Merge from vmcontention.

21 files changed, 449 insertions, 428 deletions

diff --git a/sys/vm/default_pager.c b/sys/vm/default_pager.c
index 12dc823..a71a22a 100644
--- a/sys/vm/default_pager.c
+++ b/sys/vm/default_pager.c
@@ -45,7 +45,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/lock.h>
 #include <sys/proc.h>
 #include <sys/resourcevar.h>
-#include <sys/mutex.h>
+#include <sys/rwlock.h>
 
 #include <vm/vm.h>
 #include <vm/vm_object.h>
@@ -91,10 +91,10 @@ default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 	object = vm_object_allocate(OBJT_DEFAULT,
 	    OFF_TO_IDX(round_page(offset + size)));
 	if (cred != NULL) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		object->cred = cred;
 		object->charge = size;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	return (object);
 }
diff --git a/sys/vm/device_pager.c b/sys/vm/device_pager.c
index 809c32c..fd20664 100644
--- a/sys/vm/device_pager.c
+++ b/sys/vm/device_pager.c
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 #include <sys/mutex.h>
 #include <sys/mman.h>
+#include <sys/rwlock.h>
 #include <sys/sx.h>
 
 #include <vm/vm.h>
@@ -206,7 +207,7 @@ void
 cdev_pager_free_page(vm_object_t object, vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (object->type == OBJT_MGTDEVICE) {
 		KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("unmanaged %p", m));
 		pmap_remove_all(m);
@@ -221,7 +222,7 @@ static void
 dev_pager_free_page(vm_object_t object, vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT((object->type == OBJT_DEVICE &&
 	    (m->oflags & VPO_UNMANAGED) != 0),
 	    ("Managed device or page obj %p m %p", object, m));
@@ -235,13 +236,13 @@ dev_pager_dealloc(object)
 {
 	vm_page_t m;
 
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	object->un_pager.devp.ops->cdev_pg_dtor(object->un_pager.devp.dev);
 
 	mtx_lock(&dev_pager_mtx);
 	TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
 	mtx_unlock(&dev_pager_mtx);
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 
 	if (object->type == OBJT_DEVICE) {
 		/*
@@ -258,11 +259,11 @@ dev_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int reqpage)
 {
 	int error, i;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	error = object->un_pager.devp.ops->cdev_pg_fault(object,
 	    IDX_TO_OFF(ma[reqpage]->pindex), PROT_READ, &ma[reqpage]);
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	for (i = 0; i < count; i++) {
 		if (i != reqpage) {
@@ -304,12 +305,12 @@ old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
 	pidx = OFF_TO_IDX(offset);
 	memattr = object->memattr;
 
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	dev = object->handle;
 	csw = dev_refthread(dev, &ref);
 	if (csw == NULL) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		return (VM_PAGER_FAIL);
 	}
 	td = curthread;
@@ -321,7 +322,7 @@ old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
 	if (ret != 0) {
 		printf(
 	    "WARNING: dev_pager_getpage: map function returns error %d", ret);
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		return (VM_PAGER_FAIL);
 	}
 
@@ -338,7 +339,7 @@ old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
 		 * the new physical address.
 		 */
 		page = *mres;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		vm_page_updatefake(page, paddr, memattr);
 	} else {
 		/*
@@ -346,7 +347,7 @@ old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
 		 * free up the all of the original pages.
 		 */
 		page = vm_page_getfake(paddr, memattr);
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		vm_page_lock(*mres);
 		vm_page_free(*mres);
 		vm_page_unlock(*mres);
diff --git a/sys/vm/phys_pager.c b/sys/vm/phys_pager.c
index 0ffafea..7b9f7b2 100644
--- a/sys/vm/phys_pager.c
+++ b/sys/vm/phys_pager.c
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 #include <sys/mutex.h>
 #include <sys/mman.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 
 #include <vm/vm.h>
@@ -123,11 +124,11 @@ phys_pager_dealloc(vm_object_t object)
 {
 
 	if (object->handle != NULL) {
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		mtx_lock(&phys_pager_mtx);
 		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 		mtx_unlock(&phys_pager_mtx);
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 	}
 }
 
@@ -139,7 +140,7 @@ phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 {
 	int i;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	for (i = 0; i < count; i++) {
 		if (m[i]->valid == 0) {
 			if ((m[i]->flags & PG_ZERO) == 0)
diff --git a/sys/vm/sg_pager.c b/sys/vm/sg_pager.c
index 097039e..76cae68 100644
--- a/sys/vm/sg_pager.c
+++ b/sys/vm/sg_pager.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/rwlock.h>
 #include <sys/sglist.h>
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -142,10 +143,10 @@ sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	size_t space;
 	int i;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	sg = object->handle;
 	memattr = object->memattr;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	offset = m[reqpage]->pindex;
 
 	/*
@@ -180,7 +181,7 @@ sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 
 	/* Construct a new fake page. */
 	page = vm_page_getfake(paddr, memattr);
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, pageq);
 
 	/* Free the original pages and insert this fake page into the object. */
diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index 712fd83..2049996 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -89,6 +89,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/racct.h>
 #include <sys/resource.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 #include <sys/sysproto.h>
 #include <sys/blist.h>
@@ -621,14 +622,14 @@ swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 				crhold(cred);
 			}
 			object = vm_object_allocate(OBJT_DEFAULT, pindex);
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			object->handle = handle;
 			if (cred != NULL) {
 				object->cred = cred;
 				object->charge = size;
 			}
 			swp_pager_meta_build(object, 0, SWAPBLK_NONE);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		}
 		sx_xunlock(&sw_alloc_sx);
 		mtx_unlock(&Giant);
@@ -639,13 +640,13 @@ swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 			crhold(cred);
 		}
 		object = vm_object_allocate(OBJT_DEFAULT, pindex);
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (cred != NULL) {
 			object->cred = cred;
 			object->charge = size;
 		}
 		swp_pager_meta_build(object, 0, SWAPBLK_NONE);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	return (object);
 }
@@ -674,7 +675,7 @@ swap_pager_dealloc(vm_object_t object)
 		mtx_unlock(&sw_alloc_mtx);
 	}
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	vm_object_pip_wait(object, "swpdea");
 
 	/*
@@ -815,7 +816,7 @@ void
 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	swp_pager_meta_free(object, start, size);
 }
 
@@ -834,7 +835,7 @@ swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
 	daddr_t blk = SWAPBLK_NONE;
 	vm_pindex_t beg = start;	/* save start index */
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	while (size) {
 		if (n == 0) {
 			n = BLIST_MAX_ALLOC;
@@ -842,7 +843,7 @@ swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
 				n >>= 1;
 				if (n == 0) {
 					swp_pager_meta_free(object, beg, start - beg);
-					VM_OBJECT_UNLOCK(object);
+					VM_OBJECT_WUNLOCK(object);
 					return (-1);
 				}
 			}
@@ -854,7 +855,7 @@ swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
 		--n;
 	}
 	swp_pager_meta_free(object, start, n);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	return (0);
 }
 
@@ -883,8 +884,8 @@ swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
 {
 	vm_pindex_t i;
 
-	VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(srcobject);
+	VM_OBJECT_ASSERT_WLOCKED(dstobject);
 
 	/*
 	 * If destroysource is set, we remove the source object from the
@@ -934,11 +935,11 @@ swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
 				 * swp_pager_meta_build() can sleep.
 				 */
 				vm_object_pip_add(srcobject, 1);
-				VM_OBJECT_UNLOCK(srcobject);
+				VM_OBJECT_WUNLOCK(srcobject);
 				vm_object_pip_add(dstobject, 1);
 				swp_pager_meta_build(dstobject, i, srcaddr);
 				vm_object_pip_wakeup(dstobject);
-				VM_OBJECT_LOCK(srcobject);
+				VM_OBJECT_WLOCK(srcobject);
 				vm_object_pip_wakeup(srcobject);
 			}
 		} else {
@@ -987,7 +988,7 @@ swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *aft
 {
 	daddr_t blk0;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	/*
 	 * do we have good backing store at the requested index ?
 	 */
@@ -1058,7 +1059,7 @@ static void
 swap_pager_unswapped(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
 }
 
@@ -1147,7 +1148,7 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	/*
 	 * Getpbuf() can sleep.
 	 */
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	/*
 	 * Get a swap buffer header to perform the IO
 	 */
@@ -1168,7 +1169,7 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	bp->b_bufsize = PAGE_SIZE * (j - i);
 	bp->b_pager.pg_reqpage = reqpage - i;
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	{
 		int k;
 
@@ -1187,7 +1188,7 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	 * does not remove it.
 	 */
 	vm_object_pip_add(object, bp->b_npages);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	/*
 	 * perform the I/O.  NOTE!!!  bp cannot be considered valid after
@@ -1208,7 +1209,7 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	 * cleared on completion.  If an I/O error occurs, SWAPBLK_NONE
 	 * is set in the meta-data.
 	 */
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	while ((mreq->oflags & VPO_SWAPINPROG) != 0) {
 		mreq->oflags |= VPO_WANTED;
 		PCPU_INC(cnt.v_intrans);
@@ -1283,7 +1284,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 	 */
 	if (object->type != OBJT_SWAP)
 		swp_pager_meta_build(object, 0, SWAPBLK_NONE);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	if (curproc != pageproc)
 		sync = TRUE;
@@ -1378,7 +1379,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 		bp->b_bufsize = PAGE_SIZE * n;
 		bp->b_blkno = blk;
 
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		for (j = 0; j < n; ++j) {
 			vm_page_t mreq = m[i+j];
 
@@ -1393,7 +1394,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 			mreq->oflags |= VPO_SWAPINPROG;
 			bp->b_pages[j] = mreq;
 		}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		bp->b_npages = n;
 		/*
 		 * Must set dirty range for NFS to work.
@@ -1443,7 +1444,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 		 */
 		swp_pager_async_iodone(bp);
 	}
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 }
 
 /*
@@ -1487,7 +1488,7 @@ swp_pager_async_iodone(struct buf *bp)
 
 	if (bp->b_npages) {
 		object = bp->b_pages[0]->object;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 	}
 
 	/*
@@ -1611,7 +1612,7 @@ swp_pager_async_iodone(struct buf *bp)
 	 */
 	if (object != NULL) {
 		vm_object_pip_wakeupn(object, bp->b_npages);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 
 	/*
@@ -1652,7 +1653,7 @@ swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
 	int bcount;
 	int i;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (object->type != OBJT_SWAP)
 		return (0);
 
@@ -1746,13 +1747,13 @@ restart:
 			for (j = 0; j < SWAP_META_PAGES; ++j) {
 				if (swp_pager_isondev(swap->swb_pages[j], sp)) {
 					/* avoid deadlock */
-					if (!VM_OBJECT_TRYLOCK(object)) {
+					if (!VM_OBJECT_TRYWLOCK(object)) {
 						break;
 					} else {
 						mtx_unlock(&swhash_mtx);
 						swp_pager_force_pagein(object,
 						    pindex + j);
-						VM_OBJECT_UNLOCK(object);
+						VM_OBJECT_WUNLOCK(object);
 						mtx_lock(&swhash_mtx);
 						goto restart;
 					}
@@ -1808,7 +1809,7 @@ swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
 	struct swblock **pswap;
 	int idx;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	/*
 	 * Convert default object to swap object if necessary
 	 */
@@ -1845,7 +1846,7 @@ retry:
 		swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT);
 		if (swap == NULL) {
 			mtx_unlock(&swhash_mtx);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			if (uma_zone_exhausted(swap_zone)) {
 				if (atomic_cmpset_int(&exhausted, 0, 1))
 					printf("swap zone exhausted, "
@@ -1854,7 +1855,7 @@ retry:
 				pause("swzonex", 10);
 			} else
 				VM_WAIT;
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			goto retry;
 		}
 
@@ -1906,7 +1907,7 @@ static void
 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (object->type != OBJT_SWAP)
 		return;
 
@@ -1952,7 +1953,7 @@ swp_pager_meta_free_all(vm_object_t object)
 {
 	daddr_t index = 0;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (object->type != OBJT_SWAP)
 		return;
 
@@ -2011,7 +2012,7 @@ swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
 	daddr_t r1;
 	int idx;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	/*
 	 * The meta data only exists of the object is OBJT_SWAP
 	 * and even then might not be allocated yet.
@@ -2464,14 +2465,14 @@ vmspace_swap_count(struct vmspace *vmspace)
 	for (cur = map->header.next; cur != &map->header; cur = cur->next) {
 		if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
 		    (object = cur->object.vm_object) != NULL) {
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			if (object->type == OBJT_SWAP &&
 			    object->un_pager.swp.swp_bcount != 0) {
 				n = (cur->end - cur->start) / PAGE_SIZE;
 				count += object->un_pager.swp.swp_bcount *
 				    SWAP_META_PAGES * n / object->size + 1;
 			}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		}
 	}
 	return (count);
diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
index d298064..1879b7e 100644
--- a/sys/vm/uma_core.c
+++ b/sys/vm/uma_core.c
@@ -72,6 +72,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
+#include <sys/rwlock.h>
 #include <sys/sbuf.h>
 #include <sys/smp.h>
 #include <sys/vmmeter.h>
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index b79b3f5..6c41c07 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -81,9 +81,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
-#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 #include <sys/vmmeter.h>
 #include <sys/vnode.h>
@@ -163,14 +163,14 @@ unlock_and_deallocate(struct faultstate *fs)
 {
 
 	vm_object_pip_wakeup(fs->object);
-	VM_OBJECT_UNLOCK(fs->object);
+	VM_OBJECT_WUNLOCK(fs->object);
 	if (fs->object != fs->first_object) {
-		VM_OBJECT_LOCK(fs->first_object);
+		VM_OBJECT_WLOCK(fs->first_object);
 		vm_page_lock(fs->first_m);
 		vm_page_free(fs->first_m);
 		vm_page_unlock(fs->first_m);
 		vm_object_pip_wakeup(fs->first_object);
-		VM_OBJECT_UNLOCK(fs->first_object);
+		VM_OBJECT_WUNLOCK(fs->first_object);
 		fs->first_m = NULL;
 	}
 	vm_object_deallocate(fs->first_object);
@@ -290,7 +290,7 @@ RetryFault:;
 	 * truncation operations) during I/O.  This must be done after
 	 * obtaining the vnode lock in order to avoid possible deadlocks.
 	 */
-	VM_OBJECT_LOCK(fs.first_object);
+	VM_OBJECT_WLOCK(fs.first_object);
 	vm_object_reference_locked(fs.first_object);
 	vm_object_pip_add(fs.first_object, 1);
 
