/* * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * 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 the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. * * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94 * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Authors: Avadis Tevanian, Jr., Michael Wayne Young * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. * * $Id: vm_object.c,v 1.63 1996/01/19 04:00:02 dyson Exp $ */ /* * Virtual memory object module. */ #include "opt_ddb.h" #include #include #include #include /* for curproc, pageproc */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB static void DDB_vm_object_check __P((void)); #endif static void _vm_object_allocate __P((objtype_t, vm_size_t, vm_object_t)); #ifdef DDB static int _vm_object_in_map __P((vm_map_t map, vm_object_t object, vm_map_entry_t entry)); static int vm_object_in_map __P((vm_object_t object)); #endif static void vm_object_qcollapse __P((vm_object_t object)); #ifdef not_used static void vm_object_deactivate_pages __P((vm_object_t)); #endif static void vm_object_terminate __P((vm_object_t)); static void vm_object_cache_trim __P((void)); /* * Virtual memory objects maintain the actual data * associated with allocated virtual memory. A given * page of memory exists within exactly one object. * * An object is only deallocated when all "references" * are given up. Only one "reference" to a given * region of an object should be writeable. * * Associated with each object is a list of all resident * memory pages belonging to that object; this list is * maintained by the "vm_page" module, and locked by the object's * lock. * * Each object also records a "pager" routine which is * used to retrieve (and store) pages to the proper backing * storage. In addition, objects may be backed by other * objects from which they were virtual-copied. * * The only items within the object structure which are * modified after time of creation are: * reference count locked by object's lock * pager routine locked by object's lock * */ int vm_object_cache_max; struct object_q vm_object_cached_list; static int vm_object_cached; struct object_q vm_object_list; static long vm_object_count; vm_object_t kernel_object; vm_object_t kmem_object; static struct vm_object kernel_object_store; static struct vm_object kmem_object_store; extern int vm_pageout_page_count; static long object_collapses; static long object_bypasses; static void _vm_object_allocate(type, size, object) objtype_t type; vm_size_t size; register vm_object_t object; { TAILQ_INIT(&object->memq); TAILQ_INIT(&object->shadow_head); object->type = type; object->size = size; object->ref_count = 1; object->flags = 0; object->paging_in_progress = 0; object->resident_page_count = 0; object->shadow_count = 0; object->handle = NULL; object->paging_offset = (vm_ooffset_t) 0; object->backing_object = NULL; object->backing_object_offset = (vm_ooffset_t) 0; object->last_read = 0; TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); vm_object_count++; } /* * vm_object_init: * * Initialize the VM objects module. */ void vm_object_init() { TAILQ_INIT(&vm_object_cached_list); TAILQ_INIT(&vm_object_list); vm_object_count = 0; vm_object_cache_max = 84; if (cnt.v_page_count > 1000) vm_object_cache_max += (cnt.v_page_count - 1000) / 3; kernel_object = &kernel_object_store; _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), kernel_object); kmem_object = &kmem_object_store; _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS), kmem_object); } /* * vm_object_allocate: * * Returns a new object with the given size. */ vm_object_t vm_object_allocate(type, size) objtype_t type; vm_size_t size; { register vm_object_t result; result = (vm_object_t) malloc((u_long) sizeof *result, M_VMOBJ, M_WAITOK); _vm_object_allocate(type, size, result); return (result); } /* * vm_object_reference: * * Gets another reference to the given object. */ inline void vm_object_reference(object) register vm_object_t object; { if (object == NULL) return; if (object->ref_count == 0) { if ((object->flags & OBJ_CANPERSIST) == 0) panic("vm_object_reference: non-persistent object with 0 ref_count"); TAILQ_REMOVE(&vm_object_cached_list, object, cached_list); vm_object_cached--; } object->ref_count++; } /* * vm_object_deallocate: * * Release a reference to the specified object, * gained either through a vm_object_allocate * or a vm_object_reference call. When all references * are gone, storage associated with this object * may be relinquished. * * No object may be locked. */ void vm_object_deallocate(object) vm_object_t object; { vm_object_t temp; vm_page_t p; while (object != NULL) { if (object->ref_count == 0) panic("vm_object_deallocate: object deallocated too many times"); /* * Lose the reference */ object->ref_count--; if (object->ref_count != 0) { if ((object->ref_count == 1) && (object->handle == NULL) && (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { vm_object_t robject; robject = object->shadow_head.tqh_first; if ((robject != NULL) && (robject->handle == NULL) && (robject->type == OBJT_DEFAULT || robject->type == OBJT_SWAP)) { int s; robject->ref_count += 2; object->ref_count += 2; do { s = splhigh(); while (robject->paging_in_progress) { robject->flags |= OBJ_PIPWNT; tsleep(robject, PVM, "objde1", 0); } while (object->paging_in_progress) { object->flags |= OBJ_PIPWNT; tsleep(object, PVM, "objde2", 0); } splx(s); } while( object->paging_in_progress || robject->paging_in_progress); object->ref_count -= 2; robject->ref_count -= 2; if( robject->ref_count == 0) { robject->ref_count += 1; object = robject; continue; } vm_object_collapse(robject); return; } } /* * If there are still references, then we are done. */ return; } if (object->type == OBJT_VNODE) { struct vnode *vp = object->handle; vp->v_flag &= ~VTEXT; } /* * See if this object can persist and has some resident * pages. If so, enter it in the cache. */ if (object->flags & OBJ_CANPERSIST) { if (object->resident_page_count != 0) { vm_object_page_clean(object, 0, 0 ,TRUE, TRUE); TAILQ_INSERT_TAIL(&vm_object_cached_list, object, cached_list); vm_object_cached++; vm_object_cache_trim(); return; } else { object->flags &= ~OBJ_CANPERSIST; } } /* * Make sure no one uses us. */ object->flags |= OBJ_DEAD; temp = object->backing_object; if (temp) { TAILQ_REMOVE(&temp->shadow_head, object, shadow_list); --temp->shadow_count; } vm_object_terminate(object); /* unlocks and deallocates object */ object = temp; } } /* * vm_object_terminate actually destroys the specified object, freeing * up all previously used resources. * * The object must be locked. */ static void vm_object_terminate(object) register vm_object_t object; { register vm_page_t p; int s; /* * wait for the pageout daemon to be done with the object */ s = splhigh(); while (object->paging_in_progress) { object->flags |= OBJ_PIPWNT; tsleep(object, PVM, "objtrm", 0); } splx(s); if (object->paging_in_progress != 0) panic("vm_object_deallocate: pageout in progress"); /* * Clean and free the pages, as appropriate. All references to the * object are gone, so we don't need to lock it. */ if (object->type == OBJT_VNODE) { struct vnode *vp = object->handle; VOP_LOCK(vp); vm_object_page_clean(object, 0, 0, TRUE, FALSE); vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0); VOP_UNLOCK(vp); } /* * Now free the pages. For internal objects, this also removes them * from paging queues. */ while ((p = object->memq.tqh_first) != NULL) { if (p->flags & PG_BUSY) printf("vm_object_terminate: freeing busy page\n"); PAGE_WAKEUP(p); vm_page_free(p); cnt.v_pfree++; } /* * Let the pager know object is dead. */ vm_pager_deallocate(object); TAILQ_REMOVE(&vm_object_list, object, object_list); vm_object_count--; wakeup(object); /* * Free the space for the object. */ free((caddr_t) object, M_VMOBJ); } /* * vm_object_page_clean * * Clean all dirty pages in the specified range of object. * Leaves page on whatever queue it is currently on. * * Odd semantics: if start == end, we clean everything. * * The object must be locked. */ void vm_object_page_clean(object, start, end, syncio, lockflag) vm_object_t object; vm_pindex_t start; vm_pindex_t end; boolean_t syncio; boolean_t lockflag; { register vm_page_t p, np, tp; register vm_offset_t tstart, tend; vm_pindex_t pi; int s; struct vnode *vp; int runlen; int maxf; int chkb; int maxb; int i; vm_page_t maf[vm_pageout_page_count]; vm_page_t mab[vm_pageout_page_count]; vm_page_t ma[vm_pageout_page_count]; if (object->type != OBJT_VNODE || (object->flags & OBJ_MIGHTBEDIRTY) == 0) return; vp = object->handle; if (lockflag) VOP_LOCK(vp); object->flags |= OBJ_CLEANING; tstart = start; if (end == 0) { tend = object->size; } else { tend = end; } if ((tstart == 0) && (tend == object->size)) { object->flags &= ~(OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); } for(p = object->memq.tqh_first; p; p = p->listq.tqe_next) p->flags |= PG_CLEANCHK; rescan: for(p = object->memq.tqh_first; p; p = np) { np = p->listq.tqe_next; pi = p->pindex; if (((p->flags & PG_CLEANCHK) == 0) || (pi < tstart) || (pi >= tend) || (p->valid == 0) || (p->queue == PQ_CACHE)) { p->flags &= ~PG_CLEANCHK; continue; } vm_page_test_dirty(p); if ((p->dirty & p->valid) == 0) { p->flags &= ~PG_CLEANCHK; continue; } s = splhigh(); if ((p->flags & PG_BUSY) || p->busy) { p->flags |= PG_WANTED|PG_REFERENCED; tsleep(p, PVM, "vpcwai", 0); splx(s); goto rescan; } splx(s); maxf = 0; for(i=1;iflags & PG_BUSY) || (tp->flags & PG_CLEANCHK) == 0) break; vm_page_test_dirty(tp); if ((tp->dirty & tp->valid) == 0) { tp->flags &= ~PG_CLEANCHK; break; } maf[ i - 1 ] = tp; maxf++; continue; } break; } maxb = 0; chkb = vm_pageout_page_count - maxf; if (chkb) { for(i = 1; i < chkb;i++) { if (tp = vm_page_lookup(object, pi - i)) { if ((tp->flags & PG_BUSY) || (tp->flags & PG_CLEANCHK) == 0) break; vm_page_test_dirty(tp); if ((tp->dirty & tp->valid) == 0) { tp->flags &= ~PG_CLEANCHK; break; } mab[ i - 1 ] = tp; maxb++; continue; } break; } } for(i=0;iflags |= PG_BUSY; ma[index]->flags &= ~PG_CLEANCHK; vm_page_protect(ma[index], VM_PROT_READ); } vm_page_protect(p, VM_PROT_READ); p->flags |= PG_BUSY; p->flags &= ~PG_CLEANCHK; ma[maxb] = p; for(i=0;iflags |= PG_BUSY; ma[index]->flags &= ~PG_CLEANCHK; vm_page_protect(ma[index], VM_PROT_READ); } runlen = maxb + maxf + 1; /* printf("maxb: %d, maxf: %d, runlen: %d, offset: %d\n", maxb, maxf, runlen, ma[0]->pindex); */ vm_pageout_flush(ma, runlen, 0); goto rescan; } VOP_FSYNC(vp, NULL, syncio, curproc); if (lockflag) VOP_UNLOCK(vp); object->flags &= ~OBJ_CLEANING; return; } #ifdef not_used /* XXX I cannot tell if this should be an exported symbol */ /* * vm_object_deactivate_pages * * Deactivate all pages in the specified object. (Keep its pages * in memory even though it is no longer referenced.) * * The object must be locked. */ static void vm_object_deactivate_pages(object) register vm_object_t object; { register vm_page_t p, next; for (p = object->memq.tqh_first; p != NULL; p = next) { next = p->listq.tqe_next; vm_page_deactivate(p); } } #endif /* * Trim the object cache to size. */ static void vm_object_cache_trim() { register vm_object_t object; while (vm_object_cached > vm_object_cache_max) { object = vm_object_cached_list.tqh_first; vm_object_reference(object); pager_cache(object, FALSE); } } /* * vm_object_pmap_copy: * * Makes all physical pages in the specified * object range copy-on-write. No writeable * references to these pages should remain. * * The object must *not* be locked. */ void vm_object_pmap_copy(object, start, end) register vm_object_t object; register vm_pindex_t start; register vm_pindex_t end; { register vm_page_t p; if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) return; for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) { vm_page_protect(p, VM_PROT_READ); } object->flags &= ~OBJ_WRITEABLE; } /* * vm_object_pmap_remove: * * Removes all physical pages in the specified * object range from all physical maps. * * The object must *not* be locked. */ void vm_object_pmap_remove(object, start, end) register vm_object_t object; register vm_pindex_t start; register vm_pindex_t end; { register vm_page_t p; if (object == NULL) return; for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) { if (p->pindex >= start && p->pindex < end) vm_page_protect(p, VM_PROT_NONE); } } /* * vm_object_copy: * * Create a new object which is a copy of an existing * object, and mark all of the pages in the existing * object 'copy-on-write'. The new object has one reference. * Returns the new object. * * May defer the copy until later if the object is not backed * up by a non-default pager. * */ void vm_object_copy(src_object, src_offset, dst_object, dst_offset, src_needs_copy) register vm_object_t src_object; vm_pindex_t src_offset; vm_object_t *dst_object;/* OUT */ vm_pindex_t *dst_offset;/* OUT */ boolean_t *src_needs_copy; /* OUT */ { if (src_object == NULL) { /* * Nothing to copy */ *dst_object = NULL; *dst_offset = 0; *src_needs_copy = FALSE; return; } /* * Try to collapse the object before copying it. */ if (src_object->handle == NULL && (src_object->type == OBJT_DEFAULT || src_object->type == OBJT_SWAP)) vm_object_collapse(src_object); /* * Make another reference to the object */ src_object->ref_count++; *dst_object = src_object; *dst_offset = src_offset; /* * Must make a shadow when write is desired */ *src_needs_copy = TRUE; return; } /* * vm_object_shadow: * * Create a new object which is backed by the * specified existing object range. The source * object reference is deallocated. * * The new object and offset into that object * are returned in the source parameters. */ void vm_object_shadow(object, offset, length) vm_object_t *object; /* IN/OUT */ vm_ooffset_t *offset; /* IN/OUT */ vm_size_t length; { register vm_object_t source; register vm_object_t result; source = *object; /* * Allocate a new object with the given length */ if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL) panic("vm_object_shadow: no object for shadowing"); /* * The new object shadows the source object, adding a reference to it. * Our caller changes his reference to point to the new object, * removing a reference to the source object. Net result: no change * of reference count. */ result->backing_object = source; if (source) { TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list); ++source->shadow_count; } /* * Store the offset into the source object, and fix up the offset into * the new object. */ result->backing_object_offset = *offset; /* * Return the new things */ *offset = 0; *object = result; } /* * this version of collapse allows the operation to occur earlier and * when paging_in_progress is true for an object... This is not a complete * operation, but should plug 99.9% of the rest of the leaks. */ static void vm_object_qcollapse(object) register vm_object_t object; { register vm_object_t backing_object; register vm_pindex_t backing_offset_index, paging_offset_index; vm_pindex_t backing_object_paging_offset_index; vm_pindex_t new_pindex; register vm_page_t p, pp; register vm_size_t size; backing_object = object->backing_object; if (backing_object->ref_count != 1) return; backing_object->ref_count += 2; backing_offset_index = OFF_TO_IDX(object->backing_object_offset); backing_object_paging_offset_index = OFF_TO_IDX(backing_object->paging_offset); paging_offset_index = OFF_TO_IDX(object->paging_offset); size = object->size; p = backing_object->memq.tqh_first; while (p) { vm_page_t next; next = p->listq.tqe_next; if ((p->flags & (PG_BUSY | PG_FICTITIOUS)) || (p->queue == PQ_CACHE) || !p->valid || p->hold_count || p->wire_count || p->busy) { p = next; continue; } vm_page_protect(p, VM_PROT_NONE); new_pindex = p->pindex - backing_offset_index; if (p->pindex < backing_offset_index || new_pindex >= size) { if (backing_object->type == OBJT_SWAP) swap_pager_freespace(backing_object, backing_object_paging_offset_index+p->pindex, 1); vm_page_free(p); } else { pp = vm_page_lookup(object, new_pindex); if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object, paging_offset_index + new_pindex, NULL, NULL))) { if (backing_object->type == OBJT_SWAP) swap_pager_freespace(backing_object, backing_object_paging_offset_index + p->pindex, 1); vm_page_free(p); } else { if (backing_object->type == OBJT_SWAP) swap_pager_freespace(backing_object, backing_object_paging_offset_index + p->pindex, 1); vm_page_rename(p, object, new_pindex); p->dirty = VM_PAGE_BITS_ALL; } } p = next; } backing_object->ref_count -= 2; } /* * vm_object_collapse: * * Collapse an object with the object backing it. * Pages in the backing object are moved into the * parent, and the backing object is deallocated. */ void vm_object_collapse(object) vm_object_t object; { vm_object_t backing_object; vm_ooffset_t backing_offset; vm_size_t size; vm_pindex_t new_pindex, backing_offset_index; vm_page_t p, pp; while (TRUE) { /* * Verify that the conditions are right for collapse: * * The object exists and no pages in it are currently being paged * out. */ if (object == NULL) return; /* * Make sure there is a backing object. */ if ((backing_object = object->backing_object) == NULL) return; /* * we check the backing object first, because it is most likely * not collapsable. */ if (backing_object->handle != NULL || (backing_object->type != OBJT_DEFAULT && backing_object->type != OBJT_SWAP) || (backing_object->flags & OBJ_DEAD) || object->handle != NULL || (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) || (object->flags & OBJ_DEAD)) { return; } if (object->paging_in_progress != 0 || backing_object->paging_in_progress != 0) { vm_object_qcollapse(object); return; } /* * We know that we can either collapse the backing object (if * the parent is the only reference to it) or (perhaps) remove * the parent's reference to it. */ backing_offset = object->backing_object_offset; backing_offset_index = OFF_TO_IDX(backing_offset); size = object->size; /* * If there is exactly one reference to the backing object, we * can collapse it into the parent. */ if (backing_object->ref_count == 1) { backing_object->flags |= OBJ_DEAD; /* * We can collapse the backing object. * * Move all in-memory pages from backing_object to the * parent. Pages that have been paged out will be * overwritten by any of the parent's pages that * shadow them. */ while ((p = backing_object->memq.tqh_first) != 0) { new_pindex = p->pindex - backing_offset_index; /* * If the parent has a page here, or if this * page falls outside the parent, dispose of * it. * * Otherwise, move it as planned. */ if (p->pindex < backing_offset_index || new_pindex >= size) { vm_page_protect(p, VM_PROT_NONE); PAGE_WAKEUP(p); vm_page_free(p); } else { pp = vm_page_lookup(object, new_pindex); if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object, OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL))) { vm_page_protect(p, VM_PROT_NONE); PAGE_WAKEUP(p); vm_page_free(p); } else { vm_page_rename(p, object, new_pindex); } } } /* * Move the pager from backing_object to object. */ if (backing_object->type == OBJT_SWAP) { backing_object->paging_in_progress++; if (object->type == OBJT_SWAP) { object->paging_in_progress++; /* * copy shadow object pages into ours * and destroy unneeded pages in * shadow object. */ swap_pager_copy( backing_object, OFF_TO_IDX(backing_object->paging_offset), object, OFF_TO_IDX(object->paging_offset), OFF_TO_IDX(object->backing_object_offset)); vm_object_pip_wakeup(object); } else { object->paging_in_progress++; /* * move the shadow backing_object's pager data to * "object" and convert "object" type to OBJT_SWAP. */ object->type = OBJT_SWAP; object->un_pager.swp.swp_nblocks = backing_object->un_pager.swp.swp_nblocks; object->un_pager.swp.swp_allocsize = backing_object->un_pager.swp.swp_allocsize; object->un_pager.swp.swp_blocks = backing_object->un_pager.swp.swp_blocks; object->un_pager.swp.swp_poip = /* XXX */ backing_object->un_pager.swp.swp_poip; object->paging_offset = backing_object->paging_offset + backing_offset; TAILQ_INSERT_TAIL(&swap_pager_un_object_list, object, pager_object_list); /* * Convert backing object from OBJT_SWAP to * OBJT_DEFAULT. XXX - only the TAILQ_REMOVE is * actually necessary. */ backing_object->type = OBJT_DEFAULT; TAILQ_REMOVE(&swap_pager_un_object_list, backing_object, pager_object_list); /* * free unnecessary blocks */ swap_pager_freespace(object, 0, OFF_TO_IDX(object->paging_offset)); vm_object_pip_wakeup(object); } vm_object_pip_wakeup(backing_object); } /* * Object now shadows whatever backing_object did. * Note that the reference to backing_object->backing_object * moves from within backing_object to within object. */ TAILQ_REMOVE(&object->backing_object->shadow_head, object, shadow_list); --object->backing_object->shadow_count; if (backing_object->backing_object) { TAILQ_REMOVE(&backing_object->backing_object->shadow_head, backing_object, shadow_list); --backing_object->backing_object->shadow_count; } object->backing_object = backing_object->backing_object; if (object->backing_object) { TAILQ_INSERT_TAIL(&object->backing_object->shadow_head, object, shadow_list); ++object->backing_object->shadow_count; } object->backing_object_offset += backing_object->backing_object_offset; /* * Discard backing_object. * * Since the backing object has no pages, no pager left, * and no object references within it, all that is * necessary is to dispose of it. */ TAILQ_REMOVE(&vm_object_list, backing_object, object_list); vm_object_count--; free((caddr_t) backing_object, M_VMOBJ); object_collapses++; } else { /* * If all of the pages in the backing object are * shadowed by the parent object, the parent object no * longer has to shadow the backing object; it can * shadow the next one in the chain. * * The backing object must not be paged out - we'd have * to check all of the paged-out pages, as well. */ if (backing_object->type != OBJT_DEFAULT) { return; } /* * Should have a check for a 'small' number of pages * here. */ for (p = backing_object->memq.tqh_first; p; p = p->listq.tqe_next) { new_pindex = p->pindex - backing_offset_index; /* * If the parent has a page here, or if this * page falls outside the parent, keep going. * * Otherwise, the backing_object must be left in * the chain. */ if (p->pindex >= backing_offset_index && new_pindex <= size) { pp = vm_page_lookup(object, new_pindex); if ((pp == NULL || pp->valid == 0) && !vm_pager_has_page(object, OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL)) { /* * Page still needed. Can't go any * further. */ return; } } } /* * Make the parent shadow the next object in the * chain. Deallocating backing_object will not remove * it, since its reference count is at least 2. */ TAILQ_REMOVE(&object->backing_object->shadow_head, object, shadow_list); --object->backing_object->shadow_count; vm_object_reference(object->backing_object = backing_object->backing_object); if (object->backing_object) { TAILQ_INSERT_TAIL(&object->backing_object->shadow_head, object, shadow_list); ++object->backing_object->shadow_count; } object->backing_object_offset += backing_object->backing_object_offset; /* * Drop the reference count on backing_object. Since * its ref_count was at least 2, it will not vanish; * so we don't need to call vm_object_deallocate. */ if (backing_object->ref_count == 1) printf("should have called obj deallocate\n"); backing_object->ref_count--; object_bypasses++; } /* * Try again with this object's new backing object. */ } } /* * vm_object_page_remove: [internal] * * Removes all physical pages in the specified * object range from the object's list of pages. * * The object must be locked. */ void vm_object_page_remove(object, start, end, clean_only) register vm_object_t object; register vm_pindex_t start; register vm_pindex_t end; boolean_t clean_only; { register vm_page_t p, next; unsigned int size; int s; if (object == NULL) return; object->paging_in_progress++; again: size = end - start; if (size > 4 || size >= object->size / 4) { for (p = object->memq.tqh_first; p != NULL; p = next) { next = p->listq.tqe_next; if (p->wire_count != 0) { vm_page_protect(p, VM_PROT_NONE); p->valid = 0; continue; } if ((start <= p->pindex) && (p->pindex < end)) { s = splhigh(); if ((p->flags & PG_BUSY) || p->busy) { p->flags |= PG_WANTED; tsleep(p, PVM, "vmopar", 0); splx(s); goto again; } splx(s); if (clean_only) { vm_page_test_dirty(p); if (p->valid & p->dirty) continue; } vm_page_protect(p, VM_PROT_NONE); PAGE_WAKEUP(p); vm_page_free(p); } } } else { while (size > 0) { if ((p = vm_page_lookup(object, start)) != 0) { if (p->wire_count != 0) { p->valid = 0; vm_page_protect(p, VM_PROT_NONE); start += 1; size -= 1; continue; } s = splhigh(); if ((p->flags & PG_BUSY) || p->busy) { p->flags |= PG_WANTED; tsleep(p, PVM, "vmopar", 0); splx(s); goto again; } splx(s); if (clean_only) { vm_page_test_dirty(p); if (p->valid & p->dirty) { start += 1; size -= 1; continue; } } vm_page_protect(p, VM_PROT_NONE); PAGE_WAKEUP(p); vm_page_free(p); } start += 1; size -= 1; } } vm_object_pip_wakeup(object); } /* * Routine: vm_object_coalesce * Function: Coalesces two objects backing up adjoining * regions of memory into a single object. * * returns TRUE if objects were combined. * * NOTE: Only works at the moment if the second object is NULL - * if it's not, which object do we lock first? * * Parameters: * prev_object First object to coalesce * prev_offset Offset into prev_object * next_object Second object into coalesce * next_offset Offset into next_object * * prev_size Size of reference to prev_object * next_size Size of reference to next_object * * Conditions: * The object must *not* be locked. */ boolean_t vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size) register