diff --git a/os/Cargo.lock b/os/Cargo.lock
index 3775338..930eae3 100644
--- a/os/Cargo.lock
+++ b/os/Cargo.lock
@@ -50,7 +50,7 @@ checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
 
 [[package]]
 name = "os"
-version = "0.1.0"
+version = "0.3.0"
 dependencies = [
  "lazy_static",
  "riscv",
diff --git a/os/Cargo.toml b/os/Cargo.toml
index 22acc70..ca83c2e 100644
--- a/os/Cargo.toml
+++ b/os/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "os"
-version = "0.1.0"
+version = "0.3.0"
 edition = "2021"
 
 [dependencies]
diff --git a/os/src/boards.rs b/os/src/boards.rs
index 1d6396d..d3daf7f 100644
--- a/os/src/boards.rs
+++ b/os/src/boards.rs
@@ -1 +1 @@
-pub mod qemu;
\ No newline at end of file
+pub mod qemu;
diff --git a/os/src/boards/qemu.rs b/os/src/boards/qemu.rs
index ed95dd0..7412c84 100644
--- a/os/src/boards/qemu.rs
+++ b/os/src/boards/qemu.rs
@@ -1 +1 @@
-pub const CLOCK_FREQUENCY: usize = 10000000;
\ No newline at end of file
+pub const CLOCK_FREQUENCY: usize = 10000000;
diff --git a/os/src/config.rs b/os/src/config.rs
index 1c7c317..31c0be9 100644
--- a/os/src/config.rs
+++ b/os/src/config.rs
@@ -5,4 +5,4 @@ pub const MAX_APP_NUM: usize = 4;
 pub const APP_BASE_ADDRESS: usize = 0x80400000;
 pub const APP_SIZE_LIMIT: usize = 0x20000;
 
-pub use crate::boards::qemu::CLOCK_FREQUENCY;
\ No newline at end of file
+pub use crate::boards::qemu::CLOCK_FREQUENCY;
diff --git a/os/src/console.rs b/os/src/console.rs
index e88704f..8b22298 100644
--- a/os/src/console.rs
+++ b/os/src/console.rs
@@ -35,34 +35,34 @@ macro_rules! println {
 #[macro_export]
 macro_rules! log_error {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!("\x1b[31m" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!("\x1b[31m [kernel]" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
     }
 }
 
 #[macro_export]
 macro_rules! log_warning {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!("\x1b[93m" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!("\x1b[93m [kernel]" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
     }
 }
 
 #[macro_export]
 macro_rules! log_information {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!("\x1b[34m" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!("\x1b[34m [kernel]" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
     }
 }
 
 #[macro_export]
 macro_rules! log_debug {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!("\x1b[32m" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!("\x1b[32m [kernel]" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
     }
 }
 
 #[macro_export]
 macro_rules! log_trace {
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        $crate::console::print(format_args!(concat!("\x1b[90m" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
+        $crate::console::print(format_args!(concat!("\x1b[90m [kernel]" ,concat!($fmt, "\x1b[0m\n")) $(, $($arg)+)?));
     }
 }
diff --git a/os/src/loader.rs b/os/src/loader.rs
index e33e14b..25323f9 100644
--- a/os/src/loader.rs
+++ b/os/src/loader.rs
@@ -1,8 +1,9 @@
 use crate::config::{
     APP_BASE_ADDRESS, APP_SIZE_LIMIT, KERNEL_STACK_SIZE, MAX_APP_NUM, USER_STACK_SIZE,
 };
-use core::arch::asm;
+use crate::log_information;
 use crate::trap::context::TrapContext;
+use core::arch::asm;
 
 #[repr(align(4096))]
 #[derive(Copy, Clone)]
@@ -30,7 +31,7 @@ impl KernelStack {
     }
 
     pub fn push_context(&self, trap_context: TrapContext) -> usize {
-        let pointer = (self.get_sp() - core::mem::size_of::<TrapContext>()) as *mut TrapContext;
+        let pointer = (self.get_sp() - size_of::<TrapContext>()) as *mut TrapContext;
 
         unsafe {
             *pointer = trap_context;
@@ -85,6 +86,7 @@ pub fn load_apps() {
         destination.copy_from_slice(source);
     }
 
