core/storage: Mark Page as Send and Sync

core/storage/pager.rs

@@ -168,6 +168,11 @@ pub struct Page {
     pub inner: UnsafeCell<PageInner>,
 }
 
+// SAFETY: Page is thread-safe because we use atomic page flags to serialize
+// concurrent modifications.
+unsafe impl Send for Page {}
+unsafe impl Sync for Page {}
+
 // Concurrency control of pages will be handled by the pager, we won't wrap Page with RwLock
 // because that is bad bad.
 pub type PageRef = Arc<Page>;