From 1f612e45f7fccb4caa3901ee26605f828ec64a06 Mon Sep 17 00:00:00 2001
From: Zhang Junyang <junyang@stu.pku.edu.cn>
Date: Sat, 9 Nov 2024 19:22:41 +0800
Subject: [PATCH] Remove unnecessary page table items

---
 ostd/src/mm/kspace/kvirt_area.rs |  3 ---
 ostd/src/mm/page_table/cursor.rs |  3 ---
 ostd/src/mm/vm_space.rs          | 12 ------------
 3 files changed, 18 deletions(-)

diff --git a/ostd/src/mm/kspace/kvirt_area.rs b/ostd/src/mm/kspace/kvirt_area.rs
index 3d1562059..3ad794973 100644
--- a/ostd/src/mm/kspace/kvirt_area.rs
+++ b/ostd/src/mm/kspace/kvirt_area.rs
@@ -349,9 +349,6 @@ impl<M: AllocatorSelector + 'static> Drop for KVirtArea<M> {
                 PageTableItem::NotMapped { .. } => {
                     break;
                 }
-                PageTableItem::PageTableNode { .. } => {
-                    panic!("Found page table node in `KVirtArea`");
-                }
             }
         }
 
diff --git a/ostd/src/mm/page_table/cursor.rs b/ostd/src/mm/page_table/cursor.rs
index 561dc00e5..b6dcedccd 100644
--- a/ostd/src/mm/page_table/cursor.rs
+++ b/ostd/src/mm/page_table/cursor.rs
@@ -94,9 +94,6 @@ pub enum PageTableItem {
         page: DynPage,
         prop: PageProperty,
     },
-    PageTableNode {
-        page: DynPage,
-    },
     #[allow(dead_code)]
     MappedUntracked {
         va: Vaddr,
diff --git a/ostd/src/mm/vm_space.rs b/ostd/src/mm/vm_space.rs
index b817501e1..60de8a73a 100644
--- a/ostd/src/mm/vm_space.rs
+++ b/ostd/src/mm/vm_space.rs
@@ -369,15 +369,6 @@ impl CursorMut<'_, '_> {
                     self.flusher
                         .issue_tlb_flush_with(TlbFlushOp::Address(va), page);
                 }
-                PageTableItem::PageTableNode { page } => {
-                    if !self.flusher.need_remote_flush() && tlb_prefer_flush_all {
-                        // Only on single-CPU cases we can drop the page immediately before flushing.
-                        drop(page);
-                        continue;
-                    }
-                    // If we unmap an entire page table node, we prefer directly flushing all TLBs.
-                    self.flusher.issue_tlb_flush_with(TlbFlushOp::All, page);
-                }
                 PageTableItem::NotMapped { .. } => {
                     break;
                 }
@@ -506,9 +497,6 @@ impl TryFrom<PageTableItem> for VmItem {
             PageTableItem::MappedUntracked { .. } => {
                 Err("found untracked memory mapped into `VmSpace`")
             }
-            PageTableItem::PageTableNode { .. } => {
-                unreachable!()
-            }
         }
     }
 }