Add the superpage reservation system. This is "part 2 of 2" of the

machine-independent support for superpages.  (The earlier part was
the rewrite of the physical memory allocator.)  The remainder of the
code required for superpages support is machine-dependent and will
be added to the various pmap implementations at a later date.

Initially, I am only supporting one large page size per architecture.
Moreover, I am only enabling the reservation system on amd64.  (In
an emergency, it can be disabled by setting VM_NRESERVLEVELS to 0
in amd64/include/vmparam.h or your kernel configuration file.)

1 files changed, 668 insertions, 0 deletions

diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c
new file mode 100644
index 0000000..3d0690c
--- /dev/null
+++ b/sys/vm/vm_reserv.c
@@ -0,0 +1,668 @@
+/*-
+ * Copyright (c) 2002-2006 Rice University
+ * Copyright (c) 2007 Alan L. Cox <alc@cs.rice.edu>
+ * All rights reserved.
+ *
+ * This software was developed for the FreeBSD Project by Alan L. Cox,
+ * Olivier Crameri, Peter Druschel, Sitaram Iyer, and Juan Navarro.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * HOLDERS 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.
+ */
+
+/*
+ *	Superpage reservation management module
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_vm.h"
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
+#include <sys/sbuf.h>
+#include <sys/sysctl.h>
+#include <sys/systm.h>
+
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_phys.h>
+#include <vm/vm_reserv.h>
+
+/*
+ * The reservation system supports the speculative allocation of large physical
+ * pages ("superpages").  Speculative allocation enables the fully-automatic
+ * utilization of superpages by the virtual memory system.  In other words, no
+ * programmatic directives are required to use superpages.
+ */
+
+#if VM_NRESERVLEVEL > 0
+
+/*
+ * The number of small pages that are contained in a level 0 reservation
+ */
+#define	VM_LEVEL_0_NPAGES	(1 << VM_LEVEL_0_ORDER)
+
+/*
+ * The number of bits by which a physical address is shifted to obtain the
+ * reservation number
+ */
+#define	VM_LEVEL_0_SHIFT	(VM_LEVEL_0_ORDER + PAGE_SHIFT)
+
+/*
+ * The size of a level 0 reservation in bytes
+ */
+#define	VM_LEVEL_0_SIZE		(1 << VM_LEVEL_0_SHIFT)
+
+/*
+ * Computes the index of the small page underlying the given (object, pindex)
+ * within the reservation's array of small pages.
+ */
+#define	VM_RESERV_INDEX(object, pindex)	\
+    (((object)->pg_color + (pindex)) & (VM_LEVEL_0_NPAGES - 1))
+
+/*
+ * The reservation structure
+ *
+ * A reservation structure is constructed whenever a large physical page is
+ * speculatively allocated to an object.  The reservation provides the small
+ * physical pages for the range [pindex, pindex + VM_LEVEL_0_NPAGES) of offsets
+ * within that object.  The reservation's "popcnt" tracks the number of these
+ * small physical pages that are in use at any given time.  When and if the
+ * reservation is not fully utilized, it appears in the queue of partially-
+ * populated reservations.  The reservation always appears on the containing
+ * object's list of reservations.
+ *
+ * A partially-populated reservation can be broken and reclaimed at any time.
+ */
+struct vm_reserv {
+	TAILQ_ENTRY(vm_reserv) partpopq;
+	LIST_ENTRY(vm_reserv) objq;
+	vm_object_t	object;			/* containing object */
+	vm_pindex_t	pindex;			/* offset within object */
+	vm_page_t	pages;			/* first page of a superpage */
+	int		popcnt;			/* # of pages in use */
+	char		inpartpopq;
+};
+
+/*
+ * The reservation array
+ *
+ * This array is analoguous in function to vm_page_array.  It differs in the
+ * respect that it may contain a greater number of useful reservation
+ * structures than there are (physical) superpages.  These "invalid"
+ * reservation structures exist to trade-off space for time in the
+ * implementation of vm_reserv_from_page().  Invalid reservation structures are
+ * distinguishable from "valid" reservation structures by inspecting the
+ * reservation's "pages" field.  Invalid reservation structures have a NULL
+ * "pages" field.
