NetBSD/sys/uvm/uvm_anon.c

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/* $NetBSD: uvm_anon.c,v 1.2 1999/03/26 17:34:15 chs Exp $ */
/*
*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Charles D. Cranor and
* Washington University.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* uvm_anon.c: uvm anon ops
*/
#include "opt_uvmhist.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>
#include <uvm/uvm.h>
#include <uvm/uvm_swap.h>
/*
* allocate anons
*/
void
uvm_anon_init()
{
struct vm_anon *anon;
int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */
int lcv;
/*
* Allocate the initial anons.
*/
anon = (struct vm_anon *)uvm_km_alloc(kernel_map,
sizeof(*anon) * nanon);
if (anon == NULL) {
printf("uvm_anon_init: can not allocate %d anons\n", nanon);
panic("uvm_anon_init");
}
memset(anon, 0, sizeof(*anon) * nanon);
uvm.afree = NULL;
uvmexp.nanon = uvmexp.nfreeanon = nanon;
for (lcv = 0 ; lcv < nanon ; lcv++) {
anon[lcv].u.an_nxt = uvm.afree;
uvm.afree = &anon[lcv];
}
simple_lock_init(&uvm.afreelock);
}
/*
* add some more anons to the free pool. called when we add
* more swap space.
*/
void
uvm_anon_add(pages)
int pages;
{
struct vm_anon *anon;
int lcv;
anon = (struct vm_anon *)uvm_km_alloc(kernel_map,
sizeof(*anon) * pages);
/* XXX Should wait for VM to free up. */
if (anon == NULL) {
printf("uvm_anon_add: can not allocate %d anons\n", pages);
panic("uvm_anon_add");
}
simple_lock(&uvm.afreelock);
memset(anon, 0, sizeof(*anon) * pages);
uvmexp.nanon += pages;
uvmexp.nfreeanon += pages;
for (lcv = 0; lcv < pages; lcv++) {
simple_lock_init(&anon->an_lock);
anon[lcv].u.an_nxt = uvm.afree;
uvm.afree = &anon[lcv];
}
simple_unlock(&uvm.afreelock);
}
/*
* allocate an anon
*/
struct vm_anon *
uvm_analloc()
{
struct vm_anon *a;
simple_lock(&uvm.afreelock);
a = uvm.afree;
if (a) {
uvm.afree = a->u.an_nxt;
uvmexp.nfreeanon--;
a->an_ref = 1;
a->an_swslot = 0;
a->u.an_page = NULL; /* so we can free quickly */
}
simple_unlock(&uvm.afreelock);
return(a);
}
/*
* uvm_anfree: free a single anon structure
*
* => caller must remove anon from its amap before calling (if it was in
* an amap).
* => anon must be unlocked and have a zero reference count.
* => we may lock the pageq's.
*/
void
uvm_anfree(anon)
struct vm_anon *anon;
{
struct vm_page *pg;
UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist);
UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0);
/*
* get page
*/
pg = anon->u.an_page;
/*
* if there is a resident page and it is loaned, then anon may not
* own it. call out to uvm_anon_lockpage() to ensure the real owner
* of the page has been identified and locked.
*/
if (pg && pg->loan_count)
pg = uvm_anon_lockloanpg(anon);
/*
* if we have a resident page, we must dispose of it before freeing
* the anon.
*/
if (pg) {
/*
* if the page is owned by a uobject (now locked), then we must
* kill the loan on the page rather than free it.
*/
if (pg->uobject) {
/* kill loan */
uvm_lock_pageq();
#ifdef DIAGNOSTIC
if (pg->loan_count < 1)
panic("uvm_anfree: obj owned page "
"with no loan count");
#endif
pg->loan_count--;
pg->uanon = NULL;
uvm_unlock_pageq();
simple_unlock(&pg->uobject->vmobjlock);
} else {
/*
* page has no uobject, so we must be the owner of it.
*
* if page is busy then we just mark it as released
* (who ever has it busy must check for this when they
* wake up). if the page is not busy then we can
* free it now.
