diff --git a/drivers/infiniband/hw/hfi1/ipoib_tx.c b/drivers/infiniband/hw/hfi1/ipoib_tx.c
index 8973a081d641..e7d831330278 100644
--- a/drivers/infiniband/hw/hfi1/ipoib_tx.c
+++ b/drivers/infiniband/hw/hfi1/ipoib_tx.c
@@ -215,11 +215,11 @@ static int hfi1_ipoib_build_ulp_payload(struct ipoib_txreq *tx,
 		const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 
 		ret = sdma_txadd_page(dd,
-				      NULL,
 				      txreq,
 				      skb_frag_page(frag),
 				      frag->bv_offset,
-				      skb_frag_size(frag));
+				      skb_frag_size(frag),
+				      NULL, NULL, NULL);
 		if (unlikely(ret))
 			break;
 	}
diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.c b/drivers/infiniband/hw/hfi1/mmu_rb.c
index 1cea8b0c78e0..a864423c256d 100644
--- a/drivers/infiniband/hw/hfi1/mmu_rb.c
+++ b/drivers/infiniband/hw/hfi1/mmu_rb.c
@@ -19,8 +19,7 @@ static int mmu_notifier_range_start(struct mmu_notifier *,
 		const struct mmu_notifier_range *);
 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *,
 					   unsigned long, unsigned long);
-static void do_remove(struct mmu_rb_handler *handler,
-		      struct list_head *del_list);
+static void release_immediate(struct kref *refcount);
 static void handle_remove(struct work_struct *work);
 
 static const struct mmu_notifier_ops mn_opts = {
@@ -106,7 +105,11 @@ void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
 	}
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	do_remove(handler, &del_list);
+	while (!list_empty(&del_list)) {
+		rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
+		list_del(&rbnode->list);
+		kref_put(&rbnode->refcount, release_immediate);
+	}
 
 	/* Now the mm may be freed. */
 	mmdrop(handler->mn.mm);
@@ -134,12 +137,6 @@ int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
 	}
 	__mmu_int_rb_insert(mnode, &handler->root);
 	list_add_tail(&mnode->list, &handler->lru_list);
-
-	ret = handler->ops->insert(handler->ops_arg, mnode);
-	if (ret) {
-		__mmu_int_rb_remove(mnode, &handler->root);
-		list_del(&mnode->list); /* remove from LRU list */
-	}
 	mnode->handler = handler;
 unlock:
 	spin_unlock_irqrestore(&handler->lock, flags);
@@ -183,6 +180,48 @@ static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
 	return node;
 }
 
+/*
+ * Must NOT call while holding mnode->handler->lock.
+ * mnode->handler->ops->remove() may sleep and mnode->handler->lock is a
+ * spinlock.
+ */
+static void release_immediate(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	mnode->handler->ops->remove(mnode->handler->ops_arg, mnode);
+}
+
+/* Caller must hold mnode->handler->lock */
+static void release_nolock(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	list_move(&mnode->list, &mnode->handler->del_list);
+	queue_work(mnode->handler->wq, &mnode->handler->del_work);
+}
+
+/*
+ * struct mmu_rb_node->refcount kref_put() callback.
+ * Adds mmu_rb_node to mmu_rb_node->handler->del_list and queues
+ * handler->del_work on handler->wq.
+ * Does not remove mmu_rb_node from handler->lru_list or handler->rb_root.
+ * Acquires mmu_rb_node->handler->lock; do not call while already holding
+ * handler->lock.
+ */
+void hfi1_mmu_rb_release(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	struct mmu_rb_handler *handler = mnode->handler;
+	unsigned long flags;
+
+	spin_lock_irqsave(&handler->lock, flags);
+	list_move(&mnode->list, &mnode->handler->del_list);
+	spin_unlock_irqrestore(&handler->lock, flags);
+	queue_work(handler->wq, &handler->del_work);
+}
+
 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 {
 	struct mmu_rb_node *rbnode, *ptr;
@@ -197,6 +236,10 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 
 	spin_lock_irqsave(&handler->lock, flags);
 	list_for_each_entry_safe(rbnode, ptr, &handler->lru_list, list) {
+		/* refcount == 1 implies mmu_rb_handler has only rbnode ref */
+		if (kref_read(&rbnode->refcount) > 1)
+			continue;
+
 		if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
 					&stop)) {
 			__mmu_int_rb_remove(rbnode, &handler->root);
@@ -209,7 +252,7 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 	spin_unlock_irqrestore(&handler->lock, flags);
 
 	list_for_each_entry_safe(rbnode, ptr, &del_list, list) {
-		handler->ops->remove(handler->ops_arg, rbnode);
+		kref_put(&rbnode->refcount, release_immediate);
 	}
 }
 