@@ -363,17 +363,17 @@ RetryFault:;
 				vm_page_aflag_set(fs.m, PGA_REFERENCED);
 				vm_page_unlock(fs.m);
 				if (fs.object != fs.first_object) {
-					if (!VM_OBJECT_TRYLOCK(
+					if (!VM_OBJECT_TRYWLOCK(
 					    fs.first_object)) {
-						VM_OBJECT_UNLOCK(fs.object);
-						VM_OBJECT_LOCK(fs.first_object);
-						VM_OBJECT_LOCK(fs.object);
+						VM_OBJECT_WUNLOCK(fs.object);
+						VM_OBJECT_WLOCK(fs.first_object);
+						VM_OBJECT_WLOCK(fs.object);
 					}
 					vm_page_lock(fs.first_m);
 					vm_page_free(fs.first_m);
 					vm_page_unlock(fs.first_m);
 					vm_object_pip_wakeup(fs.first_object);
-					VM_OBJECT_UNLOCK(fs.first_object);
+					VM_OBJECT_WUNLOCK(fs.first_object);
 					fs.first_m = NULL;
 				}
 				unlock_map(&fs);
@@ -383,7 +383,7 @@ RetryFault:;
 					    "vmpfw");
 				}
 				vm_object_pip_wakeup(fs.object);
-				VM_OBJECT_UNLOCK(fs.object);
+				VM_OBJECT_WUNLOCK(fs.object);
 				PCPU_INC(cnt.v_intrans);
 				vm_object_deallocate(fs.first_object);
 				goto RetryFault;
@@ -646,12 +646,12 @@ vnode_locked:
 			 */
 			if (fs.object != fs.first_object) {
 				vm_object_pip_wakeup(fs.object);
-				VM_OBJECT_UNLOCK(fs.object);
+				VM_OBJECT_WUNLOCK(fs.object);
 
 				fs.object = fs.first_object;
 				fs.pindex = fs.first_pindex;
 				fs.m = fs.first_m;
-				VM_OBJECT_LOCK(fs.object);
+				VM_OBJECT_WLOCK(fs.object);
 			}
 			fs.first_m = NULL;
 
@@ -669,11 +669,11 @@ vnode_locked:
 		} else {
 			KASSERT(fs.object != next_object,
 			    ("object loop %p", next_object));
-			VM_OBJECT_LOCK(next_object);
+			VM_OBJECT_WLOCK(next_object);
 			vm_object_pip_add(next_object, 1);
 			if (fs.object != fs.first_object)
 				vm_object_pip_wakeup(fs.object);
-			VM_OBJECT_UNLOCK(fs.object);
+			VM_OBJECT_WUNLOCK(fs.object);
 			fs.object = next_object;
 		}
 	}
@@ -725,7 +725,7 @@ vnode_locked:
 				 */
 				((fs.object->type == OBJT_DEFAULT) ||
 				 (fs.object->type == OBJT_SWAP)) &&
-			    (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) &&
+			    (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) &&
 				/*
 				 * We don't chase down the shadow chain
 				 */
@@ -774,7 +774,7 @@ vnode_locked:
 			 * conditional
 			 */
 			vm_object_pip_wakeup(fs.object);
-			VM_OBJECT_UNLOCK(fs.object);
+			VM_OBJECT_WUNLOCK(fs.object);
 			/*
 			 * Only use the new page below...
 			 */
@@ -782,7 +782,7 @@ vnode_locked:
 			fs.pindex = fs.first_pindex;
 			fs.m = fs.first_m;
 			if (!is_first_object_locked)
-				VM_OBJECT_LOCK(fs.object);
+				VM_OBJECT_WLOCK(fs.object);
 			PCPU_INC(cnt.v_cow_faults);
 			curthread->td_cow++;
 		} else {
@@ -903,7 +903,7 @@ vnode_locked:
 	 */
 	KASSERT(fs.m->valid == VM_PAGE_BITS_ALL,
 	    ("vm_fault: page %p partially invalid", fs.m));
-	VM_OBJECT_UNLOCK(fs.object);
+	VM_OBJECT_WUNLOCK(fs.object);
 
 	/*
 	 * Put this page into the physical map.  We had to do the unlock above
@@ -914,7 +914,7 @@ vnode_locked:
 	pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired);
 	if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0)
 		vm_fault_prefault(fs.map->pmap, vaddr, fs.entry);
-	VM_OBJECT_LOCK(fs.object);
+	VM_OBJECT_WLOCK(fs.object);
 	vm_page_lock(fs.m);
 
 	/*
@@ -960,13 +960,13 @@ vm_fault_cache_behind(const struct faultstate *fs, int distance)
 	vm_pindex_t pindex;
 
 	object = fs->object;
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	first_object = fs->first_object;
 	if (first_object != object) {
-		if (!VM_OBJECT_TRYLOCK(first_object)) {
-			VM_OBJECT_UNLOCK(object);
-			VM_OBJECT_LOCK(first_object);
-			VM_OBJECT_LOCK(object);
+		if (!VM_OBJECT_TRYWLOCK(first_object)) {
+			VM_OBJECT_WUNLOCK(object);
+			VM_OBJECT_WLOCK(first_object);
+			VM_OBJECT_WLOCK(object);
 		}
 	}
 	/* Neither fictitious nor unmanaged pages can be cached. */
@@ -999,7 +999,7 @@ vm_fault_cache_behind(const struct faultstate *fs, int distance)
 		}
 	}
 	if (first_object != object)
-		VM_OBJECT_UNLOCK(first_object);
+		VM_OBJECT_WUNLOCK(first_object);
 }
 
 /*
@@ -1044,28 +1044,28 @@ vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
 
 		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
 		lobject = object;
-		VM_OBJECT_LOCK(lobject);
+		VM_OBJECT_WLOCK(lobject);
 		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
 		    lobject->type == OBJT_DEFAULT &&
 		    (backing_object = lobject->backing_object) != NULL) {
 			KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
 			    0, ("vm_fault_prefault: unaligned object offset"));
 			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
-			VM_OBJECT_LOCK(backing_object);
-			VM_OBJECT_UNLOCK(lobject);
+			VM_OBJECT_WLOCK(backing_object);
+			VM_OBJECT_WUNLOCK(lobject);
 			lobject = backing_object;
 		}
 		/*
 		 * give-up when a page is not in memory
 		 */
 		if (m == NULL) {
-			VM_OBJECT_UNLOCK(lobject);
+			VM_OBJECT_WUNLOCK(lobject);
 			break;
 		}
 		if (m->valid == VM_PAGE_BITS_ALL &&
 		    (m->flags & PG_FICTITIOUS) == 0)
 			pmap_enter_quick(pmap, addr, m, entry->protection);
-		VM_OBJECT_UNLOCK(lobject);
+		VM_OBJECT_WUNLOCK(lobject);
 	}
 }
 
@@ -1257,7 +1257,7 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 	dst_object->pg_color = atop(dst_entry->start);
 #endif
 
-	VM_OBJECT_LOCK(dst_object);
+	VM_OBJECT_WLOCK(dst_object);
 	KASSERT(upgrade || dst_entry->object.vm_object == NULL,
 	    ("vm_fault_copy_entry: vm_object not NULL"));
 	dst_entry->object.vm_object = dst_object;
@@ -1307,9 +1307,9 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 			dst_m = vm_page_alloc(dst_object, dst_pindex,
 			    VM_ALLOC_NORMAL);
 			if (dst_m == NULL) {
-				VM_OBJECT_UNLOCK(dst_object);
+				VM_OBJECT_WUNLOCK(dst_object);
 				VM_WAIT;
-				VM_OBJECT_LOCK(dst_object);
+				VM_OBJECT_WLOCK(dst_object);
 			}
 		} while (dst_m == NULL);
 
@@ -1318,7 +1318,7 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 		 * (Because the source is wired down, the page will be in
 		 * memory.)
 		 */
-		VM_OBJECT_LOCK(src_object);
+		VM_OBJECT_WLOCK(src_object);
 		object = src_object;
 		pindex = src_pindex + dst_pindex;
 		while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
@@ -1327,18 +1327,18 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 			/*
 			 * Allow fallback to backing objects if we are reading.
 			 */
-			VM_OBJECT_LOCK(backing_object);
+			VM_OBJECT_WLOCK(backing_object);
 			pindex += OFF_TO_IDX(object->backing_object_offset);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			object = backing_object;
 		}
 		if (src_m == NULL)
 			panic("vm_fault_copy_wired: page missing");
 		pmap_copy_page(src_m, dst_m);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		dst_m->valid = VM_PAGE_BITS_ALL;
 		dst_m->dirty = VM_PAGE_BITS_ALL;
-		VM_OBJECT_UNLOCK(dst_object);
+		VM_OBJECT_WUNLOCK(dst_object);
 
 		/*
 		 * Enter it in the pmap. If a wired, copy-on-write
@@ -1350,7 +1350,7 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 		/*
 		 * Mark it no longer busy, and put it on the active list.
 		 */
-		VM_OBJECT_LOCK(dst_object);
+		VM_OBJECT_WLOCK(dst_object);
 		
 		if (upgrade) {
 			vm_page_lock(src_m);
@@ -1367,7 +1367,7 @@ vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
 		}
 		vm_page_wakeup(dst_m);
 	}
-	VM_OBJECT_UNLOCK(dst_object);
+	VM_OBJECT_WUNLOCK(dst_object);
 	if (upgrade) {
 		dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
 		vm_object_deallocate(src_object);
@@ -1403,7 +1403,7 @@ vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
 	vm_page_t rtm;
 	int cbehind, cahead;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 
 	object = m->object;
 	pindex = m->pindex;
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index f44f04c..e0a8bf7 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -71,6 +71,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 #include <sys/racct.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/sched.h>
 #include <sys/sf_buf.h>
 #include <sys/shm.h>
@@ -238,7 +239,7 @@ vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
 	vm_pindex_t pindex;
 	int rv;
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	pindex = OFF_TO_IDX(offset);
 	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
 	if (m->valid != VM_PAGE_BITS_ALL) {
@@ -260,7 +261,7 @@ vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
 	vm_page_unlock(m);
 	vm_page_wakeup(m);
 out:
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	return (m);
 }
 
@@ -394,7 +395,7 @@ vm_thread_new(struct thread *td, int pages)
 	 * For the length of the stack, link in a real page of ram for each
 	 * page of stack.
 	 */
-	VM_OBJECT_LOCK(ksobj);
+	VM_OBJECT_WLOCK(ksobj);
 	for (i = 0; i < pages; i++) {
 		/*
 		 * Get a kernel stack page.
@@ -404,7 +405,7 @@ vm_thread_new(struct thread *td, int pages)
 		ma[i] = m;
 		m->valid = VM_PAGE_BITS_ALL;
 	}
-	VM_OBJECT_UNLOCK(ksobj);
+	VM_OBJECT_WUNLOCK(ksobj);
 	pmap_qenter(ks, ma, pages);
 	return (1);
 }
@@ -417,7 +418,7 @@ vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
 
 	atomic_add_int(&kstacks, -1);
 	pmap_qremove(ks, pages);
-	VM_OBJECT_LOCK(ksobj);
+	VM_OBJECT_WLOCK(ksobj);
 	for (i = 0; i < pages; i++) {
 		m = vm_page_lookup(ksobj, i);
 		if (m == NULL)
@@ -427,7 +428,7 @@ vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
 		vm_page_free(m);
 		vm_page_unlock(m);
 	}
-	VM_OBJECT_UNLOCK(ksobj);
+	VM_OBJECT_WUNLOCK(ksobj);
 	vm_object_deallocate(ksobj);
 	kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
 	    (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
@@ -505,7 +506,7 @@ vm_thread_swapout(struct thread *td)
 	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
 	pmap_qremove(td->td_kstack, pages);
-	VM_OBJECT_LOCK(ksobj);
+	VM_OBJECT_WLOCK(ksobj);
 	for (i = 0; i < pages; i++) {
 		m = vm_page_lookup(ksobj, i);
 		if (m == NULL)
@@ -515,7 +516,7 @@ vm_thread_swapout(struct thread *td)
 		vm_page_unwire(m, 0);
 		vm_page_unlock(m);
 	}
-	VM_OBJECT_UNLOCK(ksobj);
+	VM_OBJECT_WUNLOCK(ksobj);
 }
 
