Merge unmap and unmap_and_free by using free on exit flag in mappings

src/interrupts.rs

@@ -339,7 +339,7 @@ extern "C" fn syscall_handler() {
                             (ptr::with_exposed_provenance_mut::<u8>(usize(regs.rsi)))
                                 .copy_from(page.start_address().as_mut_ptr::<u8>(), len);
                         });
-                        space.unmap_and_free(page, buffer_num_pages).unwrap();
+                        space.unmap(page, buffer_num_pages).unwrap();
                         retval = 0;
                     } else {
                         retval = 1;
@@ -648,7 +648,7 @@ extern "C" fn syscall_handler() {
                 break 'call22;
             };
             retval = if regs.rcx == 0 {
-                u64::from(ACTIVE_SPACE.lock().unmap_and_free(page, usize(regs.rsi)).is_err())
+                u64::from(ACTIVE_SPACE.lock().unmap(page, usize(regs.rsi)).is_err())
             } else {
                 TASKING.address_spaces_mut(|x| {
                     #[warn(
@@ -656,7 +656,7 @@ extern "C" fn syscall_handler() {
                         reason = "FIXME: The current address space should be usize::MAX as that is an invalid index, instead of 0."
                     )]
                     if let Some(space) = x.get_mut(usize(regs.rcx - 1)) {
-                        u64::from(space.unmap_and_free(page, usize(regs.rsi)).is_err())
+                        u64::from(space.unmap(page, usize(regs.rsi)).is_err())
                     } else {
                         1
                     }

src/virtual_memory.rs

@@ -643,18 +643,6 @@ impl AddressSpace {
     }
 
     pub fn unmap(&mut self, page: Page, num_pages: usize) -> Result<(), PagingError> {
-        self.check_request_valid(page, num_pages)?;
-        #[expect(
-            clippy::arithmetic_side_effects,
-            reason = "check_request_valid guarentees this won't overflow"
-        )]
-        for page in (PageRange { start: page, end: page + u64(num_pages) }) {
-            self.mapper.unmap(page)?.1.flush();
-        }
-        Ok(())
-    }
-
-    pub fn unmap_and_free(&mut self, page: Page, num_pages: usize) -> Result<(), PagingError> {
         self.check_request_valid(page, num_pages)?;
         #[expect(
             clippy::arithmetic_side_effects,
@@ -662,12 +650,19 @@ impl AddressSpace {
         )]
         for page in (PageRange { start: page, end: page + u64(num_pages) }) {
             unsafe {
+                let TranslateResult::Mapped { frame: _, offset: 0, flags } =
+                    self.mapper.translate(page.start_address())
+                else {
+                    continue;
+                };
                 let (frame, flush) = self.mapper.unmap(page)?;
-                PHYSICAL_MEMORY.lock().deallocate_frame(frame);
+                if flags.contains(PageTableFlags::BIT_9) {
+                    PHYSICAL_MEMORY.lock().deallocate_frame(frame);
+                    self.record_dealloc(4096);
+                }
                 flush.flush();
             }
         }
-        self.record_dealloc(num_pages * 4096);
         Ok(())
     }
 
@@ -689,10 +684,10 @@ impl AddressSpace {
             let TranslateResult::Mapped { frame: MappedFrame::Size4KiB(frame), offset: 0, flags } =
                 self.mapper.translate(src_page.start_address())
             else {
-                continue;
+                return Err(PagingError::PageNotMapped);
             };
             unsafe { dest.map_to(dest_page, frame, 1, flags)? };
-            self.unmap(src_page, 1)?;
+            self.mapper.unmap(src_page)?.1.flush();
             if flags.contains(PageTableFlags::BIT_9) {
                 self.record_dealloc(4096);
                 dest.record_alloc(4096);
@@ -856,6 +851,6 @@ unsafe impl Allocator for ASpaceMutex {
             The kernel doesn't use huge pages and the mapping must be valid to be returned from allocate, so unmap cannot fail.
         "
         )]
-        self.0.lock().unmap_and_free(start_page, length).unwrap();
+        self.0.lock().unmap(start_page, length).unwrap();
     }
 }