diff --git a/crate/memory/src/paging/mod.rs b/crate/memory/src/paging/mod.rs
index ccb2a0e..322df2c 100644
--- a/crate/memory/src/paging/mod.rs
+++ b/crate/memory/src/paging/mod.rs
@@ -3,7 +3,6 @@
 //! Implemented for every architecture, used by OS.
 
 use super::*;
-use log::*;
 #[cfg(test)]
 pub use self::mock_page_table::MockPageTable;
 pub use self::ext::*;
diff --git a/crate/memory/src/swap/mod.rs b/crate/memory/src/swap/mod.rs
index 14a027a..5f47391 100644
--- a/crate/memory/src/swap/mod.rs
+++ b/crate/memory/src/swap/mod.rs
@@ -296,7 +296,7 @@ impl<T: PageTable, M: SwapManager, S: Swapper> SwapExt<T, M, S> {
                     entry.set_present(true);
                     entry.update();
                 }
-                if(swapin){
+                if swapin {
                     unsafe {
                         self.set_swappable(pt, addr & 0xfffff000);
                     }
diff --git a/crate/process/src/process_manager.rs b/crate/process/src/process_manager.rs
index b6e8af6..d052470 100644
--- a/crate/process/src/process_manager.rs
+++ b/crate/process/src/process_manager.rs
@@ -1,9 +1,7 @@
 use alloc::boxed::Box;
-use alloc::sync::Arc;
 use alloc::vec::Vec;
 use spin::Mutex;
 use log::*;
-use core::cell::UnsafeCell;
 use crate::scheduler::Scheduler;
 use crate::event_hub::EventHub;
 
diff --git a/crate/process/src/processor.rs b/crate/process/src/processor.rs
index d29d560..e316324 100644
--- a/crate/process/src/processor.rs
+++ b/crate/process/src/processor.rs
@@ -1,6 +1,5 @@
 use alloc::boxed::Box;
 use alloc::sync::Arc;
-use spin::Mutex;
 use log::*;
 use core::cell::UnsafeCell;
 use crate::process_manager::*;
@@ -30,14 +29,12 @@ impl Processor {
     }
 
     pub unsafe fn init(&self, id: usize, context: Box<Context>, manager: Arc<ProcessManager>) {
-        unsafe {
-            *self.inner.get() = Some(ProcessorInner {
-                id,
-                proc: None,
-                loop_context: context,
-                manager,
-            });
-        }
+        *self.inner.get() = Some(ProcessorInner {
+            id,
+            proc: None,
+            loop_context: context,
+            manager,
+        });
     }
 
     fn inner(&self) -> &mut ProcessorInner {
diff --git a/crate/process/src/thread.rs b/crate/process/src/thread.rs
index d333bc1..65406c4 100644
--- a/crate/process/src/thread.rs
+++ b/crate/process/src/thread.rs
@@ -7,14 +7,11 @@
 //! - `new_kernel_context`: Construct a `Context` of the new kernel thread
 
 use alloc::boxed::Box;
-use alloc::collections::BTreeMap;
 use core::marker::PhantomData;
-use core::ptr;
 use core::time::Duration;
 use log::*;
 use crate::processor::*;
 use crate::process_manager::*;
-use crate::scheduler::Scheduler;
 
 #[linkage = "weak"]
 #[no_mangle]
diff --git a/kernel/src/fs.rs b/kernel/src/fs.rs
index 725642d..7c6d4cc 100644
--- a/kernel/src/fs.rs
+++ b/kernel/src/fs.rs
@@ -1,7 +1,6 @@
 use simple_filesystem::*;
 use alloc::{boxed::Box, sync::Arc, string::String, collections::VecDeque, vec::Vec};
 use core::any::Any;
-use core::slice;
 use lazy_static::lazy_static;
 #[cfg(target_arch = "x86_64")]
 use crate::arch::driver::ide;
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index 3199250..b5190fe 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -2,4 +2,5 @@
 #![cfg_attr(not(test), no_main)] // disable all Rust-level entry points
 #![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
 