 /*
@@ -530,7 +531,7 @@ vm_thread_swapin(struct thread *td)
 
 	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
-	VM_OBJECT_LOCK(ksobj);
+	VM_OBJECT_WLOCK(ksobj);
 	for (i = 0; i < pages; i++)
 		ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY |
 		    VM_ALLOC_WIRED);
@@ -557,7 +558,7 @@ vm_thread_swapin(struct thread *td)
 		} else if (ma[i]->oflags & VPO_BUSY)
 			vm_page_wakeup(ma[i]);
 	}
-	VM_OBJECT_UNLOCK(ksobj);
+	VM_OBJECT_WUNLOCK(ksobj);
 	pmap_qenter(td->td_kstack, ma, pages);
 	cpu_thread_swapin(td);
 }
diff --git a/sys/vm/vm_init.c b/sys/vm/vm_init.c
index c507691..08c9b03 100644
--- a/sys/vm/vm_init.c
+++ b/sys/vm/vm_init.c
@@ -68,8 +68,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
-#include <sys/mutex.h>
 #include <sys/proc.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
 #include <sys/selinfo.h>
@@ -157,8 +157,6 @@ vm_ksubmap_init(struct kva_md_info *kmi)
 again:
 	v = (caddr_t)firstaddr;
 
-	v = kern_timeout_callwheel_alloc(v);
-
 	/*
 	 * Discount the physical memory larger than the size of kernel_map
 	 * to avoid eating up all of KVA space.
@@ -202,10 +200,5 @@ again:
 	 * XXX: Mbuf system machine-specific initializations should
 	 *      go here, if anywhere.
 	 */
-
-	/*
-	 * Initialize the callouts we just allocated.
-	 */
-	kern_timeout_callwheel_init();
 }
 
diff --git a/sys/vm/vm_kern.c b/sys/vm/vm_kern.c
index ad9aa0d..9f602b7 100644
--- a/sys/vm/vm_kern.c
+++ b/sys/vm/vm_kern.c
@@ -70,9 +70,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>		/* for ticks and hz */
 #include <sys/eventhandler.h>
 #include <sys/lock.h>
-#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/malloc.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 
 #include <vm/vm.h>
@@ -234,7 +234,7 @@ kmem_alloc_attr(vm_map_t map, vm_size_t size, int flags, vm_paddr_t low,
 	vm_map_insert(map, object, offset, addr, addr + size, VM_PROT_ALL,
 	    VM_PROT_ALL, 0);
 	pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	end_offset = offset + size;
 	for (; offset < end_offset; offset += PAGE_SIZE) {
 		tries = 0;
@@ -242,12 +242,12 @@ retry:
 		m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags, 1,
 		    low, high, PAGE_SIZE, 0, memattr);
 		if (m == NULL) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
 				vm_map_unlock(map);
 				vm_pageout_grow_cache(tries, low, high);
 				vm_map_lock(map);
-				VM_OBJECT_LOCK(object);
+				VM_OBJECT_WLOCK(object);
 				tries++;
 				goto retry;
 			}
@@ -266,7 +266,7 @@ retry:
 			pmap_zero_page(m);
 		m->valid = VM_PAGE_BITS_ALL;
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	vm_map_unlock(map);
 	vm_map_wire(map, addr, addr + size, VM_MAP_WIRE_SYSTEM |
 	    VM_MAP_WIRE_NOHOLES);
@@ -303,18 +303,18 @@ kmem_alloc_contig(vm_map_t map, vm_size_t size, int flags, vm_paddr_t low,
 	vm_map_insert(map, object, offset, addr, addr + size, VM_PROT_ALL,
 	    VM_PROT_ALL, 0);
 	pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	tries = 0;
 retry:
 	m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags,
 	    atop(size), low, high, alignment, boundary, memattr);
 	if (m == NULL) {
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
 			vm_map_unlock(map);
 			vm_pageout_grow_cache(tries, low, high);
 			vm_map_lock(map);
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			tries++;
 			goto retry;
 		}
@@ -328,7 +328,7 @@ retry:
 			pmap_zero_page(m);
 		m->valid = VM_PAGE_BITS_ALL;
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	vm_map_unlock(map);
 	vm_map_wire(map, addr, addr + size, VM_MAP_WIRE_SYSTEM |
 	    VM_MAP_WIRE_NOHOLES);
@@ -488,7 +488,7 @@ kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
 
 	pflags = malloc2vm_flags(flags) | VM_ALLOC_WIRED;
 
-	VM_OBJECT_LOCK(kmem_object);
+	VM_OBJECT_WLOCK(kmem_object);
 	for (i = 0; i < size; i += PAGE_SIZE) {
 retry:
 		m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i), pflags);
@@ -500,7 +500,7 @@ retry:
 		 */
 		if (m == NULL) {
 			if ((flags & M_NOWAIT) == 0) {
-				VM_OBJECT_UNLOCK(kmem_object);
+				VM_OBJECT_WUNLOCK(kmem_object);
 				entry->eflags |= MAP_ENTRY_IN_TRANSITION;
 				vm_map_unlock(map);
 				VM_WAIT;
@@ -510,7 +510,7 @@ retry:
 				    MAP_ENTRY_IN_TRANSITION,
 				    ("kmem_back: volatile entry"));
 				entry->eflags &= ~MAP_ENTRY_IN_TRANSITION;
-				VM_OBJECT_LOCK(kmem_object);
+				VM_OBJECT_WLOCK(kmem_object);
 				goto retry;
 			}
 			/* 
@@ -526,7 +526,7 @@ retry:
 				vm_page_unwire(m, 0);
 				vm_page_free(m);
 			}
-			VM_OBJECT_UNLOCK(kmem_object);
+			VM_OBJECT_WUNLOCK(kmem_object);
 			vm_map_delete(map, addr, addr + size);
 			return (KERN_NO_SPACE);
 		}
@@ -536,7 +536,7 @@ retry:
 		KASSERT((m->oflags & VPO_UNMANAGED) != 0,
 		    ("kmem_malloc: page %p is managed", m));
 	}
-	VM_OBJECT_UNLOCK(kmem_object);
+	VM_OBJECT_WUNLOCK(kmem_object);
 
 	/*
 	 * Mark map entry as non-pageable.  Repeat the assert.
@@ -556,7 +556,7 @@ retry:
 	/*
 	 * Loop thru pages, entering them in the pmap.
 	 */
-	VM_OBJECT_LOCK(kmem_object);
+	VM_OBJECT_WLOCK(kmem_object);
 	for (i = 0; i < size; i += PAGE_SIZE) {
 		m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
 		/*
@@ -566,7 +566,7 @@ retry:
 		    TRUE);
 		vm_page_wakeup(m);
 	}
-	VM_OBJECT_UNLOCK(kmem_object);
+	VM_OBJECT_WUNLOCK(kmem_object);
 
 	return (KERN_SUCCESS);
 }
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 35ac468..72d3983 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -77,6 +77,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/vnode.h>
 #include <sys/racct.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/file.h>
 #include <sys/sysctl.h>
 #include <sys/sysent.h>
@@ -1222,10 +1223,10 @@ charged:
 		 * reference counting is insufficient to recognize
 		 * aliases with precision.)
 		 */
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (object->ref_count > 1 || object->shadow_count != 0)
 			vm_object_clear_flag(object, OBJ_ONEMAPPING);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	else if ((prev_entry != &map->header) &&
 		 (prev_entry->eflags == protoeflags) &&
@@ -1623,12 +1624,12 @@ _vm_map_clip_start(vm_map_t map, vm_map_entry_t entry, vm_offset_t start)
 	} else if (entry->object.vm_object != NULL &&
 		   ((entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) &&
 		   entry->cred != NULL) {
-		VM_OBJECT_LOCK(entry->object.vm_object);
+		VM_OBJECT_WLOCK(entry->object.vm_object);
 		KASSERT(entry->object.vm_object->cred == NULL,
 		    ("OVERCOMMIT: vm_entry_clip_start: both cred e %p", entry));
 		entry->object.vm_object->cred = entry->cred;
 		entry->object.vm_object->charge = entry->end - entry->start;
-		VM_OBJECT_UNLOCK(entry->object.vm_object);
+		VM_OBJECT_WUNLOCK(entry->object.vm_object);
 		entry->cred = NULL;
 	}
 
@@ -1700,12 +1701,12 @@ _vm_map_clip_end(vm_map_t map, vm_map_entry_t entry, vm_offset_t end)
 	} else if (entry->object.vm_object != NULL &&
 		   ((entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) &&
 		   entry->cred != NULL) {
-		VM_OBJECT_LOCK(entry->object.vm_object);
+		VM_OBJECT_WLOCK(entry->object.vm_object);
 		KASSERT(entry->object.vm_object->cred == NULL,
 		    ("OVERCOMMIT: vm_entry_clip_end: both cred e %p", entry));
 		entry->object.vm_object->cred = entry->cred;
 		entry->object.vm_object->charge = entry->end - entry->start;
-		VM_OBJECT_UNLOCK(entry->object.vm_object);
+		VM_OBJECT_WUNLOCK(entry->object.vm_object);
 		entry->cred = NULL;
 	}
 
@@ -1805,7 +1806,7 @@ vm_map_pmap_enter(vm_map_t map, vm_offset_t addr, vm_prot_t prot,
 
 	if ((prot & (VM_PROT_READ | VM_PROT_EXECUTE)) == 0 || object == NULL)
 		return;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (object->type == OBJT_DEVICE || object->type == OBJT_SG) {
 		pmap_object_init_pt(map->pmap, addr, object, pindex, size);
 		goto unlock_return;
@@ -1856,7 +1857,7 @@ vm_map_pmap_enter(vm_map_t map, vm_offset_t addr, vm_prot_t prot,
 		pmap_enter_object(map->pmap, start, addr + ptoa(psize),
 		    p_start, prot);
 unlock_return:
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 }
 
 /*
@@ -1932,9 +1933,9 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
 			continue;
 		}
 
-		VM_OBJECT_LOCK(obj);
+		VM_OBJECT_WLOCK(obj);
 		if (obj->type != OBJT_DEFAULT && obj->type != OBJT_SWAP) {
-			VM_OBJECT_UNLOCK(obj);
+			VM_OBJECT_WUNLOCK(obj);
 			continue;
 		}
 
@@ -1946,7 +1947,7 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
 		KASSERT(obj->charge == 0,
 		    ("vm_map_protect: object %p overcharged\n", obj));
 		if (!swap_reserve(ptoa(obj->size))) {
-			VM_OBJECT_UNLOCK(obj);
+			VM_OBJECT_WUNLOCK(obj);
 			vm_map_unlock(map);
 			return (KERN_RESOURCE_SHORTAGE);
 		}
@@ -1954,7 +1955,7 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
 		crhold(cred);
 		obj->cred = cred;
 		obj->charge = ptoa(obj->size);
-		VM_OBJECT_UNLOCK(obj);
+		VM_OBJECT_WUNLOCK(obj);
 	}
 
 	/*
@@ -2717,7 +2718,7 @@ vm_map_entry_delete(vm_map_t map, vm_map_entry_t entry)
 		count = OFF_TO_IDX(size);
 		offidxstart = OFF_TO_IDX(entry->offset);
 		offidxend = offidxstart + count;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (object->ref_count != 1 &&
 		    ((object->flags & (OBJ_NOSPLIT|OBJ_ONEMAPPING)) == OBJ_ONEMAPPING ||
 		    object == kernel_object || object == kmem_object)) {
@@ -2746,7 +2747,7 @@ vm_map_entry_delete(vm_map_t map, vm_map_entry_t entry)
 				}
 			}
 		}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	} else
 		entry->object.vm_object = NULL;
 	if (map->system_map)
@@ -2954,7 +2955,7 @@ vm_map_copy_entry(
 		 */
 		size = src_entry->end - src_entry->start;
 		if ((src_object = src_entry->object.vm_object) != NULL) {
-			VM_OBJECT_LOCK(src_object);
+			VM_OBJECT_WLOCK(src_object);
 			charged = ENTRY_CHARGED(src_entry);
 			if ((src_object->handle == NULL) &&
 				(src_object->type == OBJT_DEFAULT ||
@@ -2975,7 +2976,7 @@ vm_map_copy_entry(
 				src_object->cred = src_entry->cred;
 				src_object->charge = size;
 			}
-			VM_OBJECT_UNLOCK(src_object);
+			VM_OBJECT_WUNLOCK(src_object);
 			dst_entry->object.vm_object = src_object;
 			if (charged) {
 				cred = curthread->td_ucred;
@@ -3151,7 +3152,7 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge)
 				vm_object_deallocate(object);
 				object = old_entry->object.vm_object;
 			}
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			vm_object_clear_flag(object, OBJ_ONEMAPPING);
 			if (old_entry->cred != NULL) {
 				KASSERT(object->cred == NULL, ("vmspace_fork both cred"));
@@ -3159,7 +3160,7 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge)
 				object->charge = old_entry->end - old_entry->start;
 				old_entry->cred = NULL;
 			}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 
 			/*
 			 * Clone the entry, referencing the shared object.
@@ -3845,10 +3846,10 @@ RetryLookup:;
 				crfree(entry->cred);
 				entry->cred = NULL;
 			} else if (entry->cred != NULL) {
-				VM_OBJECT_LOCK(eobject);
+				VM_OBJECT_WLOCK(eobject);
 				eobject->cred = entry->cred;
 				eobject->charge = size;
-				VM_OBJECT_UNLOCK(eobject);
+				VM_OBJECT_WUNLOCK(eobject);
 				entry->cred = NULL;
 			}
 
