/*- * Copyright (c) 1991 Regents of the University of California. * All rights reserved. * Copyright (c) 1998 Matthew Dillon. 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. * 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_page.c 7.4 (Berkeley) 5/7/91 */ /*- * 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. */ /* * GENERAL RULES ON VM_PAGE MANIPULATION * * - a pageq mutex is required when adding or removing a page from a * page queue (vm_page_queue[]), regardless of other mutexes or the * busy state of a page. * * - a hash chain mutex is required when associating or disassociating * a page from the VM PAGE CACHE hash table (vm_page_buckets), * regardless of other mutexes or the busy state of a page. * * - either a hash chain mutex OR a busied page is required in order * to modify the page flags. A hash chain mutex must be obtained in * order to busy a page. A page's flags cannot be modified by a * hash chain mutex if the page is marked busy. * * - The object memq mutex is held when inserting or removing * pages from an object (vm_page_insert() or vm_page_remove()). This * is different from the object's main mutex. * * Generally speaking, you have to be aware of side effects when running * vm_page ops. A vm_page_lookup() will return with the hash chain * locked, whether it was able to lookup the page or not. vm_page_free(), * vm_page_cache(), vm_page_activate(), and a number of other routines * will release the hash chain mutex for you. Intermediate manipulation * routines such as vm_page_flag_set() expect the hash chain to be held * on entry and the hash chain will remain held on return. * * pageq scanning can only occur with the pageq in question locked. * We have a known bottleneck with the active queue, but the cache * and free queues are actually arrays already. */ /* * Resident memory management module. */ #include __FBSDID("$FreeBSD$"); #include "opt_vm.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(__amd64__) || defined (__i386__) extern struct sysctl_oid_list sysctl__vm_pmap_children; #else SYSCTL_NODE(_vm, OID_AUTO, pmap, CTLFLAG_RD, 0, "VM/pmap parameters"); #endif static uint64_t pmap_tryrelock_calls; SYSCTL_QUAD(_vm_pmap, OID_AUTO, tryrelock_calls, CTLFLAG_RD, &pmap_tryrelock_calls, 0, "Number of tryrelock calls"); static int pmap_tryrelock_restart; SYSCTL_INT(_vm_pmap, OID_AUTO, tryrelock_restart, CTLFLAG_RD, &pmap_tryrelock_restart, 0, "Number of tryrelock restarts"); static int pmap_tryrelock_race; SYSCTL_INT(_vm_pmap, OID_AUTO, tryrelock_race, CTLFLAG_RD, &pmap_tryrelock_race, 0, "Number of tryrelock pmap race cases"); /* * Associated with page of user-allocatable memory is a * page structure. */ struct vpgqueues vm_page_queues[PQ_COUNT]; struct vpglocks vm_page_queue_lock; struct vpglocks vm_page_queue_free_lock; struct vpglocks pa_lock[PA_LOCK_COUNT] __aligned(CACHE_LINE_SIZE); vm_page_t vm_page_array = 0; int vm_page_array_size = 0; long first_page = 0; int vm_page_zero_count = 0; static int boot_pages = UMA_BOOT_PAGES; TUNABLE_INT("vm.boot_pages", &boot_pages); SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0, "number of pages allocated for bootstrapping the VM system"); static void vm_page_enqueue(int queue, vm_page_t m); /* Make sure that u_long is at least 64 bits when PAGE_SIZE is 32K. */ #if PAGE_SIZE == 32768 #ifdef CTASSERT CTASSERT(sizeof(u_long) >= 8); #endif #endif /* * Try to acquire a physical address lock while a pmap is locked. If we * fail to trylock we unlock and lock the pmap directly and cache the * locked pa in *locked. The caller should then restart their loop in case * the virtual to physical mapping has changed. */ int vm_page_pa_tryrelock(pmap_t pmap, vm_paddr_t pa, vm_paddr_t *locked) { vm_paddr_t lockpa; uint32_t gen_count; gen_count = pmap->pm_gen_count; atomic_add_long((volatile long *)&pmap_tryrelock_calls, 1); lockpa = *locked; *locked = pa; if (lockpa) { PA_LOCK_ASSERT(lockpa, MA_OWNED); if (PA_LOCKPTR(pa) == PA_LOCKPTR(lockpa)) return (0); PA_UNLOCK(lockpa); } if (PA_TRYLOCK(pa)) return (0); PMAP_UNLOCK(pmap); atomic_add_int((volatile int *)&pmap_tryrelock_restart, 1); PA_LOCK(pa); PMAP_LOCK(pmap); if (pmap->pm_gen_count != gen_count + 1) { pmap->pm_retries++; atomic_add_int((volatile int *)&pmap_tryrelock_race, 1); return (EAGAIN); } return (0); } /* * vm_set_page_size: * * Sets the page size, perhaps based upon the memory * size. Must be called before any use of page-size * dependent functions. */ void vm_set_page_size(void) { if (cnt.v_page_size == 0) cnt.v_page_size = PAGE_SIZE; if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0) panic("vm_set_page_size: page size not a power of two"); } /* * vm_page_blacklist_lookup: * * See if a physical address in this page has been listed * in the blacklist tunable. Entries in the tunable are * separated by spaces or commas. If an invalid integer is * encountered then the rest of the string is skipped. */ static int vm_page_blacklist_lookup(char *list, vm_paddr_t pa) { vm_paddr_t bad; char *cp, *pos; for (pos = list; *pos != '\0'; pos = cp) { bad = strtoq(pos, &cp, 0); if (*cp != '\0') { if (*cp == ' ' || *cp == ',') { cp++; if (cp == pos) continue; } else break; } if (pa == trunc_page(bad)) return (1); } return (0); } /* * vm_page_startup: * * Initializes the resident memory module. * * Allocates memory for the page cells, and * for the object/offset-to-page hash table headers. * Each page cell is initialized and placed on the free list. */ vm_offset_t vm_page_startup(vm_offset_t vaddr) { vm_offset_t mapped; vm_paddr_t page_range; vm_paddr_t new_end; int i; vm_paddr_t pa; int nblocks; vm_paddr_t last_pa; char *list; /* the biggest memory array is the second group of pages */ vm_paddr_t end; vm_paddr_t biggestsize; vm_paddr_t low_water, high_water; int biggestone; biggestsize = 0; biggestone = 0; nblocks = 0; vaddr = round_page(vaddr); for (i = 0; phys_avail[i + 1]; i += 2) { phys_avail[i] = round_page(phys_avail[i]); phys_avail[i + 1] = trunc_page(phys_avail[i + 1]); } low_water = phys_avail[0]; high_water = phys_avail[1]; for (i = 0; phys_avail[i + 1]; i += 2) { vm_paddr_t size = phys_avail[i + 1] - phys_avail[i]; if (size > biggestsize) { biggestone = i; biggestsize = size; } if (phys_avail[i] < low_water) low_water = phys_avail[i]; if (phys_avail[i + 1] > high_water) high_water = phys_avail[i + 1]; ++nblocks; } #ifdef XEN low_water = 0; #endif end = phys_avail[biggestone+1]; /* * Initialize the locks. */ mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF | MTX_RECURSE); mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL, MTX_DEF); /* Setup page locks. */ for (i = 0; i < PA_LOCK_COUNT; i++) mtx_init(&pa_lock[i].data, "page lock", NULL, MTX_DEF | MTX_RECURSE | MTX_DUPOK); /* * Initialize the queue headers