/* * 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. * * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $ * $DragonFly: src/sys/vm/vm_object.c,v 1.2 2003/06/17 04:29:00 dillon Exp $ */ /* * Virtual memory object module. */ #include #include #include /* for curproc, pageproc */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define EASY_SCAN_FACTOR 8 #define MSYNC_FLUSH_HARDSEQ 0x01 #define MSYNC_FLUSH_SOFTSEQ 0x02 static int msync_flush_flags = MSYNC_FLUSH_HARDSEQ | MSYNC_FLUSH_SOFTSEQ; SYSCTL_INT(_vm, OID_AUTO, msync_flush_flags, CTLFLAG_RW, &msync_flush_flags, 0, ""); static void vm_object_qcollapse (vm_object_t object); static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags); /* * 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 * */ struct object_q vm_object_list; #ifndef NULL_SIMPLELOCKS static struct simplelock vm_object_list_lock; #endif static long vm_object_count; /* count of all objects */ 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 int next_index; static vm_zone_t obj_zone; static struct vm_zone obj_zone_store; static int object_hash_rand; #define VM_OBJECTS_INIT 256 static struct vm_object vm_objects_init[VM_OBJECTS_INIT]; void _vm_object_allocate(type, size, object) objtype_t type; vm_size_t size; vm_object_t object; { int incr; TAILQ_INIT(&object->memq); LIST_INIT(&object->shadow_head); object->type = type; object->size = size; object->ref_count = 1; object->flags = 0; if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP)) vm_object_set_flag(object, OBJ_ONEMAPPING); object->paging_in_progress = 0; object->resident_page_count = 0; object->shadow_count = 0; object->pg_color = next_index; if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1)) incr = PQ_L2_SIZE / 3 + PQ_PRIME1; else incr = size; next_index = (next_index + incr) & PQ_L2_MASK; object->handle = NULL; object->backing_object = NULL; object->backing_object_offset = (vm_ooffset_t) 0; /* * Try to generate a number that will spread objects out in the * hash table. We 'wipe' new objects across the hash in 128 page * increments plus 1 more to offset it a little more by the time * it wraps around. */ object->hash_rand = object_hash_rand - 129; object->generation++; TAILQ_INSERT_TAIL(&vm_object_list, object, object_list); vm_object_count++; object_hash_rand = object->hash_rand; } /* * vm_object_init: * * Initialize the VM objects module. */ void vm_object_init() { TAILQ_INIT(&vm_object_list); simple_lock_init(&vm_object_list_lock); vm_object_count = 0; 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); obj_zone = &obj_zone_store; zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object), vm_objects_init, VM_OBJECTS_INIT); } void vm_object_init2() { zinitna(obj_zone, NULL, NULL, 0, 0, 0, 1); } /* * 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; { vm_object_t result; result = (vm_object_t) zalloc(obj_zone); _vm_object_allocate(type, size, result); return (result); } /* * vm_object_reference: * * Gets another reference to the given object. */ void vm_object_reference(object) vm_object_t object; { if (object == NULL) return; #if 0 /* object can be re-referenced during final cleaning */ KASSERT(!(object->flags & OBJ_DEAD), ("vm_object_reference: attempting to reference dead obj")); #endif object->ref_count++; if (object->type == OBJT_VNODE) { while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curproc)) { printf("vm_object_reference: delay in getting object\n"); } } } void vm_object_vndeallocate(object) vm_object_t object; { struct vnode *vp = (struct vnode *) object->handle; KASSERT(object->type == OBJT_VNODE, ("vm_object_vndeallocate: not a vnode object")); KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp")); #ifdef INVARIANTS if (object->ref_count == 0) { vprint("vm_object_vndeallocate", vp); panic("vm_object_vndeallocate: bad object reference count"); } #endif object->ref_count--; if (object->ref_count == 0) { vp->v_flag &= ~VTEXT; vm_object_clear_flag(object, OBJ_OPT); } vrele(vp); } /* * 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; while (object != NULL) { if (object->type == OBJT_VNODE) { vm_object_vndeallocate(object); return; } if (object->ref_count == 0) { panic("vm_object_deallocate: object deallocated too many times: %d", object->type); } else if (object->ref_count > 2) { object->ref_count--; return; } /* * Here on ref_count of one or two, which are special cases for * objects. */ if ((object->ref_count == 2) && (object->shadow_count == 0)) { vm_object_set_flag(object, OBJ_ONEMAPPING); object->ref_count--; return; } else if ((object->ref_count == 2) && (object->shadow_count == 1)) { object->ref_count--; if ((object->handle == NULL) && (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { vm_object_t robject; robject = LIST_FIRST(&object->shadow_head); KASSERT(robject != NULL, ("vm_object_deallocate: ref_count: %d, shadow_count: %d", object->ref_count, object->shadow_count)); if ((robject->handle == NULL) && (robject->type == OBJT_DEFAULT || robject->type == OBJT_SWAP)) { robject->ref_count++; while ( robject->paging_in_progress || object->paging_in_progress ) { vm_object_pip_sleep(robject, "objde1"); vm_object_pip_sleep(object, "objde2"); } if (robject->ref_count == 1) { robject->ref_count--; object = robject; goto doterm; } object = robject; vm_object_collapse(object); continue; } } return; } else { object->ref_count--; if (object->ref_count != 0) return; } doterm: temp = object->backing_object; if (temp) { LIST_REMOVE(object, shadow_list); temp->shadow_count--; if (temp->ref_count == 0) vm_object_clear_flag(temp, OBJ_OPT); temp->generation++; object->backing_object = NULL; } /* * Don't double-terminate, we could be in a termination * recursion due to the terminate having to sync data * to disk. */ if ((object->flags & OBJ_DEAD) == 0) vm_object_terminate(object); object = temp; } } /* * vm_object_terminate actually destroys the specified object, freeing * up all previously used resources. * * The object must be locked. * This routine may block. */ void vm_object_terminate(object) vm_object_t object; { vm_page_t p; int s; /* * Make sure no one uses us. */ vm_object_set_flag(object, OBJ_DEAD); /* * wait for the pageout daemon to be done with the object */ vm_object_pip_wait(object, "objtrm"); KASSERT(!object->paging_in_progress, ("vm_object_terminate: 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; /* * Freeze optimized copies. */ vm_freeze_copyopts(object, 0, object->size); /* * Clean pages and flush buffers. */ vm_object_page_clean(object, 0, 0, OBJPC_SYNC); vp = (struct vnode *) object->handle; vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0); } /* * Wait for any I/O to complete, after which there had better not * be any references left on the object. */ vm_object_pip_wait(object, "objtrm"); if (object->ref_count != 0) panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count); /* * Now free any remaining pages. For internal objects, this also * removes them from paging queues. Don't free wired pages, just * remove them from the object. */ s = splvm(); while ((p = TAILQ_FIRST(&object->memq)) != NULL) { if (p->busy || (p->flags & PG_BUSY)) panic("vm_object_terminate: freeing busy page %p\n", p); if (p->wire_count == 0) { vm_page_busy(p); vm_page_free(p); cnt.v_pfree++; } else { vm_page_busy(p); vm_page_remove(p); } } splx(s); /* * Let the pager know object is dead. */ vm_pager_deallocate(object); /* * Remove the object from the global object list. */ simple_lock(&vm_object_list_lock); TAILQ_REMOVE(&vm_object_list, object, object_list); simple_unlock(&vm_object_list_lock); wakeup(object); /* * Free the space for the object. */ zfree(obj_zone, object); } /* * vm_object_page_clean * * Clean all dirty pages in the specified range of object. Leaves page * on whatever queue it is currently on. If NOSYNC is set then do not * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC), * leaving the object dirty. * * When stuffing pages asynchronously, allow clustering. XXX we need a * synchronous clustering mode implementation. * * Odd semantics: if start == end, we clean everything. * * The object must be locked. */ void vm_object_page_clean(object, start, end, flags) vm_object_t object; vm_pindex_t start; vm_pindex_t end; int flags; { vm_page_t p, np; vm_offset_t tstart, tend; vm_pindex_t pi; struct vnode *vp; int clearobjflags; int pagerflags; int curgeneration; if (object->type != OBJT_VNODE || (object->flags & OBJ_MIGHTBEDIRTY) == 0) return; pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK; pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0; vp = object->handle; vm_object_set_flag(object, OBJ_CLEANING); /* * Handle 'entire object' case */ tstart = start; if (end == 0) { tend = object->size; } else { tend = end; } /* * If the caller is smart and only msync()s a range he knows is * dirty, we may be able to avoid an object scan. This results in * a phenominal improvement in performance. We cannot do this * as a matter of course because the object may be huge - e.g. * the size might be in the gigabytes or terrabytes. */ if (msync_flush_flags & MSYNC_FLUSH_HARDSEQ) { vm_offset_t tscan; int scanlimit; int scanreset; scanreset = object->resident_page_count / EASY_SCAN_FACTOR; if (scanreset < 16) scanreset = 16; pagerflags |= VM_PAGER_IGNORE_CLEANCHK; scanlimit = scanreset; tscan = tstart; while (tscan < tend) { curgeneration = object->generation; p = vm_page_lookup(object, tscan); if (p == NULL || p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) { if (--scanlimit == 0) break; ++tscan; continue; } vm_page_test_dirty(p); if ((p->dirty & p->valid) == 0) { if (--scanlimit == 0) break; ++tscan; continue; } /* * If we have been asked to skip nosync pages and * this is a nosync page, we can't continue. */ if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { if (--scanlimit == 0) break; ++tscan; continue; } scanlimit = scanreset; /* * This returns 0 if it was unable to busy the first * page (i.e. had to sleep). */ tscan += vm_object_page_collect_flush(object, p, curgeneration, pagerflags); } /* * If everything was dirty and we flushed it successfully, * and the requested range is not the entire object, we * don't have to mess with CLEANCHK or MIGHTBEDIRTY and can * return immediately. */ if (tscan >= tend && (tstart || tend < object->size)) { vm_object_clear_flag(object, OBJ_CLEANING); return; } pagerflags &= ~VM_PAGER_IGNORE_CLEANCHK; } /* * Generally set CLEANCHK interlock and make the page read-only so * we can then clear the object flags. * * However, if this is a nosync mmap then the object is likely to * stay dirty so do not mess with the page and do not clear the * object flags. */ clearobjflags = 1; for(p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) { vm_page_flag_set(p, PG_CLEANCHK); if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) clearobjflags = 0; else vm_page_protect(p, VM_PROT_READ); } if (clearobjflags && (tstart == 0) && (tend == object->size)) { struct vnode *vp; vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); if (object->type == OBJT_VNODE && (vp = (struct vnode *)object->handle) != NULL) { if (vp->v_flag & VOBJDIRTY) { simple_lock(&vp->v_interlock); vp->v_flag &= ~VOBJDIRTY; simple_unlock(&vp->v_interlock); } } } rescan: curgeneration = object->generation; for(p = TAILQ_FIRST(&object->memq); p; p = np) { int n; np = TAILQ_NEXT(p, listq); again: pi = p->pindex; if (((p->flags & PG_CLEANCHK) == 0) || (pi < tstart) || (pi >= tend) || (p->valid == 0) || ((p->queue - p->pc) == PQ_CACHE)) { vm_page_flag_clear(p, PG_CLEANCHK); continue; } vm_page_test_dirty(p); if ((p->dirty & p->valid) == 0) { vm_page_flag_clear(p, PG_CLEANCHK); continue; } /* * If we have been asked to skip nosync pages and this is a * nosync page, skip it. Note that the object flags were * not cleared in this case so we do not have to set them. */ if ((flags & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) { vm_page_flag_clear(p, PG_CLEANCHK); continue; } n = vm_object_page_collect_flush(object, p, curgeneration, pagerflags); if (n == 0) goto rescan; if (object->generation != curgeneration) goto rescan; /* * Try to optimize the next page. If we can't we pick up * our (random) scan where we left off. */ if (msync_flush_flags & MSYNC_FLUSH_SOFTSEQ) { if ((p = vm_page_lookup(object, pi + n)) != NULL) goto again; } } #if 0 VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc); #endif vm_object_clear_flag(object, OBJ_CLEANING); return; } static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags) { int runlen; int s; int maxf; int chkb; int maxb; int i; vm_pindex_t pi; vm_page_t