@@ -3873,10 +3874,10 @@ RetryLookup:;
 		    atop(size));
 		entry->offset = 0;
 		if (entry->cred != NULL) {
-			VM_OBJECT_LOCK(entry->object.vm_object);
+			VM_OBJECT_WLOCK(entry->object.vm_object);
 			entry->object.vm_object->cred = entry->cred;
 			entry->object.vm_object->charge = size;
-			VM_OBJECT_UNLOCK(entry->object.vm_object);
+			VM_OBJECT_WUNLOCK(entry->object.vm_object);
 			entry->cred = NULL;
 		}
 		vm_map_lock_downgrade(map);
diff --git a/sys/vm/vm_meter.c b/sys/vm/vm_meter.c
index 05174e9..713a2be 100644
--- a/sys/vm/vm_meter.c
+++ b/sys/vm/vm_meter.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/resource.h>
+#include <sys/rwlock.h>
 #include <sys/sx.h>
 #include <sys/vmmeter.h>
 #include <sys/smp.h>
@@ -110,7 +111,7 @@ vmtotal(SYSCTL_HANDLER_ARGS)
 	 */
 	mtx_lock(&vm_object_list_mtx);
 	TAILQ_FOREACH(object, &vm_object_list, object_list) {
-		if (!VM_OBJECT_TRYLOCK(object)) {
+		if (!VM_OBJECT_TRYWLOCK(object)) {
 			/*
 			 * Avoid a lock-order reversal.  Consequently,
 			 * the reported number of active pages may be
@@ -119,7 +120,7 @@ vmtotal(SYSCTL_HANDLER_ARGS)
 			continue;
 		}
 		vm_object_clear_flag(object, OBJ_ACTIVE);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	mtx_unlock(&vm_object_list_mtx);
 	/*
@@ -178,10 +179,10 @@ vmtotal(SYSCTL_HANDLER_ARGS)
 			if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) ||
 			    (object = entry->object.vm_object) == NULL)
 				continue;
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			vm_object_set_flag(object, OBJ_ACTIVE);
 			paging |= object->paging_in_progress;
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		}
 		vm_map_unlock_read(map);
 		vmspace_free(vm);
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index cf94fe5..248d9e8 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -59,6 +59,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/racct.h>
 #include <sys/resource.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 #include <sys/vnode.h>
 #include <sys/fcntl.h>
@@ -880,12 +881,12 @@ RestartScan:
 				m = PHYS_TO_VM_PAGE(locked_pa);
 				if (m->object != object) {
 					if (object != NULL)
-						VM_OBJECT_UNLOCK(object);
+						VM_OBJECT_WUNLOCK(object);
 					object = m->object;
-					locked = VM_OBJECT_TRYLOCK(object);
+					locked = VM_OBJECT_TRYWLOCK(object);
 					vm_page_unlock(m);
 					if (!locked) {
-						VM_OBJECT_LOCK(object);
+						VM_OBJECT_WLOCK(object);
 						vm_page_lock(m);
 						goto retry;
 					}
@@ -903,9 +904,9 @@ RestartScan:
 				 */
 				if (current->object.vm_object != object) {
 					if (object != NULL)
-						VM_OBJECT_UNLOCK(object);
+						VM_OBJECT_WUNLOCK(object);
 					object = current->object.vm_object;
-					VM_OBJECT_LOCK(object);
+					VM_OBJECT_WLOCK(object);
 				}
 				if (object->type == OBJT_DEFAULT ||
 				    object->type == OBJT_SWAP ||
@@ -942,7 +943,7 @@ RestartScan:
 					mincoreinfo |= MINCORE_REFERENCED_OTHER;
 			}
 			if (object != NULL)
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 
 			/*
 			 * subyte may page fault.  In case it needs to modify
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 606b605..255d919 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -78,6 +78,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>		/* for curproc, pageproc */
 #include <sys/socket.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/vnode.h>
 #include <sys/vmmeter.h>
 #include <sys/sx.h>
@@ -195,8 +196,8 @@ vm_object_zinit(void *mem, int size, int flags)
 	vm_object_t object;
 
 	object = (vm_object_t)mem;
-	bzero(&object->mtx, sizeof(object->mtx));
-	mtx_init(&object->mtx, "vm object", NULL, MTX_DEF | MTX_DUPOK);
+	bzero(&object->lock, sizeof(object->lock));
+	rw_init_flags(&object->lock, "vm object", RW_DUPOK);
 
 	/* These are true for any object that has been freed */
 	object->rtree.rt_root = 0;
@@ -267,7 +268,7 @@ vm_object_init(void)
 	TAILQ_INIT(&vm_object_list);
 	mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
 	
-	mtx_init(&kernel_object->mtx, "vm object", "kernel object", MTX_DEF);
+	rw_init(&kernel_object->lock, "kernel vm object");
 	_vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 	    kernel_object);
 #if VM_NRESERVLEVEL > 0
@@ -275,7 +276,7 @@ vm_object_init(void)
 	kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
 #endif
 
-	mtx_init(&kmem_object->mtx, "vm object", "kmem object", MTX_DEF);
+	rw_init(&kmem_object->lock, "kmem vm object");
 	_vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
 	    kmem_object);
 #if VM_NRESERVLEVEL > 0
@@ -303,7 +304,7 @@ void
 vm_object_clear_flag(vm_object_t object, u_short bits)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	object->flags &= ~bits;
 }
 
@@ -320,7 +321,7 @@ int
 vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	switch (object->type) {
 	case OBJT_DEFAULT:
 	case OBJT_DEVICE:
@@ -346,7 +347,7 @@ void
 vm_object_pip_add(vm_object_t object, short i)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	object->paging_in_progress += i;
 }
 
@@ -354,7 +355,7 @@ void
 vm_object_pip_subtract(vm_object_t object, short i)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	object->paging_in_progress -= i;
 }
 
@@ -362,7 +363,7 @@ void
 vm_object_pip_wakeup(vm_object_t object)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	object->paging_in_progress--;
 	if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
 		vm_object_clear_flag(object, OBJ_PIPWNT);
@@ -374,7 +375,7 @@ void
 vm_object_pip_wakeupn(vm_object_t object, short i)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (i)
 		object->paging_in_progress -= i;
 	if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
@@ -387,7 +388,7 @@ void
 vm_object_pip_wait(vm_object_t object, char *waitid)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	while (object->paging_in_progress) {
 		object->flags |= OBJ_PIPWNT;
 		VM_OBJECT_SLEEP(object, object, PVM, waitid, 0);
@@ -421,9 +422,9 @@ vm_object_reference(vm_object_t object)
 {
 	if (object == NULL)
 		return;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	vm_object_reference_locked(object);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 }
 
 /*
@@ -438,7 +439,7 @@ vm_object_reference_locked(vm_object_t object)
 {
 	struct vnode *vp;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	object->ref_count++;
 	if (object->type == OBJT_VNODE) {
 		vp = object->handle;
@@ -454,7 +455,7 @@ vm_object_vndeallocate(vm_object_t object)
 {
 	struct vnode *vp = (struct vnode *) object->handle;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT(object->type == OBJT_VNODE,
 	    ("vm_object_vndeallocate: not a vnode object"));
 	KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
@@ -467,23 +468,23 @@ vm_object_vndeallocate(vm_object_t object)
 
 	if (object->ref_count > 1) {
 		object->ref_count--;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		/* vrele may need the vnode lock. */
 		vrele(vp);
 	} else {
 		vhold(vp);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 		vdrop(vp);
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		object->ref_count--;
 		if (object->type == OBJT_DEAD) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			VOP_UNLOCK(vp, 0);
 		} else {
 			if (object->ref_count == 0)
 				VOP_UNSET_TEXT(vp);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			vput(vp);
 		}
 	}
@@ -506,7 +507,7 @@ vm_object_deallocate(vm_object_t object)
 	vm_object_t temp;
 
 	while (object != NULL) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (object->type == OBJT_VNODE) {
 			vm_object_vndeallocate(object);
 			return;
@@ -523,7 +524,7 @@ vm_object_deallocate(vm_object_t object)
 		 */
 		object->ref_count--;
 		if (object->ref_count > 1) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			return;
 		} else if (object->ref_count == 1) {
 			if (object->shadow_count == 0 &&
@@ -542,12 +543,12 @@ vm_object_deallocate(vm_object_t object)
 				    ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
 					 object->ref_count,
 					 object->shadow_count));
-				if (!VM_OBJECT_TRYLOCK(robject)) {
+				if (!VM_OBJECT_TRYWLOCK(robject)) {
 					/*
 					 * Avoid a potential deadlock.
 					 */
 					object->ref_count++;
-					VM_OBJECT_UNLOCK(object);
+					VM_OBJECT_WUNLOCK(object);
 					/*
 					 * More likely than not the thread
 					 * holding robject's lock has lower
@@ -571,27 +572,27 @@ vm_object_deallocate(vm_object_t object)
 					robject->ref_count++;
 retry:
 					if (robject->paging_in_progress) {
-						VM_OBJECT_UNLOCK(object);
+						VM_OBJECT_WUNLOCK(object);
 						vm_object_pip_wait(robject,
 						    "objde1");
 						temp = robject->backing_object;
 						if (object == temp) {
-							VM_OBJECT_LOCK(object);
+							VM_OBJECT_WLOCK(object);
 							goto retry;
 						}
 					} else if (object->paging_in_progress) {
-						VM_OBJECT_UNLOCK(robject);
+						VM_OBJECT_WUNLOCK(robject);
 						object->flags |= OBJ_PIPWNT;
 						VM_OBJECT_SLEEP(object, object,
 						    PDROP | PVM, "objde2", 0);
-						VM_OBJECT_LOCK(robject);
+						VM_OBJECT_WLOCK(robject);
 						temp = robject->backing_object;
 						if (object == temp) {
-							VM_OBJECT_LOCK(object);
+							VM_OBJECT_WLOCK(object);
 							goto retry;
 						}
 					} else
-						VM_OBJECT_UNLOCK(object);
+						VM_OBJECT_WUNLOCK(object);
 
 					if (robject->ref_count == 1) {
 						robject->ref_count--;
@@ -600,21 +601,21 @@ retry:
 					}
 					object = robject;
 					vm_object_collapse(object);
-					VM_OBJECT_UNLOCK(object);
+					VM_OBJECT_WUNLOCK(object);
 					continue;
 				}
-				VM_OBJECT_UNLOCK(robject);
+				VM_OBJECT_WUNLOCK(robject);
 			}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			return;
 		}
 doterm:
 		temp = object->backing_object;
 		if (temp != NULL) {
-			VM_OBJECT_LOCK(temp);
+			VM_OBJECT_WLOCK(temp);
 			LIST_REMOVE(object, shadow_list);
 			temp->shadow_count--;
-			VM_OBJECT_UNLOCK(temp);
+			VM_OBJECT_WUNLOCK(temp);
 			object->backing_object = NULL;
 		}
 		/*
@@ -625,7 +626,7 @@ doterm:
 		if ((object->flags & OBJ_DEAD) == 0)
 			vm_object_terminate(object);
 		else
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		object = temp;
 	}
 }
@@ -677,7 +678,7 @@ vm_object_terminate(vm_object_t object)
 {
 	vm_page_t p, p_next;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	/*
 	 * Make sure no one uses us.
@@ -703,11 +704,11 @@ vm_object_terminate(vm_object_t object)
 		 * Clean pages and flush buffers.
 		 */
 		vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 
 		vinvalbuf(vp, V_SAVE, 0, 0);
 
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 	}
 
 	KASSERT(object->ref_count == 0, 
@@ -762,7 +763,7 @@ vm_object_terminate(vm_object_t object)
 	 * Let the pager know object is dead.
 	 */
 	vm_pager_deallocate(object);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	vm_object_destroy(object);
 }
@@ -818,7 +819,7 @@ vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
 	int curgeneration, n, pagerflags;
 	boolean_t clearobjflags, eio, res;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT(object->type == OBJT_VNODE, ("Not a vnode object"));
 	if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
 	    object->resident_page_count == 0)
@@ -904,7 +905,7 @@ vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
 	int count, i, mreq, runlen;
 
 	vm_page_lock_assert(p, MA_NOTOWNED);
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	count = 1;
 	mreq = 0;
@@ -962,11 +963,11 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
 		return (TRUE);
 	res = TRUE;
 	error = 0;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	while ((backing_object = object->backing_object) != NULL) {
-		VM_OBJECT_LOCK(backing_object);
+		VM_OBJECT_WLOCK(backing_object);
 		offset += object->backing_object_offset;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		object = backing_object;
 		if (object->size < OFF_TO_IDX(offset + size))
 			size = IDX_TO_OFF(object->size) - offset;
@@ -986,7 +987,7 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
 	if (object->type == OBJT_VNODE &&
 	    (object->flags & OBJ_MIGHTBEDIRTY) != 0) {
 		vp = object->handle;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		(void) vn_start_write(vp, &mp, V_WAIT);
 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 		if (syncio && !invalidate && offset == 0 &&
@@ -1004,17 +1005,17 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
 			flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
 			fsync_after = FALSE;
 		}
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		res = vm_object_page_clean(object, offset, offset + size,
 		    flags);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		if (fsync_after)
 			error = VOP_FSYNC(vp, MNT_WAIT, curthread);
 		VOP_UNLOCK(vp, 0);
 		vn_finished_write(mp);
 		if (error != 0)
 			res = FALSE;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 	}
 	if ((object->type == OBJT_VNODE ||
 	     object->type == OBJT_DEVICE) && invalidate) {
@@ -1032,7 +1033,7 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
 		vm_object_page_remove(object, OFF_TO_IDX(offset),
 		    OFF_TO_IDX(offset + size + PAGE_MASK), flags);
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	return (res);
 }
 
