xref: /illumos-gate/usr/src/uts/common/vm/seg_vn.c (revision c6f039c7)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1986, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2018 Joyent, Inc.
 * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
 */

/*	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.
 */

/*
 * 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/callb.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>
#include <sys/proc.h>
#include <sys/task.h>
#include <sys/project.h>
#include <sys/zone.h>
#include <sys/shm_impl.h>

/*
 * segvn_fault needs a temporary page list array.  To avoid calling kmem all
 * the time, it creates a small (PVN_GETPAGE_NUM entry) array and uses it if
 * it can.  In the rare case when this page list is not large enough, it
 * goes and gets a large enough array from kmem.
 *
 * This small page list array covers either 8 pages or 64kB worth of pages -
 * whichever is smaller.
 */
#define	PVN_MAX_GETPAGE_SZ	0x10000
#define	PVN_MAX_GETPAGE_NUM	0x8

#if PVN_MAX_GETPAGE_SZ > PVN_MAX_GETPAGE_NUM * PAGESIZE
#define	PVN_GETPAGE_SZ	ptob(PVN_MAX_GETPAGE_NUM)
#define	PVN_GETPAGE_NUM	PVN_MAX_GETPAGE_NUM
#else
#define	PVN_GETPAGE_SZ	PVN_MAX_GETPAGE_SZ
#define	PVN_GETPAGE_NUM	btop(PVN_MAX_GETPAGE_SZ)
#endif

/*
 * 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);
static int	segvn_inherit(struct seg *, caddr_t, size_t, uint_t);

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,
	segvn_inherit
};

/*
 * 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 */

size_t	segvn_pglock_comb_thrshld = (1UL << 16);	/* 64K */
size_t	segvn_pglock_comb_balign = (1UL << 16);		/* 64K */
uint_t	segvn_pglock_comb_bshift;
size_t	segvn_pglock_comb_palign;

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 size_t	segvn_count_swap_by_vpages(struct seg *);

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

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

static int segvn_demote_range(struct seg *, caddr_t, size_t, int, uint_t);
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 void segvn_hat_rgn_unload_callback(caddr_t, caddr_t, caddr_t,
    size_t, void *, u_offset_t);

static struct kmem_cache *segvn_cache;
static struct kmem_cache **segvn_szc_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[2];
	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->segfree_syncmtx, NULL, MUTEX_DEFAULT, NULL);
	svd->svn_trnext = svd->svn_trprev = 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->segfree_syncmtx);
}

/*ARGSUSED*/
static int
svntr_cache_constructor(void *buf, void *cdrarg, int kmflags)
{
	bzero(buf, sizeof (svntr_t));
	return (0);
}

/*
 * 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_anon_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;

int segvn_use_regions = 1;

/*
 * Segvn supports text replication optimization for NUMA platforms. Text
 * replica's are represented by anon maps (amp). There's one amp per text file
 * region per lgroup. A process chooses the amp for each of its text mappings
 * based on the lgroup assignment of its main thread (t_tid = 1). All
 * processes that want a replica on a particular lgroup for the same text file
 * mapping share the same amp. amp's are looked up in svntr_hashtab hash table
 * with vp,off,size,szc used as a key. Text replication segments are read only
 * MAP_PRIVATE|MAP_TEXT segments that map vnode. Replication is achieved by
 * forcing COW faults from vnode to amp and mapping amp pages instead of vnode
 * pages. Replication amp is assigned to a segment when it gets its first
 * pagefault. To handle main thread lgroup rehoming segvn_trasync_thread
 * rechecks periodically if the process still maps an amp local to the main
 * thread. If not async thread forces process to remap to an amp in the new
 * home lgroup of the main thread. Current text replication implementation
 * only provides the benefit to workloads that do most of their work in the
 * main thread of a process or all the threads of a process run in the same
 * lgroup. To extend text replication benefit to different types of
 * multithreaded workloads further work would be needed in the hat layer to
 * allow the same virtual address in the same hat to simultaneously map
 * different physical addresses (i.e. page table replication would be needed
 * for x86).
 *
 * amp pages are used instead of vnode pages as long as segment has a very
 * simple life cycle.  It's created via segvn_create(), handles S_EXEC
 * (S_READ) pagefaults and is fully unmapped.  If anything more complicated
 * happens such as protection is changed, real COW fault happens, pagesize is
 * changed, MC_LOCK is requested or segment is partially unmapped we turn off
 * text replication by converting the segment back to vnode only segment
 * (unmap segment's address range and set svd->amp to NULL).
 *
 * The original file can be changed after amp is inserted into
 * svntr_hashtab. Processes that are launched after the file is already
 * changed can't use the replica's created prior to the file change. To
 * implement this functionality hash entries are timestamped. Replica's can
 * only be used if current file modification time is the same as the timestamp
 * saved when hash entry was created. However just timestamps alone are not
 * sufficient to detect file modification via mmap(MAP_SHARED) mappings. We
 * deal with file changes via MAP_SHARED mappings differently. When writable
 * MAP_SHARED mappings are created to vnodes marked as executable we mark all
 * existing replica's for this vnode as not usable for future text
 * mappings. And we don't create new replica's for files that currently have
 * potentially writable MAP_SHARED mappings (i.e. vn_is_mapped(V_WRITE) is
 * true).
 */

