From: Oleg Nesterov <oleg@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: mingo@redhat.com, hpa@zytor.com, acme@redhat.com,
paulus@samba.org, linux-kernel@vger.kernel.org,
stern@rowland.harvard.edu, a.p.zijlstra@chello.nl,
fweisbec@gmail.com, roland@redhat.com, tglx@linutronix.de,
prasad@linux.vnet.ibm.com, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/urgent] perf: Fix find_get_context() vs perf_event_exit_task() race
Date: Fri, 21 Jan 2011 16:53:23 +0100 [thread overview]
Message-ID: <20110121155323.GA2988@redhat.com> (raw)
In-Reply-To: <20110121152939.GA28552@elte.hu>
On 01/21, Ingo Molnar wrote:
>
> * tip-bot for Oleg Nesterov <oleg@redhat.com> wrote:
>
> > @@ -6127,7 +6133,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
> > * scheduled, so we are now safe from rescheduling changing
> > * our context.
> > */
> > - child_ctx = child->perf_event_ctxp[ctxn];
> > + child_ctx = rcu_dereference(child->perf_event_ctxp[ctxn]);
> > task_ctx_sched_out(child_ctx, EVENT_ALL);
> >
> > /*
>
> hm, this one's causing:
>
> [ 25.557579] ===================================================
> [ 25.561361] [ INFO: suspicious rcu_dereference_check() usage. ]
Oh, indeed, I am stupid!
I added rcu_dereference() because it has smp_read_barrier_depends(),
but I forgot about rcu_dereference_check().
I'll send the fix soon...
Oleg.
next prev parent reply other threads:[~2011-01-21 16:01 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-08 14:56 Q: perf_event && task->ptrace_bps[] Oleg Nesterov
2010-11-08 14:57 ` Q: sys_perf_event_open() && PF_EXITING Oleg Nesterov
2011-01-19 18:21 ` [PATCH 0/2] Was: " Oleg Nesterov
2011-01-19 18:22 ` [PATCH 1/2] perf: fix find_get_context() vs perf_event_exit_task() race Oleg Nesterov
2011-01-19 18:49 ` Peter Zijlstra
2011-01-19 19:18 ` [tip:perf/urgent] perf: Fix " tip-bot for Oleg Nesterov
2011-01-21 15:29 ` Ingo Molnar
2011-01-21 15:53 ` Oleg Nesterov [this message]
2011-01-21 17:45 ` [PATCH] perf: perf_event_exit_task_context: s/rcu_dereference/rcu_dereference_raw/ Oleg Nesterov
2011-01-21 17:53 ` Oleg Nesterov
2011-01-21 21:50 ` Paul E. McKenney
2011-01-24 11:51 ` Oleg Nesterov
2011-01-21 22:12 ` [tip:perf/urgent] " tip-bot for Oleg Nesterov
2011-01-19 18:22 ` [PATCH 2/2] perf: fix perf_event_init_task()/perf_event_free_task() interaction Oleg Nesterov
2011-01-19 18:51 ` Peter Zijlstra
2011-01-19 19:19 ` [tip:perf/urgent] perf: Fix " tip-bot for Oleg Nesterov
2011-01-20 19:30 ` Q: perf_install_in_context/perf_event_enable are racy? Oleg Nesterov
2011-01-21 12:11 ` Peter Zijlstra
2011-01-21 13:03 ` Ingo Molnar
2011-01-21 13:39 ` Peter Zijlstra
2011-01-21 14:26 ` Oleg Nesterov
2011-01-21 15:05 ` Peter Zijlstra
2011-01-21 20:40 ` Frederic Weisbecker
2011-01-24 11:42 ` Oleg Nesterov
2011-01-26 17:53 ` Oleg Nesterov
2011-01-26 18:49 ` Oleg Nesterov
