diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -1356,7 +1356,7 @@
 {
 	vm_object_t object;
 	vm_page_t m;
-	vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
+	vm_ooffset_t max_offset, next_offset, poffset, prev_offset;
 	struct uio auio;
 	struct iovec aiov;
 	off_t prev_resid, wrsz;
@@ -1431,15 +1431,15 @@
 	auio.uio_segflg = UIO_NOCOPY;
 	auio.uio_rw = UIO_WRITE;
 	auio.uio_td = NULL;
-	maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
+	max_offset = roundup2(poffset + maxsize, DEV_BSIZE);
 
-	for (prev_offset = poffset; prev_offset < maxblksz;) {
+	for (prev_offset = poffset; prev_offset < max_offset;) {
 		/* Skip clean blocks. */
-		for (in_hole = true; in_hole && prev_offset < maxblksz;) {
+		for (in_hole = true; in_hole && prev_offset < max_offset;) {
 			m = ma[OFF_TO_IDX(prev_offset - poffset)];
 			for (i = vn_off2bidx(prev_offset);
 			    i < sizeof(vm_page_bits_t) * NBBY &&
-			    prev_offset < maxblksz; i++) {
+			    prev_offset < max_offset; i++) {
 				if (vn_dirty_blk(m, prev_offset)) {
 					in_hole = false;
 					break;
@@ -1451,11 +1451,11 @@
 			goto write_done;
 
 		/* Find longest run of dirty blocks. */
-		for (next_offset = prev_offset; next_offset < maxblksz;) {
+		for (next_offset = prev_offset; next_offset < max_offset;) {
 			m = ma[OFF_TO_IDX(next_offset - poffset)];
 			for (i = vn_off2bidx(next_offset);
 			    i < sizeof(vm_page_bits_t) * NBBY &&
-			    next_offset < maxblksz; i++) {
+			    next_offset < max_offset; i++) {
 				if (!vn_dirty_blk(m, next_offset))
 					goto start_write;
 				next_offset += DEV_BSIZE;
@@ -1464,12 +1464,13 @@
 start_write:
 		if (next_offset > poffset + maxsize)
 			next_offset = poffset + maxsize;
+		if (prev_offset == next_offset)
+			goto write_done;
 
 		/*
 		 * Getting here requires finding a dirty block in the
 		 * 'skip clean blocks' loop.
 		 */
-		MPASS(prev_offset < next_offset);
 
 		aiov.iov_base = NULL;
 		auio.uio_iovcnt = 1;