xref: /titanic_51/usr/src/uts/common/vm/seg_vn.c (revision 505d05c73a6e56769f263d4803b22eddd168ee24)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * VM - shared or copy-on-write from a vnode/anonymous memory.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/t_lock.h>
#include <sys/errno.h>
#include <sys/systm.h>
#include <sys/mman.h>
#include <sys/debug.h>
#include <sys/cred.h>
#include <sys/vmsystm.h>
#include <sys/tuneable.h>
#include <sys/bitmap.h>
#include <sys/swap.h>
#include <sys/kmem.h>
#include <sys/sysmacros.h>
#include <sys/vtrace.h>
#include <sys/cmn_err.h>
#include <sys/vm.h>
#include <sys/dumphdr.h>
#include <sys/lgrp.h>

#include <vm/hat.h>
#include <vm/as.h>
#include <vm/seg.h>
#include <vm/seg_vn.h>
#include <vm/pvn.h>
#include <vm/anon.h>
#include <vm/page.h>
#include <vm/vpage.h>

/*
 * Private seg op routines.
 */
static int	segvn_dup(struct seg *seg, struct seg *newseg);
static int	segvn_unmap(struct seg *seg, caddr_t addr, size_t len);
static void	segvn_free(struct seg *seg);
static faultcode_t segvn_fault(struct hat *hat, struct seg *seg,
		    caddr_t addr, size_t len, enum fault_type type,
		    enum seg_rw rw);
static faultcode_t segvn_faulta(struct seg *seg, caddr_t addr);
static int	segvn_setprot(struct seg *seg, caddr_t addr,
		    size_t len, uint_t prot);
static int	segvn_checkprot(struct seg *seg, caddr_t addr,
		    size_t len, uint_t prot);
static int	segvn_kluster(struct seg *seg, caddr_t addr, ssize_t delta);
static size_t	segvn_swapout(struct seg *seg);
static int	segvn_sync(struct seg *seg, caddr_t addr, size_t len,
		    int attr, uint_t flags);
static size_t	segvn_incore(struct seg *seg, caddr_t addr, size_t len,
		    char *vec);
static int	segvn_lockop(struct seg *seg, caddr_t addr, size_t len,
		    int attr, int op, ulong_t *lockmap, size_t pos);
static int	segvn_getprot(struct seg *seg, caddr_t addr, size_t len,
		    uint_t *protv);
static u_offset_t	segvn_getoffset(struct seg *seg, caddr_t addr);
static int	segvn_gettype(struct seg *seg, caddr_t addr);
static int	segvn_getvp(struct seg *seg, caddr_t addr,
		    struct vnode **vpp);
static int	segvn_advise(struct seg *seg, caddr_t addr, size_t len,
		    uint_t behav);
static void	segvn_dump(struct seg *seg);
static int	segvn_pagelock(struct seg *seg, caddr_t addr, size_t len,
		    struct page ***ppp, enum lock_type type, enum seg_rw rw);
static int	segvn_setpagesize(struct seg *seg, caddr_t addr, size_t len,
		    uint_t szc);
static int	segvn_getmemid(struct seg *seg, caddr_t addr,
		    memid_t *memidp);
static lgrp_mem_policy_info_t	*segvn_getpolicy(struct seg *, caddr_t);
static int	segvn_capable(struct seg *seg, segcapability_t capable);

struct	seg_ops segvn_ops = {
	segvn_dup,
	segvn_unmap,
	segvn_free,
	segvn_fault,
	segvn_faulta,
	segvn_setprot,
	segvn_checkprot,
	segvn_kluster,
	segvn_swapout,
	segvn_sync,
	segvn_incore,
	segvn_lockop,
	segvn_getprot,
	segvn_getoffset,
	segvn_gettype,
	segvn_getvp,
	segvn_advise,
	segvn_dump,
	segvn_pagelock,
	segvn_setpagesize,
	segvn_getmemid,
	segvn_getpolicy,
	segvn_capable,
};

/*
 * Common zfod structures, provided as a shorthand for others to use.
 */
static segvn_crargs_t zfod_segvn_crargs =
	SEGVN_ZFOD_ARGS(PROT_ZFOD, PROT_ALL);
static segvn_crargs_t kzfod_segvn_crargs =
	SEGVN_ZFOD_ARGS(PROT_ZFOD & ~PROT_USER,
	PROT_ALL & ~PROT_USER);
static segvn_crargs_t stack_noexec_crargs =
	SEGVN_ZFOD_ARGS(PROT_ZFOD & ~PROT_EXEC, PROT_ALL);

caddr_t	zfod_argsp = (caddr_t)&zfod_segvn_crargs;	/* user zfod argsp */
caddr_t	kzfod_argsp = (caddr_t)&kzfod_segvn_crargs;	/* kernel zfod argsp */
caddr_t	stack_exec_argsp = (caddr_t)&zfod_segvn_crargs;	/* executable stack */
caddr_t	stack_noexec_argsp = (caddr_t)&stack_noexec_crargs; /* noexec stack */

#define	vpgtob(n)	((n) * sizeof (struct vpage))	/* For brevity */

size_t	segvn_comb_thrshld = UINT_MAX;	/* patchable -- see 1196681 */

static int	segvn_concat(struct seg *, struct seg *, int);
static int	segvn_extend_prev(struct seg *, struct seg *,
		    struct segvn_crargs *, size_t);
static int	segvn_extend_next(struct seg *, struct seg *,
		    struct segvn_crargs *, size_t);
static void	segvn_softunlock(struct seg *, caddr_t, size_t, enum seg_rw);
static void	segvn_pagelist_rele(page_t **);
static void	segvn_setvnode_mpss(vnode_t *);
static void	segvn_relocate_pages(page_t **, page_t *);
static int	segvn_full_szcpages(page_t **, uint_t, int *, uint_t *);
static int	segvn_fill_vp_pages(struct segvn_data *, vnode_t *, u_offset_t,
    uint_t, page_t **, page_t **, uint_t *, int *);
static faultcode_t segvn_fault_vnodepages(struct hat *, struct seg *, caddr_t,
    caddr_t, enum fault_type, enum seg_rw, caddr_t, caddr_t, int);
static faultcode_t segvn_fault_anonpages(struct hat *, struct seg *, caddr_t,
    caddr_t, enum fault_type, enum seg_rw, caddr_t, caddr_t, int);
static faultcode_t segvn_faultpage(struct hat *, struct seg *, caddr_t,
    u_offset_t, struct vpage *, page_t **, uint_t,
    enum fault_type, enum seg_rw, int);
static void	segvn_vpage(struct seg *);

static void segvn_purge(struct seg *seg);
static int segvn_reclaim(struct seg *, caddr_t, size_t, struct page **,
    enum seg_rw);

static int sameprot(struct seg *, caddr_t, size_t);

static int segvn_demote_range(struct seg *, caddr_t, size_t, int);
static int segvn_clrszc(struct seg *);
static struct seg *segvn_split_seg(struct seg *, caddr_t);
static int segvn_claim_pages(struct seg *, struct vpage *, u_offset_t,
    ulong_t, uint_t);

static struct kmem_cache *segvn_cache;

#ifdef VM_STATS
static struct segvnvmstats_str {
	ulong_t	fill_vp_pages[31];
	ulong_t fltvnpages[49];
	ulong_t	fullszcpages[10];
	ulong_t	relocatepages[3];
	ulong_t	fltanpages[17];
	ulong_t pagelock[3];
	ulong_t	demoterange[3];
} segvnvmstats;
#endif /* VM_STATS */

#define	SDR_RANGE	1		/* demote entire range */
#define	SDR_END		2		/* demote non aligned ends only */

#define	CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr, lpgeaddr) {            \
		if ((len) != 0) { 		      	      		      \
			lpgaddr = (caddr_t)P2ALIGN((uintptr_t)(addr), pgsz);  \
			ASSERT(lpgaddr >= (seg)->s_base);	      	      \
			lpgeaddr = (caddr_t)P2ROUNDUP((uintptr_t)((addr) +    \
			    (len)), pgsz);				      \
			ASSERT(lpgeaddr > lpgaddr);		      	      \
			ASSERT(lpgeaddr <= (seg)->s_base + (seg)->s_size);    \
		} else {					      	      \
			lpgeaddr = lpgaddr = (addr);	      		      \
		}							      \
	}

/*ARGSUSED*/
static int
segvn_cache_constructor(void *buf, void *cdrarg, int kmflags)
{
	struct segvn_data *svd = buf;

	rw_init(&svd->lock, NULL, RW_DEFAULT, NULL);
	mutex_init(&svd->segp_slock, NULL, MUTEX_DEFAULT, NULL);
	return (0);
}

/*ARGSUSED1*/
static void
segvn_cache_destructor(void *buf, void *cdrarg)
{
	struct segvn_data *svd = buf;

	rw_destroy(&svd->lock);
	mutex_destroy(&svd->segp_slock);
}

/*
 * Patching this variable to non-zero allows the system to run with
 * stacks marked as "not executable".  It's a bit of a kludge, but is
 * provided as a tweakable for platforms that export those ABIs
 * (e.g. sparc V8) that have executable stacks enabled by default.
 * There are also some restrictions for platforms that don't actually
 * implement 'noexec' protections.
 *
 * Once enabled, the system is (therefore) unable to provide a fully
 * ABI-compliant execution environment, though practically speaking,
 * most everything works.  The exceptions are generally some interpreters
 * and debuggers that create executable code on the stack and jump
 * into it (without explicitly mprotecting the address range to include
 * PROT_EXEC).
 *
 * One important class of applications that are disabled are those
 * that have been transformed into malicious agents using one of the
 * numerous "buffer overflow" attacks.  See 4007890.
 */
int noexec_user_stack = 0;
int noexec_user_stack_log = 1;

int segvn_lpg_disable = 0;
uint_t segvn_maxpgszc = 0;

ulong_t segvn_vmpss_clrszc_cnt;
ulong_t segvn_vmpss_clrszc_err;
ulong_t segvn_fltvnpages_clrszc_cnt;
ulong_t segvn_fltvnpages_clrszc_err;
ulong_t segvn_setpgsz_align_err;
ulong_t segvn_setpgsz_getattr_err;
ulong_t segvn_setpgsz_eof_err;
ulong_t segvn_faultvnmpss_align_err1;
ulong_t segvn_faultvnmpss_align_err2;
ulong_t segvn_faultvnmpss_align_err3;
ulong_t segvn_faultvnmpss_align_err4;
ulong_t segvn_faultvnmpss_align_err5;
ulong_t	segvn_vmpss_pageio_deadlk_err;

/*
 * Initialize segvn data structures
 */
void
segvn_init(void)
{
	uint_t maxszc;
	uint_t szc;
	size_t pgsz;

	segvn_cache = kmem_cache_create("segvn_cache",
		sizeof (struct segvn_data), 0,
		segvn_cache_constructor, segvn_cache_destructor, NULL,
		NULL, NULL, 0);

	if (segvn_lpg_disable != 0)
		return;
	szc = maxszc = page_num_pagesizes() - 1;
	if (szc == 0) {
		segvn_lpg_disable = 1;
		return;
	}
	if (page_get_pagesize(0) != PAGESIZE) {
		panic("segvn_init: bad szc 0");
		/*NOTREACHED*/
	}
	while (szc != 0) {
		pgsz = page_get_pagesize(szc);
		if (pgsz <= PAGESIZE || !IS_P2ALIGNED(pgsz, pgsz)) {
			panic("segvn_init: bad szc %d", szc);
			/*NOTREACHED*/
		}
		szc--;
	}
	if (segvn_maxpgszc == 0 || segvn_maxpgszc > maxszc)
		segvn_maxpgszc = maxszc;
}

#define	SEGVN_PAGEIO	((void *)0x1)
#define	SEGVN_NOPAGEIO	((void *)0x2)

static void
segvn_setvnode_mpss(vnode_t *vp)
{
	int err;

	ASSERT(vp->v_mpssdata == NULL ||
	    vp->v_mpssdata == SEGVN_PAGEIO ||
	    vp->v_mpssdata == SEGVN_NOPAGEIO);

	if (vp->v_mpssdata == NULL) {
		if (vn_vmpss_usepageio(vp)) {
			err = VOP_PAGEIO(vp, (page_t *)NULL,
			    (u_offset_t)0, 0, 0, CRED());
		} else {
			err = ENOSYS;
		}
		/*
		 * set v_mpssdata just once per vnode life
		 * so that it never changes.
		 */
		mutex_enter(&vp->v_lock);
		if (vp->v_mpssdata == NULL) {
			if (err == EINVAL) {
				vp->v_mpssdata = SEGVN_PAGEIO;
			} else {
				vp->v_mpssdata = SEGVN_NOPAGEIO;
			}
		}
		mutex_exit(&vp->v_lock);
	}
}

int
segvn_create(struct seg *seg, void *argsp)
{
	struct segvn_crargs *a = (struct segvn_crargs *)argsp;
	struct segvn_data *svd;
	size_t swresv = 0;
	struct cred *cred;
	struct anon_map *amp;
	int error = 0;
	size_t pgsz;
	lgrp_mem_policy_t mpolicy = LGRP_MEM_POLICY_DEFAULT;


	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));

	if (a->type != MAP_PRIVATE && a->type != MAP_SHARED) {
		panic("segvn_create type");
		/*NOTREACHED*/
	}

	/*
	 * Check arguments.  If a shared anon structure is given then
	 * it is illegal to also specify a vp.
	 */
	if (a->amp != NULL && a->vp != NULL) {
		panic("segvn_create anon_map");
		/*NOTREACHED*/
	}

	/* MAP_NORESERVE on a MAP_SHARED segment is meaningless. */
	if (a->type == MAP_SHARED)
		a->flags &= ~MAP_NORESERVE;

	if (a->szc != 0) {
		if (segvn_lpg_disable != 0 || a->amp != NULL ||
		    (a->type == MAP_SHARED && a->vp == NULL) ||
		    (a->flags & MAP_NORESERVE) || seg->s_as == &kas) {
			a->szc = 0;
		} else {
			if (a->szc > segvn_maxpgszc)
				a->szc = segvn_maxpgszc;
			pgsz = page_get_pagesize(a->szc);
			if (!IS_P2ALIGNED(seg->s_base, pgsz) ||
			    !IS_P2ALIGNED(seg->s_size, pgsz)) {
				a->szc = 0;
			} else if (a->vp != NULL) {
				extern struct vnode kvp;
				if (IS_SWAPFSVP(a->vp) || a->vp == &kvp) {
					/*
					 * paranoid check.
					 * hat_page_demote() is not supported
					 * on swapfs pages.
					 */
					a->szc = 0;
				} else if (map_addr_vacalign_check(seg->s_base,
				    a->offset & PAGEMASK)) {
					a->szc = 0;
				}
			}
		}
	}

	/*
	 * If segment may need private pages, reserve them now.
	 */
	if (!(a->flags & MAP_NORESERVE) && ((a->vp == NULL && a->amp == NULL) ||
	    (a->type == MAP_PRIVATE && (a->prot & PROT_WRITE)))) {
		if (anon_resv(seg->s_size) == 0)
			return (EAGAIN);
		swresv = seg->s_size;
		TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
			seg, swresv, 1);
	}

	/*
	 * Reserve any mapping structures that may be required.
	 */
	hat_map(seg->s_as->a_hat, seg->s_base, seg->s_size, HAT_MAP);

	if (a->cred) {
		cred = a->cred;
		crhold(cred);
	} else {
		crhold(cred = CRED());
	}

	/* Inform the vnode of the new mapping */
	if (a->vp) {
		error = VOP_ADDMAP(a->vp, a->offset & PAGEMASK,
		    seg->s_as, seg->s_base, seg->s_size, a->prot,
		    a->maxprot, a->type, cred);
		if (error) {
			if (swresv != 0) {
				anon_unresv(swresv);
				TRACE_3(TR_FAC_VM, TR_ANON_PROC,
					"anon proc:%p %lu %u",
					seg, swresv, 0);
			}
			crfree(cred);
			hat_unload(seg->s_as->a_hat, seg->s_base,
				seg->s_size, HAT_UNLOAD_UNMAP);
			return (error);
		}
	}

	/*
	 * If more than one segment in the address space, and
	 * they're adjacent virtually, try to concatenate them.
	 * Don't concatenate if an explicit anon_map structure
	 * was supplied (e.g., SystemV shared memory).
	 */
	if (a->amp == NULL) {
		struct seg *pseg, *nseg;
		struct segvn_data *psvd, *nsvd;
		lgrp_mem_policy_t ppolicy, npolicy;
		uint_t	lgrp_mem_policy_flags = 0;
		extern lgrp_mem_policy_t lgrp_mem_default_policy;

		/*
		 * Memory policy flags (lgrp_mem_policy_flags) is valid when
		 * extending stack/heap segments.
		 */
		if ((a->vp == NULL) && (a->type == MAP_PRIVATE) &&
			!(a->flags & MAP_NORESERVE) && (seg->s_as != &kas)) {
			lgrp_mem_policy_flags = a->lgrp_mem_policy_flags;
		} else {
			/*
			 * Get policy when not extending it from another segment
			 */
			mpolicy = lgrp_mem_policy_default(seg->s_size, a->type);
		}

		/*
		 * First, try to concatenate the previous and new segments
		 */
		pseg = AS_SEGPREV(seg->s_as, seg);
		if (pseg != NULL &&
		    pseg->s_base + pseg->s_size == seg->s_base &&
		    pseg->s_ops == &segvn_ops) {
			/*
			 * Get memory allocation policy from previous segment.
			 * When extension is specified (e.g. for heap) apply
			 * this policy to the new segment regardless of the
			 * outcome of segment concatenation.  Extension occurs
			 * for non-default policy otherwise default policy is
			 * used and is based on extended segment size.
			 */
			psvd = (struct segvn_data *)pseg->s_data;
			ppolicy = psvd->policy_info.mem_policy;
			if (lgrp_mem_policy_flags ==
			    LGRP_MP_FLAG_EXTEND_UP) {
				if (ppolicy != lgrp_mem_default_policy) {
					mpolicy = ppolicy;
				} else {
					mpolicy = lgrp_mem_policy_default(
					    pseg->s_size + seg->s_size,
					    a->type);
				}
			}

			if (mpolicy == ppolicy &&
			    (pseg->s_size + seg->s_size <=
			    segvn_comb_thrshld || psvd->amp == NULL) &&
			    segvn_extend_prev(pseg, seg, a, swresv) == 0) {
				/*
				 * success! now try to concatenate
				 * with following seg
				 */
				crfree(cred);
				nseg = AS_SEGNEXT(pseg->s_as, pseg);
				if (nseg != NULL &&
				    nseg != pseg &&
				    nseg->s_ops == &segvn_ops &&
				    pseg->s_base + pseg->s_size ==
				    nseg->s_base)
					(void) segvn_concat(pseg, nseg, 0);
				ASSERT(pseg->s_szc == 0 ||
				    (a->szc == pseg->s_szc &&
				    IS_P2ALIGNED(pseg->s_base, pgsz) &&
				    IS_P2ALIGNED(pseg->s_size, pgsz)));
				return (0);
			}
		}

		/*
		 * Failed, so try to concatenate with following seg
		 */
		nseg = AS_SEGNEXT(seg->s_as, seg);
		if (nseg != NULL &&
		    seg->s_base + seg->s_size == nseg->s_base &&
		    nseg->s_ops == &segvn_ops) {
			/*
			 * Get memory allocation policy from next segment.
			 * When extension is specified (e.g. for stack) apply
			 * this policy to the new segment regardless of the
			 * outcome of segment concatenation.  Extension occurs
			 * for non-default policy otherwise default policy is
			 * used and is based on extended segment size.
			 */
			nsvd = (struct segvn_data *)nseg->s_data;
			npolicy = nsvd->policy_info.mem_policy;
			if (lgrp_mem_policy_flags ==
			    LGRP_MP_FLAG_EXTEND_DOWN) {
				if (npolicy != lgrp_mem_default_policy) {
					mpolicy = npolicy;
				} else {
					mpolicy = lgrp_mem_policy_default(
					    nseg->s_size + seg->s_size,
					    a->type);
				}
			}

			if (mpolicy == npolicy &&
			    segvn_extend_next(seg, nseg, a, swresv) == 0) {
				crfree(cred);
				ASSERT(nseg->s_szc == 0 ||
				    (a->szc == nseg->s_szc &&
				    IS_P2ALIGNED(nseg->s_base, pgsz) &&
				    IS_P2ALIGNED(nseg->s_size, pgsz)));
				return (0);
			}
		}
	}

	if (a->vp != NULL) {
		VN_HOLD(a->vp);
		if (a->type == MAP_SHARED)
			lgrp_shm_policy_init(NULL, a->vp);
	}
	svd = kmem_cache_alloc(segvn_cache, KM_SLEEP);

	seg->s_ops = &segvn_ops;
	seg->s_data = (void *)svd;
	seg->s_szc = a->szc;

	svd->vp = a->vp;
	/*
	 * Anonymous mappings have no backing file so the offset is meaningless.
	 */
	svd->offset = a->vp ? (a->offset & PAGEMASK) : 0;
	svd->prot = a->prot;
	svd->maxprot = a->maxprot;
	svd->pageprot = 0;
	svd->type = a->type;
	svd->vpage = NULL;
	svd->cred = cred;
	svd->advice = MADV_NORMAL;
	svd->pageadvice = 0;
	svd->flags = (ushort_t)a->flags;
	svd->softlockcnt = 0;
	if (a->szc != 0 && a->vp != NULL) {
		segvn_setvnode_mpss(a->vp);
	}

	amp = a->amp;
	if ((svd->amp = amp) == NULL) {
		svd->anon_index = 0;
		if (svd->type == MAP_SHARED) {
			svd->swresv = 0;
			/*
			 * Shared mappings to a vp need no other setup.
			 * If we have a shared mapping to an anon_map object
			 * which hasn't been allocated yet,  allocate the
			 * struct now so that it will be properly shared
			 * by remembering the swap reservation there.
			 */
			if (a->vp == NULL) {
				svd->amp = anonmap_alloc(seg->s_size, swresv);
				svd->amp->a_szc = seg->s_szc;
			}
		} else {
			/*
			 * Private mapping (with or without a vp).
			 * Allocate anon_map when needed.
			 */
			svd->swresv = swresv;
		}
	} else {
		pgcnt_t anon_num;

		/*
		 * Mapping to an existing anon_map structure without a vp.
		 * For now we will insure that the segment size isn't larger
		 * than the size - offset gives us.  Later on we may wish to
		 * have the anon array dynamically allocated itself so that
		 * we don't always have to allocate all the anon pointer slots.
		 * This of course involves adding extra code to check that we
		 * aren't trying to use an anon pointer slot beyond the end
		 * of the currently allocated anon array.
		 */
		if ((amp->size - a->offset) < seg->s_size) {
			panic("segvn_create anon_map size");
			/*NOTREACHED*/
		}

		anon_num = btopr(a->offset);

		if (a->type == MAP_SHARED) {
			/*
			 * SHARED mapping to a given anon_map.
			 */
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			amp->refcnt++;
			ANON_LOCK_EXIT(&amp->a_rwlock);
			svd->anon_index = anon_num;
			svd->swresv = 0;
		} else {
			/*
			 * PRIVATE mapping to a given anon_map.
			 * Make sure that all the needed anon
			 * structures are created (so that we will
			 * share the underlying pages if nothing
			 * is written by this mapping) and then
			 * duplicate the anon array as is done
			 * when a privately mapped segment is dup'ed.
			 */
			struct anon *ap;
			caddr_t addr;
			caddr_t eaddr;
			ulong_t	anon_idx;
			int hat_flag = HAT_LOAD;

			if (svd->flags & MAP_TEXT) {
				hat_flag |= HAT_LOAD_TEXT;
			}

			svd->amp = anonmap_alloc(seg->s_size, 0);
			svd->amp->a_szc = seg->s_szc;
			svd->anon_index = 0;
			svd->swresv = swresv;

			/*
			 * Prevent 2 threads from allocating anon
			 * slots simultaneously.
			 */
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			eaddr = seg->s_base + seg->s_size;

			for (anon_idx = anon_num, addr = seg->s_base;
			    addr < eaddr; addr += PAGESIZE, anon_idx++) {
				page_t *pp;

				if ((ap = anon_get_ptr(amp->ahp,
				    anon_idx)) != NULL)
					continue;

				/*
				 * Allocate the anon struct now.
				 * Might as well load up translation
				 * to the page while we're at it...
				 */
				pp = anon_zero(seg, addr, &ap, cred);
				if (ap == NULL || pp == NULL) {
					panic("segvn_create anon_zero");
					/*NOTREACHED*/
				}

				/*
				 * Re-acquire the anon_map lock and
				 * initialize the anon array entry.
				 */
				ASSERT(anon_get_ptr(amp->ahp,
				    anon_idx) == NULL);
				(void) anon_set_ptr(amp->ahp, anon_idx, ap,
				    ANON_SLEEP);

				ASSERT(seg->s_szc == 0);
				ASSERT(!IS_VMODSORT(pp->p_vnode));

				hat_memload(seg->s_as->a_hat, addr, pp,
					svd->prot & ~PROT_WRITE, hat_flag);

				page_unlock(pp);
			}
			ASSERT(seg->s_szc == 0);
			anon_dup(amp->ahp, anon_num, svd->amp->ahp,
			    0, seg->s_size);
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}
	}

	/*
	 * Set default memory allocation policy for segment
	 *
	 * Always set policy for private memory at least for initialization
	 * even if this is a shared memory segment
	 */
	(void) lgrp_privm_policy_set(mpolicy, &svd->policy_info, seg->s_size);

	if (svd->type == MAP_SHARED)
		(void) lgrp_shm_policy_set(mpolicy, svd->amp, svd->anon_index,
		    svd->vp, svd->offset, seg->s_size);

	return (0);
}

/*
 * Concatenate two existing segments, if possible.
 * Return 0 on success, -1 if two segments are not compatible
 * or -2 on memory allocation failure.
 * If private == 1 then try and concat segments with private pages.
 */
static int
segvn_concat(struct seg *seg1, struct seg *seg2, int private)
{
	struct segvn_data *svd1 = seg1->s_data;
	struct segvn_data *svd2 = seg2->s_data;
	struct anon_map *amp1 = svd1->amp;
	struct anon_map *amp2 = svd2->amp;
	struct vpage *vpage1 = svd1->vpage;
	struct vpage *vpage2 = svd2->vpage, *nvpage = NULL;
	size_t size, nvpsize;
	pgcnt_t npages1, npages2;

	ASSERT(seg1->s_as && seg2->s_as && seg1->s_as == seg2->s_as);
	ASSERT(AS_WRITE_HELD(seg1->s_as, &seg1->s_as->a_lock));
	ASSERT(seg1->s_ops == seg2->s_ops);

	/* both segments exist, try to merge them */
#define	incompat(x)	(svd1->x != svd2->x)
	if (incompat(vp) || incompat(maxprot) ||
	    (!svd1->pageadvice && !svd2->pageadvice && incompat(advice)) ||
	    (!svd1->pageprot && !svd2->pageprot && incompat(prot)) ||
	    incompat(type) || incompat(cred) || incompat(flags) ||
	    seg1->s_szc != seg2->s_szc || incompat(policy_info.mem_policy) ||
	    (svd2->softlockcnt > 0))
		return (-1);
#undef incompat

	/*
	 * vp == NULL implies zfod, offset doesn't matter
	 */
	if (svd1->vp != NULL &&
	    svd1->offset + seg1->s_size != svd2->offset) {
		return (-1);
	}

	/*
	 * Fail early if we're not supposed to concatenate
	 * private pages.
	 */
	if ((private == 0 || svd1->type != MAP_PRIVATE) &&
	    (amp1 != NULL || amp2 != NULL)) {
		return (-1);
	}

	/*
	 * If either seg has vpages, create a new merged vpage array.
	 */
	if (vpage1 != NULL || vpage2 != NULL) {
		struct vpage *vp;

		npages1 = seg_pages(seg1);
		npages2 = seg_pages(seg2);
		nvpsize = vpgtob(npages1 + npages2);

		if ((nvpage = kmem_zalloc(nvpsize, KM_NOSLEEP)) == NULL) {
			return (-2);
		}
		if (vpage1 != NULL) {
			bcopy(vpage1, nvpage, vpgtob(npages1));
		}
		if (vpage2 != NULL) {
			bcopy(vpage2, nvpage + npages1, vpgtob(npages2));
		}
		for (vp = nvpage; vp < nvpage + npages1; vp++) {
			if (svd2->pageprot && !svd1->pageprot) {
				VPP_SETPROT(vp, svd1->prot);
			}
			if (svd2->pageadvice && !svd1->pageadvice) {
				VPP_SETADVICE(vp, svd1->advice);
			}
		}
		for (vp = nvpage + npages1;
		    vp < nvpage + npages1 + npages2; vp++) {
			if (svd1->pageprot && !svd2->pageprot) {
				VPP_SETPROT(vp, svd2->prot);
			}
			if (svd1->pageadvice && !svd2->pageadvice) {
				VPP_SETADVICE(vp, svd2->advice);
			}
		}
	}

	/*
	 * If either segment has private pages, create a new merged anon
	 * array.
	 */
	if (amp1 != NULL || amp2 != NULL) {
		struct anon_hdr *nahp;
		struct anon_map *namp = NULL;
		size_t asize = seg1->s_size + seg2->s_size;

		if ((nahp = anon_create(btop(asize), ANON_NOSLEEP)) == NULL) {
			if (nvpage != NULL) {
				kmem_free(nvpage, nvpsize);
			}
			return (-2);
		}
		if (amp1 != NULL) {
			/*
			 * XXX anon rwlock is not really needed because
			 * this is a private segment and we are writers.
			 */
			ANON_LOCK_ENTER(&amp1->a_rwlock, RW_WRITER);
			ASSERT(amp1->refcnt == 1);
			if (anon_copy_ptr(amp1->ahp, svd1->anon_index,
			    nahp, 0, btop(seg1->s_size), ANON_NOSLEEP)) {
				anon_release(nahp, btop(asize));
				ANON_LOCK_EXIT(&amp1->a_rwlock);
				if (nvpage != NULL) {
					kmem_free(nvpage, nvpsize);
				}
				return (-2);
			}
		}
		if (amp2 != NULL) {
			ANON_LOCK_ENTER(&amp2->a_rwlock, RW_WRITER);
			ASSERT(amp2->refcnt == 1);
			if (anon_copy_ptr(amp2->ahp, svd2->anon_index,
			    nahp, btop(seg1->s_size), btop(seg2->s_size),
			    ANON_NOSLEEP)) {
				anon_release(nahp, btop(asize));
				ANON_LOCK_EXIT(&amp2->a_rwlock);
				if (amp1 != NULL) {
					ANON_LOCK_EXIT(&amp1->a_rwlock);
				}
				if (nvpage != NULL) {
					kmem_free(nvpage, nvpsize);
				}
				return (-2);
			}
		}
		if (amp1 != NULL) {
			namp = amp1;
			anon_release(amp1->ahp, btop(amp1->size));
		}
		if (amp2 != NULL) {
			if (namp == NULL) {
				ASSERT(amp1 == NULL);
				namp = amp2;
				anon_release(amp2->ahp, btop(amp2->size));
			} else {
				amp2->refcnt--;
				ANON_LOCK_EXIT(&amp2->a_rwlock);
				anonmap_free(amp2);
			}
			svd2->amp = NULL; /* needed for seg_free */
		}
		namp->ahp = nahp;
		namp->size = asize;
		svd1->amp = namp;
		svd1->anon_index = 0;
		ANON_LOCK_EXIT(&namp->a_rwlock);
	}
	/*
	 * Now free the old vpage structures.
	 */
	if (nvpage != NULL) {
		if (vpage1 != NULL) {
			kmem_free(vpage1, vpgtob(npages1));
		}
		if (vpage2 != NULL) {
			svd2->vpage = NULL;
			kmem_free(vpage2, vpgtob(npages2));
		}
		if (svd2->pageprot) {
			svd1->pageprot = 1;
		}
		if (svd2->pageadvice) {
			svd1->pageadvice = 1;
		}
		svd1->vpage = nvpage;
	}

