_NO_COLOR     (-1)

/* mtype value for page_promote to use when mtype does not matter */
#define PC_MTYPE_ANY    (-1)

/*
 * page counters candidates info
 * See page_ctrs_cands comment below for more details.
 * fields are as follows:
 *      pcc_pages_free:         # pages which freelist coalesce can create
 *      pcc_color_free:         pointer to page free counts per color
 */
typedef struct pcc_info {
        pgcnt_t pcc_pages_free;
        pgcnt_t *pcc_color_free;
        uint_t  pad[12];
} pcc_info_t;

/*
 * On big machines it can take a long time to check page_counters
 * arrays. page_ctrs_cands is a summary array whose elements are a dynamically
 * updated sum of all elements of the corresponding page_counters arrays.
 * page_freelist_coalesce() searches page_counters only if an appropriate
 * element of page_ctrs_cands array is greater than 0.
 *
 * page_ctrs_cands is indexed by mutex (i), region (r), mnode (m), mrange (g)
 */
pcc_info_t **page_ctrs_cands[NPC_MUTEX][MMU_PAGE_SIZES];

/*
 * Return in val the total number of free pages which can be created
 * for the given mnode (m), mrange (g), and region size (r)
 */
#define PGCTRS_CANDS_GETVALUE(m, g, r, val) {                           \
        int i;                                                          \
        val = 0;                                                        \
        for (i = 0; i < NPC_MUTEX; i++) {                               \
            val += page_ctrs_cands[i][(r)][(m)][(g)].pcc_pages_free;    \
        }                                                               \
}

/*
 * Return in val the total number of free pages which can be created
 * for the given mnode (m), mrange (g), region size (r), and color (c)
 */
#define PGCTRS_CANDS_GETVALUECOLOR(m, g, r, c, val) {                   \
        int i;                                                          \
        val = 0;                                                        \
        ASSERT((c) < PAGE_GET_PAGECOLORS(r));                           \
        for (i = 0; i < NPC_MUTEX; i++) {                               \
            val +=                                                      \
                page_ctrs_cands[i][(r)][(m)][(g)].pcc_color_free[(c)];  \
        }                                                               \
}

/*
 * We can only allow a single thread to update a counter within the physical
 * range of the largest supported page size. That is the finest granularity
 * possible since the counter values are dependent on each other
 * as you move accross region sizes. PP_CTR_LOCK_INDX is used to determine the
 * ctr_mutex lock index for a particular physical range.
 */
static kmutex_t *ctr_mutex[NPC_MUTEX];

#define PP_CTR_LOCK_INDX(pp)                                            \
        (((pp)->p_pagenum >>                                            \
            (PAGE_BSZS_SHIFT(mmu_page_sizes - 1))) & (NPC_MUTEX - 1))

#define INVALID_COLOR 0xffffffff
#define INVALID_MASK  0xffffffff

/*
 * Local functions prototypes.
 */

void page_ctr_add(int, int, page_t *, int);
void page_ctr_add_internal(int, int, page_t *, int);
void page_ctr_sub(int, int, page_t *, int);
void page_ctr_sub_internal(int, int, page_t *, int);
void page_freelist_lock(int);
void page_freelist_unlock(int);
page_t *page_promote(int, pfn_t, uchar_t, int, int);
page_t *page_demote(int, pfn_t, pfn_t, uchar_t, uchar_t, int, int);
page_t *page_freelist_split(uchar_t,
    uint_t, int, int, pfn_t, pfn_t, page_list_walker_t *);
page_t *page_get_mnode_cachelist(uint_t, uint_t, int, int);
static int page_trylock_cons(page_t *pp, se_t se);

/*
 * The page_counters array below is used to keep track of free contiguous
 * physical memory.  A hw_page_map_t will be allocated per mnode per szc.
 * This contains an array of counters, the size of the array, a shift value
 * used to convert a pagenum into a counter array index or vice versa, as
 * well as a cache of the last successful index to be promoted to a larger
 * page size.  As an optimization, we keep track of the last successful index
 * to be promoted per page color for the given size region, and this is
 * allocated dynamically based upon the number of colors for a given
 * region size.
 *
 * Conceptually, the page counters are represented as:
 *
 *      page_counters[region_size][mnode]
 *
 *      region_size:    size code of a candidate larger page made up
 *                      of contiguous free smaller pages.
 *
 *      page_counters[region_size][mnode].hpm_counters[index]:
 *              represents how many (region_size - 1) pages either
 *              exist or can be created within the given index range.
 *
 * Let's look at a sparc example:
 *      If we want to create a free 512k page, we look at region_size 2
 *      for the mnode we want.  We calculate the index and look at a specific
 *      hpm_counters location.  If we see 8 (FULL_REGION_CNT on sparc) at
 *      this location, it means that 8 64k pages either exist or can be created
 *      from 8K pages in order to make a single free 512k page at the given
 *      index.  Note that when a region is full, it will contribute to the
 *      counts in the region above it.  Thus we will not know what page
 *      size the free pages will be which can be promoted to this new free
 *      page unless we look at all regions below the current region.
 */

/*
 * Note: hpmctr_t is defined in platform vm_dep.h
 * hw_page_map_t contains all the information needed for the page_counters
 * logic. The fields are as follows:
 *
 *      hpm_counters:   dynamically allocated array to hold counter data
 *      hpm_entries:    entries in hpm_counters
 *      hpm_shift:      shift for pnum/array index conv
 *      hpm_base:       PFN mapped to counter index 0
 *      hpm_color_current:      last index in counter array for this color at
 *                              which we successfully created a large page
 */
typedef struct hw_page_map {
        hpmctr_t        *hpm_counters;
        size_t          hpm_entries;
        int             hpm_shift;
        pfn_t           hpm_base;
        size_t          *hpm_color_current[MAX_MNODE_MRANGES];
} hw_page_map_t;

/*
 * Element zero is not used, but is allocated for convenience.
 */
static hw_page_map_t *page_counters[MMU_PAGE_SIZES];

/*
 * Cached value of MNODE_RANGE_CNT(mnode).
 * This is a function call in x86.
 */
static int mnode_nranges[MAX_MEM_NODES];
static int mnode_maxmrange[MAX_MEM_NODES];

/*
 * The following macros are convenient ways to get access to the individual
 * elements of the page_counters arrays.  They can be used on both
 * the left side and right side of equations.
 */
#define PAGE_COUNTERS(mnode, rg_szc, idx)                       \
        (page_counters[(rg_szc)][(mnode)].hpm_counters[(idx)])

#define PAGE_COUNTERS_COUNTERS(mnode, rg_szc)                   \
        (page_counters[(rg_szc)][(mnode)].hpm_counters)

#define PAGE_COUNTERS_SHIFT(mnode, rg_szc)                      \
        (page_counters[(rg_szc)][(mnode)].hpm_shift)

#define PAGE_COUNTERS_ENTRIES(mnode, rg_szc)                    \
        (page_counters[(rg_szc)][(mnode)].hpm_entries)

#define PAGE_COUNTERS_BASE(mnode, rg_szc)                       \
        (page_counters[(rg_szc)][(mnode)].hpm_base)

#define PAGE_COUNTERS_CURRENT_COLOR_ARRAY(mnode, rg_szc, g)             \
        (page_counters[(rg_szc)][(mnode)].hpm_color_current[(g)])

#define PAGE_COUNTERS_CURRENT_COLOR(mnode, rg_szc, color, mrange)       \
        (page_counters[(rg_szc)][(mnode)].                              \
        hpm_color_current[(mrange)][(color)])

#define PNUM_TO_IDX(mnode, rg_szc, pnum)                        \
        (((pnum) - PAGE_COUNTERS_BASE((mnode), (rg_szc))) >>    \
                PAGE_COUNTERS_SHIFT((mnode), (rg_szc)))

#define IDX_TO_PNUM(mnode, rg_szc, index)                       \
        (PAGE_COUNTERS_BASE((mnode), (rg_szc)) +                \
                ((index) << PAGE_COUNTERS_SHIFT((mnode), (rg_szc))))

/*
 * Protects the hpm_counters and hpm_color_current memory from changing while
 * looking at page counters information.
 * Grab the write lock to modify what these fields point at.
 * Grab the read lock to prevent any pointers from changing.
 * The write lock can not be held during memory allocation due to a possible
 * recursion deadlock with trying to grab the read lock while the
 * write lock is already held.
 */
krwlock_t page_ctrs_rwlock[MAX_MEM_NODES];


/*
 * initialize cpu_vm_data to point at cache aligned vm_cpu_data_t.
 */
void
cpu_vm_data_init(struct cpu *cp)
{
        if (cp == CPU0) {
                cp->cpu_vm_data = (void *)&vm_cpu_data0;
        } else {
                void    *kmptr;
                int     align;
                size_t  sz;

                align = (L2CACHE_ALIGN) ? L2CACHE_ALIGN : L2CACHE_ALIGN_MAX;
                sz = P2ROUNDUP(sizeof (vm_cpu_data_t), align) + align;
                kmptr = kmem_zalloc(sz, KM_SLEEP);
                cp->cpu_vm_data = (void *) P2ROUNDUP((uintptr_t)kmptr, align);
                ((vm_cpu_data_t *)cp->cpu_vm_data)->vc_kmptr = kmptr;
                ((vm_cpu_data_t *)cp->cpu_vm_data)->vc_kmsize = sz;
        }
}

/*
 * free cpu_vm_data
 */
void
cpu_vm_data_destroy(struct cpu *cp)
{
        if (cp->cpu_seqid && cp->cpu_vm_data) {
                ASSERT(cp != CPU0);
                kmem_free(((vm_cpu_data_t *)cp->cpu_vm_data)->vc_kmptr,
                    ((vm_cpu_data_t *)cp->cpu_vm_data)->vc_kmsize);
        }
        cp->cpu_vm_data = NULL;
}


/*
 * page size to page size code
 */
int
page_szc(size_t pagesize)
{
        int     i = 0;

        while (hw_page_array[i].hp_size) {
                if (pagesize == hw_page_array[i].hp_size)
                        return (i);
                i++;
        }
        return (-1);
}

/*
 * page size to page size code with the restriction that it be a supported
 * user page size.  If it's not a supported user page size, -1 will be returned.
 */
int
page_szc_user_filtered(size_t pagesize)
{
        int szc = page_szc(pagesize);
        if ((szc != -1) && (SZC_2_USERSZC(szc) != -1)) {
                return (szc);
        }
        return (-1);
}

/*
 * Return how many page sizes are available for the user to use.  This is
 * what the hardware supports and not based upon how the OS implements the
 * support of different page sizes.
 *
 * If legacy is non-zero, return the number of pagesizes available to legacy
 * applications. The number of legacy page sizes might be less than the
 * exported user page sizes. This is to prevent legacy applications that
 * use the largest page size returned from getpagesizes(3c) from inadvertantly
 * using the 'new' large pagesizes.
 */
uint_t
page_num_user_pagesizes(int legacy)
{
        if (legacy)
                return (mmu_legacy_page_sizes);
        return (mmu_exported_page_sizes);
}

uint_t
page_num_pagesizes(void)
{
        return (mmu_page_sizes);
}

/*
 * returns the count of the number of base pagesize pages associated with szc
 */
pgcnt_t
page_get_pagecnt(uint_t szc)
{
        if (szc >= mmu_page_sizes)
                panic("page_get_pagecnt: out of range %d", szc);
        return (hw_page_array[szc].hp_pgcnt);
}

size_t
page_get_pagesize(uint_t szc)
{
        if (szc >= mmu_page_sizes)
                panic("page_get_pagesize: out of range %d", szc);
        return (hw_page_array[szc].hp_size);
}

/*
 * Return the size of a page based upon the index passed in.  An index of
 * zero refers to the smallest page size in the system, and as index increases
 * it refers to the next larger supported page size in the system.
 * Note that szc and userszc may not be the same due to unsupported szc's on
 * some systems.
 */
size_t
page_get_user_pagesize(uint_t userszc)
{
        uint_t szc = USERSZC_2_SZC(userszc);

        if (szc >= mmu_page_sizes)
                panic("page_get_user_pagesize: out of range %d", szc);
        return (hw_page_array[szc].hp_size);
}

uint_t
page_get_shift(uint_t szc)
{
        if (szc >= mmu_page_sizes)
                panic("page_get_shift: out of range %d", szc);
        return (PAGE_GET_SHIFT(szc));
}

uint_t
page_get_pagecolors(uint_t szc)
{
        if (szc >= mmu_page_sizes)
                panic("page_get_pagecolors: out of range %d", szc);
        return (PAGE_GET_PAGECOLORS(szc));
}

/*
 * this assigns the desired equivalent color after a split
 */
uint_t
page_correct_color(uchar_t szc, uchar_t nszc, uint_t color,
    uint_t ncolor, uint_t ceq_mask)
{
        ASSERT(nszc > szc);
        ASSERT(szc < mmu_page_sizes);
        ASSERT(color < PAGE_GET_PAGECOLORS(szc));
        ASSERT(ncolor < PAGE_GET_PAGECOLORS(nszc));

        color &= ceq_mask;
        ncolor = PAGE_CONVERT_COLOR(ncolor, szc, nszc);
        return (color | (ncolor & ~ceq_mask));
}

/*
 * The interleaved_mnodes flag is set when mnodes overlap in
 * the physbase..physmax range, but have disjoint slices.
 * In this case hpm_counters is shared by all mnodes.
 * This flag is set dynamically by the platform.
 */
int interleaved_mnodes = 0;

/*
 * Called by startup().
 * Size up the per page size free list counters based on physmax
 * of each node and max_mem_nodes.
 *
 * If interleaved_mnodes is set we need to find the first mnode that
 * exists. hpm_counters for the first mnode will then be shared by
 * all other mnodes. If interleaved_mnodes is not set, just set
 * first=mnode each time. That means there will be no sharing.
 */
size_t
page_ctrs_sz(void)
{
        int     r;              /* region size */
        int     mnode;
        int     firstmn;        /* first mnode that exists */
        int     nranges;
        pfn_t   physbase;
        pfn_t   physmax;
        uint_t  ctrs_sz = 0;
        int     i;
        pgcnt_t colors_per_szc[MMU_PAGE_SIZES];

        /*
         * We need to determine how many page colors there are for each
         * page size in order to allocate memory for any color specific
         * arrays.
         */
        for (i = 0; i < mmu_page_sizes; i++) {
                colors_per_szc[i] = PAGE_GET_PAGECOLORS(i);
        }

        for (firstmn = -1, mnode = 0; mnode < max_mem_nodes; mnode++) {

                pgcnt_t r_pgcnt;
                pfn_t   r_base;
                pgcnt_t r_align;

                if (mem_node_config[mnode].exists == 0)
                        continue;

                HPM_COUNTERS_LIMITS(mnode, physbase, physmax, firstmn);
                nranges = MNODE_RANGE_CNT(mnode);
                mnode_nranges[mnode] = nranges;
                mnode_maxmrange[mnode] = MNODE_MAX_MRANGE(mnode);

                /*
                 * determine size needed for page counter arrays with
                 * base aligned to large page size.
                 */
                for (r = 1; r < mmu_page_sizes; r++) {
                        /* add in space for hpm_color_current */
                        ctrs_sz += sizeof (size_t) *
                            colors_per_szc[r] * nranges;

                        if (firstmn != mnode)
                                continue;

                        /* add in space for hpm_counters */
                        r_align = page_get_pagecnt(r);
                        r_base = physbase;
                        r_base &= ~(r_align - 1);
                        r_pgcnt = howmany(physmax - r_base + 1, r_align);

                        /*
                         * Round up to always allocate on pointer sized
                         * boundaries.
                         */
                        ctrs_sz += P2ROUNDUP((r_pgcnt * sizeof (hpmctr_t)),
                            sizeof (hpmctr_t *));
                }
        }

        for (r = 1; r < mmu_page_sizes; r++) {
                ctrs_sz += (max_mem_nodes * sizeof (hw_page_map_t));
        }

        /* add in space for page_ctrs_cands and pcc_color_free */
        ctrs_sz += sizeof (pcc_info_t *) * max_mem_nodes *
            mmu_page_sizes * NPC_MUTEX;

        for (mnode = 0; mnode < max_mem_nodes; mnode++) {

                if (mem_node_config[mnode].exists == 0)
                        continue;

                nranges = mnode_nranges[mnode];
                ctrs_sz += sizeof (pcc_info_t) * nranges *
                    mmu_page_sizes * NPC_MUTEX;
                for (r = 1; r < mmu_page_sizes; r++) {
                        ctrs_sz += sizeof (pgcnt_t) * nranges *
                            colors_per_szc[r] * NPC_MUTEX;
                }
        }

        /* ctr_mutex */
        ctrs_sz += (max_mem_nodes * NPC_MUTEX * sizeof (kmutex_t));

        /* size for page list counts */
        PLCNT_SZ(ctrs_sz);

        /*
         * add some slop for roundups. page_ctrs_alloc will roundup the start
         * address of the counters to ecache_alignsize boundary for every
         * memory node.
         */
        return (ctrs_sz + max_mem_nodes * L2CACHE_ALIGN);
}

caddr_t
page_ctrs_alloc(caddr_t alloc_base)
{
        int     mnode;
        int     mrange, nranges;
        int     r;              /* region size */
        int     i;
        int     firstmn;        /* first mnode that exists */
        pfn_t   physbase;
        pfn_t   physmax;
        pgcnt_t colors_per_szc[MMU_PAGE_SIZES];

