diff --git a/os/src/drivers/block/virtio_blk.rs b/os/src/drivers/block/virtio_blk.rs
index a30e3bf8..75e69c17 100644
--- a/os/src/drivers/block/virtio_blk.rs
+++ b/os/src/drivers/block/virtio_blk.rs
@@ -20,7 +20,8 @@ pub struct VirtIOBlock {
 }
 
 lazy_static! {
-    static ref QUEUE_FRAMES: UPIntrFreeCell<Vec<FrameTracker>> = unsafe { UPIntrFreeCell::new(Vec::new()) };
+    static ref QUEUE_FRAMES: UPIntrFreeCell<Vec<FrameTracker>> =
+        unsafe { UPIntrFreeCell::new(Vec::new()) };
 }
 
 impl BlockDevice for VirtIOBlock {
diff --git a/os/src/drivers/chardev/ns16550a.rs b/os/src/drivers/chardev/ns16550a.rs
index 81e3878b..da290633 100644
--- a/os/src/drivers/chardev/ns16550a.rs
+++ b/os/src/drivers/chardev/ns16550a.rs
@@ -1,7 +1,6 @@
 ///! Ref: https://www.lammertbies.nl/comm/info/serial-uart
 ///! Ref: ns16550a datasheet: https://datasheetspdf.com/pdf-file/605590/NationalSemiconductor/NS16550A/1
 ///! Ref: ns16450 datasheet: https://datasheetspdf.com/pdf-file/1311818/NationalSemiconductor/NS16450/1
-
 use super::CharDevice;
 use crate::sync::{Condvar, UPIntrFreeCell};
 use crate::task::schedule;
diff --git a/os/src/main.rs b/os/src/main.rs
index a9323be1..3c23069b 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -46,7 +46,8 @@ use lazy_static::*;
 use sync::UPIntrFreeCell;
 
 lazy_static! {
-    pub static ref DEV_NON_BLOCKING_ACCESS: UPIntrFreeCell<bool> = unsafe { UPIntrFreeCell::new(false) };
+    pub static ref DEV_NON_BLOCKING_ACCESS: UPIntrFreeCell<bool> =
+        unsafe { UPIntrFreeCell::new(false) };
 }
 
 #[no_mangle]
diff --git a/os/src/sync/condvar.rs b/os/src/sync/condvar.rs
index c50a53e2..714782c2 100644
--- a/os/src/sync/condvar.rs
+++ b/os/src/sync/condvar.rs
@@ -1,5 +1,8 @@
 use crate::sync::{Mutex, UPIntrFreeCell};
-use crate::task::{add_task, block_current_task, block_current_and_run_next, current_task, TaskControlBlock, TaskContext};
+use crate::task::{
+    add_task, block_current_and_run_next, block_current_task, current_task, TaskContext,
+    TaskControlBlock,
+};
 use alloc::{collections::VecDeque, sync::Arc};
 
 pub struct Condvar {
diff --git a/os/src/sync/up.rs b/os/src/sync/up.rs
index 3600271a..6c7a0f4a 100644
--- a/os/src/sync/up.rs
+++ b/os/src/sync/up.rs
@@ -1,7 +1,7 @@
 use core::cell::{RefCell, RefMut, UnsafeCell};
 use core::ops::{Deref, DerefMut};
-use riscv::register::sstatus;
 use lazy_static::*;
+use riscv::register::sstatus;
 
 /*
 /// Wrap a static data structure inside it so that we are
@@ -56,9 +56,8 @@ pub struct IntrMaskingInfo {
 }
 
 lazy_static! {
-    static ref INTR_MASKING_INFO: UPSafeCellRaw<IntrMaskingInfo> = unsafe {
-        UPSafeCellRaw::new(IntrMaskingInfo::new()) 
-    };
+    static ref INTR_MASKING_INFO: UPSafeCellRaw<IntrMaskingInfo> =
+        unsafe { UPSafeCellRaw::new(IntrMaskingInfo::new()) };
 }
 
