diff --git a/nightly/conf/nightly.conf b/nightly/conf/nightly.conf
index eac93b0c7..d0bdffa5b 100644
--- a/nightly/conf/nightly.conf
+++ b/nightly/conf/nightly.conf
@@ -3,26 +3,26 @@
 ABT_DETAILS="x86_64"
 ABT_JOBS=5
 ABT_KERNELS="  \
-5.2.5          \
+5.2.6          \
 5.1.21-nc      \
 5.0.21-nc      \
 4.20.17-nc     \
-4.19.63-nc     \
+4.19.64-nc     \
 4.18.20-nc     \
 4.17.19-nc     \
 4.16.18-nc     \
 4.15.18-nc     \
-4.14.135-nc    \
+4.14.136-nc    \
 4.13.16-nc     \
 4.12.14-nc     \
 4.11.12-nc     \
 4.10.17-nc     \
-4.9.186-nc     \
+4.9.187-nc     \
 4.8.17-nc      \
 4.7.10-nc      \
 4.6.7-nc       \
 4.5.7-nc       \
-4.4.186-nc     \
+4.4.187-nc     \
 4.3.6-nc       \
 4.2.8-nc       \
 4.1.52-nc      \
diff --git a/scst/include/scst.h b/scst/include/scst.h
index 24a40fcaa..35af18bd8 100644
--- a/scst/include/scst.h
+++ b/scst/include/scst.h
@@ -2317,6 +2317,9 @@ struct scst_cmd {
 	/* Set by WRITE VERIFY commands to trigger a verify after write */
 	unsigned int do_verify:1;
 
+	/* For debugging purposes. */
+	unsigned int owns_refcnt:1;
+
 	/**************************************************************/
 
 	/* cmd's async flags */
diff --git a/scst/src/scst_lib.c b/scst/src/scst_lib.c
index 32179653e..b5b7289ef 100644
--- a/scst/src/scst_lib.c
+++ b/scst/src/scst_lib.c
@@ -4578,7 +4578,7 @@ static void scst_tgt_dev_free_workfn(struct work_struct *work)
 	scst_put(a);
 }
 
-void scst_free_tgt_dev_rcu(struct rcu_head *rcu)
+static void scst_free_tgt_dev_rcu(struct rcu_head *rcu)
 {
 	struct scst_tgt_dev *tgt_dev = container_of(rcu, typeof(*tgt_dev), rcu);
 
@@ -5541,6 +5541,12 @@ void scst_nexus_loss(struct scst_tgt_dev *tgt_dev, bool queue_UA)
 	return;
 }
 
+void scst_tgt_dev_dec_cmd_count(struct scst_tgt_dev *tgt_dev)
+{
+	if (atomic_dec_return(&tgt_dev->tgt_dev_cmd_count) == 0)
+		call_rcu(&tgt_dev->rcu, scst_free_tgt_dev_rcu);
+}
+
 static void scst_del_tgt_dev(struct scst_tgt_dev *tgt_dev)
 {
 	struct scst_tgt_template *tgtt = tgt_dev->tgtt;
@@ -5563,8 +5569,7 @@ static void scst_del_tgt_dev(struct scst_tgt_dev *tgt_dev)
 	if (tgtt->get_initiator_port_transport_id == NULL)
 		dev->not_pr_supporting_tgt_devs_num--;
 
-	if (atomic_dec_return(&tgt_dev->tgt_dev_cmd_count) == 0)
-		call_rcu(&tgt_dev->rcu, scst_free_tgt_dev_rcu);
+	scst_tgt_dev_dec_cmd_count(tgt_dev);
 }
 
 /*
diff --git a/scst/src/scst_priv.h b/scst/src/scst_priv.h
index 84788dd89..9864e6971 100644
--- a/scst/src/scst_priv.h
+++ b/scst/src/scst_priv.h
@@ -382,7 +382,7 @@ void scst_check_reassign_sessions(void);
 int scst_sess_alloc_tgt_devs(struct scst_session *sess);
 void scst_sess_free_tgt_devs(struct scst_session *sess);
 struct scst_tgt_dev *scst_lookup_tgt_dev(struct scst_session *sess, u64 lun);
-void scst_free_tgt_dev_rcu(struct rcu_head *rcu);
+void scst_tgt_dev_dec_cmd_count(struct scst_tgt_dev *tgt_dev);
 void scst_nexus_loss(struct scst_tgt_dev *tgt_dev, bool queue_UA);
 
 #define SCST_ADD_LUN_READ_ONLY	1
diff --git a/scst/src/scst_targ.c b/scst/src/scst_targ.c
index a0918ae71..bee0ae2de 100644
--- a/scst/src/scst_targ.c
+++ b/scst/src/scst_targ.c
@@ -4504,8 +4504,8 @@ static int scst_pre_xmit_response1(struct scst_cmd *cmd)
 		 * latency, so we should decrement them after cmd completed.
 		 */
 		smp_mb__before_atomic_dec();
-		if (atomic_dec_return(&cmd->tgt_dev->tgt_dev_cmd_count) == 0)
-			call_rcu(&cmd->tgt_dev->rcu, scst_free_tgt_dev_rcu);
+		cmd->owns_refcnt = false;
+		scst_tgt_dev_dec_cmd_count(cmd->tgt_dev);
 		percpu_ref_put(&cmd->dev->refcnt);
 #ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
 		atomic_dec(&cmd->dev->dev_cmd_count);
@@ -4694,6 +4694,8 @@ static int scst_finish_cmd(struct scst_cmd *cmd)
 
 	TRACE_ENTRY();
 
+	WARN_ON_ONCE(cmd->owns_refcnt);
+
 	if (unlikely(cmd->delivery_status != SCST_CMD_DELIVERY_SUCCESS)) {
 		if ((cmd->tgt_dev != NULL) &&
 		    (cmd->status == SAM_STAT_CHECK_CONDITION) &&
@@ -4997,6 +4999,9 @@ static int scst_translate_lun(struct scst_cmd *cmd)
 
 		rcu_read_lock();
 		tgt_dev = scst_lookup_tgt_dev(cmd->sess, cmd->lun);
+		if (tgt_dev &&
+		    !atomic_inc_not_zero(&tgt_dev->tgt_dev_cmd_count))
+			tgt_dev = NULL;
 		rcu_read_unlock();
 
 		if (tgt_dev) {
@@ -5015,6 +5020,7 @@ static int scst_translate_lun(struct scst_cmd *cmd)
 					"the device will not be visible remotely",
 					(unsigned long long)cmd->lun);
 				nul_dev = true;
+				scst_tgt_dev_dec_cmd_count(tgt_dev);
 			}
 		}
 		if (unlikely(res != 0)) {
@@ -5143,7 +5149,7 @@ static int __scst_init_cmd(struct scst_cmd *cmd)
 
 		scst_set_cmd_state(cmd, SCST_CMD_STATE_PARSE);
 
-		cnt = atomic_inc_return(&tgt_dev->tgt_dev_cmd_count) - 1;
+		cnt = atomic_read(&tgt_dev->tgt_dev_cmd_count) - 1;
 		if (unlikely(cnt > dev->max_tgt_dev_commands)) {
 			TRACE(TRACE_FLOW_CONTROL,
 				"Too many pending commands (%d) in "
@@ -5153,6 +5159,7 @@ static int __scst_init_cmd(struct scst_cmd *cmd)
 			failure = true;
 		}
 
+		cmd->owns_refcnt = true;
 		percpu_ref_get(&dev->refcnt);
 #ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
 		atomic_inc(&dev->dev_cmd_count);