feat: implement synchronisation to protecting access to PTEs of SPTs during eviction

src/vm/frame.c

@@ -9,7 +9,6 @@
 #include "threads/vaddr.h"
 #include "userprog/pagedir.h"
 #include "threads/synch.h"
-#include "devices/swap.h"
 
 /* Hash table that maps every active frame's kernel virtual address
    to its corresponding 'frame_metadata'.*/
@@ -76,7 +75,7 @@ frame_alloc (enum palloc_flags flags, void *upage, struct thread *owner)
 {
   struct frame_metadata *frame_metadata;
   flags |= PAL_USER;
-  
+
   lock_acquire (&lru_lock);
   void *frame = palloc_get_page (flags);
 
@@ -93,15 +92,7 @@ frame_alloc (enum palloc_flags flags, void *upage, struct thread *owner)
       ASSERT (victim != NULL); /* get_victim () should never return null. */
 
       /* 2. Swap out victim into disk. */
-      /* Mark page as 'not present' and flag the page directory as having
-         been modified *before* eviction begins to prevent the owner of the
-         victim page from accessing/modifying it mid-eviction. */
-      pagedir_clear_page (victim->owner->pagedir, victim->upage);
-
-      // TODO: Lock PTE of victim page for victim process.
-
-      size_t swap_slot = swap_out (victim->frame);
-      page_set_swap (victim->owner, victim->upage, swap_slot);
+      page_insert_swapped (victim->upage, victim->frame, victim->owner);
 
       /* If zero flag is set, zero out the victim page. */
       if (flags & PAL_ZERO)