@@ -1067,7 +1068,7 @@ vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
 
 	if (object == NULL)
 		return;
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	/*
 	 * Locate and adjust resident pages
 	 */
@@ -1108,10 +1109,10 @@ shadowlookup:
 			backing_object = tobject->backing_object;
 			if (backing_object == NULL)
 				goto unlock_tobject;
-			VM_OBJECT_LOCK(backing_object);
+			VM_OBJECT_WLOCK(backing_object);
 			tpindex += OFF_TO_IDX(tobject->backing_object_offset);
 			if (tobject != object)
-				VM_OBJECT_UNLOCK(tobject);
+				VM_OBJECT_WUNLOCK(tobject);
 			tobject = backing_object;
 			goto shadowlookup;
 		} else if (m->valid != VM_PAGE_BITS_ALL)
@@ -1139,10 +1140,10 @@ shadowlookup:
 			}
 			vm_page_unlock(m);
 			if (object != tobject)
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 			m->oflags |= VPO_WANTED;
 			VM_OBJECT_SLEEP(tobject, m, PDROP | PVM, "madvpo", 0);
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
   			goto relookup;
 		}
 		if (advise == MADV_WILLNEED) {
@@ -1175,9 +1176,9 @@ shadowlookup:
 			swap_pager_freespace(tobject, tpindex, 1);
 unlock_tobject:
 		if (tobject != object)
-			VM_OBJECT_UNLOCK(tobject);
+			VM_OBJECT_WUNLOCK(tobject);
 	}	
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 }
 
 /*
@@ -1205,15 +1206,15 @@ vm_object_shadow(
 	 * Don't create the new object if the old object isn't shared.
 	 */
 	if (source != NULL) {
-		VM_OBJECT_LOCK(source);
+		VM_OBJECT_WLOCK(source);
 		if (source->ref_count == 1 &&
 		    source->handle == NULL &&
 		    (source->type == OBJT_DEFAULT ||
 		     source->type == OBJT_SWAP)) {
-			VM_OBJECT_UNLOCK(source);
+			VM_OBJECT_WUNLOCK(source);
 			return;
 		}
-		VM_OBJECT_UNLOCK(source);
+		VM_OBJECT_WUNLOCK(source);
 	}
 
 	/*
@@ -1238,7 +1239,7 @@ vm_object_shadow(
 	 */
 	result->backing_object_offset = *offset;
 	if (source != NULL) {
-		VM_OBJECT_LOCK(source);
+		VM_OBJECT_WLOCK(source);
 		LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
 		source->shadow_count++;
 #if VM_NRESERVLEVEL > 0
@@ -1246,7 +1247,7 @@ vm_object_shadow(
 		result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
 		    ((1 << (VM_NFREEORDER - 1)) - 1);
 #endif
-		VM_OBJECT_UNLOCK(source);
+		VM_OBJECT_WUNLOCK(source);
 	}
 
 
@@ -1277,7 +1278,7 @@ vm_object_split(vm_map_entry_t entry)
 		return;
 	if (orig_object->ref_count <= 1)
 		return;
-	VM_OBJECT_UNLOCK(orig_object);
+	VM_OBJECT_WUNLOCK(orig_object);
 
 	offidxstart = OFF_TO_IDX(entry->offset);
 	size = atop(entry->end - entry->start);
@@ -1292,17 +1293,17 @@ vm_object_split(vm_map_entry_t entry)
 	 * At this point, the new object is still private, so the order in
 	 * which the original and new objects are locked does not matter.
 	 */
-	VM_OBJECT_LOCK(new_object);
-	VM_OBJECT_LOCK(orig_object);
+	VM_OBJECT_WLOCK(new_object);
+	VM_OBJECT_WLOCK(orig_object);
 	source = orig_object->backing_object;
 	if (source != NULL) {
-		VM_OBJECT_LOCK(source);
+		VM_OBJECT_WLOCK(source);
 		if ((source->flags & OBJ_DEAD) != 0) {
-			VM_OBJECT_UNLOCK(source);
-			VM_OBJECT_UNLOCK(orig_object);
-			VM_OBJECT_UNLOCK(new_object);
+			VM_OBJECT_WUNLOCK(source);
+			VM_OBJECT_WUNLOCK(orig_object);
+			VM_OBJECT_WUNLOCK(new_object);
 			vm_object_deallocate(new_object);
-			VM_OBJECT_LOCK(orig_object);
+			VM_OBJECT_WLOCK(orig_object);
 			return;
 		}
 		LIST_INSERT_HEAD(&source->shadow_head,
@@ -1310,7 +1311,7 @@ vm_object_split(vm_map_entry_t entry)
 		source->shadow_count++;
 		vm_object_reference_locked(source);	/* for new_object */
 		vm_object_clear_flag(source, OBJ_ONEMAPPING);
-		VM_OBJECT_UNLOCK(source);
+		VM_OBJECT_WUNLOCK(source);
 		new_object->backing_object_offset = 
 			orig_object->backing_object_offset + entry->offset;
 		new_object->backing_object = source;
@@ -1337,10 +1338,10 @@ retry:
 		 * not be changed by this operation.
 		 */
 		if ((m->oflags & VPO_BUSY) || m->busy) {
-			VM_OBJECT_UNLOCK(new_object);
+			VM_OBJECT_WUNLOCK(new_object);
 			m->oflags |= VPO_WANTED;
 			VM_OBJECT_SLEEP(orig_object, m, PVM, "spltwt", 0);
-			VM_OBJECT_LOCK(new_object);
+			VM_OBJECT_WLOCK(new_object);
 			goto retry;
 		}
 #if VM_NRESERVLEVEL > 0
@@ -1384,14 +1385,14 @@ retry:
 			vm_page_cache_transfer(orig_object, offidxstart,
 			    new_object);
 	}
-	VM_OBJECT_UNLOCK(orig_object);
+	VM_OBJECT_WUNLOCK(orig_object);
 	TAILQ_FOREACH(m, &new_object->memq, listq)
 		vm_page_wakeup(m);
-	VM_OBJECT_UNLOCK(new_object);
+	VM_OBJECT_WUNLOCK(new_object);
 	entry->object.vm_object = new_object;
 	entry->offset = 0LL;
 	vm_object_deallocate(orig_object);
-	VM_OBJECT_LOCK(new_object);
+	VM_OBJECT_WLOCK(new_object);
 }
 
 #define	OBSC_TEST_ALL_SHADOWED	0x0001
@@ -1406,8 +1407,8 @@ vm_object_backing_scan(vm_object_t object, int op)
 	vm_object_t backing_object;
 	vm_pindex_t backing_offset_index;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(object->backing_object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
+	VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
 
 	backing_object = object->backing_object;
 	backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
@@ -1495,12 +1496,12 @@ vm_object_backing_scan(vm_object_t object, int op)
 				}
 			} else if (op & OBSC_COLLAPSE_WAIT) {
 				if ((p->oflags & VPO_BUSY) || p->busy) {
-					VM_OBJECT_UNLOCK(object);
+					VM_OBJECT_WUNLOCK(object);
 					p->oflags |= VPO_WANTED;
 					VM_OBJECT_SLEEP(backing_object, p,
 					    PDROP | PVM, "vmocol", 0);
-					VM_OBJECT_LOCK(object);
-					VM_OBJECT_LOCK(backing_object);
+					VM_OBJECT_WLOCK(object);
+					VM_OBJECT_WLOCK(backing_object);
 					/*
 					 * If we slept, anything could have
 					 * happened.  Since the object is
@@ -1627,8 +1628,8 @@ vm_object_qcollapse(vm_object_t object)
 {
 	vm_object_t backing_object = object->backing_object;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(backing_object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
+	VM_OBJECT_ASSERT_WLOCKED(backing_object);
 
 	if (backing_object->ref_count != 1)
 		return;
@@ -1646,7 +1647,7 @@ vm_object_qcollapse(vm_object_t object)
 void
 vm_object_collapse(vm_object_t object)
 {
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	
 	while (TRUE) {
 		vm_object_t backing_object;
@@ -1663,7 +1664,7 @@ vm_object_collapse(vm_object_t object)
 		 * we check the backing object first, because it is most likely
 		 * not collapsable.
 		 */
-		VM_OBJECT_LOCK(backing_object);
+		VM_OBJECT_WLOCK(backing_object);
 		if (backing_object->handle != NULL ||
 		    (backing_object->type != OBJT_DEFAULT &&
 		     backing_object->type != OBJT_SWAP) ||
@@ -1672,7 +1673,7 @@ vm_object_collapse(vm_object_t object)
 		    (object->type != OBJT_DEFAULT &&
 		     object->type != OBJT_SWAP) ||
 		    (object->flags & OBJ_DEAD)) {
-			VM_OBJECT_UNLOCK(backing_object);
+			VM_OBJECT_WUNLOCK(backing_object);
 			break;
 		}
 
@@ -1681,7 +1682,7 @@ vm_object_collapse(vm_object_t object)
 		    backing_object->paging_in_progress != 0
 		) {
 			vm_object_qcollapse(object);
-			VM_OBJECT_UNLOCK(backing_object);
+			VM_OBJECT_WUNLOCK(backing_object);
 			break;
 		}
 		/*
@@ -1742,7 +1743,7 @@ vm_object_collapse(vm_object_t object)
 			LIST_REMOVE(object, shadow_list);
 			backing_object->shadow_count--;
 			if (backing_object->backing_object) {
-				VM_OBJECT_LOCK(backing_object->backing_object);
+				VM_OBJECT_WLOCK(backing_object->backing_object);
 				LIST_REMOVE(backing_object, shadow_list);
 				LIST_INSERT_HEAD(
 				    &backing_object->backing_object->shadow_head,
@@ -1750,7 +1751,7 @@ vm_object_collapse(vm_object_t object)
 				/*
 				 * The shadow_count has not changed.
 				 */
-				VM_OBJECT_UNLOCK(backing_object->backing_object);
+				VM_OBJECT_WUNLOCK(backing_object->backing_object);
 			}
 			object->backing_object = backing_object->backing_object;
 			object->backing_object_offset +=
@@ -1766,7 +1767,7 @@ vm_object_collapse(vm_object_t object)
 			KASSERT(backing_object->ref_count == 1, (
 "backing_object %p was somehow re-referenced during collapse!",
 			    backing_object));
-			VM_OBJECT_UNLOCK(backing_object);
+			VM_OBJECT_WUNLOCK(backing_object);
 			vm_object_destroy(backing_object);
 
 			object_collapses++;
@@ -1780,7 +1781,7 @@ vm_object_collapse(vm_object_t object)
 			if (object->resident_page_count != object->size &&
 			    vm_object_backing_scan(object,
 			    OBSC_TEST_ALL_SHADOWED) == 0) {
-				VM_OBJECT_UNLOCK(backing_object);
+				VM_OBJECT_WUNLOCK(backing_object);
 				break;
 			}
 
@@ -1794,7 +1795,7 @@ vm_object_collapse(vm_object_t object)
 
 			new_backing_object = backing_object->backing_object;
 			if ((object->backing_object = new_backing_object) != NULL) {
-				VM_OBJECT_LOCK(new_backing_object);
+				VM_OBJECT_WLOCK(new_backing_object);
 				LIST_INSERT_HEAD(
 				    &new_backing_object->shadow_head,
 				    object,
@@ -1802,7 +1803,7 @@ vm_object_collapse(vm_object_t object)
 				);
 				new_backing_object->shadow_count++;
 				vm_object_reference_locked(new_backing_object);
-				VM_OBJECT_UNLOCK(new_backing_object);
+				VM_OBJECT_WUNLOCK(new_backing_object);
 				object->backing_object_offset +=
 					backing_object->backing_object_offset;
 			}
@@ -1812,7 +1813,7 @@ vm_object_collapse(vm_object_t object)
 			 * its ref_count was at least 2, it will not vanish.
 			 */
 			backing_object->ref_count--;
-			VM_OBJECT_UNLOCK(backing_object);
+			VM_OBJECT_WUNLOCK(backing_object);
 			object_bypasses++;
 		}
 
@@ -1855,7 +1856,7 @@ vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
 	vm_page_t p, next;
 	int wirings;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
 	    (options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
 	    ("vm_object_page_remove: illegal options for object %p", object));
@@ -1950,7 +1951,7 @@ vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 	struct mtx *mtx, *new_mtx;
 	vm_page_t p, next;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
 	    ("vm_object_page_cache: illegal object %p", object));
 	if (object->resident_page_count == 0)
@@ -1998,7 +1999,7 @@ vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
 	vm_pindex_t pindex;
 	int rv;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	for (pindex = start; pindex < end; pindex++) {
 		m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL |
 		    VM_ALLOC_RETRY);
@@ -2059,10 +2060,10 @@ vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
 
 	if (prev_object == NULL)
 		return (TRUE);
-	VM_OBJECT_LOCK(prev_object);
+	VM_OBJECT_WLOCK(prev_object);
 	if (prev_object->type != OBJT_DEFAULT &&
 	    prev_object->type != OBJT_SWAP) {
-		VM_OBJECT_UNLOCK(prev_object);
+		VM_OBJECT_WUNLOCK(prev_object);
 		return (FALSE);
 	}
 
