Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755482AbYHTBU1 (ORCPT ); Tue, 19 Aug 2008 21:20:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753278AbYHTBUQ (ORCPT ); Tue, 19 Aug 2008 21:20:16 -0400 Received: from gate.crashing.org ([63.228.1.57]:52566 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752868AbYHTBUO (ORCPT ); Tue, 19 Aug 2008 21:20:14 -0400 Subject: Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) From: Benjamin Herrenschmidt Reply-To: benh@kernel.crashing.org To: Jeremy Fitzhardinge Cc: Mathieu Desnoyers , Steven Rostedt , Scott Wood , Eran Liberty , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Steven Rostedt , "Paul E. McKenney" , Nick Piggin In-Reply-To: <48AB5E36.8030400@goop.org> References: <48A9901B.1080900@redhat.com> <20080818154746.GA26835@Krystal> <48A9AFA7.8080508@freescale.com> <1219110814.8062.2.camel@pasglop> <1219113549.8062.13.camel@pasglop> <20080819024707.GA22659@Krystal> <20080819173453.GA28239@Krystal> <1219182471.7826.16.camel@pasglop> <48AB5E36.8030400@goop.org> Content-Type: text/plain Date: Wed, 20 Aug 2008 11:17:28 +1000 Message-Id: <1219195048.7826.23.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 975 Lines: 28 On Tue, 2008-08-19 at 16:58 -0700, Jeremy Fitzhardinge wrote: > Benjamin Herrenschmidt wrote: > >> Ok, there are two cases where it's ok : > >> > >> 1 - in stop_machine, considering we are not touching code executed in > >> NMI handlers. > >> 2 - when using my replace_instruction_safe() which uses a temporary > >> breakpoint when doing the instruction replacement. > >> > >> In those cases you could use text_poke_early(). > >> > > > > Note that vmap/vunmap will be very slow. > > > > Don't we have Nick's speedups now? Not sure what speedups this is, but it's stlil not something you want to do a lot ... setting up and tearing down MMU mappings isn't something I'd like to see happening on a per-mcount basis. Ben -- 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/