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Date: Tue, 26 Jan 2010 14:01:12 +0800
Message-ID: <2375c9f91001252201t552022ebvcd44b225eb7f9a95@mail.gmail.com>
Subject: Re: [2.6.33-rc5] starting emacs makes lockdep warning
From: =?UTF-8?Q?Am=C3=A9rico_Wang?= <xiyou.wangcong@gmail.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
       Al Viro <viro@zeniv.linux.org.uk>, Tavis Ormandy <taviso@google.com>,
       Jeff Dike <jdike@addtoit.com>, Julien Tinnes <jln@google.com>,
       Matt Mackall <mpm@selenic.com>, LKML <linux-kernel@vger.kernel.org>,
       Oleg Nesterov <oleg@redhat.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
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On Tue, Jan 26, 2010 at 1:49 PM, KOSAKI Motohiro
<kosaki.motohiro@jp.fujitsu.com> wrote:
>> > On Tue, Jan 26, 2010 at 11:20 AM, KOSAKI Motohiro
>> > <kosaki.motohiro@jp.fujitsu.com> wrote:
>> > > Hi
>> > >
>> > > Current linus tree made following lockdep warning when starting emacs command.
>> > > Is this known issue?
>> > >
>> > >
>> > > =========================================================
>> > > [ INFO: possible irq lock inversion dependency detected ]
>> > > 2.6.33-rc5 #77
>> > > ---------------------------------------------------------
>> > > emacs/1609 just changed the state of lock:
>> > >  (&(&tty->ctrl_lock)->rlock){+.....}, at: [<ffffffff8127c648>] tty_fasync+0xe8/0x190
>> > > but this lock took another, HARDIRQ-unsafe lock in the past:
>> > >  (&(&sighand->siglock)->rlock){-.....}
>> > >
>> > > and interrupts could create inverse lock ordering between them.
>> > >
>> > >
>> >
>> > Hey,
>> >
>> > does reverting commit 703625118 help?
>>
>> Seems solved.
>>
>> Thanks.
>
> I'm sorry.
> I forgot to cc related person at last mail.
>
> Greg, can you please consider revert commit 703625118?
>

I agree, it seems that patch is useless, since we already
do lock_kernel() before calling __f_setown()...