8368dac6a2
PG_RELEASED for anon pages. PR/23171 from Christian Limpach. for details, see discussion filed in the PR database. uvm_anon_release: a new function to free anon-owned PG_RELEASED page. uvm_anfree: we can't wait for the page here because the caller might hold amap lock. instead, just mark the page as PG_RELEASED. who unbusy the page should check the PG_RELEASED. uvm_aio_aiodone: uvm_anon_release() instead of uvm_page_unbusy() if appropriate. uvmfault_anonget: check PG_RELEASED.
579 lines
13 KiB
C
579 lines
13 KiB
C
/* $NetBSD: uvm_anon.c,v 1.29 2004/05/05 11:54:32 yamt 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 <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.29 2004/05/05 11:54:32 yamt 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/proc.h>
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#include <sys/malloc.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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/*
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* anonblock_list: global list of anon blocks,
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* locked by swap_syscall_lock (since we never remove
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* anything from this list and we only add to it via swapctl(2)).
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*/
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struct uvm_anonblock {
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LIST_ENTRY(uvm_anonblock) list;
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int count;
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struct vm_anon *anons;
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};
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static LIST_HEAD(anonlist, uvm_anonblock) anonblock_list;
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static boolean_t anon_pagein(struct vm_anon *);
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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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int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */
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simple_lock_init(&uvm.afreelock);
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LIST_INIT(&anonblock_list);
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/*
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* Allocate the initial anons.
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*/
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uvm_anon_add(nanon);
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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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* => swap_syscall_lock should be held (protects anonblock_list).
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*/
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int
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uvm_anon_add(count)
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int count;
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{
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struct uvm_anonblock *anonblock;
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struct vm_anon *anon;
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int lcv, needed;
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simple_lock(&uvm.afreelock);
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uvmexp.nanonneeded += count;
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needed = uvmexp.nanonneeded - uvmexp.nanon;
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simple_unlock(&uvm.afreelock);
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if (needed <= 0) {
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return 0;
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}
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anon = (void *)uvm_km_alloc(kernel_map, sizeof(*anon) * needed);
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if (anon == NULL) {
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simple_lock(&uvm.afreelock);
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uvmexp.nanonneeded -= count;
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simple_unlock(&uvm.afreelock);
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return ENOMEM;
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}
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MALLOC(anonblock, void *, sizeof(*anonblock), M_UVMAMAP, M_WAITOK);
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anonblock->count = needed;
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anonblock->anons = anon;
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LIST_INSERT_HEAD(&anonblock_list, anonblock, list);
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memset(anon, 0, sizeof(*anon) * needed);
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simple_lock(&uvm.afreelock);
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uvmexp.nanon += needed;
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uvmexp.nfreeanon += needed;
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for (lcv = 0; lcv < needed; lcv++) {
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simple_lock_init(&anon[lcv].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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}
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simple_unlock(&uvm.afreelock);
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return 0;
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}
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/*
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* remove anons from the free pool.
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*/
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void
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uvm_anon_remove(count)
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int count;
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{
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/*
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* we never actually free any anons, to avoid allocation overhead.
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* XXX someday we might want to try to free anons.
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*/
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simple_lock(&uvm.afreelock);
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uvmexp.nanonneeded -= count;
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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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* => new anon is returned locked!
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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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LOCK_ASSERT(simple_lock_held(&a->an_lock) == 0);
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simple_lock(&a->an_lock);
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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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KASSERT(anon->an_ref == 0);
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LOCK_ASSERT(!simple_lock_held(&anon->an_lock));
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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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simple_lock(&anon->an_lock);
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pg = uvm_anon_lockloanpg(anon);
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simple_unlock(&anon->an_lock);
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}
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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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uvm_lock_pageq();
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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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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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* if page is busy then we wait until it is not busy,
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* and then free it.
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*/
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KASSERT((pg->flags & PG_RELEASED) == 0);
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simple_lock(&anon->an_lock);
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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
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* so that uvm_anon_release will 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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simple_unlock(&anon->an_lock);
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return;
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}
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uvm_lock_pageq();
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uvm_pagefree(pg);
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uvm_unlock_pageq();
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simple_unlock(&anon->an_lock);
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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 (pg == NULL && anon->an_swslot > 0) {
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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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KASSERT(uvmexp.swpgonly > 0);
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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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* 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,
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* free the anon 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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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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/*
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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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LOCK_ASSERT(simple_lock_held(&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->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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if (pg->uobject) {
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uvm_lock_pageq();
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if (pg->uobject) {
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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;
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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;
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pg->loan_count--;
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uvm_unlock_pageq();
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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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/*
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* page in every anon that is paged out to a range of swslots.
