/* $NetBSD: uvm_anon.c,v 1.33 2005/05/11 13:02:25 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 __KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.33 2005/05/11 13:02:25 yamt Exp $"); #include "opt_uvmhist.h" #include #include #include #include #include #include #include #include static POOL_INIT(uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 0, "anonpl", &pool_allocator_nointr); static struct pool_cache uvm_anon_pool_cache; static int uvm_anon_ctor(void *, void *, int); /* * allocate anons */ void uvm_anon_init() { pool_cache_init(&uvm_anon_pool_cache, &uvm_anon_pool, uvm_anon_ctor, NULL, NULL); } static int uvm_anon_ctor(void *arg, void *object, int flags) { struct vm_anon *anon = object; anon->an_ref = 0; simple_lock_init(&anon->an_lock); anon->an_page = NULL; anon->an_swslot = 0; return 0; } /* * allocate an anon * * => new anon is returned locked! */ struct vm_anon * uvm_analloc() { struct vm_anon *anon; anon = pool_cache_get(&uvm_anon_pool_cache, PR_NOWAIT); if (anon) { KASSERT(anon->an_ref == 0); LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); KASSERT(anon->an_page == NULL); KASSERT(anon->an_swslot == 0); anon->an_ref = 1; 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(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); KASSERT(anon->an_ref == 0); LOCK_ASSERT(!simple_lock_held(&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) { simple_lock(&anon->an_lock); pg = uvm_anon_lockloanpg(anon); simple_unlock(&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) { 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. */ KASSERT((pg->flags & PG_RELEASED) == 0); simple_lock(&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; simple_unlock(&anon->an_lock); return; } uvm_lock_pageq(); uvm_pagefree(pg); uvm_unlock_pageq(); simple_unlock(&anon->an_lock); UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " "freed now!", anon, pg, 0, 0); } } 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_cache_put(&uvm_anon_pool_cache, anon); 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; } /* * 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; LOCK_ASSERT(simple_lock_held(&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) { uvm_lock_pageq(); if (pg->uobject) { 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->pqflags & PQ_ANON) == 0) { uvm_lock_pageq(); pg->pqflags |= PQ_ANON; pg->loan_count--; uvm_unlock_pageq(); } 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(anon) struct vm_anon *anon; { struct vm_page *pg; struct uvm_object *uobj; int rv; /* locked: anon */ LOCK_ASSERT(simple_lock_held(&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) */ pmap_clear_reference(pg); uvm_lock_pageq(); if (pg->wire_count == 0) uvm_pagedeactivate(pg); uvm_unlock_pageq(); if (pg->flags & PG_WANTED) { wakeup(pg); pg->flags &= ~(PG_WANTED); } /* * unlock the anon and we're done. */ simple_unlock(&anon->an_lock); if (uobj) { simple_unlock(&uobj->vmobjlock); } return FALSE; } /* * 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->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->an_page == NULL); uvm_anfree(anon); }