diff --git a/userspace/ksud/src/event.rs b/userspace/ksud/src/event.rs
index 13a0423f..f5081348 100644
--- a/userspace/ksud/src/event.rs
+++ b/userspace/ksud/src/event.rs
@@ -185,9 +185,8 @@ pub fn on_post_data_fs() -> Result<()> {
     }
 
     // Finally, we should do systemless mount
-    // But we should umount all stock overlayfs and remount them after module mounted
+    // But we should backup all stock overlayfs and remount them after module mounted
     let stock_overlay = mount::StockOverlay::new();
-    stock_overlay.umount_all();
 
     // mount moduke systemlessly by overlay
     if let Err(e) = mount_systemlessly(module_dir) {
diff --git a/userspace/ksud/src/mount.rs b/userspace/ksud/src/mount.rs
index b8cbac38..40efeab6 100644
--- a/userspace/ksud/src/mount.rs
+++ b/userspace/ksud/src/mount.rs
@@ -168,9 +168,6 @@ impl StockOverlay {
         unimplemented!()
     }
 
-    pub fn umount_all(&self) {
-        unimplemented!()
-    }
 }
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
@@ -238,19 +235,6 @@ impl StockOverlay {
             }
         }
     }
-
-    pub fn umount_all(&self) {
-        log::info!("stock overlay: umount all: {:?}", self.mountinfos);
-        for mnt in &self.mountinfos {
-            let Some(p) = mnt.mount_point.to_str() else {
-                log::warn!("Failed to umount: {}", mnt.mount_point.display());
-                continue;
-            };
-
-            let result = umount_dir(p);
-            log::info!("stock umount {}: {:?}", p, result);
-        }
-    }
 }
 
 // some ROMs mount device(ext4,exfat) to /vendor, when we do overlay mount, it will overlay