	/* all looks ok, merge segments */
	svd1->swresv += svd2->swresv;
	svd2->swresv = 0;  /* so seg_free doesn't release swap space */
	size = seg2->s_size;
	seg_free(seg2);
	seg1->s_size += size;
	return (0);
}

/*
 * Extend the previous segment (seg1) to include the
 * new segment (seg2 + a), if possible.
 * Return 0 on success.
 */
static int
segvn_extend_prev(seg1, seg2, a, swresv)
	struct seg *seg1, *seg2;
	struct segvn_crargs *a;
	size_t swresv;
{
	struct segvn_data *svd1 = (struct segvn_data *)seg1->s_data;
	size_t size;
	struct anon_map *amp1;
	struct vpage *new_vpage;

	/*
	 * We don't need any segment level locks for "segvn" data
	 * since the address space is "write" locked.
	 */
	ASSERT(seg1->s_as && AS_WRITE_HELD(seg1->s_as, &seg1->s_as->a_lock));

	/* second segment is new, try to extend first */
	/* XXX - should also check cred */
	if (svd1->vp != a->vp || svd1->maxprot != a->maxprot ||
	    (!svd1->pageprot && (svd1->prot != a->prot)) ||
	    svd1->type != a->type || svd1->flags != a->flags ||
	    seg1->s_szc != a->szc)
		return (-1);

	/* vp == NULL implies zfod, offset doesn't matter */
	if (svd1->vp != NULL &&
	    svd1->offset + seg1->s_size != (a->offset & PAGEMASK))
		return (-1);

	amp1 = svd1->amp;
	if (amp1) {
		pgcnt_t newpgs;

		/*
		 * Segment has private pages, can data structures
		 * be expanded?
		 *
		 * Acquire the anon_map lock to prevent it from changing,
		 * if it is shared.  This ensures that the anon_map
		 * will not change while a thread which has a read/write
		 * lock on an address space references it.
		 * XXX - Don't need the anon_map lock at all if "refcnt"
		 * is 1.
		 *
		 * Can't grow a MAP_SHARED segment with an anonmap because
		 * there may be existing anon slots where we want to extend
		 * the segment and we wouldn't know what to do with them
		 * (e.g., for tmpfs right thing is to just leave them there,
		 * for /dev/zero they should be cleared out).
		 */
		if (svd1->type == MAP_SHARED)
			return (-1);

		ANON_LOCK_ENTER(&amp1->a_rwlock, RW_WRITER);
		if (amp1->refcnt > 1) {
			ANON_LOCK_EXIT(&amp1->a_rwlock);
			return (-1);
		}
		newpgs = anon_grow(amp1->ahp, &svd1->anon_index,
		    btop(seg1->s_size), btop(seg2->s_size), ANON_NOSLEEP);

		if (newpgs == 0) {
			ANON_LOCK_EXIT(&amp1->a_rwlock);
			return (-1);
		}
		amp1->size = ptob(newpgs);
		ANON_LOCK_EXIT(&amp1->a_rwlock);
	}
	if (svd1->vpage != NULL) {
		new_vpage =
		    kmem_zalloc(vpgtob(seg_pages(seg1) + seg_pages(seg2)),
			KM_NOSLEEP);
		if (new_vpage == NULL)
			return (-1);
		bcopy(svd1->vpage, new_vpage, vpgtob(seg_pages(seg1)));
		kmem_free(svd1->vpage, vpgtob(seg_pages(seg1)));
		svd1->vpage = new_vpage;
		if (svd1->pageprot) {
			struct vpage *vp, *evp;

			vp = new_vpage + seg_pages(seg1);
			evp = vp + seg_pages(seg2);
			for (; vp < evp; vp++)
				VPP_SETPROT(vp, a->prot);
		}
	}
	size = seg2->s_size;
	seg_free(seg2);
	seg1->s_size += size;
	svd1->swresv += swresv;
	return (0);
}

/*
 * Extend the next segment (seg2) to include the
 * new segment (seg1 + a), if possible.
 * Return 0 on success.
 */
static int
segvn_extend_next(
	struct seg *seg1,
	struct seg *seg2,
	struct segvn_crargs *a,
	size_t swresv)
{
	struct segvn_data *svd2 = (struct segvn_data *)seg2->s_data;
	size_t size;
	struct anon_map *amp2;
	struct vpage *new_vpage;

	/*
	 * We don't need any segment level locks for "segvn" data
	 * since the address space is "write" locked.
	 */
	ASSERT(seg2->s_as && AS_WRITE_HELD(seg2->s_as, &seg2->s_as->a_lock));

	/* first segment is new, try to extend second */
	/* XXX - should also check cred */
	if (svd2->vp != a->vp || svd2->maxprot != a->maxprot ||
	    (!svd2->pageprot && (svd2->prot != a->prot)) ||
	    svd2->type != a->type || svd2->flags != a->flags ||
	    seg2->s_szc != a->szc)
		return (-1);
	/* vp == NULL implies zfod, offset doesn't matter */
	if (svd2->vp != NULL &&
	    (a->offset & PAGEMASK) + seg1->s_size != svd2->offset)
		return (-1);

	amp2 = svd2->amp;
	if (amp2) {
		pgcnt_t newpgs;

		/*
		 * Segment has private pages, can data structures
		 * be expanded?
		 *
		 * Acquire the anon_map lock to prevent it from changing,
		 * if it is shared.  This ensures that the anon_map
		 * will not change while a thread which has a read/write
		 * lock on an address space references it.
		 *
		 * XXX - Don't need the anon_map lock at all if "refcnt"
		 * is 1.
		 */
		if (svd2->type == MAP_SHARED)
			return (-1);

		ANON_LOCK_ENTER(&amp2->a_rwlock, RW_WRITER);
		if (amp2->refcnt > 1) {
			ANON_LOCK_EXIT(&amp2->a_rwlock);
			return (-1);
		}
		newpgs = anon_grow(amp2->ahp, &svd2->anon_index,
		    btop(seg2->s_size), btop(seg1->s_size),
		    ANON_NOSLEEP | ANON_GROWDOWN);

		if (newpgs == 0) {
			ANON_LOCK_EXIT(&amp2->a_rwlock);
			return (-1);
		}
		amp2->size = ptob(newpgs);
		ANON_LOCK_EXIT(&amp2->a_rwlock);
	}
	if (svd2->vpage != NULL) {
		new_vpage =
		    kmem_zalloc(vpgtob(seg_pages(seg1) + seg_pages(seg2)),
			KM_NOSLEEP);
		if (new_vpage == NULL) {
			/* Not merging segments so adjust anon_index back */
			if (amp2)
				svd2->anon_index += seg_pages(seg1);
			return (-1);
		}
		bcopy(svd2->vpage, new_vpage + seg_pages(seg1),
		    vpgtob(seg_pages(seg2)));
		kmem_free(svd2->vpage, vpgtob(seg_pages(seg2)));
		svd2->vpage = new_vpage;
		if (svd2->pageprot) {
			struct vpage *vp, *evp;

			vp = new_vpage;
			evp = vp + seg_pages(seg1);
			for (; vp < evp; vp++)
				VPP_SETPROT(vp, a->prot);
		}
	}
	size = seg1->s_size;
	seg_free(seg1);
	seg2->s_size += size;
	seg2->s_base -= size;
	svd2->offset -= size;
	svd2->swresv += swresv;
	return (0);
}

static int
segvn_dup(struct seg *seg, struct seg *newseg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct segvn_data *newsvd;
	pgcnt_t npages = seg_pages(seg);
	int error = 0;
	uint_t prot;
	size_t len;

	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));

	/*
	 * If segment has anon reserved, reserve more for the new seg.
	 * For a MAP_NORESERVE segment swresv will be a count of all the
	 * allocated anon slots; thus we reserve for the child as many slots
	 * as the parent has allocated. This semantic prevents the child or
	 * parent from dieing during a copy-on-write fault caused by trying
	 * to write a shared pre-existing anon page.
	 */
	if ((len = svd->swresv) != 0) {
		if (anon_resv(svd->swresv) == 0)
			return (ENOMEM);

		TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
			seg, len, 0);
	}

	newsvd = kmem_cache_alloc(segvn_cache, KM_SLEEP);

	newseg->s_ops = &segvn_ops;
	newseg->s_data = (void *)newsvd;
	newseg->s_szc = seg->s_szc;

	if ((newsvd->vp = svd->vp) != NULL) {
		VN_HOLD(svd->vp);
		if (svd->type == MAP_SHARED)
			lgrp_shm_policy_init(NULL, svd->vp);
	}
	newsvd->offset = svd->offset;
	newsvd->prot = svd->prot;
	newsvd->maxprot = svd->maxprot;
	newsvd->pageprot = svd->pageprot;
	newsvd->type = svd->type;
	newsvd->cred = svd->cred;
	crhold(newsvd->cred);
	newsvd->advice = svd->advice;
	newsvd->pageadvice = svd->pageadvice;
	newsvd->swresv = svd->swresv;
	newsvd->flags = svd->flags;
	newsvd->softlockcnt = 0;
	newsvd->policy_info = svd->policy_info;
	if ((newsvd->amp = svd->amp) == NULL) {
		/*
		 * Not attaching to a shared anon object.
		 */
		newsvd->anon_index = 0;
	} else {
		struct anon_map *amp;

		amp = svd->amp;
		if (svd->type == MAP_SHARED) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			amp->refcnt++;
			ANON_LOCK_EXIT(&amp->a_rwlock);
			newsvd->anon_index = svd->anon_index;
		} else {
			int reclaim = 1;

			/*
			 * Allocate and initialize new anon_map structure.
			 */
			newsvd->amp = anonmap_alloc(newseg->s_size, 0);
			newsvd->amp->a_szc = newseg->s_szc;
			newsvd->anon_index = 0;

			/*
			 * We don't have to acquire the anon_map lock
			 * for the new segment (since it belongs to an
			 * address space that is still not associated
			 * with any process), or the segment in the old
			 * address space (since all threads in it
			 * are stopped while duplicating the address space).
			 */

			/*
			 * The goal of the following code is to make sure that
			 * softlocked pages do not end up as copy on write
			 * pages.  This would cause problems where one
			 * thread writes to a page that is COW and a different
			 * thread in the same process has softlocked it.  The
			 * softlock lock would move away from this process
			 * because the write would cause this process to get
			 * a copy (without the softlock).
			 *
			 * The strategy here is to just break the
			 * sharing on pages that could possibly be
			 * softlocked.
			 */
retry:
			if (svd->softlockcnt) {
				struct anon *ap, *newap;
				size_t i;
				uint_t vpprot;
				page_t *anon_pl[1+1], *pp;
				caddr_t addr;
				ulong_t anon_idx = 0;

				/*
				 * The softlock count might be non zero
				 * because some pages are still stuck in the
				 * cache for lazy reclaim. Flush the cache
				 * now. This should drop the count to zero.
				 * [or there is really I/O going on to these
				 * pages]. Note, we have the writers lock so
				 * nothing gets inserted during the flush.
				 */
				if (reclaim == 1) {
					segvn_purge(seg);
					reclaim = 0;
					goto retry;
				}
				i = btopr(seg->s_size);
				addr = seg->s_base;
				/*
				 * XXX break cow sharing using PAGESIZE
				 * pages. They will be relocated into larger
				 * pages at fault time.
				 */
				while (i-- > 0) {
					if (ap = anon_get_ptr(amp->ahp,
					    anon_idx)) {
						error = anon_getpage(&ap,
						    &vpprot, anon_pl, PAGESIZE,
						    seg, addr, S_READ,
						    svd->cred);
						if (error) {
							newsvd->vpage = NULL;
							goto out;
						}
						/*
						 * prot need not be computed
						 * below 'cause anon_private is
						 * going to ignore it anyway
						 * as child doesn't inherit
						 * pagelock from parent.
						 */
						prot = svd->pageprot ?
						    VPP_PROT(
						    &svd->vpage[
						    seg_page(seg, addr)])
						    : svd->prot;
						pp = anon_private(&newap,
						    newseg, addr, prot,
						    anon_pl[0],	0,
						    newsvd->cred);
						if (pp == NULL) {
							/* no mem abort */
							newsvd->vpage = NULL;
							error = ENOMEM;
							goto out;
						}
						(void) anon_set_ptr(
						    newsvd->amp->ahp, anon_idx,
						    newap, ANON_SLEEP);
						page_unlock(pp);
					}
					addr += PAGESIZE;
					anon_idx++;
				}
			} else {	/* common case */
				if (seg->s_szc != 0) {
					/*
					 * If at least one of anon slots of a
					 * large page exists then make sure
					 * all anon slots of a large page
					 * exist to avoid partial cow sharing
					 * of a large page in the future.
					 */
					anon_dup_fill_holes(amp->ahp,
					    svd->anon_index, newsvd->amp->ahp,
					    0, seg->s_size, seg->s_szc,
					    svd->vp != NULL);
				} else {
					anon_dup(amp->ahp, svd->anon_index,
					    newsvd->amp->ahp, 0, seg->s_size);
				}

				hat_clrattr(seg->s_as->a_hat, seg->s_base,
				    seg->s_size, PROT_WRITE);
			}
		}
	}
	/*
	 * If necessary, create a vpage structure for the new segment.
	 * Do not copy any page lock indications.
	 */
	if (svd->vpage != NULL) {
		uint_t i;
		struct vpage *ovp = svd->vpage;
		struct vpage *nvp;

		nvp = newsvd->vpage =
		    kmem_alloc(vpgtob(npages), KM_SLEEP);
		for (i = 0; i < npages; i++) {
			*nvp = *ovp++;
			VPP_CLRPPLOCK(nvp++);
		}
	} else
		newsvd->vpage = NULL;

	/* Inform the vnode of the new mapping */
	if (newsvd->vp != NULL) {
		error = VOP_ADDMAP(newsvd->vp, (offset_t)newsvd->offset,
		    newseg->s_as, newseg->s_base, newseg->s_size, newsvd->prot,
		    newsvd->maxprot, newsvd->type, newsvd->cred);
	}
out:
	return (error);
}


/*
 * callback function used by segvn_unmap to invoke free_vp_pages() for only
 * those pages actually processed by the HAT
 */
extern int free_pages;

static void
segvn_hat_unload_callback(hat_callback_t *cb)
{
	struct seg		*seg = cb->hcb_data;
	struct segvn_data	*svd = (struct segvn_data *)seg->s_data;
	size_t			len;
	u_offset_t		off;

	ASSERT(svd->vp != NULL);
	ASSERT(cb->hcb_end_addr > cb->hcb_start_addr);
	ASSERT(cb->hcb_start_addr >= seg->s_base);

	len = cb->hcb_end_addr - cb->hcb_start_addr;
	off = cb->hcb_start_addr - seg->s_base;
	free_vp_pages(svd->vp, svd->offset + off, len);
}


static int
segvn_unmap(struct seg *seg, caddr_t addr, size_t len)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct segvn_data *nsvd;
	struct seg *nseg;
	struct anon_map *amp;
	pgcnt_t	opages;		/* old segment size in pages */
	pgcnt_t	npages;		/* new segment size in pages */
	pgcnt_t	dpages;		/* pages being deleted (unmapped) */
	hat_callback_t callback;	/* used for free_vp_pages() */
	hat_callback_t *cbp = NULL;
	caddr_t nbase;
	size_t nsize;
	size_t oswresv;
	int reclaim = 1;

	/*
	 * We don't need any segment level locks for "segvn" data
	 * since the address space is "write" locked.
	 */
	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));

	/*
	 * Fail the unmap if pages are SOFTLOCKed through this mapping.
	 * softlockcnt is protected from change by the as write lock.
	 */
retry:
	if (svd->softlockcnt > 0) {
		/*
		 * since we do have the writers lock nobody can fill
		 * the cache during the purge. The flush either succeeds
		 * or we still have pending I/Os.
		 */
		if (reclaim == 1) {
			segvn_purge(seg);
			reclaim = 0;
			goto retry;
		}
		return (EAGAIN);
	}

	/*
	 * Check for bad sizes
	 */
	if (addr < seg->s_base || addr + len > seg->s_base + seg->s_size ||
	    (len & PAGEOFFSET) || ((uintptr_t)addr & PAGEOFFSET)) {
		panic("segvn_unmap");
		/*NOTREACHED*/
	}

	if (seg->s_szc != 0) {
		size_t pgsz = page_get_pagesize(seg->s_szc);
		int err;
		if (!IS_P2ALIGNED(addr, pgsz) || !IS_P2ALIGNED(len, pgsz)) {
			ASSERT(seg->s_base != addr || seg->s_size != len);
			VM_STAT_ADD(segvnvmstats.demoterange[0]);
			err = segvn_demote_range(seg, addr, len, SDR_END);
			if (err == 0) {
				return (IE_RETRY);
			}
			return (err);
		}
	}

	/* Inform the vnode of the unmapping. */
	if (svd->vp) {
		int error;

		error = VOP_DELMAP(svd->vp,
			(offset_t)svd->offset + (uintptr_t)(addr - seg->s_base),
			seg->s_as, addr, len, svd->prot, svd->maxprot,
			svd->type, svd->cred);

		if (error == EAGAIN)
			return (error);
	}
	/*
	 * Remove any page locks set through this mapping.
	 */
	(void) segvn_lockop(seg, addr, len, 0, MC_UNLOCK, NULL, 0);

	/*
	 * Unload any hardware translations in the range to be taken out.
	 * Use a callback to invoke free_vp_pages() effectively.
	 */
	if (svd->vp != NULL && free_pages != 0) {
		callback.hcb_data = seg;
		callback.hcb_function = segvn_hat_unload_callback;
		cbp = &callback;
	}
	hat_unload_callback(seg->s_as->a_hat, addr, len, HAT_UNLOAD_UNMAP, cbp);

	/*
	 * Check for entire segment
	 */
	if (addr == seg->s_base && len == seg->s_size) {
		seg_free(seg);
		return (0);
	}

	opages = seg_pages(seg);
	dpages = btop(len);
	npages = opages - dpages;
	amp = svd->amp;

	/*
	 * Check for beginning of segment
	 */
	if (addr == seg->s_base) {
		if (svd->vpage != NULL) {
			size_t nbytes;
			struct vpage *ovpage;

			ovpage = svd->vpage;	/* keep pointer to vpage */

			nbytes = vpgtob(npages);
			svd->vpage = kmem_alloc(nbytes, KM_SLEEP);
			bcopy(&ovpage[dpages], svd->vpage, nbytes);

			/* free up old vpage */
			kmem_free(ovpage, vpgtob(opages));
		}
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			if (amp->refcnt == 1 || svd->type == MAP_PRIVATE) {
				/*
				 * Free up now unused parts of anon_map array.
				 */
				if (seg->s_szc != 0) {
					anon_free_pages(amp->ahp,
					    svd->anon_index, len, seg->s_szc);
				} else {
					anon_free(amp->ahp, svd->anon_index,
					    len);
				}

				/*
				 * Unreserve swap space for the unmapped chunk
				 * of this segment in case it's MAP_SHARED
				 */
				if (svd->type == MAP_SHARED) {
					anon_unresv(len);
					amp->swresv -= len;
				}
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
			svd->anon_index += dpages;
		}
		if (svd->vp != NULL)
			svd->offset += len;

		if (svd->swresv) {
			if (svd->flags & MAP_NORESERVE) {
				ASSERT(amp);
				oswresv = svd->swresv;

				svd->swresv = ptob(anon_pages(amp->ahp,
				    svd->anon_index, npages));
				anon_unresv(oswresv - svd->swresv);
			} else {
				anon_unresv(len);
				svd->swresv -= len;
			}
			TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
				seg, len, 0);
		}

		seg->s_base += len;
		seg->s_size -= len;
		return (0);
	}

	/*
	 * Check for end of segment
	 */
	if (addr + len == seg->s_base + seg->s_size) {
		if (svd->vpage != NULL) {
			size_t nbytes;
			struct vpage *ovpage;

			ovpage = svd->vpage;	/* keep pointer to vpage */

			nbytes = vpgtob(npages);
			svd->vpage = kmem_alloc(nbytes, KM_SLEEP);
			bcopy(ovpage, svd->vpage, nbytes);

			/* free up old vpage */
			kmem_free(ovpage, vpgtob(opages));

		}
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			if (amp->refcnt == 1 || svd->type == MAP_PRIVATE) {
				/*
				 * Free up now unused parts of anon_map array
				 */
				if (seg->s_szc != 0) {
					ulong_t an_idx = svd->anon_index +
					    npages;
					anon_free_pages(amp->ahp, an_idx,
					    len, seg->s_szc);
				} else {
					anon_free(amp->ahp,
					    svd->anon_index + npages, len);
				}
				/*
				 * Unreserve swap space for the unmapped chunk
				 * of this segment in case it's MAP_SHARED
				 */
				if (svd->type == MAP_SHARED) {
					anon_unresv(len);
					amp->swresv -= len;
				}
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}

		if (svd->swresv) {
			if (svd->flags & MAP_NORESERVE) {
				ASSERT(amp);
				oswresv = svd->swresv;
				svd->swresv = ptob(anon_pages(amp->ahp,
					svd->anon_index, npages));
				anon_unresv(oswresv - svd->swresv);
			} else {
				anon_unresv(len);
				svd->swresv -= len;
			}
			TRACE_3(TR_FAC_VM, TR_ANON_PROC,
				"anon proc:%p %lu %u", seg, len, 0);
		}

		seg->s_size -= len;
		return (0);
	}

	/*
	 * The section to go is in the middle of the segment,
	 * have to make it into two segments.  nseg is made for
	 * the high end while seg is cut down at the low end.
	 */
	nbase = addr + len;				/* new seg base */
	nsize = (seg->s_base + seg->s_size) - nbase;	/* new seg size */
	seg->s_size = addr - seg->s_base;		/* shrink old seg */
	nseg = seg_alloc(seg->s_as, nbase, nsize);
	if (nseg == NULL) {
		panic("segvn_unmap seg_alloc");
		/*NOTREACHED*/
	}
	nseg->s_ops = seg->s_ops;
	nsvd = kmem_cache_alloc(segvn_cache, KM_SLEEP);
	nseg->s_data = (void *)nsvd;
	nseg->s_szc = seg->s_szc;
	*nsvd = *svd;
	nsvd->offset = svd->offset + (uintptr_t)(nseg->s_base - seg->s_base);
	nsvd->swresv = 0;
	nsvd->softlockcnt = 0;

	if (svd->vp != NULL) {
		VN_HOLD(nsvd->vp);
		if (nsvd->type == MAP_SHARED)
			lgrp_shm_policy_init(NULL, nsvd->vp);
	}
	crhold(svd->cred);

	if (svd->vpage == NULL) {
		nsvd->vpage = NULL;
	} else {
		/* need to split vpage into two arrays */
		size_t nbytes;
		struct vpage *ovpage;

		ovpage = svd->vpage;		/* keep pointer to vpage */

		npages = seg_pages(seg);	/* seg has shrunk */
		nbytes = vpgtob(npages);
		svd->vpage = kmem_alloc(nbytes, KM_SLEEP);

		bcopy(ovpage, svd->vpage, nbytes);

		npages = seg_pages(nseg);
		nbytes = vpgtob(npages);
		nsvd->vpage = kmem_alloc(nbytes, KM_SLEEP);

		bcopy(&ovpage[opages - npages], nsvd->vpage, nbytes);

		/* free up old vpage */
		kmem_free(ovpage, vpgtob(opages));
	}

	if (amp == NULL) {
		nsvd->amp = NULL;
		nsvd->anon_index = 0;
	} else {
		/*
		 * Need to create a new anon map for the new segment.
		 * We'll also allocate a new smaller array for the old
		 * smaller segment to save space.
		 */
		opages = btop((uintptr_t)(addr - seg->s_base));
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
		if (amp->refcnt == 1 || svd->type == MAP_PRIVATE) {
			/*
			 * Free up now unused parts of anon_map array
			 */
			if (seg->s_szc != 0) {
				ulong_t an_idx = svd->anon_index + opages;
				anon_free_pages(amp->ahp, an_idx, len,
				    seg->s_szc);
			} else {
				anon_free(amp->ahp, svd->anon_index + opages,
				    len);
			}

			/*
			 * Unreserve swap space for the unmapped chunk
			 * of this segment in case it's MAP_SHARED
			 */
			if (svd->type == MAP_SHARED) {
				anon_unresv(len);
				amp->swresv -= len;
			}
		}

		nsvd->anon_index = svd->anon_index +
		    btop((uintptr_t)(nseg->s_base - seg->s_base));
		if (svd->type == MAP_SHARED) {
			ASSERT(seg->s_szc == 0);
			amp->refcnt++;
			nsvd->amp = amp;
		} else {
			struct anon_map *namp;
			struct anon_hdr *nahp;

			ASSERT(svd->type == MAP_PRIVATE);
			nahp = anon_create(btop(seg->s_size), ANON_SLEEP);
			namp = anonmap_alloc(nseg->s_size, 0);
			namp->a_szc = seg->s_szc;
			(void) anon_copy_ptr(amp->ahp, svd->anon_index, nahp,
			    0, btop(seg->s_size), ANON_SLEEP);
			(void) anon_copy_ptr(amp->ahp, nsvd->anon_index,
			    namp->ahp, 0, btop(nseg->s_size), ANON_SLEEP);
			anon_release(amp->ahp, btop(amp->size));
			svd->anon_index = 0;
			nsvd->anon_index = 0;
			amp->ahp = nahp;
			amp->size = seg->s_size;
			nsvd->amp = namp;
		}
		ANON_LOCK_EXIT(&amp->a_rwlock);
	}
	if (svd->swresv) {
		if (svd->flags & MAP_NORESERVE) {
			ASSERT(amp);
			oswresv = svd->swresv;
			svd->swresv = ptob(anon_pages(amp->ahp,
				svd->anon_index, btop(seg->s_size)));
			nsvd->swresv = ptob(anon_pages(nsvd->amp->ahp,
				nsvd->anon_index, btop(nseg->s_size)));
			ASSERT(oswresv >= (svd->swresv + nsvd->swresv));
			anon_unresv(oswresv - (svd->swresv + nsvd->swresv));
		} else {
			if (seg->s_size + nseg->s_size + len != svd->swresv) {
				panic("segvn_unmap: "
				    "cannot split swap reservation");
				/*NOTREACHED*/
			}
			anon_unresv(len);
			svd->swresv = seg->s_size;
			nsvd->swresv = nseg->s_size;
		}
		TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
			seg, len, 0);
	}

	return (0);			/* I'm glad that's all over with! */
}

static void
segvn_free(struct seg *seg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	pgcnt_t npages = seg_pages(seg);
	struct anon_map *amp;
	size_t len;

	/*
	 * We don't need any segment level locks for "segvn" data
	 * since the address space is "write" locked.
	 */
	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));

	/*
	 * Be sure to unlock pages. XXX Why do things get free'ed instead
	 * of unmapped? XXX
	 */
	(void) segvn_lockop(seg, seg->s_base, seg->s_size,
	    0, MC_UNLOCK, NULL, 0);

	/*
	 * Deallocate the vpage and anon pointers if necessary and possible.
	 */
	if (svd->vpage != NULL) {
		kmem_free(svd->vpage, vpgtob(npages));
		svd->vpage = NULL;
	}
	if ((amp = svd->amp) != NULL) {
		/*
		 * If there are no more references to this anon_map
		 * structure, then deallocate the structure after freeing
		 * up all the anon slot pointers that we can.
		 */
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
		if (--amp->refcnt == 0) {
			if (svd->type == MAP_PRIVATE) {
				/*
				 * Private - we only need to anon_free
				 * the part that this segment refers to.
				 */
				if (seg->s_szc != 0) {
					anon_free_pages(amp->ahp,
					    svd->anon_index, seg->s_size,
					    seg->s_szc);
				} else {
					anon_free(amp->ahp, svd->anon_index,
					    seg->s_size);
				}
			} else {
				/*
				 * Shared - anon_free the entire
				 * anon_map's worth of stuff and
				 * release any swap reservation.
				 */
				ASSERT(seg->s_szc == 0);
				anon_free(amp->ahp, 0, amp->size);
				if ((len = amp->swresv) != 0) {
					anon_unresv(len);
					TRACE_3(TR_FAC_VM, TR_ANON_PROC,
						"anon proc:%p %lu %u",
						seg, len, 0);
				}
			}
			svd->amp = NULL;
			ANON_LOCK_EXIT(&amp->a_rwlock);
			anonmap_free(amp);
		} else if (svd->type == MAP_PRIVATE) {
			/*
			 * We had a private mapping which still has
			 * a held anon_map so just free up all the
			 * anon slot pointers that we were using.
			 */
			if (seg->s_szc != 0) {
				anon_free_pages(amp->ahp, svd->anon_index,
				    seg->s_size, seg->s_szc);
			} else {
				anon_free(amp->ahp, svd->anon_index,
				    seg->s_size);
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
		} else {
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}
	}

	/*
	 * Release swap reservation.
	 */
	if ((len = svd->swresv) != 0) {
		anon_unresv(svd->swresv);
		TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
			seg, len, 0);
		svd->swresv = 0;
	}
	/*
	 * Release claim on vnode, credentials, and finally free the
	 * private data.
	 */
	if (svd->vp != NULL) {
		if (svd->type == MAP_SHARED)
			lgrp_shm_policy_fini(NULL, svd->vp);
		VN_RELE(svd->vp);
		svd->vp = NULL;
	}
	crfree(svd->cred);
	svd->cred = NULL;

	seg->s_data = NULL;
	kmem_cache_free(segvn_cache, svd);
}

/*
 * Do a F_SOFTUNLOCK call over the range requested.  The range must have
 * already been F_SOFTLOCK'ed.
 * Caller must always match addr and len of a softunlock with a previous
 * softlock with exactly the same addr and len.
 */
static void
segvn_softunlock(struct seg *seg, caddr_t addr, size_t len, enum seg_rw rw)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	page_t *pp;
	caddr_t adr;
	struct vnode *vp;
	u_offset_t offset;
	ulong_t anon_index;
	struct anon_map *amp;
	struct anon *ap = NULL;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));
	ASSERT(SEGVN_LOCK_HELD(seg->s_as, &svd->lock));

	if ((amp = svd->amp) != NULL)
		anon_index = svd->anon_index + seg_page(seg, addr);

	hat_unlock(seg->s_as->a_hat, addr, len);
	for (adr = addr; adr < addr + len; adr += PAGESIZE) {
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			if ((ap = anon_get_ptr(amp->ahp, anon_index++))
								!= NULL) {
				swap_xlate(ap, &vp, &offset);
			} else {
				vp = svd->vp;
				offset = svd->offset +
				    (uintptr_t)(adr - seg->s_base);
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
		} else {
			vp = svd->vp;
			offset = svd->offset +
			    (uintptr_t)(adr - seg->s_base);
		}