#define	SEGVN_TEXTREPL_MAXBYTES_FACTOR	(20)
size_t	segvn_textrepl_max_bytes_factor = SEGVN_TEXTREPL_MAXBYTES_FACTOR;

static ulong_t			svntr_hashtab_sz = 512;
static svntr_bucket_t		*svntr_hashtab = NULL;
static struct kmem_cache	*svntr_cache;
static svntr_stats_t		*segvn_textrepl_stats;
static ksema_t 			segvn_trasync_sem;

int				segvn_disable_textrepl = 1;
size_t				textrepl_size_thresh = (size_t)-1;
size_t				segvn_textrepl_bytes = 0;
size_t				segvn_textrepl_max_bytes = 0;
clock_t				segvn_update_textrepl_interval = 0;
int				segvn_update_tr_time = 10;
int				segvn_disable_textrepl_update = 0;

static void segvn_textrepl(struct seg *);
static void segvn_textunrepl(struct seg *, int);
static void segvn_inval_trcache(vnode_t *);
static void segvn_trasync_thread(void);
static void segvn_trupdate_wakeup(void *);
static void segvn_trupdate(void);
static void segvn_trupdate_seg(struct seg *, segvn_data_t *, svntr_t *,
    ulong_t);

/*
 * 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) {
		szc = maxszc = page_num_pagesizes() - 1;
		if (szc == 0) {
			segvn_lpg_disable = 1;
		}
		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;
	}

	if (segvn_maxpgszc) {
		segvn_szc_cache = (struct kmem_cache **)kmem_alloc(
		    (segvn_maxpgszc + 1) * sizeof (struct kmem_cache *),
		    KM_SLEEP);
	}

	for (szc = 1; szc <= segvn_maxpgszc; szc++) {
		char	str[32];

		(void) sprintf(str, "segvn_szc_cache%d", szc);
		segvn_szc_cache[szc] = kmem_cache_create(str,
		    page_get_pagecnt(szc) * sizeof (page_t *), 0,
		    NULL, NULL, NULL, NULL, NULL, KMC_NODEBUG);
	}


	if (segvn_use_regions && !hat_supported(HAT_SHARED_REGIONS, NULL))
		segvn_use_regions = 0;

	/*
	 * For now shared regions and text replication segvn support
	 * are mutually exclusive. This is acceptable because
	 * currently significant benefit from text replication was
	 * only observed on AMD64 NUMA platforms (due to relatively
	 * small L2$ size) and currently we don't support shared
	 * regions on x86.
	 */
	if (segvn_use_regions && !segvn_disable_textrepl) {
		segvn_disable_textrepl = 1;
	}

#if defined(_LP64)
	if (lgrp_optimizations() && textrepl_size_thresh != (size_t)-1 &&
	    !segvn_disable_textrepl) {
		ulong_t i;
		size_t hsz = svntr_hashtab_sz * sizeof (svntr_bucket_t);

		svntr_cache = kmem_cache_create("svntr_cache",
		    sizeof (svntr_t), 0, svntr_cache_constructor, NULL,
		    NULL, NULL, NULL, 0);
		svntr_hashtab = kmem_zalloc(hsz, KM_SLEEP);
		for (i = 0; i < svntr_hashtab_sz; i++) {
			mutex_init(&svntr_hashtab[i].tr_lock,  NULL,
			    MUTEX_DEFAULT, NULL);
		}
		segvn_textrepl_max_bytes = ptob(physmem) /
		    segvn_textrepl_max_bytes_factor;
		segvn_textrepl_stats = kmem_zalloc(NCPU *
		    sizeof (svntr_stats_t), KM_SLEEP);
		sema_init(&segvn_trasync_sem, 0, NULL, SEMA_DEFAULT, NULL);
		(void) thread_create(NULL, 0, segvn_trasync_thread,
		    NULL, 0, &p0, TS_RUN, minclsyspri);
	}
#endif

	if (!ISP2(segvn_pglock_comb_balign) ||
	    segvn_pglock_comb_balign < PAGESIZE) {
		segvn_pglock_comb_balign = 1UL << 16; /* 64K */
	}
	segvn_pglock_comb_bshift = highbit(segvn_pglock_comb_balign) - 1;
	segvn_pglock_comb_palign = btop(segvn_pglock_comb_balign);
}

#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(), NULL);
		} 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 **segpp, void *argsp)
{
	struct seg *seg = *segpp;
	extern lgrp_mem_policy_t lgrp_mem_default_policy;
	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_default_policy;
	int use_rgn = 0;
	int trok = 0;

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

	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*/
	}

	if (a->type == MAP_PRIVATE && (a->flags & MAP_TEXT) &&
	    a->vp != NULL && a->prot == (PROT_USER | PROT_READ | PROT_EXEC) &&
	    segvn_use_regions) {
		use_rgn = 1;
	}

