/* $OpenBSD: uvm_anon.c,v 1.35 2011/07/03 18:34:14 oga Exp $ */ /* $NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 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 #include #include #include #include #include #include #include struct pool uvm_anon_pool; /* * allocate anons */ void uvm_anon_init(void) { pool_init(&uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 0, "anonpl", &pool_allocator_nointr); pool_sethiwat(&uvm_anon_pool, uvmexp.free / 16); } /* * allocate an anon */ struct vm_anon * uvm_analloc(void) { struct vm_anon *anon; anon = pool_get(&uvm_anon_pool, PR_NOWAIT); if (anon) { simple_lock_init(&anon->an_lock); anon->an_ref = 1; anon->an_page = NULL; anon->an_swslot = 0; simple_lock(&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; /* * 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) 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) { uvm_lock_pageq(); KASSERT(pg->loan_count > 0); 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->pg_flags & PG_BUSY) != 0) { /* tell them to dump it when done */ atomic_setbits_int(&pg->pg_flags, PG_RELEASED); return; } pmap_page_protect(pg, VM_PROT_NONE); uvm_lock_pageq(); /* lock out pagedaemon */ uvm_pagefree(pg); /* bye bye */ uvm_unlock_pageq(); /* free the daemon */ } } if (pg == NULL && anon->an_swslot != 0) { /* this page is no longer only in swap. */ simple_lock(&uvm.swap_data_lock); KASSERT(uvmexp.swpgonly > 0); uvmexp.swpgonly--; simple_unlock(&uvm.swap_data_lock); } /* * free any swap resources. */ uvm_anon_dropswap(anon); /* * now that we've stripped the data areas from the anon, free the anon * itself! */ KASSERT(anon->an_page == NULL); KASSERT(anon->an_swslot == 0); pool_put(&uvm_anon_pool, anon); } /* * 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) { if (anon->an_swslot == 0) return; uvm_swap_free(anon->an_swslot, 1); anon->an_swslot = 0; } /* * 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; 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->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; } } /* * if page is un-owned [i.e. the object dropped its ownership], * then we can take over as owner! */ if (pg->uobject == NULL && (pg->pg_flags & PQ_ANON) == 0) { uvm_lock_pageq(); atomic_setbits_int(&pg->pg_flags, PQ_ANON); pg->loan_count--; /* ... and drop our loan */ uvm_unlock_pageq(); } /* * we did it! break the loop */ break; } return(pg); } /* * 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. */ boolean_t uvm_anon_pagein(struct vm_anon *anon) { struct vm_page *pg; struct uvm_object *uobj; int rv; /* locked: anon */ rv = uvmfault_anonget(NULL, NULL, anon); /* * if rv == VM_PAGER_OK, anon is still locked, else anon * is unlocked */ switch (rv) { case VM_PAGER_OK: break; case VM_PAGER_ERROR: case VM_PAGER_REFAULT: /* * nothing more to do on errors. * VM_PAGER_REFAULT can only mean that the anon was freed, * so again there's nothing to do. */ return FALSE; default: #ifdef DIAGNOSTIC panic("anon_pagein: uvmfault_anonget -> %d", rv); #else return FALSE; #endif } /* * 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; uvm_swap_free(anon->an_swslot, 1); anon->an_swslot = 0; atomic_clearbits_int(&pg->pg_flags, PG_CLEAN); /* * deactivate the page (to put it on a page queue) */ pmap_clear_reference(pg); pmap_page_protect(pg, VM_PROT_NONE); uvm_lock_pageq(); uvm_pagedeactivate(pg); uvm_unlock_pageq(); /* * unlock the anon and we're done. */ simple_unlock(&anon->an_lock); if (uobj) { simple_unlock(&uobj->vmobjlock); } return FALSE; }