diff --git a/os/src/console.rs b/os/src/console.rs
index 2bd5593046ac358ae6f950486336924a088bfbdc..91988883665c860e15be67744757e1dc74fc00d7 100644
--- a/os/src/console.rs
+++ b/os/src/console.rs
@@ -19,14 +19,14 @@ pub fn print(args: fmt::Arguments) {
 #[macro_export]
 macro_rules! print {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!($fmt $(, $($arg)+)?));
+        $crate::console::print(format_args!($fmt $(, $($arg)+)?))
     }
 }
 
 #[macro_export]
 macro_rules! println {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!($fmt, "\n") $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!($fmt, "\n") $(, $($arg)+)?))
     }
 }
 
diff --git a/os/src/task/id.rs b/os/src/task/id.rs
index cf766b292c6633b293c32a1d175c8564e0e40dc3..3795a8711c5ed0190d501fc1420399997442e6ff 100644
--- a/os/src/task/id.rs
+++ b/os/src/task/id.rs
@@ -163,15 +163,9 @@ impl TaskUserRes {
             );
     }
 
-    pub fn dealloc_tid(&self) {
-        let mut process = self.process.inner_exclusive_access();
-        process.dealloc_tid(self.tid);
-    }
-
     fn dealloc_user_res(&self) {
         // dealloc tid
         let mut process = self.process.inner_exclusive_access();
-        process.dealloc_tid(self.tid);
         // dealloc ustack manually
         let ustack_bottom_va: VirtAddr = ustack_bottom_from_tid(self.ustack_base, self.tid).into();
         process.memory_set.remove_area_with_start_vpn(ustack_bottom_va.into());
@@ -180,6 +174,16 @@ impl TaskUserRes {
         process.memory_set.remove_area_with_start_vpn(trap_cx_bottom_va.into());
     }
 
+    #[allow(unused)]
+    pub fn alloc_tid(&mut self) {
+        self.tid = self.process.inner_exclusive_access().alloc_tid();
+    }
+
+    pub fn dealloc_tid(&self) {
+        let mut process = self.process.inner_exclusive_access();
+        process.dealloc_tid(self.tid);
+    }
+
     pub fn trap_cx_user_va(&self) -> usize {
         trap_cx_bottom_from_tid(self.tid)
     }
@@ -202,6 +206,7 @@ impl TaskUserRes {
 
 impl Drop for TaskUserRes {
     fn drop(&mut self) {
+        self.dealloc_tid();
         self.dealloc_user_res();
         // kstack can also be deallocated automatically 
     }
diff --git a/os/src/task/manager.rs b/os/src/task/manager.rs
index 2e3708d7c2e7857b56a4b6bbf727a23b3646fc61..82c2d1e485f1cb0372239bd195f147a7fb253b20 100644
--- a/os/src/task/manager.rs
+++ b/os/src/task/manager.rs
@@ -33,4 +33,4 @@ pub fn add_task(task: Arc<TaskControlBlock>) {
 
 pub fn fetch_task() -> Option<Arc<TaskControlBlock>> {
     TASK_MANAGER.exclusive_access().fetch()
-}
\ No newline at end of file
+}
diff --git a/os/src/task/mod.rs b/os/src/task/mod.rs
index 68c89a49df5028f2153683a9c9603662e87115f0..c83af4c0b4b1496e25bb27e58292c60bd79117e6 100644
--- a/os/src/task/mod.rs
+++ b/os/src/task/mod.rs
@@ -55,7 +55,7 @@ pub fn suspend_current_and_run_next() {
 pub fn exit_current_and_run_next(exit_code: i32) {
     // take from Processor
     let task = take_current_task().unwrap();
-    let task_exit_code = task.inner_exclusive_access().exit_code;
+    task.inner_exclusive_access().exit_code = exit_code;
     let tid = task.inner_exclusive_access().res.tid;
     // remove thread 
     let process = task.process.upgrade().unwrap();
@@ -66,7 +66,7 @@ pub fn exit_current_and_run_next(exit_code: i32) {
         // mark this process as a zombie process
         process_inner.is_zombie = true;
         // record exit code of main process
-        process_inner.exit_code = task_exit_code;
+        process_inner.exit_code = exit_code;
 
