From patchwork Mon Feb 1 19:13:28 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Subash Abhinov Kasiviswanathan X-Patchwork-Id: 576679 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 16EE2140BFA for ; Tue, 2 Feb 2016 06:13:35 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752623AbcBATNa (ORCPT ); Mon, 1 Feb 2016 14:13:30 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:52402 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751660AbcBATN3 (ORCPT ); Mon, 1 Feb 2016 14:13:29 -0500 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 19D88604BA; Mon, 1 Feb 2016 19:13:29 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 0C716604F6; Mon, 1 Feb 2016 19:13:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham autolearn_force=no version=3.4.0 Received: from www.codeaurora.org (unknown [172.30.200.11]) by smtp.codeaurora.org (Postfix) with ESMTP id C9750604AB; Mon, 1 Feb 2016 19:13:28 +0000 (UTC) Received: from 172.30.200.101 (proxying for 199.106.103.60) (SquirrelMail authenticated user subashab@codeaurora.org) by www.codeaurora.org with HTTP; Mon, 1 Feb 2016 19:13:28 -0000 Message-ID: <2cf017eba84341c95d22fda2952a3f6f.squirrel@www.codeaurora.org> Date: Mon, 1 Feb 2016 19:13:28 -0000 Subject: [PATCH net] ipv6: addrconf: Fix recursive spin lock call From: subashab@codeaurora.org To: "Netdev" Cc: "'Eric Dumazet'" , "Hannes Frederic Sowa" User-Agent: SquirrelMail/1.4.22-4.el6 MIME-Version: 1.0 X-Priority: 3 (Normal) Importance: Normal X-Virus-Scanned: ClamAV using ClamSMTP Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org A rcu stall with the following backtrace was seen on a system with forwarding, optimistic_dad and use_optimistic set. To reproduce, set these flags and then start ipv6 autoconf. This occurs because the device write_lock is acquired while already holding the read_lock. Back trace below - INFO: rcu_preempt self-detected stall on CPU { 1} (t=2100 jiffies g=3992 c=3991 q=4471) <6> Task dump for CPU 1: <2> kworker/1:0 R running task 12168 15 2 0x00000002 <2> Workqueue: ipv6_addrconf addrconf_dad_work <6> Call trace: <2> [] el1_irq+0x68/0xdc <2> [] _raw_write_lock_bh+0x20/0x30 <2> [] __ipv6_dev_ac_inc+0x64/0x1b4 <2> [] addrconf_join_anycast+0x9c/0xc4 <2> [] __ipv6_ifa_notify+0x160/0x29c <2> [] ipv6_ifa_notify+0x50/0x70 <2> [] addrconf_dad_work+0x314/0x334 <2> [] process_one_work+0x244/0x3fc <2> [] worker_thread+0x2f8/0x418 <2> [] kthread+0xe0/0xec Change-Id: I270c05598622d400b178d758fdbd8296cf521ee8 Signed-off-by: Subash Abhinov Kasiviswanathan --- net/ipv6/addrconf.c | 2 ++ 1 file changed, 2 insertions(+) -- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 2163871..ae8ac1a 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3301,7 +3301,9 @@ static void addrconf_dad_begin(struct inet6_ifaddr *ifp) /* Because optimistic nodes can use this address, * notify listeners. If DAD fails, RTM_DELADDR is sent. */ + read_unlock_bh(&idev->lock); ipv6_ifa_notify(RTM_NEWADDR, ifp); + read_lock_bh(&idev->lock); } }