diff --git a/lab4/kernel/exception/pgfault.c b/lab4/kernel/exception/pgfault.c
index 483120a..32a1dba 100644
--- a/lab4/kernel/exception/pgfault.c
+++ b/lab4/kernel/exception/pgfault.c
@@ -68,7 +68,6 @@ int handle_trans_fault(struct vmspace *vmspace, vaddr_t fault_addr)
 	struct vmregion *vmr;
 	struct pmobject *pmo;
 	paddr_t pa;
-	u64 offset;
 	int ret;
 
 	/*
diff --git a/lab4/kernel/mm/buddy.c b/lab4/kernel/mm/buddy.c
index c8cac33..32d4096 100644
--- a/lab4/kernel/mm/buddy.c
+++ b/lab4/kernel/mm/buddy.c
@@ -180,9 +180,7 @@ static struct page *merge_page(struct phys_mem_pool *pool, struct page *page) {
     list_del(&buddy->node);
     pool->free_lists[page->order].nr_free -= 2;
     // 选择左侧 page
-    struct page *t;
     if (buddy < page) {
-        t = page;
         page = buddy;
     }
     // 增加 page 的 order
diff --git a/lab4/kernel/mm/vm_syscall.c b/lab4/kernel/mm/vm_syscall.c
index 44c93a2..bef7854 100644
--- a/lab4/kernel/mm/vm_syscall.c
+++ b/lab4/kernel/mm/vm_syscall.c
@@ -318,10 +318,7 @@ u64 sys_handle_brk(u64 addr)
 {
 	struct vmspace *vmspace;
 	struct pmobject *pmo;
-	struct vmregion *vmr;
-	size_t len;
 	u64 retval;
-	int ret;
 
 	vmspace = obj_get(current_process, VMSPACE_OBJ_ID, TYPE_VMSPACE);
 
diff --git a/lab4/kernel/monitor.c b/lab4/kernel/monitor.c
index 0f951b9..cde96e4 100644
--- a/lab4/kernel/monitor.c
+++ b/lab4/kernel/monitor.c
@@ -34,10 +34,10 @@ int stack_backtrace()
 
 	// Your code here.
 	u64 *fp, *preFp;
-	fp = read_fp();
+	fp = (u64 *) read_fp();
 	// until stack end
 	while (true) {
-		preFp = *fp;
+		preFp = (u64 *) *fp;
 		// entry frame
 		if (preFp == 0)
 			break;
diff --git a/lab4/kernel/process/thread.c b/lab4/kernel/process/thread.c
index 95ee160..fd5de7b 100644
--- a/lab4/kernel/process/thread.c
+++ b/lab4/kernel/process/thread.c
@@ -395,7 +395,7 @@ int sys_create_thread(u64 process_cap, u64 stack, u64 pc, u64 arg, u32 prio,
 int sys_set_affinity(u64 thread_cap, s32 aff)
 {
 	struct thread *thread = NULL;
-	int cpuid = smp_get_cpu_id(), ret = 0;
+	int cpuid = smp_get_cpu_id();
 
 	/* currently, we use -1 to represent the current thread */
 	if (thread_cap == -1) {
@@ -424,7 +424,6 @@ int sys_get_affinity(u64 thread_cap)
 {
 	struct thread *thread = NULL;
 	int cpuid = smp_get_cpu_id();
-	s32 aff = 0;
 
 	/* currently, we use -1 to represent the current thread */
 	if (thread_cap == -1) {