From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Nigel Cunningham <ncunningham@cyclades.com>
Cc: Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
Zwane Mwaikambo <zwane@arm.linux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: PATCH: Fix race in cpu_down (hotplug cpu)
Date: Mon, 19 Sep 2005 09:52:40 +0530 [thread overview]
Message-ID: <20050919042240.GA7506@in.ibm.com> (raw)
In-Reply-To: <1127100518.9696.62.camel@localhost>
On Mon, Sep 19, 2005 at 01:28:38PM +1000, Nigel Cunningham wrote:
> There is a race condition in taking down a cpu (kernel/cpu.c::cpu_down).
> A cpu can already be idling when we clear its online flag, and we do not
> force the idle task to reschedule. This results in __cpu_die timing out.
"when we clear its online flag" - This happens in take_cpu_down in the
context of stopmachine thread. take_cpu_down also ensures that idle
thread runs when it returns (sched_idle_next). So when idle thread runs,
it should notice that it is offline and invoke play_dead. So I don't
understand why __cpu_die should time out.
--
Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017
next prev parent reply other threads:[~2005-09-19 4:23 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-19 3:28 PATCH: Fix race in cpu_down (hotplug cpu) Nigel Cunningham
2005-09-19 4:22 ` Srivatsa Vaddagiri [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-09-19 4:48 Li, Shaohua
2005-09-19 5:10 ` Srivatsa Vaddagiri
2005-09-19 5:31 ` Shaohua Li
2005-09-19 5:57 ` Srivatsa Vaddagiri
2005-09-19 6:11 ` Nigel Cunningham
2005-09-19 6:23 ` Srivatsa Vaddagiri
2005-09-19 6:29 ` Nick Piggin
2005-09-19 7:00 ` Srivatsa Vaddagiri
2005-09-19 6:31 ` Nigel Cunningham
2005-09-19 7:09 ` Srivatsa Vaddagiri
2005-09-19 6:37 ` Shaohua Li
2005-09-19 6:36 ` Nick Piggin
2005-09-19 6:54 ` Nigel Cunningham
2005-09-19 7:12 ` Shaohua Li
2005-09-19 7:22 ` Nick Piggin
2005-09-19 7:28 ` Ingo Molnar
2005-09-19 7:37 ` Nick Piggin
2005-09-19 22:55 ` Nigel Cunningham
2005-09-20 4:41 ` Srivatsa Vaddagiri
2005-09-19 7:07 ` Srivatsa Vaddagiri
2005-09-19 5:23 ` Nigel Cunningham
2005-09-19 5:28 ` Srivatsa Vaddagiri
2005-09-19 5:35 ` Nigel Cunningham
2005-09-19 3:15 Nigel Cunningham
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