        /*
         * We need to determine how many page colors there are for each
         * page size in order to allocate memory for any color specific
         * arrays.
         */
        for (i = 0; i < mmu_page_sizes; i++) {
                colors_per_szc[i] = PAGE_GET_PAGECOLORS(i);
        }

        for (r = 1; r < mmu_page_sizes; r++) {
                page_counters[r] = (hw_page_map_t *)alloc_base;
                alloc_base += (max_mem_nodes * sizeof (hw_page_map_t));
        }

        /* page_ctrs_cands and pcc_color_free array */
        for (i = 0; i < NPC_MUTEX; i++) {
                for (r = 1; r < mmu_page_sizes; r++) {

                        page_ctrs_cands[i][r] = (pcc_info_t **)alloc_base;
                        alloc_base += sizeof (pcc_info_t *) * max_mem_nodes;

                        for (mnode = 0; mnode < max_mem_nodes; mnode++) {
                                pcc_info_t *pi;

                                if (mem_node_config[mnode].exists == 0)
                                        continue;

                                nranges = mnode_nranges[mnode];

                                pi = (pcc_info_t *)alloc_base;
                                alloc_base += sizeof (pcc_info_t) * nranges;
                                page_ctrs_cands[i][r][mnode] = pi;

                                for (mrange = 0; mrange < nranges; mrange++) {
                                        pi->pcc_color_free =
                                            (pgcnt_t *)alloc_base;
                                        alloc_base += sizeof (pgcnt_t) *
                                            colors_per_szc[r];
                                        pi++;
                                }
                        }
                }
        }

        /* ctr_mutex */
        for (i = 0; i < NPC_MUTEX; i++) {
                ctr_mutex[i] = (kmutex_t *)alloc_base;
                alloc_base += (max_mem_nodes * sizeof (kmutex_t));
        }

        /* initialize page list counts */
        PLCNT_INIT(alloc_base);

        for (firstmn = -1, mnode = 0; mnode < max_mem_nodes; mnode++) {

                pgcnt_t r_pgcnt;
                pfn_t   r_base;
                pgcnt_t r_align;
                int     r_shift;
                int     nranges = mnode_nranges[mnode];

                if (mem_node_config[mnode].exists == 0)
                        continue;

                HPM_COUNTERS_LIMITS(mnode, physbase, physmax, firstmn);

                for (r = 1; r < mmu_page_sizes; r++) {
                        /*
                         * the page_counters base has to be aligned to the
                         * page count of page size code r otherwise the counts
                         * will cross large page boundaries.
                         */
                        r_align = page_get_pagecnt(r);
                        r_base = physbase;
                        /* base needs to be aligned - lower to aligned value */
                        r_base &= ~(r_align - 1);
                        r_pgcnt = howmany(physmax - r_base + 1, r_align);
                        r_shift = PAGE_BSZS_SHIFT(r);

                        PAGE_COUNTERS_SHIFT(mnode, r) = r_shift;
                        PAGE_COUNTERS_ENTRIES(mnode, r) = r_pgcnt;
                        PAGE_COUNTERS_BASE(mnode, r) = r_base;
                        for (mrange = 0; mrange < nranges; mrange++) {
                                PAGE_COUNTERS_CURRENT_COLOR_ARRAY(mnode,
                                    r, mrange) = (size_t *)alloc_base;
                                alloc_base += sizeof (size_t) *
                                    colors_per_szc[r];
                        }
                        for (i = 0; i < colors_per_szc[r]; i++) {
                                uint_t color_mask = colors_per_szc[r] - 1;
                                pfn_t  pfnum = r_base;
                                size_t idx;
                                int mrange;
                                MEM_NODE_ITERATOR_DECL(it);

                                MEM_NODE_ITERATOR_INIT(pfnum, mnode, r, &it);
                                if (pfnum == (pfn_t)-1) {
                                        idx = 0;
                                } else {
                                        PAGE_NEXT_PFN_FOR_COLOR(pfnum, r, i,
                                            color_mask, color_mask, &it);
                                        idx = PNUM_TO_IDX(mnode, r, pfnum);
                                        idx = (idx >= r_pgcnt) ? 0 : idx;
                                }
                                for (mrange = 0; mrange < nranges; mrange++) {
                                        PAGE_COUNTERS_CURRENT_COLOR(mnode,
                                            r, i, mrange) = idx;
                                }
                        }

                        /* hpm_counters may be shared by all mnodes */
                        if (firstmn == mnode) {
                                PAGE_COUNTERS_COUNTERS(mnode, r) =
                                    (hpmctr_t *)alloc_base;
                                alloc_base +=
                                    P2ROUNDUP((sizeof (hpmctr_t) * r_pgcnt),
                                    sizeof (hpmctr_t *));
                        } else {
                                PAGE_COUNTERS_COUNTERS(mnode, r) =
                                    PAGE_COUNTERS_COUNTERS(firstmn, r);
                        }

                        /*
                         * Verify that PNUM_TO_IDX and IDX_TO_PNUM
                         * satisfy the identity requirement.
                         * We should be able to go from one to the other
                         * and get consistent values.
                         */
                        ASSERT(PNUM_TO_IDX(mnode, r,
                            (IDX_TO_PNUM(mnode, r, 0))) == 0);
                        ASSERT(IDX_TO_PNUM(mnode, r,
                            (PNUM_TO_IDX(mnode, r, r_base))) == r_base);
                }
                /*
                 * Roundup the start address of the page_counters to
                 * cache aligned boundary for every memory node.
                 * page_ctrs_sz() has added some slop for these roundups.
                 */
                alloc_base = (caddr_t)P2ROUNDUP((uintptr_t)alloc_base,
                    L2CACHE_ALIGN);
        }

        /* Initialize other page counter specific data structures. */
        for (mnode = 0; mnode < MAX_MEM_NODES; mnode++) {
                rw_init(&page_ctrs_rwlock[mnode], NULL, RW_DEFAULT, NULL);
        }

        return (alloc_base);
}

/*
 * Functions to adjust region counters for each size free list.
 * Caller is responsible to acquire the ctr_mutex lock if necessary and
 * thus can be called during startup without locks.
 */
/* ARGSUSED */
void
page_ctr_add_internal(int mnode, int mtype, page_t *pp, int flags)
{
        ssize_t         r;      /* region size */
        ssize_t         idx;
        pfn_t           pfnum;
        int             lckidx;

        ASSERT(mnode == PP_2_MEM_NODE(pp));
        ASSERT(mtype == PP_2_MTYPE(pp));

        ASSERT(pp->p_szc < mmu_page_sizes);

        PLCNT_INCR(pp, mnode, mtype, pp->p_szc, flags);

        /* no counter update needed for largest page size */
        if (pp->p_szc >= mmu_page_sizes - 1) {
                return;
        }

        r = pp->p_szc + 1;
        pfnum = pp->p_pagenum;
        lckidx = PP_CTR_LOCK_INDX(pp);

        /*
         * Increment the count of free pages for the current
         * region. Continue looping up in region size incrementing
         * count if the preceeding region is full.
         */
        while (r < mmu_page_sizes) {
                idx = PNUM_TO_IDX(mnode, r, pfnum);

                ASSERT(idx < PAGE_COUNTERS_ENTRIES(mnode, r));
                ASSERT(PAGE_COUNTERS(mnode, r, idx) < FULL_REGION_CNT(r));

                if (++PAGE_COUNTERS(mnode, r, idx) != FULL_REGION_CNT(r)) {
                        break;
                } else {
                        int root_mtype = PP_2_MTYPE(PP_GROUPLEADER(pp, r));
                        pcc_info_t *cand = &page_ctrs_cands[lckidx][r][mnode]
                            [MTYPE_2_MRANGE(mnode, root_mtype)];

                        cand->pcc_pages_free++;
                        cand->pcc_color_free[PP_2_BIN_SZC(pp, r)]++;
                }
                r++;
        }
}

void
page_ctr_add(int mnode, int mtype, page_t *pp, int flags)
{
        int             lckidx = PP_CTR_LOCK_INDX(pp);
        kmutex_t        *lock = &ctr_mutex[lckidx][mnode];

        mutex_enter(lock);
        page_ctr_add_internal(mnode, mtype, pp, flags);
        mutex_exit(lock);
}

void
page_ctr_sub_internal(int mnode, int mtype, page_t *pp, int flags)
{
        int             lckidx;
        ssize_t         r;      /* region size */
        ssize_t         idx;
        pfn_t           pfnum;

        ASSERT(mnode == PP_2_MEM_NODE(pp));
        ASSERT(mtype == PP_2_MTYPE(pp));

        ASSERT(pp->p_szc < mmu_page_sizes);

        PLCNT_DECR(pp, mnode, mtype, pp->p_szc, flags);

        /* no counter update needed for largest page size */
        if (pp->p_szc >= mmu_page_sizes - 1) {
                return;
        }

        r = pp->p_szc + 1;
        pfnum = pp->p_pagenum;
        lckidx = PP_CTR_LOCK_INDX(pp);

        /*
         * Decrement the count of free pages for the current
         * region. Continue looping up in region size decrementing
         * count if the preceeding region was full.
         */
        while (r < mmu_page_sizes) {
                idx = PNUM_TO_IDX(mnode, r, pfnum);

                ASSERT(idx < PAGE_COUNTERS_ENTRIES(mnode, r));
                ASSERT(PAGE_COUNTERS(mnode, r, idx) > 0);

                if (--PAGE_COUNTERS(mnode, r, idx) != FULL_REGION_CNT(r) - 1) {
                        break;
                } else {
                        int root_mtype = PP_2_MTYPE(PP_GROUPLEADER(pp, r));
                        pcc_info_t *cand = &page_ctrs_cands[lckidx][r][mnode]
                            [MTYPE_2_MRANGE(mnode, root_mtype)];

                        ASSERT(cand->pcc_pages_free != 0);
                        ASSERT(cand->pcc_color_free[PP_2_BIN_SZC(pp, r)] != 0);

                        cand->pcc_pages_free--;
                        cand->pcc_color_free[PP_2_BIN_SZC(pp, r)]--;
                }
                r++;
        }
}

void
page_ctr_sub(int mnode, int mtype, page_t *pp, int flags)
{
        int             lckidx = PP_CTR_LOCK_INDX(pp);
        kmutex_t        *lock = &ctr_mutex[lckidx][mnode];

        mutex_enter(lock);
        page_ctr_sub_internal(mnode, mtype, pp, flags);
        mutex_exit(lock);
}

/*
 * Adjust page counters following a memory attach, since typically the
 * size of the array needs to change, and the PFN to counter index
 * mapping needs to change.
 *
 * It is possible this mnode did not exist at startup. In that case
 * allocate pcc_info_t and pcc_color_free arrays. Also, allow for nranges
 * to change (a theoretical possibility on x86), which means pcc_color_free
 * arrays must be extended.
 */
uint_t
page_ctrs_adjust(int mnode)
{
        pgcnt_t npgs;
        int     r;              /* region size */
        int     i;
        size_t  pcsz, old_csz;
        hpmctr_t *new_ctr, *old_ctr;
        pfn_t   oldbase, newbase;
        pfn_t   physbase, physmax;
        size_t  old_npgs;
        hpmctr_t *ctr_cache[MMU_PAGE_SIZES];
        size_t  size_cache[MMU_PAGE_SIZES];
        size_t  *color_cache[MMU_PAGE_SIZES][MAX_MNODE_MRANGES];
        size_t  *old_color_array[MAX_MNODE_MRANGES];
        pgcnt_t colors_per_szc[MMU_PAGE_SIZES];
        pcc_info_t **cands_cache;
        pcc_info_t *old_pi, *pi;
        pgcnt_t *pgcntp;
        int nr, old_nranges, mrange, nranges = MNODE_RANGE_CNT(mnode);
        int cands_cache_nranges;
        int old_maxmrange, new_maxmrange;
        int rc = 0;
        int oldmnode;

        cands_cache = kmem_zalloc(sizeof (pcc_info_t *) * NPC_MUTEX *
            MMU_PAGE_SIZES, KM_NOSLEEP);
        if (cands_cache == NULL)
                return (ENOMEM);

        i = -1;
        HPM_COUNTERS_LIMITS(mnode, physbase, physmax, i);

        newbase = physbase & ~PC_BASE_ALIGN_MASK;
        npgs = roundup(physmax, PC_BASE_ALIGN) - newbase;

        /* prepare to free non-null pointers on the way out */
        cands_cache_nranges = nranges;
        bzero(ctr_cache, sizeof (ctr_cache));
        bzero(color_cache, sizeof (color_cache));

        /*
         * We need to determine how many page colors there are for each
         * page size in order to allocate memory for any color specific
         * arrays.
         */
        for (r = 0; r < mmu_page_sizes; r++) {
                colors_per_szc[r] = PAGE_GET_PAGECOLORS(r);
        }

        /*
         * Preallocate all of the new hpm_counters arrays as we can't
         * hold the page_ctrs_rwlock as a writer and allocate memory.
         * If we can't allocate all of the arrays, undo our work so far
         * and return failure.
         */
        for (r = 1; r < mmu_page_sizes; r++) {
                pcsz = npgs >> PAGE_BSZS_SHIFT(r);
                size_cache[r] = pcsz;
                ctr_cache[r] = kmem_zalloc(pcsz *
                    sizeof (hpmctr_t), KM_NOSLEEP);
                if (ctr_cache[r] == NULL) {
                        rc = ENOMEM;
                        goto cleanup;
                }
        }

        /*
         * Preallocate all of the new color current arrays as we can't
         * hold the page_ctrs_rwlock as a writer and allocate memory.
         * If we can't allocate all of the arrays, undo our work so far
         * and return failure.
         */
        for (r = 1; r < mmu_page_sizes; r++) {
                for (mrange = 0; mrange < nranges; mrange++) {
                        color_cache[r][mrange] = kmem_zalloc(sizeof (size_t) *
                            colors_per_szc[r], KM_NOSLEEP);
                        if (color_cache[r][mrange] == NULL) {
                                rc = ENOMEM;
                                goto cleanup;
                        }
                }
        }

        /*
         * Preallocate all of the new pcc_info_t arrays as we can't
         * hold the page_ctrs_rwlock as a writer and allocate memory.
         * If we can't allocate all of the arrays, undo our work so far
         * and return failure.
         */
        for (r = 1; r < mmu_page_sizes; r++) {
                for (i = 0; i < NPC_MUTEX; i++) {
                        pi = kmem_zalloc(nranges * sizeof (pcc_info_t),
                            KM_NOSLEEP);
                        if (pi == NULL) {
                                rc = ENOMEM;
                                goto cleanup;
                        }
                        cands_cache[i * MMU_PAGE_SIZES + r] = pi;

                        for (mrange = 0; mrange < nranges; mrange++, pi++) {
                                pgcntp = kmem_zalloc(colors_per_szc[r] *
                                    sizeof (pgcnt_t), KM_NOSLEEP);
                                if (pgcntp == NULL) {
                                        rc = ENOMEM;
                                        goto cleanup;
                                }
                                pi->pcc_color_free = pgcntp;
                        }
                }
        }

        /*
         * Grab the write lock to prevent others from walking these arrays
         * while we are modifying them.
         */
        PAGE_CTRS_WRITE_LOCK(mnode);

        /*
         * For interleaved mnodes, find the first mnode
         * with valid page counters since the current
         * mnode may have just been added and not have
         * valid page counters.
         */
        if (interleaved_mnodes) {
                for (i = 0; i < max_mem_nodes; i++)
                        if (PAGE_COUNTERS_COUNTERS(i, 1) != NULL)
                                break;
                ASSERT(i < max_mem_nodes);
                oldmnode = i;
        } else
                oldmnode = mnode;

        old_nranges = mnode_nranges[mnode];
        cands_cache_nranges = old_nranges;
        mnode_nranges[mnode] = nranges;
        old_maxmrange = mnode_maxmrange[mnode];
        mnode_maxmrange[mnode] = MNODE_MAX_MRANGE(mnode);
        new_maxmrange = mnode_maxmrange[mnode];

        for (r = 1; r < mmu_page_sizes; r++) {
                PAGE_COUNTERS_SHIFT(mnode, r) = PAGE_BSZS_SHIFT(r);
                old_ctr = PAGE_COUNTERS_COUNTERS(oldmnode, r);
                old_csz = PAGE_COUNTERS_ENTRIES(oldmnode, r);
                oldbase = PAGE_COUNTERS_BASE(oldmnode, r);
                old_npgs = old_csz << PAGE_COUNTERS_SHIFT(oldmnode, r);
                for (mrange = 0; mrange < MAX_MNODE_MRANGES; mrange++) {
                        old_color_array[mrange] =
                            PAGE_COUNTERS_CURRENT_COLOR_ARRAY(mnode,
                            r, mrange);
                }

                pcsz = npgs >> PAGE_COUNTERS_SHIFT(mnode, r);
                new_ctr = ctr_cache[r];
                ctr_cache[r] = NULL;
                if (old_ctr != NULL &&
                    (oldbase + old_npgs > newbase) &&
                    (newbase + npgs > oldbase)) {
                        /*
                         * Map the intersection of the old and new
                         * counters into the new array.
                         */
                        size_t offset;
                        if (newbase > oldbase) {
                                offset = (newbase - oldbase) >>
                                    PAGE_COUNTERS_SHIFT(mnode, r);
                                bcopy(old_ctr + offset, new_ctr,
                                    MIN(pcsz, (old_csz - offset)) *
                                    sizeof (hpmctr_t));
                        } else {
                                offset = (oldbase - newbase) >>
                                    PAGE_COUNTERS_SHIFT(mnode, r);
                                bcopy(old_ctr, new_ctr + offset,
                                    MIN(pcsz - offset, old_csz) *
                                    sizeof (hpmctr_t));
                        }
                }