*/
if ((pg->flags & PG_BUSY) != 0) {
/* tell them to dump it when done */
pg->flags |= PG_RELEASED;
UVMHIST_LOG(maphist,
" anon 0x%x, page 0x%x: BUSY (released!)",
anon, pg, 0, 0);
return;
}
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE);
uvm_lock_pageq(); /* lock out pagedaemon */
uvm_pagefree(pg); /* bye bye */
uvm_unlock_pageq(); /* free the daemon */
UVMHIST_LOG(maphist," anon 0x%x, page 0x%x: freed now!",
anon, pg, 0, 0);
}
}
/*
* free any swap resources.
*/
uvm_anon_dropswap(anon);
/*
* now that we've stripped the data areas from the anon, free the anon
* itself!
*/
simple_lock(&uvm.afreelock);
anon->u.an_nxt = uvm.afree;
uvm.afree = anon;
uvmexp.nfreeanon++;
simple_unlock(&uvm.afreelock);
UVMHIST_LOG(maphist,"<- done!",0,0,0,0);
}
/*
* uvm_anon_dropswap: release any swap resources from this anon.
*
* => anon must be locked or have a reference count of 0.
*/
void
uvm_anon_dropswap(anon)
struct vm_anon *anon;
{
UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist);
if (anon->an_swslot == 0) {
return;
}
UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x",
anon, anon->an_swslot, 0, 0);
uvm_swap_free(anon->an_swslot, 1);
anon->an_swslot = 0;
if (anon->u.an_page == NULL) {
/* this page is no longer only in swap. */
simple_lock(&uvm.swap_data_lock);
uvmexp.swpgonly--;
simple_unlock(&uvm.swap_data_lock);
}
}
/*
* uvm_anon_lockloanpg: given a locked anon, lock its resident page
*
* => anon is locked by caller
* => on return: anon is locked
* if there is a resident page:
* if it has a uobject, it is locked by us
* if it is ownerless, we take over as owner
* we return the resident page (it can change during
* this function)
* => note that the only time an anon has an ownerless resident page
* is if the page was loaned from a uvm_object and the uvm_object
* disowned it
* => this only needs to be called when you want to do an operation
* on an anon's resident page and that page has a non-zero loan
* count.
*/
struct vm_page *
uvm_anon_lockloanpg(anon)
struct vm_anon *anon;
{
struct vm_page *pg;
boolean_t locked = FALSE;
/*
* loop while we have a resident page that has a non-zero loan count.
* if we successfully get our lock, we will "break" the loop.
* note that the test for pg->loan_count is not protected -- this
* may produce false positive results. note that a false positive
* result may cause us to do more work than we need to, but it will
* not produce an incorrect result.
*/
while (((pg = anon->u.an_page) != NULL) && pg->loan_count != 0) {
/*
* quickly check to see if the page has an object before
* bothering to lock the page queues. this may also produce
* a false positive result, but that's ok because we do a real
* check after that.
*
* XXX: quick check -- worth it? need volatile?
*/
if (pg->uobject) {
uvm_lock_pageq();
if (pg->uobject) { /* the "real" check */
locked =
simple_lock_try(&pg->uobject->vmobjlock);
} else {
/* object disowned before we got PQ lock */
locked = TRUE;
}
uvm_unlock_pageq();
/*
* if we didn't get a lock (try lock failed), then we
* toggle our anon lock and try again
*/
if (!locked) {
simple_unlock(&anon->an_lock);
/*
* someone locking the object has a chance to
* lock us right now
*/
simple_lock(&anon->an_lock);
continue; /* start over */
}
}
/*
* if page is un-owned [i.e. the object dropped its ownership],
* then we can take over as owner!
*/
if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) {
uvm_lock_pageq();
pg->pqflags |= PQ_ANON; /* take ownership... */
pg->loan_count--; /* ... and drop our loan */
uvm_unlock_pageq();
}
/*
* we did it! break the loop
*/
break;
}
/*
* done!
*/
return(pg);
}