From: David Miller <davem@davemloft.net>
To: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com, a.p.zijlstra@chello.nl, mingo@elte.hu,
sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Weird rcu lockdep warning
Date: Tue, 13 Apr 2010 18:51:06 -0700 (PDT) [thread overview]
Message-ID: <20100413.185106.46340154.davem@davemloft.net> (raw)
In-Reply-To: <20100414014930.GI2538@linux.vnet.ibm.com>
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Tue, 13 Apr 2010 18:49:30 -0700
> On Tue, Apr 13, 2010 at 05:13:06PM -0700, David Miller wrote:
>> From: Frederic Weisbecker <fweisbec@gmail.com>
>> Date: Wed, 14 Apr 2010 02:02:27 +0200
>>
>> > I just have a guess though....
>> > This seems to always happen from NMI path, and lockdep is disabled on NMI.
>> > I suspect the lock_acquire() performed by rcu_read_lock() is just ignored
>> > and then the rcu_read_lock_held() check has the wrong result...
>>
>> Yeah, I bet that's it too.
>>
>> lock_is_held() can't return anything meaningful while lockdep is
>> disabled, which it is during NMIs.
>
> Ah! So I just need to add a "current->lockdep_recursion"
> check to debug_lockdep_rcu_enabled(). And move the function to
> kernel/rcutree_plugin.h to avoid #include hell.
>
> See below for (untested) patch.
Looks good to me, Frederic please test :-)
next prev parent reply other threads:[~2010-04-14 1:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-13 20:04 Frederic Weisbecker
2010-04-13 23:40 ` Paul E. McKenney
2010-04-14 0:02 ` Frederic Weisbecker
2010-04-14 0:13 ` David Miller
2010-04-14 1:49 ` Paul E. McKenney
2010-04-14 1:51 ` David Miller [this message]
2010-04-14 3:34 ` Lai Jiangshan
2010-04-14 15:43 ` Paul E. McKenney
2010-04-14 15:51 ` Frederic Weisbecker
2010-04-14 16:00 ` Paul E. McKenney
2010-04-15 4:24 ` Paul E. McKenney
2010-04-15 18:57 ` Frederic Weisbecker
2010-04-15 19:47 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100413.185106.46340154.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=a.p.zijlstra@chello.nl \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulmck@linux.vnet.ibm.com \
--cc=sparclinux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome