diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 01d554758..2883f20af 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -41,6 +41,7 @@
 #include "mlx5_autoconf.h"
 #include "mlx5_defs.h"
 #include "mlx5_glue.h"
+#include "mlx5_mr.h"
 
 /* Device parameter to enable RX completion queue compression. */
 #define MLX5_RXQ_CQE_COMP_EN "rxq_cqe_comp_en"
@@ -84,10 +85,49 @@
 #define MLX5DV_CONTEXT_FLAGS_CQE_128B_COMP (1 << 4)
 #endif
 
+static const char *MZ_MLX5_PMD_SHARED_DATA = "mlx5_pmd_shared_data";
+
+/* Shared memory between primary and secondary processes. */
+struct mlx5_shared_data *mlx5_shared_data;
+
+/* Spinlock for mlx5_shared_data allocation. */
+static rte_spinlock_t mlx5_shared_data_lock = RTE_SPINLOCK_INITIALIZER;
+
 /** Driver-specific log messages type. */
 int mlx5_logtype;
 
 /**
+ * Prepare shared data between primary and secondary process.
+ */
+static void
+mlx5_prepare_shared_data(void)
+{
+	const struct rte_memzone *mz;
+
+	rte_spinlock_lock(&mlx5_shared_data_lock);
+	if (mlx5_shared_data == NULL) {
+		if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+			/* Allocate shared memory. */
+			mz = rte_memzone_reserve(MZ_MLX5_PMD_SHARED_DATA,
+						 sizeof(*mlx5_shared_data),
+						 SOCKET_ID_ANY, 0);
+		} else {
+			/* Lookup allocated shared memory. */
+			mz = rte_memzone_lookup(MZ_MLX5_PMD_SHARED_DATA);
+		}
+		if (mz == NULL)
+			rte_panic("Cannot allocate mlx5 shared data\n");
+		mlx5_shared_data = mz->addr;
+		/* Initialize shared data. */
+		if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+			LIST_INIT(&mlx5_shared_data->mem_event_cb_list);
+			rte_rwlock_init(&mlx5_shared_data->mem_event_rwlock);
+		}
+	}
+	rte_spinlock_unlock(&mlx5_shared_data_lock);
+}
+
+/**
  * Retrieve integer value from environment variable.
  *
  * @param[in] name
@@ -201,6 +241,7 @@ mlx5_dev_close(struct rte_eth_dev *dev)
 		priv->txqs = NULL;
 	}
 	mlx5_flow_delete_drop_queue(dev);
+	mlx5_mr_release(dev);
 	if (priv->pd != NULL) {
 		assert(priv->ctx != NULL);
 		claim_zero(mlx5_glue->dealloc_pd(priv->pd));
@@ -633,6 +674,8 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	struct ibv_counter_set_description cs_desc;
 #endif
 
+	/* Prepare shared data between primary and secondary process. */
+	mlx5_prepare_shared_data();
 	assert(pci_drv == &mlx5_driver);
 	/* Get mlx5_dev[] index. */
 	idx = mlx5_dev_idx(&pci_dev->addr);
@@ -1293,6 +1336,8 @@ rte_mlx5_pmd_init(void)
 	}
 	mlx5_glue->fork_init();
 	rte_pci_register(&mlx5_driver);
+	rte_mem_event_callback_register("MLX5_MEM_EVENT_CB",
+					mlx5_mr_mem_event_cb);
 }
 
 RTE_PMD_EXPORT_NAME(net_mlx5, __COUNTER__);
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index 47d266c90..d3fc74dc1 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -26,11 +26,13 @@
 #include <rte_pci.h>
 #include <rte_ether.h>
 #include <rte_ethdev_driver.h>
+#include <rte_rwlock.h>
 #include <rte_interrupts.h>
 #include <rte_errno.h>
 #include <rte_flow.h>
 
 #include "mlx5_utils.h"
+#include "mlx5_mr.h"
 #include "mlx5_rxtx.h"
 #include "mlx5_autoconf.h"
 #include "mlx5_defs.h"
@@ -50,6 +52,16 @@ enum {
 	PCI_DEVICE_ID_MELLANOX_CONNECTX5EXVF = 0x101a,
 };
 
+LIST_HEAD(mlx5_dev_list, priv);
+
+/* Shared memory between primary and secondary processes. */
+struct mlx5_shared_data {
+	struct mlx5_dev_list mem_event_cb_list;
+	rte_rwlock_t mem_event_rwlock;
+};
+
+extern struct mlx5_shared_data *mlx5_shared_data;
+
 struct mlx5_xstats_ctrl {
 	/* Number of device stats. */
 	uint16_t stats_n;
@@ -119,7 +131,10 @@ struct mlx5_verbs_alloc_ctx {
 	const void *obj; /* Pointer to the DPDK object. */
 };
 
+LIST_HEAD(mlx5_mr_list, mlx5_mr);
+
 struct priv {
+	LIST_ENTRY(priv) mem_event_cb; /* Called by memory event callback. */
 	struct rte_eth_dev_data *dev_data;  /* Pointer to device data. */
 	struct ibv_context *ctx; /* Verbs context. */
 	struct ibv_device_attr_ex device_attr; /* Device properties. */
@@ -146,6 +161,13 @@ struct priv {
 	struct mlx5_hrxq_drop *flow_drop_queue; /* Flow drop queue. */
 	struct mlx5_flows flows; /* RTE Flow rules. */
 	struct mlx5_flows ctrl_flows; /* Control flow rules. */
+	struct {
+		uint32_t dev_gen; /* Generation number to flush local caches. */
+		rte_rwlock_t rwlock; /* MR Lock. */
+		struct mlx5_mr_btree cache; /* Global MR cache table. */
+		struct mlx5_mr_list mr_list; /* Registered MR list. */
+		struct mlx5_mr_list mr_free_list; /* Freed MR list. */
+	} mr;
 	LIST_HEAD(rxq, mlx5_rxq_ctrl) rxqsctrl; /* DPDK Rx queues. */
 	LIST_HEAD(rxqibv, mlx5_rxq_ibv) rxqsibv; /* Verbs Rx queues. */
 	LIST_HEAD(hrxq, mlx5_hrxq) hrxqs; /* Verbs Hash Rx queues. */
diff --git a/drivers/net/mlx5/mlx5_defs.h b/drivers/net/mlx5/mlx5_defs.h
index f9093777d..72e80af26 100644
--- a/drivers/net/mlx5/mlx5_defs.h
+++ b/drivers/net/mlx5/mlx5_defs.h
@@ -37,6 +37,12 @@
  */
 #define MLX5_TX_COMP_THRESH_INLINE_DIV (1 << 3)
 
+/* Size of per-queue MR cache array for linear search. */
+#define MLX5_MR_CACHE_N 8
+
+/* Size of MR cache table for binary search. */
+#define MLX5_MR_BTREE_CACHE_N 256
+
 /*
  * If defined, only use software counters. The PMD will never ask the hardware
  * for these, and many of them won't be available.
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 746b94f73..6bb43cf4e 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -34,6 +34,7 @@
 #include <rte_interrupts.h>
 #include <rte_malloc.h>
 #include <rte_string_fns.h>
+#include <rte_rwlock.h>
 
 #include "mlx5.h"
 #include "mlx5_glue.h"
@@ -413,6 +414,21 @@ mlx5_dev_configure(struct rte_eth_dev *dev)
 		if (++j == rxqs_n)
 			j = 0;
 	}
+	/*
+	 * Once the device is added to the list of memory event callback, its
+	 * global MR cache table cannot be expanded on the fly because of
+	 * deadlock. If it overflows, lookup should be done by searching MR list
+	 * linearly, which is slow.
+	 */
+	if (mlx5_mr_btree_init(&priv->mr.cache, MLX5_MR_BTREE_CACHE_N * 2,
+			       dev->device->numa_node)) {
+		/* rte_errno is already set. */
+		return -rte_errno;
+	}
+	rte_rwlock_write_lock(&mlx5_shared_data->mem_event_rwlock);
+	LIST_INSERT_HEAD(&mlx5_shared_data->mem_event_cb_list,
+			 priv, mem_event_cb);
+	rte_rwlock_write_unlock(&mlx5_shared_data->mem_event_rwlock);
 	return 0;
 }
 
diff --git a/drivers/net/mlx5/mlx5_mr.c b/drivers/net/mlx5/mlx5_mr.c
index 736c40ae4..e964912bb 100644
--- a/drivers/net/mlx5/mlx5_mr.c
+++ b/drivers/net/mlx5/mlx5_mr.c
@@ -13,8 +13,1202 @@
 
 #include <rte_mempool.h>
 #include <rte_malloc.h>
+#include <rte_rwlock.h>
 
 #include "mlx5.h"
+#include "mlx5_mr.h"
 #include "mlx5_rxtx.h"
 #include "mlx5_glue.h"
 