2011-01-26 18:51 ` [PATCH] fix the theoretical task_cpu/task_curr problem in kick_process/task_oncpu_function_call Oleg Nesterov
2011-01-26 19:05 ` Q: perf_install_in_context/perf_event_enable are racy? Peter Zijlstra
2011-01-26 19:33 ` Peter Zijlstra
2011-01-26 19:38 ` Peter Zijlstra
2011-01-26 21:19 ` Oleg Nesterov
2011-01-26 21:33 ` Oleg Nesterov
2011-01-27 10:32 ` Peter Zijlstra
2011-01-27 12:29 ` Peter Zijlstra
2011-01-27 16:10 ` Oleg Nesterov
2011-01-27 16:27 ` Peter Zijlstra
2011-01-27 16:59 ` Oleg Nesterov
2011-01-27 15:52 ` Oleg Nesterov
2011-01-27 13:14 ` Peter Zijlstra
2011-01-27 14:28 ` Peter Zijlstra
2011-01-27 14:58 ` Peter Zijlstra
2011-01-27 16:57 ` Oleg Nesterov
2011-01-27 17:11 ` Peter Zijlstra
2011-01-27 22:18 ` Oleg Nesterov
2011-01-28 11:52 ` Peter Zijlstra
2011-01-28 14:57 ` Peter Zijlstra
2011-01-28 16:28 ` Oleg Nesterov
2011-01-28 18:11 ` Peter Zijlstra
2011-01-31 17:26 ` Oleg Nesterov
2011-01-31 18:23 ` Peter Zijlstra
2011-01-31 19:11 ` Oleg Nesterov
2011-01-31 19:29 ` Peter Zijlstra
2011-02-01 14:03 ` [PATCH] perf: Cure task_oncpu_function_call() races Peter Zijlstra
2011-02-01 17:27 ` Oleg Nesterov
2011-02-01 18:08 ` Peter Zijlstra
2011-02-01 18:18 ` Peter Zijlstra
2011-02-01 21:00 ` Peter Zijlstra
2010-11-08 14:57 ` Q: perf_event && event->owner Oleg Nesterov
2010-11-08 20:11 ` Frederic Weisbecker
2010-11-08 20:41 ` Peter Zijlstra
2010-11-09 16:18 ` Oleg Nesterov
2010-11-09 15:57 ` Oleg Nesterov
2010-11-09 16:56 ` Peter Zijlstra
2010-11-09 16:58 ` Oleg Nesterov
2010-11-09 17:07 ` Peter Zijlstra
2010-11-09 17:42 ` Oleg Nesterov
2010-11-09 18:01 ` Peter Zijlstra
2010-11-09 18:57 ` Oleg Nesterov
2010-11-09 19:16 ` Peter Zijlstra
2010-11-10 15:17 ` Peter Zijlstra
2010-11-10 15:44 ` Oleg Nesterov
2010-11-12 15:48 ` Peter Zijlstra
2010-11-12 18:49 ` Oleg Nesterov
2010-11-18 14:09 ` [tip:perf/urgent] perf: Fix owner-list vs exit tip-bot for Peter Zijlstra
2010-11-08 18:41 ` Q: perf_event && task->ptrace_bps[] Frederic Weisbecker
2010-11-08 19:18 ` Oleg Nesterov
2011-01-17 23:58 ` Frederic Weisbecker
2011-01-18 1:16 ` Roland McGrath
2011-01-17 20:34 ` Oleg Nesterov
2011-01-17 20:52 ` Peter Zijlstra
2011-01-17 21:01 ` Frederic Weisbecker
2011-01-18 16:09 ` [PATCH 0/2] perf: event->cpu checking fixes Oleg Nesterov
2011-01-18 16:10 ` [PATCH 1/2] perf: find_get_context: fix the per-cpu-counter check Oleg Nesterov
2011-01-18 19:06 ` [tip:perf/urgent] perf: Find_get_context: " tip-bot for Oleg Nesterov
2011-01-18 16:10 ` [PATCH 2/2] perf: validate cpu early in perf_event_alloc() Oleg Nesterov
2011-01-18 19:07 ` [tip:perf/urgent] perf: Validate " tip-bot for Oleg Nesterov
2011-01-18 18:42 ` Q: perf_event && task->ptrace_bps[] Frederic Weisbecker
2011-01-19 15:37 ` Oleg Nesterov
2011-01-19 20:05 ` Frederic Weisbecker
2011-01-20 17:28 ` Oleg Nesterov
2011-01-28 17:41 ` Frederic Weisbecker
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