+ *
+ * vm_reserv_from_page() maps a small (physical) page to an element of this
+ * array by computing a physical reservation number from the page's physical
+ * address.  The physical reservation number is used as the array index.
+ *
+ * An "active" reservation is a valid reservation structure that has a non-NULL
+ * "object" field and a non-zero "popcnt" field.  In other words, every active
+ * reservation belongs to a particular object.  Moreover, every active
+ * reservation has an entry in the containing object's list of reservations.  
+ */
+static vm_reserv_t vm_reserv_array;
+
+/*
+ * The partially-populated reservation queue
+ *
+ * This queue enables the fast recovery of an unused cached or free small page
+ * from a partially-populated reservation.  The head of this queue is either
+ * the least-recently-populated or most-recently-depopulated reservation.
+ *
+ * Access to this queue is synchronized by the free page queue lock.
+ */
+static TAILQ_HEAD(, vm_reserv) vm_rvq_partpop =
+			    TAILQ_HEAD_INITIALIZER(vm_rvq_partpop);
+
+static SYSCTL_NODE(_vm, OID_AUTO, reserv, CTLFLAG_RD, 0, "Reservation Info");
+
+static long vm_reserv_broken;
+SYSCTL_LONG(_vm_reserv, OID_AUTO, broken, CTLFLAG_RD,
+    &vm_reserv_broken, 0, "Cumulative number of broken reservations");
+
+static long vm_reserv_freed;
+SYSCTL_LONG(_vm_reserv, OID_AUTO, freed, CTLFLAG_RD,
+    &vm_reserv_freed, 0, "Cumulative number of freed reservations");
+
+static int sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS);
+
+SYSCTL_OID(_vm_reserv, OID_AUTO, partpopq, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0,
+    sysctl_vm_reserv_partpopq, "A", "Partially-populated reservation queues");
+
+static long vm_reserv_reclaimed;
+SYSCTL_LONG(_vm_reserv, OID_AUTO, reclaimed, CTLFLAG_RD,
+    &vm_reserv_reclaimed, 0, "Cumulative number of reclaimed reservations");
+
+static void		vm_reserv_depopulate(vm_reserv_t rv);
+static vm_reserv_t	vm_reserv_from_page(vm_page_t m);
+static boolean_t	vm_reserv_has_pindex(vm_reserv_t rv,
+			    vm_pindex_t pindex);
+static void		vm_reserv_populate(vm_reserv_t rv);
+
+/*
+ * Describes the current state of the partially-populated reservation queue.
+ */
+static int
+sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
+{
+	struct sbuf sbuf;
+	vm_reserv_t rv;
+	char *cbuf;
+	const int cbufsize = (VM_NRESERVLEVEL + 1) * 81;
+	int counter, error, level, unused_pages;
+
+	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
+	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	sbuf_printf(&sbuf, "\nLEVEL     SIZE  NUMBER\n\n");
+	for (level = -1; level <= VM_NRESERVLEVEL - 2; level++) {
+		counter = 0;
+		unused_pages = 0;
+		mtx_lock(&vm_page_queue_free_mtx);
+		TAILQ_FOREACH(rv, &vm_rvq_partpop/*[level]*/, partpopq) {
+			counter++;
+			unused_pages += VM_LEVEL_0_NPAGES - rv->popcnt;
+		}
+		mtx_unlock(&vm_page_queue_free_mtx);
+		sbuf_printf(&sbuf, "%5.5d: %6.6dK, %6.6d\n", level,
+		    unused_pages * (PAGE_SIZE / 1024), counter);
+	}
+	sbuf_finish(&sbuf);
+	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	sbuf_delete(&sbuf);
+	free(cbuf, M_TEMP);
+	return (error);
+}
+
+/*
+ * Reduces the given reservation's population count.  If the population count
+ * becomes zero, the reservation is destroyed.  Additionally, moves the
+ * reservation to the head of the partially-populated reservations queue if the
+ * population count is non-zero.