		/*
		 * Use page_find() instead of page_lookup() to
		 * find the page since we know that it is locked.
		 */
		pp = page_find(vp, offset);
		if (pp == NULL) {
			panic(
			    "segvn_softunlock: addr %p, ap %p, vp %p, off %llx",
			    (void *)adr, (void *)ap, (void *)vp, offset);
			/*NOTREACHED*/
		}

		if (rw == S_WRITE) {
			hat_setrefmod(pp);
			if (seg->s_as->a_vbits)
				hat_setstat(seg->s_as, adr, PAGESIZE,
				    P_REF | P_MOD);
		} else if (rw != S_OTHER) {
			hat_setref(pp);
			if (seg->s_as->a_vbits)
				hat_setstat(seg->s_as, adr, PAGESIZE, P_REF);
		}
		TRACE_3(TR_FAC_VM, TR_SEGVN_FAULT,
			"segvn_fault:pp %p vp %p offset %llx", pp, vp, offset);
		page_unlock(pp);
	}
	mutex_enter(&freemem_lock); /* for availrmem */
	availrmem += btop(len);
	segvn_pages_locked -= btop(len);
	svd->softlockcnt -= btop(len);
	mutex_exit(&freemem_lock);
	if (svd->softlockcnt == 0) {
		/*
		 * All SOFTLOCKS are gone. Wakeup any waiting
		 * unmappers so they can try again to unmap.
		 * Check for waiters first without the mutex
		 * held so we don't always grab the mutex on
		 * softunlocks.
		 */
		if (AS_ISUNMAPWAIT(seg->s_as)) {
			mutex_enter(&seg->s_as->a_contents);
			if (AS_ISUNMAPWAIT(seg->s_as)) {
				AS_CLRUNMAPWAIT(seg->s_as);
				cv_broadcast(&seg->s_as->a_cv);
			}
			mutex_exit(&seg->s_as->a_contents);
		}
	}
}

#define	PAGE_HANDLED	((page_t *)-1)

/*
 * Release all the pages in the NULL terminated ppp list
 * which haven't already been converted to PAGE_HANDLED.
 */
static void
segvn_pagelist_rele(page_t **ppp)
{
	for (; *ppp != NULL; ppp++) {
		if (*ppp != PAGE_HANDLED)
			page_unlock(*ppp);
	}
}

static int stealcow = 1;

/*
 * Workaround for viking chip bug.  See bug id 1220902.
 * To fix this down in pagefault() would require importing so
 * much as and segvn code as to be unmaintainable.
 */
int enable_mbit_wa = 0;

/*
 * Handles all the dirty work of getting the right
 * anonymous pages and loading up the translations.
 * This routine is called only from segvn_fault()
 * when looping over the range of addresses requested.
 *
 * The basic algorithm here is:
 * 	If this is an anon_zero case
 *		Call anon_zero to allocate page
 *		Load up translation
 *		Return
 *	endif
 *	If this is an anon page
 *		Use anon_getpage to get the page
 *	else
 *		Find page in pl[] list passed in
 *	endif
 *	If not a cow
 *		Load up the translation to the page
 *		return
 *	endif
 *	Call anon_private to handle cow
 *	Load up (writable) translation to new page
 */
static faultcode_t
segvn_faultpage(
	struct hat *hat,		/* the hat to use for mapping */
	struct seg *seg,		/* seg_vn of interest */
	caddr_t addr,			/* address in as */
	u_offset_t off,			/* offset in vp */
	struct vpage *vpage,		/* pointer to vpage for vp, off */
	page_t *pl[],			/* object source page pointer */
	uint_t vpprot,			/* access allowed to object pages */
	enum fault_type type,		/* type of fault */
	enum seg_rw rw,			/* type of access at fault */
	int brkcow)			/* we may need to break cow */
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	page_t *pp, **ppp;
	uint_t pageflags = 0;
	page_t *anon_pl[1 + 1];
	page_t *opp = NULL;		/* original page */
	uint_t prot;
	int err;
	int cow;
	int claim;
	int steal = 0;
	ulong_t anon_index;
	struct anon *ap, *oldap;
	struct anon_map *amp;
	int hat_flag = (type == F_SOFTLOCK) ? HAT_LOAD_LOCK : HAT_LOAD;
	int anon_lock = 0;
	anon_sync_obj_t cookie;

	if (svd->flags & MAP_TEXT) {
		hat_flag |= HAT_LOAD_TEXT;
	}

	ASSERT(SEGVN_READ_HELD(seg->s_as, &svd->lock));
	ASSERT(seg->s_szc == 0);

	/*
	 * Initialize protection value for this page.
	 * If we have per page protection values check it now.
	 */
	if (svd->pageprot) {
		uint_t protchk;

		switch (rw) {
		case S_READ:
			protchk = PROT_READ;
			break;
		case S_WRITE:
			protchk = PROT_WRITE;
			break;
		case S_EXEC:
			protchk = PROT_EXEC;
			break;
		case S_OTHER:
		default:
			protchk = PROT_READ | PROT_WRITE | PROT_EXEC;
			break;
		}

		prot = VPP_PROT(vpage);
		if ((prot & protchk) == 0)
			return (FC_PROT);	/* illegal access type */
	} else {
		prot = svd->prot;
	}

	if (type == F_SOFTLOCK) {
		mutex_enter(&freemem_lock);
		if (availrmem <= tune.t_minarmem) {
			mutex_exit(&freemem_lock);
			return (FC_MAKE_ERR(ENOMEM));	/* out of real memory */
		} else {
			svd->softlockcnt++;
			availrmem--;
			segvn_pages_locked++;
		}
		mutex_exit(&freemem_lock);
	}

	/*
	 * Always acquire the anon array lock to prevent 2 threads from
	 * allocating separate anon slots for the same "addr".
	 */

	if ((amp = svd->amp) != NULL) {
		ASSERT(RW_READ_HELD(&amp->a_rwlock));
		anon_index = svd->anon_index + seg_page(seg, addr);
		anon_array_enter(amp, anon_index, &cookie);
		anon_lock = 1;
	}

	if (svd->vp == NULL && amp != NULL) {
		if ((ap = anon_get_ptr(amp->ahp, anon_index)) == NULL) {
			/*
			 * Allocate a (normally) writable anonymous page of
			 * zeroes. If no advance reservations, reserve now.
			 */
			if (svd->flags & MAP_NORESERVE) {
				if (anon_resv(ptob(1))) {
					svd->swresv += ptob(1);
				} else {
					err = ENOMEM;
					goto out;
				}
			}
			if ((pp = anon_zero(seg, addr, &ap,
			    svd->cred)) == NULL) {
				err = ENOMEM;
				goto out;	/* out of swap space */
			}
			/*
			 * Re-acquire the anon_map lock and
			 * initialize the anon array entry.
			 */
			(void) anon_set_ptr(amp->ahp, anon_index, ap,
				ANON_SLEEP);
			if (enable_mbit_wa) {
				if (rw == S_WRITE)
					hat_setmod(pp);
				else if (!hat_ismod(pp))
					prot &= ~PROT_WRITE;
			}
			/*
			 * If AS_PAGLCK is set in a_flags (via memcntl(2)
			 * with MC_LOCKAS, MCL_FUTURE) and this is a
			 * MAP_NORESERVE segment, we may need to
			 * permanently lock the page as it is being faulted
			 * for the first time. The following text applies
			 * only to MAP_NORESERVE segments:
			 *
			 * As per memcntl(2), if this segment was created
			 * after MCL_FUTURE was applied (a "future"
			 * segment), its pages must be locked.  If this
			 * segment existed at MCL_FUTURE application (a
			 * "past" segment), the interface is unclear.
			 *
			 * We decide to lock only if vpage is present:
			 *
			 * - "future" segments will have a vpage array (see
			 *    as_map), and so will be locked as required
			 *
			 * - "past" segments may not have a vpage array,
			 *    depending on whether events (such as
			 *    mprotect) have occurred. Locking if vpage
			 *    exists will preserve legacy behavior.  Not
			 *    locking if vpage is absent, will not break
			 *    the interface or legacy behavior.  Note that
			 *    allocating vpage here if it's absent requires
			 *    upgrading the segvn reader lock, the cost of
			 *    which does not seem worthwhile.
			 */
			if (AS_ISPGLCK(seg->s_as) && vpage != NULL &&
			    (svd->flags & MAP_NORESERVE)) {
				claim = VPP_PROT(vpage) & PROT_WRITE;
				ASSERT(svd->type == MAP_PRIVATE);
				if (page_pp_lock(pp, claim, 0))
					VPP_SETPPLOCK(vpage);
			}


			/*
			 * Handle pages that have been marked for migration
			 */
			if (lgrp_optimizations())
				page_migrate(seg, addr, &pp, 1);
			hat_memload(hat, addr, pp, prot, hat_flag);

			if (!(hat_flag & HAT_LOAD_LOCK))
				page_unlock(pp);

			anon_array_exit(&cookie);
			return (0);
		}
	}

	/*
	 * Obtain the page structure via anon_getpage() if it is
	 * a private copy of an object (the result of a previous
	 * copy-on-write).
	 */
	if (amp != NULL) {
		if ((ap = anon_get_ptr(amp->ahp, anon_index)) != NULL) {
			err = anon_getpage(&ap, &vpprot, anon_pl, PAGESIZE,
			    seg, addr, rw, svd->cred);
			if (err)
				goto out;

			if (svd->type == MAP_SHARED) {
				/*
				 * If this is a shared mapping to an
				 * anon_map, then ignore the write
				 * permissions returned by anon_getpage().
				 * They apply to the private mappings
				 * of this anon_map.
				 */
				vpprot |= PROT_WRITE;
			}
			opp = anon_pl[0];
		}
	}

	/*
	 * Search the pl[] list passed in if it is from the
	 * original object (i.e., not a private copy).
	 */
	if (opp == NULL) {
		/*
		 * Find original page.  We must be bringing it in
		 * from the list in pl[].
		 */
		for (ppp = pl; (opp = *ppp) != NULL; ppp++) {
			if (opp == PAGE_HANDLED)
				continue;
			ASSERT(opp->p_vnode == svd->vp); /* XXX */
			if (opp->p_offset == off)
				break;
		}
		if (opp == NULL) {
			panic("segvn_faultpage not found");
			/*NOTREACHED*/
		}
		*ppp = PAGE_HANDLED;

	}

	ASSERT(PAGE_LOCKED(opp));

	TRACE_3(TR_FAC_VM, TR_SEGVN_FAULT,
		"segvn_fault:pp %p vp %p offset %llx",
		opp, NULL, 0);

	/*
	 * The fault is treated as a copy-on-write fault if a
	 * write occurs on a private segment and the object
	 * page (i.e., mapping) is write protected.  We assume
	 * that fatal protection checks have already been made.
	 */

	cow = brkcow && ((vpprot & PROT_WRITE) == 0);

	/*
	 * If not a copy-on-write case load the translation
	 * and return.
	 */
	if (cow == 0) {
		if (IS_VMODSORT(opp->p_vnode) || enable_mbit_wa) {
			if (rw == S_WRITE)
				hat_setmod(opp);
			else if (rw != S_OTHER && !hat_ismod(opp))
				prot &= ~PROT_WRITE;
		}

		/*
		 * Handle pages that have been marked for migration
		 */
		if (lgrp_optimizations())
			page_migrate(seg, addr, &opp, 1);

		hat_memload(hat, addr, opp, prot & vpprot, hat_flag);

		if (!(hat_flag & HAT_LOAD_LOCK))
			page_unlock(opp);

		if (anon_lock) {
			anon_array_exit(&cookie);
		}
		return (0);
	}

	hat_setref(opp);

	ASSERT(amp != NULL && anon_lock);

	/*
	 * Steal the page only if it isn't a private page
	 * since stealing a private page is not worth the effort.
	 */
	if ((ap = anon_get_ptr(amp->ahp, anon_index)) == NULL)
		steal = 1;

	/*
	 * Steal the original page if the following conditions are true:
	 *
	 * We are low on memory, the page is not private, page is not large,
	 * not shared, not modified, not `locked' or if we have it `locked'
	 * (i.e., p_cowcnt == 1 and p_lckcnt == 0, which also implies
	 * that the page is not shared) and if it doesn't have any
	 * translations. page_struct_lock isn't needed to look at p_cowcnt
	 * and p_lckcnt because we first get exclusive lock on page.
	 */
	(void) hat_pagesync(opp, HAT_SYNC_DONTZERO | HAT_SYNC_STOPON_MOD);

	if (stealcow && freemem < minfree && steal && opp->p_szc == 0 &&
	    page_tryupgrade(opp) && !hat_ismod(opp) &&
	    ((opp->p_lckcnt == 0 && opp->p_cowcnt == 0) ||
	    (opp->p_lckcnt == 0 && opp->p_cowcnt == 1 &&
	    vpage != NULL && VPP_ISPPLOCK(vpage)))) {
		/*
		 * Check if this page has other translations
		 * after unloading our translation.
		 */
		if (hat_page_is_mapped(opp)) {
			hat_unload(seg->s_as->a_hat, addr, PAGESIZE,
				HAT_UNLOAD);
		}

		/*
		 * hat_unload() might sync back someone else's recent
		 * modification, so check again.
		 */
		if (!hat_ismod(opp) && !hat_page_is_mapped(opp))
			pageflags |= STEAL_PAGE;
	}

	/*
	 * If we have a vpage pointer, see if it indicates that we have
	 * ``locked'' the page we map -- if so, tell anon_private to
	 * transfer the locking resource to the new page.
	 *
	 * See Statement at the beginning of segvn_lockop regarding
	 * the way lockcnts/cowcnts are handled during COW.
	 *
	 */
	if (vpage != NULL && VPP_ISPPLOCK(vpage))
		pageflags |= LOCK_PAGE;

	/*
	 * Allocate a private page and perform the copy.
	 * For MAP_NORESERVE reserve swap space now, unless this
	 * is a cow fault on an existing anon page in which case
	 * MAP_NORESERVE will have made advance reservations.
	 */
	if ((svd->flags & MAP_NORESERVE) && (ap == NULL)) {
		if (anon_resv(ptob(1))) {
			svd->swresv += ptob(1);
		} else {
			page_unlock(opp);
			err = ENOMEM;
			goto out;
		}
	}
	oldap = ap;
	pp = anon_private(&ap, seg, addr, prot, opp, pageflags, svd->cred);
	if (pp == NULL) {
		err = ENOMEM;	/* out of swap space */
		goto out;
	}

	/*
	 * If we copied away from an anonymous page, then
	 * we are one step closer to freeing up an anon slot.
	 *
	 * NOTE:  The original anon slot must be released while
	 * holding the "anon_map" lock.  This is necessary to prevent
	 * other threads from obtaining a pointer to the anon slot
	 * which may be freed if its "refcnt" is 1.
	 */
	if (oldap != NULL)
		anon_decref(oldap);

	(void) anon_set_ptr(amp->ahp, anon_index, ap, ANON_SLEEP);

	ASSERT(!IS_VMODSORT(pp->p_vnode));
	if (enable_mbit_wa) {
		if (rw == S_WRITE)
			hat_setmod(pp);
		else if (!hat_ismod(pp))
			prot &= ~PROT_WRITE;
	}


	/*
	 * Handle pages that have been marked for migration
	 */
	if (lgrp_optimizations())
		page_migrate(seg, addr, &pp, 1);
	hat_memload(hat, addr, pp, prot, hat_flag);

	if (!(hat_flag & HAT_LOAD_LOCK))
		page_unlock(pp);

	ASSERT(anon_lock);
	anon_array_exit(&cookie);
	return (0);
out:
	if (anon_lock)
		anon_array_exit(&cookie);

	if (type == F_SOFTLOCK) {
		mutex_enter(&freemem_lock);
		availrmem++;
		segvn_pages_locked--;
		svd->softlockcnt--;
		mutex_exit(&freemem_lock);
	}
	return (FC_MAKE_ERR(err));
}

/*
 * relocate a bunch of smaller targ pages into one large repl page. all targ
 * pages must be complete pages smaller than replacement pages.
 * it's assumed that no page's szc can change since they are all PAGESIZE or
 * complete large pages locked SHARED.
 */
static void
segvn_relocate_pages(page_t **targ, page_t *replacement)
{
	page_t *pp;
	pgcnt_t repl_npgs, curnpgs;
	pgcnt_t i;
	uint_t repl_szc = replacement->p_szc;
	page_t *first_repl = replacement;
	page_t *repl;
	spgcnt_t npgs;

	VM_STAT_ADD(segvnvmstats.relocatepages[0]);

	ASSERT(repl_szc != 0);
	npgs = repl_npgs = page_get_pagecnt(repl_szc);

	i = 0;
	while (repl_npgs) {
		spgcnt_t nreloc;
		int err;
		ASSERT(replacement != NULL);
		pp = targ[i];
		ASSERT(pp->p_szc < repl_szc);
		ASSERT(PAGE_EXCL(pp));
		ASSERT(!PP_ISFREE(pp));
		curnpgs = page_get_pagecnt(pp->p_szc);
		if (curnpgs == 1) {
			VM_STAT_ADD(segvnvmstats.relocatepages[1]);
			repl = replacement;
			page_sub(&replacement, repl);
			ASSERT(PAGE_EXCL(repl));
			ASSERT(!PP_ISFREE(repl));
			ASSERT(repl->p_szc == repl_szc);
		} else {
			page_t *repl_savepp;
			int j;
			VM_STAT_ADD(segvnvmstats.relocatepages[2]);
			repl_savepp = replacement;
			for (j = 0; j < curnpgs; j++) {
				repl = replacement;
				page_sub(&replacement, repl);
				ASSERT(PAGE_EXCL(repl));
				ASSERT(!PP_ISFREE(repl));
				ASSERT(repl->p_szc == repl_szc);
				ASSERT(page_pptonum(targ[i + j]) ==
				    page_pptonum(targ[i]) + j);
			}
			repl = repl_savepp;
			ASSERT(IS_P2ALIGNED(page_pptonum(repl), curnpgs));
		}
		err = page_relocate(&pp, &repl, 0, 1, &nreloc, NULL);
		if (err || nreloc != curnpgs) {
			panic("segvn_relocate_pages: "
			    "page_relocate failed err=%d curnpgs=%ld "
			    "nreloc=%ld", err, curnpgs, nreloc);
		}
		ASSERT(curnpgs <= repl_npgs);
		repl_npgs -= curnpgs;
		i += curnpgs;
	}
	ASSERT(replacement == NULL);

	repl = first_repl;
	repl_npgs = npgs;
	for (i = 0; i < repl_npgs; i++) {
		ASSERT(PAGE_EXCL(repl));
		ASSERT(!PP_ISFREE(repl));
		targ[i] = repl;
		page_downgrade(targ[i]);
		repl++;
	}
}

/*
 * Check if all pages in ppa array are complete smaller than szc pages and
 * their roots will still be aligned relative to their current size if the
 * entire ppa array is relocated into one szc page. If these conditions are
 * not met return 0.
 *
 * If all pages are properly aligned attempt to upgrade their locks
 * to exclusive mode. If it fails set *upgrdfail to 1 and return 0.
 * upgrdfail was set to 0 by caller.
 *
 * Return 1 if all pages are aligned and locked exclusively.
 *
 * If all pages in ppa array happen to be physically contiguous to make one
 * szc page and all exclusive locks are successfully obtained promote the page
 * size to szc and set *pszc to szc. Return 1 with pages locked shared.
 */
static int
segvn_full_szcpages(page_t **ppa, uint_t szc, int *upgrdfail, uint_t *pszc)
{
	page_t *pp;
	pfn_t pfn;
	pgcnt_t totnpgs = page_get_pagecnt(szc);
	pfn_t first_pfn;
	int contig = 1;
	pgcnt_t i;
	pgcnt_t j;
	uint_t curszc;
	pgcnt_t curnpgs;
	int root = 0;

	ASSERT(szc > 0);

	VM_STAT_ADD(segvnvmstats.fullszcpages[0]);

	for (i = 0; i < totnpgs; i++) {
		pp = ppa[i];
		ASSERT(PAGE_SHARED(pp));
		ASSERT(!PP_ISFREE(pp));
		pfn = page_pptonum(pp);
		if (i == 0) {
			if (!IS_P2ALIGNED(pfn, totnpgs)) {
				contig = 0;
			} else {
				first_pfn = pfn;
			}
		} else if (contig && pfn != first_pfn + i) {
			contig = 0;
		}
		if (pp->p_szc == 0) {
			if (root) {
				VM_STAT_ADD(segvnvmstats.fullszcpages[1]);
				return (0);
			}
		} else if (!root) {
			if ((curszc = pp->p_szc) >= szc) {
				VM_STAT_ADD(segvnvmstats.fullszcpages[2]);
				return (0);
			}
			if (curszc == 0) {
				/*
				 * p_szc changed means we don't have all pages
				 * locked. return failure.
				 */
				VM_STAT_ADD(segvnvmstats.fullszcpages[3]);
				return (0);
			}
			curnpgs = page_get_pagecnt(curszc);
			if (!IS_P2ALIGNED(pfn, curnpgs) ||
			    !IS_P2ALIGNED(i, curnpgs)) {
				VM_STAT_ADD(segvnvmstats.fullszcpages[4]);
				return (0);
			}
			root = 1;
		} else {
			ASSERT(i > 0);
			VM_STAT_ADD(segvnvmstats.fullszcpages[5]);
			if (pp->p_szc != curszc) {
				VM_STAT_ADD(segvnvmstats.fullszcpages[6]);
				return (0);
			}
			if (pfn - 1 != page_pptonum(ppa[i - 1])) {
				panic("segvn_full_szcpages: "
				    "large page not physically contiguous");
			}
			if (P2PHASE(pfn, curnpgs) == curnpgs - 1) {
				root = 0;
			}
		}
	}

	for (i = 0; i < totnpgs; i++) {
		ASSERT(ppa[i]->p_szc < szc);
		if (!page_tryupgrade(ppa[i])) {
			for (j = 0; j < i; j++) {
				page_downgrade(ppa[j]);
			}
			*pszc = ppa[i]->p_szc;
			*upgrdfail = 1;
			VM_STAT_ADD(segvnvmstats.fullszcpages[7]);
			return (0);
		}
	}

	/*
	 * When a page is put a free cachelist its szc is set to 0.  if file
	 * system reclaimed pages from cachelist targ pages will be physically
	 * contiguous with 0 p_szc.  in this case just upgrade szc of targ
	 * pages without any relocations.
	 * To avoid any hat issues with previous small mappings
	 * hat_pageunload() the target pages first.
	 */
	if (contig) {
		VM_STAT_ADD(segvnvmstats.fullszcpages[8]);
		for (i = 0; i < totnpgs; i++) {
			(void) hat_pageunload(ppa[i], HAT_FORCE_PGUNLOAD);
		}
		for (i = 0; i < totnpgs; i++) {
			ppa[i]->p_szc = szc;
		}
		for (i = 0; i < totnpgs; i++) {
			ASSERT(PAGE_EXCL(ppa[i]));
			page_downgrade(ppa[i]);
		}
		if (pszc != NULL) {
			*pszc = szc;
		}
	}
	VM_STAT_ADD(segvnvmstats.fullszcpages[9]);
	return (1);
}

/*
 * Create physically contiguous pages for [vp, off] - [vp, off +
 * page_size(szc)) range and for private segment return them in ppa array.
 * Pages are created either via IO or relocations.
 *
 * Return 1 on sucess and 0 on failure.
 *
 * If physically contiguos pages already exist for this range return 1 without
 * filling ppa array. Caller initializes ppa[0] as NULL to detect that ppa
 * array wasn't filled. In this case caller fills ppa array via VOP_GETPAGE().
 */

static int
segvn_fill_vp_pages(struct segvn_data *svd, vnode_t *vp, u_offset_t off,
    uint_t szc, page_t **ppa, page_t **ppplist, uint_t *ret_pszc,
    int *downsize)

{
	page_t *pplist = *ppplist;
	size_t pgsz = page_get_pagesize(szc);
	pgcnt_t pages = btop(pgsz);
	ulong_t start_off = off;
	u_offset_t eoff = off + pgsz;
	spgcnt_t nreloc;
	u_offset_t io_off = off;
	size_t io_len;
	page_t *io_pplist = NULL;
	page_t *done_pplist = NULL;
	pgcnt_t pgidx = 0;
	page_t *pp;
	page_t *newpp;
	page_t *targpp;
	int io_err = 0;
	int i;
	pfn_t pfn;
	ulong_t ppages;
	page_t *targ_pplist = NULL;
	page_t *repl_pplist = NULL;
	page_t *tmp_pplist;
	int nios = 0;
	uint_t pszc;
	struct vattr va;

	VM_STAT_ADD(segvnvmstats.fill_vp_pages[0]);

	ASSERT(szc != 0);
	ASSERT(pplist->p_szc == szc);

	/*
	 * downsize will be set to 1 only if we fail to lock pages. this will
	 * allow subsequent faults to try to relocate the page again. If we
	 * fail due to misalignment don't downsize and let the caller map the
	 * whole region with small mappings to avoid more faults into the area
	 * where we can't get large pages anyway.
	 */
	*downsize = 0;

	while (off < eoff) {
		newpp = pplist;
		ASSERT(newpp != NULL);
		ASSERT(PAGE_EXCL(newpp));
		ASSERT(!PP_ISFREE(newpp));
		/*
		 * we pass NULL for nrelocp to page_lookup_create()
		 * so that it doesn't relocate. We relocate here
		 * later only after we make sure we can lock all
		 * pages in the range we handle and they are all
		 * aligned.
		 */
		pp = page_lookup_create(vp, off, SE_SHARED, newpp, NULL, 0);
		ASSERT(pp != NULL);
		ASSERT(!PP_ISFREE(pp));
		ASSERT(pp->p_vnode == vp);
		ASSERT(pp->p_offset == off);
		if (pp == newpp) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[1]);
			page_sub(&pplist, pp);
			ASSERT(PAGE_EXCL(pp));
			ASSERT(page_iolock_assert(pp));
			page_list_concat(&io_pplist, &pp);
			off += PAGESIZE;
			continue;
		}
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[2]);
		pfn = page_pptonum(pp);
		pszc = pp->p_szc;
		if (pszc >= szc && targ_pplist == NULL && io_pplist == NULL &&
		    IS_P2ALIGNED(pfn, pages)) {
			ASSERT(repl_pplist == NULL);
			ASSERT(done_pplist == NULL);
			ASSERT(pplist == *ppplist);
			page_unlock(pp);
			page_free_replacement_page(pplist);
			page_create_putback(pages);
			*ppplist = NULL;
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[3]);
			return (1);
		}
		if (pszc >= szc) {
			page_unlock(pp);
			segvn_faultvnmpss_align_err1++;
			goto out;
		}
		ppages = page_get_pagecnt(pszc);
		if (!IS_P2ALIGNED(pfn, ppages)) {
			ASSERT(pszc > 0);
			/*
			 * sizing down to pszc won't help.
			 */
			page_unlock(pp);
			segvn_faultvnmpss_align_err2++;
			goto out;
		}
		pfn = page_pptonum(newpp);
		if (!IS_P2ALIGNED(pfn, ppages)) {
			ASSERT(pszc > 0);
			/*
			 * sizing down to pszc won't help.
			 */
			page_unlock(pp);
			segvn_faultvnmpss_align_err3++;
			goto out;
		}
		if (!PAGE_EXCL(pp)) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[4]);
			page_unlock(pp);
			*downsize = 1;
			*ret_pszc = pp->p_szc;
			goto out;
		}
		targpp = pp;
		if (io_pplist != NULL) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[5]);
			io_len = off - io_off;
			/*
			 * Some file systems like NFS don't check EOF
			 * conditions in VOP_PAGEIO(). Check it here
			 * now that pages are locked SE_EXCL. Any file
			 * truncation will wait until the pages are
			 * unlocked so no need to worry that file will
			 * be truncated after we check its size here.
			 * XXX fix NFS to remove this check.
			 */
			va.va_mask = AT_SIZE;
			if (VOP_GETATTR(vp, &va, ATTR_HINT, svd->cred) != 0) {
				VM_STAT_ADD(segvnvmstats.fill_vp_pages[6]);
				page_unlock(targpp);
				goto out;
			}
			if (btopr(va.va_size) < btopr(io_off + io_len)) {
				VM_STAT_ADD(segvnvmstats.fill_vp_pages[7]);
				*downsize = 1;
				*ret_pszc = 0;
				page_unlock(targpp);
				goto out;
			}
			io_err = VOP_PAGEIO(vp, io_pplist, io_off, io_len,
				B_READ, svd->cred);
			if (io_err) {
				VM_STAT_ADD(segvnvmstats.fill_vp_pages[8]);
				page_unlock(targpp);
				if (io_err == EDEADLK) {
					segvn_vmpss_pageio_deadlk_err++;
				}
				goto out;
			}
			nios++;
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[9]);
			while (io_pplist != NULL) {
				pp = io_pplist;
				page_sub(&io_pplist, pp);
				ASSERT(page_iolock_assert(pp));
				page_io_unlock(pp);
				pgidx = (pp->p_offset - start_off) >>
				    PAGESHIFT;
				ASSERT(pgidx < pages);
				ppa[pgidx] = pp;
				page_list_concat(&done_pplist, &pp);
			}
		}
		pp = targpp;
		ASSERT(PAGE_EXCL(pp));
		ASSERT(pp->p_szc <= pszc);
		if (pszc != 0 && !group_page_trylock(pp, SE_EXCL)) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[10]);
			page_unlock(pp);
			*downsize = 1;
			*ret_pszc = pp->p_szc;
			goto out;
		}
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[11]);
		/*
		 * page szc chould have changed before the entire group was
		 * locked. reread page szc.
		 */
		pszc = pp->p_szc;
		ppages = page_get_pagecnt(pszc);

