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Date: Mon, 22 Feb 2010 17:12:10 +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 Mon, Feb 22, 2010 at 5:04 PM, Johannes Berg <johannes@...solutions.net> wrote: > On Mon, 2010-02-22 at 16:34 +0800, Américo Wang wrote: >> 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? > > No luck. > Ok, thanks. Since it hangs in put_cpu() which is just preempt_enable(), so I began to suspect if we need a synchronize_sched(), or some barrier perhaps. I am not sure at all. Before other experts look at this, I think doing a bisect would be very useful. Again, thanks for your testing! -- 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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