458 lines
11 KiB
C
458 lines
11 KiB
C
/* $NetBSD: uvm_anon.c,v 1.63 2013/10/25 20:08:11 martin Exp $ */
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/*
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* Copyright (c) 1997 Charles D. Cranor and Washington University.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* uvm_anon.c: uvm anon ops
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.63 2013/10/25 20:08:11 martin Exp $");
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#include "opt_uvmhist.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/pool.h>
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#include <sys/kernel.h>
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#include <uvm/uvm.h>
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#include <uvm/uvm_swap.h>
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#include <uvm/uvm_pdpolicy.h>
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static struct pool_cache uvm_anon_cache;
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static int uvm_anon_ctor(void *, void *, int);
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void
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uvm_anon_init(void)
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{
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pool_cache_bootstrap(&uvm_anon_cache, sizeof(struct vm_anon), 0, 0,
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PR_LARGECACHE, "anonpl", NULL, IPL_NONE, uvm_anon_ctor,
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NULL, NULL);
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}
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static int
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uvm_anon_ctor(void *arg, void *object, int flags)
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{
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struct vm_anon *anon = object;
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anon->an_ref = 0;
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anon->an_lock = NULL;
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anon->an_page = NULL;
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#if defined(VMSWAP)
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anon->an_swslot = 0;
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#endif
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return 0;
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}
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/*
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* uvm_analloc: allocate a new anon.
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*
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* => anon will have no lock associated.
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*/
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struct vm_anon *
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uvm_analloc(void)
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{
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struct vm_anon *anon;
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anon = pool_cache_get(&uvm_anon_cache, PR_NOWAIT);
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if (anon) {
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KASSERT(anon->an_ref == 0);
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KASSERT(anon->an_lock == NULL);
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KASSERT(anon->an_page == NULL);
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#if defined(VMSWAP)
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KASSERT(anon->an_swslot == 0);
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#endif
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anon->an_ref = 1;
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}
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return anon;
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}
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/*
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* uvm_anon_dispose: free any resident page or swap resources of anon.
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*
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* => anon must be removed from the amap (if anon was in an amap).
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* => amap must be locked; we may drop and re-acquire the lock here.
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*/
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static bool
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uvm_anon_dispose(struct vm_anon *anon)
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{
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struct vm_page *pg = anon->an_page;
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UVMHIST_FUNC("uvm_anon_dispose"); UVMHIST_CALLED(maphist);
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UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0);
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KASSERT(mutex_owned(anon->an_lock));
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/*
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* If there is a resident page and it is loaned, then anon may not
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* own it. Call out to uvm_anon_lockloanpg() to identify and lock
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* the real owner of the page.
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*/
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if (pg && pg->loan_count) {
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KASSERT(anon->an_lock != NULL);
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pg = uvm_anon_lockloanpg(anon);
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}
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/*
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* Dispose the page, if it is resident.
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*/
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if (pg) {
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KASSERT(anon->an_lock != NULL);
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/*
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* If the page is owned by a UVM object (now locked),
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* then kill the loan on the page rather than free it,
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* and release the object lock.
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*/
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if (pg->uobject) {
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mutex_enter(&uvm_pageqlock);
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KASSERT(pg->loan_count > 0);
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pg->loan_count--;
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pg->uanon = NULL;
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mutex_exit(&uvm_pageqlock);
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mutex_exit(pg->uobject->vmobjlock);
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} else {
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/*
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* If page has no UVM object, then anon is the owner,
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* and it is already locked.
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*/
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KASSERT((pg->flags & PG_RELEASED) == 0);
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pmap_page_protect(pg, VM_PROT_NONE);
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/*
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* If the page is busy, mark it as PG_RELEASED, so
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* that uvm_anon_release(9) would release it later.