		/* link just the roots */
		page_list_concat(&targ_pplist, &pp);
		page_sub(&pplist, newpp);
		page_list_concat(&repl_pplist, &newpp);
		off += PAGESIZE;
		while (--ppages != 0) {
			newpp = pplist;
			page_sub(&pplist, newpp);
			off += PAGESIZE;
		}
		io_off = off;
	}
	if (io_pplist != NULL) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[12]);
		io_len = eoff - io_off;
		va.va_mask = AT_SIZE;
		if (VOP_GETATTR(vp, &va, ATTR_HINT, svd->cred) != 0) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[13]);
			goto out;
		}
		if (btopr(va.va_size) < btopr(io_off + io_len)) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[14]);
			*downsize = 1;
			*ret_pszc = 0;
			goto out;
		}
		io_err = VOP_PAGEIO(vp, io_pplist, io_off, io_len,
		    B_READ, svd->cred);
		if (io_err) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[15]);
			if (io_err == EDEADLK) {
				segvn_vmpss_pageio_deadlk_err++;
			}
			goto out;
		}
		nios++;
		while (io_pplist != NULL) {
			pp = io_pplist;
			page_sub(&io_pplist, pp);
			ASSERT(page_iolock_assert(pp));
			page_io_unlock(pp);
			pgidx = (pp->p_offset - start_off) >> PAGESHIFT;
			ASSERT(pgidx < pages);
			ppa[pgidx] = pp;
		}
	}
	/*
	 * we're now bound to succeed or panic.
	 * remove pages from done_pplist. it's not needed anymore.
	 */
	while (done_pplist != NULL) {
		pp = done_pplist;
		page_sub(&done_pplist, pp);
	}
	VM_STAT_ADD(segvnvmstats.fill_vp_pages[16]);
	ASSERT(pplist == NULL);
	*ppplist = NULL;
	while (targ_pplist != NULL) {
		int ret;
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[17]);
		ASSERT(repl_pplist);
		pp = targ_pplist;
		page_sub(&targ_pplist, pp);
		pgidx = (pp->p_offset - start_off) >> PAGESHIFT;
		newpp = repl_pplist;
		page_sub(&repl_pplist, newpp);
#ifdef DEBUG
		pfn = page_pptonum(pp);
		pszc = pp->p_szc;
		ppages = page_get_pagecnt(pszc);
		ASSERT(IS_P2ALIGNED(pfn, ppages));
		pfn = page_pptonum(newpp);
		ASSERT(IS_P2ALIGNED(pfn, ppages));
		ASSERT(P2PHASE(pfn, pages) == pgidx);
#endif
		nreloc = 0;
		ret = page_relocate(&pp, &newpp, 0, 1, &nreloc, NULL);
		if (ret != 0 || nreloc == 0) {
			panic("segvn_fill_vp_pages: "
			    "page_relocate failed");
		}
		pp = newpp;
		while (nreloc-- != 0) {
			ASSERT(PAGE_EXCL(pp));
			ASSERT(pp->p_vnode == vp);
			ASSERT(pgidx ==
			    ((pp->p_offset - start_off) >> PAGESHIFT));
			ppa[pgidx++] = pp;
			pp++;
		}
	}

	if (svd->type == MAP_PRIVATE) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[18]);
		for (i = 0; i < pages; i++) {
			ASSERT(ppa[i] != NULL);
			ASSERT(PAGE_EXCL(ppa[i]));
			ASSERT(ppa[i]->p_vnode == vp);
			ASSERT(ppa[i]->p_offset ==
			    start_off + (i << PAGESHIFT));
			page_downgrade(ppa[i]);
		}
		ppa[pages] = NULL;
	} else {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[19]);
		/*
		 * the caller will still call VOP_GETPAGE() for shared segments
		 * to check FS write permissions. For private segments we map
		 * file read only anyway.  so no VOP_GETPAGE is needed.
		 */
		for (i = 0; i < pages; i++) {
			ASSERT(ppa[i] != NULL);
			ASSERT(PAGE_EXCL(ppa[i]));
			ASSERT(ppa[i]->p_vnode == vp);
			ASSERT(ppa[i]->p_offset ==
			    start_off + (i << PAGESHIFT));
			page_unlock(ppa[i]);
		}
		ppa[0] = NULL;
	}

	return (1);
out:
	/*
	 * Do the cleanup. Unlock target pages we didn't relocate. They are
	 * linked on targ_pplist by root pages. reassemble unused replacement
	 * and io pages back to pplist.
	 */
	if (io_pplist != NULL) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[20]);
		pp = io_pplist;
		do {
			ASSERT(pp->p_vnode == vp);
			ASSERT(pp->p_offset == io_off);
			ASSERT(page_iolock_assert(pp));
			page_io_unlock(pp);
			page_hashout(pp, NULL);
			io_off += PAGESIZE;
		} while ((pp = pp->p_next) != io_pplist);
		page_list_concat(&io_pplist, &pplist);
		pplist = io_pplist;
	}
	tmp_pplist = NULL;
	while (targ_pplist != NULL) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[21]);
		pp = targ_pplist;
		ASSERT(PAGE_EXCL(pp));
		page_sub(&targ_pplist, pp);

		pszc = pp->p_szc;
		ppages = page_get_pagecnt(pszc);
		ASSERT(IS_P2ALIGNED(page_pptonum(pp), ppages));

		if (pszc != 0) {
			group_page_unlock(pp);
		}
		page_unlock(pp);

		pp = repl_pplist;
		ASSERT(pp != NULL);
		ASSERT(PAGE_EXCL(pp));
		ASSERT(pp->p_szc == szc);
		page_sub(&repl_pplist, pp);

		ASSERT(IS_P2ALIGNED(page_pptonum(pp), ppages));

		/* relink replacement page */
		page_list_concat(&tmp_pplist, &pp);
		while (--ppages != 0) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[22]);
			pp++;
			ASSERT(PAGE_EXCL(pp));
			ASSERT(pp->p_szc == szc);
			page_list_concat(&tmp_pplist, &pp);
		}
	}
	if (tmp_pplist != NULL) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[23]);
		page_list_concat(&tmp_pplist, &pplist);
		pplist = tmp_pplist;
	}
	/*
	 * at this point all pages are either on done_pplist or
	 * pplist. They can't be all on done_pplist otherwise
	 * we'd've been done.
	 */
	ASSERT(pplist != NULL);
	if (nios != 0) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[24]);
		pp = pplist;
		do {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[25]);
			ASSERT(pp->p_szc == szc);
			ASSERT(PAGE_EXCL(pp));
			ASSERT(pp->p_vnode != vp);
			pp->p_szc = 0;
		} while ((pp = pp->p_next) != pplist);

		pp = done_pplist;
		do {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[26]);
			ASSERT(pp->p_szc == szc);
			ASSERT(PAGE_EXCL(pp));
			ASSERT(pp->p_vnode == vp);
			pp->p_szc = 0;
		} while ((pp = pp->p_next) != done_pplist);

		while (pplist != NULL) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[27]);
			pp = pplist;
			page_sub(&pplist, pp);
			page_free(pp, 0);
		}

		while (done_pplist != NULL) {
			VM_STAT_ADD(segvnvmstats.fill_vp_pages[28]);
			pp = done_pplist;
			page_sub(&done_pplist, pp);
			page_unlock(pp);
		}
		*ppplist = NULL;
		return (0);
	}
	ASSERT(pplist == *ppplist);
	if (io_err) {
		VM_STAT_ADD(segvnvmstats.fill_vp_pages[29]);
		/*
		 * don't downsize on io error.
		 * see if vop_getpage succeeds.
		 * pplist may still be used in this case
		 * for relocations.
		 */
		return (0);
	}
	VM_STAT_ADD(segvnvmstats.fill_vp_pages[30]);
	page_free_replacement_page(pplist);
	page_create_putback(pages);
	*ppplist = NULL;
	return (0);
}

int segvn_anypgsz = 0;

#define	SEGVN_RESTORE_SOFTLOCK(type, pages) 		\
		if ((type) == F_SOFTLOCK) {		\
			mutex_enter(&freemem_lock);	\
			availrmem += (pages);		\
			segvn_pages_locked -= (pages);	\
			svd->softlockcnt -= (pages);	\
			mutex_exit(&freemem_lock);	\
		}

#define	SEGVN_UPDATE_MODBITS(ppa, pages, rw, prot, vpprot)		\
		if (IS_VMODSORT((ppa)[0]->p_vnode)) {			\
			if ((rw) == S_WRITE) {				\
				for (i = 0; i < (pages); i++) {		\
					ASSERT((ppa)[i]->p_vnode ==	\
					    (ppa)[0]->p_vnode);		\
					hat_setmod((ppa)[i]);		\
				}					\
			} else if ((rw) != S_OTHER &&			\
			    ((prot) & (vpprot) & PROT_WRITE)) {		\
				for (i = 0; i < (pages); i++) {		\
					ASSERT((ppa)[i]->p_vnode ==	\
					    (ppa)[0]->p_vnode);		\
					if (!hat_ismod((ppa)[i])) {	\
						prot &= ~PROT_WRITE;	\
						break;			\
					}				\
				}					\
			}						\
		}

#ifdef  VM_STATS

#define	SEGVN_VMSTAT_FLTVNPAGES(idx)					\
		VM_STAT_ADD(segvnvmstats.fltvnpages[(idx)]);

#else /* VM_STATS */

#define	SEGVN_VMSTAT_FLTVNPAGES(idx)

#endif

static faultcode_t
segvn_fault_vnodepages(struct hat *hat, struct seg *seg, caddr_t lpgaddr,
    caddr_t lpgeaddr, enum fault_type type, enum seg_rw rw, caddr_t addr,
    caddr_t eaddr, int brkcow)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon_map *amp = svd->amp;
	uchar_t segtype = svd->type;
	uint_t szc = seg->s_szc;
	size_t pgsz = page_get_pagesize(szc);
	size_t maxpgsz = pgsz;
	pgcnt_t pages = btop(pgsz);
	pgcnt_t maxpages = pages;
	size_t ppasize = (pages + 1) * sizeof (page_t *);
	caddr_t a = lpgaddr;
	caddr_t	maxlpgeaddr = lpgeaddr;
	u_offset_t off = svd->offset + (uintptr_t)(a - seg->s_base);
	ulong_t aindx = svd->anon_index + seg_page(seg, a);
	struct vpage *vpage = (svd->vpage != NULL) ?
	    &svd->vpage[seg_page(seg, a)] : NULL;
	vnode_t *vp = svd->vp;
	page_t **ppa;
	uint_t	pszc;
	size_t	ppgsz;
	pgcnt_t	ppages;
	faultcode_t err = 0;
	int ierr;
	int vop_size_err = 0;
	uint_t protchk, prot, vpprot;
	ulong_t i;
	int hat_flag = (type == F_SOFTLOCK) ? HAT_LOAD_LOCK : HAT_LOAD;
	anon_sync_obj_t an_cookie;
	enum seg_rw arw;
	int alloc_failed = 0;
	int adjszc_chk;
	struct vattr va;
	int xhat = 0;
	page_t *pplist;
	pfn_t pfn;
	int physcontig;
	int upgrdfail;
	int segvn_anypgsz_vnode = 0; /* for now map vnode with 2 page sizes */

	ASSERT(szc != 0);
	ASSERT(vp != NULL);
	ASSERT(brkcow == 0 || amp != NULL);
	ASSERT(enable_mbit_wa == 0); /* no mbit simulations with large pages */
	ASSERT(!(svd->flags & MAP_NORESERVE));
	ASSERT(type != F_SOFTUNLOCK);
	ASSERT(IS_P2ALIGNED(a, maxpgsz));
	ASSERT(amp == NULL || IS_P2ALIGNED(aindx, maxpages));
	ASSERT(SEGVN_LOCK_HELD(seg->s_as, &svd->lock));
	ASSERT(seg->s_szc < NBBY * sizeof (int));
	ASSERT(type != F_SOFTLOCK || lpgeaddr - a == maxpgsz);

	VM_STAT_COND_ADD(type == F_SOFTLOCK, segvnvmstats.fltvnpages[0]);
	VM_STAT_COND_ADD(type != F_SOFTLOCK, segvnvmstats.fltvnpages[1]);

	if (svd->flags & MAP_TEXT) {
		hat_flag |= HAT_LOAD_TEXT;
	}

	if (svd->pageprot) {
		switch (rw) {
		case S_READ:
			protchk = PROT_READ;
			break;
		case S_WRITE:
			protchk = PROT_WRITE;
			break;
		case S_EXEC:
			protchk = PROT_EXEC;
			break;
		case S_OTHER:
		default:
			protchk = PROT_READ | PROT_WRITE | PROT_EXEC;
			break;
		}
	} else {
		prot = svd->prot;
		/* caller has already done segment level protection check. */
	}

	if (seg->s_as->a_hat != hat) {
		xhat = 1;
	}

	if (rw == S_WRITE && segtype == MAP_PRIVATE) {
		SEGVN_VMSTAT_FLTVNPAGES(2);
		arw = S_READ;
	} else {
		arw = rw;
	}

	ppa = kmem_alloc(ppasize, KM_SLEEP);

	VM_STAT_COND_ADD(amp != NULL, segvnvmstats.fltvnpages[3]);

	for (;;) {
		adjszc_chk = 0;
		for (; a < lpgeaddr; a += pgsz, off += pgsz, aindx += pages) {
			if (adjszc_chk) {
				while (szc < seg->s_szc) {
					uintptr_t e;
					uint_t tszc;
					tszc = segvn_anypgsz_vnode ? szc + 1 :
					    seg->s_szc;
					ppgsz = page_get_pagesize(tszc);
					if (!IS_P2ALIGNED(a, ppgsz) ||
					    ((alloc_failed >> tszc) &
						0x1)) {
						break;
					}
					SEGVN_VMSTAT_FLTVNPAGES(4);
					szc = tszc;
					pgsz = ppgsz;
					pages = btop(pgsz);
					e = P2ROUNDUP((uintptr_t)eaddr, pgsz);
					lpgeaddr = (caddr_t)e;
				}
			}

		again:
			if (IS_P2ALIGNED(a, maxpgsz) && amp != NULL) {
				ASSERT(IS_P2ALIGNED(aindx, maxpages));
				ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
				anon_array_enter(amp, aindx, &an_cookie);
				if (anon_get_ptr(amp->ahp, aindx) != NULL) {
					SEGVN_VMSTAT_FLTVNPAGES(5);
					if (anon_pages(amp->ahp, aindx,
					    maxpages) != maxpages) {
						panic("segvn_fault_vnodepages:"
						    " empty anon slots\n");
					}
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
					err = segvn_fault_anonpages(hat, seg,
					    a, a + maxpgsz, type, rw,
					    MAX(a, addr),
					    MIN(a + maxpgsz, eaddr), brkcow);
					if (err != 0) {
						SEGVN_VMSTAT_FLTVNPAGES(6);
						goto out;
					}
					if (szc < seg->s_szc) {
						szc = seg->s_szc;
						pgsz = maxpgsz;
						pages = maxpages;
						lpgeaddr = maxlpgeaddr;
					}
					goto next;
				} else if (anon_pages(amp->ahp, aindx,
				    maxpages)) {
					panic("segvn_fault_vnodepages:"
						" non empty anon slots\n");
				} else {
					SEGVN_VMSTAT_FLTVNPAGES(7);
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				}
			}
			ASSERT(!brkcow || IS_P2ALIGNED(a, maxpgsz));

			if (svd->pageprot != 0 && IS_P2ALIGNED(a, maxpgsz)) {
				ASSERT(vpage != NULL);
				prot = VPP_PROT(vpage);
				ASSERT(sameprot(seg, a, maxpgsz));
				if ((prot & protchk) == 0) {
					SEGVN_VMSTAT_FLTVNPAGES(8);
					err = FC_PROT;
					goto out;
				}
			}
			if (type == F_SOFTLOCK) {
				mutex_enter(&freemem_lock);
				if (availrmem < tune.t_minarmem + pages) {
					mutex_exit(&freemem_lock);
					err = FC_MAKE_ERR(ENOMEM);
					goto out;
				} else {
					availrmem -= pages;
					segvn_pages_locked += pages;
					svd->softlockcnt += pages;
				}
				mutex_exit(&freemem_lock);
			}

			pplist = NULL;
			physcontig = 0;
			ppa[0] = NULL;
			if (!brkcow && szc &&
			    !page_exists_physcontig(vp, off, szc,
				segtype == MAP_PRIVATE ? ppa : NULL)) {
				SEGVN_VMSTAT_FLTVNPAGES(9);
				if (page_alloc_pages(vp, seg, a, &pplist, NULL,
				    szc, 0) && type != F_SOFTLOCK) {
					SEGVN_VMSTAT_FLTVNPAGES(10);
					pszc = 0;
					ierr = -1;
					alloc_failed |= (1 << szc);
					break;
				}
				if (pplist != NULL &&
				    vp->v_mpssdata == SEGVN_PAGEIO) {
					int downsize;
					SEGVN_VMSTAT_FLTVNPAGES(11);
					physcontig = segvn_fill_vp_pages(svd,
					    vp, off, szc, ppa, &pplist,
					    &pszc, &downsize);
					ASSERT(!physcontig || pplist == NULL);
					if (!physcontig && downsize &&
					    type != F_SOFTLOCK) {
						ASSERT(pplist == NULL);
						SEGVN_VMSTAT_FLTVNPAGES(12);
						ierr = -1;
						break;
					}
					ASSERT(!physcontig ||
					    segtype == MAP_PRIVATE ||
					    ppa[0] == NULL);
					if (physcontig && ppa[0] == NULL) {
						physcontig = 0;
					}
				}
			} else if (!brkcow && szc && ppa[0] != NULL) {
				SEGVN_VMSTAT_FLTVNPAGES(13);
				ASSERT(segtype == MAP_PRIVATE);
				physcontig = 1;
			}

			if (!physcontig) {
				SEGVN_VMSTAT_FLTVNPAGES(14);
				ppa[0] = NULL;
				ierr = VOP_GETPAGE(vp, (offset_t)off, pgsz,
				    &vpprot, ppa, pgsz, seg, a, arw,
				    svd->cred);
				if (segtype == MAP_PRIVATE) {
					SEGVN_VMSTAT_FLTVNPAGES(15);
					vpprot &= ~PROT_WRITE;
				}
			} else {
				ASSERT(segtype == MAP_PRIVATE);
				SEGVN_VMSTAT_FLTVNPAGES(16);
				vpprot = PROT_ALL & ~PROT_WRITE;
				ierr = 0;
			}

			if (ierr != 0) {
				SEGVN_VMSTAT_FLTVNPAGES(17);
				if (pplist != NULL) {
					SEGVN_VMSTAT_FLTVNPAGES(18);
					page_free_replacement_page(pplist);
					page_create_putback(pages);
				}
				SEGVN_RESTORE_SOFTLOCK(type, pages);
				if (a + pgsz <= eaddr) {
					SEGVN_VMSTAT_FLTVNPAGES(19);
					err = FC_MAKE_ERR(ierr);
					goto out;
				}
				va.va_mask = AT_SIZE;
				if (VOP_GETATTR(vp, &va, 0, svd->cred) != 0) {
					SEGVN_VMSTAT_FLTVNPAGES(20);
					err = FC_MAKE_ERR(EIO);
					goto out;
				}
				if (btopr(va.va_size) >= btopr(off + pgsz)) {
					SEGVN_VMSTAT_FLTVNPAGES(21);
					err = FC_MAKE_ERR(ierr);
					goto out;
				}
				if (btopr(va.va_size) <
				    btopr(off + (eaddr - a))) {
					SEGVN_VMSTAT_FLTVNPAGES(22);
					err = FC_MAKE_ERR(ierr);
					goto out;
				}
				if (brkcow || type == F_SOFTLOCK) {
					/* can't reduce map area */
					SEGVN_VMSTAT_FLTVNPAGES(23);
					vop_size_err = 1;
					goto out;
				}
				SEGVN_VMSTAT_FLTVNPAGES(24);
				ASSERT(szc != 0);
				pszc = 0;
				ierr = -1;
				break;
			}

			if (amp != NULL) {
				ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
				anon_array_enter(amp, aindx, &an_cookie);
			}
			if (amp != NULL &&
			    anon_get_ptr(amp->ahp, aindx) != NULL) {
				ulong_t taindx = P2ALIGN(aindx, maxpages);

				SEGVN_VMSTAT_FLTVNPAGES(25);
				if (anon_pages(amp->ahp, taindx, maxpages) !=
				    maxpages) {
					panic("segvn_fault_vnodepages:"
					    " empty anon slots\n");
				}
				for (i = 0; i < pages; i++) {
					page_unlock(ppa[i]);
				}
				anon_array_exit(&an_cookie);
				ANON_LOCK_EXIT(&amp->a_rwlock);
				if (pplist != NULL) {
					page_free_replacement_page(pplist);
					page_create_putback(pages);
				}
				SEGVN_RESTORE_SOFTLOCK(type, pages);
				if (szc < seg->s_szc) {
					SEGVN_VMSTAT_FLTVNPAGES(26);
					/*
					 * For private segments SOFTLOCK
					 * either always breaks cow (any rw
					 * type except S_READ_NOCOW) or
					 * address space is locked as writer
					 * (S_READ_NOCOW case) and anon slots
					 * can't show up on second check.
					 * Therefore if we are here for
					 * SOFTLOCK case it must be a cow
					 * break but cow break never reduces
					 * szc. Thus the assert below.
					 */
					ASSERT(!brkcow && type != F_SOFTLOCK);
					pszc = seg->s_szc;
					ierr = -2;
					break;
				}
				ASSERT(IS_P2ALIGNED(a, maxpgsz));
				goto again;
			}
#ifdef DEBUG
			if (amp != NULL) {
				ulong_t taindx = P2ALIGN(aindx, maxpages);
				ASSERT(!anon_pages(amp->ahp, taindx, maxpages));
			}
#endif /* DEBUG */

			if (brkcow) {
				ASSERT(amp != NULL);
				ASSERT(pplist == NULL);
				ASSERT(szc == seg->s_szc);
				ASSERT(IS_P2ALIGNED(a, maxpgsz));
				ASSERT(IS_P2ALIGNED(aindx, maxpages));
				SEGVN_VMSTAT_FLTVNPAGES(27);
				ierr = anon_map_privatepages(amp, aindx, szc,
				    seg, a, prot, ppa, vpage, segvn_anypgsz,
				    svd->cred);
				if (ierr != 0) {
					SEGVN_VMSTAT_FLTVNPAGES(28);
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
					SEGVN_RESTORE_SOFTLOCK(type, pages);
					err = FC_MAKE_ERR(ierr);
					goto out;
				}

				ASSERT(!IS_VMODSORT(ppa[0]->p_vnode));
				/*
				 * p_szc can't be changed for locked
				 * swapfs pages.
				 */
				hat_memload_array(hat, a, pgsz, ppa, prot,
				    hat_flag);

				if (!(hat_flag & HAT_LOAD_LOCK)) {
					SEGVN_VMSTAT_FLTVNPAGES(29);
					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
				}
				anon_array_exit(&an_cookie);
				ANON_LOCK_EXIT(&amp->a_rwlock);
				goto next;
			}

			pfn = page_pptonum(ppa[0]);
			/*
			 * hat_page_demote() needs an EXCl lock on one of
			 * constituent page_t's and it decreases root's p_szc
			 * last. This means if root's p_szc is equal szc and
			 * all its constituent pages are locked
			 * hat_page_demote() that could have changed p_szc to
			 * szc is already done and no new have page_demote()
			 * can start for this large page.
			 */

			/*
			 * we need to make sure same mapping size is used for
			 * the same address range if there's a possibility the
			 * adddress is already mapped because hat layer panics
			 * when translation is loaded for the range already
			 * mapped with a different page size.  We achieve it
			 * by always using largest page size possible subject
			 * to the constraints of page size, segment page size
			 * and page alignment.  Since mappings are invalidated
			 * when those constraints change and make it
			 * impossible to use previously used mapping size no
			 * mapping size conflicts should happen.
			 */

		chkszc:
			if ((pszc = ppa[0]->p_szc) == szc &&
			    IS_P2ALIGNED(pfn, pages)) {

				SEGVN_VMSTAT_FLTVNPAGES(30);
#ifdef DEBUG
				for (i = 0; i < pages; i++) {
					ASSERT(PAGE_LOCKED(ppa[i]));
					ASSERT(!PP_ISFREE(ppa[i]));
					ASSERT(page_pptonum(ppa[i]) ==
					    pfn + i);
					ASSERT(ppa[i]->p_szc == szc);
					ASSERT(ppa[i]->p_vnode == vp);
					ASSERT(ppa[i]->p_offset ==
					    off + (i << PAGESHIFT));
				}
#endif /* DEBUG */
				/*
				 * All pages are of szc we need and they are
				 * all locked so they can't change szc. load
				 * translations.
				 *
				 * if page got promoted since last check
				 * we don't need pplist.
				 */
				if (pplist != NULL) {
					page_free_replacement_page(pplist);
					page_create_putback(pages);
				}
				if (PP_ISMIGRATE(ppa[0])) {
					page_migrate(seg, a, ppa, pages);
				}
				SEGVN_UPDATE_MODBITS(ppa, pages, rw,
				    prot, vpprot);
				if (!xhat) {
					hat_memload_array(hat, a, pgsz, ppa,
					    prot & vpprot, hat_flag);
				} else {
					/*
					 * avoid large xhat mappings to FS
					 * pages so that hat_page_demote()
					 * doesn't need to check for xhat
					 * large mappings.
					 */
					for (i = 0; i < pages; i++) {
						hat_memload(hat,
						    a + (i << PAGESHIFT),
						    ppa[i], prot & vpprot,
						    hat_flag);
					}
				}

				if (!(hat_flag & HAT_LOAD_LOCK)) {
					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
				}
				if (amp != NULL) {
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				}
				goto next;
			}

			/*
			 * See if upsize is possible.
			 */
			if (pszc > szc && szc < seg->s_szc &&
			    (segvn_anypgsz_vnode || pszc >= seg->s_szc)) {
				pgcnt_t aphase;
				uint_t pszc1 = MIN(pszc, seg->s_szc);
				ppgsz = page_get_pagesize(pszc1);
				ppages = btop(ppgsz);
				aphase = btop(P2PHASE((uintptr_t)a, ppgsz));

				ASSERT(type != F_SOFTLOCK);

				SEGVN_VMSTAT_FLTVNPAGES(31);
				if (aphase != P2PHASE(pfn, ppages)) {
					segvn_faultvnmpss_align_err4++;
				} else {
					SEGVN_VMSTAT_FLTVNPAGES(32);
					if (pplist != NULL) {
						page_t *pl = pplist;
						page_free_replacement_page(pl);
						page_create_putback(pages);
					}
					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
					if (amp != NULL) {
						anon_array_exit(&an_cookie);
						ANON_LOCK_EXIT(&amp->a_rwlock);
					}
					pszc = pszc1;
					ierr = -2;
					break;
				}
			}

			/*
			 * check if we should use smallest mapping size.
			 */
			upgrdfail = 0;
			if (szc == 0 || xhat ||
			    (pszc >= szc &&
			    !IS_P2ALIGNED(pfn, pages)) ||
			    (pszc < szc &&
			    !segvn_full_szcpages(ppa, szc, &upgrdfail,
				&pszc))) {

				if (upgrdfail && type != F_SOFTLOCK) {
					/*
					 * segvn_full_szcpages failed to lock
					 * all pages EXCL. Size down.
					 */
					ASSERT(pszc < szc);

					SEGVN_VMSTAT_FLTVNPAGES(33);

					if (pplist != NULL) {
						page_t *pl = pplist;
						page_free_replacement_page(pl);
						page_create_putback(pages);
					}

					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
					if (amp != NULL) {
						anon_array_exit(&an_cookie);
						ANON_LOCK_EXIT(&amp->a_rwlock);
					}
					ierr = -1;
					break;
				}
				if (szc != 0 && !xhat) {
					segvn_faultvnmpss_align_err5++;
				}
				SEGVN_VMSTAT_FLTVNPAGES(34);
				if (pplist != NULL) {
					page_free_replacement_page(pplist);
					page_create_putback(pages);
				}
				SEGVN_UPDATE_MODBITS(ppa, pages, rw,
				    prot, vpprot);
				for (i = 0; i < pages; i++) {
					hat_memload(hat, a + (i << PAGESHIFT),
					    ppa[i], prot & vpprot, hat_flag);
				}
				if (!(hat_flag & HAT_LOAD_LOCK)) {
					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
				}
				if (amp != NULL) {
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				}
				goto next;
			}

			if (pszc == szc) {
				/*
				 * segvn_full_szcpages() upgraded pages szc.
				 */
				ASSERT(pszc == ppa[0]->p_szc);
				ASSERT(IS_P2ALIGNED(pfn, pages));
				goto chkszc;
			}

			if (pszc > szc) {
				kmutex_t *szcmtx;
				SEGVN_VMSTAT_FLTVNPAGES(35);
				/*
				 * p_szc of ppa[0] can change since we haven't
				 * locked all constituent pages. Call
				 * page_lock_szc() to prevent szc changes.
				 * This should be a rare case that happens when
				 * multiple segments use a different page size
				 * to map the same file offsets.
				 */
				szcmtx = page_szc_lock(ppa[0]);
				pszc = ppa[0]->p_szc;
				ASSERT(szcmtx != NULL || pszc == 0);
				ASSERT(ppa[0]->p_szc <= pszc);
				if (pszc <= szc) {
					SEGVN_VMSTAT_FLTVNPAGES(36);
					if (szcmtx != NULL) {
						mutex_exit(szcmtx);
					}
					goto chkszc;
				}
				if (pplist != NULL) {
					/*
					 * page got promoted since last check.
					 * we don't need preaalocated large
					 * page.
					 */
					SEGVN_VMSTAT_FLTVNPAGES(37);
					page_free_replacement_page(pplist);
					page_create_putback(pages);
				}
				SEGVN_UPDATE_MODBITS(ppa, pages, rw,
				    prot, vpprot);
				hat_memload_array(hat, a, pgsz, ppa,
				    prot & vpprot, hat_flag);
				mutex_exit(szcmtx);
				if (!(hat_flag & HAT_LOAD_LOCK)) {
					for (i = 0; i < pages; i++) {
						page_unlock(ppa[i]);
					}
				}
				if (amp != NULL) {
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				}
				goto next;
			}

			/*
			 * if page got demoted since last check
			 * we could have not allocated larger page.
			 * allocate now.
			 */
			if (pplist == NULL &&
			    page_alloc_pages(vp, seg, a, &pplist, NULL,
				szc, 0) && type != F_SOFTLOCK) {
				SEGVN_VMSTAT_FLTVNPAGES(38);
				for (i = 0; i < pages; i++) {
					page_unlock(ppa[i]);
				}
				if (amp != NULL) {
					anon_array_exit(&an_cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				}
				ierr = -1;
				alloc_failed |= (1 << szc);
				break;
			}

			SEGVN_VMSTAT_FLTVNPAGES(39);

			if (pplist != NULL) {
				segvn_relocate_pages(ppa, pplist);
#ifdef DEBUG
			} else {
				ASSERT(type == F_SOFTLOCK);
				SEGVN_VMSTAT_FLTVNPAGES(40);
#endif /* DEBUG */
			}

			SEGVN_UPDATE_MODBITS(ppa, pages, rw, prot, vpprot);

			if (pplist == NULL && segvn_anypgsz_vnode == 0) {
				ASSERT(type == F_SOFTLOCK);
				for (i = 0; i < pages; i++) {
					ASSERT(ppa[i]->p_szc < szc);
					hat_memload(hat, a + (i << PAGESHIFT),
					    ppa[i], prot & vpprot, hat_flag);
				}
			} else {
				ASSERT(pplist != NULL || type == F_SOFTLOCK);
				hat_memload_array(hat, a, pgsz, ppa,
				    prot & vpprot, hat_flag);
			}
			if (!(hat_flag & HAT_LOAD_LOCK)) {
				for (i = 0; i < pages; i++) {
					ASSERT(PAGE_SHARED(ppa[i]));
					page_unlock(ppa[i]);
				}
			}
			if (amp != NULL) {
				anon_array_exit(&an_cookie);
				ANON_LOCK_EXIT(&amp->a_rwlock);
			}

		next:
			if (vpage != NULL) {
				vpage += pages;
			}
			adjszc_chk = 1;
		}
		if (a == lpgeaddr)
			break;
		ASSERT(a < lpgeaddr);

		ASSERT(!brkcow && type != F_SOFTLOCK);