+    log_information!("Load {} applications in memory.", app_num);
     unsafe {
         asm!("fence.i");
     }
@@ -93,6 +95,6 @@ pub fn load_apps() {
 pub fn initialize_app_context(app_id: usize) -> usize {
     KERNEL_STACK[app_id].push_context(TrapContext::init_application_context(
         APP_BASE_ADDRESS + app_id * APP_SIZE_LIMIT,
-        USER_STACK[app_id].get_sp()
+        USER_STACK[app_id].get_sp(),
     ))
-}
\ No newline at end of file
+}
diff --git a/os/src/main.rs b/os/src/main.rs
index b1f37a1..351c8f4 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -4,17 +4,17 @@
 use crate::utils::clear_bss;
 use core::arch::global_asm;
 
+mod boards;
+mod config;
 mod console;
+mod loader;
 mod sbi;
 mod sync;
 mod syscall;
-mod trap;
-mod utils;
-mod loader;
-mod boards;
-mod config;
 mod task;
 mod timer;
+mod trap;
+mod utils;
 
 global_asm!(include_str!("entry.asm"));
 global_asm!(include_str!("link_app.asm"));
@@ -22,7 +22,7 @@ global_asm!(include_str!("link_app.asm"));
 #[no_mangle]
 fn rust_main() -> ! {
     clear_bss();
-    log_information!("[kernel] Hello, rCore!");
+    log_information!("Hello, rCore!");
     trap::init();
     loader::load_apps();
     task::run_first_task();
diff --git a/os/src/sync/single_cell.rs b/os/src/sync/single_cell.rs
index f6687cd..20ab3be 100644
--- a/os/src/sync/single_cell.rs
+++ b/os/src/sync/single_cell.rs
@@ -8,7 +8,7 @@ pub struct SingleCell<T> {
 unsafe impl<T> Sync for SingleCell<T> {}
 
 impl<T> SingleCell<T> {
-    pub unsafe fn new(value: T) -> SingleCell<T> {
+    pub fn new(value: T) -> SingleCell<T> {
         SingleCell {
             inner: RefCell::new(value),
         }
diff --git a/os/src/syscall.rs b/os/src/syscall.rs
index 03dcfbe..6e9bd4d 100644
--- a/os/src/syscall.rs
+++ b/os/src/syscall.rs
@@ -1,3 +1,4 @@
+use crate::log_error;
 use crate::syscall::fs::sys_write;
 use crate::syscall::process::{sys_exit, sys_get_time, sys_yield};
 
@@ -16,7 +17,8 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> usize {
         SYSCALL_YIELD => sys_yield(),
         SYSCALL_GET_TIME => sys_get_time(),
         _ => {
-            panic!("Unsupported syscall: {}", syscall_id)
-        },
+            log_error!("Unsupported syscall {} used.", syscall_id);
+            0
+        }
     }
 }
diff --git a/os/src/syscall/fs.rs b/os/src/syscall/fs.rs
index 97d129b..3eef5e3 100644
--- a/os/src/syscall/fs.rs
+++ b/os/src/syscall/fs.rs
@@ -1,4 +1,4 @@
-use crate::print;
+use crate::{log_error, print};
 
 const STDOUT_FD: usize = 1;
 
@@ -11,7 +11,8 @@ pub fn sys_write(fd: usize, buffer: *const u8, len: usize) -> usize {
             len
         }
         _ => {
-            panic!("Unsupported file descriptor in sys_write");
+            log_error!("Unsupported file descriptor {} used.", fd);
+            0
         }
     }
 }
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index 54059cd..06a14fd 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -1,9 +1,9 @@
-use crate::println;
+use crate::log_information;
 use crate::task::{exit_current_and_run_next, suspend_current_and_run_next};
 use crate::timer::get_time_ms;
 
