From: Vivek Goyal <vgoyal@redhat.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <jaxboe@fusionio.com>, Paul Bolle <pebolle@tiscali.nl>,
linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Mysterious CFQ crash and RCU
Date: Mon, 23 May 2011 11:36:02 -0400 [thread overview]
Message-ID: <20110523153602.GC4019@redhat.com> (raw)
In-Reply-To: <20110521210013.GJ2271@linux.vnet.ibm.com>
On Sat, May 21, 2011 at 02:00:13PM -0700, Paul E. McKenney wrote:
[..]
> > Is there any known issue or is there any quick tip on how can I
> > go about debugging it further from rcu point of view.
>
> First for uses of RCU:
>
> o One thing to try would be CONFIG_PROVE_RCU, which could help
> find missing rcu_read_lock()s and similar. Some years back, it
> used to be the case that spin_lock() implied rcu_read_lock(),
> but it no longer does. There might still be some cases where
> spin_lock() needs to have an rcu_read_lock() added.
In this case we take explicit rcu_read_lock() in call_for_each_cic()
and do not rely on that spin_lock() also means rcu_read_lock().
call_for_each_cic() {
rcu_read_lock();
hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
func(ioc, cic);
rcu_read_unlock();
}
>
> o There are a few entries in the bugzilla mentioning that elements
> are being removed more often than expected.
Are you referring to my comments about additional messages of cgroup
changed. If yes, that issue has now been identified and I have posted
a fix to get rid of thos unnecessary calls.
https://lkml.org/lkml/2011/5/23/201
Is still there a need to enable CONFIG_DEBUG_OBJECTS_RCU_HEAD as the
kernel in question is non-preemptible one.
Thanks
Vivek
prev parent reply other threads:[~2011-05-23 15:36 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-19 22:24 Mysterious CFQ crash and RCU Vivek Goyal
2011-05-21 21:00 ` Paul E. McKenney
2011-05-21 22:23 ` Paul Bolle
2011-05-21 23:54 ` Paul E. McKenney
2011-05-22 19:30 ` Paul Bolle
2011-05-22 20:13 ` Paul E. McKenney
2011-05-23 15:21 ` Vivek Goyal
2011-05-23 15:38 ` Paul E. McKenney
2011-05-23 22:20 ` Paul Bolle
2011-05-24 4:14 ` Paul E. McKenney
2011-05-24 9:41 ` Jens Axboe
2011-05-24 14:35 ` Paul E. McKenney
2011-05-24 14:51 ` Jens Axboe
2011-05-24 15:42 ` Paul E. McKenney
2011-05-24 15:51 ` Paul E. McKenney
2011-05-25 8:28 ` Paul Bolle
2011-05-25 8:46 ` Jens Axboe
2011-05-25 9:13 ` Paul Bolle
2011-05-25 9:30 ` Jens Axboe
2011-05-25 9:40 ` Paul Bolle
2011-05-25 12:48 ` Paul Bolle
2011-05-25 12:51 ` Jens Axboe
2011-05-25 17:28 ` Paul Bolle
2011-05-25 18:59 ` Jens Axboe
2011-05-25 10:17 ` Paul Bolle
2011-05-25 15:33 ` Paul E. McKenney
2011-05-25 17:44 ` Paul Bolle
2011-05-25 20:40 ` Paul E. McKenney
2011-05-26 9:15 ` Paul Bolle
2011-06-03 5:07 ` Paul E. McKenney
2011-06-03 13:45 ` Vivek Goyal
2011-06-03 15:33 ` Paul E. McKenney
2011-06-03 16:54 ` Paul E. McKenney
2011-06-04 12:22 ` Paul Bolle
2011-06-04 12:50 ` Paul Bolle
2011-06-04 16:03 ` Paul E. McKenney
2011-06-04 22:48 ` Paul Bolle
2011-06-04 23:06 ` Paul E. McKenney
2011-08-04 15:05 ` Vivek Goyal
2011-08-04 19:43 ` Jens Axboe
2011-08-04 19:51 ` Vivek Goyal
2011-06-05 6:56 ` Jens Axboe
2011-06-05 8:39 ` Paul Bolle
2011-06-05 10:38 ` Paul Bolle
2011-06-05 22:51 ` Jens Axboe
2011-06-06 14:28 ` Vivek Goyal
2011-05-23 15:36 ` Vivek Goyal [this message]
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