diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index 3179463..373d666 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -42,4 +42,5 @@ uintr = { path = "../crates/uintr" }
 default = ["oscomp", "test"]
 test = []
 oscomp = []
-uintr = []
\ No newline at end of file
+uintr = []
+sleeplock = []
\ No newline at end of file
diff --git a/kernel/src/arch/riscv64/trap/mod.rs b/kernel/src/arch/riscv64/trap/mod.rs
index ff6f5b6..6c6086f 100644
--- a/kernel/src/arch/riscv64/trap/mod.rs
+++ b/kernel/src/arch/riscv64/trap/mod.rs
@@ -55,6 +55,9 @@ pub fn enable_timer_intr() {
 /// 2. Handles page fault caused by Instruction Fetch, Load or Store.
 #[no_mangle]
 pub fn user_trap_handler() -> ! {
+    #[cfg(feature = "uintr")]
+    uintr_save();
+
     set_kernel_trap();
 
     let scause = scause::read();
@@ -136,7 +139,8 @@ pub fn user_trap_handler() -> ! {
 /// current task. We must drop them before changing the control flow without unwinding.
 #[no_mangle]
 pub fn user_trap_return() -> ! {
-    // crate::tests::sleeplock::test();
+    #[cfg(feature = "sleeplock")]
+    crate::tests::sleeplock::test();
 
     #[cfg(feature = "uintr")]
     uintr_return();
diff --git a/kernel/src/arch/riscv64/uintr.rs b/kernel/src/arch/riscv64/uintr.rs
index 54f2115..517abfd 100644
--- a/kernel/src/arch/riscv64/uintr.rs
+++ b/kernel/src/arch/riscv64/uintr.rs
@@ -182,6 +182,9 @@ pub struct TaskUIntrInner {
 
     /// User interrupt handler
     pub uscratch: usize,
+
+    /// User error pc
+    pub uepc: usize,
 }
 
 impl TaskUIntrInner {
@@ -192,6 +195,7 @@ impl TaskUIntrInner {
             mask: 0,
             utvec: 0,
             uscratch: 0,
+            uepc: 0,
         }
     }
 
@@ -355,7 +359,11 @@ mod syscall {
 
     /// Synchronize receiver status to UINTC and raise user interrupt if kernel returns to
     /// a receiver with pending interrupt requests.
-    pub unsafe fn uirs_sync() {
+    /// 
+    /// Each time a receiver traps into a U-mode trap handler, it can be migrated to another hart
+    /// caused by U-ecall or other exceptions thus we must save and restore CPU-local registers such
+    /// as `upec`, `utvec` and `uscratch`. 
+    pub unsafe fn uirs_restore() {
         let uintr_inner = cpu().curr.as_ref().unwrap().uintr_inner();
         if let Some(uirs) = &uintr_inner.uirs {
             let index = uirs.0;
@@ -364,9 +372,10 @@ mod syscall {
             uirs.mode |= 0x2; // 64 bits
             uirs.sync(index);
 
-            log::trace!("uirs_sync {:x} {:x?}", index, uirs);
+            log::trace!("uirs_restore {:x} {:x?}", index, uirs);
 
             // user configurations
+            uepc::write(uintr_inner.uepc);
             utvec::write(uintr_inner.utvec, utvec::TrapMode::Direct);
             uscratch::write(uintr_inner.uscratch);
             uie::set_usoft();
@@ -400,12 +409,19 @@ mod syscall {
     /// Called during trap return.
     pub fn uintr_return() {
         // receiver
-        unsafe { uirs_sync() };
+        unsafe { uirs_restore() };
 
         // sender
         uist_init();
     }
 
+    /// Called when task traps into kernel.
+    pub fn uintr_save() {
+        let curr = cpu().curr.as_ref().unwrap();
+        
+        curr.uintr_inner().uepc = uepc::read();
+    }
+
     pub struct UIntrFile {
         pub uirs_index: usize,
         pub vector: usize,
diff --git a/kernel/src/cons/logger.rs b/kernel/src/cons/logger.rs
index 3a01b19..9c564d7 100644
--- a/kernel/src/cons/logger.rs
+++ b/kernel/src/cons/logger.rs
@@ -18,7 +18,7 @@ impl Log for Logger {
             Level::Warn => 93,  // BrightYellow
             Level::Info => 34,  // Blue
             Level::Debug => 32, // Green
-            Level::Trace => 90, // BrightBlack
+            Level::Trace => 33, // BrightBlack
         };
         let cpu_id = get_cpu_id();
         println!(
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index fa50f36..2f5cda9 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -76,9 +76,11 @@ pub extern "C" fn rust_main(hartid: usize) -> ! {
 #[no_mangle]
 pub extern "C" fn rust_main_others(hartid: usize) -> ! {
     // Other initializations.
-
     arch::init(hartid, false);
     info!("(Secondary) Start executing tasks.");
+    // Enable timer interrupt
+    arch::trap::enable_timer_intr();
+    timer::set_next_trigger();
     // IDLE loop
     unsafe { task::idle() };
 }
diff --git a/test b/test
index 71f0659..cbfb47f 160000
--- a/test
+++ b/test
@@ -1 +1 @@
-Subproject commit 71f0659875208374c445ac03b93be22c06fca610
+Subproject commit cbfb47f3c231613cf0fc74b3dd4d393c5fadbeaf