                PAGE_COUNTERS_COUNTERS(mnode, r) = new_ctr;
                PAGE_COUNTERS_ENTRIES(mnode, r) = pcsz;
                PAGE_COUNTERS_BASE(mnode, r) = newbase;

                /* update shared hpm_counters in other mnodes */
                if (interleaved_mnodes) {
                        for (i = 0; i < max_mem_nodes; i++) {
                                if ((i == mnode) ||
                                    (mem_node_config[i].exists == 0))
                                        continue;
                                ASSERT(
                                    PAGE_COUNTERS_COUNTERS(i, r) == old_ctr ||
                                    PAGE_COUNTERS_COUNTERS(i, r) == NULL);
                                PAGE_COUNTERS_COUNTERS(i, r) = new_ctr;
                                PAGE_COUNTERS_ENTRIES(i, r) = pcsz;
                                PAGE_COUNTERS_BASE(i, r) = newbase;
                        }
                }

                for (mrange = 0; mrange < MAX_MNODE_MRANGES; mrange++) {
                        PAGE_COUNTERS_CURRENT_COLOR_ARRAY(mnode, r, mrange) =
                            color_cache[r][mrange];
                        color_cache[r][mrange] = NULL;
                }
                /*
                 * for now, just reset on these events as it's probably
                 * not worthwhile to try and optimize this.
                 */
                for (i = 0; i < colors_per_szc[r]; i++) {
                        uint_t color_mask = colors_per_szc[r] - 1;
                        int mlo = interleaved_mnodes ? 0 : mnode;
                        int mhi = interleaved_mnodes ? max_mem_nodes :
                            (mnode + 1);
                        int m;
                        pfn_t  pfnum;
                        size_t idx;
                        MEM_NODE_ITERATOR_DECL(it);

                        for (m = mlo; m < mhi; m++) {
                                if (mem_node_config[m].exists == 0)
                                        continue;
                                pfnum = newbase;
                                MEM_NODE_ITERATOR_INIT(pfnum, m, r, &it);
                                if (pfnum == (pfn_t)-1) {
                                        idx = 0;
                                } else {
                                        PAGE_NEXT_PFN_FOR_COLOR(pfnum, r, i,
                                            color_mask, color_mask, &it);
                                        idx = PNUM_TO_IDX(m, r, pfnum);
                                        idx = (idx < pcsz) ? idx : 0;
                                }
                                for (mrange = 0; mrange < nranges; mrange++) {
                                        if (PAGE_COUNTERS_CURRENT_COLOR_ARRAY(m,
                                            r, mrange) != NULL)
                                                PAGE_COUNTERS_CURRENT_COLOR(m,
                                                    r, i, mrange) = idx;
                                }
                        }
                }

                /* cache info for freeing out of the critical path */
                if ((caddr_t)old_ctr >= kernelheap &&
                    (caddr_t)old_ctr < ekernelheap) {
                        ctr_cache[r] = old_ctr;
                        size_cache[r] = old_csz;
                }
                for (mrange = 0; mrange < MAX_MNODE_MRANGES; mrange++) {
                        size_t *tmp = old_color_array[mrange];
                        if ((caddr_t)tmp >= kernelheap &&
                            (caddr_t)tmp < ekernelheap) {
                                color_cache[r][mrange] = tmp;
                        }
                }
                /*
                 * Verify that PNUM_TO_IDX and IDX_TO_PNUM
                 * satisfy the identity requirement.
                 * We should be able to go from one to the other
                 * and get consistent values.
                 */
                ASSERT(PNUM_TO_IDX(mnode, r,
                    (IDX_TO_PNUM(mnode, r, 0))) == 0);
                ASSERT(IDX_TO_PNUM(mnode, r,
                    (PNUM_TO_IDX(mnode, r, newbase))) == newbase);

                /* pcc_info_t and pcc_color_free */
                for (i = 0; i < NPC_MUTEX; i++) {
                        pcc_info_t *epi;
                        pcc_info_t *eold_pi;

                        pi = cands_cache[i * MMU_PAGE_SIZES + r];
                        old_pi = page_ctrs_cands[i][r][mnode];
                        page_ctrs_cands[i][r][mnode] = pi;
                        cands_cache[i * MMU_PAGE_SIZES + r] = old_pi;

                        /* preserve old pcc_color_free values, if any */
                        if (old_pi == NULL)
                                continue;

                        /*
                         * when/if x86 does DR, must account for
                         * possible change in range index when
                         * preserving pcc_info
                         */
                        epi = &pi[nranges];
                        eold_pi = &old_pi[old_nranges];
                        if (new_maxmrange > old_maxmrange) {
                                pi += new_maxmrange - old_maxmrange;
                        } else if (new_maxmrange < old_maxmrange) {
                                old_pi += old_maxmrange - new_maxmrange;
                        }
                        for (; pi < epi && old_pi < eold_pi; pi++, old_pi++) {
                                pcc_info_t tmp = *pi;
                                *pi = *old_pi;
                                *old_pi = tmp;
                        }
                }
        }
        PAGE_CTRS_WRITE_UNLOCK(mnode);

        /*
         * Now that we have dropped the write lock, it is safe to free all
         * of the memory we have cached above.
         * We come thru here to free memory when pre-alloc fails, and also to
         * free old pointers which were recorded while locked.
         */
cleanup:
        for (r = 1; r < mmu_page_sizes; r++) {
                if (ctr_cache[r] != NULL) {
                        kmem_free(ctr_cache[r],
                            size_cache[r] * sizeof (hpmctr_t));
                }
                for (mrange = 0; mrange < MAX_MNODE_MRANGES; mrange++) {
                        if (color_cache[r][mrange] != NULL) {
                                kmem_free(color_cache[r][mrange],
                                    colors_per_szc[r] * sizeof (size_t));
                        }
                }
                for (i = 0; i < NPC_MUTEX; i++) {
                        pi = cands_cache[i * MMU_PAGE_SIZES + r];
                        if (pi == NULL)
                                continue;
                        nr = cands_cache_nranges;
                        for (mrange = 0; mrange < nr; mrange++, pi++) {
                                pgcntp = pi->pcc_color_free;
                                if (pgcntp == NULL)
                                        continue;
                                if ((caddr_t)pgcntp >= kernelheap &&
                                    (caddr_t)pgcntp < ekernelheap) {
                                        kmem_free(pgcntp,
                                            colors_per_szc[r] *
                                            sizeof (pgcnt_t));
                                }
                        }
                        pi = cands_cache[i * MMU_PAGE_SIZES + r];
                        if ((caddr_t)pi >= kernelheap &&
                            (caddr_t)pi < ekernelheap) {
                                kmem_free(pi, nr * sizeof (pcc_info_t));
                        }
                }
        }

        kmem_free(cands_cache,
            sizeof (pcc_info_t *) * NPC_MUTEX * MMU_PAGE_SIZES);
        return (rc);
}

/*
 * Cleanup the hpm_counters field in the page counters
 * array.
 */
void
page_ctrs_cleanup(void)
{
        int r;  /* region size */
        int i;  /* mnode index */

        /*
         * Get the page counters write lock while we are
         * setting the page hpm_counters field to NULL
         * for non-existent mnodes.
         */
        for (i = 0; i < max_mem_nodes; i++) {
                PAGE_CTRS_WRITE_LOCK(i);
                if (mem_node_config[i].exists) {
                        PAGE_CTRS_WRITE_UNLOCK(i);
                        continue;
                }
                for (r = 1; r < mmu_page_sizes; r++) {
                        PAGE_COUNTERS_COUNTERS(i, r) = NULL;
                }
                PAGE_CTRS_WRITE_UNLOCK(i);
        }
}

#ifdef DEBUG

/*
 * confirm pp is a large page corresponding to szc
 */
void
chk_lpg(page_t *pp, uchar_t szc)
{
        spgcnt_t npgs = page_get_pagecnt(pp->p_szc);
        uint_t noreloc;

        if (npgs == 1) {
                ASSERT(pp->p_szc == 0);
                ASSERT(pp->p_next == pp);
                ASSERT(pp->p_prev == pp);
                return;
        }

        ASSERT(pp->p_list.largepg.next == pp || pp->p_list.largepg.next == NULL);
        ASSERT(pp->p_list.largepg.prev == pp || pp->p_list.largepg.prev == NULL);

        ASSERT(IS_P2ALIGNED(pp->p_pagenum, npgs));
        ASSERT(pp->p_pagenum == (pp->p_next->p_pagenum - 1));
        ASSERT(pp->p_prev->p_pagenum == (pp->p_pagenum + (npgs - 1)));
        ASSERT(pp->p_prev == (pp + (npgs - 1)));

        /*
         * Check list of pages.
         */
        noreloc = PP_ISNORELOC(pp);
        while (npgs--) {
                if (npgs != 0) {
                        ASSERT(pp->p_pagenum == pp->p_next->p_pagenum - 1);
                        ASSERT(pp->p_next == (pp + 1));
                }
                ASSERT(pp->p_szc == szc);
                ASSERT(PP_ISFREE(pp));
                ASSERT(PP_ISAGED(pp));
                ASSERT(pp->p_list.largepg.next == pp || pp->p_list.largepg.next == NULL);
                ASSERT(pp->p_list.largepg.prev == pp || pp->p_list.largepg.prev == NULL);
                VERIFY(pp->p_object == NULL);
                ASSERT(pp->p_vnode  == NULL);
                ASSERT(PP_ISNORELOC(pp) == noreloc);

                pp = pp->p_next;
        }
}
#endif /* DEBUG */

void
page_freelist_lock(int mnode)
{
        int i;
        for (i = 0; i < NPC_MUTEX; i++) {
                mutex_enter(FPC_MUTEX(mnode, i));
                mutex_enter(CPC_MUTEX(mnode, i));
        }
}

void
page_freelist_unlock(int mnode)
{
        int i;
        for (i = 0; i < NPC_MUTEX; i++) {
                mutex_exit(FPC_MUTEX(mnode, i));
                mutex_exit(CPC_MUTEX(mnode, i));
        }
}

/*
 * add pp to the specified page list. Defaults to head of the page list
 * unless PG_LIST_TAIL is specified.
 */
void
page_list_add(page_t *pp, int flags)
{
        page_t          **ppp;
        kmutex_t        *pcm;
        uint_t          bin, mtype;
        int             mnode;

        ASSERT(PAGE_EXCL(pp) || (flags & PG_LIST_ISINIT));
        ASSERT(PP_ISFREE(pp));
        ASSERT(!hat_page_is_mapped(pp));
        ASSERT(hat_page_getshare(pp) == 0);

        /*
         * Large pages should be freed via page_list_add_pages().
         */
        ASSERT(pp->p_szc == 0);

        /*
         * Don't need to lock the freelist first here
         * because the page isn't on the freelist yet.
         * This means p_szc can't change on us.
         */

        bin = PP_2_BIN(pp);
        mnode = PP_2_MEM_NODE(pp);
        mtype = PP_2_MTYPE(pp);

        if (flags & PG_LIST_ISINIT) {
                /*
                 * PG_LIST_ISINIT is set during system startup (ie. single
                 * threaded), add a page to the free list and add to the
                 * the free region counters w/o any locking
                 */
                ppp = &PAGE_FREELISTS(mnode, 0, bin, mtype);

                /* inline version of page_add() */
                if (*ppp != NULL) {
                        pp->p_next = *ppp;
                        pp->p_prev = (*ppp)->p_prev;
                        (*ppp)->p_prev = pp;
                        pp->p_prev->p_next = pp;
                } else
                        *ppp = pp;

                page_ctr_add_internal(mnode, mtype, pp, flags);
                VM_STAT_ADD(vmm_vmstats.pladd_free[0]);
        } else {
                pcm = PC_BIN_MUTEX(mnode, bin, flags);

                if (flags & PG_FREE_LIST) {
                        VM_STAT_ADD(vmm_vmstats.pladd_free[0]);
                        ASSERT(PP_ISAGED(pp));
                        ppp = &PAGE_FREELISTS(mnode, 0, bin, mtype);

                } else {
                        VM_STAT_ADD(vmm_vmstats.pladd_cache);
                        VERIFY(pp->p_object);
                        ASSERT(pp->p_vnode);
                        ASSERT((pp->p_offset & PAGEOFFSET) == 0);
                        ppp = &PAGE_CACHELISTS(mnode, bin, mtype);
                }
                mutex_enter(pcm);
                page_add(ppp, pp);

                if (flags & PG_LIST_TAIL)
                        *ppp = (*ppp)->p_next;
                /*
                 * Add counters before releasing pcm mutex to avoid a race with
                 * page_freelist_coalesce and page_freelist_split.
                 */
                page_ctr_add(mnode, mtype, pp, flags);
                mutex_exit(pcm);
        }


        /*
         * It is up to the caller to unlock the page!
         */
        ASSERT(PAGE_EXCL(pp) || (flags & PG_LIST_ISINIT));
}



/* ARGSUSED */
void
page_list_noreloc_startup(page_t *pp)
{
        panic("page_list_noreloc_startup: should be here only for sparc");
}

void
page_list_add_pages(page_t *pp, int flags)
{
        kmutex_t *pcm;
        pgcnt_t pgcnt;
        uint_t  bin, mtype, i;
        int     mnode;

        /* default to freelist/head */
        ASSERT((flags & (PG_CACHE_LIST | PG_LIST_TAIL)) == 0);

        CHK_LPG(pp, pp->p_szc);
        VM_STAT_ADD(vmm_vmstats.pladd_free[pp->p_szc]);

        bin = PP_2_BIN(pp);
        mnode = PP_2_MEM_NODE(pp);
        mtype = PP_2_MTYPE(pp);

        if (flags & PG_LIST_ISINIT) {
                ASSERT(pp->p_szc == mmu_page_sizes - 1);
                page_lpadd(&PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype), pp);
                ASSERT(!PP_ISNORELOC(pp));
                PLCNT_INCR(pp, mnode, mtype, pp->p_szc, flags);
        } else {

                ASSERT(pp->p_szc != 0 && pp->p_szc < mmu_page_sizes);

                pcm = PC_BIN_MUTEX(mnode, bin, PG_FREE_LIST);

                mutex_enter(pcm);
                page_lpadd(&PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype), pp);
                page_ctr_add(mnode, mtype, pp, PG_FREE_LIST);
                mutex_exit(pcm);

                pgcnt = page_get_pagecnt(pp->p_szc);
                for (i = 0; i < pgcnt; i++, pp++)
                        page_unlock_nocapture(pp);
        }
}

/*
 * During boot, need to demote a large page to base
 * pagesize pages for seg_kmem for use in boot_alloc()
 */
void
page_boot_demote(page_t *pp)
{
        ASSERT(pp->p_szc != 0);
        ASSERT(PP_ISFREE(pp));
        ASSERT(PP_ISAGED(pp));

        (void) page_demote(PP_2_MEM_NODE(pp),
            PFN_BASE(pp->p_pagenum, pp->p_szc), 0, pp->p_szc, 0, PC_NO_COLOR,
            PC_FREE);

        ASSERT(PP_ISFREE(pp));
        ASSERT(PP_ISAGED(pp));
        ASSERT(pp->p_szc == 0);
}

/*
 * Take a particular page off of whatever freelist the page
 * is claimed to be on.
 *
 * NOTE: Only used for PAGESIZE pages.
 */
void
page_list_sub(page_t *pp, int flags)
{
        int             bin;
        uint_t          mtype;
        int             mnode;
        kmutex_t        *pcm;
        page_t          **ppp;

        ASSERT(PAGE_EXCL(pp));
        ASSERT(PP_ISFREE(pp));

        /*
         * The p_szc field can only be changed by page_promote()
         * and page_demote(). Only free pages can be promoted and
         * demoted and the free list MUST be locked during these
         * operations. So to prevent a race in page_list_sub()
         * between computing which bin of the freelist lock to
         * grab and actually grabing the lock we check again that
         * the bin we locked is still the correct one. Notice that
         * the p_szc field could have actually changed on us but
         * if the bin happens to still be the same we are safe.
         */
try_again:
        bin = PP_2_BIN(pp);
        mnode = PP_2_MEM_NODE(pp);
        pcm = PC_BIN_MUTEX(mnode, bin, flags);
        mutex_enter(pcm);
        if (PP_2_BIN(pp) != bin) {
                mutex_exit(pcm);
                goto try_again;
        }
        mtype = PP_2_MTYPE(pp);

        if (flags & PG_FREE_LIST) {
                VM_STAT_ADD(vmm_vmstats.plsub_free[0]);
                ASSERT(PP_ISAGED(pp));
                ppp = &PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype);
        } else {
                VM_STAT_ADD(vmm_vmstats.plsub_cache);
                ASSERT(!PP_ISAGED(pp));
                ppp = &PAGE_CACHELISTS(mnode, bin, mtype);
        }

        /*
         * Common PAGESIZE case.
         *
         * Note that we locked the freelist. This prevents
         * any page promotion/demotion operations. Therefore
         * the p_szc will not change until we drop pcm mutex.
         */
        if (pp->p_szc == 0) {
                page_sub(ppp, pp);
                /*
                 * Subtract counters before releasing pcm mutex
                 * to avoid race with page_freelist_coalesce.
                 */
                page_ctr_sub(mnode, mtype, pp, flags);
                mutex_exit(pcm);

                return;
        }

        /*
         * Large pages on the cache list are not supported.
         */
        if (flags & PG_CACHE_LIST)
                panic("page_list_sub: large page on cachelist");