+#[allow(unused_imports)]
 use ucore;
\ No newline at end of file
diff --git a/kernel/src/memory.rs b/kernel/src/memory.rs
index 295e26e..875c9b2 100644
--- a/kernel/src/memory.rs
+++ b/kernel/src/memory.rs
@@ -2,13 +2,11 @@ pub use crate::arch::paging::*;
 use bit_allocator::BitAlloc;
 use crate::consts::MEMORY_OFFSET;
 use super::HEAP_ALLOCATOR;
-use ucore_memory::{*, paging::PageTable};
+use ucore_memory::*;
 use ucore_memory::cow::CowExt;
 pub use ucore_memory::memory_set::{MemoryArea, MemoryAttr, handler::*};
-use ucore_memory::swap::*;
 use crate::process::{process};
 use crate::sync::{SpinNoIrqLock, SpinNoIrq, MutexGuard};
-use alloc::collections::VecDeque;
 use lazy_static::*;
 use log::*;
 use linked_list_allocator::LockedHeap;
diff --git a/kernel/src/process/context.rs b/kernel/src/process/context.rs
index c115bdf..e83e364 100644
--- a/kernel/src/process/context.rs
+++ b/kernel/src/process/context.rs
@@ -4,10 +4,10 @@ use log::*;
 use simple_filesystem::file::File;
 use spin::Mutex;
 use ucore_process::Context;
-use xmas_elf::{ElfFile, header, program::{Flags, ProgramHeader, SegmentData, Type}};
+use xmas_elf::{ElfFile, header, program::{Flags, Type}};
 
 use crate::arch::interrupt::{Context as ArchContext, TrapFrame};
-use crate::memory::{ByFrame, Delay, FrameAllocator, GlobalFrameAlloc, KernelStack, MemoryArea, MemoryAttr, MemorySet};
+use crate::memory::{ByFrame, GlobalFrameAlloc, KernelStack, MemoryAttr, MemorySet};
 
 // TODO: avoid pub
 pub struct Process {
@@ -110,7 +110,7 @@ impl Process {
     pub fn fork(&self, tf: &TrapFrame) -> Box<Context> {
         info!("COME into fork!");
         // Clone memory set, make a new page table
-        let mut memory_set = self.memory_set.clone();
+        let memory_set = self.memory_set.clone();
         info!("finish mmset clone in fork!");
 
         // MMU:   copy data to the new space
@@ -149,7 +149,6 @@ unsafe fn push_slice<T: Copy>(mut sp: usize, vs: &[T]) -> usize {
 unsafe fn push_args_at_stack<'a, Iter>(args: Iter, stack_top: usize) -> usize
     where Iter: Iterator<Item=&'a str>
 {
-    use core::{ptr, slice};
     let mut sp = stack_top;
     let mut argv = Vec::new();
     for arg in args {
diff --git a/kernel/src/process/mod.rs b/kernel/src/process/mod.rs
index 790e4ce..2f2a4e5 100644
--- a/kernel/src/process/mod.rs
+++ b/kernel/src/process/mod.rs
@@ -1,11 +1,8 @@
-use spin::Mutex;
 pub use self::context::Process;
 pub use ucore_process::*;
 use crate::consts::{MAX_CPU_NUM, MAX_PROCESS_NUM};
 use crate::arch::cpu;
-use alloc::{boxed::Box, sync::Arc, vec::Vec};
-use crate::sync::Condvar;
-use core::sync::atomic::*;
+use alloc::{boxed::Box, sync::Arc};
 use log::*;
 
 pub mod context;
diff --git a/kernel/src/shell.rs b/kernel/src/shell.rs
index 236bb42..cddd898 100644
--- a/kernel/src/shell.rs
+++ b/kernel/src/shell.rs
@@ -1,7 +1,6 @@
 //! Kernel shell
 
 use alloc::string::String;
-use alloc::vec::Vec;
 use crate::fs::{ROOT_INODE, INodeExt};
 use crate::process::*;
 
diff --git a/kernel/src/syscall.rs b/kernel/src/syscall.rs
index 2a7ffdf..e438ee8 100644
--- a/kernel/src/syscall.rs
+++ b/kernel/src/syscall.rs
@@ -141,7 +141,7 @@ fn sys_dup(fd1: usize, fd2: usize) -> SysResult {
 
 /// Fork the current process. Return the child's PID.
 fn sys_fork(tf: &TrapFrame) -> SysResult {
-    let mut context = process().fork(tf);
+    let context = process().fork(tf);
     //memory_set_map_swappable(context.get_memory_set_mut());
     let pid = processor().manager().add(context, thread::current().id());
     //memory_set_map_swappable(processor.get_context_mut(pid).get_memory_set_mut());
@@ -374,6 +374,7 @@ impl From<FileInfo> for Stat {
             mode: match info.type_ {
                 FileType::File => StatMode::FILE,
                 FileType::Dir => StatMode::DIR,
+                #[allow(unreachable_patterns)]
                 _ => StatMode::NULL,
             },
             nlinks: info.nlinks as u32,
diff --git a/kernel/src/util.rs b/kernel/src/util.rs
index 1629386..a4ff86a 100644
--- a/kernel/src/util.rs
+++ b/kernel/src/util.rs
@@ -1,5 +1,3 @@
-use core::fmt::Debug;
-
 /// Convert C string to Rust string
 pub unsafe fn from_cstr(s: *const u8) -> &'static str {
     use core::{str, slice};