From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>,
Li Zefan <lizf@cn.fujitsu.com>, Ingo Molnar <mingo@elte.hu>,
eric.dumazet@gmail.com, shaohua.li@intel.com, ak@linux.intel.com,
mhocko@suse.cz, alex.shi@intel.com, efault@gmx.de,
linux-kernel@vger.kernel.org, Paul Turner <pjt@google.com>
Subject: Re: [GIT PULL rcu/next] RCU commits for 3.1
Date: Mon, 7 Nov 2011 09:53:32 -0800 [thread overview]
Message-ID: <20111107175332.GJ2332@linux.vnet.ibm.com> (raw)
In-Reply-To: <1320686777.17809.34.camel@twins>
On Mon, Nov 07, 2011 at 06:26:17PM +0100, Peter Zijlstra wrote:
> On Mon, 2011-11-07 at 17:12 +0000, Stephane Eranian wrote:
> > I think on that path:
> >
> > >>> [<8108aa02>] perf_event_enable_on_exec+0x1d2/0x1e0
> > >>> [<81063764>] ? __lock_release+0x54/0xb0
> > >>> [<8108cca8>] perf_event_comm+0x18/0x60
> > >>> [<810d1abd>] ? set_task_comm+0x5d/0x80
> > >>> [<81af622d>] ? _raw_spin_unlock+0x1d/0x40
> > >>> [<810d1ac4>] set_task_comm+0x64/0x80
> >
> > We are neither holding the rcu_read_lock() nor the task_lock() but we
> > are operating on the current task. The task cannot just vanish. So
> > the rcu_dereference() and lock_is_held() macros may detect a false
> > positive in that case. Yet, I doubt this would be the only place....
>
> Well, normally being current doesn't guarantee your cgroup won't
> disappear. The perf stuff hwoever takes refs and is synced against
> ->attach() by virtue of it calling perf_cgroup_switch() etc..
OK, never mind my task==current suggestion. :-/
Thanx, Paul
next prev parent reply other threads:[~2011-11-07 17:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110930204503.GA32687@linux.vnet.ibm.com>
[not found] ` <20111001152514.GA16930@elte.hu>
[not found] ` <20111003055302.GA23527@elte.hu>
[not found] ` <20111003161335.GA2403@linux.vnet.ibm.com>
2011-10-04 7:46 ` Ingo Molnar
2011-10-24 10:05 ` Paul E. McKenney
2011-10-24 11:48 ` Paul E. McKenney
2011-10-26 20:30 ` Ingo Molnar
2011-10-27 7:59 ` Paul E. McKenney
2011-10-27 8:00 ` Ingo Molnar
2011-10-28 2:34 ` Li Zefan
2011-10-29 18:27 ` Paul E. McKenney
2011-10-31 8:09 ` Li Zefan
2011-10-31 9:32 ` Paul E. McKenney
2011-11-01 2:37 ` Li Zefan
2011-11-02 19:23 ` Paul E. McKenney
2011-11-02 19:55 ` Stephane Eranian
2011-11-03 12:50 ` Stephane Eranian
2011-11-04 8:44 ` Li Zefan
2011-11-04 9:02 ` Stephane Eranian
2011-11-07 14:24 ` Stephane Eranian
2011-11-07 14:41 ` Eric Dumazet
2011-11-07 14:44 ` Stephane Eranian
2011-11-07 15:15 ` Peter Zijlstra
2011-11-07 16:16 ` Stephane Eranian
2011-11-07 16:35 ` Peter Zijlstra
2011-11-07 16:56 ` Paul E. McKenney
2011-11-07 17:09 ` Peter Zijlstra
2011-11-07 17:55 ` Paul E. McKenney
2011-11-08 13:10 ` Stephane Eranian
2011-11-07 17:11 ` Peter Zijlstra
2011-11-07 17:12 ` Stephane Eranian
2011-11-07 17:26 ` Peter Zijlstra
2011-11-07 17:50 ` Stephane Eranian
2011-11-07 17:53 ` Paul E. McKenney [this message]
2011-11-07 17:53 ` Paul E. McKenney
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