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Date: Mon, 22 Feb 2010 16:34:40 +0800 From: Américo Wang <xiyou.wangcong@...il.com> To: Johannes Berg <johannes@...solutions.net> Cc: Xiaotian Feng <xtfeng@...il.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org> Subject: Re: [2.6.33-rc5] Weird deadlock when shutting down On Sun, Feb 21, 2010 at 7:22 PM, Johannes Berg <johannes@...solutions.net> wrote: > On Sun, 2010-02-21 at 12:14 +0100, Johannes Berg wrote: > >> printk("got cpu\n"); >> for_each_online_cpu(i) { >> sm_work = per_cpu_ptr(stop_machine_work, i); >> INIT_WORK(sm_work, stop_cpu); >> queue_work_on(i, stop_machine_wq, sm_work); >> } >> /* This will release the thread on our CPU. */ >> put_cpu(); >> printk("put cpu\n"); > > As odd as that may be, it hangs in put_cpu() here. > Hmm, does adding synchronize_sched() in _cpu_down() help? Something like this: diff --git a/kernel/cpu.c b/kernel/cpu.c index 677f253..681f5c5 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -228,6 +228,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) cpumask_copy(old_allowed, ¤t->cpus_allowed); set_cpus_allowed_ptr(current, cpu_active_mask); + synchronize_sched(); err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu)); if (err) { set_cpu_active(cpu, true); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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