	/* 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->szc == AS_MAP_NO_LPOOB) ||
		    (a->amp != NULL && a->type == MAP_PRIVATE) ||
		    (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) {
				if (IS_SWAPFSVP(a->vp) || VN_ISKAS(a->vp)) {
					/*
					 * 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;
				}
			} else if (a->amp != NULL) {
				pgcnt_t anum = btopr(a->offset);
				pgcnt_t pgcnt = page_get_pagecnt(a->szc);
				if (!IS_P2ALIGNED(anum, pgcnt)) {
					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_zone(seg->s_size,
		    seg->s_as->a_proc->p_zone) == 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.
	 *
	 * Don't do it for segments that may use regions. It's currently a
	 * noop in the hat implementations anyway.
	 */
	if (!use_rgn) {
		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 != NULL) {
		error = VOP_ADDMAP(a->vp, a->offset & PAGEMASK,
		    seg->s_as, seg->s_base, seg->s_size, a->prot,
		    a->maxprot, a->type, cred, NULL);
		if (error) {
			if (swresv != 0) {
				anon_unresv_zone(swresv,
				    seg->s_as->a_proc->p_zone);
				TRACE_3(TR_FAC_VM, TR_ANON_PROC,
				    "anon proc:%p %lu %u", seg, swresv, 0);
			}
			crfree(cred);
			if (!use_rgn) {
				hat_unload(seg->s_as->a_hat, seg->s_base,
				    seg->s_size, HAT_UNLOAD_UNMAP);
			}
			return (error);
		}
		/*
		 * svntr_hashtab will be NULL if we support shared regions.
		 */
		trok = ((a->flags & MAP_TEXT) &&
		    (seg->s_size > textrepl_size_thresh ||
		    (a->flags & _MAP_TEXTREPL)) &&
		    lgrp_optimizations() && svntr_hashtab != NULL &&
		    a->type == MAP_PRIVATE && swresv == 0 &&
		    !(a->flags & MAP_NORESERVE) &&
		    seg->s_as != &kas && a->vp->v_type == VREG);

		ASSERT(!trok || !use_rgn);
	}

	/*
	 * MAP_NORESERVE mappings don't count towards the VSZ of a process
	 * until we fault the pages in.
	 */
	if ((a->vp == NULL || a->vp->v_type != VREG) &&
	    a->flags & MAP_NORESERVE) {
		seg->s_as->a_resvsize -= seg->s_size;
	}

	/*
	 * 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) or if we'll use text replication for this segment.
	 */
	if (a->amp == NULL && !use_rgn && !trok) {
		struct seg *pseg, *nseg;
		struct segvn_data *psvd, *nsvd;
		lgrp_mem_policy_t ppolicy, npolicy;
		uint_t	lgrp_mem_policy_flags = 0;

		/*
		 * 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)));
				/*
				 * Communicate out the newly concatenated
				 * segment as part of the result.
				 */
				*segpp = pseg;
				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)));
				/*
				 * Communicate out the newly concatenated
				 * segment as part of the result.
				 */
				*segpp = nseg;
				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->seg = seg;
	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;
	svd->softlockcnt_sbase = 0;
	svd->softlockcnt_send = 0;
	svd->svn_inz = 0;
	svd->rcookie = HAT_INVALID_REGION_COOKIE;
	svd->pageswap = 0;

	if (a->szc != 0 && a->vp != NULL) {
		segvn_setvnode_mpss(a->vp);
	}
	if (svd->type == MAP_SHARED && svd->vp != NULL &&
	    (svd->vp->v_flag & VVMEXEC) && (svd->prot & PROT_WRITE)) {
		ASSERT(vn_is_mapped(svd->vp, V_WRITE));
		segvn_inval_trcache(svd->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,
				    ANON_SLEEP);
				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++;
			if (a->szc > amp->a_szc) {
				amp->a_szc = a->szc;
			}
			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, ANON_SLEEP);
			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));

				ASSERT(use_rgn == 0);
				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);

	if (use_rgn) {
		ASSERT(!trok);
		ASSERT(svd->amp == NULL);
		svd->rcookie = hat_join_region(seg->s_as->a_hat, seg->s_base,
		    seg->s_size, (void *)svd->vp, svd->offset, svd->prot,
		    (uchar_t)seg->s_szc, segvn_hat_rgn_unload_callback,
		    HAT_REGION_TEXT);
	}

	ASSERT(!trok || !(svd->prot & PROT_WRITE));
	svd->tr_state = trok ? SEGVN_TR_INIT : SEGVN_TR_OFF;

	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 amp_cat == 1 then try and concat segments with anon maps
 */
static int
segvn_concat(struct seg *seg1, struct seg *seg2, int amp_cat)
{
	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));
	ASSERT(seg1->s_ops == seg2->s_ops);

	if (HAT_IS_REGION_COOKIE_VALID(svd1->rcookie) ||
	    HAT_IS_REGION_COOKIE_VALID(svd2->rcookie)) {
		return (-1);
	}

	/* 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) || svd1->softlockcnt_send > 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);
	}

	/*
	 * Don't concatenate if either segment uses text replication.
	 */
	if (svd1->tr_state != SEGVN_TR_OFF || svd2->tr_state != SEGVN_TR_OFF) {
		return (-1);
	}

	/*
	 * Fail early if we're not supposed to concatenate
	 * segments with non NULL amp.
	 */
	if (amp_cat == 0 && (amp1 != NULL || amp2 != NULL)) {
		return (-1);
	}

	if (svd1->vp == NULL && svd1->type == MAP_SHARED) {
		if (amp1 != amp2) {
			return (-1);
		}
		if (amp1 != NULL && svd1->anon_index + btop(seg1->s_size) !=
		    svd2->anon_index) {
			return (-1);
		}
		ASSERT(amp1 == NULL || amp1->refcnt >= 2);
	}

