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diff --git a/sys/vm/vm_reserv.h b/sys/vm/vm_reserv.h
--- a/sys/vm/vm_reserv.h
+++ b/sys/vm/vm_reserv.h
@@ -51,6 +51,9 @@
vm_paddr_t boundary);
vm_page_t vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex,
int domain, int req, vm_page_t mpred);
+int vm_reserv_alloc_npages(vm_object_t object, vm_pindex_t pindex,
+ int domain, vm_page_t mpred, int req, vm_page_t *ma,
+ u_long npages);
void vm_reserv_break_all(vm_object_t object);
boolean_t vm_reserv_free_page(vm_page_t m);
void vm_reserv_init(void);
diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c
--- a/sys/vm/vm_reserv.c
+++ b/sys/vm/vm_reserv.c
@@ -806,6 +806,133 @@
return (m_ret);
}
+/*
+ * Allocates "npages" physical pages from an existing or newly created
+ * reservation, starting from the offset "pindex". The allocated pages may
+ * not be physically contiguous.
+ *
+ * The page "mpred" must immediately precede the offset "pindex" within the
+ * specified object.
+ *
+ * The object must be locked.
+ */
+int
+vm_reserv_alloc_npages(vm_object_t object, vm_pindex_t pindex, int domain,
+ vm_page_t mpred, int req, vm_page_t *ma, u_long npages)
+{
+ struct vm_domain *vmd;
+ vm_page_t m, msucc;
+ vm_pindex_t first, leftcap, rightcap;
+ vm_reserv_t rv;
+ int index, got;
+
+ VM_OBJECT_ASSERT_WLOCKED(object);
+ KASSERT(npages != 0, ("%s: npages is 0", __func__));
+ vmd = VM_DOMAIN(domain);
+
+ /*
+ * Is a reservation fundamentally impossible?
+ */
+ if (pindex < VM_RESERV_INDEX(object, pindex) || pindex >= object->size)
+ return (0);
+ /*
+ * Look for an existing reservation.
+ */
+ npages = min(VM_LEVEL_0_NPAGES, npages);
+ rv = vm_reserv_from_object(object, pindex, mpred, &msucc);
+ if (rv == NULL) {
+ /*
+ * Could a reservation fit between the first index to the left
+ * that can be used and the first index to the right that cannot
+ * be used?
+ *
+ * We must synchronize with the reserv object lock to protect
+ * the pindex/object of the resulting reservations against
+ * rename while we are inspecting.
+ */
+ first = pindex - VM_RESERV_INDEX(object, pindex);
+ vm_reserv_object_lock(object);
+ if (mpred != NULL) {
+ if ((rv = vm_reserv_from_page(mpred))->object != object)
+ leftcap = mpred->pindex + 1;
+ else
+ leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
+ if (leftcap > first) {
+ vm_reserv_object_unlock(object);
+ return (0);
+ }
+ }
+ if (msucc != NULL) {
+ if ((rv = vm_reserv_from_page(msucc))->object != object)
+ rightcap = msucc->pindex;
+ else
+ rightcap = rv->pindex;
+ if (first + VM_LEVEL_0_NPAGES > rightcap) {
+ vm_reserv_object_unlock(object);
+ return (0);
+ }
+ }
+ vm_reserv_object_unlock(object);
+
+ /*
+ * Would the last new reservation extend past the end of the
+ * object?
+ *
+ * If the object is unlikely to grow don't allocate a
+ * reservation for the tail.
+ */
+ if ((object->flags & OBJ_ANON) == 0 &&
+ first + VM_LEVEL_0_NPAGES > object->size)
+ return (0);
+
+ /*
+ * Allocate and populate the new reservation.
+ */
+ m = NULL;
+ if (vm_domain_allocate(vmd, req, npages)) {
+ vm_domain_free_lock(vmd);
+ m = vm_phys_alloc_pages(domain, VM_FREEPOOL_DEFAULT,
+ VM_LEVEL_0_ORDER);
+ vm_domain_free_unlock(vmd);
+ if (m == NULL) {
+ vm_domain_freecnt_inc(vmd, npages);
+ return (0);
+ }
+ } else
+ return (0);
+
+ rv = vm_reserv_from_page(m);
+ vm_reserv_lock(rv);
+ KASSERT(rv->pages == m,
+ ("vm_reserv_alloc_page: reserv %p's pages is corrupted",
+ rv));
+ vm_reserv_insert(rv, object, first);
+ } else {
+ if (!vm_domain_allocate(vmd, req, npages))
+ return (0);
+ vm_reserv_lock(rv);
+ }
+
+ KASSERT(object != kernel_object || rv->domain == domain,
+ ("vm_reserv_alloc_page: domain mismatch"));
+
+ index = VM_RESERV_INDEX(object, pindex);
+ got = 0;
+ for (; index < VM_LEVEL_0_NPAGES && got < npages; index++) {
+ if (bit_test(rv->popmap, index))
+ continue;
+ vm_reserv_populate(rv, index);
+ ma[got] = &rv->pages[index];
+ got++;
+ }
+ vm_reserv_unlock(rv);
+
+ if (got < npages)
+ vm_domain_freecnt_inc(vmd, npages - got);
+
+ return (got);
+}
+
/*
* Allocate a physical page from an existing or newly created reservation.
*

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