sched/core: Allow kthreads to fall back to online && !active cpus

[cascardo/linux.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f2cae4..51d7105 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1536,7 +1536,9 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
        for (;;) {
                /* Any allowed, online CPU? */
                for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
-                       if (!cpu_active(dest_cpu))
+                       if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu))
+                               continue;
+                       if (!cpu_online(dest_cpu))
                                continue;
                        goto out;
                }
@@ -2253,9 +2255,11 @@ int sysctl_numa_balancing(struct ctl_table *table, int write,
 #endif
 #endif
 
+#ifdef CONFIG_SCHEDSTATS
+
 DEFINE_STATIC_KEY_FALSE(sched_schedstats);
+static bool __initdata __sched_schedstats = false;
 
-#ifdef CONFIG_SCHEDSTATS
 static void set_schedstats(bool enabled)
 {
        if (enabled)
@@ -2278,11 +2282,16 @@ static int __init setup_schedstats(char *str)
        if (!str)
                goto out;
 
+       /*
+        * This code is called before jump labels have been set up, so we can't
+        * change the static branch directly just yet.  Instead set a temporary
+        * variable so init_schedstats() can do it later.
+        */
        if (!strcmp(str, "enable")) {
-               set_schedstats(true);
+               __sched_schedstats = true;
                ret = 1;
        } else if (!strcmp(str, "disable")) {
-               set_schedstats(false);
+               __sched_schedstats = false;
                ret = 1;
        }
 out:
@@ -2293,6 +2302,11 @@ out:
 }
 __setup("schedstats=", setup_schedstats);
 
+static void __init init_schedstats(void)
+{
+       set_schedstats(__sched_schedstats);
+}
+
 #ifdef CONFIG_PROC_SYSCTL
 int sysctl_schedstats(struct ctl_table *table, int write,
                         void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -2313,8 +2327,10 @@ int sysctl_schedstats(struct ctl_table *table, int write,
                set_schedstats(state);
        return err;
 }
-#endif
-#endif
+#endif /* CONFIG_PROC_SYSCTL */
+#else  /* !CONFIG_SCHEDSTATS */
+static inline void init_schedstats(void) {}
+#endif /* CONFIG_SCHEDSTATS */
 
 /*
  * fork()/clone()-time setup:
@@ -2521,10 +2537,9 @@ void wake_up_new_task(struct task_struct *p)
         */
        set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
 #endif
-       /* Post initialize new task's util average when its cfs_rq is set */
+       rq = __task_rq_lock(p, &rf);
        post_init_entity_util_avg(&p->se);
 
-       rq = __task_rq_lock(p, &rf);
        activate_task(rq, p, 0);
        p->on_rq = TASK_ON_RQ_QUEUED;
        trace_sched_wakeup_new(p);
@@ -3156,7 +3171,8 @@ static noinline void __schedule_bug(struct task_struct *prev)
 static inline void schedule_debug(struct task_struct *prev)
 {
 #ifdef CONFIG_SCHED_STACK_END_CHECK
-       BUG_ON(task_stack_end_corrupted(prev));
+       if (task_stack_end_corrupted(prev))
+               panic("corrupted stack end detected inside scheduler\n");
 #endif
 
        if (unlikely(in_atomic_preempt_off())) {
@@ -5133,14 +5149,16 @@ void show_state_filter(unsigned long state_filter)
                /*
                 * reset the NMI-timeout, listing all files on a slow
                 * console might take a lot of time:
+                * Also, reset softlockup watchdogs on all CPUs, because
+                * another CPU might be blocked waiting for us to process
+                * an IPI.
                 */
                touch_nmi_watchdog();
+               touch_all_softlockup_watchdogs();
                if (!state_filter || (p->state & state_filter))
                        sched_show_task(p);
        }
 
-       touch_all_softlockup_watchdogs();
-
 #ifdef CONFIG_SCHED_DEBUG
        if (!state_filter)
                sysrq_sched_debug_show();
@@ -7487,6 +7505,8 @@ void __init sched_init(void)
 #endif
        init_sched_fair_class();
 
+       init_schedstats();
+
        scheduler_running = 1;
 }