+struct mr_find_contig_memsegs_data {
+	uintptr_t addr;
+	uintptr_t start;
+	uintptr_t end;
+	const struct rte_memseg_list *msl;
+};
+
+struct mr_update_mp_data {
+	struct rte_eth_dev *dev;
+	struct mlx5_mr_ctrl *mr_ctrl;
+	int ret;
+};
+
+/**
+ * Expand B-tree table to a given size. Can't be called with holding
+ * memory_hotplug_lock or priv->mr.rwlock due to rte_realloc().
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ * @param n
+ *   Number of entries for expansion.
+ *
+ * @return
+ *   0 on success, -1 on failure.
+ */
+static int
+mr_btree_expand(struct mlx5_mr_btree *bt, int n)
+{
+	void *mem;
+	int ret = 0;
+
+	if (n <= bt->size)
+		return ret;
+	/*
+	 * Downside of directly using rte_realloc() is that SOCKET_ID_ANY is
+	 * used inside if there's no room to expand. Because this is a quite
+	 * rare case and a part of very slow path, it is very acceptable.
+	 * Initially cache_bh[] will be given practically enough space and once
+	 * it is expanded, expansion wouldn't be needed again ever.
+	 */
+	mem = rte_realloc(bt->table, n * sizeof(struct mlx5_mr_cache), 0);
+	if (mem == NULL) {
+		/* Not an error, B-tree search will be skipped. */
+		DRV_LOG(WARNING, "failed to expand MR B-tree (%p) table",
+			(void *)bt);
+		ret = -1;
+	} else {
+		DRV_LOG(DEBUG, "expanded MR B-tree table (size=%u)", n);
+		bt->table = mem;
+		bt->size = n;
+	}
+	return ret;
+}
+
+/**
+ * Look up LKey from given B-tree lookup table, store the last index and return
+ * searched LKey.
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ * @param[out] idx
+ *   Pointer to index. Even on searh failure, returns index where it stops
+ *   searching so that index can be used when inserting a new entry.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static uint32_t
+mr_btree_lookup(struct mlx5_mr_btree *bt, uint16_t *idx, uintptr_t addr)
+{
+	struct mlx5_mr_cache *lkp_tbl;
+	uint16_t n;
+	uint16_t base = 0;
+
+	assert(bt != NULL);
+	lkp_tbl = *bt->table;
+	n = bt->len;
+	/* First entry must be NULL for comparison. */
+	assert(bt->len > 0 || (lkp_tbl[0].start == 0 &&
+			       lkp_tbl[0].lkey == UINT32_MAX));
+	/* Binary search. */
+	do {
+		register uint16_t delta = n >> 1;
+
+		if (addr < lkp_tbl[base + delta].start) {
+			n = delta;
+		} else {
+			base += delta;
+			n -= delta;
+		}
+	} while (n > 1);
+	assert(addr >= lkp_tbl[base].start);
+	*idx = base;
+	if (addr < lkp_tbl[base].end)
+		return lkp_tbl[base].lkey;
+	/* Not found. */
+	return UINT32_MAX;
+}
+
+/**
+ * Insert an entry to B-tree lookup table.
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ * @param entry
+ *   Pointer to new entry to insert.
+ *
+ * @return
+ *   0 on success, -1 on failure.
+ */
+static int
+mr_btree_insert(struct mlx5_mr_btree *bt, struct mlx5_mr_cache *entry)
+{
+	struct mlx5_mr_cache *lkp_tbl;
+	uint16_t idx = 0;
+	size_t shift;
+
+	assert(bt != NULL);
+	assert(bt->len <= bt->size);
+	assert(bt->len > 0);
+	lkp_tbl = *bt->table;
+	/* Find out the slot for insertion. */
+	if (mr_btree_lookup(bt, &idx, entry->start) != UINT32_MAX) {
+		DRV_LOG(DEBUG,
+			"abort insertion to B-tree(%p):"
+			" already exist at idx=%u [0x%lx, 0x%lx) lkey=0x%x",
+			(void *)bt, idx, entry->start, entry->end, entry->lkey);
+		/* Already exist, return. */
+		return 0;
+	}
+	/* If table is full, return error. */
+	if (unlikely(bt->len == bt->size)) {
+		bt->overflow = 1;
+		return -1;
+	}
+	/* Insert entry. */
+	++idx;
+	shift = (bt->len - idx) * sizeof(struct mlx5_mr_cache);
+	if (shift)
+		memmove(&lkp_tbl[idx + 1], &lkp_tbl[idx], shift);
+	lkp_tbl[idx] = *entry;
+	bt->len++;
+	DRV_LOG(DEBUG,
+		"inserted B-tree(%p)[%u], [0x%lx, 0x%lx) lkey=0x%x",
+		(void *)bt, idx, entry->start, entry->end, entry->lkey);
+	return 0;
+}
+
+/**
+ * Initialize B-tree and allocate memory for lookup table.
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ * @param n
+ *   Number of entries to allocate.
+ * @param socket
+ *   NUMA socket on which memory must be allocated.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx5_mr_btree_init(struct mlx5_mr_btree *bt, int n, int socket)
+{
+	if (bt == NULL) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
+	memset(bt, 0, sizeof(*bt));
+	bt->table = rte_calloc_socket("B-tree table",
+				      n, sizeof(struct mlx5_mr_cache),
+				      0, socket);
+	if (bt->table == NULL) {
+		rte_errno = ENOMEM;
+		DRV_LOG(ERR,
+			"failed to allocate memory for btree cache on socket %d",
+			socket);
+		return -rte_errno;
+	}
+	bt->size = n;
+	/* First entry must be NULL for binary search. */
+	(*bt->table)[bt->len++] = (struct mlx5_mr_cache) {
+		.lkey = UINT32_MAX,
+	};
+	DRV_LOG(DEBUG, "initialized B-tree %p with table %p",
+		(void *)bt, (void *)bt->table);
+	return 0;
+}
+
+/**
+ * Free B-tree resources.
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ */
+void
+mlx5_mr_btree_free(struct mlx5_mr_btree *bt)
+{
+	if (bt == NULL)
+		return;
+	DRV_LOG(DEBUG, "freeing B-tree %p with table %p",
+		(void *)bt, (void *)bt->table);
+	rte_free(bt->table);
+	memset(bt, 0, sizeof(*bt));
+}
+
+/**
+ * Dump all the entries in a B-tree
+ *
+ * @param bt
+ *   Pointer to B-tree structure.
+ */
+static void
+mlx5_mr_btree_dump(struct mlx5_mr_btree *bt)
+{
+	int idx;
+	struct mlx5_mr_cache *lkp_tbl;
+
+	if (bt == NULL)
+		return;
+	lkp_tbl = *bt->table;
+	for (idx = 0; idx < bt->len; ++idx) {
+		struct mlx5_mr_cache *entry = &lkp_tbl[idx];
+
+		DRV_LOG(DEBUG,
+			"B-tree(%p)[%u], [0x%lx, 0x%lx) lkey=0x%x",
+			(void *)bt, idx, entry->start, entry->end, entry->lkey);
+	}
+}
+
+/**
+ * Find virtually contiguous memory chunk in a given MR.
+ *
+ * @param dev
+ *   Pointer to MR structure.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry. If not found, this will not be
+ *   updated.
+ * @param start_idx
+ *   Start index of the memseg bitmap.
+ *
+ * @return
+ *   Next index to go on lookup.
+ */
+static int
+mr_find_next_chunk(struct mlx5_mr *mr, struct mlx5_mr_cache *entry,
+		   int base_idx)
+{
+	uintptr_t start = 0;
+	uintptr_t end = 0;
+	uint32_t idx = 0;
+
+	for (idx = base_idx; idx < mr->ms_bmp_n; ++idx) {
+		if (rte_bitmap_get(mr->ms_bmp, idx)) {
+			const struct rte_memseg_list *msl;
+			const struct rte_memseg *ms;
+
+			msl = mr->msl;
+			ms = rte_fbarray_get(&msl->memseg_arr,
+					     mr->ms_base_idx + idx);
+			assert(msl->page_sz == ms->hugepage_sz);
+			if (!start)
+				start = ms->addr_64;
+			end = ms->addr_64 + ms->hugepage_sz;
+		} else if (start) {
+			/* Passed the end of a fragment. */
+			break;
+		}
+	}
+	if (start) {
+		/* Found one chunk. */
+		entry->start = start;
+		entry->end = end;
+		entry->lkey = rte_cpu_to_be_32(mr->ibv_mr->lkey);
+	}
+	return idx;
+}
+
+/**
+ * Insert a MR to the global B-tree cache. It may fail due to low-on-memory.
+ * Then, this entry will have to be searched by mr_lookup_dev_list() in
+ * mlx5_mr_create() on miss.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param mr
+ *   Pointer to MR to insert.
+ *
+ * @return
+ *   0 on success, -1 on failure.
+ */
+static int
+mr_insert_dev_cache(struct rte_eth_dev *dev, struct mlx5_mr *mr)
+{
+	struct priv *priv = dev->data->dev_private;
+	unsigned int n;
+
+	DRV_LOG(DEBUG, "port %u inserting MR(%p) to global cache",
+		dev->data->port_id, (void *)mr);
+	for (n = 0; n < mr->ms_bmp_n; ) {
+		struct mlx5_mr_cache entry = { 0, };
+
+		/* Find a contiguous chunk and advance the index. */
+		n = mr_find_next_chunk(mr, &entry, n);
+		if (!entry.end)
+			break;
+		if (mr_btree_insert(&priv->mr.cache, &entry) < 0) {
+			/*
+			 * Overflowed, but the global table cannot be expanded
+			 * because of deadlock.
+			 */
+			return -1;
+		}
+	}
+	return 0;
+}
+
+/**
+ * Look up address in the original global MR list.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry. If no match, this will not be updated.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Found MR on match, NULL otherwise.
+ */
+static struct mlx5_mr *
+mr_lookup_dev_list(struct rte_eth_dev *dev, struct mlx5_mr_cache *entry,
+		   uintptr_t addr)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr *mr;
+
+	/* Iterate all the existing MRs. */
+	LIST_FOREACH(mr, &priv->mr.mr_list, mr) {
+		unsigned int n;
+
+		if (mr->ms_n == 0)
+			continue;
+		for (n = 0; n < mr->ms_bmp_n; ) {
+			struct mlx5_mr_cache ret = { 0, };
+
+			n = mr_find_next_chunk(mr, &ret, n);
+			if (addr >= ret.start && addr < ret.end) {
+				/* Found. */
+				*entry = ret;
+				return mr;
+			}
+		}
+	}
+	return NULL;
+}
+
+/**
+ * Look up address on device.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry. If no match, this will not be updated.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on failure and rte_errno is set.
+ */
+static uint32_t
+mr_lookup_dev(struct rte_eth_dev *dev, struct mlx5_mr_cache *entry,
+	      uintptr_t addr)
+{
+	struct priv *priv = dev->data->dev_private;
+	uint16_t idx;
+	uint32_t lkey = UINT32_MAX;
+	struct mlx5_mr *mr;
+
+	/*
+	 * If the global cache has overflowed since it failed to expand the
+	 * B-tree table, it can't have all the exisitng MRs. Then, the address
+	 * has to be searched by traversing the original MR list instead, which
+	 * is very slow path. Otherwise, the global cache is all inclusive.
+	 */
+	if (!unlikely(priv->mr.cache.overflow)) {
+		lkey = mr_btree_lookup(&priv->mr.cache, &idx, addr);
+		if (lkey != UINT32_MAX)
+			*entry = (*priv->mr.cache.table)[idx];
+	} else {
+		/* Falling back to the slowest path. */
+		mr = mr_lookup_dev_list(dev, entry, addr);
+		if (mr != NULL)
+			lkey = entry->lkey;
+	}
+	assert(lkey == UINT32_MAX || (addr >= entry->start &&
+				      addr < entry->end));
+	return lkey;
+}
+
+/**
+ * Free MR resources. MR lock must not be held to avoid a deadlock. rte_free()
+ * can raise memory free event and the callback function will spin on the lock.
+ *
+ * @param mr
+ *   Pointer to MR to free.
+ */
+static void
+mr_free(struct mlx5_mr *mr)
+{
+	if (mr == NULL)
+		return;
+	DRV_LOG(DEBUG, "freeing MR(%p):", (void *)mr);
+	if (mr->ibv_mr != NULL)
+		claim_zero(mlx5_glue->dereg_mr(mr->ibv_mr));
+	if (mr->ms_bmp != NULL)
+		rte_bitmap_free(mr->ms_bmp);
+	rte_free(mr);
+}
+
+/**
+ * Free Memory Region (MR).
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param mr
+ *   Pointer to MR to free.
+ */
+void
+mlx5_mr_free(struct rte_eth_dev *dev, struct mlx5_mr *mr)
+{
+	struct priv *priv = dev->data->dev_private;
+
+	/* Detach from the list and free resources later. */
+	rte_rwlock_write_lock(&priv->mr.rwlock);
+	LIST_REMOVE(mr, mr);
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+	/*
+	 * rte_free() inside can't be called with holding the lock. This could
+	 * cause deadlock when calling free callback.
+	 */
+	mr_free(mr);
+	DRV_LOG(DEBUG, "port %u MR(%p) freed", dev->data->port_id, (void *)mr);
+}
+
+/**
+ * Releass resources of detached MR having no online entry.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ */
+static void
+mlx5_mr_garbage_collect(struct rte_eth_dev *dev)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr *mr_next;
+	struct mlx5_mr_list free_list = LIST_HEAD_INITIALIZER(free_list);
+
+	/* Must be called from the primary process. */
+	assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
+	/*
+	 * MR can't be freed with holding the lock because rte_free() could call
+	 * memory free callback function. This will be a deadlock situation.
+	 */
+	rte_rwlock_write_lock(&priv->mr.rwlock);
+	/* Detach the whole free list and release it after unlocking. */
+	free_list = priv->mr.mr_free_list;
+	LIST_INIT(&priv->mr.mr_free_list);
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+	/* Release resources. */
+	mr_next = LIST_FIRST(&free_list);
+	while (mr_next != NULL) {
+		struct mlx5_mr *mr = mr_next;
+
+		mr_next = LIST_NEXT(mr, mr);
+		mr_free(mr);
+	}
+}
+
+/* Called during rte_memseg_contig_walk() by mlx5_mr_create(). */
+static int
+mr_find_contig_memsegs_cb(const struct rte_memseg_list *msl,
+			  const struct rte_memseg *ms, size_t len, void *arg)
+{
+	struct mr_find_contig_memsegs_data *data = arg;
+
+	if (data->addr < ms->addr_64 || data->addr >= ms->addr_64 + len)
+		return 0;
+	/* Found, save it and stop walking. */
+	data->start = ms->addr_64;
+	data->end = ms->addr_64 + len;
+	data->msl = msl;
+	return 1;
+}
+
+/**
+ * Create a new global Memroy Region (MR) for a missing virtual address.
+ * Register entire virtually contiguous memory chunk around the address.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry, found in the global cache or newly
+ *   created. If failed to create one, this will not be updated.
+ * @param addr
+ *   Target virtual address to register.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on failure and rte_errno is set.
+ */
+static uint32_t
+mlx5_mr_create(struct rte_eth_dev *dev, struct mlx5_mr_cache *entry,
+	       uintptr_t addr)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	const struct rte_memseg_list *msl;
+	const struct rte_memseg *ms;
+	struct mlx5_mr *mr = NULL;
+	size_t len;
+	uint32_t ms_n;
+	uint32_t bmp_size;
+	void *bmp_mem;
+	int ms_idx_shift = -1;
+	unsigned int n;
+	struct mr_find_contig_memsegs_data data = {
+		.addr = addr,
+	};
+	struct mr_find_contig_memsegs_data data_re;
+