@@ -2077,7 +2078,7 @@ vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
 	 * pages not mapped to prev_entry may be in use anyway)
 	 */
 	if (prev_object->backing_object != NULL) {
-		VM_OBJECT_UNLOCK(prev_object);
+		VM_OBJECT_WUNLOCK(prev_object);
 		return (FALSE);
 	}
 
@@ -2087,7 +2088,7 @@ vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
 
 	if ((prev_object->ref_count > 1) &&
 	    (prev_object->size != next_pindex)) {
-		VM_OBJECT_UNLOCK(prev_object);
+		VM_OBJECT_WUNLOCK(prev_object);
 		return (FALSE);
 	}
 
@@ -2141,7 +2142,7 @@ vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
 	if (next_pindex + next_size > prev_object->size)
 		prev_object->size = next_pindex + next_size;
 
-	VM_OBJECT_UNLOCK(prev_object);
+	VM_OBJECT_WUNLOCK(prev_object);
 	return (TRUE);
 }
 
@@ -2149,7 +2150,7 @@ void
 vm_object_set_writeable_dirty(vm_object_t object)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (object->type != OBJT_VNODE)
 		return;
 	object->generation++;
diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index d69e679..7598ea3 100644
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -70,6 +70,7 @@
 #include <sys/queue.h>
 #include <sys/_lock.h>
 #include <sys/_mutex.h>
+#include <sys/_rwlock.h>
 
 #include <vm/_vm_radix.h>
 
@@ -78,9 +79,9 @@
  *
  *	vm_object_t		Virtual memory object.
  *
- *	The root of cached pages pool is protected by both the per-object mutex
+ *	The root of cached pages pool is protected by both the per-object lock
  *	and the free pages queue mutex.
- *	On insert in the cache radix trie, the per-object mutex is expected
+ *	On insert in the cache radix trie, the per-object lock is expected
  *	to be already held and the free pages queue mutex will be
  *	acquired during the operation too.
  *	On remove and lookup from the cache radix trie, only the free
@@ -91,13 +92,13 @@
  *
  * List of locks
  *	(c)	const until freed
- *	(o)	per-object mutex
+ *	(o)	per-object lock 
  *	(f)	free pages queue mutex
  *
  */
 
 struct vm_object {
-	struct mtx mtx;
+	struct rwlock lock;
 	TAILQ_ENTRY(vm_object) object_list; /* list of all objects */
 	LIST_HEAD(, vm_object) shadow_head; /* objects that this is a shadow for */
 	LIST_ENTRY(vm_object) shadow_list; /* chain of shadow objects */
@@ -205,14 +206,26 @@ extern struct vm_object kmem_object_store;
 #define	kernel_object	(&kernel_object_store)
 #define	kmem_object	(&kmem_object_store)
 
-#define	VM_OBJECT_LOCK(object)		mtx_lock(&(object)->mtx)
-#define	VM_OBJECT_LOCK_ASSERT(object, type) \
-					mtx_assert(&(object)->mtx, (type))
-#define	VM_OBJECT_SLEEP(object, wchan, pri, wmesg, timo) \
-					msleep((wchan), &(object)->mtx, (pri), \
-					    (wmesg), (timo))
-#define	VM_OBJECT_TRYLOCK(object)	mtx_trylock(&(object)->mtx)
-#define	VM_OBJECT_UNLOCK(object)	mtx_unlock(&(object)->mtx)
+#define	VM_OBJECT_ASSERT_LOCKED(object)					\
+	rw_assert(&(object)->lock, RA_LOCKED)
+#define	VM_OBJECT_ASSERT_RLOCKED(object)				\
+	rw_assert(&(object)->lock, RA_RLOCKED)
+#define	VM_OBJECT_ASSERT_WLOCKED(object)				\
+	rw_assert(&(object)->lock, RA_WLOCKED)
+#define	VM_OBJECT_RLOCK(object)						\
+	rw_rlock(&(object)->lock)
+#define	VM_OBJECT_RUNLOCK(object)					\
+	rw_runlock(&(object)->lock)
+#define	VM_OBJECT_SLEEP(object, wchan, pri, wmesg, timo)		\
+	rw_sleep((wchan), &(object)->lock, (pri), (wmesg), (timo))
+#define	VM_OBJECT_TRYRLOCK(object)					\
+	rw_try_rlock(&(object)->lock)
+#define	VM_OBJECT_TRYWLOCK(object)					\
+	rw_try_wlock(&(object)->lock)
+#define	VM_OBJECT_WLOCK(object)						\
+	rw_wlock(&(object)->lock)
+#define	VM_OBJECT_WUNLOCK(object)					\
+	rw_wunlock(&(object)->lock)
 
 /*
  *	The object must be locked or thread private.
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 47ffc31..e51a28d 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -96,6 +96,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/msgbuf.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
+#include <sys/rwlock.h>
 #include <sys/sysctl.h>
 #include <sys/vmmeter.h>
 #include <sys/vnode.h>
@@ -469,7 +470,7 @@ void
 vm_page_busy(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	KASSERT((m->oflags & VPO_BUSY) == 0,
 	    ("vm_page_busy: page already busy!!!"));
 	m->oflags |= VPO_BUSY;
@@ -484,7 +485,7 @@ void
 vm_page_flash(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (m->oflags & VPO_WANTED) {
 		m->oflags &= ~VPO_WANTED;
 		wakeup(m);
@@ -502,7 +503,7 @@ void
 vm_page_wakeup(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	KASSERT(m->oflags & VPO_BUSY, ("vm_page_wakeup: page not busy!!!"));
 	m->oflags &= ~VPO_BUSY;
 	vm_page_flash(m);
@@ -512,7 +513,7 @@ void
 vm_page_io_start(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	m->busy++;
 }
 
@@ -520,7 +521,7 @@ void
 vm_page_io_finish(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	KASSERT(m->busy > 0, ("vm_page_io_finish: page %p is not busy", m));
 	m->busy--;
 	if (m->busy == 0)
@@ -752,7 +753,7 @@ void
 vm_page_sleep(vm_page_t m, const char *msg)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (mtx_owned(vm_page_lockptr(m)))
 		vm_page_unlock(m);
 
@@ -810,7 +811,7 @@ vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
 {
 	vm_page_t neighbor;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (m->object != NULL)
 		panic("vm_page_insert: page already inserted");
 
@@ -876,7 +877,7 @@ vm_page_remove(vm_page_t m)
 		vm_page_lock_assert(m, MA_OWNED);
 	if ((object = m->object) == NULL)
 		return;
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (m->oflags & VPO_BUSY) {
 		m->oflags &= ~VPO_BUSY;
 		vm_page_flash(m);
@@ -914,7 +915,7 @@ vm_page_t
 vm_page_lookup(vm_object_t object, vm_pindex_t pindex)
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	return (vm_radix_lookup(&object->rtree, pindex));
 }
 
@@ -931,7 +932,7 @@ vm_page_find_least(vm_object_t object, vm_pindex_t pindex)
 {
 	vm_page_t m;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if ((m = TAILQ_FIRST(&object->memq)) != NULL && m->pindex < pindex)
 		m = vm_radix_lookup_ge(&object->rtree, pindex);
 	return (m);
@@ -948,7 +949,7 @@ vm_page_next(vm_page_t m)
 {
 	vm_page_t next;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if ((next = TAILQ_NEXT(m, listq)) != NULL &&
 	    next->pindex != m->pindex + 1)
 		next = NULL;
@@ -966,7 +967,7 @@ vm_page_prev(vm_page_t m)
 {
 	vm_page_t prev;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
 	    prev->pindex != m->pindex - 1)
 		prev = NULL;
@@ -1094,7 +1095,7 @@ vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
 	 * requires the object to be locked.  In contrast, removal does
 	 * not.
 	 */
-	VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(new_object);
 	KASSERT(vm_object_cache_is_empty(new_object),
 	    ("vm_page_cache_transfer: object %p has cached pages",
 	    new_object));
@@ -1135,7 +1136,7 @@ vm_page_is_cached(vm_object_t object, vm_pindex_t pindex)
 	 * page queues lock in order to prove that the specified page doesn't
 	 * exist.
 	 */
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if (__predict_true(vm_object_cache_is_empty(object)))
 		return (FALSE);
 	mtx_lock(&vm_page_queue_free_mtx);
@@ -1184,7 +1185,7 @@ vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
 	KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0),
 	    ("vm_page_alloc: inconsistent object/req"));
 	if (object != NULL)
-		VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+		VM_OBJECT_ASSERT_WLOCKED(object);
 
 	req_class = req & VM_ALLOC_CLASS_MASK;
 
@@ -1392,7 +1393,7 @@ vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
 	KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0),
 	    ("vm_page_alloc_contig: inconsistent object/req"));
 	if (object != NULL) {
-		VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+		VM_OBJECT_ASSERT_WLOCKED(object);
 		KASSERT(object->type == OBJT_PHYS,
 		    ("vm_page_alloc_contig: object %p isn't OBJT_PHYS",
 		    object));
@@ -1803,7 +1804,7 @@ vm_page_activate(vm_page_t m)
 	int queue;
 
 	vm_page_lock_assert(m, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if ((queue = m->queue) != PQ_ACTIVE) {
 		if (m->wire_count == 0 && (m->oflags & VPO_UNMANAGED) == 0) {
 			if (m->act_count < ACT_INIT)
@@ -2087,7 +2088,7 @@ vm_page_try_to_cache(vm_page_t m)
 {
 
 	vm_page_lock_assert(m, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (m->dirty || m->hold_count || m->busy || m->wire_count ||
 	    (m->oflags & (VPO_BUSY | VPO_UNMANAGED)) != 0)
 		return (0);
@@ -2110,7 +2111,7 @@ vm_page_try_to_free(vm_page_t m)
 
 	vm_page_lock_assert(m, MA_OWNED);
 	if (m->object != NULL)
-		VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+		VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (m->dirty || m->hold_count || m->busy || m->wire_count ||
 	    (m->oflags & (VPO_BUSY | VPO_UNMANAGED)) != 0)
 		return (0);
@@ -2136,7 +2137,7 @@ vm_page_cache(vm_page_t m)
 
 	vm_page_lock_assert(m, MA_OWNED);
 	object = m->object;
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	if ((m->oflags & (VPO_UNMANAGED | VPO_BUSY)) || m->busy ||
 	    m->hold_count || m->wire_count)
 		panic("vm_page_cache: attempting to cache busy page");
@@ -2241,7 +2242,7 @@ vm_page_dontneed(vm_page_t m)
 	int head;
 
 	vm_page_lock_assert(m, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	dnw = PCPU_GET(dnweight);
 	PCPU_INC(dnweight);
 
@@ -2306,7 +2307,7 @@ vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
 {
 	vm_page_t m;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT((allocflags & VM_ALLOC_RETRY) != 0,
 	    ("vm_page_grab: VM_ALLOC_RETRY is required"));
 retrylookup:
@@ -2335,9 +2336,9 @@ retrylookup:
 	m = vm_page_alloc(object, pindex, allocflags & ~(VM_ALLOC_RETRY |
 	    VM_ALLOC_IGN_SBUSY));
 	if (m == NULL) {
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		VM_WAIT;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		goto retrylookup;
 	} else if (m->valid != 0)
 		return (m);
@@ -2387,7 +2388,7 @@ vm_page_set_valid_range(vm_page_t m, int base, int size)
 {
 	int endoff, frag;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (size == 0)	/* handle degenerate case */
 		return;
 
@@ -2440,7 +2441,7 @@ vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits)
 	 * write mapped, then the page's dirty field cannot possibly be
 	 * set by a concurrent pmap operation.
 	 */
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if ((m->oflags & VPO_BUSY) == 0 && !pmap_page_is_write_mapped(m))
 		m->dirty &= ~pagebits;
 	else {
@@ -2494,7 +2495,7 @@ vm_page_set_validclean(vm_page_t m, int base, int size)
 	vm_page_bits_t oldvalid, pagebits;
 	int endoff, frag;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (size == 0)	/* handle degenerate case */
 		return;
 
