kernel: try introduce like susfs's method to fix prctl delay

Co-authored-by: AlexLiuDev233 <wzylin11@outlook.com>

kernel/core_hook.h

@@ -3,8 +3,19 @@
 
 #include <linux/init.h>
 #include "apk_sign.h"
+#include <linux/thread_info.h>
 
 void __init ksu_core_init(void);
 void ksu_core_exit(void);
 
+#define KSU_PROC_UMOUNT 50
+
+static inline bool ksu_is_current_proc_umounted(void) {
+	return test_ti_thread_flag(&current->thread_info, KSU_PROC_UMOUNT);
+}
+
+static inline void ksu_set_current_proc_umounted(void) {
+	set_ti_thread_flag(&current->thread_info, KSU_PROC_UMOUNT);
+}
+
 #endif