From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jesse Brandeburg" Subject: Re: [RFC PATCH 02/12] On Tue, 23 Sep 2008, David Miller wrote: Date: Sat, 4 Oct 2008 18:24:10 -0700 Message-ID: <4807377b0810041824u5ea472d1q4cf5ff606bd23a11@mail.gmail.com> References: <20080930030825.22950.18891.stgit@jbrandeb-bw.jf.intel.com> <200810021523.45884.jbarnes@virtuousgeek.org> <20081003.134634.240211201.davem@davemloft.net> <200810031429.22598.jbarnes@virtuousgeek.org> <4807377b0810031628x43f79eferdbb9c9c264a5816e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Jiri Kosina" , "Jesse Barnes" , "David Miller" , jesse.brandeburg@intel.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kkeil@suse.de, agospoda@redhat.com, arjan@linux.intel.com, david.graham@intel.com, bruce.w.allan@intel.com, john.ronciak@intel.com, chris.jones@canonical.com, tim.gardner@canonical.com, airlied@gmail.com, "Olaf Kirch" , "Linus Torvalds" To: "Thomas Gleixner" Return-path: Received: from rv-out-0506.google.com ([209.85.198.227]:46006 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754061AbYJEBYL (ORCPT ); Sat, 4 Oct 2008 21:24:11 -0400 Received: by rv-out-0506.google.com with SMTP id k40so2310478rvb.1 for ; Sat, 04 Oct 2008 18:24:10 -0700 (PDT) In-Reply-To: Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: On Sat, Oct 4, 2008 at 4:02 AM, Thomas Gleixner wrote: > On Sat, 4 Oct 2008, Jiri Kosina wrote: >> On Fri, 3 Oct 2008, Jesse Brandeburg wrote: >> > Our experience is different. We are also testing with the "protection >> > patch" reverted. >> > We see that the problem specifically comes and goes when >> > removing/adding the use of set_memory_ro/set_memory_rw to the driver. >> >> But if this patch (which is an obvious workaround, compared to the other >> patches which fix real bugs, right?) would be catching some malicious >> accessess to the mapped EEPROM, there should be stacktraces present in the >> kernel log, right? yes, but I think it is just changing timing, i don't see any backtraces either. > Exactly. The access to a ro region results in a fault. I have nowhere > seen that trigger, but I can reproduce the trylock() WARN_ON, which > confirms that there is concurrent access to the NVRAM registers. The > backtrace pattern is similar to the one you have seen. are you still getting WARN_ON *with* all the mutex based fixes already applied? with the mutex patches in place (without protection patch) we are still reproducing the issue, until we apply the set_memory_ro patch. I had no luck on friday setting a hardware breakpoint on memory access with kgdb to catch the writer with a breakpoint.