diff --git a/kernel/src/process/structs.rs b/kernel/src/process/structs.rs
index dbf9bca..8754f1e 100644
--- a/kernel/src/process/structs.rs
+++ b/kernel/src/process/structs.rs
@@ -98,6 +98,11 @@ impl Pid {
     pub fn get(&self) -> usize {
         self.0.unwrap()
     }
+
+    /// Return whether this pid represents the init process
+    pub fn is_init(&self) -> bool {
+        self.0 == Some(0)
+    }
 }
 
 impl fmt::Display for Pid {
diff --git a/kernel/src/shell.rs b/kernel/src/shell.rs
index ab5b1e0..1bd28b0 100644
--- a/kernel/src/shell.rs
+++ b/kernel/src/shell.rs
@@ -8,7 +8,7 @@ use crate::process::*;
 pub fn run_user_shell() {
     //use crate::net::server;
     //processor().manager().add(Thread::new_kernel(server, 0), 0);
-    if let Ok(inode) = ROOT_INODE.lookup("sh") {
+    if let Ok(inode) = ROOT_INODE.lookup("rust/sh") {
         println!("Going to user mode shell.");
         println!("Use 'ls' to list available programs.");
         let data = inode.read_as_vec().unwrap();
diff --git a/kernel/src/syscall/fs.rs b/kernel/src/syscall/fs.rs
index e0a8143..167052f 100644
--- a/kernel/src/syscall/fs.rs
+++ b/kernel/src/syscall/fs.rs
@@ -12,8 +12,11 @@ use crate::drivers::SOCKET_ACTIVITY;
 use super::*;
 
 pub fn sys_read(fd: usize, base: *mut u8, len: usize) -> SysResult {
-    info!("read: fd: {}, base: {:?}, len: {:#x}", fd, base, len);
     let mut proc = process();
+    if !proc.pid.is_init() {
+        // we trust pid 0 process
+        info!("read: fd: {}, base: {:?}, len: {:#x}", fd, base, len);
+    }
     proc.memory_set.check_mut_array(base, len)?;
     match proc.files.get(&fd) {
         Some(FileLike::File(_)) => sys_read_file(&mut proc, fd, base, len),
@@ -23,8 +26,11 @@ pub fn sys_read(fd: usize, base: *mut u8, len: usize) -> SysResult {
 }
 
 pub fn sys_write(fd: usize, base: *const u8, len: usize) -> SysResult {
-    info!("write: fd: {}, base: {:?}, len: {:#x}", fd, base, len);
     let mut proc = process();
+    if !proc.pid.is_init() {
+        // we trust pid 0 process
+        info!("write: fd: {}, base: {:?}, len: {:#x}", fd, base, len);
+    }
     proc.memory_set.check_array(base, len)?;
 
     match proc.files.get(&fd) {
diff --git a/kernel/src/syscall/mod.rs b/kernel/src/syscall/mod.rs
index ad8856f..8c3b714 100644
--- a/kernel/src/syscall/mod.rs
+++ b/kernel/src/syscall/mod.rs
@@ -35,7 +35,10 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
         process().pid.clone()
     };
     let tid = processor().tid();
-    debug!("{}:{}:{} syscall id {} begin", cid, pid, tid, id);
+    if !pid.is_init() {
+        // we trust pid 0 process
+        debug!("{}:{}:{} syscall id {} begin", cid, pid, tid, id);
+    }
     let ret = match id {
         // file
         000 => sys_read(args[0], args[1] as *mut u8, args[2]),
@@ -211,7 +214,10 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
             crate::trap::error(tf);
         }
     };
-    debug!("{}:{}:{} syscall id {} ret with {:x?}", cid, pid, tid, id, ret);
+    if !pid.is_init() {
+        // we trust pid 0 process
+        debug!("{}:{}:{} syscall id {} ret with {:x?}", cid, pid, tid, id, ret);
+    }
     match ret {
         Ok(code) => code as isize,
         Err(err) => -(err as isize),
diff --git a/kernel/src/syscall/proc.rs b/kernel/src/syscall/proc.rs
index b2eab2d..3c258f9 100644
--- a/kernel/src/syscall/proc.rs
+++ b/kernel/src/syscall/proc.rs
@@ -104,6 +104,7 @@ pub fn sys_exec(name: *const u8, argv: *const *const u8, envp: *const *const u8,
     let mut args = Vec::new();
     unsafe {
         let mut current_argv = argv as *const *const u8;
+        proc.memory_set.check_ptr(current_argv)?;
         while !(*current_argv).is_null() {
             let arg = proc.memory_set.check_and_clone_cstr(*current_argv)?;
             args.push(arg);
@@ -125,6 +126,9 @@ pub fn sys_exec(name: *const u8, argv: *const *const u8, envp: *const *const u8,
     let mut thread = Thread::new_user(buf.as_slice(), iter);
     thread.proc.lock().files = proc.files.clone();
     thread.proc.lock().cwd = proc.cwd.clone();
+    thread.proc.lock().pid = proc.pid.clone();
+    thread.proc.lock().parent = proc.parent.clone();
+    thread.proc.lock().threads = proc.threads.clone();
 
     // Activate new page table
     unsafe { thread.proc.lock().memory_set.activate(); }
diff --git a/user b/user
index bae6866..f0441d1 160000
--- a/user
+++ b/user
@@ -1 +1 @@
-Subproject commit bae6866610fc24ca66584c1a5200648d2de7d767
+Subproject commit f0441d1fe30022acfadced2224b00ed9a29db455