        /*
         * Slow but rare.
         *
         * Somebody wants this particular page which is part
         * of a large page. In this case we just demote the page
         * if it's on the freelist.
         *
         * We have to drop pcm before locking the entire freelist.
         * Once we have re-locked the freelist check to make sure
         * the page hasn't already been demoted or completely
         * freed.
         */
        mutex_exit(pcm);
        page_freelist_lock(mnode);
        if (pp->p_szc != 0) {
                /*
                 * Large page is on freelist.
                 */
                (void) page_demote(mnode, PFN_BASE(pp->p_pagenum, pp->p_szc),
                    0, pp->p_szc, 0, PC_NO_COLOR, PC_FREE);
        }
        ASSERT(PP_ISFREE(pp));
        ASSERT(PP_ISAGED(pp));
        ASSERT(pp->p_szc == 0);

        /*
         * Subtract counters before releasing pcm mutex
         * to avoid race with page_freelist_coalesce.
         */
        bin = PP_2_BIN(pp);
        mtype = PP_2_MTYPE(pp);
        ppp = &PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype);

        page_sub(ppp, pp);
        page_ctr_sub(mnode, mtype, pp, flags);
        page_freelist_unlock(mnode);

}

void
page_list_sub_pages(page_t *pp, uint_t szc)
{
        kmutex_t *pcm;
        uint_t  bin, mtype;
        int     mnode;

        ASSERT(PAGE_EXCL(pp));
        ASSERT(PP_ISFREE(pp));
        ASSERT(PP_ISAGED(pp));

        /*
         * See comment in page_list_sub().
         */
try_again:
        bin = PP_2_BIN(pp);
        mnode = PP_2_MEM_NODE(pp);
        pcm = PC_BIN_MUTEX(mnode, bin, PG_FREE_LIST);
        mutex_enter(pcm);
        if (PP_2_BIN(pp) != bin) {
                mutex_exit(pcm);
                goto    try_again;
        }

        /*
         * If we're called with a page larger than szc or it got
         * promoted above szc before we locked the freelist then
         * drop pcm and re-lock entire freelist. If page still larger
         * than szc then demote it.
         */
        if (pp->p_szc > szc) {
                mutex_exit(pcm);
                pcm = NULL;
                page_freelist_lock(mnode);
                if (pp->p_szc > szc) {
                        VM_STAT_ADD(vmm_vmstats.plsubpages_szcbig);
                        (void) page_demote(mnode,
                            PFN_BASE(pp->p_pagenum, pp->p_szc), 0,
                            pp->p_szc, szc, PC_NO_COLOR, PC_FREE);
                }
                bin = PP_2_BIN(pp);
        }
        ASSERT(PP_ISFREE(pp));
        ASSERT(PP_ISAGED(pp));
        ASSERT(pp->p_szc <= szc);
        ASSERT(pp == PP_PAGEROOT(pp));

        VM_STAT_ADD(vmm_vmstats.plsub_free[pp->p_szc]);

        mtype = PP_2_MTYPE(pp);
        if (pp->p_szc != 0) {
                page_lpsub(&PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype), pp);
                CHK_LPG(pp, pp->p_szc);
        } else {
                VM_STAT_ADD(vmm_vmstats.plsubpages_szc0);
                page_sub(&PAGE_FREELISTS(mnode, pp->p_szc, bin, mtype), pp);
        }
        page_ctr_sub(mnode, mtype, pp, PG_FREE_LIST);

        if (pcm != NULL) {
                mutex_exit(pcm);
        } else {
                page_freelist_unlock(mnode);
        }

}

/*
 * Add the page to the front of a linked list of pages
 * using the p_next & p_prev pointers for the list.
 * The caller is responsible for protecting the list pointers.
 */
void
mach_page_add(page_t **ppp, page_t *pp)
{
        if (*ppp == NULL) {
                pp->p_next = pp->p_prev = pp;
        } else {
                pp->p_next = *ppp;
                pp->p_prev = (*ppp)->p_prev;
                (*ppp)->p_prev = pp;
                pp->p_prev->p_next = pp;
        }
        *ppp = pp;
}

/*
 * Remove this page from a linked list of pages
 * using the p_next & p_prev pointers for the list.
 *
 * The caller is responsible for protecting the list pointers.
 */
void
mach_page_sub(page_t **ppp, page_t *pp)
{
        ASSERT(PP_ISFREE(pp));

        if (*ppp == NULL || pp == NULL)
                panic("mach_page_sub");

        if (*ppp == pp)
                *ppp = pp->p_next;              /* go to next page */

        if (*ppp == pp)
                *ppp = NULL;                    /* page list is gone */
        else {
                pp->p_prev->p_next = pp->p_next;
                pp->p_next->p_prev = pp->p_prev;
        }
        pp->p_prev = pp->p_next = pp;           /* make pp a list of one */
}

/*
 * Routine fsflush uses to gradually coalesce the free list into larger pages.
 */
void
page_promote_size(page_t *pp, uint_t cur_szc)
{
        pfn_t pfn;
        int mnode;
        int idx;
        int new_szc = cur_szc + 1;
        int full = FULL_REGION_CNT(new_szc);

        pfn = page_pptonum(pp);
        mnode = PFN_2_MEM_NODE(pfn);

        page_freelist_lock(mnode);

        idx = PNUM_TO_IDX(mnode, new_szc, pfn);
        if (PAGE_COUNTERS(mnode, new_szc, idx) == full)
                (void) page_promote(mnode, pfn, new_szc, PC_FREE, PC_MTYPE_ANY);

        page_freelist_unlock(mnode);
}

static uint_t page_promote_err;
static uint_t page_promote_noreloc_err;

/*
 * Create a single larger page (of szc new_szc) from smaller contiguous pages
 * for the given mnode starting at pfnum. Pages involved are on the freelist
 * before the call and may be returned to the caller if requested, otherwise
 * they will be placed back on the freelist.
 * If flags is PC_ALLOC, then the large page will be returned to the user in
 * a state which is consistent with a page being taken off the freelist.  If
 * we failed to lock the new large page, then we will return NULL to the
 * caller and put the large page on the freelist instead.
 * If flags is PC_FREE, then the large page will be placed on the freelist,
 * and NULL will be returned.
 * The caller is responsible for locking the freelist as well as any other
 * accounting which needs to be done for a returned page.
 *
 * RFE: For performance pass in pp instead of pfnum so
 *      we can avoid excessive calls to page_numtopp_nolock().
 *      This would depend on an assumption that all contiguous
 *      pages are in the same memseg so we can just add/dec
 *      our pp.
 *
 * Lock ordering:
 *
 *      There is a potential but rare deadlock situation
 *      for page promotion and demotion operations. The problem
 *      is there are two paths into the freelist manager and
 *      they have different lock orders:
 *
 *      page_create()
 *              lock freelist
 *              page_lock(EXCL)
 *              unlock freelist
 *              return
 *              caller drops page_lock
 *
 *      page_free() and page_reclaim()
 *              caller grabs page_lock(EXCL)
 *
 *              lock freelist
 *              unlock freelist
 *              drop page_lock
 *
 *      What prevents a thread in page_create() from deadlocking
 *      with a thread freeing or reclaiming the same page is the
 *      page_trylock() in page_get_freelist(). If the trylock fails
 *      it skips the page.
 *
 *      The lock ordering for promotion and demotion is the same as
 *      for page_create(). Since the same deadlock could occur during
 *      page promotion and freeing or reclaiming of a page on the
 *      cache list we might have to fail the operation and undo what
 *      have done so far. Again this is rare.
 */
page_t *
page_promote(int mnode, pfn_t pfnum, uchar_t new_szc, int flags, int mtype)
{
        page_t          *pp, *pplist, *tpp, *start_pp;
        pgcnt_t         new_npgs, npgs;
        uint_t          bin;
        pgcnt_t         tmpnpgs, pages_left;
        uint_t          noreloc;
        int             which_list;
        ulong_t         index;
        kmutex_t        *phm;

        /*
         * General algorithm:
         * Find the starting page
         * Walk each page struct removing it from the freelist,
         * and linking it to all the other pages removed.
         * Once all pages are off the freelist,
         * walk the list, modifying p_szc to new_szc and what
         * ever other info needs to be done to create a large free page.
         * According to the flags, either return the page or put it
         * on the freelist.
         */

        start_pp = page_numtopp_nolock(pfnum);
        ASSERT(start_pp && (start_pp->p_pagenum == pfnum));
        new_npgs = page_get_pagecnt(new_szc);
        ASSERT(IS_P2ALIGNED(pfnum, new_npgs));

        /* don't return page of the wrong mtype */
        if (mtype != PC_MTYPE_ANY && mtype != PP_2_MTYPE(start_pp))
                        return (NULL);

        /*
         * Loop through smaller pages to confirm that all pages
         * give the same result for PP_ISNORELOC().
         * We can check this reliably here as the protocol for setting
         * P_NORELOC requires pages to be taken off the free list first.
         */
        noreloc = PP_ISNORELOC(start_pp);
        for (pp = start_pp + new_npgs; --pp > start_pp; ) {
                if (noreloc != PP_ISNORELOC(pp)) {
                        page_promote_noreloc_err++;
                        page_promote_err++;
                        return (NULL);
                }
        }

        pages_left = new_npgs;
        pplist = NULL;
        pp = start_pp;

        /* Loop around coalescing the smaller pages into a big page. */
        while (pages_left) {
                /*
                 * Remove from the freelist.
                 */
                ASSERT(PP_ISFREE(pp));
                bin = PP_2_BIN(pp);
                ASSERT(mnode == PP_2_MEM_NODE(pp));
                mtype = PP_2_MTYPE(pp);
                if (PP_ISAGED(pp)) {

                        /*
                         * PG_FREE_LIST
                         */
                        if (pp->p_szc) {
                                page_lpsub(&PAGE_FREELISTS(mnode,
                                    pp->p_szc, bin, mtype), pp);
                        } else {
                                mach_page_sub(&PAGE_FREELISTS(mnode, 0,
                                    bin, mtype), pp);
                        }
                        which_list = PG_FREE_LIST;
                } else {
                        struct vmobject *obj;

                        ASSERT(pp->p_szc == 0);

                        /*
                         * PG_CACHE_LIST
                         *
                         * Since this page comes from the
                         * cachelist, we must destroy the
                         * vnode association.
                         */
                        if (!page_trylock(pp, SE_EXCL)) {
                                goto fail_promote;
                        }

                        obj = &pp->p_vnode->v_object;

                        /*
                         * We need to be careful not to deadlock
                         * with another thread in page_lookup().
                         * The page_lookup() thread could be holding
                         * the same phm that we need if the two
                         * pages happen to hash to the same phm lock.
                         * At this point we have locked the entire
                         * freelist and page_lookup() could be trying
                         * to grab a freelist lock.
                         */
                        if (!vmobject_trylock(obj)) {
                                page_unlock_nocapture(pp);
                                goto fail_promote;
                        }

                        mach_page_sub(&PAGE_CACHELISTS(mnode, bin, mtype), pp);
                        page_hashout(pp, true);
                        vmobject_unlock(obj);
                        PP_SETAGED(pp);
                        page_unlock_nocapture(pp);
                        which_list = PG_CACHE_LIST;
                }
                page_ctr_sub(mnode, mtype, pp, which_list);

                /*
                 * Concatenate the smaller page(s) onto
                 * the large page list.
                 */
                tmpnpgs = npgs = page_get_pagecnt(pp->p_szc);
                pages_left -= npgs;
                tpp = pp;
                while (npgs--) {
                        tpp->p_szc = new_szc;
                        tpp = tpp->p_next;
                }
                page_list_concat(&pplist, &pp);
                pp += tmpnpgs;
        }
        CHK_LPG(pplist, new_szc);

        /*
         * return the page to the user if requested
         * in the properly locked state.
         */
        if (flags == PC_ALLOC && (page_trylock_cons(pplist, SE_EXCL))) {
                return (pplist);
        }

        /*
         * Otherwise place the new large page on the freelist
         */
        bin = PP_2_BIN(pplist);
        mnode = PP_2_MEM_NODE(pplist);
        mtype = PP_2_MTYPE(pplist);
        page_lpadd(&PAGE_FREELISTS(mnode, new_szc, bin, mtype), pplist);

        page_ctr_add(mnode, mtype, pplist, PG_FREE_LIST);
        return (NULL);

fail_promote:
        /*
         * A thread must have still been freeing or
         * reclaiming the page on the cachelist.
         * To prevent a deadlock undo what we have
         * done sofar and return failure. This
         * situation can only happen while promoting
         * PAGESIZE pages.
         */
        page_promote_err++;
        while (pplist) {
                pp = pplist;
                mach_page_sub(&pplist, pp);
                pp->p_szc = 0;
                bin = PP_2_BIN(pp);
                mtype = PP_2_MTYPE(pp);
                mach_page_add(&PAGE_FREELISTS(mnode, 0, bin, mtype), pp);
                page_ctr_add(mnode, mtype, pp, PG_FREE_LIST);
        }
        return (NULL);

}

/*
 * Break up a large page into smaller size pages.
 * Pages involved are on the freelist before the call and may
 * be returned to the caller if requested, otherwise they will
 * be placed back on the freelist.
 * The caller is responsible for locking the freelist as well as any other
 * accounting which needs to be done for a returned page.
 * If flags is not PC_ALLOC, the color argument is ignored, and thus
 * technically, any value may be passed in but PC_NO_COLOR is the standard
 * which should be followed for clarity's sake.
 * Returns a page whose pfn is < pfnmax
 */
page_t *
page_demote(int mnode, pfn_t pfnum, pfn_t pfnmax, uchar_t cur_szc,
    uchar_t new_szc, int color, int flags)
{
        page_t  *pp, *pplist, *npplist;
        pgcnt_t npgs, n;
        uint_t  bin;
        uint_t  mtype;
        page_t  *ret_pp = NULL;

        ASSERT(cur_szc != 0);
        ASSERT(new_szc < cur_szc);

        pplist = page_numtopp_nolock(pfnum);
        ASSERT(pplist != NULL);

        ASSERT(pplist->p_szc == cur_szc);

        bin = PP_2_BIN(pplist);
        ASSERT(mnode == PP_2_MEM_NODE(pplist));
        mtype = PP_2_MTYPE(pplist);
        page_lpsub(&PAGE_FREELISTS(mnode, cur_szc, bin, mtype), pplist);

        CHK_LPG(pplist, cur_szc);
        page_ctr_sub(mnode, mtype, pplist, PG_FREE_LIST);

        /*
         * Number of PAGESIZE pages for smaller new_szc
         * page.
         */
        npgs = page_get_pagecnt(new_szc);

        while (pplist) {
                pp = pplist;

                ASSERT(pp->p_szc == cur_szc);

                /*
                 * We either break it up into PAGESIZE pages or larger.
                 */
                if (npgs == 1) {        /* PAGESIZE case */
                        mach_page_sub(&pplist, pp);
                        ASSERT(pp->p_szc == cur_szc);
                        ASSERT(new_szc == 0);
                        ASSERT(mnode == PP_2_MEM_NODE(pp));
                        pp->p_szc = new_szc;
                        bin = PP_2_BIN(pp);
                        if ((bin == color) && (flags == PC_ALLOC) &&
                            (ret_pp == NULL) && (pfnmax == 0 ||
                            pp->p_pagenum < pfnmax) &&
                            page_trylock_cons(pp, SE_EXCL)) {
                                ret_pp = pp;
                        } else {
                                mtype = PP_2_MTYPE(pp);
                                mach_page_add(&PAGE_FREELISTS(mnode, 0, bin,
                                    mtype), pp);
                                page_ctr_add(mnode, mtype, pp, PG_FREE_LIST);
                        }
                } else {
                        page_t *try_to_return_this_page = NULL;
                        int count = 0;

                        /*
                         * Break down into smaller lists of pages.
                         */
                        page_list_break(&pplist, &npplist, npgs);

                        pp = pplist;
                        n = npgs;
                        while (n--) {
                                ASSERT(pp->p_szc == cur_szc);
                                /*
                                 * Check whether all the pages in this list
                                 * fit the request criteria.
                                 */
                                if (pfnmax == 0 || pp->p_pagenum < pfnmax) {
                                        count++;
                                }
                                pp->p_szc = new_szc;
                                pp = pp->p_next;
                        }

                        if (count == npgs &&
                            (pfnmax == 0 || pp->p_pagenum < pfnmax)) {
                                try_to_return_this_page = pp;
                        }

                        CHK_LPG(pplist, new_szc);

                        bin = PP_2_BIN(pplist);
                        if (try_to_return_this_page)
                                ASSERT(mnode ==
                                    PP_2_MEM_NODE(try_to_return_this_page));
                        if ((bin == color) && (flags == PC_ALLOC) &&
                            (ret_pp == NULL) && try_to_return_this_page &&
                            page_trylock_cons(try_to_return_this_page,
                            SE_EXCL)) {
                                ret_pp = try_to_return_this_page;
                        } else {
                                mtype = PP_2_MTYPE(pp);
                                page_lpadd(&PAGE_FREELISTS(mnode, new_szc,
                                    bin, mtype), pplist);

                                page_ctr_add(mnode, mtype, pplist,
                                    PG_FREE_LIST);
                        }
                        pplist = npplist;
                }
        }
        return (ret_pp);
}

int mpss_coalesce_disable = 0;

/*
 * Coalesce free pages into a page of the given szc and color if possible.
 * Return the pointer to the page created, otherwise, return NULL.
 *
 * If pfnhi is non-zero, search for large page with pfn range less than pfnhi.
 */
page_t *
page_freelist_coalesce(int mnode, uchar_t szc, uint_t color, uint_t ceq_mask,
    int mtype, pfn_t pfnhi)
{
        int     r = szc;                /* region size */
        int     mrange;
        uint_t  full, bin, color_mask, wrap = 0;
        pfn_t   pfnum, lo, hi;
        size_t  len, idx, idx0;
        pgcnt_t cands = 0, szcpgcnt = page_get_pagecnt(szc);
        page_t  *ret_pp;
        MEM_NODE_ITERATOR_DECL(it);

        if (mpss_coalesce_disable) {
                ASSERT(szc < MMU_PAGE_SIZES);
                VM_STAT_ADD(vmm_vmstats.page_ctrs_coalesce[szc][0]);
                return (NULL);
        }