maf[vm_pageout_page_count]; vm_page_t mab[vm_pageout_page_count]; vm_page_t ma[vm_pageout_page_count]; s = splvm(); pi = p->pindex; while (vm_page_sleep_busy(p, TRUE, "vpcwai")) { if (object->generation != curgeneration) { splx(s); return(0); } } maxf = 0; for(i = 1; i < vm_pageout_page_count; i++) { vm_page_t tp; if ((tp = vm_page_lookup(object, pi + i)) != NULL) { if ((tp->flags & PG_BUSY) || ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && (tp->flags & PG_CLEANCHK) == 0) || (tp->busy != 0)) break; if((tp->queue - tp->pc) == PQ_CACHE) { vm_page_flag_clear(tp, PG_CLEANCHK); break; } vm_page_test_dirty(tp); if ((tp->dirty & tp->valid) == 0) { vm_page_flag_clear(tp, 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++) { vm_page_t tp; if ((tp = vm_page_lookup(object, pi - i)) != NULL) { if ((tp->flags & PG_BUSY) || ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 && (tp->flags & PG_CLEANCHK) == 0) || (tp->busy != 0)) break; if((tp->queue - tp->pc) == PQ_CACHE) { vm_page_flag_clear(tp, PG_CLEANCHK); break; } vm_page_test_dirty(tp); if ((tp->dirty & tp->valid) == 0) { vm_page_flag_clear(tp, PG_CLEANCHK); break; } mab[ i - 1 ] = tp; maxb++; continue; } break; } } for(i = 0; i < maxb; i++) { int index = (maxb - i) - 1; ma[index] = mab[i]; vm_page_flag_clear(ma[index], PG_CLEANCHK); } vm_page_flag_clear(p, PG_CLEANCHK); ma[maxb] = p; for(i = 0; i < maxf; i++) { int index = (maxb + i) + 1; ma[index] = maf[i]; vm_page_flag_clear(ma[index], PG_CLEANCHK); } runlen = maxb + maxf + 1; splx(s); vm_pageout_flush(ma, runlen, pagerflags); for (i = 0; i < runlen; i++) { if (ma[i]->valid & ma[i]->dirty) { vm_page_protect(ma[i], VM_PROT_READ); vm_page_flag_set(ma[i], PG_CLEANCHK); /* * maxf will end up being the actual number of pages * we wrote out contiguously, non-inclusive of the * first page. We do not count look-behind pages. */ if (i >= maxb + 1 && (maxf > i - maxb - 1)) maxf = i - maxb - 1; } } return(maxf + 1); } #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) vm_object_t object; { vm_page_t p, next; for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { next = TAILQ_NEXT(p, listq); vm_page_deactivate(p); } } #endif /* * Same as vm_object_pmap_copy, except range checking really * works, and is meant for small sections of an object. * * This code protects resident pages by making them read-only * and is typically called on a fork or split when a page * is converted to copy-on-write. * * NOTE: If the page is already at VM_PROT_NONE, calling * vm_page_protect will have no effect. */ void vm_object_pmap_copy_1(object, start, end) vm_object_t object; vm_pindex_t start; vm_pindex_t end; { vm_pindex_t idx; vm_page_t p; if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0) return; for (idx = start; idx < end; idx++) { p = vm_page_lookup(object, idx); if (p == NULL) continue; vm_page_protect(p, VM_PROT_READ); } } /* * 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) vm_object_t object; vm_pindex_t start; vm_pindex_t end; { vm_page_t p; if (object == NULL) return; for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) { if (p->pindex >= start && p->pindex < end) vm_page_protect(p, VM_PROT_NONE); } if ((start == 0) && (object->size == end)) vm_object_clear_flag(object, OBJ_WRITEABLE); } /* * vm_object_madvise: * * Implements the madvise function at the object/page level. * * MADV_WILLNEED (any object) * * Activate the specified pages if they are resident. * * MADV_DONTNEED (any object) * * Deactivate the specified pages if they are resident. * * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, * OBJ_ONEMAPPING only) * * Deactivate and clean the specified pages if they are * resident. This permits the process to reuse the pages * without faulting or the kernel to reclaim the pages * without I/O. */ void vm_object_madvise(object, pindex, count, advise) vm_object_t object; vm_pindex_t pindex; int count; int advise; { vm_pindex_t end, tpindex; vm_object_t tobject; vm_page_t m; if (object == NULL) return; end = pindex + count; /* * Locate and adjust resident pages */ for (; pindex < end; pindex += 1) { relookup: tobject = object; tpindex = pindex; shadowlookup: /* * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages * and those pages must be OBJ_ONEMAPPING. */ if (advise == MADV_FREE) { if ((tobject->type != OBJT_DEFAULT && tobject->type != OBJT_SWAP) || (tobject->flags & OBJ_ONEMAPPING) == 0) { continue; } } m = vm_page_lookup(tobject, tpindex); if (m == NULL) { /* * There may be swap even if there is no backing page */ if (advise == MADV_FREE && tobject->type == OBJT_SWAP) swap_pager_freespace(tobject, tpindex, 1); /* * next object */ tobject = tobject->backing_object; if (tobject == NULL) continue; tpindex += OFF_TO_IDX(tobject->backing_object_offset); goto shadowlookup; } /* * If the page is busy or not in a normal active state, * we skip it. If the page is not managed there are no * page queues to mess with. Things can break if we mess * with pages in any of the below states. */ if ( m->hold_count || m->wire_count || (m->flags & PG_UNMANAGED) || m->valid != VM_PAGE_BITS_ALL ) { continue; } if (vm_page_sleep_busy(m, TRUE, "madvpo")) goto relookup; if (advise == MADV_WILLNEED) { vm_page_activate(m); } else if (advise == MADV_DONTNEED) { vm_page_dontneed(m); } else if (advise == MADV_FREE) { /* * Mark the page clean. This will allow the page * to be freed up by the system. However, such pages * are often reused quickly by malloc()/free() * so we do not do anything that would cause * a page fault if we can help it. * * Specifically, we do not try to actually free * the page now nor do we try to put it in the * cache (which would cause a page fault on reuse). * * But we do make the page is freeable as we * can without actually taking the step of unmapping * it. */ pmap_clear_modify(m); m->dirty = 0; m->act_count = 0; vm_page_dontneed(m); if (tobject->type == OBJT_SWAP) swap_pager_freespace(tobject, tpindex, 1); } } } /* * 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; { vm_object_t source; vm_object_t result; source = *object; /* * Don't create the new object if the old object isn't shared. */ if (source != NULL && source->ref_count == 1 && source->handle == NULL && (source->type == OBJT_DEFAULT || source->type == OBJT_SWAP)) return; /* * 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. * * Try to optimize the result object's page color when shadowing * in order to maintain page coloring consistency in the combined * shadowed object. */ result->backing_object = source; if (source) { LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list); source->shadow_count++; source->generation++; result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK; } /* * 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; } #define OBSC_TEST_ALL_SHADOWED 0x0001 #define OBSC_COLLAPSE_NOWAIT 0x0002 #define OBSC_COLLAPSE_WAIT 0x0004 static __inline int vm_object_backing_scan(vm_object_t object, int op) { int s; int r = 1; vm_page_t p; vm_object_t backing_object; vm_pindex_t backing_offset_index; s = splvm(); backing_object = object->backing_object; backing_offset_index = OFF_TO_IDX(object->backing_object_offset); /* * Initial conditions */ if (op & OBSC_TEST_ALL_SHADOWED) { /* * We do not want to have to test for the existence of * swap pages in the backing object. XXX but with the * new swapper this would be pretty easy to do. * * XXX what about anonymous MAP_SHARED memory that hasn't * been ZFOD faulted yet? If we do not test for this, the * shadow test may succeed! XXX */ if (backing_object->type != OBJT_DEFAULT) { splx(s); return(0); } } if (op & OBSC_COLLAPSE_WAIT) { vm_object_set_flag(backing_object, OBJ_DEAD); } /* * Our scan */ p = TAILQ_FIRST(&backing_object->memq); while (p) { vm_page_t next = TAILQ_NEXT(p, listq); vm_pindex_t new_pindex = p->pindex - backing_offset_index; if (op & OBSC_TEST_ALL_SHADOWED) { vm_page_t pp; /* * Ignore pages outside the parent object's range * and outside the parent object's mapping of the * backing object. * * note that we do not busy the backing object's * page. */ if ( p->pindex < backing_offset_index || new_pindex >= object->size ) { p = next; continue; } /* * See if the parent has the page or if the parent's * object pager has the page. If the parent has the * page but the page is not valid, the parent's * object pager must have the page. * * If this fails, the parent does not completely shadow * the object