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

		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));
		} else {
			evp = nvpage + npages1;
			for (vp = nvpage; vp < evp; vp++) {
				VPP_SETPROT(vp, svd1->prot);
				VPP_SETADVICE(vp, svd1->advice);
			}
		}

		if (vpage2 != NULL) {
			bcopy(vpage2, nvpage + npages1, vpgtob(npages2));
		} else {
			evp = nvpage + npages1 + npages2;
			for (vp = nvpage + npages1; vp < evp; vp++) {
				VPP_SETPROT(vp, svd2->prot);
				VPP_SETADVICE(vp, svd2->advice);
			}
		}

		if (svd2->pageswap && (!svd1->pageswap && svd1->swresv)) {
			ASSERT(svd1->swresv == seg1->s_size);
			ASSERT(!(svd1->flags & MAP_NORESERVE));
			ASSERT(!(svd2->flags & MAP_NORESERVE));
			evp = nvpage + npages1;
			for (vp = nvpage; vp < evp; vp++) {
				VPP_SETSWAPRES(vp);
			}
		}

		if (svd1->pageswap && (!svd2->pageswap && svd2->swresv)) {
			ASSERT(svd2->swresv == seg2->s_size);
			ASSERT(!(svd1->flags & MAP_NORESERVE));
			ASSERT(!(svd2->flags & MAP_NORESERVE));
			vp = nvpage + npages1;
			evp = vp + npages2;
			for (; vp < evp; vp++) {
				VPP_SETSWAPRES(vp);
			}
		}
	}
	ASSERT((vpage1 != NULL || vpage2 != NULL) ||
	    (svd1->pageswap == 0 && svd2->pageswap == 0));

	/*
	 * If either segment has private pages, create a new merged anon
	 * array. If mergeing shared anon segments just decrement anon map's
	 * refcnt.
	 */
	if (amp1 != NULL && svd1->type == MAP_SHARED) {
		ASSERT(amp1 == amp2 && svd1->vp == NULL);
		ANON_LOCK_ENTER(&amp1->a_rwlock, RW_WRITER);
		ASSERT(amp1->refcnt >= 2);
		amp1->refcnt--;
		ANON_LOCK_EXIT(&amp1->a_rwlock);
		svd2->amp = NULL;
	} else if (amp1 != NULL || amp2 != NULL) {
		struct anon_hdr *nahp;
		struct anon_map *namp = NULL;
		size_t asize;

		ASSERT(svd1->type == MAP_PRIVATE);

		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;
		}
		if (svd2->pageswap) {
			svd1->pageswap = 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(struct seg *seg1, struct seg *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));

	if (HAT_IS_REGION_COOKIE_VALID(svd1->rcookie)) {
		return (-1);
	}

	/* 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 || svd1->softlockcnt_send > 0)
		return (-1);

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

	if (svd1->tr_state != SEGVN_TR_OFF) {
		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) {
		struct vpage *vp, *evp;
		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;

		vp = new_vpage + seg_pages(seg1);
		evp = vp + seg_pages(seg2);
		for (; vp < evp; vp++)
			VPP_SETPROT(vp, a->prot);
		if (svd1->pageswap && swresv) {
			ASSERT(!(svd1->flags & MAP_NORESERVE));
			ASSERT(swresv == seg2->s_size);
			vp = new_vpage + seg_pages(seg1);
			for (; vp < evp; vp++) {
				VPP_SETSWAPRES(vp);
			}
		}
	}
	ASSERT(svd1->vpage != NULL || svd1->pageswap == 0);
	size = seg2->s_size;
	seg_free(seg2);
	seg1->s_size += size;
	svd1->swresv += swresv;
	if (svd1->pageprot && (a->prot & PROT_WRITE) &&
	    svd1->type == MAP_SHARED && svd1->vp != NULL &&
	    (svd1->vp->v_flag & VVMEXEC)) {
		ASSERT(vn_is_mapped(svd1->vp, V_WRITE));
		segvn_inval_trcache(svd1->vp);
	}
	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));

	if (HAT_IS_REGION_COOKIE_VALID(svd2->rcookie)) {
		return (-1);
	}

	/* 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 || svd2->softlockcnt_sbase > 0)
		return (-1);
	/* vp == NULL implies zfod, offset doesn't matter */
	if (svd2->vp != NULL &&
	    (a->offset & PAGEMASK) + seg1->s_size != svd2->offset)
		return (-1);

	if (svd2->tr_state != SEGVN_TR_OFF) {
		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) {
		struct vpage *vp, *evp;
		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;

		vp = new_vpage;
		evp = vp + seg_pages(seg1);
		for (; vp < evp; vp++)
			VPP_SETPROT(vp, a->prot);
		if (svd2->pageswap && swresv) {
			ASSERT(!(svd2->flags & MAP_NORESERVE));
			ASSERT(swresv == seg1->s_size);
			vp = new_vpage;
			for (; vp < evp; vp++) {
				VPP_SETSWAPRES(vp);
			}
		}
	}
	ASSERT(svd2->vpage != NULL || svd2->pageswap == 0);
	size = seg1->s_size;
	seg_free(seg1);
	seg2->s_size += size;
	seg2->s_base -= size;
	svd2->offset -= size;
	svd2->swresv += swresv;
	if (svd2->pageprot && (a->prot & PROT_WRITE) &&
	    svd2->type == MAP_SHARED && svd2->vp != NULL &&
	    (svd2->vp->v_flag & VVMEXEC)) {
		ASSERT(vn_is_mapped(svd2->vp, V_WRITE));
		segvn_inval_trcache(svd2->vp);
	}
	return (0);
}

/*
 * Duplicate all the pages in the segment. This may break COW sharing for a
 * given page. If the page is marked with inherit zero set, then instead of
 * duplicating the page, we zero the page.
 */
static int
segvn_dup_pages(struct seg *seg, struct seg *newseg)
{
	int error;
	uint_t prot;
	page_t *pp;
	struct anon *ap, *newap;
	size_t i;
	caddr_t addr;

