sched/isolation: Prevent boot crash when the boot CPU is nohz_full

[linux-block.git] / kernel / sched / isolation.c

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 373d42c707bc5d65d70c18d66e0ffd1621d33f5b..2a262d3ecb3da4964f42cecccc5f44479d5ea5f1 100644 (file)
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -46,7 +46,16 @@ int housekeeping_any_cpu(enum hk_type type)
                        if (cpu < nr_cpu_ids)
                                return cpu;
 
-                       return cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask);
+                       cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask);
+                       if (likely(cpu < nr_cpu_ids))
+                               return cpu;
+                       /*
+                        * Unless we have another problem this can only happen
+                        * at boot time before start_secondary() brings the 1st
+                        * housekeeping CPU up.
+                        */
+                       WARN_ON_ONCE(system_state == SYSTEM_RUNNING ||
+                                    type != HK_TYPE_TIMER);
                }
        }
        return smp_processor_id();