+ *
+ * The free page queue lock must be held.
+ */
+static void
+vm_reserv_depopulate(vm_reserv_t rv)
+{
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	KASSERT(rv->object != NULL,
+	    ("vm_reserv_depopulate: reserv %p is free", rv));
+	KASSERT(rv->popcnt > 0,
+	    ("vm_reserv_depopulate: reserv %p's popcnt is corrupted", rv));
+	if (rv->inpartpopq) {
+		TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
+		rv->inpartpopq = FALSE;
+	}
+	rv->popcnt--;
+	if (rv->popcnt == 0) {
+		LIST_REMOVE(rv, objq);
+		rv->object = NULL;
+		vm_phys_free_pages(rv->pages, VM_LEVEL_0_ORDER);
+		vm_reserv_freed++;
+	} else {
+		rv->inpartpopq = TRUE;
+		TAILQ_INSERT_HEAD(&vm_rvq_partpop, rv, partpopq);
+	}
+}
+
+/*
+ * Returns the reservation to which the given page might belong.
+ */
+static __inline vm_reserv_t
+vm_reserv_from_page(vm_page_t m)
+{
+
+	return (&vm_reserv_array[VM_PAGE_TO_PHYS(m) >> VM_LEVEL_0_SHIFT]);
+}
+
+/*
+ * Returns TRUE if the given reservation contains the given page index and
+ * FALSE otherwise.
+ */
+static __inline boolean_t
+vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
+{
+
+	return (((pindex - rv->pindex) & ~(VM_LEVEL_0_NPAGES - 1)) == 0);
+}
+
+/*
+ * Increases the given reservation's population count.  Moves the reservation
+ * to the tail of the partially-populated reservation queue.
+ *
+ * The free page queue must be locked.
+ */
+static void
+vm_reserv_populate(vm_reserv_t rv)
+{
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	KASSERT(rv->object != NULL,
+	    ("vm_reserv_populate: reserv %p is free", rv));
+	KASSERT(rv->popcnt < VM_LEVEL_0_NPAGES,
+	    ("vm_reserv_populate: reserv %p is already full", rv));
+	if (rv->inpartpopq) {
+		TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
+		rv->inpartpopq = FALSE;
+	}
+	rv->popcnt++;
+	if (rv->popcnt < VM_LEVEL_0_NPAGES) {
+		rv->inpartpopq = TRUE;
+		TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
+	}
+}
+
+/*
+ * Allocates a page from an existing or newly-created reservation.
+ *
+ * The object and free page queue must be locked.
+ */
+vm_page_t
+vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex)
+{
+	vm_page_t m, mpred, msucc;
+	vm_pindex_t first, leftcap, rightcap;
+	vm_reserv_t rv;
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+
+	/*
+	 * Is a reservation fundamentally not possible?
+	 */
+	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	if (pindex < VM_RESERV_INDEX(object, pindex) ||
+	    pindex >= object->size)
+		return (NULL);
+
+	/*
+	 * Look for an existing reservation.