 pub fn sys_exit(exit_state: i32) -> ! {
-    println!("[kernel] Application exited with code {}.", exit_state);
+    log_information!("Application exited with code {}.", exit_state);
     exit_current_and_run_next();
 
     unreachable!()
diff --git a/os/src/task.rs b/os/src/task.rs
index e65477c..7a97b46 100644
--- a/os/src/task.rs
+++ b/os/src/task.rs
@@ -1,3 +1,5 @@
+use lazy_static::lazy_static;
+
 use crate::config::MAX_APP_NUM;
 use crate::loader::{get_app_num, initialize_app_context};
 use crate::log_information;
@@ -5,7 +7,6 @@ use crate::sbi::shutdown;
 use crate::sync::single_cell::SingleCell;
 use crate::task::context::TaskContext;
 use crate::task::switch::__switch;
-use lazy_static::lazy_static;
 
 mod context;
 mod switch;
@@ -30,7 +31,7 @@ pub struct TaskManagerInner {
 }
 
 pub struct TaskManager {
-    app_numer: usize,
+    app_number: usize,
     inner: SingleCell<TaskManagerInner>,
 }
 
@@ -48,8 +49,8 @@ lazy_static! {
         }
 
         TaskManager {
-            app_numer: app_num,
-            inner: unsafe {
+            app_number: app_num,
+            inner: {
                 SingleCell::new(TaskManagerInner {
                     tasks,
                     current_task: 0,
@@ -90,8 +91,8 @@ impl TaskManager {
 
     fn find_next_task(&self) -> Option<usize> {
         let inner = self.inner.exclusive_borrow();
-        (inner.current_task + 1..inner.current_task + self.app_numer + 1)
-            .map(|id| id % self.app_numer)
+        (inner.current_task + 1..inner.current_task + self.app_number + 1)
+            .map(|id| id % self.app_number)
             .find(|id| inner.tasks[*id].status == TaskStatus::Ready)
     }
 
@@ -116,7 +117,7 @@ impl TaskManager {
         }
     }
 
-    fn run_first_task(&self) -> ! {
+    fn run_first_task(&self) {
         let mut inner = self.inner.exclusive_borrow();
         let task0 = &mut inner.tasks[0];
         task0.status = TaskStatus::Running;
@@ -127,7 +128,5 @@ impl TaskManager {
         unsafe {
             __switch(&mut unused as *mut TaskContext, next_task_context);
         }
-
-        unreachable!();
     }
 }
diff --git a/os/src/task/context.rs b/os/src/task/context.rs
index 9b0b887..3c0373a 100644
--- a/os/src/task/context.rs
+++ b/os/src/task/context.rs
@@ -1,10 +1,9 @@
-
 #[derive(Copy, Clone)]
 #[repr(C)]
 pub struct TaskContext {
     ra: usize,
     sp: usize,
-    s: [usize; 12]
+    s: [usize; 12],
 }
 
 impl TaskContext {
@@ -12,7 +11,7 @@ impl TaskContext {
         Self {
             ra: 0,
             sp: 0,
-            s: [0; 12]
+            s: [0; 12],
         }
     }
 
@@ -25,7 +24,7 @@ impl TaskContext {
         Self {
             ra: __restore as usize,
             sp: kernel_stack_pointer,
-            s: [0; 12]
+            s: [0; 12],
         }
     }
 }
diff --git a/os/src/task/switch.rs b/os/src/task/switch.rs
index 6ef6dcf..2fa2abb 100644
--- a/os/src/task/switch.rs
+++ b/os/src/task/switch.rs
@@ -6,5 +6,3 @@ global_asm!(include_str!("switch.asm"));
 extern "C" {
     pub fn __switch(current_task_context: *mut TaskContext, next_task_context: *const TaskContext);
 }
-
-
diff --git a/os/src/timer.rs b/os/src/timer.rs
index 6c0ec82..d2eff6f 100644
--- a/os/src/timer.rs
+++ b/os/src/timer.rs
@@ -1,6 +1,6 @@
-use riscv::register::time;
 use crate::config::CLOCK_FREQUENCY;
 use crate::sbi::set_timer;
+use riscv::register::time;
 
