diff --git a/executer/user/mcexec.c b/executer/user/mcexec.c
index 6b0553d5..38b7d4ad 100644
--- a/executer/user/mcexec.c
+++ b/executer/user/mcexec.c
@@ -1956,6 +1956,10 @@ int main(int argc, char **argv)
 		n_threads = ncpu;
 	}
 
+	/* Quick fix for #900: Limit the number of clone() */
+	desc->rlimit[MCK_RLIMIT_NPROC].rlim_cur = n_threads;
+	desc->rlimit[MCK_RLIMIT_NPROC].rlim_max = n_threads;
+
 	/* 
 	 * XXX: keep thread_data ncpu sized despite that there are only
 	 * n_threads worker threads in the pool so that signaling code
diff --git a/kernel/include/rusage.h b/kernel/include/rusage.h
index e31ad1f6..c7e984fc 100644
--- a/kernel/include/rusage.h
+++ b/kernel/include/rusage.h
@@ -147,6 +147,12 @@ rusage_num_threads_dec()
 {
 	__sync_sub_and_fetch(&monitor->rusage_num_threads, 1);
 }
+
+static inline unsigned long
+rusage_num_threads_get()
+{
+	return monitor->rusage_num_threads;
+}
 #else
 static inline void
 rusage_total_memory_add(unsigned long size)
@@ -192,6 +198,12 @@ static inline void
 rusage_num_threads_dec()
 {
 }
+
+static inline unsigned long
+rusage_num_threads_get()
+{
+	return -1;
+}
 #endif // ENABLE_RUSAGE
 
 #endif
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 7526bb48..9a0acaa9 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -2124,6 +2124,7 @@ unsigned long do_fork(int clone_flags, unsigned long newsp,
 {
 	int cpuid;
 	int parent_cpuid;
+	int nr_threads;
 	struct thread *old = cpu_local_var(current);
 	struct process *oldproc = old->proc;
 	struct process *newproc;
@@ -2170,6 +2171,17 @@ unsigned long do_fork(int clone_flags, unsigned long newsp,
 		return -EINVAL;
 	}
 
+	/* FIXME: It is not appropriate to enforce rlimit only when rusage is enabled */
+	nr_threads = rusage_num_threads_get();
+	if(nr_threads != -1) {
+		struct rlimit *rlim;
+		rlim = &oldproc->rlimit[MCK_RLIMIT_NPROC];
+		if (nr_threads >= rlim->rlim_cur) {
+			ekprintf("%s,resource limit exceeded,RLIMIT_NPROC=%d,nr_threads=%d\n", __FUNCTION__, rlim->rlim_cur, nr_threads);
+			return -EAGAIN;
+		}
+	}
+
 	cpuid = obtain_clone_cpuid(&old->cpu_set);
     if (cpuid == -1) {
 		kprintf("do_fork,core not available\n");