diff --git a/src/arch/x86_64/driver/serial.rs b/src/arch/x86_64/driver/serial.rs
index 66c6e22..bee8ad2 100644
--- a/src/arch/x86_64/driver/serial.rs
+++ b/src/arch/x86_64/driver/serial.rs
@@ -1,8 +1,8 @@
 // Copy from Redox
 
 use core::fmt::{self, Write};
+use redox_syscall::io::{Io, Mmio, Pio, ReadOnly};
 use spin::Mutex;
-use redox_syscall::io::{Io, Pio, Mmio, ReadOnly};
 
 pub static COM1: Mutex<Serial> = Mutex::new(Serial::new(0x3F8));
 pub static COM2: Mutex<Serial> = Mutex::new(Serial::new(0x2F8));
@@ -85,7 +85,7 @@ impl<T: Io<Value = u8>> SerialPort<T> {
     pub fn receive(&mut self) {
         while self.line_sts().contains(LineStsFlags::INPUT_FULL) {
             let data = self.data.read();
-            write!(self, "serial receive {}", data);
+            write!(self, "serial receive {}", data).unwrap();
             // TODO handle received data
         }
     }
diff --git a/src/arch/x86_64/gdt.rs b/src/arch/x86_64/gdt.rs
index daca7ad..4cddda9 100644
--- a/src/arch/x86_64/gdt.rs
+++ b/src/arch/x86_64/gdt.rs
@@ -1,24 +1,23 @@
-use core::fmt;
-use core::fmt::Debug;
-use x86_64::structures::tss::TaskStateSegment;
-use x86_64::structures::gdt::SegmentSelector;
-use x86_64::{PrivilegeLevel, VirtualAddress};
-use spin::{Once, Mutex, MutexGuard};
 use alloc::boxed::Box;
 use arch::driver::apic::lapic_id;
 use consts::MAX_CPU_NUM;
+use core::fmt;
+use core::fmt::Debug;
+use spin::{Mutex, MutexGuard, Once};
+use x86_64::{PrivilegeLevel, VirtualAddress};
+use x86_64::structures::gdt::SegmentSelector;
+use x86_64::structures::tss::TaskStateSegment;
 
 /// Alloc TSS & GDT at kernel heap, then init and load it.
 /// The double fault stack will be allocated at kernel heap too.
 pub fn init() {
-    use x86_64::structures::gdt::SegmentSelector;
     use x86_64::instructions::segmentation::set_cs;
     use x86_64::instructions::tables::load_tss;
 
     let double_fault_stack_top = Box::into_raw(Box::new([0u8; 4096])) as usize + 4096;
     debug!("Double fault stack top @ {:#x}", double_fault_stack_top);
 
-    let mut tss = Box::new({
+    let tss = Box::new({
         let mut tss = TaskStateSegment::new();
 
         // 设置 Double Fault 时，自动切换栈的地址
@@ -75,9 +74,7 @@ impl Cpu {
     /// 每次进入用户态前，都要调用此函数，才能保证正确返回内核态
     pub fn set_ring0_rsp(&mut self, rsp: usize) {
         trace!("gdt.set_ring0_rsp: {:#x}", rsp);
-        unsafe {
-            self.tss.privilege_stack_table[0] = VirtualAddress(rsp);
-        }
+        self.tss.privilege_stack_table[0] = VirtualAddress(rsp);
     }
 }
 
diff --git a/src/arch/x86_64/idt.rs b/src/arch/x86_64/idt.rs
index 2444ad4..7ce0f7b 100644
--- a/src/arch/x86_64/idt.rs
+++ b/src/arch/x86_64/idt.rs
@@ -1,4 +1,3 @@
-use alloc::boxed::Box;
 use x86_64::structures::idt::*;
 
 pub fn init() {
diff --git a/src/arch/x86_64/interrupt/handler.rs b/src/arch/x86_64/interrupt/handler.rs
index b221c95..c6635d2 100644
--- a/src/arch/x86_64/interrupt/handler.rs
+++ b/src/arch/x86_64/interrupt/handler.rs
@@ -64,6 +64,7 @@
 //!	deactivate CPU
 //! ```
 
+use super::consts::*;
 use super::TrapFrame;
 
