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From: Steven Rostedt <rostedt@goodmis.org>
To: paulmck@linux.vnet.ibm.com
Cc: Fengguang Wu <fengguang.wu@intel.com>,
	Avi Kivity <avi@redhat.com>, Steven Rostedt <srostedt@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: Testing tracer wakeup_rt: .. no entries found ..FAILED!
Date: Tue, 31 Jul 2012 20:09:38 -0400	[thread overview]
Message-ID: <1343779778.27983.73.camel@gandalf.stny.rr.com> (raw)
In-Reply-To: <20120731235705.GW2422@linux.vnet.ibm.com>

On Tue, 2012-07-31 at 16:57 -0700, Paul E. McKenney wrote:

> > What was the next lines? I bet you it was "PASSED". Which means it did
> > not fail. This is the second bug you found that has to do with RCU being
> > called in 'idle'. The one that Paul posted a patch for.
> 
> Though it needs another patch to actually use it in the right place...

Right. Something like this:

-- Steve

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5638104..d915638 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -631,7 +631,12 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
 	memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
 	max_data->pid = tsk->pid;
-	max_data->uid = task_uid(tsk);
+	/*
+	 * task_uid() calls rcu_read_lock, but this can be called
+	 * outside of RCU state monitoring (irq going back to idle).
+	 */ 
+	RCU_NONIDLE(max_data->uid = task_uid(tsk));
+
 	max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
 	max_data->policy = tsk->policy;
 	max_data->rt_priority = tsk->rt_priority;



  reply	other threads:[~2012-08-01  0:09 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-24  9:03 __update_max_tr: rcu_read_lock() used illegally while idle! Fengguang Wu
2012-07-24  9:07 ` Testing tracer wakeup_rt: .. no entries found ..FAILED! Fengguang Wu
2012-07-25  1:31   ` Testing tracer wakeup: " Fengguang Wu
2012-07-30 15:45   ` Testing tracer wakeup_rt: " Steven Rostedt
2012-07-31 12:17     ` Fengguang Wu
2012-07-31 12:37       ` Avi Kivity
2012-07-31 12:43         ` Steven Rostedt
2012-07-31 12:50           ` Avi Kivity
2012-07-31 13:13             ` Steven Rostedt
2012-07-31 23:43               ` Fengguang Wu
2012-07-31 23:51                 ` Steven Rostedt
2012-07-31 23:57                   ` Paul E. McKenney
2012-08-01  0:09                     ` Steven Rostedt [this message]
2012-08-01  0:18                       ` Paul E. McKenney
2012-08-01  0:43                         ` pci_get_subsys: GFP_KERNEL allocations with IRQs disabled Fengguang Wu
2012-08-22  2:50                           ` Fengguang Wu
2012-08-22  7:49                             ` Feng Tang
2012-08-22 13:02                               ` Fengguang Wu
2012-08-22 18:02                               ` Bjorn Helgaas
2012-08-23  5:45                                 ` Feng Tang
2012-08-23  7:45                                 ` [PATCH 1/2] PCI: Use local parameter pci_device_id for pci_get_subsys/class() Feng Tang
2012-09-08  1:00                                   ` Yinghai Lu
2012-09-08  1:32                                     ` Yinghai Lu
2012-09-08  1:59                                       ` Greg Kroah-Hartman
2012-09-08 13:42                                       ` Fengguang Wu
2012-09-08 15:30                                         ` Yinghai Lu
2012-09-08 15:34                                         ` Feng Tang
2012-09-08 18:40                                           ` Yinghai Lu
2012-09-08 21:06                                             ` Bjorn Helgaas
2012-08-23  7:45                                 ` [PATCH 2/2] PCI: Remove the obsolete no_pci_devices() check Feng Tang
2012-07-31 23:57                   ` Testing tracer wakeup_rt: .. no entries found ..FAILED! Fengguang Wu
2012-08-07 13:29                     ` Steven Rostedt
2012-08-07 13:32                       ` Fengguang Wu
2012-08-21 15:16     ` [tip:perf/core] tracing: Fix wakeup_rt self test on virtual machines tip-bot for Steven Rostedt
2012-07-30 15:39 ` __update_max_tr: rcu_read_lock() used illegally while idle! Steven Rostedt
2012-07-31 12:05   ` Fengguang Wu
2012-07-31 12:10     ` Fengguang Wu
2012-07-31 13:44       ` Steven Rostedt
2012-07-31 14:41         ` Paul E. McKenney
2012-07-31 13:33     ` Steven Rostedt
2012-07-31 14:44       ` Paul E. McKenney
2012-07-31 14:51         ` Steven Rostedt
2012-07-31 14:56           ` Steven Rostedt
2012-07-31 15:18             ` Paul E. McKenney
2012-07-31 15:45               ` Steven Rostedt
2012-07-31 17:17                 ` Paul E. McKenney
2012-07-31 17:24                   ` Steven Rostedt
2012-07-31 17:44                     ` Paul E. McKenney
2012-07-31 18:06                       ` Steven Rostedt
2012-07-31 18:21                         ` Paul E. McKenney
2012-07-31 15:00           ` Paul E. McKenney

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