for the hold queue, the active queue, * and the inactive queue. */ for (i = 0; i < PQ_COUNT; i++) TAILQ_INIT(&vm_page_queues[i].pl); vm_page_queues[PQ_INACTIVE].cnt = &cnt.v_inactive_count; vm_page_queues[PQ_ACTIVE].cnt = &cnt.v_active_count; vm_page_queues[PQ_HOLD].cnt = &cnt.v_active_count; /* * Allocate memory for use when boot strapping the kernel memory * allocator. */ new_end = end - (boot_pages * UMA_SLAB_SIZE); new_end = trunc_page(new_end); mapped = pmap_map(&vaddr, new_end, end, VM_PROT_READ | VM_PROT_WRITE); bzero((void *)mapped, end - new_end); uma_startup((void *)mapped, boot_pages); #if defined(__amd64__) || defined(__i386__) || defined(__arm__) /* * Allocate a bitmap to indicate that a random physical page * needs to be included in a minidump. * * The amd64 port needs this to indicate which direct map pages * need to be dumped, via calls to dump_add_page()/dump_drop_page(). * * However, i386 still needs this workspace internally within the * minidump code. In theory, they are not needed on i386, but are * included should the sf_buf code decide to use them. */ page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE; vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY); new_end -= vm_page_dump_size; vm_page_dump = (void *)(uintptr_t)pmap_map(&vaddr, new_end, new_end + vm_page_dump_size, VM_PROT_READ | VM_PROT_WRITE); bzero((void *)vm_page_dump, vm_page_dump_size); #endif /* * Compute the number of pages of memory that will be available for * use (taking into account the overhead of a page structure per * page). */ first_page = low_water / PAGE_SIZE; #ifdef VM_PHYSSEG_SPARSE page_range = 0; for (i = 0; phys_avail[i + 1] != 0; i += 2) page_range += atop(phys_avail[i + 1] - phys_avail[i]); #elif defined(VM_PHYSSEG_DENSE) page_range = high_water / PAGE_SIZE - first_page; #else #error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined." #endif end = new_end; /* * Reserve an unmapped guard page to trap access to vm_page_array[-1]. */ vaddr += PAGE_SIZE; /* * Initialize the mem entry structures now, and put them in the free * queue. */ new_end = trunc_page(end - page_range * sizeof(struct vm_page)); mapped = pmap_map(&vaddr, new_end, end, VM_PROT_READ | VM_PROT_WRITE); vm_page_array = (vm_page_t) mapped; #if VM_NRESERVLEVEL > 0 /* * Allocate memory for the reservation management system's data * structures. */ new_end = vm_reserv_startup(&vaddr, new_end, high_water); #endif #ifdef __amd64__ /* * pmap_map on amd64 comes out of the direct-map, not kvm like i386, * so the pages must be tracked for a crashdump to include this data. * This includes the vm_page_array and the early UMA bootstrap pages. */ for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE) dump_add_page(pa); #endif phys_avail[biggestone + 1] = new_end; /* * Clear all of the page structures */ bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page)); for (i = 0; i < page_range; i++) vm_page_array[i].order = VM_NFREEORDER; vm_page_array_size = page_range; /* * Initialize the physical memory allocator. */ vm_phys_init(); /* * Add every available physical page that is not blacklisted to * the free lists. */ cnt.v_page_count = 0; cnt.v_free_count = 0; list = getenv("vm.blacklist"); for (i = 0; phys_avail[i + 1] != 0; i += 2) { pa = phys_avail[i]; last_pa = phys_avail[i + 1]; while (pa < last_pa) { if (list != NULL && vm_page_blacklist_lookup(list, pa)) printf("Skipping page with pa 0x%jx\n", (uintmax_t)pa); else vm_phys_add_page(pa); pa += PAGE_SIZE; } } freeenv(list); #if VM_NRESERVLEVEL > 0 /* * Initialize the reservation management system. */ vm_reserv_init(); #endif return (vaddr); } void vm_page_flag_set(vm_page_t m, unsigned short bits) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); m->flags |= bits; } void vm_page_flag_clear(vm_page_t m, unsigned short bits) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); m->flags &= ~bits; } void vm_page_busy(vm_page_t m) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); KASSERT((m->oflags & VPO_BUSY) == 0, ("vm_page_busy: page already busy!!!")); m->oflags |= VPO_BUSY; } /* * vm_page_flash: * * wakeup anyone waiting for the page. */ void vm_page_flash(vm_page_t m) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (m->oflags & VPO_WANTED) { m->oflags &= ~VPO_WANTED; wakeup(m); } } /* * vm_page_wakeup: * * clear the VPO_BUSY flag and wakeup anyone waiting for the * page. * */ void vm_page_wakeup(vm_page_t m) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); KASSERT(m->oflags & VPO_BUSY, ("vm_page_wakeup: page not busy!!!")); m->oflags &= ~VPO_BUSY; vm_page_flash(m); } void vm_page_io_start(vm_page_t m) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); m->busy++; } void vm_page_io_finish(vm_page_t m) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); m->busy--; if (m->busy == 0) vm_page_flash(m); } /* * Keep page from being freed by the page daemon * much of the same effect as wiring, except much lower * overhead and should be used only for *very* temporary * holding ("wiring"). */ void vm_page_hold(vm_page_t mem) { vm_page_lock_assert(mem, MA_OWNED); mem->hold_count++; } void vm_page_unhold(vm_page_t mem) { vm_page_lock_assert(mem, MA_OWNED); --mem->hold_count; KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!")); if (mem->hold_count == 0 && VM_PAGE_INQUEUE2(mem, PQ_HOLD)) { vm_page_lock_queues(); vm_page_free_toq(mem); vm_page_unlock_queues(); } } /* * vm_page_free: * * Free a page. */ void vm_page_free(vm_page_t m) { m->flags &= ~PG_ZERO; vm_page_free_toq(m); } /* * vm_page_free_zero: * * Free a page to the zerod-pages queue */ void vm_page_free_zero(vm_page_t m) { m->flags |= PG_ZERO; vm_page_free_toq(m); } /* * vm_page_sleep: * * Sleep and release the page and page queues locks. * * The object containing the given page must be locked. */ void vm_page_sleep(vm_page_t m, const char *msg) { VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (mtx_owned(&vm_page_queue_mtx)) vm_page_unlock_queues(); if (mtx_owned(vm_page_lockptr(m))) vm_page_unlock(m); /* * It's possible that while we sleep, the page will get * unbusied and freed. If we are holding the object * lock, we will assume we hold a reference to the object * such that even if m->object changes, we can re-lock * it. */ m->oflags |= VPO_WANTED; msleep(m, VM_OBJECT_MTX(m->object), PVM, msg, 0); } /* * vm_page_dirty: * * make page all dirty */ void vm_page_dirty(vm_page_t m) { KASSERT((m->flags & PG_CACHED) == 0, ("vm_page_dirty: page in cache!")); KASSERT(!VM_PAGE_IS_FREE(m), ("vm_page_dirty: page is free!")); KASSERT(m->valid == VM_PAGE_BITS_ALL, ("vm_page_dirty: page is invalid!")); m->dirty = VM_PAGE_BITS_ALL; } /* * vm_page_splay: * * Implements Sleator and Tarjan's top-down splay algorithm. Returns * the vm_page