@@ -2584,7 +2585,7 @@ vm_page_set_invalid(vm_page_t m, int base, int size)
 {
 	vm_page_bits_t bits;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	KASSERT((m->oflags & VPO_BUSY) == 0,
 	    ("vm_page_set_invalid: page %p is busy", m));
 	bits = vm_page_bits(base, size);
@@ -2613,7 +2614,7 @@ vm_page_zero_invalid(vm_page_t m, boolean_t setvalid)
 	int b;
 	int i;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	/*
 	 * Scan the valid bits looking for invalid sections that
 	 * must be zerod.  Invalid sub-DEV_BSIZE'd areas ( where the
@@ -2652,7 +2653,7 @@ vm_page_is_valid(vm_page_t m, int base, int size)
 {
 	vm_page_bits_t bits;
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	bits = vm_page_bits(base, size);
 	if (m->valid && ((m->valid & bits) == bits))
 		return 1;
@@ -2667,7 +2668,7 @@ void
 vm_page_test_dirty(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (m->dirty != VM_PAGE_BITS_ALL && pmap_is_modified(m))
 		vm_page_dirty(m);
 }
@@ -2721,7 +2722,7 @@ vm_page_cowfault(vm_page_t m)
 
 	vm_page_lock_assert(m, MA_OWNED);
 	object = m->object;
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT(object->paging_in_progress != 0,
 	    ("vm_page_cowfault: object %p's paging-in-progress count is zero.",
 	    object)); 
@@ -2734,9 +2735,9 @@ vm_page_cowfault(vm_page_t m)
 	if (mnew == NULL) {
 		vm_page_insert(m, object, pindex);
 		vm_page_unlock(m);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		VM_WAIT;
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (m == vm_page_lookup(object, pindex)) {
 			vm_page_lock(m);
 			goto retry_alloc;
@@ -2793,11 +2794,11 @@ vm_page_cowsetup(vm_page_t m)
 	vm_page_lock_assert(m, MA_OWNED);
 	if ((m->flags & PG_FICTITIOUS) != 0 ||
 	    (m->oflags & VPO_UNMANAGED) != 0 ||
-	    m->cow == USHRT_MAX - 1 || !VM_OBJECT_TRYLOCK(m->object))
+	    m->cow == USHRT_MAX - 1 || !VM_OBJECT_TRYWLOCK(m->object))
 		return (EBUSY);
 	m->cow++;
 	pmap_remove_write(m);
-	VM_OBJECT_UNLOCK(m->object);
+	VM_OBJECT_WUNLOCK(m->object);
 	return (0);
 }
 
@@ -2814,7 +2815,7 @@ vm_page_object_lock_assert(vm_page_t m)
 	 * here.
 	 */
 	if (m->object != NULL && (m->oflags & VPO_BUSY) == 0)
-		VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+		VM_OBJECT_ASSERT_WLOCKED(m->object);
 }
 #endif
 
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index ac593a4..c0a0da4 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -92,6 +92,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/signalvar.h>
 #include <sys/vnode.h>
 #include <sys/vmmeter.h>
+#include <sys/rwlock.h>
 #include <sys/sx.h>
 #include <sys/sysctl.h>
 
@@ -248,7 +249,7 @@ vm_pageout_init_marker(vm_page_t marker, u_short queue)
 /*
  * vm_pageout_fallback_object_lock:
  * 
- * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is
+ * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is
  * known to have failed and page queue must be either PQ_ACTIVE or
  * PQ_INACTIVE.  To avoid lock order violation, unlock the page queues
  * while locking the vm object.  Use marker page to detect page queue
@@ -276,7 +277,7 @@ vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
 	TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, pageq);
 	vm_pagequeue_unlock(pq);
 	vm_page_unlock(m);
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	vm_page_lock(m);
 	vm_pagequeue_lock(pq);
 
@@ -346,7 +347,7 @@ vm_pageout_clean(vm_page_t m)
 
 	vm_page_lock_assert(m, MA_OWNED);
 	object = m->object;
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	/*
 	 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
@@ -484,7 +485,7 @@ vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
 	int numpagedout = 0;
 	int i, runlen;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	/*
 	 * Initiate I/O.  Bump the vm_page_t->busy counter and
@@ -595,12 +596,12 @@ vm_pageout_launder(int queue, int tries, vm_paddr_t low, vm_paddr_t high)
 			continue;
 		}
 		object = m->object;
-		if ((!VM_OBJECT_TRYLOCK(object) &&
+		if ((!VM_OBJECT_TRYWLOCK(object) &&
 		    (!vm_pageout_fallback_object_lock(m, &next) ||
 		    m->hold_count != 0)) || (m->oflags & VPO_BUSY) != 0 ||
 		    m->busy != 0) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			continue;
 		}
 		vm_page_test_dirty(m);
@@ -609,19 +610,19 @@ vm_pageout_launder(int queue, int tries, vm_paddr_t low, vm_paddr_t high)
 		if (m->dirty != 0) {
 			vm_page_unlock(m);
 			if (tries == 0 || (object->flags & OBJ_DEAD) != 0) {
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				continue;
 			}
 			if (object->type == OBJT_VNODE) {
 				vm_pagequeue_unlock(pq);
 				vp = object->handle;
 				vm_object_reference_locked(object);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				(void)vn_start_write(vp, &mp, V_WAIT);
 				vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
-				VM_OBJECT_LOCK(object);
+				VM_OBJECT_WLOCK(object);
 				vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				VOP_UNLOCK(vp, 0);
 				vm_object_deallocate(object);
 				vn_finished_write(mp);
@@ -632,7 +633,7 @@ vm_pageout_launder(int queue, int tries, vm_paddr_t low, vm_paddr_t high)
 				m_tmp = m;
 				vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC,
 				    0, NULL, NULL);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				return (TRUE);
 			}
 		} else {
@@ -644,7 +645,7 @@ vm_pageout_launder(int queue, int tries, vm_paddr_t low, vm_paddr_t high)
 			vm_page_cache(m);
 			vm_page_unlock(m);
 		}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	vm_pagequeue_unlock(pq);
 	return (FALSE);
@@ -713,13 +714,13 @@ vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
 	vm_page_t p;
 	int actcount, remove_mode;
 
-	VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(first_object);
 	if ((first_object->flags & OBJ_FICTITIOUS) != 0)
 		return;
 	for (object = first_object;; object = backing_object) {
 		if (pmap_resident_count(pmap) <= desired)
 			goto unlock_return;
-		VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+		VM_OBJECT_ASSERT_WLOCKED(object);
 		if ((object->flags & OBJ_UNMANAGED) != 0 ||
 		    object->paging_in_progress != 0)
 			goto unlock_return;
@@ -775,13 +776,13 @@ vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
 		}
 		if ((backing_object = object->backing_object) == NULL)
 			goto unlock_return;
-		VM_OBJECT_LOCK(backing_object);
+		VM_OBJECT_WLOCK(backing_object);
 		if (object != first_object)
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 	}
 unlock_return:
 	if (object != first_object)
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 }
 
 /*
@@ -811,15 +812,15 @@ vm_pageout_map_deactivate_pages(map, desired)
 	while (tmpe != &map->header) {
 		if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
 			obj = tmpe->object.vm_object;
-			if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) {
+			if (obj != NULL && VM_OBJECT_TRYWLOCK(obj)) {
 				if (obj->shadow_count <= 1 &&
 				    (bigobj == NULL ||
 				     bigobj->resident_page_count < obj->resident_page_count)) {
 					if (bigobj != NULL)
-						VM_OBJECT_UNLOCK(bigobj);
+						VM_OBJECT_WUNLOCK(bigobj);
 					bigobj = obj;
 				} else
-					VM_OBJECT_UNLOCK(obj);
+					VM_OBJECT_WUNLOCK(obj);
 			}
 		}
 		if (tmpe->wired_count > 0)
@@ -829,7 +830,7 @@ vm_pageout_map_deactivate_pages(map, desired)
 
 	if (bigobj != NULL) {
 		vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
-		VM_OBJECT_UNLOCK(bigobj);
+		VM_OBJECT_WUNLOCK(bigobj);
 	}
 	/*
 	 * Next, hunt around for other pages to deactivate.  We actually
@@ -842,9 +843,9 @@ vm_pageout_map_deactivate_pages(map, desired)
 		if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
 			obj = tmpe->object.vm_object;
 			if (obj != NULL) {
-				VM_OBJECT_LOCK(obj);
+				VM_OBJECT_WLOCK(obj);
 				vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
-				VM_OBJECT_UNLOCK(obj);
+				VM_OBJECT_WUNLOCK(obj);
 			}
 		}
 		tmpe = tmpe->next;
@@ -963,10 +964,10 @@ vm_pageout_scan(int pass)
 			continue;
 		}
 		object = m->object;
-		if (!VM_OBJECT_TRYLOCK(object) &&
+		if (!VM_OBJECT_TRYWLOCK(object) &&
 		    !vm_pageout_fallback_object_lock(m, &next)) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			continue;
 		}
 
@@ -979,7 +980,7 @@ vm_pageout_scan(int pass)
 		 */
 		if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			addl_page_shortage++;
 			continue;
 		}
@@ -1016,7 +1017,7 @@ vm_pageout_scan(int pass)
 			vm_page_activate(m);
 			vm_page_unlock(m);
 			m->act_count += actcount + ACT_ADVANCE;
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			goto relock_queues;
 		}
 
@@ -1032,13 +1033,13 @@ vm_pageout_scan(int pass)
 			vm_page_activate(m);
 			vm_page_unlock(m);
 			m->act_count += actcount + ACT_ADVANCE + 1;
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			goto relock_queues;
 		}
 
 		if (m->hold_count != 0) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 
 			/*
 			 * Held pages are essentially stuck in the
@@ -1122,7 +1123,7 @@ vm_pageout_scan(int pass)
 			if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
 				vm_pagequeue_lock(pq);
 				vm_page_unlock(m);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				queues_locked = TRUE;
 				vm_page_requeue_locked(m);
 				goto relock_queues;
@@ -1165,17 +1166,17 @@ vm_pageout_scan(int pass)
 				KASSERT(mp != NULL,
 				    ("vp %p with NULL v_mount", vp));
 				vm_object_reference_locked(object);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK,
 				    curthread)) {
-					VM_OBJECT_LOCK(object);
+					VM_OBJECT_WLOCK(object);
 					++pageout_lock_miss;
 					if (object->flags & OBJ_MIGHTBEDIRTY)
 						vnodes_skipped++;
 					vp = NULL;
 					goto unlock_and_continue;
 				}
-				VM_OBJECT_LOCK(object);
+				VM_OBJECT_WLOCK(object);
 				vm_page_lock(m);
 				vm_pagequeue_lock(pq);
 				queues_locked = TRUE;
@@ -1236,7 +1237,7 @@ vm_pageout_scan(int pass)
 			}
 unlock_and_continue:
 			vm_page_lock_assert(m, MA_NOTOWNED);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			if (mp != NULL) {
 				if (queues_locked) {
 					vm_pagequeue_unlock(pq);
@@ -1251,7 +1252,7 @@ unlock_and_continue:
 			goto relock_queues;
 		}
 		vm_page_unlock(m);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 relock_queues:
 		if (!queues_locked) {
 			vm_pagequeue_lock(pq);
@@ -1299,9 +1300,9 @@ relock_queues:
 			continue;
 		}
 		object = m->object;
-		if (!VM_OBJECT_TRYLOCK(object) &&
+		if (!VM_OBJECT_TRYWLOCK(object) &&
 		    !vm_pageout_fallback_object_lock(m, &next)) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			vm_page_unlock(m);
 			m = next;
 			continue;
@@ -1314,7 +1315,7 @@ relock_queues:
 		    (m->oflags & VPO_BUSY) ||
 		    (m->hold_count != 0)) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			vm_page_requeue_locked(m);
 			m = next;
 			continue;
@@ -1375,7 +1376,7 @@ relock_queues:
 				vm_page_requeue_locked(m);
 		}
 		vm_page_unlock(m);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		m = next;
 	}
 	vm_pagequeue_unlock(pq);
@@ -1571,9 +1572,9 @@ vm_pageout_page_stats(void)
 			continue;
 		}
 		object = m->object;
-		if (!VM_OBJECT_TRYLOCK(object) &&
+		if (!VM_OBJECT_TRYWLOCK(object) &&
 		    !vm_pageout_fallback_object_lock(m, &next)) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			vm_page_unlock(m);
 			m = next;
 			continue;
@@ -1586,7 +1587,7 @@ vm_pageout_page_stats(void)
 		    (m->oflags & VPO_BUSY) ||
 		    (m->hold_count != 0)) {
 			vm_page_unlock(m);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			vm_page_requeue_locked(m);
 			m = next;
 			continue;
@@ -1625,7 +1626,7 @@ vm_pageout_page_stats(void)
 			}
 		}
 		vm_page_unlock(m);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		m = next;
 	}
 	vm_pagequeue_unlock(pq);
diff --git a/sys/vm/vm_pager.c b/sys/vm/vm_pager.c
index 6ed64ea..a991e41 100644
--- a/sys/vm/vm_pager.c
+++ b/sys/vm/vm_pager.c
@@ -74,6 +74,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/buf.h>
 #include <sys/ucred.h>
 #include <sys/malloc.h>
+#include <sys/rwlock.h>
 
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -248,7 +249,7 @@ vm_pager_deallocate(object)
 	vm_object_t object;
 {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	(*pagertab[object->type]->pgo_dealloc) (object);
 }
 
@@ -272,13 +273,13 @@ vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 
 	TAILQ_FOREACH(object, pg_list, pager_object_list) {
 		if (object->handle == handle) {
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			if ((object->flags & OBJ_DEAD) == 0) {
 				vm_object_reference_locked(object);
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				break;
 			}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		}
 	}
 	return (object);
diff --git a/sys/vm/vm_pager.h b/sys/vm/vm_pager.h
index bb7a5ec..b5d923c 100644
--- a/sys/vm/vm_pager.h
+++ b/sys/vm/vm_pager.h
@@ -124,7 +124,7 @@ vm_pager_get_pages(
 ) {
 	int r;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	r = (*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage);
 	if (r == VM_PAGER_OK && m[reqpage]->valid != VM_PAGE_BITS_ALL) {
 		vm_page_zero_invalid(m[reqpage], TRUE);
@@ -141,7 +141,7 @@ vm_pager_put_pages(
 	int *rtvals
 ) {
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	(*pagertab[object->type]->pgo_putpages)
 	    (object, m, count, flags, rtvals);
 }
@@ -165,7 +165,7 @@ vm_pager_has_page(
 ) {
 	boolean_t ret;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	ret = (*pagertab[object->type]->pgo_haspage)
 	    (object, offset, before, after);
 	return (ret);
@@ -188,7 +188,7 @@ static __inline void
 vm_pager_page_unswapped(vm_page_t m)
 {
 
