diff --git a/labcodes_answer/lab6_result/kern/process/proc.c b/labcodes_answer/lab6_result/kern/process/proc.c
index 994e77c..4eb1531 100644
--- a/labcodes_answer/lab6_result/kern/process/proc.c
+++ b/labcodes_answer/lab6_result/kern/process/proc.c
@@ -845,6 +845,9 @@ init_main(void *arg) {
     int i = 0;
     for (; i < 10; i++) {
         int pid = kernel_thread(my_test_user_main, (void *)i, 0);
+        if (pid <= 0) {
+            panic("create my_test_user_main failed.\n");
+        }
         struct proc_strucht *proc = find_proc(pid);
     }
 
diff --git a/labcodes_answer/lab7_result/kern/process/proc.c b/labcodes_answer/lab7_result/kern/process/proc.c
index a726dda..4122c03 100644
--- a/labcodes_answer/lab7_result/kern/process/proc.c
+++ b/labcodes_answer/lab7_result/kern/process/proc.c
@@ -844,8 +844,8 @@ init_main(void *arg) {
     if (pid <= 0) {
         panic("create user_main failed.\n");
     }
- extern void check_sync(void);
-    check_sync();                // check philosopher sync problem
+ extern void read_write_sync(void);
+    read_write_sync();                // check philosopher sync problem
 
     while (do_wait(0, NULL) == 0) {
         schedule();
diff --git a/labcodes_answer/lab7_result/kern/sync/read_write_sync.c b/labcodes_answer/lab7_result/kern/sync/read_write_sync.c
new file mode 100644
index 0000000..59cb60d
--- /dev/null
+++ b/labcodes_answer/lab7_result/kern/sync/read_write_sync.c
@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <proc.h>
+#include <sem.h>
+#include <monitor.h>
+#include <assert.h>
+
+#define READER_NUM 100 // 读者数量，取值应大于1，小于int范围
+#define WRITER_NUM 100 // 写者数量，取值应大于1，小于int范围
+// #define BUFFER_NUM 10 // 缓冲区数量，取值应大于1，小于int范围
+#define SLEEP_TIME 10
+
+// down和up、P和V 都实在是用不习惯，还是用acquire和release吧。
+#define acquire down
+#define release up
+
+semaphore_t mutex; /* 临界区互斥 */
+semaphore_t synchronization; // 同步
+int read_pos_write_neg = 0; // 表示正在读取的读者数量
+int buffer;
+
+int reader(int index){
+    lab6_set_priority(rand() % 100);
+    int result;
+    acquire(&mutex);
+    read_pos_write_neg++;
+    if (read_pos_write_neg == 1)
+        acquire(&synchronization);
+    release(&mutex);
+    do_sleep(rand() % SLEEP_TIME); // 模拟读延迟
+    result = buffer;
+    acquire(&mutex);
+    read_pos_write_neg--;
+    assert(read_pos_write_neg >=0);
+    if (read_pos_write_neg == 0) {
+        release(&synchronization);
+    }
+    release(&mutex);
+    cprintf("reader %2d read   %2d\n", index, result);
+    return result;
+}
+
+void writer(int index) {
+    lab6_set_priority(rand() % 100);
+    int write_data = rand() % 100;
+    acquire(&synchronization);
+    do_sleep(rand() % SLEEP_TIME); // 模拟写延迟
+    buffer = write_data;
+    release(&synchronization);
+    cprintf("writer %2d writed %2d\n", index, write_data);
+}
+
+void read_write_sync() {
+    sem_init(&mutex, 1);
+    sem_init(&synchronization, 1);
+    int reader_num = 0, writer_num = 0;
+    while (reader_num < READER_NUM || writer_num < WRITER_NUM) {
+        if (rand() % 2) {
+            if (reader_num < READER_NUM) {
+                int pid = kernel_thread(reader, (void *)reader_num, 0);
+                if (pid <= 0) {
+                    panic("create No.%d reader failed.\n");
+                }
+                reader_num++;
+            }
+        } else {
+            if (writer_num < WRITER_NUM) {
+                int pid = kernel_thread(writer, (void *)writer_num, 0);
+                if (pid <= 0) {
+                    panic("create No.%d writer failed.\n");
+                }
+                writer_num++;
+            }
+        }
+        do_sleep(rand() % SLEEP_TIME); // 模拟入队延迟
+    }
+}
\ No newline at end of file