containing the given pindex. If, however, that * pindex is not found in the vm_object, returns a vm_page that is * adjacent to the pindex, coming before or after it. */ vm_page_t vm_page_splay(vm_pindex_t pindex, vm_page_t root) { struct vm_page dummy; vm_page_t lefttreemax, righttreemin, y; if (root == NULL) return (root); lefttreemax = righttreemin = &dummy; for (;; root = y) { if (pindex < root->pindex) { if ((y = root->left) == NULL) break; if (pindex < y->pindex) { /* Rotate right. */ root->left = y->right; y->right = root; root = y; if ((y = root->left) == NULL) break; } /* Link into the new root's right tree. */ righttreemin->left = root; righttreemin = root; } else if (pindex > root->pindex) { if ((y = root->right) == NULL) break; if (pindex > y->pindex) { /* Rotate left. */ root->right = y->left; y->left = root; root = y; if ((y = root->right) == NULL) break; } /* Link into the new root's left tree. */ lefttreemax->right = root; lefttreemax = root; } else break; } /* Assemble the new root. */ lefttreemax->right = root->left; righttreemin->left = root->right; root->left = dummy.right; root->right = dummy.left; return (root); } /* * vm_page_insert: [ internal use only ] * * Inserts the given mem entry into the object and object list. * * The pagetables are not updated but will presumably fault the page * in if necessary, or if a kernel page the caller will at some point * enter the page into the kernel's pmap. We are not allowed to block * here so we *can't* do this anyway. * * The object and page must be locked. * This routine may not block. */ void vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) { vm_page_t root; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); if (m->object != NULL) panic("vm_page_insert: page already inserted"); /* * Record the object/offset pair in this page */ m->object = object; m->pindex = pindex; /* * Now link into the object's ordered list of backed pages. */ root = object->root; if (root == NULL) { m->left = NULL; m->right = NULL; TAILQ_INSERT_TAIL(&object->memq, m, listq); } else { root = vm_page_splay(pindex, root); if (pindex < root->pindex) { m->left = root->left; m->right = root; root->left = NULL; TAILQ_INSERT_BEFORE(root, m, listq); } else if (pindex == root->pindex) panic("vm_page_insert: offset already allocated"); else { m->right = root->right; m->left = root; root->right = NULL; TAILQ_INSERT_AFTER(&object->memq, root, m, listq); } } object->root = m; object->generation++; /* * show that the object has one more resident page. */ object->resident_page_count++; /* * Hold the vnode until the last page is released. */ if (object->resident_page_count == 1 && object->type == OBJT_VNODE) vhold((struct vnode *)object->handle); /* * Since we are inserting a new and possibly dirty page, * update the object's OBJ_MIGHTBEDIRTY flag. */ if (m->flags & PG_WRITEABLE) vm_object_set_writeable_dirty(object); } /* * vm_page_remove: * NOTE: used by device pager as well -wfj * * Removes the given mem entry from the object/offset-page * table and the object page list, but do not invalidate/terminate * the backing store. * * The object and page must be locked. * The underlying pmap entry (if any) is NOT removed here. * This routine may not block. */ void vm_page_remove(vm_page_t m) { vm_object_t object; vm_page_t root; if ((object = m->object) == NULL) return; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); if (m->oflags & VPO_BUSY) { m->oflags &= ~VPO_BUSY; vm_page_flash(m); } mtx_assert(&vm_page_queue_mtx, MA_OWNED); /* * Now remove from the object's list of backed pages. */ if (m != object->root) vm_page_splay(m->pindex, object->root); if (m->left == NULL) root = m->right; else { root = vm_page_splay(m->pindex, m->left); root->right = m->right; } object->root = root; TAILQ_REMOVE(&object->memq, m, listq); /* * And show that the object has one fewer resident page. */ object->resident_page_count--; object->generation++; /* * The vnode may now be recycled. */ if (object->resident_page_count == 0 && object->type == OBJT_VNODE) vdrop((struct vnode *)object->handle); m->object = NULL; } /* * vm_page_lookup: * * Returns the page associated with the object/offset * pair specified; if none is found, NULL is returned. * * The object must be locked. * This routine may not block. * This is a critical path routine */ vm_page_t vm_page_lookup(vm_object_t object, vm_pindex_t pindex) { vm_page_t m; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); if ((m = object->root) != NULL && m->pindex != pindex) { m = vm_page_splay(pindex, m); if ((object->root = m)->pindex != pindex) m = NULL; } return (m); } /* * vm_page_rename: * * Move the given memory entry from its * current object to the specified target object/offset. * * The object must be locked. * This routine may not block. * * Note: swap associated with the page must be invalidated by the move. We * have to do this for several reasons: (1) we aren't freeing the * page, (2) we are dirtying the page, (3) the VM system is probably * moving the page from object A to B, and will then later move * the backing store from A to B and we can't have a conflict. * * Note: we *always* dirty the page. It is necessary both for the * fact that we moved it, and because we may be invalidating * swap. If the page is on the cache, we have to deactivate it * or vm_page_dirty() will panic. Dirty pages are not allowed * on the cache. */ void vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) { vm_page_remove(m); vm_page_insert(m, new_object, new_pindex); vm_page_dirty(m); } /* * Convert all of the given object's cached pages that have a * pindex within the given range into free pages. If the value * zero is given for "end", then the range's upper bound is * infinity. If the given object is backed by a vnode and it * transitions from having one or more cached pages to none, the * vnode's hold count is reduced. */ void vm_page_cache_free(vm_object_t object, vm_pindex_t start, vm_pindex_t end) { vm_page_t m, m_next; boolean_t empty; mtx_lock(&vm_page_queue_free_mtx); if (__predict_false(object->cache == NULL)) { mtx_unlock(&vm_page_queue_free_mtx); return; } m = object->cache = vm_page_splay(start, object->cache); if (m->pindex < start) { if (m->right == NULL) m = NULL; else { m_next = vm_page_splay(start, m->right); m_next->left = m; m->right = NULL; m = object->cache = m_next; } } /* * At this point, "m" is either (1) a reference to the page * with the least pindex that is greater than or equal to * "start" or (2) NULL. */ for (; m != NULL && (m->pindex < end || end == 0); m = m_next) { /* * Find "m"'s successor and remove "m" from the * object's cache. */ if (m->right == NULL) { object->cache = m->left; m_next = NULL; } else { m_next = vm_page_splay(start, m->right); m_next->left = m->left; object->cache = m_next; } /* Convert "m" to a free page. */ m->object = NULL; m->valid = 0; /* Clear PG_CACHED and set PG_FREE. */ m->flags ^= PG_CACHED | PG_FREE; KASSERT((m->flags & (PG_CACHED | PG_FREE)) == PG_FREE, ("vm_page_cache_free: page %p has inconsistent flags", m)); cnt.v_cache_count--; cnt.v_free_count++; } empty = object->cache == NULL; mtx_unlock(&vm_page_queue_free_mtx); if (object->type == OBJT_VNODE && empty) vdrop(object->handle); } /* * Returns the cached page that is associated with the given * object and offset. If, however, none exists, returns NULL. * * The free page queue must be locked. */ static inline vm_page_t vm_page_cache_lookup(vm_object_t object, vm_pindex_t pindex) { vm_page_t m; mtx_assert(&vm_page_queue_free_mtx, MA_OWNED); if ((m = object->cache) != NULL && m->pindex != pindex) { m = vm_page_splay(pindex, m); if ((object->cache = m)->pindex != pindex) m = NULL; } return (m); } /* * Remove the given cached page from its containing object's * collection of cached pages. * * The free page queue must be locked. */ void vm_page_cache_remove(vm_page_t m) { vm_object_t object; vm_page_t root; mtx_assert(&vm_page_queue_free_mtx, MA_OWNED); KASSERT((m->flags & PG_CACHED) != 0, ("vm_page_cache_remove: page %p is not cached", m)); object = m->object; if (m != object->cache) { root = vm_page_splay(m->pindex, object->cache); KASSERT(root == m, ("vm_page_cache_remove: page %p is not cached in object %p", m, object)); } if (m->left == NULL) root = m->right; else if (m->right == NULL) root = m->left; else { root = vm_page_splay(m->pindex, m->left); root->right = m->right; } object->cache = root; m->object = NULL; cnt.v_cache_count--; } /* * Transfer all of the cached pages with offset greater than or * equal to 'offidxstart' from the original object's cache to the * new object's cache. However, any cached pages with offset * greater than or equal to the new object's size are kept in the * original object. Initially, the new object's cache must be * empty. Offset 'offidxstart' in the original object must * correspond to offset zero in the new object. * * The new object must be locked. */ void vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart, vm_object_t new_object) { vm_page_t m, m_next; /* * Insertion into an object's collection of cached pages * requires the object to be locked. In contrast, removal does * not. */ VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED); KASSERT(new_object->cache == NULL, ("vm_page_cache_transfer: object %p has cached pages", new_object)); mtx_lock(&vm_page_queue_free_mtx); if ((m = orig_object->cache) != NULL) { /* * Transfer all of the pages with offset greater than or * equal to 'offidxstart' from the original object's * cache to the new object's cache. */ m = vm_page_splay(offidxstart, m); if (m->pindex < offidxstart) { orig_object->cache = m; new_object->cache = m->right; m->right = NULL; } else { orig_object->cache = m->left; new_object->cache = m; m->left = NULL; } while ((m = new_object->cache) != NULL) { if ((m->pindex - offidxstart) >= new_object->size) { /* * Return all of the cached pages with * offset greater than or equal to the * new object's size to the original * object's cache. */ new_object->cache = m->left; m->left = orig_object->cache; orig_object->cache = m; break; } m_next = vm_page_splay(m->pindex, m->right); /* Update the page's object and offset. */ m->object = new_object; m->pindex -= offidxstart; if (m_next == NULL) break; m->right = NULL; m_next->left = m; new_object->cache = m_next; } KASSERT(new_object->cache == NULL || new_object->type == OBJT_SWAP, ("vm_page_cache_transfer: object %p's type is incompatible" " with cached pages", new_object)); } mtx_unlock(&vm_page_queue_free_mtx); } /* * vm_page_alloc: * * Allocate and return a memory cell associated * with this VM object/offset pair. * * page_req classes: * VM_ALLOC_NORMAL normal process request * VM_ALLOC_SYSTEM system *really* needs a page * VM_ALLOC_INTERRUPT interrupt time request * VM_ALLOC_ZERO zero page * VM_ALLOC_WIRED wire the allocated page * VM_ALLOC_NOOBJ page is not associated with a vm object * VM_ALLOC_NOBUSY do not set the page busy * VM_ALLOC_IFNOTCACHED return NULL, do not reactivate if the page * is cached * * This routine may not sleep. */ vm_page_t vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req) { struct vnode *vp = NULL; vm_object_t m_object; vm_page_t m; int flags, page_req; page_req = req & VM_ALLOC_CLASS_MASK; KASSERT(curthread->td_intr_nesting_level == 0 || page_req == VM_ALLOC_INTERRUPT, ("vm_page_alloc(NORMAL|SYSTEM) in interrupt context")); if ((req & VM_ALLOC_NOOBJ) == 0) { KASSERT(object != NULL, ("vm_page_alloc: NULL object.")); VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); } /* * The pager is allowed to eat deeper into the free page list. */ if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT)) { page_req = VM_ALLOC_SYSTEM; }; mtx_lock(&vm_page_queue_free_mtx); if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved || (page_req == VM_ALLOC_SYSTEM && cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) || (page_req == VM_ALLOC_INTERRUPT && cnt.v_free_count + cnt.v_cache_count > 0)) { /* * Allocate from the free queue if the number of free pages * exceeds the minimum for the request class. */ if (object != NULL && (m = vm_page_cache_lookup(object, pindex)) != NULL) { if ((req & VM_ALLOC_IFNOTCACHED) != 0) { mtx_unlock(&vm_page_queue_free_mtx); return (NULL); } if (vm_phys_unfree_page(m)) vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0); #if VM_NRESERVLEVEL > 0 else if (!vm_reserv_reactivate_page(m)) #else else #endif panic("vm_page_alloc: cache page %p is missing" " from the free queue", m); } else if ((req & VM_ALLOC_IFCACHED) != 0) { mtx_unlock(&vm_page_queue_free_mtx); return (NULL); #if VM_NRESERVLEVEL > 0 } else if (object == NULL || object->type == OBJT_DEVICE || object->type == OBJT_SG || (object->flags & OBJ_COLORED) == 0 || (m = vm_reserv_alloc_page(object, pindex)) == NULL) { #else } else { #endif m = vm_phys_alloc_pages(object != NULL ? VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0); #if VM_NRESERVLEVEL > 0 if (m == NULL && vm_reserv_reclaim_inactive()) { m = vm_phys_alloc_pages(object != NULL ? VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0); } #endif } } else { /* * Not allocatable, give up. */ mtx_unlock(&vm_page_queue_free_mtx); atomic_add_int(&vm_pageout_deficit, 1); pagedaemon_wakeup(); return (NULL); } /* * At this point we had better have found a good page. */ KASSERT(m != NULL, ("vm_page_alloc: missing page")); KASSERT(m->queue == PQ_NONE, ("vm_page_alloc: page %p has unexpected queue %d", m, m->queue)); KASSERT(m->wire_count == 0, ("vm_page_alloc: page %p is wired", m)); KASSERT(m->hold_count == 0, ("vm_page_alloc: page %p is held", m)); KASSERT(m->busy == 0, ("vm_page_alloc: page %p is busy", m)); KASSERT(m->dirty == 0, ("vm_page_alloc: page %p is dirty", m)); KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT, ("vm_page_alloc: page %p has unexpected memattr %d", m, pmap_page_get_memattr(m))); if ((m->flags & PG_CACHED) != 0) { KASSERT(m->valid != 0, ("vm_page_alloc: cached page %p is invalid", m)); if (m->object == object && m->pindex == pindex) cnt.v_reactivated++; else m->valid = 0; m_object = m->object; vm_page_cache_remove(m); if (m_object->type == OBJT_VNODE && m_object->cache == NULL) vp = m_object->handle; } else { KASSERT(VM_PAGE_IS_FREE(m), ("vm_page_alloc: page %p is not free", m)); KASSERT(m->valid == 0, ("vm_page_alloc: free page %p is valid", m)); cnt.v_free_count--; } /* * Initialize structure. Only the PG_ZERO flag is inherited. */ flags = 0; if (m->flags & PG_ZERO) { vm_page_zero_count--; if (req & VM_ALLOC_ZERO) flags = PG_ZERO; } if (object == NULL || object->type == OBJT_PHYS) flags |= PG_UNMANAGED; m->flags = flags; if (req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ)) m->oflags = 0; else m->oflags = VPO_BUSY; if (req & VM_ALLOC_WIRED) { atomic_add_int(&cnt.v_wire_count, 1); m->wire_count = 1; } m->act_count = 0; mtx_unlock(&vm_page_queue_free_mtx); if (object != NULL) { /* Ignore device objects; the pager sets "memattr" for them. */ if (object->memattr != VM_MEMATTR_DEFAULT && object->type != OBJT_DEVICE && object->type != OBJT_SG) pmap_page_set_memattr(m, object->memattr); vm_page_insert(m, object, pindex); } else m->pindex = pindex; /* * The following call to vdrop() must come after the above call * to vm_page_insert() in case both affect the same object and * vnode. Otherwise, the affected vnode's hold count could * temporarily become zero. */ if (vp != NULL) vdrop(vp); /* * Don't wakeup too often - wakeup the pageout daemon when * we would be nearly out of memory. */ if (vm_paging_needed()) pagedaemon_wakeup(); return (m); } /* * vm_wait: (also see VM_WAIT macro) * * Block until free pages are available for allocation * - Called in various places before memory allocations. */ void vm_wait(void) { mtx_lock(&vm_page_queue_free_mtx); if (curproc == pageproc) { vm_pageout_pages_needed = 1; msleep(&vm_pageout_pages_needed, &vm_page_queue_free_mtx, PDROP | PSWP, "VMWait", 0); } else { if (!vm_pages_needed) { vm_pages_needed = 1; wakeup(&vm_pages_needed); } msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PVM, "vmwait", 0); } } /* * vm_waitpfault: (also see VM_WAITPFAULT macro) * * Block until free pages are available for allocation * - Called only in vm_fault so that processes page faulting * can be easily tracked. * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing * processes will be able to grab memory first. Do not change * this balance without careful testing first. */ void vm_waitpfault(void) { mtx_lock(&vm_page_queue_free_mtx); if (!vm_pages_needed) { vm_pages_needed = 1; wakeup(&vm_pages_needed); } msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PUSER, "pfault", 0); } /* * vm_page_requeue: * * If the given page is contained within a page queue, move it to the tail * of that queue. * * The page queues must be locked. */ void vm_page_requeue(vm_page_t m) { int queue = VM_PAGE_GETQUEUE(m); struct vpgqueues *vpq; if (queue != PQ_NONE) { vpq = &vm_page_queues[queue]; TAILQ_REMOVE(&vpq->pl, m, pageq); TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); } } /* * vm_pageq_remove: * * Remove a page from its queue. * * The queue containing the given page must be locked. * This routine may not block. */ void vm_pageq_remove(vm_page_t m) { int queue = VM_PAGE_GETQUEUE(m); struct vpgqueues *pq; if (queue != PQ_NONE) { VM_PAGE_SETQUEUE2(m, PQ_NONE); pq = &vm_page_queues[queue]; TAILQ_REMOVE(&pq->pl, m, pageq); (*pq->cnt)--; } } /* * vm_page_enqueue: * * Add the given page to the specified queue. * * The page queues must be locked. */ static void vm_page_enqueue(int queue, vm_page_t m) { struct vpgqueues *vpq; vpq = &vm_page_queues[queue]; VM_PAGE_SETQUEUE2(m, queue); TAILQ_INSERT_TAIL(&vpq->pl, m, pageq); ++*vpq->cnt; } /* * vm_page_activate: * * Put the specified page on the active list (if appropriate). * Ensure that act_count is at least ACT_INIT but do not otherwise * mess with it. * * The page queues must be locked. * This routine may not block. */ void vm_page_activate(vm_page_t m) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (VM_PAGE_GETKNOWNQUEUE2(m) != PQ_ACTIVE) { vm_pageq_remove(m); if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { if (m->act_count < ACT_INIT) m->act_count = ACT_INIT; vm_page_enqueue(PQ_ACTIVE, m); } } else { if (m->act_count < ACT_INIT) m->act_count = ACT_INIT; } } /* * vm_page_free_wakeup: * * Helper routine for vm_page_free_toq() and vm_page_cache(). This * routine is called when a page has been added to the cache or free * queues. * * The page queues must be locked. * This routine may not block. */ static inline void vm_page_free_wakeup(void) { mtx_assert(&vm_page_queue_free_mtx, MA_OWNED); /* * if pageout daemon needs pages, then tell it that there are * some free. */ if (vm_pageout_pages_needed && cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) { wakeup(&vm_pageout_pages_needed); vm_pageout_pages_needed = 0; } /* * wakeup processes that are waiting on memory if we hit a * high water mark. And wakeup scheduler process if we have * lots of memory. this process will swapin processes. */ if (vm_pages_needed && !vm_page_count_min()) { vm_pages_needed = 0; wakeup(&cnt.v_free_count); } } /* * vm_page_free_toq: * * Returns the given page to the free list, * disassociating it with any VM object. * * Object and page must be locked prior to entry. * This routine may not block. */ void vm_page_free_toq(vm_page_t m) { if (VM_PAGE_GETQUEUE(m) != PQ_NONE) mtx_assert(&vm_page_queue_mtx, MA_OWNED); KASSERT(!pmap_page_is_mapped(m), ("vm_page_free_toq: freeing mapped page %p", m)); PCPU_INC(cnt.v_tfree); if (m->busy || VM_PAGE_IS_FREE(m)) { printf( "vm_page_free: pindex(%lu), busy(%d), VPO_BUSY(%d), hold(%d)\n", (u_long)m->pindex, m->busy, (m->oflags & VPO_BUSY) ? 