Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758749AbXLLKph (ORCPT ); Wed, 12 Dec 2007 05:45:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757200AbXLLKp2 (ORCPT ); Wed, 12 Dec 2007 05:45:28 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:41870 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757477AbXLLKp1 (ORCPT ); Wed, 12 Dec 2007 05:45:27 -0500 Date: Wed, 12 Dec 2007 11:44:41 +0100 From: Ingo Molnar To: Nick Piggin Cc: Stefano Brivio , Robert Love , linux-kernel@vger.kernel.org, Dave Jones , "Rafael J. Wysocki" , Michael Buesch , Thomas Gleixner , Andrew Morton , Len Brown Subject: Re: [PATCH] scheduler: fix x86 regression in native_sched_clock Message-ID: <20071212104441.GC1611@elte.hu> References: <20071207021952.6f0ac922@morte> <200712081157.27840.nickpiggin@yahoo.com.au> <20071208085207.GE30997@elte.hu> <200712121542.45957.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200712121542.45957.nickpiggin@yahoo.com.au> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 31 * Nick Piggin wrote: > > the scariest bit is the adding of cpu_clock() to kernel/printk.c so > > late in the game, and the anti-recursion code i did there. Maybe > > because this only affects CONFIG_PRINTK_TIME we could try it even > > for v2.6.24. > > Printk recursion I guess shouldn't happen, but if there is a bug > somewhere in eg. the scheduler locking, then it may trigger, right? or we just crash somewhere. It's all about risk management - printk is crutial, and with more complex codepaths being touched in printk it might make sense to just add built-in recursion protection into printk via my patch. > Probably pretty rare case, however it would be nice to be able to find > out where the recursion comes from? Can you put an instruction pointer > in the recursion message perhaps? yeah, as i mentioned if this would be occuring in practice we can always save the stacktrace of the incident and output that. I opted for the simplest approach first. Thanks for your Reviewed-by, i've queued it up for 2.6.25. Ingo -- 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/