From: Amit K. Arora Date: Tue, 25 May 2010 13:23:46 +0000 (+0530) Subject: sched: Make sure timers have migrated before killing the migration_thread X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=54e88fad223c4e1d94289611a90c7fe3ebe5631b;p=linux-beck.git sched: Make sure timers have migrated before killing the migration_thread Problem: In a stress test where some heavy tests were running along with regular CPU offlining and onlining, a hang was observed. The system seems to be hung at a point where migration_call() tries to kill the migration_thread of the dying CPU, which just got moved to the current CPU. This migration thread does not get a chance to run (and die) since rt_throttled is set to 1 on current, and it doesn't get cleared as the hrtimer which is supposed to reset the rt bandwidth (sched_rt_period_timer) is tied to the CPU which we just marked dead! Solution: This patch pushes the killing of migration thread to "CPU_POST_DEAD" event. By then all the timers (including sched_rt_period_timer) should have got migrated (along with other callbacks). Signed-off-by: Amit Arora Signed-off-by: Gautham R Shenoy Acked-by: Tejun Heo Signed-off-by: Peter Zijlstra Cc: Thomas Gleixner LKML-Reference: <20100525132346.GA14986@amitarora.in.ibm.com> Signed-off-by: Ingo Molnar --- diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index b4e7431e7c78..70f8d90331e9 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -321,7 +321,7 @@ static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb, #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: - case CPU_DEAD: + case CPU_POST_DEAD: { struct cpu_stop_work *work;