From 1c6b4aa94576eee6dec3b8011f60d7f666db90b0 Mon Sep 17 00:00:00 2001 From: Satoru Takeuchi Date: Sun, 15 Jul 2007 23:39:48 -0700 Subject: [PATCH] cpu hotplug: fix ksoftirqd termination on cpu hotplug with naughty realtime process Fix ksoftirqd termination on cpu hotplug with naughty real time process. Assuming the following case: - Try to hot remove CPU2 from CPU1. - There is a real time process on CPU2, and that process doesn't sleep at all. - That rt process and ksoftirqd/2 is migrated to the CPU0 Then ksoftirqd/2 can't stop becasue that rt process runs everlastingly on CPU0, and CPU1 waiting the ksoftirqd/2's termination hangs up. To fix this problem, set the priority of ksoftirqd/2 to max one before kthread_stop(). [akpm@linux-foundation.org: fix warning] Signed-off-by: Satoru Takeuchi Cc: Rusty Russell Cc: Ingo Molnar Cc: Oleg Nesterov Cc: Ashok Raj Cc: Gautham R Shenoy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/softirq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 73217a9e2875..8de267790166 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -614,12 +614,16 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb, kthread_bind(per_cpu(ksoftirqd, hotcpu), any_online_cpu(cpu_online_map)); case CPU_DEAD: - case CPU_DEAD_FROZEN: + case CPU_DEAD_FROZEN: { + struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; + p = per_cpu(ksoftirqd, hotcpu); per_cpu(ksoftirqd, hotcpu) = NULL; + sched_setscheduler(p, SCHED_FIFO, ¶m); kthread_stop(p); takeover_tasklets(hotcpu); break; + } #endif /* CONFIG_HOTPLUG_CPU */ } return NOTIFY_OK; -- 2.20.1