NetBSD-5.0.2/sys/uvm/uvm_anon.c
/* $NetBSD: uvm_anon.c,v 1.51 2008/01/18 10:48:23 yamt 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.51 2008/01/18 10:48:23 yamt Exp $");
#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 <sys/kernel.h>
#include <uvm/uvm.h>
#include <uvm/uvm_swap.h>
#include <uvm/uvm_pdpolicy.h>
static struct pool_cache uvm_anon_cache;
static int uvm_anon_ctor(void *, void *, int);
static void uvm_anon_dtor(void *, void *);
/*
* allocate anons
*/
void
uvm_anon_init(void)
{
pool_cache_bootstrap(&uvm_anon_cache, sizeof(struct vm_anon), 0, 0,
PR_LARGECACHE, "anonpl", NULL, IPL_NONE, uvm_anon_ctor,
uvm_anon_dtor, NULL);
}
static int
uvm_anon_ctor(void *arg, void *object, int flags)
{
struct vm_anon *anon = object;
anon->an_ref = 0;
mutex_init(&anon->an_lock, MUTEX_DEFAULT, IPL_NONE);
anon->an_page = NULL;
#if defined(VMSWAP)
anon->an_swslot = 0;
#endif /* defined(VMSWAP) */
return 0;
}
static void
uvm_anon_dtor(void *arg, void *object)
{
struct vm_anon *anon = object;
mutex_destroy(&anon->an_lock);
}
/*
* allocate an anon
*
* => new anon is returned locked!
*/
struct vm_anon *
uvm_analloc(void)
{
struct vm_anon *anon;
anon = pool_cache_get(&uvm_anon_cache, PR_NOWAIT);
if (anon) {
KASSERT(anon->an_ref == 0);
KASSERT(anon->an_page == NULL);
#if defined(VMSWAP)
KASSERT(anon->an_swslot == 0);
#endif /* defined(VMSWAP) */
anon->an_ref = 1;
mutex_enter(&anon->an_lock);
}
return anon;
}
/*
* 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(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);
KASSERT(anon->an_ref == 0);
KASSERT(!mutex_owned(&anon->an_lock));
/*
* get page
*/
pg = anon->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) {
mutex_enter(&anon->an_lock);
pg = uvm_anon_lockloanpg(anon);
mutex_exit(&anon->an_lock);
}
/*
* 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) {
mutex_enter(&uvm_pageqlock);
KASSERT(pg->loan_count > 0);
pg->loan_count--;
pg->uanon = NULL;
mutex_exit(&uvm_pageqlock);
mutex_exit(&pg->uobject->vmobjlock);
} else {
/*
* page has no uobject, so we must be the owner of it.
*/
KASSERT((pg->flags & PG_RELEASED) == 0);
mutex_enter(&anon->an_lock);
pmap_page_protect(pg, VM_PROT_NONE);
/*
* if the page is busy, mark it as PG_RELEASED
* so that uvm_anon_release will release it later.
*/
if (pg->flags & PG_BUSY) {
pg->flags |= PG_RELEASED;
mutex_exit(&anon->an_lock);
return;
}
mutex_enter(&uvm_pageqlock);
uvm_pagefree(pg);
mutex_exit(&uvm_pageqlock);
mutex_exit(&anon->an_lock);
UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: "
"freed now!", anon, pg, 0, 0);
}
}
#if defined(VMSWAP)
if (pg == NULL && anon->an_swslot > 0) {
/* this page is no longer only in swap. */
mutex_enter(&uvm_swap_data_lock);
KASSERT(uvmexp.swpgonly > 0);
uvmexp.swpgonly--;
mutex_exit(&uvm_swap_data_lock);
}
#endif /* defined(VMSWAP) */
/*
* free any swap resources.
*/
uvm_anon_dropswap(anon);
/*
* give a page replacement hint.
*/
uvmpdpol_anfree(anon);
/*
* now that we've stripped the data areas from the anon,
* free the anon itself.
*/
KASSERT(anon->an_page == NULL);
#if defined(VMSWAP)
KASSERT(anon->an_swslot == 0);
#endif /* defined(VMSWAP) */
pool_cache_put(&uvm_anon_cache, anon);
UVMHIST_LOG(maphist,"<- done!",0,0,0,0);
}
#if defined(VMSWAP)
/*
* 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(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;
}
#endif /* defined(VMSWAP) */
/*
* 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(struct vm_anon *anon)
{
struct vm_page *pg;
bool locked = false;
KASSERT(mutex_owned(&anon->an_lock));
/*
* 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->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.
*/
if (pg->uobject) {
mutex_enter(&uvm_pageqlock);
if (pg->uobject) {
locked =
mutex_tryenter(&pg->uobject->vmobjlock);
} else {
/* object disowned before we got PQ lock */
locked = true;
}
mutex_exit(&uvm_pageqlock);
/*
* if we didn't get a lock (try lock failed), then we
* toggle our anon lock and try again
*/
if (!locked) {
mutex_exit(&anon->an_lock);
/*
* someone locking the object has a chance to
* lock us right now
*/
/* XXX Better than yielding but inadequate. */
kpause("livelock", false, 1, NULL);
mutex_enter(&anon->an_lock);
continue;
}
}
/*
* 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) {
mutex_enter(&uvm_pageqlock);
pg->pqflags |= PQ_ANON;
pg->loan_count--;
mutex_exit(&uvm_pageqlock);
}
break;
}
return(pg);
}
#if defined(VMSWAP)
/*
* fetch an anon's page.
*
* => anon must be locked, and is unlocked upon return.
* => returns true if pagein was aborted due to lack of memory.
*/
bool
uvm_anon_pagein(struct vm_anon *anon)
{
struct vm_page *pg;
struct uvm_object *uobj;
int rv;
/* locked: anon */
KASSERT(mutex_owned(&anon->an_lock));
rv = uvmfault_anonget(NULL, NULL, anon);
/*
* if rv == 0, anon is still locked, else anon
* is unlocked
*/
switch (rv) {
case 0:
break;
case EIO:
case ERESTART:
/*
* nothing more to do on errors.
* ERESTART can only mean that the anon was freed,
* so again there's nothing to do.
*/
return false;
default:
return true;
}
/*
* ok, we've got the page now.
* mark it as dirty, clear its swslot and un-busy it.
*/
pg = anon->an_page;
uobj = pg->uobject;
if (anon->an_swslot > 0)
uvm_swap_free(anon->an_swslot, 1);
anon->an_swslot = 0;
pg->flags &= ~(PG_CLEAN);
/*
* deactivate the page (to put it on a page queue)
*/
mutex_enter(&uvm_pageqlock);
if (pg->wire_count == 0)
uvm_pagedeactivate(pg);
mutex_exit(&uvm_pageqlock);
if (pg->flags & PG_WANTED) {
wakeup(pg);
pg->flags &= ~(PG_WANTED);
}
/*
* unlock the anon and we're done.
*/
mutex_exit(&anon->an_lock);
if (uobj) {
mutex_exit(&uobj->vmobjlock);
}
return false;
}
#endif /* defined(VMSWAP) */
/*
* uvm_anon_release: release an anon and its page.
*
* => caller must lock the anon.
*/
void
uvm_anon_release(struct vm_anon *anon)
{
struct vm_page *pg = anon->an_page;
KASSERT(mutex_owned(&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);
mutex_enter(&uvm_pageqlock);
uvm_pagefree(pg);
mutex_exit(&uvm_pageqlock);
mutex_exit(&anon->an_lock);
KASSERT(anon->an_page == NULL);
uvm_anfree(anon);
}