366 lines
9.1 KiB
C
366 lines
9.1 KiB
C
/* $NetBSD: uvm_anon.c,v 1.4 1999/09/12 01:17:34 chs Exp $ */
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/*
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Charles D. Cranor and
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* Washington University.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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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 "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/proc.h>
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#include <sys/malloc.h>
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#include <sys/pool.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_kern.h>
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#include <uvm/uvm.h>
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#include <uvm/uvm_swap.h>
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/*
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* allocate anons
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*/
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void
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uvm_anon_init()
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{
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struct vm_anon *anon;
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int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */
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int lcv;
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/*
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* Allocate the initial anons.
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*/
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anon = (struct vm_anon *)uvm_km_alloc(kernel_map,
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sizeof(*anon) * nanon);
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if (anon == NULL) {
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printf("uvm_anon_init: can not allocate %d anons\n", nanon);
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panic("uvm_anon_init");
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}
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memset(anon, 0, sizeof(*anon) * nanon);
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uvm.afree = NULL;
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uvmexp.nanon = uvmexp.nfreeanon = nanon;
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for (lcv = 0 ; lcv < nanon ; lcv++) {
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anon[lcv].u.an_nxt = uvm.afree;
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uvm.afree = &anon[lcv];
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simple_lock_init(&uvm.afree->an_lock);
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}
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simple_lock_init(&uvm.afreelock);
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}
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/*
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* add some more anons to the free pool. called when we add
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* more swap space.
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*/
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void
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uvm_anon_add(pages)
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int pages;
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{
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struct vm_anon *anon;
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int lcv;
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anon = (struct vm_anon *)uvm_km_alloc(kernel_map,
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sizeof(*anon) * pages);
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/* XXX Should wait for VM to free up. */
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if (anon == NULL) {
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printf("uvm_anon_add: can not allocate %d anons\n", pages);
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panic("uvm_anon_add");
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}
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simple_lock(&uvm.afreelock);
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memset(anon, 0, sizeof(*anon) * pages);
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uvmexp.nanon += pages;
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uvmexp.nfreeanon += pages;
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for (lcv = 0; lcv < pages; lcv++) {
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simple_lock_init(&anon->an_lock);
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anon[lcv].u.an_nxt = uvm.afree;
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uvm.afree = &anon[lcv];
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simple_lock_init(&uvm.afree->an_lock);
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}
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simple_unlock(&uvm.afreelock);
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}
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/*
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* allocate an anon
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*/
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struct vm_anon *
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uvm_analloc()
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{
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struct vm_anon *a;
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simple_lock(&uvm.afreelock);
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a = uvm.afree;
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if (a) {
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uvm.afree = a->u.an_nxt;
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uvmexp.nfreeanon--;
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a->an_ref = 1;
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a->an_swslot = 0;
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a->u.an_page = NULL; /* so we can free quickly */
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}
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simple_unlock(&uvm.afreelock);
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return(a);
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}
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/*
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* uvm_anfree: free a single anon structure
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*
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* => caller must remove anon from its amap before calling (if it was in
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* an amap).
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* => anon must be unlocked and have a zero reference count.
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* => we may lock the pageq's.
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*/
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void
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uvm_anfree(anon)
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struct vm_anon *anon;
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{
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struct vm_page *pg;
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UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist);
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UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0);
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/*
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* get page
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*/
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pg = anon->u.an_page;
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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_lockpage() to ensure the real owner
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* of the page has been identified and locked.
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*/
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if (pg && pg->loan_count)
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pg = uvm_anon_lockloanpg(anon);
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/*
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* if we have a resident page, we must dispose of it before freeing
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* the anon.
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*/
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if (pg) {
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/*
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* if the page is owned by a uobject (now locked), then we must
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* kill the loan on the page rather than free it.
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*/
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if (pg->uobject) {
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/* kill loan */
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uvm_lock_pageq();
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#ifdef DIAGNOSTIC
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if (pg->loan_count < 1)
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panic("uvm_anfree: obj owned page "
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"with no loan count");
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#endif
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pg->loan_count--;
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pg->uanon = NULL;
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uvm_unlock_pageq();
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simple_unlock(&pg->uobject->vmobjlock);
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} else {
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/*
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* page has no uobject, so we must be the owner of it.
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*
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* if page is busy then we just mark it as released
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* (who ever has it busy must check for this when they
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* wake up). if the page is not busy then we can
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* free it now.
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*/
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if ((pg->flags & PG_BUSY) != 0) {
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/* tell them to dump it when done */
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pg->flags |= PG_RELEASED;
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UVMHIST_LOG(maphist,
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" anon 0x%x, page 0x%x: BUSY (released!)",
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anon, pg, 0, 0);
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return;
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}
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pmap_page_protect(pg, VM_PROT_NONE);
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uvm_lock_pageq(); /* lock out pagedaemon */
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uvm_pagefree(pg); /* bye bye */
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uvm_unlock_pageq(); /* free the daemon */
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UVMHIST_LOG(maphist," anon 0x%x, page 0x%x: freed now!",
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anon, pg, 0, 0);
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}
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}
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/*
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* free any swap resources.
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*/
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uvm_anon_dropswap(anon);
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/*
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* now that we've stripped the data areas from the anon, free the anon
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* itself!
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*/
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simple_lock(&uvm.afreelock);
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anon->u.an_nxt = uvm.afree;
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uvm.afree = anon;
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uvmexp.nfreeanon++;
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simple_unlock(&uvm.afreelock);
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UVMHIST_LOG(maphist,"<- done!",0,0,0,0);
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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(anon)
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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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}
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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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if (anon->u.an_page == NULL) {
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/* this page is no longer only in swap. */
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simple_lock(&uvm.swap_data_lock);
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uvmexp.swpgonly--;
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simple_unlock(&uvm.swap_data_lock);
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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
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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(anon)
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struct vm_anon *anon;
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{
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struct vm_page *pg;
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boolean_t locked = FALSE;
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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->u.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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* XXX: quick check -- worth it? need volatile?
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*/
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if (pg->uobject) {
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uvm_lock_pageq();
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if (pg->uobject) { /* the "real" check */
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locked =
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simple_lock_try(&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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uvm_unlock_pageq();
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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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simple_unlock(&anon->an_lock);
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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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simple_lock(&anon->an_lock);
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continue; /* start over */
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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 can take over as owner!
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*/
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if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) {
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uvm_lock_pageq();
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pg->pqflags |= PQ_ANON; /* take ownership... */
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pg->loan_count--; /* ... and drop our loan */
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uvm_unlock_pageq();
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}
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/*
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* we did it! break the loop
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*/
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break;
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}
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/*
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* done!
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*/
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return(pg);
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}
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