diff --git a/os/src/mm/memory_set.rs b/os/src/mm/memory_set.rs
index 93e2f43..a6a0fdb 100644
--- a/os/src/mm/memory_set.rs
+++ b/os/src/mm/memory_set.rs
@@ -241,27 +241,27 @@ impl MemorySet {
         self.page_table.translate(vpn)
     }
     #[allow(unused)]
-    pub fn shrink_to(&mut self, start: VirtAddr, end: VirtAddr, new_end: VirtAddr) -> bool {
+    pub fn shrink_to(&mut self, start: VirtAddr, new_end: VirtAddr) -> bool {
         if let Some(area) = self
             .areas
             .iter_mut()
-            .find(|area| area.vpn_range.get_start() == start.floor()
-            && area.vpn_range.get_end() == end.ceil()) {
-                area.shrink_to(&mut self.page_table, new_end.ceil());
-                true
+            .find(|area| area.vpn_range.get_start() == start.floor())
+        {
+            area.shrink_to(&mut self.page_table, new_end.ceil());
+            true
         } else {
             false
         }
     }
     #[allow(unused)]
-    pub fn append_to(&mut self, start: VirtAddr, end: VirtAddr, new_end: VirtAddr) -> bool {
+    pub fn append_to(&mut self, start: VirtAddr, new_end: VirtAddr) -> bool {
         if let Some(area) = self
             .areas
             .iter_mut()
-            .find(|area| area.vpn_range.get_start() == start.floor()
-            && area.vpn_range.get_end() == end.ceil()) {
-                area.append_to(&mut self.page_table, new_end.ceil());
-                true
+            .find(|area| area.vpn_range.get_start() == start.floor())
+        {
+            area.append_to(&mut self.page_table, new_end.ceil());
+            true
         } else {
             false
         }
diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index cdee65b..269581f 100644
--- a/os/src/sbi.rs
+++ b/os/src/sbi.rs
@@ -44,7 +44,6 @@ pub fn console_putchar(c: usize) {
 // pub fn console_getchar() -> usize {
 //     sbi_call(SBI_CONSOLE_GETCHAR, 0, 0, 0)
 // }
-
 use crate::board::QEMUExit;
 /// use sbi call to shutdown the kernel
 pub fn shutdown() -> ! {
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index a39914a..d302373 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -1,6 +1,6 @@
 //! Process management syscalls
 
-use crate::task::{exit_current_and_run_next, suspend_current_and_run_next, change_program_brk};
+use crate::task::{change_program_brk, exit_current_and_run_next, suspend_current_and_run_next};
 use crate::timer::get_time_ms;
 
 /// task exits and submit an exit code
@@ -28,4 +28,4 @@ pub fn sys_sbrk(size: i32) -> isize {
     } else {
         -1
     }
-}
\ No newline at end of file
+}
diff --git a/os/src/task/mod.rs b/os/src/task/mod.rs
index bba26a1..dd27422 100644
--- a/os/src/task/mod.rs
+++ b/os/src/task/mod.rs
@@ -126,7 +126,7 @@ impl TaskManager {
         inner.tasks[inner.current_task].get_trap_cx()
     }
 
-    /// Change the current 'Running' task's program break 
+    /// Change the current 'Running' task's program break
     pub fn change_current_program_brk(&self, size: i32) -> Option<usize> {
         let mut inner = self.inner.exclusive_access();
         let cur = inner.current_task;
@@ -200,7 +200,7 @@ pub fn current_trap_cx() -> &'static mut TrapContext {
     TASK_MANAGER.get_current_trap_cx()
 }
 
- /// Change the current 'Running' task's program break 
- pub fn change_program_brk(size: i32) -> Option<usize> {
+/// Change the current 'Running' task's program break
+pub fn change_program_brk(size: i32) -> Option<usize> {
     TASK_MANAGER.change_current_program_brk(size)
- }
+}
diff --git a/os/src/task/task.rs b/os/src/task/task.rs
index 64e9f67..6c87ddd 100644
--- a/os/src/task/task.rs
+++ b/os/src/task/task.rs
@@ -62,12 +62,14 @@ impl TaskControlBlock {
         let old_break = self.program_brk;
         let new_brk = self.program_brk as isize + size as isize;
         if new_brk < self.heap_bottom as isize {
-            return None
+            return None;
         }
         let result = if size < 0 {
-            self.memory_set.shrink_to(VirtAddr(self.heap_bottom), VirtAddr(self.program_brk), VirtAddr(new_brk as usize))
+            self.memory_set
+                .shrink_to(VirtAddr(self.heap_bottom), VirtAddr(new_brk as usize))
         } else {
-            self.memory_set.append_to(VirtAddr(self.heap_bottom), VirtAddr(self.program_brk), VirtAddr(new_brk as usize))
+            self.memory_set
+                .append_to(VirtAddr(self.heap_bottom), VirtAddr(new_brk as usize))
         };
         if result {
             self.program_brk = new_brk as usize;
diff --git a/user/src/bin/sbrk_test.rs b/user/src/bin/sbrk_test.rs
index 3dfe4f4..af21bd1 100644
--- a/user/src/bin/sbrk_test.rs
+++ b/user/src/bin/sbrk_test.rs
@@ -42,6 +42,5 @@ fn main() -> i32 {
     for pos in 0..PAGE_SIZE {
         new_page[pos] = 2;
     }
-    println!("Test sbrk OK!");
     0
 }