 #[no_mangle]
@@ -74,7 +75,7 @@ pub extern fn rust_trap(tf: &mut TrapFrame) {
         T_BRKPT => breakpoint(),
         T_DBLFLT => double_fault(tf),
         T_PGFLT => page_fault(tf),
-        T_IRQ0...64 => {
+        T_IRQ0...63 => {
             let irq = tf.trap_num as u8 - T_IRQ0;
             match irq {
                 IRQ_TIMER => timer(),
@@ -123,8 +124,6 @@ fn page_fault(tf: &mut TrapFrame) {
     error(tf);
 }
 
-use super::consts::*;
-
 fn keyboard() {
     use arch::driver::keyboard;
     info!("\nInterupt: Keyboard");
diff --git a/src/arch/x86_64/paging/cow.rs b/src/arch/x86_64/paging/cow.rs
index b8ed039..bbba191 100644
--- a/src/arch/x86_64/paging/cow.rs
+++ b/src/arch/x86_64/paging/cow.rs
@@ -34,10 +34,10 @@
 //!
 //! * 为了维护引用计数，开一个全局映射 `RC_MAP`: Frame -> (read_count, write_count)
 
-use super::*;
-use alloc::rc::Rc;
 use alloc::BTreeMap;
-use spin::{Once, Mutex};
+pub use self::test::test_cow;
+use spin::Mutex;
+use super::*;
 use x86_64::instructions::tlb;
 use x86_64::VirtualAddress;
 
@@ -163,8 +163,6 @@ impl FrameRcMap {
     }
 }
 
-pub use self::test::test_cow;
-
 mod test {
     use super::*;
 
diff --git a/src/arch/x86_64/paging/entry.rs b/src/arch/x86_64/paging/entry.rs
index 3746074..9193cc4 100644
--- a/src/arch/x86_64/paging/entry.rs
+++ b/src/arch/x86_64/paging/entry.rs
@@ -49,13 +49,3 @@ bitflags! {
         const COW =             2 << 9;
     }
 }
-
-use core::fmt;
-use core::fmt::Debug;
-
-impl Debug for Entry {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        write!(f, "{:#014X} {:?}", self.0 & 0x000fffff_fffff000, self.flags());
-        Ok(())
-    }
-}
diff --git a/src/arch/x86_64/paging/mapper.rs b/src/arch/x86_64/paging/mapper.rs
index 76e0013..27b0fc1 100644
--- a/src/arch/x86_64/paging/mapper.rs
+++ b/src/arch/x86_64/paging/mapper.rs
@@ -1,7 +1,7 @@
-use super::{Page, ENTRY_COUNT, EntryFlags};
-use super::table::{self, Table, Level4, Level1};
-use memory::*;
 use core::ptr::Unique;
+use memory::*;
+use super::{ENTRY_COUNT, EntryFlags, Page};
+use super::table::{self, Level1, Level4, Table};
 
 pub struct Mapper {
     p4: Unique<Table<Level4>>,
@@ -71,9 +71,9 @@ impl Mapper {
     pub(super) fn entry_mut(&mut self, page: Page) -> &mut Entry {
         use core::ops::IndexMut;
         let p4 = self.p4_mut();
-        let mut p3 = p4.next_table_create(page.p4_index());
-        let mut p2 = p3.next_table_create(page.p3_index());
-        let mut p1 = p2.next_table_create(page.p2_index());
+        let p3 = p4.next_table_create(page.p4_index());
+        let p2 = p3.next_table_create(page.p3_index());
+        let p1 = p2.next_table_create(page.p2_index());
         p1.index_mut(page.p1_index())
     }
 
diff --git a/src/arch/x86_64/paging/mod.rs b/src/arch/x86_64/paging/mod.rs
index 773583d..85370bb 100644
--- a/src/arch/x86_64/paging/mod.rs
+++ b/src/arch/x86_64/paging/mod.rs
@@ -1,9 +1,9 @@
+use core::ops::{Add, Deref, DerefMut};
+use memory::*;
+pub use self::cow::*;
 pub use self::entry::*;
 pub use self::mapper::Mapper;
-use core::ops::{Deref, DerefMut, Add};
-use memory::*;
 pub use self::temporary_page::TemporaryPage;
-pub use self::cow::*;
 
 mod entry;
 mod table;
@@ -118,7 +118,7 @@ impl ActivePageTable {
         use x86_64::instructions::tlb;
         use x86_64::registers::control_regs;
 