        ASSERT(szc < mmu_page_sizes);
        color_mask = PAGE_GET_PAGECOLORS(szc) - 1;
        ASSERT(ceq_mask <= color_mask);
        ASSERT(color <= color_mask);
        color &= ceq_mask;

        /* Prevent page_counters dynamic memory from being freed */
        rw_enter(&page_ctrs_rwlock[mnode], RW_READER);

        mrange = MTYPE_2_MRANGE(mnode, mtype);
        ASSERT(mrange < mnode_nranges[mnode]);
        VM_STAT_ADD(vmm_vmstats.page_ctrs_coalesce[r][mrange]);

        /* get pfn range for mtype */
        len = PAGE_COUNTERS_ENTRIES(mnode, r);
        MNODETYPE_2_PFN(mnode, mtype, lo, hi);
        hi++;

        /* use lower limit if given */
        if (pfnhi != PFNNULL && pfnhi < hi)
                hi = pfnhi;

        /* round to szcpgcnt boundaries */
        lo = P2ROUNDUP(lo, szcpgcnt);
        MEM_NODE_ITERATOR_INIT(lo, mnode, szc, &it);
        if (lo == (pfn_t)-1) {
                rw_exit(&page_ctrs_rwlock[mnode]);
                return (NULL);
        }
        hi = hi & ~(szcpgcnt - 1);

        /* set lo to the closest pfn of the right color */
        if (((PFN_2_COLOR(lo, szc, &it) ^ color) & ceq_mask) ||
            (interleaved_mnodes && PFN_2_MEM_NODE(lo) != mnode)) {
                PAGE_NEXT_PFN_FOR_COLOR(lo, szc, color, ceq_mask, color_mask,
                    &it);
        }

        if (hi <= lo) {
                rw_exit(&page_ctrs_rwlock[mnode]);
                return (NULL);
        }

        full = FULL_REGION_CNT(r);

        /* calculate the number of page candidates and initial search index */
        bin = color;
        idx0 = (size_t)(-1);
        do {
                pgcnt_t acand;

                PGCTRS_CANDS_GETVALUECOLOR(mnode, mrange, r, bin, acand);
                if (acand) {
                        idx = PAGE_COUNTERS_CURRENT_COLOR(mnode,
                            r, bin, mrange);
                        idx0 = MIN(idx0, idx);
                        cands += acand;
                }
                bin = ADD_MASKED(bin, 1, ceq_mask, color_mask);
        } while (bin != color);

        if (cands == 0) {
                VM_STAT_ADD(vmm_vmstats.page_ctrs_cands_skip[r][mrange]);
                rw_exit(&page_ctrs_rwlock[mnode]);
                return (NULL);
        }

        pfnum = IDX_TO_PNUM(mnode, r, idx0);
        if (pfnum < lo || pfnum >= hi) {
                pfnum = lo;
        } else {
                MEM_NODE_ITERATOR_INIT(pfnum, mnode, szc, &it);
                if (pfnum == (pfn_t)-1) {
                        pfnum = lo;
                        MEM_NODE_ITERATOR_INIT(pfnum, mnode, szc, &it);
                        ASSERT(pfnum != (pfn_t)-1);
                } else if ((PFN_2_COLOR(pfnum, szc, &it) ^ color) & ceq_mask ||
                    (interleaved_mnodes && PFN_2_MEM_NODE(pfnum) != mnode)) {
                        /* invalid color, get the closest correct pfn */
                        PAGE_NEXT_PFN_FOR_COLOR(pfnum, szc, color, ceq_mask,
                            color_mask, &it);
                        if (pfnum >= hi) {
                                pfnum = lo;
                                MEM_NODE_ITERATOR_INIT(pfnum, mnode, szc, &it);
                        }
                }
        }

        /* set starting index */
        idx0 = PNUM_TO_IDX(mnode, r, pfnum);
        ASSERT(idx0 < len);


        for (idx = idx0; wrap == 0 || (idx < idx0 && wrap < 2); ) {


                if (PAGE_COUNTERS(mnode, r, idx) != full)
                        goto next;

                /*
                 * RFE: For performance maybe we can do something less
                 *      brutal than locking the entire freelist. So far
                 *      this doesn't seem to be a performance problem?
                 */
                page_freelist_lock(mnode);
                if (PAGE_COUNTERS(mnode, r, idx) == full) {
                        ret_pp =
                            page_promote(mnode, pfnum, r, PC_ALLOC, mtype);
                        if (ret_pp != NULL) {
                                VM_STAT_ADD(vmm_vmstats.pfc_coalok[r][mrange]);
                                PAGE_COUNTERS_CURRENT_COLOR(mnode, r,
                                    PFN_2_COLOR(pfnum, szc, &it), mrange) = idx;
                                page_freelist_unlock(mnode);
                                rw_exit(&page_ctrs_rwlock[mnode]);
                                return (ret_pp);
                        }
                } else {
                        VM_STAT_ADD(vmm_vmstats.page_ctrs_changed[r][mrange]);
                }

                page_freelist_unlock(mnode);
                /*
                 * No point looking for another page if we've
                 * already tried all of the ones that
                 * page_ctr_cands indicated.  Stash off where we left
                 * off.
                 * Note: this is not exact since we don't hold the
                 * page_freelist_locks before we initially get the
                 * value of cands for performance reasons, but should
                 * be a decent approximation.
                 */
                if (--cands == 0) {
                        PAGE_COUNTERS_CURRENT_COLOR(mnode, r, color, mrange) =
                            idx;
                        break;
                }
next:
                PAGE_NEXT_PFN_FOR_COLOR(pfnum, szc, color, ceq_mask,
                    color_mask, &it);
                idx = PNUM_TO_IDX(mnode, r, pfnum);
                if (idx >= len || pfnum >= hi) {
wrapit:
                        pfnum = lo;
                        MEM_NODE_ITERATOR_INIT(pfnum, mnode, szc, &it);
                        idx = PNUM_TO_IDX(mnode, r, pfnum);
                        wrap++;
                }
        }

        rw_exit(&page_ctrs_rwlock[mnode]);
        VM_STAT_ADD(vmm_vmstats.page_ctrs_failed[r][mrange]);
        return (NULL);
}

/*
 * For the given mnode, promote as many small pages to large pages as possible.
 * mnode can be -1, which means do them all
 */
void
page_freelist_coalesce_all(int mnode)
{
        int     r;              /* region size */
        int     idx, full;
        size_t  len;
        int doall = interleaved_mnodes || mnode < 0;
        int mlo = doall ? 0 : mnode;
        int mhi = doall ? max_mem_nodes : (mnode + 1);

        VM_STAT_ADD(vmm_vmstats.page_ctrs_coalesce_all);

        if (mpss_coalesce_disable) {
                return;
        }

        /*
         * Lock the entire freelist and coalesce what we can.
         *
         * Always promote to the largest page possible
         * first to reduce the number of page promotions.
         */
        for (mnode = mlo; mnode < mhi; mnode++) {
                rw_enter(&page_ctrs_rwlock[mnode], RW_READER);
                page_freelist_lock(mnode);
        }
        for (r = mmu_page_sizes - 1; r > 0; r--) {
                for (mnode = mlo; mnode < mhi; mnode++) {
                        pgcnt_t cands = 0;
                        int mrange, nranges = mnode_nranges[mnode];

                        for (mrange = 0; mrange < nranges; mrange++) {
                                PGCTRS_CANDS_GETVALUE(mnode, mrange, r, cands);
                                if (cands != 0)
                                        break;
                        }
                        if (cands == 0) {
                                VM_STAT_ADD(vmm_vmstats.
                                    page_ctrs_cands_skip_all);
                                continue;
                        }

                        full = FULL_REGION_CNT(r);
                        len  = PAGE_COUNTERS_ENTRIES(mnode, r);

                        for (idx = 0; idx < len; idx++) {
                                if (PAGE_COUNTERS(mnode, r, idx) == full) {
                                        pfn_t pfnum =
                                            IDX_TO_PNUM(mnode, r, idx);
                                        int tmnode = interleaved_mnodes ?
                                            PFN_2_MEM_NODE(pfnum) : mnode;

                                        ASSERT(pfnum >=
                                            mem_node_config[tmnode].physbase &&
                                            pfnum <
                                            mem_node_config[tmnode].physmax);

                                        (void) page_promote(tmnode,
                                            pfnum, r, PC_FREE, PC_MTYPE_ANY);
                                }
                        }
                        /* shared hpm_counters covers all mnodes, so we quit */
                        if (interleaved_mnodes)
                                break;
                }
        }
        for (mnode = mlo; mnode < mhi; mnode++) {
                page_freelist_unlock(mnode);
                rw_exit(&page_ctrs_rwlock[mnode]);
        }
}

/*
 * This is where all polices for moving pages around
 * to different page size free lists is implemented.
 * Returns 1 on success, 0 on failure.
 *
 * So far these are the priorities for this algorithm in descending
 * order:
 *
 *      1) When servicing a request try to do so with a free page
 *         from next size up. Helps defer fragmentation as long
 *         as possible.
 *
 *      2) Page coalesce on demand. Only when a freelist
 *         larger than PAGESIZE is empty and step 1
 *         will not work since all larger size lists are
 *         also empty.
 *
 * If pfnhi is non-zero, search for large page with pfn range less than pfnhi.
 */

page_t *
page_freelist_split(uchar_t szc, uint_t color, int mnode, int mtype,
    pfn_t pfnlo, pfn_t pfnhi, page_list_walker_t *plw)
{
        uchar_t nszc = szc + 1;
        uint_t  bin, sbin, bin_prev;
        page_t  *pp, *firstpp;
        page_t  *ret_pp = NULL;
        uint_t  color_mask;

        if (nszc == mmu_page_sizes)
                return (NULL);

        ASSERT(nszc < mmu_page_sizes);
        color_mask = PAGE_GET_PAGECOLORS(nszc) - 1;
        bin = sbin = PAGE_GET_NSZ_COLOR(szc, color);
        bin_prev = (plw->plw_bin_split_prev == color) ? INVALID_COLOR :
            PAGE_GET_NSZ_COLOR(szc, plw->plw_bin_split_prev);

        VM_STAT_ADD(vmm_vmstats.pfs_req[szc]);
        /*
         * First try to break up a larger page to fill current size freelist.
         */
        while (plw->plw_bins[nszc] != 0) {

                ASSERT(nszc < mmu_page_sizes);

                /*
                 * If page found then demote it.
                 */
                if (PAGE_FREELISTS(mnode, nszc, bin, mtype)) {
                        page_freelist_lock(mnode);
                        firstpp = pp = PAGE_FREELISTS(mnode, nszc, bin, mtype);

                        /*
                         * If pfnhi is not PFNNULL, look for large page below
                         * pfnhi. PFNNULL signifies no pfn requirement.
                         */
                        if (pp &&
                            ((pfnhi != PFNNULL && pp->p_pagenum >= pfnhi) ||
                            (pfnlo != PFNNULL && pp->p_pagenum < pfnlo))) {
                                do {
                                        pp = pp->p_list.largepg.next;
                                        if (pp == firstpp) {
                                                pp = NULL;
                                                break;
                                        }
                                } while ((pfnhi != PFNNULL &&
                                    pp->p_pagenum >= pfnhi) ||
                                    (pfnlo != PFNNULL &&
                                    pp->p_pagenum < pfnlo));

                                if (pfnhi != PFNNULL && pp != NULL)
                                        ASSERT(pp->p_pagenum < pfnhi);

                                if (pfnlo != PFNNULL && pp != NULL)
                                        ASSERT(pp->p_pagenum >= pfnlo);
                        }
                        if (pp) {
                                uint_t ccolor = page_correct_color(szc, nszc,
                                    color, bin, plw->plw_ceq_mask[szc]);

                                ASSERT(pp->p_szc == nszc);
                                VM_STAT_ADD(vmm_vmstats.pfs_demote[nszc]);
                                ret_pp = page_demote(mnode, pp->p_pagenum,
                                    pfnhi, pp->p_szc, szc, ccolor, PC_ALLOC);
                                if (ret_pp) {
                                        page_freelist_unlock(mnode);
                                        return (ret_pp);
                                }
                        }
                        page_freelist_unlock(mnode);
                }

                /* loop through next size bins */
                bin = ADD_MASKED(bin, 1, plw->plw_ceq_mask[nszc], color_mask);
                plw->plw_bins[nszc]--;

                if (bin == sbin) {
                        uchar_t nnszc = nszc + 1;

                        /* we are done with this page size - check next */
                        if (plw->plw_bins[nnszc] == 0)
                                /* we have already checked next size bins */
                                break;

                        bin = sbin = PAGE_GET_NSZ_COLOR(nszc, bin);
                        if (bin_prev != INVALID_COLOR) {
                                bin_prev = PAGE_GET_NSZ_COLOR(nszc, bin_prev);
                                if (!((bin ^ bin_prev) &
                                    plw->plw_ceq_mask[nnszc]))
                                        break;
                        }
                        ASSERT(nnszc < mmu_page_sizes);
                        color_mask = PAGE_GET_PAGECOLORS(nnszc) - 1;
                        nszc = nnszc;
                        ASSERT(nszc < mmu_page_sizes);
                }
        }

        return (ret_pp);
}

/*
 * Helper routine used only by the freelist code to lock
 * a page. If the page is a large page then it succeeds in
 * locking all the constituent pages or none at all.
 * Returns 1 on sucess, 0 on failure.
 */
static int
page_trylock_cons(page_t *pp, se_t se)
{
        page_t  *tpp, *first_pp = pp;

        /*
         * Fail if can't lock first or only page.
         */
        if (!page_trylock(pp, se)) {
                return (0);
        }

        /*
         * PAGESIZE: common case.
         */
        if (pp->p_szc == 0) {
                return (1);
        }

        /*
         * Large page case.
         */
        tpp = pp->p_next;
        while (tpp != pp) {
                if (!page_trylock(tpp, se)) {
                        /*
                         * On failure unlock what we have locked so far.
                         * We want to avoid attempting to capture these
                         * pages as the pcm mutex may be held which could
                         * lead to a recursive mutex panic.
                         */
                        while (first_pp != tpp) {
                                page_unlock_nocapture(first_pp);
                                first_pp = first_pp->p_next;
                        }
                        return (0);
                }
                tpp = tpp->p_next;
        }
        return (1);
}

/*
 * init context for walking page lists
 * Called when a page of the given szc in unavailable. Sets markers
 * for the beginning of the search to detect when search has
 * completed a full cycle. Sets flags for splitting larger pages
 * and coalescing smaller pages. Page walking procedes until a page
 * of the desired equivalent color is found.
 */
void
page_list_walk_init(uchar_t szc, uint_t flags, uint_t bin, int can_split,
    int use_ceq, page_list_walker_t *plw)
{
        uint_t  nszc, ceq_mask, colors;
        uchar_t ceq = use_ceq ? colorequivszc[szc] : 0;

        ASSERT(szc < mmu_page_sizes);
        colors = PAGE_GET_PAGECOLORS(szc);

        plw->plw_colors = colors;
        plw->plw_color_mask = colors - 1;
        plw->plw_bin_marker = plw->plw_bin0 = bin;
        plw->plw_bin_split_prev = bin;
        plw->plw_bin_step = (szc == 0) ? vac_colors : 1;

        /*
         * if vac aliasing is possible make sure lower order color
         * bits are never ignored
         */
        if (vac_colors > 1)
                ceq &= 0xf0;

        /*
         * calculate the number of non-equivalent colors and
         * color equivalency mask
         */
        plw->plw_ceq_dif = colors >> ((ceq >> 4) + (ceq & 0xf));
        ASSERT(szc > 0 || plw->plw_ceq_dif >= vac_colors);
        ASSERT(plw->plw_ceq_dif > 0);
        plw->plw_ceq_mask[szc] = (plw->plw_ceq_dif - 1) << (ceq & 0xf);

        if (flags & PG_MATCH_COLOR) {
                if (cpu_page_colors <  0) {
                        /*
                         * this is a heterogeneous machine with different CPUs
                         * having different size e$ (not supported for ni2/rock
                         */
                        uint_t cpucolors = CPUSETSIZE() >> PAGE_GET_SHIFT(szc);
                        cpucolors = MAX(cpucolors, 1);
                        ceq_mask = plw->plw_color_mask & (cpucolors - 1);
                        plw->plw_ceq_mask[szc] =
                            MIN(ceq_mask, plw->plw_ceq_mask[szc]);
                }
                plw->plw_ceq_dif = 1;
        }

        /* we can split pages in the freelist, but not the cachelist */
        if (can_split) {
                plw->plw_do_split = (szc + 1 < mmu_page_sizes) ? 1 : 0;

                /* set next szc color masks and number of free list bins */
                for (nszc = szc + 1; nszc < mmu_page_sizes; nszc++, szc++) {
                        plw->plw_ceq_mask[nszc] = PAGE_GET_NSZ_MASK(szc,
                            plw->plw_ceq_mask[szc]);
                        plw->plw_bins[nszc] = PAGE_GET_PAGECOLORS(nszc);
                }
                plw->plw_ceq_mask[nszc] = INVALID_MASK;
                plw->plw_bins[nszc] = 0;