1 : 0, m->hold_count); if (VM_PAGE_IS_FREE(m)) panic("vm_page_free: freeing free page"); else panic("vm_page_free: freeing busy page"); } /* * unqueue, then remove page. Note that we cannot destroy * the page here because we do not want to call the pager's * callback routine until after we've put the page on the * appropriate free queue. */ vm_pageq_remove(m); vm_page_remove(m); /* * If fictitious remove object association and * return, otherwise delay object association removal. */ if ((m->flags & PG_FICTITIOUS) != 0) { return; } m->valid = 0; vm_page_undirty(m); if (m->wire_count != 0) { if (m->wire_count > 1) { panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx", m->wire_count, (long)m->pindex); } panic("vm_page_free: freeing wired page"); } if (m->hold_count != 0) { vm_page_lock_assert(m, MA_OWNED); m->flags &= ~PG_ZERO; vm_page_enqueue(PQ_HOLD, m); } else { /* * Restore the default memory attribute to the page. */ if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT) pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT); /* * Insert the page into the physical memory allocator's * cache/free page queues. */ mtx_lock(&vm_page_queue_free_mtx); m->flags |= PG_FREE; cnt.v_free_count++; #if VM_NRESERVLEVEL > 0 if (!vm_reserv_free_page(m)) #else if (TRUE) #endif vm_phys_free_pages(m, 0); if ((m->flags & PG_ZERO) != 0) ++vm_page_zero_count; else vm_page_zero_idle_wakeup(); vm_page_free_wakeup(); mtx_unlock(&vm_page_queue_free_mtx); } } /* * vm_page_wire: * * Mark this page as wired down by yet * another map, removing it from paging queues * as necessary. * * The page queues must be locked. * This routine may not block. */ void vm_page_wire(vm_page_t m) { /* * Only bump the wire statistics if the page is not already wired, * and only unqueue the page if it is on some queue (if it is unmanaged * it is already off the queues). */ mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (m->flags & PG_FICTITIOUS) return; if (m->wire_count == 0) { if ((m->flags & PG_UNMANAGED) == 0) vm_pageq_remove(m); atomic_add_int(&cnt.v_wire_count, 1); } m->wire_count++; KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m)); } /* * vm_page_unwire: * * Release one wiring of this page, potentially * enabling it to be paged again. * * Many pages placed on the inactive queue should actually go * into the cache, but it is difficult to figure out which. What * we do instead, if the inactive target is well met, is to put * clean pages at the head of the inactive queue instead of the tail. * This will cause them to be moved to the cache more quickly and * if not actively re-referenced, freed more quickly. If we just * stick these pages at the end of the inactive queue, heavy filesystem * meta-data accesses can cause an unnecessary paging load on memory bound * processes. This optimization causes one-time-use metadata to be * reused more quickly. * * BUT, if we are in a low-memory situation we have no choice but to * put clean pages on the cache queue. * * A number of routines use vm_page_unwire() to guarantee that the page * will go into either the inactive or active queues, and will NEVER * be placed in the cache - for example, just after dirtying a page. * dirty pages in the cache are not allowed. * * The page queues must be locked. * This routine may not block. */ void vm_page_unwire(vm_page_t m, int activate) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (m->flags & PG_FICTITIOUS) return; if (m->wire_count > 0) { m->wire_count--; if (m->wire_count == 0) { atomic_subtract_int(&cnt.v_wire_count, 1); if (m->flags & PG_UNMANAGED) { ; } else if (activate) vm_page_enqueue(PQ_ACTIVE, m); else { vm_page_flag_clear(m, PG_WINATCFLS); vm_page_enqueue(PQ_INACTIVE, m); } } } else { panic("vm_page_unwire: invalid wire count: %d", m->wire_count); } } /* * Move the specified page to the inactive queue. If the page has * any associated swap, the swap is deallocated. * * Normally athead is 0 resulting in LRU operation. athead is set * to 1 if we want this page to be 'as if it were placed in the cache', * except without unmapping it from the process address space. * * This routine may not block. */ static inline void _vm_page_deactivate(vm_page_t m, int athead) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); /* * Ignore if already inactive. */ if (VM_PAGE_INQUEUE2(m, PQ_INACTIVE)) return; if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) { vm_page_flag_clear(m, PG_WINATCFLS); vm_pageq_remove(m); if (athead) TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); else TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq); VM_PAGE_SETQUEUE2(m, PQ_INACTIVE); cnt.v_inactive_count++; } } void vm_page_deactivate(vm_page_t m) { _vm_page_deactivate(m, 0); } /* * vm_page_try_to_cache: * * Returns 0 on failure, 1 on success */ int vm_page_try_to_cache(vm_page_t m) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); vm_page_lock_assert(m, MA_OWNED); VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (m->dirty || m->hold_count || m->busy || m->wire_count || (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) { return (0); } pmap_remove_all(m); if (m->dirty) return (0); vm_page_cache(m); return (1); } /* * vm_page_try_to_free() * * Attempt to free the page. If we cannot free it, we do nothing. * 1 is returned on success, 0 on failure. */ int vm_page_try_to_free(vm_page_t m) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); vm_page_lock_assert(m, MA_OWNED); if (m->object != NULL) VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (m->dirty || m->hold_count || m->busy || m->wire_count || (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) { return (0); } pmap_remove_all(m); if (m->dirty) return (0); vm_page_free(m); return (1); } /* * vm_page_cache * * Put the specified page onto the page cache queue (if appropriate). * * This routine may not block. */ void vm_page_cache(vm_page_t m) { vm_object_t object; vm_page_t root; mtx_assert(&vm_page_queue_mtx, MA_OWNED); vm_page_lock_assert(m, MA_OWNED); object = m->object; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); if ((m->flags & PG_UNMANAGED) || (m->oflags & VPO_BUSY) || m->busy || m->hold_count || m->wire_count) { panic("vm_page_cache: attempting to cache busy page"); } pmap_remove_all(m); if (m->dirty != 0) panic("vm_page_cache: page %p is dirty", m); if (m->valid == 0 || object->type == OBJT_DEFAULT || (object->type == OBJT_SWAP && !vm_pager_has_page(object, m->pindex, NULL, NULL))) { /* * Hypothesis: A cache-elgible page belonging to a * default object or swap object but without a backing * store must be zero filled. */ vm_page_free(m); return; } KASSERT((m->flags & PG_CACHED) == 0, ("vm_page_cache: page %p is already cached", m)); cnt.v_tcached++; /* * Remove the page from the paging queues. */ vm_pageq_remove(m); /* * Remove the page from the object's collection of resident * pages. */ if (m != object->root) vm_page_splay(m->pindex, object->root); if (m->left == NULL) root = m->right; else { root = vm_page_splay(m->pindex, m->left); root->right = m->right; } object->root = root; TAILQ_REMOVE(&object->memq, m, listq); object->resident_page_count--; object->generation++; /* * Restore the default memory attribute to the page. */ if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT) pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT); /* * Insert