diff --git a/security/landlock/tsync.c b/security/landlock/tsync.c
index 1e738ef2cff5..f0e5f8102001 100644
--- a/security/landlock/tsync.c
+++ b/security/landlock/tsync.c
@@ -485,6 +485,16 @@ int landlock_restrict_sibling_threads(const struct cred *old_cred,
 	shared_ctx.new_cred = new_cred;
 	shared_ctx.set_no_new_privs = task_no_new_privs(current);
 
+	/*
+	 * Serialize concurrent TSYNC operations to prevent deadlocks when
+	 * multiple threads call landlock_restrict_self() simultaneously.
+	 * If the lock is already held, we gracefully yield by restarting the
+	 * syscall. This allows the current thread to process pending
+	 * task_works before retrying.
+	 */
+	if (!down_write_trylock(&current->signal->exec_update_lock))
+		return restart_syscall();
+
 	/*
 	 * We schedule a pseudo-signal task_work for each of the calling task's
 	 * sibling threads.  In the task work, each thread:
@@ -594,6 +604,6 @@ int landlock_restrict_sibling_threads(const struct cred *old_cred,
 		wait_for_completion(&shared_ctx.all_finished);
 
 	tsync_works_release(&works);
-
+	up_write(&current->signal->exec_update_lock);
 	return atomic_read(&shared_ctx.preparation_error);
 }