         {
             // move all child processes under init process
@@ -99,5 +99,5 @@ lazy_static! {
 }
 
 pub fn add_initproc() {
-    let initproc = INITPROC.clone();
+    let _initproc = INITPROC.clone();
 }
diff --git a/os/src/task/process.rs b/os/src/task/process.rs
index 45858b9e8a01c84c76c7696714c505c2d13f5682..370d80377409807225bd0292a79c04b56958c4af 100644
--- a/os/src/task/process.rs
+++ b/os/src/task/process.rs
@@ -3,8 +3,6 @@ use crate::mm::{
     KERNEL_SPACE, 
     translated_refmut,
 };
-use crate::task::TaskContext;
-use crate::task::id::TaskUserRes;
 use crate::trap::{TrapContext, trap_handler};
 use crate::sync::UPSafeCell;
 use core::cell::RefMut;
@@ -37,6 +35,7 @@ pub struct ProcessControlBlockInner {
 }
 
 impl ProcessControlBlockInner {
+    #[allow(unused)]
     pub fn get_user_token(&self) -> usize {
         self.memory_set.token()
     }
@@ -138,9 +137,9 @@ impl ProcessControlBlock {
         // since memory_set has been changed
         let task = self.inner_exclusive_access().get_task(0);
         let mut task_inner = task.inner_exclusive_access();
-        task_inner.res.dealloc_tid();
         task_inner.res.ustack_base = ustack_base;
         task_inner.res.alloc_user_res();
+        task_inner.trap_cx_ppn = task_inner.res.trap_cx_ppn();
         // push arguments on user stack
         let mut user_sp = task_inner.res.ustack_top();
         user_sp -= (args.len() + 1) * core::mem::size_of::<usize>();
@@ -177,7 +176,6 @@ impl ProcessControlBlock {
         trap_cx.x[10] = args.len();
         trap_cx.x[11] = argv_base;
         *task_inner.get_trap_cx() = trap_cx;
-        task_inner.task_cx = TaskContext::goto_trap_return(task_inner.res.kstack_top());
     }
 
     /// Only support processes with a single thread.
diff --git a/os/src/task/task.rs b/os/src/task/task.rs
index 74ced440351704d7e3ba74238a810c502acb24cf..996e41157f17e8f366920a9ada3a1a13e0075567 100644
--- a/os/src/task/task.rs
+++ b/os/src/task/task.rs
@@ -41,7 +41,7 @@ impl TaskControlBlockInner {
         self.trap_cx_ppn.get_mut()
     }
     
-
+    #[allow(unused)]
     fn get_status(&self) -> TaskStatus {
         self.task_status
     }
diff --git a/os/src/trap/mod.rs b/os/src/trap/mod.rs
index 560127e8116998cd978fdd3a2ed37beb84f4185b..7f214195f7d87c84a58188db78ebc5349f87228c 100644
--- a/os/src/trap/mod.rs
+++ b/os/src/trap/mod.rs
@@ -47,7 +47,6 @@ pub fn enable_timer_interrupt() {
 
 #[no_mangle]
 pub fn trap_handler() -> ! {
-    println!("into trap!");
     set_kernel_trap_entry();
     let scause = scause::read();
     let stval = stval::read();
@@ -55,7 +54,6 @@ pub fn trap_handler() -> ! {
         Trap::Exception(Exception::UserEnvCall) => {
             // jump to next instruction anyway
             let mut cx = current_trap_cx();
-            println!("syscall #{}", cx.x[17]);
             cx.sepc += 4;
             // get system call return value
             let result = syscall(cx.x[17], [cx.x[10], cx.x[11], cx.x[12]]);
@@ -96,11 +94,9 @@ pub fn trap_handler() -> ! {
 
 #[no_mangle]
 pub fn trap_return() -> ! {
-    println!("into trap_return!");
     set_user_trap_entry();
     let trap_cx_user_va = current_trap_cx_user_va();
     let user_satp = current_user_token();
-    println!("trap_cx = {:#x}, user_satp = {:#x}", trap_cx_user_va, user_satp);
     extern "C" {
         fn __alltraps();
         fn __restore();
diff --git a/user/src/lib.rs b/user/src/lib.rs
index d7f51cf2c48c751f965b65859b2cb5ac8727c1a0..f13a36730865f1c444a973a8ee13567c037136d4 100644
--- a/user/src/lib.rs
+++ b/user/src/lib.rs
@@ -105,4 +105,4 @@ pub fn sleep(period_ms: usize) {
     while sys_get_time() < start + period_ms as isize {
         sys_yield();
     }
-}
\ No newline at end of file
+}