 pub fn get_time() -> usize {
     time::read()
diff --git a/os/src/trap.asm b/os/src/trap.asm
index 3aaad85..9a05fd6 100644
--- a/os/src/trap.asm
+++ b/os/src/trap.asm
@@ -59,4 +59,5 @@ __restore:
     addi sp, sp, 34*8
     # now sp->kernel stack, sscratch->user stack
     csrrw sp, sscratch, sp
+    # now sp->user stack, sscratch->kernel stack
     sret
\ No newline at end of file
diff --git a/os/src/trap.rs b/os/src/trap.rs
index d97caac..ff6496f 100644
--- a/os/src/trap.rs
+++ b/os/src/trap.rs
@@ -1,10 +1,14 @@
-use crate::println;
+use crate::log_warning;
 use crate::syscall::syscall;
-use crate::trap::context::TrapContext;
-use core::arch::global_asm;
-use riscv::register::{mtvec::TrapMode, scause::{self, Exception, Trap, Interrupt}, sie, stval, stvec};
 use crate::task::{exit_current_and_run_next, suspend_current_and_run_next};
 use crate::timer::set_next_trigger;
+use crate::trap::context::TrapContext;
+use core::arch::global_asm;
+use riscv::register::{
+    mtvec::TrapMode,
+    scause::{self, Exception, Interrupt, Trap},
+    sie, stval, stvec,
+};
 
 pub mod context;
 
@@ -35,11 +39,15 @@ pub fn trap_handler(context: &mut TrapContext) -> &mut TrapContext {
             context.x[10] = syscall(context.x[17], [context.x[10], context.x[11], context.x[12]]);
         }
         Trap::Exception(Exception::StoreFault) | Trap::Exception(Exception::StorePageFault) => {
-            println!("[kernel] PageFault in application, kernel will kill it.");
+            log_warning!("PageFault in application, kernel will kill it.");
             exit_current_and_run_next();
         }
         Trap::Exception(Exception::IllegalInstruction) => {
-            println!("[kernel] Illegal instruction in application, kernel will kill it.");
+            log_warning!("Illegal instruction in application, kernel will kill it.");
+            exit_current_and_run_next();
+        }
+        Trap::Exception(Exception::LoadFault) => {
+            log_warning!("Illegal memory access in application, kernel will kill it.");
             exit_current_and_run_next();
         }
         Trap::Interrupt(Interrupt::SupervisorTimer) => {
diff --git a/user/src/bin/sleep.rs b/user/src/bin/0sleep.rs
similarity index 91%
rename from user/src/bin/sleep.rs
rename to user/src/bin/0sleep.rs
index b19774a..d3df999 100644
--- a/user/src/bin/sleep.rs
+++ b/user/src/bin/0sleep.rs
@@ -11,10 +11,11 @@ fn main() -> i32 {
     let current_time = get_time();
     let wait_time = current_time + 3000;
 
+    println!("Sleep~~~~");
     while get_time() < wait_time {
         sys_yield();
     }
 
     println!("Test sleep OK!");
     0
-}
\ No newline at end of file
+}
diff --git a/user/src/bin/power_3.rs b/user/src/bin/power_3.rs
index e0ec5f3..1a04dc7 100644
--- a/user/src/bin/power_3.rs
+++ b/user/src/bin/power_3.rs
@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_3 OK!");
     0
-}
\ No newline at end of file
+}
diff --git a/user/src/bin/power_5.rs b/user/src/bin/power_5.rs
index f31a24e..e47761b 100644
--- a/user/src/bin/power_5.rs
+++ b/user/src/bin/power_5.rs
@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_5 OK!");
     0
-}
\ No newline at end of file
+}
diff --git a/user/src/bin/power_7.rs b/user/src/bin/power_7.rs
index fd9f23e..a97d2f5 100644
--- a/user/src/bin/power_7.rs
+++ b/user/src/bin/power_7.rs
@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_7 OK!");
     0
-}
\ No newline at end of file
+}