/* $NetBSD: uvm_anon.c,v 1.63.22.1 2017/11/02 21:29:53 snj 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. * * 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 1.63.22.1 2017/11/02 21:29:53 snj Exp $"); #include "opt_uvmhist.h" #include #include #include #include #include #include #include static struct pool_cache uvm_anon_cache; static int uvm_anon_ctor(void *, void *, int); 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, NULL, NULL); } static int uvm_anon_ctor(void *arg, void *object, int flags) { struct vm_anon *anon = object; anon->an_ref = 0; anon->an_lock = NULL; anon->an_page = NULL; #if defined(VMSWAP) anon->an_swslot = 0; #endif return 0; } /* * uvm_analloc: allocate a new anon. * * => anon will have no lock associated. */ 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_lock == NULL); KASSERT(anon->an_page == NULL); #if defined(VMSWAP) KASSERT(anon->an_swslot == 0); #endif anon->an_ref = 1; } return anon; } /* * uvm_anon_dispose: free any resident page or swap resources of anon. * * => anon must be removed from the amap (if anon was in an amap). * => amap must be locked; we may drop and re-acquire the lock here. */ static bool uvm_anon_dispose(struct vm_anon *anon) { struct vm_page *pg = anon->an_page; UVMHIST_FUNC("uvm_anon_dispose"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist,"(anon=0x%#jx)", (uintptr_t)anon, 0,0,0); KASSERT(mutex_owned(anon->an_lock)); /* * If there is a resident page and it is loaned, then anon may not * own it. Call out to uvm_anon_lockloanpg() to identify and lock * the real owner of the page. */ if (pg && pg->loan_count) { KASSERT(anon->an_lock != NULL); pg = uvm_anon_lockloanpg(anon); } /* * Dispose the page, if it is resident. */ if (pg) { KASSERT(anon->an_lock != NULL); /* * If the page is owned by a UVM object (now locked), * then kill the loan on the page rather than free it, * and release the object lock. */ 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 { /* * If page has no UVM object, then anon is the owner, * and it is already locked. */ KASSERT((pg->flags & PG_RELEASED) == 0); pmap_page_protect(pg, VM_PROT_NONE); /* * If the page is busy, mark it as PG_RELEASED, so * that uvm_anon_release(9) would release it later. */ if (pg->flags & PG_BUSY) { pg->flags |= PG_RELEASED; mutex_obj_hold(anon->an_lock); return false; } mutex_enter(&uvm_pageqlock); uvm_pagefree(pg); mutex_exit(&uvm_pageqlock); UVMHIST_LOG(maphist, "anon 0x%#jx, page 0x%#jx: " "freed now!", (uintptr_t)anon, (uintptr_t)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 /* * Free any swap resources, leave a page replacement hint. */ uvm_anon_dropswap(anon); uvmpdpol_anfree(anon); UVMHIST_LOG(maphist,"<- done!",0,0,0,0); return true; } /* * uvm_anon_free: free a single anon. * * => anon must be already disposed. */ void uvm_anon_free(struct vm_anon *anon) { KASSERT(anon->an_ref == 0); KASSERT(anon->an_lock == NULL); KASSERT(anon->an_page == NULL); #if defined(VMSWAP) KASSERT(anon->an_swslot == 0); #endif pool_cache_put(&uvm_anon_cache, anon); } /* * uvm_anon_freelst: free a linked list of anon structures. * * => anon must be locked, we will unlock it. */ void uvm_anon_freelst(struct vm_amap *amap, struct vm_anon *anonlst) { struct vm_anon *anon; struct vm_anon **anonp = &anonlst; KASSERT(mutex_owned(amap->am_lock)); while ((anon = *anonp) != NULL) { if (!uvm_anon_dispose(anon)) { /* Do not free this anon. */ *anonp = anon->an_link; /* Note: clears an_ref as well. */ anon->an_link = NULL; } else { anonp = &anon->an_link; } } amap_unlock(amap); while (anonlst) { anon = anonlst->an_link; /* Note: clears an_ref as well. */ anonlst->an_link = NULL; anonlst->an_lock = NULL; uvm_anon_free(anonlst); anonlst = anon; } } /* * uvm_anon_lockloanpg: given a locked anon, lock its resident page owner. * * => 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) { /* * someone locking the object has a chance to * lock us right now * * XXX Better than yielding but inadequate. */ kpause("livelock", false, 1, anon->an_lock); continue; } } /* * If page is un-owned i.e. the object dropped its ownership, * then we have to take the ownership. */ 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) /* * uvm_anon_pagein: 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_amap *amap, struct vm_anon *anon) { struct vm_page *pg; struct uvm_object *uobj; KASSERT(mutex_owned(anon->an_lock)); KASSERT(anon->an_lock == amap->am_lock); /* * Get the page of the anon. */ switch (uvmfault_anonget(NULL, amap, anon)) { case 0: /* Success - we have the page. */ KASSERT(mutex_owned(anon->an_lock)); break; case EIO: case ERESTART: /* * Nothing more to do on errors. ERESTART means that the * anon was freed. */ return false; default: return true; } /* * Mark the page 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) { pg->flags &= ~PG_WANTED; wakeup(pg); } mutex_exit(anon->an_lock); if (uobj) { mutex_exit(uobj->vmobjlock); } return false; } /* * 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 %#jx, paged to swslot 0x%jx", (uintptr_t)anon, anon->an_swslot, 0, 0); uvm_swap_free(anon->an_swslot, 1); anon->an_swslot = 0; } #endif /* * uvm_anon_release: release an anon and its page. * * => anon should not have any references. * => anon must be locked. */ void uvm_anon_release(struct vm_anon *anon) { struct vm_page *pg = anon->an_page; bool success __diagused; 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); KASSERT(anon->an_page == NULL); /* dispose should succeed as no one can reach this anon anymore. */ success = uvm_anon_dispose(anon); KASSERT(success); mutex_exit(anon->an_lock); /* Note: extra reference is held for PG_RELEASED case. */ mutex_obj_free(anon->an_lock); anon->an_lock = NULL; uvm_anon_free(anon); }