@@ -221,7 +264,6 @@ static int mmu_notifier_range_start(struct mmu_notifier *mn,
 	struct rb_root_cached *root = &handler->root;
 	struct mmu_rb_node *node, *ptr = NULL;
 	unsigned long flags;
-	bool added = false;
 
 	spin_lock_irqsave(&handler->lock, flags);
 	for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
@@ -230,38 +272,16 @@ static int mmu_notifier_range_start(struct mmu_notifier *mn,
 		ptr = __mmu_int_rb_iter_next(node, range->start,
 					     range->end - 1);
 		trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
-		if (handler->ops->invalidate(handler->ops_arg, node)) {
-			__mmu_int_rb_remove(node, root);
-			/* move from LRU list to delete list */
-			list_move(&node->list, &handler->del_list);
-			added = true;
-		}
+		/* Remove from rb tree and lru_list. */
+		__mmu_int_rb_remove(node, root);
+		list_del_init(&node->list);
+		kref_put(&node->refcount, release_nolock);
 	}
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	if (added)
-		queue_work(handler->wq, &handler->del_work);
-
 	return 0;
 }
 
-/*
- * Call the remove function for the given handler and the list.  This
- * is expected to be called with a delete list extracted from handler.
- * The caller should not be holding the handler lock.
- */
-static void do_remove(struct mmu_rb_handler *handler,
-		      struct list_head *del_list)
-{
-	struct mmu_rb_node *node;
-
-	while (!list_empty(del_list)) {
-		node = list_first_entry(del_list, struct mmu_rb_node, list);
-		list_del(&node->list);
-		handler->ops->remove(handler->ops_arg, node);
-	}
-}
-
 /*
  * Work queue function to remove all nodes that have been queued up to
  * be removed.  The key feature is that mm->mmap_lock is not being held
@@ -274,11 +294,16 @@ static void handle_remove(struct work_struct *work)
 						del_work);
 	struct list_head del_list;
 	unsigned long flags;
+	struct mmu_rb_node *node;
 
 	/* remove anything that is queued to get removed */
 	spin_lock_irqsave(&handler->lock, flags);
 	list_replace_init(&handler->del_list, &del_list);
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	do_remove(handler, &del_list);
+	while (!list_empty(&del_list)) {
+		node = list_first_entry(&del_list, struct mmu_rb_node, list);
+		list_del(&node->list);
+		handler->ops->remove(handler->ops_arg, node);
+	}
 }
diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.h b/drivers/infiniband/hw/hfi1/mmu_rb.h
index c4da064188c9..82c505a04fc6 100644
--- a/drivers/infiniband/hw/hfi1/mmu_rb.h
+++ b/drivers/infiniband/hw/hfi1/mmu_rb.h
@@ -16,6 +16,7 @@ struct mmu_rb_node {
 	struct rb_node node;
 	struct mmu_rb_handler *handler;
 	struct list_head list;
+	struct kref refcount;
 };
 