-        let mut temporary_page = TemporaryPage::new(Page::of_addr(0xcafebabe));
+        let temporary_page = TemporaryPage::new();
         {
             let backup = Frame::of_addr(
                 control_regs::cr3().0 as usize);
@@ -142,7 +142,6 @@ impl ActivePageTable {
     }
 
     pub fn switch(&mut self, new_table: InactivePageTable) -> InactivePageTable {
-        use x86_64::PhysicalAddress;
         use x86_64::registers::control_regs;
         debug!("switch table {:?} -> {:?}", Frame::of_addr(control_regs::cr3().0 as usize), new_table.p4_frame);
         if new_table.p4_frame.start_address() == control_regs::cr3() {
@@ -168,7 +167,7 @@ pub struct InactivePageTable {
 
 impl InactivePageTable {
     pub fn new(frame: Frame, active_table: &mut ActivePageTable) -> InactivePageTable {
-        let mut temporary_page = TemporaryPage::new(Page::of_addr(0xcafebabe));
+        let temporary_page = TemporaryPage::new();
         {
             let table = temporary_page.map_table_frame(frame.clone(),
                 active_table);
diff --git a/src/arch/x86_64/paging/temporary_page.rs b/src/arch/x86_64/paging/temporary_page.rs
index d3406f8..136452d 100644
--- a/src/arch/x86_64/paging/temporary_page.rs
+++ b/src/arch/x86_64/paging/temporary_page.rs
@@ -1,21 +1,18 @@
-use super::{Page, ActivePageTable};
-use super::table::{Table, Level1};
-use memory::{Frame, FrameAllocator, VirtAddr};
+use super::*;
+use super::table::{Level1, Table};
 
 pub struct TemporaryPage {
     page: Page,
 }
 
 impl TemporaryPage {
-    pub fn new(page: Page) -> TemporaryPage {
-        TemporaryPage { page }
+    pub fn new() -> TemporaryPage {
+        TemporaryPage { page: Page::of_addr(0xcafebabe) }
     }
 
     /// Maps the temporary page to the given frame in the active table.
     /// Returns the start address of the temporary page.
-    pub fn map(&self, frame: Frame, active_table: &mut ActivePageTable)
-        -> VirtAddr
-    {
+    pub fn map(&self, frame: Frame, active_table: &mut ActivePageTable) -> VirtAddr {
         use super::entry::EntryFlags;
 
         assert!(active_table.translate_page(self.page).is_none(),
@@ -31,10 +28,7 @@ impl TemporaryPage {
 
     /// Maps the temporary page to the given page table frame in the active
     /// table. Returns a reference to the now mapped table.
-    pub fn map_table_frame(&self,
-                        frame: Frame,
-                        active_table: &mut ActivePageTable)
-                        -> &mut Table<Level1> {
+    pub fn map_table_frame(&self, frame: Frame, active_table: &mut ActivePageTable) -> &mut Table<Level1> {
         unsafe { &mut *(self.map(frame, active_table) as *mut Table<Level1>) }
     }
 }
diff --git a/src/io/mod.rs b/src/io/mod.rs
index 7f54ac3..416951f 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -1,5 +1,8 @@
-use core::fmt;
 use arch::driver::serial::COM1;
+use arch::driver::vga::Color;
+use core::fmt;
+use log;
+use log::{Level, LevelFilter, Log, Metadata, Record};
 
 mod vga_writer;
 
@@ -35,11 +38,9 @@ macro_rules! with_color {
     }};
 }
 
-use arch::driver::vga::Color;
-
 fn print_in_color(args: fmt::Arguments, color: Color) {
     use core::fmt::Write;
-    use arch::driver::vga::*;
+//    use arch::driver::vga::*;
 //    {
 //        let mut writer = vga_writer::VGA_WRITER.lock();
 //        writer.set_color(color);
@@ -57,9 +58,6 @@ pub fn print(args: fmt::Arguments) {
     COM1.lock().write_fmt(args).unwrap();
 }
 
-use log;
-use log::{Record, Level, Metadata, Log, SetLoggerError, LevelFilter};
-
 struct SimpleLogger;
 
 impl Log for SimpleLogger {
diff --git a/src/macros.rs b/src/macros.rs
index 31049c5..d349beb 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -17,7 +17,6 @@ macro_rules! test {
 	($func:ident) => (
 		if cfg!(feature = "test") {
 			println!("Testing: {}", stringify!($func));
-			use self::test::$func;
 			test::$func();
 			println!("Success: {}", stringify!($func));
 		}
diff --git a/src/memory/frame.rs b/src/memory/frame.rs
index 7f1d39e..5c38cf3 100644
--- a/src/memory/frame.rs
+++ b/src/memory/frame.rs
@@ -1,5 +1,4 @@
 use super::address::PhysAddr;
-use memory::FRAME_ALLOCATOR;
 
 pub const PAGE_SIZE: usize = 4096;
 