+	DRV_LOG(DEBUG, "port %u creating a MR using address (%p)",
+		dev->data->port_id, (void *)addr);
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
+		DRV_LOG(WARNING,
+			"port %u using address (%p) of unregistered mempool"
+			" in secondary process, please create mempool"
+			" before rte_eth_dev_start()",
+			dev->data->port_id, (void *)addr);
+		rte_errno = EPERM;
+		goto err_nolock;
+	}
+	/*
+	 * Release detached MRs if any. This can't be called with holding either
+	 * memory_hotplug_lock or priv->mr.rwlock. MRs on the free list have
+	 * been detached by the memory free event but it couldn't be released
+	 * inside the callback due to deadlock. As a result, releasing resources
+	 * is quite opportunistic.
+	 */
+	mlx5_mr_garbage_collect(dev);
+	/*
+	 * Find out a contiguous virtual address chunk in use, to which the
+	 * given address belongs, in order to register maximum range. In the
+	 * best case where mempools are not dynamically recreated and
+	 * '--socket-mem' is speicified as an EAL option, it is very likely to
+	 * have only one MR(LKey) per a socket and per a hugepage-size even
+	 * though the system memory is highly fragmented.
+	 */
+	if (!rte_memseg_contig_walk(mr_find_contig_memsegs_cb, &data)) {
+		DRV_LOG(WARNING,
+			"port %u unable to find virtually contigous"
+			" chunk for address (%p)."
+			" rte_memseg_contig_walk() failed.",
+			dev->data->port_id, (void *)addr);
+		rte_errno = ENXIO;
+		goto err_nolock;
+	}
+alloc_resources:
+	/* Addresses must be page-aligned. */
+	assert(rte_is_aligned((void *)data.start, data.msl->page_sz));
+	assert(rte_is_aligned((void *)data.end, data.msl->page_sz));
+	msl = data.msl;
+	ms = rte_mem_virt2memseg((void *)data.start, msl);
+	len = data.end - data.start;
+	assert(msl->page_sz == ms->hugepage_sz);
+	/* Number of memsegs in the range. */
+	ms_n = len / msl->page_sz;
+	DRV_LOG(DEBUG,
+		"port %u extending %p to [0x%lx, 0x%lx), page_sz=0x%lx, ms_n=%u",
+		dev->data->port_id, (void *)addr,
+		data.start, data.end, msl->page_sz, ms_n);
+	/* Size of memory for bitmap. */
+	bmp_size = rte_bitmap_get_memory_footprint(ms_n);
+	mr = rte_zmalloc_socket(NULL,
+				RTE_ALIGN_CEIL(sizeof(*mr),
+					       RTE_CACHE_LINE_SIZE) +
+				bmp_size,
+				RTE_CACHE_LINE_SIZE, msl->socket_id);
+	if (mr == NULL) {
+		DRV_LOG(WARNING,
+			"port %u unable to allocate memory for a new MR of"
+			" address (%p).",
+			dev->data->port_id, (void *)addr);
+		rte_errno = ENOMEM;
+		goto err_nolock;
+	}
+	mr->msl = msl;
+	/*
+	 * Save the index of the first memseg and initialize memseg bitmap. To
+	 * see if a memseg of ms_idx in the memseg-list is still valid, check:
+	 *	rte_bitmap_get(mr->bmp, ms_idx - mr->ms_base_idx)
+	 */
+	mr->ms_base_idx = rte_fbarray_find_idx(&msl->memseg_arr, ms);
+	bmp_mem = RTE_PTR_ALIGN_CEIL(mr + 1, RTE_CACHE_LINE_SIZE);
+	mr->ms_bmp = rte_bitmap_init(ms_n, bmp_mem, bmp_size);
+	if (mr->ms_bmp == NULL) {
+		DRV_LOG(WARNING,
+			"port %u unable to initialize bitamp for a new MR of"
+			" address (%p).",
+			dev->data->port_id, (void *)addr);
+		rte_errno = EINVAL;
+		goto err_nolock;
+	}
+	/*
+	 * Should recheck whether the extended contiguous chunk is still valid.
+	 * Because memory_hotplug_lock can't be held if there's any memory
+	 * related calls in a critical path, resource allocation above can't be
+	 * locked. If the memory has been changed at this point, try again with
+	 * just single page. If not, go on with the big chunk atomically from
+	 * here.
+	 */
+	rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
+	data_re = data;
+	if (len > msl->page_sz &&
+	    !rte_memseg_contig_walk(mr_find_contig_memsegs_cb, &data_re)) {
+		DRV_LOG(WARNING,
+			"port %u unable to find virtually contigous"
+			" chunk for address (%p)."
+			" rte_memseg_contig_walk() failed.",
+			dev->data->port_id, (void *)addr);
+		rte_errno = ENXIO;
+		goto err_memlock;
+	}
+	if (data.start != data_re.start || data.end != data_re.end) {
+		/*
+		 * The extended contiguous chunk has been changed. Try again
+		 * with single memseg instead.
+		 */
+		data.start = RTE_ALIGN_FLOOR(addr, msl->page_sz);
+		data.end = data.start + msl->page_sz;
+		rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
+		mr_free(mr);
+		goto alloc_resources;
+	}
+	assert(data.msl == data_re.msl);
+	rte_rwlock_write_lock(&priv->mr.rwlock);
+	/*
+	 * Check the address is really missing. If other thread already created
+	 * one or it is not found due to overflow, abort and return.
+	 */
+	if (mr_lookup_dev(dev, entry, addr) != UINT32_MAX) {
+		/*
+		 * Insert to the global cache table. It may fail due to
+		 * low-on-memory. Then, this entry will have to be searched
+		 * here again.
+		 */
+		mr_btree_insert(&priv->mr.cache, entry);
+		DRV_LOG(DEBUG,
+			"port %u found MR for %p on final lookup, abort",
+			dev->data->port_id, (void *)addr);
+		rte_rwlock_write_unlock(&priv->mr.rwlock);
+		rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
+		/*
+		 * Must be unlocked before calling rte_free() because
+		 * mlx5_mr_mem_event_free_cb() can be called inside.
+		 */
+		mr_free(mr);
+		return entry->lkey;
+	}
+	/*
+	 * Trim start and end addresses for verbs MR. Set bits for registering
+	 * memsegs but exclude already registered ones. Bitmap can be
+	 * fragmented.
+	 */
+	for (n = 0; n < ms_n; ++n) {
+		uintptr_t start;
+		struct mlx5_mr_cache ret = { 0, };
+
+		start = data_re.start + n * msl->page_sz;
+		/* Exclude memsegs already registered by other MRs. */
+		if (mr_lookup_dev(dev, &ret, start) == UINT32_MAX) {
+			/*
+			 * Start from the first unregistered memseg in the
+			 * extended range.
+			 */
+			if (ms_idx_shift == -1) {
+				mr->ms_base_idx += n;
+				data.start = start;
+				ms_idx_shift = n;
+			}
+			data.end = start + msl->page_sz;
+			rte_bitmap_set(mr->ms_bmp, n - ms_idx_shift);
+			++mr->ms_n;
+		}
+	}
+	len = data.end - data.start;
+	mr->ms_bmp_n = len / msl->page_sz;
+	assert(ms_idx_shift + mr->ms_bmp_n <= ms_n);
+	/*
+	 * Finally create a verbs MR for the memory chunk. ibv_reg_mr() can be
+	 * called with holding the memory lock because it doesn't use
+	 * mlx5_alloc_buf_extern() which eventually calls rte_malloc_socket()
+	 * through mlx5_alloc_verbs_buf().
+	 */
+	mr->ibv_mr = mlx5_glue->reg_mr(priv->pd, (void *)data.start, len,
+				       IBV_ACCESS_LOCAL_WRITE);
+	if (mr->ibv_mr == NULL) {
+		DRV_LOG(WARNING,
+			"port %u fail to create a verbs MR for address (%p)",
+			dev->data->port_id, (void *)addr);
+		rte_errno = EINVAL;
+		goto err_mrlock;
+	}
+	assert((uintptr_t)mr->ibv_mr->addr == data.start);
+	assert(mr->ibv_mr->length == len);
+	LIST_INSERT_HEAD(&priv->mr.mr_list, mr, mr);
+	DRV_LOG(DEBUG,
+		"port %u MR CREATED (%p) for %p:\n"
+		"  [0x%lx, 0x%lx), lkey=0x%x base_idx=%u ms_n=%u, ms_bmp_n=%u",
+		dev->data->port_id, (void *)mr, (void *)addr,
+		data.start, data.end, rte_cpu_to_be_32(mr->ibv_mr->lkey),
+		mr->ms_base_idx, mr->ms_n, mr->ms_bmp_n);
+	/* Insert to the global cache table. */
+	mr_insert_dev_cache(dev, mr);
+	/* Fill in output data. */
+	mr_lookup_dev(dev, entry, addr);
+	/* Lookup can't fail. */
+	assert(entry->lkey != UINT32_MAX);
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+	rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
+	return entry->lkey;
+err_mrlock:
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+err_memlock:
+	rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
+err_nolock:
+	/*
+	 * In case of error, as this can be called in a datapath, a warning
+	 * message per an error is preferable instead. Must be unlocked before
+	 * calling rte_free() because mlx5_mr_mem_event_free_cb() can be called
+	 * inside.
+	 */
+	mr_free(mr);
+	return UINT32_MAX;
+}
+
+/**
+ * Rebuild the global B-tree cache of device from the original MR list.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ */
+static void
+mr_rebuild_dev_cache(struct rte_eth_dev *dev)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr *mr;
+
+	DRV_LOG(DEBUG, "port %u rebuild dev cache[]", dev->data->port_id);
+	/* Flush cache to rebuild. */
+	priv->mr.cache.len = 1;
+	priv->mr.cache.overflow = 0;
+	/* Iterate all the existing MRs. */
+	LIST_FOREACH(mr, &priv->mr.mr_list, mr)
+		if (mr_insert_dev_cache(dev, mr) < 0)
+			return;
+}
+
+/**
+ * Callback for memory free event. Iterate freed memsegs and check whether it
+ * belongs to an existing MR. If found, clear the bit from bitmap of MR. As a
+ * result, the MR would be fragmented. If it becomes empty, the MR will be freed
+ * later by mlx5_mr_garbage_collect(). Even if this callback is called from a
+ * secondary process, the garbage collector will be called in primary process
+ * as the secondary process can't call mlx5_mr_create().
+ *
+ * The global cache must be rebuilt if there's any change and this event has to
+ * be propagated to dataplane threads to flush the local caches.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param addr
+ *   Address of freed memory.
+ * @param len
+ *   Size of freed memory.
+ */
+static void
+mlx5_mr_mem_event_free_cb(struct rte_eth_dev *dev, const void *addr, size_t len)
+{
+	struct priv *priv = dev->data->dev_private;
+	const struct rte_memseg_list *msl;
+	struct mlx5_mr *mr;
+	int ms_n;
+	int i;
+	int rebuild = 0;
+
+	DRV_LOG(DEBUG, "port %u free callback: addr=%p, len=%lu",
+		dev->data->port_id, addr, len);
+	msl = rte_mem_virt2memseg_list(addr);
+	/* addr and len must be page-aligned. */
+	assert((uintptr_t)addr == RTE_ALIGN((uintptr_t)addr, msl->page_sz));
+	assert(len == RTE_ALIGN(len, msl->page_sz));
+	ms_n = len / msl->page_sz;
+	rte_rwlock_write_lock(&priv->mr.rwlock);
+	/* Clear bits of freed memsegs from MR. */
+	for (i = 0; i < ms_n; ++i) {
+		const struct rte_memseg *ms;
+		struct mlx5_mr_cache entry;
+		uintptr_t start;
+		int ms_idx;
+		uint32_t pos;
+
+		/* Find MR having this memseg. */
+		start = (uintptr_t)addr + i * msl->page_sz;
+		mr = mr_lookup_dev_list(dev, &entry, start);
+		if (mr == NULL)
+			continue;
+		ms = rte_mem_virt2memseg((void *)start, msl);
+		assert(ms != NULL);
+		assert(msl->page_sz == ms->hugepage_sz);
+		ms_idx = rte_fbarray_find_idx(&msl->memseg_arr, ms);
+		pos = ms_idx - mr->ms_base_idx;
+		assert(rte_bitmap_get(mr->ms_bmp, pos));
+		assert(pos < mr->ms_bmp_n);
+		DRV_LOG(DEBUG, "port %u MR(%p): clear bitmap[%u] for addr %p",
+			dev->data->port_id, (void *)mr, pos, (void *)start);
+		rte_bitmap_clear(mr->ms_bmp, pos);
+		if (--mr->ms_n == 0) {
+			LIST_REMOVE(mr, mr);
+			LIST_INSERT_HEAD(&priv->mr.mr_free_list, mr, mr);
+			DRV_LOG(DEBUG, "port %u remove MR(%p) from list",
+				dev->data->port_id, (void *)mr);
+		}
+		/*
+		 * MR is fragmented or will be freed. the global cache must be
+		 * rebuilt.
+		 */
+		rebuild = 1;
+	}
+	if (rebuild) {
+		mr_rebuild_dev_cache(dev);
+		/*
+		 * Flush local caches by propagating invalidation across cores.
+		 * rte_smp_wmb() is enough to synchronize this event. If one of
+		 * freed memsegs is seen by other core, that means the memseg
+		 * has been allocated by allocator, which will come after this
+		 * free call. Therefore, this store instruction (incrementing
+		 * generation below) will be guaranteed to be seen by other core
+		 * before the core sees the newly allocated memory.
+		 */
+		++priv->mr.dev_gen;
+		DRV_LOG(DEBUG, "broadcasting local cache flush, gen=%d",
+			priv->mr.dev_gen);
+		rte_smp_wmb();
+	}
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+	if (rebuild && rte_log_get_level(mlx5_logtype) == RTE_LOG_DEBUG)
+		mlx5_mr_dump_dev(dev);
+}
+
+/**
+ * Callback for memory event. This can be called from both primary and secondary
+ * process.
+ *
+ * @param event_type
+ *   Memory event type.
+ * @param addr
+ *   Address of memory.
+ * @param len
+ *   Size of memory.
+ */
+void
+mlx5_mr_mem_event_cb(enum rte_mem_event event_type, const void *addr,
+		     size_t len)
+{
+	struct priv *priv;
+	struct mlx5_dev_list *dev_list = &mlx5_shared_data->mem_event_cb_list;
+
+	switch (event_type) {
+	case RTE_MEM_EVENT_FREE:
+		rte_rwlock_write_lock(&mlx5_shared_data->mem_event_rwlock);
+		/* Iterate all the existing mlx5 devices. */
+		LIST_FOREACH(priv, dev_list, mem_event_cb)
+			mlx5_mr_mem_event_free_cb(eth_dev(priv), addr, len);
+		rte_rwlock_write_unlock(&mlx5_shared_data->mem_event_rwlock);
+		break;
+	case RTE_MEM_EVENT_ALLOC:
+	default:
+		break;
+	}
+}
+
+/**
+ * Look up address in the global MR cache table. If not found, create a new MR.
+ * Insert the found/created entry to local bottom-half cache table.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param mr_ctrl
+ *   Pointer to per-queue MR control structure.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry, found in the global cache or newly
+ *   created. If failed to create one, this is not written.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static uint32_t
+mlx5_mr_lookup_dev(struct rte_eth_dev *dev, struct mlx5_mr_ctrl *mr_ctrl,
+		   struct mlx5_mr_cache *entry, uintptr_t addr)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr_btree *bt = &mr_ctrl->cache_bh;
+	uint16_t idx;
+	uint32_t lkey;
+
+	/* If local cache table is full, try to double it. */
+	if (unlikely(bt->len == bt->size))
+		mr_btree_expand(bt, bt->size << 1);
+	/* Look up in the global cache. */
