init, sched: Fix race between init and kthreadd

[firefly-linux-kernel-4.4.55.git] / init / main.c

diff --git a/init/main.c b/init/main.c
index 5988debfc505c84c8c5f7abeb0b5fb1e2d88f1fc..1eb4bd5f09ac3366fade12fcfc4db209f770fccb 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -251,7 +251,7 @@ early_param("loglevel", loglevel);
 
 /*
  * Unknown boot options get handed to init, unless they look like
- * failed parameters
+ * unused parameters (modprobe will find them in /proc/cmdline).
  */
 static int __init unknown_bootoption(char *param, char *val)
 {
@@ -272,14 +272,9 @@ static int __init unknown_bootoption(char *param, char *val)
        if (obsolete_checksetup(param))
                return 0;
 
-       /*
-        * Preemptive maintenance for "why didn't my misspelled command
-        * line work?"
-        */
-       if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
-               printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
+       /* Unused module parameter. */
+       if (strchr(param, '.') && (!val || strchr(param, '.') < val))
                return 0;
-       }
 
        if (panic_later)
                return 0;
@@ -374,12 +369,6 @@ static void __init smp_init(void)
 {
        unsigned int cpu;
 
-       /*
-        * Set up the current CPU as possible to migrate to.
-        * The other ones will be done by cpu_up/cpu_down()
-        */
-       set_cpu_active(smp_processor_id(), true);
-
        /* FIXME: This should be done in userspace --RR */
        for_each_present_cpu(cpu) {
                if (num_online_cpus() >= setup_max_cpus)
@@ -418,16 +407,24 @@ static void __init setup_command_line(char *command_line)
  * gcc-3.4 accidentally inlines this function, so use noinline.
  */
 
+static __initdata DECLARE_COMPLETION(kthreadd_done);
+
 static noinline void __init_refok rest_init(void)
        __releases(kernel_lock)
 {
        int pid;
 
        rcu_scheduler_starting();
+       /*
+        * We need to spawn init first so that it obtains pid-1, however
+        * the init task will end up wanting to create kthreads, which, if
+        * we schedule it before we create kthreadd, will OOPS.
+        */
        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
        numa_default_policy();
        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
+       complete(&kthreadd_done);
        unlock_kernel();
 
        /*
@@ -491,6 +488,7 @@ static void __init boot_cpu_init(void)
        int cpu = smp_processor_id();
        /* Mark the boot cpu "present", "online" etc for SMP and UP case */
        set_cpu_online(cpu, true);
+       set_cpu_active(cpu, true);
        set_cpu_present(cpu, true);
        set_cpu_possible(cpu, true);
 }
@@ -851,12 +849,16 @@ static noinline int init_post(void)
 
 static int __init kernel_init(void * unused)
 {
+       /*
+        * Wait until kthreadd is all set-up.
+        */
+       wait_for_completion(&kthreadd_done);
        lock_kernel();
 
        /*
         * init can allocate pages on any node
         */
-       set_mems_allowed(node_possible_map);
+       set_mems_allowed(node_states[N_HIGH_MEMORY]);
        /*
         * init can run on any cpu.
         */