 impl IntrMaskingInfo {
@@ -71,7 +70,9 @@ impl IntrMaskingInfo {
 
     pub fn enter(&mut self) {
         let sie = sstatus::read().sie();
-        unsafe { sstatus::clear_sie(); }
+        unsafe {
+            sstatus::clear_sie();
+        }
         if self.nested_level == 0 {
             self.sie_before_masking = sie;
         }
@@ -81,7 +82,9 @@ impl IntrMaskingInfo {
     pub fn exit(&mut self) {
         self.nested_level -= 1;
         if self.nested_level == 0 && self.sie_before_masking {
-            unsafe { sstatus::set_sie(); }            
+            unsafe {
+                sstatus::set_sie();
+            }
         }
     }
 }
@@ -101,14 +104,17 @@ impl<T> UPIntrFreeCell<T> {
             inner: RefCell::new(value),
         }
     }
-    
+
     /// Panic if the data has been borrowed.
     pub fn exclusive_access(&self) -> UPIntrRefMut<'_, T> {
         INTR_MASKING_INFO.get_mut().enter();
         UPIntrRefMut(Some(self.inner.borrow_mut()))
     }
 
-    pub fn exclusive_session<F, V>(&self, f: F) -> V where F: FnOnce(&mut T) -> V {
+    pub fn exclusive_session<F, V>(&self, f: F) -> V
+    where
+        F: FnOnce(&mut T) -> V,
+    {
         let mut inner = self.exclusive_access();
         f(inner.deref_mut())
     }
@@ -132,4 +138,3 @@ impl<'a, T> DerefMut for UPIntrRefMut<'a, T> {
         self.0.as_mut().unwrap().deref_mut()
     }
 }
-
diff --git a/os/src/task/mod.rs b/os/src/task/mod.rs
index 6b4082b4..9f8e3b10 100644
--- a/os/src/task/mod.rs
+++ b/os/src/task/mod.rs
@@ -26,7 +26,6 @@ pub use processor::{
 pub use signal::SignalFlags;
 pub use task::{TaskControlBlock, TaskStatus};
 
-
 pub fn suspend_current_and_run_next() {
     // There must be an application running.
     let task = take_current_task().unwrap();
@@ -54,7 +53,7 @@ pub fn block_current_task() -> *mut TaskContext {
 }
 
 pub fn block_current_and_run_next() {
-    let task_cx_ptr = block_current_task(); 
+    let task_cx_ptr = block_current_task();
     schedule(task_cx_ptr);
 }
 
diff --git a/os/src/task/processor.rs b/os/src/task/processor.rs
index f196f681..dfa7d4c5 100644
--- a/os/src/task/processor.rs
+++ b/os/src/task/processor.rs
@@ -30,7 +30,8 @@ impl Processor {
 }
 
 lazy_static! {
-    pub static ref PROCESSOR: UPIntrFreeCell<Processor> = unsafe { UPIntrFreeCell::new(Processor::new()) };
+    pub static ref PROCESSOR: UPIntrFreeCell<Processor> =
+        unsafe { UPIntrFreeCell::new(Processor::new()) };
 }
 
 pub fn run_tasks() {
@@ -94,9 +95,8 @@ pub fn current_kstack_top() -> usize {
 }
 
 pub fn schedule(switched_task_cx_ptr: *mut TaskContext) {
-    let idle_task_cx_ptr = PROCESSOR.exclusive_session(|processor| {
-        processor.get_idle_task_cx_ptr()
-    });
+    let idle_task_cx_ptr =
+        PROCESSOR.exclusive_session(|processor| processor.get_idle_task_cx_ptr());
     unsafe {
         __switch(switched_task_cx_ptr, idle_task_cx_ptr);
     }
diff --git a/os/src/task/task.rs b/os/src/task/task.rs
index 85d949f8..c620890e 100644
--- a/os/src/task/task.rs
+++ b/os/src/task/task.rs
@@ -1,7 +1,10 @@
 use super::id::TaskUserRes;
 use super::{kstack_alloc, KernelStack, ProcessControlBlock, TaskContext};
 use crate::trap::TrapContext;
-use crate::{mm::PhysPageNum, sync::{UPIntrFreeCell, UPIntrRefMut}};
+use crate::{
+    mm::PhysPageNum,
+    sync::{UPIntrFreeCell, UPIntrRefMut},
+};
 use alloc::sync::{Arc, Weak};
 
 pub struct TaskControlBlock {
diff --git a/os/src/trap/mod.rs b/os/src/trap/mod.rs
index 5eb417dc..ce2aae8e 100644
--- a/os/src/trap/mod.rs
+++ b/os/src/trap/mod.rs
@@ -11,7 +11,7 @@ use core::arch::{asm, global_asm};
 use riscv::register::{
     mtvec::TrapMode,
     scause::{self, Exception, Interrupt, Trap},
-    sie, stval, stvec, sstatus, sscratch,
+    sie, sscratch, sstatus, stval, stvec,
 };
 
