From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: kernel BUG in ipmr_queue_xmit() Date: Fri, 30 Oct 2015 01:15:10 +0100 Message-ID: <20151030001510.GG18062@breakpoint.cc> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, ani@anirban.org, fruggeri@arista.com To: Ani Sinha Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:60968 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757072AbbJ3APO (ORCPT ); Thu, 29 Oct 2015 20:15:14 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Ani Sinha wrote: [ trimmed CC list ] > We are noticing the following kernel BUG in 3.18 kernel. The > code path that leads to the crash is the following : > > ip_mroute_setsockopt() > ->ipmr_mfc_add() > ->ipmr_cache_resolve() > ->ip_mr_forward() > -> ipmr_queue_xmit() > -> ipmr_forward_finish() > ->IP_INC_STATS_BH() > -> SNMP_INC_STATS64_BH() > -> SNMP_INC_STATS_BH() > -> __this_cpu_inc() > -> __this_cpu_add() > -> __this_cpu_preempt_check() > -> check_preemption_disabled() > > I have verified that preempt_count() is 0 when the crash happens. > Is anyone else seeing the same crash in the laetst upstream code? I dug > around a little bit and it does not look like there were any fixes that > went into post 3.18 kernel which could have disabled preemption in this > code path but I could be wrong. > > thoughts? Send a patch to preempt_disable before ip_mr_forward call in the affected setsockopt path?