message: clears user stack during the initialization
diff: @@ -124,6 +124,14 @@ impl TaskStacks {
  flags,
  );
  + // clear user stack
  + ptr::write_bytes(
  + (virt_addr + KERNEL_STACK_SIZE + DEFAULT_STACK_SIZE + 3 * BasePageSize::SIZE)
  + as *mut u8,
  + 0,
  + user_stack_size,
  + );
  +
  TaskStacks::Common(CommonStack {
  virt_addr: virt_addr,
  phys_addr: phys_addr,
  