Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754707Ab3IJH3O (ORCPT ); Tue, 10 Sep 2013 03:29:14 -0400 Received: from mail-bk0-f54.google.com ([209.85.214.54]:47786 "EHLO mail-bk0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754086Ab3IJH3N (ORCPT ); Tue, 10 Sep 2013 03:29:13 -0400 Date: Tue, 10 Sep 2013 09:29:09 +0200 From: Ingo Molnar To: John Stultz Cc: Gerlando Falauto , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Richard Cochran , Prarit Bhargava , "Brunck, Holger" , "Longchamp, Valentin" , "Bigler, Stefan" , Peter Zijlstra Subject: Re: kernel deadlock Message-ID: <20130910072908.GA32257@gmail.com> References: <521F6D06.1040107@keymile.com> <521FDD12.7050000@linaro.org> <52212511.9050206@keymile.com> <5221264F.4070402@linaro.org> <5225F8EF.3040701@keymile.com> <52261BBB.60904@linaro.org> <5226EB35.6080604@keymile.com> <522E2FBB.4070406@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <522E2FBB.4070406@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 30 * John Stultz wrote: > Now, I'm still in the dark as to why HRTICK exposes this, but seems like > the following patch should resolve the issue (and quiets the lockdep > warnings in my testing). Let me know how it works for you! > > Ingo: This makes me think we really should have some lockdep smarts > added to seqlock/seqcount structures. Is there something already > discovered thats preventing this, or has this just not yet been tried? There's no fundamental reason to not do it, it's a very good idea! > From 09885df9734aa678ccb61dbef356fea4faeff16c Mon Sep 17 00:00:00 2001 > From: John Stultz > Date: Mon, 9 Sep 2013 13:07:18 -0700 > Subject: [PATCH] timekeepeing: Fix HRTICK related deadlock from ntp lock changes Cool fix! I think I've seen this deadlock in various incarnations but was never able to track it down. Do you have a guesstimate about roughly when it was introduced? Is it an ancient bug? Thanks, 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/