 /*
@@ -61,6 +62,8 @@ int hfi1_mmu_rb_register(void *ops_arg,
 void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler);
 int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
 		       struct mmu_rb_node *mnode);
+void hfi1_mmu_rb_release(struct kref *refcount);
+
 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg);
 struct mmu_rb_node *hfi1_mmu_rb_get_first(struct mmu_rb_handler *handler,
 					  unsigned long addr,
diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index bb2552dd29c1..26c62162759b 100644
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/drivers/infiniband/hw/hfi1/sdma.c
@@ -1593,7 +1593,20 @@ static inline void sdma_unmap_desc(
 	struct hfi1_devdata *dd,
 	struct sdma_desc *descp)
 {
-	system_descriptor_complete(dd, descp);
+	switch (sdma_mapping_type(descp)) {
+	case SDMA_MAP_SINGLE:
+		dma_unmap_single(&dd->pcidev->dev, sdma_mapping_addr(descp),
+				 sdma_mapping_len(descp), DMA_TO_DEVICE);
+		break;
+	case SDMA_MAP_PAGE:
+		dma_unmap_page(&dd->pcidev->dev, sdma_mapping_addr(descp),
+			       sdma_mapping_len(descp), DMA_TO_DEVICE);
+		break;
+	}
+
+	if (descp->pinning_ctx && descp->ctx_put)
+		descp->ctx_put(descp->pinning_ctx);
+	descp->pinning_ctx = NULL;
 }
 
 /*
@@ -3113,8 +3126,8 @@ int ext_coal_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx,
 
 		/* Add descriptor for coalesce buffer */
 		tx->desc_limit = MAX_DESC;
-		return _sdma_txadd_daddr(dd, SDMA_MAP_SINGLE, NULL, tx,
-					 addr, tx->tlen);
+		return _sdma_txadd_daddr(dd, SDMA_MAP_SINGLE, tx,
+					 addr, tx->tlen, NULL, NULL, NULL);
 	}
 
 	return 1;
@@ -3157,9 +3170,9 @@ int _pad_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 	make_tx_sdma_desc(
 		tx,
 		SDMA_MAP_NONE,
-		NULL,
 		dd->sdma_pad_phys,
-		sizeof(u32) - (tx->packet_len & (sizeof(u32) - 1)));
+		sizeof(u32) - (tx->packet_len & (sizeof(u32) - 1)),
+		NULL, NULL, NULL);
 	tx->num_desc++;
 	_sdma_close_tx(dd, tx);
 	return rval;
diff --git a/drivers/infiniband/hw/hfi1/sdma.h b/drivers/infiniband/hw/hfi1/sdma.h
index 95aaec14c6c2..7fdebab202c4 100644
--- a/drivers/infiniband/hw/hfi1/sdma.h
+++ b/drivers/infiniband/hw/hfi1/sdma.h
@@ -594,9 +594,11 @@ static inline dma_addr_t sdma_mapping_addr(struct sdma_desc *d)
 static inline void make_tx_sdma_desc(
 	struct sdma_txreq *tx,
 	int type,
-	void *pinning_ctx,
 	dma_addr_t addr,
-	size_t len)
+	size_t len,
+	void *pinning_ctx,
+	void (*ctx_get)(void *),
+	void (*ctx_put)(void *))
 {
 	struct sdma_desc *desc = &tx->descp[tx->num_desc];
 
@@ -613,7 +615,11 @@ static inline void make_tx_sdma_desc(
 				<< SDMA_DESC0_PHY_ADDR_SHIFT) |
 			(((u64)len & SDMA_DESC0_BYTE_COUNT_MASK)
 				<< SDMA_DESC0_BYTE_COUNT_SHIFT);
+
 	desc->pinning_ctx = pinning_ctx;
+	desc->ctx_put = ctx_put;
+	if (pinning_ctx && ctx_get)
+		ctx_get(pinning_ctx);
 }
 
 /* helper to extend txreq */
@@ -645,18 +651,20 @@ static inline void _sdma_close_tx(struct hfi1_devdata *dd,
 static inline int _sdma_txadd_daddr(
 	struct hfi1_devdata *dd,
 	int type,
-	void *pinning_ctx,
 	struct sdma_txreq *tx,
 	dma_addr_t addr,
-	u16 len)
+	u16 len,
+	void *pinning_ctx,
+	void (*ctx_get)(void *),
+	void (*ctx_put)(void *))
 {
 	int rval = 0;
 
