From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH v2] ipv6: Don't depend on per socket memory for neighbour discovery messages Date: Tue, 3 Sep 2013 20:30:19 +0200 Message-ID: <20130903183019.GG21729@order.stressinduktion.org> References: <52261A12.3060203@wwwdotorg.org> <20130903172736.GB21729@order.stressinduktion.org> <52261F68.70907@wwwdotorg.org> <1378230697.7360.38.camel@edumazet-glaptop> <52262462.80308@wwwdotorg.org> <20130903182348.GB4166@casper.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Stephen Warren , Eric Dumazet , davem@davemloft.net, netdev@vger.kernel.org, Fabio Estevam To: Thomas Graf Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:35165 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755694Ab3ICSaV (ORCPT ); Tue, 3 Sep 2013 14:30:21 -0400 Content-Disposition: inline In-Reply-To: <20130903182348.GB4166@casper.infradead.org> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Sep 03, 2013 at 07:23:48PM +0100, Thomas Graf wrote: > On 09/03/13 at 12:03pm, Stephen Warren wrote: > > On 09/03/2013 11:51 AM, Eric Dumazet wrote: > > > On Tue, 2013-09-03 at 11:42 -0600, Stephen Warren wrote: > > > > > >> I don't see any extra messages from PROVE_LOCKING related to networking. > > >> There is a single extra message from inside the audio driver, but that's > > >> not networking-related at all. > > > > > > LOCKDEP is automatically disabled at first splat. > > > > > > Please try a kernel without audio driver ;) > > > > Ah, OK. Now I do see something from ipv6: > > > > > [ 25.327622] > > > [ 25.329142] ============================================= > > > [ 25.334533] [ INFO: possible recursive locking detected ] > > > [ 25.339927] 3.11.0-rc7-next-20130830-00024-g209b4d8-dirty #17 Not tainted > > > [ 25.346705] --------------------------------------------- > > > [ 25.352095] login/704 is trying to acquire lock: > > > [ 25.356705] (&ndev->lock){++--..}, at: [] ipv6_chk_mcast_addr+0x5c/0x200 > > > [ 25.364405] > > > [ 25.364405] but task is already holding lock: > > > [ 25.370230] (&ndev->lock){++--..}, at: [] addrconf_rs_timer+0x18/0x134 > > Real deadlock, we should not hold idev->lock for ndisc_send_rs(), we > should drop the lock beforehand I guess. We also don't hold idev->lock > if we send out the RS via addrconf_dad_completed(). Yes, this already happend by the series to implement ipv6 for vxlan: caf92bc4007036cfac8ee06c845fdfe6496e4fb3 ("ipv6: do not call ndisc_send_rs() with write lock"). > I'm confused why lockdep would only trigger after my patch, the > deadlock is unrelated. Reordering by the compiler in the short-curcuit evaluation in ip6_finish_output2 maybe (sk_mc_loop)? Greetings, Hannes