Remove the level in RawPageTableNode

ostd/src/mm/page_table/cursor.rs

@@ -271,12 +271,16 @@ where
     fn level_down(&mut self) {
         debug_assert!(self.level > 1);
 
-        if let Child::PageTable(nxt_lvl_ptn) = self.cur_child() {
+        let Child::PageTable(nxt_lvl_ptn) = self.cur_child() else {
-            self.level -= 1;
-            self.guards[(self.level - 1) as usize] = Some(nxt_lvl_ptn.lock());
-        } else {
             panic!("Trying to level down when it is not mapped to a page table");
-        }
+        };
+
+        let nxt_lvl_ptn_locked = nxt_lvl_ptn.lock();
+
+        self.level -= 1;
+        debug_assert_eq!(self.level, nxt_lvl_ptn_locked.level());
+
+        self.guards[(self.level - 1) as usize] = Some(nxt_lvl_ptn_locked);
     }
 
     fn cur_node(&self) -> &PageTableNode<E, C> {

ostd/src/mm/page_table/node.rs

@@ -56,7 +56,6 @@ where
     [(); C::NR_LEVELS as usize]:,
 {
     pub(super) raw: Paddr,
-    pub(super) level: PagingLevel,
     _phantom: PhantomData<(E, C)>,
 }
 
@@ -74,7 +73,6 @@ where
         // transferring the ownership to a new handle. No increment of the reference
         // count is needed.
         let page = unsafe { Page::<PageTablePageMeta<E, C>>::from_raw(self.paddr()) };
-        debug_assert!(page.meta().level == self.level);
 
         // Acquire the lock.
         while page
@@ -98,7 +96,6 @@ where
 
         Self {
             raw: self.raw,
-            level: self.level,
             _phantom: PhantomData,
         }
     }
@@ -121,8 +118,6 @@ where
             mm::CachePolicy,
         };
 
-        debug_assert_eq!(self.level, PagingConsts::NR_LEVELS);
-
         let last_activated_paddr = current_page_table_paddr();
 
         activate_page_table(self.raw, CachePolicy::Writeback);
@@ -137,7 +132,6 @@ where
         // Restore and drop the last activated page table.
         drop(Self {
             raw: last_activated_paddr,
-            level: PagingConsts::NR_LEVELS,
             _phantom: PhantomData,
         });
     }
@@ -149,8 +143,6 @@ where
     pub(super) unsafe fn first_activate(&self) {
         use crate::{arch::mm::activate_page_table, mm::CachePolicy};
 
-        debug_assert_eq!(self.level, PagingConsts::NR_LEVELS);
-
         self.inc_ref();
 
         activate_page_table(self.raw, CachePolicy::Writeback);
@@ -240,7 +232,6 @@ where
 
     /// Converts the handle into a raw handle to be stored in a PTE or CPU.
     pub(super) fn into_raw(self) -> RawPageTableNode<E, C> {
-        let level = self.level();
         let raw = self.page.paddr();
 
         self.page.meta().lock.store(0, Ordering::Release);
@@ -248,7 +239,6 @@ where
 
         RawPageTableNode {
             raw,
-            level,
             _phantom: PhantomData,
         }
     }
@@ -259,7 +249,6 @@ where
 
         RawPageTableNode {
             raw: self.page.paddr(),
-            level: self.level(),
             _phantom: PhantomData,
         }
     }
@@ -283,7 +272,6 @@ where
                 core::mem::forget(inc_ref);
                 Child::PageTable(RawPageTableNode {
                     raw: paddr,
-                    level: self.level() - 1,
                     _phantom: PhantomData,
                 })
             } else if in_tracked_range {
@@ -368,7 +356,6 @@ where
     ) {
         // They should be ensured by the cursor.
         debug_assert!(idx < nr_subpage_per_huge::<C>());
-        debug_assert_eq!(pt.level, self.level() - 1);
 
         let pte = Some(E::new_pt(pt.paddr()));
         self.overwrite_pte(idx, pte, in_tracked_range);