        } else {
                ASSERT(szc == 0);
                plw->plw_do_split = 0;
                plw->plw_bins[1] = 0;
                plw->plw_ceq_mask[1] = INVALID_MASK;
        }
}

/*
 * set mark to flag where next split should occur
 */
#define PAGE_SET_NEXT_SPLIT_MARKER(szc, nszc, bin, plw) {                    \
        uint_t bin_nsz = PAGE_GET_NSZ_COLOR(szc, bin);                       \
        uint_t bin0_nsz = PAGE_GET_NSZ_COLOR(szc, plw->plw_bin0);            \
        uint_t neq_mask = ~plw->plw_ceq_mask[nszc] & plw->plw_color_mask;    \
        plw->plw_split_next =                                                \
                INC_MASKED(bin_nsz, neq_mask, plw->plw_color_mask);          \
        if (!((plw->plw_split_next ^ bin0_nsz) & plw->plw_ceq_mask[nszc])) { \
                plw->plw_split_next =                                        \
                INC_MASKED(plw->plw_split_next,                              \
                    neq_mask, plw->plw_color_mask);                          \
        }                                                                    \
}

uint_t
page_list_walk_next_bin(uchar_t szc, uint_t bin, page_list_walker_t *plw)
{
        uint_t  neq_mask = ~plw->plw_ceq_mask[szc] & plw->plw_color_mask;
        uint_t  bin0_nsz, nbin_nsz, nbin0, nbin;
        uchar_t nszc = szc + 1;

        nbin = ADD_MASKED(bin,
            plw->plw_bin_step, neq_mask, plw->plw_color_mask);

        if (plw->plw_do_split) {
                plw->plw_bin_split_prev = bin;
                PAGE_SET_NEXT_SPLIT_MARKER(szc, nszc, bin, plw);
                plw->plw_do_split = 0;
        }

        if (szc == 0) {
                if (plw->plw_count != 0 || plw->plw_ceq_dif == vac_colors) {
                        if (nbin == plw->plw_bin0 &&
                            (vac_colors == 1 || nbin != plw->plw_bin_marker)) {
                                nbin = ADD_MASKED(nbin, plw->plw_bin_step,
                                    neq_mask, plw->plw_color_mask);
                                plw->plw_bin_split_prev = plw->plw_bin0;
                        }

                        if (vac_colors > 1 && nbin == plw->plw_bin_marker) {
                                plw->plw_bin_marker =
                                    nbin = INC_MASKED(nbin, neq_mask,
                                    plw->plw_color_mask);
                                plw->plw_bin_split_prev = plw->plw_bin0;
                                /*
                                 * large pages all have the same vac color
                                 * so by now we should be done with next
                                 * size page splitting process
                                 */
                                ASSERT(plw->plw_bins[1] == 0);
                                plw->plw_do_split = 0;
                                return (nbin);
                        }

                } else {
                        uint_t bin_jump = (vac_colors == 1) ?
                            (BIN_STEP & ~3) - (plw->plw_bin0 & 3) : BIN_STEP;

                        bin_jump &= ~(vac_colors - 1);

                        nbin0 = ADD_MASKED(plw->plw_bin0, bin_jump, neq_mask,
                            plw->plw_color_mask);

                        if ((nbin0 ^ plw->plw_bin0) & plw->plw_ceq_mask[szc]) {

                                plw->plw_bin_marker = nbin = nbin0;

                                if (plw->plw_bins[nszc] != 0) {
                                        /*
                                         * check if next page size bin is the
                                         * same as the next page size bin for
                                         * bin0
                                         */
                                        nbin_nsz = PAGE_GET_NSZ_COLOR(szc,
                                            nbin);
                                        bin0_nsz = PAGE_GET_NSZ_COLOR(szc,
                                            plw->plw_bin0);

                                        if ((bin0_nsz ^ nbin_nsz) &
                                            plw->plw_ceq_mask[nszc])
                                                plw->plw_do_split = 1;
                                }
                                return (nbin);
                        }
                }
        }

        if (plw->plw_bins[nszc] != 0) {
                nbin_nsz = PAGE_GET_NSZ_COLOR(szc, nbin);
                if (!((plw->plw_split_next ^ nbin_nsz) &
                    plw->plw_ceq_mask[nszc]))
                        plw->plw_do_split = 1;
        }

        return (nbin);
}

page_t *
page_get_mnode_freelist(int mnode, uint_t bin, int mtype, uchar_t szc,
    uint_t flags)
{
        kmutex_t                *pcm;
        page_t                  *pp, *first_pp;
        uint_t                  sbin;
        int                     plw_initialized;
        page_list_walker_t      plw;

        ASSERT(szc < mmu_page_sizes);

        VM_STAT_ADD(vmm_vmstats.pgmf_alloc[szc]);

        MTYPE_START(mnode, mtype, flags);
        if (mtype < 0) {        /* mnode does not have memory in mtype range */
                VM_STAT_ADD(vmm_vmstats.pgmf_allocempty[szc]);
                return (NULL);
        }
try_again:

        plw_initialized = 0;
        plw.plw_ceq_dif = 1;

        /*
         * Only hold one freelist lock at a time, that way we
         * can start anywhere and not have to worry about lock
         * ordering.
         */
        for (plw.plw_count = 0;
            plw.plw_count < plw.plw_ceq_dif; plw.plw_count++) {
                sbin = bin;
                do {
                        if (!PAGE_FREELISTS(mnode, szc, bin, mtype))
                                goto bin_empty_1;

                        pcm = PC_BIN_MUTEX(mnode, bin, PG_FREE_LIST);
                        mutex_enter(pcm);
                        pp = PAGE_FREELISTS(mnode, szc, bin, mtype);
                        if (pp == NULL)
                                goto bin_empty_0;

                        /*
                         * These were set before the page
                         * was put on the free list,
                         * they must still be set.
                         */
                        ASSERT(PP_ISFREE(pp));
                        ASSERT(PP_ISAGED(pp));
                        VERIFY(pp->p_object == NULL);
                        ASSERT(pp->p_vnode == NULL);
                        ASSERT(pp->p_offset == (uoff_t)-1);
                        ASSERT(pp->p_szc == szc);
                        ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) == mnode);

                        /*
                         * Walk down the hash chain.  4k/8k pages are linked
                         * on p_next and p_prev fields. Large pages are a
                         * contiguous group of constituent pages linked
                         * together on their p_next and p_prev fields.  The
                         * large pages are linked together on the hash chain
                         * using p_list.largepg of the base constituent page
                         * of each large page.
                         */
                        first_pp = pp;
                        while (!page_trylock_cons(pp, SE_EXCL)) {
                                if (szc == 0) {
                                        pp = pp->p_next;
                                } else {
                                        pp = pp->p_list.largepg.next;
                                }

                                ASSERT(PP_ISFREE(pp));
                                ASSERT(PP_ISAGED(pp));
                                VERIFY(pp->p_object == NULL);
                                ASSERT(pp->p_vnode == NULL);
                                ASSERT(pp->p_offset == (uoff_t)-1);
                                ASSERT(pp->p_szc == szc);
                                ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) == mnode);

                                if (pp == first_pp)
                                        goto bin_empty_0;
                        }

                        ASSERT(pp != NULL);
                        ASSERT(mtype == PP_2_MTYPE(pp));
                        ASSERT(pp->p_szc == szc);
                        if (szc == 0) {
                                page_sub(&PAGE_FREELISTS(mnode,
                                    szc, bin, mtype), pp);
                        } else {
                                page_lpsub(&PAGE_FREELISTS(mnode,
                                    szc, bin, mtype), pp);
                                CHK_LPG(pp, szc);
                        }
                        page_ctr_sub(mnode, mtype, pp, PG_FREE_LIST);

                        if ((PP_ISFREE(pp) == 0) || (PP_ISAGED(pp) == 0))
                                panic("free page is not. pp %p", (void *)pp);
                        mutex_exit(pcm);

                        VM_STAT_ADD(vmm_vmstats.pgmf_allocok[szc]);
                        return (pp);

bin_empty_0:
                        mutex_exit(pcm);
bin_empty_1:
                        if (plw_initialized == 0) {
                                page_list_walk_init(szc, flags, bin, 1, 1,
                                    &plw);
                                plw_initialized = 1;
                                ASSERT(plw.plw_colors <=
                                    PAGE_GET_PAGECOLORS(szc));
                                ASSERT(plw.plw_colors > 0);
                                ASSERT((plw.plw_colors &
                                    (plw.plw_colors - 1)) == 0);
                                ASSERT(bin < plw.plw_colors);
                                ASSERT(plw.plw_ceq_mask[szc] < plw.plw_colors);
                        }
                        /* calculate the next bin with equivalent color */
                        bin = ADD_MASKED(bin, plw.plw_bin_step,
                            plw.plw_ceq_mask[szc], plw.plw_color_mask);
                } while (sbin != bin);

                /*
                 * color bins are all empty if color match. Try and
                 * satisfy the request by breaking up or coalescing
                 * pages from a different size freelist of the correct
                 * color that satisfies the ORIGINAL color requested.
                 * If that fails then try pages of the same size but
                 * different colors assuming we are not called with
                 * PG_MATCH_COLOR.
                 */
                if (plw.plw_do_split &&
                    (pp = page_freelist_split(szc, bin, mnode,
                    mtype, PFNNULL, PFNNULL, &plw)) != NULL)
                        return (pp);

                if (szc > 0 && (pp = page_freelist_coalesce(mnode, szc,
                    bin, plw.plw_ceq_mask[szc], mtype, PFNNULL)) !=  NULL)
                        return (pp);

                if (plw.plw_ceq_dif > 1)
                        bin = page_list_walk_next_bin(szc, bin, &plw);
        }

        /* if allowed, cycle through additional mtypes */
        MTYPE_NEXT(mnode, mtype, flags);
        if (mtype >= 0)
                goto try_again;

        VM_STAT_ADD(vmm_vmstats.pgmf_allocfailed[szc]);

        return (NULL);
}

/*
 * Returns the count of free pages for 'pp' with size code 'szc'.
 * Note: This function does not return an exact value as the page freelist
 * locks are not held and thus the values in the page_counters may be
 * changing as we walk through the data.
 */
static int
page_freecnt(int mnode, page_t *pp, uchar_t szc)
{
        pgcnt_t pgfree;
        pgcnt_t cnt;
        ssize_t r = szc;        /* region size */
        ssize_t idx;
        int     i;
        int     full, range;

        /* Make sure pagenum passed in is aligned properly */
        ASSERT((pp->p_pagenum & (PNUM_SIZE(szc) - 1)) == 0);
        ASSERT(szc > 0);

        /* Prevent page_counters dynamic memory from being freed */
        rw_enter(&page_ctrs_rwlock[mnode], RW_READER);
        idx = PNUM_TO_IDX(mnode, r, pp->p_pagenum);
        cnt = PAGE_COUNTERS(mnode, r, idx);
        pgfree = cnt << PNUM_SHIFT(r - 1);
        range = FULL_REGION_CNT(szc);

        /* Check for completely full region */
        if (cnt == range) {
                rw_exit(&page_ctrs_rwlock[mnode]);
                return (pgfree);
        }

        while (--r > 0) {
                idx = PNUM_TO_IDX(mnode, r, pp->p_pagenum);
                full = FULL_REGION_CNT(r);
                for (i = 0; i < range; i++, idx++) {
                        cnt = PAGE_COUNTERS(mnode, r, idx);
                        /*
                         * If cnt here is full, that means we have already
                         * accounted for these pages earlier.
                         */
                        if (cnt != full) {
                                pgfree += (cnt << PNUM_SHIFT(r - 1));
                        }
                }
                range *= full;
        }
        rw_exit(&page_ctrs_rwlock[mnode]);
        return (pgfree);
}

/*
 * Called from page_geti_contig_pages to exclusively lock constituent pages
 * starting from 'spp' for page size code 'szc'.
 *
 * If 'ptcpthreshold' is set, the number of free pages needed in the 'szc'
 * region needs to be greater than or equal to the threshold.
 */
static int
page_trylock_contig_pages(int mnode, page_t *spp, uchar_t szc, int flags)
{
        pgcnt_t pgcnt = PNUM_SIZE(szc);
        pgcnt_t pgfree, i;
        page_t *pp;

        VM_STAT_ADD(vmm_vmstats.ptcp[szc]);


        if ((ptcpthreshold == 0) || (flags & PGI_PGCPHIPRI))
                goto skipptcpcheck;
        /*
         * check if there are sufficient free pages available before attempting
         * to trylock. Count is approximate as page counters can change.
         */
        pgfree = page_freecnt(mnode, spp, szc);

        /* attempt to trylock if there are sufficient already free pages */
        if (pgfree < pgcnt/ptcpthreshold) {
                VM_STAT_ADD(vmm_vmstats.ptcpfreethresh[szc]);
                return (0);
        }

skipptcpcheck:

        for (i = 0; i < pgcnt; i++) {
                pp = &spp[i];
                if (!page_trylock(pp, SE_EXCL)) {
                        VM_STAT_ADD(vmm_vmstats.ptcpfailexcl[szc]);
                        while (--i != (pgcnt_t)-1) {
                                pp = &spp[i];
                                ASSERT(PAGE_EXCL(pp));
                                page_unlock_nocapture(pp);
                        }
                        return (0);
                }
                ASSERT(spp[i].p_pagenum == spp->p_pagenum + i);
                if ((pp->p_szc > szc || (szc && pp->p_szc == szc)) &&
                    !PP_ISFREE(pp)) {
                        VM_STAT_ADD(vmm_vmstats.ptcpfailszc[szc]);
                        ASSERT(i == 0);
                        page_unlock_nocapture(pp);
                        return (0);
                }

                /*
                 * If a page has been marked non-relocatable or has been
                 * explicitly locked in memory, we don't want to relocate it;
                 * unlock the pages and fail the operation.
                 */
                if (PP_ISNORELOC(pp) ||
                    pp->p_lckcnt != 0 || pp->p_cowcnt != 0) {
                        VM_STAT_ADD(vmm_vmstats.ptcpfailcage[szc]);
                        while (i != (pgcnt_t)-1) {
                                pp = &spp[i];
                                ASSERT(PAGE_EXCL(pp));
                                page_unlock_nocapture(pp);
                                i--;
                        }
                        return (0);
                }
        }
        VM_STAT_ADD(vmm_vmstats.ptcpok[szc]);
        return (1);
}

/*
 * Claim large page pointed to by 'pp'. 'pp' is the starting set
 * of 'szc' constituent pages that had been locked exclusively previously.
 * Will attempt to relocate constituent pages in use.
 */
static page_t *
page_claim_contig_pages(page_t *pp, uchar_t szc, int flags)
{
        spgcnt_t pgcnt, npgs, i;
        page_t *targpp, *rpp, *hpp;
        page_t *replpp = NULL;
        page_t *pplist = NULL;

        ASSERT(pp != NULL);

        pgcnt = page_get_pagecnt(szc);
        while (pgcnt) {
                ASSERT(PAGE_EXCL(pp));
                ASSERT(!PP_ISNORELOC(pp));
                if (PP_ISFREE(pp)) {
                        /*
                         * If this is a PG_FREE_LIST page then its
                         * size code can change underneath us due to
                         * page promotion or demotion. As an optimzation
                         * use page_list_sub_pages() instead of
                         * page_list_sub().
                         */
                        if (PP_ISAGED(pp)) {
                                page_list_sub_pages(pp, szc);
                                if (pp->p_szc == szc) {
                                        return (pp);
                                }
                                ASSERT(pp->p_szc < szc);
                                npgs = page_get_pagecnt(pp->p_szc);
                                hpp = pp;
                                for (i = 0; i < npgs; i++, pp++) {
                                        pp->p_szc = szc;
                                }
                                page_list_concat(&pplist, &hpp);
                                pgcnt -= npgs;
                                continue;
                        }
                        ASSERT(!PP_ISAGED(pp));
                        ASSERT(pp->p_szc == 0);
                        page_list_sub(pp, PG_CACHE_LIST);
                        page_hashout(pp, false);
                        PP_SETAGED(pp);
                        pp->p_szc = szc;
                        page_list_concat(&pplist, &pp);
                        pp++;
                        pgcnt--;
                        continue;
                }
                npgs = page_get_pagecnt(pp->p_szc);

                /*
                 * page_create_wait freemem accounting done by caller of
                 * page_get_freelist and not necessary to call it prior to
                 * calling page_get_replacement_page.
                 *
                 * page_get_replacement_page can call page_get_contig_pages
                 * to acquire a large page (szc > 0); the replacement must be
                 * smaller than the contig page size to avoid looping or
                 * szc == 0 and PGI_PGCPSZC0 is set.
                 */
                if (pp->p_szc < szc || (szc == 0 && (flags & PGI_PGCPSZC0))) {
                        replpp = page_get_replacement_page(pp, NULL, 0);
                        if (replpp) {
                                npgs = page_get_pagecnt(pp->p_szc);
                                ASSERT(npgs <= pgcnt);
                                targpp = pp;
                        }
                }

                /*
                 * If replacement is NULL or do_page_relocate fails, fail
                 * coalescing of pages.
                 */
                if (replpp == NULL || (do_page_relocate(&targpp, &replpp, 0,
                    &npgs, NULL) != 0)) {
                        /*
                         * Unlock un-processed target list
                         */
                        while (pgcnt--) {
                                ASSERT(PAGE_EXCL(pp));
                                page_unlock_nocapture(pp);
                                pp++;
                        }
                        /*
                         * Free the processed target list.
                         */
                        while (pplist) {
                                pp = pplist;
                                page_sub(&pplist, pp);
                                ASSERT(PAGE_EXCL(pp));
                                ASSERT(pp->p_szc == szc);
                                ASSERT(PP_ISFREE(pp));
                                ASSERT(PP_ISAGED(pp));
                                pp->p_szc = 0;
                                page_list_add(pp, PG_FREE_LIST | PG_LIST_TAIL);
                                page_unlock_nocapture(pp);
                        }