+	 */
+	msucc = NULL;
+	mpred = object->root;
+	while (mpred != NULL) {
+		KASSERT(mpred->pindex != pindex,
+		    ("vm_reserv_alloc_page: pindex already allocated"));
+		rv = vm_reserv_from_page(mpred);
+		if (rv->object == object && vm_reserv_has_pindex(rv, pindex)) {
+			m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
+			/* Handle vm_page_rename(m, new_object, ...). */
+			if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
+				return (NULL);
+			vm_reserv_populate(rv);
+			return (m);
+		} else if (mpred->pindex < pindex) {
+			if (msucc != NULL ||
+			    (msucc = TAILQ_NEXT(mpred, listq)) == NULL)
+				break;
+			KASSERT(msucc->pindex != pindex,
+			    ("vm_reserv_alloc_page: pindex already allocated"));
+			rv = vm_reserv_from_page(msucc);
+			if (rv->object == object &&
+			    vm_reserv_has_pindex(rv, pindex)) {
+				m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
+				/* Handle vm_page_rename(m, new_object, ...). */
+				if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
+					return (NULL);
+				vm_reserv_populate(rv);
+				return (m);
+			} else if (pindex < msucc->pindex)
+				break;
+		} else if (msucc == NULL) {
+			msucc = mpred;
+			mpred = TAILQ_PREV(msucc, pglist, listq);
+			continue;
+		}
+		msucc = NULL;
+		mpred = object->root = vm_page_splay(pindex, object->root);
+	}
+
+	/*
+	 * Determine the first index to the left that can be used.
+	 */
+	if (mpred == NULL)
+		leftcap = 0;
+	else if ((rv = vm_reserv_from_page(mpred))->object != object)
+		leftcap = mpred->pindex + 1;
+	else
+		leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
+
+	/*
+	 * Determine the first index to the right that cannot be used.
+	 */
+	if (msucc == NULL)
+		rightcap = pindex + VM_LEVEL_0_NPAGES;
+	else if ((rv = vm_reserv_from_page(msucc))->object != object)
+		rightcap = msucc->pindex;
+	else
+		rightcap = rv->pindex;
+
+	/*
+	 * Determine if a reservation fits between the first index to
+	 * the left that can be used and the first index to the right
+	 * that cannot be used. 
+	 */
+	first = pindex - VM_RESERV_INDEX(object, pindex);
+	if (first < leftcap || first + VM_LEVEL_0_NPAGES > rightcap)
+		return (NULL);
+
+	/*
+	 * Would a new reservation extend past the end of the given object? 
+	 */
+	if (object->size < first + VM_LEVEL_0_NPAGES) {
+		/*
+		 * Don't allocate a new reservation if the object is a vnode or
+		 * backed by another object that is a vnode. 
+		 */
+		if (object->type == OBJT_VNODE ||
+		    (object->backing_object != NULL &&
+		    object->backing_object->type == OBJT_VNODE))
+			return (NULL);
+		/* Speculate that the object may grow. */
+	}
+
+	/*
+	 * Allocate a new reservation.
+	 */
+	m = vm_phys_alloc_pages(VM_FREEPOOL_DEFAULT, VM_LEVEL_0_ORDER);
+	if (m != NULL) {
+		rv = vm_reserv_from_page(m);
+		KASSERT(rv->pages == m,
+		    ("vm_reserv_alloc_page: reserv %p's pages is corrupted",
+		    rv));
+		KASSERT(rv->object == NULL,
+		    ("vm_reserv_alloc_page: reserv %p isn't free", rv));
+		LIST_INSERT_HEAD(&object->rvq, rv, objq);
+		rv->object = object;
+		rv->pindex = first;
+		KASSERT(rv->popcnt == 0,
+		    ("vm_reserv_alloc_page: reserv %p's popcnt is corrupted",
+		    rv));
+		KASSERT(!rv->inpartpopq,
+		    ("vm_reserv_alloc_page: reserv %p's inpartpopq is TRUE",
+		    rv));
+		vm_reserv_populate(rv);
+		m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
+	}
+	return (m);
+}
+
+/*
+ * Breaks all reservations belonging to the given object.