		/*
		 * ierr == -1 means we failed to map with a large page.
		 * (either due to allocation/relocation failures or
		 * misalignment with other mappings to this file.
		 *
		 * ierr == -2 means some other thread allocated a large page
		 * after we gave up tp map with a large page.  retry with
		 * larger mapping.
		 */
		ASSERT(ierr == -1 || ierr == -2);
		ASSERT(ierr == -2 || szc != 0);
		ASSERT(ierr == -1 || szc < seg->s_szc);
		if (ierr == -2) {
			SEGVN_VMSTAT_FLTVNPAGES(41);
			ASSERT(pszc > szc && pszc <= seg->s_szc);
			szc = pszc;
		} else if (segvn_anypgsz_vnode) {
			SEGVN_VMSTAT_FLTVNPAGES(42);
			szc--;
		} else {
			SEGVN_VMSTAT_FLTVNPAGES(43);
			ASSERT(pszc < szc);
			/*
			 * other process created pszc large page.
			 * but we still have to drop to 0 szc.
			 */
			szc = 0;
		}

		pgsz = page_get_pagesize(szc);
		pages = btop(pgsz);
		if (ierr == -2) {
			/*
			 * Size up case. Note lpgaddr may only be needed for
			 * softlock case so we don't adjust it here.
			 */
			a = (caddr_t)P2ALIGN((uintptr_t)a, pgsz);
			ASSERT(a >= lpgaddr);
			lpgeaddr = (caddr_t)P2ROUNDUP((uintptr_t)eaddr, pgsz);
			off = svd->offset + (uintptr_t)(a - seg->s_base);
			aindx = svd->anon_index + seg_page(seg, a);
			vpage = (svd->vpage != NULL) ?
			    &svd->vpage[seg_page(seg, a)] : NULL;
		} else {
			/*
			 * Size down case. Note lpgaddr may only be needed for
			 * softlock case so we don't adjust it here.
			 */
			ASSERT(IS_P2ALIGNED(a, pgsz));
			ASSERT(IS_P2ALIGNED(lpgeaddr, pgsz));
			lpgeaddr = (caddr_t)P2ROUNDUP((uintptr_t)eaddr, pgsz);
			ASSERT(a < lpgeaddr);
			if (a < addr) {
				SEGVN_VMSTAT_FLTVNPAGES(44);
				/*
				 * The beginning of the large page region can
				 * be pulled to the right to make a smaller
				 * region. We haven't yet faulted a single
				 * page.
				 */
				a = (caddr_t)P2ALIGN((uintptr_t)addr, pgsz);
				ASSERT(a >= lpgaddr);
				off = svd->offset +
				    (uintptr_t)(a - seg->s_base);
				aindx = svd->anon_index + seg_page(seg, a);
				vpage = (svd->vpage != NULL) ?
				    &svd->vpage[seg_page(seg, a)] : NULL;
			}
		}
	}
out:
	kmem_free(ppa, ppasize);
	if (!err && !vop_size_err) {
		SEGVN_VMSTAT_FLTVNPAGES(45);
		return (0);
	}
	if (type == F_SOFTLOCK && a > lpgaddr) {
		SEGVN_VMSTAT_FLTVNPAGES(46);
		segvn_softunlock(seg, lpgaddr, a - lpgaddr, S_OTHER);
	}
	if (!vop_size_err) {
		SEGVN_VMSTAT_FLTVNPAGES(47);
		return (err);
	}
	ASSERT(brkcow || type == F_SOFTLOCK);
	/*
	 * Large page end is mapped beyond the end of file and it's a cow
	 * fault or softlock so we can't reduce the map area.  For now just
	 * demote the segment. This should really only happen if the end of
	 * the file changed after the mapping was established since when large
	 * page segments are created we make sure they don't extend beyond the
	 * end of the file.
	 */
	SEGVN_VMSTAT_FLTVNPAGES(48);

	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);
	err = 0;
	if (seg->s_szc != 0) {
		segvn_fltvnpages_clrszc_cnt++;
		ASSERT(svd->softlockcnt == 0);
		err = segvn_clrszc(seg);
		if (err != 0) {
			segvn_fltvnpages_clrszc_err++;
		}
	}
	ASSERT(err || seg->s_szc == 0);
	SEGVN_LOCK_DOWNGRADE(seg->s_as, &svd->lock);
	/* segvn_fault will do its job as if szc had been zero to begin with */
	return (err == 0 ? IE_RETRY : FC_MAKE_ERR(err));
}

/*
 * This routine will attempt to fault in one large page.
 * it will use smaller pages if that fails.
 * It should only be called for pure anonymous segments.
 */
static faultcode_t
segvn_fault_anonpages(struct hat *hat, struct seg *seg, caddr_t lpgaddr,
    caddr_t lpgeaddr, enum fault_type type, enum seg_rw rw, caddr_t addr,
    caddr_t eaddr, int brkcow)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon_map *amp = svd->amp;
	uchar_t segtype = svd->type;
	uint_t szc = seg->s_szc;
	size_t pgsz = page_get_pagesize(szc);
	size_t maxpgsz = pgsz;
	pgcnt_t pages = btop(pgsz);
	size_t ppasize = pages * sizeof (page_t *);
	caddr_t a = lpgaddr;
	ulong_t aindx = svd->anon_index + seg_page(seg, a);
	struct vpage *vpage = (svd->vpage != NULL) ?
	    &svd->vpage[seg_page(seg, a)] : NULL;
	page_t **ppa;
	uint_t	ppa_szc;
	faultcode_t err;
	int ierr;
	uint_t protchk, prot, vpprot;
	int i;
	int hat_flag = (type == F_SOFTLOCK) ? HAT_LOAD_LOCK : HAT_LOAD;
	anon_sync_obj_t cookie;

	ASSERT(szc != 0);
	ASSERT(amp != NULL);
	ASSERT(enable_mbit_wa == 0); /* no mbit simulations with large pages */
	ASSERT(!(svd->flags & MAP_NORESERVE));
	ASSERT(type != F_SOFTUNLOCK);
	ASSERT(segtype == MAP_PRIVATE);
	ASSERT(IS_P2ALIGNED(a, maxpgsz));

	ASSERT(SEGVN_LOCK_HELD(seg->s_as, &svd->lock));

	VM_STAT_COND_ADD(type == F_SOFTLOCK, segvnvmstats.fltanpages[0]);
	VM_STAT_COND_ADD(type != F_SOFTLOCK, segvnvmstats.fltanpages[1]);

	if (svd->flags & MAP_TEXT) {
		hat_flag |= HAT_LOAD_TEXT;
	}

	if (svd->pageprot) {
		switch (rw) {
		case S_READ:
			protchk = PROT_READ;
			break;
		case S_WRITE:
			protchk = PROT_WRITE;
			break;
		case S_EXEC:
			protchk = PROT_EXEC;
			break;
		case S_OTHER:
		default:
			protchk = PROT_READ | PROT_WRITE | PROT_EXEC;
			break;
		}
		VM_STAT_ADD(segvnvmstats.fltanpages[2]);
	} else {
		prot = svd->prot;
		/* caller has already done segment level protection check. */
	}

	ppa = kmem_alloc(ppasize, KM_SLEEP);
	ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
	for (;;) {
		for (; a < lpgeaddr; a += pgsz, aindx += pages) {
			if (svd->pageprot != 0 && IS_P2ALIGNED(a, maxpgsz)) {
				VM_STAT_ADD(segvnvmstats.fltanpages[3]);
				ASSERT(vpage != NULL);
				prot = VPP_PROT(vpage);
				ASSERT(sameprot(seg, a, maxpgsz));
				if ((prot & protchk) == 0) {
					err = FC_PROT;
					goto error;
				}
			}
			if (type == F_SOFTLOCK) {
				mutex_enter(&freemem_lock);
				if (availrmem < tune.t_minarmem + pages) {
					mutex_exit(&freemem_lock);
					err = FC_MAKE_ERR(ENOMEM);
					goto error;
				} else {
					availrmem -= pages;
					segvn_pages_locked += pages;
					svd->softlockcnt += pages;
				}
				mutex_exit(&freemem_lock);
			}
			anon_array_enter(amp, aindx, &cookie);
			ppa_szc = (uint_t)-1;
			ierr = anon_map_getpages(amp, aindx, szc, seg, a,
				prot, &vpprot, ppa, &ppa_szc, vpage, rw, brkcow,
				segvn_anypgsz, svd->cred);
			if (ierr != 0) {
				anon_array_exit(&cookie);
				VM_STAT_ADD(segvnvmstats.fltanpages[4]);
				if (type == F_SOFTLOCK) {
					VM_STAT_ADD(segvnvmstats.fltanpages[5]);
					mutex_enter(&freemem_lock);
					availrmem += pages;
					segvn_pages_locked -= pages;
					svd->softlockcnt -= pages;
					mutex_exit(&freemem_lock);
				}
				if (ierr > 0) {
					VM_STAT_ADD(segvnvmstats.fltanpages[6]);
					err = FC_MAKE_ERR(ierr);
					goto error;
				}
				break;
			}

			ASSERT(!IS_VMODSORT(ppa[0]->p_vnode));

			/*
			 * Handle pages that have been marked for migration
			 */
			if (lgrp_optimizations())
				page_migrate(seg, a, ppa, pages);

			hat_memload_array(hat, a, pgsz, ppa,
			    prot & vpprot, hat_flag);

			if (hat_flag & HAT_LOAD_LOCK) {
				VM_STAT_ADD(segvnvmstats.fltanpages[7]);
			} else {
				VM_STAT_ADD(segvnvmstats.fltanpages[8]);
				for (i = 0; i < pages; i++)
					page_unlock(ppa[i]);
			}
			if (vpage != NULL)
				vpage += pages;

			anon_array_exit(&cookie);
		}
		if (a == lpgeaddr)
			break;
		ASSERT(a < lpgeaddr);
		/*
		 * ierr == -1 means we failed to allocate a large page.
		 * so do a size down operation.
		 *
		 * ierr == -2 means some other process that privately shares
		 * pages with this process has allocated a larger page and we
		 * need to retry with larger pages. So do a size up
		 * operation. This relies on the fact that large pages are
		 * never partially shared i.e. if we share any constituent
		 * page of a large page with another process we must share the
		 * entire large page. Note this cannot happen for SOFTLOCK
		 * case, unless current address (a) is at the beginning of the
		 * next page size boundary because the other process couldn't
		 * have relocated locked pages.
		 */
		ASSERT(ierr == -1 || ierr == -2);
		if (segvn_anypgsz) {
			ASSERT(ierr == -2 || szc != 0);
			ASSERT(ierr == -1 || szc < seg->s_szc);
			szc = (ierr == -1) ? szc - 1 : szc + 1;
		} else {
			/*
			 * For non COW faults and segvn_anypgsz == 0
			 * we need to be careful not to loop forever
			 * if existing page is found with szc other
			 * than 0 or seg->s_szc. This could be due
			 * to page relocations on behalf of DR or
			 * more likely large page creation. For this
			 * case simply re-size to existing page's szc
			 * if returned by anon_map_getpages().
			 */
			if (ppa_szc == (uint_t)-1) {
				szc = (ierr == -1) ? 0 : seg->s_szc;
			} else {
				ASSERT(ppa_szc <= seg->s_szc);
				ASSERT(ierr == -2 || ppa_szc < szc);
				ASSERT(ierr == -1 || ppa_szc > szc);
				szc = ppa_szc;
			}
		}

		pgsz = page_get_pagesize(szc);
		pages = btop(pgsz);
		ASSERT(type != F_SOFTLOCK || ierr == -1 ||
		    (IS_P2ALIGNED(a, pgsz) && IS_P2ALIGNED(lpgeaddr, pgsz)));
		if (type == F_SOFTLOCK) {
			/*
			 * For softlocks we cannot reduce the fault area
			 * (calculated based on the largest page size for this
			 * segment) for size down and a is already next
			 * page size aligned as assertted above for size
			 * ups. Therefore just continue in case of softlock.
			 */
			VM_STAT_ADD(segvnvmstats.fltanpages[9]);
			continue; /* keep lint happy */
		} else if (ierr == -2) {

			/*
			 * Size up case. Note lpgaddr may only be needed for
			 * softlock case so we don't adjust it here.
			 */
			VM_STAT_ADD(segvnvmstats.fltanpages[10]);
			a = (caddr_t)P2ALIGN((uintptr_t)a, pgsz);
			ASSERT(a >= lpgaddr);
			lpgeaddr = (caddr_t)P2ROUNDUP((uintptr_t)eaddr, pgsz);
			aindx = svd->anon_index + seg_page(seg, a);
			vpage = (svd->vpage != NULL) ?
			    &svd->vpage[seg_page(seg, a)] : NULL;
		} else {
			/*
			 * Size down case. Note lpgaddr may only be needed for
			 * softlock case so we don't adjust it here.
			 */
			VM_STAT_ADD(segvnvmstats.fltanpages[11]);
			ASSERT(IS_P2ALIGNED(a, pgsz));
			ASSERT(IS_P2ALIGNED(lpgeaddr, pgsz));
			lpgeaddr = (caddr_t)P2ROUNDUP((uintptr_t)eaddr, pgsz);
			ASSERT(a < lpgeaddr);
			if (a < addr) {
				/*
				 * The beginning of the large page region can
				 * be pulled to the right to make a smaller
				 * region. We haven't yet faulted a single
				 * page.
				 */
				VM_STAT_ADD(segvnvmstats.fltanpages[12]);
				a = (caddr_t)P2ALIGN((uintptr_t)addr, pgsz);
				ASSERT(a >= lpgaddr);
				aindx = svd->anon_index + seg_page(seg, a);
				vpage = (svd->vpage != NULL) ?
				    &svd->vpage[seg_page(seg, a)] : NULL;
			}
		}
	}
	VM_STAT_ADD(segvnvmstats.fltanpages[13]);
	ANON_LOCK_EXIT(&amp->a_rwlock);
	kmem_free(ppa, ppasize);
	return (0);
error:
	VM_STAT_ADD(segvnvmstats.fltanpages[14]);
	ANON_LOCK_EXIT(&amp->a_rwlock);
	kmem_free(ppa, ppasize);
	if (type == F_SOFTLOCK && a > lpgaddr) {
		VM_STAT_ADD(segvnvmstats.fltanpages[15]);
		segvn_softunlock(seg, lpgaddr, a - lpgaddr, S_OTHER);
	}
	return (err);
}

int fltadvice = 1;	/* set to free behind pages for sequential access */

/*
 * This routine is called via a machine specific fault handling routine.
 * It is also called by software routines wishing to lock or unlock
 * a range of addresses.
 *
 * Here is the basic algorithm:
 *	If unlocking
 *		Call segvn_softunlock
 *		Return
 *	endif
 *	Checking and set up work
 *	If we will need some non-anonymous pages
 *		Call VOP_GETPAGE over the range of non-anonymous pages
 *	endif
 *	Loop over all addresses requested
 *		Call segvn_faultpage passing in page list
 *		    to load up translations and handle anonymous pages
 *	endloop
 *	Load up translation to any additional pages in page list not
 *	    already handled that fit into this segment
 */
static faultcode_t
segvn_fault(struct hat *hat, struct seg *seg, caddr_t addr, size_t len,
    enum fault_type type, enum seg_rw rw)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	page_t **plp, **ppp, *pp;
	u_offset_t off;
	caddr_t a;
	struct vpage *vpage;
	uint_t vpprot, prot;
	int err;
	page_t *pl[PVN_GETPAGE_NUM + 1];
	size_t plsz, pl_alloc_sz;
	size_t page;
	ulong_t anon_index;
	struct anon_map *amp;
	int dogetpage = 0;
	caddr_t	lpgaddr, lpgeaddr;
	size_t pgsz;
	anon_sync_obj_t cookie;
	int brkcow = BREAK_COW_SHARE(rw, type, svd->type);

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	/*
	 * First handle the easy stuff
	 */
	if (type == F_SOFTUNLOCK) {
		if (rw == S_READ_NOCOW) {
			rw = S_READ;
			ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));
		}
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
		pgsz = (seg->s_szc == 0) ? PAGESIZE :
		    page_get_pagesize(seg->s_szc);
		VM_STAT_COND_ADD(pgsz > PAGESIZE, segvnvmstats.fltanpages[16]);
		CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr, lpgeaddr);
		segvn_softunlock(seg, lpgaddr, lpgeaddr - lpgaddr, rw);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (0);
	}

top:
	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);

	/*
	 * If we have the same protections for the entire segment,
	 * insure that the access being attempted is legitimate.
	 */

	if (svd->pageprot == 0) {
		uint_t protchk;

		switch (rw) {
		case S_READ:
		case S_READ_NOCOW:
			protchk = PROT_READ;
			break;
		case S_WRITE:
			protchk = PROT_WRITE;
			break;
		case S_EXEC:
			protchk = PROT_EXEC;
			break;
		case S_OTHER:
		default:
			protchk = PROT_READ | PROT_WRITE | PROT_EXEC;
			break;
		}

		if ((svd->prot & protchk) == 0) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (FC_PROT);	/* illegal access type */
		}
	}

	/*
	 * We can't allow the long term use of softlocks for vmpss segments,
	 * because in some file truncation cases we should be able to demote
	 * the segment, which requires that there are no softlocks.  The
	 * only case where it's ok to allow a SOFTLOCK fault against a vmpss
	 * segment is S_READ_NOCOW, where the caller holds the address space
	 * locked as writer and calls softunlock before dropping the as lock.
	 * S_READ_NOCOW is used by /proc to read memory from another user.
	 *
	 * Another deadlock between SOFTLOCK and file truncation can happen
	 * because segvn_fault_vnodepages() calls the FS one pagesize at
	 * a time. A second VOP_GETPAGE() call by segvn_fault_vnodepages()
	 * can cause a deadlock because the first set of page_t's remain
	 * locked SE_SHARED.  To avoid this, we demote segments on a first
	 * SOFTLOCK if they have a length greater than the segment's
	 * page size.
	 *
	 * So for now, we only avoid demoting a segment on a SOFTLOCK when
	 * the access type is S_READ_NOCOW and the fault length is less than
	 * or equal to the segment's page size. While this is quite restrictive,
	 * it should be the most common case of SOFTLOCK against a vmpss
	 * segment.
	 *
	 * For S_READ_NOCOW, it's safe not to do a copy on write because the
	 * caller makes sure no COW will be caused by another thread for a
	 * softlocked page.
	 */
	if (type == F_SOFTLOCK && svd->vp != NULL && seg->s_szc != 0) {
		int demote = 0;

		if (rw != S_READ_NOCOW) {
			demote = 1;
		}
		if (!demote && len > PAGESIZE) {
			pgsz = page_get_pagesize(seg->s_szc);
			CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr,
			    lpgeaddr);
			if (lpgeaddr - lpgaddr > pgsz) {
				demote = 1;
			}
		}

		ASSERT(demote || AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));

		if (demote) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);
			if (seg->s_szc != 0) {
				segvn_vmpss_clrszc_cnt++;
				ASSERT(svd->softlockcnt == 0);
				err = segvn_clrszc(seg);
				if (err) {
					segvn_vmpss_clrszc_err++;
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (FC_MAKE_ERR(err));
				}
			}
			ASSERT(seg->s_szc == 0);
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			goto top;
		}
	}

	/*
	 * Check to see if we need to allocate an anon_map structure.
	 */
	if (svd->amp == NULL && (svd->vp == NULL || brkcow)) {
		/*
		 * Drop the "read" lock on the segment and acquire
		 * the "write" version since we have to allocate the
		 * anon_map.
		 */
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);

		if (svd->amp == NULL) {
			svd->amp = anonmap_alloc(seg->s_size, 0);
			svd->amp->a_szc = seg->s_szc;
		}
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);

		/*
		 * Start all over again since segment protections
		 * may have changed after we dropped the "read" lock.
		 */
		goto top;
	}

	/*
	 * S_READ_NOCOW vs S_READ distinction was
	 * only needed for the code above. After
	 * that we treat it as S_READ.
	 */
	if (rw == S_READ_NOCOW) {
		ASSERT(type == F_SOFTLOCK);
		ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));
		rw = S_READ;
	}

	amp = svd->amp;

	/*
	 * MADV_SEQUENTIAL work is ignored for large page segments.
	 */
	if (seg->s_szc != 0) {
		pgsz = page_get_pagesize(seg->s_szc);
		ASSERT(SEGVN_LOCK_HELD(seg->s_as, &svd->lock));
		/*
		 * We may need to do relocations so purge seg_pcache to allow
		 * pages to be locked exclusively.
		 */
		if (svd->softlockcnt != 0)
			segvn_purge(seg);
		CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr, lpgeaddr);
		if (svd->vp == NULL) {
			ASSERT(svd->type == MAP_PRIVATE);
			err = segvn_fault_anonpages(hat, seg, lpgaddr,
			    lpgeaddr, type, rw, addr, addr + len, brkcow);
		} else {
			err = segvn_fault_vnodepages(hat, seg, lpgaddr,
				lpgeaddr, type, rw, addr, addr + len, brkcow);
			if (err == IE_RETRY) {
				ASSERT(seg->s_szc == 0);
				ASSERT(SEGVN_READ_HELD(seg->s_as, &svd->lock));
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				goto top;
			}
		}
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (err);
	}

	page = seg_page(seg, addr);
	if (amp != NULL) {
		anon_index = svd->anon_index + page;

		if ((type == F_PROT) && (rw == S_READ) &&
		    svd->type == MAP_PRIVATE && svd->pageprot == 0) {
			size_t index = anon_index;
			struct anon *ap;

			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			/*
			 * The fast path could apply to S_WRITE also, except
			 * that the protection fault could be caused by lazy
			 * tlb flush when ro->rw. In this case, the pte is
			 * RW already. But RO in the other cpu's tlb causes
			 * the fault. Since hat_chgprot won't do anything if
			 * pte doesn't change, we may end up faulting
			 * indefinitely until the RO tlb entry gets replaced.
			 */
			for (a = addr; a < addr + len; a += PAGESIZE, index++) {
				anon_array_enter(amp, index, &cookie);
				ap = anon_get_ptr(amp->ahp, index);
				anon_array_exit(&cookie);
				if ((ap == NULL) || (ap->an_refcnt != 1)) {
					ANON_LOCK_EXIT(&amp->a_rwlock);
					goto slow;
				}
			}
			hat_chgprot(seg->s_as->a_hat, addr, len, svd->prot);
			ANON_LOCK_EXIT(&amp->a_rwlock);
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}
	}
slow:

	if (svd->vpage == NULL)
		vpage = NULL;
	else
		vpage = &svd->vpage[page];

	off = svd->offset + (uintptr_t)(addr - seg->s_base);

	/*
	 * If MADV_SEQUENTIAL has been set for the particular page we
	 * are faulting on, free behind all pages in the segment and put
	 * them on the free list.
	 */
	if ((page != 0) && fltadvice) {	/* not if first page in segment */
		struct vpage *vpp;
		ulong_t fanon_index;
		size_t fpage;
		u_offset_t pgoff, fpgoff;
		struct vnode *fvp;
		struct anon *fap = NULL;

		if (svd->advice == MADV_SEQUENTIAL ||
		    (svd->pageadvice &&
		    VPP_ADVICE(vpage) == MADV_SEQUENTIAL)) {
			pgoff = off - PAGESIZE;
			fpage = page - 1;
			if (vpage != NULL)
				vpp = &svd->vpage[fpage];
			if (amp != NULL)
				fanon_index = svd->anon_index + fpage;

			while (pgoff > svd->offset) {
				if (svd->advice != MADV_SEQUENTIAL &&
				    (!svd->pageadvice || (vpage &&
				    VPP_ADVICE(vpp) != MADV_SEQUENTIAL)))
					break;

				/*
				 * If this is an anon page, we must find the
				 * correct <vp, offset> for it
				 */
				fap = NULL;
				if (amp != NULL) {
					ANON_LOCK_ENTER(&amp->a_rwlock,
						RW_READER);
					anon_array_enter(amp, fanon_index,
						&cookie);
					fap = anon_get_ptr(amp->ahp,
					    fanon_index);
					if (fap != NULL) {
						swap_xlate(fap, &fvp, &fpgoff);
					} else {
						fpgoff = pgoff;
						fvp = svd->vp;
					}
					anon_array_exit(&cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
				} else {
					fpgoff = pgoff;
					fvp = svd->vp;
				}
				if (fvp == NULL)
					break;	/* XXX */
				/*
				 * Skip pages that are free or have an
				 * "exclusive" lock.
				 */
				pp = page_lookup_nowait(fvp, fpgoff, SE_SHARED);
				if (pp == NULL)
					break;
				/*
				 * We don't need the page_struct_lock to test
				 * as this is only advisory; even if we
				 * acquire it someone might race in and lock
				 * the page after we unlock and before the
				 * PUTPAGE, then VOP_PUTPAGE will do nothing.
				 */
				if (pp->p_lckcnt == 0 && pp->p_cowcnt == 0) {
					/*
					 * Hold the vnode before releasing
					 * the page lock to prevent it from
					 * being freed and re-used by some
					 * other thread.
					 */
					VN_HOLD(fvp);
					page_unlock(pp);
					/*
					 * We should build a page list
					 * to kluster putpages XXX
					 */
					(void) VOP_PUTPAGE(fvp,
					    (offset_t)fpgoff, PAGESIZE,
					    (B_DONTNEED|B_FREE|B_ASYNC),
					    svd->cred);
					VN_RELE(fvp);
				} else {
					/*
					 * XXX - Should the loop terminate if
					 * the page is `locked'?
					 */
					page_unlock(pp);
				}
				--vpp;
				--fanon_index;
				pgoff -= PAGESIZE;
			}
		}
	}

	plp = pl;
	*plp = NULL;
	pl_alloc_sz = 0;

	/*
	 * See if we need to call VOP_GETPAGE for
	 * *any* of the range being faulted on.
	 * We can skip all of this work if there
	 * was no original vnode.
	 */
	if (svd->vp != NULL) {
		u_offset_t vp_off;
		size_t vp_len;
		struct anon *ap;
		vnode_t *vp;

		vp_off = off;
		vp_len = len;

		if (amp == NULL)
			dogetpage = 1;
		else {
			/*
			 * Only acquire reader lock to prevent amp->ahp
			 * from being changed.  It's ok to miss pages,
			 * hence we don't do anon_array_enter
			 */
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			ap = anon_get_ptr(amp->ahp, anon_index);

			if (len <= PAGESIZE)
				/* inline non_anon() */
				dogetpage = (ap == NULL);
			else
				dogetpage = non_anon(amp->ahp, anon_index,
				    &vp_off, &vp_len);
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}

		if (dogetpage) {
			enum seg_rw arw;
			struct as *as = seg->s_as;

			if (len > ptob((sizeof (pl) / sizeof (pl[0])) - 1)) {
				/*
				 * Page list won't fit in local array,
				 * allocate one of the needed size.
				 */
				pl_alloc_sz =
				    (btop(len) + 1) * sizeof (page_t *);
				plp = kmem_alloc(pl_alloc_sz, KM_SLEEP);
				plp[0] = NULL;
				plsz = len;
			} else if (rw == S_WRITE && svd->type == MAP_PRIVATE ||
			    rw == S_OTHER ||
			    (((size_t)(addr + PAGESIZE) <
			    (size_t)(seg->s_base + seg->s_size)) &&
			    hat_probe(as->a_hat, addr + PAGESIZE))) {
				/*
				 * Ask VOP_GETPAGE to return the exact number
				 * of pages if
				 * (a) this is a COW fault, or
				 * (b) this is a software fault, or
				 * (c) next page is already mapped.
				 */
				plsz = len;
			} else {
				/*
				 * Ask VOP_GETPAGE to return adjacent pages
				 * within the segment.
				 */
				plsz = MIN((size_t)PVN_GETPAGE_SZ, (size_t)
					((seg->s_base + seg->s_size) - addr));
				ASSERT((addr + plsz) <=
				    (seg->s_base + seg->s_size));
			}

			/*
			 * Need to get some non-anonymous pages.
			 * We need to make only one call to GETPAGE to do
			 * this to prevent certain deadlocking conditions
			 * when we are doing locking.  In this case
			 * non_anon() should have picked up the smallest
			 * range which includes all the non-anonymous
			 * pages in the requested range.  We have to
			 * be careful regarding which rw flag to pass in
			 * because on a private mapping, the underlying
			 * object is never allowed to be written.
			 */
			if (rw == S_WRITE && svd->type == MAP_PRIVATE) {
				arw = S_READ;
			} else {
				arw = rw;
			}
			vp = svd->vp;
			TRACE_3(TR_FAC_VM, TR_SEGVN_GETPAGE,
				"segvn_getpage:seg %p addr %p vp %p",
				seg, addr, vp);
			err = VOP_GETPAGE(vp, (offset_t)vp_off, vp_len,
			    &vpprot, plp, plsz, seg, addr + (vp_off - off), arw,
			    svd->cred);
			if (err) {
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				segvn_pagelist_rele(plp);
				if (pl_alloc_sz)
					kmem_free(plp, pl_alloc_sz);
				return (FC_MAKE_ERR(err));
			}
			if (svd->type == MAP_PRIVATE)
				vpprot &= ~PROT_WRITE;
		}
	}

	/*
	 * N.B. at this time the plp array has all the needed non-anon
	 * pages in addition to (possibly) having some adjacent pages.
	 */

	/*
	 * Always acquire the anon_array_lock to prevent
	 * 2 threads from allocating separate anon slots for
	 * the same "addr".
	 *
	 * If this is a copy-on-write fault and we don't already
	 * have the anon_array_lock, acquire it to prevent the
	 * fault routine from handling multiple copy-on-write faults
	 * on the same "addr" in the same address space.
	 *
	 * Only one thread should deal with the fault since after
	 * it is handled, the other threads can acquire a translation
	 * to the newly created private page.  This prevents two or
	 * more threads from creating different private pages for the
	 * same fault.
	 *
	 * We grab "serialization" lock here if this is a MAP_PRIVATE segment
	 * to prevent deadlock between this thread and another thread
	 * which has soft-locked this page and wants to acquire serial_lock.
	 * ( bug 4026339 )
	 *
	 * The fix for bug 4026339 becomes unnecessary when using the
	 * locking scheme with per amp rwlock and a global set of hash
	 * lock, anon_array_lock.  If we steal a vnode page when low
	 * on memory and upgrad the page lock through page_rename,
	 * then the page is PAGE_HANDLED, nothing needs to be done
	 * for this page after returning from segvn_faultpage.
	 *
	 * But really, the page lock should be downgraded after
	 * the stolen page is page_rename'd.
	 */

	if (amp != NULL)
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);

	/*
	 * Ok, now loop over the address range and handle faults
	 */
	for (a = addr; a < addr + len; a += PAGESIZE, off += PAGESIZE) {
		err = segvn_faultpage(hat, seg, a, off, vpage, plp, vpprot,
		    type, rw, brkcow);
		if (err) {
			if (amp != NULL)
				ANON_LOCK_EXIT(&amp->a_rwlock);
			if (type == F_SOFTLOCK && a > addr)
				segvn_softunlock(seg, addr, (a - addr),
				    S_OTHER);
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			segvn_pagelist_rele(plp);
			if (pl_alloc_sz)
				kmem_free(plp, pl_alloc_sz);
			return (err);
		}
		if (vpage) {
			vpage++;
		} else if (svd->vpage) {
			page = seg_page(seg, addr);
			vpage = &svd->vpage[++page];
		}
	}

	/* Didn't get pages from the underlying fs so we're done */
	if (!dogetpage)
		goto done;