@@ -20,34 +19,8 @@ impl Frame {
     pub fn clone(&self) -> Frame {
         Frame { number: self.number }
     }
-    //TODO: Set private    
-    pub fn range_inclusive(start: Frame, end: Frame) -> FrameIter {
-        FrameIter {
-            start,
-            end,
-        }
-    }
-}
-
-pub struct FrameIter {
-    start: Frame,
-    end: Frame,
 }
 
-impl Iterator for FrameIter {
-    type Item = Frame;
-
-    fn next(&mut self) -> Option<Frame> {
-        if self.start <= self.end {
-            let frame = self.start.clone();
-            self.start.number += 1;
-            Some(frame)
-        } else {
-            None
-        }
-    }
- }
-
 pub trait FrameAllocator {
     fn allocate_frame(&mut self) -> Option<Frame>;
     fn deallocate_frame(&mut self, frame: Frame);
diff --git a/src/memory/heap_allocator.rs b/src/memory/heap_allocator.rs
deleted file mode 100644
index 0a232f9..0000000
--- a/src/memory/heap_allocator.rs
+++ /dev/null
@@ -1,62 +0,0 @@
-use alloc::heap::{Alloc, AllocErr, Layout};
-
-use core::sync::atomic::{AtomicUsize, Ordering};
-
-/// A simple allocator that allocates memory linearly and ignores freed memory.
-#[derive(Debug)]
-pub struct BumpAllocator {
-    heap_start: usize,
-    heap_end: usize,
-    next: AtomicUsize,
-}
-
-impl BumpAllocator {
-    pub const fn new(heap_start: usize, heap_end: usize) -> Self {
-        Self { heap_start, heap_end, next: AtomicUsize::new(heap_start) }
-    }
-}
-
-unsafe impl<'a> Alloc for &'a BumpAllocator {
-    unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
-        loop {
-            // load current state of the `next` field
-            let current_next = self.next.load(Ordering::Relaxed);
-            let alloc_start = align_up(current_next, layout.align());
-            let alloc_end = alloc_start.saturating_add(layout.size());
-
-            if alloc_end <= self.heap_end {
-                // update the `next` pointer if it still has the value `current_next`
-                let next_now = self.next.compare_and_swap(current_next, alloc_end,
-                    Ordering::Relaxed);
-                if next_now == current_next {
-                    // next address was successfully updated, allocation succeeded
-                    return Ok(alloc_start as *mut u8);
-                }
-            } else {
-                return Err(AllocErr::Exhausted{ request: layout })
-            }
-        }
-    }
-
-    unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
-        // do nothing, leak memory
-    }
-}
-
-/// Align downwards. Returns the greatest x with alignment `align`
-/// so that x <= addr. The alignment must be a power of 2.
-pub fn align_down(addr: usize, align: usize) -> usize {
-    if align.is_power_of_two() {
-        addr & !(align - 1)
-    } else if align == 0 {
-        addr
-    } else {
-        panic!("`align` must be a power of 2");
-    }
-}
-
-/// Align upwards. Returns the smallest x with alignment `align`
-/// so that x >= addr. The alignment must be a power of 2.
-pub fn align_up(addr: usize, align: usize) -> usize {
-    align_down(addr + align - 1, align)
-}
diff --git a/src/memory/mod.rs b/src/memory/mod.rs
index f756907..4dc32b9 100644
--- a/src/memory/mod.rs
+++ b/src/memory/mod.rs
@@ -1,17 +1,17 @@
 pub use arch::paging::*;
-pub use self::stack_allocator::*;
+use arch::paging;
+use bit_allocator::{BitAlloc, BitAlloc64K};
+use consts::KERNEL_OFFSET;
+use multiboot2::{ElfSection, ElfSectionFlags, ElfSectionsTag};
+use multiboot2::BootInformation;
 pub use self::address::*;
 pub use self::frame::*;
 pub use self::memory_set::*;
-
-use multiboot2::BootInformation;
-use consts::KERNEL_OFFSET;
-use arch::paging;
+pub use self::stack_allocator::*;
 use spin::{Mutex, MutexGuard};
 use super::HEAP_ALLOCATOR;
 
 mod memory_set;
-pub mod heap_allocator;
 mod stack_allocator;
 mod address;
 mod frame;
@@ -74,8 +74,6 @@ pub fn init(boot_info: BootInformation) -> MemorySet {
     kernel_memory
 }
 