+	rte_rwlock_read_lock(&priv->mr.rwlock);
+	lkey = mr_btree_lookup(&priv->mr.cache, &idx, addr);
+	if (lkey != UINT32_MAX) {
+		/* Found. */
+		*entry = (*priv->mr.cache.table)[idx];
+		rte_rwlock_read_unlock(&priv->mr.rwlock);
+		/*
+		 * Update local cache. Even if it fails, return the found entry
+		 * to update top-half cache. Next time, this entry will be found
+		 * in the global cache.
+		 */
+		mr_btree_insert(bt, entry);
+		return lkey;
+	}
+	rte_rwlock_read_unlock(&priv->mr.rwlock);
+	/* First time to see the address? Create a new MR. */
+	lkey = mlx5_mr_create(dev, entry, addr);
+	/*
+	 * Update the local cache if successfully created a new global MR. Even
+	 * if failed to create one, there's no action to take in this datapath
+	 * code. As returning LKey is invalid, this will eventually make HW
+	 * fail.
+	 */
+	if (lkey != UINT32_MAX)
+		mr_btree_insert(bt, entry);
+	return lkey;
+}
+
+/**
+ * Bottom-half of LKey search on datapath. Firstly search in cache_bh[] and if
+ * misses, search in the global MR cache table and update the new entry to
+ * per-queue local caches.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param mr_ctrl
+ *   Pointer to per-queue MR control structure.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static uint32_t
+mlx5_mr_addr2mr_bh(struct rte_eth_dev *dev, struct mlx5_mr_ctrl *mr_ctrl,
+		   uintptr_t addr)
+{
+	uint32_t lkey;
+	uint16_t bh_idx = 0;
+	/* Victim in top-half cache to replace with new entry. */
+	struct mlx5_mr_cache *repl = &mr_ctrl->cache[mr_ctrl->head];
+
+	/* Binary-search MR translation table. */
+	lkey = mr_btree_lookup(&mr_ctrl->cache_bh, &bh_idx, addr);
+	/* Update top-half cache. */
+	if (likely(lkey != UINT32_MAX)) {
+		*repl = (*mr_ctrl->cache_bh.table)[bh_idx];
+	} else {
+		/*
+		 * If missed in local lookup table, search in the global cache
+		 * and local cache_bh[] will be updated inside if possible.
+		 * Top-half cache entry will also be updated.
+		 */
+		lkey = mlx5_mr_lookup_dev(dev, mr_ctrl, repl, addr);
+		if (unlikely(lkey == UINT32_MAX))
+			return UINT32_MAX;
+	}
+	/* Update the most recently used entry. */
+	mr_ctrl->mru = mr_ctrl->head;
+	/* Point to the next victim, the oldest. */
+	mr_ctrl->head = (mr_ctrl->head + 1) % MLX5_MR_CACHE_N;
+	return lkey;
+}
+
+/**
+ * Bottom-half of LKey search on Rx.
+ *
+ * @param rxq
+ *   Pointer to Rx queue structure.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+uint32_t
+mlx5_rx_addr2mr_bh(struct mlx5_rxq_data *rxq, uintptr_t addr)
+{
+	struct mlx5_rxq_ctrl *rxq_ctrl =
+		container_of(rxq, struct mlx5_rxq_ctrl, rxq);
+	struct mlx5_mr_ctrl *mr_ctrl = &rxq->mr_ctrl;
+	struct priv *priv = rxq_ctrl->priv;
+
+	DRV_LOG(DEBUG,
+		"Rx queue %u: miss on top-half, mru=%u, head=%u, addr=%p",
+		rxq_ctrl->idx, mr_ctrl->mru, mr_ctrl->head, (void *)addr);
+	return mlx5_mr_addr2mr_bh(eth_dev(priv), mr_ctrl, addr);
+}
+
+/**
+ * Bottom-half of LKey search on Tx.
+ *
+ * @param txq
+ *   Pointer to Tx queue structure.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+uint32_t
+mlx5_tx_addr2mr_bh(struct mlx5_txq_data *txq, uintptr_t addr)
+{
+	struct mlx5_txq_ctrl *txq_ctrl =
+		container_of(txq, struct mlx5_txq_ctrl, txq);
+	struct mlx5_mr_ctrl *mr_ctrl = &txq->mr_ctrl;
+	struct priv *priv = txq_ctrl->priv;
+
+	DRV_LOG(DEBUG,
+		"Tx queue %u: miss on top-half, mru=%u, head=%u, addr=%p",
+		txq_ctrl->idx, mr_ctrl->mru, mr_ctrl->head, (void *)addr);
+	return mlx5_mr_addr2mr_bh(eth_dev(priv), mr_ctrl, addr);
+}
+
+/**
+ * Flush all of the local cache entries.
+ *
+ * @param mr_ctrl
+ *   Pointer to per-queue MR control structure.
+ */
+void
+mlx5_mr_flush_local_cache(struct mlx5_mr_ctrl *mr_ctrl)
+{
+	/* Reset the most-recently-used index. */
+	mr_ctrl->mru = 0;
+	/* Reset the linear search array. */
+	mr_ctrl->head = 0;
+	memset(mr_ctrl->cache, 0, sizeof(mr_ctrl->cache));
+	/* Reset the B-tree table. */
+	mr_ctrl->cache_bh.len = 1;
+	mr_ctrl->cache_bh.overflow = 0;
+	/* Update the generation number. */
+	mr_ctrl->cur_gen = *mr_ctrl->dev_gen_ptr;
+	DRV_LOG(DEBUG, "mr_ctrl(%p): flushed, cur_gen=%d",
+		(void *)mr_ctrl, mr_ctrl->cur_gen);
+}
+
+/* Called during rte_mempool_mem_iter() by mlx5_mr_update_mp(). */
+static void
+mlx5_mr_update_mp_cb(struct rte_mempool *mp __rte_unused, void *opaque,
+		     struct rte_mempool_memhdr *memhdr,
+		     unsigned mem_idx __rte_unused)
+{
+	struct mr_update_mp_data *data = opaque;
+	uint32_t lkey;
+
+	/* Stop iteration if failed in the previous walk. */
+	if (data->ret < 0)
+		return;
+	/* Register address of the chunk and update local caches. */
+	lkey = mlx5_mr_addr2mr_bh(data->dev, data->mr_ctrl,
+				  (uintptr_t)memhdr->addr);
+	if (lkey == UINT32_MAX)
+		data->ret = -1;
+}
+
+/**
+ * Register entire memory chunks in a Mempool.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param mr_ctrl
+ *   Pointer to per-queue MR control structure.
+ * @param mp
+ *   Pointer to registering Mempool.
+ *
+ * @return
+ *   0 on success, -1 on failure.
+ */
+int
+mlx5_mr_update_mp(struct rte_eth_dev *dev, struct mlx5_mr_ctrl *mr_ctrl,
+		  struct rte_mempool *mp)
+{
+	struct mr_update_mp_data data = {
+		.dev = dev,
+		.mr_ctrl = mr_ctrl,
+		.ret = 0,
+	};
+
+	rte_mempool_mem_iter(mp, mlx5_mr_update_mp_cb, &data);
+	return data.ret;
+}
+
+/**
+ * Dump all the created MRs and the global cache entries.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ */
+void
+mlx5_mr_dump_dev(struct rte_eth_dev *dev)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr *mr;
+	int mr_n = 0;
+	int chunk_n = 0;
+
+	rte_rwlock_read_lock(&priv->mr.rwlock);
+	/* Iterate all the existing MRs. */
+	LIST_FOREACH(mr, &priv->mr.mr_list, mr) {
+		unsigned int n;
+
+		DRV_LOG(DEBUG,
+			"port %u MR[%u], LKey = 0x%x, ms_n = %u, ms_bmp_n = %u",
+			dev->data->port_id, mr_n++,
+			rte_cpu_to_be_32(mr->ibv_mr->lkey),
+			mr->ms_n, mr->ms_bmp_n);
+		if (mr->ms_n == 0)
+			continue;
+		for (n = 0; n < mr->ms_bmp_n; ) {
+			struct mlx5_mr_cache ret = { 0, };
+
+			n = mr_find_next_chunk(mr, &ret, n);
+			if (!ret.end)
+				break;
+			DRV_LOG(DEBUG, "  chunk[%u], [0x%lx, 0x%lx)",
+				chunk_n++, ret.start, ret.end);
+		}
+	}
+	DRV_LOG(DEBUG, "port %u dumping global cache", dev->data->port_id);
+	mlx5_mr_btree_dump(&priv->mr.cache);
+	rte_rwlock_read_unlock(&priv->mr.rwlock);
+}
+
+/**
+ * Release all the created MRs and resources. Remove device from memory callback
+ * list.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ */
+void
+mlx5_mr_release(struct rte_eth_dev *dev)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct mlx5_mr *mr_next = LIST_FIRST(&priv->mr.mr_list);
+
+	/* Remove from memory callback device list. */
+	rte_rwlock_write_lock(&mlx5_shared_data->mem_event_rwlock);
+	LIST_REMOVE(priv, mem_event_cb);
+	rte_rwlock_write_unlock(&mlx5_shared_data->mem_event_rwlock);
+	if (rte_log_get_level(mlx5_logtype) == RTE_LOG_DEBUG)
+		mlx5_mr_dump_dev(dev);
+	rte_rwlock_write_lock(&priv->mr.rwlock);
+	/* Detach from MR list and move to free list. */
+	while (mr_next != NULL) {
+		struct mlx5_mr *mr = mr_next;
+
+		mr_next = LIST_NEXT(mr, mr);
+		LIST_REMOVE(mr, mr);
+		LIST_INSERT_HEAD(&priv->mr.mr_free_list, mr, mr);
+	}
+	LIST_INIT(&priv->mr.mr_list);
+	/* Free global cache. */
+	mlx5_mr_btree_free(&priv->mr.cache);
+	rte_rwlock_write_unlock(&priv->mr.rwlock);
+	/* Free all remaining MRs. */
+	mlx5_mr_garbage_collect(dev);
+}
diff --git a/drivers/net/mlx5/mlx5_mr.h b/drivers/net/mlx5/mlx5_mr.h
new file mode 100644
index 000000000..a0a0ef755
--- /dev/null
+++ b/drivers/net/mlx5/mlx5_mr.h
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2018 6WIND S.A.
+ * Copyright 2018 Mellanox Technologies, Ltd
+ */
+
+#ifndef RTE_PMD_MLX5_MR_H_
+#define RTE_PMD_MLX5_MR_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/queue.h>
+
+/* Verbs header. */
+/* ISO C doesn't support unnamed structs/unions, disabling -pedantic. */
+#ifdef PEDANTIC
+#pragma GCC diagnostic ignored "-Wpedantic"
+#endif
+#include <infiniband/verbs.h>
+#include <infiniband/mlx5dv.h>
+#ifdef PEDANTIC
+#pragma GCC diagnostic error "-Wpedantic"
+#endif
+
+#include <rte_eal_memconfig.h>
+#include <rte_ethdev.h>
+#include <rte_rwlock.h>
+#include <rte_bitmap.h>
+
+/* Memory Region object. */
+struct mlx5_mr {
+	LIST_ENTRY(mlx5_mr) mr; /**< Pointer to the prev/next entry. */
+	struct ibv_mr *ibv_mr; /* Verbs Memory Region. */
+	const struct rte_memseg_list *msl;
+	int ms_base_idx; /* Start index of msl->memseg_arr[]. */
+	int ms_n; /* Number of memsegs in use. */
+	uint32_t ms_bmp_n; /* Number of bits in memsegs bit-mask. */
+	struct rte_bitmap *ms_bmp; /* Bit-mask of memsegs belonged to MR. */
+};
+
+/* Cache entry for Memory Region. */
+struct mlx5_mr_cache {
+	uintptr_t start; /* Start address of MR. */
+	uintptr_t end; /* End address of MR. */
+	uint32_t lkey; /* rte_cpu_to_be_32(ibv_mr->lkey). */
+} __rte_packed;
+
+/* MR Cache table for Binary search. */
+struct mlx5_mr_btree {
+	uint16_t len; /* Number of entries. */
+	uint16_t size; /* Total number of entries. */
+	int overflow; /* Mark failure of table expansion. */
+	struct mlx5_mr_cache (*table)[];
+} __rte_packed;
+
+/* Per-queue MR control descriptor. */
+struct mlx5_mr_ctrl {
+	uint32_t *dev_gen_ptr; /* Generation number of device to poll. */
+	uint32_t cur_gen; /* Generation number saved to flush caches. */
+	uint16_t mru; /* Index of last hit entry in top-half cache. */
+	uint16_t head; /* Index of the oldest entry in top-half cache. */
+	struct mlx5_mr_cache cache[MLX5_MR_CACHE_N]; /* Cache for top-half. */
+	struct mlx5_mr_btree cache_bh; /* Cache for bottom-half. */
+} __rte_packed;
+
+/* First entry must be NULL for comparison. */
+#define MR_N(n) ((n) - 1)
+
+/* Whether there's only one entry in MR lookup table. */
+#define IS_SINGLE_MR(n) (MR_N(n) == 1)
+
+extern struct mlx5_dev_list  mlx5_mem_event_cb_list;
+extern rte_rwlock_t mlx5_mem_event_rwlock;
+
+void mlx5_mr_free(struct rte_eth_dev *dev, struct mlx5_mr *mr);
+int mlx5_mr_btree_init(struct mlx5_mr_btree *bt, int n, int socket);
+void mlx5_mr_btree_free(struct mlx5_mr_btree *bt);
+void mlx5_mr_mem_event_cb(enum rte_mem_event event_type, const void *addr,
+			  size_t len);
+int mlx5_mr_update_mp(struct rte_eth_dev *dev, struct mlx5_mr_ctrl *mr_ctrl,
+		      struct rte_mempool *mp);
+void mlx5_mr_dump_dev(struct rte_eth_dev *dev);
+void mlx5_mr_release(struct rte_eth_dev *dev);
+
+/**
+ * Look up LKey from given lookup table by linear search. Firstly look up the
+ * last-hit entry. If miss, the entire array is searched. If found, update the
+ * last-hit index and return LKey.
+ *
+ * @param lkp_tbl
+ *   Pointer to lookup table.
+ * @param[in,out] cached_idx
+ *   Pointer to last-hit index.
+ * @param n
+ *   Size of lookup table.
+ * @param addr
+ *   Search key.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static __rte_always_inline uint32_t
+mlx5_mr_lookup_cache(struct mlx5_mr_cache *lkp_tbl, uint16_t *cached_idx,
+		     uint16_t n, uintptr_t addr)
+{
+	uint16_t idx;
+
+	if (likely(addr >= lkp_tbl[*cached_idx].start &&
+		   addr < lkp_tbl[*cached_idx].end))
+		return lkp_tbl[*cached_idx].lkey;
+	for (idx = 0; idx < n && lkp_tbl[idx].start != 0; ++idx) {
+		if (addr >= lkp_tbl[idx].start &&
+		    addr < lkp_tbl[idx].end) {
+			/* Found. */
+			*cached_idx = idx;
+			return lkp_tbl[idx].lkey;
+		}
+	}
+	return UINT32_MAX;
+}
+
+#endif /* RTE_PMD_MLX5_MR_H_ */
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index d4fe1fed7..22e2f9673 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -789,7 +789,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 			.addr = rte_cpu_to_be_64(rte_pktmbuf_mtod(buf,
 								  uintptr_t)),
 			.byte_count = rte_cpu_to_be_32(DATA_LEN(buf)),
-			.lkey = UINT32_MAX,
+			.lkey = mlx5_rx_mb2mr(rxq_data, buf),
 		};
 	}
 	rxq_data->rq_db = rwq.dbrec;
@@ -967,6 +967,11 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		rte_errno = ENOMEM;
 		return NULL;
 	}
+	if (mlx5_mr_btree_init(&tmpl->rxq.mr_ctrl.cache_bh,
+			       MLX5_MR_BTREE_CACHE_N, socket)) {
+		/* rte_errno is already set. */
+		goto error;
+	}
 	tmpl->socket = socket;
 	if (dev->data->dev_conf.intr_conf.rxq)
 		tmpl->irq = 1;
@@ -1120,6 +1125,7 @@ mlx5_rxq_release(struct rte_eth_dev *dev, uint16_t idx)
 		DRV_LOG(DEBUG, "port %u Rx queue %u: refcnt %d",
 			dev->data->port_id, rxq_ctrl->idx,
 			rte_atomic32_read(&rxq_ctrl->refcnt));
+		mlx5_mr_btree_free(&rxq_ctrl->rxq.mr_ctrl.cache_bh);
 		LIST_REMOVE(rxq_ctrl, next);
 		rte_free(rxq_ctrl);
 		(*priv->rxqs)[idx] = NULL;
diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 56c243495..8a863c157 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -1965,6 +1965,9 @@ mlx5_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		 * changes.
 		 */
 		wqe->addr = rte_cpu_to_be_64(rte_pktmbuf_mtod(rep, uintptr_t));
+		/* If there's only one MR, no need to replace LKey in WQE. */
+		if (unlikely(!IS_SINGLE_MR(rxq->mr_ctrl.cache_bh.len)))
+			wqe->lkey = mlx5_rx_mb2mr(rxq, rep);
 		if (len > DATA_LEN(seg)) {
 			len -= DATA_LEN(seg);
 			++NB_SEGS(pkt);
diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
index e8cad51aa..74581cf9b 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -29,6 +29,7 @@
 
