Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966017AbXFFXMn (ORCPT ); Wed, 6 Jun 2007 19:12:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965434AbXFFXMe (ORCPT ); Wed, 6 Jun 2007 19:12:34 -0400 Received: from nz-out-0506.google.com ([64.233.162.228]:14777 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965225AbXFFXMd (ORCPT ); Wed, 6 Jun 2007 19:12:33 -0400 Message-ID: <5640c7e00706061612h62074699wdbd2725654a164@mail.gmail.com> Date: Thu, 7 Jun 2007 11:12:32 +1200 From: "Ian McDonald" To: "Chuck Ebbert" Subject: Re: [BUG] Fwd: segfault : modprobe dccp_probe/tcp_probe Cc: "Linux Kernel Mailing List" , prasanna@in.ibm.com, ananth@in.ibm.com, anil.s.keshavamurthy@intel.com, "David S. Miller" , "Patrick Andrieux" , "DCCP Mailing List" , jbeulich@novell.com In-Reply-To: <46673B76.2090508@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <5640c7e00706061347v42c9ecbahb5354f6687a70a78@mail.gmail.com> <46673B76.2090508@redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1580 Lines: 39 On 6/7/07, Chuck Ebbert wrote: > On 06/06/2007 04:47 PM, Ian McDonald wrote: > > Hi there, > > > > We've seen a report of a problem with dccp_probe as shown below. The > > user has also verified that it occurs in tcp_probe as well. This is on > > Dave Miller's tree but that currently tracks Linus' tree quite > > closely. I do note that it is around 2.6.22-rc2 timeframe so there is > > a possibility fixes may have gone in since. > > > > It faulted when it tried to write the breakpoint instruction into the > running kernel's executable code. Apparently the kernel code is now marked > read-only? > > Yes it would appear to be the case as user has CONFIG_DEBUG_RODATA set. Patrick - can you turn this off and retest? It's under Kernel Hacking, Write protect kernel read only data structures. The list of commits that I see around this are at: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git&a=search&h=HEAD&st=commit&s=DEBUG_RODATA I suspect it's probably one of the latter ones giving the timing. I guess there are a couple of solutions here - either make kprobes conflict with CONFIG_DEBUG_RODATA so you can do one or the other, or look into more detail what access kprobes need. Ian -- Web: http://wand.net.nz/~iam4/ Blog: http://iansblog.jandi.co.nz WAND Network Research Group - 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/