From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Am=C3=A9rico_Wang?= Subject: Re: 2.6.34-rc1: rcu lockdep bug? Date: Mon, 15 Mar 2010 18:12:29 +0800 Message-ID: <2375c9f91003150312u37dfd70fk55a4b8820e13590e@mail.gmail.com> References: <20100311134556.GA6344@linux.vnet.ibm.com> <1268392276.3141.4.camel@edumazet-laptop> <2375c9f91003120511j6f33592cl12cb2617a27351ec@mail.gmail.com> <1268401058.3141.9.camel@edumazet-laptop> <20100313053356.GC3704@hack> <20100313215838.GB6805@linux.vnet.ibm.com> <20100315010802.GB2735@hack> <2375c9f91003142010g61841666iad53c24f39036acf@mail.gmail.com> <2375c9f91003150239m1abc765bh59eb51c948eed592@mail.gmail.com> <1268647460.3154.1.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "Paul E. McKenney" , David Miller , peterz@infradead.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from mail-qy0-f179.google.com ([209.85.221.179]:53913 "EHLO mail-qy0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964792Ab0COKMa convert rfc822-to-8bit (ORCPT ); Mon, 15 Mar 2010 06:12:30 -0400 In-Reply-To: <1268647460.3154.1.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Mar 15, 2010 at 6:04 PM, Eric Dumazet = wrote: > Le lundi 15 mars 2010 =C3=A0 17:39 +0800, Am=C3=A9rico Wang a =C3=A9c= rit : > >> >> Ok, I think I found what lockdep really complains about, it is that = we took >> spin_lock in netpoll_poll_lock() which is in hardirq-enabled environ= ment, >> later, we took another spin_lock with spin_lock_irqsave() in netpoll= _rx(), >> so lockdep thought we broke the locking rule. >> >> I don't know why netpoll_rx() needs irq disabled, it looks like that= no one >> takes rx_lock in hardirq context. So can we use spin_lock(&rx_lock) >> instead? Or am I missing something here? Eric? David? > > I am a bit lost. > > Could you give the complete picture, because I cannot find it in my > netdev archives. > Sure, sorry for this. Here is the whole thread: http://lkml.org/lkml/2010/3/11/100