 #include "mlx5_utils.h"
 #include "mlx5.h"
+#include "mlx5_mr.h"
 #include "mlx5_autoconf.h"
 #include "mlx5_defs.h"
 #include "mlx5_prm.h"
@@ -81,6 +82,7 @@ struct mlx5_rxq_data {
 	uint16_t rq_ci;
 	uint16_t rq_pi;
 	uint16_t cq_ci;
+	struct mlx5_mr_ctrl mr_ctrl; /* MR control descriptor. */
 	volatile struct mlx5_wqe_data_seg(*wqes)[];
 	volatile struct mlx5_cqe(*cqes)[];
 	struct rxq_zip zip; /* Compressed context. */
@@ -109,8 +111,8 @@ struct mlx5_rxq_ibv {
 struct mlx5_rxq_ctrl {
 	LIST_ENTRY(mlx5_rxq_ctrl) next; /* Pointer to the next element. */
 	rte_atomic32_t refcnt; /* Reference counter. */
-	struct priv *priv; /* Back pointer to private data. */
 	struct mlx5_rxq_ibv *ibv; /* Verbs elements. */
+	struct priv *priv; /* Back pointer to private data. */
 	struct mlx5_rxq_data rxq; /* Data path structure. */
 	unsigned int socket; /* CPU socket ID for allocations. */
 	uint32_t tunnel_types[16]; /* Tunnel type counter. */
@@ -165,6 +167,7 @@ struct mlx5_txq_data {
 	uint16_t inline_max_packet_sz; /* Max packet size for inlining. */
 	uint32_t qp_num_8s; /* QP number shifted by 8. */
 	uint64_t offloads; /* Offloads for Tx Queue. */
+	struct mlx5_mr_ctrl mr_ctrl; /* MR control descriptor. */
 	volatile struct mlx5_cqe (*cqes)[]; /* Completion queue. */
 	volatile void *wqes; /* Work queue (use volatile to write into). */
 	volatile uint32_t *qp_db; /* Work queue doorbell. */
@@ -187,11 +190,11 @@ struct mlx5_txq_ibv {
 struct mlx5_txq_ctrl {
 	LIST_ENTRY(mlx5_txq_ctrl) next; /* Pointer to the next element. */
 	rte_atomic32_t refcnt; /* Reference counter. */
-	struct priv *priv; /* Back pointer to private data. */
 	unsigned int socket; /* CPU socket ID for allocations. */
 	unsigned int max_inline_data; /* Max inline data. */
 	unsigned int max_tso_header; /* Max TSO header size. */
 	struct mlx5_txq_ibv *ibv; /* Verbs queue object. */
+	struct priv *priv; /* Back pointer to private data. */
 	struct mlx5_txq_data txq; /* Data path structure. */
 	off_t uar_mmap_offset; /* UAR mmap offset for non-primary process. */
 	volatile void *bf_reg_orig; /* Blueflame register from verbs. */
@@ -308,6 +311,12 @@ uint16_t mlx5_tx_burst_vec(void *dpdk_txq, struct rte_mbuf **pkts,
 uint16_t mlx5_rx_burst_vec(void *dpdk_txq, struct rte_mbuf **pkts,
 			   uint16_t pkts_n);
 