-	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (pagertab[m->object->type]->pgo_pageunswapped)
 		(*pagertab[m->object->type]->pgo_pageunswapped)(m);
 }
diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c
index eb14411..bb071bd 100644
--- a/sys/vm/vm_reserv.c
+++ b/sys/vm/vm_reserv.c
@@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <sys/mutex.h>
 #include <sys/queue.h>
+#include <sys/rwlock.h>
 #include <sys/sbuf.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
@@ -312,7 +313,7 @@ vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
 	int i, index, n;
 
 	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	KASSERT(npages != 0, ("vm_reserv_alloc_contig: npages is 0"));
 
 	/*
@@ -485,7 +486,7 @@ vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex)
 	vm_reserv_t rv;
 
 	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	/*
 	 * Is a reservation fundamentally impossible?
@@ -849,7 +850,7 @@ vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
 {
 	vm_reserv_t rv;
 
-	VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(new_object);
 	rv = vm_reserv_from_page(m);
 	if (rv->object == old_object) {
 		mtx_lock(&vm_page_queue_free_mtx);
diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index 4c678f4..5e331ee 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -63,6 +63,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/vmmeter.h>
 #include <sys/limits.h>
 #include <sys/conf.h>
+#include <sys/rwlock.h>
 #include <sys/sf_buf.h>
 
 #include <machine/atomic.h>
@@ -109,9 +110,9 @@ vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
 		return (0);
 
 	while ((object = vp->v_object) != NULL) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if (!(object->flags & OBJ_DEAD)) {
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			return (0);
 		}
 		VOP_UNLOCK(vp, 0);
@@ -135,9 +136,9 @@ vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
 	 * Dereference the reference we just created.  This assumes
 	 * that the object is associated with the vp.
 	 */
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	object->ref_count--;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	vrele(vp);
 
 	KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
@@ -154,7 +155,7 @@ vnode_destroy_vobject(struct vnode *vp)
 	if (obj == NULL)
 		return;
 	ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
-	VM_OBJECT_LOCK(obj);
+	VM_OBJECT_WLOCK(obj);
 	if (obj->ref_count == 0) {
 		/*
 		 * vclean() may be called twice. The first time
@@ -167,13 +168,13 @@ vnode_destroy_vobject(struct vnode *vp)
 		if ((obj->flags & OBJ_DEAD) == 0)
 			vm_object_terminate(obj);
 		else
-			VM_OBJECT_UNLOCK(obj);
+			VM_OBJECT_WUNLOCK(obj);
 	} else {
 		/*
 		 * Woe to the process that tries to page now :-).
 		 */
 		vm_pager_deallocate(obj);
-		VM_OBJECT_UNLOCK(obj);
+		VM_OBJECT_WUNLOCK(obj);
 	}
 	vp->v_object = NULL;
 }
@@ -206,7 +207,7 @@ vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 	 */
 retry:
 	while ((object = vp->v_object) != NULL) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		if ((object->flags & OBJ_DEAD) == 0)
 			break;
 		vm_object_set_flag(object, OBJ_DISCONNECTWNT);
@@ -239,7 +240,7 @@ retry:
 		VI_UNLOCK(vp);
 	} else {
 		object->ref_count++;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	vref(vp);
 	return (object);
@@ -259,7 +260,7 @@ vnode_pager_dealloc(object)
 	if (vp == NULL)
 		panic("vnode_pager_dealloc: pager already dealloced");
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	vm_object_pip_wait(object, "vnpdea");
 	refs = object->ref_count;
 
@@ -278,10 +279,10 @@ vnode_pager_dealloc(object)
 	}
 	vp->v_object = NULL;
 	VOP_UNSET_TEXT(vp);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	while (refs-- > 0)
 		vunref(vp);
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 }
 
 static boolean_t
@@ -299,7 +300,7 @@ vnode_pager_haspage(object, pindex, before, after)
 	int bsize;
 	int pagesperblock, blocksperpage;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	/*
 	 * If no vp or vp is doomed or marked transparent to VM, we do not
 	 * have the page.
@@ -322,9 +323,9 @@ vnode_pager_haspage(object, pindex, before, after)
 		blocksperpage = (PAGE_SIZE / bsize);
 		reqblock = pindex * blocksperpage;
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (err)
 		return TRUE;
 	if (bn == -1)
@@ -379,12 +380,12 @@ vnode_pager_setsize(vp, nsize)
 	if ((object = vp->v_object) == NULL)
 		return;
 /* 	ASSERT_VOP_ELOCKED(vp, "vnode_pager_setsize and not locked vnode"); */
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (nsize == object->un_pager.vnp.vnp_size) {
 		/*
 		 * Hasn't changed size
 		 */
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return;
 	}
 	nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
@@ -445,7 +446,7 @@ vnode_pager_setsize(vp, nsize)
 	}
 	object->un_pager.vnp.vnp_size = nsize;
 	object->size = nobjsize;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 }
 
 /*
@@ -568,9 +569,9 @@ vnode_pager_input_smlfs(object, m)
 			bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
 		KASSERT((m->dirty & bits) == 0,
 		    ("vnode_pager_input_smlfs: page %p is dirty", m));
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		m->valid |= bits;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 	}
 	sf_buf_free(sf);
 	if (error) {
@@ -594,7 +595,7 @@ vnode_pager_input_old(object, m)
 	struct sf_buf *sf;
 	struct vnode *vp;
 
-	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 	error = 0;
 
 	/*
@@ -607,7 +608,7 @@ vnode_pager_input_old(object, m)
 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
 		vp = object->handle;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 
 		/*
 		 * Allocate a kernel virtual address and initialize so that
@@ -637,7 +638,7 @@ vnode_pager_input_old(object, m)
 		}
 		sf_buf_free(sf);
 
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 	}
 	KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
 	if (!error)
@@ -669,11 +670,11 @@ vnode_pager_getpages(object, m, count, reqpage)
 	int bytes = count * PAGE_SIZE;
 
 	vp = object->handle;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	rtval = VOP_GETPAGES(vp, m, bytes, reqpage, 0);
 	KASSERT(rtval != EOPNOTSUPP,
 	    ("vnode_pager: FS getpages not implemented\n"));
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	return rtval;
 }
 
@@ -723,7 +724,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	 */
 	error = VOP_BMAP(vp, foff / bsize, &bo, &reqblock, NULL, NULL);
 	if (error == EOPNOTSUPP) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		
 		for (i = 0; i < count; i++)
 			if (i != reqpage) {
@@ -734,17 +735,17 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 		PCPU_INC(cnt.v_vnodein);
 		PCPU_INC(cnt.v_vnodepgsin);
 		error = vnode_pager_input_old(object, m[reqpage]);
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return (error);
 	} else if (error != 0) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		for (i = 0; i < count; i++)
 			if (i != reqpage) {
 				vm_page_lock(m[i]);
 				vm_page_free(m[i]);
 				vm_page_unlock(m[i]);
 			}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return (VM_PAGER_ERROR);
 
 		/*
@@ -754,14 +755,14 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 		 */
 	} else if ((PAGE_SIZE / bsize) > 1 &&
 	    (vp->v_mount->mnt_stat.f_type != nfs_mount_type)) {
-		VM_OBJECT_LOCK(object);
+		VM_OBJECT_WLOCK(object);
 		for (i = 0; i < count; i++)
 			if (i != reqpage) {
 				vm_page_lock(m[i]);
 				vm_page_free(m[i]);
 				vm_page_unlock(m[i]);
 			}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		PCPU_INC(cnt.v_vnodein);
 		PCPU_INC(cnt.v_vnodepgsin);
 		return vnode_pager_input_smlfs(object, m[reqpage]);
@@ -772,7 +773,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	 * clean up and return.  Otherwise we have to re-read the
 	 * media.
 	 */
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (m[reqpage]->valid == VM_PAGE_BITS_ALL) {
 		for (i = 0; i < count; i++)
 			if (i != reqpage) {
@@ -780,7 +781,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 				vm_page_free(m[i]);
 				vm_page_unlock(m[i]);
 			}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return VM_PAGER_OK;
 	} else if (reqblock == -1) {
 		pmap_zero_page(m[reqpage]);
@@ -793,11 +794,11 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 				vm_page_free(m[i]);
 				vm_page_unlock(m[i]);
 			}
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return (VM_PAGER_OK);
 	}
 	m[reqpage]->valid = 0;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	/*
 	 * here on direct device I/O
@@ -810,18 +811,18 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	for (first = 0, i = 0; i < count; i = runend) {
 		if (vnode_pager_addr(vp, IDX_TO_OFF(m[i]->pindex), &firstaddr,
 		    &runpg) != 0) {
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			for (; i < count; i++)
 				if (i != reqpage) {
 					vm_page_lock(m[i]);
 					vm_page_free(m[i]);
 					vm_page_unlock(m[i]);
 				}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			return (VM_PAGER_ERROR);
 		}
 		if (firstaddr == -1) {
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
 				panic("vnode_pager_getpages: unexpected missing page: firstaddr: %jd, foff: 0x%jx%08jx, vnp_size: 0x%jx%08jx",
 				    (intmax_t)firstaddr, (uintmax_t)(foff >> 32),
@@ -833,29 +834,29 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 			vm_page_lock(m[i]);
 			vm_page_free(m[i]);
 			vm_page_unlock(m[i]);
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 			runend = i + 1;
 			first = runend;
 			continue;
 		}
 		runend = i + runpg;
 		if (runend <= reqpage) {
-			VM_OBJECT_LOCK(object);
+			VM_OBJECT_WLOCK(object);
 			for (j = i; j < runend; j++) {
 				vm_page_lock(m[j]);
 				vm_page_free(m[j]);
 				vm_page_unlock(m[j]);
 			}
-			VM_OBJECT_UNLOCK(object);
+			VM_OBJECT_WUNLOCK(object);
 		} else {
 			if (runpg < (count - first)) {
-				VM_OBJECT_LOCK(object);
+				VM_OBJECT_WLOCK(object);
 				for (i = first + runpg; i < count; i++) {
 					vm_page_lock(m[i]);
 					vm_page_free(m[i]);
 					vm_page_unlock(m[i]);
 				}
-				VM_OBJECT_UNLOCK(object);
+				VM_OBJECT_WUNLOCK(object);
 				count = first + runpg;
 			}
 			break;
@@ -946,7 +947,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	pbrelbo(bp);
 	relpbuf(bp, &vnode_pbuf_freecnt);
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	for (i = 0, tfoff = foff; i < count; i++, tfoff = nextoff) {
 		vm_page_t mt;
 
@@ -983,7 +984,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 		if (i != reqpage)
 			vm_page_readahead_finish(mt);
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	if (error) {
 		printf("vnode_pager_getpages: I/O read error\n");
 	}
@@ -1029,11 +1030,11 @@ vnode_pager_putpages(object, m, count, sync, rtvals)
 	 * Call device-specific putpages function
 	 */
 	vp = object->handle;
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
 	KASSERT(rtval != EOPNOTSUPP, 
 	    ("vnode_pager: stale FS putpages\n"));
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 }
 
 
@@ -1095,7 +1096,7 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 	 * We do not under any circumstances truncate the valid bits, as
 	 * this will screw up bogus page replacement.
 	 */
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
 		if (object->un_pager.vnp.vnp_size > poffset) {
 			int pgoff;
@@ -1127,7 +1128,7 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 			}
 		}
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 
 	/*
 	 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
@@ -1181,7 +1182,7 @@ vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
 	if (written == 0)
 		return;
 	obj = ma[0]->object;
-	VM_OBJECT_LOCK(obj);
+	VM_OBJECT_WLOCK(obj);
 	for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
 		if (pos < trunc_page(written)) {
 			rtvals[i] = VM_PAGER_OK;
@@ -1192,7 +1193,7 @@ vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
 			vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
 		}
 	}
-	VM_OBJECT_UNLOCK(obj);
+	VM_OBJECT_WUNLOCK(obj);
 }
 
 void
@@ -1202,9 +1203,9 @@ vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
 	struct vnode *vp;
 	vm_ooffset_t old_wm;
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 	if (object->type != OBJT_VNODE) {
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return;
 	}
 	old_wm = object->un_pager.vnp.writemappings;
@@ -1221,7 +1222,7 @@ vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
 		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
 		    __func__, vp, vp->v_writecount);
 	}
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 }
 
 void
@@ -1232,14 +1233,14 @@ vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
 	struct mount *mp;
 	vm_offset_t inc;
 
-	VM_OBJECT_LOCK(object);
+	VM_OBJECT_WLOCK(object);
 
 	/*
 	 * First, recheck the object type to account for the race when
 	 * the vnode is reclaimed.
 	 */
 	if (object->type != OBJT_VNODE) {
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return;
 	}
 
@@ -1250,13 +1251,13 @@ vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
 	inc = end - start;
 	if (object->un_pager.vnp.writemappings != inc) {
 		object->un_pager.vnp.writemappings -= inc;
-		VM_OBJECT_UNLOCK(object);
+		VM_OBJECT_WUNLOCK(object);
 		return;
 	}
 
 	vp = object->handle;
 	vhold(vp);
-	VM_OBJECT_UNLOCK(object);
+	VM_OBJECT_WUNLOCK(object);
 	mp = NULL;
 	vn_start_write(vp, &mp, V_WAIT);
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);