	/*
	 * Now handle any other pages in the list returned.
	 * If the page can be used, load up the translations now.
	 * Note that the for loop will only be entered if "plp"
	 * is pointing to a non-NULL page pointer which means that
	 * VOP_GETPAGE() was called and vpprot has been initialized.
	 */
	if (svd->pageprot == 0)
		prot = svd->prot & vpprot;


	/*
	 * Large Files: diff should be unsigned value because we started
	 * supporting > 2GB segment sizes from 2.5.1 and when a
	 * large file of size > 2GB gets mapped to address space
	 * the diff value can be > 2GB.
	 */

	for (ppp = plp; (pp = *ppp) != NULL; ppp++) {
		size_t diff;
		struct anon *ap;
		int anon_index;
		anon_sync_obj_t cookie;
		int hat_flag = HAT_LOAD_ADV;

		if (svd->flags & MAP_TEXT) {
			hat_flag |= HAT_LOAD_TEXT;
		}

		if (pp == PAGE_HANDLED)
			continue;

		if (pp->p_offset >=  svd->offset &&
			(pp->p_offset < svd->offset + seg->s_size)) {

			diff = pp->p_offset - svd->offset;

			/*
			 * Large Files: Following is the assertion
			 * validating the above cast.
			 */
			ASSERT(svd->vp == pp->p_vnode);

			page = btop(diff);
			if (svd->pageprot)
				prot = VPP_PROT(&svd->vpage[page]) & vpprot;

			/*
			 * Prevent other threads in the address space from
			 * creating private pages (i.e., allocating anon slots)
			 * while we are in the process of loading translations
			 * to additional pages returned by the underlying
			 * object.
			 */
			if (amp != NULL) {
				anon_index = svd->anon_index + page;
				anon_array_enter(amp, anon_index, &cookie);
				ap = anon_get_ptr(amp->ahp, anon_index);
			}
			if ((amp == NULL) || (ap == NULL)) {
				if (IS_VMODSORT(pp->p_vnode) ||
				    enable_mbit_wa) {
					if (rw == S_WRITE)
						hat_setmod(pp);
					else if (rw != S_OTHER &&
					    !hat_ismod(pp))
						prot &= ~PROT_WRITE;
				}
				/*
				 * Skip mapping read ahead pages marked
				 * for migration, so they will get migrated
				 * properly on fault
				 */
				if ((prot & PROT_READ) && !PP_ISMIGRATE(pp)) {
					hat_memload(hat, seg->s_base + diff,
						pp, prot, hat_flag);
				}
			}
			if (amp != NULL)
				anon_array_exit(&cookie);
		}
		page_unlock(pp);
	}
done:
	if (amp != NULL)
		ANON_LOCK_EXIT(&amp->a_rwlock);
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	if (pl_alloc_sz)
		kmem_free(plp, pl_alloc_sz);
	return (0);
}

/*
 * This routine is used to start I/O on pages asynchronously.  XXX it will
 * only create PAGESIZE pages. At fault time they will be relocated into
 * larger pages.
 */
static faultcode_t
segvn_faulta(struct seg *seg, caddr_t addr)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	int err;
	struct anon_map *amp;
	vnode_t *vp;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
	if ((amp = svd->amp) != NULL) {
		struct anon *ap;

		/*
		 * Reader lock to prevent amp->ahp from being changed.
		 * This is advisory, it's ok to miss a page, so
		 * we don't do anon_array_enter lock.
		 */
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
		if ((ap = anon_get_ptr(amp->ahp,
			svd->anon_index + seg_page(seg, addr))) != NULL) {

			err = anon_getpage(&ap, NULL, NULL,
			    0, seg, addr, S_READ, svd->cred);

			ANON_LOCK_EXIT(&amp->a_rwlock);
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			if (err)
				return (FC_MAKE_ERR(err));
			return (0);
		}
		ANON_LOCK_EXIT(&amp->a_rwlock);
	}

	if (svd->vp == NULL) {
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (0);			/* zfod page - do nothing now */
	}

	vp = svd->vp;
	TRACE_3(TR_FAC_VM, TR_SEGVN_GETPAGE,
		"segvn_getpage:seg %p addr %p vp %p", seg, addr, vp);
	err = VOP_GETPAGE(vp,
	    (offset_t)(svd->offset + (uintptr_t)(addr - seg->s_base)),
	    PAGESIZE, NULL, NULL, 0, seg, addr,
	    S_OTHER, svd->cred);

	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	if (err)
		return (FC_MAKE_ERR(err));
	return (0);
}

static int
segvn_setprot(struct seg *seg, caddr_t addr, size_t len, uint_t prot)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *svp, *evp;
	struct vnode *vp;
	size_t pgsz;
	pgcnt_t pgcnt;
	anon_sync_obj_t cookie;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	if ((svd->maxprot & prot) != prot)
		return (EACCES);			/* violated maxprot */

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);

	/* return if prot is the same */
	if (!svd->pageprot && svd->prot == prot) {
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (0);
	}

	/*
	 * Since we change protections we first have to flush the cache.
	 * This makes sure all the pagelock calls have to recheck
	 * protections.
	 */
	if (svd->softlockcnt > 0) {
		/*
		 * Since we do have the segvn writers lock nobody can fill
		 * the cache with entries belonging to this seg during
		 * the purge. The flush either succeeds or we still have
		 * pending I/Os.
		 */
		segvn_purge(seg);
		if (svd->softlockcnt > 0) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (EAGAIN);
		}
	}

	if (seg->s_szc != 0) {
		int err;
		pgsz = page_get_pagesize(seg->s_szc);
		pgcnt = pgsz >> PAGESHIFT;
		ASSERT(IS_P2ALIGNED(pgcnt, pgcnt));
		if (!IS_P2ALIGNED(addr, pgsz) || !IS_P2ALIGNED(len, pgsz)) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			ASSERT(seg->s_base != addr || seg->s_size != len);
			/*
			 * If we are holding the as lock as a reader then
			 * we need to return IE_RETRY and let the as
			 * layer drop and re-aquire the lock as a writer.
			 */
			if (AS_READ_HELD(seg->s_as, &seg->s_as->a_lock))
				return (IE_RETRY);
			VM_STAT_ADD(segvnvmstats.demoterange[1]);
			err = segvn_demote_range(seg, addr, len, SDR_END);
			if (err == 0)
				return (IE_RETRY);
			if (err == ENOMEM)
				return (IE_NOMEM);
			return (err);
		}
	}


	/*
	 * If it's a private mapping and we're making it writable
	 * and no swap space has been reserved, have to reserve
	 * it all now.  If it's a private mapping to a file (i.e., vp != NULL)
	 * and we're removing write permission on the entire segment and
	 * we haven't modified any pages, we can release the swap space.
	 */
	if (svd->type == MAP_PRIVATE) {
		if (prot & PROT_WRITE) {
			size_t sz;
			if (svd->swresv == 0 && !(svd->flags & MAP_NORESERVE)) {
				if (anon_resv(seg->s_size) == 0) {
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (IE_NOMEM);
				}
				sz = svd->swresv = seg->s_size;
				TRACE_3(TR_FAC_VM, TR_ANON_PROC,
					"anon proc:%p %lu %u",
					seg, sz, 1);
			}
		} else {
			/*
			 * Swap space is released only if this segment
			 * does not map anonymous memory, since read faults
			 * on such segments still need an anon slot to read
			 * in the data.
			 */
			if (svd->swresv != 0 && svd->vp != NULL &&
			    svd->amp == NULL && addr == seg->s_base &&
			    len == seg->s_size && svd->pageprot == 0) {
				anon_unresv(svd->swresv);
				svd->swresv = 0;
				TRACE_3(TR_FAC_VM, TR_ANON_PROC,
					"anon proc:%p %lu %u",
					seg, 0, 0);
			}
		}
	}

	if (addr == seg->s_base && len == seg->s_size && svd->pageprot == 0) {
		if (svd->prot == prot) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);			/* all done */
		}
		svd->prot = (uchar_t)prot;
	} else {
		struct anon *ap = NULL;
		page_t *pp;
		u_offset_t offset, off;
		struct anon_map *amp;
		ulong_t anon_idx = 0;

		/*
		 * A vpage structure exists or else the change does not
		 * involve the entire segment.  Establish a vpage structure
		 * if none is there.  Then, for each page in the range,
		 * adjust its individual permissions.  Note that write-
		 * enabling a MAP_PRIVATE page can affect the claims for
		 * locked down memory.  Overcommitting memory terminates
		 * the operation.
		 */
		segvn_vpage(seg);
		if ((amp = svd->amp) != NULL) {
			anon_idx = svd->anon_index + seg_page(seg, addr);
			ASSERT(seg->s_szc == 0 ||
			    IS_P2ALIGNED(anon_idx, pgcnt));
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
		}

		offset = svd->offset + (uintptr_t)(addr - seg->s_base);
		evp = &svd->vpage[seg_page(seg, addr + len)];

		/*
		 * See Statement at the beginning of segvn_lockop regarding
		 * the way cowcnts and lckcnts are handled.
		 */
		for (svp = &svd->vpage[seg_page(seg, addr)]; svp < evp; svp++) {

			ASSERT(seg->s_szc == 0 ||
			    (svd->vp != NULL || svd->type == MAP_PRIVATE));

			if (seg->s_szc != 0 && svd->type == MAP_PRIVATE) {
				if (amp != NULL) {
					anon_array_enter(amp, anon_idx,
					    &cookie);
				}
				if (IS_P2ALIGNED(anon_idx, pgcnt) &&
				    !segvn_claim_pages(seg, svp, offset,
					anon_idx, prot)) {
					if (amp != NULL) {
						anon_array_exit(&cookie);
					}
					break;
				}
				if (amp != NULL) {
					anon_array_exit(&cookie);
				}
				anon_idx++;
			} else {
				if (amp != NULL) {
					anon_array_enter(amp, anon_idx,
						&cookie);
					ap = anon_get_ptr(amp->ahp, anon_idx++);
				}

				if (VPP_ISPPLOCK(svp) &&
				    (VPP_PROT(svp) != prot) &&
				    (svd->type == MAP_PRIVATE)) {

					if (amp == NULL || ap == NULL) {
						vp = svd->vp;
						off = offset;
					} else
						swap_xlate(ap, &vp, &off);
					if (amp != NULL)
						anon_array_exit(&cookie);

					if ((pp = page_lookup(vp, off,
					    SE_SHARED)) == NULL) {
						panic("segvn_setprot: no page");
						/*NOTREACHED*/
					}
					ASSERT(seg->s_szc == 0);
					if ((VPP_PROT(svp) ^ prot) &
					    PROT_WRITE) {
						if (prot & PROT_WRITE) {
						    if (!page_addclaim(pp)) {
							page_unlock(pp);
							break;
						    }
						} else {
						    if (!page_subclaim(pp)) {
							page_unlock(pp);
							break;
						    }
						}
					}
					page_unlock(pp);
				} else if (amp != NULL)
					anon_array_exit(&cookie);
			}
			VPP_SETPROT(svp, prot);
			offset += PAGESIZE;
		}
		if (amp != NULL)
			ANON_LOCK_EXIT(&amp->a_rwlock);

		/*
		 * Did we terminate prematurely?  If so, simply unload
		 * the translations to the things we've updated so far.
		 */
		if (svp != evp) {
			len = (svp - &svd->vpage[seg_page(seg, addr)]) *
			    PAGESIZE;
			ASSERT(seg->s_szc == 0 || IS_P2ALIGNED(len, pgsz));
			if (len != 0)
				hat_unload(seg->s_as->a_hat, addr,
				    len, HAT_UNLOAD);
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (IE_NOMEM);
		}
	}

	if ((prot & PROT_WRITE) != 0 || (prot & ~PROT_USER) == PROT_NONE) {
		/*
		 * Either private or shared data with write access (in
		 * which case we need to throw out all former translations
		 * so that we get the right translations set up on fault
		 * and we don't allow write access to any copy-on-write pages
		 * that might be around or to prevent write access to pages
		 * representing holes in a file), or we don't have permission
		 * to access the memory at all (in which case we have to
		 * unload any current translations that might exist).
		 */
		hat_unload(seg->s_as->a_hat, addr, len, HAT_UNLOAD);
	} else {
		/*
		 * A shared mapping or a private mapping in which write
		 * protection is going to be denied - just change all the
		 * protections over the range of addresses in question.
		 * segvn does not support any other attributes other
		 * than prot so we can use hat_chgattr.
		 */
		hat_chgattr(seg->s_as->a_hat, addr, len, prot);
	}

	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);

	return (0);
}

/*
 * segvn_setpagesize is called via SEGOP_SETPAGESIZE from as_setpagesize,
 * to determine if the seg is capable of mapping the requested szc.
 */
static int
segvn_setpagesize(struct seg *seg, caddr_t addr, size_t len, uint_t szc)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct segvn_data *nsvd;
	struct anon_map *amp = svd->amp;
	struct seg *nseg;
	caddr_t eaddr = addr + len, a;
	size_t pgsz = page_get_pagesize(szc);
	int err;
	u_offset_t off = svd->offset + (uintptr_t)(addr - seg->s_base);
	extern struct vnode kvp;

	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));
	ASSERT(addr >= seg->s_base && eaddr <= seg->s_base + seg->s_size);

	if (seg->s_szc == szc || segvn_lpg_disable != 0) {
		return (0);
	}

	/*
	 * addr should always be pgsz aligned but eaddr may be misaligned if
	 * it's at the end of the segment.
	 *
	 * XXX we should assert this condition since as_setpagesize() logic
	 * guarantees it.
	 */
	if (!IS_P2ALIGNED(addr, pgsz) ||
	    (!IS_P2ALIGNED(eaddr, pgsz) &&
		eaddr != seg->s_base + seg->s_size)) {

		segvn_setpgsz_align_err++;
		return (EINVAL);
	}

	if ((svd->vp == NULL && svd->type == MAP_SHARED) ||
	    (svd->flags & MAP_NORESERVE) || seg->s_as == &kas ||
	    szc > segvn_maxpgszc) {
		return (EINVAL);
	}

	/* paranoid check */
	if (svd->vp != NULL &&
	    (IS_SWAPFSVP(svd->vp) || svd->vp == &kvp)) {
		    return (EINVAL);
	}

	if (seg->s_szc == 0 && svd->vp != NULL &&
	    map_addr_vacalign_check(addr, off)) {
		return (EINVAL);
	}

	/*
	 * Check that protections are the same within new page
	 * size boundaries.
	 */
	if (svd->pageprot) {
		for (a = addr; a < eaddr; a += pgsz) {
			if ((a + pgsz) > eaddr) {
				if (!sameprot(seg, a, eaddr - a)) {
					return (EINVAL);
				}
			} else {
				if (!sameprot(seg, a, pgsz)) {
					return (EINVAL);
				}
			}
		}
	}

	/*
	 * Since we are changing page size we first have to flush
	 * the cache. This makes sure all the pagelock calls have
	 * to recheck protections.
	 */
	if (svd->softlockcnt > 0) {
		/*
		 * Since we do have the segvn writers lock nobody can fill
		 * the cache with entries belonging to this seg during
		 * the purge. The flush either succeeds or we still have
		 * pending I/Os.
		 */
		segvn_purge(seg);
		if (svd->softlockcnt > 0) {
			return (EAGAIN);
		}
	}

	/*
	 * Operation for sub range of existing segment.
	 */
	if (addr != seg->s_base || eaddr != (seg->s_base + seg->s_size)) {
		if (szc < seg->s_szc) {
			VM_STAT_ADD(segvnvmstats.demoterange[2]);
			err = segvn_demote_range(seg, addr, len, SDR_RANGE);
			if (err == 0) {
				return (IE_RETRY);
			}
			if (err == ENOMEM) {
				return (IE_NOMEM);
			}
			return (err);
		}
		if (addr != seg->s_base) {
			nseg = segvn_split_seg(seg, addr);
			if (eaddr != (nseg->s_base + nseg->s_size)) {
				/* eaddr is szc aligned */
				(void) segvn_split_seg(nseg, eaddr);
			}
			return (IE_RETRY);
		}
		if (eaddr != (seg->s_base + seg->s_size)) {
			/* eaddr is szc aligned */
			(void) segvn_split_seg(seg, eaddr);
		}
		return (IE_RETRY);
	}

	/*
	 * Break any low level sharing and reset seg->s_szc to 0.
	 */
	if ((err = segvn_clrszc(seg)) != 0) {
		if (err == ENOMEM) {
			err = IE_NOMEM;
		}
		return (err);
	}
	ASSERT(seg->s_szc == 0);

	/*
	 * If the end of the current segment is not pgsz aligned
	 * then attempt to concatenate with the next segment.
	 */
	if (!IS_P2ALIGNED(eaddr, pgsz)) {
		nseg = AS_SEGNEXT(seg->s_as, seg);
		if (nseg == NULL || nseg == seg || eaddr != nseg->s_base) {
			return (ENOMEM);
		}
		if (nseg->s_ops != &segvn_ops) {
			return (EINVAL);
		}
		nsvd = (struct segvn_data *)nseg->s_data;
		if (nsvd->softlockcnt > 0) {
			segvn_purge(nseg);
			if (nsvd->softlockcnt > 0) {
				return (EAGAIN);
			}
		}
		err = segvn_clrszc(nseg);
		if (err == ENOMEM) {
			err = IE_NOMEM;
		}
		if (err != 0) {
			return (err);
		}
		err = segvn_concat(seg, nseg, 1);
		if (err == -1) {
			return (EINVAL);
		}
		if (err == -2) {
			return (IE_NOMEM);
		}
		return (IE_RETRY);
	}

	/*
	 * May need to re-align anon array to
	 * new szc.
	 */
	if (amp != NULL) {
		pgcnt_t pgcnt = pgsz >> PAGESHIFT;
		if (!IS_P2ALIGNED(svd->anon_index, pgcnt)) {
			struct anon_hdr *nahp;

			ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
			ASSERT(amp->refcnt == 1);
			nahp = anon_create(btop(amp->size), ANON_NOSLEEP);
			if (nahp == NULL) {
				ANON_LOCK_EXIT(&amp->a_rwlock);
				return (IE_NOMEM);
			}
			if (anon_copy_ptr(amp->ahp, svd->anon_index,
				nahp, 0, btop(seg->s_size), ANON_NOSLEEP)) {
				anon_release(nahp, btop(amp->size));
				ANON_LOCK_EXIT(&amp->a_rwlock);
				return (IE_NOMEM);
			}
			anon_release(amp->ahp, btop(amp->size));
			amp->ahp = nahp;
			svd->anon_index = 0;
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}
	}
	if (svd->vp != NULL && szc != 0) {
		struct vattr va;
		u_offset_t eoffpage = svd->offset;
		va.va_mask = AT_SIZE;
		eoffpage += seg->s_size;
		eoffpage = btopr(eoffpage);
		if (VOP_GETATTR(svd->vp, &va, 0, svd->cred) != 0) {
			segvn_setpgsz_getattr_err++;
			return (EINVAL);
		}
		if (btopr(va.va_size) < eoffpage) {
			segvn_setpgsz_eof_err++;
			return (EINVAL);
		}
		if (amp != NULL) {
			/*
			 * anon_fill_cow_holes() may call VOP_GETPAGE().
			 * don't take anon map lock here to avoid holding it
			 * across VOP_GETPAGE() calls that may call back into
			 * segvn for klsutering checks. We don't really need
			 * anon map lock here since it's a private segment and
			 * we hold as level lock as writers.
			 */
			if ((err = anon_fill_cow_holes(seg, seg->s_base,
			    amp->ahp, svd->anon_index, svd->vp, svd->offset,
			    seg->s_size, szc, svd->prot, svd->vpage,
			    svd->cred)) != 0) {
				return (EINVAL);
			}
		}
		segvn_setvnode_mpss(svd->vp);
	}

	if (amp != NULL) {
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
		amp->a_szc = szc;
		ANON_LOCK_EXIT(&amp->a_rwlock);
	}

	seg->s_szc = szc;

	return (0);
}

static int
segvn_clrszc(struct seg *seg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon_map *amp = svd->amp;
	size_t pgsz;
	pgcnt_t pages;
	int err = 0;
	caddr_t a = seg->s_base;
	caddr_t ea = a + seg->s_size;
	ulong_t an_idx = svd->anon_index;
	vnode_t *vp = svd->vp;
	struct vpage *vpage = svd->vpage;
	page_t *anon_pl[1 + 1], *pp;
	struct anon *ap, *oldap;
	uint_t prot = svd->prot, vpprot;

	ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock) ||
	    SEGVN_WRITE_HELD(seg->s_as, &svd->lock));
	ASSERT(svd->type == MAP_PRIVATE ||
	    (vp != NULL && svd->amp == NULL));

	if (vp == NULL && amp == NULL) {
		seg->s_szc = 0;
		return (0);
	}

	/*
	 * do HAT_UNLOAD_UNMAP since we are changing the pagesize.
	 * unload argument is 0 when we are freeing the segment
	 * and unload was already done.
	 */
	hat_unload(seg->s_as->a_hat, seg->s_base, seg->s_size,
	    HAT_UNLOAD_UNMAP);

	if (amp == NULL) {
		seg->s_szc = 0;
		return (0);
	}

	pgsz = page_get_pagesize(seg->s_szc);
	pages = btop(pgsz);

	/*
	 * XXX anon rwlock is not really needed because this is a
	 * private segment and we are writers.
	 */
	ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);

	for (; a < ea; a += pgsz, an_idx += pages) {
		if ((oldap = anon_get_ptr(amp->ahp, an_idx)) != NULL) {
			if (svd->pageprot != 0) {
				ASSERT(vpage != NULL);
				prot = VPP_PROT(vpage);
				ASSERT(sameprot(seg, a, pgsz));
			}
			if (seg->s_szc != 0) {
				ASSERT(vp == NULL || anon_pages(amp->ahp,
				    an_idx, pages) == pages);
				if ((err = anon_map_demotepages(amp, an_idx,
				    seg, a, prot, vpage, svd->cred)) != 0) {
					goto out;
				}
			} else {
				if (oldap->an_refcnt == 1) {
					continue;
				}
				if ((err = anon_getpage(&oldap, &vpprot,
				    anon_pl, PAGESIZE, seg, a, S_READ,
				    svd->cred))) {
					goto out;
				}
				if ((pp = anon_private(&ap, seg, a, prot,
				    anon_pl[0], 0, svd->cred)) == NULL) {
					err = ENOMEM;
					goto out;
				}
				anon_decref(oldap);
				(void) anon_set_ptr(amp->ahp, an_idx, ap,
				    ANON_SLEEP);
				page_unlock(pp);
			}
		}
		vpage = (vpage == NULL) ? NULL : vpage + pages;
	}

	amp->a_szc = 0;
	seg->s_szc = 0;
out:
	ANON_LOCK_EXIT(&amp->a_rwlock);
	return (err);
}

static int
segvn_claim_pages(
	struct seg *seg,
	struct vpage *svp,
	u_offset_t off,
	ulong_t anon_idx,
	uint_t prot)
{
	pgcnt_t	pgcnt = page_get_pagecnt(seg->s_szc);
	size_t ppasize = (pgcnt + 1) * sizeof (page_t *);
	page_t	**ppa;
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon_map *amp = svd->amp;
	struct vpage *evp = svp + pgcnt;
	caddr_t addr = ((uintptr_t)(svp - svd->vpage) << PAGESHIFT)
	    + seg->s_base;
	struct anon *ap;
	struct vnode *vp = svd->vp;
	page_t *pp;
	pgcnt_t pg_idx, i;
	int err = 0;
	anoff_t	aoff;
	int anon = (amp != NULL) ? 1 : 0;

	ASSERT(svd->type == MAP_PRIVATE);
	ASSERT(svd->vpage != NULL);
	ASSERT(seg->s_szc != 0);
	ASSERT(IS_P2ALIGNED(pgcnt, pgcnt));
	ASSERT(amp == NULL || IS_P2ALIGNED(anon_idx, pgcnt));
	ASSERT(sameprot(seg, addr, pgcnt << PAGESHIFT));

	if (VPP_PROT(svp) == prot)
		return (1);
	if (!((VPP_PROT(svp) ^ prot) & PROT_WRITE))
		return (1);

	ppa = kmem_alloc(ppasize, KM_SLEEP);
	if (anon && vp != NULL) {
		if (anon_get_ptr(amp->ahp, anon_idx) == NULL) {
			anon = 0;
			ASSERT(!anon_pages(amp->ahp, anon_idx, pgcnt));
		}
		ASSERT(!anon ||
		    anon_pages(amp->ahp, anon_idx, pgcnt) == pgcnt);
	}

	for (*ppa = NULL, pg_idx = 0; svp < evp; svp++, anon_idx++) {
		if (!VPP_ISPPLOCK(svp))
			continue;
		if (anon) {
			ap = anon_get_ptr(amp->ahp, anon_idx);
			if (ap == NULL) {
				panic("segvn_claim_pages: no anon slot");
			}
			swap_xlate(ap, &vp, &aoff);
			off = (u_offset_t)aoff;
		}
		ASSERT(vp != NULL);
		if ((pp = page_lookup(vp,
		    (u_offset_t)off, SE_SHARED)) == NULL) {
			panic("segvn_claim_pages: no page");
		}
		ppa[pg_idx++] = pp;
		off += PAGESIZE;
	}

	if (ppa[0] == NULL) {
		kmem_free(ppa, ppasize);
		return (1);
	}

	ASSERT(pg_idx <= pgcnt);
	ppa[pg_idx] = NULL;

	if (prot & PROT_WRITE)
		err = page_addclaim_pages(ppa);
	else
		err = page_subclaim_pages(ppa);

	for (i = 0; i < pg_idx; i++) {
		ASSERT(ppa[i] != NULL);
		page_unlock(ppa[i]);
	}

	kmem_free(ppa, ppasize);
	return (err);
}

/*
 * Returns right (upper address) segment if split occured.
 * If the address is equal to the beginning or end of its segment it returns
 * the current segment.
 */
static struct seg *
segvn_split_seg(struct seg *seg, caddr_t addr)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct seg *nseg;
	size_t nsize;
	struct segvn_data *nsvd;

	ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));
	ASSERT(svd->type == MAP_PRIVATE || svd->amp == NULL);
	ASSERT(addr >= seg->s_base);
	ASSERT(addr <= seg->s_base + seg->s_size);

	if (addr == seg->s_base || addr == seg->s_base + seg->s_size)
		return (seg);

	nsize = seg->s_base + seg->s_size - addr;
	seg->s_size = addr - seg->s_base;
	nseg = seg_alloc(seg->s_as, addr, nsize);
	ASSERT(nseg != NULL);
	nseg->s_ops = seg->s_ops;
	nsvd = kmem_cache_alloc(segvn_cache, KM_SLEEP);
	nseg->s_data = (void *)nsvd;
	nseg->s_szc = seg->s_szc;
	*nsvd = *svd;
	rw_init(&nsvd->lock, NULL, RW_DEFAULT, NULL);

	if (nsvd->vp != NULL) {
		VN_HOLD(nsvd->vp);
		nsvd->offset = svd->offset +
		    (uintptr_t)(nseg->s_base - seg->s_base);
		if (nsvd->type == MAP_SHARED)
			lgrp_shm_policy_init(NULL, nsvd->vp);
	} else {
		/*
		 * The offset for an anonymous segment has no signifigance in
		 * terms of an offset into a file. If we were to use the above
		 * calculation instead, the structures read out of
		 * /proc/<pid>/xmap would be more difficult to decipher since
		 * it would be unclear whether two seemingly contiguous
		 * prxmap_t structures represented different segments or a
		 * single segment that had been split up into multiple prxmap_t
		 * structures (e.g. if some part of the segment had not yet
		 * been faulted in).
		 */
		nsvd->offset = 0;
	}

	ASSERT(svd->softlockcnt == 0);
	crhold(svd->cred);

	if (svd->vpage != NULL) {
		size_t bytes = vpgtob(seg_pages(seg));
		size_t nbytes = vpgtob(seg_pages(nseg));
		struct vpage *ovpage = svd->vpage;

		svd->vpage = kmem_alloc(bytes, KM_SLEEP);
		bcopy(ovpage, svd->vpage, bytes);
		nsvd->vpage = kmem_alloc(nbytes, KM_SLEEP);
		bcopy(ovpage + seg_pages(seg), nsvd->vpage, nbytes);
		kmem_free(ovpage, bytes + nbytes);
	}
	if (svd->amp != NULL) {
		struct anon_map *oamp = svd->amp, *namp;
		struct anon_hdr *nahp;

		ANON_LOCK_ENTER(&oamp->a_rwlock, RW_WRITER);
		ASSERT(oamp->refcnt == 1);
		nahp = anon_create(btop(seg->s_size), ANON_SLEEP);
		(void) anon_copy_ptr(oamp->ahp, svd->anon_index,
		    nahp, 0, btop(seg->s_size), ANON_SLEEP);

		namp = anonmap_alloc(nseg->s_size, 0);
		namp->a_szc = nseg->s_szc;
		(void) anon_copy_ptr(oamp->ahp,
		    svd->anon_index + btop(seg->s_size),
		    namp->ahp, 0, btop(nseg->s_size), ANON_SLEEP);
		anon_release(oamp->ahp, btop(oamp->size));
		oamp->ahp = nahp;
		oamp->size = seg->s_size;
		svd->anon_index = 0;
		nsvd->amp = namp;
		nsvd->anon_index = 0;
		ANON_LOCK_EXIT(&oamp->a_rwlock);
	}

	/*
	 * Split amount of swap reserve
	 */
	if (svd->swresv) {
		/*
		 * For MAP_NORESERVE, only allocate swap reserve for pages
		 * being used.  Other segments get enough to cover whole
		 * segment.
		 */
		if (svd->flags & MAP_NORESERVE) {
			size_t	oswresv;

			ASSERT(svd->amp);
			oswresv = svd->swresv;
			svd->swresv = ptob(anon_pages(svd->amp->ahp,
				svd->anon_index, btop(seg->s_size)));
			nsvd->swresv = ptob(anon_pages(nsvd->amp->ahp,
				nsvd->anon_index, btop(nseg->s_size)));
			ASSERT(oswresv >= (svd->swresv + nsvd->swresv));
		} else {
			ASSERT(svd->swresv == seg->s_size + nseg->s_size);
			svd->swresv = seg->s_size;
			nsvd->swresv = nseg->s_size;
		}
	}

	return (nseg);
}


/*
 * called on memory operations (unmap, setprot, setpagesize) for a subset
 * of a large page segment to either demote the memory range (SDR_RANGE)
 * or the ends (SDR_END) by addr/len.
 *
 * returns 0 on success. returns errno, including ENOMEM, on failure.
 */
static int
segvn_demote_range(struct seg *seg, caddr_t addr, size_t len, int flag)
{
	caddr_t eaddr = addr + len;
	caddr_t lpgaddr, lpgeaddr;
	struct seg *nseg;
	struct seg *badseg1 = NULL;
	struct seg *badseg2 = NULL;
	size_t pgsz;
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	int err;

	ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock));
	ASSERT(seg->s_szc != 0);
	pgsz = page_get_pagesize(seg->s_szc);
	ASSERT(seg->s_base != addr || seg->s_size != len);
	ASSERT(addr >= seg->s_base && eaddr <= seg->s_base + seg->s_size);
	ASSERT(svd->softlockcnt == 0);
	ASSERT(svd->type == MAP_PRIVATE ||
	    (svd->vp != NULL && svd->amp == NULL));

	CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr, lpgeaddr);
	ASSERT(flag == SDR_RANGE || eaddr < lpgeaddr || addr > lpgaddr);
	if (flag == SDR_RANGE) {
		/* demote entire range */
		badseg1 = nseg = segvn_split_seg(seg, lpgaddr);
		(void) segvn_split_seg(nseg, lpgeaddr);
		ASSERT(badseg1->s_base == lpgaddr);
		ASSERT(badseg1->s_size == lpgeaddr - lpgaddr);
	} else if (addr != lpgaddr) {
		ASSERT(flag == SDR_END);
		badseg1 = nseg = segvn_split_seg(seg, lpgaddr);
		if (eaddr != lpgeaddr && eaddr > lpgaddr + pgsz &&
		    eaddr < lpgaddr + 2 * pgsz) {
			(void) segvn_split_seg(nseg, lpgeaddr);
			ASSERT(badseg1->s_base == lpgaddr);
			ASSERT(badseg1->s_size == 2 * pgsz);
		} else {
			nseg = segvn_split_seg(nseg, lpgaddr + pgsz);
			ASSERT(badseg1->s_base == lpgaddr);
			ASSERT(badseg1->s_size == pgsz);
			if (eaddr != lpgeaddr && eaddr > lpgaddr + pgsz) {
				ASSERT(lpgeaddr - lpgaddr > 2 * pgsz);
				nseg = segvn_split_seg(nseg, lpgeaddr - pgsz);
				badseg2 = nseg;
				(void) segvn_split_seg(nseg, lpgeaddr);
				ASSERT(badseg2->s_base == lpgeaddr - pgsz);
				ASSERT(badseg2->s_size == pgsz);
			}
		}
	} else {
		ASSERT(flag == SDR_END);
		ASSERT(eaddr < lpgeaddr);
		badseg1 = nseg = segvn_split_seg(seg, lpgeaddr - pgsz);
		(void) segvn_split_seg(nseg, lpgeaddr);
		ASSERT(badseg1->s_base == lpgeaddr - pgsz);
		ASSERT(badseg1->s_size == pgsz);
	}

	ASSERT(badseg1 != NULL);
	ASSERT(badseg1->s_szc != 0);
	ASSERT(page_get_pagesize(badseg1->s_szc) == pgsz);
	ASSERT(flag == SDR_RANGE || badseg1->s_size == pgsz ||
	    badseg1->s_size == 2 * pgsz);
	if (err = segvn_clrszc(badseg1)) {
		return (err);
	}
	ASSERT(badseg1->s_szc == 0);

	if (badseg2 == NULL)
		return (0);
	ASSERT(badseg2->s_szc != 0);
	ASSERT(page_get_pagesize(badseg2->s_szc) == pgsz);
	ASSERT(badseg2->s_size == pgsz);
	ASSERT(sameprot(badseg2, badseg2->s_base, badseg2->s_size));
	if (err = segvn_clrszc(badseg2)) {
		return (err);
	}
	ASSERT(badseg2->s_szc == 0);
	return (0);
}

static int
segvn_checkprot(struct seg *seg, caddr_t addr, size_t len, uint_t prot)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vp, *evp;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
	/*
	 * If segment protection can be used, simply check against them.
	 */
	if (svd->pageprot == 0) {
		int err;

		err = ((svd->prot & prot) != prot) ? EACCES : 0;
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (err);
	}

	/*
	 * Have to check down to the vpage level.
	 */
	evp = &svd->vpage[seg_page(seg, addr + len)];
	for (vp = &svd->vpage[seg_page(seg, addr)]; vp < evp; vp++) {
		if ((VPP_PROT(vp) & prot) != prot) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (EACCES);
		}
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	return (0);
}

static int
segvn_getprot(struct seg *seg, caddr_t addr, size_t len, uint_t *protv)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	size_t pgno = seg_page(seg, addr + len) - seg_page(seg, addr) + 1;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	if (pgno != 0) {
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
		if (svd->pageprot == 0) {
			do
				protv[--pgno] = svd->prot;
			while (pgno != 0);
		} else {
			size_t pgoff = seg_page(seg, addr);

			do {
				pgno--;
				protv[pgno] = VPP_PROT(&svd->vpage[pgno+pgoff]);
			} while (pgno != 0);
		}
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	}
	return (0);
}

static u_offset_t
segvn_getoffset(struct seg *seg, caddr_t addr)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	return (svd->offset + (uintptr_t)(addr - seg->s_base));
}

/*ARGSUSED*/
static int
segvn_gettype(struct seg *seg, caddr_t addr)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	return (svd->type | (svd->flags & MAP_NORESERVE));
}

/*ARGSUSED*/
static int
segvn_getvp(struct seg *seg, caddr_t addr, struct vnode **vpp)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	*vpp = svd->vp;
	return (0);
}

/*
 * Check to see if it makes sense to do kluster/read ahead to
 * addr + delta relative to the mapping at addr.  We assume here
 * that delta is a signed PAGESIZE'd multiple (which can be negative).
 *
 * For segvn, we currently "approve" of the action if we are
 * still in the segment and it maps from the same vp/off,
 * or if the advice stored in segvn_data or vpages allows it.
 * Currently, klustering is not allowed only if MADV_RANDOM is set.
 */
static int
segvn_kluster(struct seg *seg, caddr_t addr, ssize_t delta)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon *oap, *ap;
	ssize_t pd;
	size_t page;
	struct vnode *vp1, *vp2;
	u_offset_t off1, off2;
	struct anon_map *amp;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));
	ASSERT(AS_WRITE_HELD(seg->s_as, &seg->s_as->a_lock) ||
	    SEGVN_LOCK_HELD(seg->s_as, &svd->lock));

	if (addr + delta < seg->s_base ||
	    addr + delta >= (seg->s_base + seg->s_size))
		return (-1);		/* exceeded segment bounds */

	pd = delta / (ssize_t)PAGESIZE;	/* divide to preserve sign bit */
	page = seg_page(seg, addr);

	/*
	 * Check to see if either of the pages addr or addr + delta
	 * have advice set that prevents klustering (if MADV_RANDOM advice
	 * is set for entire segment, or MADV_SEQUENTIAL is set and delta
	 * is negative).
	 */
	if (svd->advice == MADV_RANDOM ||
	    svd->advice == MADV_SEQUENTIAL && delta < 0)
		return (-1);
	else if (svd->pageadvice && svd->vpage) {
		struct vpage *bvpp, *evpp;

		bvpp = &svd->vpage[page];
		evpp = &svd->vpage[page + pd];
		if (VPP_ADVICE(bvpp) == MADV_RANDOM ||
		    VPP_ADVICE(evpp) == MADV_SEQUENTIAL && delta < 0)
			return (-1);
		if (VPP_ADVICE(bvpp) != VPP_ADVICE(evpp) &&
		    VPP_ADVICE(evpp) == MADV_RANDOM)
			return (-1);
	}

	if (svd->type == MAP_SHARED)
		return (0);		/* shared mapping - all ok */

	if ((amp = svd->amp) == NULL)
		return (0);		/* off original vnode */

	page += svd->anon_index;

	ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);

	oap = anon_get_ptr(amp->ahp, page);
	ap = anon_get_ptr(amp->ahp, page + pd);

	ANON_LOCK_EXIT(&amp->a_rwlock);

	if ((oap == NULL && ap != NULL) || (oap != NULL && ap == NULL)) {
		return (-1);		/* one with and one without an anon */
	}

	if (oap == NULL) {		/* implies that ap == NULL */
		return (0);		/* off original vnode */
	}

	/*
	 * Now we know we have two anon pointers - check to
	 * see if they happen to be properly allocated.
	 */

	/*
	 * XXX We cheat here and don't lock the anon slots. We can't because
	 * we may have been called from the anon layer which might already
	 * have locked them. We are holding a refcnt on the slots so they
	 * can't disappear. The worst that will happen is we'll get the wrong
	 * names (vp, off) for the slots and make a poor klustering decision.
	 */
	swap_xlate(ap, &vp1, &off1);
	swap_xlate(oap, &vp2, &off2);


	if (!VOP_CMP(vp1, vp2) || off1 - off2 != delta)
		return (-1);
	return (0);
}

/*
 * Swap the pages of seg out to secondary storage, returning the
 * number of bytes of storage freed.
 *
 * The basic idea is first to unload all translations and then to call
 * VOP_PUTPAGE() for all newly-unmapped pages, to push them out to the
 * swap device.  Pages to which other segments have mappings will remain
 * mapped and won't be swapped.  Our caller (as_swapout) has already
 * performed the unloading step.
 *
 * The value returned is intended to correlate well with the process's
 * memory requirements.  However, there are some caveats:
 * 1)	When given a shared segment as argument, this routine will
 *	only succeed in swapping out pages for the last sharer of the
 *	segment.  (Previous callers will only have decremented mapping
 *	reference counts.)
 * 2)	We assume that the hat layer maintains a large enough translation
 *	cache to capture process reference patterns.
 */
static size_t
segvn_swapout(struct seg *seg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon_map *amp;
	pgcnt_t pgcnt = 0;
	pgcnt_t npages;
	pgcnt_t page;
	ulong_t anon_index;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
	/*
	 * Find pages unmapped by our caller and force them
	 * out to the virtual swap device.
	 */
	if ((amp = svd->amp) != NULL)
		anon_index = svd->anon_index;
	npages = seg->s_size >> PAGESHIFT;
	for (page = 0; page < npages; page++) {
		page_t *pp;
		struct anon *ap;
		struct vnode *vp;
		u_offset_t off;
		anon_sync_obj_t cookie;

		/*
		 * Obtain <vp, off> pair for the page, then look it up.
		 *
		 * Note that this code is willing to consider regular
		 * pages as well as anon pages.  Is this appropriate here?
		 */
		ap = NULL;
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			anon_array_enter(amp, anon_index + page, &cookie);
			ap = anon_get_ptr(amp->ahp, anon_index + page);
			if (ap != NULL) {
				swap_xlate(ap, &vp, &off);
			} else {
				vp = svd->vp;
				off = svd->offset + ptob(page);
			}
			anon_array_exit(&cookie);
			ANON_LOCK_EXIT(&amp->a_rwlock);
		} else {
			vp = svd->vp;
			off = svd->offset + ptob(page);
		}
		if (vp == NULL) {		/* untouched zfod page */
			ASSERT(ap == NULL);
			continue;
		}

		pp = page_lookup_nowait(vp, off, SE_SHARED);
		if (pp == NULL)
			continue;


		/*
		 * Examine the page to see whether it can be tossed out,
		 * keeping track of how many we've found.
		 */
		if (!page_tryupgrade(pp)) {
			/*
			 * If the page has an i/o lock and no mappings,
			 * it's very likely that the page is being
			 * written out as a result of klustering.
			 * Assume this is so and take credit for it here.
			 */
			if (!page_io_trylock(pp)) {
				if (!hat_page_is_mapped(pp))
					pgcnt++;
			} else {
				page_io_unlock(pp);
			}
			page_unlock(pp);
			continue;
		}
		ASSERT(!page_iolock_assert(pp));


		/*
		 * Skip if page is locked or has mappings.
		 * We don't need the page_struct_lock to look at lckcnt
		 * and cowcnt because the page is exclusive locked.
		 */
		if (pp->p_lckcnt != 0 || pp->p_cowcnt != 0 ||
		    hat_page_is_mapped(pp)) {
			page_unlock(pp);
			continue;
		}

		/*
		 * dispose skips large pages so try to demote first.
		 */
		if (pp->p_szc != 0 && !page_try_demote_pages(pp)) {
			page_unlock(pp);
			/*
			 * XXX should skip the remaining page_t's of this
			 * large page.
			 */
			continue;
		}

		ASSERT(pp->p_szc == 0);

		/*
		 * No longer mapped -- we can toss it out.  How
		 * we do so depends on whether or not it's dirty.
		 */
		if (hat_ismod(pp) && pp->p_vnode) {
			/*
			 * We must clean the page before it can be
			 * freed.  Setting B_FREE will cause pvn_done
			 * to free the page when the i/o completes.
			 * XXX:	This also causes it to be accounted
			 *	as a pageout instead of a swap: need
			 *	B_SWAPOUT bit to use instead of B_FREE.
			 *
			 * Hold the vnode before releasing the page lock
			 * to prevent it from being freed and re-used by
			 * some other thread.
			 */
			VN_HOLD(vp);
			page_unlock(pp);

			/*
			 * Queue all i/o requests for the pageout thread
			 * to avoid saturating the pageout devices.
			 */
			if (!queue_io_request(vp, off))
				VN_RELE(vp);
		} else {
			/*
			 * The page was clean, free it.
			 *
			 * XXX:	Can we ever encounter modified pages
			 *	with no associated vnode here?
			 */
			ASSERT(pp->p_vnode != NULL);
			/*LINTED: constant in conditional context*/
			VN_DISPOSE(pp, B_FREE, 0, kcred);
		}

		/*
		 * Credit now even if i/o is in progress.
		 */
		pgcnt++;
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);

	/*
	 * Wakeup pageout to initiate i/o on all queued requests.
	 */
	cv_signal_pageout();
	return (ptob(pgcnt));
}

/*
 * Synchronize primary storage cache with real object in virtual memory.
 *
 * XXX - Anonymous pages should not be sync'ed out at all.
 */
static int
segvn_sync(struct seg *seg, caddr_t addr, size_t len, int attr, uint_t flags)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vpp;
	page_t *pp;
	u_offset_t offset;
	struct vnode *vp;
	u_offset_t off;
	caddr_t eaddr;
	int bflags;
	int err = 0;
	int segtype;
	int pageprot;
	int prot;
	ulong_t anon_index;
	struct anon_map *amp;
	struct anon *ap;
	anon_sync_obj_t cookie;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);

	if (svd->softlockcnt > 0) {
		/*
		 * flush all pages from seg cache
		 * otherwise we may deadlock in swap_putpage
		 * for B_INVAL page (4175402).
		 *
		 * Even if we grab segvn WRITER's lock or segp_slock
		 * here, there might be another thread which could've
		 * successfully performed lookup/insert just before
		 * we acquired the lock here.  So, grabbing either
		 * lock here is of not much use.  Until we devise
		 * a strategy at upper layers to solve the
		 * synchronization issues completely, we expect
		 * applications to handle this appropriately.
		 */
		segvn_purge(seg);
		if (svd->softlockcnt > 0) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (EAGAIN);
		}
	}

	vpp = svd->vpage;
	offset = svd->offset + (uintptr_t)(addr - seg->s_base);
	bflags = ((flags & MS_ASYNC) ? B_ASYNC : 0) |
	    ((flags & MS_INVALIDATE) ? B_INVAL : 0);

	if (attr) {
		pageprot = attr & ~(SHARED|PRIVATE);
		segtype = (attr & SHARED) ? MAP_SHARED : MAP_PRIVATE;

		/*
		 * We are done if the segment types don't match
		 * or if we have segment level protections and
		 * they don't match.
		 */
		if (svd->type != segtype) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}
		if (vpp == NULL) {
			if (svd->prot != pageprot) {
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				return (0);
			}
			prot = svd->prot;
		} else
			vpp = &svd->vpage[seg_page(seg, addr)];

	} else if (svd->vp && svd->amp == NULL &&
	    (flags & MS_INVALIDATE) == 0) {

		/*
		 * No attributes, no anonymous pages and MS_INVALIDATE flag
		 * is not on, just use one big request.
		 */
		err = VOP_PUTPAGE(svd->vp, (offset_t)offset, len,
		    bflags, svd->cred);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (err);
	}

	if ((amp = svd->amp) != NULL)
		anon_index = svd->anon_index + seg_page(seg, addr);

	for (eaddr = addr + len; addr < eaddr; addr += PAGESIZE) {
		ap = NULL;
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			anon_array_enter(amp, anon_index, &cookie);
			ap = anon_get_ptr(amp->ahp, anon_index++);
			if (ap != NULL) {
				swap_xlate(ap, &vp, &off);
			} else {
				vp = svd->vp;
				off = offset;
			}
			anon_array_exit(&cookie);
			ANON_LOCK_EXIT(&amp->a_rwlock);
		} else {
			vp = svd->vp;
			off = offset;
		}
		offset += PAGESIZE;

		if (vp == NULL)		/* untouched zfod page */
			continue;

		if (attr) {
			if (vpp) {
				prot = VPP_PROT(vpp);
				vpp++;
			}
			if (prot != pageprot) {
				continue;
			}
		}

		/*
		 * See if any of these pages are locked --  if so, then we
		 * will have to truncate an invalidate request at the first
		 * locked one. We don't need the page_struct_lock to test
		 * as this is only advisory; even if we acquire it someone
		 * might race in and lock the page after we unlock and before
		 * we do the PUTPAGE, then PUTPAGE simply does nothing.
		 */
		if (flags & MS_INVALIDATE) {
			if ((pp = page_lookup(vp, off, SE_SHARED)) != NULL) {
				if (pp->p_lckcnt != 0 || pp->p_cowcnt != 0) {
					page_unlock(pp);
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (EBUSY);
				}
				if (ap != NULL && pp->p_szc != 0 &&
				    page_tryupgrade(pp)) {
					if (pp->p_lckcnt == 0 &&
					    pp->p_cowcnt == 0) {
						/*
						 * swapfs VN_DISPOSE() won't
						 * invalidate large pages.
						 * Attempt to demote.
						 * XXX can't help it if it
						 * fails. But for swapfs
						 * pages it is no big deal.
						 */
						(void) page_try_demote_pages(
						    pp);
				    }
				}
				page_unlock(pp);
			}
		} else if (svd->type == MAP_SHARED && amp != NULL) {
			/*
			 * Avoid writting out to disk ISM's large pages
			 * because segspt_free_pages() relies on NULL an_pvp
			 * of anon slots of such pages.
			 */

			ASSERT(svd->vp == NULL);
			/*
			 * swapfs uses page_lookup_nowait if not freeing or
			 * invalidating and skips a page if
			 * page_lookup_nowait returns NULL.
			 */
			pp = page_lookup_nowait(vp, off, SE_SHARED);
			if (pp == NULL) {
				continue;
			}
			if (pp->p_szc != 0) {
				page_unlock(pp);
				continue;
			}

			/*
			 * Note ISM pages are created large so (vp, off)'s
			 * page cannot suddenly become large after we unlock
			 * pp.
			 */
			page_unlock(pp);
		}
		/*
		 * XXX - Should ultimately try to kluster
		 * calls to VOP_PUTPAGE() for performance.
		 */
		VN_HOLD(vp);
		err = VOP_PUTPAGE(vp, (offset_t)off, PAGESIZE,
		    bflags, svd->cred);
		VN_RELE(vp);
		if (err)
			break;
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	return (err);
}

/*
 * Determine if we have data corresponding to pages in the
 * primary storage virtual memory cache (i.e., "in core").
 */
static size_t
segvn_incore(struct seg *seg, caddr_t addr, size_t len, char *vec)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vnode *vp, *avp;
	u_offset_t offset, aoffset;
	size_t p, ep;
	int ret;
	struct vpage *vpp;
	page_t *pp;
	uint_t start;
	struct anon_map *amp;		/* XXX - for locknest */
	struct anon *ap;
	uint_t attr;
	anon_sync_obj_t cookie;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
	if (svd->amp == NULL && svd->vp == NULL) {
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		bzero(vec, btopr(len));
		return (len);	/* no anonymous pages created yet */
	}

	p = seg_page(seg, addr);
	ep = seg_page(seg, addr + len);
	start = svd->vp ? SEG_PAGE_VNODEBACKED : 0;

	amp = svd->amp;
	for (; p < ep; p++, addr += PAGESIZE) {
		vpp = (svd->vpage) ? &svd->vpage[p]: NULL;
		ret = start;
		ap = NULL;
		avp = NULL;
		/* Grab the vnode/offset for the anon slot */
		if (amp != NULL) {
			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			anon_array_enter(amp, svd->anon_index + p, &cookie);
			ap = anon_get_ptr(amp->ahp, svd->anon_index + p);
			if (ap != NULL) {
				swap_xlate(ap, &avp, &aoffset);
			}
			anon_array_exit(&cookie);
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}
		if ((avp != NULL) && page_exists(avp, aoffset)) {
			/* A page exists for the anon slot */
			ret |= SEG_PAGE_INCORE;

			/*
			 * If page is mapped and writable
			 */
			attr = (uint_t)0;
			if ((hat_getattr(seg->s_as->a_hat, addr,
			    &attr) != -1) && (attr & PROT_WRITE)) {
				ret |= SEG_PAGE_ANON;
			}
			/*
			 * Don't get page_struct lock for lckcnt and cowcnt,
			 * since this is purely advisory.
			 */
			if ((pp = page_lookup_nowait(avp, aoffset,
			    SE_SHARED)) != NULL) {
				if (pp->p_lckcnt)
					ret |= SEG_PAGE_SOFTLOCK;
				if (pp->p_cowcnt)
					ret |= SEG_PAGE_HASCOW;
				page_unlock(pp);
			}
		}

		/* Gather vnode statistics */
		vp = svd->vp;
		offset = svd->offset + (uintptr_t)(addr - seg->s_base);

		if (vp != NULL) {
			/*
			 * Try to obtain a "shared" lock on the page
			 * without blocking.  If this fails, determine
			 * if the page is in memory.
			 */
			pp = page_lookup_nowait(vp, offset, SE_SHARED);
			if ((pp == NULL) && (page_exists(vp, offset))) {
				/* Page is incore, and is named */
				ret |= (SEG_PAGE_INCORE | SEG_PAGE_VNODE);
			}
			/*
			 * Don't get page_struct lock for lckcnt and cowcnt,
			 * since this is purely advisory.
			 */
			if (pp != NULL) {
				ret |= (SEG_PAGE_INCORE | SEG_PAGE_VNODE);
				if (pp->p_lckcnt)
					ret |= SEG_PAGE_SOFTLOCK;
				if (pp->p_cowcnt)
					ret |= SEG_PAGE_HASCOW;
				page_unlock(pp);
			}
		}

		/* Gather virtual page information */
		if (vpp) {
			if (VPP_ISPPLOCK(vpp))
				ret |= SEG_PAGE_LOCKED;
			vpp++;
		}

		*vec++ = (char)ret;
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	return (len);
}

/*
 * Statement for p_cowcnts/p_lckcnts.
 *
 * p_cowcnt is updated while mlock/munlocking MAP_PRIVATE and PROT_WRITE region
 * irrespective of the following factors or anything else:
 *
 *	(1) anon slots are populated or not
 *	(2) cow is broken or not
 *	(3) refcnt on ap is 1 or greater than 1
 *
 * If it's not MAP_PRIVATE and PROT_WRITE, p_lckcnt is updated during mlock
 * and munlock.
 *
 *
 * Handling p_cowcnts/p_lckcnts during copy-on-write fault:
 *
 *	if vpage has PROT_WRITE
 *		transfer cowcnt on the oldpage -> cowcnt on the newpage
 *	else
 *		transfer lckcnt on the oldpage -> lckcnt on the newpage
 *
 *	During copy-on-write, decrement p_cowcnt on the oldpage and increment
 *	p_cowcnt on the newpage *if* the corresponding vpage has PROT_WRITE.
 *
 *	We may also break COW if softlocking on read access in the physio case.
 *	In this case, vpage may not have PROT_WRITE. So, we need to decrement
 *	p_lckcnt on the oldpage and increment p_lckcnt on the newpage *if* the
 *	vpage doesn't have PROT_WRITE.
 *
 *
 * Handling p_cowcnts/p_lckcnts during mprotect on mlocked region:
 *
 * 	If a MAP_PRIVATE region loses PROT_WRITE, we decrement p_cowcnt and
 *	increment p_lckcnt by calling page_subclaim() which takes care of
 * 	availrmem accounting and p_lckcnt overflow.
 *
 *	If a MAP_PRIVATE region gains PROT_WRITE, we decrement p_lckcnt and
 *	increment p_cowcnt by calling page_addclaim() which takes care of
 *	availrmem availability and p_cowcnt overflow.
 */

/*
 * Lock down (or unlock) pages mapped by this segment.
 *
 * XXX only creates PAGESIZE pages if anon slots are not initialized.
 * At fault time they will be relocated into larger pages.
 */
static int
segvn_lockop(struct seg *seg, caddr_t addr, size_t len,
    int attr, int op, ulong_t *lockmap, size_t pos)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vpp;
	struct vpage *evp;
	page_t *pp;
	u_offset_t offset;
	u_offset_t off;
	int segtype;
	int pageprot;
	int claim;
	struct vnode *vp;
	ulong_t anon_index;
	struct anon_map *amp;
	struct anon *ap;
	struct vattr va;
	anon_sync_obj_t cookie;

	/*
	 * Hold write lock on address space because may split or concatenate
	 * segments
	 */
	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);
	if (attr) {
		pageprot = attr & ~(SHARED|PRIVATE);
		segtype = attr & SHARED ? MAP_SHARED : MAP_PRIVATE;

		/*
		 * We are done if the segment types don't match
		 * or if we have segment level protections and
		 * they don't match.
		 */
		if (svd->type != segtype) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}
		if (svd->pageprot == 0 && svd->prot != pageprot) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}
	}

	/*
	 * If we're locking, then we must create a vpage structure if
	 * none exists.  If we're unlocking, then check to see if there
	 * is a vpage --  if not, then we could not have locked anything.
	 */

	if ((vpp = svd->vpage) == NULL) {
		if (op == MC_LOCK)
			segvn_vpage(seg);
		else {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}
	}

	/*
	 * The anonymous data vector (i.e., previously
	 * unreferenced mapping to swap space) can be allocated
	 * by lazily testing for its existence.
	 */
	if (op == MC_LOCK && svd->amp == NULL && svd->vp == NULL) {
		svd->amp = anonmap_alloc(seg->s_size, 0);
		svd->amp->a_szc = seg->s_szc;
	}

	if ((amp = svd->amp) != NULL) {
		anon_index = svd->anon_index + seg_page(seg, addr);
	}

	offset = svd->offset + (uintptr_t)(addr - seg->s_base);
	evp = &svd->vpage[seg_page(seg, addr + len)];

	/*
	 * Loop over all pages in the range.  Process if we're locking and
	 * page has not already been locked in this mapping; or if we're
	 * unlocking and the page has been locked.
	 */
	for (vpp = &svd->vpage[seg_page(seg, addr)]; vpp < evp;
	    vpp++, pos++, addr += PAGESIZE, offset += PAGESIZE, anon_index++) {
		if ((attr == 0 || VPP_PROT(vpp) == pageprot) &&
		    ((op == MC_LOCK && !VPP_ISPPLOCK(vpp)) ||
		    (op == MC_UNLOCK && VPP_ISPPLOCK(vpp)))) {

			if (amp != NULL)
				ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			/*
			 * If this isn't a MAP_NORESERVE segment and
			 * we're locking, allocate anon slots if they
			 * don't exist.  The page is brought in later on.
			 */
			if (op == MC_LOCK && svd->vp == NULL &&
			    ((svd->flags & MAP_NORESERVE) == 0) &&
			    amp != NULL &&
			    ((ap = anon_get_ptr(amp->ahp, anon_index))
								== NULL)) {
				anon_array_enter(amp, anon_index, &cookie);

				if ((ap = anon_get_ptr(amp->ahp,
						anon_index)) == NULL) {
					pp = anon_zero(seg, addr, &ap,
					    svd->cred);
					if (pp == NULL) {
						anon_array_exit(&cookie);
						ANON_LOCK_EXIT(&amp->a_rwlock);
						SEGVN_LOCK_EXIT(seg->s_as,
						    &svd->lock);
						return (ENOMEM);
					}
					ASSERT(anon_get_ptr(amp->ahp,
						anon_index) == NULL);
					(void) anon_set_ptr(amp->ahp,
						anon_index, ap, ANON_SLEEP);
					page_unlock(pp);
				}
				anon_array_exit(&cookie);
			}

			/*
			 * Get name for page, accounting for
			 * existence of private copy.
			 */
			ap = NULL;
			if (amp != NULL) {
				anon_array_enter(amp, anon_index, &cookie);
				ap = anon_get_ptr(amp->ahp, anon_index);
				if (ap != NULL) {
					swap_xlate(ap, &vp, &off);
				} else {
					if (svd->vp == NULL &&
					    (svd->flags & MAP_NORESERVE)) {
						anon_array_exit(&cookie);
						ANON_LOCK_EXIT(&amp->a_rwlock);
						continue;
					}
					vp = svd->vp;
					off = offset;
				}
				anon_array_exit(&cookie);
				ANON_LOCK_EXIT(&amp->a_rwlock);
			} else {
				vp = svd->vp;
				off = offset;
			}

			/*
			 * Get page frame.  It's ok if the page is
			 * not available when we're unlocking, as this
			 * may simply mean that a page we locked got
			 * truncated out of existence after we locked it.
			 *
			 * Invoke VOP_GETPAGE() to obtain the page struct
			 * since we may need to read it from disk if its
			 * been paged out.
			 */
			if (op != MC_LOCK)
				pp = page_lookup(vp, off, SE_SHARED);
			else {
				page_t *pl[1 + 1];
				int error;

				ASSERT(vp != NULL);

				error = VOP_GETPAGE(vp, (offset_t)off, PAGESIZE,
				    (uint_t *)NULL, pl, PAGESIZE, seg, addr,
				    S_OTHER, svd->cred);

				/*
				 * If the error is EDEADLK then we must bounce
				 * up and drop all vm subsystem locks and then
				 * retry the operation later
				 * This behavior is a temporary measure because
				 * ufs/sds logging is badly designed and will
				 * deadlock if we don't allow this bounce to
				 * happen.  The real solution is to re-design
				 * the logging code to work properly.  See bug
				 * 4125102 for details of the problem.
				 */
				if (error == EDEADLK) {
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (error);
				}
				/*
				 * Quit if we fail to fault in the page.  Treat
				 * the failure as an error, unless the addr
				 * is mapped beyond the end of a file.
				 */
				if (error && svd->vp) {
					va.va_mask = AT_SIZE;
					if (VOP_GETATTR(svd->vp, &va, 0,
					    svd->cred) != 0) {
						SEGVN_LOCK_EXIT(seg->s_as,
						    &svd->lock);
						return (EIO);
					}
					if (btopr(va.va_size) >=
					    btopr(off + 1)) {
						SEGVN_LOCK_EXIT(seg->s_as,
						    &svd->lock);
						return (EIO);
					}
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (0);
				} else if (error) {
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (EIO);
				}
				pp = pl[0];
				ASSERT(pp != NULL);
			}

			/*
			 * See Statement at the beginning of this routine.
			 *
			 * claim is always set if MAP_PRIVATE and PROT_WRITE
			 * irrespective of following factors:
			 *
			 * (1) anon slots are populated or not
			 * (2) cow is broken or not
			 * (3) refcnt on ap is 1 or greater than 1
			 *
			 * See 4140683 for details
			 */
			claim = ((VPP_PROT(vpp) & PROT_WRITE) &&
				(svd->type == MAP_PRIVATE));

			/*
			 * Perform page-level operation appropriate to
			 * operation.  If locking, undo the SOFTLOCK
			 * performed to bring the page into memory
			 * after setting the lock.  If unlocking,
			 * and no page was found, account for the claim
			 * separately.
			 */
			if (op == MC_LOCK) {
				int ret = 1;	/* Assume success */