+ */
+void
+vm_reserv_break_all(vm_object_t object)
+{
+	vm_reserv_t rv;
+	int i;
+
+	mtx_lock(&vm_page_queue_free_mtx);
+	while ((rv = LIST_FIRST(&object->rvq)) != NULL) {
+		KASSERT(rv->object == object,
+		    ("vm_reserv_break_all: reserv %p is corrupted", rv));
+		if (rv->inpartpopq) {
+			TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
+			rv->inpartpopq = FALSE;
+		}
+		LIST_REMOVE(rv, objq);
+		rv->object = NULL;
+		for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
+			if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
+				vm_phys_free_pages(&rv->pages[i], 0);
+			else
+				rv->popcnt--;
+		}
+		KASSERT(rv->popcnt == 0,
+		    ("vm_reserv_break_all: reserv %p's popcnt is corrupted",
+		    rv));
+		vm_reserv_broken++;
+	}
+	mtx_unlock(&vm_page_queue_free_mtx);
+}
+
+/*
+ * Frees the given page if it belongs to a reservation.  Returns TRUE if the
+ * page is freed and FALSE otherwise.
+ *
+ * The free page queue lock must be held.
+ */
+boolean_t
+vm_reserv_free_page(vm_page_t m)
+{
+	vm_reserv_t rv;
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	rv = vm_reserv_from_page(m);
+	if (rv->object != NULL) {
+		vm_reserv_depopulate(rv);
+		return (TRUE);
+	}
+	return (FALSE);
+}
+
+/*
+ * Initializes the reservation management system.  Specifically, initializes
+ * the reservation array.
+ *
+ * Requires that vm_page_array and first_page are initialized!
+ */
+void
+vm_reserv_init(void)
+{
+	vm_paddr_t paddr;
+	int i;
+
+	/*
+	 * Initialize the reservation array.  Specifically, initialize the
+	 * "pages" field for every element that has an underlying superpage.
+	 */
+	for (i = 0; phys_avail[i + 1] != 0; i += 2) {
+		paddr = roundup2(phys_avail[i], VM_LEVEL_0_SIZE);
+		while (paddr + VM_LEVEL_0_SIZE <= phys_avail[i + 1]) {
+			vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT].pages =
+			    PHYS_TO_VM_PAGE(paddr);
+			paddr += VM_LEVEL_0_SIZE;
+		}
+	}
+}
+
+/*
+ * Returns a reservation level if the given page belongs to a fully-populated
+ * reservation and -1 otherwise.
+ */
+int
+vm_reserv_level_iffullpop(vm_page_t m)
+{
+	vm_reserv_t rv;
+
+	rv = vm_reserv_from_page(m);
+	return (rv->popcnt == VM_LEVEL_0_NPAGES ? 0 : -1);
+}
+
+/*
+ * Prepare for the reactivation of a cached page.
+ *
+ * First, suppose that the given page "m" was allocated individually, i.e., not
+ * as part of a reservation, and cached.  Then, suppose a reservation
+ * containing "m" is allocated by the same object.  Although "m" and the
+ * reservation belong to the same object, "m"'s pindex may not match the
+ * reservation's.
+ *
+ * The free page queue must be locked.
+ */
+boolean_t
+vm_reserv_reactivate_page(vm_page_t m)
+{
+	vm_reserv_t rv;
+	int i, m_index;
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	rv = vm_reserv_from_page(m);
+	if (rv->object == NULL)
+		return (FALSE);
+	KASSERT((m->flags & PG_CACHED) != 0,
+	    ("vm_reserv_uncache_page: page %p is not cached", m));
+	if (m->object == rv->object &&
+	    m->pindex - rv->pindex == VM_RESERV_INDEX(m->object, m->pindex))
+		vm_reserv_populate(rv);
+	else {
+		KASSERT(rv->inpartpopq,
+		    ("vm_reserv_uncache_page: reserv %p's inpartpopq is FALSE",
+		    rv));
+		TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
+		rv->inpartpopq = FALSE;
+		LIST_REMOVE(rv, objq);
+		rv->object = NULL;
+		/* Don't vm_phys_free_pages(m, 0). */
+		m_index = m - rv->pages;
+		for (i = 0; i < m_index; i++) {
+			if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
+				vm_phys_free_pages(&rv->pages[i], 0);
+			else
+				rv->popcnt--;
+		}
+		for (i++; i < VM_LEVEL_0_NPAGES; i++) {
+			if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
+				vm_phys_free_pages(&rv->pages[i], 0);
+			else
+				rv->popcnt--;
+		}
+		KASSERT(rv->popcnt == 0,
+		    ("vm_reserv_uncache_page: reserv %p's popcnt is corrupted",
+		    rv));
+		vm_reserv_broken++;
+	}
+	return (TRUE);
+}
+
+/*
+ * Breaks the reservation at the head of the partially-populated reservation
+ * queue, releasing its cached and free pages to the physical memory
+ * allocator.  Returns TRUE if a reservation is broken and FALSE otherwise.