vm_object_t prev_object; vm_pindex_t prev_pindex; vm_size_t prev_size, next_size; { vm_size_t newsize; if (prev_object == NULL) { return (TRUE); } /* * Try to collapse the object first */ vm_object_collapse(prev_object); /* * Can't coalesce if: . more than one reference . paged out . shadows * another object . has a copy elsewhere (any of which mean that the * pages not mapped to prev_entry may be in use anyway) */ if (prev_object->ref_count > 1 || prev_object->type != OBJT_DEFAULT || prev_object->backing_object != NULL) { return (FALSE); } prev_size >>= PAGE_SHIFT; next_size >>= PAGE_SHIFT; /* * Remove any pages that may still be in the object from a previous * deallocation. */ vm_object_page_remove(prev_object, prev_pindex + prev_size, prev_pindex + prev_size + next_size, FALSE); /* * Extend the object if necessary. */ newsize = prev_pindex + prev_size + next_size; if (newsize > prev_object->size) prev_object->size = newsize; return (TRUE); } #ifdef DDB static int _vm_object_in_map(map, object, entry) vm_map_t map; vm_object_t object; vm_map_entry_t entry; { vm_map_t tmpm; vm_map_entry_t tmpe; vm_object_t obj; int entcount; if (map == 0) return 0; if (entry == 0) { tmpe = map->header.next; entcount = map->nentries; while (entcount-- && (tmpe != &map->header)) { if( _vm_object_in_map(map, object, tmpe)) { return 1; } tmpe = tmpe->next; } } else if (entry->is_sub_map || entry->is_a_map) { tmpm = entry->object.share_map; tmpe = tmpm->header.next; entcount = tmpm->nentries; while (entcount-- && tmpe != &tmpm->header) { if( _vm_object_in_map(tmpm, object, tmpe)) { return 1; } tmpe = tmpe->next; } } else if (obj = entry->object.vm_object) { for(; obj; obj=obj->backing_object) if( obj == object) { return 1; } } return 0; } static int vm_object_in_map( object) vm_object_t object; { struct proc *p; for (p = (struct proc *) allproc; p != NULL; p = p->p_next) { if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */) continue; /* if (p->p_stat != SRUN && p->p_stat != SSLEEP) { continue; } */ if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) return 1; } if( _vm_object_in_map( kernel_map, object, 0)) return 1; if( _vm_object_in_map( kmem_map, object, 0)) return 1; if( _vm_object_in_map( pager_map, object, 0)) return 1; if( _vm_object_in_map( buffer_map, object, 0)) return 1; if( _vm_object_in_map( io_map, object, 0)) return 1; if( _vm_object_in_map( phys_map, object, 0)) return 1; if( _vm_object_in_map( mb_map, object, 0)) return 1; if( _vm_object_in_map( u_map, object, 0)) return 1; return 0; } #ifdef DDB static void DDB_vm_object_check() { vm_object_t object; /* * make sure that internal objs are in a map somewhere * and none have zero ref counts. */ for (object = vm_object_list.tqh_first; object != NULL; object = object->object_list.tqe_next) { if (object->handle == NULL && (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { if (object->ref_count == 0) { printf("vmochk: internal obj has zero ref count: %d\n", object->size); } if (!vm_object_in_map(object)) { printf("vmochk: internal obj is not in a map: " "ref: %d, size: %d: 0x%x, backing_object: 0x%x\n", object->ref_count, object->size, object->size, object->backing_object); } } } } #endif /* DDB */ /* * vm_object_print: [ debug ] */ void vm_object_print(iobject, full, dummy3, dummy4) /* db_expr_t */ int iobject; boolean_t full; /* db_expr_t */ int dummy3; char *dummy4; { vm_object_t object = (vm_object_t)iobject; /* XXX */ register vm_page_t p; register int count; if (object == NULL) return; iprintf("Object 0x%x: size=0x%x, res=%d, ref=%d, ", (int) object, (int) object->size, object->resident_page_count, object->ref_count); printf("offset=0x%x, backing_object=(0x%x)+0x%x\n", (int) object->paging_offset, (int) object->backing_object, (int) object->backing_object_offset); printf("cache: next=%p, prev=%p\n", object->cached_list.tqe_next, object->cached_list.tqe_prev); if (!full) return; indent += 2; count = 0; for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) { if (count == 0) iprintf("memory:="); else if (count == 6) { printf("\n"); iprintf(" ..."); count = 0; } else printf(","); count++; printf("(off=0x%lx,page=0x%lx)", (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); } if (count != 0) printf("\n"); indent -= 2; } #endif /* DDB */