	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct segvn_data *newsvd = (struct segvn_data *)newseg->s_data;
	ulong_t old_idx = svd->anon_index;
	ulong_t new_idx = 0;

	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(svd->amp->ahp, old_idx)) != NULL) {
			struct vpage *vpp;

			vpp = &svd->vpage[seg_page(seg, addr)];

			/*
			 * 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(vpp) : svd->prot;

			/*
			 * Check whether we should zero this or dup it.
			 */
			if (svd->svn_inz == SEGVN_INZ_ALL ||
			    (svd->svn_inz == SEGVN_INZ_VPP &&
			    VPP_ISINHZERO(vpp))) {
				pp = anon_zero(newseg, addr, &newap,
				    newsvd->cred);
			} else {
				page_t *anon_pl[1+1];
				uint_t vpprot;
				error = anon_getpage(&ap, &vpprot, anon_pl,
				    PAGESIZE, seg, addr, S_READ, svd->cred);
				if (error != 0)
					return (error);

				pp = anon_private(&newap, newseg, addr, prot,
				    anon_pl[0], 0, newsvd->cred);
			}
			if (pp == NULL) {
				return (ENOMEM);
			}
			(void) anon_set_ptr(newsvd->amp->ahp, new_idx, newap,
			    ANON_SLEEP);
			page_unlock(pp);
		}
		addr += PAGESIZE;
		old_idx++;
		new_idx++;
	}

	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;
	size_t len;
	struct anon_map *amp;

	ASSERT(seg->s_as && AS_WRITE_HELD(seg->s_as));
	ASSERT(newseg->s_as->a_proc->p_parent == curproc);

	/*
	 * 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;

	newsvd->seg = newseg;
	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->svn_inz = svd->svn_inz;
	newsvd->swresv = svd->swresv;
	newsvd->pageswap = svd->pageswap;
	newsvd->flags = svd->flags;
	newsvd->softlockcnt = 0;
	newsvd->softlockcnt_sbase = 0;
	newsvd->softlockcnt_send = 0;
	newsvd->policy_info = svd->policy_info;
	newsvd->rcookie = HAT_INVALID_REGION_COOKIE;

	if ((amp = svd->amp) == NULL || svd->tr_state == SEGVN_TR_ON) {
		/*
		 * Not attaching to a shared anon object.
		 */
		ASSERT(!HAT_IS_REGION_COOKIE_VALID(svd->rcookie) ||
		    svd->tr_state == SEGVN_TR_OFF);
		if (svd->tr_state == SEGVN_TR_ON) {
			ASSERT(newsvd->vp != NULL && amp != NULL);
			newsvd->tr_state = SEGVN_TR_INIT;
		} else {
			newsvd->tr_state = svd->tr_state;
		}
		newsvd->amp = NULL;
		newsvd->anon_index = 0;
	} else {
		/* regions for now are only used on pure vnode segments */
		ASSERT(svd->rcookie == HAT_INVALID_REGION_COOKIE);
		ASSERT(svd->tr_state == SEGVN_TR_OFF);
		newsvd->tr_state = SEGVN_TR_OFF;
		if (svd->type == MAP_SHARED) {
			ASSERT(svd->svn_inz == SEGVN_INZ_NONE);
			newsvd->amp = amp;
			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,
			    ANON_SLEEP);
			newsvd->amp->a_szc = newseg->s_szc;
			newsvd->anon_index = 0;
			ASSERT(svd->svn_inz == SEGVN_INZ_NONE ||
			    svd->svn_inz == SEGVN_INZ_ALL ||
			    svd->svn_inz == SEGVN_INZ_VPP);

			/*
			 * 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.
			 *
			 * In addition, if any pages have been marked that they
			 * should be inherited as zero, then we immediately go
			 * ahead and break COW and zero them. In the case of a
			 * softlocked page that should be inherited zero, we
			 * break COW and just get a zero page.
			 */
retry:
			if (svd->softlockcnt ||
			    svd->svn_inz != SEGVN_INZ_NONE) {
				/*
				 * 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 (svd->softlockcnt && reclaim == 1) {
					segvn_purge(seg);
					reclaim = 0;
					goto retry;
				}

				error = segvn_dup_pages(seg, newseg);
				if (error != 0) {
					newsvd->vpage = NULL;
					goto out;
				}
			} 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, NULL);
	}
out:
	if (error == 0 && HAT_IS_REGION_COOKIE_VALID(svd->rcookie)) {
		ASSERT(newsvd->amp == NULL);
		ASSERT(newsvd->tr_state == SEGVN_TR_OFF);
		newsvd->rcookie = svd->rcookie;
		hat_dup_region(newseg->s_as->a_hat, newsvd->rcookie);
	}
	return (error);
}


/*
 * callback function to invoke free_vp_pages() for only those pages actually
 * processed by the HAT when a shared region is destroyed.
 */
extern int free_pages;

static void
segvn_hat_rgn_unload_callback(caddr_t saddr, caddr_t eaddr, caddr_t r_saddr,
    size_t r_size, void *r_obj, u_offset_t r_objoff)
{
	u_offset_t off;
	size_t len;
	vnode_t *vp = (vnode_t *)r_obj;