and we might as well give up now. */ pp = vm_page_lookup(object, new_pindex); if ( (pp == NULL || pp->valid == 0) && !vm_pager_has_page(object, new_pindex, NULL, NULL) ) { r = 0; break; } } /* * Check for busy page */ if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) { vm_page_t pp; if (op & OBSC_COLLAPSE_NOWAIT) { if ( (p->flags & PG_BUSY) || !p->valid || p->hold_count || p->wire_count || p->busy ) { p = next; continue; } } else if (op & OBSC_COLLAPSE_WAIT) { if (vm_page_sleep_busy(p, TRUE, "vmocol")) { /* * If we slept, anything could have * happened. Since the object is * marked dead, the backing offset * should not have changed so we * just restart our scan. */ p = TAILQ_FIRST(&backing_object->memq); continue; } } /* * Busy the page */ vm_page_busy(p); KASSERT( p->object == backing_object, ("vm_object_qcollapse(): object mismatch") ); /* * Destroy any associated swap */ if (backing_object->type == OBJT_SWAP) { swap_pager_freespace( backing_object, p->pindex, 1 ); } if ( p->pindex < backing_offset_index || new_pindex >= object->size ) { /* * Page is out of the parent object's range, we * can simply destroy it. */ vm_page_protect(p, VM_PROT_NONE); vm_page_free(p); p = next; continue; } pp = vm_page_lookup(object, new_pindex); if ( pp != NULL || vm_pager_has_page(object, new_pindex, NULL, NULL) ) { /* * page already exists in parent OR swap exists * for this location in the parent. Destroy * the original page from the backing object. * * Leave the parent's page alone */ vm_page_protect(p, VM_PROT_NONE); vm_page_free(p); p = next; continue; } /* * Page does not exist in parent, rename the * page from the backing object to the main object. * * If the page was mapped to a process, it can remain * mapped through the rename. */ if ((p->queue - p->pc) == PQ_CACHE) vm_page_deactivate(p); vm_page_rename(p, object, new_pindex); /* page automatically made dirty by rename */ } p = next; } splx(s); return(r); } /* * 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) vm_object_t object; { vm_object_t backing_object = object->backing_object; if (backing_object->ref_count != 1) return; backing_object->ref_count += 2; vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT); 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; { while (TRUE) { vm_object_t backing_object; /* * Verify that the conditions are right for collapse: * * The object exists and the backing object exists. */ if (object == NULL) break; if ((backing_object = object->backing_object) == NULL) break; /* * 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)) { break; } if ( object->paging_in_progress != 0 || backing_object->paging_in_progress != 0 ) { vm_object_qcollapse(object); break; } /* * We know that we can either collapse the backing object (if * the parent is the only reference to it) or (perhaps) have * the parent bypass the object if the parent happens to shadow * all the resident pages in the entire backing object. * * This is ignoring pager-backed pages such as swap pages. * vm_object_backing_scan fails the shadowing test in this * case. */ if (backing_object->ref_count == 1) { /* * If there is exactly one reference to the backing * object, we can collapse it into the parent. */ vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT); /* * Move the pager from backing_object to object. */ if (backing_object->type == OBJT_SWAP) { vm_object_pip_add(backing_object, 1); /* * scrap the paging_offset junk and do a * discrete copy. This also removes major * assumptions about how the swap-pager * works from where it doesn't belong. The * new swapper is able to optimize the * destroy-source case. */ vm_object_pip_add(object, 1); swap_pager_copy( backing_object, object, OFF_TO_IDX(object->backing_object_offset), TRUE); 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. */ LIST_REMOVE(object, shadow_list); object->backing_object->shadow_count--; object->backing_object->generation++; if (backing_object->backing_object) { LIST_REMOVE(backing_object, shadow_list); backing_object->backing_object->shadow_count--; backing_object->backing_object->generation++; } object->backing_object = backing_object->backing_object; if (object->backing_object) { LIST_INSERT_HEAD( &object->backing_object->shadow_head, object, shadow_list ); object->backing_object->shadow_count++; object->backing_object->generation++; } 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. */ KASSERT(backing_object->ref_count == 1, ("backing_object %p was somehow re-referenced during collapse!", backing_object)); KASSERT(TAILQ_FIRST(&backing_object->memq) == NULL, ("backing_object %p somehow has left over pages during collapse!", backing_object)); TAILQ_REMOVE( &vm_object_list, backing_object, object_list ); vm_object_count--; zfree(obj_zone, backing_object); object_collapses++; } else { vm_object_t new_backing_object; /* * If we do not entirely shadow the backing object, * there is nothing we can do so we give up. */ if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) { break; } /* * 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. */ LIST_REMOVE(object, shadow_list); backing_object->shadow_count--; backing_object->generation++; new_backing_object = backing_object->backing_object; if ((object->backing_object = new_backing_object) != NULL) { vm_object_reference(new_backing_object); LIST_INSERT_HEAD( &new_backing_object->shadow_head, object, shadow_list ); new_backing_object->shadow_count++; new_backing_object->generation++; 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, but * we do anyway. */ vm_object_deallocate(backing_object); 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) vm_object_t object; vm_pindex_t start; vm_pindex_t end; boolean_t clean_only; { vm_page_t p, next; unsigned int size; int all; if (object == NULL || object->resident_page_count == 0) return; all = ((end == 0) && (start == 0)); /* * Since physically-backed objects do not use managed pages, we can't * remove pages from the object (we must instead remove the page * references, and then destroy the object). */ KASSERT(object->type != OBJT_PHYS, ("attempt to remove pages from a physical object")); vm_object_pip_add(object, 1); again: size = end - start; if (all || size > object->resident_page_count / 4) { for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) { next = TAILQ_NEXT(p, listq); if (all || ((start <= p->pindex) && (p->pindex < end))) { if (p->wire_count != 0) { vm_page_protect(p, VM_PROT_NONE); if (!clean_only) p->valid = 0; continue; } /* * The busy flags are only cleared at * interrupt -- minimize the spl transitions */ if (vm_page_sleep_busy(p, TRUE, "vmopar")) goto again; if (clean_only && p->valid) { vm_page_test_dirty(p); if (p->valid & p->dirty) continue; } vm_page_busy(p); vm_page_protect(p, VM_PROT_NONE); vm_page_free(p); } } } else { while (size > 0) { if ((p = vm_page_lookup(object, start)) != 0) { if (p->wire_count != 0) { vm_page_protect(p, VM_PROT_NONE); if (!clean_only) p->valid = 0; start += 1; size -= 1; continue; } /* * The busy flags are only cleared at * interrupt -- minimize the spl transitions */ if (vm_page_sleep_busy(p, TRUE, "vmopar")) goto again; if (clean_only && p->valid) { vm_page_test_dirty(p); if (p->valid & p->dirty) { start += 1; size -= 1; continue; } } vm_page_busy(p); vm_page_protect(p, VM_PROT_NONE); 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) vm_object_t prev_object; vm_pindex_t prev_pindex; vm_size_t prev_size, next_size; { vm_pindex_t next_pindex; if (prev_object == NULL) { return (TRUE); } if (prev_object->type != OBJT_DEFAULT && prev_object->type != OBJT_SWAP) { return (FALSE); } /* * 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->backing_object != NULL) { return (FALSE); } prev_size >>= PAGE_SHIFT; next_size >>= PAGE_SHIFT; next_pindex = prev_pindex + prev_size; if ((prev_object->ref_count > 1) && (prev_object->size != next_pindex)) { return (FALSE); } /* * Remove any pages that may still be in the object from a previous * deallocation. */ if (next_pindex < prev_object->size) { vm_object_page_remove(prev_object, next_pindex, next_pindex + next_size, FALSE); if (prev_object->type == OBJT_SWAP) swap_pager_freespace(prev_object, next_pindex, next_size); } /* * Extend the object if necessary. */ if (next_pindex + next_size > prev_object->size) prev_object->size = next_pindex + next_size; return (TRUE); } void vm_object_set_writeable_dirty(vm_object_t object) { struct