Use pointer metadata for page metadata

ostd/src/task/kernel_stack.rs

@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use crate::{
+    impl_page_meta,
     mm::{
         kspace::kvirt_area::{KVirtArea, Tracked},
-        page::{allocator, meta::KernelStackMeta},
+        page::allocator,
         page_prop::{CachePolicy, PageFlags, PageProperty, PrivilegedPageFlags},
         PAGE_SIZE,
     },
@@ -34,6 +35,11 @@ pub struct KernelStack {
     has_guard_page: bool,
 }
 
+#[derive(Debug, Default)]
+struct KernelStackMeta {}
+
+impl_page_meta!(KernelStackMeta);
+
 impl KernelStack {
     /// Generates a kernel stack with guard pages.
     /// 4 additional pages are allocated and regarded as guard pages, which should not be accessed.