+/* mlx5_mr.c */
+
+void mlx5_mr_flush_local_cache(struct mlx5_mr_ctrl *mr_ctrl);
+uint32_t mlx5_rx_addr2mr_bh(struct mlx5_rxq_data *rxq, uintptr_t addr);
+uint32_t mlx5_tx_addr2mr_bh(struct mlx5_txq_data *txq, uintptr_t addr);
+
 #ifndef NDEBUG
 /**
  * Verify or set magic value in CQE.
@@ -493,14 +502,66 @@ mlx5_tx_complete(struct mlx5_txq_data *txq)
 	*txq->cq_db = rte_cpu_to_be_32(cq_ci);
 }
 
+/**
+ * Query LKey from a packet buffer for Rx. No need to flush local caches for Rx
+ * as mempool is pre-configured and static.
+ *
+ * @param rxq
+ *   Pointer to Rx queue structure.
+ * @param addr
+ *   Address to search.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
 static __rte_always_inline uint32_t
-mlx5_tx_mb2mr(struct mlx5_txq_data *txq, struct rte_mbuf *mb)
+mlx5_rx_addr2mr(struct mlx5_rxq_data *rxq, uintptr_t addr)
 {
-	(void)txq;
-	(void)mb;
-	return UINT32_MAX;
+	struct mlx5_mr_ctrl *mr_ctrl = &rxq->mr_ctrl;
+	uint32_t lkey;
+
+	/* Linear search on MR cache array. */
+	lkey = mlx5_mr_lookup_cache(mr_ctrl->cache, &mr_ctrl->mru,
+				    MLX5_MR_CACHE_N, addr);
+	if (likely(lkey != UINT32_MAX))
+		return lkey;
+	/* Take slower bottom-half (Binary Search) on miss. */
+	return mlx5_rx_addr2mr_bh(rxq, addr);
 }
 