the page into the object's collection of cached pages * and the physical memory allocator's cache/free page queues. */ vm_page_flag_clear(m, PG_ZERO); mtx_lock(&vm_page_queue_free_mtx); m->flags |= PG_CACHED; cnt.v_cache_count++; root = object->cache; if (root == NULL) { m->left = NULL; m->right = NULL; } else { root = vm_page_splay(m->pindex, root); if (m->pindex < root->pindex) { m->left = root->left; m->right = root; root->left = NULL; } else if (__predict_false(m->pindex == root->pindex)) panic("vm_page_cache: offset already cached"); else { m->right = root->right; m->left = root; root->right = NULL; } } object->cache = m; #if VM_NRESERVLEVEL > 0 if (!vm_reserv_free_page(m)) { #else if (TRUE) { #endif vm_phys_set_pool(VM_FREEPOOL_CACHE, m, 0); vm_phys_free_pages(m, 0); } vm_page_free_wakeup(); mtx_unlock(&vm_page_queue_free_mtx); /* * Increment the vnode's hold count if this is the object's only * cached page. Decrement the vnode's hold count if this was * the object's only resident page. */ if (object->type == OBJT_VNODE) { if (root == NULL && object->resident_page_count != 0) vhold(object->handle); else if (root != NULL && object->resident_page_count == 0) vdrop(object->handle); } } /* * vm_page_dontneed * * Cache, deactivate, or do nothing as appropriate. This routine * is typically used by madvise() MADV_DONTNEED. * * Generally speaking we want to move the page into the cache so * it gets reused quickly. However, this can result in a silly syndrome * due to the page recycling too quickly. Small objects will not be * fully cached. On the otherhand, if we move the page to the inactive * queue we wind up with a problem whereby very large objects * unnecessarily blow away our inactive and cache queues. * * The solution is to move the pages based on a fixed weighting. We * either leave them alone, deactivate them, or move them to the cache, * where moving them to the cache has the highest weighting. * By forcing some pages into other queues we eventually force the * system to balance the queues, potentially recovering other unrelated * space from active. The idea is to not force this to happen too * often. */ void vm_page_dontneed(vm_page_t m) { static int dnweight; int dnw; int head; mtx_assert(&vm_page_queue_mtx, MA_OWNED); dnw = ++dnweight; /* * occassionally leave the page alone */ if ((dnw & 0x01F0) == 0 || VM_PAGE_INQUEUE2(m, PQ_INACTIVE)) { if (m->act_count >= ACT_INIT) --m->act_count; return; } /* * Clear any references to the page. Otherwise, the page daemon will * immediately reactivate the page. */ vm_page_flag_clear(m, PG_REFERENCED); pmap_clear_reference(m); if (m->dirty == 0 && pmap_is_modified(m)) vm_page_dirty(m); if (m->dirty || (dnw & 0x0070) == 0) { /* * Deactivate the page 3 times out of 32. */ head = 0; } else { /* * Cache the page 28 times out of every 32. Note that * the page is deactivated instead of cached, but placed * at the head of the queue instead of the tail. */ head = 1; } _vm_page_deactivate(m, head); } /* * Grab a page, waiting until we are waken up due to the page * changing state. We keep on waiting, if the page continues * to be in the object. If the page doesn't exist, first allocate it * and then conditionally zero it. * * This routine may block. */ vm_page_t vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) { vm_page_t m; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); retrylookup: if ((m = vm_page_lookup(object, pindex)) != NULL) { if ((m->oflags & VPO_BUSY) != 0 || m->busy != 0) { if ((allocflags & VM_ALLOC_RETRY) != 0) { /* * Reference the page before unlocking and * sleeping so that the page daemon is less * likely to reclaim it. */ vm_page_lock_queues(); vm_page_flag_set(m, PG_REFERENCED); } vm_page_sleep(m, "pgrbwt"); if ((allocflags & VM_ALLOC_RETRY) == 0) return (NULL); goto retrylookup; } else { if ((allocflags & VM_ALLOC_WIRED) != 0) { vm_page_lock_queues(); vm_page_wire(m); vm_page_unlock_queues(); } if ((allocflags & VM_ALLOC_NOBUSY) == 0) vm_page_busy(m); return (m); } } m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY); if (m == NULL) { VM_OBJECT_UNLOCK(object); VM_WAIT; VM_OBJECT_LOCK(object); if ((allocflags & VM_ALLOC_RETRY) == 0) return (NULL); goto retrylookup; } else if (m->valid != 0) return (m); if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0) pmap_zero_page(m); return (m); } /* * Mapping function for valid bits or for dirty bits in * a page. May not block. * * Inputs are required to range within a page. */ int vm_page_bits(int base, int size) { int first_bit; int last_bit; KASSERT( base + size <= PAGE_SIZE, ("vm_page_bits: illegal base/size %d/%d", base, size) ); if (size == 0) /* handle degenerate case */ return (0); first_bit = base >> DEV_BSHIFT; last_bit = (base + size - 1) >> DEV_BSHIFT; return ((2 << last_bit) - (1 << first_bit)); } /* * vm_page_set_valid: * * Sets portions of a page valid. The arguments are expected * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive * of any partial chunks touched by the range. The invalid portion of * such chunks will be zeroed. * * (base + size) must be less then or equal to PAGE_SIZE. */ void vm_page_set_valid(vm_page_t m, int base, int size) { int endoff, frag; VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (size == 0) /* handle degenerate case */ return; /* * If the base is not DEV_BSIZE aligned and the valid * bit is clear, we have to zero out a portion of the * first block. */ if ((frag = base & ~(DEV_BSIZE - 1)) != base && (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) pmap_zero_page_area(m, frag, base - frag); /* * If the ending offset is not DEV_BSIZE aligned and the * valid bit is clear, we have to zero out a portion of * the last block. */ endoff = base + size; if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) pmap_zero_page_area(m, endoff, DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); /* * Assert that no previously invalid block that is now being validated * is already dirty. */ KASSERT((~m->valid & vm_page_bits(base, size) & m->dirty) == 0, ("vm_page_set_valid: page %p is dirty", m)); /* * Set valid bits inclusive of any overlap. */ m->valid |= vm_page_bits(base, size); } /* * vm_page_set_validclean: * * Sets portions of a page valid and clean. The arguments are expected * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive * of any partial chunks touched by the range. The invalid portion of * such chunks will be zero'd. * * This routine may not block. * * (base + size) must be less then or equal to PAGE_SIZE. */ void vm_page_set_validclean(vm_page_t m, int base, int size) { int pagebits; int frag; int endoff; mtx_assert(&vm_page_queue_mtx, MA_OWNED); VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (size == 0) /* handle degenerate case */ return; /* * If the base is not DEV_BSIZE aligned and the valid * bit is clear, we have to zero out a portion of the * first block. */ if ((frag = base & ~(DEV_BSIZE - 1)) != base && (m->valid & (1 << (base >> DEV_BSHIFT))) == 0) pmap_zero_page_area(m, frag, base - frag); /* * If the ending offset is not DEV_BSIZE aligned and the * valid bit is clear, we have to zero out a portion of * the last block. */ endoff = base + size; if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff && (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0) pmap_zero_page_area(m, endoff, DEV_BSIZE - (endoff & (DEV_BSIZE - 1))); /* * Set valid, clear dirty bits. If validating the entire * page we can safely clear the pmap modify bit. We also * use this opportunity to clear the VPO_NOSYNC flag. If a process * takes a write fault on a MAP_NOSYNC memory area the flag will * be set again. * * We set valid bits inclusive of any overlap, but we can only * clear dirty bits for DEV_BSIZE chunks that are fully within * the range. */ pagebits = vm_page_bits(base, size); m->valid |= pagebits; #if 0 /* NOT YET */ if ((frag = base & (DEV_BSIZE - 1)) != 0) { frag = DEV_BSIZE - frag; base += frag; size -= frag; if (size < 0) size = 0; } pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1)); #endif m->dirty &= ~pagebits; if (base == 0 && size == PAGE_SIZE) { pmap_clear_modify(m); m->oflags &= ~VPO_NOSYNC; } } void vm_page_clear_dirty(vm_page_t m, int base, int size) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); m->dirty &= ~vm_page_bits(base, size); } /* * vm_page_set_invalid: * * Invalidates DEV_BSIZE'd chunks within a page. Both the * valid and dirty bits for the effected areas are cleared. * * May not block. */ void vm_page_set_invalid(vm_page_t m, int base, int size) { int bits; VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); bits = vm_page_bits(base, size); mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (m->valid == VM_PAGE_BITS_ALL && bits != 0) pmap_remove_all(m); m->valid &= ~bits; m->dirty &= ~bits; m->object->generation++; } /* * vm_page_zero_invalid() * * The kernel assumes that the invalid portions of a page contain * garbage, but such pages can be mapped into memory by user code. * When this occurs, we must zero out the non-valid portions of the * page so user code sees what it expects. * * Pages are most often semi-valid when the end of a file is mapped * into memory and the file's size is not page aligned. */ void vm_page_zero_invalid(vm_page_t m, boolean_t setvalid) { int b; int i; VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); /* * Scan the valid bits looking for invalid sections that * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the * valid bit may be set ) have already been zerod by * vm_page_set_validclean(). */ for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) { if (i == (PAGE_SIZE / DEV_BSIZE) || (m->valid & (1 << i)) ) { if (i > b) { pmap_zero_page_area(m, b << DEV_BSHIFT, (i - b) << DEV_BSHIFT); } b = i + 1; } } /* * setvalid is TRUE when we can safely set the zero'd areas * as being valid. We can do this if there are no cache consistancy * issues. e.g. it is ok to do with UFS, but not ok to do with NFS. */ if (setvalid) m->valid = VM_PAGE_BITS_ALL; } /* * vm_page_is_valid: * * Is (partial) page valid? Note that the case where size == 0 * will return FALSE in the degenerate case where the page is * entirely invalid, and TRUE otherwise. * * May not block. */ int vm_page_is_valid(vm_page_t m, int base, int size) { int bits = vm_page_bits(base, size); VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); if (m->valid && ((m->valid & bits) == bits)) return 1; else return 0; } /* * update dirty bits from pmap/mmu. May not block. */ void vm_page_test_dirty(vm_page_t m) { if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) { vm_page_dirty(m); } } int so_zerocp_fullpage = 0; /* * Replace the given page with a copy. The copied page assumes * the portion of the given page's "wire_count" that is not the * responsibility of this copy-on-write mechanism. * * The object containing the given page must have a non-zero * paging-in-progress count and be locked. */ void vm_page_cowfault(vm_page_t m) { vm_page_t mnew; vm_object_t object; vm_pindex_t pindex; object = m->object; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); KASSERT(object->paging_in_progress != 0, ("vm_page_cowfault: object %p's paging-in-progress count is zero.", object)); pindex = m->pindex; retry_alloc: pmap_remove_all(m); vm_page_remove(m); mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); if (mnew == NULL) { vm_page_insert(m, object, pindex); vm_page_unlock_queues(); VM_OBJECT_UNLOCK(object); VM_WAIT; VM_OBJECT_LOCK(object); if (m == vm_page_lookup(object, pindex)) { vm_page_lock_queues(); goto retry_alloc; } else { /* * Page disappeared during the wait. */ vm_page_lock_queues(); return; } } if (m->cow == 0) { /* * check to see if we raced with an xmit complete when * waiting to allocate a page. If so, put things back * the way they were */ vm_page_free(mnew); vm_page_insert(m, object, pindex); } else { /* clear COW & copy page */ if (!so_zerocp_fullpage) pmap_copy_page(m, mnew); mnew->valid = VM_PAGE_BITS_ALL; vm_page_dirty(mnew); mnew->wire_count = m->wire_count - m->cow; m->wire_count = m->cow; } } void vm_page_cowclear(vm_page_t m) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (m->cow) { m->cow--; /* * let vm_fault add back write permission lazily */ } /* * sf_buf_free() will free the page, so we needn't do it here */ } int vm_page_cowsetup(vm_page_t m) { mtx_assert(&vm_page_queue_mtx, MA_OWNED); if (m->cow == USHRT_MAX - 1) return (EBUSY); m->cow++; pmap_remove_write(m); return (0); } #include "opt_ddb.h" #ifdef DDB #include #include DB_SHOW_COMMAND(page, vm_page_print_page_info) { db_printf("cnt.v_free_count: %d\n", cnt.v_free_count); db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count); db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count); db_printf("cnt.v_active_count: %d\n", cnt.v_active_count); db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count); db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved); db_printf("cnt.v_free_min: %d\n", cnt.v_free_min); db_printf("cnt.v_free_target: %d\n", cnt.v_free_target); db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min); db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target); } DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info) { db_printf("PQ_FREE:"); db_printf(" %d", cnt.v_free_count); db_printf("\n"); db_printf("PQ_CACHE:"); db_printf(" %d", cnt.v_cache_count); db_printf("\n"); db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n", *vm_page_queues[PQ_ACTIVE].cnt, *vm_page_queues[PQ_INACTIVE].cnt); } #endif /* DDB */