+ *
+ * The free page queue lock must be held.
+ */
+boolean_t
+vm_reserv_reclaim(void)
+{
+	vm_reserv_t rv;
+	int i;
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	if ((rv = TAILQ_FIRST(&vm_rvq_partpop)) != NULL) {
+		KASSERT(rv->inpartpopq,
+		    ("vm_reserv_reclaim: reserv %p's inpartpopq is corrupted",
+		    rv));
+		TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
+		rv->inpartpopq = FALSE;
+		KASSERT(rv->object != NULL,
+		    ("vm_reserv_reclaim: reserv %p is free", rv));
+		LIST_REMOVE(rv, objq);
+		rv->object = NULL;
+		for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
+			if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
+				vm_phys_free_pages(&rv->pages[i], 0);
+			else
+				rv->popcnt--;
+		}
+		KASSERT(rv->popcnt == 0,
+		    ("vm_reserv_reclaim: reserv %p's popcnt is corrupted",
+		    rv));
+		vm_reserv_reclaimed++;
+		return (TRUE);
+	}
+	return (FALSE);
+}
+
+/*
+ * Transfers the reservation underlying the given page to a new object.
+ *
+ * The object must be locked.
+ */
+void
+vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
+    vm_pindex_t old_object_offset)
+{
+	vm_reserv_t rv;
+
+	VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
+	rv = vm_reserv_from_page(m);
+	if (rv->object == old_object) {
+		mtx_lock(&vm_page_queue_free_mtx);
+		if (rv->object == old_object) {
+			LIST_REMOVE(rv, objq);
+			LIST_INSERT_HEAD(&new_object->rvq, rv, objq);
+			rv->object = new_object;
+			rv->pindex -= old_object_offset;
+		}
+		mtx_unlock(&vm_page_queue_free_mtx);
+	}
+}
+
+/*
+ * Allocates the virtual and physical memory required by the reservation
+ * management system's data structures, in particular, the reservation array.
+ */
+vm_paddr_t
+vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
+{
+	vm_paddr_t new_end;
+	size_t size;
+
+	/*
+	 * Calculate the size (in bytes) of the reservation array.  Round up
+	 * from "high_water" because every small page is mapped to an element
+	 * in the reservation array based on its physical address.  Thus, the
+	 * number of elements in the reservation array can be greater than the
+	 * number of superpages. 
+	 */
+	size = howmany(high_water, VM_LEVEL_0_SIZE) * sizeof(struct vm_reserv);
+
+	/*
+	 * Allocate and map the physical memory for the reservation array.  The
+	 * next available virtual address is returned by reference.
+	 */
+	new_end = end - round_page(size);
+	vm_reserv_array = (void *)(uintptr_t)pmap_map(vaddr, new_end, end,
+	    VM_PROT_READ | VM_PROT_WRITE);
+	bzero(vm_reserv_array, size);
+
+	/*
+	 * Return the next available physical address.
+	 */
+	return (new_end);
+}
+
+#endif	/* VM_NRESERVLEVEL > 0 */