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*
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* swap_syscall_lock should be held (protects anonblock_list).
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*/
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boolean_t
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anon_swap_off(startslot, endslot)
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int startslot, endslot;
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{
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struct uvm_anonblock *anonblock;
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LIST_FOREACH(anonblock, &anonblock_list, list) {
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int i;
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/*
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* loop thru all the anons in the anonblock,
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* paging in where needed.
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*/
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for (i = 0; i < anonblock->count; i++) {
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struct vm_anon *anon = &anonblock->anons[i];
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int slot;
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/*
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* lock anon to work on it.
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*/
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simple_lock(&anon->an_lock);
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/*
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* is this anon's swap slot in range?
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*/
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slot = anon->an_swslot;
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if (slot >= startslot && slot < endslot) {
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boolean_t rv;
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/*
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* yup, page it in.
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*/
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/* locked: anon */
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rv = anon_pagein(anon);
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/* unlocked: anon */
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if (rv) {
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return rv;
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}
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} else {
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/*
|
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* nope, unlock and proceed.
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*/
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|
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simple_unlock(&anon->an_lock);
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}
|
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}
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}
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return FALSE;
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}
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/*
|
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* 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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|
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static boolean_t
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anon_pagein(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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struct uvm_object *uobj;
|
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int rv;
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|
|
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/* locked: anon */
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LOCK_ASSERT(simple_lock_held(&anon->an_lock));
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|
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rv = uvmfault_anonget(NULL, NULL, anon);
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|
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/*
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* if rv == 0, anon is still locked, else anon
|
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* is unlocked
|
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*/
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|
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switch (rv) {
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case 0:
|
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break;
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|
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case EIO:
|
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case ERESTART:
|
|
|
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/*
|
|
* nothing more to do on errors.
|
|
* ERESTART can only mean that the anon was freed,
|
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* so again there's nothing to do.
|
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*/
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|
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return FALSE;
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|
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default:
|
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return TRUE;
|
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}
|
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|
|
/*
|
|
* ok, we've got the page now.
|
|
* mark it as dirty, clear its swslot and un-busy it.
|
|
*/
|
|
|
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pg = anon->u.an_page;
|
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uobj = pg->uobject;
|
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if (anon->an_swslot > 0)
|
|
uvm_swap_free(anon->an_swslot, 1);
|
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anon->an_swslot = 0;
|
|
pg->flags &= ~(PG_CLEAN);
|
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|
|
/*
|
|
* deactivate the page (to put it on a page queue)
|
|
*/
|
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|
|
pmap_clear_reference(pg);
|
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uvm_lock_pageq();
|
|
if (pg->wire_count == 0)
|
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uvm_pagedeactivate(pg);
|
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uvm_unlock_pageq();
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|
|
if (pg->flags & PG_WANTED) {
|
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wakeup(pg);
|
|
pg->flags &= ~(PG_WANTED);
|
|
}
|
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|
|
/*
|
|
* unlock the anon and we're done.
|
|
*/
|
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|
|
simple_unlock(&anon->an_lock);
|
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if (uobj) {
|
|
simple_unlock(&uobj->vmobjlock);
|
|
}
|
|
return FALSE;
|
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}
|
|
|
|
/*
|
|
* uvm_anon_release: release an anon and its page.
|
|
*
|
|
* => caller must lock the anon.
|
|
*/
|
|
|
|
void
|
|
uvm_anon_release(anon)
|
|
struct vm_anon *anon;
|
|
{
|
|
struct vm_page *pg = anon->u.an_page;
|
|
|
|
LOCK_ASSERT(simple_lock_held(&anon->an_lock));
|
|
|
|
KASSERT(pg != NULL);
|
|
KASSERT((pg->flags & PG_RELEASED) != 0);
|
|
KASSERT((pg->flags & PG_BUSY) != 0);
|
|
KASSERT(pg->uobject == NULL);
|
|
KASSERT(pg->uanon == anon);
|
|
KASSERT(pg->loan_count == 0);
|
|
KASSERT(anon->an_ref == 0);
|
|
|
|
uvm_lock_pageq();
|
|
uvm_pagefree(pg);
|
|
uvm_unlock_pageq();
|
|
simple_unlock(&anon->an_lock);
|
|
|
|
KASSERT(anon->u.an_page == NULL);
|
|
|
|
uvm_anfree(anon);
|
|
}
|