	ASSERT(eaddr > saddr);
	ASSERT(saddr >= r_saddr);
	ASSERT(saddr < r_saddr + r_size);
	ASSERT(eaddr > r_saddr);
	ASSERT(eaddr <= r_saddr + r_size);
	ASSERT(vp != NULL);

	if (!free_pages) {
		return;
	}

	len = eaddr - saddr;
	off = (saddr - r_saddr) + r_objoff;
	free_vp_pages(vp, off, len);
}

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

/*
 * This function determines the number of bytes of swap reserved by
 * a segment for which per-page accounting is present. It is used to
 * calculate the correct value of a segvn_data's swresv.
 */
static size_t
segvn_count_swap_by_vpages(struct seg *seg)
{
	struct segvn_data *svd = (struct segvn_data *)seg->s_data;
	struct vpage *vp, *evp;
	size_t nswappages = 0;

	ASSERT(svd->pageswap);
	ASSERT(svd->vpage != NULL);

	evp = &svd->vpage[seg_page(seg, seg->s_base + seg->s_size)];

	for (vp = svd->vpage; vp < evp; vp++) {
		if (VPP_ISSWAPRES(vp))
			nswappages++;
	}

	return (nswappages << PAGESHIFT);
}

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));

	/*
	 * 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) {
		ASSERT(svd->tr_state == SEGVN_TR_OFF);

		/*
		 * If this is shared segment non 0 softlockcnt
		 * means locked pages are still in use.
		 */
		if (svd->type == MAP_SHARED) {
			return (EAGAIN);
		}

		/*
		 * 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);
			if (HAT_IS_REGION_COOKIE_VALID(svd->rcookie)) {
				ASSERT(svd->amp == NULL);
				ASSERT(svd->tr_state == SEGVN_TR_OFF);
				hat_leave_region(seg->s_as->a_hat,
				    svd->rcookie, HAT_REGION_TEXT);
				svd->rcookie = HAT_INVALID_REGION_COOKIE;
				/*
				 * could pass a flag to segvn_demote_range()
				 * below to tell it not to do any unloads but
				 * this case is rare enough to not bother for
				 * now.
				 */
			} else if (svd->tr_state == SEGVN_TR_INIT) {
				svd->tr_state = SEGVN_TR_OFF;
			} else if (svd->tr_state == SEGVN_TR_ON) {
				ASSERT(svd->amp != NULL);
				segvn_textunrepl(seg, 1);
				ASSERT(svd->amp == NULL);
				ASSERT(svd->tr_state == SEGVN_TR_OFF);
			}
			VM_STAT_ADD(segvnvmstats.demoterange[0]);
			err = segvn_demote_range(seg, addr, len, SDR_END, 0);
			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, NULL);

		if (error == EAGAIN)
			return (error);
	}

	/*
	 * Remove any page locks set through this mapping.
	 * If text replication is not off no page locks could have been
	 * established via this mapping.
	 */
	if (svd->tr_state == SEGVN_TR_OFF) {
		(void) segvn_lockop(seg, addr, len, 0, MC_UNLOCK, NULL, 0);
	}

	if (HAT_IS_REGION_COOKIE_VALID(svd->rcookie)) {
		ASSERT(svd->amp == NULL);
		ASSERT(svd->tr_state == SEGVN_TR_OFF);
		ASSERT(svd->type == MAP_PRIVATE);
		hat_leave_region(seg->s_as->a_hat, svd->rcookie,
		    HAT_REGION_TEXT);
		svd->rcookie = HAT_INVALID_REGION_COOKIE;
	} else if (svd->tr_state == SEGVN_TR_ON) {
		ASSERT(svd->amp != NULL);
		ASSERT(svd->pageprot == 0 && !(svd->prot & PROT_WRITE));
		segvn_textunrepl(seg, 1);
		ASSERT(svd->amp == NULL && svd->tr_state == SEGVN_TR_OFF);
	} else {
		if (svd->tr_state != SEGVN_TR_OFF) {
			ASSERT(svd->tr_state == SEGVN_TR_INIT);
			svd->tr_state = SEGVN_TR_OFF;
		}
		/*
		 * 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);

		if (svd->type == MAP_SHARED && svd->vp != NULL &&
		    (svd->vp->v_flag & VVMEXEC) &&
		    ((svd->prot & PROT_WRITE) || svd->pageprot)) {
			segvn_inval_trcache(svd->vp);
		}
	}

	/*
	 * 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;
	ASSERT(amp == NULL || amp->a_szc >= seg->s_szc);

	/*
	 * 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) {
				/*
				 * Shared anon map is no longer in use. Before
				 * freeing its pages purge all entries from
				 * pcache that belong to this amp.
				 */
				if (svd->type == MAP_SHARED) {
					ASSERT(amp->refcnt == 1);
					ASSERT(svd->softlockcnt == 0);
					anonmap_purge(amp);
				}
				/*
				 * Free up now unused parts of anon_map array.
				 */
				if (amp->a_szc == seg->s_szc) {
					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);
					}
				} else {
					ASSERT(svd->type == MAP_SHARED);
					ASSERT(amp->a_szc > seg->s_szc);
					anon_shmap_free_pages(amp,
					    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_zone(len,
					    seg->s_as->a_proc->p_zone);
					amp->swresv -= len;
				}
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
			svd->anon_index += dpages;
		}
		if (svd->vp != NULL)
			svd->offset += len;

		seg->s_base += len;
		seg->s_size -= 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_zone(oswresv - svd->swresv,
				    seg->s_as->a_proc->p_zone);
				if (SEG_IS_PARTIAL_RESV(seg))
					seg->s_as->a_resvsize -= oswresv -
					    svd->swresv;
			} else {
				size_t unlen;

				if (svd->pageswap) {
					oswresv = svd->swresv;
					svd->swresv =
					    segvn_count_swap_by_vpages(seg);
					ASSERT(oswresv >= svd->swresv);
					unlen = oswresv - svd->swresv;
				} else {
					svd->swresv -= len;
					ASSERT(svd->swresv == seg->s_size);
					unlen = len;
				}
				anon_unresv_zone(unlen,
				    seg->s_as->a_proc->p_zone);
			}
			TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
			    seg, len, 0);
		}