				/*
				 * Make sure another thread didn't lock
				 * the page after we released the segment
				 * lock.
				 */
				if ((attr == 0 || VPP_PROT(vpp) == pageprot) &&
				    !VPP_ISPPLOCK(vpp)) {
					ret = page_pp_lock(pp, claim, 0);
					if (ret != 0) {
						VPP_SETPPLOCK(vpp);
						if (lockmap != (ulong_t *)NULL)
							BT_SET(lockmap, pos);
					}
				}
				page_unlock(pp);
				if (ret == 0) {
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (EAGAIN);
				}
			} else {
				if (pp != NULL) {
					if ((attr == 0 ||
					    VPP_PROT(vpp) == pageprot) &&
					    VPP_ISPPLOCK(vpp))
						page_pp_unlock(pp, claim, 0);
					page_unlock(pp);
				}
				VPP_CLRPPLOCK(vpp);
			}
		}
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	return (0);
}

/*
 * Set advice from user for specified pages
 * There are 5 types of advice:
 *	MADV_NORMAL	- Normal (default) behavior (whatever that is)
 *	MADV_RANDOM	- Random page references
 *				do not allow readahead or 'klustering'
 *	MADV_SEQUENTIAL	- Sequential page references
 *				Pages previous to the one currently being
 *				accessed (determined by fault) are 'not needed'
 *				and are freed immediately
 *	MADV_WILLNEED	- Pages are likely to be used (fault ahead in mctl)
 *	MADV_DONTNEED	- Pages are not needed (synced out in mctl)
 *	MADV_FREE	- Contents can be discarded
 *	MADV_ACCESS_DEFAULT- Default access
 *	MADV_ACCESS_LWP	- Next LWP will access heavily
 *	MADV_ACCESS_MANY- Many LWPs or processes will access heavily
 */
static int
segvn_advise(struct seg *seg, caddr_t addr, size_t len, uint_t behav)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	size_t page;
	int err = 0;
	int already_set;
	struct anon_map *amp;
	ulong_t anon_index;
	struct seg *next;
	lgrp_mem_policy_t policy;
	struct seg *prev;
	struct vnode *vp;

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));

	/*
	 * In case of MADV_FREE, we won't be modifying any segment private
	 * data structures; so, we only need to grab READER's lock
	 */
	if (behav != MADV_FREE)
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_WRITER);
	else
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);

	/*
	 * Large pages are assumed to be only turned on when accesses to the
	 * segment's address range have spatial and temporal locality. That
	 * justifies ignoring MADV_SEQUENTIAL for large page segments.
	 * Also, ignore advice affecting lgroup memory allocation
	 * if don't need to do lgroup optimizations on this system
	 */

	if ((behav == MADV_SEQUENTIAL && seg->s_szc != 0) ||
	    (!lgrp_optimizations() && (behav == MADV_ACCESS_DEFAULT ||
	    behav == MADV_ACCESS_LWP || behav == MADV_ACCESS_MANY))) {
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (0);
	}

	if (behav == MADV_SEQUENTIAL || behav == MADV_ACCESS_DEFAULT ||
	    behav == MADV_ACCESS_LWP || behav == MADV_ACCESS_MANY) {
		/*
		 * Since we are going to unload hat mappings
		 * we first have to flush the cache. Otherwise
		 * this might lead to system panic if another
		 * thread is doing physio on the range whose
		 * mappings are unloaded by madvise(3C).
		 */
		if (svd->softlockcnt > 0) {
			/*
			 * Since we do have the segvn writers lock
			 * nobody can fill the cache with entries
			 * belonging to this seg during the purge.
			 * The flush either succeeds or we still
			 * have pending I/Os. In the later case,
			 * madvise(3C) fails.
			 */
			segvn_purge(seg);
			if (svd->softlockcnt > 0) {
				/*
				 * Since madvise(3C) is advisory and
				 * it's not part of UNIX98, madvise(3C)
				 * failure here doesn't cause any hardship.
				 * Note that we don't block in "as" layer.
				 */
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				return (EAGAIN);
			}
		}
	}

	amp = svd->amp;
	vp = svd->vp;
	if (behav == MADV_FREE) {
		/*
		 * MADV_FREE is not supported for segments with
		 * underlying object; if anonmap is NULL, anon slots
		 * are not yet populated and there is nothing for
		 * us to do. As MADV_FREE is advisory, we don't
		 * return error in either case.
		 */
		if (vp || amp == NULL) {
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
			return (0);
		}

		page = seg_page(seg, addr);
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
		anon_disclaim(amp, svd->anon_index + page, len, 0);
		ANON_LOCK_EXIT(&amp->a_rwlock);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		return (0);
	}

	/*
	 * If advice is to be applied to entire segment,
	 * use advice field in seg_data structure
	 * otherwise use appropriate vpage entry.
	 */
	if ((addr == seg->s_base) && (len == seg->s_size)) {
		switch (behav) {
		case MADV_ACCESS_LWP:
		case MADV_ACCESS_MANY:
		case MADV_ACCESS_DEFAULT:
			/*
			 * Set memory allocation policy for this segment
			 */
			policy = lgrp_madv_to_policy(behav, len, svd->type);
			if (svd->type == MAP_SHARED)
				already_set = lgrp_shm_policy_set(policy, amp,
				    svd->anon_index, vp, svd->offset, len);
			else {
				/*
				 * For private memory, need writers lock on
				 * address space because the segment may be
				 * split or concatenated when changing policy
				 */
				if (AS_READ_HELD(seg->s_as,
				    &seg->s_as->a_lock)) {
					SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
					return (IE_RETRY);
				}

				already_set = lgrp_privm_policy_set(policy,
				    &svd->policy_info, len);
			}

			/*
			 * If policy set already and it shouldn't be reapplied,
			 * don't do anything.
			 */
			if (already_set &&
			    !LGRP_MEM_POLICY_REAPPLICABLE(policy))
				break;

			/*
			 * Mark any existing pages in given range for
			 * migration
			 */
			page_mark_migrate(seg, addr, len, amp, svd->anon_index,
			    vp, svd->offset, 1);

			/*
			 * If same policy set already or this is a shared
			 * memory segment, don't need to try to concatenate
			 * segment with adjacent ones.
			 */
			if (already_set || svd->type == MAP_SHARED)
				break;

			/*
			 * Try to concatenate this segment with previous
			 * one and next one, since we changed policy for
			 * this one and it may be compatible with adjacent
			 * ones now.
			 */
			prev = AS_SEGPREV(seg->s_as, seg);
			next = AS_SEGNEXT(seg->s_as, seg);

			if (next && next->s_ops == &segvn_ops &&
			    addr + len == next->s_base)
				(void) segvn_concat(seg, next, 1);

			if (prev && prev->s_ops == &segvn_ops &&
			    addr == prev->s_base + prev->s_size) {
				/*
				 * Drop lock for private data of current
				 * segment before concatenating (deleting) it
				 * and return IE_REATTACH to tell as_ctl() that
				 * current segment has changed
				 */
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				if (!segvn_concat(prev, seg, 1))
					err = IE_REATTACH;

				return (err);
			}
			break;

		case MADV_SEQUENTIAL:
			/*
			 * unloading mapping guarantees
			 * detection in segvn_fault
			 */
			ASSERT(seg->s_szc == 0);
			hat_unload(seg->s_as->a_hat, addr, len,
				HAT_UNLOAD);
			/* FALLTHROUGH */
		case MADV_NORMAL:
		case MADV_RANDOM:
			svd->advice = (uchar_t)behav;
			svd->pageadvice = 0;
			break;
		case MADV_WILLNEED:	/* handled in memcntl */
		case MADV_DONTNEED:	/* handled in memcntl */
		case MADV_FREE:		/* handled above */
			break;
		default:
			err = EINVAL;
		}
	} else {
		caddr_t			eaddr;
		struct seg		*new_seg;
		struct segvn_data	*new_svd;
		u_offset_t		off;
		caddr_t			oldeaddr;

		page = seg_page(seg, addr);

		segvn_vpage(seg);

		switch (behav) {
			struct vpage *bvpp, *evpp;

		case MADV_ACCESS_LWP:
		case MADV_ACCESS_MANY:
		case MADV_ACCESS_DEFAULT:
			/*
			 * Set memory allocation policy for portion of this
			 * segment
			 */

			/*
			 * Align address and length of advice to page
			 * boundaries for large pages
			 */
			if (seg->s_szc != 0) {
				size_t	pgsz;

				pgsz = page_get_pagesize(seg->s_szc);
				addr = (caddr_t)P2ALIGN((uintptr_t)addr, pgsz);
				len = P2ROUNDUP(len, pgsz);
			}

			/*
			 * Check to see whether policy is set already
			 */
			policy = lgrp_madv_to_policy(behav, len, svd->type);

			anon_index = svd->anon_index + page;
			off = svd->offset + (uintptr_t)(addr - seg->s_base);

			if (svd->type == MAP_SHARED)
				already_set = lgrp_shm_policy_set(policy, amp,
				    anon_index, vp, off, len);
			else
				already_set =
				    (policy == svd->policy_info.mem_policy);

			/*
			 * If policy set already and it shouldn't be reapplied,
			 * don't do anything.
			 */
			if (already_set &&
			    !LGRP_MEM_POLICY_REAPPLICABLE(policy))
				break;

			/*
			 * For private memory, need writers lock on
			 * address space because the segment may be
			 * split or concatenated when changing policy
			 */
			if (svd->type == MAP_PRIVATE &&
			    AS_READ_HELD(seg->s_as, &seg->s_as->a_lock)) {
				SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
				return (IE_RETRY);
			}

			/*
			 * Mark any existing pages in given range for
			 * migration
			 */
			page_mark_migrate(seg, addr, len, amp, svd->anon_index,
			    vp, svd->offset, 1);

			/*
			 * Don't need to try to split or concatenate
			 * segments, since policy is same or this is a shared
			 * memory segment
			 */
			if (already_set || svd->type == MAP_SHARED)
				break;

			/*
			 * Split off new segment if advice only applies to a
			 * portion of existing segment starting in middle
			 */
			new_seg = NULL;
			eaddr = addr + len;
			oldeaddr = seg->s_base + seg->s_size;
			if (addr > seg->s_base) {
				/*
				 * Must flush I/O page cache
				 * before splitting segment
				 */
				if (svd->softlockcnt > 0)
					segvn_purge(seg);

				/*
				 * Split segment and return IE_REATTACH to tell
				 * as_ctl() that current segment changed
				 */
				new_seg = segvn_split_seg(seg, addr);
				new_svd = (struct segvn_data *)new_seg->s_data;
				err = IE_REATTACH;

				/*
				 * If new segment ends where old one
				 * did, try to concatenate the new
				 * segment with next one.
				 */
				if (eaddr == oldeaddr) {
					/*
					 * Set policy for new segment
					 */
					(void) lgrp_privm_policy_set(policy,
					    &new_svd->policy_info,
					    new_seg->s_size);

					next = AS_SEGNEXT(new_seg->s_as,
					    new_seg);

					if (next &&
					    next->s_ops == &segvn_ops &&
					    eaddr == next->s_base)
						(void) segvn_concat(new_seg,
						    next, 1);
				}
			}

			/*
			 * Split off end of existing segment if advice only
			 * applies to a portion of segment ending before
			 * end of the existing segment
			 */
			if (eaddr < oldeaddr) {
				/*
				 * Must flush I/O page cache
				 * before splitting segment
				 */
				if (svd->softlockcnt > 0)
					segvn_purge(seg);

				/*
				 * If beginning of old segment was already
				 * split off, use new segment to split end off
				 * from.
				 */
				if (new_seg != NULL && new_seg != seg) {
					/*
					 * Split segment
					 */
					(void) segvn_split_seg(new_seg, eaddr);

					/*
					 * Set policy for new segment
					 */
					(void) lgrp_privm_policy_set(policy,
					    &new_svd->policy_info,
					    new_seg->s_size);
				} else {
					/*
					 * Split segment and return IE_REATTACH
					 * to tell as_ctl() that current
					 * segment changed
					 */
					(void) segvn_split_seg(seg, eaddr);
					err = IE_REATTACH;

					(void) lgrp_privm_policy_set(policy,
					    &svd->policy_info, seg->s_size);

					/*
					 * If new segment starts where old one
					 * did, try to concatenate it with
					 * previous segment.
					 */
					if (addr == seg->s_base) {
						prev = AS_SEGPREV(seg->s_as,
						    seg);

						/*
						 * Drop lock for private data
						 * of current segment before
						 * concatenating (deleting) it
						 */
						if (prev &&
						    prev->s_ops ==
						    &segvn_ops &&
						    addr == prev->s_base +
						    prev->s_size) {
							SEGVN_LOCK_EXIT(
							    seg->s_as,
							    &svd->lock);
							(void) segvn_concat(
							    prev, seg, 1);
							return (err);
						}
					}
				}
			}
			break;
		case MADV_SEQUENTIAL:
			ASSERT(seg->s_szc == 0);
			hat_unload(seg->s_as->a_hat, addr, len, HAT_UNLOAD);
			/* FALLTHROUGH */
		case MADV_NORMAL:
		case MADV_RANDOM:
			bvpp = &svd->vpage[page];
			evpp = &svd->vpage[page + (len >> PAGESHIFT)];
			for (; bvpp < evpp; bvpp++)
				VPP_SETADVICE(bvpp, behav);
			svd->advice = MADV_NORMAL;
			break;
		case MADV_WILLNEED:	/* handled in memcntl */
		case MADV_DONTNEED:	/* handled in memcntl */
		case MADV_FREE:		/* handled above */
			break;
		default:
			err = EINVAL;
		}
	}
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	return (err);
}

/*
 * Create a vpage structure for this seg.
 */
static void
segvn_vpage(struct seg *seg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vp, *evp;

	ASSERT(SEGVN_WRITE_HELD(seg->s_as, &svd->lock));

	/*
	 * If no vpage structure exists, allocate one.  Copy the protections
	 * and the advice from the segment itself to the individual pages.
	 */
	if (svd->vpage == NULL) {
		svd->pageprot = 1;
		svd->pageadvice = 1;
		svd->vpage = kmem_zalloc(seg_pages(seg) * sizeof (struct vpage),
		    KM_SLEEP);
		evp = &svd->vpage[seg_page(seg, seg->s_base + seg->s_size)];
		for (vp = svd->vpage; vp < evp; vp++) {
			VPP_SETPROT(vp, svd->prot);
			VPP_SETADVICE(vp, svd->advice);
		}
	}
}

/*
 * Dump the pages belonging to this segvn segment.
 */
static void
segvn_dump(struct seg *seg)
{
	struct segvn_data *svd;
	page_t *pp;
	struct anon_map *amp;
	ulong_t	anon_index;
	struct vnode *vp;
	u_offset_t off, offset;
	pfn_t pfn;
	pgcnt_t page, npages;
	caddr_t addr;

	npages = seg_pages(seg);
	svd = (struct segvn_data *)seg->s_data;
	vp = svd->vp;
	off = offset = svd->offset;
	addr = seg->s_base;

	if ((amp = svd->amp) != NULL) {
		anon_index = svd->anon_index;
		ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
	}

	for (page = 0; page < npages; page++, offset += PAGESIZE) {
		struct anon *ap;
		int we_own_it = 0;

		if (amp && (ap = anon_get_ptr(svd->amp->ahp, anon_index++))) {
			swap_xlate_nopanic(ap, &vp, &off);
		} else {
			vp = svd->vp;
			off = offset;
		}

		/*
		 * If pp == NULL, the page either does not exist
		 * or is exclusively locked.  So determine if it
		 * exists before searching for it.
		 */

		if ((pp = page_lookup_nowait(vp, off, SE_SHARED)))
			we_own_it = 1;
		else
			pp = page_exists(vp, off);

		if (pp) {
			pfn = page_pptonum(pp);
			dump_addpage(seg->s_as, addr, pfn);
			if (we_own_it)
				page_unlock(pp);
		}
		addr += PAGESIZE;
		dump_timeleft = dump_timeout;
	}

	if (amp != NULL)
		ANON_LOCK_EXIT(&amp->a_rwlock);
}

/*
 * lock/unlock anon pages over a given range. Return shadow list
 */
static int
segvn_pagelock(struct seg *seg, caddr_t addr, size_t len, struct page ***ppp,
    enum lock_type type, enum seg_rw rw)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	size_t np, adjustpages = 0, npages = (len >> PAGESHIFT);
	ulong_t anon_index;
	uint_t protchk;
	uint_t error;
	struct anon_map *amp;
	struct page **pplist, **pl, *pp;
	caddr_t a;
	size_t page;
	caddr_t lpgaddr, lpgeaddr;

	TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_START,
		"segvn_pagelock: start seg %p addr %p", seg, addr);

	ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as, &seg->s_as->a_lock));
	if (seg->s_szc != 0 && (type == L_PAGELOCK || type == L_PAGEUNLOCK)) {
		/*
		 * We are adjusting the pagelock region to the large page size
		 * boundary because the unlocked part of a large page cannot
		 * be freed anyway unless all constituent pages of a large
		 * page are locked. Therefore this adjustment allows us to
		 * decrement availrmem by the right value (note we don't want
		 * to just decrement availrem by the large page size without
		 * adjusting addr and len because then we may end up
		 * decrementing availrmem by large page size for every
		 * constituent page locked by a new as_pagelock call).
		 * as_pageunlock caller must always match as_pagelock call's
		 * addr and len.
		 *
		 * Note segment's page size cannot change while we are holding
		 * as lock.  And then it cannot change while softlockcnt is
		 * not 0. This will allow us to correctly recalculate large
		 * page size region for the matching pageunlock/reclaim call.
		 *
		 * for pageunlock *ppp points to the pointer of page_t that
		 * corresponds to the real unadjusted start address. Similar
		 * for pagelock *ppp must point to the pointer of page_t that
		 * corresponds to the real unadjusted start address.
		 */
		size_t pgsz = page_get_pagesize(seg->s_szc);
		CALC_LPG_REGION(pgsz, seg, addr, len, lpgaddr, lpgeaddr);
		adjustpages = ((uintptr_t)(addr - lpgaddr)) >> PAGESHIFT;
	}

	if (type == L_PAGEUNLOCK) {

		/*
		 * update hat ref bits for /proc. We need to make sure
		 * that threads tracing the ref and mod bits of the
		 * address space get the right data.
		 * Note: page ref and mod bits are updated at reclaim time
		 */
		if (seg->s_as->a_vbits) {
			for (a = addr; a < addr + len; a += PAGESIZE) {
				if (rw == S_WRITE) {
					hat_setstat(seg->s_as, a,
					    PAGESIZE, P_REF | P_MOD);
				} else {
					hat_setstat(seg->s_as, a,
					    PAGESIZE, P_REF);
				}
			}
		}
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
		if (seg->s_szc != 0) {
			VM_STAT_ADD(segvnvmstats.pagelock[0]);
			seg_pinactive(seg, lpgaddr, lpgeaddr - lpgaddr,
			    *ppp - adjustpages, rw, segvn_reclaim);
		} else {
			seg_pinactive(seg, addr, len, *ppp, rw, segvn_reclaim);
		}

		/*
		 * If someone is blocked while unmapping, we purge
		 * segment page cache and thus reclaim pplist synchronously
		 * without waiting for seg_pasync_thread. This speeds up
		 * unmapping in cases where munmap(2) is called, while
		 * raw async i/o is still in progress or where a thread
		 * exits on data fault in a multithreaded application.
		 */
		if (AS_ISUNMAPWAIT(seg->s_as) && (svd->softlockcnt > 0)) {
			/*
			 * Even if we grab segvn WRITER's lock or segp_slock
			 * here, there might be another thread which could've
			 * successfully performed lookup/insert just before
			 * we acquired the lock here.  So, grabbing either
			 * lock here is of not much use.  Until we devise
			 * a strategy at upper layers to solve the
			 * synchronization issues completely, we expect
			 * applications to handle this appropriately.
			 */
			segvn_purge(seg);
		}
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_UNLOCK_END,
			"segvn_pagelock: unlock seg %p addr %p", seg, addr);
		return (0);
	} else if (type == L_PAGERECLAIM) {
		VM_STAT_COND_ADD(seg->s_szc != 0, segvnvmstats.pagelock[1]);
		SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
		(void) segvn_reclaim(seg, addr, len, *ppp, rw);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_UNLOCK_END,
			"segvn_pagelock: reclaim seg %p addr %p", seg, addr);
		return (0);
	}

	if (seg->s_szc != 0) {
		VM_STAT_ADD(segvnvmstats.pagelock[2]);
		addr = lpgaddr;
		len = lpgeaddr - lpgaddr;
		npages = (len >> PAGESHIFT);
	}

	/*
	 * for now we only support pagelock to anon memory. We've to check
	 * protections for vnode objects and call into the vnode driver.
	 * That's too much for a fast path. Let the fault entry point handle it.
	 */
	if (svd->vp != NULL) {
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_MISS_END,
		    "segvn_pagelock: mapped vnode seg %p addr %p", seg, addr);
		*ppp = NULL;
		return (ENOTSUP);
	}

	/*
	 * if anonmap is not yet created, let the fault entry point populate it
	 * with anon ptrs.
	 */
	if ((amp = svd->amp) == NULL) {
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_MISS_END,
		    "segvn_pagelock: anonmap null seg %p addr %p", seg, addr);
		*ppp = NULL;
		return (EFAULT);
	}

	SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);

	/*
	 * we acquire segp_slock to prevent duplicate entries
	 * in seg_pcache
	 */
	mutex_enter(&svd->segp_slock);

	/*
	 * try to find pages in segment page cache
	 */
	pplist = seg_plookup(seg, addr, len, rw);
	if (pplist != NULL) {
		mutex_exit(&svd->segp_slock);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		*ppp = pplist + adjustpages;
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_HIT_END,
			"segvn_pagelock: cache hit seg %p addr %p", seg, addr);
		return (0);
	}

	if (rw == S_READ) {
		protchk = PROT_READ;
	} else {
		protchk = PROT_WRITE;
	}

	if (svd->pageprot == 0) {
		if ((svd->prot & protchk) == 0) {
			mutex_exit(&svd->segp_slock);
			error = EFAULT;
			goto out;
		}
	} else {
		/*
		 * check page protections
		 */
		for (a = addr; a < addr + len; a += PAGESIZE) {
			struct vpage *vp;

			vp = &svd->vpage[seg_page(seg, a)];
			if ((VPP_PROT(vp) & protchk) == 0) {
				mutex_exit(&svd->segp_slock);
				error = EFAULT;
				goto out;
			}
		}
	}

	mutex_enter(&freemem_lock);
	if (availrmem < tune.t_minarmem + npages) {
		mutex_exit(&freemem_lock);
		mutex_exit(&svd->segp_slock);
		error = ENOMEM;
		goto out;
	} else {
		svd->softlockcnt += npages;
		availrmem -= npages;
		segvn_pages_locked += npages;
	}
	mutex_exit(&freemem_lock);

	pplist = kmem_alloc(sizeof (page_t *) * npages, KM_SLEEP);
	pl = pplist;
	*ppp = pplist + adjustpages;

	page = seg_page(seg, addr);
	anon_index = svd->anon_index + page;

	ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
	for (a = addr; a < addr + len; a += PAGESIZE, anon_index++) {
		struct anon *ap;
		struct vnode *vp;
		u_offset_t off;
		anon_sync_obj_t cookie;

		anon_array_enter(amp, anon_index, &cookie);
		ap = anon_get_ptr(amp->ahp, anon_index);
		if (ap == NULL) {
			anon_array_exit(&cookie);
			break;
		} else {
			/*
			 * We must never use seg_pcache for COW pages
			 * because we might end up with original page still
			 * lying in seg_pcache even after private page is
			 * created. This leads to data corruption as
			 * aio_write refers to the page still in cache
			 * while all other accesses refer to the private
			 * page.
			 */
			if (ap->an_refcnt != 1) {
				anon_array_exit(&cookie);
				break;
			}
		}
		swap_xlate(ap, &vp, &off);
		anon_array_exit(&cookie);

		pp = page_lookup_nowait(vp, off, SE_SHARED);
		if (pp == NULL) {
			break;
		}
		*pplist++ = pp;
	}
	ANON_LOCK_EXIT(&amp->a_rwlock);

	if (a >= addr + len) {
		(void) seg_pinsert(seg, addr, len, pl, rw, SEGP_ASYNC_FLUSH,
			segvn_reclaim);
		mutex_exit(&svd->segp_slock);
		SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
		TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_FILL_END,
		    "segvn_pagelock: cache fill seg %p addr %p", seg, addr);
		return (0);
	}

	mutex_exit(&svd->segp_slock);
	error = EFAULT;
	pplist = pl;
	np = ((uintptr_t)(a - addr)) >> PAGESHIFT;
	while (np > (uint_t)0) {
		page_unlock(*pplist);
		np--;
		pplist++;
	}
	kmem_free(pl, sizeof (page_t *) * npages);
	mutex_enter(&freemem_lock);
	svd->softlockcnt -= npages;
	availrmem += npages;
	segvn_pages_locked -= npages;
	mutex_exit(&freemem_lock);
	if (svd->softlockcnt <= 0) {
		if (AS_ISUNMAPWAIT(seg->s_as)) {
			mutex_enter(&seg->s_as->a_contents);
			if (AS_ISUNMAPWAIT(seg->s_as)) {
				AS_CLRUNMAPWAIT(seg->s_as);
				cv_broadcast(&seg->s_as->a_cv);
			}
			mutex_exit(&seg->s_as->a_contents);
		}
	}

out:
	SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);
	*ppp = NULL;
	TRACE_2(TR_FAC_PHYSIO, TR_PHYSIO_SEGVN_MISS_END,
		"segvn_pagelock: cache miss seg %p addr %p", seg, addr);
	return (error);
}

/*
 * purge any cached pages in the I/O page cache
 */
static void
segvn_purge(struct seg *seg)
{
	seg_ppurge(seg);
}

static int
segvn_reclaim(struct seg *seg, caddr_t addr, size_t len, struct page **pplist,
	enum seg_rw rw)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	pgcnt_t np, npages;
	struct page **pl;

#ifdef lint
	addr = addr;
#endif

	npages = np = (len >> PAGESHIFT);
	ASSERT(npages);
	pl = pplist;
	if (seg->s_szc != 0) {
		size_t pgsz = page_get_pagesize(seg->s_szc);
		if (!IS_P2ALIGNED(addr, pgsz) || !IS_P2ALIGNED(len, pgsz)) {
			panic("segvn_reclaim: unaligned addr or len");
			/*NOTREACHED*/
		}
	}

	while (np > (uint_t)0) {
		if (rw == S_WRITE) {
			hat_setrefmod(*pplist);
		} else {
			hat_setref(*pplist);
		}
		page_unlock(*pplist);
		np--;
		pplist++;
	}
	kmem_free(pl, sizeof (page_t *) * npages);

	mutex_enter(&freemem_lock);
	availrmem += npages;
	segvn_pages_locked -= npages;
	svd->softlockcnt -= npages;
	mutex_exit(&freemem_lock);
	if (svd->softlockcnt <= 0) {
		if (AS_ISUNMAPWAIT(seg->s_as)) {
			mutex_enter(&seg->s_as->a_contents);
			if (AS_ISUNMAPWAIT(seg->s_as)) {
				AS_CLRUNMAPWAIT(seg->s_as);
				cv_broadcast(&seg->s_as->a_cv);
			}
			mutex_exit(&seg->s_as->a_contents);
		}
	}
	return (0);
}
/*
 * get a memory ID for an addr in a given segment
 *
 * XXX only creates PAGESIZE pages if anon slots are not initialized.
 * At fault time they will be relocated into larger pages.
 */
static int
segvn_getmemid(struct seg *seg, caddr_t addr, memid_t *memidp)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct anon 	*ap = NULL;
	ulong_t		anon_index;
	struct anon_map	*amp;
	anon_sync_obj_t cookie;

	if (svd->type == MAP_PRIVATE) {
		memidp->val[0] = (uintptr_t)seg->s_as;
		memidp->val[1] = (uintptr_t)addr;
		return (0);
	}

	if (svd->type == MAP_SHARED) {
		if (svd->vp) {
			memidp->val[0] = (uintptr_t)svd->vp;
			memidp->val[1] = (u_longlong_t)svd->offset +
			    (uintptr_t)(addr - seg->s_base);
			return (0);
		} else {

			SEGVN_LOCK_ENTER(seg->s_as, &svd->lock, RW_READER);
			if ((amp = svd->amp) != NULL) {
				anon_index = svd->anon_index +
				    seg_page(seg, addr);
			}
			SEGVN_LOCK_EXIT(seg->s_as, &svd->lock);

			ASSERT(amp != NULL);

			ANON_LOCK_ENTER(&amp->a_rwlock, RW_READER);
			anon_array_enter(amp, anon_index, &cookie);
			ap = anon_get_ptr(amp->ahp, anon_index);
			if (ap == NULL) {
				page_t		*pp;

				pp = anon_zero(seg, addr, &ap, svd->cred);
				if (pp == NULL) {
					anon_array_exit(&cookie);
					ANON_LOCK_EXIT(&amp->a_rwlock);
					return (ENOMEM);
				}
				ASSERT(anon_get_ptr(amp->ahp, anon_index)
								== NULL);
				(void) anon_set_ptr(amp->ahp, anon_index,
				    ap, ANON_SLEEP);
				page_unlock(pp);
			}

			anon_array_exit(&cookie);
			ANON_LOCK_EXIT(&amp->a_rwlock);

			memidp->val[0] = (uintptr_t)ap;
			memidp->val[1] = (uintptr_t)addr & PAGEOFFSET;
			return (0);
		}
	}
	return (EINVAL);
}

static int
sameprot(struct seg *seg, caddr_t a, size_t len)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vpage;
	spgcnt_t pages = btop(len);
	uint_t prot;

	if (svd->pageprot == 0)
		return (1);

	ASSERT(svd->vpage != NULL);

	vpage = &svd->vpage[seg_page(seg, a)];
	prot = VPP_PROT(vpage);
	vpage++;
	pages--;
	while (pages-- > 0) {
		if (prot != VPP_PROT(vpage))
			return (0);
		vpage++;
	}
	return (1);
}

/*
 * Get memory allocation policy info for specified address in given segment
 */
static lgrp_mem_policy_info_t *
segvn_getpolicy(struct seg *seg, caddr_t addr)
{
	struct anon_map		*amp;
	ulong_t			anon_index;
	lgrp_mem_policy_info_t	*policy_info;
	struct segvn_data	*svn_data;
	u_offset_t		vn_off;
	vnode_t			*vp;

	ASSERT(seg != NULL);

	svn_data = (struct segvn_data *)seg->s_data;
	if (svn_data == NULL)
		return (NULL);

	/*
	 * Get policy info for private or shared memory
	 */
	if (svn_data->type != MAP_SHARED)
		policy_info = &svn_data->policy_info;
	else {
		amp = svn_data->amp;
		anon_index = svn_data->anon_index + seg_page(seg, addr);
		vp = svn_data->vp;
		vn_off = svn_data->offset + (uintptr_t)(addr - seg->s_base);
		policy_info = lgrp_shm_policy_get(amp, anon_index, vp, vn_off);
	}

	return (policy_info);
}

/*ARGSUSED*/
static int
segvn_capable(struct seg *seg, segcapability_t capability)
{
	return (0);
}