 	make_tx_sdma_desc(
 		tx,
 		type,
-		pinning_ctx,
-		addr, len);
+		addr, len,
+		pinning_ctx, ctx_get, ctx_put);
 	WARN_ON(len > tx->tlen);
 	tx->num_desc++;
 	tx->tlen -= len;
@@ -676,11 +684,18 @@ static inline int _sdma_txadd_daddr(
 /**
  * sdma_txadd_page() - add a page to the sdma_txreq
  * @dd: the device to use for mapping
- * @pinning_ctx: context to be released at descriptor retirement
  * @tx: tx request to which the page is added
  * @page: page to map
  * @offset: offset within the page
  * @len: length in bytes
+ * @pinning_ctx: context to be stored on struct sdma_desc .pinning_ctx. Not
+ *               added if coalesce buffer is used. E.g. pointer to pinned-page
+ *               cache entry for the sdma_desc.
+ * @ctx_get: optional function to take reference to @pinning_ctx. Not called if
+ *           @pinning_ctx is NULL.
+ * @ctx_put: optional function to release reference to @pinning_ctx after
+ *           sdma_desc completes. May be called in interrupt context so must
+ *           not sleep. Not called if @pinning_ctx is NULL.
  *
  * This is used to add a page/offset/length descriptor.
  *
@@ -692,11 +707,13 @@ static inline int _sdma_txadd_daddr(
  */
 static inline int sdma_txadd_page(
 	struct hfi1_devdata *dd,
-	void *pinning_ctx,
 	struct sdma_txreq *tx,
 	struct page *page,
 	unsigned long offset,
-	u16 len)
+	u16 len,
+	void *pinning_ctx,
+	void (*ctx_get)(void *),
+	void (*ctx_put)(void *))
 {
 	dma_addr_t addr;
 	int rval;
@@ -720,7 +737,8 @@ static inline int sdma_txadd_page(
 		return -ENOSPC;
 	}
 
-	return _sdma_txadd_daddr(dd, SDMA_MAP_PAGE, pinning_ctx, tx, addr, len);
+	return _sdma_txadd_daddr(dd, SDMA_MAP_PAGE, tx, addr, len,
+				 pinning_ctx, ctx_get, ctx_put);
 }
 
 /**
@@ -754,8 +772,8 @@ static inline int sdma_txadd_daddr(
 			return rval;
 	}
 
-	return _sdma_txadd_daddr(dd, SDMA_MAP_NONE, NULL, tx,
-				 addr, len);
+	return _sdma_txadd_daddr(dd, SDMA_MAP_NONE, tx, addr, len,
+				 NULL, NULL, NULL);
 }
 
 /**
@@ -801,7 +819,8 @@ static inline int sdma_txadd_kvaddr(
 		return -ENOSPC;
 	}
 
-	return _sdma_txadd_daddr(dd, SDMA_MAP_SINGLE, NULL, tx, addr, len);
+	return _sdma_txadd_daddr(dd, SDMA_MAP_SINGLE, tx, addr, len,
+				 NULL, NULL, NULL);
 }
 
 struct iowait_work;
@@ -1034,6 +1053,4 @@ u16 sdma_get_descq_cnt(void);
 extern uint mod_num_sdma;
 
 void sdma_update_lmc(struct hfi1_devdata *dd, u64 mask, u32 lid);
-
-void system_descriptor_complete(struct hfi1_devdata *dd, struct sdma_desc *descp);
 #endif
diff --git a/drivers/infiniband/hw/hfi1/sdma_txreq.h b/drivers/infiniband/hw/hfi1/sdma_txreq.h
index fad946cb5e0d..85ae7293c274 100644
--- a/drivers/infiniband/hw/hfi1/sdma_txreq.h
+++ b/drivers/infiniband/hw/hfi1/sdma_txreq.h
@@ -20,6 +20,8 @@ struct sdma_desc {
 	/* private:  don't use directly */
 	u64 qw[2];
 	void *pinning_ctx;
+	/* Release reference to @pinning_ctx. May be called in interrupt context. Must not sleep. */
+	void (*ctx_put)(void *ctx);
 };
 