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*/
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if (pg->flags & PG_BUSY) {
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pg->flags |= PG_RELEASED;
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mutex_obj_hold(anon->an_lock);
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return false;
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}
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mutex_enter(&uvm_pageqlock);
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uvm_pagefree(pg);
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mutex_exit(&uvm_pageqlock);
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UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: "
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"freed now!", anon, pg, 0, 0);
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}
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}
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#if defined(VMSWAP)
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if (pg == NULL && anon->an_swslot > 0) {
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/* This page is no longer only in swap. */
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mutex_enter(&uvm_swap_data_lock);
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KASSERT(uvmexp.swpgonly > 0);
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uvmexp.swpgonly--;
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mutex_exit(&uvm_swap_data_lock);
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}
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#endif
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/*
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* Free any swap resources, leave a page replacement hint.
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*/
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uvm_anon_dropswap(anon);
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uvmpdpol_anfree(anon);
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UVMHIST_LOG(maphist,"<- done!",0,0,0,0);
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return true;
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}
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/*
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* uvm_anon_free: free a single anon.
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*
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* => anon must be already disposed.
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*/
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void
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uvm_anon_free(struct vm_anon *anon)
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{
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KASSERT(anon->an_ref == 0);
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KASSERT(anon->an_lock == NULL);
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KASSERT(anon->an_page == NULL);
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#if defined(VMSWAP)
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KASSERT(anon->an_swslot == 0);
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#endif
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pool_cache_put(&uvm_anon_cache, anon);
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}
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/*
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* uvm_anon_freelst: free a linked list of anon structures.
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*
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* => anon must be locked, we will unlock it.
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*/
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void
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uvm_anon_freelst(struct vm_amap *amap, struct vm_anon *anonlst)
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{
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struct vm_anon *anon;
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struct vm_anon **anonp = &anonlst;
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KASSERT(mutex_owned(amap->am_lock));
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while ((anon = *anonp) != NULL) {
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if (!uvm_anon_dispose(anon)) {
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/* Do not free this anon. */
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*anonp = anon->an_link;
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/* Note: clears an_ref as well. */
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anon->an_link = NULL;
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} else {
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anonp = &anon->an_link;
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}
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}
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amap_unlock(amap);
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while (anonlst) {
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anon = anonlst->an_link;
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/* Note: clears an_ref as well. */
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anonlst->an_link = NULL;
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anonlst->an_lock = NULL;
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uvm_anon_free(anonlst);
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anonlst = anon;
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}
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}
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/*
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* uvm_anon_lockloanpg: given a locked anon, lock its resident page owner.
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*
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* => anon is locked by caller
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* => on return: anon is locked
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* if there is a resident page:
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* if it has a uobject, it is locked by us
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* if it is ownerless, we take over as owner
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* we return the resident page (it can change during
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* this function)
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* => note that the only time an anon has an ownerless resident page
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* is if the page was loaned from a uvm_object and the uvm_object
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* disowned it
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* => this only needs to be called when you want to do an operation
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* on an anon's resident page and that page has a non-zero loan
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* count.
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*/
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struct vm_page *
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uvm_anon_lockloanpg(struct vm_anon *anon)
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{
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struct vm_page *pg;
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bool locked = false;
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KASSERT(mutex_owned(anon->an_lock));
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/*
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* loop while we have a resident page that has a non-zero loan count.
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* if we successfully get our lock, we will "break" the loop.
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* note that the test for pg->loan_count is not protected -- this
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* may produce false positive results. note that a false positive
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* result may cause us to do more work than we need to, but it will
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* not produce an incorrect result.
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*/
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while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) {
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/*
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* quickly check to see if the page has an object before
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* bothering to lock the page queues. this may also produce
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* a false positive result, but that's ok because we do a real
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* check after that.
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*/
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if (pg->uobject) {
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mutex_enter(&uvm_pageqlock);
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if (pg->uobject) {
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locked =
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mutex_tryenter(pg->uobject->vmobjlock);
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} else {
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/* object disowned before we got PQ lock */
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locked = true;
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}
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mutex_exit(&uvm_pageqlock);
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/*
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* if we didn't get a lock (try lock failed), then we
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* toggle our anon lock and try again
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*/
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if (!locked) {
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/*
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* someone locking the object has a chance to
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* lock us right now
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*
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* XXX Better than yielding but inadequate.
