diff --git a/executer/kernel/mcctrl/control.c b/executer/kernel/mcctrl/control.c
index 3700c3d0..f3022733 100644
--- a/executer/kernel/mcctrl/control.c
+++ b/executer/kernel/mcctrl/control.c
@@ -476,25 +476,33 @@ out:
 
 static DECLARE_WAIT_QUEUE_HEAD(signalq);
 
+struct mcctrl_signal_desc {
+	struct mcctrl_signal msig;
+	struct mcctrl_wakeup_desc wakeup;
+	void *addrs[1];
+};
+
 static long mcexec_send_signal(ihk_os_t os, struct signal_desc *sigparam)
 {
 	struct ikc_scd_packet isp;
 	struct mcctrl_channel *c;
 	struct mcctrl_usrdata *usrdata = ihk_host_os_get_usrdata(os);
 	struct signal_desc sig;
-	struct mcctrl_signal msig[2];
+	struct mcctrl_signal_desc *desc;
 	struct mcctrl_signal *msigp;
-	int rc;
+	int rc, do_free;
 
 	if (copy_from_user(&sig, sigparam, sizeof(struct signal_desc))) {
 		return -EFAULT;
 	}
 
-	msigp = msig;
-	if(((unsigned long)msig & 0xfffffffffffff000L) !=
-	   ((unsigned long)(msig + 1) & 0xfffffffffffff000L))
-		msigp++;
-	memset(msigp, '\0', sizeof msig);
+	desc = kmalloc(sizeof(*desc), GFP_KERNEL);
+	if (!desc) {
+		return -ENOMEM;
+	}
+
+	msigp = &desc->msig;
+	memset(msigp, '\0', sizeof(*msigp));
 	msigp->sig = sig.sig;
 	msigp->pid = sig.pid;
 	msigp->tid = sig.tid;
@@ -506,25 +514,19 @@ static long mcexec_send_signal(ihk_os_t os, struct signal_desc *sigparam)
 	isp.pid = sig.pid;
 	isp.arg = virt_to_phys(msigp);
 
-	if ((rc = mcctrl_ikc_send(os, sig.cpu, &isp)) < 0) {
+	rc = mcctrl_ikc_send_wait(os, sig.cpu, &isp, 0, &desc->wakeup,
+				  &do_free, 1, desc);
+	if (rc < 0) {
 		printk("mcexec_send_signal: mcctrl_ikc_send ret=%d\n", rc);
+		if (do_free)
+			kfree(desc);
 		return rc;
 	}
-	wait_event_interruptible(signalq, msigp->cond != 0);
 
+	kfree(desc);
 	return 0;
 }
 
-void
-sig_done(unsigned long arg, int err)
-{
-	struct mcctrl_signal *msigp;
-
-	msigp = phys_to_virt(arg);
-	msigp->cond = 1;
-	wake_up_interruptible(&signalq);
-}
-
 static long mcexec_get_cpu(ihk_os_t os)
 {
 	struct ihk_cpu_info *info;
diff --git a/executer/kernel/mcctrl/ikc.c b/executer/kernel/mcctrl/ikc.c
index acf88860..1faf7f5d 100644
--- a/executer/kernel/mcctrl/ikc.c
+++ b/executer/kernel/mcctrl/ikc.c
@@ -106,7 +106,8 @@ int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
 	int alloc_desc = (desc == NULL);
 	va_list ap;
 
-	*do_frees = 1;
+	if (free_addrs_count)
+		*do_frees = 1;
 	if (alloc_desc)
 		desc = kmalloc(sizeof(struct mcctrl_wakeup_desc) +
 			       (free_addrs_count + 1) * sizeof(void *),
@@ -153,7 +154,8 @@ int mcctrl_ikc_send_wait(ihk_os_t os, int cpu, struct ikc_scd_packet *pisp,
 		spin_lock_irqsave(&usrdata->wakeup_descs_lock, flags);
 		list_add(&desc->chain, &usrdata->wakeup_descs_list);
 		spin_unlock_irqrestore(&usrdata->wakeup_descs_lock, flags);
-		*do_frees = 0;
+		if (free_addrs_count)
+			*do_frees = 0;
 		return ret < 0 ? ret : -ETIME;
 	}
 
@@ -179,6 +181,7 @@ static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
 
 	case SCD_MSG_PREPARE_PROCESS_ACKED:
 	case SCD_MSG_PERF_ACK:
+	case SCD_MSG_SEND_SIGNAL_ACK:
 		mcctrl_wakeup_cb(__os, pisp);
 		break;
 
@@ -190,9 +193,6 @@ static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
 		procfs_answer(usrdata, pisp->pid);
 		break;
 
-	case SCD_MSG_SEND_SIGNAL:
-		sig_done(pisp->arg, pisp->err);
-		break;
 
 	case SCD_MSG_SYSFS_REQ_CREATE:
 	case SCD_MSG_SYSFS_REQ_MKDIR:
diff --git a/executer/kernel/mcctrl/mcctrl.h b/executer/kernel/mcctrl/mcctrl.h
index d1c37e26..1761861b 100644
--- a/executer/kernel/mcctrl/mcctrl.h
+++ b/executer/kernel/mcctrl/mcctrl.h
@@ -55,7 +55,8 @@
 #define SCD_MSG_INIT_CHANNEL_ACKED      0x6
 
 #define SCD_MSG_SYSCALL_ONESIDE         0x4
-#define SCD_MSG_SEND_SIGNAL     	0x8
+#define SCD_MSG_SEND_SIGNAL             0x7
+#define SCD_MSG_SEND_SIGNAL_ACK         0x8
 #define SCD_MSG_CLEANUP_PROCESS         0x9
 #define SCD_MSG_GET_VDSO_INFO           0xa
 
diff --git a/kernel/host.c b/kernel/host.c
index d34a0346..5d62544e 100644
--- a/kernel/host.c
+++ b/kernel/host.c
@@ -655,10 +655,11 @@ static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
 		memcpy(&info, sp, sizeof(struct mcctrl_signal));
 		ihk_mc_unmap_virtual(sp, 1, 0);
 		ihk_mc_unmap_memory(NULL, pp, sizeof(struct mcctrl_signal));
-		pckt.msg = SCD_MSG_SEND_SIGNAL;
+		pckt.msg = SCD_MSG_SEND_SIGNAL_ACK;
 		pckt.err = 0;
 		pckt.ref = packet->ref;
 		pckt.arg = packet->arg;
+		pckt.reply = packet->reply;
 		syscall_channel_send(resp_channel, &pckt);
 
 		rc = do_kill(NULL, info.pid, info.tid, info.sig, &info.info, 0);
diff --git a/kernel/include/syscall.h b/kernel/include/syscall.h
index e18b13d5..35807168 100644
--- a/kernel/include/syscall.h
+++ b/kernel/include/syscall.h
@@ -37,8 +37,9 @@
 #define SCD_MSG_INIT_CHANNEL_ACKED      0x6
 
 #define SCD_MSG_SYSCALL_ONESIDE         0x4
-#define SCD_MSG_SEND_SIGNAL		0x8
-#define	SCD_MSG_CLEANUP_PROCESS		0x9
+#define SCD_MSG_SEND_SIGNAL             0x7
+#define SCD_MSG_SEND_SIGNAL_ACK         0x8
+#define SCD_MSG_CLEANUP_PROCESS         0x9
 #define SCD_MSG_GET_VDSO_INFO           0xa
 
 #define SCD_MSG_GET_CPU_MAPPING         0xc