-use bit_allocator::{BitAlloc64K, BitAlloc};
-
 impl FrameAllocator for BitAlloc64K {
     fn allocate_frame(&mut self) -> Option<Frame> {
         self.alloc().map(|x| Frame { number: x })
@@ -150,8 +148,6 @@ fn get_init_kstack_and_set_guard_page() -> Stack {
     Stack::new(stack_bottom + 8 * PAGE_SIZE, stack_bottom + 1 * PAGE_SIZE)
 }
 
-use multiboot2::{ElfSectionsTag, ElfSection, ElfSectionFlags};
-
 impl From<ElfSectionsTag> for MemorySet {
     fn from(sections: ElfSectionsTag) -> Self {
         assert_has_not_been_called!();
@@ -167,7 +163,6 @@ impl From<ElfSectionsTag> for MemorySet {
 
 impl From<ElfSection> for MemoryArea {
     fn from(section: ElfSection) -> Self {
-        use self::address::FromToVirtualAddress;
         let mut start_addr = section.start_address() as usize;
         let mut end_addr = section.end_address() as usize;
         assert_eq!(start_addr % PAGE_SIZE, 0, "sections need to be page aligned");
diff --git a/src/process/mod.rs b/src/process/mod.rs
index c615875..4bc4b6e 100644
--- a/src/process/mod.rs
+++ b/src/process/mod.rs
@@ -1,18 +1,16 @@
-use memory::MemorySet;
-use spin::Once;
-use sync::SpinNoIrqLock;
-use core::slice;
 use alloc::String;
-
+use memory::MemorySet;
 use self::process::*;
 pub use self::processor::*;
+use spin::Once;
+use sync::SpinNoIrqLock;
 
 mod process;
 mod processor;
 mod scheduler;
 
 
-pub fn init(mut ms: MemorySet) {
+pub fn init(ms: MemorySet) {
     PROCESSOR.call_once(|| {
         SpinNoIrqLock::new({
             let initproc = Process::new_init(ms);
@@ -26,7 +24,7 @@ pub fn init(mut ms: MemorySet) {
 
 pub static PROCESSOR: Once<SpinNoIrqLock<Processor>> = Once::new();
 
-extern fn idle_thread(arg: usize) -> ! {
+extern fn idle_thread(_arg: usize) -> ! {
     loop {}
 }
 
@@ -39,7 +37,7 @@ pub fn add_user_process(name: impl AsRef<str>, data: &[u8]) {
 
 pub fn add_kernel_process(entry: extern fn(usize) -> !, arg: usize) -> Pid {
     let mut processor = PROCESSOR.try().unwrap().lock();
-    let mut new = Process::new("", entry, arg);
+    let new = Process::new("", entry, arg);
     processor.add(new)
 }
 
diff --git a/src/process/process.rs b/src/process/process.rs
index f757a58..b4a0735 100644
--- a/src/process/process.rs
+++ b/src/process/process.rs
@@ -1,9 +1,7 @@
-use super::*;
-use memory::{self, Stack, InactivePageTable, MemoryAttr};
-use xmas_elf::{ElfFile, program::{Flags, ProgramHeader}, header::HeaderPt2};
-use core::slice;
-use alloc::{rc::Rc, String};
+use alloc::String;
 use arch::interrupt::*;
+use memory::{MemoryArea, MemoryAttr, MemorySet};
+use xmas_elf::{ElfFile, header::HeaderPt2, program::{Flags, ProgramHeader}};
 
 #[derive(Debug)]
 pub struct Process {
@@ -66,7 +64,6 @@ impl Process {
     /// uCore x86 32bit program is planned to be supported.
     pub fn new_user(data: &[u8]) -> Self {
         // Parse elf
-        let begin = data.as_ptr() as usize;
         let elf = ElfFile::new(data).expect("failed to read elf");
         let is32 = match elf.header.pt2 {
             HeaderPt2::Header32(_) => true,
@@ -97,6 +94,7 @@ impl Process {
                     ProgramHeader::Ph32(ph) => (ph.virtual_addr as usize, ph.offset as usize, ph.file_size as usize),
                     ProgramHeader::Ph64(ph) => (ph.virtual_addr as usize, ph.offset as usize, ph.file_size as usize),
                 };
+                use core::slice;
                 let target = unsafe { slice::from_raw_parts_mut(virt_addr as *mut u8, file_size) };
                 target.copy_from_slice(&data[offset..offset + file_size]);
             }
@@ -168,8 +166,6 @@ impl Process {
     }
 }
 