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*/
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kpause("livelock", false, 1, anon->an_lock);
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continue;
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}
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}
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/*
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* If page is un-owned i.e. the object dropped its ownership,
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* then we have to take the ownership.
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*/
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if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) {
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mutex_enter(&uvm_pageqlock);
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pg->pqflags |= PQ_ANON;
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pg->loan_count--;
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mutex_exit(&uvm_pageqlock);
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}
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break;
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}
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return pg;
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}
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#if defined(VMSWAP)
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/*
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* uvm_anon_pagein: fetch an anon's page.
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*
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* => anon must be locked, and is unlocked upon return.
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* => returns true if pagein was aborted due to lack of memory.
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*/
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bool
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uvm_anon_pagein(struct vm_amap *amap, struct vm_anon *anon)
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{
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struct vm_page *pg;
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struct uvm_object *uobj;
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KASSERT(mutex_owned(anon->an_lock));
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KASSERT(anon->an_lock == amap->am_lock);
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/*
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* Get the page of the anon.
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*/
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switch (uvmfault_anonget(NULL, amap, anon)) {
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case 0:
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/* Success - we have the page. */
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KASSERT(mutex_owned(anon->an_lock));
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break;
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case EIO:
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case ERESTART:
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/*
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* Nothing more to do on errors. ERESTART means that the
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* anon was freed.
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*/
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return false;
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default:
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return true;
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}
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/*
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* Mark the page as dirty, clear its swslot and un-busy it.
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*/
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pg = anon->an_page;
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uobj = pg->uobject;
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if (anon->an_swslot > 0) {
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uvm_swap_free(anon->an_swslot, 1);
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}
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anon->an_swslot = 0;
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pg->flags &= ~PG_CLEAN;
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/*
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* Deactivate the page (to put it on a page queue).
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*/
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mutex_enter(&uvm_pageqlock);
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if (pg->wire_count == 0) {
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uvm_pagedeactivate(pg);
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}
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mutex_exit(&uvm_pageqlock);
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if (pg->flags & PG_WANTED) {
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pg->flags &= ~PG_WANTED;
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wakeup(pg);
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}
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mutex_exit(anon->an_lock);
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if (uobj) {
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mutex_exit(uobj->vmobjlock);
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}
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return false;
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}
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/*
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* uvm_anon_dropswap: release any swap resources from this anon.
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*
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* => anon must be locked or have a reference count of 0.
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*/
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void
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uvm_anon_dropswap(struct vm_anon *anon)
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{
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UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist);
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if (anon->an_swslot == 0)
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return;
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UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x",
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anon, anon->an_swslot, 0, 0);
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uvm_swap_free(anon->an_swslot, 1);
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anon->an_swslot = 0;
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}
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#endif
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/*
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* uvm_anon_release: release an anon and its page.
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*
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* => anon should not have any references.
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* => anon must be locked.
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*/
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void
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uvm_anon_release(struct vm_anon *anon)
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{
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struct vm_page *pg = anon->an_page;
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bool success __diagused;
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KASSERT(mutex_owned(anon->an_lock));
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KASSERT(pg != NULL);
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KASSERT((pg->flags & PG_RELEASED) != 0);
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KASSERT((pg->flags & PG_BUSY) != 0);
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KASSERT(pg->uobject == NULL);
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KASSERT(pg->uanon == anon);
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KASSERT(pg->loan_count == 0);
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KASSERT(anon->an_ref == 0);
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mutex_enter(&uvm_pageqlock);
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uvm_pagefree(pg);
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mutex_exit(&uvm_pageqlock);
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KASSERT(anon->an_page == NULL);
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/* dispose should succeed as no one can reach this anon anymore. */
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success = uvm_anon_dispose(anon);
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KASSERT(success);
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mutex_exit(anon->an_lock);
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/* Note: extra reference is held for PG_RELEASED case. */
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mutex_obj_free(anon->an_lock);
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anon->an_lock = NULL;
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uvm_anon_free(anon);
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}
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