 global_asm!(include_str!("trap.S"));
@@ -23,7 +23,7 @@ pub fn init() {
 fn set_kernel_trap_entry() {
     extern "C" {
         fn __alltraps();
-        fn __alltraps_k(); 
+        fn __alltraps_k();
     }
     let __alltraps_k_va = __alltraps_k as usize - __alltraps as usize + TRAMPOLINE;
     unsafe {
@@ -52,7 +52,7 @@ fn enable_supervisor_interrupt() {
 
 fn disable_supervisor_interrupt() {
     unsafe {
-        sstatus::clear_sie(); 
+        sstatus::clear_sie();
     }
 }
 
@@ -67,7 +67,7 @@ pub fn trap_handler() -> ! {
             // jump to next instruction anyway
             let mut cx = current_trap_cx();
             cx.sepc += 4;
-            
+
             enable_supervisor_interrupt();
 
             // get system call return value
@@ -150,19 +150,19 @@ pub fn trap_from_kernel(_trap_cx: &TrapContext) {
     match scause.cause() {
         Trap::Interrupt(Interrupt::SupervisorExternal) => {
             crate::board::irq_handler();
-        },
+        }
         Trap::Interrupt(Interrupt::SupervisorTimer) => {
             set_next_trigger();
             check_timer();
             // do not schedule now
-        },
+        }
         _ => {
             panic!(
                 "Unsupported trap from kernel: {:?}, stval = {:#x}!",
                 scause.cause(),
                 stval
             );
-        },
+        }
     }
 }
 
diff --git a/user/src/bin/huge_write_mt.rs b/user/src/bin/huge_write_mt.rs
index 63146a58..8ca75783 100644
--- a/user/src/bin/huge_write_mt.rs
+++ b/user/src/bin/huge_write_mt.rs
@@ -5,9 +5,9 @@
 extern crate user_lib;
 extern crate alloc;
 
-use alloc::{vec::Vec, string::String, fmt::format};
+use alloc::{fmt::format, string::String, vec::Vec};
+use user_lib::{close, get_time, gettid, open, write, OpenFlags};
 use user_lib::{exit, thread_create, waittid};
-use user_lib::{close, get_time, open, write, OpenFlags, gettid};
 
 fn worker(size_kib: usize) {
     let mut buffer = [0u8; 1024]; // 1KiB
@@ -17,11 +17,11 @@ fn worker(size_kib: usize) {
     let filename = format(format_args!("testf{}\0", gettid()));
     let f = open(filename.as_str(), OpenFlags::CREATE | OpenFlags::WRONLY);
     if f < 0 {
-        panic!("Open test file failed!"); 
+        panic!("Open test file failed!");
     }
     let f = f as usize;
     for _ in 0..size_kib {
-        write(f, &buffer); 
+        write(f, &buffer);
     }
     close(f);
     exit(0)
@@ -34,18 +34,18 @@ pub fn main(argc: usize, argv: &[&str]) -> i32 {
     let size_kb = size_mb << 10;
     let workers = argv[1].parse::<usize>().expect("wrong argument");
     assert!(workers >= 1 && size_kb % workers == 0, "wrong argument");
-    
+
     let start = get_time();
-    
+
     let mut v = Vec::new();
     let size_mb = 1usize;
     for _ in 0..workers {
-        v.push(thread_create(worker as usize, size_kb / workers)); 
+        v.push(thread_create(worker as usize, size_kb / workers));
     }
     for tid in v.iter() {
         assert_eq!(0, waittid(*tid as usize));
     }
-    
+
     let time_ms = (get_time() - start) as usize;
     let speed_kbs = size_kb * 1000 / time_ms;
     println!(
diff --git a/user/src/bin/usertests.rs b/user/src/bin/usertests.rs
index 89f3ce51..32b28f6f 100644
--- a/user/src/bin/usertests.rs
+++ b/user/src/bin/usertests.rs
@@ -17,9 +17,7 @@ static SUCC_TESTS: &[&str] = &[
     "yield\0",
 ];
 
-static FAIL_TESTS: &[&str] = &[
-    "stack_overflow\0",
-];
+static FAIL_TESTS: &[&str] = &["stack_overflow\0"];
 
 use user_lib::{exec, fork, waitpid};