+#define mlx5_rx_mb2mr(rxq, mb) mlx5_rx_addr2mr(rxq, (uintptr_t)((mb)->buf_addr))
+
+/**
+ * Query LKey from a packet buffer for Tx. If not found, add the mempool.
+ *
+ * @param txq
+ *   Pointer to Tx queue structure.
+ * @param addr
+ *   Address to search.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static __rte_always_inline uint32_t
+mlx5_tx_addr2mr(struct mlx5_txq_data *txq, uintptr_t addr)
+{
+	struct mlx5_mr_ctrl *mr_ctrl = &txq->mr_ctrl;
+	uint32_t lkey;
+
+	/* Check generation bit to see if there's any change on existing MRs. */
+	if (unlikely(*mr_ctrl->dev_gen_ptr != mr_ctrl->cur_gen))
+		mlx5_mr_flush_local_cache(mr_ctrl);
+	/* Linear search on MR cache array. */
+	lkey = mlx5_mr_lookup_cache(mr_ctrl->cache, &mr_ctrl->mru,
+				    MLX5_MR_CACHE_N, addr);
+	if (likely(lkey != UINT32_MAX))
+		return lkey;
+	/* Take slower bottom-half (binary search) on miss. */
+	return mlx5_tx_addr2mr_bh(txq, addr);
+}
+
+#define mlx5_tx_mb2mr(rxq, mb) mlx5_tx_addr2mr(rxq, (uintptr_t)((mb)->buf_addr))
+
 /**
  * Ring TX queue doorbell and flush the update if requested.
  *
diff --git a/drivers/net/mlx5/mlx5_rxtx_vec.h b/drivers/net/mlx5/mlx5_rxtx_vec.h
index 56c5a1b0c..76678a820 100644
--- a/drivers/net/mlx5/mlx5_rxtx_vec.h
+++ b/drivers/net/mlx5/mlx5_rxtx_vec.h
@@ -99,9 +99,13 @@ mlx5_rx_replenish_bulk_mbuf(struct mlx5_rxq_data *rxq, uint16_t n)
 		rxq->stats.rx_nombuf += n;
 		return;
 	}
-	for (i = 0; i < n; ++i)
+	for (i = 0; i < n; ++i) {
 		wq[i].addr = rte_cpu_to_be_64((uintptr_t)elts[i]->buf_addr +
 					      RTE_PKTMBUF_HEADROOM);
+		/* If there's only one MR, no need to replace LKey in WQE. */
+		if (unlikely(!IS_SINGLE_MR(rxq->mr_ctrl.cache_bh.len)))
+			wq[i].lkey = mlx5_rx_mb2mr(rxq, elts[i]);
+	}
 	rxq->rq_ci += n;
 	/* Prevent overflowing into consumed mbufs. */
 	elts_idx = rxq->rq_ci & q_mask;
diff --git a/drivers/net/mlx5/mlx5_trigger.c b/drivers/net/mlx5/mlx5_trigger.c
index 3db6c3f35..36b7c9e2f 100644
--- a/drivers/net/mlx5/mlx5_trigger.c
+++ b/drivers/net/mlx5/mlx5_trigger.c
@@ -104,9 +104,18 @@ mlx5_rxq_start(struct rte_eth_dev *dev)
 
