diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
index 0bf07c7..46c2072 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -50,6 +50,8 @@
 #include <rte_mempool.h>
 #include <rte_mbuf.h>
 
+#define VHOST_MEMORY_MAX_NREGIONS 8
+
 /* Used to indicate that the device is running on a data core */
 #define VIRTIO_DEV_RUNNING 1
 
diff --git a/lib/librte_vhost/vhost-net.h b/lib/librte_vhost/vhost-net.h
index 3f18f25..94b359f 100644
--- a/lib/librte_vhost/vhost-net.h
+++ b/lib/librte_vhost/vhost-net.h
@@ -43,8 +43,6 @@
 
 #include "rte_virtio_net.h"
 
-#define VHOST_MEMORY_MAX_NREGIONS 8
-
 extern struct vhost_net_device_ops const *ops;
 
 /* Macros for printing using RTE_LOG */
diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.h b/lib/librte_vhost/vhost_user/vhost-net-user.h
index 7e6cda4..91e8fc3 100644
--- a/lib/librte_vhost/vhost_user/vhost-net-user.h
+++ b/lib/librte_vhost/vhost_user/vhost-net-user.h
@@ -37,6 +37,7 @@
 #include <stdint.h>
 #include <linux/vhost.h>
 
+#include "rte_virtio_net.h"
 #include "fd_man.h"
 
 struct vhost_server {
@@ -47,8 +48,6 @@ struct vhost_server {
 
 /* refer to hw/virtio/vhost-user.c */
 
-#define VHOST_MEMORY_MAX_NREGIONS    8
-
 typedef enum VhostUserRequest {
 	VHOST_USER_NONE = 0,
 	VHOST_USER_GET_FEATURES = 1,
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
index 6601fcd..3481eb8 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -36,7 +36,11 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
+#include <rte_common.h>
 #include <rte_log.h>
 
 #include "virtio-net.h"
@@ -44,13 +48,59 @@
 #include "vhost-net-user.h"
 #include "vhost-net.h"
 
+struct orig_region_map {
+	int fd;
+	uint64_t mapped_address;
+	uint64_t mapped_size;
+	uint64_t blksz;
+};
+
+#define orig_region(ptr, nregions) ((struct orig_region_map *)RTE_PTR_ADD(ptr, \
+		sizeof(struct virtio_memory) + \
+		sizeof(struct virtio_memory_regions) * (nregions)))
+
+static uint64_t
+get_blk_size(int fd)
+{
+	struct stat stat;
+
+	fstat(fd, &stat);
+	return (uint64_t)stat.st_blksize;
+}
+
 int
 user_set_mem_table(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 {
-	unsigned int idx;
 	struct VhostUserMemory memory = pmsg->payload.memory;
 	struct virtio_memory_regions regions[VHOST_MEMORY_MAX_NREGIONS];
-	uint64_t mapped_address, base_address = 0;
+	uint64_t mapped_address, mapped_size, base_address = 0;
+	struct virtio_net *dev;
+	unsigned int idx = 0;
+	struct orig_region_map tmp[VHOST_MEMORY_MAX_NREGIONS] = {
+		[0 ... VHOST_MEMORY_MAX_NREGIONS - 1] = { 0 } };
+	struct orig_region_map *region;
+	uint64_t alignment;
+	int ret;
+
+	/* unmap old memory regions one by one*/
+	dev = get_device(ctx);
+	if (dev->mem) {
+		region = orig_region(dev->mem, dev->mem->nregions);
+		for (idx = 0; idx < dev->mem->nregions; idx++) {
+			if (region[idx].mapped_address) {
+				alignment = region[idx].blksz;
+				printf("Freeing %p\n",
+					(void *)(uintptr_t)region[idx].mapped_address);
+				ret = munmap((void *)RTE_ALIGN_FLOOR(region[idx].mapped_address, alignment),
+					RTE_ALIGN_CEIL(region[idx].mapped_size, alignment));
+				printf("munmap ret= %d\n", ret);
+				printf("close file %d\n", region[idx].fd);
+				close(region[idx].fd);
+			}
+		}
+		free(dev->mem);
+		dev->mem = NULL;
+	}
 
 	for (idx = 0; idx < memory.nregions; idx++) {
 		if (memory.regions[idx].guest_phys_addr == 0)
@@ -73,22 +123,30 @@ user_set_mem_table(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 			memory.regions[idx].userspace_addr;
 
 		/* This is ugly */
+		mapped_size = regions[idx].memory_size +
+			memory.regions[idx].mmap_offset;
 		mapped_address = (uint64_t)(uintptr_t)mmap(NULL,
-			regions[idx].memory_size +
-				memory.regions[idx].mmap_offset,
+			mapped_size,
 			PROT_READ | PROT_WRITE, MAP_SHARED,
 			pmsg->fds[idx],
 			0);
+
 		RTE_LOG(INFO, VHOST_CONFIG,
-			"mapped region %d to %p\n",
-			idx, (void *)mapped_address);
+			"mapped region %d fd:%d to %p sz:0x%"PRIx64" off:0x%"PRIx64"\n",
+			idx, pmsg->fds[idx], (void *)mapped_address,
+			mapped_size, memory.regions[idx].mmap_offset);
 
 		if (mapped_address == (uint64_t)(uintptr_t)MAP_FAILED) {
 			RTE_LOG(ERR, VHOST_CONFIG,
 				"mmap qemu guest failed.\n");
-			return -1;
+			goto err;
 		}
 
+		tmp[idx].mapped_address = mapped_address;
+		tmp[idx].mapped_size = mapped_size;
+		tmp[idx].blksz = get_blk_size(pmsg->fds[idx]);
+		tmp[idx].fd = pmsg->fds[idx];
+
 		mapped_address +=  memory.regions[idx].mmap_offset;
 
 		regions[idx].address_offset = mapped_address -
@@ -100,10 +158,45 @@ user_set_mem_table(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 			(void *)(uintptr_t)regions[idx].userspace_address,
 			 regions[idx].memory_size);
 	}
+
 	ops->set_mem_table(ctx, regions, memory.nregions);
+
+	if (dev->mem) {
+		void *tmp_mem;
+		tmp_mem = realloc(dev->mem,
+			sizeof(struct virtio_memory) +
+			sizeof(struct virtio_memory_regions) * memory.nregions +
+			sizeof(struct orig_region_map) * memory.nregions);
+		if (tmp_mem == NULL)
+			goto err_realloc;
+
+		dev->mem = tmp_mem;
+		region = orig_region(dev->mem, memory.nregions);
+		for (idx = 0; idx < memory.nregions; idx++) {
+			region[idx].mapped_address = tmp[idx].mapped_address;
+			region[idx].mapped_size = tmp[idx].mapped_size;
+			region[idx].blksz = tmp[idx].blksz;
+			region[idx].fd = tmp[idx].fd;
+		}
+	} else
+		goto err_set_mem_table;
+
 	return 0;
-}
 
+err_realloc:
+	free(dev->mem);
+err_set_mem_table:
+err:
+	while (idx--) {
+		alignment = tmp[idx].blksz;
+		munmap((void *)RTE_ALIGN_FLOOR(
+			tmp[idx].mapped_address, alignment),
+			RTE_ALIGN_CEIL(tmp[idx].mapped_size, alignment));
+		close(tmp[idx].fd);
+	}
+	dev->mem = NULL;
+	return -1;
+}
 
 static int
 virtio_is_ready(struct virtio_net *dev)