vnode *vp; vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); if (object->type == OBJT_VNODE && (vp = (struct vnode *)object->handle) != NULL) { if ((vp->v_flag & VOBJDIRTY) == 0) { simple_lock(&vp->v_interlock); vp->v_flag |= VOBJDIRTY; simple_unlock(&vp->v_interlock); } } } #include "opt_ddb.h" #ifdef DDB #include #include #include 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)); 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->eflags & MAP_ENTRY_IS_SUB_MAP) { tmpm = entry->object.sub_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) != NULL) { 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 = allproc.lh_first; p != 0; p = p->p_list.le_next) { if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */) 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( mb_map, object, 0)) return 1; return 0; } DB_SHOW_COMMAND(vmochk, 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 = TAILQ_FIRST(&vm_object_list); object != NULL; object = TAILQ_NEXT(object, object_list)) { if (object->handle == NULL && (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) { if (object->ref_count == 0) { db_printf("vmochk: internal obj has zero ref count: %ld\n", (long)object->size); } if (!vm_object_in_map(object)) { db_printf( "vmochk: internal obj is not in a map: " "ref: %d, size: %lu: 0x%lx, backing_object: %p\n", object->ref_count, (u_long)object->size, (u_long)object->size, (void *)object->backing_object); } } } } /* * vm_object_print: [ debug ] */ DB_SHOW_COMMAND(object, vm_object_print_static) { /* XXX convert args. */ vm_object_t object = (vm_object_t)addr; boolean_t full = have_addr; vm_page_t p; /* XXX count is an (unused) arg. Avoid shadowing it. */ #define count was_count int count; if (object == NULL) return; db_iprintf( "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n", object, (int)object->type, (u_long)object->size, object->resident_page_count, object->ref_count, object->flags); /* * XXX no %qd in kernel. Truncate object->backing_object_offset. */ db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n", object->shadow_count, object->backing_object ? object->backing_object->ref_count : 0, object->backing_object, (long)object->backing_object_offset); if (!full) return; db_indent += 2; count = 0; for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) { if (count == 0) db_iprintf("memory:="); else if (count == 6) { db_printf("\n"); db_iprintf(" ..."); count = 0; } else db_printf(","); count++; db_printf("(off=0x%lx,page=0x%lx)", (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p)); } if (count != 0) db_printf("\n"); db_indent -= 2; } /* XXX. */ #undef count /* XXX need this non-static entry for calling from vm_map_print. */ void vm_object_print(addr, have_addr, count, modif) /* db_expr_t */ long addr; boolean_t have_addr; /* db_expr_t */ long count; char *modif; { vm_object_print_static(addr, have_addr, count, modif); } DB_SHOW_COMMAND(vmopag, vm_object_print_pages) { vm_object_t object; int nl = 0; int c; for (object = TAILQ_FIRST(&vm_object_list); object != NULL; object = TAILQ_NEXT(object, object_list)) { vm_pindex_t idx, fidx; vm_pindex_t osize; vm_offset_t pa = -1, padiff; int rcount; vm_page_t m; db_printf("new object: %p\n", (void *)object); if ( nl > 18) { c = cngetc(); if (c != ' ') return; nl = 0; } nl++; rcount = 0; fidx = 0; osize = object->size; if (osize > 128) osize = 128; for(idx=0;idx 18) { c = cngetc(); if (c != ' ') return; nl = 0; } nl++; rcount = 0; } continue; } if (rcount && (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) { ++rcount; continue; } if (rcount) { padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m); padiff >>= PAGE_SHIFT; padiff &= PQ_L2_MASK; if (padiff == 0) { pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE; ++rcount; continue; } db_printf(" index(%ld)run(%d)pa(0x%lx)", (long)fidx, rcount, (long)pa); db_printf("pd(%ld)\n", (long)padiff); if ( nl > 18) { c = cngetc(); if (c != ' ') return; nl = 0; } nl++; } fidx = idx; pa = VM_PAGE_TO_PHYS(m); rcount = 1; } if (rcount) { db_printf(" index(%ld)run(%d)pa(0x%lx)\n", (long)fidx, rcount, (long)pa); if ( nl > 18) { c = cngetc(); if (c != ' ') return; nl = 0; } nl++; } } } #endif /* DDB */