 	for (i = 0; i != priv->rxqs_n; ++i) {
 		struct mlx5_rxq_ctrl *rxq_ctrl = mlx5_rxq_get(dev, i);
+		struct rte_mempool *mp;
 
 		if (!rxq_ctrl)
 			continue;
+		/* Pre-register Rx mempool. */
+		mp = rxq_ctrl->rxq.mp;
+		DRV_LOG(DEBUG,
+			"port %u Rx queue %u registering"
+			" mp %s having %u chunks",
+			dev->data->port_id, rxq_ctrl->idx,
+			mp->name, mp->nb_mem_chunks);
+		mlx5_mr_update_mp(dev, &rxq_ctrl->rxq.mr_ctrl, mp);
 		ret = rxq_alloc_elts(rxq_ctrl);
 		if (ret)
 			goto error;
@@ -154,6 +163,8 @@ mlx5_dev_start(struct rte_eth_dev *dev)
 			dev->data->port_id, strerror(rte_errno));
 		goto error;
 	}
+	if (rte_log_get_level(mlx5_logtype) == RTE_LOG_DEBUG)
+		mlx5_mr_dump_dev(dev);
 	ret = mlx5_rx_intr_vec_enable(dev);
 	if (ret) {
 		DRV_LOG(ERR, "port %u Rx interrupt vector creation failed",
diff --git a/drivers/net/mlx5/mlx5_txq.c b/drivers/net/mlx5/mlx5_txq.c
index a71f3d0f0..9ce6f2098 100644
--- a/drivers/net/mlx5/mlx5_txq.c
+++ b/drivers/net/mlx5/mlx5_txq.c
@@ -804,6 +804,13 @@ mlx5_txq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		rte_errno = ENOMEM;
 		return NULL;
 	}
+	if (mlx5_mr_btree_init(&tmpl->txq.mr_ctrl.cache_bh,
+			       MLX5_MR_BTREE_CACHE_N, socket)) {
+		/* rte_errno is already set. */
+		goto error;
+	}
+	/* Save pointer of global generation number to check memory event. */
+	tmpl->txq.mr_ctrl.dev_gen_ptr = &priv->mr.dev_gen;
 	assert(desc > MLX5_TX_COMP_THRESH);
 	tmpl->txq.offloads = conf->offloads;
 	tmpl->priv = priv;
@@ -823,6 +830,9 @@ mlx5_txq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		idx, rte_atomic32_read(&tmpl->refcnt));
 	LIST_INSERT_HEAD(&priv->txqsctrl, tmpl, next);
 	return tmpl;
+error:
+	rte_free(tmpl);
+	return NULL;
 }
 
 /**
@@ -882,6 +892,7 @@ mlx5_txq_release(struct rte_eth_dev *dev, uint16_t idx)
 			dev->data->port_id, txq->idx,
 			rte_atomic32_read(&txq->refcnt));
 		txq_free_elts(txq);
+		mlx5_mr_btree_free(&txq->txq.mr_ctrl.cache_bh);
 		LIST_REMOVE(txq, next);
 		rte_free(txq);
 		(*priv->txqs)[idx] = NULL;