 /**
diff --git a/drivers/infiniband/hw/hfi1/user_sdma.c b/drivers/infiniband/hw/hfi1/user_sdma.c
index ae58b48afe07..02bd62b857b7 100644
--- a/drivers/infiniband/hw/hfi1/user_sdma.c
+++ b/drivers/infiniband/hw/hfi1/user_sdma.c
@@ -62,18 +62,14 @@ static int defer_packet_queue(
 static void activate_packet_queue(struct iowait *wait, int reason);
 static bool sdma_rb_filter(struct mmu_rb_node *node, unsigned long addr,
 			   unsigned long len);
-static int sdma_rb_insert(void *arg, struct mmu_rb_node *mnode);
 static int sdma_rb_evict(void *arg, struct mmu_rb_node *mnode,
 			 void *arg2, bool *stop);
 static void sdma_rb_remove(void *arg, struct mmu_rb_node *mnode);
-static int sdma_rb_invalidate(void *arg, struct mmu_rb_node *mnode);
 
 static struct mmu_rb_ops sdma_rb_ops = {
 	.filter = sdma_rb_filter,
-	.insert = sdma_rb_insert,
 	.evict = sdma_rb_evict,
 	.remove = sdma_rb_remove,
-	.invalidate = sdma_rb_invalidate
 };
 
 static int add_system_pages_to_sdma_packet(struct user_sdma_request *req,
@@ -247,14 +243,14 @@ int hfi1_user_sdma_free_queues(struct hfi1_filedata *fd,
 		spin_unlock(&fd->pq_rcu_lock);
 		synchronize_srcu(&fd->pq_srcu);
 		/* at this point there can be no more new requests */
-		if (pq->handler)
-			hfi1_mmu_rb_unregister(pq->handler);
 		iowait_sdma_drain(&pq->busy);
 		/* Wait until all requests have been freed. */
 		wait_event_interruptible(
 			pq->wait,
 			!atomic_read(&pq->n_reqs));
 		kfree(pq->reqs);
+		if (pq->handler)
+			hfi1_mmu_rb_unregister(pq->handler);
 		bitmap_free(pq->req_in_use);
 		kmem_cache_destroy(pq->txreq_cache);
 		flush_pq_iowait(pq);
@@ -1275,25 +1271,17 @@ static void free_system_node(struct sdma_mmu_node *node)
 	kfree(node);
 }
 
-static inline void acquire_node(struct sdma_mmu_node *node)
-{
-	atomic_inc(&node->refcount);
-	WARN_ON(atomic_read(&node->refcount) < 0);
-}
-
-static inline void release_node(struct mmu_rb_handler *handler,
-				struct sdma_mmu_node *node)
-{
-	atomic_dec(&node->refcount);
-	WARN_ON(atomic_read(&node->refcount) < 0);
-}
-
+/*
+ * kref_get()'s an additional kref on the returned rb_node to prevent rb_node
+ * from being released until after rb_node is assigned to an SDMA descriptor
+ * (struct sdma_desc) under add_system_iovec_to_sdma_packet(), even if the
+ * virtual address range for rb_node is invalidated between now and then.
+ */
 static struct sdma_mmu_node *find_system_node(struct mmu_rb_handler *handler,
 					      unsigned long start,
 					      unsigned long end)
 {
 	struct mmu_rb_node *rb_node;
-	struct sdma_mmu_node *node;
 	unsigned long flags;
 
 	spin_lock_irqsave(&handler->lock, flags);
@@ -1302,11 +1290,12 @@ static struct sdma_mmu_node *find_system_node(struct mmu_rb_handler *handler,
 		spin_unlock_irqrestore(&handler->lock, flags);
 		return NULL;
 	}
-	node = container_of(rb_node, struct sdma_mmu_node, rb);
-	acquire_node(node);
+
+	/* "safety" kref to prevent release before add_system_iovec_to_sdma_packet() */
+	kref_get(&rb_node->refcount);
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	return node;
+	return container_of(rb_node, struct sdma_mmu_node, rb);
 }
 
 static int pin_system_pages(struct user_sdma_request *req,
@@ -1355,6 +1344,13 @@ static int pin_system_pages(struct user_sdma_request *req,
 	return 0;
 }
 
+/*
+ * kref refcount on *node_p will be 2 on successful addition: one kref from
+ * kref_init() for mmu_rb_handler and one kref to prevent *node_p from being
+ * released until after *node_p is assigned to an SDMA descriptor (struct
+ * sdma_desc) under add_system_iovec_to_sdma_packet(), even if the virtual
+ * address range for *node_p is invalidated between now and then.
+ */
 static int add_system_pinning(struct user_sdma_request *req,
 			      struct sdma_mmu_node **node_p,
 			      unsigned long start, unsigned long len)
@@ -1368,6 +1364,12 @@ static int add_system_pinning(struct user_sdma_request *req,
 	if (!node)
 		return -ENOMEM;
 
