Some more clippy fixes, warnings are noisy

kernel/src/arch/x86_64/cpu/apic.rs

@@ -1,3 +1,5 @@
+#![expect(unused)]
+
 use core::arch::x86_64::__cpuid;
 
 use crate::arch::x86_64::memory::mapping::PHYSICAL_MEMORY_OFFSET;

kernel/src/arch/x86_64/cpu/msr.rs

@@ -1,3 +1,4 @@
+#![expect(unused)]
 use core::arch::x86_64::__cpuid;
 use spin::Lazy;
 use x86_64::registers::model_specific::Msr;

kernel/src/arch/x86_64/cpu/pic.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::missing_safety_doc)]
+
 use x86_64::instructions::port::Port;
 
 const CMD_INIT: u8 = 0x11;

kernel/src/arch/x86_64/memory/allocation/heap_alloc.rs

@@ -173,15 +173,22 @@ impl FoundryFallbackAllocator {
         }
     }
 
+    /// Initialises the Foundry OS fallback allocator. This is currently a
+    /// linked list allocator pulled from the linked_list_allocator crate.
+    ///
+    /// # Safety
+    ///
+    /// This function assumes you passed a valid `heap_start` and `heap_size`,
+    /// as these are unchecked.
     pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
         unsafe { self.add_region(heap_start, heap_size) };
     }
 
     unsafe fn add_region(&mut self, addr: usize, size: usize) {
+        let mut node = FallbackListNode::new(size);
+        node.next = self.head.next.take();
+        let node_ptr = addr as *mut FallbackListNode;
         unsafe {
-            let mut node = FallbackListNode::new(size);
-            node.next = self.head.next.take();
-            let node_ptr = addr as *mut FallbackListNode;
             node_ptr.write(node);
             self.head.next = Some(&mut *node_ptr);
         }