From: Miao Xie <miaox@cn.fujitsu.com>
To: Paul Menage <menage@google.com>
Cc: paulmck@linux.vnet.ibm.com, Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
containers@lists.linux-foundation.org, balbir@linux.vnet.ibm.com,
lizf@cn.fujitsu.com, Oleg Nesterov <oleg@redhat.com>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: Lockdep splat in cpuset code acquiring alloc_lock
Date: Thu, 15 Apr 2010 14:39:47 +0800 [thread overview]
Message-ID: <4BC6B4B3.8070000@cn.fujitsu.com> (raw)
In-Reply-To: <z2m6599ad831004141410tdc40feb0h529dabe4a39d67d5@mail.gmail.com>
CC Oleg
CC Ingo
on 2010-4-15 5:10, Paul Menage wrote:
> Looks like select_fallback_rq() shouldn't be calling
> cpuset_cpus_allowed_locked(), which does a task_lock(), which isn't
> IRQ safe. Also, according to its comments that should only be held
> with the cpuset callback_mutex held, which seems unlikely from a
> softirq handler.
>
> Also, calling cpuset_cpus_allowed_locked(p, &p->cpus_allowed) stomps
> on state in p without (AFAICS) synchronization.
>
> The description of commit e76bd8d9850c2296a7e8e24c9dce9b5e6b55fe2f
> includes the phrase " I'm fairly sure this works, but there might be a
> deadlock hiding" although I think that the lockdep-reported problem is
> different than what Rusty had in mind.
This problem have been fixed by Oleg Nesterov, and the patchset was merged
into tip tree, but it's scheduled for .35 ...
http://lkml.org/lkml/2010/3/15/73
Thanks!
Miao
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prev parent reply other threads:[~2010-04-15 6:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-14 20:23 Lockdep splat in cpuset code acquiring alloc_lock Paul E. McKenney
2010-04-14 21:10 ` Paul Menage
2010-04-15 6:39 ` Miao Xie [this message]
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