From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id DD4F8DDF38 for ; Tue, 19 Aug 2008 11:57:01 +1000 (EST) Subject: Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) From: Benjamin Herrenschmidt To: Steven Rostedt In-Reply-To: <48A9901B.1080900@redhat.com> References: <48591941.4070408@extricom.com> <48A92E15.2080709@extricom.com> <48A9901B.1080900@redhat.com> Content-Type: text/plain Date: Tue, 19 Aug 2008 11:51:32 +1000 Message-Id: <1219110692.8062.0.camel@pasglop> Mime-Version: 1.0 Cc: "Paul E. McKenney" , Mathieu Desnoyers , linux-kernel@vger.kernel.org, rostedt@goodmis.org, linuxppc-dev@ozlabs.org, Eran Liberty Reply-To: benh@kernel.crashing.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2008-08-18 at 11:07 -0400, Steven Rostedt wrote: > Eran Liberty wrote: > > After compiling a kernel with ftrace I started to experience all sorts > > of crashes. > > Just to make sure... > > ftrace enables markers too, and RCU has tracing with the markers. This > may not be the problem, but I just want to eliminate as many variables > as possible. > Could you disable ftrace, but keep the markers on too. Also, could you > enable ftrace again and turn on the FTRACE_STARTUP_TEST. I spent some time last week tracking one of those crashes and it appears that we are getting corruption of some of the non-volatile registers. So far, I found out that it -seems- to be coming from stack frame corruption during a timer interrupt. I haven't had a chance to dig further yet. Cheers, Ben.