+	/* First kref "moves" to mmu_rb_handler */
+	kref_init(&node->rb.refcount);
+
+	/* "safety" kref to prevent release before add_system_iovec_to_sdma_packet() */
+	kref_get(&node->rb.refcount);
+
 	node->pq = pq;
 	ret = pin_system_pages(req, start, len, node, PFN_DOWN(len));
 	if (ret == 0) {
@@ -1431,15 +1433,15 @@ static int get_system_cache_entry(struct user_sdma_request *req,
 			return 0;
 		}
 
-		SDMA_DBG(req, "prepend: node->rb.addr %lx, node->refcount %d",
-			 node->rb.addr, atomic_read(&node->refcount));
+		SDMA_DBG(req, "prepend: node->rb.addr %lx, node->rb.refcount %d",
+			 node->rb.addr, kref_read(&node->rb.refcount));
 		prepend_len = node->rb.addr - start;
 
 		/*
 		 * This node will not be returned, instead a new node
 		 * will be. So release the reference.
 		 */
-		release_node(handler, node);
+		kref_put(&node->rb.refcount, hfi1_mmu_rb_release);
 
 		/* Prepend a node to cover the beginning of the allocation */
 		ret = add_system_pinning(req, node_p, start, prepend_len);
@@ -1451,6 +1453,20 @@ static int get_system_cache_entry(struct user_sdma_request *req,
 	}
 }
 
+static void sdma_mmu_rb_node_get(void *ctx)
+{
+	struct mmu_rb_node *node = ctx;
+
+	kref_get(&node->refcount);
+}
+
+static void sdma_mmu_rb_node_put(void *ctx)
+{
+	struct sdma_mmu_node *node = ctx;
+
+	kref_put(&node->rb.refcount, hfi1_mmu_rb_release);
+}
+
 static int add_mapping_to_sdma_packet(struct user_sdma_request *req,
 				      struct user_sdma_txreq *tx,
 				      struct sdma_mmu_node *cache_entry,
@@ -1494,9 +1510,12 @@ static int add_mapping_to_sdma_packet(struct user_sdma_request *req,
 			ctx = cache_entry;
 		}
 
-		ret = sdma_txadd_page(pq->dd, ctx, &tx->txreq,
+		ret = sdma_txadd_page(pq->dd, &tx->txreq,
 				      cache_entry->pages[page_index],
-				      page_offset, from_this_page);
+				      page_offset, from_this_page,
+				      ctx,
+				      sdma_mmu_rb_node_get,
+				      sdma_mmu_rb_node_put);
 		if (ret) {
 			/*
 			 * When there's a failure, the entire request is freed by
@@ -1518,8 +1537,6 @@ static int add_system_iovec_to_sdma_packet(struct user_sdma_request *req,
 					   struct user_sdma_iovec *iovec,
 					   size_t from_this_iovec)
 {
-	struct mmu_rb_handler *handler = req->pq->handler;
-
 	while (from_this_iovec > 0) {
 		struct sdma_mmu_node *cache_entry;
 		size_t from_this_cache_entry;
@@ -1540,15 +1557,15 @@ static int add_system_iovec_to_sdma_packet(struct user_sdma_request *req,
 
 		ret = add_mapping_to_sdma_packet(req, tx, cache_entry, start,
 						 from_this_cache_entry);
+
+		/*
+		 * Done adding cache_entry to zero or more sdma_desc. Can
+		 * kref_put() the "safety" kref taken under
+		 * get_system_cache_entry().
+		 */
+		kref_put(&cache_entry->rb.refcount, hfi1_mmu_rb_release);
+
 		if (ret) {
-			/*
-			 * We're guaranteed that there will be no descriptor
-			 * completion callback that releases this node
-			 * because only the last descriptor referencing it
-			 * has a context attached, and a failure means the
-			 * last descriptor was never added.
-			 */
-			release_node(handler, cache_entry);
 			SDMA_DBG(req, "add system segment failed %d", ret);
 			return ret;
 		}
@@ -1599,42 +1616,12 @@ static int add_system_pages_to_sdma_packet(struct user_sdma_request *req,
 	return 0;
 }
 
