Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932468AbZJTA4F (ORCPT ); Mon, 19 Oct 2009 20:56:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932401AbZJTA4E (ORCPT ); Mon, 19 Oct 2009 20:56:04 -0400 Received: from smtp.zeugmasystems.com ([70.79.96.174]:25008 "EHLO zeugmasystems.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932396AbZJTA4D (ORCPT ); Mon, 19 Oct 2009 20:56:03 -0400 Date: Mon, 19 Oct 2009 17:56:07 -0700 (PDT) From: Anirban Sinha X-X-Sender: asinha@sleet.zeugmasystems.local To: Oleg Nesterov cc: Anirban Sinha , linux-kernel@vger.kernel.org, David Miller , netdev@vger.kernel.org Subject: Re: Kernel oops when clearing bgp neighbor info with TCP MD5SUM enabled In-Reply-To: <20091019121327.GA11423@redhat.com> Message-ID: References: <20091008.155429.02850661.davem@davemloft.net> <20091008.175703.83006470.davem@davemloft.net> <4ADA7EDC.5010402@anirban.org> <4ADB7856.7000803@anirban.org> <20091019121327.GA11423@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 20 Oct 2009 00:56:07.0081 (UTC) FILETIME=[1B360990:01CA5120] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1143 Lines: 26 > I'd suppose that this unbalance comes from inet_twdr_hangman() pathes. > > Could you verify this? Yes, I have now verified this. There is indeed an issue with one of the functions called by inet_twdr_hangman(). The call sequence is: inet_twdr_hangman() -> inet_twdr_do_twkill_work() -> inet_twsk_put() -> twsk_destructor(). In this case, the destructor callback is tcp_twsk_destructor() (installed from line 1208 in net/ipv4/tcp_ipv4.c and line 906 in net/ipv6/tcp_ipv6.c) . Without the TCP_MD5SUM compiled in, the function is a no-op. However, with the MD5SUM compiled in, it calls tcp_put_md5_sig_pool() (when keylen is non zero) which does an unbalanced put_cpu(). I did a grep across the entire tree. tcp_put_md5_sig_pool() is a matching function for tcp_get_md5_sig_pool() and in all other TCP IPV4 cases, it is called from net/ipv4/tcp_ipv4.c from functions tcp_v4_md5_hash_hdr() and -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/