diff --git a/kernel/src/memory.rs b/kernel/src/memory.rs
index a2dc902..cd4d17c 100644
--- a/kernel/src/memory.rs
+++ b/kernel/src/memory.rs
@@ -28,6 +28,8 @@ pub fn dealloc_frame(target: usize) {
 pub fn alloc_stack() -> Stack {
     use alloc::boxed::Box;
     const STACK_SIZE: usize = 0x8000;
+    // FIXME: This alignment will cause rsp align with 0x8000 in x86_64 release mode.
+    //        Because kernel stack is not large enough, it will trigger double fault.
     #[repr(align(0x8000))]
     struct StackData([u8; STACK_SIZE]);
     let data = Box::new(StackData([0; STACK_SIZE]));