                        if (replpp != NULL)
                                page_free_replacement_page(replpp);

                        return (NULL);
                }
                ASSERT(pp == targpp);

                ASSERT(hpp = pp); /* That's right, it's an assignment */

                pp += npgs;
                pgcnt -= npgs;

                while (npgs--) {
                        ASSERT(PAGE_EXCL(targpp));
                        ASSERT(!PP_ISFREE(targpp));
                        ASSERT(!PP_ISNORELOC(targpp));
                        PP_SETFREE(targpp);
                        ASSERT(PP_ISAGED(targpp));
                        ASSERT(targpp->p_szc < szc || (szc == 0 &&
                            (flags & PGI_PGCPSZC0)));
                        targpp->p_szc = szc;
                        targpp = targpp->p_next;

                        rpp = replpp;
                        ASSERT(rpp != NULL);
                        page_sub(&replpp, rpp);
                        ASSERT(PAGE_EXCL(rpp));
                        ASSERT(!PP_ISFREE(rpp));
                        page_unlock_nocapture(rpp);
                }
                ASSERT(targpp == hpp);
                ASSERT(replpp == NULL);
                page_list_concat(&pplist, &targpp);
        }
        CHK_LPG(pplist, szc);
        return (pplist);
}

/*
 * called from page_get_contig_pages to search 'pfnlo' thru 'pfnhi' to claim a
 * page with size code 'szc'. Claiming such a page requires acquiring
 * exclusive locks on all constituent pages (page_trylock_contig_pages),
 * relocating pages in use and concatenating these constituent pages into a
 * large page.
 *
 * The page lists do not have such a large page and page_freelist_split has
 * already failed to demote larger pages and/or coalesce smaller free pages.
 *
 * 'flags' may specify PG_COLOR_MATCH which would limit the search of large
 * pages with the same color as 'bin'.
 *
 * 'pfnflag' specifies the subset of the pfn range to search.
 */

static page_t *
page_geti_contig_pages(int mnode, uint_t bin, uchar_t szc, int flags,
    pfn_t pfnlo, pfn_t pfnhi, pgcnt_t pfnflag)
{
        struct memseg *mseg;
        pgcnt_t szcpgcnt = page_get_pagecnt(szc);
        pgcnt_t szcpgmask = szcpgcnt - 1;
        pfn_t   randpfn;
        page_t *pp, *randpp, *endpp;
        uint_t colors, ceq_mask;
        uint_t color_mask __unused;
        pfn_t hi, lo;
        uint_t skip;
        MEM_NODE_ITERATOR_DECL(it);

        ASSERT(szc != 0 || (flags & PGI_PGCPSZC0));

        pfnlo = P2ROUNDUP(pfnlo, szcpgcnt);

        if ((pfnhi - pfnlo) + 1 < szcpgcnt || pfnlo >= pfnhi)
                return (NULL);

        ASSERT(szc < mmu_page_sizes);

        colors = PAGE_GET_PAGECOLORS(szc);
        color_mask = colors - 1;
        if ((colors > 1) && (flags & PG_MATCH_COLOR)) {
                uchar_t ceq = colorequivszc[szc];
                uint_t  ceq_dif = colors >> ((ceq >> 4) + (ceq & 0xf));

                ASSERT(ceq_dif > 0);
                ceq_mask = (ceq_dif - 1) << (ceq & 0xf);
        } else {
                ceq_mask = 0;
        }

        ASSERT(bin < colors);

        /* clear "non-significant" color bits */
        bin &= ceq_mask;

        /*
         * trim the pfn range to search based on pfnflag. pfnflag is set
         * when there have been previous page_get_contig_page failures to
         * limit the search.
         *
         * The high bit in pfnflag specifies the number of 'slots' in the
         * pfn range and the remainder of pfnflag specifies which slot.
         * For example, a value of 1010b would mean the second slot of
         * the pfn range that has been divided into 8 slots.
         */
        if (pfnflag > 1) {
                int     slots = 1 << (highbit(pfnflag) - 1);
                int     slotid = pfnflag & (slots - 1);
                pgcnt_t szcpages;
                int     slotlen;

                pfnhi = P2ALIGN((pfnhi + 1), szcpgcnt) - 1;
                szcpages = ((pfnhi - pfnlo) + 1) / szcpgcnt;
                slotlen = howmany(szcpages, slots);
                /* skip if 'slotid' slot is empty */
                if (slotid * slotlen >= szcpages)
                        return (NULL);
                pfnlo = pfnlo + (((slotid * slotlen) % szcpages) * szcpgcnt);
                ASSERT(pfnlo < pfnhi);
                if (pfnhi > pfnlo + (slotlen * szcpgcnt))
                        pfnhi = pfnlo + (slotlen * szcpgcnt) - 1;
        }

        /*
         * This routine is can be called recursively so we shouldn't
         * acquire a reader lock if a write request is pending. This
         * could lead to a deadlock with the DR thread.
         *
         * Returning NULL informs the caller that we could not get
         * a contig page with the required characteristics.
         */

        if (!memsegs_trylock(0))
                return (NULL);

        /*
         * loop through memsegs to look for contig page candidates
         */

        for (mseg = memsegs; mseg != NULL; mseg = mseg->next) {
                if (pfnhi < mseg->pages_base || pfnlo >= mseg->pages_end) {
                        /* no overlap */
                        continue;
                }

                if (mseg->pages_end - mseg->pages_base < szcpgcnt)
                        /* mseg too small */
                        continue;

                lo = MAX(pfnlo, mseg->pages_base);
                hi = MIN(pfnhi, (mseg->pages_end - 1));

                /* round to szcpgcnt boundaries */
                lo = P2ROUNDUP(lo, szcpgcnt);

                MEM_NODE_ITERATOR_INIT(lo, mnode, szc, &it);
                hi = P2ALIGN((hi + 1), szcpgcnt) - 1;

                if (hi <= lo)
                        continue;

                /*
                 * set lo to point to the pfn for the desired bin. Large
                 * page sizes may only have a single page color
                 */
                skip = szcpgcnt;
                if (ceq_mask > 0 || interleaved_mnodes) {
                        /* set lo to point at appropriate color */
                        if (((PFN_2_COLOR(lo, szc, &it) ^ bin) & ceq_mask) ||
                            (interleaved_mnodes &&
                            PFN_2_MEM_NODE(lo) != mnode)) {
                                PAGE_NEXT_PFN_FOR_COLOR(lo, szc, bin, ceq_mask,
                                    color_mask, &it);
                        }
                        if (hi <= lo)
                                /* mseg cannot satisfy color request */
                                continue;
                }

                /* randomly choose a point between lo and hi to begin search */

                randpfn = (pfn_t)GETTICK();
                randpfn = ((randpfn % (hi - lo)) + lo) & ~(skip - 1);
                MEM_NODE_ITERATOR_INIT(randpfn, mnode, szc, &it);
                if (ceq_mask || interleaved_mnodes || randpfn == (pfn_t)-1) {
                        if (randpfn != (pfn_t)-1) {
                                PAGE_NEXT_PFN_FOR_COLOR(randpfn, szc, bin,
                                    ceq_mask, color_mask, &it);
                        }
                        if (randpfn >= hi) {
                                randpfn = lo;
                                MEM_NODE_ITERATOR_INIT(randpfn, mnode, szc,
                                    &it);
                        }
                }
                randpp = mseg->pages + (randpfn - mseg->pages_base);

                ASSERT(randpp->p_pagenum == randpfn);

                pp = randpp;
                endpp =  mseg->pages + (hi - mseg->pages_base) + 1;

                ASSERT(randpp + szcpgcnt <= endpp);

                do {
                        ASSERT(!(pp->p_pagenum & szcpgmask));
                        ASSERT(((PP_2_BIN(pp) ^ bin) & ceq_mask) == 0);

                        if (page_trylock_contig_pages(mnode, pp, szc, flags)) {
                                /* pages unlocked by page_claim on failure */
                                if (page_claim_contig_pages(pp, szc, flags)) {
                                        memsegs_unlock(0);
                                        return (pp);
                                }
                        }

                        if (ceq_mask == 0 && !interleaved_mnodes) {
                                pp += skip;
                        } else {
                                pfn_t pfn = pp->p_pagenum;

                                PAGE_NEXT_PFN_FOR_COLOR(pfn, szc, bin,
                                    ceq_mask, color_mask, &it);
                                if (pfn == (pfn_t)-1) {
                                        pp = endpp;
                                } else {
                                        pp = mseg->pages +
                                            (pfn - mseg->pages_base);
                                }
                        }
                        if (pp >= endpp) {
                                /* start from the beginning */
                                MEM_NODE_ITERATOR_INIT(lo, mnode, szc, &it);
                                pp = mseg->pages + (lo - mseg->pages_base);
                                ASSERT(pp->p_pagenum == lo);
                                ASSERT(pp + szcpgcnt <= endpp);
                        }
                } while (pp != randpp);
        }
        memsegs_unlock(0);
        return (NULL);
}


/*
 * controlling routine that searches through physical memory in an attempt to
 * claim a large page based on the input parameters.
 * on the page free lists.
 *
 * calls page_geti_contig_pages with an initial pfn range from the mnode
 * and mtype. page_geti_contig_pages will trim off the parts of the pfn range
 * that overlaps with the kernel cage or does not match the requested page
 * color if PG_MATCH_COLOR is set.  Since this search is very expensive,
 * page_geti_contig_pages may further limit the search range based on
 * previous failure counts (pgcpfailcnt[]).
 *
 * for PGI_PGCPSZC0 requests, page_get_contig_pages will relocate a base
 * pagesize page that satisfies mtype.
 */
page_t *
page_get_contig_pages(int mnode, uint_t bin, int mtype, uchar_t szc,
    uint_t flags)
{
        pfn_t           pfnlo, pfnhi;   /* contig pages pfn range */
        page_t          *pp;
        pgcnt_t         pfnflag = 0;    /* no limit on search if 0 */

        VM_STAT_ADD(vmm_vmstats.pgcp_alloc[szc]);

        /* no allocations from cage */
        flags |= PGI_NOCAGE;

        MTYPE_START(mnode, mtype, flags);
        if (mtype < 0) {        /* mnode does not have memory in mtype range */
                VM_STAT_ADD(vmm_vmstats.pgcp_allocempty[szc]);
                return (NULL);
        }

        ASSERT(szc > 0 || (flags & PGI_PGCPSZC0));

        /* do not limit search and ignore color if hi pri */

        if (pgcplimitsearch && ((flags & PGI_PGCPHIPRI) == 0))
                pfnflag = pgcpfailcnt[szc];

        /* remove color match to improve chances */

        if (flags & PGI_PGCPHIPRI || pfnflag)
                flags &= ~PG_MATCH_COLOR;

        do {
                /* get pfn range based on mnode and mtype */
                MNODETYPE_2_PFN(mnode, mtype, pfnlo, pfnhi);

                ASSERT(pfnhi >= pfnlo);

                pp = page_geti_contig_pages(mnode, bin, szc, flags,
                    pfnlo, pfnhi, pfnflag);

                if (pp != NULL) {
                        pfnflag = pgcpfailcnt[szc];
                        if (pfnflag) {
                                /* double the search size */
                                pgcpfailcnt[szc] = pfnflag >> 1;
                        }
                        VM_STAT_ADD(vmm_vmstats.pgcp_allocok[szc]);
                        return (pp);
                }
                MTYPE_NEXT(mnode, mtype, flags);
        } while (mtype >= 0);

        VM_STAT_ADD(vmm_vmstats.pgcp_allocfailed[szc]);
        return (NULL);
}

#if defined(__i386) || defined(__amd64)
/*
 * Determine the likelihood of finding/coalescing a szc page.
 * Return 0 if the likelihood is small otherwise return 1.
 *
 * For now, be conservative and check only 1g pages and return 0
 * if there had been previous coalescing failures and the szc pages
 * needed to satisfy request would exhaust most of freemem.
 */
int
page_chk_freelist(uint_t szc)
{
        pgcnt_t         pgcnt;

        if (szc <= 1)
                return (1);

        pgcnt = page_get_pagecnt(szc);
        if (pgcpfailcnt[szc] && pgcnt + throttlefree >= freemem) {
                VM_STAT_ADD(vmm_vmstats.pcf_deny[szc]);
                return (0);
        }
        VM_STAT_ADD(vmm_vmstats.pcf_allow[szc]);
        return (1);
}
#endif

/*
 * Find the `best' page on the freelist for this (obj,off) (as,vaddr) pair.
 *
 * Does its own locking and accounting.
 * If PG_MATCH_COLOR is set, then NULL will be returned if there are no
 * pages of the proper color even if there are pages of a different color.
 *
 * Finds a page, removes it, THEN locks it.
 */

/*ARGSUSED*/
page_t *
page_get_freelist(struct vmobject *obj, uoff_t off, struct seg *seg,
        caddr_t vaddr, size_t size, uint_t flags, struct lgrp *lgrp)
{
        struct as       *as = seg->s_as;
        page_t          *pp = NULL;
        ulong_t         bin;
        uchar_t         szc;
        int             mnode;
        int             mtype;
        page_t          *(*page_get_func)(int, uint_t, int, uchar_t, uint_t);
        lgrp_mnode_cookie_t     lgrp_cookie;

        page_get_func = page_get_mnode_freelist;

        /*
         * If we aren't passed a specific lgroup, or passed a freed lgrp
         * assume we wish to allocate near to the current thread's home.
         */
        if (!LGRP_EXISTS(lgrp))
                lgrp = lgrp_home_lgrp();

        flags &= ~PG_NORELOC;
        flags |= PGI_NOCAGE;

        MTYPE_INIT(mtype, obj->vnode, vaddr, flags, size);

        /*
         * Convert size to page size code.
         */
        if ((szc = page_szc(size)) == (uchar_t)-1)
                panic("page_get_freelist: illegal page size request");
        ASSERT(szc < mmu_page_sizes);

        VM_STAT_ADD(vmm_vmstats.pgf_alloc[szc]);

        AS_2_BIN(as, seg, obj->vnode, vaddr, bin, szc);

        ASSERT(bin < PAGE_GET_PAGECOLORS(szc));

        /*
         * Try to get a local page first, but try remote if we can't
         * get a page of the right color.
         */
pgretry:
        LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp, LGRP_SRCH_LOCAL);
        while ((mnode = lgrp_memnode_choose(&lgrp_cookie)) >= 0) {
                pp = page_get_func(mnode, bin, mtype, szc, flags);
                if (pp != NULL) {
                        VM_STAT_ADD(vmm_vmstats.pgf_allocok[szc]);
                        DTRACE_PROBE4(page__get,
                            lgrp_t *, lgrp,
                            int, mnode,
                            ulong_t, bin,
                            uint_t, flags);
                        return (pp);
                }
        }
        ASSERT(pp == NULL);

        /*
         * for non-SZC0 PAGESIZE requests, check cachelist before checking
         * remote free lists.  Caller expected to call page_get_cachelist which
         * will check local cache lists and remote free lists.
         */
        if (szc == 0 && ((flags & PGI_PGCPSZC0) == 0)) {
                VM_STAT_ADD(vmm_vmstats.pgf_allocdeferred);
                return (NULL);
        }

        ASSERT(szc > 0 || (flags & PGI_PGCPSZC0));

        lgrp_stat_add(lgrp->lgrp_id, LGRP_NUM_ALLOC_FAIL, 1);

        if (!(flags & PG_LOCAL)) {
                /*
                 * Try to get a non-local freelist page.
                 */
                LGRP_MNODE_COOKIE_UPGRADE(lgrp_cookie);
                while ((mnode = lgrp_memnode_choose(&lgrp_cookie)) >= 0) {
                        pp = page_get_func(mnode, bin, mtype, szc, flags);
                        if (pp != NULL) {
                                DTRACE_PROBE4(page__get,
                                    lgrp_t *, lgrp,
                                    int, mnode,
                                    ulong_t, bin,
                                    uint_t, flags);
                                VM_STAT_ADD(vmm_vmstats.pgf_allocokrem[szc]);
                                return (pp);
                        }
                }
                ASSERT(pp == NULL);
        }

        /*
         * when the cage is off chances are page_get_contig_pages() will fail
         * to lock a large page chunk therefore when the cage is off it's not
         * called by default.  this can be changed via /etc/system.
         *
         * page_get_contig_pages() also called to acquire a base pagesize page
         * for page_create_get_something().
         */
        if (!(flags & PG_NORELOC) && (pg_contig_disable == 0) &&
            (pg_lpgcreate_nocage || szc == 0) &&
            (page_get_func != page_get_contig_pages)) {

                VM_STAT_ADD(vmm_vmstats.pgf_allocretry[szc]);
                page_get_func = page_get_contig_pages;
                goto pgretry;
        }

        if (!(flags & PG_LOCAL) && pgcplimitsearch &&
            page_get_func == page_get_contig_pages)
                SETPGCPFAILCNT(szc);

        VM_STAT_ADD(vmm_vmstats.pgf_allocfailed[szc]);
        return (NULL);
}

/*
 * Find the `best' page on the cachelist for this (obj,off) (as,vaddr) pair.
 *
 * Does its own locking.
 * If PG_MATCH_COLOR is set, then NULL will be returned if there are no
 * pages of the proper color even if there are pages of a different color.
 * Otherwise, scan the bins for ones with pages.  For each bin with pages,
 * try to lock one of them.  If no page can be locked, try the
 * next bin.  Return NULL if a page can not be found and locked.
 *
 * Finds a pages, trys to lock it, then removes it.
 */