		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.
				 */
				ulong_t an_idx = svd->anon_index + npages;

				/*
				 * Shared anon map is no longer in use. Before
				 * freeing its pages purge all entries from
				 * pcache that belong to this amp.
				 */
				if (svd->type == MAP_SHARED) {
					ASSERT(amp->refcnt == 1);
					ASSERT(svd->softlockcnt == 0);
					anonmap_purge(amp);
				}

				if (amp->a_szc == seg->s_szc) {
					if (seg->s_szc != 0) {
						anon_free_pages(amp->ahp,
						    an_idx, len,
						    seg->s_szc);
					} else {
						anon_free(amp->ahp, an_idx,
						    len);
					}
				} else {
					ASSERT(svd->type == MAP_SHARED);
					ASSERT(amp->a_szc > seg->s_szc);
					anon_shmap_free_pages(amp,
					    an_idx, len);
				}

				/*
				 * Unreserve swap space for the
				 * unmapped chunk of this segment in
				 * case it's MAP_SHARED
				 */
				if (svd->type == MAP_SHARED) {
					anon_unresv_zone(len,
					    seg->s_as->a_proc->p_zone);
					amp->swresv -= len;
				}
			}
			ANON_LOCK_EXIT(&amp->a_rwlock);
		}

		seg->s_size -= 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_zone(oswresv - svd->swresv,
				    seg->s_as->a_proc->p_zone);
				if (SEG_IS_PARTIAL_RESV(seg))
					seg->s_as->a_resvsize -= oswresv -
					    svd->swresv;
			} else {
				size_t unlen;

				if (svd->pageswap) {
					oswresv = svd->swresv;
					svd->swresv =
					    segvn_count_swap_by_vpages(seg);
					ASSERT(oswresv >= svd->swresv);
					unlen = oswresv - svd->swresv;
				} else {
					svd->swresv -= len;
					ASSERT(svd->swresv == seg->s_size);
					unlen = len;
				}
				anon_unresv_zone(unlen,
				    seg->s_as->a_proc->p_zone);
			}
			TRACE_3(TR_FAC_VM, TR_ANON_PROC,
			    "anon proc:%p %lu %u", seg, len, 0);
		}

		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->seg = nseg;
	nsvd->offset = svd->offset + (uintptr_t)(nseg->s_base - seg->s_base);
	nsvd->swresv = 0;
	nsvd->softlockcnt = 0;
	nsvd->softlockcnt_sbase = 0;
	nsvd->softlockcnt_send = 0;
	nsvd->svn_inz = svd->svn_inz;
	ASSERT(nsvd->rcookie == HAT_INVALID_REGION_COOKIE);

	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.
			 */
			ulong_t an_idx = svd->anon_index + opages;

			/*
			 * Shared anon map is no longer in use. Before
			 * freeing its pages purge all entries from
			 * pcache that belong to this amp.
			 */
			if (svd->type == MAP_SHARED) {
				ASSERT(amp->refcnt == 1);
				ASSERT(svd->softlockcnt == 0);
				anonmap_purge(amp);
			}

			if (amp->a_szc == seg->s_szc) {
				if (seg->s_szc != 0) {
					anon_free_pages(amp->ahp, an_idx, len,
					    seg->s_szc);
				} else {
					anon_free(amp->ahp, an_idx,
					    len);
				}
			} else {
				ASSERT(svd->type == MAP_SHARED);
				ASSERT(amp->a_szc > seg->s_szc);
				anon_shmap_free_pages(amp, an_idx, len);
			}

			/*
			 * Unreserve swap space for the
			 * unmapped chunk of this segment in
			 * case it's MAP_SHARED
			 */
			if (svd->type == MAP_SHARED) {
				anon_unresv_zone(len,
				    seg->s_as->a_proc->p_zone);
				amp->swresv -= len;
			}
		}
		nsvd->anon_index = svd->anon_index +
		    btop((uintptr_t)(nseg->s_base - seg->s_base));
		if (svd->type == MAP_SHARED) {
			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, ANON_SLEEP);
			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_zone(oswresv - (svd->swresv + nsvd->swresv),
			    seg->s_as->a_proc->p_zone);
			if (SEG_IS_PARTIAL_RESV(seg))
				seg->s_as->a_resvsize -= oswresv -
				    (svd->swresv + nsvd->swresv);
		} else {
			size_t unlen;

			if (svd->pageswap) {
				oswresv = svd->swresv;
				svd->swresv = segvn_count_swap_by_vpages(seg);
				nsvd->swresv = segvn_count_swap_by_vpages(nseg);
				ASSERT(oswresv >= (svd->swresv + nsvd->swresv));
				unlen = oswresv - (svd->swresv + nsvd->swresv);
			} else {
				if (seg->s_size + nseg->s_size + len !=
				    svd->swresv) {
					panic("segvn_unmap: cannot split "
					    "swap reservation");
					/*NOTREACHED*/
				}
				svd->swresv = seg->s_size;
				nsvd->swresv = nseg->s_size;
				unlen = len;
			}
			anon_unresv_zone(unlen,
			    seg->s_as->a_proc->p_zone);
		}
		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));
	ASSERT(svd->tr_state == SEGVN_TR_OFF);