-void system_descriptor_complete(struct hfi1_devdata *dd,
-				struct sdma_desc *descp)
-{
-	switch (sdma_mapping_type(descp)) {
-	case SDMA_MAP_SINGLE:
-		dma_unmap_single(&dd->pcidev->dev, sdma_mapping_addr(descp),
-				 sdma_mapping_len(descp), DMA_TO_DEVICE);
-		break;
-	case SDMA_MAP_PAGE:
-		dma_unmap_page(&dd->pcidev->dev, sdma_mapping_addr(descp),
-			       sdma_mapping_len(descp), DMA_TO_DEVICE);
-		break;
-	}
-
-	if (descp->pinning_ctx) {
-		struct sdma_mmu_node *node = descp->pinning_ctx;
-
-		release_node(node->rb.handler, node);
-	}
-}
-
 static bool sdma_rb_filter(struct mmu_rb_node *node, unsigned long addr,
 			   unsigned long len)
 {
 	return (bool)(node->addr == addr);
 }
 
-static int sdma_rb_insert(void *arg, struct mmu_rb_node *mnode)
-{
-	struct sdma_mmu_node *node =
-		container_of(mnode, struct sdma_mmu_node, rb);
-
-	atomic_inc(&node->refcount);
-	return 0;
-}
-
 /*
  * Return 1 to remove the node from the rb tree and call the remove op.
  *
@@ -1647,10 +1634,6 @@ static int sdma_rb_evict(void *arg, struct mmu_rb_node *mnode,
 		container_of(mnode, struct sdma_mmu_node, rb);
 	struct evict_data *evict_data = evict_arg;
 
-	/* is this node still being used? */
-	if (atomic_read(&node->refcount))
-		return 0; /* keep this node */
-
 	/* this node will be evicted, add its pages to our count */
 	evict_data->cleared += node->npages;
 
@@ -1668,13 +1651,3 @@ static void sdma_rb_remove(void *arg, struct mmu_rb_node *mnode)
 
 	free_system_node(node);
 }
-
-static int sdma_rb_invalidate(void *arg, struct mmu_rb_node *mnode)
-{
-	struct sdma_mmu_node *node =
-		container_of(mnode, struct sdma_mmu_node, rb);
-
-	if (!atomic_read(&node->refcount))
-		return 1;
-	return 0;
-}
diff --git a/drivers/infiniband/hw/hfi1/user_sdma.h b/drivers/infiniband/hw/hfi1/user_sdma.h
index a241836371dc..548347d4c5bc 100644
--- a/drivers/infiniband/hw/hfi1/user_sdma.h
+++ b/drivers/infiniband/hw/hfi1/user_sdma.h
@@ -104,7 +104,6 @@ struct hfi1_user_sdma_comp_q {
 struct sdma_mmu_node {
 	struct mmu_rb_node rb;
 	struct hfi1_user_sdma_pkt_q *pq;
-	atomic_t refcount;
 	struct page **pages;
 	unsigned int npages;
 };
diff --git a/drivers/infiniband/hw/hfi1/vnic_sdma.c b/drivers/infiniband/hw/hfi1/vnic_sdma.c
index 727eedfba332..cc6324d2d1dd 100644
--- a/drivers/infiniband/hw/hfi1/vnic_sdma.c
+++ b/drivers/infiniband/hw/hfi1/vnic_sdma.c
@@ -64,11 +64,11 @@ static noinline int build_vnic_ulp_payload(struct sdma_engine *sde,
 
 		/* combine physically continuous fragments later? */
 		ret = sdma_txadd_page(sde->dd,
-				      NULL,
 				      &tx->txreq,
 				      skb_frag_page(frag),
 				      skb_frag_off(frag),
-				      skb_frag_size(frag));
+				      skb_frag_size(frag),
+				      NULL, NULL, NULL);
 		if (unlikely(ret))
 			goto bail_txadd;
 	}
