/* $OpenBSD: uvm_anon.c,v 1.27 2007/04/13 18:57:49 art 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 /* * anonblock_list: global list of anon blocks, * locked by swap_syscall_lock (since we never remove * anything from this list and we only add to it via swapctl(2)). */ struct uvm_anonblock { LIST_ENTRY(uvm_anonblock) list; int count; struct vm_anon *anons; }; static LIST_HEAD(anonlist, uvm_anonblock) anonblock_list; static boolean_t anon_pagein(struct vm_anon *); /* * allocate anons */ void uvm_anon_init() { int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */ simple_lock_init(&uvm.afreelock); LIST_INIT(&anonblock_list); /* * Allocate the initial anons. */ uvm_anon_add(nanon); } /* * add some more anons to the free pool. called when we add * more swap space. * * => swap_syscall_lock should be held (protects anonblock_list). */ int uvm_anon_add(count) int count; { struct uvm_anonblock *anonblock; struct vm_anon *anon; int lcv, needed; simple_lock(&uvm.afreelock); uvmexp.nanonneeded += count; needed = uvmexp.nanonneeded - uvmexp.nanon; simple_unlock(&uvm.afreelock); if (needed <= 0) { return 0; } anon = (void *)uvm_km_alloc(kernel_map, sizeof(*anon) * needed); /* XXX Should wait for VM to free up. */ if (anon == NULL) { printf("uvm_anon_add: can not allocate %d anons\n", needed); panic("uvm_anon_add"); } MALLOC(anonblock, void *, sizeof(*anonblock), M_UVMAMAP, M_WAITOK); anonblock->count = needed; anonblock->anons = anon; LIST_INSERT_HEAD(&anonblock_list, anonblock, list); memset(anon, 0, sizeof(*anon) * needed); simple_lock(&uvm.afreelock); uvmexp.nanon += needed; uvmexp.nfreeanon += needed; for (lcv = 0; lcv < needed; lcv++) { simple_lock_init(&anon->an_lock); anon[lcv].u.an_nxt = uvm.afree; uvm.afree = &anon[lcv]; simple_lock_init(&uvm.afree->an_lock); } simple_unlock(&uvm.afreelock); return 0; } /* * remove anons from the free pool. */ void uvm_anon_remove(count) int count; { /* * we never actually free any anons, to avoid allocation overhead. * XXX someday we might want to try to free anons. */ simple_lock(&uvm.afreelock); uvmexp.nanonneeded -= count; 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=%p)", 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) { 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); UVMHIST_LOG(maphist, " anon %p, page %p: BUSY (released!)", anon, pg, 0, 0); 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 */ UVMHIST_LOG(maphist,"anon %p, page %p: 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%lx", 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; } } /* * 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); } /* * page in every anon that is paged out to a range of swslots. * * swap_syscall_lock should be held (protects anonblock_list). */ boolean_t anon_swap_off(startslot, endslot) int startslot, endslot; { struct uvm_anonblock *anonblock; for (anonblock = LIST_FIRST(&anonblock_list); anonblock != NULL; anonblock = LIST_NEXT(anonblock, list)) { int i; /* * loop thru all the anons in the anonblock, * paging in where needed. */ for (i = 0; i < anonblock->count; i++) { struct vm_anon *anon = &anonblock->anons[i]; int slot; /* * lock anon to work on it. */ simple_lock(&anon->an_lock); /* * is this anon's swap slot in range? */ slot = anon->an_swslot; if (slot >= startslot && slot < endslot) { boolean_t rv; /* * yup, page it in. */ /* locked: anon */ rv = anon_pagein(anon); /* unlocked: anon */ if (rv) { return rv; } } else { /* * nope, unlock and proceed. */ simple_unlock(&anon->an_lock); } } } return FALSE; } /* * 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. */ static boolean_t anon_pagein(anon) 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->u.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; }