	ASSERT(svd->rcookie == HAT_INVALID_REGION_COOKIE);

	/*
	 * 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);
		ASSERT(amp->a_szc >= seg->s_szc);
		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 map is no longer in use. Before
				 * freeing its pages purge all entries from
				 * pcache that belong to this amp.
				 */
				ASSERT(svd->softlockcnt == 0);
				anonmap_purge(amp);

				/*
				 * Shared - anon_free the entire
				 * anon_map's worth of stuff and
				 * release any swap reservation.
				 */
				if (amp->a_szc != 0) {
					anon_shmap_free_pages(amp, 0,
					    amp->size);
				} else {
					anon_free(amp->ahp, 0, amp->size);
				}
				if ((len = amp->swresv) != 0) {
					anon_unresv_zone(len,
					    seg->s_as->a_proc->p_zone);
					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_zone(svd->swresv,
		    seg->s_as->a_proc->p_zone);
		TRACE_3(TR_FAC_VM, TR_ANON_PROC, "anon proc:%p %lu %u",
		    seg, len, 0);
		if (SEG_IS_PARTIAL_RESV(seg))
			seg->s_as->a_resvsize -= svd->swresv;
		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->pageprot = 0;
	svd->pageadvice = 0;
	svd->pageswap = 0;
	svd->cred = NULL;

	/*
	 * Take segfree_syncmtx lock to let segvn_reclaim() finish if it's
	 * still working with this segment without holding as lock (in case
	 * it's called by pcache async thread).
	 */
	ASSERT(svd->softlockcnt == 0);
	mutex_enter(&svd->segfree_syncmtx);
	mutex_exit(&svd->segfree_syncmtx);

	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 = 0;
	struct anon_map *amp;
	struct anon *ap = NULL;

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

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

	if (HAT_IS_REGION_COOKIE_VALID(svd->rcookie)) {
		ASSERT(svd->tr_state == SEGVN_TR_OFF);
		hat_unlock_region(seg->s_as->a_hat, addr, len, svd->rcookie);
	} else {
		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);
	}
	ASSERT(svd->softlockcnt >= btop(len));
	if (!atomic_add_long_nv((ulong_t *)&svd->softlockcnt, -btop(len))) {
		/*
		 * 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 = 0;
	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);
	ASSERT(svd->tr_state != SEGVN_TR_INIT);

	/*
	 * 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) {
		atomic_inc_ulong((ulong_t *)&svd->softlockcnt);
	}

	/*
	 * 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_zone(ptob(1),
				    seg->s_as->a_proc->p_zone)) {
					atomic_add_long(&svd->swresv, ptob(1));
					atomic_add_long(&seg->s_as->a_resvsize,
					    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);

			ASSERT(pp->p_szc == 0);

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

			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.
			 *
			 * Usually testing and setting VPP_ISPPLOCK and
			 * VPP_SETPPLOCK requires holding the segvn lock as
			 * writer, but in this case all readers are
			 * serializing on the anon array lock.
			 */
			if (AS_ISPGLCK(seg->s_as) && vpage != NULL &&
			    (svd->flags & MAP_NORESERVE) &&
			    !VPP_ISPPLOCK(vpage)) {
				proc_t *p = seg->s_as->a_proc;
				ASSERT(svd->type == MAP_PRIVATE);
				mutex_enter(&p->p_lock);
				if (rctl_incr_locked_mem(p, NULL, PAGESIZE,
				    1) == 0) {
					claim = VPP_PROT(vpage) & PROT_WRITE;
					if (page_pp_lock(pp, claim, 0)) {
						VPP_SETPPLOCK(vpage);
					} else {
						rctl_decr_locked_mem(p, NULL,
						    PAGESIZE, 1);
					}
				}
				mutex_exit(&p->p_lock);
			}

			ASSERT(svd->rcookie == HAT_INVALID_REGION_COOKIE);
			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.
	 */

	if (brkcow) {
		ASSERT(svd->tr_state == SEGVN_TR_OFF);
		cow = !(vpprot & PROT_WRITE);
	} else if (svd->tr_state == SEGVN_TR_ON) {
		/*
		 * If we are doing text replication COW on first touch.
		 */
		ASSERT(amp != NULL);
		ASSERT(svd->vp != NULL);
		ASSERT(rw != S_WRITE);
		cow = (ap == NULL);
	} else {
		cow = 0;
	}

	/*
	 * If not a copy-on-write case load the translation
	 * and return.
	 */
	if (cow == 0) {

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

		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;
		}

		ASSERT(svd->rcookie == HAT_INVALID_REGION_COOKIE ||
		    (!svd->pageprot && svd->prot == (prot & vpprot)));
		ASSERT(amp == NULL ||
		    svd->rcookie == HAT_INVALID_REGION_COOKIE);
		hat_memload_region(hat, addr, opp, prot & vpprot, hat_flag,
		    svd->rcookie);

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

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

	ASSERT(svd->rcookie == HAT_INVALID_REGION_COOKIE);

	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 (