diff --git a/source/module/monitor_kernel.c b/source/module/monitor_kernel.c
index 06c334d..bf0d872 100644
--- a/source/module/monitor_kernel.c
+++ b/source/module/monitor_kernel.c
@@ -69,7 +69,10 @@ static long device_ioctl(struct file *file, unsigned int ioctl_num,
     warg.time_ns =
         warg.time_ns == 0 ? def_interval_ns : warg.time_ns; // default 10us
     // start watch variable
-    start_watch_variable(warg);
+    ret = start_watch_variable(warg);
+    if (ret) {
+      printk(KERN_INFO "start_watch_variable failed\n");
+    }
     break;
   case IOCTL_DUMP_LOG:
     printk(KERN_INFO "variable_monitor IOCTL_DUMP_LOG\n");
diff --git a/source/module/monitor_kernel_lib.c b/source/module/monitor_kernel_lib.c
index 68ed9ad..ade2616 100644
--- a/source/module/monitor_kernel_lib.c
+++ b/source/module/monitor_kernel_lib.c
@@ -239,7 +239,7 @@ int monitor_init(void) {
   if (ret)
     return ret;
   //!todo
-  ret = init_buffer(512 * 1024 * 1024); // 512M
+  ret = init_buffer(256 * 1024 * 1024); // 512M
   if (ret)
     return -1;
   return 0;
@@ -284,6 +284,11 @@ int start_watch_variable(watch_arg warg) {
   w_arg2k_w_arg(kptr, warg, &k_watch_arg);
   timer = get_timer(warg.time_ns); // get a valuable timer
 
+  if (timer == NULL) {
+    printk(KERN_ERR "Timer is full\n");
+    return -1;
+  }
+
   INIT_WORK(&timer->wk, diag_task_info_work);
 
   printk(KERN_INFO "ptr transform kptr: %p\n", kptr);