-use memory::{MemorySet, MemoryArea, PhysAddr, FromToVirtualAddress, EntryFlags};
-
 impl<'a> From<&'a ElfFile<'a>> for MemorySet {
     fn from(elf: &'a ElfFile<'a>) -> Self {
         let mut set = MemorySet::new(7);
diff --git a/src/process/processor.rs b/src/process/processor.rs
index 45788cf..a98726d 100644
--- a/src/process/processor.rs
+++ b/src/process/processor.rs
@@ -1,11 +1,8 @@
 use alloc::BTreeMap;
-use memory::{ActivePageTable, InactivePageTable};
+use core::fmt::{Debug, Error, Formatter};
 use super::process::*;
 use super::scheduler::*;
-use core::cell::RefCell;
-use core::fmt::{Debug, Formatter, Error};
 use util::{EventHub, GetMut2};
-use arch::interrupt::*;
 
 pub struct Processor {
     procs: BTreeMap<Pid, Process>,
diff --git a/src/sync/mutex.rs b/src/sync/mutex.rs
index 9b8c00f..ce1b3ba 100644
--- a/src/sync/mutex.rs
+++ b/src/sync/mutex.rs
@@ -26,10 +26,12 @@
 //! `MutexSupport`提供了若干接口，它们会在操作锁的不同时间点被调用。
 //! 注意这个接口实际是取了几种实现的并集，并不是很通用。
 
-use core::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
+use arch::interrupt;
 use core::cell::UnsafeCell;
-use core::ops::{Deref, DerefMut};
 use core::fmt;
+use core::ops::{Deref, DerefMut};
+use core::sync::atomic::{ATOMIC_BOOL_INIT, AtomicBool, Ordering};
+use super::Condvar;
 
 pub type SpinLock<T> = Mutex<T, Spin>;
 pub type SpinNoIrqLock<T> = Mutex<T, SpinNoIrq>;
@@ -89,7 +91,7 @@ impl<T, S: MutexSupport> Mutex<T, S>
         // We know statically that there are no outstanding references to
         // `self` so there's no need to lock.
         let Mutex { data, .. } = self;
-        unsafe { data.into_inner() }
+        data.into_inner()
     }
 }
 
@@ -222,8 +224,6 @@ impl MutexSupport for Spin {
     fn after_unlock(&self) {}
 }
 
-use arch::interrupt;
-
 /// Spin & no-interrupt lock
 #[derive(Debug)]
 pub struct SpinNoIrq;
@@ -251,10 +251,6 @@ impl MutexSupport for SpinNoIrq {
     fn after_unlock(&self) {}
 }
 
-use thread;
-use alloc::VecDeque;
-use super::Condvar;
-
 impl MutexSupport for Condvar {
     type GuardData = ();
     fn new() -> Self {
diff --git a/src/syscall.rs b/src/syscall.rs
index 7a42e28..902cdce 100644
--- a/src/syscall.rs
+++ b/src/syscall.rs
@@ -1,5 +1,7 @@
 //! 系统调用解析执行模块
 
+#![allow(unused)]
+
 use arch::interrupt::TrapFrame;
 use process::*;
 use thread;
diff --git a/src/util.rs b/src/util.rs
index 5f72c47..4092e99 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,3 +1,6 @@
+use core::fmt::Debug;
+pub use self::event::EventHub;
+
 pub fn bytes_sum<T>(p: &T) -> u8 {
 	use core::mem::size_of_val;
 	let len = size_of_val(p);
@@ -26,9 +29,6 @@ pub unsafe fn from_cstr(s: *const u8) -> &'static str {
     str::from_utf8(slice::from_raw_parts(s, len)).unwrap()
 }
 
-use core::ops::IndexMut;
-use core::fmt::Debug;
-
 /// Get values by 2 diff keys at the same time
 pub trait GetMut2<Idx: Debug + Eq> {
     type Output;
@@ -44,8 +44,6 @@ pub trait GetMut2<Idx: Debug + Eq> {
 }
 
 
-pub use self::event::EventHub;
-
 mod event {
     use alloc::BinaryHeap;
     use core::cmp::{Ordering, PartialOrd};