/*ARGSUSED*/
struct page *
page_get_cachelist(struct vmobject *obj, uoff_t off, struct seg *seg,
    caddr_t vaddr, uint_t flags, struct lgrp *lgrp)
{
        page_t          *pp;
        struct as       *as = seg->s_as;
        ulong_t         bin;
        int             mnode;
        int             mtype;
        lgrp_mnode_cookie_t     lgrp_cookie;

        /*
         * If we aren't passed a specific lgroup, or pasased a freed lgrp
         * assume we wish to allocate near to the current thread's home.
         */
        if (!LGRP_EXISTS(lgrp))
                lgrp = lgrp_home_lgrp();

        flags &= ~PG_NORELOC;
        flags |= PGI_NOCAGE;

        if ((flags & (PG_NORELOC | PG_PANIC | PG_PUSHPAGE)) == PG_NORELOC)
                return (NULL);

        AS_2_BIN(as, seg, obj->vnode, vaddr, bin, 0);

        ASSERT(bin < PAGE_GET_PAGECOLORS(0));

        MTYPE_INIT(mtype, obj->vnode, vaddr, flags, MMU_PAGESIZE);

        VM_STAT_ADD(vmm_vmstats.pgc_alloc);

        /*
         * Try local cachelists first
         */
        LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp, LGRP_SRCH_LOCAL);
        while ((mnode = lgrp_memnode_choose(&lgrp_cookie)) >= 0) {
                pp = page_get_mnode_cachelist(bin, flags, mnode, mtype);
                if (pp != NULL) {
                        VM_STAT_ADD(vmm_vmstats.pgc_allocok);
                        DTRACE_PROBE4(page__get,
                            lgrp_t *, lgrp,
                            int, mnode,
                            ulong_t, bin,
                            uint_t, flags);
                        return (pp);
                }
        }

        lgrp_stat_add(lgrp->lgrp_id, LGRP_NUM_ALLOC_FAIL, 1);

        /*
         * Try freelists/cachelists that are farther away
         * This is our only chance to allocate remote pages for PAGESIZE
         * requests.
         */
        LGRP_MNODE_COOKIE_UPGRADE(lgrp_cookie);
        while ((mnode = lgrp_memnode_choose(&lgrp_cookie)) >= 0) {
                pp = page_get_mnode_freelist(mnode, bin, mtype,
                    0, flags);
                if (pp != NULL) {
                        VM_STAT_ADD(vmm_vmstats.pgc_allocokdeferred);
                        DTRACE_PROBE4(page__get,
                            lgrp_t *, lgrp,
                            int, mnode,
                            ulong_t, bin,
                            uint_t, flags);
                        return (pp);
                }
                pp = page_get_mnode_cachelist(bin, flags, mnode, mtype);
                if (pp != NULL) {
                        VM_STAT_ADD(vmm_vmstats.pgc_allocokrem);
                        DTRACE_PROBE4(page__get,
                            lgrp_t *, lgrp,
                            int, mnode,
                            ulong_t, bin,
                            uint_t, flags);
                        return (pp);
                }
        }

        VM_STAT_ADD(vmm_vmstats.pgc_allocfailed);
        return (NULL);
}

page_t *
page_get_mnode_cachelist(uint_t bin, uint_t flags, int mnode, int mtype)
{
        kmutex_t                *pcm;
        page_t                  *pp, *first_pp;
        uint_t                  sbin;
        int                     plw_initialized;
        page_list_walker_t      plw;

        VM_STAT_ADD(vmm_vmstats.pgmc_alloc);

        MTYPE_START(mnode, mtype, flags);
        if (mtype < 0) {        /* mnode does not have memory in mtype range */
                VM_STAT_ADD(vmm_vmstats.pgmc_allocempty);
                return (NULL);
        }

try_again:

        plw_initialized = 0;
        plw.plw_ceq_dif = 1;

        /*
         * Only hold one cachelist lock at a time, that way we
         * can start anywhere and not have to worry about lock
         * ordering.
         */

        for (plw.plw_count = 0;
            plw.plw_count < plw.plw_ceq_dif; plw.plw_count++) {
                sbin = bin;
                do {

                        if (!PAGE_CACHELISTS(mnode, bin, mtype))
                                goto bin_empty_1;
                        pcm = PC_BIN_MUTEX(mnode, bin, PG_CACHE_LIST);
                        mutex_enter(pcm);
                        pp = PAGE_CACHELISTS(mnode, bin, mtype);
                        if (pp == NULL)
                                goto bin_empty_0;

                        first_pp = pp;
                        VERIFY(pp->p_object);
                        ASSERT(pp->p_vnode);
                        ASSERT(PP_ISAGED(pp) == 0);
                        ASSERT(pp->p_szc == 0);
                        ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) == mnode);
                        while (!page_trylock(pp, SE_EXCL)) {
                                pp = pp->p_next;
                                ASSERT(pp->p_szc == 0);
                                if (pp == first_pp) {
                                        /*
                                         * We have searched the complete list!
                                         * And all of them (might only be one)
                                         * are locked. This can happen since
                                         * these pages can also be found via
                                         * the hash list. When found via the
                                         * hash list, they are locked first,
                                         * then removed. We give up to let the
                                         * other thread run.
                                         */
                                        pp = NULL;
                                        break;
                                }
                                VERIFY(pp->p_object);
                                ASSERT(pp->p_vnode);
                                ASSERT(PP_ISFREE(pp));
                                ASSERT(PP_ISAGED(pp) == 0);
                                ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) ==
                                    mnode);
                        }

                        if (pp) {
                                page_t  **ppp;
                                /*
                                 * Found and locked a page.
                                 * Pull it off the list.
                                 */
                                ASSERT(mtype == PP_2_MTYPE(pp));
                                ppp = &PAGE_CACHELISTS(mnode, bin, mtype);
                                page_sub(ppp, pp);
                                /*
                                 * Subtract counters before releasing pcm mutex
                                 * to avoid a race with page_freelist_coalesce
                                 * and page_freelist_split.
                                 */
                                page_ctr_sub(mnode, mtype, pp, PG_CACHE_LIST);
                                mutex_exit(pcm);
                                VERIFY(pp->p_object);
                                ASSERT(pp->p_vnode);
                                ASSERT(PP_ISAGED(pp) == 0);
                                VM_STAT_ADD(vmm_vmstats. pgmc_allocok);
                                return (pp);
                        }
bin_empty_0:
                        mutex_exit(pcm);
bin_empty_1:
                        if (plw_initialized == 0) {
                                page_list_walk_init(0, flags, bin, 0, 1, &plw);
                                plw_initialized = 1;
                        }
                        /* calculate the next bin with equivalent color */
                        bin = ADD_MASKED(bin, plw.plw_bin_step,
                            plw.plw_ceq_mask[0], plw.plw_color_mask);
                } while (sbin != bin);

                if (plw.plw_ceq_dif > 1)
                        bin = page_list_walk_next_bin(0, bin, &plw);
        }

        MTYPE_NEXT(mnode, mtype, flags);
        if (mtype >= 0)
                goto try_again;

        VM_STAT_ADD(vmm_vmstats.pgmc_allocfailed);
        return (NULL);
}

#ifdef DEBUG
#define REPL_PAGE_STATS
#endif /* DEBUG */

#ifdef REPL_PAGE_STATS
struct repl_page_stats {
        uint_t  ngets;
        uint_t  ngets_noreloc;
        uint_t  npgr_noreloc;
        uint_t  nnopage_first;
        uint_t  nnopage;
        uint_t  nhashout;
        uint_t  nnofree;
        uint_t  nnext_pp;
} repl_page_stats;
#define REPL_STAT_INCR(v)       atomic_inc_32(&repl_page_stats.v)
#else /* REPL_PAGE_STATS */
#define REPL_STAT_INCR(v)
#endif /* REPL_PAGE_STATS */

int     pgrppgcp;

/*
 * The freemem accounting must be done by the caller.
 * First we try to get a replacement page of the same size as like_pp,
 * if that is not possible, then we just get a set of discontiguous
 * PAGESIZE pages.
 */
page_t *
page_get_replacement_page(page_t *orig_like_pp, struct lgrp *lgrp_target,
    uint_t pgrflags)
{
        page_t          *like_pp;
        page_t          *pp, *pplist;
        page_t          *pl = NULL;
        ulong_t         bin;
        int             mnode, page_mnode;
        int             szc;
        spgcnt_t        npgs, pg_cnt;
        pfn_t           pfnum;
        int             mtype;
        int             flags = 0;
        lgrp_mnode_cookie_t     lgrp_cookie;
        lgrp_t          *lgrp;

        REPL_STAT_INCR(ngets);
        like_pp = orig_like_pp;
        ASSERT(PAGE_EXCL(like_pp));

        szc = like_pp->p_szc;
        npgs = page_get_pagecnt(szc);
        /*
         * Now we reset like_pp to the base page_t.
         * That way, we won't walk past the end of this 'szc' page.
         */
        pfnum = PFN_BASE(like_pp->p_pagenum, szc);
        like_pp = page_numtopp_nolock(pfnum);
        ASSERT(like_pp->p_szc == szc);

        VERIFY0(PP_ISNORELOC(like_pp));
        VERIFY0(pgrflags & PGR_NORELOC);

        /*
         * Kernel pages must always be replaced with the same size
         * pages, since we cannot properly handle demotion of kernel
         * pages.
         */
        if (PP_ISKAS(like_pp))
                pgrflags |= PGR_SAMESZC;

        MTYPE_PGR_INIT(mtype, flags, like_pp, page_mnode, npgs);

        while (npgs) {
                pplist = NULL;
                for (;;) {
                        pg_cnt = page_get_pagecnt(szc);
                        bin = PP_2_BIN(like_pp);
                        ASSERT(like_pp->p_szc == orig_like_pp->p_szc);
                        ASSERT(pg_cnt <= npgs);

                        /*
                         * If an lgroup was specified, try to get the
                         * page from that lgroup.
                         * NOTE: Must be careful with code below because
                         *       lgroup may disappear and reappear since there
                         *       is no locking for lgroup here.
                         */
                        if (LGRP_EXISTS(lgrp_target)) {
                                /*
                                 * Keep local variable for lgroup separate
                                 * from lgroup argument since this code should
                                 * only be exercised when lgroup argument
                                 * exists....
                                 */
                                lgrp = lgrp_target;

                                /* Try the lgroup's freelists first */
                                LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp,
                                    LGRP_SRCH_LOCAL);
                                while ((pplist == NULL) &&
                                    (mnode = lgrp_memnode_choose(&lgrp_cookie))
                                    != -1) {
                                        pplist =
                                            page_get_mnode_freelist(mnode, bin,
                                            mtype, szc, flags);
                                }

                                /*
                                 * Now try it's cachelists if this is a
                                 * small page. Don't need to do it for
                                 * larger ones since page_freelist_coalesce()
                                 * already failed.
                                 */
                                if (pplist != NULL || szc != 0)
                                        break;

                                /* Now try it's cachelists */
                                LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp,
                                    LGRP_SRCH_LOCAL);

                                while ((pplist == NULL) &&
                                    (mnode = lgrp_memnode_choose(&lgrp_cookie))
                                    != -1) {
                                        pplist =
                                            page_get_mnode_cachelist(bin, flags,
                                            mnode, mtype);
                                }
                                if (pplist != NULL) {
                                        page_hashout(pplist, false);
                                        PP_SETAGED(pplist);
                                        REPL_STAT_INCR(nhashout);
                                        break;
                                }
                                /* Done looking in this lgroup. Bail out. */
                                break;
                        }

                        /*
                         * No lgroup was specified (or lgroup was removed by
                         * DR, so just try to get the page as close to
                         * like_pp's mnode as possible.
                         * First try the local freelist...
                         */
                        mnode = PP_2_MEM_NODE(like_pp);
                        pplist = page_get_mnode_freelist(mnode, bin,
                            mtype, szc, flags);
                        if (pplist != NULL)
                                break;

                        REPL_STAT_INCR(nnofree);

                        /*
                         * ...then the local cachelist. Don't need to do it for
                         * larger pages cause page_freelist_coalesce() already
                         * failed there anyway.
                         */
                        if (szc == 0) {
                                pplist = page_get_mnode_cachelist(bin, flags,
                                    mnode, mtype);
                                if (pplist != NULL) {
                                        page_hashout(pplist, false);
                                        PP_SETAGED(pplist);
                                        REPL_STAT_INCR(nhashout);
                                        break;
                                }
                        }

                        /* Now try remote freelists */
                        page_mnode = mnode;
                        lgrp =
                            lgrp_hand_to_lgrp(MEM_NODE_2_LGRPHAND(page_mnode));
                        LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp,
                            LGRP_SRCH_HIER);
                        while (pplist == NULL &&
                            (mnode = lgrp_memnode_choose(&lgrp_cookie))
                            != -1) {
                                /*
                                 * Skip local mnode.
                                 */
                                if ((mnode == page_mnode) ||
                                    (mem_node_config[mnode].exists == 0))
                                        continue;

                                pplist = page_get_mnode_freelist(mnode,
                                    bin, mtype, szc, flags);
                        }

                        if (pplist != NULL)
                                break;


                        /* Now try remote cachelists */
                        LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp,
                            LGRP_SRCH_HIER);
                        while (pplist == NULL && szc == 0) {
                                mnode = lgrp_memnode_choose(&lgrp_cookie);
                                if (mnode == -1)
                                        break;
                                /*
                                 * Skip local mnode.
                                 */
                                if ((mnode == page_mnode) ||
                                    (mem_node_config[mnode].exists == 0))
                                        continue;

                                pplist = page_get_mnode_cachelist(bin,
                                    flags, mnode, mtype);

                                if (pplist != NULL) {
                                        page_hashout(pplist, false);
                                        PP_SETAGED(pplist);
                                        REPL_STAT_INCR(nhashout);
                                        break;
                                }
                        }

                        /*
                         * Break out of while loop under the following cases:
                         * - If we successfully got a page.
                         * - If pgrflags specified only returning a specific
                         *   page size and we could not find that page size.
                         * - If we could not satisfy the request with PAGESIZE
                         *   or larger pages.
                         */
                        if (pplist != NULL || szc == 0)
                                break;

                        if ((pgrflags & PGR_SAMESZC) || pgrppgcp) {
                                /* try to find contig page */

                                LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp,
                                    LGRP_SRCH_HIER);

                                while ((pplist == NULL) &&
                                    (mnode =
                                    lgrp_memnode_choose(&lgrp_cookie))
                                    != -1) {
                                        pplist = page_get_contig_pages(
                                            mnode, bin, mtype, szc,
                                            flags | PGI_PGCPHIPRI);
                                }
                                break;
                        }

                        /*
                         * The correct thing to do here is try the next
                         * page size down using szc--. Due to a bug
                         * with the processing of HAT_RELOAD_SHARE
                         * where the sfmmu_ttecnt arrays of all
                         * hats sharing an ISM segment don't get updated,
                         * using intermediate size pages for relocation
                         * can lead to continuous page faults.
                         */
                        szc = 0;
                }

                if (pplist != NULL) {
                        DTRACE_PROBE4(page__get,
                            lgrp_t *, lgrp,
                            int, mnode,
                            ulong_t, bin,
                            uint_t, flags);

                        while (pplist != NULL && pg_cnt--) {
                                ASSERT(pplist != NULL);
                                pp = pplist;
                                page_sub(&pplist, pp);
                                PP_CLRFREE(pp);
                                PP_CLRAGED(pp);
                                page_list_concat(&pl, &pp);
                                npgs--;
                                like_pp = like_pp + 1;
                                REPL_STAT_INCR(nnext_pp);
                        }
                        ASSERT(pg_cnt == 0);
                } else {
                        break;
                }
        }

        if (npgs) {
                /*
                 * We were unable to allocate the necessary number
                 * of pages.
                 * We need to free up any pl.
                 */
                REPL_STAT_INCR(nnopage);
                page_free_replacement_page(pl);
                return (NULL);
        } else {
                return (pl);
        }
}

/*
 * demote a free large page to it's constituent pages
 */
void
page_demote_free_pages(page_t *pp)
{

        int mnode;

        ASSERT(pp != NULL);
        ASSERT(PAGE_LOCKED(pp));
        ASSERT(PP_ISFREE(pp));
        ASSERT(pp->p_szc != 0 && pp->p_szc < mmu_page_sizes);

        mnode = PP_2_MEM_NODE(pp);
        page_freelist_lock(mnode);
        if (pp->p_szc != 0) {
                (void) page_demote(mnode, PFN_BASE(pp->p_pagenum,
                    pp->p_szc), 0, pp->p_szc, 0, PC_NO_COLOR, PC_FREE);
        }
        page_freelist_unlock(mnode);
        ASSERT(pp->p_szc == 0);
}

/*
 * Factor in colorequiv to check additional 'equivalent' bins.
 * colorequiv may be set in /etc/system
 */
void
page_set_colorequiv_arr(void)
{
        if (colorequiv > 1) {
                int i;
                uint_t sv_a = lowbit(colorequiv) - 1;

                if (sv_a > 15)
                        sv_a = 15;

                for (i = 0; i < MMU_PAGE_SIZES; i++) {
                        uint_t colors;
                        uint_t a = sv_a;

                        if ((colors = hw_page_array[i].hp_colors) <= 1) {
                                continue;
                        }
                        while ((colors >> a) == 0)
                                a--;
                        if ((a << 4) > colorequivszc[i]) {
                                colorequivszc[i] = (a << 4);
                        }
                }
        }
}